Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/01/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
935 PM MST THU AUG 29 2013
.UPDATE...UPDATED AVIATION DISCUSSION.
&&
.SYNOPSIS...
THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE
POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND
A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY
CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING
BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON
PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT
WEEK.
&&
.DISCUSSION...
CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED
IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA.
LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE
ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN
LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE
DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON
THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE
INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES
ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR
SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND
THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER
TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL
AREAS EXCEPT FOR AZZ024.
FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A
WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS
SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS
FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL
COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES
THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV
IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS
THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE
COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS
SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN
THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN
CONSIDERABLY ABOVE CLIMO.
&&
.PREVIOUS DISCUSSION...
FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN
AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW
MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY
MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND
ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES
SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING.
THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST
THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE
DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF
LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF
ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED
ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN
ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO
BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR
DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS
IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST
AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD
SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT
CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA.
TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT
HIGHS NEAR 100 BOTH DAYS.
NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO
NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER
CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW
THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS
BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES
COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER
DESERTS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
ISOLATED THUNDERSTORMS REMAIN A THREAT OVERNIGHT...THOUGH CHANCES
ARE CONSIDERABLY HIGHER ACROSS THE HIGHER TERRAIN EAST OF PHOENIX.
OTHERWISE...MID CLOUDS WILL PERSIST INTO FRIDAY WITH CIGS AROUND
12-15K FT. CONVECTION IS EXPECTED TO REDEVELOP FRIDAY AFTERNOON ACROSS
SOUTH-CENTRAL AZ...THOUGH IT REMAINS HIGHLY UNCERTAIN AS TO EXACTLY
WHERE/WHEN THIS WILL OCCUR. CONDITIONS REMAIN EXCEPTIONALLY MOIST SO
IT IS MORE LIKELY THAT LIGHTNING AND WET RUNWAYS WILL BE MORE A
FACTOR THAN WIND/DUST IMPACTS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
CONVECTION HAS ENDED ACROSS THE AREA...THOUGH THERE IS A SLIGHT
CHANCE THAT ADDITIONAL STORMS WILL AFFECT KBLH OVERNIGHT. FOR
FRIDAY...SHOWERS AND THUNDERSTORMS ARE GENERALLY EXPECTED TO REMAIN
WELL NORTH OF THE AREA AND ALONG THE PENINSULAR RANGES OF SOUTHERN
CA. TAF FORECAST IS CONSEQUENTLY WEIGHTED TOWARDS CLIMO.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE
MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC
NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL
STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND
ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY...
FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL
GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON
AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN
LOCATIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...KUHLMAN
AVIATION...HIRSCH
FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
900 PM MST THU AUG 29 2013
.SYNOPSIS...
THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE
POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND
A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY
CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING
BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON
PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT
WEEK.
&&
.DISCUSSION...
CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED
IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA.
LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE
ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN
LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE
DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON
THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE
INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES
ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR
SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND
THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER
TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL
AREAS EXCEPT FOR AZZ024.
FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A
WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS
SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS
FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL
COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES
THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV
IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS
THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE
COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS
SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN
THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN
CONSIDERABLY ABOVE CLIMO.
&&
.PREVIOUS DISCUSSION...
FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN
AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW
MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY
MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND
ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES
SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING.
THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST
THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE
DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF
LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF
ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED
ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN
ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO
BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR
DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS
IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST
AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD
SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT
CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA.
TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT
HIGHS NEAR 100 BOTH DAYS.
NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO
NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER
CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW
THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS
BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES
COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER
DESERTS.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
ABUNDANT MOISTURE AVAILABLE FOR SHOWERS TO OCCUR JUST ABOUT
ANYWHERE. HOWEVER...AREAS WHERE MORE SUNSHINE REACHES THE GROUND
WILL HAVE BETTER INSTABILITY. AS OF 18Z THOSE AREAS WOULD INCLUDE
NORTHWEST MARICOPA COUNTY...LA PAZ COUNTY...AND YUMA COUNTY. AN
ADDITIONAL FACTOR FOR SHWR/TSTM PRODUCTION WILL BE A CIRCULATION
CENTERED NEAR NORTHERN BAJA MEXICO. MODELS INDICATE A SWATH OF
ENHANCED LIFT FOR THIS AFTERNOON AND EVENING...ASSOCIATED WITH THE
BAJA FEATURE...ACROSS SOUTHWEST MARICOPA COUNTY...YUMA COUNTY...AND
IMPERIAL COUNTY. FOR THE ABOVE REASONS...INCLUDED TEMPO SHWRS/TSTMS
IN THE TAFS. EVEN WITHOUT A FULL FLEDGED TSTM...CEILINGS AND
VISIBILITY WILL BE LOWERED SUBSTANTIALLY BY ANY RAIN SHOWERS. OF
NOTE...THERE IS CONSIDERABLE UNCERTAINTY IN THE TIMING AND EXTENT OF
THE ABOVE MENTIONED FACTORS INFLUENCING THE CONVECTION. WINDS WILL
FAVOR SOUTHWEST DIRECTIONS OVER THE PHOENIX AREA AND SOUTH/SOUTHEAST
DIRECTIONS OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE
MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC
NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL
STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND
ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY...
FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL
GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON
AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN
LOCATIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...KUHLMAN
AVIATION...AJ
FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1126 AM MDT FRI AUG 30 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM MDT FRI AUG 30 2013
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE
UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF
STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA
INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL
AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING
ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO
REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE
MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S
ACROSS THE LOWER ELEVATIONS AT THIS TIME.
TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH
TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE
NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN
UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON
AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL
MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER
DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER
RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE
AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING
CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT
MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER
QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD
COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN
YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN
2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD
AT PUB OF 102F IN 1990 LOOKS SAFE.
CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY
DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE
SEASONAL AVERAGES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 402 AM MDT FRI AUG 30 2013
...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO
MOST AREAS THIS WEEKEND...
MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL
DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND
EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING
MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN
FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING
ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE
PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF
FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS
FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS
WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL.
ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE
FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS
FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS
SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE
PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN
POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS
PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER
ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE
PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE...
KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY
IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE
TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO
THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY.
NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND
RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN
CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH
DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS.
SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES...
BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE
HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING
ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL
OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON
PLUME. LW
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1000 AM MDT FRI AUG 30 2013
VFR CONDITIONS EXPECTED AT THE TAF SITES TODAY WITH ISOLATED
THUNDERSTORMS EXPECTED TO DEVELOP OVER THE MOUNTAINS AROUND 17Z.
KALS HAS THE BEST CHANCE FOR SEEING VCTS...HOWEVER THERE IS SOME
CHANCE THAT KCOS COULD AS WELL. WILL CARRY VCTS IN KALS TAF FOR
NOW AND MONITOR LATEST RADAR TRENDS FOR POSSIBLE INCLUSION IN
KCOS. GUSTY ERRATIC WINDS WILL BE THE MAIN THREATS WITH
THUNDERSTORMS ALONG WITH LIGHTNING. SOME BRIEF MODERATE TO HEAVY
RAINFALL WILL BE POSSIBLE WITH STORMS ALONG THE CONTINENTAL DIVIDE
THIS AFTERNOON AND EVENING. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...LW
AVIATION...KT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
454 AM MDT FRI AUG 30 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 453 AM MDT FRI AUG 30 2013
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE
UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF
STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA
INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL
AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING
ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO
REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE
MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S
ACROSS THE LOWER ELEVATIONS AT THIS TIME.
TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH
TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE
NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN
UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON
AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL
MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER
DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER
RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE
AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING
CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT
MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER
QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD
COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN
YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN
2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD
AT PUB OF 102F IN 1990 LOOKS SAFE.
CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY
DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE
SEASONAL AVERAGES.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 402 AM MDT FRI AUG 30 2013
...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO
MOST AREAS THIS WEEKEND...
MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL
DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND
EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING
MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN
FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING
ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE
PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF
FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS
FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS
WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL.
ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE
FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS
FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS
SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE
PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN
POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS
PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER
ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE
PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE...
KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY
IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE
TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO
THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY.
NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND
RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN
CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH
DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS.
SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES...
BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE
HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING
ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL
OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON
PLUME. LW
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 402 AM MDT FRI AUG 30 2013
VFR CONDITIONS EXPECTED FOR THE NEXT 24 HRS AT COS...PUB AND ALS
WITH LARGE UPPER HIGH IN PLACE ACROSS THE HIGH PLAINS THROUGH THE
ROCKIES. ENOUGH MOISTURE REMAINS IN PLACE UNDER RIDGE FOR ISOLATED
TO SCATTERED -TSRA OVER AND NEAR THE MOUNTAINS THIS AFTERNOON AND
EVENING. BEST COVERAGE OF TSRA EXPECTED ACROSS THE CONTDVD THOUGH
LOOKS TO BE BETTER COVERAGE OF STORMS ACROSS THE PIKES PEAK REGION
THAN YESTERDAY. STILL TOO LOW OF A CHANCE TO INCLUDE IN TAFS AT THIS
TIME.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...LW
AVIATION...MW
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1015 PM MDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 242 PM MDT THU AUG 29 2013
SHOWERS AND STORMS DEVELOPED AS EXPECTED AROUND 18Z OVER THE FAVORED
HIGHER TERRAIN AREAS PARTICULARLY THE ABAJOS...SAN JUANS...AND
FLATTOPS. THE 12Z GJT SOUNDING SHOWED PW VALUES OF 0.95 INCHES
WHICH IS MATCHING UP QUITE WELL WITH THE RAP AND THE NAM MODELS.
THE GFS PWATS WERE MUCH LOWER SO THINKING THE GFS IS UNDERPLAYING
THE AMT OF MOISTURE. WITH HIGH PRESSURE OVERHEAD...LIGHT STEERING
FLOW WILL LEAD TO STORMS STAYING RELATIVELY ANCHORED TO THE
TERRAIN WITH LITTLE MOVEMENT. SIMILAR PATTERN TO YESTERDAY...SO
EXPECT MUCH OF THE SAME WITH CONVECTION ENDING SHORTLY AFTER
SUNSET AND SOME STORMS LINGERING TILL MIDNIGHT. BIGGEST CONCERN
FOR THE REST OF THIS AFTERNOON INTO THE EVENING IS ANY STORMS THAT
FORM OVER ALREADY SATURATED AREAS...ESPECIALLY THE SAN JUANS WHERE
FLOODING OCCURRED YESTERDAY IN OURAY AND OVER RED MOUNTAIN PASS.
THE 12Z NAM SEEMS TO BE HANDLING THE MOISTURE BETTER THAN THE GFS SO
LEANING TOWARDS IT FOR FRIDAY. PW VALUES STAY RELATIVELY THE SAME
AT 0.9 INCHES ACROSS MUCH OF WESTERN COLORADO. HOWEVER PWATS
INCREASE SOME OVER SE UTAH...WITH SOME OF THE DEEPER MOISTURE
ASSOCIATED WITH THE INVERTED TROUGH OVER AZ AND SOCAL CREEPING INTO
SE UTAH WHERE PWATS INCREASE TO A LITTLE OVER AN INCH. AN ACTIVE
NORTHERN STREAM CAUSES THE RIDGE TO FLATTEN A LITTLE WHICH LAYS A
55KT JET MAX OVER THE CO-WY BORDER. IN ADDITION TO THIS...850-700MB
STREAMLINES SHOW A LOW LEVEL CONVERGENCE SIGNATURE THAT MOVES
THROUGH SE UTAH AND SW COLORADO FRIDAY AFTERNOON...WITH UPPER LEVEL
DIVERGENCE AS INDICATED IN DIVQ FIELDS. THINKING THAT FRIDAY MAY BE
A LITTLE MORE ACTIVE AND WIDESPREAD IN TERMS OF CONVECTION AS THERE
IS SOME LOW LEVEL AND UPPER LEVEL SUPPORT AND SEVERAL STRONG VORT
MAXES THAT MOVE THROUGH THE FLOW THAT CAN ACT AS A TRIGGER ON THE
MOISTURE. THINK THERE WILL BE ENOUGH SFC HEATING TO GET THINGS
GOING AGAIN AS SKIES BEGIN RELATIVELY CLEAR FRIDAY MORNING.
CONVECTION WILL BEGIN FRIDAY AFTERNOON OVER THE HIGHER TERRAIN WITH
SOME STORMS FORMING OVER THE VALLEYS LATER IN THE DAY AS
DISTURBANCES AND BOUNDARIES INTERACT GIVEN THE ADDITIONAL FORCING.
THINGS SHOULD WIND DOWN AFTER SUNSET AGAIN WITH SOME STORMS
LINGERING UNTIL MIDNIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 242 PM MDT THU AUG 29 2013
THE UPPER RIDGE STAYS CENTERED OVER THE FOUR CORNERS ON SATURDAY FOR
ANOTHER DAY OF MAINLY AFTERNOON THUNDERSTORMS OVER ELEVATED
LOCATIONS AS SUFFICIENT 0.60 TO 1.00 PWATS REMAIN TRAPPED UNDER
THE RIDGE...WITH THE DRIEST IN NORTHERN AREAS. THINKING THAT THE
NORTHERN UT/CO BORDER WILL SEE SOME BETTER ORGANIZED/LONGER LIVING
STORMS DESPITE THE LOWER BUT STILL GOOD ENOUGH AVAILABLE MOISTURE
SATURDAY AS THE MODELS INDICATE A MODERATE 40-50 KT SPEED MAX AT
250 MB. SE UTAH AND THE SAN JUANS OF COLORADO WILL REMAIN THE MOST
LIKELY LOCATION FOR STORM DEVELOPMENT WITH HEAVY RAIN AS THE
BIGGEST THREAT. IN SOUTHERN AREAS WITH LOW SHEER...CELLS WILL LIKELY BE
SHORT-LIVED BUT COULD CAUSE INTENSE HEAVY RAINFALL IN LOCALIZED
AREAS WITHIN A SHORT PERIOD OF TIME. A FEW OF THESE STORMS MAY
SURVIVE PAST SUNSET BUT OTHERWISE ARE EXPECTED TO DIMINISH AFTER
DARK. A VORT MAX AXIS WILL LIE NW TO SE ACROSS OUR AREA AND HELP
WITH STORM DEVELOPMENT AS WELL.
DISCREPANCY OVER THE WEEKEND ON THE AMOUNT OF MOISTURE WHICH WILL
REMAIN AVAILABLE BUT OVERALL TRENDS ARE SHOWING A SIMILAR
PATTERN.
SUNDAY IS EXPECTED TO BE SLIGHTLY DRIER UP ALONG THE WYOMING
BORDER WITH OUR CWA DUE TO DRY AIR ADVECTION KICKING INTO THE
REGION FROM THE NORTHWEST AND MINIMAL FORCING ALOFT...THEREFORE POPS
ARE AMPLIFIED TO THE SOUTHERN HALF OF OUR AREA. THIS IS NOT
EXPECTED TO LAST LONG AND WILL LIKELY KEEP A SECTION OF THE
NORTHERN REGION RAIN-FREE ON SUNDAY. ELSEWHERE...ESPECIALLY DOWN
IN THE SAN JUANS...ABAJOS...AND LA SALS...THE ATMOSPHERE WILL
REMAIN JUICY AND ALLOW FOR STRONG DIURNAL TSTORMS IN THE AFTERNOON.
MONDAY THROUGH WEDNESDAY...UPPER LEVEL HIGH PRESSURE STAYS POSITIONED
OVER COLORADO THROUGHOUT THE PERIOD. MONSOONAL MOISTURE CONTINUES
TO STREAM AROUND THE WRN PERIPHERY OF THE HIGH ALLOWING FOR DAILY
STORM INITIATION. SHORTWAVE ON TUESDAY SLICING THROUGH THE CENTER
OF THE HIGH PRESSURE WILL ALLOW FOR ENHANCED ACTIVITY ASSUMING
SKIES REMAIN FAIRLY CLEAR DURING THE FIRST HALF OF THE DAY.
THURSDAY COULD GET INTERESTING...BUT THIS FAR OUT THERE IS VERY
LOW CONFIDENCE IN THE LONG TERM MODELS...ESPECIALLY WITH TWO VERY
DIFFERENT SOLUTIONS. THE GFS IS PROGGING A STRONG PACIFIC LOW TO
DROP DOWN INTO THE INTERMOUNTAIN WEST THURSDAY SWIPING WITHIN NEAR
REACH OF THE REGION...FILTERING UNSEASONALLY COOL AIR INTO NORTHERN
BREACHES OF THE CWA. THE EURO KEEPS THIS FEATURE ALONG THE
NORTHERN ROCKIES WITHOUT MUCH INTERACTION WITH COLORADO AND UTAH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1015 PM MDT THU AUG 29 2013
VFR CONDITIONS WILL CONTINUE AT ALL TAFS SITES OVERNIGHT.
SCATTERED SHOWERS WILL SLOWLY DISSIPATE OVER THE CENTRAL CO
MOUNTAINS IN THE KASE AND VAIL PASS VICINITIES...WITH LOCAL
MOUNTAIN OBSCURATIONS THROUGH ABOUT 09Z. FRIDAY AFTERNOON ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP AGAIN OVER THE
CO CENTRAL AND SOUTHWEST MOUNTAINS...WITH BRIEF MVFR VSBYS IN
STRONGER RAIN SHOWERS AT KASE...KEGE...KRIL AND KTEX.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...MDA
LONG TERM...JAM
AVIATION...CC
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 PM EDT FRI AUG 30 2013
.AVIATION...
A WEAK UPPER LOW COMBINED WITH DAYTIME HEATING AND SEA BREEZES
WILL MAINTAIN A SLIGHT CHANCE FOR SHOWERS AND STORMS ACROSS THE
LOCAL AREA THROUGH THE EVENING HOURS TODAY. THE LATEST HRRR MODEL
RUN INDICATES THE BULK OF THIS ACTIVITY REMAINING INLAND OF THE
TAF SITES THROUGH THIS TIME. CONDITIONS SHOULD TREND DOWN THROUGH
OVERNIGHT HOURS WITH THE BEST RAIN CHANCES REMAINING OVER THE
ADJACENT MARINE AREAS THROUGH SATURDAY MORNING. WINDS WILL BECOME
CALM OVERNIGHT ACROSS THE AREA. SIMILAR CONDITIONS ARE ANTICIPATED
SATURDAY WITH ONSHORE WINDS THROUGH THE LATE MORNING AND AFTERNOON
PERIODS. THE BEST RAIN CHANCES WILL REMAIN INLAND OF THE SITES.
&&
.PREV DISCUSSION... /ISSUED 932 AM EDT FRI AUG 30 2013/
UPDATE...A MID-UPPER LEVEL LOW CONTINUES OVER SOUTH FL AS SEEN IN
WATER VAPOR IMAGERY. A COMPLEX OF THUNDERSTORMS IS OCCURRING OVER
THE FLORIDA STRAITS...DRIVEN BY A VORT LOBE TRAVERSING THE
SOUTHERN SIDE OF THIS UPPER LEVEL LOW. THIS VORT WILL MOVE NE
AND ACROSS THE BAHAMAS TODAY, KEEPING ORGANIZED CONVECTION TO OUR
EAST. HOWEVER, LATEST RADAR IMAGERY SHOWS AN OUTFLOW BOUNDARY
ORIGINATING FROM THIS CONVECTION MOVING NORTH AT 25 KNOTS...NOW
LOCATED EAST OF THE MIDDLE TO UPPER KEYS. THIS COULD BRING A BRIEF
PERIOD OF RAIN TO FAR SE MIAMI-DADE COUNTY AND THE ADJACENT WATERS
IF IT HOLDS. HOWEVER, AM EXPECTING A DISSIPATING TREND AS IT
ENCOUNTERS DRY LOW LEVEL AIR IN PLACE OVERHEAD. THE MIAMI SOUNDING
THIS MORNING SHOWED UNUSUALLY DRY AIR IN THE 1-10K FT LAYER. THIS
SHOULD ACT TO LIMIT AND DIMINISH ACTIVITY INCOMING FROM THE
SOUTHEAST. HAVE PLACED CHANCE POPS SE MIAMI-DADE COUNTY FOR THE
POSSIBILITY OF AT LEAST SOME RAIN MAKING IT IN THERE OVER THE NEXT
FEW HOURS. THE REST OF THE FORECAST LOOKS GOOD WITH TSTORMS
FOCUSING ACROSS THE LAKE REGION LATER THIS AFTERNOON. SEE
PREVIOUS DISCUSSION BELOW FOR FURTHER FORECAST DETAILS BEYOND
TODAY. /GREGORIA
PREV DISCUSSION... /ISSUED 644 AM EDT FRI AUG 30 2013/
AVIATION...
WITH A DRY, WEAK UPPER LEVEL LOW ALMOST DIRECTLY OVER SOUTH
FLORIDA, FAIRLY QUIET VFR CONDITIONS AREA EXPECTED THROUGH THE DAY
TODAY. THE EXCEPTION MAY BE A BRIEF PASSING SHOWER. HOWEVER,
CONFIDENCE IS LOW ON ANY TAF SITES BEING AFFECTED BY ANY SHOWERS,
AND WHAT SHOWERS DO DEVELOP WILL MOST LIKELY BE BRIEF. THE MOST
LIKELY AREA TO SEE ACTIVITY IS KPBI. THE MAIN AREA TO SEE ANY
CONVECTIVE ACTIVITY WILL BE IN THE INTERIOR AREA, CLOSER TO LAKE
OKEECHOBEE. THERE IS A CHANCE OF THUNDERSTORMS IN THAT AREA AS
WELL. THUS, HAVE LEFT ANY MENTION OF SHOWERS OR THUNDERSTORMS OUT
OF THE TAFS AT THIS TIME.
LIGHT AND VARIABLE WINDS WILL PERSIST INTO THE MID DAY. AROUND 18Z
THEY ARE EXPECTED TO PICK UP OUT OF THE SE BETWEEN 5 AND 10 KTS.
THEY WILL BECOME LIGHT AND VARIABLE ONCE AGAIN THIS EVENING.
PREV DISCUSSION... /ISSUED 308 AM EDT FRI AUG 30 2013/
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE FOR
THE HOLIDAY WEEKEND...
SHORT TERM...
AN UPPER LEVEL LOW WILL REMAIN OVER SOUTH FLORIDA TODAY INTO
SATURDAY...AS WEAK HIGH PRESSURE REMAINS OVER THE WESTERN
ATLANTIC WATERS. THIS WILL ALLOW FOR A STEERING FLOW OVER SOUTH
FLORIDA TO BE FROM THE SOUTHERLY DIRECTION WHICH WILL FOCUS THE
SHOWER AND THUNDERSTORM ACTIVITY OVER THE LAKE OKEECHOBEE REGION
TODAY AND AGAIN ON SATURDAY.
THERE IS ALSO SOME DRY AIR LOCATED BETWEEN 850 MB AND 700 MB IN
THE 00Z MIA SOUNDING. THIS DRY AIR WILL REMAIN IN PLACE TODAY INTO
SATURDAY HELPING TO REDUCE THE SHOWER AND THUNDERSTORM ACTIVITY
OVER SOUTH FLORIDA.
THEREFORE...THE POPS OVER SOUTH FLORIDA WILL RANGE FROM 20 PERCENT
OVER THE SOUTHERN AREAS TO 40 PERCENT OVER THE LAKE OKEECHOBEE
AREA FOR TODAY AND AGAIN ON SATURDAY. THE THUNDER THREAT WILL ALSO
BE LIMITED TO THE NORTHERN AREAS OF SOUTH FLORIDA FOR TODAY INTO
SATURDAY WHERE THE SEA BREEZES AND LAKE BREEZE COLLIDE.
THE UPPER LEVEL LOW SHOULD MOVE NORTHEAST LATE THIS LABOR DAY
WEEKEND INTO THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR THE
DRY AIR BETWEEN THE 700 MB AND 850 MB TO MOISTEN UP ALONG WITH
THE STEERING FLOW BECOMING MORE SOUTHEAST. THE SEA BREEZES WILL
ALSO DEVELOP EACH DAY AND PUSH INLAND. SO THE POPS WILL BE
INCREASED TO SCATTERED COVERAGE WITH THE HIGHEST POPS OVER THE
INTERIOR AREAS.
LONG TERM...
THE HIGH OVER THE WESTERN ATLANTIC WATERS SHOULD STRENGTHEN LATE
NEXT WEEK OVER THE WESTERN ATLANTIC WATERS AND EXTEND INTO THE
FLORIDA PENINSULA. THIS WILL ALLOW FOR THE EASTERLY WIND FLOW TO
REMAIN IN PLACE OVER SOUTH FLORIDA LATE NEXT WEEK ALONG WITH THE
DAILY SEA BREEZE DEVELOPMENT. SO WILL CONTINUE THE SCATTERED POPS
OVER SOUTH FLORIDA WITH THE BEST COVERAGE OVER THE INTERIOR AREA
FOR LATE NEXT WEEK.
THERE IS ALSO A TROPICAL WAVE OVER THE CENTRAL ATLANTIC WATERS
THAT IS FORECAST BY THE MODELS TO MOVE WEST-NORTHWEST NEXT WEEK
AND POSSIBILITY OVER SOUTH FLORIDA BY END OF NEXT WEEK. IF THIS
TREND CONDITIONS THEN THE POPS MAY HAVE TO BE RAISED UP FOR NEXT OF
NEXT WEEK.
MARINE...
THE WINDS OVER SOUTH FLORIDA WATERS THIS LABOR DAY WEEKEND WILL BE
FROM THE WEST TO SOUTHWEST DIRECTION AT 5 TO 10 KNOTS SWINGING TO
A EASTERLY DIRECTION BY LABOR DAY. THIS WILL KEEP THE SEAS IN BOTH
THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING
CONDITIONS OVER SOUTH FLORIDA THIS LABOR DAY WEEKEND SHOULD BE
GOOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS.
THE THREAT OF RIP CURRENTS THIS LABOR DAY WEEKEND AT BOTH THE
ATLANTIC AND GULF COAST BEACHES OF SOUTH FLORIDA LOOKS LOW AT
THIS TIME AS THE WINDS WILL BE 10 KNOTS OR LESS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 77 90 / 20 30 20 40
FORT LAUDERDALE 78 89 79 89 / 10 20 20 30
MIAMI 77 90 78 90 / 10 20 20 30
NAPLES 74 89 75 89 / 10 20 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...57/DG
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS MIAMI FL
201 AM EDT FRI AUG 30 2013
.AVIATION...
WITH A DRY, WEAK UPPER LEVEL LOW OVER SOUTH FLORIDA, CONDITIONS
WILL BE MOSTLY QUIET FOR ANOTHER DAY, AS MOST CONVECTION WILL BE
INLAND FROM THE TAF SITES. CONDITIONS SHOULD REMAIN VFR TODAY,
ALTHOUGH THERE COULD BE STRAY SHOWER THAT BRIEFLY IMPACTS
CONDITIONS, BUT GIVEN THE LOW CONFIDENCE IN THIS, HAVE KEPT MENTION
OUT OF THE TAFS FOR TODAY. WINDS WILL BE LIGHT AND VARIABLE
THROUGH EARLY AFTERNOON, THEN BECOME SOUTHEAST BETWEEN 5 AND 10
KTS, GOING LIGHT AND VARIABLE ONCE AGAIN THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 858 PM EDT THU AUG 29 2013/
UPDATE...
A FEW CHANGES WERE MADE TO THE SHORT TERM FORECAST...DUE TO THE
LACK OF ACTIVITY THIS AFTERNOON AND EVENING. THE ONLY AREA THAT
REMAINED ACTIVE WITH SOME SHOWERS AND THUNDERSTORMS WAS AROUND THE
LAKE...AND NOW A FEW SHOWERS DEVELOPED FROM OUTFLOW BOUNDARIES
COLLISIONS ACROSS INTERIOR MIAMI-DADE COUNTY. ALL THIS ACTIVITY
WILL DISSIPATE QUICKLY AS THE NIGHT PROGRESSES. CURRENT GUIDANCE
CONTINUES SHOWING THE STALLED UPPER LEVEL LOW OVER THE WESTERN
HALF OF SOUTH FLORIDA THROUGH THE WEEKEND. THEREFORE...SIMILAR
WEATHER CONDITIONS ARE EXPECTED THROUGH THE HOLIDAY WEEKEND.
PREV DISCUSSION... /ISSUED 308 PM EDT THU AUG 29 2013/
SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
SHORT TERM...THROUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF SHOWERS
AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS STILL AN OFF
CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING GUSTY WINDS AND
LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND LOCAL HIGH RES
MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 75 90 78 / 30 20 30 20
FORT LAUDERDALE 91 78 90 81 / 30 20 30 20
MIAMI 92 77 90 79 / 30 20 30 20
NAPLES 91 74 90 75 / 30 20 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...17/ERA
AVIATION/RADAR...13/SI
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
734 PM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH
FLOW INTO THE FORECAST AREA THROUGH SUNDAY. A COLD FRONT WILL
MOVE INTO THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SOME SHOWER AND THUNDERSTORM ACTIVITY OVER OUR CENTRAL FA...WITH
SCATTERED THUNDERSTORMS ACROSS THE WESTERN CAROLINAS ALONG A WEAK
SURFACE TROUGH...DRIFTING SE. QUESTION AS TO HOW FAR SOUTH THIS
ACTIVITY WILL GET. LATEST HRRR APPEARS TO BRING SOME OF IT INTO OUR
NORTHERN FA BY WHILE INDICATING SLOW WEAKENING OF THE ACTIVITY. WILL
MAINTAIN HIGHER POPS NORTHERN FA THROUGH THIS EVENING.
TONIGHT...HIGH-LOW LEVEL MOISTURE AND DRY AIR ALOFT SHOULD RESULT
IN CONSIDERABLE STRATUS AND OR FOG LATE TONIGHT. TEMPERATURES NEAR
MOS CONSENSUS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
WV LOOP SHOWS RIDGE OF HIGH PRESSURE ANCHORED ACROSS THE FOUR
CORNERS REGION. THE MODELS HINT AT A WEAK CONVERGENCE AREA/TROUGH
ACROSS THE PIEDMONT THAT WILL LINGER ACROSS THE PIEDMONT/MIDLANDS
THROUGH MONDAY. MODEL TIME SECTIONS INDICATE INCREASING MOISTURE
THROUGH THE PERIOD. THERE WILL BE A SERIES OF SHORTWAVES THAT WILL
DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THIS
ALONG WITH THE EXPECTED COLD FRONT ARRIVING INTO THE REGION ON
TUESDAY. MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS
THROUGH MONDAY NIGHT. BEST CHANCE FOR SHOWERS/THUNDERSTORMS
APPEARS TO BE WITH FRONT ON TUESDAY. GUIDANCE NUMBERS SHOWING
QUITE A RANGE FOR DAYTIME HEIGHTS BUT REASONABLY CLOSE. HAVE
STAYED CLOSE TO A CONSENSUS OF THE GUIDANCE WHICH IS CLOSE TO
CLIMATOLOGY FOR HIGHS AND ABOVE CLIMO FOR LOWS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE MODELS SHOW SOME DRYING BEHIND THE FRONT FOR TUESDAY NIGHT
THROUGH THURSDAY BUT THE FRONT DOES APPEAR TO STALL JUST SOUTH
AND EAST OF THE AREA. THE MODELS DISPLAY A MOISTURE INCREASE FOR
FRIDAY AS ANOTHER SHORTWAVE/SURFACE FRONT APPROACHES FROM THE NW.
THE GFS ENSEMBLE MEANS SUPPORT TEMPERATURES NEAR CLIMATOLOGY FOR
TEMPERATURES. POPS DIMINISHING TUESDAY NIGHT BEHIND THE COLD
FRONT. NEXT CHANCE FOR PRECIPITATION APPEARS TO BE FRIDAY AND
SATURDAY.
&&
.AVIATION /00Z SUNDAY THROUGH FRIDAY/...
MAINLY VFR THIS EVENING. SCATTERED THUNDERSTORMS WILL CONTINUE
ACROSS THE REGION THROUGH AROUND 04Z. MVFR OR LOWER CONDITIONS
DUE TO LOW CEILING AND OR FOG AFTER 06Z...MORE LIKELY TOWARD 12Z.
IMPROVING CONDITIONS TO VFR BY 15Z. DIURNALLY DRIVEN SCATTERED
CONVECTION EXPECTED SUNDAY AFTERNOON.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
331 AM CDT FRI AUG 30 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
//PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK.
* SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z.
* PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE
WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A
REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME
IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF
GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS
WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING
AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF
SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A
SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED
UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL
BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS
EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA.
IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL
PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z.
CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL
FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN
CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK
SAT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT.
* LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN.
* MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
321 AM CDT
A SERIES OF FRONTAL BOUNDARIES WILL TRAVERSE LAKE MICHIGAN OVER
THE NEXT FEW DAYS. PATCHY FOG WILL LINGER THROUGH EARLY THIS
MORNING...AND SHOULD DISSIPATE BY MID MORNING.
FOR TODAY A SOUTHWEST FLOW WILL INCREASE WITH WINDS PUSHING TO 15
TO 25 KT ACROSS THE NORTHERN HALF OF THE LAKE...WHICH WILL QUICKLY
BUILD WAVES FOR THE NORTHERN PORTIONS. THEN A FRONTAL BOUNDARY
WILL STEADILY PUSH SOUTH ACROSS THE LAKE...WITH WINDS VEERING TO
NORTHWEST THEN NORTH. THIS WILL ALLOW A PERIOD OF BETTER FETCH FOR
THE SOUTHERN HALF AND BUILDING WAVES FOR SATURDAY. THE GRADIENT
WILL TIGHTEN BEHIND THE BOUNDARY AND WAVES SHOULD EASILY BUILD TO
4 TO 6 FT SATURDAY...HOWEVER THIS APPEARS TO BE A NARROW WINDOW AS
HIGH PRESSURE WILL PUSH OVER THE LAKE AND LINGER UNTIL SUNDAY
MORNING. WHICH WILL ALLOW WAVES TO SUBSIDE BRIEFLY SUNDAY. THEN
ANOTHER COLD FRONT WILL ARRIVE SUNDAY NIGHT...WHICH WILL BRING
COOLER AIR OF THE WARMER LAKE FOR MONDAY. THE RESULT WILL LIKELY
BE A PERIOD OF GUSTY WINDS...WITH BUILDING WAVES FOR MONDAY. BASED
ON THE CURRENT FORECAST...MONDAY COULD PRODUCE SMALL CRAFT
HEADLINES FOR THE ILLINOIS/INDIANA NEARSHORE WATERS AS WINDS WILL
BE NORTHERLY FOR A PROLONGED PERIOD AND GUSTY...ALONG WITH THE
COOLER AIR FLOWING OVER THE WARMER LAKE.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1256 AM CDT FRI AUG 30 2013
.DISCUSSION...
942 PM CDT
THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT
MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE
SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE
LAKE MI SHORE NAMELY FOR OVERNIGHT.
THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO
EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER
THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY
7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A
RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25
MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO
DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH
DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE
DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR
SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF
THIS ALREADY AT A HANDFUL OF LOCATIONS.
WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST
TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH
FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND
MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT
CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY
MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG
WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST
OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY
EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE
LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME
OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT.
HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY
LOOK ON TRACK.
EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF
SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID-
EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST
IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR
ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN
PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT.
MTF
//PREV DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK.
* SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z.
* PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE
WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A
REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME
IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF
GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS
WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING
AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF
SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A
SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED
UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL
BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS
EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA.
IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL
PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z.
CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL
FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN
CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK
SAT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT.
* LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN.
* MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR. WX NIL.
SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE
BRIEF LOCAL MVFR/IFR.
MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX.
TRS
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
703 PM CDT SAT AUG 31 2013
.SYNOPSIS...
ISSUED AT 223 PM CDT SAT AUG 31 2013
WEAK LOW PRESSURE OVER WEST CENTRAL IL EARLY THIS AFTERNOON. HOT
AND HUMID CONDITIONS WERE FOUND NEAR THE LOW WITH LOW TO MID 90
TEMPERATURES AND DEW POINTS IN THE LOW 70. IN THE LOW EASTERLY
FLOW NORTH OF THE LOW TEMPERATURES WERE COOLER BUT DEWPOINTS WERE
STILL AROUND 70. A COLD FRONT OVER THE NORTHERN PLAINS WAS THE
LEADING EDGE OF COOL DRY AIR MASS. EARLY AFTERNOON TEMPERATURES
OVER WESTERN NORTH DAKOTA WERE IN THE 70S WITH DEW POINTS IN THE 50S.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 223 PM CDT SAT AUG 31 2013
THIS FORECAST PERIOD WILL SEE A TRANSITION TO A MUCH MORE
COMFORTABLE AIRMASS BY LATE SUNDAY AFTERNOON AS THE NORTHERN
PLAINS FRONT MOVES THROUGH THE REGION. RAIN CHANCES WILL ACCOMPANY
THE FRONT BUT AT THIS TIME...COVERAGE LOOKS SCATTERED AT BEST.
FOR TONIGHT THE AREA OF LOW PRESSURE OVER WEST CENTRAL IL WILL BE
THE FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND
THIS EVENING. IT APPEARS THAT THE DEVELOPMENT WILL TAKE PLACE JUST
EAST OF THE FORECAST AREA BASED CURRENT SATELLITE IMAGERY. HOWEVER
WITH AN UPSTREAM VORT...OVER NORTHWEST IL... EXPECT TO MOVE
THROUGH NORTHERN MO AND VERY UNSTABLE AIR STILL OVER THE SOUTHERN
COUNTIES...A LOW POP WAS MAINTAINED FOR THE EARLY EVENING HOURS.
WINDS WILL REMAIN LIGHT OVERNIGHT AND WITH THE HIGH DEWPOINTS
STILL IN PLACE WE COULD SEE SOME PATCHY FOG LATE ESPECIALLY EAST
OF THE MISSISSIPPI RIVER.
THE NORTHERN PLAINS COLD FRONT IS EXPECTED TO REACH THE NORTHWEST
CWA BY EARLY SUNDAY MORNING AND WILL EXIT THE EASTERN COUNTIES
DURING THE EARLY AFTERNOON. THE BETTER FORCING WITH THIS SYSTEM
WILL STAY OVER THE GREAT LAKES...BUT THE MODELS ARE SHOWING SOME
UPPER DIFFLUENCE AHEAD OF THE S/W MOVING OVER THE AREA WITH THE
COLD FRONT. THERE WILL ALSO BE OF NARROW THETAE RIDGE WITH THE
BOUNDARY AND STEEPENING MID LEVEL LAPSE RATES WHICH SHOULD BE
ENOUGH FOR SCATTERED STORMS AS THE FRONT MOVES THROUGH. COVERAGE
OF THE STORMS SHOULD INCREASE AS THE FRONT MOVES ACROSS THE
MISSISSIPPI RIVER WHERE THE AIRMASS HAS A CHANCE TO DESTABILIZE
DURING THE MORNING. THE THREAT OF SEVERE STORMS WILL BE LOW ON
SUNDAY DUE TO THE EARLY DAY FROPA AND WEAK DEEP LAYER SHEAR.
THE HIGH LOW LEVEL MOISTURE WILL KEEP MIN TEMPS IN THE MID 60S TO
AROUND 70 TONIGHT. HIGHS SUNDAY WILL STILL BE ON THE WARM SIDE
TOPPING OUT AROUND 90 SOUTH TO THE MID 80S IN THE NORTH...BUT WE
SHOULD SEE DEW POINTS COME DOWN A LITTLE...ESPECIALLY WEST OF THE
MISSISSIPPI RIVER.
DLF
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 223 PM CDT
SAT AUG 31 2013
ANY LINGERING RAIN ACROSS THE SOUTHEAST THIRD OF THE CWFA SUNDAY
EVENING WILL END SHORTLY AFTER SUNSET.
HIGH PRESSURE WILL MOVE ACROSS THE MIDWEST SUNDAY NIGHT THROUGH
TUESDAY RESULTING IN DRY BUT PLEASANT CONDITIONS. TEMPERATURES
SHOULD AVERAGE CLOSE TO NORMAL.
TUESDAY NIGHT ON...
NORTHWEST FLOW ALOFT WILL PERSIST THROUGH NEXT WEEKEND. SEVERAL
ADDITIONAL COLD FRONTS WILL MOVE THROUGH THE AREA BUT MOISTURE IS
EXPECTED TO BE LIMITED WITH EACH FRONTAL PASSAGE. WHILE NOT
CERTAIN...THE PROBABILITY IS MODERATE TO HIGH THAT MOST OF THE AREA
WILL REMAIN DRY.
THE MODEL CONSENSUS FOR TUESDAY NIGHT THROUGH SATURDAY IS FOR DRY
CONDITIONS THROUGH THE PERIOD WITH TEMPERATURES AVERAGING AT OR
SOMEWHAT ABOVE NORMAL. ..08..
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 639 PM CDT SAT AUG 31 2013
MAIN CHALLENGE IS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT
INTO SUNDAY.
MVFR CIGS STILL FOUND OVER NORTHWEST IL WITHIN MOISTURE CONVERGENCE
ALONG INVERTED SURFACE TROUGH EXTENDING NWD FROM LOW PRESSURE
OVER CENTRAL IL. THIS TROUGH IS EXPECTED TO SHIFT EAST THIS EVENING
AND SHOULD KEEP ANY MVFR CIGS EAST OF THE TERMINALS...BUT WILL HAVE
TO WATCH KMLI. OTHERWISE...LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE
FAVORABLE FOR DEVELOPMENT OF FOG AND POSSIBLY SOME LOW CLOUDS OVERNIGHT.
THE RAP AND HRRR MODELS DO INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS
BUT ANTICIPATE INCREASE IN MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN
APPROACHING COLD FRONT...AND THIS COULD HAVE IMPACT ON MAGNITUDE/EXTENT
OF LOW CLOUDS AND FOG. FOR NOW HAVE LOWERED VSBYS INTO IFR TO LOWER
MVFR RANGE OVERNIGHT AND HINTED AT LOW CLOUDS WITH MENTION OF SCT CLOUDS
BLO 1KFT AGL. ALSO ANTICIPATE SCATTERED SHOWERS AND STORMS TO ACCOMPANY
THE COLD FRONT...WHICH IS SLATED TO PASS THROUGH THE TERMINALS FROM
12Z-18Z. CONDITIONS TO IMPROVE TO VFR AFTER PASSAGE OF FRONT WITH WINDS
INCREASING FROM NW AT 10-15 KTS WITH GUSTS AROUND 18-22+ KTS DURING
THE AFTERNOON.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...DLF
SHORT TERM...DLF
LONG TERM...08
AVIATION...05
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
624 PM CDT Sat Aug 31 2013
...Updated aviation discussion...
.SYNOPSIS...
ISSUED AT 300 PM CDT SAT AUG 31 2013
An upper level center of high pressure was located across New Mexico
and the extreme southern High Plains today, as the upper westerly
jet was positioned zonally across the northern Rockies and Northern
Plains. A shortwave was in place across southern Canada, on the
north side of the jet. A hot airmass still encompassed the central
part of the country. 850 mb level temperatures in excess of 20
degrees C extended from the entire great plains region eastward to
the the Ohio valley. at the surface...a cold front was moving
southward across western South Dakota and extreme western Nebraska.
Another weak stationary front was positioned from the Texas
panhandle northeast into south central Kansas. Easterly surface
winds became more southerly across western Kansas as surface low
pressure slowly filled across the Oklahoma panhandle and temperatures
warmed into the 90`s by early afternoon.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 300 PM CDT SAT AUG 31 2013
The immediate concern will revolve around convective chances which
are not great, but non-zero as well. The best location appears along
the diffuse boundary across south central Kansas. The HRRR runs have
somewhat approximated isolated convection occurring by about 23 utc.
A lack of upper winds and lack of shear suggest little chances at
all of severe thunderstorms, and storms should have short life
cycles. A better chance for showers and thunderstorms exists well
into the overnight as the Northern Plains cold front enters the
area. Probabilities increase from north to south around 6z and
after.
Very warm temperatures will continue into this evening. The NAM
models surface temperatures sill around 100 degrees this evening
near the Oklahoma line and low 80s persisting after midnight.
Morning lows will likely be warm across all of southwest Kansas,
with a few locations having lows in the upper 70s, however rain
cooled air form a few vigorous storm cluster might augment the
temperatures locally.
Thunderstorms chances are again in the forecast during the afternoon
Sunday as redevelopment is likely along the frontal boundary,
wherever it decides to stall out.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 235 PM CDT SAT AUG 31 2013
A cold front will move across Kansas tonight as a vigorous upper
level trough moves from southeast Saskatchewan to the Great Lakes,
and a brief period of near climatological temperatures should extend
into Monday. However, the anticyclone centered over the Rockies will
build back into the Central Plains early next week, and several days
of warm, quiet weather will follow. Unless rainfall tonight is more
widespread than appears likely, vegetation will become increasingly
drought stressed next week. Reduced evapotranspiration may allow
more solar radiation to covert into sensible heat, and temperatures
in the mid to upper 90s can be expected on most days.
Tropical thunderstorm activity has been strongly suppressed from
about 130E to the dateline, although an area of enhanced
thunderstorms has been persistent in the Indian Ocean southwest of
India. Most of the numerical models suggest that a coherent tropical
cluster that projects onto a Madden Julian Oscillation (MJO) will
amplify in Phase 1 of the Wheeler-Hendon Phase Space Diagram early
in September and propagate slowly east before losing identity in the
Indian Ocean. There is little correlation between the MJO and
sensible weather in the central plains at this time of the year, but
there may be in increased chance for tropical waves to come off
Africa into the eastern Atlantic next week.
Global relative angular momentum remains below climatology, but
mountain torque has increased in recent days. The atmosphere will be
best represented by Phase 4-5 of the Weickmann-Berry Global Wind
Oscillation, which correlates with anticyclonic flow in the western
and central United States. The deterministic model solutions all
favor ridging from the central Rockies across the central and
southern United States through the first ten days of September with
only minor synoptic scale differences. The 12Z GFS has trended
toward the 00Z ECMWF in handling the closed cyclone near 140W that
wallows into the northern plains 9-10 September and largely was
followed for grid adjustments, although confidence in behavior of
this cyclone is low.
Upslope flow into the foothills in eastern Colorado Sunday evening
should favor thunderstorm development, but the upper level flow will
be light and largely meridional over western Kansas. Most of the
thunderstorms will remain west of the Colorado border, but there is
a nonzero chance that a thunderstorm could reach far southwest
Kansas before midnight Sunday night. Cool high pressure with light
winds and low level dewpoints in the 50s will allow for strong
radiational cooling, and lows will drop into the upper 50s in most
areas Tuesday morning. Another minor trough dropping into the mean
long wave trough near 80W will support a weak boundary that may
survive into northern Kansas Wednesday night, but limited
instability and weak flow aloft do not favor an organized
thunderstorm event. As the upper level trough near 140W moves across
the Northern Plains around 9 September, a cold front will move into
Kansas and provide another opportunity for thunderstorm development
and a return to more seasonal temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 619 PM CDT SAT AUG 31 2013
Southeasterly winds at less than 10 knots this evening will shift
to the northeast late tonight as a cold front moves south across
western Kansas. There will also be a chance for some convection
along this front as it crosses western Kansas after midnight.
Based on 18z Bufr soundings the cloud bases overnight and early
Sunday are expected to be at or above 9000ft level so VFR
conditions are expected. Evening convection that was occurring
across northwest Kansas at 23z may bring a slight chance for
thunderstorms near the Hays area between 03z and 06z but
confidence is not high enough yet to a mention thunder prior to
06z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 75 88 60 89 / 20 20 10 0
GCK 72 88 58 90 / 30 20 10 0
EHA 70 88 64 91 / 20 20 10 10
LBL 72 88 60 92 / 20 20 10 0
HYS 75 88 57 90 / 40 20 0 0
P28 73 95 64 90 / 10 20 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Russell
SHORT TERM...Russell
LONG TERM...Ruthi
AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS GOODLAND KS
500 PM MDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 150 PM MDT SAT AUG 31 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE
EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW
BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA.
A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE
PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL
FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN
NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS
MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE
CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER
TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER
EASTERN WYOMING.
AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL
HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE
FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE
INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS
REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY
OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH
THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY
MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL
LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA
THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE
AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION
FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE
ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS
SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF
OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN
ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND
SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM
ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT
WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT
RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL.
REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE
FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD
ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER
THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS
WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE
MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO
BE FOR LABOR DAY WEEKEND.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 204 PM MDT SAT AUG 31 2013
THE UPPER RIDGE IS IN PLACE AGAIN OVER THE ROCKIES AND HIGH PLAINS
FROM SUNDAY NIGHT THROUGH ALL OF NEXT WEEK. DIFFERENCES BEGIN TO
SHOW UP IN MODEL PROGRESSIONS OF THE UPPER LOW CENTER RIDING UP
OVER THE RIDGE IN THE PACIFIC NORTHWEST AND THE OVERALL FLATTENING
OF THE RIDGE IN THE FRIDAY NIGHT THROUGH SATURDAY TIME PERIOD.
SURFACE COOLER HIGH PRESSURE AREA STAYS MOSTLY OVER THE CENTRAL
PLAINS AND CENTRAL HIGH PLAINS SUNDAY NIGHT AND MONDAY BEFORE
PUSHING FURTHER EAST WITH A DEEPENING LEE TROUGH THAT PERSISTS IN
THE VICINITY OF THE EASTERN COLORADO BORDER. WITH SOUTHERLY FLOW
ACROSS THE FORECAST AREA...EXPECT MORE DRY AND WARM CONDITIONS
THROUGH THE UPCOMING WORK WEEK AND NEXT WEEKEND WITH HIGHS IN THE
90S AND LOWS IN THE 60S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 500 PM MDT SAT AUG 31 2013
FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. AT 23Z FRONTAL
BOUNDARY LOCATED NEAR K2V5 AND KSYF WHERE SHOWERS AND
THUNDERSTORMS ONGOING. WIND GUSTS TO 35KTS REPORTED AT KSYF. FRONT
NOT EXPECTED TO PASS THROUGH TERMINALS TIL THE 03Z-07Z TIMEFRAME
WHERE NORTHEAST WINDS GUSTING AROUND 20KTS POSSIBLE. THIS WILL
CONTINUE THROUGH MUCH OF THE DAY SUNDAY BEFORE DECREASING TO
AROUND 10KTS OR LESS BY LATE IN THE AFTERNOON. CANT RULE OUT SOME
PRECIPITATION AT EITHER TERMINAL TIL THE FRONT PASSES WITH DRY
WEATHER EXPECTED BEHIND IT. DISTANCE SPEED TOOL SUGGESTS CURRENT
AREA OF THUNDERSTORMS AT TAF ISSUANCE WILL BE IN THE VICINITY OF
KGLD FOR A FEW HOURS SO HAVE ADDED A TEMPO GROUP FOR THUNDERSTORMS
THROUGH 02Z. CONFIDENCE NOT QUITE AS HIGH AT KMCK TO INCLUDE A
THUNDER/PRECIP GROUP BUT WILL WATCH CLOSELY AND ADD ONCE
CONFIDENCE INCREASES SHOULD THAT TERMINAL BE IMPACTED.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
1047 PM EDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 1043 PM EDT SAT AUG 31 2013
MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS
EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A
FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST
CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE
SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY
THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND
THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE
POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR
THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN
STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT
FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO
DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS
PERIOD.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 841 PM EDT SAT AUG 31 2013
SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA
SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE
AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT
AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE
SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY...
WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS
EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT
WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE
SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING
SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR
THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR
SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO
EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS
POINT FOR ANYTHING MORE THAN VCTS IN TAFS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...HAL
AREA FORECAST DISCUSSION...CORRECTED
NWS JACKSON KY
844 PM EDT SAT AUG 31 2013
.MESOSCALE DISCUSSION...
ISSUED AT 540 PM EDT SAT AUG 31 2013
IN GENERAL...THE LINE ENTERING EASTERN KENTUCKY HAS BEEN WEAKENING.
JUST BEFORE THE LINE MOVED INTO THE AREA...AN OUTFLOW BOUNDARY MOVED
ACROSS THE AREA FROM NE TO SW AND AND HELPED TO DESTROY SOME OF THE
FAVORABLE STORM ENVIRONMENT. SOME TEMPERATURES STILL TO THE EAST OF
THE LINE ARE PRETTY WARM...SO DECIDED TO ISSUE A SPECIAL WEATHER
STATEMENT FOR THE LINE AS IT MAY STRENGTHEN AS THEY FIND MORE
FAVORABLE AIR. THE WARMER TEMPERATURES ARE GENERALLY WEST OF A LINE
FROM ROCKCASTLE TO BELL COUNTIES.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 841 PM EDT SAT AUG 31 2013
SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA
SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE
AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT
AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE
SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY...
WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS
EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT
WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE
SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING
SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR
THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR
SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO
EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS
POINT FOR ANYTHING MORE THAN VCTS IN TAFS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...JJ
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
842 PM EDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 841 PM EDT SAT AUG 31 2013
SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA
SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE
AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT
AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE
SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY...
WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS
EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT
WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE
SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING
SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR
THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR
SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO
EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS
POINT FOR ANYTHING MORE THAN VCTS IN TAFS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS GRAY ME
1206 PM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY
BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW
ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
1202 PM...MINOR ESTF UPDATE TO 1ST PERIOD GRIDS TO REFLECT 16Z
MESONET AND CURRENT SATELLITE TRENDS.
PREV DISC...
930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE
LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN
THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES.
I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO
REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY.
PREV DISC...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
ES
AREA FORECAST DISCUSSION
NWS GRAY ME
937 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY
BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW
ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE
LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN
THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES.
I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO
REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY.
PREV DISC...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
ES
AREA FORECAST DISCUSSION
NWS GRAY ME
659 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
448 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS.
PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS
NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS
SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A
FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
246 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA
EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE
SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH
THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON
TUESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND
WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS
THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN
AREAS THAT CLEARED OUT EARLIER.
LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE
AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY
AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR
AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH
PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE
NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING
THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND
TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST.
SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE
FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE
AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS.
HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT
MENTIONING IN THE GRIDS.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS
OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A
FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS
WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF
CLOUDS AND MILD MIN TEMPS.
ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE
AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE
BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER
INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL
SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE
FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY
MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER
VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND
CENTRAL MAINE AND NEW HAMPSHIRE.
THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY.
SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF
THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE
EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY
TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE
REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW
THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST
AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING.
THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR
INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR
DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR
CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR
CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND
SAT.
LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY.
THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN
CEILINGS AND VSBYS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT.
LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5
FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
738 PM EDT SAT AUG 31 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WITH PERIODIC SHOWERS AND THUNDERSTORMS
WILL PREVAIL THROUGH THE LABOR DAY WEEKEND.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF MID-AFTERNOON...CONVECTION HAS GENERALLY BEEN A BUST SO
FAR. EXCEPT FOR A FEW ISOLATED SHOWERS ALONG THE INTERSTATE 80
CORRIDOR...ALL LOCATIONS HAVE REMAINED DRY SINCE MID-MORNING.
CONSIDERING THE MAIN UPPER LEVEL SHORTWAVE HAS ALREADY PUSHED EAST
OF THE REGION...DO NOT REALLY SEE ANYTHING THAT WILL PROVIDE MUCH
OF A FORCING MECHANISM UNTIL THE NEXT SHORTWAVE AFFECTING THE AREA
LATE TONIGHT INTO SUNDAY. AS A RESULT...HAVE CUT WAY BACK ON POPS
EARLY...RAMPING THEM UP AGAIN BY LATE TONIGHT. HOWEVER...CANNOT
COMPLETELY DISCOUNT THE POSSIBILITY OF A LINE OF SHOWERS/STORMS
DEVELOPING FROM NORTHEAST TO SOUTHWEST ACROSS THE REGION WHICH
SEVERAL RUNS OF THE HRRR HAS BEEN INSISTENT WILL DEVELOP JUST
BEFORE SUNSET. ANOTHER STICKY NIGHT CAN BE EXPECTED WITH LOWS ONLY
DROPPING TO AROUND 70.
A BIT OF DISAGREEMENT BETWEEN MODELS FOR TOMORROWS FORECAST. ALL OF
THE SYNOPTIC MODELS BRING A DECENT SHORTWAVE FROM EASTERN OHIO IN
THE MORNING TO CENTRAL PENNSYLVANIA BY THE AFTERNOON...TRIGGERING
WIDESPREAD PRECIPITATION. ON THE OTHER HAND...ALL OF THE HIGH
RESOLUTION MODELS SHOW MUCH LESS COVERAGE WITH PRECIP. SEEING AS THE
SHORTWAVE IN QUESTION IS CURRENTLY OVER CHICAGO PRODUCING SHOWERS
AND THUNDERSTORMS...WILL STICK WITH THE SYNOPTIC MODEL SOLUTIONS. A
SCENARIO SIMILAR TO TODAY COULD OCCUR...WITH THE HIGHEST POPS
POTENTIALLY ARRIVING IN THE MORNING ACROSS WESTERN PORTIONS OF THE
AREA ALONG WITH THE SHORTWAVE AND REMNANT THUNDERSTORMS.
HOWEVER...WILL PUT IN LIKELY POPS ALONG THE RIDGES DURING THE EARLY
AFTERNOON WHILE THE SHORTWAVE IS PASSING THROUGH.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
THERE SHOULD BE A BRIEF LULL IN PRECIPITATION SUNDAY EVENING WITH
THE UPPER LEVEL SHORTWAVE TO THE EAST AND THE NEXT COLD FRONT OUT
TO THE WEST. RAIN SHOULD BEGIN TO OVERTAKE THE EASTERN COUNTIES
VERY EARLY MONDAY...AND THE FRONT WILL BE HUGGING THE RIDGES BY
MONDAY EVENING. INSTABILITY AND WIND SHEAR SHOULD BE HIGH ENOUGH
THAT A FEW STRONGER THUNDERSTORMS ARE POSSIBLE...BUT OVERALL
SEVERE THREAT APPEARS TO BE LOW.TEMPERATURES SUNDAY NIGHT AND
MONDAY SHOULD BE SIMILAR TO THOSE THROUGH THE EARLIER PORTIONS OF
THE WEEKEND.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE CDFNT IS FORECAST TO EXIT THE RGN MON NGT AND END THE SHWR
CHCS. BLDG HIGH PRES SHOULD THEN MAINTAIN DRY WEATHER UNTIL
PASSAGE OF ANOTHER WEAK CDFNT ON THU. LTD MSTR IS PROGGED WITH
THAT FNT...SO ONLY SLGT CHC POPS WERE INCLUDED ATTM. UNDR ERN
CONUS TROFG ALOFT...SUB AVG TEMPS ARE EXPD INTO SATURDAY.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS SHOULD PREVAIL OUTSIDE OF ISOLATED CONVECTIVE
ACTIVITY THIS EVENING. MORE ORGANIZED TS WILL LIKELY STAY MOSTLY
TO THE SOUTHWEST OF THE AREA THROUGH THE EARLY EVENING...WITH ONLY
ISOLATED ACTIVITY POSSIBLY CLIPPING KZZV AND KMGW.
OTHERWISE...MVFR VIS/CIG RESTRICTIONS ARE POSSIBLE OVERNIGHT
TOWARD MORNING BEFORE A MORE POTENT WAVE MOVES THROUGH THE AREA ON
SUNDAY...BRINGING A BETTER CHANCE FOR SHOWERS/TS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
A DECISIVE CDFNT PASSAGE IS STILL SLATED FOR MONDAY. RESTRICTIONS
MAY THUS BE EXPECTED UNTIL HIGH PRES BUILDS FOR TUESDAY THROUGH
THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
744 PM EDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE SHRA/TS CHCS ASSOCIATED
WITH SHRTWV NOW NEAR LK WINNIPEG.
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER
THE NRN CONUS ON THE NRN FLANK OF SPRAWLING HI PRES CENTERED OVER
THE SW CONUS. STUBBORN LO CLDS OVER THE SCENTRAL COUNTIES ARE
FINALLY BURNING OFF. THERE IS A SHRTWV TRACKING THRU ONTARIO...BUT
THIS DISTURBANCE IS PASSING FAR ENUF TO THE N THAT THE COMMA TAIL
-SHRA ARE JUST BRUSHING NEAR ISLE ROYALE. WEAK RDG OF HI PRES OVER
THE GRT LKS/SHARP SUBSIDENCE INVRN SHOWN ON LOCAL 12Z RAOBS IS
BRINGING QUIET WX TO THE CWA FOR NOW. A STRONGER SHRTWV IS PRESENT
ALONG THE NDAKOTA/CNDN BORDER AND MOVING QUICKLY TO THE ESE. WHERE
THE SHARP DPVA/DEEP LYR QVECTOR CNVGC IN ADVANCE OF THIS FEATURE IS
OVERSPREADING AXIS OF HIER MUCAPE/H85 THETA E AHEAD OF ATTENDANT
COLD FNT...NMRS SHRA/TS ARE BREAKING OUT IN MN.
TNGT...SHRTWV JUST SW OF LK WINNIPEG IS PROGGED TO MOVE ESE AND OVER
NCENTRAL LK SUP BY 12Z SUN. AS THE DPVA/DEEP LYR QVECTOR CNVGC AND
AXIS OF HIER INSTABILITY/H85 THETA E MOVE INTO WRN LK SUP THIS
EVNG...EXPECT SHRA/TS NOW OVER MN TO SHIFT INTO THE WRN LAND CWA BY
06Z. GIVEN FCST MUCAPE IN EXCESS OF 1000 J/KG...SFC-6KM SHEAR IN THE
40-50KT RANGE /FORTUNATELY THE STORMS WL BECOME ELEVATED SO THIS WL
NOT BE THE EFFECTIVE LYR SHEAR/...AND FAIRLY SHARP LLVL CNVGC ALONG
ATTENDANT COLD FNT...SOME OF THESE STORMS MAY BE STRONG. BUT WITH
LOSS OF DAYTIME HEATING AND WEAKENING H85 THETA E AXIS...EXPECT THE
INTENSITY OF THESE SHRA/TS TO DIMINISH AS THEY SPREAD INTO CENTRAL
UPR MI LATE. IN FACT...THE MOST RECENT SPC CONVECTIVE OUTLOOK THRU
12Z SUN CONFINES THE SLGT RISK FOR SVR TS TO MN AND FAR WRN LK SUP.
WHERE TEMPS HAVE A CHC TO COOL DOWN A BIT OVER THE E HALF BEFORE THE
ARRIVAL OF CLDS/A BIT SHARPER PRES GRADIENT...ADDED PATCHY FOG WITH
EXPECTATION THAT MIN TEMPS FALLING INTO THE UPR 50S WL FALL THRU THE
CROSSOVER DEWPT OBSVD THIS AFTN.
SUN...AS SHRTWV OVER NCENTRAL LK SUP IN THE MRNG SHIFTS INTO SE
ONTARIO IN THE AFTN...DNVA/DEEP LYR QVECTOR DVGC/VIGOROUS NEGATIVE
H85 THETA E ADVCTN IS FCST TO ARRIVE W-E FOLLOWING ATTENDANT COLD
FROPA. EXPECT BAND OF SHRA/TS AHD OF COLD FNT TO SHIFT FM THE CNTRL
ZNS INTO THE ERN ZNS DURING THE MRNG. SHRA/TS INTENSITY MAY PICK UP
OVER THE FAR ERN CWA IN THE EARLY AFTN WITH IMPACT OF DAYTIME
HEATING LIFTING MUCAPE TO 500-1000 J/KG AND DEEP LYR SHEAR 30 TO 40
KTS BEFORE THE MORE ROBUST QVECTOR DVGC ARRIVES IN THE AFTN AND
BEGINS TO SUPPRESS THE CONVECTION WITH STRENGTHENING INVRN FOLLOWING
COLD FROPA AT ERY NEAR 21Z. THIS THREAT WOULD BE GREATER IF THE
SOMEWHAT SLOWER GFS VERIFIES...BUT THE PRESENT STEADY SPEED OF
SHRTWV INDICATES THE FASTER MODEL FCSTS ARE ON THE RIGHT TRACK.
FOLLOWING THE COLD FROPA AND ARRIVAL OF LLVL COOLER AIR...NAM FCST
SDNGS SHOW SHARPENING LLVL INVRN/PROSPECT FOR LO CLDS AND SOME
SPRINKLES...ESPECIALLY OVER THE W AND NCENTRAL WITH UPSLOPE NW FLOW.
SFC TEMPS MAY ACTUALLY FALL AT THESE PLACES DURING THE AFTN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MORE SEASONABLE WEATHER IS EXPECTED THROUGH MUCH OF THE UPCOMING
WEEK...WITH CHANCES OF PRECIPITATION MONDAY AND AGAIN WEDNESDAY.
SUNDAY NIGHT AND MONDAY...A STRONG AND SHARP MID-LEVEL SHORTWAVE
OVER NE LAKE SUPERIOR WILL BE STARTING TO EXIT TO THE EAST AT THE
START OF THE PERIOD. THE ASSOCIATED SFC LOW WILL ALSO BE TRACKING
EASTWARD AWAY FROM EASTERN LAKE SUPERIOR. THE MAIN FORECAST CONCERN
IS HOW LONG MOISTURE WILL LINGER BEHIND THIS SYSTEM...AND HOW
WIDESPREAD UPSLOPE DRIZZLE/SHOWERS WILL BE. WITH PLENTY OF LOW-LEVEL
MOISTURE WRAPPING BEHIND THE LOW...EXPECT PLENTY OF DRIZZLE AND
LIGHT SHOWERS FOR ANY AREA EXPOSED TO NNW WINDS OFF LAKE SUPERIOR.
SUBSIDENCE WILL LOWER INVERSION HEIGHTS TO AROUND 1KM ACROSS THE
AREA...SO THE SATURATED LAYER WILL BE QUITE SHALLOW. INSOLATION ON
MONDAY SHOULD BE STRONG ENOUGH TO START ERODING THIS MOIST LAYER
MONDAY MORNING. INCREASINGLY DRIER AIR ADVECTING IN FROM WESTERN
ONTARIO SHOULD THEN REMOVE REMAINING CLOUDS/PRECIP FROM WEST TO EAST
THROUGHOUT MONDAY AFTERNOON.
HAVE INCREASED WINDS SEVERAL KNOTS ACROSS THE EAST HALF OF THE CWA
GIVEN A 1020MB SFC HIGH IN THE UPPER MS VALLEY IMPINGING ON THE
BACKSIDE OF THE DEPARTING 1002MB LOW. COULD SEE QUITE A BREEZY DAY
FOR MUCH OF THE AREA...WITH WINDS GUSTING OVER 30MPH RIGHT NEAR THE
LAKE SUPERIOR SHORE FROM BIG BAY EASTWARD. WILL CONTINUE TO RAMP UP
WORDING ON A HIGH SWIM RISK GIVEN THE LABOR DAY HOLIDAY.
MONDAY NIGHT...AS THE SFC HIGH SETTLES OVER NORTHERN WI MONDAY
NIGHT...CLEAR SKIES AND LOW PWAT VALUES OF LESS THAN 0.5 INCHES WILL
ALLOW FOR GOOD RADIATIONAL COOLING. HAVE MAINTAINED PREVIOUS
FORECAST TEMPS OF LOW 40S INTERIOR WEST HALF TO LOW 50S NEAR THE
GREAT LAKES. RESIDUAL STRONGER NW GRADIENT FLOW ACROSS THE EAST HALF
SHOULD LIMIT COOLING TO SOME EXTENT.
TUESDAY THROUGH THURSDAY...A SHORTWAVE TROUGH CURRENTLY TRACKING
EASTWARD ALONG THE ALLUETIAN ISLANDS WILL STALL OVER WESTERN ALASKA
AND SEND A SERIES OF WEAK WAVES ACROSS WESTERN CANADA. THE MAIN WAVE
OF INTEREST WILL BECOME AMPLIFIED BY ANOTHER STRONGER WAVE OVER THE
NORTH SLOPE OF ALAKSA. TIMING AND STRENGTH OF THIS FEATURE HAVE BEEN
UNDERSTANDABLY DIFFICULT FOR THE MODELS TO PIN DOWN. THE GFS HAS
WAVERED IN STRENGTH OVER THE LAST SEVERAL RUNS...WITH THE LATEST TWO
RUNS INDICATING A SLOWER AND WETTER SOLUTION. THIS IS LIKELY A
RESULT OF A LONGER PRECEEDING PERIOD OF LOW-LEVEL MOISTURE RETURN.
THE GEM IS THE QUICKEST SOLUTION OF THE THREE. HAVE OPTED TO EMPLOY
THE ECMWF FOR THE REST OF THE FORECAST GIVEN ITS MIDDLE GROUND AND
CONTINUITY OVER THE LAST COUPLE DAYS.
THE MAIN MID-LEVEL AND SFC LOWS WILL TRACK WELL NORTH OF THE
CWA...POSSIBLY AS FAR NORTH AS SOUTHERN HUDSON BAY. THE 990MB SFC
LOW DEPICTED BY THE ECMWF WILL BE STRONG ENOUGH TO SEND A POTENT
COLD FRONT SSE-WARD ACROSS THE CWA WEDNESDAY MORNING.
HOWEVER...THERE WILL BE A SUBSTANTIAL AMOUNT OF DRY AIR WITH THIS
SYSTEM GIVEN ITS ORIGIN. WILL PLACE ONLY SLIGHT CHANCE POPS ACROSS
THE FAR NORTH AND EAST CLOSER TO THE STRONGEST FORCING VIA MID-LEVEL
Q-VECTOR CONVERGENCE AND THE LEFT EXIT OF A 120KT UPPER JET. MUCH OF
UPPER MI...ESPECIALLY THE SOUTHWEST...LOOKS TO BE UNDER SUBSIDENCE
FROM THE RIGHT ENTRANCE OF THE JET...AND MAY NOT EVEN SEE MUCH IN
THE WAY OF CLOUD COVER. MOST OF THE COOLER AIR BEHIND THE FRONT WILL
STAY EAST OF THE AREA...SO ONLY A SLIGHTLY COOLER DAY THAN WEDNESDAY
IS EXPECTED FOR THURSDAY.
FRIDAY AND SATURDAY...BESIDE DEVELOPING THE IDEA OF DEEPER TROUGHING
ACROSS EASTERN CANADA...MODEL AGREEMENT ON SMALLER SCALE FEATURES IS
POOR BY THIS POINT IN THE FORECAST. THE GFS/GEM INDICATE STRONG SFC
HIGH PRESSURE BUILDING ACROSS THE AREA...WHILE THE ECMWF KEEP THE
HIGH MUCH FARTHER NE NEAR JAMES BAY. A WEAK SHORTWAVE DEPICTED BY
BOTH THE ECMWF AND GFS COULD BRING SHOWER CHANCES FOR FRIDAY...BUT
TIMING THE GFS IS SOMEWHAT SLOWER WITH THIS IDEA. EITHER WAY...VERY
LIMITED MOISTURE WILL PRECLUDE ANYTHING MORE THAN SPOTTY SHOWER
COVERAGE. HAVE OPTED TO MAINTAIN CONCENSUS FORECAST AT THIS POINT
GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 743 PM EDT SAT AUG 31 2013
EXPECT DRY WX/VFR CONDITIONS AT KIWD/KCMX/KSAW THRU THE EVENING WITH
RELATIVELY DRY/STABLE AIR MASS IN PLACE. ONE POSSIBLE EXCEPTION WILL
BE AT KCMX LATE THIS EVENING/EARLY OVERNIGHT AS AREA OF FOG HAS
DEVELOPED OVER ERN LAKE SUPERIOR. IF WINDS MAINTAIN AN EASTERLY
COMPONENT LONG ENOUGH...FOG/STRATUS COULD DEVELOP AT KCMX.
CONDITIONS COULD BE AS LOW AS LIFR IF FOG MAKES A STRONG WESTWARD
PUSH TO THE KEWEENAW. OTHERWISE...APPROACH OF COLD FRONT/MORE
UNSTABLE AIR MASS WILL BRING THREAT OF SHRA AND PERHAPS SOME TS
LATER TONIGHT FROM W TO E. SUFFICIENT INSTABILITY IS PRESENT TO
RETAIN MENTION OF VCTS. FOLLOWING THE COLD FROPA SUN MORNING...
EXPECT LOW CLDS/IFR CONDITIONS TO IMPACT KIWD AND KCMX WITH UPSLOPE
NW FLOW UNDER STRENGTHENING SHARP INVERSION. MVFR CONDITIONS SHOULD
DEVELOP AT KSAW IN THE AFTN AFTER WIND VEERS TO THE NNW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT SAT AUG 31 2013
EXPECT SSW WINDS UP TO 20-25 KTS TONIGHT INTO SUN MORNING OVER THE E
HALF OF THE LAKE UNDER A SHARPENING PRES GRADIENT AHEAD OF AN
APPROACHING COLD FRONT. FOLLOWING THE PASSAGE OF THIS FRONT...THERE
WILL BE A WIND SHIFT TO THE NW...WITH WINDS INCREASING UP TO 25 KTS
IN THE AFTERNOON. THE COMBINATION OF DECREASING STABILITY WITH THE
ARRIVAL OF A COOL AIRMASS AND A SHARPENING PRES GRADIENT BETWEEN A
DEPARTING LO PRES SYSTEM AND AN APPROACHING HI WILL RESULT IN NW-N
WINDS UP TO 20-30 KTS ON SUN NIGHT INTO MON. THE ARRIVAL OF THE HI
AND WEAKER PRES GRADIENT WILL ALLOW WINDS TO DIMINISH UNDER 20 KTS
TUE THRU THU.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
127 PM CDT FRI AUG 30 2013
.AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS ARE EXPECTED ACROSS THE NORTHLAND TODAY INTO THIS
EVENING. AS THE NIGHT WEARS ON...AREAS OF FOG ARE EXPECTED TO
DEVELOP WITH LOCAL IFR/MVFR CONDITIONS.
&&
.PREV DISCUSSION... /ISSUED 1016 AM CDT FRI AUG 30 2013/
UPDATE...
REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED
WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE
FORECAST.
PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/
AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 0 20 50
INL 79 60 83 57 / 10 20 50 50
BRD 81 60 87 60 / 10 10 30 50
HYR 79 56 85 63 / 20 0 10 60
ASX 74 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...TENTINGER
LONG TERM....DAP
AVIATION...DAP
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1016 AM CDT FRI AUG 30 2013
.UPDATE...
REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED
WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE
FORECAST.
&&
.PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/
AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 0 50 50
INL 79 60 83 57 / 10 20 50 50
BRD 81 60 87 60 / 10 10 50 50
HYR 79 56 85 63 / 20 0 10 60
ASX 74 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
643 AM CDT FRI AUG 30 2013
.AVIATION...12Z TAFS
A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS
MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON
THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO
THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND
BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY
WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN.
WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS
AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS
SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL.
TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE
LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM
OVER OR AROUND LAKE SUPERIOR.
&&
.PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/
SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD
FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER
DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING
OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH
VERY SLOW REDUCTION IN SFC DEWPOINTS.
TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM
PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY
LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY.
POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON
RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH
AND EAST INTO WISC ZONES DURING THE AFTN.
TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM
MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT
OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN
ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED
ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM
ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST.
TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE
INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA
BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE
UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND
MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY
LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF
THE CWA.
SATURDAY NIGHT THROUGH THURSDAY.
MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT
SATURDAY NIGHT.
THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE
AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE
STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER.
PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE
FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS
OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS
COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS
STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS
STRONGER STORMS.
THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO
SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS
THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH
HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR
SOUTHEAST ZONES.
HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO
THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING
FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE
SEVENTIES BY THURSDAY.
&&
.POINT TEMPS/POPS...
DLH 78 57 81 61 / 10 10 20 50
INL 82 60 83 57 / 10 10 50 50
BRD 84 60 87 60 / 10 0 30 50
HYR 81 56 85 63 / 20 0 10 60
ASX 76 57 80 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
104 AM CDT FRI AUG 30 2013
.UPDATE...QUICK UPDATE TO LOWER/DROP POPS OVER MN ZONES AND REDUCE
OVER WISC ZONES. NW POST FRONTAL FLOW IS DEEPENING OVER NE MN WITH
DRIER AIR FILTERING INTO THE CWA. OPPORTUNITY STILL EXISTS FOR
REDEVELOPMENT OF CONVECTION OVER WISC WITH PREFRONTAL LIFT AND MID
LVL LAPSE RATES EXCEEDING 7C/KM PER SPC MESOANALYSIS. ALSO HAVE
30/35KT DEEP LAYER SHEAR HOWEVER WITH BDRY LYR
DECOUPLED...ELEVATED CONVECTION SHOULD BE THE RESULT WITH LOCALLY
GUSTY WINDS AND HEAVY DOWNPOURS.
&&
.PREV DISCUSSION... /ISSUED 1239 AM CDT FRI AUG 30 2013/
AVIATION...06Z TAFS.
MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE
TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY
AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL
08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT
INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS
ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE
WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW
CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN
MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY
15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE
FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10
KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN
10KTS.
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/
SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.POINT TEMPS/POPS...
DLH 80 58 79 61 / 10 0 20 50
INL 84 62 82 57 / 10 20 50 50
BRD 86 62 86 60 / 10 0 40 50
HYR 83 58 84 63 / 20 0 10 60
ASX 78 59 78 63 / 20 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CANNON
AREA FORECAST DISCUSSION
NWS DULUTH MN
1239 AM CDT FRI AUG 30 2013
.AVIATION...06Z TAFS.
MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE
TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY
AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL
08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT
INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS
ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE
WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW
CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN
MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY
15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE
FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10
KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN
10KTS.
&&
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/
SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.POINT TEMPS/POPS...
DLH 80 58 79 61 / 30 0 20 50
INL 84 62 82 57 / 10 20 50 50
BRD 86 62 86 60 / 10 0 40 50
HYR 83 58 84 63 / 30 0 10 60
ASX 78 59 78 63 / 30 0 10 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
AVIATION...LE/MELDE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1148 PM CDT Thu Aug 29 2013
.UPDATE:
Issued at 930 PM CDT Thu Aug 29 2013
Mid-evening update mainly to remove isolated thunderstorms from
the forecast over south central Illinois. The rest of the forecast
looks to be in good shape for the rest of the night. Noticed that
the RUC is spitting out some precip over parts of west central and
central Missouri late tonight in proximity to the upper low now
moving through eastern Kansas in an area of weak 850mb warm
advection. The new 00Z NAM is dry until after sunrise and then the
precip is further to the southwest. Will keep the forecast dry for
the rest of the night and let the midnight shift add in some
isolated showers or storms if something does indeed pop up.
Carney
&&
.SHORT TERM: (Through Late Tonight)
Issued at 254 PM CDT Thu Aug 29 2013
The front at midday was located from extreme southeast IA to east of
a KUIN-KSLO line into western KY, while a weak north-south surface
ridge axis was located through central MO. The front appears to be
trying to jump west into a new wind shift line closer to the MS
River. However, the more agitated cu field and axis of greatest
instability and weak CIN resides along the more eastern location,
and present indications are this would be the most favored location
for isolated shower/thunderstorm development through early evening.
After sunset the threat of any precipitation appears quite low as
the air mass will become more stable, diurnal cu will dissipate, and
any forcing along the boundary will be quite weak. Otherwise,
tonight looks rather uneventful with the upper low dropping
southeastward through KS spreading some high clouds into the western
half of the CWA, and min temperatures a tad bit warmer.
Glass
.LONG TERM: (Friday through Next Thursday)
Issued at 254 PM CDT Thu Aug 29 2013
Upper level shortwave over southwestern Missouri will continue to
slowly slide to the south on Friday. Could see a slight chance of
showers and thunderstorms mainly over the Ozarks on Friday. In the
meantime the next frontal boundary, currently over South
Dakota/western Nebraska, will move into northern Missouri by Friday
afternoon. Activity associated with this boundary, very scattered in
nature, will move into northeast MO, west central IL Friday evening.
There could be some lingering isolated activity associated with
upper level system over southern and eastern portions of forecast
area as well.
As for high temperatures on Friday, it will be a bit warmer than
today, but with a few more clouds and dewpts still mixing out, heat
indicies will remain in the 100 to 104 range, though a few spots
could reach 105.
By Saturday, cold front to weaken even more as it slides through
region. There is a chance of a few storms, mainly over far eastern
portions of forecast area. Otherwise, another hot day in store
despite a few more clouds and front moving through. Highs will be in
the low to mid 90s with heat indicies between 100 and 104.
A more vigorous cold front to approach area late Saturday night with
best chances of rain Sunday and Sunday night. Again not a lot of
moisture associated with it, so activity to be rather scattered with
it. With this front, cooler and less humid air to make its way into
region, so will keep heat advisory headline going through Saturday
for metro area, no need to extend it beyond this time period.
Beyond that, precipitation to taper off very early Monday morning
with surface ridge building in and more seasonable temperatures
expected through the work week.
Byrd
&&
.AVIATION: (For the 06z TAFs through 06z Friday Night)
Issued at 1135 PM CDT Thu Aug 29 2013
Stalled trof/boundary over extreme eastern Missouri in the process
of dissipating attm as pressure falls from retreating ridge are
allowing a gradual return of weak southerly flow across the mid-
Mississippi Valley. Due to fairly low T/Td spreads and vsby
forecasts on 00z based MET/MAV have added some MVFR vsbys in fog
at climatologically favored locations (SUS, CPS), as well as at
UIN where the visbility has already started a gradual decline.
Some of the 00z guidance is also hinting at some convection
developing over mid-Missouri by daybreak, but signal is still
fairly weak so have maintained a dry forecast for now...with a few
early morning mid clouds followed by another day of diurnal cu
development. Will also need to keep an eye on convective potential
with approaching cold front Friday night, but attm it appears that
primary threat with this feature into Friday evening will remain
north of our CWA.
Specifics for KSTL: While latest guidance and obs suggest that
there will be some vsby restriction at low lying locations (SUS
and CPS) in the STL metro believe this will not impact the STL TAF
vicinity. So...forecast for the overnight hours maintains VFR
conditions with a generally clear sky...with diurnal heating
leading to another afternoon of cu with bases aoa 5kft.
Truett
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...HEAT ADVISORY until 7 PM CDT Saturday FOR St. Charles MO-St.
Louis City MO-St. Louis MO.
IL...HEAT ADVISORY until 7 PM CDT Saturday FOR Madison IL-St. Clair
IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
218 PM MDT FRI AUG 30 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
NOT AS WARM THIS WEEKEND WITH WIND SATURDAY.
LOW PRESSURE OVER SASK THIS AFTERNOON WILL BEGIN TO SEND A COLD
FRONT OUR WAY TONIGHT WHEN AN UPPER LEVEL SYSTEM TO IT/S WEST
CATCHES UP. THIS FRONT IS EXPECTED TO PUSH SOUTHEAST THROUGH NE MT
SATURDAY MORNING. 850 MB TEMPS FALL A FEW DEGREES SATURDAY AND
ATMOSPHERE MIXES TO ABOUT 750 MB. WINDS AT THAT LEVEL LOOK TO BE
ABOUT 25-30 KTS SO 20 TO 30 MPH SURFACE WINDS CAN BE EXPECTED.
THESE WINDS ARE LOOKING TO OCCUR FROM ABOUT NOON TO 8 PM OVER FORT
PECK LAKE...SO WILL GO AHEAD AND ISSUE A LAKE WIND ADVISORY FOR
THIS PERIOD.
OTHERWISE...SOME MID-LEVEL INSTABILITY MAY BUBBLE UP A SHOWER/STORM
LATE THIS AFTERNOON. THE HRRR AS USUAL IS EXCITED ABOUT IT WHILE THE
OTHER MODELS (INCLUDING THE RUC) ARE MUCH DRIER. THE NAM IS SHOWING
THIS TO OCCUR LATER TONIGHT IN THE SOUTHERN ZONES...FINALLY EXITING
INTO THE DAKOTAS SATURDAY AFTERNOON.
SURFACE HIGH PRESSURE THEN BUILDS INTO THE AREA SATURDAY NIGHT
PROVIDING LIGHT WINDS...NEAR NORMAL TEMPS AND CLEAR SKIES THROUGH
SUNDAY. ENJOY! TFJ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THE LONG TERM FORECAST PERIOD IS CHARACTERIZED BY A SIGNIFICANT
AND AMPLIFIED WEATHER PATTERN...BASICALLY SPLIT BETWEEN TWO
DIFFERENT WEATHER REGIMES.
SUNDAY NIGHT THROUGH WEDNESDAY AFTERNOON...THE CENTRAL CONUS RIDGE
AND THE PACIFIC NORTHWEST LOW BUTT UP AGAINST EACH OTHER IN A
STRUGGLE FOR DOMINANCE THAT DOES NOT COME TO A RESOLUTION UNTIL
LATE WEDNESDAY NIGHT.
IT SHOULD BE NOTED THAT THE LARGE SCALE MODELS HINT AT A SHORT
WAVE DISTURBANCE RIDING UP AND AROUND THE RIDGE OF HIGH PRESSURE
MAKING ITS WAY THROUGH EASTERN MONTANA TUESDAY MORNING THROUGH
TUESDAY AFTERNOON...LIKELY BRINGING ONLY ISOLATED PRECIPITATION TO
THE AREA.
THE BIGGER STORY BEGINS OVERNIGHT WEDNESDAY NIGHT AS THE LARGE
UPPER LEVEL LOW PRESSURE SYSTEM FINALLY MOVES INLAND OVER THE
PACIFIC NORTHWEST...TURNING OUR FLOW ALOFT FROM THE SOUTHWEST AND
SOUTH. THIS WILL LIKELY PUMP SIGNIFICANT AMOUNTS OF PACIFIC
MOISTURE OVER THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS. WITH
EACH MODEL RUN...THE CONSENSUS IMPROVES REGARDING THE TIMING AND
PLACEMENT OF THIS UPPER LOW INTO THE INTER-MOUNTAIN NORTHWEST.
AT THIS TIME...SIGNIFICANT DIFFERENCES WITH THIS WEATHER REGIME
CHANGE BEGIN TO EMERGE EARLY THURSDAY MORNING AS THE AGGRESSIVE GEM
PUSHES FASTER AHEAD...FOLLOWED BY THE SLOWER GFS AND THEN THE
SLOWEST EC. FOR NOW...CAN ONLY BROAD-BRUSH THE END OF THE EXTENDED
FORECAST PERIOD WITH A WETTER WEATHER PATTERN. WOULD EXPECT THINGS
TO COME MORE INTO FOCUS OVER THE NEXT FEW DAYS. BMICKELSON
PREVIOUS LONG TERM DISCUSSION...
UPPER RIDGE WILL BE OVER THE AREA MOST OF THE WEEK WITH WARM AND
MAINLY DRY WEATHER. THERE WILL BE SUMMER LIKE TEMPERATURES NEAR 90
MONDAY AND TUESDAY.
ECMWF STILL WANTS TO BRING A BACK DOOR COLD FRONT THROUGH THE AREA
TUESDAY NIGHT WHILE THE GFS KEEP THE FRONT TO THE EAST. THIS HAS
THE ECMWF FORECASTING COOLER TEMPERATURES ON WEDNESDAY. WILL GO
SOMEWHAT COOLER ON WEDNESDAY FOR NOW.
MODELS EVENTUALLY WANT TO BRING AN UPPER LOW/TROUGH INLAND TOWARDS
THE END OF NEXT WEEK. THE FLOW ALOFT IS EXPECTED TO TURN TO THE
SOUTHWEST AROUND THURSDAY ALLOWING FOR SOME INCREASE IN MOISTURE.
WILL MENTION A SLIGHT CHANCE OF THUNDERSTORMS STARTING THURSDAY
AFTERNOON IN THE WEST AND SPREADING TO THE ENTIRE AREA BY FRIDAY.
FORRESTER
&&
.AVIATION...
MAINLY VFR CONDITIONS WILL PREVAIL FOR ALL TAF SITES.
LATELY RIVER VALLEY FOG HAS BEEN ABLE TO MAKE ITS WAY INTO KOLF
BUT SEEMS LESS LIKELY NOW OVER THE NEXT FEW DAYS AS NORTHWESTERLY
SURFACE WINDS AND DRIER ARE ARE EXPECTED TO MOVE THROUGH THE AREA
WITH A COLD FRONT. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE
TODAY AND TONIGHT. WIND SPEEDS WILL BE 10 KNOTS OR LESS TODAY AND
TONIGHT. EXPECT WINDY NORTHWEST WINDS LATER ON SATURDAY...AROUND
20G30KT. BMICKELSON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TO 8 PM MDT SATURDAY FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
430 PM CDT FRI AUG 30 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 430 PM CDT FRI AUG 30 2013
THE MAIN HIGHLIGHTS OF THE NEXT 36 HOURS INCLUDE ONE MORE DAY OF
NOTABLE LATE SUMMER HEAT ON SATURDAY BEFORE READINGS RETURN TO
MORE SEASONAL LEVELS FOR SUNDAY...ALONG WITH STILL HIGHLY-
UNCERTAIN THUNDERSTORM CHANCES BOTH TONIGHT AND ESPECIALLY FOR
SATURDAY NIGHT. WANT TO STATE OFF THE TOP THAT MODELS VARY
CONSIDERABLY ON THE PROBABILITY/COVERAGE OF CONVECTION SATURDAY
NIGHT...AND THUS POPS CONTINUE TO BE CAPPED AT NO MORE THAN 30-40
PERCENT ACROSS THE CWA.
STARTING OFF LATE THIS AFTERNOON...20Z OBJECTIVE SURFACE ANALYSIS
DEPICTS A SURFACE TROUGH/VERY WEAK COLD FRONT STRETCHED FROM
NORTHWEST KS INTO CENTRAL IA...WITH THE VAST MAJORITY OF THE CWA
POSITIONED JUST NORTH OF THIS BOUNDARY. AS A RESULT...BREEZES THIS
AFTERNOON HAVE PREVAILED FROM THE EAST-NORTHEAST AT SPEEDS
GENERALLY AROUND 10 MPH WITH OCCASIONAL HIGHER GUSTS.
HOWEVER...THIS HAS BY NO MEANS BEEN A COOLING NORTHERLY WIND
COMPONENT...AS HIGH TEMPS ARE ON TARGET TO RANGE FROM THE LOW-MID
90S CENTRAL/NORTHEAST...TO THE UPPER 90S TO AROUND 104 IN
SOUTHERN ZONES. FURTHERMORE...THE FAIRLY LIGHT EAST-NORTHEAST
BREEZE HAS ALLOWED DEWPOINTS ACROSS MAINLY THE NORTHEAST 2/3 OF
THE CWA TO REMAIN WELL UP AROUND 70...RESULTING IN POSSIBLY THE
MOST WIDESPREAD COVERAGE OF 100-105 HEAT INDEX VALUES WE HAVE SEEN
ALL WEEK...WITH VALUES IN ALL AREAS LIKELY SAFELY UNDER 100 BY
01Z/8PM. ALOFT...WATER VAPOR IMAGERY SHOWS THE CWA LOCATED
NORTHEAST OF THE CENTER OF THE EXPANSIVE MID/UPPER RIDGE AXIS
CENTERED OVER CO...RESULTING IN NORTH/NORTHWEST FLOW OVERHEAD.
WHILE WATER VAPOR AND MODELED VORTICITY FIELDS HINT AT SOME SUBTLE
PERTURBATIONS HELPING KICK OFF HIGH PLAINS CONVECTION OFF TO OUR
WEST AT THIS HOUR...BY FAR THE MOST NOTABLE SHORTWAVE OF INTEREST
FOR THE NEXT FEW DAYS WEATHER IS SHIFTING EAST INTO SOUTHERN
ALBERTA AT THIS TIME. VISIBLE SATELLITE LATE THIS AFTERNOON SHOWS
ESSENTIALLY CLOUD-FREE SKIES OVER THE VAST MAJORITY OF THE
CWA...WITH ONLY SOME VERY HIGH BASED CUMULUS DEVELOPING FROM
INTENSE HEATING IN OUR FAR SOUTHERN KS ZONES.
TURNING TO THE EVENING/OVERNIGHT HOURS...FROM A BASIC SENSE HAVE
MADE VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. HAVE KEPT LOW
END 20-30 PERCENT STORM CHANCES CONFINED TO ROUGHLY THE NORTHWEST
1/3 OF THE CWA...WITH TWO POSSIBLE SCENARIOS ENVISIONED AND
PORTRAYED BY VARIOUS MODELS. STARTING WITH THE BIG PICTURE
ALOFT...VERY SUBTLE HEIGHT FALLS WILL OCCUR AS THE LARGE RIDGE
AXIS FLATTENS JUST A BIT IN RESPONSE TO THE AFOREMENTIONED CANADIAN
SHORTWAVE TROUGH SHIFTING EAST TO JUST NORTH OF THE MT/ND BORDER
BY SUNRISE. CLOSER TO HOME...VERY SUBTLE MID LEVEL
PERTURBATIONS...POSSIBLY CONVECTIVELY DRIVEN...WILL CONTINUE
SHIFTING EAST TOWARD/INTO THE CWA FROM THE CENTRAL HIGH PLAINS.
SOME MODELS...NAMELY THE HRRR AND 12Z 4KM WRF-NMM...ARE
SURPRISINGLY AGGRESSIVE IN DRIVING HIGH PLAINS CONVECTION EASTWARD
INTO AT LEAST WESTERN PORTIONS OF THE CWA THIS EVENING...BUT WITH
A GENERAL TREND OF KILLING OFF CONVECTION AS IT GETS TOWARD
CENTRAL PORTIONS OF THE CWA LIKELY IN RESPONSE TO INCREASING CINH.
ALTHOUGH A FEW STORMS ARE ALREADY EVIDENT 100+ MILES WEST OF THE
CWA...UNCERTAINTY IS QUITE HIGH WHETHER OR NOT ANY OF THIS WILL
ACTUALLY SLIP INTO OUR AREA...AND THUS OPTED TO KEEP LOW POPS
CONFINED TO WESTERN COUNTIES AND NOT ADVERTISE ANYTHING ACROSS THE
MAJORITY OF THE AREA...BUT THIS WILL NEED WATCHED. LATER IN THE
NIGHT...MODELS SUCH AS THE RAP KICK OFF A POTENTIALLY SEPARATE
AREA OF HIGH-BASED CONVECTION IN OUR NORTHWEST COUNTIES POSSIBLY
IN RESPONSE TO MID-LEVEL THETA-E ADVECTION...BUT AGAIN THIS IS
MAINLY IN THE AREA ALREADY COVERED WITH LOW POPS. IF STORMS
DEVELOP/MOVE IN THIS EVENING/OVERNIGHT...WOULD BE SURPRISED TO SEE
MORE THAN SMALL SUB-SEVERE HAIL. OTHERWISE...BREEZES TONIGHT WILL
AVERAGE VERY LIGHT/EASTERLY...AND MADE LITTLE IF ANY CHANGE TO
OVERNIGHT LOWS WITH MAINLY 66-71.
TURNING TO THE SATURDAY DAYTIME/SATURDAY NIGHT HOURS...AGAIN ON
THE SURFACE THERE HAS BEEN LITTLE NOTICEABLE CHANGE FROM THE
PREVIOUS FORECAST...WITH THE OVERALL BEST CHANCES FOR RAIN/STORMS
DURING THE CURRENT VALID 7-DAY FORECAST ARRIVING SATURDAY
NIGHT...ALTHOUGH BY FAR FROM A SURE THING. ON THE LARGE
SCALE...THE FAIRLY VIGOROUS SHORTWAVE TROUGH ALONG CENTRAL
PORTIONS OF THE U.S./CANADIAN BORDER ON SATURDAY MORNING WILL
SLIDE EAST-SOUTHEAST TO OVER/NEAR LAKE SUPERIOR BY SUNRISE SUNDAY
MORNING...WITH THIS WAVE LOWERING HEIGHTS FURTHER OVER THE LOCAL
AREA AND SHUNTING THE RIDGE SLIGHTLY OFF TO THE SOUTHWEST A BIT.
AT THE SURFACE...BY FAR THE BIG STORY IS A LEGITIMATE COLD FRONT
THAT WILL BE FORCED SOUTHWARD INTO THE CENTRAL PLAINS FROM THIS
WAVE. DURING THE DAYTIME HOURS...THERE IS GOOD AGREEMENT THIS
FRONT WILL BE POSITIONED AT LEAST SLIGHTLY NORTHWEST OF THE CWA
THROUGH LATE AFTERNOON...BEFORE PASSING THROUGH SOMEWHAT
AGGRESSIVELY DURING THE NIGHT AS FAR AS SUMMER COLD FRONTS
GO...WITH ALL AREAS EXPECTED TO HAVE A STEADY 10+ MPH NORTH BREEZE
AND INCREASINGLY COOLER/DRIER AIR BY SUNRISE SUNDAY MORNING. DUE
TO THE CWA REMAINING AHEAD OF THE FRONT DURING THE DAY...ONE MORE
HOT/STEAMY AFTERNOON IS IN STORE...WITH MAYBE ONLY A BIT MORE IN
THE WAY OF MID/HIGH CLOUDS POSSIBLE HOLDING SOME AREAS A TAD
COOLER THAN TODAY...BUT STILL AIMING FOR LOW-MID 90S
CENTRAL/NORTHEAST TO NEAR 100 SOUTH/SOUTHWEST...WITH HEAT INDEX
VALUES AGAIN AROUND 100 OR SLIGHTLY HIGHER. AS FOR DAYTIME
CONVECTIVE CHANCES...THERE IS ADMITTEDLY SOME UNCERTAINTY
HERE...AS SOME MODELS SUCH AS THE NAM SUGGEST THAT ESPECIALLY THE
WESTERN 1/2 OF THE CWA COULD SEE SOME LIKELY HIGH-BASED DAYTIME
CONVECTION...EVEN IN THE MORNING...POSSIBLY A CONTINUATION OF SOME
ACTIVITY THAT MIGHT DEVELOP LATE TONIGHT. HOWEVER...FORECAST
SOUNDINGS AND A CONCEPTUAL MODEL OF THIS PATTERN SUGGEST THAT VERY
WARM MID LEVEL TEMPERATURES ARE MORE LIKELY TO INHIBIT DAYTIME
CONVECTION THAN SUPPORT IT. SO ALTHOUGH ITS NO GUARANTEE...LEFT
POPS BELOW THE MENTIONABLE 15+ PERCENT THRESHOLD IN THE MORNING AND
THROUGH MID-AFTERNOON...BUT LEFT SLIGHT CHANCES MAINLY IN THE
WESTERN 1/2 DURING THE LATE AFTERNOON JUST IN CASE SOMETHING CAN
GET GOING IN THE HOT/DEEPLY MIXED AIRMASS AHEAD OF THE FRONT.
CERTAINLY THE BETTER LARGE-SCALE SUPPORT TO BREAK THROUGH THE CAP
AND SUPPORT CONVECTION COMES SATURDAY NIGHT...AS THE SURFACE COLD
FRONT PASSES THROUGH AND IS ACCOMPANIED/FOLLOWED BY A DECENT AXIS
OF MID LEVEL FRONTOGENESIS. EVEN SO...WITH THE MAIN TRACK OF THE
PARENT SHORTWAVE TROUGH TRACKING HUNDREDS OF MILES NORTHEAST OF
THE CWA...THERE ARE PLENTY OF QUESTIONS ABOUT HOW WIDESPREAD THIS
CONVECTION WILL BE. FOR EXAMPLE...WILL IT SWEEP THROUGH FROM
NORTHWEST-SOUTHEAST IN A FAIRLY SOLID LINE AS THE 12Z NAM WOULD
SUGGEST...OR WILL IT BE VERY HIT-AND-MISS AND IN FACT MISS THE
MAJORITY OF THE AREA ALTOGETHER AS THE 12Z 4KM-WRF NMM
REFLECTIVITY PROG WOULD SUGGEST. WITH THIS STILL BEING 24+ HOURS
OUT...OPTED TO PLAY POPS FAIRLY STATUS QUO FOR NOW...CAPPING THEM
IN THE 30-40 PERCENT RANGE GIVEN THIS DEGREE OF UNCERTAINTY.
IF/WHEN STORM FORM...CERTAINLY CANNOT RULE OUT AT LEAST A MARGINAL
SEVERE THREAT...WITH THE NAM ADVERTISING 2000+ J/KG OF CAPE IN THE
850-700MB LAYER IN THE EVENING...BUT IN THE PRESENCE OF ONLY
25-30KT OF DEEP LAYER SHEAR. ITS CERTAINLY POSSIBLE THAT IF ENOUGH
STORMS FORM AND DEVELOP INTO A FORWARD-PROPAGATING LINE THAT AN
ENHANCED WIND THREAT COULD MATERIALIZE...BUT THIS IS ALL
PREDICATED ON HOW WIDESPREAD DEVELOPMENT ULTIMATELY IS. NO MATTER
WHAT...ROUGHLY THE NORTHWEST 1/3 TO 1/2 OF THE CWA SHOULD BE CLEAR
OF STORM CHANCES BY AROUND MIDNIGHT OR SHORTLY THEREAFTER...WITH
THE LATE NIGHT FOCUS IN THE SOUTHEASTERN 1/2. LOW TEMPS BY SUNRISE
SUNDAY ARE FORECAST TO RANGE LOW 60S NORTH TO NEAR 70 FAR
SOUTHEAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 PM CDT FRI AUG 30 2013
MAIN CONCERNS ARE CHANCES FOR THUNDERSTORMS SUNDAY MORNING AND
WEDNESDAY EVENING.
ON THE LARGE SCALE...THE WEATHER PATTERN WILL BE SWINGING TO A
NORTHWEST FLOW REGIME AS THE UPPER LEVEL RIDGE THAT HAS BEEN
PERSISTENT OVER THE AREA THE LAST WEEK OR SO RETROGRADES WEST. THIS
CHANGE IN FLOW WILL RESULT IN TEMPERATURES ABOUT 10 DEGREES COOLER
THAN THIS WEEK AND SOME LOW CHANCES FOR RAIN AS FRONTAL BOUNDARIES
INTERMITTENTLY MOVE THROUGH THE AREA.
MODELS SUGGESTING LINGERING STORMS POSSIBLE EARLY SUNDAY MORNING
BEFORE CONVECTION EXITS SOUTHEAST OF THE AREA. WE LEFT SMALL CHANCES
OF RAIN IN OVER THE EXTREME SOUTHEAST CORNER OF THE CWA SUNDAY
MORNING AS THE FRONT SAGS OUT OF THE AREA. ALL MODELS SUGGEST A
CHANCE FOR STORMS WEDNESDAY EVENING AS ANOTHER COOL FRONT MOVES
THROUGH THE AREA. THERE IS A MARGINAL THREAT THAT A FEW OF THE
STORMS MAY PRODUCE SMALL HAIL AND GUSTY WINDS WEDNESDAY NIGHT
DUE TO LOW TO MARGINAL INSTABILITY AND WEAK SHEAR.
OTHER THAN THOSE TWO PERIODS...HIGH PRESSURE SHOULD BE THE DOMINANT
WEATHER FEATURE. SO DRY AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS WILL
BE THE RULE MOST DAYS.
&&
.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1218 PM CDT FRI AUG 30 2013
EXPECT NORTHEASTERLY FLOW TODAY AS A WEAK SURFACE TROUGH HAS
TRANSITED THE AREA. BOTH CEILINGS AND VISIBILITIES ARE EXPECTED TO
REMAIN VFR THROUGH THE PERIOD. A FEW MODELS ARE HINTING AT A
CHANCE FOR PRECIPITATION OVERNIGHT. CONFIDENCE IS CURRENTLY LOW AS
TO WHETHER IT WILL REACH THE GRI AIRPORT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...EDDY
AVIATION...BEDA
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
308 PM CDT FRI AUG 30 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
TONIGHT THROUGH SATURDAY...A WEAK UPPER LEVEL DISTURBANCE...
CURRENTLY ACROSS THE WYOMING...WILL MOVE ACROSS THE FCST AREA
TONIGHT SPAWNING A FAIRLY ORGANIZED AREA OF TSTMS. ALL MODELS SHOW
K INDICES INCREASING TO AROUND 40C OR GREATER. THE RAP AND OTHER
MODELS SHOW PRECIPITABLE WATER INCREASING TO 1.50 INCHES OR
GREATER. FCST STORM MOTION OF 10KT OR LESS WOULD SUPPORT LOCALLY
HEAVY RAINFALL AND WEAK WINDS ALOFT 30KT OR LESS AT AND BELOW
300MB SUGGEST OUTFLOW DOMINANT COLD POOL DRIVEN BOW SEGMENTS
CAPABLE OF GUSTY WINDS.
LOW LEVEL EASTERLIES AND WEAK WESTERLIES ALOFT PRODUCE BULK SHEAR OF
35 TO 40 KT SO SOME STORMS THIS EVENING COULD BECOME SEVERE WITH
WIND DAMAGE AND LARGE HAIL. SPC PROVIDED THIS DISCUSSION AT 227 PM
CDT...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK
HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE
ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE
SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING
MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG
SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE
REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH
AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO
RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE
NEXT HOUR OR TWO.
THE STORM COMPLEX COULD MOVE MOSTLY EAST ACCORDING TO THE RAP MODEL
OR TAKE A SOUTHEAST TURN AS INDICATED BY THE HRRR. EITHER WAY THE
CONVECTION WILL AFFECT MOST OF THE FCST AREA AND EXIT SOUTH OR EAST
BY AROUND 12Z.
THIS TSTM COMPLEX SHOULD SET UP A FRONTAL BOUNDARY FOR ADDITIONAL
STORM DEVELOPMENT SATURDAY AFTN AND BEYOND WITH THE BEST SHEAR AND
INSTABILITY ACROSS NCNTL NEB NEAR KANW AND KONL. THE MODELS HAVE A
TOTALLY DIFFERENT IDEA IN MIND WITH THE FRONT AND LIFT IT RAPIDLY
NORTH BY 15Z SATURDAY MORNING AND THEN DROP ANOTHER COLD FRONT
THROUGH DURING THE AFTN. SO THERE IS A DISCONNECT IN CONVENTIONAL
STORM THEORY VS THE MODELS. IF THE FRONT IS DOES NOT RETREAT NORTH
AS QUICKLY THAN STORM DEVELOPMENT COULD BE MUCH FARTHER
SOUTH...PERHAPS OVER KS. THE FCST USES A BLEND OF NAM...GEMREG...GFS
AND ECM FOR A 30 POP FROM 20Z ONWARD...MAINLY SOUTH AND EAST OF
KVTN/KIML.
TEMPERATURES ARE A BLEND OF TRIED AND TRUE MODEL DATA PLUS BIAS
CORRECTION FOR HIGHS IN THE LOWER 90S NORTH TO UPPER 90S SOUTH.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
SATURDAY NIGHT THROUGH LABOR DAY...
COLD FRONT SHOULD STRETCH FROM NEAR ANW THROUGH LBF AND IML EARLY
SATURDAY EVENING. DO EXPECT SCATTERED SHOWERS AND THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT. COVERAGE MAY END UP LESS ACROSS SWRN
NEBR WHICH WILL BE FURTHER REMOVED FROM COOLER TEMPERATURES ALOFT
ASSOCIATED WITH MAIN UPPER TROUGH ACROSS MINNESOTA. ONLY A SLIGHT
CHANCE FOR THUNDERSTORMS FAR SOUTHEAST AFTER MIDNIGHT. DRY AND
LESS HOT SUNDAY AND LABOR DAY. HIGHS SUNDAY FORECAST VERY NEAR
PREVIOUS FROM NEAR 83 NCTRL AND 85 TO 88 SOUTHWEST. NORTHERLY WINDS
SUNDAY LOOK FAIRLY LIGHT FROM 5 TO 15 MPH WEST AND 10 TO 20 MPH
EAST. ON LABOR DAY...NORTHWEST FLOW ALOFT WILL CONTINUE WITH A
RETURN SOUTHEAST FLOW AT THE SURFACE AND HIGHS FROM NEAR 83
NORTHEAST TO NEAR 90 WEST TIER. SOUTHERLY WINDS MONDAY FROM 10 TO
20 MPH WEST TO 5 TO 15 MPH EAST.
ON TUESDAY THROUGH FRIDAY...
A HEAT UP AGAIN LIKELY AS UPPER RIDGE PERSISTS OVER COLORADO AND
TROUGHING INCREASES ACROSS THE PAC NW AND NORTHEASTERN U.S. A WEAK
COLD FRONT AND DISTURBANCE IN NORTHWEST FLOW ALOFT INDICATED BY
THE GFS AND ECMWF. THIS FRONT ASSOCIATED WITH A DEEP UPPER LOW
MOVING ACROSS HUDSON BAY. AS A RESULT OF ECMWF CONSISTENCY AND
FAIR AGREEMENT BY THE GFS...WILL INTRODUCE A SLIGHT CHANCE FOR
THUNDERSTORMS WEDNESDAY NIGHT. AN OTHERWISE DRY EXTENDED. HIGHS
FORECAST IN THE UPPER 80S TO LOW 90S MOST AREAS WITH MID 90S PARTS
OF SWRN NEBR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI AUG 30 2013
ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB
THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB
BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN
AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING
TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALESCE NORTH
AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY
SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1222 PM CDT FRI AUG 30 2013
.SYNOPSIS...
ISSUED AT 345 AM CDT FRI AUG 30 2013
A STAGNANT H5 PATTERN REMAINS IN PLACE ACROSS THE CENTRAL CONUS
TONIGHT WITH A BROAD RIDGE OF HIGH PRESSURE EXTENDING FROM THE
SRN ROCKIES WELL INTO CENTRAL CANADA. WV IMAGERY ATTM IS
INDICATING A COUPLE OF SHORTWAVES...THE FIRST OVER EASTERN
KANSAS...AND A SECOND OVER UTAH AND SWRN WYOMING. AT THE
SURFACE...A WEAK FRONTAL BOUNDARY HAS PUSHED INTO NORTH CENTRAL
AND WESTERN NEBRASKA THIS EVENING...WHICH HAS INCREASED DEW
POINTS INTO THE MID AND UPPER 60S...AND RESULTED IN LIGHT
NORTHERLY WINDS. TEMPERATURES AS OF 3 AM CDT...RANGED FROM 65 AT
NORTH PLATTE...TO 74 AT ONEILL AND AINSWORTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT FRI AUG 30 2013
TODAY AND TONIGHT...FORECAST CHALLENGES OVER THE NEXT 24 HOURS
ARE TEMPERATURES TODAY...AND PRECIPITATION CHANCES TONIGHT. FOR
TODAY...SOME LIMITED RELIEF FROM THE TRIPLE DIGIT HEAT WILL BE
SEEN NORTH OF THE FRONTAL BOUNDARY ACROSS NORTHERN NEBRASKA THIS
AFTERNOON...AS HIGHS TOP OUT IN THE MIDDLE 90S. SOUTH OF THE
FRONT...TEMPS WILL SURGE TOWARD THE CENTURY MARK...TOPPING OUT AT
99 FOR NORTH PLATTE AND OGALLALA AND 102 FOR IMPERIAL. LATER THIS
AFTERNOON...THE BEFORE MENTIONED FRONTAL BOUNDARY...WILL LIFT TO
THE EAST AS A WEAK WARM FRONT. MID LEVEL LIFT WILL BEGIN TO
INCREASE LATE THIS AFTERNOON AND THIS EVENING AS MID LEVEL WARM
AIR ADVECTION INCREASES IN ADVANCE OF AN APPROACHING SHORT WAVE
TROUGH. MID LEVEL LIFT...COMBINED WITH LOW LEVEL CONVERGENCE
INVOF OF THE FRONT...WILL INCREASE THE THREAT FOR THUNDERSTORMS
LATER THIS AFTERNOON IN THE NORTHWEST...TRANSITIONING EAST TO THE
REMAINDER OF THE FORECAST AREA THIS EVENING. THE ONE LIMITING
FACTOR...MAY BE CAP STRENGTH...ESPECIALLY IN THE SRN CWA...AND
FOR THAT REASON...WILL LIMIT POPS TO SLIGHT CHANCE ATTM...AS
THUNDERSTORM INITIATION IS CONDITIONAL ATTM. ONE DISCLAIMER
THOUGH...IF STORMS CAN FIRE...SURFACE TO H400 SHEAR TOPS OUT AT
40 KTS THIS EVENING...SO SOME STRONG TO LOW END SEVERE STORMS MAY
BE POSSIBLE...ESPECIALLY OVER NORTHERN NEBRASKA.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 345 AM CDT FRI AUG 30 2013
SATURDAY IS EXPECTED TO BEGIN WITH PARTLY TO MOSTLY SUNNY SKIES.
COLD FRONT WILL BE PUSHING INTO FAR NW NEB. BY AFTERNOON HEATING
ALONG AND AHEAD OF THE FRONT SHOULD BE ENOUGH TO BREAK THROUGH
THE CAP. WITH THE INCREASING OF CLOUDS BY MID TO LATER
AFTERNOON...HAVE TEMPS ONLY GOING INTO THE LOWER TO MID 90S
NORTHERN AND UPPER 90S SOUTH. FRONT IS SLOWER WITH THE 00Z RUN SO
HAVE DELAYED ONSET OF POPS UNTIL THE AFTERNOON. SATURDAY NIGHT
THE FRONT WILL BE CROSSING THE REST OF THE CWA...WITH DECREASING
CLOUDS AND AN END TO POPS BEHIND THE FRONT.
SUNDAY AND LABOR DAY WILL BE PLEASANT DAYS AS COOLER HIGH
PRESSURE SETTLES IN BEHIND THE FRONT. 850 MB TEMPS DROP TO AROUND
20 DEGREES WITH GUIDANCE SHOWING HIGHS IN THE 80S...WHICH IS
SEASONAL. SUBSIDENCE BEHIND THE FRONT WILL LIMIT CLOUDS AND HIGH
PRESSURE WILL KEEP AFTERNOON WINDS AROUND 15 MPH OR LESS.
BY TUESDAY THE MODELS ARE IN GOOD AGREEMENT BRINGING AN UPPER
LEVEL CLOSED LOW TOWARDS THE PAC NW WEST...WHICH STALLS THROUGH
MID WEEK...DUE TO THE BLOCKING RIDGE. SOME DIVERGENCE OF THE
MODELS THEN AS THE GFS BRINGS IT ONSHORE INTO WA/OR...WHILE THE
EC LIFTS THE LOW INTO SW CANADA. DOWN STREAM IS A
PERSISTENT/BLOCKING RIDGE WHICH REPOSITIONS ITSELF OVER THE
CENTRAL ROCKIES INTO THE HIGH PLAINS. HEIGHTS INCREASE QUICKLY
FOR TUESDAY AND TEMPS SHOULD WARM BACK INTO THE 90S FOR MOST
AREAS. RIDGE THAT REDEVELOPS IS NOT QUITE AS STRONG AS CURRENT
AND THINK HIGHS WILL GENERALLY REMAIN BELOW 100. ALSO WE ARE
GETTING INTO THE FIRST WEEK OF SEPTEMBER WITH SHORTER DAYLIGHT
HOURS AND LESS OCCURRENCES OF TRIPLE DIGITS. STILL HAVE A FEW
RECORDS AT 100 OR ABOVE SO IT WILL BE POSSIBLE AND NEED TO BE
WATCHED. CURRENT FORECAST IS CLOSE TO GUIDANCE WHICH IS HIGHEST
IN THE SW NEB...WITH MID 90S. THE STORM TRACK LOOKS TO RIDE THE
RIDGE AND CROSS THE DAKOTAS SO A DRY FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI AUG 30 2013
ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB
THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB
BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN
AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING
TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALECSE NORTH
AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY
SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CLB
SHORT TERM...CLB
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
915 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.UPDATE...HAVE GONE AHEAD AND EXPANDED THE FLASH FLOOD WATCH TO
INCLUDE ALL OF SAN BERNARDINO COUNTY...THE SOUTHERN AREAS OF THE
COLORADO RIVER VALLEY AND THE WHITE MOUNTAINS OF INYO COUNTY. PLENTY
OF MOISTURE AVAILABLE WITH MOST OF THE PW SENSORS READING BETWEEN
1.75 AND 2.00 INCHES. SO FAR THIS MORNING SHOWERS AND THUNDERSTORMS
HAVE MAINLY BEEN CONFINED TO CENTRAL CLARK COUNTY WHERE THERE HAS
BEEN SOME ENHANCEMENT FROM A DISTURBANCE MOVING THROUGH ARIZONA. ONLY
ISOLATED ACTIVITY ELSEWHERE...BUT COVERAGE IS EXPECTED TO INCREASE
THIS AFTERNOON ESPECIALLY IN AREAS THAT ARE SEEING PLENTY OF
SUNSHINE THIS MORNING WHICH IS BASICALLY THE FAR WESTERN AND
NORTHERN AREAS OF THE CWA. AREAS UNDER THE CLOUD COVER COULD BE
DELAYED IN SEEING CONVECTION UNTIL LATER THIS AFTERNOON.
&&
.PREV DISCUSSION...
225 AM PDT FRI AUG 30 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR CAZ519>527.
&&
$$
UPDATE...GORELOW
SHORT TERM/AVIATION...STACHELSKI
LONG TERM...HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
638 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.UPDATE...SHOWERS AND THUNDERSTORMS HAVE DEVELOPED FARTHER WEST THAN
EXPECTED THIS MORNING WITH MEASURABLE RAIN HAVING MOVED INTO
HENDERSON. UPDATED THE FORECAST TO ACCOUNT FOR THIS TREND.
&&
.PREV DISCUSSION...
225 AM PDT FRI AUG 30 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS
EVENING FOR AZZ001-003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519-520-522-524.
&&
$$
UPDATE...HARRISON
SHORT TERM/AVIATION...STACHELSKI
LONG TERM...HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
225 AM PDT FRI AUG 30 2013
.SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND
WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE
PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD
RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO
DECREASE SLIGHTLY FROM MONDAY ONWARD.
&&
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE
CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY
AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR
NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO
COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT
DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND
THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS
MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF
THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO
OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT
REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED
ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS
COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY
OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA.
AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE
DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND
INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL.
SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH
PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA,
WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15
ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT
LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY
PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR
ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S
OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE
WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE
AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN
75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS
TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND
ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK,
SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT
THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS
WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN
ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE
WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY
THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS,
THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS
VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR
ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY
OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING,
HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD
IMPACT THE FORECAST FOR SATURDAY.
AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE
SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT
WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE
POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON
SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY
THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM
ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL
HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS
SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH
LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH.
FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY,
BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN
WILL BE FLASH FLOODING.
TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE
NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF
FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS.
DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE
HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW
ON PICKING UP ON THIS.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD
AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON
PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE
IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA
WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST.
SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE
AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE
FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE
STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE
WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND
TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND.
THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS
EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN
PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY
GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND
KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE
FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A
WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY.
&&
.AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE
VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND
TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS
AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR
NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY
OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT
OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR
OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY
SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR
ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND
ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE,
CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES.
SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF
THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER.
WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS
AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ016>022.
AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS
EVENING FOR AZZ001-003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519-520-522-524.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
941 PM PDT THU AUG 29 2013
.SYNOPSIS...A FAVORABLE UPPER LEVEL FLOW PATTERN WILL CONTINUE TO
BRING MONSOON MOISTURE INTO THE AREA THROUGH THE MIDDLE OF NEXT WEEK
AND RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. THE
PRIMARY HAZARD WITH STORMS...ESPECIALLY THROUGH SUNDAY...WILL BE
HEAVY RAINFALL THAT COULD RESULT IN DANGEROUS FLASH FLOODING.
&&
.UPDATE...THE LATEST RADAR SHOWS THE CONVECTIVE COMPLEX THAT GOT
GOING OVER MOHAVE COUNTY HAS PUSHED INTO SAN BERNARDINO COUNTY BUT
DECREASED IN AREAL COVERAGE. THIS ACTIVITY WILL CONTINUE TO MOVE
WESTWARD BUT BASED ON THE HRRR AND RADAR TRENDS SHOULD START TO FALL
FURTHER APART AS IT REACHES CENTRAL SAN BERNARDINO COUNTY. THE MAIN
THREAT WILL CONTINUE TO BE HEAVY RAINFALL AND I WILL LEAVE THE FLASH
FLOOD WATCH UP UNTIL IT EXPIRES AS THIS CONVECTION IS STILL OUT
THERE. BEHIND THE LEADING EDGE OF THUNDERSTORMS...MAINLY LIGHT RAIN
WAS FALLING ACROSS MOHAVE AND FAR EASTERN SAN BERNARDINO COUNTY AND
THIS SHOULD GRADUALLY WIND DOWN OVERNIGHT. I WENT AHEAD AND REMOVED
POPS OR LOWERED THEM GREATLY ACROSS THE NORTHERN TWO-THIRDS OF THE
AREA FOR THE REST OF TONIGHT AS WE HAVE LOST HEATING AND THERE IS NO
ORGANIZED FEATURE CLOSE ENOUGH TO INITIATE CONVECTION IN THESE AREAS.
VERY STICKY AIR IS IN PLACE ACROSS OUR AREA WITH DEW POINTS WELL
INTO THE 60S AND EVEN 70S ACROSS THE MOJAVE DESERT. JUST OUTSIDE OF
OUR AREA THE DEW POINT AT BLYTHE, CALIFORNIA SPIKED TO 79 DEGREES
THIS EVENING WHICH IS ABOUT AS HIGH AS ONE WILL SEE OUT HERE IN THE
WEST AND EVEN VERY IMPRESSIVE FOR OUT EAST. I WENT AHEAD AND
ADJUSTED DEW POINTS UP OVERNIGHT A FEW DEGREES BASED ON CURRENT
OBSERVATIONS.
WITH RESPECT TO TOMORROW, I WILL TAKE A CLOSER LOOK AT THIS FOR THE
MORNING PACKAGE. FROM WHAT I HAVE LOOKED AT SO FAR, THE WRF SUGGESTS
LOTS OF LIGHT QPF ACROSS ALL OF MOHAVE COUNTY WHICH SEEMS WACKY BUT
MAY NOT BE TOO FAR OFF IF WE WIND UP STAYING CLOUDY THERE OVERNIGHT
AND FRIDAY MORNING. THE STEERING FLOW FROM THE WRF AND GFS IS SHOWN
TO BE LIGHT EAST WHICH WOULD FAVOR CONVECTION HEADING IN FROM WHAT
DEVELOPS OVER NW ARIZONA AND SW UTAH. THE LATEST MODELS ALSO FAVOR
ACTIVITY DEVELOPING OVER THE SPRING MOUNTAINS AND ACROSS INTO
COUNTY. AGAIN WITH SO MUCH MOISTURE AVAILABLE, FLASH FLOODING WILL
BE THE MAJOR CONCERN WITH STORMS, THE BIG QUESTION IS WHAT HAPPENS
TO ALL THE DEBRIS CLOUDS IN PLACE TONIGHT. IF THEY CAN CLEAR BY THE
LATE MORNING, WE WILL HAVE AMPLE HEATING AND SUFFICIENT INSTABILITY
FOR THUNDERSTORMS TO POP-UP ACROSS THE ENTIRE AREA. I WILL HOLD OFF
ON ANY NEW FLASH FLOOD WATCHES AT THIS TIME UNTIL I HAVE A BETTER
CHANCE TO INSPECT THE MODELS.
&&
.AVIATION...FOR MCCARRAN...DRY CONDITIONS ARE EXPECTED OVERNIGHT
WITH WINDS FAVORING TYPICAL DIURNAL TRENDS. SHRA/TSRA ARE EXPECTED
TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z.
SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION
IN THE AFTERNOON SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST
CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW
BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE
COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW
BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN
CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY
SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SHRA/TSRA SHOULD MAINLY BE ACROSS MOHAVE AND SAN
BERNARDINO COUNTIES OVERNIGHT WITH LITTLE TO NO ACTIVITY ELSEWHERE.
SCT-BKN CLOUDS AOA 10K-15K FEET SOUTH OF KDAG-KLAS-KSGU LINE WITH
FEW IF ANY CLOUDS TO THE NORTH. ON FRIDAY...SHRA/TSRA ARE EXPECTED
ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z WITH THE GREATEST
COVERAGE ACROSS MOHAVE, CLARK AND INYO COUNTIES. SHRA AND TSRA
SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA.
SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD
FAVOR TYPICAL DIURNAL TRENDS THROUGH FRIDAY EVENING BUT COULD BE
GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA.
&&
.PREVIOUS UPDATE...
ISSUED AT 629 PM PDT THU AUG 29 2013
.UPDATE...MOST OF THE ACTION RIGHT NOW IS ACROSS MOHAVE COUNTY WHERE
CONVECTION IS PROPAGATING WESTWARD. A PSEUDO-LINE OF CONVECTION
PRESENTLY STRETCHED FROM NEAR DOLAN SPRINGS SOUTHWEST TOWARD ALAMO
DAM AND LOOKS TO HAVE ENOUGH MOMENTUM TO KEEP GOING TOWARD THE
COLORADO RIVER VALLEY. I WENT AHEAD AND INCREASED POPS BY 20-30
PERCENT IN THIS AREA BASED ON THE LATEST RADAR TRENDS. HEAVY RAIN
WILL BE THE PRIMARY HAZARD WITH STORMS IN THIS AREA, HOWEVER, GUSTY
WINDS WILL ALSO BE A CONCERN IN SPOTS. ELSEWHERE ACTIVITY IS IN THE
ISOLATED RANGE AND SHOULD START TO WIND DOWN AS WE LOOSE DAYTIME
HEATING. WE WILL NEED TO KEEP AN EYE ON SOUTHERN CLARK AND EASTERN
SAN BERNARDINO COUNTY LATER THIS EVENING TO SEE WHAT GOES ON ONCE
THE CONVECTION IN MOHAVE COUNTY GETS CLOSER TO THE BORDER.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 237 PM PDT THU AUG 29 2013
.SHORT TERM...MAINLY ISOLATED THUNDERSTORMS SO FAR THIS AFTERNOON
HOWEVER EXPECTATIONS ARE FOR SOUTHERN MOHAVE AND EASTERN SAN
BERNARDINO COUNTIES TO FILL IN BASED ON STORM ACTIVITY JUST OUTSIDE
OF THE CWA AND LATEST SATELLITE TRENDS. REGARDING THESE ISOLATED
STORMS...IT IS VERY APPARENT THEY ARE LOW MOVING AND EFFICIENT RAIN
PRODUCERS. THE RADAR ESTIMATED RAIN RATES AND OBSERVED GAGE DATA ARE
QUITE IMPRESSIVE. ANY STORM THAT DEVELOPS HAS THE POTENTIAL TO
UNLOAD AND CREATE PROBLEMS QUICKLY SO REMAIN AWARE.
TONIGHT THROUGH SUNDAY...SCATTERED TO NUMEROUS HEAVY RAIN PRODUCING
SHOWERS AND THUNDERSTORMS ARE EXPECTED IN THE WATCH AREAS THIS
EVENING WITH MORE ISOLATED...BUT EQUALLY INTENSE...STORM COVERAGE
ELSEWHERE. STORMS EVERYWHERE ARE EXPECTED TO DIMINISH IN INTENSITY
AND COVERAGE OVERNIGHT. SIMILAR CONDITIONS ARE IN PLACE FOR SATURDAY
AND SUNDAY REGARDING AVAILABLE MOISTURE AND INSTABILITY. HOWEVER...
OVERALL COVERAGE COULD BE REDUCED IF FORECASTED THICKER CLOUD COVER
BECOMES A REALITY AND LIMITS DAYTIME HEATING. HOPEFULLY THIS WILL BE
CLEARER BY MORNING AND HELP DIMINISH THE CURRENT UNCERTAINTY FOR
ISSUING ANY ADDITIONAL FLASH FLOOD WATCHES FOR FRIDAY AND SATURDAY.
TEMPERATURES ARE GENERALLY EXPECTED TO BE BELOW NORMAL FRIDAY AND
SATURDAY BASED ON EXPECTED LACK OF SUNSHINE BUT COULD EXCEED
FORECASTED NUMBERS IF CLOUD COVER THINS.
.LONG TERM...MONDAY THROUGH THURSDAY...MINIMAL CHANGES MADE TO THE
EXTENDED SINCE OVERALL THINKING IS UNCHANGED. MONSOON MOISTURE WILL
REMAIN IN PLACE THROUGH THE PERIOD...WITH THE DEEPEST MOISTURE
FORECAST OVER MOHAVE COUNTY. THERE REMAINS SOME MODEL AGREEMENT THAT
A BIG RIDGE OVER THE CENTRAL STATES WILL GRADUALLY SHIFT WESTWARD BY
THE MIDDLE OF THE WEEK...RESULTING IN RISING HEIGHTS THAT COULD HELP
WARM TEMPERATURES ALOFT AND CAP THE AIRMASS. OTHERWISE...TYPICAL
MONSOON CONDITIONS ARE EXPECTED EACH AFTERNOON/EVENING MINUS ANY
TROPICAL INFLUENCE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...FLASH FLOOD WATCH FROM NOON MST TODAY THROUGH THIS EVENING FOR
AZZ002-003.
CA...FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING FOR
CAZ524>527.
&&
$$
UPDATE...STACHELSKI
PREVIOUS...SALMEN
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
751 PM EDT SAT AUG 31 2013
.SYNOPSIS...
WARM...HUMID AND UNSETTLED WEATHER IS ON TAP FOR THE HOLIDAY WEEKEND
WITH SHOWERS AND THUNDERSTORMS EXPECTED...BEING MOST NUMEROUS THIS
AFTERNOON AND THEN AGAIN ON MONDAY. SOME OF THE THUNDERSTORMS WILL
BRING LOCALLY HEAVY DOWNPOURS...ALONG WITH THE POSSIBILITY OF STRONG
WINDS AND HAIL MONDAY. DRIER AND COOLER WEATHER WILL RETURN FOR THE
LATER HALF OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 739 PM EDT SATURDAY...PREVIOUS FORECAST IS IN GOOD SHAPE.
MAIN CONCERN NEXT SEVERAL HOURS IS POTENTIAL FOR SHOWERS WITH
LOCALLY HEAVY RAINFALL...MAINLY ACROSS CENTRAL/S-CENTRAL VT.
LATEST RAP SHOWS VERY HIGH PW VALUES (1.8-1.9") ACROSS RUTLAND AND
WINDSOR COUNTIES...AND IT APPEARS A WEAK WARM FRONTAL BNDRY
EXTENDS EWD FROM WAVE LOW OVER ESSEX COUNTY NY ACROSS S-CENTRAL
VT. 2-M DEWPOINTS ALSO REFLECT VERY HUMID AIR MASS IN PLACE WITH
DEWPOINTS OF 70F AT BTV AND IN THE LOWER 70S ACROSS S-CENTRAL VT.
HEAVIEST RAINFALL SHOULD BE THRU 03-04Z AS WAVE LOW PUSHES EWD
ACROSS S-CNTRL VT WITH TRAILING WIND SHIFT LINE SWD ACROSS
E-CENTRAL VT. WHILE BETTER INSTABILITY AND ONGOING CONVECTIVE
ACTIVITY IS FOCUSING MORE WIDESPREAD STORMS FURTHER
SOUTH...CONTINUE TO SEE SCATTERED SHOWERS ACROSS CENTRAL AND
S-CENTRAL VT. DESPITE WEAK LAPSE RATES AND LIMITED CAPE...WARM
RAIN PROCESSES FAVORING HEAVY DOWNPOURS WITH THIS ACTIVITY. DUAL-
POL RAINFALL ESTIMATES SHOW LOCALLY 1.5-1.75" AROUND RUTLAND AND
ACROSS N-CENTRAL WINDSOR COUNTY DURING PAST COUPLE OF HRS. WILL
CONTINUE TO MONITOR FOR LOCALIZED FLOODING POSSIBLE ACROSS
RUTLAND/WINDSOR NEXT FEW HOURS. WITH SATURATED AIRMASS...LOTS OF
FOG TONIGHT WITH LIGHT WINDS, HIGH DEWPOINTS, AND LOW TEMPERATURES
ONLY IN THE 60S TO AROUND 70. COULD BE SOME BREAKS IN THE CLOUDS
LATE TO JUST ADD TO FOG POTENTIAL.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 409 PM EDT SATURDAY...
SUNDAY THERE WILL BE LOTS OF LOW LEVEL MOISTURE AND FOG EARLY
GIVING WAY TO PARTLY SUNNY SKIES BY AFTERNOON. WITH THE WEAK
FRONTAL SYSTEM OVER/NEAR OUR AREA A FEW SHOWERS OR THUNDERSTORMS
MAY POP ACROSS PORTIONS OF THE AREA, BUT IN GENERAL EXPECTING MORE
SUN THAN SATURDAY AND WARMER TEMPERATURES IN THE UPPER 70S TO
LOWER 80S.
SUNDAY NIGHT...WARM/MUGGY CONDITIONS CONTINUE WITH LOWS ONLY IN
THE MID TO UPPER 60S. MODELS SHOWING A SHORTWAVE WITH FALLING
HGTS WITH MOISTURE ADVECTING BACK IN LATE SUNDAY NIGHT ALONG
WHATEVER WEAK BOUNDARY REMAINS. THIS WILL BE AFFECTING US MAINLY
06-12Z MONDAY SO HAVE GONE ALONG WITH INCREASED CHANCES OF SHOWERS
AND THUNDERSTORMS OVERNIGHT TOWARD 12Z MONDAY.
ON MONDAY...MODELS CONTINUE TO BE FAIRLY CONSISTENT SHOWING
WIDESPREAD SHOWERS AND THUNDERSTORMS A POTENT SHORTWAVE TROUGH
SHIFTS EASTWARD OF GREAT LAKES REGION ALONG WITH A COLD FRONT.
NORTH COUNTRY CONTINUES TO BE SITUATED IN A VERY WARM/MOIST
AIRMASS WITH SURFACE DEWPOINTS IN THE MID TO UPPER 60S AND
FORECAST MAX TEMPS IN THE UPPER 70S TO MID 80S. THIS WILL PROVIDE
MODEST SURFACE INSTABILITY WITH SBCAPES ON THE ORDER OF 1000-1500
J/KG AND 0-6KM SHEAR GENERALLY 25-30 KTS. THERE CONTINUES TO BE THE
POSSIBILITY OF A COUPLE OF SEVERE STORMS. PWATS REMAIN HIGH IN
THE 1.5-2" RANGE SO LOCALLY HEAVY RAINFALL CONTINUES TO BE A
THREAT.
FRONT IS RATHER SLOW TO MOVE THROUGH THE REGION MONDAY NIGHT SO A
DIMINISHING CHANCE OF SHOWERS AND THUNDERSTORMS OVERNIGHT ALONG
WITH TEMPERATURES IN THE 60S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 414 PM EDT SATURDAY...SFC LOW PRESSURE TO OUR NORTH WILL
CONTINUE TO BRING A COLD FRONT THROUGH THE ERN HALF OF THE FA ON
TUESDAY WITH SOME SCT SHOWERS CONTINUING IN THE FRONTS WAKE AS A
WEAKENING SFC TROUGH MOVES IN BEHIND IT. EXPECT DRYING TREND
TUESDAY NIGHT WITH SOME SLGT SFC RIDGING. 850MB TEMPS OF 10-14C
EARLY TUESDAY WILL COOL TO THE SINGLE DIGITS BY WEDNESDAY
MORNING. SFC MAX TEMPS WILL BE IN THE 70S WITH TUESDAY NGT MIN
TEMPS IN THE 50S.
WEDNESDAY WILL BE DRY WITH CONTINUED SFC RIDGING...BUT CLOUDS
STILL PREVALENT...ESP OVER THE HIGH TRRN AS ANOTHER...STRONGER
FRONT APPROACHES FROM THE WEST. THIS FRONT WILL BRING MORE RAIN
SHOWERS WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. NOT AS MUCH
MOISTURE ASSOCIATED WITH THIS FRONT AS IT DRIES UP EARLY
THURSDAY. LARGE UPPER LEVEL TROUGH WILL CONTINUE TO PRODUCE
CLOUDS OVER THE AREA ON THURSDAY WITH GENERAL NW FLOW KEEPING AT
LEAST SLGT CHC OF SHOWERS OVER THE AREA...ESP THE HIGH TRRN.
WEDNESDAY MAX TEMPS IN THE 70S WITH NOTICEABLY COOLER MIN TEMPS
WEDNESDAY NGT IN THE 40S- M50S.
HIGH PRESSURE BUILDS IN OVER THE SRN GREAT LAKES REGION THURSDAY
NGT...WITH CLEARING SKIES...DRY WEATHER AND MUCH COOLER TEMPS AS
NW FLOW PERSISTS. THE HIGH WILL SLIDE SOUTH AND EAST THRU THE END
OF THE WORK WEEK...ALLOWING FOR DRY MOSTLY CLEAR CONDITIONS OVER
THE NORTH COUNTRY. 850MB TEMPS WILL DROP TO -2C TO 2C EXPECTED ON
THURSDAY. AT THE SFC...MAX TEMPS WILL BE IN THE 60S THURSDAY AND
FRIDAY WITH MIN TEMPS IN THE U30S-NEAR 50 THURSDAY AND FRIDAY
NIGHTS.
LATE FRIDAY NIGHT INTO SATURDAY...ANOTHER COLD FRONT WILL
APPROACH FROM THE NORTHWEST...BRINGING YET ANOTHER CHANCE FOR
SHOWERS...FOLLOWED BY ANOTHER RIDGE OF HIGH PRESSURE SATURDAY
NIGHT INTO SUNDAY.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
THROUGH 00Z MONDAY...WIDESPREAD REDUCTIONS TO MVFR OR LOWER
EXPECTED THIS EVENING AND INTO SUNDAY MORNING...IMPROVING TO VFR
LATE SUNDAY MORNING. AN ABUNDANCE OF LOW LEVEL MOISTURE WILL ALLOW
FOR THE CONTINUANCE OF LOW CEILINGS AND REDUCED VISIBILITIES
THROUGH THE NIGHT. SCATTERED RAIN SHOWERS WILL END FOR THE MOST
PART AFTER 03Z. WILL KEEP VCSH IN THROUGH 12Z AS A LINGERING
ISOLATED RAIN SHOWER OR AREA OF DRIZZLE REMAINS POSSIBLE.
OTHERWISE...EXPECTING LARGELY MVFR CEILINGS AT BTV/PBG...IFR
OR LOWER CEILINGS CONTINUING OR DEVELOPING AT MPV/SLK/RUT...AND
PREDOMINANTLY VFR CEILINGS AT MSS. TRICKY VISIBILITY FORECAST WITH
AREAS OF FOG/BR LIKELY...HOWEVER COVERAGE AND DENSITY IS
QUESTIONABLE GIVEN WIDESPREAD CLOUD COVER. BTV/PBG SHOULD KEEP
VISIBILITIES AT 6SM OR ABOVE FOR THE MAJORITY OF THE NIGHT...WITH
SOME IFR/LIFR FOG LIKELY AT MPV/SLK/MSS/RUT AT LEAST FOR A TIME
TONIGHT. CONDITIONS START IMPROVING AFTER 12Z SUNDAY WITH VFR
EXPECTED AFTER 14Z AT ALL TAF SITES. WINDS WILL BE GENERALLY LIGHT
AND VARIABLE THROUGH THE PERIOD.
00Z MONDAY THROUGH THURSDAY...
00Z MONDAY THROUGH 00Z WEDNESDAY...SCT SHOWERS/STORMS THROUGH
TUESDAY WITH MVFR/IFR POSSIBLE IN HEAVIER ACTIVITY. HIGHEST THREAT OF
PCPN MONDAY/MONDAY EVENING. PATCHY IFR IN BR/FG ALSO POSSIBLE EACH
NIGHT...ESPECIALLY AT MPV/SLK.
00Z WEDNESDAY THROUGH 06Z THURSDAY...TRENDING VFR WITH HIGH
PRESSURE. PATCHY IFR IN FG AT KMPV/KSLK 06-12Z WED.
06Z THURSDAY ONWARD...INCREASING THREAT FOR SHOWERS AND TSTMS AS
COLD FRONT MOVES THROUGH THE AREA FROM NORTHWEST TO SOUTHEAST.
&&
.EQUIPMENT...
AS OF 354 AM EDT SATURDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT
PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL
WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE
INCONVENIENCE.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SISSON
NEAR TERM...BANACOS/SISSON
SHORT TERM...NASH
LONG TERM...KGM
AVIATION...MUCCILLI
EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
354 PM EDT FRI AUG 30 2013
.SYNOPSIS...
THE LABOR DAY HOLIDAY WEEKEND WILL FEATURE WARM, HUMID AND
UNSETTLED WEATHER. SHOWERS AND THUNDERSTORMS ARE EXPECTED, BEING
MOST NUMEROUS SATURDAY AFTERNOON AND MONDAY. SOME OF THE
THUNDERSTORMS WILL BRING LOCALLY HEAVY DOWNPOURS. DRIER AND COOLER
WEATHER WILL RETURN FOR THE LATER HALF OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 330 PM EDT FRIDAY...STILL MONITORING THE APPROACH OF THE
CONVECTIVE CLUSTER MOVING ACROSS EASTERN ONTARIO AND THE GREAT
LAKES. RADAR SHOWING A FEW SMALL T-STORMS DEVELOPING BETWEEN
MASSENA AND OTTAWA, WHICH IS ALSO AN AREA THAT LOCAL ANALYSIS
INDICATES IS MOST UNSTABLE (CAPE APPROACHING 2000 J/KG AND LIFTED
INDEX VALUES LESS THAN -4). ELSEWHERE ACROSS THE REGION, CAPE
VALUES ARE A LITTLE LOWER (1000-1500 J/KG) ALONG WITH SUB-ZERO
LIFTED INDEX VALUES. HOWEVER, HAVEN`T YET SEEN SHOWER DEVELOPMENT.
LIKELY DUE TO MID-LEVEL DRY AIR. HOWEVER WATER VAPOR SHOWS
INCREASING MOISTURE MOVING IN, SO WOULD THINK WE SHOULD BE ABLE TO
POP A FEW INSTABILITY SHOWERS YET THIS AFTERNOON. HAVE KEPT IN
SOME SMALL POPS FOR THE EARLY EVENING FOR THE HIGHER TERRAIN.
OTHERWISE, THE FORECAST REALLY HINGES ON HOW THE CONVECTIVE
CLUSTER WILL EVOLVE TONIGHT AS IT MOVES INTO OUR AREA. MODELS
CONTINUE TO STRUGGLE WITH ALL THE DETAILS, AND THIS LEADS TO LOW
CONFIDENCE IN OVERALL FORECAST DETAILS. DO THINK THE 15Z HRRR HAD
A DECENT HANDLE ON THINGS AND SO HAVE TRIED TO PAINT ITS SCENARIO
IN. BASICALLY ITS FOR CONVECTION TO REACH THE ST LAWRENCE VALLEY
ABOUT 5PM AND WORK ITS WAY EASTWARD DURING THE MID EVENING.
HOWEVER SHORTWAVE SUPPORT APPEARS TO BE WEAKENING AND WITH LOSS OF
SUN, CONVECTION SHOULD DIMINISH AFTER SUNSET AS IT GETS TOWARD
VERMONT. BY MIDNIGHT EXPECT A BROKEN BAND OF SHOWERS -- PERHAPS AN
ISOLATED THUNDERSHOWER -- TO BE DISSIPATING ACROSS THE REGION.
NOT LOOKING FOR ANYTHING STRONG OR SEVERE OR MUCH IN THE WAY OF
HEAVY RAIN (OUTSIDE LOCALIZED DOWNPOUR). SEMI-BROADBRUSHED THE
GRIDDED FORECAST AS SPECIFIC LOCATION AND TIMING IS STILL TOO FUZZY.
SKIES OVERNIGHT WILL TREND MOSTLY CLOUDY. THE DEBRIS CLOUDS WILL
KEEP TEMPERATURES IN THE 60S FOR PRETTY MUCH EVERYONE. ADD ON
DEWPOINTS IN THE 60S, IT WILL BE RATHER MUGGY. THE CLOUDS SHOULD
PRECLUDE MUCH IN THE WAY OF ANY DENSE FOG FROM FORMING.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 330 PM EDT FRIDAY...SATURDAY THE REGION WILL BE SMACK DAB
IN THE CONTINUE WARM AIRMASS THAT WILL ALSO HAVE BECOME JUICED
FROM INCREASED MOISTURE. PRECIPITABLE WATER VALUES SHOULD BE UP
AROUND 1.75". A WEAK SURFACE BOUNDARY WILL BE STRUNG OUT JUST TO
OUR NORTH AND ADD IN OTHER WEAK BOUNDARIES FROM THE LEFTOVER
CONVECTIVE COMPLEX, WE WILL CERTAINLY HAVE PLENTY OF FOCUS
MECHANISMS FOR CONVECTIVE DEVELOPMENT. SHOULD BE ABLE TO SQUEAK
OUT A BIT OF SUNSHINE DURING THE MORNING, SO TEMPERATURES SHOULD
CLIMB QUICKLY THROUGH THE 70S AND PERHAPS INTO THE LOW 80S IN A
FEW SPOTS. THIS WILL PRODUCE ABUNDANT SURFACE BASED INSTABILITY
WITH CAPE VALUES OVER 1500 J/KG AND NEGATIVE LIFTED INDEX VALUES.
TOSS IN A LITTLE UPPER LEVEL ENERGY ZIPPING BY DURING MID- DAY,
AND ALL THE INGREDIENTS ARE IN PLACE FOR DEVELOPMENT OF WIDESPREAD
THUNDERSTORMS. WIND FIELDS ARE NOT ALL THAT STRONG, NOR IS THERE
MUCH SHEAR, SO THE STORMS WILL BE MORE DISORGANIZED BUT CAPABLE OF
PRODUCING SOME LOCALLY HEAVY DOWNPOURS. THIS COULD CAUSE A LITTLE
BIT OF MINOR FLOODING PROBLEMS.
SATURDAY NIGHT - STORMS SHOULD WIND DOWN IN THE EVENING, BUT LOTS
OF CLOUDS WILL REMAIN. ANOTHER WARM/MUGGY NIGHT WITH TEMPERATURES
IN THE MID-UPPER 60S FOR MOST OF US.
SUNDAY - LOOKS LIKE THE QUIETEST WEATHER FOR THE WEEKEND. THAT
SURFACE BOUNDARY SLIDES TO A POINT JUST SOUTH OF HERE, SO EVER SO
SLIGHTLY MORE STABLE CONDITIONS. NO IDENTIFIABLE TRIGGER ALOFT EITHER.
SO THAT SAID, SURFACE DEWPOINTS WILL STILL BE WELL INTO THE 60S,
SO ITS CONTINUED HUMID. SUNSHINE WILL AGAIN RESULT IN CONVECTION
STARTING TO BUBBLE UP BY MID-DAY. HAVE PAINTED INTO THE GRIDS
SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS. COVERAGE WONT BE AS
STUPENDOUS AS ON SATURDAY AND MOST OF US MAY MANAGE TO STAY DRY.
SUNDAYS TEMPERATURES SHOULD RISE INTO THE LOWER TO PERHAPS 80S AS
SUNSHINE OFFSETS A SLIGHTLY COOLER AIRMASS (925MB TEMPERATURES
SHOULD BE 17-19C VS 20-22C THAT WERE OVERHEAD ON SATURDAY)
SUNDAY NIGHT - FAIRLY SIGNIFICANT UPPER TROUGH BEGINS TO DEVELOP
SOMEWHERE TO OUR WEST. SO ALTHOUGH ANY DAYTIME HEATING CONVECTION
SHOULD WIND DOWN IN THE EVENING, BY LATE NIGHT WE MAY SEE
SHOWERS/ISOLATED THUNDERSTORM RETURN TO THE AREA ALL THANKS TO
SOUTHERLY FLOW BECOMING DEEPER AND MORE ESTABLISHED. STILL A
SWEATY/WARM/MUGGY NIGHT WITH ALL THE CLOUDS AND HIGH DEWPOINTS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 PM EDT FRIDAY...CHANGEABLE WEATHER EXPECTED THROUGH THE
EXTENDED FCST PERIOD AS THE PATTERN TRANSITIONS FROM A WARM AND
HUMID AIR MASS WITH WIDESPREAD SHOWERS AND TSTMS ON MONDAY TO
QUIET...DRY CONDITIONS AND BELOW AVERAGE TEMPERATURES BY THE END
OF THE WORK WEEK. IN FACT...CURRENT INDICATIONS ARE THAT THE FIRST
FROST OF THE SEASON IS POSSIBLE THURSDAY NIGHT OR FRIDAY NIGHT
ACROSS THE NRN ADIRONDACKS AND ESSEX COUNTY VT.
THE 12Z GFS REMAINS CONSISTENT WITH PREVIOUS RUNS SHOWING POTENTIAL
FOR WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY AFTN INTO MONDAY
EVENING. UPSTREAM 700-500MB SHORTWAVE TROUGH IS PROGGED TO AMPLIFY
ACROSS THE ERN GREAT LAKES REGION WITH INCREASING SWLY DEEP-LAYER
SHEAR TO 30-35 KTS ACROSS THE NORTH COUNTRY. PRE-EXISTING AIR MASS
SHOULD REMAIN MODERATELY HUMID WITH BOUNDARY LAYER DEWPOINTS IN THE
MID-UPR 60S AND HIGH TEMPS IN THE LOWER 80S IN VALLEY LOCATIONS.
THIS WILL CONTRIBUTE TO MODERATE SURFACE-BASED INSTABILITY WITH CAPE
VALUES 1000-2000 J/KG. MID-LEVEL LAPSE RATES AND LOW-LEVEL SHEAR NOT
GREAT...BUT OVERALL CONDITIONS FAVOR A FEW SVR STORMS MONDAY
AFTN/EARLY EVE WITH LOCALLY DAMAGING WINDS AND MARGINALLY SVR HAIL.
PW VALUES PEAK AROUND 1.70 INCHES 00Z TUESDAY AND SUPPORT LOCALLY
HEAVY DOWNPOURS WITH THE CONVECTIVE STORMS.
SURFACE TROUGH TRANSLATES EWD ACROSS THE AREA DURING MONDAY NIGHT
AND AS INSTABILITY DIMINISHING SHOULD SEE CONTINUED CHANCES FOR
SHOWER ACTIVITY...GRADUALLY LESSENING FROM WEST TO EAST OVERNIGHT.
NOT A FRONT...SO WITH LITTLE LOW-LEVEL CAA AND CONTINUED CLOUDS
SHOULD SEE LOWS MAINLY IN THE LOW-MID 60S.
LINGERING UPPER TROUGH ON TUESDAY...MAY GENERATE ISOLD/SCT SHOWERS
DURING THE AFTN HOURS. STILL WARM WITH HIGHS IN THE MID 70S TO NEAR
80...WITH SLIGHTLY LESS HUMIDITY. ONCE THE UPR TROUGH CLEARS THE
AREA LATE TUESDAY/TUESDAY NIGHT...SHOULD TRANSITION TO MOSTLY CLEAR
CONDITIONS. PROSPECTS GOOD FOR VALLEY FOG ON TUESDAY NIGHT/WED
MORNING AS A RESULT WITH LOWS IN THE 50S TO AROUND 60.
WED-FRI: WEDNESDAY...LOOKS DRY AND MOSTLY SUNNY WITH SW-NE ORIENTED
LOW-LEVEL RIDGE AXIS IN PLACE. SHOULD SEE NEAR SEASONABLE HIGHS IN
THE MID 70S. A COLD FRONT SLIDES SEWD ACROSS THE REGION ON
THURSDAY...AND SHOULD BE ASSOCIATED WITH A NARROW BAND OF SHOWERS
THURSDAY AFTN. SHOWING 30 POPS WITH THIS FEATURE FOR THURSDAY AFTN.
IN THE WAKE OF THE COLD FRONT...STRONGER CAA AND SHOULD SEE LOWS
DOWN INTO THE 40S THURSDAY NIGHT WITH HIGHS 62-68F ON FRIDAY. LARGER
SFC ANTICYCLONE BUILDS IN THU NIGHT THRU FRIDAY...AND OVERALL
PATTERN MAY ALLOW A FROST TO OCCUR THU NIGHT OR FRIDAY NIGHT IN THE
COLDER SPOTS WITHIN THE NRN ADIRONDACKS AND IN THE SHELTERED VALLEYS
OF THE NORTHEAST KINGDOM...ESPECIALLY IN ESSEX COUNTY VT. GOOD
POTENTIAL AGAIN FOR RIVER VALLEY FOG THURSDAY NIGHT AND FRIDAY
NIGHT BASED ON SYNOPTIC PATTERN AND ASSOCIATED CLIMATOLOGY.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
THROUGH 18Z SATURDAY...VFR AT ALL TERMINALS EARLY THIS AFTN AS
LOW CLOUDS HAVE MIXED OUT WITH DAYTIME HEATING. MAIN FOCUS NOW IS
ON UPSTREAM SHOWER ACTIVITY IN ADVANCE OF SHORTWAVE TROUGH
CROSSING LAKE HURON AND SERN ONTARIO AT 17Z. SCATTERED SHOWERS
WILL LIKELY IMPACT SLK/MSS BETWEEN 20-23Z...WITH A SLIGHT CHANCE
OF A TSTM. A BIT MORE DIFFICULT TO TELL IF TAF SITES FROM THE
CHAMPLAIN VALLEY EWD WILL BE AFFECTED...BUT CERTAINLY A CHANCE
22-02Z OF A SHOWER OR T-STORM WITH BRIEF MVFR CONDITIONS. HAVE
OPTED TO LEAVE OUT OF THE TAFS ATTM FROM PBG EASTWARD GIVEN
GREATER UNCERTAINTY. WINDS THRU THIS EVENING WILL BE FROM THE S-SW
AT 5-10 KTS...EXCEPT LOCALLY SE 10 KTS AT PBG WITH THE ONGOING
LAKE BREEZE. GREATER POTENTIAL FOR MID-LEVEL CLOUDS TONIGHT...SO
OPTED NOT TO INCLUDE FOG MENTION GIVING BKN-OVC100-120. ADDITIONAL
SHORTWAVE TROUGH AND ASSOCIATED SFC TROUGH MOVE THRU WITH
POTENTIAL FOR MORE WIDESPREAD SHOWERS AND TSTMS...ESPECIALLY
DURING SATURDAY AFTN. AT THIS POINT...INCLUDED MORNING MENTION OF
SHRA AT SLK/MSS...AS THEY WILL LIKELY SEE SOME ACTIVITY BEFORE THE
END OF THE TAF PERIOD. REMAINING SITES HAVE BEST CHANCE FOR
SHOWERS/TSTMS AFTER 18Z SATURDAY.
18Z SATURDAY THROUGH WEDNESDAY...SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THRU THE AVIATION OUTLOOK PERIOD.
FIRST SFC/UPR TROUGH BRINGS WIDESPREAD SHOWERS AND T-STORMS DURING
SATURDAY AFTN AND EVENING. SHOULD SEE BRIEF INTERVALS OF MVFR AND
POSSIBLE BRIEF IFR AT ALL TAF LOCATIONS ASSOCIATED WITH THE
CONVECTIVE ACTIVITY. ANY PRECIPITATION SHOULD BE ISOLD
SUNDAY...WITH MAINLY VFR CONDITIONS DURING THE DAYLIGHT HRS. ANOTHER
STRONG UPR TROUGH APPROACHES THE REGION FROM THE WEST DURING
MONDAY/MONDAY NIGHT...LIKELY RESULTING IN NUMEROUS ADDITIONAL
SHOWERS AND TSTMS...ESPECIALLY MONDAY AFTN/EVE. DURING THESE
HIGHER THREAT PERIODS A FEW OF THE STORMS COULD TREND STRONG WITH
GUSTY WINDS/TURBULENCE/FRQ LIGHTNING. SCATTERED SHOWERS POSSIBLE
TUESDAY AND TRENDING DRIER FOR WEDNESDAY. PATCHY BR/FG AND ASSOC
MVFR/IFR CONDS ALSO POSSIBLE FROM 06-12Z EACH MORNING...WITH
HIGHEST CONFIDENCE AT MPV AND SLK.
&&
.EQUIPMENT...
AS OF 342 AM EDT FRIDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT
PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL
WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE
INCONVENIENCE.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...NASH
NEAR TERM...NASH
SHORT TERM...NASH
LONG TERM...BANACOS
AVIATION...BANACOS
EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
332 PM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
315 PM EDT UPDATE...
MADE MINOR ADJUSTMENTS TO PREVIOUS FORECASTS. MODELS THIS
AFTERNOON AGAIN ARE IN GOOD AGREEMENT WITH MID WEEK BUT DISAGREE
GREATLY IN THE EXTENDED. SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH LATE TUESDAY NIGHT. WENT WITH MORE OF A ECMWF/CMC
BLEND. LEANED MORE TOWARDS ECMWF GUIDANCE SINCE THIS MODEL HAS
BEEN MOST CONSISTENT WITH PREVIOUS RUNS. TUESDAY A COLD FRONT WILL
PASS THROUGH THE REGION BRINGING CAA TO THE NE PA AND C NY. MODELS
STILL DIFFER GREATLY IN THE EXTENDED SO WENT WITH A CONSERVATIVE
PERSPECTIVE TO TEMPS WITH LOWS IN THE UPPER 40S TO LOW 50S AND
HIGHS IN THE UPPER 60S TO LOW 70S WED THRU FRIDAY.
PREVIOUS UPDAT...
430 AM FRI...
LITTLE TO CHANGE FROM THE PREVIOUS FORECAST FROM YESTERDAY
AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD AGREEMENT WITH A
TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF COOLER WEATHER
THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES THROUGH THE AREA
WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING WITH RESPECT TO
WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE WEEK. THE NEW 0Z
EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS AS CHILLY AS -2C
BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS HAS 850 TEMPS OF
+16C DURING THE SAME TIME. TALK ABOUT A DIFFERENCE! NO CLEAR SIGN
WHICH WAY TO LEAN AT THIS POINT WITH THE CANADIAN FAVORING THE
GFS...WHILE SOME OF THE GFS ENSEMBLES FAVORING THE EURO. WILL BE
FUN TO WATCH AS WE TURN TOWARD FALL. THE PREVIOUS AFD IS BELOW...
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
145 PM EDT UPDATE...
THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS
THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS
TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS
OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE
TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING
INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW.
TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL
DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS
PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO
EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE
EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN
TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED
TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED
THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT
CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT.
OUTLOOK...
SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...KAH/EH
AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
209 PM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST
FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD
AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF
COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES
THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING
WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE
WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS
AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS
HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A
DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE
CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES
FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL.
THE PREVIOUS AFD IS BELOW...
PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE
PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF
CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES
EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM
THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO
MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT.
THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN
PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW.
THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY
BRINGING A COLD FRONT TO THE AREA.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
145 PM EDT UPDATE...
THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS
THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS
TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS
OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE
TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING
INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW.
TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL
DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS
PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO
EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE
EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN
TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED
TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED
THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT
CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT.
OUTLOOK...
SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...HEDEN/KAH
AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1030 AM EDT FRI AUG 30 2013
.SYNOPSIS...
RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A
CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE
RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING
THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS
A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER-
LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY
MUGGY...THROUGHOUT THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...
FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY
SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S
VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG
INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL
PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS
CONVECTION INTO FA LATE THIS AFTN.
A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A
BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT
WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP
POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND
TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES
INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV
NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK
THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE
HWO ACCORDINGLY.
PREV DISCO BLO...
4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD
ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR
ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE
FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z).
BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE
INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING
IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION).
OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN
SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE
OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER
THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF
THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS.
AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF
NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV
WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER
ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER
CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN
ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO
APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE
LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY
RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY
LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH
COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN
EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY
THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN
CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD
SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF
SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z).
FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO
FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY
INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL
BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT
NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE
FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT
TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN
CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS
ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH
AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN
PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER
TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND
WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN
NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN
CONVECTIVE WAVES.
ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT
AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE
DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT
MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN
VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST.
WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL
INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST
FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD
AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF
COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES
THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING
WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE
WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS
AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS
HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A
DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE
CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES
FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL.
THE PREVIOUS AFD IS BELOW...
PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE
PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF
CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES
EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM
THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO
MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT.
THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN
PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW.
THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY
BRINGING A COLD FRONT TO THE AREA.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
700 AM UPDATE...
DENSE FOG WILL PRODUCE WIDESPREAD RESTRICTIONS FOR THE NEXT FEW
HOURS OUTSIDE OF KSYR.
WORST CONDITIONS WILL BE AT KITH AND BGM. LIFR CONDITIONS
CONTINUE HERE THROUGH 13Z BEFORE SLOW IMPROVEMENT TO
VFR BY 15Z.
KAVP AND KRME...IFR CIGS AND VSBYS WILL SLOWLY IMPROVE TO VFR BY
15Z.
AFTER MID MORNING VFR IS EXPECTED THE REST OF TODAY.
NEAR CALM CONDITIONS THROUGH DAYBREAK. WINDS INCREASE TO 4 TO 8
KTS 13 TO 16Z AND REMAIN THROUGH THE AFTN.
OUTLOOK...
FRI NGT...GENERALLY VFR SOME MVFR POSSIBLE NORTHERN TERMINALS IN
SHOWERS/STORMS.
SAT-TUES...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...KAH
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
858 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PREVAIL THROUGH THE REST OF THE
WEEKEND. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON
MONDAY...THEN PUSH SLOWLY EAST THROUGH THE CAROLINAS ON TUESDAY. IN
THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...
OVERVIEW:
LIGHT NW FLOW ALOFT WILL PREVAIL ACROSS THE REGION THROUGH
TONIGHT...IN A WEAKNESS BETWEEN AN UPSTREAM RIDGE OVER THE SOUTHERN
PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST.
17Z WV IMAGERY AND RAP DATA INDICATED SMALL AMPLITUDE DISTURBANCES
UPSTREAM ACROSS OH/KY/WV...TRACKING SOUTHEAST TOWARD THE MID-
ATLANTIC AND NORTHERN PORTIONS OF NC.
PRECIPITATION CHANCES:
THE LOW-LEVEL RIDGE EXTENDING WESTWARD INTO CENTRAL NC THIS MORNING
HAS FURTHER WEAKENED...GIVING WAY TO AN INCREASINGLY MOIST SOUTHERLY
RETURN FLOW FROM THE SFC-925 MB...WITH ADDITIONAL MOISTURE ADVECTING
INTO THE AREA FROM THE WEST/WNW AT H85. SEASONABLY STRONG INSOLATION
WILL RESULT IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION BY PEAK
HEATING WITH MLCAPE VALUES RANGING FROM 1500-2000 J/KG IN THE
WESTERN PIEDMONT TO 500-1000 J/KG IN THE EAST WHERE THE LOW-LEVELS
ARE DRIER AS NOTED ABOVE. THE PRIMARY UNCERTAINTY W/REGARD TO
CONVECTION WILL BE FORCING. VERY LITTLE IF ANY LOW-LEVEL FORCING
WILL BE PRESENT THIS AFT/EVE WITH LARGELY UNIDIRECTIONAL SFC-925 MB
FLOW OVER CENTRAL NC. ADDITIONALLY...UPPER LEVEL FORCING /DPVA/ IS
EXPECTED TO REMAIN N/NW OF CENTRAL NC THIS AFT/EVE AS SMALL
AMPLITUDE DISTURBANCES TRACK SLOWLY E/ESE FROM THE OH VALLEY INTO
THE WV AND CENTRAL/WESTERN VA. AN MCV AND A ROBUST COLD POOL ASSOC/W
AN ONGOING MCS UPSTREAM OVER EASTERN KY AND SOUTHWEST VA AT 17Z IS
LIKELY TO TRACK SOUTHEASTWARD TOWARD NORTHWEST NC AND MAY PROVIDE
SUFFICIENT FORCING FOR CONVECTION TO DEVELOP IN THE NW PIEDMONT LATE
THIS AFT/EVE (22-04Z). WITH THE ABOVE IN MIND...WILL INDICATE PRECIP
CHANCES OF 20-30% WEST OF THE HWY 1 CORRIDOR WITH THE RELATIVE BEST
CHANCE IN THE TRIAD. EAST OF HWY 1...GIVEN A PROFOUND LACK OF
FORCING AND A DRIER LOW-LEVEL AIRMASS /MARGINAL DESTABILIZATION/...
WILL KEEP THE FCST DRY. CHANCES FOR CONVECTION WILL DECREASE BY
MIDNIGHT IN ASSOC/W INCREASING NOCTURNAL STABILIZATION...THOUGH IF
SMALL AMPLITUDE DISTURBANCES AND/OR THE AFOREMENTIONED MCV GRAZE OR
TRACK ACROSS NORTHERN PORTIONS OF CENTRAL NC THERE MAY BE SUFFICIENT
MOISTURE/INSTABILITY TO SUPPORT ISOLD CONVECTION OVERNIGHT...AND
THIS WILL BE THE BASIS FOR A 20% CHANCE OF SHOWERS NORTH OF HWY 64
AFTER MIDNIGHT.
TEMPERATURES:
EXPECT HIGHS TODAY SLIGHTLY ABOVE NORMAL...IN THE MID/UPPER 80S TO
NEAR 90F. LOWS TONIGHT A FEW DEGREES ABOVE NORMAL DUE TO INCREASING
LOW-LEVEL MOISTURE AND PERHAPS MID/UPPER LEVEL CLOUD COVER...IN THE
UPPER 60S TO NEAR 70F.
SEVERE POTENTIAL:
A VERY SMALL (ALBEIT CONDITIONAL) THREAT OF AN ISOLD SEVERE
DOWNBURST EXISTS IN THE FAR W/NW PIEDMONT LATE THIS AFT/EVE WHERE
MODERATE INSTABILITY (1500-2000 J/KG) AND MODERATE DCAPE (1000 J/KG)
ARE PRESENT IN ADVANCE OF THE MCS /COLD POOL/ APPROACHING THE
NORTHWEST NC MOUNTAINS. CONFIDENCE IS LOW WITH REGARD TO HOW THE
AFOREMENTIONED COLD POOL WILL EVOLVE AND WHETHER OR NOT IT WILL
AFFECT THE NW PIEDMONT IN VICINITY OF PEAK HEATING...AND HAVE OPTED
TO LEAVE OUT ANY MENTION OF SVR WX IN THE HWO. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 215 PM SATURDAY...
CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS
POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER
MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON
SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL
STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES
INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL
DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000
J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL
BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW...
THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE
WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP
CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER
TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40%
CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN
PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING
AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE
PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY...
PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE
AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS
AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO
CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 255 PM SATURDAY...
THE LONG TERM WILL BE CHARACTERIZED BY A FAIRLY STAGNANT UPPER LEVEL
PATTERN CONSISTING OF STRONG HIGH PRESSURE OVER THE SOUTHWESTERN
UNITED STATES AND A NEAR STATIONARY UPPER LEVEL TROUGH OVER THE EAST
COAST. THE FIRST HALF OF THE LONG TERM WILL SEE A SLOW DEEPENING OF
THE TROUGH THROUGH WEDNESDAY BEFORE A GRADUAL LIFTING FOR THE END OF
THE WEEK AND INTO THE WEEKEND. AT THE SURFACE A LOW PRESSURE SYSTEM
OVER THE NORTHERN GREAT LAKES WILL TRACK VERY SLOWLY EASTWARD
THROUGH SOUTHERN QUEBEC WITH A COUPLE OF ASSOCIATED COLD FRONTS
STRETCHED ACROSS THE EASTERN CONUS. EARLY IN THE PERIOD THE BERMUDA
HIGH WILL HELP TRANSPORT MOISTURE OUT OF THE GULF OF MEXICO AND
CARIBBEAN SEA INTO THE SOUTHEASTERN US BEFORE IT MOVES FURTHER OUT
TO SEA...HELPING TO DRY CONDITIONS OUT BY THE END OF THE WEEK.
MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF
THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT
BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST
SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM
ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON
THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES
PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL
INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE
A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY
AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE
BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE
MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD
CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS
WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW
90S...LOWS UPPER 70S.
ALTHOUGH THERE IS SOME DISCREPANCIES IN MODEL TIMING AND
LOCATION...THE NEWEST RUN OF THE GFS SUGGESTS THE FRONT WILL BE
SOMEWHERE IN BETWEEN RALEIGH AND FAYETTEVILLE BY PEAK HEATING AND
WHILE ISOLATED TO SCATTERED CONVECTION CANT BE RULED OUT IN THE
EXTREME SOUTHEAST IT LOOKS LIKE A MUCH DRIER AIRMASS WILL TAKE OVER
MOST OF THE CWA WITH VERY LIMITED INSTABILITY AND SHEAR. COOLER AND
DRIER CONDITIONS WILL BEGIN TO FILTER INTO THE AREA...HIGHS MID TO
UPPER 80S. LOWS LOWER 60S NW TO UPPER 60S SE.
WEDNESDAY THROUGH FRIDAY SHOULD REMAIN QUIET AS SURFACE HIGH
PRESSURE OVER THE OHIO VALLEY KEEPS THE COLD FRONT EAST OF THE AREA.
A SUPPORTING MIGRATORY HIGH DROPPING SOUTHEASTWARD OUT OF THE
NORTHERN PLAINS WILL HELP TO PROPEL A SECONDARY COLD FRONT THROUGH
THE REGION THAT WILL REINFORCE DRY CONDITIONS THROUGH AT LEAST
FRIDAY MORNING. MOISTURE SLOWLY INCREASES FRIDAY AFTERNOON AND
EASTERLY FLOW OFF THE ATLANTIC COULD HELP AID SOME DIURNAL
CONVECTION FRIDAY AFTERNOON...PRIMARILY FOCUSED ON THE SEA BREEZE.
SATURDAY WILL FEATURE INCREASED MOISTURE WITH A GREATER CHANCE FOR
DIURNAL CONVECTION. HIGHS DURING THIS PERIOD WILL BE LOW TO MID 80S
WITH LOWS IN THE LOWER TO MID 60S.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 835 PM SATURDAY...
24-HR TAF PERIOD:
MOST OF THE AFTERNOON/EARLY EVENING SHOWERS AND STORMS HAVE
DISSIPATED THIS EVENING WITH THE LOSS OF DAYTIME HEATING. HOWEVER...
A FEW MORE SHOWERS AND/OR STORMS WILL BE POSSIBLE OVER THE NEXT
SEVERAL HOURS ALONG ANY REMNANT OUTFLOW BOUNDARIES ACROSS THE
NORTHERN PIEDMONT (KGSO/KINT/KRDU). WILL HANDLE THIS THREAT WITH
AMENDMENTS. OTHERWISE EXPECT VFR CONDITIONS TO CONTINUE FOR THE
REMAINDER OF THIS EVENING INTO THE OVERNIGHT HOURS. WILL CONTINUE TO
MENTION A TEMPO GROUP FOR MVFR VISBYS AT ALL SITES FOR THE PRE-DAWN
HOURS FOR SUNDAY. HOWEVER... CONFIDENCE IS RATHER LOW GIVEN AN UPPER
LEVEL DISTURBANCE CURRENTLY OVER EASTERN KY WILL MOVE INTO OUR
REGION AFTER MIDNIGHT (GENERALLY AFTER 06Z). THIS SHOULD AT LEAST
SPREAD MID AND HIGH LEVEL CLOUD COVER INTO OUR REGION... WITH
POSSIBLY SOME SHOWERS AND STORMS. GIVEN THE NOCTURNAL TIMING WILL
NOT MENTION ANY SHOWERS AND STORMS IN THE TAFS AT THIS TIME FOR THE
OVERNIGHT (BEST CHANCE NORTHWEST PIEDMONT... KGSO/KINT).
EXPECT WE WILL SEE ISOLATED TO SCATTERED SHOWERS AND STORMS DEVELOP
SUNDAY AFTERNOON AND EVENING. THINK WE WILL SEE SHOWERS AND STORMS
FIRST DEVELOP WHERE THE REMNANT OUTFLOW FROM TODAYS ACTIVITY STALLS
THIS EVENING.... CURRENTLY EXPECTED TO RANGE FROM THE SW PIEDMONT TO
NE COASTAL PLAIN. THUS... WILL ADD VCTS TO THE TAFS STARTING AT 18Z
FOR KRDU/KFAY/KRWI... WITH SHOWERS AND STORMS EXPECTED A BIT LATER
IN THE DAY AT KGSO/KINT... AS SHOWERS AND STORMS DEVELOP ACROSS THE
HIGHER TERRAIN AND MOVE INTO THE NORTHWEST PIEDMONT. ANY SHOWERS AND
STORMS WILL HAVE THE POTENTIAL TO PRODUCE SUB VFR CONDITIONS AND
GUSTY WINDS. -BSD
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON/MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING
CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE
NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS
CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE
AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO
SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE
FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...ELLIS
AVIATION...BSD/VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM FRIDAY...
IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL
NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS
AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE
LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT
MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN
EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE
DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE
TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO
SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN
CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE
MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER
MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG
(GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE
MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20
KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN
CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW
PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO
CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP
MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A
LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK
OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING
DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72.
-GIH
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...
THE PATTERN FOR THE LONG TERM PORTION OF THE FORECAST WILL CONTINUE
TO FEATURE A STRONG RIDGE ACROSS THE ROCKY MOUNTAIN STATES AND AN
AMPLIFYING EASTERN U.S./CANADA TROUGH DURING THE MID TO LATE WORK
WEEK.
SUNDAY WILL FEATURE INCREASING DEEP LEVEL MOISTURE AS PRECIPITABLE
WATER VALUES INCREASE FROM AROUND 1.25 INCHES ON SATURDAY MORNING TO
BETWEEN 1.9 AND 2.0 INCHES ON SUNDAY MORNING. THE AIR MASS WILL BE
SOMEWHAT UNSTABLE BUT WILL BE LACKING A STRONG FOCUS FOR ASCENT. A
WEAKNESS/SHEAR AXIS IN THE MID LEVELS IS EXPECTED TO BE DRIFTING
EAST ACROSS THE SOUTHERN MOUNTAINS ON SUNDAY AFTERNOON WHICH WILL
SUPPORT SLIGHTLY HIGHER POPS IN THE CHANCE RANGE IN THE WEST. HIGHS
SUNDAY WILL BE SLIGHTLY ABOVE NORMAL IN THE UPPER 80S WITH LOWS
AROUND 70.
THE MAIN WEATHER EVENT OF THE LONGER TERM PERIOD ARRIVES MONDAY AND
PERSISTS INTO TUESDAY AS A DIGGING SHORT WAVE TROUGH DIVES INTO THE
OHIO VALLEY ON MONDAY. THE SHORTWAVE ASSOCIATED WITH A 70KT JET
ALOFT LINGERS ACROSS THE MID ATLANTIC MONDAY NIGHT AND TUESDAY
BEFORE ANOTHER DISTURBANCE GIVES THE TROUGH AXIS A PUSH AND MOVES IT
EAST OF CENTRAL NC ON TUESDAY. A LEE TOUGH DEVELOPS OVER CENTRAL NC
ON MONDAY WHILE THE COLD FRONT MOVES INTO THE REGION ON TUESDAY
AFTERNOON AND FINALLY PUSHES TOWARD THE COAST BY AROUND WEDNESDAY
MORNING. THE AIR MASS ACROSS CENTRAL NC WILL BE VERY MOIST WITH PW
VALUES AROUND 2.0 AND CAPE VALUES WILL CLIMB INTO THE 1500-2500 J/KG
RANGE ON MONDAY AFTERNOON ACROSS CENTRAL NC WITH THE INSTABILITY
SHIFTING EAST ON TUESDAY AFTERNOON AS A CAPPING INVERSION MOVES INTO
THE PIEDMONT. WHILE INSTABILITY IS PRESENT AND MECHANISMS
TO INITIATE AND FOCUS CONVECTION ARE IN PLACE...THE WIND FIELD IS
RATHER LIMITED WITH BULK SHEAR VALUES PROGGED TO BE AROUND OR A
LITTLE LESS THAN 20KS. SO AT THIS POINT EXPECT A PRETTY GOOD
COVERAGE OF CONVECTION...MAINLY DURING THE AFTERNOON AND EVENING.
SOME OF THE CONVECTION COULD BE STRONG BUT A WIDESPREAD SEVERE
WEATHER EVENT ISN`T EXPECTED. WILL INCLUDE HIGH CHANCE POPS DURING
THE AFTERNOON AND EVENING PERIODS WITH LINGERING LOW CHANCE POPS
OVERNIGHT. THE FOCUS FOR PRECIPITATION...ESPECIALLY THUNDERSTORMS
SHIFTS TO THE EAST ON TUESDAY AND HAVE ADJUSTED POPS UPWARD IN THOSE
LOCATIONS. HIGHS ON MONDAY WILL RANGE IN THE UPPER 80S AND A JUST A
BIT COOLER IN THE MID 80S ON TUESDAY WITH LOWS NEAR 70.
THE COLD FRONT IS PROGGED TO REACH THE COAST BY WEDNESDAY MORNING
WITH WEAK HIGH PRESSURE OVER THE WESTERN OHIO VALLEY ON WEDNESDAY
MORNING SLOWLY BUILDING EAST ON THURSDAY. THIS SHOULD RESULT IN FAIR
AND DRY WEATHER WITH COOLER TEMPERATURES. HIGHS WEDNESDAY SHOULD BE
IN THE 80-85 RANGE WITH SLIGHTLY WARMER TEMPERATURES ON THURSDAY IN
THE LOWER TO MID 80S. MORNING LOWS WILL RANGE IN THE LOWER TO MID
60S. -BLAES
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
245 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM FRIDAY...
IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL
NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS
AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE
LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT
MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN
EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE
DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE
TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO
SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN
CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE
MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER
MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG
(GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE
MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20
KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN
CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW
PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO
CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP
MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A
LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK
OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING
DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72.
-GIH
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND
STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL
PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF
CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND
DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS
EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF
CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH
THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT
ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 205 AM FRIDAY...
OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY
DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK
SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH
PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP
LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF
SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK
OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED
FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR
THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH
THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE
WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER
ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS
OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER
HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER
AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC
DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS
OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST.
THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS
AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE
FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID
LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING
MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN
CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT
LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL
MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE
INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM
ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 230 PM THURSDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND
STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL
PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF
CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND
DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS
EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF
CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH
THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT
ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1250 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 815 PM THURSDAY...
OVERVIEW:
NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS
OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/
ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH
PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY
NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC.
PRECIPITATION CHANCES:
ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE
FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL
FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM
THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY
DIFFLUENT FLOW ALOFT.
TEMPERATURES:
LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A
COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE
LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO
NEAR 70F FAR S/SW. -VINCENT
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 PM THURSDAY...
QUIET WEATHER-WISE.
WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY
MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY
SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH
CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE
SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S.
SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH
SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT.
SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR
A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW
DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW
LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH
SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF
INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT
MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A
BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON
SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE
AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY
85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...VINCENT
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1245 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION
THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP
ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL
CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 815 PM THURSDAY...
OVERVIEW:
NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS
OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/
ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH
PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY
NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC.
PRECIPITATION CHANCES:
ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE
FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL
FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM
THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY
DIFFLUENT FLOW ALOFT.
TEMPERATURES:
LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A
COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE
LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO
NEAR 70F FAR S/SW. -VINCENT
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 PM THURSDAY...
QUIET WEATHER-WISE.
WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY
MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY
SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH
CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE
SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S.
SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH
SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT.
SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR
A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 235 PM THURSDAY...
SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH
THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF
MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK.
SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW
DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW
LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH
SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF
INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT
MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A
BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON
SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE
AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY
85-90.
MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE
EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH
A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO
ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME
CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH
DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO
LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND
WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD
AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD
FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE
PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS
THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT
AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY
AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL
BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY
TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE...
84 NORTHWEST TO 88 SOUTHEAST.
WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST
TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON
WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN
PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING
LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A
BIT ON THURSDAY...MOSTLY MID 80S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...
CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE
APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING.
SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER
THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL
REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING.
MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS
AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE
FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY
STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS
IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z...
REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT
SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR
TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP
TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z.
HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE
END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH
PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY
WEATHER TODAY.
LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF
IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING
(09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER
MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE
EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR
CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT
AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS
SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY
AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND
STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...VINCENT
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
955 PM CDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 954 PM CDT SAT AUG 31 2013
CLEAR SKIES ACROSS ALL BUT THE FAR NORTHWEST THIS EVENING WITH
DIMINISHING NORTH TO NORTHWEST WINDS. EXTENSIVE CLOUD COVER ACROSS
SOUTHERN SASKATCHEWAN AND MANITOBA IS PUSHING SOUTH AND IS
EXPECTED TO DROP SOUTH ACROSS WESTERN AND CENTRAL NORTH DAKOTA
LATE TONIGHT. LATEST 01 SEP 00Z NAM AND RUC GUIDANCE SUGGESTS
HIGHEST 925-850MB RH SHOULD CONTINUE TO PUSH SOUTH THROUGH EASTERN
PORTIONS OF THE CWA...BUT LINGER IN THE WEST...MAINLY FROM ISN TO
BETWEEN BISMARCK AND DICKINSON ON THE BACK SIDE OF THE SURFACE
HIGH. ADJUSTED CLOUD COVER BASED ON LATEST LOW LEVEL RH GUIDANCE.
OTHERWISE A QUIET NIGHT WITH DIMINISHING WINDS AND COMFORTABLE
TEMPERATURES MAINLY IN THE 50S.
UPDATE ISSUED AT 638 PM CDT SAT AUG 31 2013
MUCH COOLER AIR BEHIND AN EXITING COLD FRONT WILL CONTINUE TO
SPILL ACROSS WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. AN UPPER
LEVEL LOW ACROSS MANITOBA HAS MOVED FAR ENOUGH EAST THAT EARLY
EVENING SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL. OTHER
THAN REMOVING POPS NORTH CENTRAL AND MINOR CLOUD COVER
ADJUSTMENTS...THE CURRENT FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 250 PM CDT SAT AUG 31 2013
DRIER AND COOLER AIR WILL HIGHLIGHT THE SHORT TERM FORECAST.
AS OF 20 UTC...THE COLD FRONT HAS CLEARED THE CWA WITH LOW LEVEL
DRY AND COLD AIR ADVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA
AND WIDESPREAD WIND GUSTS OF 25-30 KTS IN POST FRONTAL MIXING.
DID ADD A MENTION OF ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE
NORTH CENTRAL THIS AFTERNOON AND EARLY EVENING WITH THE UPPER
LEVEL LOW THAT IS PROPAGATING SOUTHEAST OUT OF FAR SOUTHEAST
SASKATCHEWAN. ANY CONVECTION THAT DOES FORM WILL FADE WITH SUNSET.
AN EXPANSE OF STRATUS IS EXPECTED TO OVERSPREAD AREAS ALONG AND
NORTH OF I-94 TONIGHT...WHICH WILL HELP TO KEEP OVERNIGHT LOWS IN
THE 50S. A QUIET A REFRESHINGLY COOL DAY IS EXPECTED SUNDAY WITH
HIGHS IN THE 70S WITH HIGH PRESSURE IN PLACE. GIVEN GOOD
AGREEMENT...A BLEND OF THE 12 UTC GUIDANCE SUITE WAS USED FOR ALL
FIELDS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 250 PM CDT SAT AUG 31 2013
AFTER A COOL AND DRY SUNDAY...WILL SEE A WARMING TREND BACK TO
ABOVE NORMAL TEMPERATURES THROUGH THE COMING WORK WEEK AS THE
CENTRAL U.S. UPPER RIDGE REBUILDS/AMPLIFIES FROM ACROSS THE
ROCKIES NORTH INTO THE CANADIAN HIGH PLAINS...BRINGING WAA BACK
EAST INTO THE DAKOTAS. EXPECT MOSTLY DRY CONDITIONS OVER NORTH
DAKOTA THROUGH THURSDAY NIGHT WITH A DRY NORTHWEST FLOW ALOFT.
THE EXCEPTION MAY BE THE TUESDAY AFTERNOON THROUGH WEDNESDAY
NIGHT PERIOD WHEN MODELS PROJECT AN EMBEDDED S/WV IMPULSE MOVING
THROUGH THE RIDGE FROM ACROSS SOUTHERN MONTANA EAST INTO THE
DAKOTAS. HAVE CONFINED SLIGHT CHANCE POPS FOR NOW TUESDAY NIGHT
THROUGH WED NIGHT. THE LATEST ECMWF (12Z) NOW BRINGS THIS FEATURE
TO THE ND/MT BORDER BY 00Z WED...SO FUTURE UPDATED FORECASTS MAY
NEED TO ADD SOME MENTION OF THUNDERSTORMS STARTING TUESDAY
AFTERNOON ACROSS THE WEST.
AS WE HEAD INTO THE LATER PORTIONS OF THE WORK WEEK AND THE FIRST
HALF OF NEXT WEEKEND...MODELS PROJECT THE RIDGE TO BREAKDOWN AS A
CLOSED UPPER LOW (NOW OFF THE NORTHWEST U.S. COAST) MOVES INLAND
SOMETIME THURSDAY NIGHT OR FRIDAY...THEN EAST TOWARDS THE NORTHERN
PLAINS SOMETIME FRI-SUN. LATEST GFS/ECMWF DIFFER ON THE TIMING OF
THIS FEATURE...SO LOTS OF UNCERTAINTY STILL IN PLAY. EVENTUALLY
THIS FEATURE WILL BE THE FOCUS OF LATER FORECASTS AS IT IS
EXPECTED TO BRING COOLER WEATHER AND INCREASED CHANCES FOR
PRECIPITATION TO OUR REGION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 954 PM CDT SAT AUG 31 2013
LATEST GUIDANCE IS STILL SUGGESTING LOW VFR TO MVFR CEILINGS
DROPPING SOUTH INTO THE FORECAST AREA LATE TONIGHT AND SUNDAY
MORNING. THEN IMPROVING CEILINGS LATE SUNDAY MORNING WITH A
NORTH FLOW SHIFTING EAST ACROSS THE WEST SUNDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...AYD
LONG TERM...NH
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1258 PM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1258 PM CDT FRI AUG 30 2013
NO SIGNIFICANT CHANGES WITH THIS FORECAST UPDATE. THE THINKING
REMAINS UNCHANGED FROM THE 1021 AM CDT UPDATE BELOW REGARDING
EXPECTED CONVECTION. THIS IS CONFIRMED BY THE 16 UTC HRRR AND 12
UTC 4 KM WRF.
UPDATE ISSUED AT 1021 AM CDT FRI AUG 30 2013
CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE
15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS
THE AREA.
THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS
AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE
TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING
CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83
BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG
WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A
PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE
VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH
PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY
SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A
LOCALIZED THREAT FOR TORNADOES.
UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013
QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL
NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS
AND WEBCAMS.
UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013
UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH
JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83
CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY
AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED
THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST
TONIGHT...SOME POSSIBLY SEVERE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT FRI AUG 30 2013
CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD
ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE
FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA.
AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN
ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER
LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF
SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND
SOUTH CENTRAL SASKATCHEWAN.
THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING
NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS
NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON
THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS
WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY
LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO
MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS
EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA.
FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN
AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK
SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE
CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS
THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION
CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT.
ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO
UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO
THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS
TONIGHT IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 335 AM CDT FRI AUG 30 2013
ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY
SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST
WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR
ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE
SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON
RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS
FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN
BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF
THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL
BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1258 PM CDT FRI AUG 30 2013
VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE
UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO
INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE
CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST
THROUGH THE EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1022 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1021 AM CDT FRI AUG 30 2013
CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE
15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS
THE AREA.
THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS
AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE
TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING
CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83
BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG
WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A
PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE
VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH
PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY
SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A
LOCALIZED THREAT FOR TORNADOES.
UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013
QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL
NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS
AND WEBCAMS.
UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013
UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH
JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83
CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY
AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED
THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST
TONIGHT...SOME POSSIBLY SEVERE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT FRI AUG 30 2013
CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD
ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE
FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA.
AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN
ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER
LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF
SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND
SOUTH CENTRAL SASKATCHEWAN.
THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING
NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS
NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON
THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS
WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY
LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO
MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS
EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA.
FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN
AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK
SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE
CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS
THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION
CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT.
ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO
UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO
THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS
TONIGHT IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 335 AM CDT FRI AUG 30 2013
ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY
SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST
WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR
ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE
SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON
RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS
FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN
BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF
THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL
BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 182 SATURDAY)
ISSUED AT 1021 AM CDT FRI AUG 30 2013
VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE
UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO
INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE
CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST
THROUGH THE EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
918 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 917 AM CDT FRI AUG 30 2013
VISIBILITIES OUTSIDE OF THE CENTRAL AND NORTHERN RED RIVER VALLEY
HAVE BEGUN TO RAPIDLY INCREASE. I WILL EXTEND THE DENSE FOG
ADVISORY FROM HILLSBORO NORTH TO THE CANADIAN BORDER AND ALLOW
OTHER COUNTIES TO EXPIRE AT 9 AM CDT. WILL NEED TO FINE TUNE SKY
AND TEMP TRENDS PRIOR TO ANOTHER GRID/ZONE FORECAST AT 10 AM CDT.
UPDATE ISSUED AT 710 AM CDT FRI AUG 30 2013
VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED
TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE
FOG ADVISORY.
UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NDZ008-016-
027-030.
MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ001-002-
004-007.
&&
$$
UPDATE...SPEICHER
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
710 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 710 AM CDT FRI AUG 30 2013
VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED
TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE
FOG ADVISORY.
UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008-
014>016-024-026>030-038-039-054.
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001>009-
013>016.
&&
$$
UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
635 AM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 635 AM CDT FRI AUG 30 2013
OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW
STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP
GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY
THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS
THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS
CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED.
UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013
ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG
IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM
OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE
NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT
STILL A GOOD IDEA TO HEIGHTEN AWARENESS.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT
AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT
NOT QUITE AS WARM AS PREVIOUS DAYS.
LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE
PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL
YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY.
WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE
STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC
NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS
REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE
GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS
AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF
MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO
THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY
SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE
LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE
SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN
LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE
MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS
AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND
INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL
HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR
WILL BE STRONG (FAVORABLE FOR SEVERE STORMS).
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI AUG 30 2013
SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER
AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH
PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER
(EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF
ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES
NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES.
MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY
ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST
AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A
CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE
GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION
FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE
NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED
SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS
FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED
DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE
THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO
LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 635 AM CDT FRI AUG 30 2013
DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN
ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER
VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE
BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF
NEEDED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008-
014>016-024-026>030-054.
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001-
004>009-013>016.
&&
$$
UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/ROGERS
AVIATION...TG
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
335 PM EDT FRI AUG 30 2013
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A
COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT
WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD
FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NWRN PA. RADAR
HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR
NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS
WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES
THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL
CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING
ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN
LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN
INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND
BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST
NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NWRN OHIO AND THE
LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS
THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF
TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID
SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH
LOWS IN THE UPPER 60S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD
FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY
SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT
AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL
LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST
OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES
AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO
THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER
HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS
CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER
APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA
MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON
TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL
BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY.
TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH
PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS
IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL
BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL
TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL
NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES
DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH
THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW
70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA.
HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON
WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES
WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD
INSOLATION ON WEDNESDAY.
12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF
THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND
STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN
AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION
OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER
MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF
THE COLDER SOLUTION.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH ABOUT 04Z WHEN HZ/BR WILL START
TO DEVELOP WITH HIGH BOUNDARY LAYER MOISTURE IN PLACE. LOW PRESSURE WILL
MOVE FROM THE UPPER GREAT LAKES TO NEAR LAKE ONTARIO OVERNIGHT.
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR AHEAD OF THE ASSOCIATED
FRONT THAT WILL PUSH SOUTH OVER THE AREA LATE TONIGHT INTO SATURDAY
MORNING. FOR NOW HAVE PUT VCSH INTO ALL SITES BUT HAVE NOT INCLUDED
THUNDERSTORMS GIVEN THE UNCERTAINTY IN COVERAGE. A SCT-BKN MVFR
CLOUD DECK WILL LIKELY DEVELOP BEHIND THE FRONT ON SATURDAY MORNING
WITH SOME POTENTIAL FOR IFR CLOUDS/VISIBILITY.
OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY
FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH
MONDAY.
&&
.MARINE...
A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE
EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO
10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE
LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED
TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL
OHIO.
WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES
BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS
SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE
APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A
STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY
WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE
NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON
MONDAY NIGHT AND TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1137 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL DRIFT SOUTH ACROSS THE REGION
TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM
FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE
THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE
FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MESO ANAL STILL SHOWS A WEAK LOW LEVEL CONVERGENCE ZONE PRETTY
MUCH BISECTING THE FCST AREA FROM NEAR CLEARFIELD ENE TO JUST
NORTH OF WILLIAMSPORT. THIS HAS ACTED AS THE FOCUS FOR THE MOST
PERSISTENT CONVECTION WHICH HAS CAUSED LOCALLY HEAVY RAIN...BUT
ACTIVITY FINALLY SEEMS TO BE SHOWING SIGNS OF WINDING DOWN. THE
HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT QUICKLY.
RADAR TRENDS SUGGEST SHOWERS WILL CONTINUE TO MOVE ONLY SLOWLY
EASTWARD WHILE SAGGING SOUTH A BIT...BUT STILL THINK MOST ACTIVITY
WILL REMAIN MAINLY NORTH OF RTE 80.
OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY
SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER
THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST
MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS
FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN
ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW.
TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT
TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST
ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY
FOG DURING THE PREDAWN HOURS.
LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER
60S IN THE SOUTHERN VALLEYS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT
SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY
WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE
MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF
SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION.
AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY
WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS
AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON.
DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD
AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE
PRIMARY/ANTICIPATED STORM TYPE.
HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL
4-5F ABOVE NORMAL IN MANY LOCATIONS/.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH
MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN
CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH
SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE
AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE
WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW
OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS
STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT
MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS
ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH
MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A
STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS
DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH
PLAINS.
AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE
CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER
RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH
ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE
CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE
SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT
WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER
TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE
NEXT WEEK.
THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD
REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR
TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU
THE END NEXT WEEK.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
SCT SHRA/TSRA CONTINUE TO FIRE ACROSS CENTRAL PA LATE THIS EVENING
IN VICINITY OF STALLED FRONTAL BOUNDARY. AS ATMOS CONTINUES TO
COOL/STABILIZE OVERNIGHT...EXPECT THE SHRA/TSRA TO DIMINISH. THE
BIG AVIATION CONCERN WILL THEN BECOME FOG LATE TONIGHT. ABUNDANT
LOW LVL MOISTURE AND A NEARLY CALM WIND COULD PRODUCE DENSE FOG
OVER PARTS OF THE AREA. AM CURRENTLY FORECASTING A PERIOD OF IFR
CONDS AT ALL AIRFIELDS EARLY SUN AM. HOWEVER...CONFIDENCE HIGHEST
ACROSS NORTHERN PA...BASED ON LATEST SREF AND OPER MDL SFC RH
FIELDS. ACROSS THE SOUTHERN AIRFIELDS...HIGH CLOUD COVER COULD
POTENTIALLY LIMIT RAD COOLING AND FOG POTENTIAL.
EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT
TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE
RIDES EAST ALONG STALLED FRONTAL BOUNDARY.
OUTLOOK...
MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA.
TUE...AM LOW CIGS/FOG POSS W MTNS.
WED...AM FOG PSBL WEST AND CNTRL.
THU...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...DANGELO/LA CORTE/LAMBERT
LONG TERM...CERU/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1018 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL DRIFT SOUTH ACROSS THE REGION
TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM
FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE
THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE
FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MESO ANAL STILL SHOWS A WEAK LOW LEVEL CONVERGENCE ZONE PRETTY
MUCH BISECTING THE FCST AREA FROM NEAR CLEARFIELD ENE TO JUST
NORTH OF WILLIAMSPORT. THIS HAS ACTED AS THE FOCUS FOR THE MOST
PERSISTENT CONVECTION WHICH HAS CAUSED LOCALLY HEAVY RAIN...BUT
ACTIVITY FINALLY SEEMS TO BE SHOWING SIGNS OF WINDING DOWN. THE
HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT QUICKLY.
RADAR TRENDS SUGGEST SHOWERS WILL CONTINUE TO MOVE ONLY SLOWLY
EASTWARD WHILE SAGGING SOUTH A BIT...BUT STILL THINK MOST ACTIVITY
WILL REMAIN MAINLY NORTH OF RTE 80.
OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY
SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER
THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST
MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS
FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN
ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW.
TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT
TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST
ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY
FOG DURING THE PREDAWN HOURS.
LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER
60S IN THE SOUTHERN VALLEYS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT
SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY
WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE
MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF
SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION.
AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY
WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS
AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON.
DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD
AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE
PRIMARY/ANTICIPATED STORM TYPE.
HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL
4-5F ABOVE NORMAL IN MANY LOCATIONS/.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH
MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN
CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH
SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE
AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE
WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW
OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS
STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT
MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS
ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH
MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A
STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS
DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH
PLAINS.
AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE
CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER
RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH
ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE
CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE
SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT
WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER
TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE
NEXT WEEK.
THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD
REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR
TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU
THE END NEXT WEEK.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF
SHRA AROUND LNS AT 2330Z...WHILE A BAND OF SLOW MOVING TSRA ASSOC
WITH A DYING COLD FRONT IS AFFECTING THE N MTNS. LOW DWPT
DEPRESSION...COMBINED WITH ARRIVAL OF ADDITIONAL SHRA...WILL
LIKELY KEEP VSBY AT LNS IN THE MVFR CATEGORY THIS EVENING. LINE
OF TSRA OVR THE N MTNS IS EXPECTED TO WEAKEN AFTER SUNSET...AS IT
PRESSES SLOWLY SE...POSSIBLY PRODUCING A BRIEF TSRA IMPACT AT
UNV OR IPT BTWN 01Z-04Z.
COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION
DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN
BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 06Z-13Z TIME
FRAME. BASED ON LATEST SREF AND OPER MDL SFC RH FIELDS...BFD
APPEARS MOST LIKELY TO EXPERIENCE DENSE FOG OVERNIGHT.
EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT
TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE
RIDES EAST ALONG STALLED FRONTAL BOUNDARY.
OUTLOOK...
MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA.
TUE...AM LOW CIGS/FOG POSS W MTNS.
WED...AM FOG PSBL WEST AND CNTRL.
THU...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...DANGELO/LA CORTE/LAMBERT
LONG TERM...CERU/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
802 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE REGION
TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM
FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE
THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE
FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MESO ANAL SHOWS A WEAK COLD FRONT OR OUTFLOW BOUNDARY FROM NEAR
DUBOIS NE TO AROUND ELMIRA AND BINGHAMTON. THIS HAS ACTED AS THE
FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH IS CAUSING LOCALLY
HEAVY RAIN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING
IT AFTER 00Z. RADAR TRENDS SUGGEST IT WILL MOVE MORE EASTWARD AS
IT FADES...REMAINING MAINLY NORTH OF RTE 80.
OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY
SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER
THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST
MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS
FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN
ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW.
TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT
TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST
ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY
FOG DURING THE PREDAWN HOURS.
LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER
60S IN THE SOUTHERN VALLEYS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT
SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY
WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE
MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF
SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION.
AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY
WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS
AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON.
DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD
AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE
PRIMARY/ANTICIPATED STORM TYPE.
HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL
4-5F ABOVE NORMAL IN MANY LOCATIONS/.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH
MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN
CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH
SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE
AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE
WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW
OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS
STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT
MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS
ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH
MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A
STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS
DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH
PLAINS.
AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE
CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER
RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH
ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE
CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE
SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT
WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER
TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE
NEXT WEEK.
THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD
REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR
TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU
THE END NEXT WEEK.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF
SHRA AROUND LNS AT 2330Z...WHILE A BAND OF SLOW MOVING TSRA ASSOC
WITH A DYING COLD FRONT IS AFFECTING THE N MTNS. LOW DWPT
DEPRESSION...COMBINED WITH ARRIVAL OF ADDITIONAL SHRA...WILL
LIKELY KEEP VSBY AT LNS IN THE MVFR CATEGORY THIS EVENING. LINE
OF TSRA OVR THE N MTNS IS EXPECTED TO WEAKEN AFTER SUNSET...AS IT
PRESSES SLOWLY SE...POSSIBLY PRODUCING A BRIEF TSRA IMPACT AT
UNV OR IPT BTWN 01Z-04Z.
COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION
DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN
BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 06Z-13Z TIME
FRAME. BASED ON LATEST SREF AND OPER MDL SFC RH FIELDS...BFD
APPEARS MOST LIKELY TO EXPERIENCE DENSE FOG OVERNIGHT.
EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT
TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE
RIDES EAST ALONG STALLED FRONTAL BOUNDARY.
OUTLOOK...
MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA.
TUE...AM LOW CIGS/FOG POSS W MTNS.
WED...AM FOG PSBL WEST AND CNTRL.
THU...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...DANGELO/LA CORTE/LAMBERT
LONG TERM...CERU/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
731 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE REGION
TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM
FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE
THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE
FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MESO ANAL SHOWS A WEAK COLD FRONT OR OUTFLOW BOUNDARY FROM NEAR
DUBOIS NE TO AROUND ELMIRA AND BINGHAMTON. THIS HAS ACTED AS THE
FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH IS CAUSING LOCALLY
HEAVY RAIN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING
IT AFTER 00Z. RADAR TRENDS SUGGEST IT WILL MOVE MORE EASTWARD AS
IT FADES...REMAINING MAINLY NORTH OF RTE 80.
OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY
SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER
THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST
MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS
FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN
ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW.
TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT
TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST
ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY
FOG DURING THE PREDAWN HOURS.
LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER
60S IN THE SOUTHERN VALLEYS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT
SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY
WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE
MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF
SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION.
AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY
WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS
AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON.
DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD
AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE
PRIMARY/ANTICIPATED STORM TYPE.
HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL
4-5F ABOVE NORMAL IN MANY LOCATIONS/.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH
MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN
CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH
SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE
AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE
WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW
OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS
STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT
MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS
ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH
MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A
STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS
DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH
PLAINS.
AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE
CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER
RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH
ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE
CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE
SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT
WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER
TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE
NEXT WEEK.
THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD
REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR
TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU
THE END NEXT WEEK.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF
SHRA/TSRA AROUND MDT/LNS THIS EVENING...WHILE A BAND OF SLOW
MOVING TSRA ASSOC WITH A DYING COLD FRONT IS AFFECTING THE N MTNS.
THE SHRA OVR THE SE COULD PRODUCE A BRIEF MVFR VIS RESTRICTION AT
MDT OR LNS BTWN 22Z-01Z. LINE OF TSRA OVR THE N MTNS IS EXPECTED
TO WEAKEN AFTER SUNSET...AS IT PRESSES SLOWLY SE...POSSIBLY
PRODUCING A BRIEF TSRA IMPACT AT JST/AOO/UNV/IPT.
COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION
DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN
BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 08Z-13Z TIME
FRAME...ESP IN THOSE SPOTS THAT RECEIVE RAINFALL THIS EVENING.
EARLY LOW CIGS/FOG WILL LIFT TO VFR CONDS BY AFTN. HOWEVER...SCT
TSRA IMPACTS ARE EXPECTED IN THE AFTN IN VICINITY OF STALLED
FRONTAL BOUNDARY.
OUTLOOK...
MON...AM FOG. SCT PM TSRA IMPACTS. FROPA.
TUE...MVFR CIGS WEST/VFR CNTRL AND EAST.
WED...AM FOG PSBL WEST AND CNTRL. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...DANGELO/LA CORTE/LAMBERT
LONG TERM...CERU/STEINBUGL
AVIATION...FITZGERALD/LAMBERT
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
212 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM...I WILL ISSUE A QUICK UPDATE TO INCREASE SKY COVER AND
REDUCE POPS OVER THE NEXT COUPLE OF HOURS. TEMPERATURES UNDER THE
CLOUD COVER HAS MANAGED TO AGREE FAIRLY WELL WITH THE FORECAST...BUT
I WILL MAKE SEVERAL MINOR ADJUSTMENTS.
AS OF NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF
STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A
BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER
VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH
WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS
MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS
MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM
INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING
IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY
SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING
SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL
UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL
HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN.
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL
ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS
AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW
FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT
NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE
SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY
LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH
PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE
INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON
AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT.
COVERAGE BOTH DAYS WILL FAVOR THE MOUNTAINS WITH LOWER...BUT STILL
SCATTERED COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL
BOTH DAYS WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST
SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A
LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT.
HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH
FLOODING BOTH SUN AND MON DUE TO SLOW MOVING STORMS.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH
AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT
THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON
NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT TUE NIGHT INTO THU.
A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI.
THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE
EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD
FRONT MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT WILL
HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW. TEMPS
WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...A U SHAPED BAND OF MVFR CLOUDS REMAINS
ACROSS THE EASTERN SLOPES OF THE MTNS AND THE UPSTATE OF SC THIS
AFTERNOON. RECENT SATELLITE TRENDS SHOWS SLOW ADVECTION OF DRIER AIR
SW ACROSS THE NC/SC LINE NEAR THE I-77 CORRIDOR. DIURNAL HEATING AND
INCREASING DRY AIR SHOULD RESULT IN PREVAILING VFR BASED CLOUDS BY
19Z...THEN REMAIN VFR THROUGH THIS EVENING. THE CHALLENGE OVERNIGHT
WILL BE THE POTENTIAL FOR ANOTHER ROUND OF RESTRICTIVE CEILINGS.
MODELS HAVE DONE A POOR JOB WITH THIS MORNINGS CLOUD COVER. GIVEN
THE LINGERING LLVL MOISTURE ACROSS THE SAVANNAH RIVER
VALLEY...COMBINED WITH VEERING LLVL FLOW...MOISTURE SHOULD INCREASE
ACROSS THE REGION OVERNIGHT. I WILL INDICATE THE REDEVELOPMENT OF
MVFR CEILINGS BY 7Z...PERSISTING THROUGH MID MORNING SAT. VFR
CONDITIONS ARE EXPECTED FROM 15Z ON. CLT MAY REMAIN VFR UNTIL
MORNING HEATING DEVELOPS MVFR CLOUDS. CONVECTION SHOULD REMAIN WEST
OF THE TERMINALS THROUGH 18Z SAT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 98% HIGH 82%
KGSP HIGH 100% HIGH 100% HIGH 91% MED 60%
KAVL HIGH 85% HIGH 81% LOW 38% LOW 59%
KHKY HIGH 100% HIGH 100% HIGH 83% MED 69%
KGMU HIGH 100% HIGH 100% HIGH 91% MED 64%
KAND HIGH 94% HIGH 100% MED 69% LOW 53%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED
SHORT TERM...LG
LONG TERM...LG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1212 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF
STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A
BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER
VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH
WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS
MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS
MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM
INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING
IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY
SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING
SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL
UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL
HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN.
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL
ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS
AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW
FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT
NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE
SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY
LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH
PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE
INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON
AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT.
COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT
COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL BOTH DAYS
WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST
SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A
LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT.
HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH
FLOODIND BOTH SUN AND MON DUE TO SLOW MOVING STORMS.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH
AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT
THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON
NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WED INTO THU.
A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI.
THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE
EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD
FRONT TUE MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT
WILL HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW.
TEMPS WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL
REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS
MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS
WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD
VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW
WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR
TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS
MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW.
ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS
MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME
BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL
CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY
FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID
MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR
THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO
ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE
INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND
MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO
SUPPORTING MVFR FOG ACRS MUCH OF THE AREA.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
16-22Z 22-04Z 04-10Z 10-16Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 87%
KGSP HIGH 100% HIGH 100% HIGH 88% HIGH 95%
KAVL HIGH 99% HIGH 100% MED 74% HIGH 87%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% MED 79%
KAND HIGH 94% HIGH 100% HIGH 94% MED 79%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...NED
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
658 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE
CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY
BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN
RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG
SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE
RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM
RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS
FROM THE WRN UPSTATE UP TO THE MTNS.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL
REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS
MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS
WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD
VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW
WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR
TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS
MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW.
ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS
MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME
BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL
CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY
FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID
MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR
THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO
ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE
INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND
MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO
SUPPORTING MVFR FOG ACRS MUCH OF THE AREA.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 97%
KGSP HIGH 84% HIGH 100% HIGH 100% HIGH 94%
KAVL HIGH 90% HIGH 98% HIGH 100% HIGH 86%
KHKY HIGH 85% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 81% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 87% HIGH 100% HIGH 100% HIGH 90%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
500 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS
SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED.
EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER
ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN
PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC
INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED
POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN
THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT
MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH
FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z
NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT /09Z UPDATE/...PATCHY VFR STRATOCU OVER THE FOOTHILLS AND
WRN PIEDMONT WILL LIKELY LAST INTO THE MORNING. OBS SUGGEST A FEW
LOWER CLOUDS ARE UNDERNEATH THE MAIN DECK AND I CANNOT RULE OUT
BRIEF RESTRICTIONS ENTIRELY THRU DAYBREAK. GUIDANCE PERFORMING
POORLY AND NOT PROVIDING MUCH CONFIDENCE...BUT FEEL VFR LIKELY TO
CONTINUE. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE
WINDS SHOULD VEER TO SE BY AFTN PER 06Z NAM AND CONSENSUS OF
PREVIOUS NAM/GFS RUNS.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 89% HIGH 100% HIGH 100% HIGH 100%
KGSP LOW 58% HIGH 95% HIGH 100% HIGH 100%
KAVL MED 75% HIGH 88% HIGH 100% HIGH 91%
KHKY MED 75% HIGH 98% HIGH 100% HIGH 83%
KGMU MED 62% HIGH 95% HIGH 100% HIGH 100%
KAND MED 78% HIGH 96% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
427 AM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST
EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND
WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE
NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE
RETURNS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS
SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED.
EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER
ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN
PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC
INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED
POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN
THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT
MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH
FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z
NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY.
AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION
WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL
LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE
REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK
OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE
RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY
CORRESPONDINGLY GREATER.
UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER
THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS
THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO
MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW
CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS
CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST
CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER
THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE
RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK
SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER
THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS
AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW
LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS
HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD
TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH
DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE
PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH
LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL.
A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE
FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER
OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL.
WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS
POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON
TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW
THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE
ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS
OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS
HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL
SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD
LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER
AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY
FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH
PRESSURE MOVING IN.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
08-14Z 14-20Z 20-02Z 02-08Z
KCLT HIGH 87% HIGH 100% HIGH 100% HIGH 100%
KGSP MED 66% HIGH 93% HIGH 100% HIGH 100%
KAVL MED 76% HIGH 87% HIGH 100% HIGH 93%
KHKY HIGH 80% HIGH 93% HIGH 100% HIGH 87%
KGMU MED 73% HIGH 93% HIGH 100% HIGH 100%
KAND HIGH 84% HIGH 97% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
153 AM EDT FRI AUG 30 2013
.SYNOPSIS...
HIGH PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A
MOIST EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH
SOUTHERLY FLOW WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL
APPROACH FROM THE NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT
INTO TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW
STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT
CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF
MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS
IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO
COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE
MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER
ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER
SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A
SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE
RIDGE SEES UPTICK.
REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO
ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN
ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY.
I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS.
EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH
TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH
WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE
UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR
NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A
WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS
INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75
INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS
TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE
WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE
WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON
SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH
NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED
STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH.
WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE
WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING.
MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE
SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE
TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT
APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT
THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE
NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE
PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON
AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON
ANALOGS.
THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY.
SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY
THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF
FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE
PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON
TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS
ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED
AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY
OF NORMAL.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 91% HIGH 91% HIGH 100% HIGH 100%
KGSP MED 74% MED 78% HIGH 100% HIGH 100%
KAVL MED 79% HIGH 80% HIGH 100% HIGH 97%
KHKY MED 68% HIGH 88% HIGH 100% HIGH 88%
KGMU HIGH 86% HIGH 82% HIGH 100% HIGH 100%
KAND HIGH 91% HIGH 83% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...LG
LONG TERM...LG
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
150 AM EDT FRI AUG 30 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SOUTH ACROSS THE REGION TODAY. HIGH
PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A MOIST
EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH SOUTHERLY FLOW
WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH FROM THE
NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT INTO
TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW
STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT
CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF
MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS
IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO
COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE
MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER
ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER
SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A
SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE
RIDGE SEES UPTICK.
REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO
ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN
ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY.
I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS.
EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH
TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH
WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE
UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR
NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A
WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS
INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75
INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS
TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE
WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE
WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON
SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH
NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED
STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH.
WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE
WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING.
MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE
SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE
TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT
APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT
THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE
NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE
PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON
AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON
ANALOGS.
THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY.
SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY
THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF
FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE
PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON
TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS
ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED
AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY
OF NORMAL.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY
FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL
BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR
THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR
CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER
TO SE BY AFTN.
ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL
SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR
THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES
EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE
AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY
RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG
AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM
OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY
MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME
FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY
THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN
VALLEYS AND WHERE RAIN FELL THE DAY BEFORE.
CONFIDENCE TABLE...
05-11Z 11-17Z 17-23Z 23-05Z
KCLT HIGH 98% HIGH 85% HIGH 100% HIGH 100%
KGSP MED 75% MED 70% HIGH 100% HIGH 100%
KAVL HIGH 84% MED 79% HIGH 99% HIGH 100%
KHKY MED 76% HIGH 83% HIGH 100% HIGH 91%
KGMU HIGH 92% MED 76% HIGH 100% HIGH 100%
KAND HIGH 98% MED 70% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JOH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...LG
LONG TERM...LG
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
324 PM CDT FRI AUG 30 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
DESTABILIZATION OCCURRING THIS AFTERNOON ACROSS THE WESTERN
DAKOTAS WITH MESOANALYSIS INDICATING AROUND 2000 J/KG MLCAPE.
SHEAR VALUES RANGE FROM AROUND 35 TO 40 KNOTS OVER WESTERN SD. A
SEVERE STORM IS AFFECTING THE BLACK HILLS AT THIS TIME...WITH VIS
SATELLITE IMAGERY SHOWING THE BEGINNINGS OF A CU FIELD EXTENDING
NORTHWARD INTO DICKINSON ND. HI RES MODELS DO SHOW ISOLD/WDLY SCT
CONVECTION OCCURRING OVER THE NEXT FEW HOURS AND LASTING INTO THE
EVENING HOURS...SOME OF WHICH MAY AFFECT THE FAR WESTERN CWA.
LATEST HRRR RUN HAS THE CONVECTION OVER THE BLACK HILLS NAILED
RIGHT NOW AND SHOWS SMALL BUT POTENT CELLS DEVELOPING ALONG THE
CURRENT CU FIELD OVER THE NEXT COUPLE HOURS...THEN PUSHES THINGS
INTO CORSON/DEWEY COUNTIES. NOT SURE AREAL COVERAGE WILL BE AS
GREAT AS THE HRRR...BUT IN SOME FORM OR ANOTHER...DO EXPECT ISOLD
TO WDLY SCT STORMS OVER THE NEXT FEW HOURS. SVR WATCH 505 WAS
RECENTLY ISSUED TO COVER THIS THREAT. WITH THE LACK OF ANY
APPRECIABLE LOW LEVEL JET OVERNIGHT...DO NOT EXPECT THIS ACTIVITY
TO SURVIVE MUCH PAST THE MISSOURI RIVER AND SHOULD WANE WITH THE
LOSS OF DAYTIME HEATING.
FOCUS WILL THEN TURN TO THE ADVANCING COLD FRONT ON SATURDAY.
FRONT WILL SET UP ACROSS THE EASTERN CWA BY PEAK HEATING...WITH
MODERATE INSTABILITY AND SHEAR DEVELOPING. ALTHOUGH BEST UPPER
LEVEL SUPPORT IS NORTH OF THE REGION...CONVERGENCE ALONG THE SHARP
FRONTAL BOUNDARY ALONG WITH SUFFICIENT LOW LEVEL MOISTURE AND
STEEP LAPSE RATES IS EXPECTED TO LEAD TO MID/LATE AFTERNOON
THUNDERSTORM DEVELOPMENT ALONG THE FRONT. SPEED OF THE FRONT WILL
BE KEY IN DETERMINING BEST CHANCE FOR STORMS. GIVEN PLACEMENT OF
THE FRONT BY AFTERNOON...CONVECTIVE INITIATION COULD OCCUR BETWEEN
THE JAMES VALLEY AND I-29...WITH MORE CONSOLIDATION/BETTER STORM
CHANCES CLOSER TO I-29 AND POINTS EAST BY LATE AFTERNOON AND INTO
THE EVENING. DAY TWO SLIGHT RISK IS NOW INCLUDING EASTERN PORTIONS
OF THE FORECAST AREA.
BEHIND THIS FRONT WILL BE MUCH COOLER AIR...WITH HIGHS ON SUNDAY
EXPECTED TO DROP BACK INTO THE 70S FOR MOST AREAS. SFC HIGH WILL
BUILD SOUTH INTO THE AREA SUNDAY NIGHT...AND WITH THE COOLER AND
DRIER AIR MASS IN PLACE...LOWS BY MONDAY MORNING COULD ACTUALLY
DIP INTO THE UPPER 40S.
.LONG TERM...MONDAY THROUGH FRIDAY
THE LONG TERM LOOKS TO REMAIN ON THE DRY SIDE WITH UPPER LEVEL
RIDGING AND SUBSIDENT FLOW DOMINATING THE WEATHER. THE MODELS SHOW
THE UPPER LEVEL RIDGE AXIS OUT WEST TO BEGIN THE LONG TERM PUSHING
EAST THROUGH FRIDAY OVER OUR REGION. ANY SHORT WAVES MOVING OVER
THE RIDGE SHOULD BE MOISTURE STARVED WITH ONLY SOME CLOUDS MOVING
IN. AFTER A COOLER DAY ON MONDAY...WARMER AIR WILL RETURN FOR
TUESDAY AND REMAIN THROUGH FRIDAY. SHOULD HAVE MID 70S EAST ON
MONDAY WARMING TO THE 80S TO THE LOWER 90S ACROSS ALL OF THE CWA
THROUGH THE REST OF THE WEEK.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH TONIGHT AND
SATURDAY MORNING. A COLD FRONT COMING ACROSS THE REGION LATER
TONIGHT AND SATURDAY WILL BRING SOME SHOWERS AND STORMS ALONG IT
WHICH MAY AFFECT THE TERMINALS. WILL WATCH FOR DEVELOPMENT.
ALSO...EXPECT SOME FOG TO FORM AT ATY LATER TONIGHT WITH THE LIGHT
WINDS AND CLEAR SKIES. LIGHT FOG MAY ALSO BE POSSIBLE AT ABR.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...TMT
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
153 PM EDT FRI AUG 30 2013
.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE MID ATLANTIC TODAY WILL SHIFT OFFSHORE
BY THIS EVENING. A WARM FRONT ENTERS THE MOUNTAINS
SATURDAY...FOLLOWED BY A COLD FRONT ARRIVING SOMETIME MONDAY.
DURING THIS PERIOD...SHOWER AND THUNDERSTORM CHANCES REMAIN.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 148 PM EDT FRIDAY...
WEAK INSITU WEDGE WILL MOVE OFF SHORE THROUGH THIS EVENING. AS
THIS WEDGE MOVES OUT OF THE AREA...ANY LINGERING LOW STRATUS DECK
WILL ALSO EXIT THE AREA. LIGHT SOUTHERLY FLOW WILL THEN BRING WARM
HUMID AIR BACK INTO THE REGION OVER THE NEXT 24 HOURS. HRRR AND
06Z RNK WRF PICKING UP ON A THETA-E BOUNDARY ACROSS THE AREA FROM
SUMMERS COUNTY WV TO THE WESTERN PART OF GRAYSON COUNTY NC. THE
LOCATION OF THIS BOUNDARY AND POINTS WEST WILL BE THE AREA THAT
SHOULD SEE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON. ISOLATED SEVERE THREAT IS POSSIBLE WITH DRY AIR ABOVE
700 MB. HOWEVER...SATURATED SOUNDING BELOW 700 MB MAY ONLY
GENERATE LOW TOP CONVECTION WITH THE POTENTIAL FOR SOME STRONGER
STORMS TO PRODUCE HEAVY RAIN. STORMS THAT DEVELOP WITH THE HEATING
OF THE DAY WILL BE SLOW MOVING. THEREFORE...THE BIGGEST THREAT
WILL BE LOCALIZED FLOODING...ESPECIALLY IN AREAS THAT HAVE SEEN
RAIN THE PAST COUPLE OF DAYS.
BREAKS IN THE CLOUDS TODAY WILL ALLOW TEMPERATURES TO MAX OUT
NEAR NORMAL...WIDESPREAD 80S. DEW POINTS WILL REMAIN HIGH WITH
READINGS IN THE MID 60S TO LOWER 70S.
TONIGHT...THERE SHOULD BE A QUICKER DROP OFF IN PRECIP THAN THIS
PAST EVENING AS THE HIGHER THETA-E AIR MOVES INTO TN/KY. WITH
CLEARING SKIES AND LIGHT WINDS...SHOULD SEE PATCHY FOG OVER MOST OF
THE AREA...ESPECIALLY RIVER VALLEYS. LOWS ARE GOING TO BE IN THE 60S
STILL.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
AS OF 400 AM EDT FRIDAY...
HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE ATLANTIC COAST
SATURDAY MORNING...WITH A WEAK WARM FRONT CROSSING OUR AREA FROM
THE SOUTHWEST. WILL SEE ANOTHER ROUND OF SPOTTY SHOWERS AND
THUNDERSTORMS DEVELOP WITH DAYTIME HEATING...MAINLY ACROSS THE
MOUNTAINS STARTING IN EARLY AFTERNOON...AND THEN SPILLING OVER
INTO THE PIEDMONTS DURING THE EARLY EVENING AS WINDS AND
ATMOSPHERIC MIXING BEGINS TO WEAKEN. A LEE SIDE TROUGH SETTING UP
ACROSS THE PIEDMONTS WILL CAUSE WINDS ACROSS THE MOUNTAINS TO
SHIFT MORE WESTERLY AND THEREFORE DOWNSLOPE...WHICH WILL HELP
LIMIT INSTABILITY SOMEWHAT...BUT STILL CANNOT RULE OUT A FEW
STRONG STORMS. THINK THE BIGGER ISSUE TO KEEP WATCH FOR WILL BE
THE POTENTIAL FOR LOCALLY HEAVY RAIN DUE TO ABUNDANT TROPICAL
MOISTURE...AND SLOW MOVEMENT OF STORMS DUE TO LIGHT UPPER LEVEL
WINDS.
LOOKING AT A SIMILAR WEATHER PATTERN FOR SUNDAY...WITH SHOWERS
AND THUNDERSTORMS DEVELOPING IN THE WEST DURING EARLY AFTERNOON
AND SPREADING EAST LATER IN THE DAY. HOWEVER...BELIEVE COVERAGE OF
RAINFALL WILL BE GREATER AS AN UPPER LEVEL TROUGH APPROACHES FROM
THE GREAT LAKES...FURTHER DESTABILIZING THE ATMOSPHERE.
ON MONDAY...A DEEP LOW PRESSURE SYSTEM WILL CROSS THE GREAT
LAKES...DRAGGING A COLD FRONT RAPIDLY EASTWARD FROM THE
MISSISSIPPI RIVER VALLEY. WILL AGAIN SEE SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOP...WHICH WILL LINGER INTO LATE EVENING AS THE
COLD FRONT MAKES ITS WAY ACROSS OUR AREA AFTER SUNSET. THIS COLD
FRONT WILL USHER IN A MUCH DRIER CANADIAN AIRMASS...WHICH WILL
BRING AND END TO ALL BUT LINGERING SHOWERS ACROSS OUR WESTERN
RIDGELINES BY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 246 AM EDT FRIDAY...
BY TUESDAY...THE COLD FRONT WILL BE SITUATED ALONG THE EAST
COAST...WITH HIGH PRESSURE BUILDING INTO THE REGION FOR THE
REMAINDER OF THE WORK WEEK. TEMPERATURES IN THIS HIGH PRESSURE
AIRMASS WILL RUN COOLER THAN NORMAL FOR OUR AREA...RANGING FROM
THE MID 70S IN THE WEST TO LOWER 80S IN THE EAST FOR DAILY HIGHS.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 127 PM EDT FRIDAY...
AREAS EAST OF THE BLUE RIDGE STILL UNDER THE INFLUENCE OF A WEAK
INSITU WEDGE. MVFR VISIBILITIES WERE SLOW TO LIFT AND SO IS THE
MVFR CEILINGS. ENOUGH MIXING AND SUNSHINE WILL EVENTUALLY
LIFT/ERODE THESE CLOUDS TO VFR THIS AFTERNOON. WEDGE MAY LINGER
ACROSS THE SOUTHERN HALF OF RNK CWA OVERNIGHT. THIS MAY BRING A
RETURN TO SUB- MVFR FOG AND CLOUDS TO AREAS ALONG THE VA/NC BORDER
(DAN) POSSIBLY AGAIN TO ROA/LYH. IF ENOUGH CLEARING TAKES PLACE
OVERNIGHT...RADIATIONAL IFR OR LOWER VALLEY FOG LIKELY AT LWB/BCB
EARLY SATURDAY MORNING.
RAIN CHANCE THIS AFTERNOON ARE BETTER FOCUS WEST OF THE THETA-E
BOUNDARY ACROSS THE MOUNTAINS. SCATTERED SLOW MOVING STORMS ARE
POSSIBLE AT BLF THROUGH THIS EVENING. ISOLATED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE AT LWB/BCB LATE THIS AFTERNOON AND
EVENING. AREAL COVERAGE SPOTTY THEREFORE WILL ONLY HAVE VICINITY
SHOWERS AT EACH OF THESE AIRPORTS THIS AFTERNOON.
MORE AREAL COVERAGE OF SHOWERS AND STORMS EXPECTED
SATURDAY...ESPECIALLY ACROSS THE MOUNTAINS. THE AREA WILL BE IN A
WARM SECTOR WITH THE DAILY THREAT FOR SHOWERS/STORMS SUNDAY. A
COLD FRONT WILL WORK ACROSS BY LATE MONDAY WITH DRIER AIR MOVING
IN BY THE MIDDLE OF NEXT WEEK. OVERALL OUTSIDE OF LATE NIGHT
FOG/STRATUS AND SUB VFR CONDITIONS IN SHOWERS/STORMS WILL BE
SEEING VFR SAT-TUE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...RCS/WP
SHORT TERM...NF
LONG TERM...RCS
AVIATION...JH/KK/RCS/WP
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
1035 PM PDT Thu Aug 29 2013
.SYNOPSIS...
Warm late-summer weather is expected over the Inland Northwest
through the upcoming holiday weekend. The passage of a cold front
late tonight will deliver a few showers and thunderstorms with a
small chance returning on Friday to the for a small portion of
northeast Washington and the Idaho Panhandle. The Labor Day
weekend is looking warmer than average with an abundance of
sunshine. A transition to a showery weather pattern is expected to
begin Monday and could persist through much of next week.
&&
.DISCUSSION...
Update this evening is to freshen the shower and thunderstorm
potential. The fast moving negatively tilted shortwave has quickly
moved out of the area and we are currently void of any showers and
thunderstorms in our area. There are some pretty decent showers
and thunderstorms developing across western WA and OR and may move
up the Cascades later this evening. So have taken out all evening
weather wording except for in the Cascades. Cold front passes
overnight. HRRR suggests a line of showers and possible
thunderstorms developing from eastern Columbia Basin after
midnight and moving into eastern WA and ID Panhandle overnight
into the early morning hours on Friday. /Nisbet
&&
.AVIATION...
06Z TAFS: Cold front passes overnight with a thin line of showers
and an isolated thunderstorm possible...impacting KGEG...KSFF...KCOE
btwn 07-12z. Post frontal southwesterly winds 10-15 mph with gusts
up to 25 mph can be expected Friday afternoon. VFR conditions
expected at all TAF sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 78 56 82 57 91 / 20 10 0 0 0 0
Coeur d`Alene 57 78 54 81 53 90 / 20 20 0 0 0 0
Pullman 53 78 48 83 49 93 / 10 10 0 0 0 0
Lewiston 64 86 59 89 61 99 / 10 10 0 0 0 0
Colville 56 83 50 85 49 93 / 20 10 0 0 0 0
Sandpoint 54 77 47 79 45 86 / 20 20 0 0 0 0
Kellogg 56 75 53 80 53 88 / 10 20 0 0 0 0
Moses Lake 58 84 54 86 56 93 / 10 10 0 0 0 0
Wenatchee 62 82 59 84 61 89 / 10 0 0 0 0 0
Omak 58 82 55 85 55 91 / 10 10 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
616 PM CDT SAT AUG 31 2013
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 325 PM CDT SAT AUG 31 2013
MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT INTO
SUN...TEMPERATURES.
AT 18Z...WEAK HIGH PRESSURE WAS CENTERED OVER NORTHERN LOWER MI WITH
RIDGING SOUTHWEST INTO NORTHERN IA. LOW PRESSURE WAS OVER SOUTHEAST
MANITOBA WITH A TRAILING COLD FRONT INTO THE EASTERN DAKOTAS.
CONVECTION SLOWLY DEVELOPING ALONG THIS FRONT EARLY THIS AFTERNOON.
SHALLOW LOWER LEVEL MOISTURE/STRATO-CU TRAPPED UNDER AN INVERSION
NEAR 900MB CONTINUED TO PLAGUE SOUTHERN WI/SOUTHEAST MN/EASTERN IA...
BUT CONTINUED TO SLOWLY DISSIPATING WITH DIURNAL WARMING/MIXING AS OF
MID-DAY. MORE COMFORTABLE DAY ACROSS MUCH OF MN/IA/WI...WITH SFC DEW
POINTS IN THE 60S AND TEMPS IN THE MID 70S TO MID 80S.
FOR THE MOST PART...31.12Z MODELS INITIALIZED WELL. GFS WITH ITS
USUAL QUIRKY SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS VALLEY
BUT NAM 850-500MB HGTS DO NOT PROVIDE THE BEST FIT TO THE RA-OBS
HGTS ACROSS MUCH OF CENTRAL NOAM THIS CYCLE. NAM WITH TOO MUCH 850-
500MB SHORTWAVE TROUGHING OVER NORTHEAST MT PER THE GLASGOW MT
RA-OB. DESPITE THIS...SOLUTIONS REMAIN QUITE SIMILAR FOR TONIGHT
THRU SUN NIGHT AS THE SOUTHERN SASKAT SHORTWAVE DROPS SOUTHEAST
ACROSS THE AREA AND INTO THE CENTRAL GREAT LAKES BY 12Z MON.
DPROG/DT OF 500MB HGTS AT 31.12Z SHOWED THE MODEL RUNS OF 29.12Z
AND VERIFIED WELL ACROSS NOAM/EASTERN PAC WITH BETTER RUN-TO-RUN
CONSISTENCY TO ECMWF. TREND THRU TONIGHT/SUN FAVORS FASTER OF AS
THE TROUGH DROPS ACROSS THE REGION THEN FAVORS A TIGHTENING
COMPROMISE OF THE EARLIER RUNS WITH THE TROUGH INTO THE CENTRAL
LAKES SUN NIGHT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL TO BE
REASONABLE WITH THE SOUTHEAST MAN LOW/EASTERN DAKOTAS COLD FRONT. GFS
REMAINED ON THE DRY SIDE WITH SFC DEW POINTS OVER THE MID/UPPER MS
VALLEY. PER WV IMAGERY...ECMWF/GFS/GEM APPEARED BETTER THAN NAM WITH
THE STRENGTH/ POSITION OF THE SOUTHEAST SASKAT SHORTWAVE. GIVEN THIS
AND THE INITIALIZATIONS...FAVORED A NON-NAM CONSENSUS OF THE MODELS
FOR TONIGHT THRU SUN NIGHT. SHORT TERM CONFIDENCE REMAINS ABOVE
AVERAGE.
IN THE SHORT TERM...MAIN SHORTWAVE AND MID/UPPER LEVEL DYNAMICS/LIFT
WITH IT TO PASS TO NORTH OF OR ACROSS THE NORTH END OF THE FCST
TONIGHT/EARLY SUNDAY. MAIN LOWER LEVEL THERMO-DYNAMIC FORCING WITH
THE COLD FRONT PEAKS AROUND 00Z THIS EVENING...THEN GRADUALLY
WEAKENS AS IT COMES EAST AND CROSSES THE FCST AREA LATER THIS
EVENING THRU SUN MORNING. MU CAPE OF 2K-3K J/KG COINCIDENT WITH THE
FRONT/THERMO-DYNAMIC FORCING EARLY THIS EVENING WANES AS WELL AS THE
FRONT/FORCING/LIFT APPROACH/CROSS THE FCST AREA. PW VALUES STILL
PROGGED TO BE AROUND 1.5 INCHES AHEAD OF THE FRONT TONIGHT. RATHER
CONTINUOUS LINE OF CONVECTION EXPECTED TO BE IN PROGRESS FROM NORTH-
CENTRAL MN TO EASTERN SD EARLY THIS EVENING...GRADUALLY WEAKENING/
BECOMING MORE SCT/BKN OVERNIGHT AS IT MOVES INTO ACROSS THE FCST
AREA. CARRIED HIGHEST SHRA/TSRA CHANCES DURING THE LATE EVENING
OVER THE NORTHWEST END OF THE FCST AREA WHEN/WHERE THE LINE OF
CONVECTION WOULD STILL HAVE MORE INSTABILITY/FORCING/LIFT TO WORK
WITH. CONTINUED/TRENDED SHRA/TSRA CHANCES MORE IN THE 20-40 PERCENT
RANGE AFTER MIDNIGHT/SUN MORNING WITH LESS INSTABILITY/FORCING. WITH
THE FASTER MOVEMENT OF THE MID LEVEL TROUGH...TRENDED SHRA/TSRA
CHANCES DOWN/OUT OF THE FCST AREA MORE QUICKLY SUN AFTERNOON.
QUESTION FOR SUN AFTERNOON ONCE THE FRONT/FORCING ARE EAST OF THE
AREA IS EXTENT OF CLOUDS WITH SOME 925-850MB MOISTURE WRAPPING AROUND
THE SFC-MID LEVEL LOW IN DEEP CYCLONIC FLOW...ESPECIALLY OVER THE
NORTH/EAST PORTIONS OF THE FCST AREA. INCREASED CLOUD COVER FOR SUN
AFTERNOON THESE AREAS. CLEARING SUN NIGHT AS THE MID LEVEL LOW
QUICKLY PULLS AWAY AND LOWER LEVEL ANTICYCLONIC FLOW/HIGH PRESSURE
BUILDS INTO THE AREA. 925MB TEMPS IN THE 10C-13C RANGE BY 12Z MON...
FOR COOLER...MORE NEAR NORMAL LOWS MON MORNING. USED A BLEND OF THE
NUMERICAL GUIDANCE LOWS/HIGHS FOR TONIGHT THRU SUN NIGHT.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 325 PM CDT SAT AUG 31 2013
MAIN FORECAST CONCERNS FOR MON THRU TUE NIGHT...FOG POTENTIAL
CENTERED ON DAYBREAK TUE...TEMPERATURES THRU THE PERIOD.
MODELS REMAIN IN GOOD AGREEMENT MON THRU TUE NIGHT AS THE TROUGH
PROGRESSES INTO THE EASTERN CONUS...HGTS RISE AND SHORTWAVE RIDGING
BUILDS INTO THE UPPER MIDWEST. FCST CONFIDENCE IN THIS PERIOD IS
GOOD.
THE CENTER OF THE CANADIAN HIGH DRIFTS FROM NORTHERN MN MON MORNING
TO IL/IN BY WED MORNING. A WEAKENING COLD FRONT SLIDES INTO NORTHERN
WI/CENTRAL MN BY WED MORNING...BUT LIMITED MOISTURE AND MINIMAL
INSTABILITY AHEAD OF IT. THE MON-TUE NIGHT PERIOD CONTINUES TO TREND
DRY/QUIET WITH COOLER/MORE SEASONABLE TEMPS. MONDAY STILL APPEARS AS
THE COOLEST DAY WITH SLOWLY MODERATING TEMPS TUE. COOLEST 925MB OVER
THE AREA AROUND 12Z MON...BUT SOME NORTH GRADIENTS TO KEEP THE
BOUNDARY LAYER STIRRED AND LOWS MON MORNING MOSTLY IN THE 50S. MON
NIGHT THE CENTER OF THE HIGH DRIFTS OVERHEAD WITH LIGHT WINDS/CLEAR
SKIES. 925MB TEMPS TUE MORNING IN THE 12C-15C RANGE...BUT THE
LIGHT/CALM WINDS AND STRONG RADIATIONAL COOLING LOOK TO MAKE TUE
MORNING THE COOLER OF THE MORNINGS...WITH LOWS IN THE MID 40S TO LOW
50S. RADIATIONAL LATE NIGHT/EARLY MORNING VALLEY FOG REMAINS A
CONCERN CENTERED ON 12Z TUE. PREVIOUS FCST GRID SET ALREADY INCLUDED
THIS AND APPEARS WELL TRENDED. USED A BLEND OF THE NUMERICAL
GUIDANCE HIGHS/LOWS FOR MON...TUE/TUE NIGHT. TRENDED TOWARD COOLER
OF GUIDANCE LOWS MON NIGHT WITH THE HIGH OVERHEAD.
FOR WEDNESDAY THROUGH SATURDAY.../DAYS 4-7/...
MEDIUM RANGE MODEL COMING INTO BETTER AGREEMENT WITH A SHORTWAVE TO
DROP SOUTHEAST ACROSS THE EASTERN GREAT LAKES WED...KEEPING THE
REGION UNDER NORTHWEST FLOW ALOFT AND THE RIDGE AXIS OVER THE WESTERN
PLAINS INTO ALB/SASKAT. PATTERN SLOWLY PROGRESSES THU-SAT WITH
RISING HGTS OVER THE UPPER MIDWEST...WHILE THE TROUGHING MOVING
ACROSS THE NORTHERN ROCKIES DEVELOP STRONGER LEE TROUGHING BY LATE
IN THE WEEK. DAY 4-7 FCST CONFIDENCE IS AVERAGE.
IMPROVING MODEL CONSENSUS MOVES A COLD FRONT INTO THE AREA ON WED...
DURING PEAK HEATING. MOISTURE REMAINS IN QUESTION...BUT TREND IS
TOWARD MORE OF AN 850-700MB MOISTURE TRANSPORT/THETA-E CONVERGENCE
SIGNAL...WITH INCREASING PW VALUES INTO THE AREA. MAY YET NEED A
SMALL SHRA/TSRA CHANCE CENTERED ON WED AFTERNOON/EVENING BUT LEFT
THESE PERIODS DRY FOR NOW. POST-FRONTAL CAN HIGH PRESSURE TO
SETTLE ACROSS THE REGION FOR THU. MIXED SIGNALS BY FRI/SAT WITH THE
STRENGTHENING LEE TROUGHING AND SOUTHWEST FLOW AHEAD OF IT PUSHING
INCREASING MOISTURE/INSTABILITY INTO THE UPPER MIDWEST. MAY YET NEED
SHRA/TSRA CHANCES FRI/SAT...DEPENDING ON WHERE ANY LOWER LEVEL
THERMAL/MOISTURE RIDGING AND LOWER LEVEL TOUGHS/BOUNDARIES MAY END
UP. LEFT THU NIGHT THRU SAT DRY FOR NOW PER THE MODEL/ENSEMBLE
CONSENSUS. A WARM-UP ON WED AHEAD OF THE FRONT THEN A BIT OF A COOL-
DOWN ON THU BEHIND THE FRONT...TEMPS GRADUALLY WARM FRI/SAT WITH THE
LOWER LEVEL FLOW BECOMING SOUTH/SOUTHWEST AND THE RISING HGTS ALOFT.
USED THE MODEL/ENSEMBLE CONSENSUS OF NUMERICAL GUIDANCE FOR HIGHS/
LOWS ON WED THRU SAT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 615 PM CDT SAT AUG 31 2013
THE COLD FRONT IS MAKING GOOD EASTWARD PROGRESS AND IS NOW MOVING
INTO WESTERN MINNESOTA. LINE OF CONVECTION OUT AHEAD OF THE FRONT
IS PRIMARILY MOVING EAST AND IF IT CONTINUES ON THIS PATH WOULD
TRACK NORTH OF BOTH TAF SITES. MOST OF THE SHORT RANGE MESO MODELS
CONTINUE TO INDICATE THIS LINE WILL DIMINISH AS IT MOVES EAST WITH
WEAKENING CAPE AND AS IT GETS FARTHER AWAY FROM THE MAIN SHORT
WAVE TROUGH. THIS WAS THE TREND SET FORTH IN THE PREVIOUS
FORECASTS AND FOR NOW WILL STAY WITH THIS BUT WILL CLOSELY MONITOR
THROUGH THE EVENING TO SEE IF THIS OCCURS OR NOT. THE FRONT DOES
APPEAR TO BE MOVING FASTER THAN THE PREVIOUS FORECAST SO BROUGHT
IN THE REMAINS OF THE CONVECTIVE LINE AS SHOWERS FOR THE LATE
EVENING FOR A COUPLE OF HOURS. THE 31.21Z RAP AND 31.21Z HRRR TRY
TO GENERATE MORE SHOWERS OVERNIGHT ALONG THE FRONT AS IT COMES
THROUGH AND TO HONOR THIS...HAVE INCLUDED A VCSH FOR A COUPLE OF
HOURS AFTER THE FRONTAL PASSAGE WHICH SHOULD OCCUR LATE TONIGHT.
WINDS EXPECTED TO COME AROUND TO THE NORTHWEST AND INCREASE TO
OVER 10 KNOTS BEHIND THE FRONT. A LARGE AREA OF CLOUDS BEHIND THE
MAIN SURFACE LOW IS COVERING MUCH OF MANITOBA AND SASKATCHEWAN AND
IS JUST STARTING TO MOVE ACROSS THE BORDER. PREVIOUS FORECAST HAD
THESE COMING IN BY 12Z FOR BOTH TAF SITES WITH MVFR CEILINGS.
LOOKING AT THE 850 MB RELATIVE HUMIDITY CHARTS FOR BOTH THE RAP
AND 31.18Z NAM SUGGESTS THIS WAS TOO FAST AND THE MOISTURE IS NOT
EXPECTED TO ARRIVE UNTIL EARLY TO MID AFTERNOON. BY THAT
TIME...THE MIXING BEHIND THE FRONT MAY BE TOO STRONG AND DEEP TO
ALLOW FOR MORE THAN JUST SCATTERED CLOUDS...SO HAVE REMOVED THE
MVFR CEILINGS FOR NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
354 PM CDT FRI AUG 30 2013
.VERY SHORT TERM...TONIGHT AND SATURDAY.
TONIGHT - CONFIDENCE...MEDIUM
PLENTY OF CAPE POOLING AHEAD OF SOUTHWARD MOVING FRONTAL BOUNDARY.
STORMS ARE ORGAN ZING AS BEST AS THEY CAN GIVEN THE LACK OF DECENT
0-6KM SHEAR AND SUSPECT MID LEVEL LAPSE RATES. HOWEVER PLENTY OF
CAPE IN THE LOW LEVELS WITH GOOD LOW LEVEL LAPSE RATES WITH
SURFACE/925 CONVERGENCE ALLOWING FOR SOME STRONGER WINDS AND HAIL.
WATER VAPOR/RUC COMBO DOES SHOW A WEAK UPSTREAM WAVE RIDING IN
FROM SRN MN AND NRN IA. HRRR SHOWING STORMS CLEARING THE FAR SOUTH
AROUND 00Z OR SO. HOWEVER 4KM WRF-SPC AND 12Z ECMWF LINGER PRECIP
ACROSS PORTIONS OF SC WI DEEPER INTO THE EVENING. BASED ON FRONTAL
PROGRESSION WILL BANK ON A QUICKER EXIT OF PRECIP BASED ON OTHER
MODELS. SO FRONTAL BOUNDARY EXITS TO THE SOUTH THIS EVENING TAKING
ANY LINGERING STORMS WITH IT. WILL RETAIN HEAT ADVISORY FOR SOUTHERN
TIER ONLY AS I-94 CORRIDOR AFFECTED BY OUTFLOW AND STORMS.
SURFACE/925 COOL AIR ADVECTION THEN TAKES HOLD. NOT SO MUCH UP TO
850 MILLIBARS...BUT FROM 925 AND ON DOWN PRETTY STRONG SIGNAL AND
THIS IS PLAUSIBLE GIVEN CONDITIONS UPSTREAM IN NORTHERN WISCONSIN.
EXPECTING COOLER AND DRIER DEW POINTS TO ADVECT INTO THE AREA WITH
THE EVOLVING POST-FRONTAL NORTH WINDS. LOW LEVEL WIND FLOW/DEGREE OF
MIXING SUGGESTS THE EVOLUTION OF DENSE FOG NOT LIKELY. LOOKS MORE
LIKE STRATUS POTENTIAL.
SATURDAY - CONFIDENCE...MEDIUM HIGH PRESSURE SETTLES IN. MORNING
FOG/LOW STRATUS POTENTIAL WILL GRADUALLY BURN OFF. NOT A BIG
DROP OFF IN 850 TEMPS. NEVERTHELESS CU RULE SUPPORTIVE OF SCT
COVERAGE AFTER MORNING STRATUS. 925 TEMPS PROGGD TO 20-23C.
COMFORTABLY COOLER AND LESS HUMID. SO LOW TO MID 80S WITH
MID/UPPER 70S IN THE FAR EAST WITH THE SUSTAINED ONSHORE FLOW.
.SHORT TERM...SATURDAY NIGHT THROUGH MONDAY.
SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
NEXT BEST CHANCE OF PRECIPITATION COMES WITH SHORT WAVE TROUGH AND
COLD FRONT. STILL SOME DIFFERENCES IN CONFIGURATION OF SHORT WAVE
THAT IMPACTS TIMING OF SURFACE TROUGH/COLD FRONT THROUGH REGION.
WILL GO WITH BLENDED SOLUTION THAT BRINGS A CHANCE TO THE NW CWA
BETWEEN 06Z AND 12Z SUNDAY...THEN HIGH CHANCE POPS ACROSS THE
ENTIRE FORECAST AREA DURING THE DAY SUNDAY. SHOULD SEE LOW TO MID
80S HIGHS PRIOR TO ONSET OF PCPN.
SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH.
PRECIPITATION CHANCES LINGER INTO SUNDAY EVENING IN THE EAST WITH
HIGH PRESSURE BUILDING IN BEHIND. LABOR DAY MORE FALL-LIKE WITH
LOW TO MID 70 HIGHS.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE
MEDIUM TO HIGH.
DRY WEATHER AS HIGH PRESSURE DOMINATES THE WESTERN GREAT LAKES REGION
UNDER NORTHWEST FLOW REGIME. MODELS TRY TO BRUSH SW/SOUTHERN CWA
WITH LIGHT QPF WITH A WEAK WAVE/WARM AIR ADVECTION BUT FOR NOW
WILL LEAVE DRY. BELOW NORMAL TEMPERATURES WILL WARM BACK TOWARD
NORMAL LEVELS...OR SLIGHTLY ABOVE...WEDNESDAY THROUGH THE REST OF
THE EXTENDED.
&&
.AVIATION/00Z TAFS/...
THUNDERSTORM POTENTIAL THROUGH 00Z WITH FRONTAL BOUNDARY DROPPING
IN FROM THE NORTH. WINDS WILL SHIFT TO THE NORTH IN THE WAKE OF
THE FRONT WITH THE EVENING FROPA. WILL MONITOR STRATUS TRENDS IN
THE COOL ADVECTION REGIME. EXPECT MVFR CEILINGS AND POTENTIAL FOR
IFR LATER TONIGHT INTO EARLY SATURDAY. THINKING ENOUGH MIXING WILL
INHIBIT DENSE FOG FORMATION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR WIZ067>072.
LM...NONE.
&&
$$
TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR
SATURDAY NIGHT THROUGH FRIDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 AM CDT FRI AUG 30 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 320 AM CDT FRI AUG 30 2013
MAIN FORECAST CONCERNS INCLUDE SHOWER/THUNDERSTORM CHANCES
TODAY...THEN AREAS OF FOG LATE TONIGHT.
WATER VAPOR IMAGERY SHOWING A WELL-DEFINED MID-LEVEL TROUGH MAKING
ITS WAY THROUGH WESTERN LAKE SUPERIOR/NORTHWEST WI. AT THE
SURFACE...A COLD FRONT EXTENDED FROM FROM WESTERN LAKE SUPERIOR TO
JUST EAST OF THE TWIN CITIES...AND INTO SOUTHWEST MN. RADAR MOSAIC
SHOWING ISOLATED-SCATTERED ELEVATED SHOWERS AND THUNDERSTORMS ALONG
THIS FRONTAL BOUNDARY AS IT SINKS SOUTHEASTWARD INTO THE AREA.
FOR TODAY...WILL BE WATCHING THE COLD FRONT AS IT MAKES PASSAGE
THROUGH THE AREA. SHOULD BE SOME ONGOING ISOLATED-SCATTERED
SHOWERS/THUNDERSTORMS ALONG THE FRONT AS IT PRESSES INTO THE AREA.
GFS/NAM DETERMINISTIC MODELS ALONG WITH THE HRRR/HIRES ARW-EAST WRF
MODELS SHOWING THIS CONVECTION UPSCALING A BIT ACROSS PORTIONS OF
FAR SOUTHERN WI INTO NORTHEAST IA THIS AFTERNOON AS THE FRONT PUSHES
INTO A VERY MUGGY AIRMASS WITH 0-1KM MLCAPE OF 2500-3500J/KG ALONG
WITH 0-3KM BULK SHEAR IN THE 20 TO 30KT RANGE. BASED ON THIS
SIGNAL...CANNOT RULE OUT THE THREAT FOR A FEW SEVERE THUNDERSTORMS
ACROSS THIS AREA WITH DAMAGING WINDS AND HAIL BEING THE MAIN
THREATS. ALSO WILL BE GOING WITH A HEAT ADVISORY THIS AFTERNOON FOR
PORTIONS OF FAR SOUTHWEST WI INTO NORTHEAST IA BASED ON HEAT
INDICES CREEPING INTO THE 100-105 DEGREE RANGE. OTHERWISE BEHIND
THE FRONT/ACROSS THE REST OF THE FORECAST AREA...LOOK FOR SOME
RELIEF TO THE MUGGY CONDITIONS WITH DEW POINTS LOWERING INTO THE
65-70 DEGREE RANGE AND TEMPERATURES TOPPING OFF IN THE 80-90 DEGREE
RANGE.
LOOK FOR THE COLD FRONT/SHOWER AND THUNDERSTORM CHANCES TO PUSH
SOUTHWARD OUT OF THE AREA THIS EVENING WITH A RIDGE OF HIGH PRESSURE
BUILDING OVERHEAD THROUGH THE OVERNIGHT HOURS. LIGHT-CALM WINDS
ALONG WITH COOLING LOWER BOUNDARY LAYER WILL SET UP FAVORABLE
CONDITIONS FOR AREAS OF FOG...MAINLY ALONG AND NORTH OF I-94 WHERE
RECENT RAINS HAVE FALLEN AND IN RIVER VALLEYS ACROSS THE REST OF THE
AREA. OVERNIGHT LOWS ARE EXPECTED TO DROP OFF IN THE UPPER 50S TO
THE MIDDLE AND UPPER 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 320 AM CDT FRI AUG 30 2013
NORTHWEST FLOW ALOFT BRINGS ANOTHER FAIRLY VIGOROUS MID-LEVEL
SHORTWAVE TROUGH/SURFACE COLD FRONT INTO THE REGION SATURDAY THROUGH
SUNDAY FOR A DECENT CHANCE OF SHOWERS AND THUNDERSTORMS. TIMING OF
THE FRONTAL PASSAGE BY LATE MORNING/EARLIER IN THE AFTERNOON SHOULD
MITIGATE SEVERE POTENTIAL. WILL HAVE TO KEEP AN EYE ON THE TIMING OF
THE FRONT AS ANY SLOWING TO LATER IN THE AFTERNOON COULD INCREASE
THE SEVERE POTENTIAL. OTHERWISE...HIGH SUNDAY ARE EXPECTED TO TOP
OFF ONLY IN THE MIDDLE 70S TO THE MIDDLE 80S...OR JUST A FEW DEGREES
ABOVE NORMAL. COOLER TEMPERATURES ON TAP FOR SUNDAY NIGHT BEHIND THE
FRONTAL PASSAGE WITH OVERNIGHT LOWS DROPPING INTO THE MIDDLE TO UPPER 50S.
FOR MONDAY THROUGH THURSDAY...GFS AND ECMWF SHOW THE MIDDLE/UPPER
LEVEL RIDGE BUILDING ACROSS THE INTERMOUNTAIN WEST WITH OUR AREA IN
DRY NORTHWEST FLOW ALOFT. COOLER SHOT OF AIR WITH 850MB TEMPERATURES
IN THE 5-10C RANGE MOVES OVER THE AREA ON MONDAY FOR HIGHS IN THE
UPPER 60S TO THE MIDDLE 70S. TEMPERATURES LOOK TO HOLD RIGHT AROUND
NORMAL LEVELS FOR TUESDAY THROUGH THURSDAY WITH HIGHS IN THE MIDDLE
70S TO AROUND 80S AND OVERNIGHT LOWS MAINLY IN THE 50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT
1143 PM CDT THU AUG 29 2013
AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR
LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO
SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT
AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST
WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD
FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL
SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO
MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION
SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS
CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE
WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING
THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT
MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME
DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE
CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT
WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO
WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES
THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG
MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA
INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM
AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH
JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE
FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE
DIMINISHING FRIDAY EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING
FOR WIZ061.
MN...NONE.
IA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING
FOR IAZ018-019-029-030.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY TONIGHT)
ISSUED AT 328 PM CDT THU AUG 29 2013
MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT/
FRI...TEMPS/HEAT/HUMIDITY FRIDAY.
DATA ANALYSIS AT 18Z HAD HIGH PRESSURE OVER LOWER MI AND LOW
PRESSURE OVER EASTERN ND WITH TOUGHING FROM LK WINNIPEG TO EASTERN
CO. DIFFUSE/ILL-DEFINED WARM FRONT WAS LOCATED FROM THE ND LOW
TO NEAR THE MS RIVER THRU THE FCST AREA. MAIN FORCING/LIFT/MOISTURE
CONVERGENCE WAS INTO NORTHERN MN...WHERE A MATURE CONVECTIVE COMPLEX
WAS MOVING INTO WESTERN LK SUPERIOR. ACROSS WI/IA/REST OF MN...WARM
TEMPS IN THE 800-700MB LAYER CONTINUED TO CAP THE AIRMASS EARLY THIS
AFTERNOON...EVEN WITH SFC DEW POINTS IN THE UPPER 60S/LOW 70S AND
TEMPS IN THE MID 80S/LOW 90S. LAPS SOUNDINGS SHOWING CONVECTIVE TEMPS
IN THE 98F-108F RANGE.
NO BIG PROBLEMS NOTED WITH 29.12Z INITIALIZATIONS. GFS WITH ITS
USUAL SLIGHTLY OFF SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS
VALLEY. SOLUTIONS REASONABLY SIMILAR FOR TONIGHT THRU FRI NIGHT
WITH THE MAIN FORCING/LIFT SHRA/TSRA CHANCE PASSING NORTH OF THE
FCST AREA THEN A WEAK COLD FRONT TO SLIDE ACROSS THE AREA FRI.
DPROG/DT OF 500MB HGTS AT 29.12Z SHOWED THE MODEL RUNS OF 27.12Z AND
28.12Z VERIFIED QUITE WELL ACROSS NOAM...WITH STRONGER OF EARLIER
RUNS BETTER ON THE SHORTWAVE APPROACHING LK WINNIPEG. TREND FAVORS
STRONGER OF EARLIER RUNS AS THE LK WINNIPEG WAVE CROSSES LK
SUPERIOR THRU TONIGHT...AND STRONGER WITH THE NEXT WAVE TO TOP THE
MID NOAM RIDGE MOVING INTO WA/SOUTHERN BC. TREND CONTINUES TO FAVOR
STRONGER/FASTER OF EARLIER MODELS AS THIS WAVE MOVES INTO SASKAT/
EASTERN MT BY 12Z SAT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL
TO BE REASONABLE WITH THE SFC MASS FIELDS OVER THE CENTRAL CONUS.
PER WV IMAGERY...NON-NAM MODELS LOOKED BETTER WITH THE SHORTWAVE
PASSING ACROSS SOUTHERN MANITOBA. MODELS ALL GENERALLY TOO FAR
SOUTH WITH THE 12-18Z PRECIP IN EASTERN MN/WESTERN WI...AND NOT
STRONG ENOUGH WITH THE TSRA COMPLEX NEAR KDLH. NO ONE MODEL LOOKED
PREFERRED THIS CYCLE. WITH A RATHER TIGHT CONSENSUS AMONG THE
MODELS...EVEN WITH THE TRENDS ON THE SHORTWAVES OF INTEREST...
FAVORED THE MODEL/ENSEMBLE CONSENSUS. SHORT-TERM FCST CONFIDENCE
IS GOOD THIS CYCLE.
IN THE SHORT TERM...FIRST SHORTWAVE TRACKS EAST/SOUTHEAST AND ACROSS
LK SUPERIOR TONIGHT. BULK OF FORCING/CONVERGENCE/LIFT WITH THIS
FEATURE...AND HIGHER SHRA/TSRA CHANCES PASS NORTHEAST OF OR JUST
CLIP THE NORTHEAST END OF THE FCST AREA. ATTENDANT SFC LOW/TROUGH
DRAGS A COLD FRONT INTO THE AREA LATER TONIGHT...TO NEAR A KAUW-KLSE-
KMCW LINE BY 12Z FRI. NOT MUCH FOR LOWER LEVEL THERMO-DYNAMIC
FORCING WITH THIS FRONT/BOUNDARY AS IT PUSHES INTO/ACROSS THE FCST
AREA LATE TONIGHT/FRI MORNING. SOME WEAK 925MB THETA-E CONVERGENCE...
BUT THESE PARCELS FIGHTING CIN TO 650MB OR NO CAPE AT ALL. THUS
MODELS ONLY GENERATE SOME ISOLATED/WDLY SCT SHRA/TSRA WITH THIS
FRONTAL PASSAGE. LEFT SOME 20-40 PERCENT SHRA/TSRA CHANCES OVER THE
NORTHEAST END OF THE FCST AREA TONIGHT. ONLY CARRIED 20 PERCENT
SHRA/TSRA CHANCES OVER THE CENTRAL/WEST PARTS OF THE FCST AREA WITH
THE FRONTAL PASSAGE LATE TONIGHT/FRI MORNING. LEFT SOME 20-40
PERCENT SHRA/TSRA CHANCES OVER THE SOUTHEAST HALF OF THE FCST AREA
FRI AFTERNOON INTO FRI EVENING...DUE TO PROXIMITY OF THE BOUNDARY AND
ML CAPE VALUES RISING INTO THE 1.5. TO 2.5 K J/KG RANGE. 0-6KM BULK
SHEAR IN THE 25-30KT RANGE FRI AFTERNOON...ISOLATED SEVERE STORMS
WITH A HAIL OR WIND THREAT CANNOT BE RULED OUT.
AHEAD OF THE FRONT...HEAT INDICES WILL AGAIN CLIMB INTO THE 90-100
RANGE OVER THE SOUTHEAST THIRD OF THE FCST AREA FRI AFTERNOON/EARLY
FRI EVENING. MAY YET NEED A HEAT ADVISORY FOR THE SOUTHEAST END OF
THE FCST AREA CENTERED ON FRI AFTERNOON...BUT IF SCT SHRA/TSRA
DEVELOP AND SKIES BECOME MORE CLOUDY THAN SUNNY...HEAT INDICES
WOULD NOT REACH 100...AT LEAST FOR MORE THAN AN HOUR AT ANY ONE SPOT.
WEAK BUBBLE HIGH SETTLES OVER THE AREA FRI NIGHT. WITH LIGHT WINDS...
CLEAR/MOSTLY CLEAR SKIES...COOLER 925-850MB TEMPS AND STRONG
RADIATIONAL COOLING EXPECTED...CONTINUED THE MENTION OF PATCHY TO
AREAS OF FOG IN GRIDS FOR LATER FRI NIGHT INTO EARLY SAT MORNING.
USED A MODEL/ENSEMBLE CONSENSUS OF LOWS/HIGHS FOR TONIGHT THRU FRI
NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 328 PM CDT THU AUG 29 2013
MAIN FORECAST CONCERNS FOR SAT THRU SUN NIGHT...TEMPERATURES/HEAT
POTENTIAL SATURDAY...SHRA/TSRA CHANCES SAT NIGHT/SUN.
THE STRONGER/TREND WITH THE MT/SASKAT SHORTWAVE CONTINUES SAT/SAT
NIGHT AS IT MOVE INTO MN/WESTERN ONT BY 12Z SUN...THEN PASSES
ACROSS THE REGION SUN...PUSHING A RATHER STRONG COLD FRONT THRU THE
AREA. AGAIN WITH A RATHER TIGHT CONSENSUS/SHIFT BY ALL MODELS...
FAVORED THE MODEL/ENSEMBLE CONSENSUS FOR SAT THRU SUN NIGHT.
WEAK HIGH PRESSURE REMAINS OVER THE AREA SAT. WITH DIURNAL WARMING/
MIXING...AND SOME DRIER 925-850MB AIR OVER THE REGION...SFC DEW
POINTS LOOKING TO BE MORE IN THE LOW-MID 60S SAT AFTERNOON. SAT
AFTERNOON HEAT INDICES TRENDING TO TOP OUT MORE IN THE 85-90 RANGE...
FOR A LITTLE MORE RELIEF FROM THE RECENT HEAT/HUMIDITY. MOISTURE
TRANSPORT INCREASES INTO THE AREA SAT NIGHT WITH PW VALUES BACK IN
THE 1.5 INCH RANGE BY 12Z SUN. STRONGER/DEEPER LOWER LEVEL THERMO-
DYNAMIC FORCING INDICATED WITH APPROACH/PASSAGE OF THE TROUGH/FRONT
LATE SAT NIGHT/SUN MORNING. THIS ALONG WITH SOME 400-200MB PV
ADVECTION AHEAD OF THE STRONGER SHORTWAVE...AND MU CAPE VALUES OF
AROUND 1K J/KG LIFTING 900-800MB PARCELS. CONTINUED/RAISED SHRA/
TSRA CHANCES CENTERED ON LATE SAT NIGHT/SUN MORNING IN THE 30- 50
PERCENT RANGE. TRENDED SHRA/TSRA CHANCES DOWN SUN AFTERNOON WITH
PASSAGE OF THE FRONT/LIFT AND LOWER LEVEL COLD ADVECTION/DRYING
SPREADING SOUTHEAST ACROSS THE AREA. SOME BRISK/GUSTY NORTHWEST
WINDS SUN AFTERNOON WITH THE COLD ADVECTION AND MIXING TO AT LEAST
850MB. DRY/COOLER SUN NIGHT AS CAN HIGH PRESSURE SETTLES INTO THE
NORTHERN PLAINS/WESTERN GREAT LAKES AND 850MB TEMPS FALL INTO THE
8C-12C RANGE BY MON MORNING. AGAIN USED A MODEL/ENSEMBLE CONSENSUS
OF THE NUMERICAL GUIDANCE FOR HIGHS/LOWS SAT THRU SUN NIGHT.
FOR MONDAY/LABOR DAY THROUGH THURSDAY.../DAYS 4-7/...
LATEST MEDIUM RANGE MODEL RUNS REMAIN IN GOOD AGREEMENT MONDAY
WITH RATHER STRONG TROUGHING TO BE OVER ONT/GREAT LAKES AND RIDGING
TO BE BUILDING NORTHWARD INTO SASKAT/MANITOBA. GOOD CONSISTENCY FOR
HGTS TO RISE OVER THE REGION TUE AS THE TROUGHING MOVES INTO
EASTERN NOAM...BUT MN/WI/IA TO REMAIN UNDER RATHER STRONG NORTHWEST
FLOW ALOFT. 29.00Z WERE DIFFERENT FOR WED/THU...WITH STRENGTH OF
A SHORTWAVE TROUGH TO DROP DOWN THE EAST SIDE OF THE RIDGE AND
INTO THE EASTERN NOAM TROUGH. 29.12Z MODELS HAVE TRENDED TOWARD A
COMPROMISE ON THE TIMING/STRENGTH OF THIS FEATURE AND THE
TROUGHING OVER EASTERN NOAM WED/THU. 29.12Z GFS/ECMWF WITH BETTER
CONSENSUS ON THE NEXT TROUGHING MOVING INTO THE NORTHWEST
CONUS/WESTERN CAN ON DAYS 6/7 TOO. FCST CONFIDENCE GOOD FOR
MON/TUE THEN AVERAGE WED/THU.
STRONG PASSING COLD FROM SUNDAY USHERS A COOLER/DRIER CAN HIGH
PRESSURE SYSTEM INTO THE UPPER MIDWEST FOR MON/TUE. BY LABOR DAY
MORNING...925MB TEMPS IN THE 11C-14C RANGE ACROSS THE FCST AREA.
THESE TEMPS SLOWLY MODERATE THRU MON/TUE BUT ONLY RECOVER TO THE 19C-
21C RANGE BY TUE EVENING. MON/TUE STILL LOOKING LIKE A A COUPLE OF
COOLER...COMFORTABLE DAYS COMPARED TO THE PAST SEVERAL DAYS. LIKE
PREVIOUS FORECASTER STATED...MAY NEED A VALLEY FOG MENTION CENTERED
ON DAYBREAK TUE...BUT WILL LEAVE THAT OUT OF THE GRIDS FOR NOW GIVEN
THE SENSITIVITY OF VALLEY FOG TO LOWER LEVEL/BOUNDARY LAYER NUANCES.
EVEN WITH SHORTWAVE/TROUGH STRENGTH DIFFERENCES BY WED...BOTH GFS/
ECMWF PUSH A COLD FRONT SOUTHEAST ACROSS THE REGION WED. MOISTURE/
CAPE CONTINUE TO LOOK LIMITED AHEAD OF/WITH THIS FEATURE. SMALL
SHRA/TSRA CHANCE AT BEST WED BUT WILL LEAVE THIS PERIOD DRY FOR
NOW PER THE MODEL/ENSEMBLE CONSENSUS. NORTHWEST FLOW ALOFT SENDS
ANOTHER CAN HIGH SOUTH INTO THE REGION FOR THU BUT CORE OF THE
COOLEST 925-850MB AIR WITH THIS HIGH REMAINS NORTH/EAST OF THE
FCST AREA AS IT BUILDS IN. EVEN WITH SOME MODEL DIFFERENCES...
GUIDANCE HIGHS/LOWS FOR MON-THU NOT THAT DIFFERENT AND USED THE
MODEL/ENSEMBLE CONSENSUS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1143 PM CDT THU AUG 29 2013
AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR
LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO
SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT
AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST
WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD
FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL
SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO
MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION
SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS
CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE
WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING
THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT
MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME
DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE
CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT
WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO
WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES
THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG
MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA
INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM
AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH
JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE
FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE
DIMINISHING FRIDAY EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1030 AM MDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1022 AM MDT FRI AUG 30 2013
STILL SEEING LOW TO MID 60 DEWPOINTS IN THE PANHANDLE THIS
AFTERNOON. LATEST HRRR RADAR COMPOSITE FORECAST SHOWING SHOWERS
DEVELOPING OVER THE LARAMIE RANGE AROUND 20Z AND THEN DRIFTING OFF
AND MOVING EAST INTO THE PANHANDLE AROUND THE 22Z TO 02Z
TIME FRAME. WENT AHEAD AND INCREASED POPS IN THE PANHANDLE TO
CHANCE/SCATTERED CATEGORY FOR THIS TIME FRAME. THOUGH PWATS ARE NOT
FORECAST TO BE TOO HIGH...GENERALLY AROUND .8 INCHES...FORECAST
STORM MOTIONS ARE FAIRLY SLOW...GENERALLY UNDER 6KTS...SO WE COULD
SEE SOME ISOLATED HEAVY RAIN SHOWERS OUT THAT WAY. ALSO A FEW
STRONG TO SEVERE THUNDERSTORMS ARE NOT TOTALLY OUT OF THE QUESTION
WITH AFTERNOON CAPE VALUES AROUND 1500 TO 200 J/KG. UPDATES HAVE
BEEN SENT.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 335 AM MDT FRI AUG 30 2013
ANOTHER HOT DAY TO END THE WORK WEEK WITH HIGH TEMPERATURES MAINLY
IN THE 90S ACROSS THE PLAINS AND AROUND 100 DEGREES FOR SOME
LOCATIONS. HIGHER ELEVATIONS WILL GENERALLY SEE HIGH TEMPERATURES
IN THE 80S. THE UPPER LEVEL RIDGE WHICH IS RESPONSIBLE FOR THE
ABOVE NORMAL TEMPERATURES WILL TEMPORARILY BREAK DOWN THIS
WEEKEND...PROVIDING A LITTLE RELIEF TO THE HOT WEATHER BUT THE
RIDGE WILL REBUILD EARLY NEXT WEEK WITH DAYTIME TEMPERATURES WELL
ABOVE NORMAL WITH SOME RECORD HIGHS A GOOD POSSIBILITY.
A SUBTLE SHORTWAVE CURRENTLY MOVING ACROSS NIOBRARA COUNTY AND FAR
SOUTHWEST SOUTH DAKOTA HAS PRODUCED A FEW SHOWERS AND EVEN SOME
LIGHTING STRIKES EARLY THIS MORNING. CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL MAINLY PUSH EAST OF THE AREA AFTER SUNRISE AS
THE WAVE EXITS THE FORECAST AREA. MODELS DO SHOW AND WEAK MID
LEVEL FRONT HANGING OVER THE NEBRASKA PANHANDLE AT 12Z BUT FORCING
WEAK ENOUGH THAT NOT EXPECTING MUCH MORE THAN SOME ACCAS
CLOUDS...MAYBE A FEW SPRINKLES. MAIN CHANCE FOR PRECIPITATION WILL
HOLD OFF UNTIL THIS AFTERNOON AS CONVECTIVE TEMPERATURES ARE
REACHED. SHOULD SEE CONVECTION INITIATE FIRST OVER THE MOUNTAINS
THEN MOVING OFF THE MOUNTAINS BY MID AFTERNOON. MAY ALSO SEE
STORMS FIRE OFF OVER THE NEBRASKA PANHANDLE MID AFTERNOON.
SEVERE THUNDERSTORM POTENTIAL IS LOW BUT NOT COMPLETELY OUT OF THE
QUESTION INTO THE NEBRASKA PANHANDLE. 0-6 KM SHEAR MAY PUSH 40 KTS
OVER NORTHERN PORTIONS OF THE FORECAST AREA WITH SURFACE BASED
CAPE 1000-1500 J/KG INTO THE NEBRASKA PANHANDLE. IF THUNDERSTORMS
DEVELOP OVER THE PANHANDLE...ONE OR TWO MARGINALLY SEVERE
THUNDERSTORMS POSSIBLE. GUSTY WINDS WILL BE THE MAIN CONCERN
FARTHER WEST WHERE THE TYPICAL INVERTED-V SOUNDING WILL ONCE AGAIN
BE IN PLACE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 335 AM MDT FRI AUG 30 2013
QUITE WARM CONDITIONS EXPECTED ACROSS THE CWA DURING THE PERIOD AS
AN UPPER HIGH DRIFTS OVER THE SOUTHERN AND CENTRAL ROCKIES EARLY
IN THE WEEK THEN SHIFTS EAST OVER THE PLAINS THURSDAY. ISOLATED
MAINLY MTN CONVECTION POSSIBLE EARLY IN THE WEEK WHERE BEST
INSTABILITY SHOULD BE REALIZED THEN AS THE WEEK PROGRESSES SOME
SUBTROPICAL MOISTURE SHOULD SPREAD OVER AT LEAST SE WYOMING
ALLOWING FOR AN UPTICK IN CONVECTION THERE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 515 PM MDT THU AUG 29 2013
VFR CONDITIONS EXPECTED OVERALL THROUGH THE TAF PERIOD. ISOLATED
SHOWERS AND A FEW STORMS WILL MOVE ACROSS THE AREA THIS AFTERNOON
INTO THIS EVENING. BRIEF GUSTY WINDS AND MVFR VSBYS POSSIBLE WITH
ANY STORMS.
&&
.FIRE WEATHER...
ISSUED AT 335 AM MDT FRI AUG 30 2013
FIRE WEATHER CONCERNS ARE MINIMAL AS WINDS WILL REMAIN ON THE
LIGHT SIDE THE NEXT SEVERAL DAYS. THE HOT AND DRY CONDITIONS DOES
MAKE THE POTENTIAL FOR FIRE STARTS A GREATER RISK...SUCH THAT
LIGHTNING WITH THUNDERSTORMS DOES POSE SOME FIRE START THREAT THE
NEXT FEW AFTERNOONS. NOT EXPECTING WIDESPREAD DRY LIGHTNING BUT A
FEW DRY STRIKES ARE POSSIBLE MAINLY INTO SOUTHEAST WYOMING WEST OF
THE LARAMIE RANGE.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...CLAYCOMB
SHORT TERM...LIEBL
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...LIEBL
AREA FORECAST DISCUSSION
NWS ALBANY NY
439 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY
OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 435 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL
BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG
IT HAS SHIFTED DOWN STREAM INTO SRN NEW ENGLAND. SOME DUAL POL QPE
VALUES OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE
SRN TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX
RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE
MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL
DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND.
THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS
REMAIN MUGGY FOR THE OPENING DAY OF SEPT.
THE MORNING SHOULD BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE
REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START
OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP
NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY
INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING
BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD
BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST
3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO
INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF
THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL
WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL
/1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE
SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN
THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE
CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S.
NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL
LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED
CONVECTION.
ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY
CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME
SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO
M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE
SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM
THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF
LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE
ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT
THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND
EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN
SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE
DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL
ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL
DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR
LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY
IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS.
LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE
MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN
THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT
ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS
IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME
STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A
BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE
MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY.
PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A
COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM
500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO
25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE
POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT
OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER
LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM
OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET
WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY
HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT
LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE
MONITORED.
OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS
VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND
U60S TO M70S OVER THE HIGH PEAKS.
MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE
PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES
NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND
U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES.
TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE
HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY
COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS
POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS
FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL
HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S
TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS
WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH
SOME U40S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL
REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD.
WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS
IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A
MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS
WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY
THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5
DEGREES BELOW NORMAL.
TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS
FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR
SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP.
HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND
STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW
OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL
BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS
A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW
PASSES TO OUR NORTH.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION
WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE
BOUNDARY. THE RADAR IS QUIET ACROSS THE FORECAST AREA AT THIS TIME
AND A LULL IN THE CONVECTION IS EXPECTED ACROSS THE LOCAL AREA INTO
THIS AFTERNOON. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN
AND DISSIPATE. CHANCES FOR CONVECTION WILL INCREASE MID TO LATE
AFTERNOON AND ESPECIALLY TONIGHT AS A STRONGER SHORT WAVE APPROACHES
WITH HEIGHT FALLS OCCURRING ACROSS THE REGION.
MVFR TO LIFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE
TO FOG AND CIGS. CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING.
VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH
CONDITIONS LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR
SHOWERS AND THUNDERSTORMS INCREASES.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY
NIGHT.
OUTLOOK...
MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID
AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO
TUESDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE
RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND
REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT.
EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY.
LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS
OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR
WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW
INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON
SATURDAY AND THIS MORNING.
ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE
POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN
BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS
OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME.
HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING
THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR
DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING
INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF
THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY.
RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE
THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3
INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW
CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE
SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE
TO MONITORED FOR ANY HYDRO ISSUES.
COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID
WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
153 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW
YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK
DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL
SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY
RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR
DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER
THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES
AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW
PRESSURE OVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A
RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING
MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30
KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN
THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE
BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR
OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY
AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO
ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD
ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW
SPOTS.
THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES
HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO
SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING
CONVECTION. A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER
COUNTY AS OF 05Z.
PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR
LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC
TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY
SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME
CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK
ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE
FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS
ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING
THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME
SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR
THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN
PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND
THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE
WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES.
THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT
AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH
MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED.
THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE
THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING
LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS
TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A
WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS
OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH
THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN
THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO
SLIGHTLY BELOW NORMAL.
FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED
WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD
FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH
ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT
THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST
POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT.
WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR
WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA
WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED
SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO
THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY
FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR
WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES.
ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO
PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS
ON SATURDAY WITH THE FRONTAL PASSAGE.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION
WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE
BOUNDARY. A CLUSTER OF SHOWERS AND THUNDERSTORMS BETWEEN KPSF AND
KPOU WILL CONTINUE TO MOVE EASTWARD IN ASSOCIATION WITH A SHORT WAVE
TROUGH WITH ADDITIONAL SCATTERED CONVECTION DEVELOPING JUST TO THE
NORTH WHICH WILL IMPACT KPSF. ONCE THE SHORT WAVE TROUGH MOVES OFF
TO THE EAST EXPECTING A LULL IN THE CONVECTION WELL INTO THIS
AFTERNOON. GUIDANCE INDICATES THE BOUNDARY WILL WEAKEN AND DISSIPATE
OVER THE AREA. CHANCES FOR CONVECTION WILL INCREASE MID/LATE THIS
AFTERNOON AND ESPECIALLY THIS EVENING AS A STRONGER SHORT WAVE
APPROACHES CAUSING HEIGHT FALLS ACROSS THE REGION.
MVFR/IFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE TO
FOG AND CIGS WITH AN IMPROVEMENT BY LATE MORNING. VFR CONDITIONS
ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING
TO MVFR AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASES.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN TONIGHT.
OUTLOOK...
TUE: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
TUE NIGHT-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON
AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL
CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS
AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND
CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY
AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED
IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING
ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND
MONDAY.
THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH
VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH
TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20
MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD
RAINFALL WILL BE TODAY AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME
MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE
SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS
TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW
MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE
WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SND/WASULA
NEAR TERM...HWJIV/WASULA
SHORT TERM...SND
LONG TERM...SND
AVIATION...IAA
FIRE WEATHER...SND
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
140 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW
YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK
DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL
SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY
RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR
DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER
THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES
AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW
PRESSURE OVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A
RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING
MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30
KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN
THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE
BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR
OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY
AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO
ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD
ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW
SPOTS.
THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES
HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO
SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING CONVECTION.
A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER COUNTY AS OF
05Z.
PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR
LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC
TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY
SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME
CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK
ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE
FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS
ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING
THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME
SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR
THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN
PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND
THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE
WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES.
THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT
AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH
MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED.
THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE
THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING
LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS
TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A
WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS
OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH
THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN
THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO
SLIGHTLY BELOW NORMAL.
FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED
WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD
FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH
ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT
THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST
POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT.
WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR
WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA
WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED
SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO
THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY
FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR
WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES.
ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO
PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS
ON SATURDAY WITH THE FRONTAL PASSAGE.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION
WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE
BOUNDARY. A CLUSTER OF SHOWERS AND THUNDERSTORMS BETWEEN KPSF AND
KPOU WILL CONTINUE TO MOVE EASTWARD IN ASSOCIATION WITH A SHORT WAVE
TROUGH. ONCE THE SHORT WAVE TROUGH MOVES OFF TO THE EAST EXPECTING
A LULL IN THE CONVECTION WELL INTO THIS AFTERNOON. GUIDANCE INDICATES
THE BOUNDARY WILL WEAKEN AND DISSIPATE OVER THE AREA. CHANCES FOR
CONVECTION WILL INCREASE MID/LATE THIS AFTERNOON AND ESPECIALLY
THIS EVENING AS A STRONGER SHORT WAVE APPROACHES CAUSING HEIGHT
FALLS ACROSS THE REGION.
MVFR/IFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE TO
FOG AND CIGS WITH AN IMPROVEMENT BY LATE MORNING. VFR CONDITIONS
ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING
TO MVFR AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASES.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN TONIGHT.
OUTLOOK...
TUE: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
TUE NIGHT-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON
AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL
CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS
AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND
CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY
AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED
IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING
ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND
MONDAY.
THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH
VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH
TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20
MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD
RAINFALL WILL BE TODAY AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME
MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE
SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS
TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW
MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE
WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SND/WASULA
NEAR TERM...HWJIV/WASULA
SHORT TERM...SND
LONG TERM...SND
AVIATION...IAA
FIRE WEATHER...SND
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
124 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW
YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK
DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL
SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY
RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR
DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER
THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES
AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW
PRESSUREOVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A
RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING
MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30
KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN
THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE
BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR
OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY
AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO
ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD
ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW
SPOTS.
THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES
HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO
SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING CONVECTION.
A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER COUNTY AS OF
05Z.
PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR
LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC
TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY
SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME
CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK
ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE
FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS
ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING
THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME
SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR
THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN
PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND
THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE
WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES.
THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT
AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH
MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED.
THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE
THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING
LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS
TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A
WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS
OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH
THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN
THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO
SLIGHTLY BELOW NORMAL.
FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED
WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD
FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH
ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT
THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST
POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT.
WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR
WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA
WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED
SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO
THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY
FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR
WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES.
ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO
PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS
ON SATURDAY WITH THE FRONTAL PASSAGE.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
AS OF 1015 PM EDT...A FEW MORE SHOWERS AND THUNDERSTORMS HAVE POPPED
UP NEAR THE POUGHKEEPSIE AREA. OTHERWISE...THE CONVECTION HAS PRETTY
MUCH WEATHER DOWN. PLACED A VCTS FOR AN HOUR OR SO THERE ALONG WITH
AN HOUR LONG TEMPO FOR MVFR THUNDERSTORM THROUGH 03Z.
ANY PARTIAL CLEARING HAS COME TO A HALT AS THERE WERE PLENTY OF HIGH
AND MID LEVEL CLOUDS.
LOW STRATUS HAS ALREADY TAKEN PLACE AT KGFL AT KPSF WILL LIKELY FORM
AT THE OTHER TAF SITES IN THE NEXT COUPLE OF HOURS. RIGHT NOW WE
STILL FEEL THE BEST FOR IFR WILL BE KGFL (ALREADY HAPPENING) AND
KPSF...WITH LOW MVFR AT KPOU AND HIGH END MVFR AT KALB.
HOWEVER...THIS IS A MODERATE CONFIDENCE FORECAST SO PLEASE CHECK
BACK IF YOU PLAN TO FLY TOWARD DAYBREAK!
IT WILL PROBABLY TAKE UNTIL AROUND 14Z TO LOOSE THE STRATUS AND FOG.
AFTER THAT...WE EXPECT VFR CONDITIONS TO PREVAIL. WE DID PLACE IN A
VCSH AS WE EXPECT SCATTERED CONVECTION TO DEVELOP IN THE
AFTERNOON...BUT IT DOES NOT LOOK TO BE AS NUMEROUS AS TODAY/S.
AS A POTENT UPPER LEVEL DISTURBANCE APPROACHES SUNDAY...CONVECTION
LOOKS TO RAMP UP.
THE VERY LIGHT SURFACE WIND WILL BECOME SOUTHERLY 5-10KTS ON
SUNDAY.
OUTLOOK...
SUNDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON
AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL
CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS
AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND
CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY
AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED
IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING
ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND
MONDAY.
THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH
VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH
TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20
MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD
RAINFALL WILL BE TODAY AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME
MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE
SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS
TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW
MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE
WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SND/WASULA
NEAR TERM...WASULA
SHORT TERM...SND
LONG TERM...SND
AVIATION...HWJIV
FIRE WEATHER...SND
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
324 AM EDT SUN SEP 1 2013
.SHORT TERM /TODAY THROUGH MONDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY
REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND
SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN
AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC
BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF
FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT
SHOULD BEGIN TO BURN OFF AFTER SUNRISE.
THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/
THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA
DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS
THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE
NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS
UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE
TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR
OUTPUT.
MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS
NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO
FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP
THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL
MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT
HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO
BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS
FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN.
THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP
SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED
DEVELOP...POPS MAY HAVE TO BE RAISED.
FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND
CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW
AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF
SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR
MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION...
LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE
ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING
OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS.
NLISTEMAA
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO...
TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED
COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE
ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE
COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT
AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST
DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE
COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON
THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS
TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING
IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST
MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE
INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS
FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS
DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS
UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE
AREA ON SATURDAY.
AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL
TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A
COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE
NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT
LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY
IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG
SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE
COOLEST DAY OF THE PERIOD.
TDP
&&
AVIATION...
06Z UPDATE...
PATCHY FOG HAS DEVELOPED AT QUITE A FEW OF THE TERMINAL SITES THIS
MORNING. FOR THE NORTHERN TERMINAL SITES...VSBYS/CIGS SHOULD
REMAIN IN THE MVFR RANGE. EVEN ATL HAS A CHANCE AT 4SM AND BKN012
AFTER RECEIVING RAINFALL TODAY. MCN WILL HAVE THE BEST CHANCE AT
SEEING 1/2SM IN FG TOWARDS SUNRISE. BKN DIURNAL CU BTWN 040 AND
050 EXPECTED TODAY. BEST TIMES FOR CONVECTION ARE BETWEEN 19Z AND
01Z. LOW CIGS A POSSIBILITY FOR OVERNIGHT SUN/EARLY MON.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON CIGS/VSBYS THROUGH 13Z. OTHERWISE...HIGH
CONFIDENCE ALL ELEMENTS.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 89 70 90 70 / 50 40 40 40
ATLANTA 89 73 88 72 / 50 40 30 40
BLAIRSVILLE 83 66 84 65 / 60 50 50 30
CARTERSVILLE 90 70 89 70 / 50 50 40 50
COLUMBUS 92 74 90 74 / 40 30 30 20
GAINESVILLE 86 71 87 70 / 50 50 50 30
MACON 92 71 89 71 / 40 30 30 30
ROME 92 71 90 69 / 50 50 50 40
PEACHTREE CITY 88 71 89 70 / 50 40 30 30
VIDALIA 91 73 90 73 / 40 30 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...NLISTEMAA
LONG TERM....TDP
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
359 AM CDT SUN SEP 1 2013
.DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* PATCHY GROUND FOG CONTINUES TO DEVELOP WITH VSBY REDUCTIONS
EXPECTED THROUGH DAYBREAK.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY AFT 21Z.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY MOIST AND CALM AIRMASS OVERHEAD...WITH THINNING STRATUS CLOUD
COVER. THIS ALL POINTS TOWARDS PATCHY FOG DEVELOPING AND REDUCING
VSBYS TO MVFR AND A FEW AREAS OF IFR. WITH THE LACK OF A GRADIENT
OVERNIGHT...WINDS WILL BECOME NEARLY CALM IN A FEW LOCATIONS. THIS
SHOULD AID IN FOG FORMATION ALONG WITH RECENT RAINFALL.
THEN AFT DAYBREAK HEATING SHOULD PROVIDE SOME
INSTABILITY...HOWEVER NOT EXPECTING ANY SHRA/TSRA TO DEVELOP UNTIL
THE FRONTAL BOUNDARY APPROACHES THE REGION FROM THE NORTHWEST. AT
THIS TIME CURRENT GUIDANCE WOULD SUGGEST LIGHT WINDS FROM THE
SOUTHWEST THRU MUCH OF THE DAY...THEN AS THE BOUNDARY NEARS AROUND
20-22Z SHRA/TSRA WILL BEGIN TO DEVELOP. THEN THE BOUNDARY PASSAGE
IS POISED FOR 00-02Z AND WILL ALLOW WINDS TO VEER TO
NORTHWEST/NORTH.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DEVELOPING.
* MEDIUM CONFIDENCE IN ORD/MDW REMAINING MVFR VSBYS FROM FOG.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR. NORTH-NORTHEAST WINDS.
TUESDAY...VFR. LAKE BREEZE LIKELY.
WEDNESDAY...VFR.
THURSDAY...VFR. NORTHEAST WINDS.
FRIDAY...VFR.
RC
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
353 AM CDT SUN SEP 1 2013
.DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PATCHY MVFR CIGS SLOWLY DISSIPATING...WITH PSBL GROUND FOG
DEVELOPING AFT 08Z.
* PATCHY FOG MAY REDUCE VSBYS TO MVFR TO IFR THRU DAYBREAK.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY AFT 21Z.
BEACHLER
//DISCUSSION...UPDATED 06Z...
VERY MOIST AND CALM AIRMASS OVERHEAD...WITH THINNING STRATUS CLOUD
COVER. THIS ALL POINTS TOWARDS PATCHY FOG DEVELOPING AND REDUCING
VSBYS TO MVFR AND A FEW AREAS OF IFR. WITH THE LACK OF A GRADIENT
OVERNIGHT...WINDS WILL BECOME NEARLY CALM IN A FEW LOCATIONS. THIS
SHOULD AID IN FOG FORMATION ALONG WITH RECENT RAINFALL.
THEN AFT DAYBREAK HEATING SHOULD PROVIDE SOME
INSTABILITY...HOWEVER NOT EXPECTING ANY SHRA/TSRA TO DEVELOP UNTIL
THE FRONTAL BOUNDARY APPROACHES THE REGION FROM THE NORTHWEST. AT
THIS TIME CURRENT GUIDANCE WOULD SUGGEST LIGHT WINDS FROM THE
SOUTHWEST THRU MUCH OF THE DAY...THEN AS THE BOUNDARY NEARS AROUND
20-22Z SHRA/TSRA WILL BEGIN TO DEVELOP. THEN THE BOUNDARY PASSAGE
IS POISED FOR 00-02Z AND WILL ALLOW WINDS TO VEER TO
NORTHWEST/NORTH.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DEVELOPING.
* MEDIUM CONFIDENCE IN ORD/MDW REMAINING MVFR VSBYS FROM FOG.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR. NORTH-NORTHEAST WINDS.
TUESDAY...VFR. LAKE BREEZE LIKELY.
WEDNESDAY...VFR.
THURSDAY...VFR. NORTHEAST WINDS.
FRIDAY...VFR.
RC
&&
.MARINE...
335 PM...A WEAK RIDGE OF HIGH PRESSURE OVER THE NORTHERN LAKES
WILL MOVE EAST TONIGHT AS LOW PRESSURE MOVES ACROSS ONTARIO AND
LAKE SUPERIOR ON SUNDAY. A TRAILING COLD FRONT WILL MOVE ACROSS
LAKE MICHIGAN LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. THE
GRADIENT WILL TIGHTEN BEHIND THIS FRONT AND COMBINED WITH MUCH
COOLER AIR SPREADING ACROSS REGION...NORTHERLY WINDS WILL INCREASE
TO 20 TO 25 KTS WITH SOME HIGHER GUSTS POSSIBLE. THESE WINDS WILL
SLOWLY DIMINISH MONDAY NIGHT INTO TUESDAY AS HIGH PRESSURE BUILDS
ACROSS THE NORTHERN PLAINS MONDAY NIGHT AND ACROSS THE LAKES
REGION TUESDAY AND TUESDAY NIGHT. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
403 AM CDT SUN SEP 1 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 252 AM CDT SUN SEP 1 2013
TODAY...HAVE HANDLED OVERNIGHT FOG DEVELOPMENT WITH A SPECIAL WX
STATEMENT AND HOPE ARRIVING FRONTAL PROCESSES AND HIGH CLOUD COVER
WILL LIMIT ADDITIONAL DEVELOPMENT TO PREVENT A NEED FOR AN ADVISORY.
CURRENT EXTRAPOLATION OF UPSTREAM INCOMING FRONT GENERALLY AGREES
WITH SREF PLACEMENT OF THIS FEATURE CROSSING THE MS RVR AT AROUND
17-18Z OR SO TODAY. MORE IMPORTANTLY WHEN LOOKING AT UPSTREAM
CONVECTIVE TRENDS AND PRESSURE FALLS...IT APPEARS THAT SOME OF THE
MCS WEST OF THE DSM AREA WILL CONTINUE TO PROPAGATE TOWARD/ ALONG
BETTER INSTABILITY AND LLVL MOISTURE GRADIENTS AND MAKE IT ACRS AT
LEAST THE SOUTHWESTERN THIRD OF THE DVN CWA THIS MORNING. NORTHEAST
OF THAT AN ACRS THE REST OF THE DVN CWA...MAY JUST HAVE DECAYING
DEBRIS OR DWINDLING AREAS OF STRATI-FORMING OUT PRECIP. SEVERAL OF
THE HIGH-RES MODELS DRY THE INCOMING PRECIP UP ENOUGH THE BULK OF THE
CWA WILL REMAIN DRY THROUGH 18Z. BUT WITH THE INCOMING FRONT...DEEPER
FORCING UNDER DIFFLUENT NORTHWESTERLIES AND EMBEDDED WAVE ALOFT...
WILL KEEP CHC POPS GOING THROUGH 18Z EXCEPT FOR THE FAR SOUTHWEST
WHERE WILL GO WITH HIGH CHC TO LIKELY POPS FOR NOW AND MAY HAVE TO
UPDATE LATER TO CATEGORICAL. MAY ALSO HAVE TO EXPAND HIGHER POPS
FURTHER TO THE NORTH AND EAST. THUS SOME HOPE FOR RAIN FOR
LOCALIZED DROUGHT AREAS THIS MORNING. CHALLENGING TEMP FCST AND
AFTERNOON INSTABILITY SCENARIO DEPENDING ON WHAT HAPPENS THIS
MORNING AND LINGERING AFFECTS OF CONVECTIVE DEBRIS. THTA-E
ADVECTION FROM THE SOUTH AND PRE-FRONTAL WARM AIR SURGE WOULD
SUGGEST TEMPS ACRS THE SOUTHERN AND SOUTHEASTERN CWA IN THE UPPER
80S TO AROUND 90 DEGREES WITH DPTS AT LEAST IN THE UPPER 60 TO
AROUND 70. THIS WOULD MAKE FOR INSTABILITY AND CAPES CAPABLE OF
SUPPORTING STRONG TO A FEW SVR STORMS THIS AFTERNOON IN CENTRAL IL
AND POSSIBLY EXTENDING WESTWARD BACK INTO THE SOUTHEASTERN AND
EAST CENTRAL DVN FCST AREA. BUT AGAIN...MUCH UNCERTAINTY WITH
CLOUDS/DEBRIS FORM THE MORNING/UPSTREAM CONVECTIVE ACTIVITY
POSSIBLY HAMPERING THE TRUE HEAT UP ABILITY AND INSTABILITY AND
FCST TEMPS MAY BE WELL TOO WARM ESPECIALLY ACRS THE SOUTH/
SOUTHEAST. WILL STILL KEEP HIGHER AFTERNOON POPS FOR THIS
POTENTIAL ACRS THE SOUTHEASTERN THIRD OF THE FCST AREA THIS
AFTERNOON...BUT IF THIS MORNING/S SHOWER/STORM CHANCES INCREASE
AND CONTINUE TO DEVELOP ACRS THESE AREAS THIS MORNING...THAT MAY
BE IT FOR THE LOCAL AREA AND THE AFTERNOON RE-DEVELOPMENT WILL
OCCUR OFF TO THE EAST OF THE DVN CWA. OTHERWISE POST-FRONTAL
CLEARING PROCESSES THIS AFTERNOON AND EVENING ACRS THE REST OF THE
DVN CWA.
TONIGHT...SEASONABLY STRONG CANADIAN SFC ANTICYCLONE/HIGH STILL ON
TRACK TO DUMP DOWN THE NORTHERN PLAINS AND UPPER MS RVR VALLEY WITH
ASSOCIATED AIRMASS RELIEF FROM THE NORTH. WILL BANK ON INHERENT
NORTHERLY SFC FLOW AND LOWER SFC DPT INFLUX TO PREVENT MORE FOG
DEVELOPMENT TONIGHT DESPITE CLEAR OUT AND SFC TEMP COOL DOWN. LOW
TEMPS IN THE 50S TO LOWER 60S...SOME MID 50S POSSIBLE NORTH OF I80.
..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 252 AM CDT SUN SEP 1 2013
TURNING COOLER WITH CONTINUED DRY CONDITIONS THROUGH THE WEEK.
OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH NORMAL POOR
HANDLING OF BL MOISTURE AND ALSO SOME LOW LEVEL THERMAL FIELDS
DISCREPANCIES. VERIFICATION AND RUN TO RUN CONTINUITY SUGGEST A
50/50 MIX OF THE UKMET/GEM-RH WITH GFS. HI-RES ECMWF HAS SOME
CONTINUITY AND BL THERMAL FEEDBACK ISSUES. MINOR SENSIBLE WEATHER
ISSUES SINCE DRY. IF WASN/T FOR THE FACT WE NEED RAIN...THE
WEATHER THIS WEEK WILL BE ENJOYABLE.
MONDAY AND TUESDAY...COMFORTABLE AND REFRESHING EARLY FALL WEATHER
AS CANADIAN HIGH PRESSURE MOVES ACROSS THE REGION. HIGHS MIDDLE 70S
NORTH TO LOWER 80S FAR SOUTH. MINS MAY STILL NEED TRIMMING A DEGREE
OR TWO WITH LIGHT WINDS...CLEAR SKIES AND DRY GROUND FROM GOOD
RADIATIONAL COOLING CONDITIONS.
WEDNESDAY THROUGH SATURDAY...NW UPPER FLOW CONTINUES WITH WEAK HIGH
PRESSURE TO CONTINUE. LATER SHIFTS MAY BE ABLE TO GO COMPLETELY
DRY WEDNESDAY NIGHT IN FAR NW SECTIONS. HIGHS SHOULD RISE BACK
WELL INTO THE 80S WITH LOWS UPPER 50S TO MIDDLE 60S. OVERALL...SLIGHTLY
ABOVE NORMAL CONDITIONS WITH A SLIGHTLY HUMID BY NEXT WEEKEND BUT
HEAT INDICES STAYING AT OR BELOW 90 DEGREES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1150 PM CDT SAT AUG 31 2013
MAIN CHALLENGE REMAINS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT
INTO SUNDAY.
LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE FAVORABLE FOR DEVELOPMENT
OF FOG OVERNIGHT WITH VISIBILITIES POTENTIALLY FLUCTUATING QUITE
A BIT SHALLOW LOW LEVEL INVERSION. THE RAP AND HRRR MODELS DO
INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS ESPECIALLY EAST OF THE
MISSISSIPPI RIVER. INCREASING MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN
APPROACHING COLD FRONT COULD HAVE IMPACT ON MAGNITUDE/EXTENT OF FOG
AND POSSIBLY EVEN SOME LOW CLOUDS...THUS WILL BE A CHALLENGING SET
OF TAFS. HAVE HIT THE FOG THE HARDEST WITH LIFR CONDITIONS AT KDBQ
WHERE RECENT RAINS PAST 24+ HRS. ELSEWHERE...HAVE IFR TO MVFR
VSBYS. COULD SEE SOME STRATUS WITH CIGS BLO 1KFT AGL AND HAVE
HINTED AT THIS STILL AT ALL SITES. ANTICIPATE SCATTERED SHOWERS
AND STORMS TO ACCOMPANY THE COLD FRONT...WHICH IS SLATED TO PASS
THROUGH THE TERMINALS FROM 13Z-19Z. CONDITIONS TO IMPROVE TO VFR
AFTER PASSAGE OF FRONT WITH WINDS INCREASING FROM NW AT 10-15 KTS
WITH GUSTS AROUND 18-22+ KTS DURING THE AFTERNOON...THEN DIMINISH
BLO 10 KTS BY 00Z.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SHORT TERM...12
LONG TERM...NICHOLS
AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1200 AM CDT SUN SEP 1 2013
.SYNOPSIS...
ISSUED AT 223 PM CDT SAT AUG 31 2013
WEAK LOW PRESSURE OVER WEST CENTRAL IL EARLY THIS AFTERNOON. HOT
AND HUMID CONDITIONS WERE FOUND NEAR THE LOW WITH LOW TO MID 90
TEMPERATURES AND DEW POINTS IN THE LOW 70. IN THE LOW EASTERLY
FLOW NORTH OF THE LOW TEMPERATURES WERE COOLER BUT DEWPOINTS WERE
STILL AROUND 70. A COLD FRONT OVER THE NORTHERN PLAINS WAS THE
LEADING EDGE OF COOL DRY AIR MASS. EARLY AFTERNOON TEMPERATURES
OVER WESTERN NORTH DAKOTA WERE IN THE 70S WITH DEW POINTS IN THE 50S.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 223 PM CDT SAT AUG 31 2013
THIS FORECAST PERIOD WILL SEE A TRANSITION TO A MUCH MORE
COMFORTABLE AIRMASS BY LATE SUNDAY AFTERNOON AS THE NORTHERN
PLAINS FRONT MOVES THROUGH THE REGION. RAIN CHANCES WILL ACCOMPANY
THE FRONT BUT AT THIS TIME...COVERAGE LOOKS SCATTERED AT BEST.
FOR TONIGHT THE AREA OF LOW PRESSURE OVER WEST CENTRAL IL WILL BE
THE FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND
THIS EVENING. IT APPEARS THAT THE DEVELOPMENT WILL TAKE PLACE JUST
EAST OF THE FORECAST AREA BASED CURRENT SATELLITE IMAGERY. HOWEVER
WITH AN UPSTREAM VORT...OVER NORTHWEST IL... EXPECT TO MOVE
THROUGH NORTHERN MO AND VERY UNSTABLE AIR STILL OVER THE SOUTHERN
COUNTIES...A LOW POP WAS MAINTAINED FOR THE EARLY EVENING HOURS.
WINDS WILL REMAIN LIGHT OVERNIGHT AND WITH THE HIGH DEWPOINTS
STILL IN PLACE WE COULD SEE SOME PATCHY FOG LATE ESPECIALLY EAST
OF THE MISSISSIPPI RIVER.
THE NORTHERN PLAINS COLD FRONT IS EXPECTED TO REACH THE NORTHWEST
CWA BY EARLY SUNDAY MORNING AND WILL EXIT THE EASTERN COUNTIES
DURING THE EARLY AFTERNOON. THE BETTER FORCING WITH THIS SYSTEM
WILL STAY OVER THE GREAT LAKES...BUT THE MODELS ARE SHOWING SOME
UPPER DIFFLUENCE AHEAD OF THE S/W MOVING OVER THE AREA WITH THE
COLD FRONT. THERE WILL ALSO BE OF NARROW THETAE RIDGE WITH THE
BOUNDARY AND STEEPENING MID LEVEL LAPSE RATES WHICH SHOULD BE
ENOUGH FOR SCATTERED STORMS AS THE FRONT MOVES THROUGH. COVERAGE
OF THE STORMS SHOULD INCREASE AS THE FRONT MOVES ACROSS THE
MISSISSIPPI RIVER WHERE THE AIRMASS HAS A CHANCE TO DESTABILIZE
DURING THE MORNING. THE THREAT OF SEVERE STORMS WILL BE LOW ON
SUNDAY DUE TO THE EARLY DAY FROPA AND WEAK DEEP LAYER SHEAR.
THE HIGH LOW LEVEL MOISTURE WILL KEEP MIN TEMPS IN THE MID 60S TO
AROUND 70 TONIGHT. HIGHS SUNDAY WILL STILL BE ON THE WARM SIDE
TOPPING OUT AROUND 90 SOUTH TO THE MID 80S IN THE NORTH...BUT WE
SHOULD SEE DEW POINTS COME DOWN A LITTLE...ESPECIALLY WEST OF THE
MISSISSIPPI RIVER.
DLF
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 223 PM CDT
SAT AUG 31 2013
ANY LINGERING RAIN ACROSS THE SOUTHEAST THIRD OF THE CWFA SUNDAY
EVENING WILL END SHORTLY AFTER SUNSET.
HIGH PRESSURE WILL MOVE ACROSS THE MIDWEST SUNDAY NIGHT THROUGH
TUESDAY RESULTING IN DRY BUT PLEASANT CONDITIONS. TEMPERATURES
SHOULD AVERAGE CLOSE TO NORMAL.
TUESDAY NIGHT ON...
NORTHWEST FLOW ALOFT WILL PERSIST THROUGH NEXT WEEKEND. SEVERAL
ADDITIONAL COLD FRONTS WILL MOVE THROUGH THE AREA BUT MOISTURE IS
EXPECTED TO BE LIMITED WITH EACH FRONTAL PASSAGE. WHILE NOT
CERTAIN...THE PROBABILITY IS MODERATE TO HIGH THAT MOST OF THE AREA
WILL REMAIN DRY.
THE MODEL CONSENSUS FOR TUESDAY NIGHT THROUGH SATURDAY IS FOR DRY
CONDITIONS THROUGH THE PERIOD WITH TEMPERATURES AVERAGING AT OR
SOMEWHAT ABOVE NORMAL. ..08..
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1150 PM CDT SAT AUG 31 2013
MAIN CHALLENGE REMAINS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT
INTO SUNDAY.
LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE FAVORABLE FOR DEVELOPMENT
OF FOG OVERNIGHT WITH VISIBILITIES POTENTIALLY FLUCTUATING QUITE
A BIT SHALLOW LOW LEVEL INVERSION. THE RAP AND HRRR MODELS DO
INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS ESPECIALLY EAST OF THE
MISSISSIPPI RIVER. INCREASING MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN
APPROACHING COLD FRONT COULD HAVE IMPACT ON MAGNITUDE/EXTENT OF FOG
AND POSSIBLY EVEN SOME LOW CLOUDS...THUS WILL BE A CHALLENGING SET
OF TAFS. HAVE HIT THE FOG THE HARDEST WITH LIFR CONDITIONS AT KDBQ
WHERE RECENT RAINS PAST 24+ HRS. ELSEWHERE...HAVE IFR TO MVFR
VSBYS. COULD SEE SOME STRATUS WITH CIGS BLO 1KFT AGL AND HAVE
HINTED AT THIS STILL AT ALL SITES. ANTICIPATE SCATTERED SHOWERS
AND STORMS TO ACCOMPANY THE COLD FRONT...WHICH IS SLATED TO PASS
THROUGH THE TERMINALS FROM 13Z-19Z. CONDITIONS TO IMPROVE TO VFR
AFTER PASSAGE OF FRONT WITH WINDS INCREASING FROM NW AT 10-15 KTS
WITH GUSTS AROUND 18-22+ KTS DURING THE AFTERNOON...THEN DIMINISH
BLO 10 KTS BY 00Z.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...DLF
SHORT TERM...DLF
LONG TERM...08
AVIATION...05
AREA FORECAST DISCUSSION
NWS GOODLAND KS
218 AM MDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 150 PM MDT SAT AUG 31 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE
EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW
BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA.
A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE
PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL
FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN
NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS
MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE
CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER
TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER
EASTERN WYOMING.
AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL
HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE
FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE
INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS
REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY
OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH
THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY
MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL
LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA
THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE
AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION
FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE
ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS
SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF
OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN
ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND
SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM
ACTIVITY. HOWEVER...I`M NOT SURE ABOUT HOW WIDESPREAD THAT THREAT
WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT
RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL.
REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE
FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD
ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER
THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS
WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE
MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO
BE FOR LABOR DAY WEEKEND.
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 214 AM MDT SUN SEP 1 2013
UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR
THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM TEMPERATURES AND
DRY CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA
WILL BE CENTERED OVER COLORADO FOR WEDNESDAY AS RIDGE BECOMES MORE
AMPLIFIED INTO THE NORTHERN HIGH PLAINS FOR THURSDAY AND FRIDAY. THE
RIDGE WILL DEAMPLIFY AND RETROGRADE WESTWARD INTO THE DESERT
SOUTHWEST REGION NEXT WEEKEND AS AN UPPER LEVEL LOW MOVES OUT OF
ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE TROUGHS LOOK TO
DEVELOP LATE INTO NEXT WEEKEND AND MOVE INTO THE HIGH PLAINS WITH
THE MAIN ASSOCIATED UPPER LEVEL TROUGH...WHICH COULD PROVIDE
ENOUGH LIFT FOR THUNDERSTORM DEVELOPMENT FOR SUNDAY.
STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE
EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE
LOWER 90S. LOW TEMPERATURES FOR THE EXTENDED PERIOD WILL BE IN THE
UPPER 60S FOR MOST LOCATIONS. MODEL SOUNDINGS SHOW STABLE UPPER AIR
PROFILE THROUGH THE PERIOD...WITH MARGINAL INSTABILITY PARAMETERS AT
BEST AND A GENERAL LACK OF MOISTURE IN THE UPPER AIR PROFILES.
MODEL FORECASTS DIFFER ON PRECIPITATION CHANCES FOR NEXT
SUNDAY...BUT ENCROACHING FRONTAL CLIPPER SYSTEM WILL LIKELY
PROVIDE SOME CHANCES FOR STORM DEVELOPMENT. BESIDES SLIGHT
PRECIPITATION CHANCES NEXT WEEKEND...THE MAIN WEATHER PATTERN FOR
THE EXTENDED FORECAST PERIOD CONTINUES TO BE WARM TEMPERATURES AND
MAINLY DRY CONDITIONS FOR THE TRI STATE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1100 PM MDT SAT AUG 31 2013
FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. POST FRONTAL NORTHEAST
WINDS EXPECTED TO GUST CLOSE TO 25KTS OR SO AFTER 13Z-15Z THROUGH
20Z BEFORE DECREASING TOWARD 10KTS FROM THE EAST THEN LIGHT
EAST/SOUTHEAST 5KTS OR SO BY 02Z AS SFC HIGH MOVES IN. LATEST
MODELS HINTING AT SOME IFR CIGS FOR KGLD IN THE 12Z-16Z TIME FRAME.
HAVE INTRODUCED A SCATTERED GROUP AROUND 500FT TO ACCOUNT FOR THIS
AND WILL ALLOW NEXT SHIFT TO RE-EVALUATE POTENTIAL NEED FOR
PREVAILING IFR/VLIFR CONDITIONS. NO PRECIPITATION EXPECTED.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...MK
AVIATION...99
AREA FORECAST DISCUSSION
NWS WICHITA KS
242 AM CDT SUN SEP 1 2013
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION
OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS
EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS
EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN
NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM
PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR
TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH
CENTRAL/SOUTHEAST KS.
THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT
MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL
MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A
RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE
FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD
OF THE FRONT.
COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO
TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY
NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS.
JMC
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL
ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO
THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES
TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN
RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS
VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH.
THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME.
JMC
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1129 PM CDT SAT AUG 31 2013
A FRONTAL BOUNDARY WILL SINK SOUTHWARD INTO CENTRAL KANSAS TOWARDS
DAYBREAK...THEN PUSH SLOWLY SOUTHWARD INTO SOUTHERN KANSAS BY
SUNDAY AFTERNOON. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG THE
FRONTAL BOUNDARY.
JAKUB
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 94 65 88 64 / 30 10 0 0
HUTCHINSON 92 64 87 63 / 40 10 0 0
NEWTON 92 64 86 62 / 30 10 0 0
ELDORADO 94 65 86 62 / 30 10 0 0
WINFIELD-KWLD 97 66 89 64 / 20 10 0 0
RUSSELL 89 60 87 62 / 40 0 0 0
GREAT BEND 90 63 88 62 / 40 0 0 0
SALINA 91 62 87 62 / 30 0 0 0
MCPHERSON 92 63 87 62 / 30 0 0 0
COFFEYVILLE 97 67 88 64 / 20 10 0 0
CHANUTE 94 65 86 63 / 30 10 0 0
IOLA 94 64 86 62 / 30 10 0 0
PARSONS-KPPF 96 66 87 63 / 20 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1243 AM CDT Sun Sep 1 2013
...Updated for Aviation...
.SYNOPSIS...
ISSUED AT 300 PM CDT SAT AUG 31 2013
An upper level center of high pressure was located across New Mexico
and the extreme southern High Plains today, as the upper westerly
jet was positioned zonally across the northern Rockies and Northern
Plains. A shortwave was in place across southern Canada, on the
north side of the jet. A hot airmass still encompassed the central
part of the country. 850 mb level temperatures in excess of 20
degrees C extended from the entire great plains region eastward to
the the Ohio valley. at the surface...a cold front was moving
southward across western South Dakota and extreme western Nebraska.
Another weak stationary front was positioned from the Texas
panhandle northeast into south central Kansas. Easterly surface
winds became more southerly across western Kansas as surface low
pressure slowly filled across the Oklahoma panhandle and temperatures
warmed into the 90`s by early afternoon.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 300 PM CDT SAT AUG 31 2013
The immediate concern will revolve around convective chances which
are not great, but non-zero as well. The best location appears along
the diffuse boundary across south central Kansas. The HRRR runs have
somewhat approximated isolated convection occurring by about 23 utc.
A lack of upper winds and lack of shear suggest little chances at
all of severe thunderstorms, and storms should have short life
cycles. A better chance for showers and thunderstorms exists well
into the overnight as the Northern Plains cold front enters the
area. Probabilities increase from north to south around 6z and
after.
Very warm temperatures will continue into this evening. The NAM
models surface temperatures sill around 100 degrees this evening
near the Oklahoma line and low 80s persisting after midnight.
Morning lows will likely be warm across all of southwest Kansas,
with a few locations having lows in the upper 70s, however rain
cooled air form a few vigorous storm cluster might augment the
temperatures locally.
Thunderstorms chances are again in the forecast during the afternoon
Sunday as redevelopment is likely along the frontal boundary,
wherever it decides to stall out.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 235 PM CDT SAT AUG 31 2013
A cold front will move across Kansas tonight as a vigorous upper
level trough moves from southeast Saskatchewan to the Great Lakes,
and a brief period of near climatological temperatures should extend
into Monday. However, the anticyclone centered over the Rockies will
build back into the Central Plains early next week, and several days
of warm, quiet weather will follow. Unless rainfall tonight is more
widespread than appears likely, vegetation will become increasingly
drought stressed next week. Reduced evapotranspiration may allow
more solar radiation to covert into sensible heat, and temperatures
in the mid to upper 90s can be expected on most days.
Tropical thunderstorm activity has been strongly suppressed from
about 130E to the dateline, although an area of enhanced
thunderstorms has been persistent in the Indian Ocean southwest of
India. Most of the numerical models suggest that a coherent tropical
cluster that projects onto a Madden Julian Oscillation (MJO) will
amplify in Phase 1 of the Wheeler-Hendon Phase Space Diagram early
in September and propagate slowly east before losing identity in the
Indian Ocean. There is little correlation between the MJO and
sensible weather in the central plains at this time of the year, but
there may be in increased chance for tropical waves to come off
Africa into the eastern Atlantic next week.
Global relative angular momentum remains below climatology, but
mountain torque has increased in recent days. The atmosphere will be
best represented by Phase 4-5 of the Weickmann-Berry Global Wind
Oscillation, which correlates with anticyclonic flow in the western
and central United States. The deterministic model solutions all
favor ridging from the central Rockies across the central and
southern United States through the first ten days of September with
only minor synoptic scale differences. The 12Z GFS has trended
toward the 00Z ECMWF in handling the closed cyclone near 140W that
wallows into the northern plains 9-10 September and largely was
followed for grid adjustments, although confidence in behavior of
this cyclone is low.
Upslope flow into the foothills in eastern Colorado Sunday evening
should favor thunderstorm development, but the upper level flow will
be light and largely meridional over western Kansas. Most of the
thunderstorms will remain west of the Colorado border, but there is
a nonzero chance that a thunderstorm could reach far southwest
Kansas before midnight Sunday night. Cool high pressure with light
winds and low level dewpoints in the 50s will allow for strong
radiational cooling, and lows will drop into the upper 50s in most
areas Tuesday morning. Another minor trough dropping into the mean
long wave trough near 80W will support a weak boundary that may
survive into northern Kansas Wednesday night, but limited
instability and weak flow aloft do not favor an organized
thunderstorm event. As the upper level trough near 140W moves across
the Northern Plains around 9 September, a cold front will move into
Kansas and provide another opportunity for thunderstorm development
and a return to more seasonal temperatures.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1235 AM CDT SUN SEP 1 2013
Scattered thunderstorms at KDDC and KGCK with west to northwest
winds of 25-38kt will continue through 08-10z this morning, then
winds shifting to the northeast at 10-15kt after 15z. Vfr
conditions will prevail after the thunderstorms. KHYS will likely
stay out of the thunderstorm activity.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 60 89 61 91 / 10 0 0 0
GCK 58 90 61 91 / 10 0 0 0
EHA 64 91 65 91 / 10 10 10 0
LBL 60 92 62 92 / 10 0 0 0
HYS 57 90 59 91 / 0 0 0 0
P28 64 90 62 91 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Russell
SHORT TERM...Russell
LONG TERM...Ruthi
AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1102 PM MDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 150 PM MDT SAT AUG 31 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE
EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW
BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA.
A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE
PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL
FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN
NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS
MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE
CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER
TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER
EASTERN WYOMING.
AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL
HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE
FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE
INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS
REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY
OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH
THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY
MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL
LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA
THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE
AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION
FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE
ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS
SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF
OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN
ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND
SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM
ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT
WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT
RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL.
REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE
FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD
ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER
THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS
WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE
MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO
BE FOR LABOR DAY WEEKEND.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 204 PM MDT SAT AUG 31 2013
THE UPPER RIDGE IS IN PLACE AGAIN OVER THE ROCKIES AND HIGH PLAINS
FROM SUNDAY NIGHT THROUGH ALL OF NEXT WEEK. DIFFERENCES BEGIN TO
SHOW UP IN MODEL PROGRESSIONS OF THE UPPER LOW CENTER RIDING UP
OVER THE RIDGE IN THE PACIFIC NORTHWEST AND THE OVERALL FLATTENING
OF THE RIDGE IN THE FRIDAY NIGHT THROUGH SATURDAY TIME PERIOD.
SURFACE COOLER HIGH PRESSURE AREA STAYS MOSTLY OVER THE CENTRAL
PLAINS AND CENTRAL HIGH PLAINS SUNDAY NIGHT AND MONDAY BEFORE
PUSHING FURTHER EAST WITH A DEEPENING LEE TROUGH THAT PERSISTS IN
THE VICINITY OF THE EASTERN COLORADO BORDER. WITH SOUTHERLY FLOW
ACROSS THE FORECAST AREA...EXPECT MORE DRY AND WARM CONDITIONS
THROUGH THE UPCOMING WORK WEEK AND NEXT WEEKEND WITH HIGHS IN THE
90S AND LOWS IN THE 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1100 PM MDT SAT AUG 31 2013
FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. POST FRONTAL NORTHEAST
WINDS EXPECTED TO GUST CLOSE TO 25KTS OR SO AFTER 13Z-15Z THROUGH
20Z BEFORE DECREASING TOWARD 10KTS FROM THE EAST THEN LIGHT
EAST/SOUTHEAST 5KTS OR SO BY 02Z AS SFC HIGH MOVES IN. LATEST
MODELS HINTING AT SOME IFR CIGS FOR KGLD IN THE 12Z-16Z TIMEFRAME.
HAVE INTRODUCED A SCATTERED GROUP AROUND 500FT TO ACCOUNT FOR THIS
AND WILL ALLOW NEXT SHIFT TO RE-EVALUATE POTENTIAL NEED FOR
PREVAILING IFR/VLIFR CONDITIONS. NO PRECIPITATION EXPECTED.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
345 AM EDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 240 AM EDT SUN SEP 1 2013
THE BULK OF THE CONVECTION HAS DIED OUT OVER EAST KENTUCKY...THOUGH
ADDITIONAL STORMS LOOK TO BE TRACKING INTO THE CUMBERLAND VALLEY
OVER THE NEXT SEVERAL HOURS. RAN A QUICK UPDATE MAINLY TO THE POP/WX
AND SKY GRIDS THROUGH DAWN TO REFLECT THESE CONVECTIVE...AND FOG...
TRENDS. ALSO FINE TUNED THE T AND TD GRIDS THROUGH 12Z BASED ON THE
CURRENT OBS. THE GRID UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS.
UPDATE ISSUED AT 1043 PM EDT SAT AUG 31 2013
MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS
EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A
FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST
CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE
SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY
THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND
THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE
POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR
THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN
STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT
FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO
DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS
PERIOD.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 AM EDT SUN SEP 1 2013
A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START
OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN.
AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A
COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING
OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN
THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY
TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE
DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS
WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIRMASS...WITH WINDS
AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY
REACH NEAR 80 TUESDAY.
THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST
THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING
TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIRMASS IN
PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE
50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END
OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL
SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT
THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE
CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER
GREAT LAKES SATURDAY. ACCORDING THE ECWMF...WARM AIR PULLING IN
AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO
THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL
CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT
COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL
SOMEWHAT UNKNOWN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 300 AM EDT SUN SEP 1 2013
THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH MOST OF THE AREA...BUT
AN ADDITIONAL ROUND OF STORMS MAY AFFECT SME AND LOZ FROM NOW UNTIL
12Z. OUTSIDE OF THE CUMBERLAND VALLEY...PATCHY FOG WILL BE THE MAIN
AVN CONCERN INTO DAWN. DO EXPECT ADDITIONAL STORMS TO DEVELOP AND
AFFECT THE ENTIRE AREA LATER ON SUNDAY WITH A PEAK OF COVERAGE
ANTICIPATED DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. HAVE
REFLECTED THIS IN THE TAFS VIA A PREVAILING SHRA AND VCTS DURING THIS
TIME. LATE ON...BACKED THESE OFF TO JUST VCSH MENTIONS AFTER 02Z AS
INSTABILITY WANES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND
VARIABLE...OUTSIDE OF ANY STORMS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...JMW
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
300 AM EDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 240 AM EDT SUN SEP 1 2013
THE BULK OF THE CONVECTION HAS DIED OUT OVER EAST KENTUCKY...THOUGH
ADDITIONAL STORMS LOOK TO BE TRACKING INTO THE CUMBERLAND VALLEY
OVER THE NEXT SEVERAL HOURS. RAN A QUICK UPDATE MAINLY TO THE POP/WX
AND SKY GRIDS THROUGH DAWN TO REFLECT THESE CONVECTIVE...AND FOG...
TRENDS. ALSO FINE TUNED THE T AND TD GRIDS THROUGH 12Z BASED ON THE
CURRENT OBS. THE GRID UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS.
UPDATE ISSUED AT 1043 PM EDT SAT AUG 31 2013
MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS
EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A
FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST
CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE
SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY
THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND
THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE
POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR
THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN
STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT
FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO
DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS
PERIOD.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 300 AM EDT SUN SEP 1 2013
THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH MOST OF THE AREA...BUT
AN ADDITIONAL ROUND OF STORMS MAY AFFECT SME AND LOZ FROM NOW UNTIL
12Z. OUTSIDE OF THE CUMBERLAND VALLEY...PATCHY FOG WILL BE THE MAIN
AVN CONCERN INTO DAWN. DO EXPECT ADDITIONAL STORMS TO DEVELOP AND
AFFECT THE ENTIRE AREA LATER ON SUNDAY WITH A PEAK OF COVERAGE
ANTICIPATED DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. HAVE
REFLECTED THIS IN THE TAFS VIA A PREVAILING SHRA AND VCTS DURING THIS
TIME. LATE ON...BACKED THESE OFF TO JUST VCSH MENTIONS AFTER 02Z AS
INSTABILITY WANES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND
VARIABLE...OUTSIDE OF ANY STORMS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
359 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER LAKE SUPERIOR WILL CONTINUE TO DEVELOP
AND MOVE EAST INTO NORTHERN QUEBEC THROUGH EARLY THIS WEEK. A
COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE THROUGH THE MID-
ATLANTIC MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE BUILDS IN FROM
THE NORTHWEST MID TO LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DEBRIS CLOUDS LEFT OVER FROM YDA`S CONVECTION HAS LIMITED EXTENT
OF FOG FORMATION ERY THIS MRNG. SOME PATCHY FOG WILL STILL DEVELOP
THRU DAYBREAK PRIMARILY WITHIN THE SHELTERED VLYS IN CENTRAL
VA...WHERE THE GROUND IS WET FROM YDA`S STORMS.
HIPRES WILL REMAIN PARKED OVER THE WRN ATLANTIC TDA. WITH PERSISTENT
SLY RETURN FLOW OVER THE ERN SEABOARD...THE AIRMASS WILL BE SIMILAR
TO YDA...WARM AND HUMID /DESPITE THE CALENDAR CHANGING FROM
METEOROLOGICAL SUMMER TO FALL/. MAX TEMPS ARE FCST IN MID TO UPPER
80S ALONG AND WEST OF THE BLUE RIDGE AND UPPER 80S TO LOWER 90S
FARTHER EAST. ONE MID-LVL SHORTWAVE TROUGH EXITS THE MID-ATLANTIC
REGION ERY THIS MRNG AS ANOTHER ONE APPROACHES FROM THE OH VLY. THE
REMNANTS OF THIS UPSTREAM MCS WILL PROGRESS EWD THRU THE NRN
MID-ATLANTIC STATES THIS AFTN/EVE. THE CWA WILL HAVE FILTERED
SUNSHINE BEFOREHAND...PROVIDING AN OPPORTUNITY FOR THE ATMOSPHERE TO
DESTABILIZE. SIMILAR TO YDA...SCT SHOWERS AND STORMS SHOULD DEVELOP
OVER THE MTS THIS AFTN AS MODEST LIFT FROM THE SHORTWAVE TROUGH
REACHES THE WRN CWA. WITH THE MID-LVL SUBSIDENCE INVERSION WEAKER
THAN YDA...DEEPER CONVECTION WILL HAVE A BETTER CHANCE TO MAKE IT
EAST OF THE MTS. THE BEST CHANCE FOR SHOWERS AND STORMS APPEAR TO BE
LATE THIS AFTN AND EVE WHEN THE SHORTWAVE TROUGH MOVES THRU. LIMITED
POPS TO CHANCE ACROSS THE ENTIRE CWA THOUGH AS CONVECTION MAY HAVE
DIFFICULTY ORGANIZING DUE TO WEAK SHEAR PROFILES AND LIFT FROM THE
TROUGH. FCST PARAMETERS FROM THE LATEST RAP INDICATE ABOUT 1500-2000
J/KG OF SBCAPE THIS AFTN. CANNOT RULE OUT A COUPLE OF PULSE SEVERE
STORMS ESPECIALLY IN THE MTS GIVEN THE THERMODYNAMIC PROFILES.
ONGOING CONVECTION WILL DIMINISH LATE THIS EVE WITH THE LOSS OF
HEATING AND AS THE SHORTWAVE TROUGH LIFTS NEWD TNGT. DRY SLOT MOVES
IN FROM THE WEST TNGT WHILE THE LLVL FLOW VEERS OUT OF THE WEST.
THIS COULD ALLOW FOR BREAKS IN THE CLOUD COVER AND FOR FOG TO
DEVELOP LATE TNGT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
LABOR DAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN APPROACHING
COLD FRONT FROM THE WEST. A PREFRONTAL TROUGH WILL DEVELOP IN THE
LEE OF THE APPALACHIANS WHICH SHOULD PROVIDE A FOCUS FOR
ISOLATED/SCATTERED AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT. IT
WILL BE A HOT DAY WITH MAX TEMPS IN THE LOW 90S. NAM AND GFS HAVE
SBCAPE AROUND 2500 J/KG WITH BULK SHEAR UNDER 30 KT.
MONDAY NIGHT...LINES OF CONVECTION SHOULD DEVELOP AHEAD OF THE FRONT
AND PUSH EAST THROUGH THE AREA MONDAY EVENING/THROUGH MIDNIGHT.
INCREASED LIKELY POP COVERAGE TO ACROSS THE BALT-WASH METRO FOR THE
EVENING HOURS. THIS IS JUST ABOVE MOST GUIDANCE WHICH IS AROUND 50
POP. WITH AMPLE AVAILABLE ENERGY AND A STRAIGHT-LINE HODOGRAPH...
EXPECT ORGANIZED ACTIVITY. SEVERE THREAT OF LARGE HAIL AND DAMAGING
WIND. SPEAKING OF HAIL...THERE HAVE ONLY BEEN FOUR 1 INCH HAIL
REPORTS SINCE JULY 4. WITH TALL AND FAT CAPE DEPICTED BY THE NAM/GFS
SOUNDINGS...THIS HAIL DEARTH MAY END SOON. FRONT DRIFTS EAST THROUGH
THE NIGHT...MIN TEMPS AROUND 60F IN THE ALLEGHENY HIGHLANDS...CLOSER
TO 70F EAST OF THE BLUE RIDGE PER MAV/MET/SREF BLEND.
TUESDAY...FRONT IS SLOW TO CLEAR THE AREA...MAY STALL OVER SRN MD
CONTINUING A THUNDERSTORM THREAT DOWN THERE. OTW...NRN CONUS (NOT
QUITE CANADIAN...AND THUS NOT AS COOL) HIGH PRESSURE BUILDS IN FROM
THE NW...WITH SUNNY CONDITIONS ON TAP IN WRN PARTS OF THE CWA. MAX
TEMPS GENERALLY 80S AT LOW ELEVATIONS...MID 80S I-95 AND EAST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
DRY CONDITIONS AS HIGH PRESSURE DOMINATES THROUGH FRIDAY. WEAK SFC
TROUGH DROPS SOUTH INTO THE CWA WEDNESDAY NIGHT...PUSHING SOUTH
THURSDAY. PROBABLY JUST SOME MID LEVEL CLOUDS ASSOCIATED WITH THIS
DISTURBANCE. MAX TEMPS CLOSE TO NORMAL...LOW 80S WED-FRI.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
LGT SLY WINDS AND MID TO HI CLOUDS HAVE LIMITED THE COVERAGE OF FOG
ERY THIS MRNG. AS OF 0730Z...ALL TERMINALS ARE VFR. CHO HAS THE BEST
OPPORTUNITY FOR A BRIEF PERIOD OF FOG TOWARD SUNRISE AS THE SOIL IS
SATURATED FROM YDA`S STORMS.
VFR CONDITIONS FOR MUCH OF TDA. SCT SHOWERS AND STORMS ARE EXPECTED
TO INITIALLY DEVELOP OVER THE MTS THIS AFTN AND MOVE EWD TOWARD THE
TERMINALS APPROX BETWEEN 20Z-01Z. TEMPORARY FLGT RESTRICTIONS
POSSIBLE WITH THESE STORMS. PATCHY FOG POSSIBLE AGAIN LATE
TNGT...ESPECIALLY AT THE FOG-PRONE LOCATIONS AT CHO AND MRB.
THUNDERSTORMS INCREASE MONDAY AFTERNOON/CONTINUE THROUGH THE NIGHT
AS A COLD FRONT DRIFTS EAST ACROSS THE TERMINALS. SLY FLOW AROUND 10
KT...THOUGH DAMAGING WINDS ARE POSSIBLE IN THUNDERSTORMS. HIGH
PRESSURE THEN BUILDS TUESDAY AND DOMINATES REST OF THE WORK WEEK
WITH VFR CONDS OUTSIDE OF MORNING FOG.
&&
.MARINE...
SLY CHANNELING HAS ENHANCED WINDS TO NEAR SCA THRESHOLD IN THE
TANGIER SOUND ERY THIS MRNG. HAVE AN MARINE WX STATEMENT FOR THIS
ZONE PUT OPTED TO NOT ISSUE A SCA AS THE PRESSURE GRADIENT WILL
CONTINUE TO WEAKEN OVER THE NEXT COUPLE OF HRS. OTHERWISE...SLY
WINDS BETWEEN 10-15 KT WILL CONTINUE TDA AND TNGT. SCT STORMS
EXPECTED LATE IN THE DAY. LOCALLY STRONG WINDS WITH THESE STORMS
COULD BECOME HAZARDOUS TO MARINERS AND HOLIDAY BOATERS.
10-15 KT SLY FLOW AHEAD OF A COLD FRONT ACROSS THE WATERS MONDAY.
SPECIAL MARINE WARNINGS POSSIBLE FROM THUNDERSTORMS LATE MONDAY
AFTERNOON THROUGH THE NIGHT. FLOW BECOMES NWLY BY TUESDAY
EVENING...SOME CHANNELING GUSTS MAY APPROACH 18 KT. VARIABLE FLOW
AND HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BAJ/JRK
NEAR TERM...JRK
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/JRK
MARINE...BAJ/JRK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
152 AM EDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE SHRA/TS CHCS ASSOCIATED
WITH SHRTWV NOW NEAR LK WINNIPEG.
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER
THE NRN CONUS ON THE NRN FLANK OF SPRAWLING HI PRES CENTERED OVER
THE SW CONUS. STUBBORN LO CLDS OVER THE SCENTRAL COUNTIES ARE
FINALLY BURNING OFF. THERE IS A SHRTWV TRACKING THRU ONTARIO...BUT
THIS DISTURBANCE IS PASSING FAR ENUF TO THE N THAT THE COMMA TAIL
-SHRA ARE JUST BRUSHING NEAR ISLE ROYALE. WEAK RDG OF HI PRES OVER
THE GRT LKS/SHARP SUBSIDENCE INVRN SHOWN ON LOCAL 12Z RAOBS IS
BRINGING QUIET WX TO THE CWA FOR NOW. A STRONGER SHRTWV IS PRESENT
ALONG THE NDAKOTA/CNDN BORDER AND MOVING QUICKLY TO THE ESE. WHERE
THE SHARP DPVA/DEEP LYR QVECTOR CNVGC IN ADVANCE OF THIS FEATURE IS
OVERSPREADING AXIS OF HIER MUCAPE/H85 THETA E AHEAD OF ATTENDANT
COLD FNT...NMRS SHRA/TS ARE BREAKING OUT IN MN.
TNGT...SHRTWV JUST SW OF LK WINNIPEG IS PROGGED TO MOVE ESE AND OVER
NCENTRAL LK SUP BY 12Z SUN. AS THE DPVA/DEEP LYR QVECTOR CNVGC AND
AXIS OF HIER INSTABILITY/H85 THETA E MOVE INTO WRN LK SUP THIS
EVNG...EXPECT SHRA/TS NOW OVER MN TO SHIFT INTO THE WRN LAND CWA BY
06Z. GIVEN FCST MUCAPE IN EXCESS OF 1000 J/KG...SFC-6KM SHEAR IN THE
40-50KT RANGE /FORTUNATELY THE STORMS WL BECOME ELEVATED SO THIS WL
NOT BE THE EFFECTIVE LYR SHEAR/...AND FAIRLY SHARP LLVL CNVGC ALONG
ATTENDANT COLD FNT...SOME OF THESE STORMS MAY BE STRONG. BUT WITH
LOSS OF DAYTIME HEATING AND WEAKENING H85 THETA E AXIS...EXPECT THE
INTENSITY OF THESE SHRA/TS TO DIMINISH AS THEY SPREAD INTO CENTRAL
UPR MI LATE. IN FACT...THE MOST RECENT SPC CONVECTIVE OUTLOOK THRU
12Z SUN CONFINES THE SLGT RISK FOR SVR TS TO MN AND FAR WRN LK SUP.
WHERE TEMPS HAVE A CHC TO COOL DOWN A BIT OVER THE E HALF BEFORE THE
ARRIVAL OF CLDS/A BIT SHARPER PRES GRADIENT...ADDED PATCHY FOG WITH
EXPECTATION THAT MIN TEMPS FALLING INTO THE UPR 50S WL FALL THRU THE
CROSSOVER DEWPT OBSVD THIS AFTN.
SUN...AS SHRTWV OVER NCENTRAL LK SUP IN THE MRNG SHIFTS INTO SE
ONTARIO IN THE AFTN...DNVA/DEEP LYR QVECTOR DVGC/VIGOROUS NEGATIVE
H85 THETA E ADVCTN IS FCST TO ARRIVE W-E FOLLOWING ATTENDANT COLD
FROPA. EXPECT BAND OF SHRA/TS AHD OF COLD FNT TO SHIFT FM THE CNTRL
ZNS INTO THE ERN ZNS DURING THE MRNG. SHRA/TS INTENSITY MAY PICK UP
OVER THE FAR ERN CWA IN THE EARLY AFTN WITH IMPACT OF DAYTIME
HEATING LIFTING MUCAPE TO 500-1000 J/KG AND DEEP LYR SHEAR 30 TO 40
KTS BEFORE THE MORE ROBUST QVECTOR DVGC ARRIVES IN THE AFTN AND
BEGINS TO SUPPRESS THE CONVECTION WITH STRENGTHENING INVRN FOLLOWING
COLD FROPA AT ERY NEAR 21Z. THIS THREAT WOULD BE GREATER IF THE
SOMEWHAT SLOWER GFS VERIFIES...BUT THE PRESENT STEADY SPEED OF
SHRTWV INDICATES THE FASTER MODEL FCSTS ARE ON THE RIGHT TRACK.
FOLLOWING THE COLD FROPA AND ARRIVAL OF LLVL COOLER AIR...NAM FCST
SDNGS SHOW SHARPENING LLVL INVRN/PROSPECT FOR LO CLDS AND SOME
SPRINKLES...ESPECIALLY OVER THE W AND NCENTRAL WITH UPSLOPE NW FLOW.
SFC TEMPS MAY ACTUALLY FALL AT THESE PLACES DURING THE AFTN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MORE SEASONABLE WEATHER IS EXPECTED THROUGH MUCH OF THE UPCOMING
WEEK...WITH CHANCES OF PRECIPITATION MONDAY AND AGAIN WEDNESDAY.
SUNDAY NIGHT AND MONDAY...A STRONG AND SHARP MID-LEVEL SHORTWAVE
OVER NE LAKE SUPERIOR WILL BE STARTING TO EXIT TO THE EAST AT THE
START OF THE PERIOD. THE ASSOCIATED SFC LOW WILL ALSO BE TRACKING
EASTWARD AWAY FROM EASTERN LAKE SUPERIOR. THE MAIN FORECAST CONCERN
IS HOW LONG MOISTURE WILL LINGER BEHIND THIS SYSTEM...AND HOW
WIDESPREAD UPSLOPE DRIZZLE/SHOWERS WILL BE. WITH PLENTY OF LOW-LEVEL
MOISTURE WRAPPING BEHIND THE LOW...EXPECT PLENTY OF DRIZZLE AND
LIGHT SHOWERS FOR ANY AREA EXPOSED TO NNW WINDS OFF LAKE SUPERIOR.
SUBSIDENCE WILL LOWER INVERSION HEIGHTS TO AROUND 1KM ACROSS THE
AREA...SO THE SATURATED LAYER WILL BE QUITE SHALLOW. INSOLATION ON
MONDAY SHOULD BE STRONG ENOUGH TO START ERODING THIS MOIST LAYER
MONDAY MORNING. INCREASINGLY DRIER AIR ADVECTING IN FROM WESTERN
ONTARIO SHOULD THEN REMOVE REMAINING CLOUDS/PRECIP FROM WEST TO EAST
THROUGHOUT MONDAY AFTERNOON.
HAVE INCREASED WINDS SEVERAL KNOTS ACROSS THE EAST HALF OF THE CWA
GIVEN A 1020MB SFC HIGH IN THE UPPER MS VALLEY IMPINGING ON THE
BACKSIDE OF THE DEPARTING 1002MB LOW. COULD SEE QUITE A BREEZY DAY
FOR MUCH OF THE AREA...WITH WINDS GUSTING OVER 30MPH RIGHT NEAR THE
LAKE SUPERIOR SHORE FROM BIG BAY EASTWARD. WILL CONTINUE TO RAMP UP
WORDING ON A HIGH SWIM RISK GIVEN THE LABOR DAY HOLIDAY.
MONDAY NIGHT...AS THE SFC HIGH SETTLES OVER NORTHERN WI MONDAY
NIGHT...CLEAR SKIES AND LOW PWAT VALUES OF LESS THAN 0.5 INCHES WILL
ALLOW FOR GOOD RADIATIONAL COOLING. HAVE MAINTAINED PREVIOUS
FORECAST TEMPS OF LOW 40S INTERIOR WEST HALF TO LOW 50S NEAR THE
GREAT LAKES. RESIDUAL STRONGER NW GRADIENT FLOW ACROSS THE EAST HALF
SHOULD LIMIT COOLING TO SOME EXTENT.
TUESDAY THROUGH THURSDAY...A SHORTWAVE TROUGH CURRENTLY TRACKING
EASTWARD ALONG THE ALLUETIAN ISLANDS WILL STALL OVER WESTERN ALASKA
AND SEND A SERIES OF WEAK WAVES ACROSS WESTERN CANADA. THE MAIN WAVE
OF INTEREST WILL BECOME AMPLIFIED BY ANOTHER STRONGER WAVE OVER THE
NORTH SLOPE OF ALAKSA. TIMING AND STRENGTH OF THIS FEATURE HAVE BEEN
UNDERSTANDABLY DIFFICULT FOR THE MODELS TO PIN DOWN. THE GFS HAS
WAVERED IN STRENGTH OVER THE LAST SEVERAL RUNS...WITH THE LATEST TWO
RUNS INDICATING A SLOWER AND WETTER SOLUTION. THIS IS LIKELY A
RESULT OF A LONGER PRECEEDING PERIOD OF LOW-LEVEL MOISTURE RETURN.
THE GEM IS THE QUICKEST SOLUTION OF THE THREE. HAVE OPTED TO EMPLOY
THE ECMWF FOR THE REST OF THE FORECAST GIVEN ITS MIDDLE GROUND AND
CONTINUITY OVER THE LAST COUPLE DAYS.
THE MAIN MID-LEVEL AND SFC LOWS WILL TRACK WELL NORTH OF THE
CWA...POSSIBLY AS FAR NORTH AS SOUTHERN HUDSON BAY. THE 990MB SFC
LOW DEPICTED BY THE ECMWF WILL BE STRONG ENOUGH TO SEND A POTENT
COLD FRONT SSE-WARD ACROSS THE CWA WEDNESDAY MORNING.
HOWEVER...THERE WILL BE A SUBSTANTIAL AMOUNT OF DRY AIR WITH THIS
SYSTEM GIVEN ITS ORIGIN. WILL PLACE ONLY SLIGHT CHANCE POPS ACROSS
THE FAR NORTH AND EAST CLOSER TO THE STRONGEST FORCING VIA MID-LEVEL
Q-VECTOR CONVERGENCE AND THE LEFT EXIT OF A 120KT UPPER JET. MUCH OF
UPPER MI...ESPECIALLY THE SOUTHWEST...LOOKS TO BE UNDER SUBSIDENCE
FROM THE RIGHT ENTRANCE OF THE JET...AND MAY NOT EVEN SEE MUCH IN
THE WAY OF CLOUD COVER. MOST OF THE COOLER AIR BEHIND THE FRONT WILL
STAY EAST OF THE AREA...SO ONLY A SLIGHTLY COOLER DAY THAN WEDNESDAY
IS EXPECTED FOR THURSDAY.
FRIDAY AND SATURDAY...BESIDE DEVELOPING THE IDEA OF DEEPER TROUGHING
ACROSS EASTERN CANADA...MODEL AGREEMENT ON SMALLER SCALE FEATURES IS
POOR BY THIS POINT IN THE FORECAST. THE GFS/GEM INDICATE STRONG SFC
HIGH PRESSURE BUILDING ACROSS THE AREA...WHILE THE ECMWF KEEP THE
HIGH MUCH FARTHER NE NEAR JAMES BAY. A WEAK SHORTWAVE DEPICTED BY
BOTH THE ECMWF AND GFS COULD BRING SHOWER CHANCES FOR FRIDAY...BUT
TIMING THE GFS IS SOMEWHAT SLOWER WITH THIS IDEA. EITHER WAY...VERY
LIMITED MOISTURE WILL PRECLUDE ANYTHING MORE THAN SPOTTY SHOWER
COVERAGE. HAVE OPTED TO MAINTAIN CONCENSUS FORECAST AT THIS POINT
GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 151 AM EDT SUN SEP 1 2013
STRONG DISTURBANCE AND ASSOCIATED SFC LOW AND COLD FRONT WILL AFFECT
THE REGION THRU THIS FCST PERIOD. ALTHOUGH SHRA/TSRA HAVE DIMINISHED
IN COVERAGE OVER THE LAST SEVERAL HRS...STRENGTH OF DISTURBANCE
SUGGESTS THERE WILL BE SHRA AND A FEW TSRA SCATTERED AROUND THE AREA
THRU THE NIGHT INTO THE MORNING HRS. UNLESS MORE ORGANIZED PCPN
DEVELOPS...ONLY VCSH WILL BE UTILIZED AT KIWD/KCMX/KSAW OVERNIGHT.
VFR CONDITIONS SHOULD GENERALLY PREVAIL...EXCEPT AT KCMX WHERE SOME
BR HAS DEVELOPED WITH LIGHT UPSLOPE. NOT OUT OF THE QUESTION THAT
IFR OR EVEN LIFR COULD DEVELOP THERE. AS WINDS VEER THEN SHIFT TO
GUSTY NW WITH PASSAGE OF COLD FRONT...EXPECT CONDITIONS TO
DETERIORATE TO IFR AT KIWD/KCMX THIS MORNING. LATER FRONTAL PASSAGE
AND INITIALLY POST FRONTAL DOWNSLOPE NW WINDS SHOULD RESULT IN ONLY
MVFR CIGS AT KSAW MID/LATE AFTN. WITH LATER FRONTAL PASSAGE...IT`S
POSSIBLE TSRA COULD AFFECT KSAW EARLY IN THE AFTN. MVFR CIGS SHOULD
PREVAIL AT ALL TERMINALS INTO THE EVENING HRS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT SAT AUG 31 2013
EXPECT SSW WINDS UP TO 20-25 KTS TONIGHT INTO SUN MORNING OVER THE E
HALF OF THE LAKE UNDER A SHARPENING PRES GRADIENT AHEAD OF AN
APPROACHING COLD FRONT. FOLLOWING THE PASSAGE OF THIS FRONT...THERE
WILL BE A WIND SHIFT TO THE NW...WITH WINDS INCREASING UP TO 25 KTS
IN THE AFTERNOON. THE COMBINATION OF DECREASING STABILITY WITH THE
ARRIVAL OF A COOL AIRMASS AND A SHARPENING PRES GRADIENT BETWEEN A
DEPARTING LO PRES SYSTEM AND AN APPROACHING HI WILL RESULT IN NW-N
WINDS UP TO 20-30 KTS ON SUN NIGHT INTO MON. THE ARRIVAL OF THE HI
AND WEAKER PRES GRADIENT WILL ALLOW WINDS TO DIMINISH UNDER 20 KTS
TUE THRU THU.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
324 AM MDT SUN SEP 1 2013
...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR
DAY...
.DISCUSSION...COLD FRONT APPEARS TO BE IN NORTHEASTERN CO
STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY
WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE
LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP
A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET
SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF
OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE
NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER
MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL
BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY
STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE
SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH
ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW
WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE
ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE
BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A
SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE
BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD
HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED.
LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS
EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS
CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY
MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH
SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING
THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR
WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR
DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE
SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40.
WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL
ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE
CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER
BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE
SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL
MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH
SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF
400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL
MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST
TOWARD TX.
TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT
MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH
THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO
CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING
TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT
WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH
WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE
MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED
ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP
SUBTROPICAL MOISTURE INTRUSIONS.
52
&&
.FIRE WEATHER...
UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND
FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING
SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY.
WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS
STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM.
NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST
LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING
ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS
BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON.
NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES
TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO
THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE
RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO
REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS
OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH
RECOVERIES ANTICIPATED.
CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE
CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A
BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO
SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO
POOR VENTILATION LIKELY OVER THE WEST AND NORTH.
A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY
PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING
WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER
HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING
TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES.
AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL
AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY.
WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST.
HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND
CENTRAL NM.
&&
.AVIATION...
06Z TAF CYCLE
ISOLD -SHRA AND POSSIBLY A -TSRA WILL LINGER INTO THE LATE NIGHT
HOURS MAINLY NORTH OF I-40 AND EAST OF HIGHWAY 550 TO THE BORDER
WITH TX/OK. A BACK DOOR COLD FRONT WILL SAG INTO THE NE PLAINS
TONIGHT AND THE REST OF THE EASTERN PLAINS ON SUNDAY...BEFORE
PUSHING THROUGH GAPS IN THE CENTRAL MOUNTAIN CHAIN WITH A SOMEWHAT
GUSTY E CANYON WIND IN THE RIO GRANDE VALLEY LATE SUNDAY AFTN INTO
THE NIGHT. THE FRONT WILL BRING MOISTURE AND A TRIGGER FOR TS AND
SHRA WITH MORE WDSPRD CONVECTION SUNDAY AFTN AND EVENING. WITH
THE FRONT PROGRESSING UP THE EAST SLOPES OF THE CONTDVD...THE
CONTDVD REGION COULD REMAIN ACTIVE WITH STORMS INTO THE LATE NIGHT
HOURS.
44
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 90 65 90 62 / 20 40 20 20
DULCE........................... 83 51 80 51 / 40 50 50 40
CUBA............................ 85 56 82 54 / 50 40 60 60
GALLUP.......................... 86 57 86 55 / 20 40 40 40
EL MORRO........................ 84 54 82 52 / 30 50 60 50
GRANTS.......................... 88 57 85 54 / 40 50 60 50
QUEMADO......................... 86 57 85 55 / 40 40 50 50
GLENWOOD........................ 90 62 89 61 / 20 20 30 30
CHAMA........................... 80 47 79 45 / 50 60 60 60
LOS ALAMOS...................... 86 58 83 56 / 50 40 50 50
PECOS........................... 83 56 81 55 / 60 60 60 60
CERRO/QUESTA.................... 79 51 77 49 / 70 50 60 50
RED RIVER....................... 69 40 66 41 / 80 60 70 60
ANGEL FIRE...................... 74 39 72 39 / 80 60 70 60
TAOS............................ 83 55 81 52 / 50 50 50 50
MORA............................ 78 53 74 51 / 70 70 60 60
ESPANOLA........................ 91 60 87 59 / 40 30 40 40
SANTA FE........................ 87 59 83 57 / 50 40 50 50
SANTA FE AIRPORT................ 91 60 86 59 / 40 30 40 40
ALBUQUERQUE FOOTHILLS........... 91 66 87 64 / 40 30 40 40
ALBUQUERQUE HEIGHTS............. 93 70 89 69 / 30 30 30 40
ALBUQUERQUE VALLEY.............. 95 64 91 62 / 20 30 30 40
ALBUQUERQUE WEST MESA........... 95 65 90 65 / 20 30 30 40
LOS LUNAS....................... 96 67 93 65 / 20 30 30 40
RIO RANCHO...................... 94 68 90 67 / 30 30 30 40
SOCORRO......................... 95 67 91 66 / 20 20 20 30
SANDIA PARK/CEDAR CREST......... 85 54 82 55 / 50 50 50 50
TIJERAS......................... 89 59 85 58 / 50 40 50 40
MORIARTY/ESTANCIA............... 91 56 87 56 / 50 30 50 50
CLINES CORNERS.................. 85 58 80 58 / 60 60 70 60
GRAN QUIVIRA.................... 88 60 82 59 / 40 30 40 50
CARRIZOZO....................... 91 61 86 59 / 30 20 40 40
RUIDOSO......................... 82 56 74 53 / 30 40 60 60
CAPULIN......................... 82 54 80 53 / 70 50 50 40
RATON........................... 84 56 81 55 / 60 50 50 40
SPRINGER........................ 88 56 83 56 / 70 50 50 40
LAS VEGAS....................... 84 55 79 55 / 70 70 50 50
CLAYTON......................... 90 62 86 63 / 50 40 30 20
ROY............................. 88 60 82 61 / 60 50 50 40
CONCHAS......................... 94 66 89 66 / 50 50 40 40
SANTA ROSA...................... 94 65 87 64 / 40 50 40 40
TUCUMCARI....................... 96 66 89 65 / 50 50 40 30
CLOVIS.......................... 94 64 86 63 / 20 40 40 30
PORTALES........................ 94 67 87 64 / 20 30 40 30
FORT SUMNER..................... 95 67 89 65 / 30 40 40 40
ROSWELL......................... 98 69 91 67 / 10 20 40 40
PICACHO......................... 92 64 86 62 / 20 20 40 50
ELK............................. 86 60 79 57 / 20 20 50 60
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
52
AREA FORECAST DISCUSSION
NWS RALEIGH NC
302 AM EDT SUN SEP 01 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...
THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND TUESDAY
NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE REGION
FROM THE NORTHWEST WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 220 AM SUNDAY...
WE`RE STILL EXPECTING SCATTERED SHOWERS/STORMS TODAY INTO THIS
EVENING... ALTHOUGH DETAILS AS TO WHO WILL SEE THE BEST CHANCES AND
WHEN REMAIN MURKY. LATEST SURFACE MAP SHOWS THE SYNOPTIC FRONTAL
ZONE EXTENDING FROM A LOW OVER THE UPPER MIDWEST ACROSS THE LOWER
GREAT LAKES AND ST LAWRENCE VALLEY... WHILE WEAK LEE SURFACE
TROUGHING HOLDS OVER CENTRAL VA/NC. TWO PRIMARY FORCING FEATURES ARE
EXPECTED TO DRIVE OUR PRECIP CHANCES TODAY. FIRST IS A MID LEVEL
SHORTWAVE -- A REFLECTION OF YESTERDAY`S CONVECTION TO THE WEST OVER
THE MOUNTAINS -- NOW TRACKING THROUGH MD/VA/NC AND EXPECTED TO SHIFT
SLOWLY ESE THEN EAST INTO ERN VA/NC THIS MORNING. THIS SHOULD
ENCOUNTER A MOIST (AND INCREASINGLY SO... WITH PW VALUES EXPECTED TO
QUICKLY JUMP UP TOWARD 1.8-1.9 IN.) ENVIRONMENT OVER THE COASTAL
PLAIN AND COASTAL AREA. WITH DEW POINTS IN THE 70-75 RANGE AND GOOD
MORNING HEATING ALLOWING THE CONVECTIVE TEMP TO BE REACHED BY
MID-LATE MORNING... EXPECT EARLY DEVELOPMENT OF SHOWERS/STORMS OVER
THE COASTAL PLAIN AND SANDHILLS... AUGMENTED BY AN INLAND-MOVING SEA
BREEZE BY AFTERNOON. THE SECOND FEATURE OF INTEREST IS AN MCV
RESULTING FROM THE ORGANIZED STORMS NOW OVER SRN IN/IL EXTENDING
THROUGH THE OH VALLEY. THIS WAVE SHOULD FOLLOW IN THE TRACKS OF THE
PREVIOUS ONE... SHIFTING ESE THEN EAST DURING THE DAY... POTENTIALLY
ENHANCING CONVECTION OVER THE CENTRAL/SRN APPALACHIANS WHICH WOULD
THEN DRIFT EASTWARD OFF THE HIGHER TERRAIN INTO THE FOOTHILLS AND
WRN PIEDMONT LATER IN THE DAY INTO EARLY EVENING. THE NAM/GFS
GENERALLY FIT WITH THE SCENARIO OUTLINED HERE FOR THE TWO
FEATURES... SO WHILE THE OVERALL FORECAST WILL REFLECT SCATTERED
STORMS (30-50% POPS) OVER ALL OF CENTRAL NC... THE FORECAST TIMING
WILL SHOW GREATER POPS SOUTHEAST OF RALEIGH STARTING IN THE LATE
MORNING... THEN PEAKING LATER (MID AFTERNOON) OVER THE WRN
PIEDMONT... SHIFTING EAST INTO THE ERN PIEDMONT AND WRN SANDHILLS
BEFORE DISSIPATING BY MID TO LATE EVENING WITH LOSS OF HEATING AND
WEAK POST-WAVE SUBSIDENCE. REGARDING STORM STRENGTH... MLCAPE IS
EXPECTED TO TOP OUT AT 1500-2000 J/KG MAINLY OVER THE ERN CWA... BUT
DEEP LAYER SHEAR REMAINS WEAK AT AROUND 15 KTS. WE MAY SEE A FEW
STRONG GUSTS WITH ISOLATED CELLS BASED ON THE FORECAST SOUNDING
PROFILES... BUT WIDESPREAD STRONG/SEVERE STORMS ARE NOT EXPECTED.
TEMPS ARE TOUGH AS ABOVE-NORMAL THICKNESSES (BY ABOUT 10-12 M) WILL
BE MODULATED BY SOME MORNING STRATUS AND CONVECTIVE CLOUD COVER THIS
AFTERNOON. GRIDDED LAMP GUIDANCE INDICATES HIGHS OF 88-92... CLOSE
TO THAT INDICATED BY A DRY ADIABATIC LAPSE RATE... AND ABOUT A
DEGREE ABOVE EARLIER FORECAST HIGHS. EXPECT GENERALLY PARTLY CLOUDY
SKIES TONIGHT WITH VARYING DEGREES OF CONVECTIVE DEBRIS CLOUDINESS
OVER THE REGION. LOWS 69-73. -GIH
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SUNDAY...
SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG
DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI
SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC
MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST
LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE...
THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY
NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID
LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL
MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT
1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW
DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES
TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR
INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG
FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW
CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW
AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY
AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS...
WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS
SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS...
ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15
KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY
CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY
AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN
CONVECTIONS DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF
COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR
TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS
MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430
M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR
90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A
LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 215 AM SUNDAY...
THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE
SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S.
TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE
THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL
WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND
SATURDAY.
THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND
TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM
IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL
TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT.
GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE
FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL
PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE
WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE
THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE
COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH
A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL
RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE
SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER
AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS
STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE
LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON
PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR
THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE
COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS
WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S.
FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH
PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT
PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC.
THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND
SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE
A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS
WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED
AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES
SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA
BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING
FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING
THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING
LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE
TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS
IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD
FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT
LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING
THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH
THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES
TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL
LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW
LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM
EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE
TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING
SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES
THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND
FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING
POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE
RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND
DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS
STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR --
SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN
TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO
PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST
TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE
BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH
DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM
LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY
DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY
SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF
THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING).
LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS
POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW
SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND
STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY
AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM
THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS
AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE
LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN
FROM THE NW WITH MUCH DRIER AIR. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
224 AM EDT SUN SEP 01 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY
NIGHT...THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND
TUESDAY NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE
REGION FROM THE NORTHWEST WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 220 AM SUNDAY...
WE`RE STILL EXPECTING SCATTERED SHOWERS/STORMS TODAY INTO THIS
EVENING... ALTHOUGH DETAILS AS TO WHO WILL SEE THE BEST CHANCES AND
WHEN REMAIN MURKY. LATEST SURFACE MAP SHOWS THE SYNOPTIC FRONTAL
ZONE EXTENDING FROM A LOW OVER THE UPPER MIDWEST ACROSS THE LOWER
GREAT LAKES AND ST LAWRENCE VALLEY... WHILE WEAK LEE SURFACE
TROUGHING HOLDS OVER CENTRAL VA/NC. TWO PRIMARY FORCING FEATURES ARE
EXPECTED TO DRIVE OUR PRECIP CHANCES TODAY. FIRST IS A MID LEVEL
SHORTWAVE -- A REFLECTION OF YESTERDAY`S CONVECTION TO THE WEST OVER
THE MOUNTAINS -- NOW TRACKING THROUGH MD/VA/NC AND EXPECTED TO SHIFT
SLOWLY ESE THEN EAST INTO ERN VA/NC THIS MORNING. THIS SHOULD
ENCOUNTER A MOIST (AND INCREASINGLY SO... WITH PW VALUES EXPECTED TO
QUICKLY JUMP UP TOWARD 1.8-1.9 IN.) ENVIRONMENT OVER THE COASTAL
PLAIN AND COASTAL AREA. WITH DEW POINTS IN THE 70-75 RANGE AND GOOD
MORNING HEATING ALLOWING THE CONVECTIVE TEMP TO BE REACHED BY
MID-LATE MORNING... EXPECT EARLY DEVELOPMENT OF SHOWERS/STORMS OVER
THE COASTAL PLAIN AND SANDHILLS... AUGMENTED BY AN INLAND-MOVING SEA
BREEZE BY AFTERNOON. THE SECOND FEATURE OF INTEREST IS AN MCV
RESULTING FROM THE ORGANIZED STORMS NOW OVER SRN IN/IL EXTENDING
THROUGH THE OH VALLEY. THIS WAVE SHOULD FOLLOW IN THE TRACKS OF THE
PREVIOUS ONE... SHIFTING ESE THEN EAST DURING THE DAY... POTENTIALLY
ENHANCING CONVECTION OVER THE CENTRAL/SRN APPALACHIANS WHICH WOULD
THEN DRIFT EASTWARD OFF THE HIGHER TERRAIN INTO THE FOOTHILLS AND
WRN PIEDMONT LATER IN THE DAY INTO EARLY EVENING. THE NAM/GFS
GENERALLY FIT WITH THE SCENARIO OUTLINED HERE FOR THE TWO
FEATURES... SO WHILE THE OVERALL FORECAST WILL REFLECT SCATTERED
STORMS (30-50% POPS) OVER ALL OF CENTRAL NC... THE FORECAST TIMING
WILL SHOW GREATER POPS SOUTHEAST OF RALEIGH STARTING IN THE LATE
MORNING... THEN PEAKING LATER (MID AFTERNOON) OVER THE WRN
PIEDMONT... SHIFTING EAST INTO THE ERN PIEDMONT AND WRN SANDHILLS
BEFORE DISSIPATING BY MID TO LATE EVENING WITH LOSS OF HEATING AND
WEAK POST-WAVE SUBSIDENCE. REGARDING STORM STRENGTH... MLCAPE IS
EXPECTED TO TOP OUT AT 1500-2000 J/KG MAINLY OVER THE ERN CWA... BUT
DEEP LAYER SHEAR REMAINS WEAK AT AROUND 15 KTS. WE MAY SEE A FEW
STRONG GUSTS WITH ISOLATED CELLS BASED ON THE FORECAST SOUNDING
PROFILES... BUT WIDESPREAD STRONG/SEVERE STORMS ARE NOT EXPECTED.
TEMPS ARE TOUGH AS ABOVE-NORMAL THICKNESSES (BY ABOUT 10-12 M) WILL
BE MODULATED BY SOME MORNING STRATUS AND CONVECTIVE CLOUD COVER THIS
AFTERNOON. GRIDDED LAMP GUIDANCE INDICATES HIGHS OF 88-92... CLOSE
TO THAT INDICATED BY A DRY ADIABATIC LAPSE RATE... AND ABOUT A
DEGREE ABOVE EARLIER FORECAST HIGHS. EXPECT GENERALLY PARTLY CLOUDY
SKIES TONIGHT WITH VARYING DEGREES OF CONVECTIVE DEBRIS CLOUDINESS
OVER THE REGION. LOWS 69-73. -GIH
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 215 PM SATURDAY...
MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF
THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT
BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST
SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM
ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON
THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES
PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL
INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE
A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY
AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE
BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE
MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD
CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS
WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW
90S...LOWS UPPER 70S. -MLM
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 215 AM SUNDAY...
THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE
SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S.
TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE
THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL
WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND
SATURDAY.
THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND
TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM
IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL
TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT.
GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE
FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL
PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE
WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE
THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE
COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH
A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL
RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE
SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER
AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS
STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE
LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON
PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR
THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE
COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS
WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S.
FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH
PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT
PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC.
THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND
SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE
A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS
WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED
AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES
SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA
BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING
FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING
THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING
LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE
TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS
IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD
FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT
LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING
THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH
THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES
TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL
LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW
LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM
EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE
TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING
SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES
THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND
FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING
POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE
RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND
DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS
STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR --
SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN
TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO
PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST
TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE
BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH
DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM
LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY
DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY
SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF
THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING).
LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS
POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW
SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND
STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY
AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM
THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS
AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE
LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN
FROM THE NW WITH MUCH DRIER AIR. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...MLM
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
215 AM EDT SUN SEP 01 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY
NIGHT...THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND
TUESDAY NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE
REGION FROM THE NORTHWEST WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 1025 PM SATURDAY...
BAND OF SHOWERS AND THUNDERSTORMS WHICH ENTERED THE NW PIEDMONT
AROUND 21Z DIMINISHED AS IT DRIFTED EAST. AIR MASS OVER BULK OF THE
PIEDMONT NOT AS UNSTABLE AS THE FOOTHILLS AND WESTERN PIEDMONT PLUS
LACK OF DECENT SHEAR AND LACK OF UPPER LEVEL SUPPORT LED TO THE
DISSIPATION OF MOST OF THE SHOWERS.
ANOTHER UPPER LEVEL DISTURBANCE IS APPROACHING WESTERN NC FROM THE
EASTERN TN VALLEY. THIS FEATURE PROJECTED TO CROSS OUR REGION
OVERNIGHT (AFTER 06Z). WITH PRECIP WATER VALUES 1.8-2 INCHES AND A
FEW SFC TROUGHS/OUTFLOW BOUNDARIES EXISTING ACROSS THE
REGION...COULD SEE A REGENERATION IN SHOWER/ISOLATED THUNDERSTORM
ACTIVITY OVERNIGHT-EARLY SUNDAY MORNING. PLAN TO MAINTAIN A SMALL
CHANCE POP ACROSS THE FAR NW-NORTHERN PIEDMONT...AND SLIGHT CHANCE
ACROSS MOST OF THE REMAINDER OF CENTRAL NC. OVERNIGHT MIN TEMPS
SHOULD BE FAIRLY UNIFORM AROUND 70.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 215 PM SATURDAY...
CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS
POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER
MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON
SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL
STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES
INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL
DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000
J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL
BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW...
THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE
WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP
CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER
TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40%
CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN
PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING
AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE
PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY...
PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE
AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS
AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO
CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT
MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF
THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT
BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST
SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM
ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON
THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES
PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL
INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE
A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY
AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE
BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE
MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD
CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS
WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW
90S...LOWS UPPER 70S. -MLM
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 215 AM SUNDAY...
THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE
SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S.
TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE
THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL
WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND
SATURDAY.
THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND
TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM
IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL
TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT.
GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE
FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL
PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE
WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE
THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE
COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH
A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL
RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE
SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER
AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS
STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE
LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON
PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR
THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE
COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS
WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S.
FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH
PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT
PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC.
THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND
SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE
A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS
WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED
AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES
SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA
BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING
FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING
THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING
LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE
TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS
IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD
FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT
LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING
THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH
THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES
TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL
LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW
LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM
EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE
TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING
SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES
THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND
FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING
POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE
RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND
DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS
STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR --
SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN
TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO
PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST
TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE
BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH
DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM
LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY
DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY
SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF
THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING).
LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS
POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW
SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND
STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY
AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM
THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS
AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE
LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN
FROM THE NW WITH MUCH DRIER AIR. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...WSS
SHORT TERM...VINCENT/MLM
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 1245 AM CDT SUN SEP 1 2013
CURRENTLY...HIGH PRESSURE WAS CENTERED OVER CENTRAL/SOUTHERN
SASKATCHEWAN WITH THE HIGH AXIS EXTENDING INTO EASTERN MONTANA. AN
AREA OF VFR/MVFR CLOUDS OVER SOUTHERN SASKATCHEWAN AND MANITOBA HAD
EDGED INTO FAR NORTHERN NORTH DAKOTA. MODELS STILL SUGGESTING THESE
CLOUDS WILL MOVE SOUTH ACROSS THE STATE OVERNIGHT. THE HIGH IS
FORECAST TO MOVE SOUTHEAST AND BY EARLY AFTERNOON BE CENTERED OVER
LAKE WINNIPEG INTO THE JAMES/RED RIVER VALLEYS. NORTHWEST WINDS
SHOULD BECOME NORTH...THEN NORTHEAST OVERNIGHT INTO THE LATER
MORNING HOURS. LOWERED OVERNIGHT LOWS A BIT...ESPECIALLY IN THE
SOUTH WHICH SHOULD REMAIN CLOUD-FREE UNTIL LATER TONIGHT. CURRENT
FORECAST LOOKS ON TRACK.
UPDATE ISSUED AT 954 PM CDT SAT AUG 31 2013
CLEAR SKIES ACROSS ALL BUT THE FAR NORTHWEST THIS EVENING WITH
DIMINISHING NORTH TO NORTHWEST WINDS. EXTENSIVE CLOUD COVER ACROSS
SOUTHERN SASKATCHEWAN AND MANITOBA IS PUSHING SOUTH AND IS
EXPECTED TO DROP SOUTH ACROSS WESTERN AND CENTRAL NORTH DAKOTA
LATE TONIGHT. LATEST 01 SEP 00Z NAM AND RUC GUIDANCE SUGGESTS
HIGHEST 925-850MB RH SHOULD CONTINUE TO PUSH SOUTH THROUGH EASTERN
PORTIONS OF THE CWA...BUT LINGER IN THE WEST...MAINLY FROM ISN TO
BETWEEN BISMARCK AND DICKINSON ON THE BACK SIDE OF THE SURFACE
HIGH. ADJUSTED CLOUD COVER BASED ON LATEST LOW LEVEL RH GUIDANCE.
OTHERWISE A QUIET NIGHT WITH DIMINISHING WINDS AND COMFORTABLE
TEMPERATURES MAINLY IN THE 50S.
UPDATE ISSUED AT 638 PM CDT SAT AUG 31 2013
MUCH COOLER AIR BEHIND AN EXITING COLD FRONT WILL CONTINUE TO
SPILL ACROSS WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. AN UPPER
LEVEL LOW ACROSS MANITOBA HAS MOVED FAR ENOUGH EAST THAT EARLY
EVENING SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL. OTHER
THAN REMOVING POPS NORTH CENTRAL AND MINOR CLOUD COVER
ADJUSTMENTS...THE CURRENT FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 250 PM CDT SAT AUG 31 2013
DRIER AND COOLER AIR WILL HIGHLIGHT THE SHORT TERM FORECAST.
AS OF 20 UTC...THE COLD FRONT HAS CLEARED THE CWA WITH LOW LEVEL
DRY AND COLD AIR ADVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA
AND WIDESPREAD WIND GUSTS OF 25-30 KTS IN POST FRONTAL MIXING.
DID ADD A MENTION OF ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE
NORTH CENTRAL THIS AFTERNOON AND EARLY EVENING WITH THE UPPER
LEVEL LOW THAT IS PROPAGATING SOUTHEAST OUT OF FAR SOUTHEAST
SASKATCHEWAN. ANY CONVECTION THAT DOES FORM WILL FADE WITH SUNSET.
AN EXPANSE OF STRATUS IS EXPECTED TO OVERSPREAD AREAS ALONG AND
NORTH OF I-94 TONIGHT...WHICH WILL HELP TO KEEP OVERNIGHT LOWS IN
THE 50S. A QUIET A REFRESHINGLY COOL DAY IS EXPECTED SUNDAY WITH
HIGHS IN THE 70S WITH HIGH PRESSURE IN PLACE. GIVEN GOOD
AGREEMENT...A BLEND OF THE 12 UTC GUIDANCE SUITE WAS USED FOR ALL
FIELDS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 250 PM CDT SAT AUG 31 2013
AFTER A COOL AND DRY SUNDAY...WILL SEE A WARMING TREND BACK TO
ABOVE NORMAL TEMPERATURES THROUGH THE COMING WORK WEEK AS THE
CENTRAL U.S. UPPER RIDGE REBUILDS/AMPLIFIES FROM ACROSS THE
ROCKIES NORTH INTO THE CANADIAN HIGH PLAINS...BRINGING WAA BACK
EAST INTO THE DAKOTAS. EXPECT MOSTLY DRY CONDITIONS OVER NORTH
DAKOTA THROUGH THURSDAY NIGHT WITH A DRY NORTHWEST FLOW ALOFT.
THE EXCEPTION MAY BE THE TUESDAY AFTERNOON THROUGH WEDNESDAY
NIGHT PERIOD WHEN MODELS PROJECT AN EMBEDDED S/WV IMPULSE MOVING
THROUGH THE RIDGE FROM ACROSS SOUTHERN MONTANA EAST INTO THE
DAKOTAS. HAVE CONFINED SLIGHT CHANCE POPS FOR NOW TUESDAY NIGHT
THROUGH WED NIGHT. THE LATEST ECMWF (12Z) NOW BRINGS THIS FEATURE
TO THE ND/MT BORDER BY 00Z WED...SO FUTURE UPDATED FORECASTS MAY
NEED TO ADD SOME MENTION OF THUNDERSTORMS STARTING TUESDAY
AFTERNOON ACROSS THE WEST.
AS WE HEAD INTO THE LATER PORTIONS OF THE WORK WEEK AND THE FIRST
HALF OF NEXT WEEKEND...MODELS PROJECT THE RIDGE TO BREAKDOWN AS A
CLOSED UPPER LOW (NOW OFF THE NORTHWEST U.S. COAST) MOVES INLAND
SOMETIME THURSDAY NIGHT OR FRIDAY...THEN EAST TOWARDS THE NORTHERN
PLAINS SOMETIME FRI-SUN. LATEST GFS/ECMWF DIFFER ON THE TIMING OF
THIS FEATURE...SO LOTS OF UNCERTAINTY STILL IN PLAY. EVENTUALLY
THIS FEATURE WILL BE THE FOCUS OF LATER FORECASTS AS IT IS
EXPECTED TO BRING COOLER WEATHER AND INCREASED CHANCES FOR
PRECIPITATION TO OUR REGION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1245 AM CDT SUN SEP 1 2013
LATEST GUIDANCE IS STILL SUGGESTING LOW VFR TO MVFR CEILINGS
DROPPING SOUTH INTO THE FORECAST AREA OVERNIGHT AND SUNDAY MORNING.
THEN IMPROVING CEILINGS LATE SUNDAY MORNING WITH A NORTH FLOW
SHIFTING EAST TO SOUTHEAST SUNDAY AFTERNOON. BROUGHT VFR CIGS TO
KISN/KMOT AT 06Z...THEN MVFR BY 09Z...THEN IMPROVING TO VFR CIGS BY
AROUND 16Z. SOUTHERN TAF SITES KDIK/KBIS/KJMS...BROUGHT VFR CIGS BY
09Z/10Z THEN MVFR BY AROUND 12Z...IMPROVING TO VFR BY 18Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JV
SHORT TERM...AYD
LONG TERM...NH
AVIATION...JV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
401 AM EDT SUN SEP 1 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING
MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE
FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT
AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z
MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH
SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK
HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7
TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY
DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL
SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF
THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN
BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES
TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE
TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE
POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN
ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT.
SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST
OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG
DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON
LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT
OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE
PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION.
WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP
A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST
FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO
AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT
INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS
BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED
TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER
LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET.
INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW
VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT
DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS
THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV
HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN.
ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE
IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS
NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION.
THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS
SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL
EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF
THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT
LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING
REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE
MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH.
TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH
PRESSURE MOVES INTO THE AREA FROM THE NW.
RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE
MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE
WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT
THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE
START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND
DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR
DAY WEEKEND.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH
PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK.
TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL
SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW
TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE
WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED
PRECIPITATION.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
ISOLD SHOWERS/STORMS CONTINUING TO LINGER THROUGH ABOUT 11Z...WITH
BRIEF MVFR/IFR CONDITIONS IN VICINITY. OTHERWISE...PATCHY MVFR/IFR
FOG...BUT MOST AREAS SHOULD REMAIN VFR UNDER EXTENSIVE CLOUD SHIELD.
CONVECTION WILL INCREASE IN COVERAGE AGAIN AFTER 12Z...AS AN UPPER
DISTURBANCE MOVES EAST THROUGH THE AREA. EXPECT BRIEF MVFR/IFR
CONDITIONS AND GUSTY WINDS IN VICINITY OF STORMS. BULK OF
CONVECTION WILL DIE DOWN AFTER 03Z. FOG DEVELOPMENT TONIGHT WILL
DEPEND ON THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION
DURING THE DAY. BEST LOCATION FOR POTENTIAL FOG DEVELOPMENT WILL
BE EASTERN KENTUCKY AND SOUTHEAST OHIO WHERE BETTER CLEARING IS
EXPECTED.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND POTENTIAL FOR CONVECTION DEPENDS
ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG TIMING AND DENSITY
MAY VARY FROM CURRENT FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 09/01/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M M L L H H H H H H H H
HTS CONSISTENCY M M L L M H H H H H H M
BKW CONSISTENCY H H H H M H H H H H H H
EKN CONSISTENCY M L L L M M L H H H H H
PKB CONSISTENCY M M L L H H H H H H H M
CKB CONSISTENCY M M L L H H H H H H H H
AFTER 06Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...SL
SHORT TERM...TRM
LONG TERM...26
AVIATION...SL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
518 AM EDT SUN SEP 1 2013
.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH
PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO
KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT
CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON
WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE
PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED
INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING
SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST
AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T
HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD
IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG.
AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING
THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST
TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE
INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE
CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE
TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN
MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD
THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA.
ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP
CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE
WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON
ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND
SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH
TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE
FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE
NEEDED.
STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO
YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW
EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING
THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR
TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE
MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED
WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY
FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL.
THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT
POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY
DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE
HIGHEST CHANCES BY MID AFTN.
TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM
NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY
EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL
SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS
OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS
TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES.
SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT
GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS
PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE
HEAVY RAIN AND FLASH FLOODING STILL A THREAT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY
WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING
WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A
MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS
INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP
MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO
ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER
CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS
INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO
PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY.
CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING.
WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE
LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE
ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED.
LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE
NITE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT
THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW
OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF
OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE
STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE
AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP
DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI
WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL
CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING
BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR
NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW
NORMAL AND RISE TO NEAR NORMAL.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
AT KCLT /09Z UPDATE/...SPOTTY MVFR TO IFR FOG ACCOMPANIED BY LOW
CIGS OBSERVED NEARBY...BUT SO FAR THE FIELD HAS AVOIDED ANY
RESTRICTIONS. MOST RELIABLE NEAR TERM GUIDANCE /08Z LAMP/ TAKES KCLT
DOWN TO MVFR NEAR DAYBREAK. I THINK ALL IT WILL TAKE TO GET MVFR FOG
IS A TINY DROP IN TEMPS...BUT THAT MAY NOT OCCUR SO JUST PUT MVFR IN
TEMPO. A GREATER RISK IS FOR SOME LOW CIGS TO DRIFT IN...SO WILL
KEEP MONITORING. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND
WILL KEEP A PROB30 DURING THE AFTERNOON...AND A VCSH SURROUNDING TO
REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD. FOLLOWING THE
END OF THE DIURNAL CONVECTION GUIDANCE SUPPORTS VFR FCST THRU 06Z
WITH MAINLY MID CLOUDS. WINDS WILL REMAIN LIGHT SW THRU THE PERIOD.
ELSEWHERE...SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST
EARLY TODAY THOUGH CURRENT TRENDS SUGGEST LITTLE THREAT TO KAVL OR
ANY OTHER TAF SITE. MOIST CONDITIONS AND IN SOME CASES WET SOILS
FROM SAT AFTN RAIN HAS ALREADY ALLOWED MVFR TO IFR FOG ACRS MUCH OF
THE AREA. SOME LOWERING STILL POSSIBLE THOUGH CIRRUS DEBRIS MOVING
OVERHEAD WILL BE A MITIGATING FACTOR IN FOG/CIGS...AND INDEED A FEW
SITES HAVE IMPROVED SLIGHTLY UNDER THE CIRRUS. LIFR AT KAVL AND IN
OTHER MTN VALLEYS. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY
AND WILL KEEP A PROB30 DURING THE AFTERNOON AS WELL AS A VCSH/VCTS
AS NECESSARY TO INDICATE LESSER PROBABILITY INTO THE EVENING. FLOW
REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT
KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR
NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH VFR IS EXPECTED THRU 06Z
EXCEPT FOR MVFR FOG DEVELOPING PRIOR TO THEN AT KAVL.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN
MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND
WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON
TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER
AIR WILL FOLLOW THE FRONT.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT MED 77% HIGH 85% HIGH 100% HIGH 100%
KGSP HIGH 80% MED 78% HIGH 100% HIGH 100%
KAVL MED 65% HIGH 85% HIGH 100% HIGH 100%
KHKY HIGH 86% MED 64% HIGH 100% HIGH 100%
KGMU MED 76% MED 78% HIGH 100% HIGH 100%
KAND MED 72% HIGH 85% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
319 AM CDT SUN SEP 1 2013
.DISCUSSION...
NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW
DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN
ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID
ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS
ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST
TOWARD THE UPPER TEXAS COAST.
ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH
OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE
RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109
AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS
EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A
SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER
SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON.
IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP
SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND
TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS
EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER
LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND
TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE
DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM.
SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED
RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z
LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN
THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH
INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS.
MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE
INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES
WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR.
LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH
STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER
DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A
SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS
THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE
SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE
RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING
BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM
CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS.
THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING
WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS.
THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE
DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW
CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE
SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL
COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE
ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST
TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE
CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER
HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO
SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH
POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY
DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD
TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE
AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON
WHERE THIS FEATURE TRACKS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 102 79 98 77 98 / 10 40 20 20 10
WACO, TX 101 77 100 75 98 / 5 20 20 20 20
PARIS, TX 101 74 96 71 96 / 20 30 20 10 10
DENTON, TX 103 77 97 72 97 / 20 40 20 10 10
MCKINNEY, TX 102 76 97 73 98 / 20 40 20 10 10
DALLAS, TX 103 80 98 78 99 / 10 40 20 20 10
TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10
CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10
TEMPLE, TX 99 74 98 74 97 / 5 10 20 20 20
MINERAL WELLS, TX 102 74 95 73 96 / 10 40 30 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119.
&&
$$
05/
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1146 PM CDT SAT AUG 31 2013
.AVIATION...
IN THE SHORT TERM A CLUSTER OF THUNDERSTORMS OVER SOUTHWEST KANSAS
IS SHOWING SOME TENDENCY TO DRIFT TO THE SOUTH-SOUTHEAST AND MAY
YET END UP IN THE SOUTHEAST PANHANDLE LATER TONIGHT NOT FAR FROM
KCDS. MOST SOLUTIONS DIMINISH THIS ACTIVITY BEFORE REACHING KCDS
WHILE THE LATEST HRRR DOES BRING LIGHTER SHOWERS TO THE AREA AFTER
14Z. WE REMAIN UNCONVINCED SO WILL RETAIN THE MID LEVEL CLOUD
INCREASE AT KCDS AFTER 14Z. OTHERWISE...ARRIVAL OF THE COLD FRONT
BY LATE SUNDAY EVENING OR POSSIBLY DELAYED UNTIL EARLY MONDAY
MORNING SHOULD OFFER AT LEAST SOME OPPORTUNITY FOR THUNDER AT BOTH
KLBB AND KCDS. LATEST SOLUTIONS ARE NOT TERRIBLY EAGER TO MOVE
ACTIVITY IN BEFORE 06Z HOWEVER. WE WILL FOLLOW THIS LACKADAISICAL
APPROACH AND AVOID ADDING IMPLICIT THUNDER TO THE END OF THE 06Z
TAFS JUST YET. RMCQUEEN
&&
.PREV DISCUSSION... /ISSUED 617 PM CDT SAT AUG 31 2013/
AVIATION...
QUIET VFR CONDITIONS IN STORE THIS EVENING AND OVERNIGHT ALTHOUGH
DEVELOPING ISOLATED THUNDERSTORMS OVER THE OKLAHOMA PANHANDLE WILL
HAVE A TENDENCY TO DRIFT SOUTHEAST THROUGH THE EASTERN TEXAS
PANHANDLE OVERNIGHT. ALL SOLUTIONS END ACTIVITY BEFORE REACHING
CHILDRESS...ALTHOUGH A MID LEVEL CLOUD LAYER SEEMS LIKELY TO
SURVIVE INTO KCDS EARLY SUNDAY ALONG WITH PERHAPS A SHIFT TO MORE
VARIABLE SURFACE WINDS. WILL TRY TO ADDRESS THIS WITH MORE
CONFIDENCE FOR THE 06Z TAF. OTHERWISE FOCUS WILL BE TOWARDS
INCREASING THUNDER CHANCES FOR BOTH TAF SITES JUST BEYOND THE END
OF THIS TAF PERIOD WITH APPROACHING WEAK COLD FRONT. RMCQUEEN
PREV DISCUSSION... /ISSUED 245 PM CDT SAT AUG 31 2013/
SHORT TERM...
THE PERSISTENT UPPER RIDGE CENTERED OVER NEW MEXICO WAS PROVIDING
ANOTHER HOT DAY FOR THE SOUTH PLAINS REGION. 19Z TEMPERATURES WERE
RUNNING 1-3 DEGREES ABOVE YESTERDAY AT THIS TIME...VARYING FROM THE
MID-90S ON THE CAPROCK TO AT OR JUST ABOVE 100 ACROSS THE FAR
EASTERN ZONES. THE HIGH SO FAR AT KLBB HAS REACHED 97 DEGREES AND
WILL TOP OUT VERY CLOSE TO THE RECORD OF 100 DEGREES...SET BACK IN
1930. THE STRONG HEATING AND RESULTANT DEEP MIXING WAS NOW
SUPPORTING A FEW HIGH-BASED CUMULUS...THOUGH LIMITED
MOISTURE/INSTABILITY AND WARM MID-LEVELS SHOULD KEEP THESE CLOUDS
LIMITED IN VERTICAL EXTENT. INSTEAD...THE CLOSEST CONVECTION WAS
FIRING ACROSS THE HIGHER TERRAIN OF NEW MEXICO AND COLORADO...WITH
ADDITIONAL DEVELOPMENT POSSIBLE INTO THE NORTHERN TEXAS PANHANDLE
THROUGH WESTERN KANSAS. WEAK STEERING FLOW WILL DIRECT THIS ACTIVITY
SLOWLY SOUTHEASTWARD AND THERE IS AN OUTSIDE CHANCE DECAYING
CONVECTION COULD AFFECT THE NORTHEAST ZONES LATE TONIGHT/EARLY
SUNDAY...THOUGH THE MORE LIKELY OUTCOME IS AN INCREASE IN MID/HIGH
CLOUDINESS.
THE WESTERN RIDGE WILL AMPLIFY OVER THE ROCKIES THROUGH SUNDAY IN
ADVANCE OF AN UPPER LOW OFF THE WEST COAST WHILE A POTENT SHORTWAVE
TROUGH TRANSLATES ACROSS THE UPPER MIDWEST AND INTO THE GREAT LAKES.
THIS MODEST PATTERN ADJUSTMENT WILL ALLOW HEIGHTS TO DECREASE
SLIGHTLY LOCALLY WHILE ALSO CAUSING THE MONSOONAL MOISTURE PLUME TO
BEND SOUTHWARD AND OVER THE AREA LATER IN THE DAY. IN ADDITION...THE
PASSING NORTHERN WAVE WILL PROPEL A COLD FRONT SOUTHWARD THROUGH THE
PLAINS...WITH THE LATEST INDICATIONS THAT THE FRONT WILL BE NEAR OR
INTO OUR NORTHERN ZONES BY LATE SUNDAY AFTERNOON. THE COMBINATION OF
THE FRONT...IMPROVED MID-LEVEL MOISTURE AND PERHAPS WEAK UPPER
SUPPORT WITHIN THE MOISTURE PLUME WILL RESULTING IN INCREASING
SHOWER/STORM CHANCES SUNDAY AFTERNOON INTO SUNDAY NIGHT. BEFORE
00Z...EXPECT THE BEST CHANCE OF CONVECTION TO FAVOR THE NORTHERN
HALF OF THE CWA WHERE SLIGHT CHANCE POPS WERE MAINTAINED. RELATIVELY
HOT AND DRY LOW LEVELS WITH AN INVERTED-V PROFILE COUPLED WITH MOIST
MID/UPPER LEVELS COULD SUPPORT A FEW STRONG WIND GUSTS WITH ANY MORE
INTENSE RAIN CORES. ALSO THE BETTER MOISTURE ALOFT AND RESULTING
INCREASING PWATS /FROM 1 TO 1.5 INCHES/ COUPLED WITH RELATIVELY SLOW
STEERING FLOW COULD SUPPORT DECENT RAINFALL IN A FEW SPOTS...THOUGH
COVERAGE OF CONVECTION MAY BE FAIRLY LIMITED. OTHERWISE...WE WILL
SEE ANOTHER MILD NIGHT TONIGHT...SIMILAR TO THIS MORNING. IT WILL
BE HOT AGAIN SUNDAY BUT INCREASED CLOUD COVER AND LOWERING
THICKNESSES AND HEIGHTS SHOULD KNOCK TEMPERATURES DOWN A TOUCH FROM
TODAY FOR MOST SPOTS.
LONG TERM...
COLD FRONT TO SAG SWD THROUGH THE FCST AREA SUNDAY EXPECTED TO
CONTINUE TO FOCUS THUNDER DEVELOPMENT MAINLY ACROSS THE NRN ZONES
THROUGH THE EVENING. FOCUS LIKELY TO SHIFT SLIGHTLY TO THE ROLLING
PLAINS OVERNIGHT AS UPPER SUPPORT ROTATING AROUND THE SRN ROCKIES
RIDGE STAYS JUST TO THE EAST OF THE FCST AREA. PRE-06Z POPS LOOK
GOOD AS THEY ARE BUT WILL ADJUST 06Z-12Z POPS WITH 30S EAST AND
20S ELSEWHERE.
STILL APPEARS TO BE SOME POTENTIAL FOR SHOWERS AND THUNDER MONDAY
AFTN POSSIBLY LINGERING INTO THE EVENING IN UPSLOPE FLOW REGIME TO
THE NORTH OF THE FRONT WHICH BY THAT TIME LIKELY TO BE DRAPED
ACROSS THE PERMIAN BASIN. THIS SHOULD FOCUS POPS TOWARD THE SWRN
THIRD OF THE FCST AREA...ALTHOUGH CONFIDENCE NOT QUITE HIGH ENOUGH
TO BUMP INTO CHANCE CATEGORY.
REMAINDER OF THE PERIOD LOOKS TO BE DRY WITH TEMPS AT OR JUST
ABOVE SEASONAL NORMS. STILL SOME MODEL DIFFERENCES ON HOW THE
RIDGE OVER THE SRN ROCKIES EXPANDS WITH RECENT TRENDS SUGGEST
EXPANSION MORE NWD RATHER THAN EWD ONTO THE PLAINS. LAST SEVERAL
ITERATIONS OF MEDIUM-RANGE MOS GUIDANCE KEEPS KLBB HIGHS IN A
RANGE FROM 89-92 DEGREES. CURRENT FCST FOR MID TO LATE WEEK IN
GREAT SHAPE WITH FEW CHANGES TO BE MADE.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 64 93 63 87 63 / 10 20 30 20 20
TULIA 67 93 65 87 64 / 0 20 30 20 20
PLAINVIEW 66 94 65 87 64 / 0 20 30 20 20
LEVELLAND 64 97 66 88 66 / 0 10 20 20 20
LUBBOCK 71 97 68 89 66 / 0 10 20 20 20
DENVER CITY 63 95 66 87 64 / 0 10 20 20 20
BROWNFIELD 65 98 68 89 66 / 0 10 20 20 20
CHILDRESS 70 99 69 92 67 / 10 20 30 20 10
SPUR 71 101 70 89 68 / 0 10 20 20 20
ASPERMONT 73 101 71 91 70 / 0 10 20 20 20
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99/05
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
431 AM MDT SUN SEP 1 2013
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 431 AM MDT SUN SEP 1 2013
SUBTLE CHANGES IN THE RIDGE POSITIONING LEADS TO A WESTWARD SHIFT
OF THE DEEP MONSOONAL MOISTURE PLUME...APPEARS FARTHER WEST THAN
WHAT EARLIER MODELS MAY HAVE SHOWN. THE END RESULT IS FOR LESS
CONVECTIVE POTENTIAL ACROSS THE DESERT VALLEYS (FROM SE UTAH INTO
THE GRAND VALLEY) THIS AFTERNOON.
OBJECTIVE ANALYSIS PLACES SUBTROPICAL WAVE WITH DEEP MOIST LAYER
ACROSS SRN NEVADA/SWRN UTAH/NWRN ARIZONA WITH A VORTICITY LOBE
THAT EXTENDS INTO ERN UTAH. RADAR INDICATING SOME SPOTTY SHOWERS
ASSOCIATED WITH THIS ERN UTAH VORT LOBE. RAP AND HRRR MODEL SHOWS
THIS FEATURE LIFTING NORTH OVER THE BOOKCLIFFS BY LATE MORNING...
ENHANCING CONVECTION OVER THE BOOKCLIFFS THAT EXTENDS INTO WRN
COLORADO AS FAR EAST AS INDEPENDENCE PASS.
RAP/NAM/GFS MODELS SHOW RIDGE AXIS POSITIONED JUST WEST OF THE
COLORADO SPINE AND AMPLIFIES AS THE DAY PROGRESSES. DRIER AIR THAT
HAS ADVECTED INTO ERN ARIZONA WILL BE DRAWN NORTHWARD INTO SERN
UTAH THIS MORNING...REACHING NW COLORADO LATE THIS AFTERNOON. THIS
RIBBON OF MID LEVEL DRIER AIR LIMITS CONVECTIVE POTENTIAL ACROSS
THE WRN HALF OF OUR FORECAST AREA. WITH WATER VAPOR LOOP CONFIRMING
THIS TREND...CANNOT JUSTIFY THE CONTINUATION OF THE FLASH FLOOD
WATCH FOR SOUTHEAST UTAH AS DEEP CONVECTIVE TOWERS WILL NOT
SURVIVE THE PROMINENT DRY AIR INTRUSION.
DIFFERENT ENVIRONMENT OVER THE COLORADO CENTRAL MOUNTAINS WITH
MOISTURE IN PLACE WITH SOME SHEAR IN THE 15-20 KT RANGE...CONVECTION
THAT FIRES OVER THE BOOKCLIFFS/ROAN PLATEAU AND FLAT TOP MOUNTAINS
WILL TRACK ESE ACROSS EAGLE AND PITKIN COUNTY AND THIS AREA GETS
THE HIGHEST POP VALUES FOR THIS AFTERNOON.
MODELS REMAIN CONSISTENT LEAVING THE SUB TROPICAL HIGH CIRCULATION
TO SPIN OVER CENTRAL NEW MEXICO THROUGH THE NEXT 24 TO 36 HOURS.
THIS IS WHERE 00Z HAND ANALYSIS HAS IT LOCATED AS WELL...BUT THE
ARIZONA WAVE IS NOT QUITE AS DISTINCT AS 24 HOURS AGO AND A BIT
FARTHER WEST. PWAT LOOKS TO PEAK THROUGH THE DAY ACROSS THE WESTERN
CWA THEN MODELS SHOW A DECLINING TREND THROUGH THE FIRST OF THE
WEEK...BUT STILL ABOVE NORMAL. WITH THE ARIZONA WAVE LIFTING A BIT
FARTHER WEST...MOISTURE LOOKS TO GET SPLIT APART BY THIS EVENING.
SOME LIFTING WITH THE WAVE AND THE REST WRAPPING TOWARD THE
CIRCULATION OVER NEW MEXICO...LEAVING A PSEUDO-DRY SLOT FROM THE 4
CORNERS TO THE NORTHERN MOUNTAINS GOING INTO LABOR DAY. WEAK ASCENT
ASSOCIATED WITH THE WAVE TO THE WEST PUSHES ACROSS NORTHERN UTAH AND
NORTHWEST COLORADO LATE TONIGHT INTO MONDAY MORNING AND MAY HELP
FOCUS CONVECTION DURING THE TIME. MOISTURE ALSO POOLS NEAR THE
SOUTHERN MOUNTAINS SO THESE TWO AREAS SHOULD HAVE THE BEST CHANCES
FOR PRECIPITATION WHILE IN BETWEEN CONFIDENCE IS LOWER. UPPER FLOW
NOT IMPRESSIVE BUT STORM MOTION TO THE NORTH SHOULD BE MORE APPARENT
THAN THE PAST FEW DAYS AND MAY HELP ALLEVIATE SOME OF THE FLOODING
POTENTIAL. LOCALLY HEAVY RAIN STILL POSSIBLE WITH WARM CLOUD RAIN
PROCESSES STILL IN PLACE. EXPECT A BIT MORE SUNSHINE ON MONDAY SO
PUSHED TEMPS UP A FEW DEGREES MANY AREAS CLOSER TO THE MAV GUIDANCE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 431 AM MDT SUN SEP 1 2013
SHOULD BE A BIT OF DOWNTURN TO THE CONVECTION OVER THE NORTHWEST 2/3
OF THE CWA AS THE UPPER HIGH WOBBLES TO THE NORTHWEST. THIS WILL
LEAVE THE 4 CORNERS TO THE CENTRAL MOUNTAINS UNDER THE CIRCULATION
WHERE RESIDUAL MOISTURE WILL BE POOLING. THEREFORE REFOCUSED THE
HIGH POPS TO OUR SOUTHERN CWA TAPERING OFF TO THE NORTH. HIGH NOT
CHANGING MUCH AND SHOULD REMAIN ABOVE NORMAL MOST AREAS.
TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BE ANCHORED OVER THE
COLORADO ROCKIES. MONSOONAL MOISTURE PLUME WILL BE WEST OF OUR
FORECAST AREA. SOME MONSOONAL MOISTURE WILL BE TRAPPED BENEATH THE
HIGH CORE TO ALLOW FOR DAILY SHOWERS AND THUNDERSTORMS. WITH SHEAR
ESSENTIALLY NON EXISTENT...MOST STORMS WILL STAY PUT OVER THE
MOUNTAINS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 431 AM MDT SUN SEP 1 2013
AFTER 18Z...SHOWERS AND THUNDERSTORMS WILL QUICKLY FORM OVER THE
MOUNTAIN AREAS...ESPECIALLY TOWARD THE CONTINENTAL DIVIDE WHERE
MOUNTAIN PEAKS AND RIDGE TOPS WILL BE OBSCURED FROM RAIN SHAFTS
AND LOW CIGS. FARTHER WEST OVER THE LOWER DESERT VALLEYS...AREAL
COVERAGE OF -SHRA/-TSRA WILL BE ISOLATED. SHOWERS AND STORMS
DIMINISH AFTER 02Z.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...PF/15
LONG TERM...15/PF
AVIATION...PF
AREA FORECAST DISCUSSION
NWS ALBANY NY
739 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY
OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 659 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL
BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG
IT HAS SHIFTED DOWN STREAM NEAR CAPE COD. SOME DUAL POL QPE VALUES
OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE SRN
TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX
RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE
MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL
DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND.
THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS
REMAIN MUGGY FOR THE OPENING DAY OF SEPT. A FEW SHOWERS HAVE
POPPED UP OVER SRN DUTCHESS AND LITCHFIELD COUNTIES NEAR THE
DIFFUSE BOUNDARY. A MORE ROBUST THUNDERSTORM CLUSTER CONTINUES
S/SE OF LITCHFIELD CTY. POPS WERE RETRENDED BASED ON THE RADAR TRENDS.
THE MORNING WILL BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE
REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START
OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP
NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY
INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING
BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD
BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST
3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO
INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF
THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL
WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL
/1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE
SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN
THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE
CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S.
NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL
LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED
CONVECTION.
ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY
CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME
SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO
M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE
SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM
THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF
LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE
ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT
THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND
EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN
SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE
DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL
ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL
DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR
LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY
IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS.
LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE
MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN
THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT
ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS
IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME
STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A
BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE
MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY.
PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A
COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM
500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO
25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE
POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT
OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER
LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM
OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET
WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY
HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT
LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE
MONITORED.
OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS
VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND
U60S TO M70S OVER THE HIGH PEAKS.
MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE
PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES
NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND
U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES.
TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE
HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY
COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS
POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS
FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL
HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S
TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS
WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH
SOME U40S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL
REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD.
WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS
IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A
MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS
WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY
THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5
DEGREES BELOW NORMAL.
TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS
FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR
SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP.
HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND
STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW
OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL
BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS
A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW
PASSES TO OUR NORTH.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE
REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND
DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY
DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND
EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED
TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK
WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY
MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER
SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION.
MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR
CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS
LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT
KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU
AND KALB.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY
NIGHT.
OUTLOOK...
MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID
AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO
TUESDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE
RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND
REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT.
EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY.
LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS
OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR
WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW
INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON
SATURDAY AND THIS MORNING.
ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE
POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN
BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS
OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME.
HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING
THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR
DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING
INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF
THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY.
RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE
THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3
INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW
CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE
SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE
TO MONITORED FOR ANY HYDRO ISSUES.
COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID
WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.CLIMATE...
THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW
NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND
PITTSFIELD.
THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR
ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949.
THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES
ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS.
PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013
AND THE SUMMER.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA/FRUGIS
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
701 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY
OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 659 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL
BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG
IT HAS SHIFTED DOWN STREAM NEAR CAPE COD. SOME DUAL POL QPE VALUES
OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE SRN
TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX
RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE
MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL
DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND.
THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS
REMAIN MUGGY FOR THE OPENING DAY OF SEPT. A FEW SHOWERS HAVE
POPPED UP OVER SRN DUTCHESS AND LITCHFIELD COUNTIES NEAR THE
DIFFUSE BOUNDARY. A MORE ROBUST THUNDERSTORM CLUSTER CONTINUES
S/SE OF LITCHFIELD CTY. POPS WERE RETRENDED BASED ON THE RADAR TRENDS.
THE MORNING WILL BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE
REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START
OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP
NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY
INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING
BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD
BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST
3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO
INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF
THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL
WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL
/1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE
SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN
THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE
CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S.
NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL
LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED
CONVECTION.
ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY
CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME
SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO
M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE
SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM
THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF
LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE
ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT
THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND
EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN
SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE
DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL
ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL
DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR
LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY
IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS.
LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE
MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN
THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT
ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS
IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME
STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A
BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE
MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY.
PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A
COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM
500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO
25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE
POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT
OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER
LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM
OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET
WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY
HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT
LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE
MONITORED.
OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS
VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND
U60S TO M70S OVER THE HIGH PEAKS.
MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE
PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES
NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND
U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES.
TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE
HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY
COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS
POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS
FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL
HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S
TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS
WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH
SOME U40S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL
REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD.
WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS
IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A
MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS
WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY
THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5
DEGREES BELOW NORMAL.
TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS
FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR
SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP.
HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND
STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW
OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL
BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS
A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW
PASSES TO OUR NORTH.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE
REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND
DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY
DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND
EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED
TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK
WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY
MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER
SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION.
MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR
CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS
LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT
KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU
AND KALB.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY
NIGHT.
OUTLOOK...
MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID
AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO
TUESDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE
RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND
REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT.
EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY.
LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS
OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR
WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW
INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON
SATURDAY AND THIS MORNING.
ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE
POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN
BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS
OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME.
HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING
THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR
DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING
INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF
THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY.
RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE
THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3
INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW
CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE
SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE
TO MONITORED FOR ANY HYDRO ISSUES.
COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID
WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.CLIMATE...
THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW
NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND
PITTSFIELD.
THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR
ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949.
THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES
ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS.
PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013
AND THE SUMMER.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1108 AM EDT Sun Sep 1 2013
.NEAR TERM [Through Today]...
Despite most of the Global Models indicating that today would be a
Type 4 Sea Breeze Day (Light to Moderate SW winds (5 to 10 kts)
between 1000 and 700 mb, this morning`s TAE sounding is more
indicative of a Type 5. (same direction as a 4 but with stronger
winds (10 to 15 kts). In fact, this is showing up quite well in
this morning`s Radar imagery, as the sea breeze circulation has
become convectively active and penetrated inland much earlier than
at this time on Saturday. Therefore, raised the 12 UTC to 18 UTC
PoPs across N FL into the 30-40 percent range, and for this
afternoon, raised them to about 50 percent across the board except
along the immediate coast and the SE Big Bend. This is also shown
quite well in the Hi-Res HRRR model, which has been performing
exceptionally well this morning.
&&
.SHORT TERM [Tonight Through Tuesday]...
Tonight, the large scale longwave pattern commences rather amplified
highlighted by ridge over Wrn half of Conus, digging trough over Ern
states and high in Atlc off Cntrl FL with ridge Wwd into Cntrl Gulf
of Mex. This keeps local area in relative weakness between these
systems. At surface, high well east of N FL with axis WSW across
Cntrl FL. A cold front was noted from low Srn Ontario SSW thru OH
Valley, Missouri the Nwwd thru KS. Throughout the short term period
NAM and ECMWF slower bringing cold front into our area than GFS
hence keeping more of our area in warm sector and with noticeably
higher POPs and will lean in that direction. Will go 20-30% S-N
mainly eve rain. Lows from around 70 SE counties to low 70s
elsewhere.
On Mon, the upper level trough will continue to dig down the ERN
third of the CONUS reaching N FL with increasing storm motion from
the WSW. By evening, trough also begin to shift Ewd. This will allow
cold front to push into TN by 12z Mon then into N GA during the day
and combined with position of Nrn gulf ridge yields light onshore
flow over local area. These features combined with daytime heating
and the Gulf sea breeze will help to generate SCT convection. Type 6
(SW near 10 mph) sea breeze favors FL but will be disturbed somewhat
by approaching cold front which favor Nrn counties. GFS model PWATS
increase at TLH from 1.8 inches at 12z Mon to 2inches at 00z Tues.
Dothan increases from 1.7 to 1.9 inches same time. Will go 30-50%
S-N POPs. Aftn CAPE impressive but shear negligible. Generally light
steering flow so any cell mergers could yield locally heavy rain,
gusty winds and frequent lightning. Inland highs in low 90s.
By Tues, a series of shortwaves move thru trough further deepening
and shifting it further Ewd with axis along Ern seaboard by sundown
and into Wrn Atlc at night. By sundown, surface low ejects Newd to
Canadian Maritimes with trailing front SSW down Wrn Atlc and across
local region. Some model disagreement with ECMWF bringing front to
Srn most GA/AL while GFS pushes it into N FL with more dry air
filtering in behind over GA/AL. At 18Z Tues GFS PWATS remain around
2 inches along and south of front, but reflect modestly drier air
building in behind front. For example Dothan PWATS drop to 1.78 at
18z Tues. Conversely, ECMWF PWATS remain around 2 inches at Dothan.
Believe GFS too fast with front so will go 30-50% S-N POPS with POPs
highest where NAM/ECMWF place front. Drier air seen between H8 and
H4 may favor downdrafts and gusty winds altho with shear remaining
weak, severe wx not expected. Inland highs 90 to 92 degrees.
&&
.LONG TERM [Tuesday Night through Saturday]...
The upper level ridge centered well to our west may briefly build
into our region by mid week. Otherwise, upper level troughing will
remain the dominate weather feature through the period. A cold front
is expected to push into our CWA Wednesday and possibly stall on
Thursday. Some drier air may filter into the northern zones by
Thursday and Friday. Expect to see typical summertime diurnal
convection largely driven by the sea breeze. Temperatures will stay
near or just above seasonal normals.
&&
.AVIATION...[Through 12z Monday].
While VFR conditions prevail at the 06z TAF issuance, this is
anticipated to be short-lived. Expect LIFR conditions to develop by
sunrise at DHN/ABY with the potential for at least MVFR conditions
elsewhere. One complicating factor to this is remaining mid level
cloudiness across North Florida and offshore convection. TLH/ECP
does have a shot at some early morning storms, though confidence is
too low to include in TAFs at this time. VSBY/CIG restrictions
should end by 14z. Afternoon/evening convection is expected to be
more scattered with VCTS groups indicated at all sites. Storm
development would be later at ABY/DHN.
&&
.MARINE...
Outside of any thunderstorms, and with a weak pressure gradient in
place, very light winds and minimal seas are expected over the
coastal waters through most of the upcoming week.
&&
.FIRE WEATHER...
No concerns.
&&
.HYDROLOGY...
The Middle Suwannee River points from Ellaville through Luraville
will crest over the next 24 hours below action stage as the
Withlacoochee has already crested through the confluence with the
Suwannee. The Alapaha has crested at Jennings and will soon be
cresting near its confluence with the Suwannee near Nobles Ferry.
Modest rises from Branford on through the lower portion of the
Suwannee will continue throughout the weekend and through the latter
part of this coming week from Wilcox on down to the Gulf of Mexico
Entrance. These rises will bring the river points from Wilcox
through Fowler`s Bluff to at least action stage this week. Wilcox at
US19 has the best chance of reaching flood stage late in the week
with a lesser chance further downriver at Fowler`s Bluff.
Outside of the Suwannee River Basin, all remaining rivers in the
forecast area remain in recession. The Aucilla River will continue
to fall slowly and likely be below flood stage by mid week. Releases
from Woodruff will continue to lead to a fall in river levels at
Blountstown with the Apalachicola likely below action stage by the
weekend if the current release schedule holds.
For more information, check out the rivers and lakes tab on our
homepage.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 92 73 92 72 91 / 50 20 40 30 40
Panama City 89 75 86 75 87 / 40 20 30 20 30
Dothan 92 73 91 72 91 / 50 20 50 30 50
Albany 93 73 91 73 91 / 50 30 50 40 50
Valdosta 95 71 92 73 92 / 50 20 40 30 50
Cross City 90 72 90 72 90 / 40 20 30 20 30
Apalachicola 88 75 87 76 87 / 40 20 30 20 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Gould
SHORT TERM...Block
LONG TERM...Barry
AVIATION...Barry/Gould
MARINE...Block/Gould
FIRE WEATHER...Godsey
HYDROLOGY...Godsey
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
950 AM EDT SUN SEP 1 2013
.UPDATE...
NO CHANGES TO THE ONGOING FORECAST THIS MORNING. MORE UNIFORM
SOUTHWEST FLOW IS IN PLACE AS SEEN IN AREA SOUNDINGS. SHOWER AND
THUNDERSTORM COVERAGE IS LESS THAN THIS TIME YESTERDAY
MORNING...BUT STILL SEEING SOME ACTIVITY NEAR BEACHES IN SARASOTA
AND MANATEE COUNTIES. OUR LOCAL WRF DOES NOT SHOW MUCH ACTIVITY
THIS AFTERNOON AND THE HRRR SHOWS SLIGHTLY MORE WITH THE BEST
CHANCES INLAND DUE TO THE SOUTHWEST FLOW. SCATTERED POPS SEEM FINE
AT THIS POINT SO WILL LEAVE THE FORECAST AS IS. STRONG WIND GUSTS
WILL BE A POSSIBILITY WITH SOME OF THE THUNDERSTORMS
TODAY...ESPECIALLY WITH A MID-LEVEL DRY LAYER IN PLACE AS SEEN VIA
THE MORNING SOUNDING.
&&
.AVIATION...
MAINLY VFR CONDITIONS WITH ISOLD-SCT SHRA/TSRA EXPECTED
TO CONTINUE AND DEV ON SEA BREEZE BOUNDARIES WITH BRIEF MVFR
CIGS/VSBY AND GUSTY WINDS POSSIBLE NR TAF SITES UNTIL AROUND 00Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 90 76 90 77 / 30 20 30 20
FMY 91 76 91 76 / 30 20 30 20
GIF 92 75 93 76 / 40 20 40 20
SRQ 89 76 89 75 / 30 20 30 20
BKV 92 69 92 70 / 30 20 30 20
SPG 90 79 90 78 / 30 20 30 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...05/CARLISLE
AVIATION...25/DAVIS
AREA FORECAST DISCUSSION
NWS MIAMI FL
905 AM EDT SUN SEP 1 2013
...FEW STRONG TSTORMS POSSIBLE THIS AFTERNOON WITH FREQUENT
LIGHTNING AND STRONG WIND GUSTS THE MAIN THREATS...
.UPDATE...THE MIAMI SOUNDING THIS MORNING SHOWS SLIGHT DRYING IN
THE LOWER LEVELS BUT STILL SUFFICIENTLY MOIST FOR CONVECTION. GPS
MET PWAT DATA SHOWS HIGHER PWATS OF 1.8 TO 2.0 INCHES FROM NAPLES
TO THE LAKE OKEECHOBEE REGION. SW LOW LEVEL FLOW CONTINUES. HRRR
SHOWS INITIAL CONVECTIVE DEVELOPMENT ACROSS THE EAST COAST METRO
AREAS JUST INLAND FROM THE COAST, THEN BECOMING CONCENTRATED OVER
THE EVERGLADES WHICH SEEMS REASONABLE GIVEN THE FLOW SET UP TODAY.
THEREFORE, HAVE SIDED WITH THIS OUTPUT. INCREASED POPS TO LIKELY
TO INCLUDE ALL OF THE INTERIOR, EVEN THOUGH HRRR ISN`T AS BULLISH
ACROSS THE LAKE REGION. HOWEVER, DID NOT SEE A REASON TO GO LOWER
POPS THERE. EXPANDED CHANCE POPS TO THE GULF COAST AND INTO THE
EAST COAST METRO AREAS WITH SLIGHT CHANCE ONLY ALONG THE IMMEDIATE
ATLANTIC COAST.
A FEW STRONG STORMS ARE POSSIBLE AGAIN THIS AFTERNOON. LAPSE RATES
ARE STEEPER THAN YESTERDAY AND THERE IS SOME DRY AIR ALOFT, SO
THE WIND GUST POTENTIAL IS THERE. WE HAD A FEW CELLS YESTERDAY
PRODUCING DOWNBURST WINDS ESTIMATED AT 50 MPH. THIS AFTERNOON WE
COULD HAVE A FEW CELLS APPROACHING SEVERE LIMITS AND WILL
HIGHLIGHT STRONG GUSTS TO 55 MPH POSSIBLE. ISOLATED STREET
FLOODING IS POSSIBLE AS WELL WHERE STORMS TRAIN. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 647 AM EDT SUN SEP 1 2013/
AVIATION...
HIGH PRESSURE IS BEGINNING TO BUILD IN FROM THE EAST. THIS HAS
CAUSED THE UPPER LEVEL LOW THAT HAS BEEN OVER SOUTH FLORIDA TO
DISSIPATE. THERE ARE SOME ISOLATED SHOWERS AND THUNDERSTORMS
MOVING NORTHWARD, ACROSS CENTRAL FLORIDA. THIS IS LIKELY FROM
OUTFLOW BOUNDARIES ASSOCIATED WITH YESTERDAYS CONVECTION OVER
CUBA. THIS IS EXPECTED TO DIMINISH BY MID MORNING.
FOR THE REST OF THE DAY, THERE IS STILL A SOUTHERLY FLOW OVER THE
AREA. THIS WILL BE INFLUENCED BY THE SEA AND GULF BREEZES EARLY
THIS AFTERNOON. WHEN THE BREEZES DO INITIATE, THEY WILL CAUSE
CONVECTIVE SHOWERS AND SOME THUNDERSTORMS TO DEVELOP AND MOVE BOTH
INLAND AND NORTH. THE FOCUS FOR DEVELOPMENT IS EXPECTED TO SHIFT
TO THE LAKE OKEECHOBEE REGION LATER THIS AFTERNOON. IN THE
MEANTIME, THERE IS UNCERTAINTY AS TO WHERE AND WHEN SHOWERS WILL
CONVERT TO THUNDERSTORMS, SO ONLY VCSH IN THE TAFS AT THIS TIME.
AS MODELS AND OBSERVATIONS MAKE THE PICTURE MORE CLEAR, VCTS MAY
NEED TO BE ADDED TO ANY OR EVEN ALL THE TAF SITES LATER THIS
MORNING.
PREV DISCUSSION... /ISSUED 304 AM EDT SUN SEP 1 2013/
SHORT TERM...
THE OUTFLOW BOUNDARY FROM YESTERDAYS AFTERNOON CONVECTION OVER
CUBA HAS WORKED INTO FLORIDA BAY AND GULF WATERS OF SOUTH FLORIDA
EARLY THIS MORNING. THIS OUTFLOW HAS ALLOWED FOR SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS TO DEVELOP OVER THE GULF WATERS OF
SOUTH FLORIDA EXTENDING EAST INTO THE FLORIDA BAY AND NORTHERN
FLORIDA KEYS. THE SHOWERS AND THUNDERSTORMS WILL DISSIPATE TOWARDS
SUNRISE AS THE OUTFLOW BOUNDARY DISSIPATES...BUT COULD WORK INTO
THE WESTERN AND SOUTHERN COASTAL AREAS OF SOUTH FLORIDA. SO HAVE
PUT IN A 20 PERCENT POPS FOR THESE AREAS THROUGH THE EARLY MORNING
HOURS.
THE UPPER LEVEL LOW THAT HAS BEEN HANGING AROUND SOUTH FLORIDA FOR
THE LAST SEVERAL DAYS WILL SLOWLY MOVE WEST INTO THE GULF WATERS
OF MEXICO TODAY. THIS WILL ALLOW FOR THE WESTERN ATLANTIC RIDGE
TO BUILD INTO SOUTH FLORIDA...AND ALLOW FOR BOTH THE EAST AND WEST
COAST SEA BREEZES TO DEVELOP AND PUSH INLAND ACROSS THE AREA. THE
STEERING FLOW WILL ALSO BE LIGHT FROM THE SOUTH OVER SOUTH FLORIDA
TODAY. SO ISOLATED TO SCATTERED POPS WILL ONCE AGAIN COVER SOUTH
FLORIDA TODAY WITH THE HIGHEST POPS AROUND LAKE OKEECHOBEE.
THE HIGH WILL REMAIN IN PLACE OVER SOUTH FLORIDA ON LABOR DAY
WHICH WILL KEEP A LIGHT SOUTHERLY WIND FLOW OVER SOUTH
FLORIDA...AND ALLOW FOR BOTH THE EAST AND WEST COAST SEA BREEZES
TO DEVELOP AND PUSH INLAND. SO THE POPS FOR LABOR DAY WILL ONCE
AGAIN BE IN THE ISOLATED TO SCATTERED RANGE WITH THE HIGHEST POPS
OVER THE LAKE OKEECHOBEE REGION.
THE HIGH WILL THEN MOVE NORTH INTO CENTRAL FLORIDA FOR THE MIDDLE
OF THIS WEEK. THIS WILL ALLOW FOR THE STEERING FLOW TO BECOME MORE
EASTERLY OVER SOUTH FLORIDA...AND FOCUS THE HIGHEST SCATTERED POPS
OVER THE INTERIOR AND WEST COAST METRO AREAS. THE EAST COAST METRO
AREAS WILL SEE ISOLATED TO LOW END SCATTERED POPS FOR THE MIDDLE
OF THIS WEEK.
THE HIGHS FOR LABOR DAY INTO MIDDLE OF THIS WEEK WILL BE IN THE
LOWER TO MID 90S...EXCEPT AROUND 90 FOR THE EAST COAST METRO
AREAS. THIS WILL ALLOW FOR THE HEAT INDEX READINGS TO BE IN THE
100 TO 105 RANGE OVER MOST OF SOUTH FLORIDA...EXCEPT FOR THE EAST
COAST METRO AREAS WHERE THEY WILL BE AROUND 100.
LONG TERM...
THE HIGH WILL REMAIN OVER CENTRAL FLORIDA FOR END OF THIS WEEK
INTO NEXT WEEKEND. THIS WILL KEEP A EASTERLY WIND FLOW OVER SOUTH
FLORIDA WHICH IN TURN WILL KEEP THE HIGHEST SCATTERED POPS OVER
THE INTERIOR AND WEST COAST METRO AREAS.
THERE IS A TROPICAL WAVE LOCATED JUST EAST OF THE LESSER ANTILLES
THAT WILL MOVE WEST NORTHWEST THROUGH THE WEEK...AND PASS SOUTH OF
THE AREA BY LATE THIS WEEK INTO EARLY NEXT WEEKEND. THIS WAVE
COULD BRING IN SOME DEEPER TROPICAL MOISTURE TO THE AREA DURING
THIS TIME FRAME. SO WILL CONTINUE TO MONITOR THE LATEST MODEL RUNS
ON HOW MUCH MOISTURE WORKS INTO THE AREA WITH THE PASSAGE OF THE
TROPICAL WAVE TO THE SOUTH...AND TO SEE IF THE POPS NEED TO BE
RAISED OVER SOUTH FLORIDA FOR LATE THIS WEEK INTO EARLY NEXT WEEK
IN LATER FORECAST.
MARINE...
THE WINDS WILL BE AROUND 5 KNOTS TODAY INTO LABOR DAY FROM THE SOUTH
TO SOUTHEAST DIRECTION. THE WINDS WILL THEN BECOME MORE EASTERLY
AND SLOWLY INCREASE TO 10 TO 15 KNOTS BY END OF NEXT WEEK. THIS WILL
KEEP THE SEAS AT 2 FEET OR LESS IN BOTH THE ATLANTIC AND GULF
WATERS OF SOUTH FLORIDA THROUGH THE WEEK. SO BOATING CONDITIONS
WILL REMAIN GOOD OVER ALL OF SOUTH FLORIDA WATERS THROUGH THE WEEK
OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 76 90 77 / 30 20 30 20
FORT LAUDERDALE 89 78 90 79 / 20 20 20 20
MIAMI 90 77 91 79 / 40 20 30 20
NAPLES 89 75 90 76 / 50 20 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1041 AM EDT SUN SEP 1 2013
.SYNOPSIS...
WEAK ATLANTIC HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH MONDAY.
A COLD FRONT WILL PUSH THROUGH TUESDAY NIGHT AND WEDNESDAY WITH WEAK
CANADIAN HIGH PRESSURE BUILDING IN FROM THE NORTH. THE HIGH WILL SHIFT
OFF THE COAST LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...THE LACK OF ANY FOG/STRATUS HAS RESULTED IN
CLEAR SKIES ACROSS THE FORECAST AREA. THIS IS ALLOWING TEMPS TO
WARM QUITE RAPIDLY AND SOME AREAS ALREADY IN THE MID 80S. A CU
FIELD SHOULD START DEVELOPING VERY SOON AND WILL ENCOMPASS THE
ENTIRE FORECAST AREA. THE MAIN FORECAST ISSUE FOR TODAY REVOLVES
AROUND THE COVERAGE AND INTENSITY OF DIURNAL CONVECTION. THE
MODELS ACROSS THE SPECTRUM ARE SENDING MIXED SIGNALS. SOME OF THE
HI-RES RUNS SUCH AS THE HRRR SHOW LITTLE MORE THAN ISOLATED WEAK
CONVECTION. ON THE OTHER HAND...THE 12Z NAM HAS COME IN WITH AN
UPWARD TREND IN ITS COVERAGE AND INTENSITY. CURRENTLY...THERE IS A
WELL DEFINED AREA OF NVA ALOFT NOTED ON WATER VAPOR IMAGERY IN
ADVANCE OF THE POTENT SHORTWAVE DRIVING ONGOING CONVECTION OVER
THE TENNESSEE VALLEY. THIS NVA WILL LIKELY HANG ON UNTIL LATE IN
THE AFTERNOON BEFORE THE UPSTREAM ENERGY DISRUPTS IT. ANOTHER
INTERESTING NOTE CONCERNS THE THERMODYNAMIC PARAMETERS FROM THE
MODIFIED 12Z RAOB. USING A TEMP/DP OF SOMETHING AROUND 92/73
RESULTS IN CAPE VALUES AROUND 3000 J/KG...WITH DCAPES GREATER THAN
1000 J/KG THANKS TO A GOOD DEAL OF DRY MID LEVEL AIR. THE MAIN
SOURCE OF LOW LEVEL CONVERGENCE WILL BE THE SEA BREEZE...THE BEST
CONSENSUS SEEMS TO FAVOR ISOLATED TO SCATTERED COVERAGE IN THE
MID/LATE AFTERNOON HOURS. GIVEN THE NEAR STORM ENVIRONMENT...THIS
SEEMS TO BE A DAY WITH LIMITED COVERAGE BUT THE POTENTIAL FOR A
COUPLE STRONG TO SEVERE STORMS DEPENDING ON HOW THE SEA BREEZE AND
OUTFLOW BOUNDARIES INTERACT. AS I SAID EARLIER...TEMPS ARE RISING
QUICKLY AND WITH INCREASED LOW LEVEL THICKNESSES...HIGHS WILL BE
IN THE LOW 90S. SUCH VALUES WILL RUN ABOUT 4-5 DEGREES ABOVE CLIMO
FOR EARLY SEPTEMBER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...MOST AREAS LIKELY TO SEE DRY WEATHER. THE AREA WHERE SOME
ISOLATED NOCTURNAL CONVECTION MAY CROP UP OVERNIGHT COULD BE IN
THE SAME AREAS BORDERING THE MIDLANDS AND PEE DEE WHERE A BIT MORE
MID LEVEL TROFFINESS IS NOTED. COASTAL AREAS WILL KEEP A SLIGHT SW
BREEZE GOING OVERNIGHT AS PATTERN IS FAVORABLE FOR NOCTURNAL
JETTING ALONG THE SOUTH CAROLINA COAST.
A BROAD UPPER TROUGH WILL SIT OVER THE AREA ON MONDAY WITH
SUBSTANTIAL WESTERLY FLOW IN THE LOWER LEVELS. A WELL-DEFINED LEE
TROUGH COMBINED WITH MODEST SURFACE BASED CAPE SHOULD ALLOW FOR
SCATTERED SHOWERS/TSTMS ACROSS INLAND AREAS BY EARLY AFTERNOON.
THE SEABREEZE WILL BE PINNED NEAR THE COAST MUCH OF THE DAY BUT
COULD BECOME A PLAYER LATER IN THE AFTERNOON AS IT STARTS TO NUDGE
INLAND. WESTERLY STEERING FLOW SHOULD BRING INLAND CONVECTION
TOWARD THE COAST AS THE DAY PROGRESSES. OUR BEST COVERAGE LOOKS TO
BE LATE AFTERNOON INTO THE EVENING THOUGH A FEW STORMS COULD
CONTINUE OVERNIGHT GIVEN SUCH A RICH AIRMASS IN PLACE.
THE UPPER TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES ON
TUESDAY WITH A COLD FRONT SLOWLY DROPPING SOUTHEAST TOWARD THE AREA.
DEWPOINTS RISING INTO THE MIDDLE 70S WITH TEMPS PUSHING INTO THE
LOWER 90S WILL YIELD SUBSTANTIAL SURFACE BASED CAPES RANGING FROM
2000 TO 3000 J/KG. ADDITIONALLY SHORTWAVE ENERGY WILL PUSH IN FROM
THE WEST DURING THE AFTERNOON. THUS FAIRLY GOOD COVERAGE OF SHOWERS
AND TSTMS EXPECTED DURING THE DAY TUESDAY...ESPECIALLY LATER IN THE
AFTERNOON ONCE THE CONVECTIVE BOUNDARIES BEGIN INTERACTING WITH THE
SEABREEZE.
SCATTERED CONVECTION MAY CONTINUE INTO TUESDAY NIGHT BEFORE TAPERING
OFF FROM NORTH TO SOUTH. THE FRONT SHOULD PUSH SOUTH OF THE AREA ON
WEDNESDAY WITH SLIGHTLY DRIER AND COOLER CONDITIONS IN ITS WAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
CANADIAN HIGH PRESSURE WILL PREVAIL FOR THE BEGINNING OF THE PERIOD
BUT STEADILY SHIFT EAST WITH A RETURN FLOW SETTING UP ON THE SW
PERIPHERY. MOST AREAS WILL BE DRY WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT. DIURNAL CONVECTION RETURNS TO THE FORECAST FRIDAY THROUGH
SUNDAY AS LOW-LEVEL MOISTURE INCREASES AND ANOTHER UPPER TROUGH SETS
UP SHOP.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
STANDARD LATE SUMMER TAF FARE THIS MORNING. ATMOSPHERIC ENVIRONMENT
FAVORS ISOLATED/SCATTERED SHOWERS AND TSTMS THIS AFTERNOON IN A
MAINLY PULSE-TYPE CONVECTION MODE ANCHORED ON VARIOUS MESOSCALE
BOUNDARIES ACROSS THE COASTAL CORRIDOR. BY EARLY EVENING...THE
CONVECTION SHOULD DIMINISH WILL MAINLY VFR CONDITIONS CONTINUING
TONIGHT. A SW LOW LEVEL JET SHOULD PRECLUDE ANY RISK FOR FOG.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND TSTMS MONDAY
THROUGH TUESDAY NIGHT WITH OCCASIONAL REDUCTIONS IN CEILING AND
VISIBILITY.
&&
.MARINE...
SW FLOW SURGED A BIT OVERNIGHT...INTO THE 15 KT RANGE AT PLACES
SUCH AS FOLLY BEACH AND GRAYS REEF. THIS NOCTURNAL SURGE SHOULD
EBB NEARING DAYBREAK WITH FAIRLY LIGHT WINDS AND SEAS 2 TO 3 FT
THROUGH MUCH OF THE MORNING AND EARLY AFTERNOON HOURS. A STRONGER
NOCTURNAL SURGE IS ANTICIPATED TONIGHT AS THE BOUNDARY LAYER PRES
GRADIENT TIGHTENS. THERE MAY BE A SHORT DURATION WHERE WINDS
APPROACH SMALL CRAFT ADVISORY CONDITIONS IN FREQUENT GUSTS OVER
20 KT BUT WE HAVE CAPPED OFFSHORE FLOW AT 15 TO 20 KT FOR NOW.
SEAS WILL BUILD TO NEAR 4 FT BEYOND 20 NM OFFSHORE.
MONDAY THROUGH FRIDAY...WEATHER CONDITIONS WILL REMAIN BELOW
ADVISORY CRITERIA. SOUTH TO SOUTHWEST WINDS WILL PERSIST UNTIL
TUESDAY AHEAD OF THE COLD FRONT. ONCE THE FRONT PUSHES INTO THE
AREA...WINDS WILL BECOME VARIABLE AND LIGHT...WITH SEAS NO HIGHER
THAN 2-3 FEET.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
954 AM EDT SUN SEP 1 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH
FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD
FRONT WILL MOVE INTO THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NVA COVERS THE REGION THIS MORNING WITH NO ACTIVITY IN THE FA
SO FAR. AN UPSTREAM SHORT WAVE HAS KICKED OFF SOME SHOWER AND
THUNDERSTORM ACTIVITY ACROSS NORTHERN GEORGIA. THE RUC MODEL
MOVES THIS FEATURE INTO UPSTATE SOUTH CAROLINA LATER THIS
AFTERNOON. EXPECT CONDITIONS TO REMAIN QUIET THROUGH THE MORNING
HOURS. THEN AS AFTERNOON LAPSE RATES STEEPEN...MODEL LIS LOWER
TO -6...CAPES GET OVER 2000 J/KG AND PWAT VALUES REMAIN HIGH
AROUND 1.70 INCHES. SO WILL GO WITH A 30 PERCENT CHANCE NORTH
CLOSER TO THE SHORT WAVE AND A 20 PERCENT CHANCE CENTRAL AND
SOUTH PARTS. HIGH TEMPERATURES WITH SOME SUNSHINE SHOULD REACH
90 WITH MANY LOCATIONS GETTING TO ABOUT 91.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE
FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE
INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING
COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS
THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE
PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE
POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND
THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY.
LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT
VERIFICATION AND EXPECTED CLOUDINESS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA
TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY.
DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT
AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE
MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING
FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE
POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE
MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO
PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR
CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY
AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING...BUT MAIN
ACTIVITY IS ACROSS EASTERN TN/NRN GA INTO WRN NC. DIURNALLY DRIVEN
SCATTERED SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON
CONTINUE WELL INTO THE EVENING.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
822 AM EDT SUN SEP 1 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH
FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD
FRONT WILL MOVE INTO THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A MID-LEVEL SHORTWAVE TROUGH WAS HELPING TO SUPPORT ISOLATED
SHOWERS IN THE NORTH PART EARLY THIS MORNING. LIFT ASSOCIATED WITH
THIS FEATURE WILL LIKELY BE EAST OF THE AREA BY AFTERNOON BUT
ANOTHER SHORTWAVE TROUGH MAY MOVE INTO THE AREA LATE THIS
AFTERNOON. THE LATEST RAP SHOWED THE LATER TROUGH REACHING THE
AREA AROUND 21Z. THE HIGH-RESOLUTION MODELS SUGGESTED SCATTERED
COVERAGE AND AN AVERAGE OF THE GFS AND NAM MOS SUPPORTED CHANCE
POPS. THE LIMITED COVERAGE APPEARED REASONABLE BECAUSE OF SOMEWHAT
SHALLOW MOISTURE AND WEAK LIFT. CLOUDINESS SHOULD HELP HOLD DOWN
TEMPERATURES. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE
FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE
INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING
COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS
THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE
PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE
POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND
THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY.
LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT
VERIFICATION AND EXPECTED CLOUDINESS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA
TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY.
DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT
AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE
MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING
FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE
POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE
MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY.
&&
.AVIATION /12Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO
PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR
CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY
AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING...BUT MAIN
ACTIVITY IS ACROSS EASTERN TN/NRN GA INTO WRN NC. DIURNALLY DRIVEN
SCATTERED SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON
CONTINUE WELL INTO THE EVENING.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
746 AM EDT SUN SEP 1 2013
.UPDATE...
HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A
STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS.
&&
.PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY
REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND
SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN
AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC
BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF
FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT
SHOULD BEGIN TO BURN OFF AFTER SUNRISE.
THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/
THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA
DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS
THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE
NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS
UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE
TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR
OUTPUT.
MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS
NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO
FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP
THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL
MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT
HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO
BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS
FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN.
THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP
SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED
DEVELOP...POPS MAY HAVE TO BE RAISED.
FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND
CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW
AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF
SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR
MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION...
LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE
ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING
OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS.
NLISTEMAA
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO...
TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED
COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE
ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE
COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT
AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST
DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE
COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON
THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS
TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING
IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST
MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE
INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS
FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS
DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS
UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE
AREA ON SATURDAY.
AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL
TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A
COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE
NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT
LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY
IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG
SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE
COOLEST DAY OF THE PERIOD.
TDP
&&
.AVIATION...
12Z UPDATE...
ENHANCED FOG CHANNEL SHOWS A STRIP OF 300 TO 500 FOOT CIGS FROM
CANTON TO WEST OF ATL. THIS AREA IS MOVING EAST. DON`T THINK THE
DECK WILL DISSIPATE BEFORE IT REACHES THE AIRPORT...SO WILL
INCLUDE A BKN005 DECK FOR TWO HOURS. THE LOW DECK WILL SCT OUT TO
A CU DECK AROUND 4500 FT LATE THIS MORNING. CONVECTION HAS BEEN
INCREASING ACROSS N GA THIS MORNING. LATEST RUN OF THE HRRR HAS
THIS ACTIVITY COMING THROUGH THE AIRPORT AROUND 18Z. MOVED UP THE
PRECIP TIMING.
//ATL CONFIDENCE...12Z UPDATE...
LOW-MEDIUM CONFIDENCE ON LOW STRATUS CIGS THROUGH 15Z. MEDIUM
CONFIDENCE ON CONVECTION TIMING TODAY. OTHERWISE...HIGH CONFIDENCE
REMANING ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 71 91 72 / 40 40 40 30
ATLANTA 89 72 89 74 / 40 40 40 40
BLAIRSVILLE 83 67 82 68 / 60 50 60 40
CARTERSVILLE 90 71 90 71 / 50 50 40 40
COLUMBUS 92 73 91 74 / 40 30 40 30
GAINESVILLE 88 71 88 73 / 40 50 40 40
MACON 91 72 91 72 / 40 30 40 30
ROME 91 71 92 72 / 60 50 60 40
PEACHTREE CITY 90 70 90 71 / 40 40 40 30
VIDALIA 91 74 91 74 / 40 30 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
623 AM EDT SUN SEP 1 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH
FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD
FRONT WILL MOVE INTO THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A MID-LEVEL SHORTWAVE TROUGH WAS HELPING TO SUPPORT ISOLATED
SHOWERS IN THE NORTH PART EARLY THIS MORNING. LIFT ASSOCIATED WITH
THIS FEATURE WILL LIKELY BE EAST OF THE AREA BY AFTERNOON BUT
ANOTHER SHORTWAVE TROUGH MAY MOVE INTO THE AREA LATE THIS
AFTERNOON. THE LATEST RAP SHOWED THE LATER TROUGH REACHING THE
AREA AROUND 21Z. THE HIGH-RESOLUTION MODELS SUGGESTED SCATTERED
COVERAGE AND AN AVERAGE OF THE GFS AND NAM MOS SUPPORTED CHANCE
POPS. THE LIMITED COVERAGE APPEARED REASONABLE BECAUSE OF SOMEWHAT
SHALLOW MOISTURE AND WEAK LIFT. CLOUDINESS SHOULD HELP HOLD DOWN
TEMPERATURES. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE
FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE
INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING
COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS
THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE
PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE
POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND
THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY.
LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT
VERIFICATION AND EXPECTED CLOUDINESS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA
TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY.
DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT
AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE
MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING
FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE
POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE
MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO
PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR
CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY
AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING BUT ARE NOT
EXPECTED TO AFFECT ANY OF THE TAF SITES. DIURNALLY DRIVEN SCATTERED
SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON CONTINUE
WELL INTO THE EVENING.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
640 AM CDT SUN SEP 1 2013
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION
OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS
EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS
EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN
NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM
PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR
TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH
CENTRAL/SOUTHEAST KS.
THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT
MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL
MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A
RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE
FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD
OF THE FRONT.
COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO
TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY
NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS.
JMC
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL
ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO
THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES
TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN
RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS
VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH.
THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME.
JMC
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 640 AM CDT SUN SEP 1 2013
SCATTERED SHOWERS/THUNDERSTORMS ARE WEAKENING AT 12Z TAF ISSUANCE.
HAVE INCLUDED A BRIEF PERIOD OF -SHRA IN TEMPO GROUPS FOR KRSL AND
KSLN...BUT THE OUTLOOK FOR WIDESPREAD RAIN IS NOT GOOD. THE HRRR
CONTINUES TO DIMINISH THE PRECIPITATION EXPANSE AS THE FRONT MOVES
SOUTHWARD. THUS...IF KHUT/KICT OR KCNU SEES PRECIPITATION AN
AMENDMENT WILL BE NEEDED.
THE FRONT IS JUST BEHIND THE MAIN CONVECTION/SHOWER LINE. WINDS
WILL SWITCH AROUND TO THE NORTH THIS MORNING AND ARE EXPECTED TO
STAY FROM THE NORTH SWITCHING FROM NORTHWEST TO NORTHEAST THROUGH
THE DAY. MID-HIGH CLOUDS WILL PERSIST UNTIL EVENING AS THE FRONT
EXITS TO THE SOUTH. VFR CONDITIONS ARE EXPECTED TO PREVAIL.
BILLINGS
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 94 64 88 64 / 30 10 0 0
HUTCHINSON 92 63 87 63 / 40 10 0 0
NEWTON 92 63 86 62 / 40 10 0 0
ELDORADO 94 64 86 62 / 40 10 0 0
WINFIELD-KWLD 97 65 89 64 / 30 10 0 0
RUSSELL 89 59 87 62 / 40 0 0 0
GREAT BEND 90 62 88 62 / 40 0 0 0
SALINA 91 61 87 62 / 30 0 0 0
MCPHERSON 92 62 87 62 / 30 0 0 0
COFFEYVILLE 97 66 88 64 / 30 10 0 0
CHANUTE 94 64 86 63 / 30 10 0 0
IOLA 94 63 86 62 / 30 10 0 0
PARSONS-KPPF 96 65 87 63 / 30 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1107 AM EDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 1107 AM EDT SUN SEP 1 2013
PLENTIFUL CLOUD COVER OF VARYING HEIGHTS REMAINS IN THE WAKE OF THE
OVERNIGHT AND EARLY MORNING CONVECTION. MOST OF THE SHORT RANGE MODEL
DATA SUGGESTS THAT TODAY WILL BE MUCH LESS ACTIVE THIS AFTERNOON
COMPARED TO YESTERDAY. AS SUCH...HAVE LOWERED POPS TO LOW CHANCE FOR
MOST LOCATIONS AND HAVE ONLY MENTIONED ISOLATED THUNDERSTORM CHANCES
FOR THIS AFTERNOON. CLOUDS WILL GRADUALLY THIN WITH TIME...HOWEVER
DID NUDGE THE HIGH TEMPERATURES DOWN A TAD WITH THE SLOW START THIS
MORNING. CONSEQUENTLY...WENT AHEAD AND TEMPERED THE DIURNAL RISE A
BIT MORE AS WELL.
UPDATE ISSUED AT 750 AM EDT SUN SEP 1 2013
UPDATED THE POP AND WX GRIDS TO REFLECT THE WANING OF THE SHOWERS AND
THUNDERSTORMS ACROSS OUR SOUTH. ALSO FINE TUNED THE NEAR TERM T/TD
GRIDS IN LINE WITH THE OBS AND TRENDS. UPDATES HAVE BEEN SENT TO THE
NDFD AND WEB SERVERS. A FRESHENED SET OF ZONES WILL FOLLOW.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 440 AM EDT SUN SEP 1 2013
07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING INTO THE OHIO
VALLEY FROM THE CENTRAL PLAINS. THIS...IN CONJUNCTION WITH AN MCV...
CONTINUES TO DEVELOP CONVECTION OVER NORTHWESTERN/CENTRAL KENTUCKY
AND DRIFT IT SOUTHEAST INTO THE CUMBERLAND VALLEY. THE RAINS FROM
THIS COULD BE EXCESSIVE OVER PARTS OF WAYNE AND PULASKI COUNTIES
PROMPTING A CONTINUATION OF THE URBAN AND SMALL STREAM FLOOD
ADVISORIES FOR THESE LOCATIONS. IF THE RATES PICK UP IN THE NEXT
ROUND OF CONVECTION WE WILL NEED TO CONSIDER FLOOD WARNINGS...BUT SO
FAR THESE HAVE BEEN LIGHT ENOUGH TO JUST MAINTAIN THE ADVISORIES.
OTHERWISE...MOSTLY CLOUDY SKIES COVER EAST KENTUCKY KEEPING THE FOG
PATCHY AND LIGHT FOR MOST OF THE AREA. THIS IS DESPITE ANOTHER NIGHT
OF MINIMAL DEW POINT DEPRESSIONS WITH TEMPS AND DEWS HOLDING IN THE
UPPER 60S...MUCH OF THIS THE RESULT OF RAIN COOLING EARLIER IN THE
NIGHT.
THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH THE NORTHWEST FLOW REGIME
OVER THE OHIO VALLEY AMPLIFYING IN RESPONSE TO A TROUGH PASSING
THROUGH THE NORTHERN GREAT LAKES TODAY THROUGH MONDAY. THIS TROUGH
WILL SEND PLENTY OF SHORTWAVE ENERGY INTO OUR AREA DURING THIS TIME
WITH THE MESOSCALE DOMINANT FOR SENSIBLE WEATHER. ACCORDINGLY...HAVE
USED THE NAM12 TO GUIDE THIS FORECAST IN COORDINATION WITH THE LATEST
HRRR AND CURRENT LARGER SCALE RADAR TRENDS.
SENSIBLE WEATHER WILL BE A CONTINUATION OF OUR WARM...HUMID...AND
STORMY HOLIDAY WEEKEND. CONVECTION IS ANTICIPATED OVER OUR SOUTHERN
AND WESTERN ZONES EARLY THIS MORNING GRADUALLY FADING OUT BEFORE
ANOTHER ROUND DEVELOPS LATER TODAY. THE STRONGEST STORMS COULD
CONTAIN GUSTY TO DAMAGING WINDS IF THEY GET TALL ENOUGH...BOW OR
MERGE. A VEERING WIND PROFILE AND SOME MID LEVEL SPEED SHEAR ALSO
SUPPORTS THIS CONCERN. OTHERWISE...THE MAIN ISSUE WILL BE EXCESSIVE
RAINFALL AND FLOODING POTENTIAL GIVEN THE RAINS THAT HAVE FALLEN AND
THE THREAT OF ADDITIONAL CONVECTION TRAINING OVER THE SAME AREAS.
CANNOT RULE OUT THE SCATTERED CONVECTION CONTINUING INTO THE NIGHT
WITH LOW PRESSURE IN PLACE OVER THE REGION AND THE APPROACH OF ITS
COLD FRONT...THOUGH THE NAM12 WOULD SUGGEST A LULL UNTIL LATER MONDAY
MORNING. HAVE RAMPED POPS DOWN DURING THIS TIME IN THE GRIDS...BUT
NOT AS MUCH AS THE NAM12 INDICATES. FOR MONDAY...THE SYSTEM/S FRONT
WILL MAKE A MORE DEFINITIVE PUSH INTO OUR AREA AND LIKELY ACTIVATE
THE REMAINING DEEP MOISTURE FOR ONE LAST GOOD ROUND OF CONVECTION
DURING THE DAY. TEMPERATURES WILL BE DEPENDENT ON CONVECTION...
PARTICULARLY FOR HIGHS TODAY AND TOMORROW...BUT IN GENERAL SHOULD BE
ABLE TO REACH THE MID AND UPPER 80S. AGAIN UPPER 60S WILL BE THE RULE
FOR LOWS TONIGHT.
USED THE CONSSHORT AND ITS BC VERSION FOR THE DEW POINT AND WIND
GRIDS...RESPECTIVELY...THROUGH 00Z MONDAY AS A STARTING POINT AND THE
CONSALL THEREAFTER. FOR TEMPS...ADJUSTED THE CONSALL FOR SOME MINOR
TERRAIN ENHANCEMENTS IN THE LOWS TONIGHT AND PCPN CONSIDERATIONS
TODAY AND MONDAY...WITH HOURLY DIURNAL CURVE DERIVED FROM THE NAM12.
AS FOR POPS...ENDED UP CLOSER TO THE WETTER MAV GUIDANCE TODAY...
SIMILAR TO BOTH TONIGHT...AND THEN NEARER THE MET MONDAY.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 AM EDT SUN SEP 1 2013
A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START
OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN.
AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A
COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING
OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN
THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY
TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE
DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS
WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIR MASS...WITH WINDS
AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY
REACH NEAR 80 TUESDAY.
THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST
THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING
TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIR MASS IN
PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE
50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END
OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL
SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT
THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE
CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER
GREAT LAKES SATURDAY. ACCORDING THE ECMWF...WARM AIR PULLING IN
AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO
THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL
CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT
COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL
SOMEWHAT UNKNOWN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 800 AM EDT SUN SEP 1 2013
THE LATEST ROUND OF THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH
THE CUMBERLAND VALLEY. DO STILL EXPECT SOME ADDITIONAL STORMS TO
DEVELOP AND AFFECT THE AREA LATER IN THE DAY BUT HAVE BACKED THESE
OFF TO JUST VCTS MENTIONS GIVEN THE LATEST HRRR AND NAM12 MODEL
GUIDANCE SHOWING MORE OF A DRY PERIOD IN THE WAKE OF THE MORNING
STORMS. THE REDEVELOPMENT WILL LIKEWISE FADE OUT LATER THIS EVENING
AND PATCHY MVFR FOG CAN BE ANTICIPATED AFTER 06Z AT MOST SITES.
WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY
STORMS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...GREIF
LONG TERM...JMW
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
800 AM EDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 750 AM EDT SUN SEP 1 2013
UPDATED THE POP AND WX GRIDS TO REFLECT THE WANING OF THE SHOWERS AND
THUNDERSTORMS ACROSS OUR SOUTH. ALSO FINE TUNED THE NEAR TERM T/TD
GRIDS IN LINE WITH THE OBS AND TRENDS. UPDATES HAVE BEEN SENT TO THE
NDFD AND WEB SERVERS. A FRESHENED SET OF ZONES WILL FOLLOW.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 440 AM EDT SUN SEP 1 2013
07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING INTO THE OHIO
VALLEY FROM THE CENTRAL PLAINS. THIS...IN CONJUNCTION WITH AN MCV...
CONTINUES TO DEVELOP CONVECTION OVER NORTHWESTERN/CENTRAL KENTUCKY
AND DRIFT IT SOUTHEAST INTO THE CUMBERLAND VALLEY. THE RAINS FROM
THIS COULD BE EXCESSIVE OVER PARTS OF WAYNE AND PULASKI COUNTIES
PROMPTING A CONTINUATION OF THE URBAN AND SMALL STREAM FLOOD
ADVISORIES FOR THESE LOCATIONS. IF THE RATES PICK UP IN THE NEXT
ROUND OF CONVECTION WE WILL NEED TO CONSIDER FLOOD WARNINGS...BUT SO
FAR THESE HAVE BEEN LIGHT ENOUGH TO JUST MAINTAIN THE ADVISORIES.
OTHERWISE...MOSTLY CLOUDY SKIES COVER EAST KENTUCKY KEEPING THE FOG
PATCHY AND LIGHT FOR MOST OF THE AREA. THIS IS DESPITE ANOTHER NIGHT
OF MINIMAL DEW POINT DEPRESSIONS WITH TEMPS AND DEWS HOLDING IN THE
UPPER 60S...MUCH OF THIS THE RESULT OF RAIN COOLING EARLIER IN THE
NIGHT.
THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH THE NORTHWEST FLOW REGIME
OVER THE OHIO VALLEY AMPLIFYING IN RESPONSE TO A TROUGH PASSING
THROUGH THE NORTHERN GREAT LAKES TODAY THROUGH MONDAY. THIS TROUGH
WILL SEND PLENTY OF SHORTWAVE ENERGY INTO OUR AREA DURING THIS TIME
WITH THE MESOSCALE DOMINANT FOR SENSIBLE WEATHER. ACCORDINGLY...HAVE
USED THE NAM12 TO GUIDE THIS FORECAST IN COORDINATION WITH THE LATEST
HRRR AND CURRENT LARGER SCALE RADAR TRENDS.
SENSIBLE WEATHER WILL BE A CONTINUATION OF OUR WARM...HUMID...AND
STORMY HOLIDAY WEEKEND. CONVECTION IS ANTICIPATED OVER OUR SOUTHERN
AND WESTERN ZONES EARLY THIS MORNING GRADUALLY FADING OUT BEFORE
ANOTHER ROUND DEVELOPS LATER TODAY. THE STRONGEST STORMS COULD
CONTAIN GUSTY TO DAMAGING WINDS IF THEY GET TALL ENOUGH...BOW OR
MERGE. A VEERING WIND PROFILE AND SOME MID LEVEL SPEED SHEAR ALSO
SUPPORTS THIS CONCERN. OTHERWISE...THE MAIN ISSUE WILL BE EXCESSIVE
RAINFALL AND FLOODING POTENTIAL GIVEN THE RAINS THAT HAVE FALLEN AND
THE THREAT OF ADDITIONAL CONVECTION TRAINING OVER THE SAME AREAS.
CANNOT RULE OUT THE SCATTERED CONVECTION CONTINUING INTO THE NIGHT
WITH LOW PRESSURE IN PLACE OVER THE REGION AND THE APPROACH OF ITS
COLD FRONT...THOUGH THE NAM12 WOULD SUGGEST A LULL UNTIL LATER MONDAY
MORNING. HAVE RAMPED POPS DOWN DURING THIS TIME IN THE GRIDS...BUT
NOT AS MUCH AS THE NAM12 INDICATES. FOR MONDAY...THE SYSTEM/S FRONT
WILL MAKE A MORE DEFINITIVE PUSH INTO OUR AREA AND LIKELY ACTIVATE
THE REMAINING DEEP MOISTURE FOR ONE LAST GOOD ROUND OF CONVECTION
DURING THE DAY. TEMPERATURES WILL BE DEPENDENT ON CONVECTION...
PARTICULARLY FOR HIGHS TODAY AND TOMORROW...BUT IN GENERAL SHOULD BE
ABLE TO REACH THE MID AND UPPER 80S. AGAIN UPPER 60S WILL BE THE RULE
FOR LOWS TONIGHT.
USED THE CONSSHORT AND ITS BC VERSION FOR THE DEWPOINT AND WIND
GRIDS...RESPECTIVELY...THROUGH 00Z MONDAY AS A STARTING POINT AND THE
CONSALL THEREAFTER. FOR TEMPS...ADJUSTED THE CONSALL FOR SOME MINOR
TERRAIN ENHANCEMENTS IN THE LOWS TONIGHT AND PCPN CONSIDERATIONS
TODAY AND MONDAY...WITH HOURLY DIURNAL CURVE DERIVED FROM THE NAM12.
AS FOR POPS...ENDED UP CLOSER TO THE WETTER MAV GUIDANCE TODAY...
SIMILAR TO BOTH TONIGHT...AND THEN NEARER THE MET MONDAY.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 AM EDT SUN SEP 1 2013
A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START
OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN.
AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A
COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING
OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN
THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY
TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE
DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS
WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIRMASS...WITH WINDS
AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY
REACH NEAR 80 TUESDAY.
THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST
THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING
TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIRMASS IN
PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE
50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END
OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL
SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT
THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE
CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER
GREAT LAKES SATURDAY. ACCORDING THE ECWMF...WARM AIR PULLING IN
AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO
THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL
CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT
COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL
SOMEWHAT UNKNOWN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 800 AM EDT SUN SEP 1 2013
THE LATEST ROUND OF THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH
THE CUMBERLAND VALLEY. DO STILL EXPECT SOME ADDITIONAL STORMS TO
DEVELOP AND AFFECT THE AREA LATER IN THE DAY BUT HAVE BACKED THESE
OFF TO JUST VCTS MENTIONS GIVEN THE LATEST HRRR AND NAM12 MODEL
GUIDANCE SHOWING MORE OF A DRY PERIOD IN THE WAKE OF THE MORNING
STORMS. THE REDEVELOPMENT WILL LIKEWISE FADE OUT LATER THIS EVENING
AND PATCHY MVFR FOG CAN BE ANTICIPATED AFTER 06Z AT MOST SITES.
WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY
STORMS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...JMW
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
759 AM EDT SUN SEP 1 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER LAKE SUPERIOR WILL CONTINUE TO DEVELOP
AND MOVE EAST INTO NORTHERN QUEBEC THROUGH EARLY THIS WEEK. A
COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE THROUGH THE MID-
ATLANTIC MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE BUILDS IN FROM
THE NORTHWEST MID TO LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DEBRIS CLOUDS LEFT OVER FROM YDA`S CONVECTION HAS LIMITED EXTENT
OF FOG FORMATION ERY THIS MRNG. SOME PATCHY FOG WILL STILL DEVELOP
THRU DAYBREAK PRIMARILY WITHIN THE SHELTERED VLYS IN CENTRAL
VA...WHERE THE GROUND IS WET FROM YDA`S STORMS.
HIPRES WILL REMAIN PARKED OVER THE WRN ATLANTIC TDA. WITH PERSISTENT
SLY RETURN FLOW OVER THE ERN SEABOARD...THE AIRMASS WILL BE SIMILAR
TO YDA...WARM AND HUMID /DESPITE THE CALENDAR CHANGING FROM
METEOROLOGICAL SUMMER TO FALL/. MAX TEMPS ARE FCST IN MID TO UPPER
80S ALONG AND WEST OF THE BLUE RIDGE AND UPPER 80S TO LOWER 90S
FARTHER EAST. ONE MID-LVL SHORTWAVE TROUGH EXITS THE MID-ATLANTIC
REGION ERY THIS MRNG AS ANOTHER ONE APPROACHES FROM THE OH VLY. THE
REMNANTS OF THIS UPSTREAM MCS WILL PROGRESS EWD THRU THE NRN
MID-ATLANTIC STATES THIS AFTN/EVE. THE CWA WILL HAVE FILTERED
SUNSHINE BEFOREHAND...PROVIDING AN OPPORTUNITY FOR THE ATMOSPHERE TO
DESTABILIZE. SIMILAR TO YDA...SCT SHOWERS AND STORMS SHOULD DEVELOP
OVER THE MTS THIS AFTN AS MODEST LIFT FROM THE SHORTWAVE TROUGH
REACHES THE WRN CWA. WITH THE MID-LVL SUBSIDENCE INVERSION WEAKER
THAN YDA...DEEPER CONVECTION WILL HAVE A BETTER CHANCE TO MAKE IT
EAST OF THE MTS. THE BEST CHANCE FOR SHOWERS AND STORMS APPEAR TO BE
LATE THIS AFTN AND EVE WHEN THE SHORTWAVE TROUGH MOVES THRU. LIMITED
POPS TO CHANCE ACROSS THE ENTIRE CWA THOUGH AS CONVECTION MAY HAVE
DIFFICULTY ORGANIZING DUE TO WEAK SHEAR PROFILES AND LIFT FROM THE
TROUGH. FCST PARAMETERS FROM THE LATEST RAP INDICATE ABOUT 1500-2000
J/KG OF SBCAPE THIS AFTN. CANNOT RULE OUT A COUPLE OF PULSE SEVERE
STORMS ESPECIALLY IN THE MTS GIVEN THE THERMODYNAMIC PROFILES.
ONGOING CONVECTION WILL DIMINISH LATE THIS EVE WITH THE LOSS OF
HEATING AND AS THE SHORTWAVE TROUGH LIFTS NEWD TNGT. DRY SLOT MOVES
IN FROM THE WEST TNGT WHILE THE LLVL FLOW VEERS OUT OF THE WEST.
THIS COULD ALLOW FOR BREAKS IN THE CLOUD COVER AND FOR FOG TO
DEVELOP LATE TNGT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
LABOR DAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN APPROACHING
COLD FRONT FROM THE WEST. A PREFRONTAL TROUGH WILL DEVELOP IN THE
LEE OF THE APPALACHIANS WHICH SHOULD PROVIDE A FOCUS FOR
ISOLATED/SCATTERED AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT. IT
WILL BE A HOT DAY WITH MAX TEMPS IN THE LOW 90S. NAM AND GFS HAVE
SBCAPE AROUND 2500 J/KG WITH BULK SHEAR UNDER 30 KT.
MONDAY NIGHT...LINES OF CONVECTION SHOULD DEVELOP AHEAD OF THE FRONT
AND PUSH EAST THROUGH THE AREA MONDAY EVENING/THROUGH MIDNIGHT.
INCREASED LIKELY POP COVERAGE TO ACROSS THE BALT-WASH METRO FOR THE
EVENING HOURS. THIS IS JUST ABOVE MOST GUIDANCE WHICH IS AROUND 50
POP. WITH AMPLE AVAILABLE ENERGY AND A STRAIGHT-LINE HODOGRAPH...
EXPECT ORGANIZED ACTIVITY. SEVERE THREAT OF LARGE HAIL AND DAMAGING
WIND. SPEAKING OF HAIL...THERE HAVE ONLY BEEN FOUR 1 INCH HAIL
REPORTS SINCE JULY 4. WITH TALL AND FAT CAPE DEPICTED BY THE NAM/GFS
SOUNDINGS...THIS HAIL DEARTH MAY END SOON. FRONT DRIFTS EAST THROUGH
THE NIGHT...MIN TEMPS AROUND 60F IN THE ALLEGHENY HIGHLANDS...CLOSER
TO 70F EAST OF THE BLUE RIDGE PER MAV/MET/SREF BLEND.
TUESDAY...FRONT IS SLOW TO CLEAR THE AREA...MAY STALL OVER SRN MD
CONTINUING A THUNDERSTORM THREAT DOWN THERE. OTW...NRN CONUS (NOT
QUITE CANADIAN...AND THUS NOT AS COOL) HIGH PRESSURE BUILDS IN FROM
THE NW...WITH SUNNY CONDITIONS ON TAP IN WRN PARTS OF THE CWA. MAX
TEMPS GENERALLY 80S AT LOW ELEVATIONS...MID 80S I-95 AND EAST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
DRY CONDITIONS AS HIGH PRESSURE DOMINATES THROUGH FRIDAY. WEAK SFC
TROUGH DROPS SOUTH INTO THE CWA WEDNESDAY NIGHT...PUSHING SOUTH
THURSDAY. PROBABLY JUST SOME MID LEVEL CLOUDS ASSOCIATED WITH THIS
DISTURBANCE. MAX TEMPS CLOSE TO NORMAL...LOW 80S WED-FRI.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
LGT SLY WINDS AND MID TO HI CLOUDS HAVE LIMITED THE COVERAGE OF FOG
ERY THIS MRNG. AS OF 0730Z...ALL TERMINALS ARE VFR. CHO HAS THE BEST
OPPORTUNITY FOR A BRIEF PERIOD OF FOG TOWARD SUNRISE AS THE SOIL IS
SATURATED FROM YDA`S STORMS.
VFR CONDITIONS FOR MUCH OF TDA. SCT SHOWERS AND STORMS ARE EXPECTED
TO INITIALLY DEVELOP OVER THE MTS THIS AFTN AND MOVE EWD TOWARD THE
TERMINALS APPROX BETWEEN 20Z-01Z. TEMPORARY FLGT RESTRICTIONS
POSSIBLE WITH THESE STORMS. PATCHY FOG POSSIBLE AGAIN LATE
TNGT...ESPECIALLY AT THE FOG-PRONE LOCATIONS AT CHO AND MRB.
THUNDERSTORMS INCREASE MONDAY AFTERNOON/CONTINUE THROUGH THE NIGHT
AS A COLD FRONT DRIFTS EAST ACROSS THE TERMINALS. SLY FLOW AROUND 10
KT...THOUGH DAMAGING WINDS ARE POSSIBLE IN THUNDERSTORMS. HIGH
PRESSURE THEN BUILDS TUESDAY AND DOMINATES REST OF THE WORK WEEK
WITH VFR CONDS OUTSIDE OF MORNING FOG.
&&
.MARINE...
SLY WINDS BETWEEN 10-15 KT WILL CONTINUE TDA AND TNGT. SCT STORMS
EXPECTED LATE IN THE DAY. LOCALLY STRONG WINDS WITH THESE STORMS
COULD BECOME HAZARDOUS TO MARINERS AND HOLIDAY BOATERS.
10-15 KT SLY FLOW AHEAD OF A COLD FRONT ACROSS THE WATERS MONDAY.
SPECIAL MARINE WARNINGS POSSIBLE FROM THUNDERSTORMS LATE MONDAY
AFTERNOON THROUGH THE NIGHT. FLOW BECOMES NWLY BY TUESDAY
EVENING...SOME CHANNELING GUSTS MAY APPROACH 18 KT. VARIABLE FLOW
AND HIGH PRESSURE WEDNESDAY THROUGH FRIDAY.
&&
.CLIMATE...
FOR WASHINGTON DC (DCA)...
ALTHOUGH THE AVG TEMP OF 78.3F FOR THE 2013 METEOROLOGICAL SUMMER
WAS SLIGHTLY ABOVE THE 1981-2010 NORMAL...IT WAS CONSIDERABLY COOLER
THAN THE PREVIOUS THREE SUMMERS (WHICH WERE THE THREE WARMEST SUMMERS
ON RECORD FOR DC). BASED ON AVG TEMPS...THIS SUMMER RANKS AS THE
25TH WARMEST SUMMER ON RECORD (TIED WITH 1959). AUGUST 2013 WAS
THE FIRST SUMMER MONTH THAT WAS BELOW NORMAL SINCE JULY 2009.
MIN TEMPS WERE PARTICULARLY WARM. THE MIN TEMP FOR THE SUMMER
AVERAGED 70.8F...WHICH WAS THE TIED WITH 1980 FOR THE 4TH WARMEST
ON RECORD. THE ONLY THREE SUMMER THAT HAD A HIGHER MIN TEMP WAS
2010...2011 AND 2012. THE MIN TEMPERATURE WAS NEVER LOWER THAN
80F IN DC FOR FIVE STRAIGHT DAYS FROM 16-20 JULY...THE FIRST TIME
THIS HAD HAPPENED ON RECORD. THE MOST NUMBER OF DAYS IN A ROW
ABOVE 80F WAS PREVIOUSLY FOUR (21-24 JULY 2011).
A MAX TEMP OF 90F OR WARMER WAS RECORDED 23 DAYS THIS SUMMER.
LOOKING AT THE TEMP RECORDS SINCE 1871...THE AVERAGE NUMBER OF
90-DEGREE DAYS IN A SUMMER IS 26 FOR DC. THE NUMBER OF 90-DEGREE
DAYS IN THE PREVIOUS THREE SUMMERS WAS 52 IN 2010...47 IN 2011
AND 48 IN 2012.
THIS SUMMER FEATURED FIVE DAYS WITH A MAX TEMP OF 95F OR WARMER.
THE AVG NUMBER OF 95-DEGREE DAYS IN A SUMMER IS 6 FOR DC. A RECORD
28 95-DEGREE DAYS OCCURRED IN THE SUMMER OF 2012 WHILE 22 SUCH DAYS
WERE OBSERVED EACH IN 2010 AND 2011.
RAINFALL THIS SUMMER MEASURED 15.74 INCHES...WHICH IS EQUIVALENT TO
50 PERCENT ABOVE THE NORMAL SUMMER RAINFALL FOR DC. IT WAS THE WETTEST
SUMMER SINCE 2006 WHEN 18.61 INCHES WAS RECORDED. THE MAJORITY
(TWO-THIRDS) OF THE RAINFALL THIS SUMMER OCCURRED IN JUNE. JUNE 2013
WAS THE 4TH WETTEST JUNE ON RECORD.
FOR BALTIMORE (BWI)...
THE AVG TEMP OF 75.8F FOR THE 2013 METEOROLOGICAL SUMMER WAS
SLIGHTLY ABOVE THE 1981-2010 NORMAL BUT IT WAS CONSIDERABLY COOLER
THAN THE PREVIOUS THREE SUMMERS (WHICH WERE ALL IN THE TOP TEN
WARMEST SUMMERS ON RECORD). AUGUST 2013 WAS THE FIRST SUMMER MONTH
THAT WAS BELOW NORMAL SINCE JULY 2009.
A MAX TEMP OF 90F OR WARMER WAS RECORDED 19 DAYS THIS SUMMER.
LOOKING AT THE TEMP RECORDS SINCE 1872...THE AVERAGE NUMBER OF
90-DEGREE DAYS IN A SUMMER IS 23 FOR BALTIMORE. THE NUMBER OF
90-DEGREE DAYS DURING THE PREVIOUS THREE SUMMERS WAS 47 IN
2010...37 IN 2011 AND 40 IN 2012.
THIS SUMMER FEATURED ONLY FIVE DAYS WITH MAX TEMP OF 95F OR WARMER.
THE AVG NUMBER OF 95-DEGREE DAYS IN A SUMMER IS 6 FOR BALTIMORE. THE
NUMBER OF 90-DEGREE DAYS DURING THE PREVIOUS THREE SUMMERS WAS 19
IN 2010...16 IN 2011 AND 20 IN 2012.
RAINFALL THIS SUMMER MEASURED 12.16 INCHES...WHICH IS SLIGHTLY
WETTER THAN NORMAL. THE MAJORITY (TWO-THIRDS) OF THE RAINFALL THIS
SUMMER OCCURRED IN JUNE. JUNE 2013 WAS THE 7TH WETTEST JUNE ON
RECORD FOR BALTIMORE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...JRK
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/JRK
MARINE...BAJ/JRK
CLIMATE...JRK
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1032 AM EDT SUN SEP 1 2013
.SYNOPSIS...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE
FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN
RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH
MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED
FOR THE REMAINDER OF THE WEEK.
&&
.UPDATE...
ISSUED AT 1032 AM EDT SUN SEP 1 2013
OVERVIEW: COMPACT SHORT WAVE NOW ADVANCING THROUGH THE WESTERN
U.P./WESTERN LAKE SUPERIOR. ATTENDING SFC LOW LOCATED OVER THE
KEWEENAW PENINSULA AS OF 14Z WITH A COLD FRONT STRETCHING DOWN
THROUGH CENTRAL WISCONSIN. AHEAD OF THE FRONT...12Z GRB/APX
SOUNDINGS REVEAL A FAIRLY DRY LOWER LEVEL AIRMASS IN PLACE AND
SFC BASED CAP UP THROUGH AROUND 800 MB OR SO.
BUT...THERE IS A THIN RIBBON OF MODEST LOW LEVEL MOISTURE (850
THETA-E RIDGE) JUST ALONG THE FRONT IN CENTRAL WISCONSIN...
WRAPPING INTO THE LOW OVER LAKE SUPERIOR. COUPLED WITH COOLING
LOWER LEVELS WITH THE SFC FRONT AND UPPER WAVE...HAS PRODUCED A
NARROW CORRIDOR OF INSTABILITY THAT IS ADVANCING EASTWARD...
EVIDENCED BY THE BKN LINE OF CONVECTION THAT WRAPS ALONG THE
LEADING EDGE OF THE SHORT WAVE.
FORECAST FOR THIS AFTERNOON/EVENING IS COMPLICATED BY A NUMBER OF
FACTORS...INCLUDING...BUT NOT LIMITED TO...MORNING STRATUS AND FOG
THAT WILL MOST CERTAINLY INHIBIT HEATING AND INSTABILITY AT LEAST
FOR AWHILE...AS WELL AS SMALLER SCALE AFFECTS ON THE LOW LEVEL
WIND FIELD INDUCED BY THE LAKES THAT WILL IMPACT FRONTAL POSITION
AND ULTIMATELY LOW LEVEL CONVERGENCE.
THROUGH EARLY AFTERNOON...ONGOING CONVECTION UPSTREAM SHOULD
BASICALLY HIT A "CINH" WALL AS IT TRIES TO ADVANCE INTO THIS
CWA...ESSENTIALLY OUTRUNNING THE FORCING AND AFOREMENTIONED NARROW
CORRIDOR OF INSTABILITY. SO...EXPECT MUCH OF THE CURRENT ACTIVITY
TO FIZZLE. MAIN EXCEPTION...ACROSS UPPER MICHIGAN ALONG THE SHORT
WAVE TRACK WHERE STRONGEST QG-FORCING WILL PROBABLY SUSTAIN
SHOWERS INTO EASTERN UPPER MICHIGAN PAST LUNCH TIME.
THEN...UPSTREAM SFC FRONT WILL TRY TO ADVANCE INTO THE CWA DURING
THE COURSE OF THE AFTERNOON...ALTHOUGH DUE TO LAKE INDUCED CHANGES
IN THE LOW LEVEL WIND FIELD...FRONT AND ASSOCIATED LOW LEVEL
CONVERGENCE WILL LIKELY LOSE IT/S IDENTITY. FRONT MAY "JUMP" INTO
NORTHEAST LOWER MICHIGAN THIS AFTERNOON AIDED BY SE FLOW OF LAKE
HURON. PROVIDED WE CAN EVENTUALLY THIN OUT THE STRATUS AND FOG BY
EARLY-MID AFTERNOON...WE MIGHT BE ABLE TO GENERATE SOME
INSTABILITY AS THE AFOREMENTIONED LOWER LEVEL MOISTURE AXIS NOSES
UP THROUGH NE LOWER MICHIGAN ALONG THE FRONT. WILL SEE HOW THIS
GOES.
BUT AT THIS POINT...THE BEST PRECIP CHANCES THROUGH THIS EVENING
ARE SETTING UP FOR EASTER UPPER MICHIGAN (ALONG THE SHORT WAVE
TRACK)...AS WELL AS NORTHEAST LOWER...THAT IS IF WE CAN MUSTER
SOME HEATING AND DESTABILIZATION. CERTAINLY NOT A RAIN OUT EVENT
BY ANY STRETCH. BUT FOLKS MAKING OUTDOOR HOLIDAY PLANS SHOULD AT
LEAST PLAN FOR THE POTENTIAL FOR A PERIOD OF SHOWERS AND SOME
THUNDER...ESPECIALLY IN EASTERN UPPER AND NORTHEAST LOWER.
SEVERE THREAT...AGAIN INSTABILITY DEPENDENT. WIDESPREAD SEVERE WEATHER
NOT ANTICIPATED. BUT...MID LEVEL FLOW DOES INCREASE TO 35 TO 4O
KNOTS ALONG THE FRONT...LEADING TO SOME BULK SHEAR TO CAPITALIZE
ON. COMBINED WITH BACKED FLOW OFF LAKE HURON...ANY STORMS THAT
MANAGE TO DEVELOP IN NE LOWER MICHIGAN WILL BEAR SCRUTINY.
UPDATE ISSUED AT 703 AM EDT SUN SEP 1 2013
STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE
HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS
COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL
LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM
THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM
NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF
CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE
EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8
WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE
WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS
WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID
MORNING FOR EASTERN UPPER.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 352 AM EDT SUN SEP 1 2013
CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD
FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER
WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK.
MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH
THE FRONT.
CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR
NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD
FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR
NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE
ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS
SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A
WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN
UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL
CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS
WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING
TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR
MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN
SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS
ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK
ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A
MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY
AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER
50S TO LOWER HALF OF THE 60S FOR MOST.
TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS
WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN
UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN
MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO
START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z
BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET
TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S
IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS
LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD
THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL
CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE
WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE
EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN
LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL
HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS.
PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER
CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK
OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG)
FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL
THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS
AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE
FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT
30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT
HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A
LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH
STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT
NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT.
THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY
INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING
COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD
DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY.
LOW TEMPS TO FALL INTO THE 50S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT SUN SEP 1 2013
INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH
MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN
LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT
WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE
IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT
TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP
BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG
TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH
TEMPERATURES MONDAY THEN POPS TO END THE PERIOD.
LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS
AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS.
THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS
NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST.
ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD
COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE
LOWER 60S NORTH TO AROUND 70 SOUTHEAST.
MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED
AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S
TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE
70S.
WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE
AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO
PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM
AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH
HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S.
FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD
INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING
TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME
INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE
AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE
CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS
TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR
NORTH TO AROUND 80 SOUTH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 703 AM EDT SUN SEP 1 2013
IFR STRATUS HAS BECOME FAIRLY WIDESPREAD ACROSS NE LOWER...WHILE
FOG HAS BEEN AN ISSUE AT PLN AND MBL. THE STRATUS WILL LIKELY LIFT
INTO MVFR AND FINALLY INTO VFR BY LATE MORNING. THE FOG LIKELY TO
LIFT SOONER. HIGH CLOUDS WILL STREAM IN FROM THE WEST...IN ADVANCE
OF UPPER LEVEL SHORTWAVE AND CLUSTER OF SHOWERS AND STORMS FROM NE
WISCONSIN/CENTRAL UPPER. THESE ARE NOT LIKELY TO AFFECT NW LOWER
TAF SITES. RATHER...WILL BE AWAITING A COLD FRONT THAT WILL BE
ASSOCIATED WITH A DIFFERENT DEVELOPING BAND OF SHOWERS AND STORMS
WHICH WILL LIKELY BE A SCATTERED BAND OF ACTIVITY ROLLING THROUGH.
WILL JUST TIME THIS WITH A VCTS FOR RIGHT NOW...AS THE BETTER
ACTION WILL LIKELY BE ACROSS EASTERN UPPER. APN TO GET VCTS IN THE
EVENING TONIGHT. ATMOSPHERE IS TOO CAPPED OFF FOR ANY DIURNAL LAKE
BREEZE CONVERGENCE FORCING. WINDS WILL BECOME MORE VARIABLE/LIGHT
AS THE FRONT/LOW PRESSURE SWINGS THROUGH...WITH AN ABRUPT SWITCH
TO OUT OF THE NW LATE IN THE TAF PERIOD...AND INCREASE IN SPEED.
THIS SPEED INCREASE WILL BE FELT MORE TOMORROW DURING THE DAY.
&&
.MARINE...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL
TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE
BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF
SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD
FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE
NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE
GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE
LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS.
THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN
NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER
BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...BA
SYNOPSIS...AS
SHORT TERM...SD
LONG TERM...AS
AVIATION...SD
MARINE...SD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
714 AM EDT SUN SEP 1 2013
.SYNOPSIS...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE
FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN
RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH
MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED
FOR THE REMAINDER OF THE WEEK.
&&
.UPDATE...
ISSUED AT 703 AM EDT SUN SEP 1 2013
STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE
HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS
COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL
LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM
THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM
NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF
CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE
EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8
WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE
WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS
WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID
MORNING FOR EASTERN UPPER.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 352 AM EDT SUN SEP 1 2013
CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD
FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER
WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK.
MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH
THE FRONT.
CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR
NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD
FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR
NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE
ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS
SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A
WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN
UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL
CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS
WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING
TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR
MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN
SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS
ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK
ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A
MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY
AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER
50S TO LOWER HALF OF THE 60S FOR MOST.
TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS
WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN
UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN
MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO
START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z
BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET
TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S
IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS
LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD
THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL
CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE
WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE
EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN
LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL
HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS.
PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER
CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK
OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG)
FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL
THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS
AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE
FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT
30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT
HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A
LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH
STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT
NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT.
THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY
INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING
COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD
DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY.
LOW TEMPS TO FALL INTO THE 50S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT SUN SEP 1 2013
INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH
MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN
LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT
WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE
IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT
TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP
BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG
TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH
TEMPERATURES MONDAY THEN POPS TO END THE PERIOD.
LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS
AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS.
THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS
NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST.
ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD
COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE
LOWER 60S NORTH TO AROUND 70 SOUTHEAST.
MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED
AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S
TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE
70S.
WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE
AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO
PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM
AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH
HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S.
FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD
INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING
TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME
INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE
AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE
CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS
TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR
NORTH TO AROUND 80 SOUTH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 703 AM EDT SUN SEP 1 2013
IFR STRATUS HAS BECOME FAIRLY WIDESPREAD ACROSS NE LOWER...WHILE
FOG HAS BEEN AN ISSUE AT PLN AND MBL. THE STRATUS WILL LIKELY LIFT
INTO MVFR AND FINALLY INTO VFR BY LATE MORNING. THE FOG LIKELY TO
LIFT SOONER. HIGH CLOUDS WILL STREAM IN FROM THE WEST...IN ADVANCE
OF UPPER LEVEL SHORTWAVE AND CLUSTER OF SHOWERS AND STORMS FROM NE
WISCONSIN/CENTRAL UPPER. THESE ARE NOT LIKELY TO AFFECT NW LOWER
TAF SITES. RATHER...WILL BE AWAITING A COLD FRONT THAT WILL BE
ASSOCIATED WITH A DIFFERENT DEVELOPING BAND OF SHOWERS AND STORMS
WHICH WILL LIKELY BE A SCATTERED BAND OF ACTIVITY ROLLING THROUGH.
WILL JUST TIME THIS WITH A VCTS FOR RIGHT NOW...AS THE BETTER
ACTION WILL LIKELY BE ACROSS EASTERN UPPER. APN TO GET VCTS IN THE
EVENING TONIGHT. ATMOSPHERE IS TOO CAPPED OFF FOR ANY DIURNAL LAKE
BREEZE CONVERGENCE FORCING. WINDS WILL BECOME MORE VARIABLE/LIGHT
AS THE FRONT/LOW PRESSURE SWINGS THROUGH...WITH AN ABRUPT SWITCH
TO OUT OF THE NW LATE IN THE TAF PERIOD...AND INCREASE IN SPEED.
THIS SPEED INCREASE WILL BE FELT MORE TOMORROW DURING THE DAY.
&&
.MARINE...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL
TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE
BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF
SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD
FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE
NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE
GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE
LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS.
THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN
NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER
BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...SD
SYNOPSIS...AS
SHORT TERM...SD
LONG TERM...AS
AVIATION...SD
MARINE...SD
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
414 AM PDT SUN SEP 1 2013
.SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY
ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS
OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN
BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE
END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS
VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL
LEVELS BY THE MIDDLE OF THE WEEK.
&&
.UPDATE...IT JUST KEEPS ON GOING. CONVECTION ACROSS MOHAVE COUNTY IS
STILL GOING. EVEN THOUGH CLOUD TOPS HAVE WARMED QUITE A BIT IN THE
LAST HOUR, THE AREAL EXTENT OF ACTIVITY HAS SPREAD OUT MORE THAN
EXPECTED AND WILL LIKELY LAST PAST 12Z. THEREFORE, I WENT AHEAD AND
ADJUSTED POPS TO MATCH THE LATEST RADAR TRENDS, ESPECIALLY ACROSS
EASTERN SAN BERNARDINO COUNTY WHERE LIGHT RAIN WAS COVERING A LARGE
AREA. THE REST OF THE FORECAST STILL LOOKS GOOD.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 304 AM PDT SUN SEP 1 2013
.SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS
MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS
ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT
PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME
HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS
MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN
WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE
COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH
THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE
FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS
CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH
THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF
THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER
TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY
CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH
OF THE NORTHWEST CWFA.
FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST
COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE
THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE
IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO
DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING
INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB
THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K
ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO
MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE
CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A
WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A
POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST
ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH
MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN
KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE
SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS
FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF
TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST
EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW
THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL
REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL
DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY,
AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY
TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO
THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1
FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS.
ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST
THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE
MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE
COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE
TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER
SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH
WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE
SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN
SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS
EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE
WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS
MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE
VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN.
TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT
WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER.
FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW
ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE
ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST
OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER,
IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT
WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE
MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER.
ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS
GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE
THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO
WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL
PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH
FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS
WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED
THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR
A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM
FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A
WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE
FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE
THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA.
GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR
MOST OF THE LONG TERM.
&&
.AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS
AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K
FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP
IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON
TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND
ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY
SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS.
THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH
TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING
MOUNTAINS TOWARD THE AIRPORT COMPLEX.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS
FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY
SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND
NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED
AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY
MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND
WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH
TONIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022.
FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ014.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519>521.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
304 AM PDT SUN SEP 1 2013
.SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY
ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS
OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN
BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE
END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS
VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL
LEVELS BY THE MIDDLE OF THE WEEK.
&&
.SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS
MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS
ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT
PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME
HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS
MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN
WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE
COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH
THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE
FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS
CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH
THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF
THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER
TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY
CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH
OF THE NORTHWEST CWFA.
FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST
COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE
THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE
IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO
DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING
INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB
THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K
ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO
MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE
CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A
WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A
POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST
ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH
MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN
KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE
SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS
FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF
TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST
EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW
THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN
OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED
FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND
THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO
MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS
AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE
BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS.
ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST
THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE
MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE
COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE
TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER
SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH
WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE
SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN
SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS
EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE
WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS
MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE
VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN.
TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT
WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER.
FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW
ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE
ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST
OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER,
IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT
WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE
MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER.
ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS
GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE
THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO
WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL
PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH
FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS
WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED
THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR
A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM
FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A
WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE
FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE
THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA.
GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR
MOST OF THE LONG TERM.
&&
.AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS
AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K
FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP
IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON
TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND
ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY
SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS.
THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH
TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING
MOUNTAINS TOWARD THE AIRPORT COMPLEX.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS
FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY
SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND
NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED
AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY
MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND
WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH
TONIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022.
FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ014.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519>521.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
303 AM PDT SUN SEP 1 2013
.SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY
ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS
OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN
BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE
END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS
VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL
LEVELS BY THE MIDDLE OF THE WEEK.
&&
.SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS
MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS
ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT
PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME
HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS
MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN
WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE
COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH
THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE
FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS
CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH
THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF
THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER
TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY
CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH
OF THE NORTHWEST CWFA.
FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST
COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE
THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE
IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO
DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING
INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB
THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K
ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO
MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE
CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A
WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A
POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST
ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH
MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN
KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE
SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS
FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF
TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST
EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW
THINGS NOT GET GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN
OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED
FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND
THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO
MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS
AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE
BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS.
ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST
THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE
MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE
COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE
TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER
SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH
WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE
SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN
SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS
EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE
WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS
MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE
VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN.
TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT
WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER.
FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW
ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE
ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST
OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER,
IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT
WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE
MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER.
ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS
GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE
THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO
WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL
PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH
FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS
WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED
THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR
A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM
FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A
WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE
FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE
THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA.
GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR
MOST OF THE LONG TERM.
&&
.AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS
AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K
FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP
IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON
TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND
ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY
SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS.
THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH
TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING
MOUNTAINS TOWARD THE AIRPORT COMPLEX.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS
FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY
SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND
NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED
AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY
MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND
WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH
TONIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022.
FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ014.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519>521.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
301 AM PDT SUN SEP 1 2013
.SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY
ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS
OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN
BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE
END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS
VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL
LEVELS BY THE MIDDLE OF THE WEEK.
&&
.SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS
MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS
ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT
PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SO
HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS
MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN
WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE
COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH
THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE
FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS
CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH
THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF
THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER
TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY
CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH
OF THE NORTHWEST CWFA.
FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST
COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE
THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE
IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO
DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING
INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB
THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K
ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO
MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE
CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A
WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A
POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST
ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH
MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN
KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE
SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS
FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF
TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST
EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW
THINGS NOT GET GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN
OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED
FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND
THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO
MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS
AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE
BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS.
ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST
THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE
MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE
COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE
TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER
SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH
WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE
SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN
SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS
EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE
WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS
MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE
VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN.
TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT
WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER.
FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW
ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE
ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST
OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER,
IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT
WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE
MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER.
ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS
GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE
THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO
WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL
PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH
FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS
WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED
THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR
A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM
FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A
WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE
FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE
THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA.
GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR
MOST OF THE LONG TERM.
&&
.AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS
AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K
FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP
IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON
TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND
ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY
SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS.
THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH
TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING
MOUNTAINS TOWARD THE AIRPORT COMPLEX.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS
FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY
SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND
NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED
AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY
MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND
WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH
TONIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022.
FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ014.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519>521.
&&
$$
STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
534 AM MDT SUN SEP 1 2013
.AVIATION...
12Z TAF CYCLE
ISOLD -SHRA AND POSSIBLY -TSRA LINGERING OVER ERN NM BEFORE 18Z
WILL BECOME MORE NUMEROUS AS WELL AS DEVELOP OVER THE WRN HIGH
TERRAIN THEREAFTER AS SURFACE FRONT PUSHES INTO NE NM AND THEN
SOUTH AND WWD...REACHING THE CENTRAL MT CHAIN BY 23Z. ISOLD TO
WDLY SCT MVFR CIGS/VSBY IN SHRA/TSRA TO OCCASIONALLY OBSCURE
HIGHER TERRAIN. CELL MOVEMENT TO BE SLOW AND OCCASIONALLY ERRATIC
DUE TO UPPER HIGH PRESSURE CENTER OVERHEAD.
&&
.PREV DISCUSSION...324 AM MDT SUN SEP 1 2013...
...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR
DAY...
COLD FRONT APPEARS TO BE IN NORTHEASTERN CO
STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY
WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE
LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP
A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET
SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF
OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE
NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER
MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL
BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY
STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE
SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH
ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW
WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE
ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE
BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A
SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE
BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD
HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED.
LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS
EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS
CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY
MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH
SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING
THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR
WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR
DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE
SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40.
WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL
ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE
CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER
BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE
SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL
MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH
SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF
400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL
MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST
TOWARD TX.
TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT
MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH
THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO
CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING
TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT
WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH
WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE
MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED
ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP
SUBTROPICAL MOISTURE INTRUSIONS.
52
&&
.FIRE WEATHER...
UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND
FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING
SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY.
WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS
STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM.
NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST
LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING
ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS
BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON.
NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES
TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO
THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE
RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO
REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS
OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH
RECOVERIES ANTICIPATED.
CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE
CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A
BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO
SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO
POOR VENTILATION LIKELY OVER THE WEST AND NORTH.
A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY
PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING
WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER
HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING
TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES.
AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL
AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY.
WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST.
HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND
CENTRAL NM.
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1013 AM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 1013 AM CDT SUN SEP 1 2013
GIVEN VISIBLE SATELLITE TRENDS THROUGH 15 UTC...INCREASED CLOUD
COVER THROUGH 18 UTC AS THE BREAK UP AND LIFTING OF THE STRATUS
FIELD IS TAKING LONGER THAN PREVIOUSLY FORECAST. THIS IS
CONFIRMED BY THE 12 UTC HRRR LOW LEVEL CLOUD COVER FORECASTS.
OTHERWISE...THE REMAINDER OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 655 AM CDT SUN SEP 1 2013
NO SIGNIFICANT CHANGES MADE TO THE FORECAST. TEMPERATURES ARE
RUNNING A LITTLE WARMER THAN FORECAST AT LOCATIONS UNDER CLOUD
COVER. OTHERWISE...THE FORECAST IS ON TRACK. SATELLITE CONTINUES
TO SHOW CLOUDS PUSHING SOUTHWARD...ALMOST TO BISMARCK AT THIS
TIME. OBS INDICATING CEILINGS WITH THESE CLOUDS AROUND 1000-1500
FEET.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 301 AM CDT SUN SEP 1 2013
DRIER AND COOLER WEATHER WILL HIGHLIGHT THE SHORT TERM FORECAST.
CLOUD COVER EXTENT AND TIMING IS THE MAIN FORECAST CONCERN...AS THIS
WILL IMPACT MAXIMUM TEMPERATURES.
CURRENTLY...HIGH PRESSURE WAS CENTERED OVER SOUTHERN SASKATCHEWAN
WITH THE HIGH AXIS EXTENDING INTO EASTERN MONTANA. AN AREA OF
VFR/MVFR CLOUDS OVER SOUTHERN SASKATCHEWAN AND MANITOBA HAD EDGED
INTO NORTHERN NORTH DAKOTA.
MODELS WERE SUGGESTING THESE CLOUDS WILL MOVE SOUTH ACROSS THE STATE
THIS MORNING. THE HIGH CENTER IS FORECAST TO MOVE SOUTHEAST AND BY
EARLY AFTERNOON BE CENTERED OVER LAKE WINNIPEG INTO THE JAMES/RED
RIVER VALLEYS. NORTHWEST WINDS SHOULD BECOME NORTH...THEN NORTHEAST
INTO THE LATER MORNING HOURS. AS THE HIGH MOVES SOUTHEAST...MODELS
ARE SUGGESTING CLEARING SKIES NEAR THE HIGH CENTER AND ASSOCIATED
CLOUDS REMAINING ON THE WESTERN/SOUTHERN PERIPHERY OF THE HIGH LATER
THIS MORNING AND EARLY AFTERNOON TODAY BEFORE FINALLY DISSIPATING
DURING THE MID-LATE AFTERNOON HOURS. THIS WOULD RESULT IN CLEARING
SKIES OVER THE TURTLE MOUNTAINS...WITH PARTLY TO MOSTLY CLOUDY SKIES
OVER MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THROUGH EARLY
AFTERNOON...THEN SCATTERING OUT DURING THE MID-LATE AFTERNOON. THIS
RESULTS IN AFTERNOON HIGH TEMPERATURES A TAD LOWER THAN THE PREVIOUS
FORECAST. SO...HIGHS FROM THE UPPER 60S IN THE TURTLE MOUNTAINS TO
THE UPPER 70S IN THE SOUTHWEST.
TONIGHT CLEAR SKIES ARE EXPECTED. THE HIGH CENTER IS FORECAST TO
SETTLE OVER MINNESOTA AND THE FAR EASTERN DAKOTAS...WITH RETURN
SOUTHEASTERLY FLOW DEVELOPING OVER THE WESTERN DAKOTAS. THUS LOWER
MINIMUM TEMPERATURES OVER THE JAMES RIVER BASIN - CLEAR SKIES AND
LIGHT WINDS CLOSER TO THE HIGH CENTER - EXPECTING LOWS IN THE MID
40S. LOW TO MID 50S FOR LOWS IN THE WEST FARTHER FROM THE HIGH
CENTER AND WHERE SOUTHEASTERLY WINDS SHOULD KEEP THE LOWER
ATMOSPHERE MIXED SOMEWHAT AND KEEP THE TEMPERATURES FROM LOWERING
INTO THE 40S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 301 AM CDT SUN SEP 1 2013
MAJORITY OF THE EXTENDED PERIOD WILL BE DOMINATED BY STRONG RIDGE
THAT EXTENDS FROM AROUND NEW MEXICO THROUGH ALBERTA/SASKATCHEWAN.
LITTLE CHANGE IN THE PATTERN EXPECTED THROUGH MUCH OF THE WEEK
WITH THE RIDGE LOCATED BETWEEN DEEP UPPER LOW JUST OFF PAC NW
COAST AND TROUGH OVER EASTERN NORTH AMERICA. THIS WILL RESULT IN
MOSTLY DRY CONDITIONS AND TEMPERATURES RUNNING WELL ABOVE NORMAL
WITH HIGHS IN THE 80S TO LOW 90S.
TOWARD THE END OF THE WEEK THE PAC NW LOW BEGINS MOVING INLAND
REACHING MONTANA BY SAT NIGHT PER 00Z GFS/ECMWF. ONE WAVE
DEPICTED BY GFS/ECMWF RIDES RIDGE AND APPROACHES ND BY TUESDAY
RESULTING IN SOME LOW POPS FOR MAINLY WESTERN ND TUE AND TUE
NIGHT. BETTER LIKELIHOOD OF PRECIPITATION BY SATURDAY AS THE UPPER
LOW APPROACHES THE REGION. GFS/ECMWF INDICATE SURFACE LOW IN
VICINITY OF EASTERN MONTANA SATURDAY AFTERNOON LEAVING NORTH
DAKOTA IN WARM SECTOR WITH GFS INDICATING AXIS OF INSTABILITY
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 1013 AM CDT SUN SEP 1 2013
MVFR STRATUS IMPACTING KMOT/KISN/KBIS WILL SLOWLY LIFT AND BREAK
UP THROUGH THE 16-18 UTC TIME FRAME. OTHERWISE...VFR CONDITIONS ARE
FORECAST WITH HIGH PRESSURE IN PLACE.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...JV
LONG TERM...JNS
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
633 AM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 630 AM CDT SUN SEP 1 2013
WE WILL INCREASE CLOUD COVER A BIT THIS MORNING BEFORE CLEARING
MOVES IN FROM THE NW. THE LATEST HRRR ACTUALLY HOLDS ONTO CLOUDS
LONGER TODAY...AND IT COULD BE CLOUDY A BIT LONGER THAN EXPECTED.
FOR NOW WILL BE MORE OPTIMISTIC WITH CLEARING PER THE NAM...BUT
MAY HAVE TO INCREASE CLOUDS TODAY IF THIS TREND CONTINUES.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 310 AM CDT SUN SEP 1 2013
THE MAIN CHALLENGE WILL BE TEMPS WITH DRY WEATHER THROUGH AT
LEAST FRIDAY NIGHT. MODELS ARE IN VERY GOOD OVERALL AGREEMENT AND
NO REAL PREFERENCE THIS MORNING...SO A MODEL BLEND WILL BE
UTILIZED THIS MORNING.
FOR TODAY...A STRONG COLD FRONT HAS USHERED IN UNSEASONABLY COOL
AIR FOR THE FIRST DAY OF SEPTEMBER. IT WILL BE BREEZY THROUGH MID
AFTERNOON WITH ABOUT 25KT TO MIX...AND TEMPS WILL STRUGGLE TO
REACH 70 IN MOST AREAS. THERE WILL BE CLOUDS FOR THE MORNING HOURS
NEAR THE STRONGEST COLD ADVECTION...WITH PLENTIFUL SUNSHINE AND
HIGH CONVECTIVE TEMPS THIS AFTERNOON FOR ALL BUT THE FAR EAST.
FOR TONIGHT...COLD HIGH PRESSURE WILL SETTLE OVER THE REGION...AND
EXPECT LOWS TO FALL INTO THE LOW/MID 40S FOR ALL AREAS. THERE
COULD BE SOME AREAS AROUND 40 WHERE WINDS DECOUPLE QUICKLY THIS
EVENING...MOST LIKELY IN THE NORTHERN RED RIVER VALLEY.
ON MONDAY...TEMPS WILL WARM TO AROUND NORMAL WITH PLENTY OF
SUNSHINE EXPECTED. SFC HIGH PRESSURE WILL MOVE INTO WESTERN
MN...AS RETURN FLOW DEVELOPS OVER THE CENTRAL DAKOTAS.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 310 AM CDT SUN SEP 1 2013
FOR MONDAY NIGHT...IT WILL BE WARMER THAN SUNDAY NIGHT...WITH
SOUTHERLY WINDS INCREASING A BIT LATE IN THE WEST.
FOR TUE...IT WILL WARM ABOVE NORMAL WITH UPPER RIDGING AND 850MB
TEMPS WARMING TO AROUND +20C IN THE WEST.
WEDNESDAY THROUGH SATURDAY NIGHT...TRANQUIL CONDITIONS WILL
CONTINUE. 500 TO 300 HPA RIDGE AXIS REMAINS ACROSS EASTERN MT/
WESTERN DAKOTAS...BUT MID-LEVEL THERMAL AXIS PUSHES EAST A BIT EACH
DAY...SO THAT DAYTIME HIGHS CLIMB BACK INTO THE MID TO UPPER 80S BY
FRIDAY. A DEGREE OR TWO OF COOLING IS POSSIBLE BY SATURDAY AS THE
RIDGE BEGINS TO BREAK-DOWN A BIT IN ADVANCE OF THE NEXT PACIFIC
SHORT-WAVE. DRY CONDITIONS WILL CONTINUE THROUGH SATURDAY GIVEN
PERSISTENT SURFACE HIGH PRESSURE WITH THE NEXT BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS SATURDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 630 AM CDT SUN SEP 1 2013
THE BIGGEST CHALLENGE WILL BE WHEN CLEARING WILL MOVE INTO THE
AREA. EXPECT THE WEST AND NORTH TO CLEAR FIRST...WITH MFVR AND
LOCAL IFR CONDITIONS THIS MORNING PERSISTING IN THE EAST.
NORTHERLY WINDS WILL GUST OVER 20KT IN ALL AREAS THROUGH MID
AFTERNOON BEFORE QUICKLY SUBSIDING AROUND SUNSET.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...DK
SHORT TERM...DK
LONG TERM...DK/ROGERS
AVIATION...DK
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1020 AM EDT SUN SEP 1 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING
MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE
FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE. ADJUSTED POPS WITH SHORT WAVE CROSSING AREA TODAY PER
RADAR...SATELLITE...SURFACE ANALYSIS TREND AND THE HRRR MODEL. LOOKS
LIKE THE HRRR MODEL HAS A VERY GOOD GRASP ON WHAT IS CURRENTLY GOING
ON MESOSCALE WISE PER THE CURRENT TRENDS...WHEREAS OTHER MODELS ARE
ACCOUNTING MORE FOR GENERAL SYNOPTIC SCALE FORCING AND JUST PAINTING
THE ARE WITH QPF. CONVECTION TO OUR SOUTH AND SOUTHWEST...WHICH HAS
KEPT THINGS QUIET AROUND HERE...HAS WEAKENED TO THE POINT WHERE NEW
CONVECTION DEVELOPING OVER SOUTHERN KENTUCKY IS STARTING TO LIFT
NORTHEAST. THIS WILL BRING THE HIGHEST POPS...PER HRRR...INTO THE
MOUNTAINS THROUGH THIS AFTERNOON. ELSEWHERE...LACK OF FOCUSING AND
UNIMPRESSIVE INSTABILITY SUGGESTS THAT EVEN WITH
SUNSHINE...CONVECTION OF A MORE SCATTERED NATURE CAN BE EXPECTED.
THUS...UPDATED TO LIKELY MOUNTAINS AND SCATTERED ELSEWHERE...WITH A
BIT LESS CLOUDS OUTSIDE OF MOUNTAINS. TEMPS STILL LOOK GOOD.
PREVIOUS DISCUSSION...
THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT
AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z
MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH
SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK
HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7
TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY
DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL
SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF
THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN
BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES
TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE
TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE
POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN
ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT.
SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST
OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG
DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON
LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT
OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE
PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION.
WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP
A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST
FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO
AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT
INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS
BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED
TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER
LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET.
INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW
VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT
DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS
THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV
HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN.
ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE
IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS
NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION.
THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS
SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL
EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF
THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT
LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING
REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE
MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH.
TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH
PRESSURE MOVES INTO THE AREA FROM THE NW.
RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE
MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE
WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT
THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE
START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND
DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR
DAY WEEKEND.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH
PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK.
TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL
SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW
TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE
WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED
PRECIPITATION.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
14Z SUNDAY THROUGH 12Z MONDAY...
SHORT WAVE CROSSES AREA TODAY...WITH MOST OF THE CONVECTION IN THE
MOUNTAINS THIS AFTERNOON...SCATTERED AFTERNOON DIURNAL CONVECTION
ELSEWHERE. EXPECT VFR OUTSIDE OF CONVECTION...EXCEPT WILL INCLUDE
PREVAILING MVFR IN CENTRAL AND SOUTHERN MOUNTAINS...ESPECIALLY AT BKW
GIVEN THE SUSTAINED HIGH POPS.
BULK OF CONVECTION WILL DIE DOWN AFTER 03Z...BUT STILL CANNOT
TOTALLY PULL POPS GIVEN THE MAIN SHORT WAVE AND FRONT ARE STILL TO
THE WEST. WILL KEEP ISOLATED. FOG DEVELOPMENT TONIGHT WILL DEPEND ON
THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE
DAY...BUT THINK MOST SITES WILL SEE ENOUGH STARS TO BRING IN MVFR TO
IFR FOG AFTER 05Z...ESPECIALLY ALONG RIVERS AND IN VALLEYS WHERE IT
RAINS TODAY.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND RESTRICTIONS IN CONVECTION DEPENDS
ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG DEVELOPMENT AND DENSITY MAY
VARY FROM CURRENT FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY H H H H M M H H H H H H
HTS CONSISTENCY H H H M M M H H H H H H
BKW CONSISTENCY H H H H M M M M M H H H
EKN CONSISTENCY H H H H M M M M H H H H
PKB CONSISTENCY H H H M M M M H H H H H
CKB CONSISTENCY H H H H M M M M M H H H
AFTER 12Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...JMV/SL
SHORT TERM...TRM
LONG TERM...26
AVIATION...JMV/SL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
624 AM EDT SUN SEP 1 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING
MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE
FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT
AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z
MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH
SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK
HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7
TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY
DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL
SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF
THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN
BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES
TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE
TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE
POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN
ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT.
SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST
OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG
DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON
LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT
OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE
PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION.
WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP
A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST
FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO
AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT
INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS
BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED
TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER
LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET.
INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW
VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT
DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS
THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV
HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN.
ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE
IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS
NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION.
THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS
SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL
EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF
THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT
LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING
REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE
MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH.
TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH
PRESSURE MOVES INTO THE AREA FROM THE NW.
RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE
MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE
WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT
THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE
START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND
DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR
DAY WEEKEND.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH
PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK.
TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL
SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW
TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE
WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED
PRECIPITATION.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12Z SUNDAY THROUGH 12Z MONDAY...
PATCHY MVFR/IFR FOG AT A FEW LOCATIONS...BUT FOR THE MOST
PART...VFR CONDITIONS WITH LIGHT SURFACE WINDS.
CONVECTION WILL INCREASE IN COVERAGE AGAIN AFTER 15Z...AS AN UPPER
DISTURBANCE MOVES EAST THROUGH THE AREA. EXPECT BRIEF MVFR/IFR
CONDITIONS AND GUSTY WINDS IN VICINITY OF STORMS. BULK OF
CONVECTION WILL DIE DOWN AFTER 03Z. FOG DEVELOPMENT TONIGHT WILL
DEPEND ON THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION
DURING THE DAY. BEST LOCATION FOR POTENTIAL FOG DEVELOPMENT WILL
BE EASTERN KENTUCKY AND SOUTHEAST OHIO WHERE BETTER CLEARING IS
EXPECTED...BUT THINKING MOST LOCATIONS WILL REMAIN VFR UNDER
EXTENSIVE CLOUD COVER.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND RESTRICTIONS IN CONVECTION DEPENDS
ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG DEVELOPMENT AND DENSITY MAY
VARY FROM CURRENT FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY H H H H H H H M M H H H
HTS CONSISTENCY H H H H H H M M M H H H
BKW CONSISTENCY M H H H H H H M M M M M
EKN CONSISTENCY M H H H H H H M M M M H
PKB CONSISTENCY H H H H H H M M M M H H
CKB CONSISTENCY H H H H H H H M M M M M
AFTER 12Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...SL
SHORT TERM...TRM
LONG TERM...26
AVIATION...SL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
743 AM EDT SUN SEP 1 2013
.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH
PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO
KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT
CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON
WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE
PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED
INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING
SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST
AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T
HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD
IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG.
AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING
THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST
TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE
INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE
CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE
TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN
MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD
THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA.
ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP
CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE
WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON
ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND
SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH
TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE
FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE
NEEDED.
STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO
YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW
EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING
THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR
TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE
MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED
WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY
FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL.
THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT
POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY
DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE
HIGHEST CHANCES BY MID AFTN.
TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM
NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY
EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL
SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS
OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS
TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES.
SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT
GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS
PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE
HEAVY RAIN AND FLASH FLOODING STILL A THREAT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY
WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING
WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A
MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS
INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP
MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO
ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER
CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS
INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO
PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY.
CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING.
WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE
LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE
ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED.
LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE
NITE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT
THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW
OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF
OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE
STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE
AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP
DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI
WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL
CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING
BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR
NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW
NORMAL AND RISE TO NEAR NORMAL.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AT KCLT...SMALL POSSIBILITY OF A LOW CIG SETTLING IN AROUND DAYBREAK
AND KEEPING A RESTRICTION AFTER 12Z...BUT PRETTY CONFIDENT IN VFR TO
START THE TAF. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND
HAVE THEM IN A TEMPO IN THE EARLY TO MID AFTN...AND A VCSH
SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD.
FOLLOWING THE END OF THE DIURNAL CONVECTION VFR WILL PREVAIL...BUT
GUIDANCE SUGGESTS SOME FOG POSSIBLE LATE TONIGHT ONCE AGAIN. THIS IS
ESPECIALLY LIKELY IF THE FIELD IS HIT BY A SHOWER OR TSTM TODAY.
ELSEWHERE...EARLY MORNING DENSE FOG AND LIFR TO VLIFR CLOUD BASES
EXPECTED ACROSS THE MTNS TO THE WESTERN PIEDMONT EARLY THIS MORNING.
CLIMO INDICATES THAT CONDITIONS MAY NOT IMPROVE TO VFR UNTIL 14Z.
SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST EARLY TODAY
THOUGH CURRENT TRENDS SUGGEST LITTLE DIRECT THREAT TO KAVL OR ANY
OTHER TAF SITE. HOWEVER DIURNAL INSTABILITY WILL GROW QUICKLY ONCE
THE LOW CIGS BURN OFF. KAVL AND THE MTNS WILL LIKELY SEE SHRA/TSRA
THIS AFTN. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL
KEEP TEMPOS DURING THE AFTERNOON AS WELL AS A VCSH/VCTS AS NECESSARY
TO INDICATE LESSER PROBABILITY IN THE SURROUNDING TIMEFRAME. FLOW
REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT
KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR
NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH RESTRICTIONS WILL MAINLY
COME FROM FOG. SITES AFFECTED BY TSRA/SHRA TODAY ARE MOST LIKELY TO
GO DOWN TONIGHT...BUT IN GENERAL MOST SITES HAVE A GOOD SHOT AT
SEEING AT LEAST MVFR VSBY BEFORE DAYBREAK.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN
MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND
WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON
TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER
AIR WILL FOLLOW THE FRONT.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT HIGH 94% HIGH 100% HIGH 100% HIGH 94%
KGSP HIGH 83% HIGH 100% HIGH 100% HIGH 94%
KAVL LOW 59% HIGH 100% HIGH 97% MED 77%
KHKY MED 78% HIGH 100% HIGH 88% HIGH 94%
KGMU MED 79% HIGH 100% HIGH 100% HIGH 91%
KAND MED 75% HIGH 100% HIGH 100% HIGH 86%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...NED/WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
741 AM EDT SUN SEP 1 2013
.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH
PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO
KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT
CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON
WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE
PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED
INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING
SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST
AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T
HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD
IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG.
AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING
THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST
TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE
INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE
CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE
TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN
MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD
THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA.
ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP
CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE
WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON
ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND
SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH
TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE
FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE
NEEDED.
STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO
YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW
EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING
THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR
TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE
MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED
WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY
FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL.
THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT
POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY
DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE
HIGHEST CHANCES BY MID AFTN.
TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM
NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY
EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL
SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS
OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS
TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES.
SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT
GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS
PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE
HEAVY RAIN AND FLASH FLOODING STILL A THREAT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY
WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING
WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A
MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS
INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP
MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO
ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER
CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS
INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO
PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY.
CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING.
WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE
LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE
ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED.
LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE
NITE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT
THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW
OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF
OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE
STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE
AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP
DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI
WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL
CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING
BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR
NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW
NORMAL AND RISE TO NEAR NORMAL.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AT KCLT...SMALL POSSIBILITY OF A LOW CIG SETTLING IN AROUND DAYBREAK
AND KEEPING A RESTRICTION AFTER 12Z...BUT PRETTY CONFIDENT IN VFR TO
START THE TAF. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND
HAVE THEM IN A TEMPO IN THE EARLY TO MID AFTN...AND A VCSH
SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD.
FOLLOWING THE END OF THE DIURNAL CONVECTION VFR WILL PREVAIL...BUT
GUIDANCE SUGGESTS SOME FOG POSSIBLE LATE TONIGHT ONCE AGAIN. THIS IS
ESPECIALLY LIKELY IF THE FIELD IS HIT BY A SHOWER OR TSTM TODAY.
ELSEWHERE...SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST
EARLY TODAY THOUGH CURRENT TRENDS SUGGEST LITTLE DIRECT THREAT TO
KAVL OR ANY OTHER TAF SITE. HOWEVER DIURNAL INSTABILITY WILL GROW
QUICKLY ONCE THE LOW CIGS BURN OFF. KAVL AND THE MTNS WILL LIKELY
SEE SHRA/TSRA THIS AFTN. THUNDER CHANCES A BIT HIGHER TODAY VS
YESTERDAY AND WILL KEEP TEMPOS DURING THE AFTERNOON AS WELL AS A
VCSH/VCTS AS NECESSARY TO INDICATE LESSER PROBABILITY IN THE
SURROUNDING TIMEFRAME. FLOW REMAINS GENERALLY SOUTHWESTERLY /EXCEPT
NW IN UP-VALLEY FLOW AT KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN
THE PATTERN...A SIMILAR NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH
RESTRICTIONS WILL MAINLY COME FROM FOG. SITES AFFECTED BY TSRA/SHRA
TODAY ARE MOST LIKELY TO GO DOWN TONIGHT...BUT IN GENERAL MOST SITES
HAVE A GOOD SHOT AT SEEING AT LEAST MVFR VSBY BEFORE DAYBREAK.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN
MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND
WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON
TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER
AIR WILL FOLLOW THE FRONT.
CONFIDENCE TABLE...
11-17Z 17-23Z 23-05Z 05-11Z
KCLT HIGH 94% HIGH 100% HIGH 100% HIGH 94%
KGSP HIGH 83% HIGH 100% HIGH 100% HIGH 94%
KAVL LOW 59% HIGH 100% HIGH 97% MED 77%
KHKY MED 78% HIGH 100% HIGH 88% HIGH 94%
KGMU MED 79% HIGH 100% HIGH 100% HIGH 91%
KAND MED 75% HIGH 100% HIGH 100% HIGH 86%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...NED/WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1028 AM CDT SUN SEP 1 2013
.UPDATE...
FORT WORTH SOUNDING SHOWS SLIGHT COOLING DURING THE LAST 24 HOURS IN
THE LOWEST 50MB...SO TEMPS SHOULD BE A DEGREE OR SO COOLER THAN
YESTERDAY. HOWEVER HIGHS WILL ONCE AGAIN REACH THE CENTURY MARK
ACROSS MOST OF NORTH TEXAS TODAY AND DID RAISE THEM A BIT FROM THE
PREVIOUS FORECAST IN A FEW LOCATIONS. THE MORNING SOUNDING ALSO
INDICATED HIGHER PRECIPITABLE WATER WITH NOTABLE
COOLING/MOISTENING OCCURRING IN THE MID LEVELS...SUGGESTING WEAK
UPPER LEVEL LIFT IS NOW SPREADING ACROSS NORTH TEXAS. AS HEATING
OCCURS TODAY WOULD EXPECT ISOLATED CONVECTION TO DEVELOP. HI-RES
AND SHORT-TERM GUIDANCE DOES NOT FAVOR ANY PARTICULAR AREA FOR
THIS POP-UP ACTIVITY...AND THUS WILL MENTION ISOLATED
SHOWERS/STORMS EVERYWHERE THIS AFTERNOON WITH A 10 POP SINCE
COVERAGE WILL BE LOW WITHOUT A SURFACE FOCUSING MECHANISM. A COLD
FRONT WILL ARRIVE INTO THE NORTHERN ZONES AFTER 00Z...AND NORTHERN
AND WESTERN ZONES WILL BE THE FAVORED AREA FOR MORE SIGNIFICANT
RAINFALL COVERAGE TONIGHT.
TR.92
&&
.AVIATION...
CONCERNS...ISOLATED TO SCATTERED CONVECTION TONIGHT.
FOR THIS FORECAST CYCLE...HAVE DECIDED TO KEEP ALL TAFS VFR.
HOWEVER...A CONVECTIVE OUTFLOW BOUNDARY...CURRENTLY MOVING THROUGH
CENTRAL OKLAHOMA...IS A CONCERN FOR THE METROPLEX TERMINALS AS IT IS
EXPECTED TO MOVE SOUTH OF THE RED RIVER LATER THIS AFTERNOON. THIS
BOUNDARY SHOULD BE ABLE TO FIRE ISOLATED TO WIDELY SCATTERED
CONVECTION BETWEEN THE RED RIVER AND I-20 MID-LATE AFTERNOON AND
OVERNIGHT PER LAST SEVERAL HI- RES RUNS AS WELL AS THE GFS AND NAM
SERIES. ERGO...HAVE DECIDED TO ADD A PROB30 0205/0209 FOR THIS
POTENTIAL. ALSO...A WIND SHIFT IS INDICATED FOR THE KDFW EXTENDED
FORECAST AFTER 02/15Z. 75
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SUN SEP 1 2013/
NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW
DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN
ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID
ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS
ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST
TOWARD THE UPPER TEXAS COAST.
ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH
OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE
RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109
AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS
EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A
SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER
SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON.
IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP
SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND
TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS
EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER
LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND
TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE
DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM.
SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED
RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z
LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN
THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH
INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS.
MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE
INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES
WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR.
LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH
STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER
DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A
SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS
THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE
SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE
RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING
BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM
CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS.
THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING
WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS.
THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE
DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW
CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE
SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL
COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE
ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST
TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE
CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER
HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO
SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH
POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY
DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD
TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE
AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON
WHERE THIS FEATURE TRACKS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 103 79 98 77 98 / 10 30 20 20 10
WACO, TX 102 77 100 75 98 / 10 20 20 20 20
PARIS, TX 101 74 96 71 96 / 10 30 20 10 10
DENTON, TX 103 77 97 72 97 / 10 40 20 10 10
MCKINNEY, TX 102 76 97 73 98 / 10 30 20 10 10
DALLAS, TX 104 80 98 78 99 / 10 30 20 20 10
TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10
CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10
TEMPLE, TX 100 74 98 74 97 / 10 10 20 20 20
MINERAL WELLS, TX 103 74 95 73 96 / 10 40 30 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
616 AM CDT SUN SEP 1 2013
.AVIATION...
CONCERNS...ISOLATED TO SCATTERED CONVECTION TONIGHT.
FOR THIS FORECAST CYCLE...HAVE DECIDED TO KEEP ALL TAFS VFR.
HOWEVER...A CONVECTIVE OUTFLOW BOUNDARY...CURRENTLY MOVING THROUGH
CENTRAL OKLAHOMA...IS A CONCERN FOR THE METROPLEX TERMINALS AS IT IS
EXPECTED TO MOVE SOUTH OF THE RED RIVER LATER THIS AFTERNOON. THIS
BOUNDARY SHOULD BE ABLE TO FIRE ISOLATED TO WIDELY SCATTERED
CONVECTION BETWEEN THE RED RIVER AND I-20 MID-LATE AFTERNOON AND
OVERNIGHT PER LAST SEVERAL HI- RES RUNS AS WELL AS THE GFS AND NAM
SERIES. ERGO...HAVE DECIDED TO ADD A PROB30 0205/0209 FOR THIS
POTENTIAL. ALSO...A WIND SHIFT IS INDICATED FOR THE KDFW EXTENDED
FORECAST AFTER 02/15Z. 75
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SUN SEP 1 2013/
NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW
DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN
ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID
ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS
ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST
TOWARD THE UPPER TEXAS COAST.
ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH
OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE
RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109
AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS
EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A
SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER
SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON.
IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP
SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND
TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS
EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER
LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND
TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE
DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM.
SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED
RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z
LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN
THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH
INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS.
MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE
INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES
WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR.
LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH
STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER
DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A
SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS
THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE
SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE
RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING
BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM
CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS.
THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING
WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS.
THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE
DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW
CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE
SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL
COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE
ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST
TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE
CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER
HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO
SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH
POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY
DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD
TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE
AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON
WHERE THIS FEATURE TRACKS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 102 79 98 77 98 / 10 40 20 20 10
WACO, TX 101 77 100 75 98 / 5 20 20 20 20
PARIS, TX 101 74 96 71 96 / 20 30 20 10 10
DENTON, TX 103 77 97 72 97 / 20 40 20 10 10
MCKINNEY, TX 102 76 97 73 98 / 20 40 20 10 10
DALLAS, TX 103 80 98 78 99 / 10 40 20 20 10
TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10
CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10
TEMPLE, TX 99 74 98 74 97 / 5 10 20 20 20
MINERAL WELLS, TX 102 74 95 73 96 / 10 40 30 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1004 AM EDT SUN SEP 1 2013
.SYNOPSIS...
UPPER AIR DISTURBANCES WILL MOVE EAST ACROSS THE AREA THROUGH
MONDAY WITH A COLD FRONT MOVING THROUGH BY TUESDAY. THIS FRONT
WILL BRING A DRIER AIRMASS TO THE REGION FOR THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EDT SUNDAY...
BAND OF SHRA/TSRA APPROACHING FROM THE SW WILL BE PUSHING NE INTO
THE FAR WESTERN AREAS AROUND 11 AM...AND THEN LIKELY AID NEW
DEVELOPMENT FARTHER EAST AS INSTABILITY INCREASES PER EARLY
HEATING. EARLY ARRIVAL OF CONVECTION MAY TEND TO LIMIT THE WESTERN
SEVERE THREAT TO SOME DEGREE ESPCLY GIVEN WEAKER WINDS ALOFT OFF
MORNING RAOBS AND DEEP MOISTURE TO 6H. HOWEVER LATEST SHORT RANGE
GUIDANCE REMAINS VARIED ON LATER TRENDS WITH SOME TAKING BETTER
LIFT TO THE SW OF THE AREA WITH THE OLD OUTFLOW UNFOLDING INTO THE
TN VALLEY...WHILE THE HRRR BRINGS A SWATH OF SHRA/TSRA EAST ALONG
THE RESIDUAL VORT AXIS. THIS LOOKS BEST IN LINE WITH THE CURRENT
SCENARIO ESPCLY GIVEN DECENT INSTABILITY OFF MODIFIED RAOBS WEST
AND BETTER HEATING EAST WHERE INITIAL LIFT MAY GET WEAKENED SOME
VIA DOWNSLOPE. THUS HAVE UPPED POPS TO LIKELYS A BIT SOONER FAR
WEST AND EXTENDED EAST TO THE BLUE RIDGE FOR NOW. LEFT CHANCE POPS
IN THE EAST FOR LATER DEVELOPMENT ALTHOUGH MAY NEED TO RAISE LATER
PENDING TRENDS. KEPT HIGHS A LITTLE COOLER...75-80 OVER THE SW
GIVEN EARLIER ARRIVAL OF SHRA...WITH THE EAST PUSHING 90 UNDER
WEAK WESTERLY FLOW AND 85H TEMPS OF +18C.
PREVIOUS VALID DISCUSSION...
HAVE ADJUSTED POPS DOWNWARD EARLY THEN BLEND INTO THE HIGHER POPS
BY MIDDAY OVER THE WEST. THINK ANY OUTFLOW AND HIGHER THETA-E
ACROSS THE MTNS WILL BE ENOUGH TO GET SHRA/TSRA GOING BEFORE NOON
ACROSS SE WV/FAR SW VA. THE 06Z NAM/00Z ECMWF CONTINUE TO
ADVERTISE MORE ORGANZIED CONVECTION MOVING FROM NRN KY INTO ERN
WV/SHENANDOAH VALLEY OF VA THIS AFTERNOON WITH 6Z GFS SINGLING OUT
THE MOUNTAINS OF NC/FAR SW VA. OVERALL KEPT THE LIKELY POPS OVER
THE WEST BY EARLY AFTERNOON TAPERING TO SCATTERED EAST OF THE BLUE
RIDGE. ANY FOG EARLY WILL BURN OFF BY 10 AM.
PREVIOUS DISCUSSION AT 330 AM...
EARLY THIS MORNING...SEEING SOME DENSE FOG ACROSS THE AREA
RESULTING FROM LACK OF LOWER OR MID CLOUDS AND WET GROUND FROM
SATURDAYS RAINS. WILL MAINTAIN SPECIAL WX STATEMENTS FOR
THIS...GIVEN THAT WILL SEE UPSTREAM CLOUDINESS ARRIVING THAT MAY
CAUSE VSBYS TO FLUCTUATE ENOUGH TO KEEP THE COVERAGE OF DENSE FOG
TO A LOCALIZED/PATCHY STATE.
HAVE STAYED CLOSER TO THE 00Z GFS SOLUTION THIS PERIOD AS IT WAS
HANDLING THE UPPER SHORTWAVE ACROSS OHIO AND STORMS OVER KY THIS
MORNING BETTER THAN THE OTHER MODELS. THE LOCAL WRF/HRRR NOT ALL
THAT BAD EITHER BUT APPEAR TO BE OVERDOING PRECIP IN THE EAST AS
RADAR IS CLEAR.
SO FOR TODAY...STILL LOOKS LIKELY THAT SHOWERS AND STORMS WILL
IMPACT THE MOUNTAINS BY MIDDAY...THEN SHIFT ENE ACROSS THE REST OF
THE AREA THRU THE AFTERNOON. THE FLOW WILL BE SW TO WEST WHICH MAY
LIMIT COVERAGE AS WE HEAD DOWNSTREAM OF THE BLUE RIDGE SO LEFT POPS
IN THE FOOTHILLS PIEDMONT AREAS TO 30/4O WHILE GOING LIKELY OR HIGH
CHANCE WEST. PWATS REMAINING HIGH WILL FAVOR HEAVY RAINERS AS STORM
MOTION WILL BE IN THE 10-20 MPH RANGE. SEVERE THREAT WILL BE
ISOLATED TO WIND DAMAGE FROM OUTFLOW/DOWNBURSTS. WILL CONTINUE TO
MENTION THE RAIN/SVR THREAT IN THE HWO.
AS THE WAVE PASSES THIS EVENING...THE CENTRAL/ERN CWA SHOULD SEE
DRYING TREND. NEXT UPSTREAM WAVE WILL BE WEAKENING AS IT MOVES FROM
KY INTO WV OVERNIGHT...BUT ENOUGH THETA-E/HIGH MOISTURE AHEAD OF THE
FRONT TO KEEP HIGHER POPS ACROSS THE SE WV/FAR SW VA AFTER MIDNIGHT
BUT ONLY ABOUT 30/40 POPS.
WITH MAINLY A MIX OF CLOUDS/SUN TODAY WILL STILL SEE WARM TEMPS IN
THE MAV/MET BLEND RANGE FROM UPPER 70S/LOWER 80S MOUNTAINS...TO NEAR
90 PIEDMONT.
TONIGHT...MUGGY CONDITIONS REMAIN WITH TEMPS FALLING INTO THE 60S.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 400 AM EDT SATURDAY...
LOOKING AHEAD TO MONDAY...THE APPALACHIAN CHAIN WILL BE SITUATED AT
THE BASE OF A BROAD UPPER LEVEL TROUGH EXTENDING SOUTHWARD FROM THE
GREAT LAKES...RESULTING IN WESTERLY WINDFLOW ACROSS OUR AREA. ASIDE
FROM A FEW SHOWERS SPILLING OVER OUR FAR WESTERN RIDGELINES...THIS
WEST WIND WILL KEEP A LID ON CONVECTION DURING THE MORNING AND MUCH
OF THE AFTERNOON...BEFORE AN UPPER LEVEL DISTURBANCE APPROACHES
DURING THE EVENING. CLOUD COVER WILL BE SCATTERED EAST OF THE BLUE
RIDGE...MAINLY CONFINED TO MID AND HIGH CLOUDS...AND BELIEVE THE
COMBINATION OF THE DOWNSLOPE WIND AND FILTERED SUNSHINE REACHING THE
SURFACE WILL BE SUFFICIENT TO ALLOW TEMPERATURES TO REACH INTO THE
LOWER 90S IN A FEW AREA OF THE PIEDMONTS.
AS MENTIONED...AN UPPER LEVEL DISTURBANCE IS EXPECTED TO MOVE IN
FROM THE WEST DURING THE EVENING...INCREASING THE COVERAGE OF
SHOWERS AND THUNDERSTORMS ACROSS OUR AREA. INSTABILITY ASSOCIATED
WITH THE DISTURBANCE WILL BE SUFFICIENT TO ALLOW A FEW THUNDERSTORMS
TO BECOME SEVERE...AND EXPECT THE BIGGER THREAT TO COME IN THE FORM
OF DAMAGING WINDS. ATMOSPHERIC MOISTURE WILL REMAIN ABUNDANT...AND
EXPECT WE WILL ALSO SEE A FEW STORMS PRODUCE HEAVY RAIN...AND
POSSIBLY LOCALIZED FLASH FLOODING. THUNDERSTORM ACTIVITY WILL
DECREASE LATE MONDAY NIGHT/EARLY TUESDAY AS THIS DISTURBANCE
MOVES EAST.
MODELS ARE IN DECENT AGREEMENT THAT AN ASSOCIATED COLD FRONT WILL
ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES TUESDAY MORNING...AND
CONTINUE SOUTHEAST...EXITING OUR AREA DURING THE AFTERNOON. THE TRULY
DRIER AIR IN THE LOW LEVELS WILL LAG A FEW HOURS BEHIND THE
FRONT...SO EXPECT WE WILL STILL SEE A COUPLE SHOWERS AND
THUNDERSTORMS SOUTH OF INTERSTATE 81 THROUGH SUNSET...AT WHICH POINT
INSTABILITY WILL DISAPPEAR.
CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...BRINGING WITH IT A HINT OF AUTUMN AS
TEMPERATURES FOR MID WEEK ARE EXPECTED TO BE SLIGHTLY BELOW NORMAL
FOR EARLY SEPTEMBER.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 400 PM EDT SATURDAY...
A STRONG RIDGE CONTINUES IN THE WEST...WHILE AMPLIFYING TROUGH
ANTICIPATED IN THE EAST. HIGH PRESSURE WILL CONTROL OUR WEATHER
PATTERN FOR THURSDAY...RESULTING IN DRY CONDITIONS WITH MOSTLY
CLEAR SKIES...OUTSIDE OF EARLY MORNING FOG. ANOTHER COLD FRONT
WILL DROP SOUTHEAST ACROSS THE REGION FRIDAY WITH SOME MOISTURE
AND INSTABILITY...KEPT THE MENTION OF ISOLATED TO SCATTERED
SHOWERS WITH FRONTAL BOUNDARY. ISOLATED AFTERNOON CONVECTION IS
POSSIBLE SATURDAY AFTERNOON WITH BEST CHANCES ACROSS THE HIGHER
TERRAIN. TEMPERATURES INITIALLY START BELOW NORMAL THEN SLOWLY
MODERATE INTO THE WEEKEND.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
AS OF 735 AM EDT SUNDAY...
LIFR/VLIFR AT LWB/BCB/LYH AND DAN AT 12Z WILL LIFT TO VFR BY 15Z.
WILL SEE SHOWERS/TSRA ARRIVING IN THE BLF/LWB CORRIDOR AROUND
MIDDAY THEN NEXT AT BCB AND ROA BY 19Z. KEPT VCTS AT THESE SITES
BUT NO MENTION OF IT AT DAN/LYH. ANTICIPATING AT LEAST SOME TIME
THIS AFTERNOON THAT THE TAF SITES FROM ROA/BCB TO LWB/BLF WILL SEE
A STORM IMPACT THE TERMINAL BUT NOT ENOUGH CONFIDENCE YET TO PIN
DOWN THE TIMING. OVERALL VFR EXPECTED TODAY WHILE STORMS COULD
DROP HEAVY RAIN/GUSTY WINDS SENDING VSBYS/CIGS TO UNDER VFR.
WEAKENING IN THE CONVECTION THIS EVENING WITH FOG AGAIN FORMING
OVERNIGHT AT MOST SITES...WITH FOG BECOMING DENSE AT LWB/BCB...AND
MAYBE LYH IF IT RAINS NEARBY.
TRUE FRONT EXPECTED TO NOT MOVE INTO AND THRU THE CWA UNTIL
TUESDAY MORNING...SO MONDAY WILL BE ANOTHER DAY OF SCATTERED
CONVECTION WITH THE LAST IN THE UPPER LEVEL SHORTWAVES MOVING
ACROSS INTERACTING WITH HUMID SFC CONDITIONS AND LOW LVL
CONVERGENCE. ANTICIPATE MORE FOG TUESDAY MORNING WITH DRIER AIR
NOSING IN DURING THE DAY TUESDAY. MOSTLY VFR WX EXPECTED THROUGH
LATE WEEK OUTSIDE OF ANY OVERNIGHT FOG.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS/WP
NEAR TERM...JH/WP
SHORT TERM...NF
LONG TERM...KK
AVIATION...DS/RCS/WP
AREA FORECAST DISCUSSION...CORRECTED
NWS PHOENIX AZ
310 PM MST SUN SEP 1 2013
CORRECTED TYPO
.SYNOPSIS...
A DECLINE IN MONSOON MOISTURE WILL LEAD TO LOWER HUMIDITY AND
SLIGHTLY WARMER TEMPERATURES THAN WHAT HAS BEEN EXPERIENCED IN
RECENT DAYS. THERE WILL BE ENOUGH LINGERING MOISTURE AND WEATHER
DISTURBANCES TO KEEP AT LEAST A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ACROSS THE REGION THROUGH WEDNESDAY. ANTICIPATE A SLOW
EASTWARD RETREAT OF STORM CHANCES THE REST OF THE WEEK.
&&
.DISCUSSION...
REST OF TODAY THROUGH MONDAY...
WITH LESS MORNING CLOUDINESS AND SOMEWHAT LOWER SURFACE DEW
POINTS...24 HOUR TEMP TRENDS EARLY THIS AFTERNOON ARE RUNNING AT
LEAST A FEW DEGREES WARMER OVER SOUTH CENTRAL ARIZONA...LITTLE
CHANGE FURTHER WEST WHERE THERE WAS MORE STORM ACTIVITY LAST NIGHT.
SATELLITE AND RADAR IMAGERY AS OF 21Z SHOWS MEAGER STORM DEVELOPMENT
OVER EASTERN ARIZONA WITH ONLY ACTIVITY IN SANTA CRUZ COUNTY. THE
NORTHWEST QUARTER OF ARIZONA HAS HAD MOST OF THE STORMS SO FAR. IN
OUR FORECAST AREA...LA PAZ COUNTY HAS HAD A STRAY THUNDERSTORM SO
FAR. CUMULUS DEVELOPMENT OVER ZONE 24 INDICATES THAT THERE IS STILL
SOME MOISTURE TO WORK WITH. GPS IPW DATA TRENDS ARE A MIXED BAG WITH
SOME STATIONS SHOWING SOME ADDITIONAL DRYING SINCE THIS MORNING AND
SOME OTHERS WITH SOME REVERSAL OF THE DRYING TREND. BUT
OVERALL...NOT A LOT OF CHANGE FROM THE MORNING. HRRR MODEL CONTINUES
TO SHOW ONLY ISOLATED STORMS OVER SOUTH-CENTRAL ARIZONA THROUGH THIS
EVENING...MAINLY OVER ZONE 24...WITH BETTER COVERAGE FURTHER
WEST...MAINLY LA PAZ AND EASTERN RIVERSIDE COUNTIES. LATEST RUC/RAP
SHOWS A SIMILAR PATTERN BUT IS NOT AS GENEROUS OVER LA PAZ AND
EASTERN RIVERSIDE. THE NMM6KM AND LOCAL WRF ARE EVEN LESS GENEROUS
WITH STORM ACTIVITY. HOWEVER...THE AFTERNOON IS STILL YOUNG AND THE
INFLUENCE OF STORMS OVER NORTHERN SONORA REMAINS TO BE SEEN. NAM
APPEARS TO HAVE HAD A BETTER HANDLE ON THE MOISTURE TRENDS FOR TODAY
THAN THE GFS AS DEW POINTS HAVENT DROPPED AS MUCH. GFS HAD ALSO
UNDERINITIALIZED THE LOWER LEVEL MOISTURE OVER PORTIONS OF SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA. MADE SOME MINOR UPWARD TWEAKS TO
THE POPS FOR THIS EVENING DUE TO LINGERING MOISTURE AVAILABILITY AND
MORE UNSTABLE BOUNDARY LAYERS. ANTICIPATE SOME ADDITIONAL MOISTURE
DECLINE TOMORROW AND THUS SOMEWHAT LOWER POPS...BUT NOT ENOUGH TO
DROP THEM ALTOGETHER.
TUESDAY...
TROPICAL STORM KIKO OFF THE SOUTHERN BAJA COAST WILL NOT
BE SENDING A BIG SLUG OF TROPICAL MOISTURE INTO OUR FORECAST AREA
LIKE JULIETTE DID. HOWEVER...THERE IS AN INVERTED TROUGH/SHORT WAVE
ADVERTISED TO MOVE ACROSS NORTHERN MEXICO AND INTO SOUTHEAST ARIZONA
TUESDAY NIGHT. THIS WILL LEAD TO SOME UPPER LEVEL DIVERGENCE WHICH
WILL BE MORE CONDUCIVE TO STORM DEVELOPMENT. HOWEVER...THE GFS
DOESNT DEPICT A SUBSTANTIAL INCREASE IN MOISTURE WITH IT. IT ALSO IS
UNCHARACTERISTICALLY MODEST WITH THE DIVERGENCE FIELDS. ECMWF AND
NAM ARE A BIT MORE GENEROUS WITH MOISTURE AVAILABILITY.
MEANWHILE...THE REMNANT ATMOSPHERIC WAVE ASSOCIATED WITH KIKO MAY
ALSO BE A PLAYER...MORE SO FOR SOUTHEAST CALIFORNIA. GFS SHOWS IT
MOVING NORTHWARD ACROSS SOUTHERN CALIFORNIA ON TUESDAY GETTING
ABSORBED INTO THE MUCH LARGER WEST COAST TROUGH. THERE IS ALSO A
JETLET ASSOCIATED WITH THE WAVE WHICH LEADS TO SOME SPEED DIVERGENCE
WHICH MIGHT BE A SUBTLE DIFFERENCE MAKER. MADE SOME MODEST UPWARD
ADJUSTMENTS BUT INHERENT UNCERTAINTY ABOUT THESE FEATURES AND
MOISTURE AVAILABILITY MAKES HIGH POPS UNWARRANTED.
WEDNESDAY THROUGH SUNDAY...
MODELS ARE FORECASTING A NUMBER OF HARD TO TIME UPPER LEVEL
PERTURBATIONS MOVING INTO AZ FROM NORTHWEST MEXICO. THEREFORE A
SLIGHT CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ARE
WARRANTED.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
12Z MODELS SUGGESTING CONVECTION SHOULD REMAIN CONFINED TO THE
HIGHER TERRAIN SURROUNDING THE PHOENIX METRO AS SLIGHTLY DRIER AIR
MOVES INTO THE REGION. STORMS WILL BE ISOLATED IN NATURE BUT I DO
NOT ANTICIPATE ANYTHING DIRECTLY AFFECTING THE TERMINALS ASIDE FROM
DEBRIS CLOUDS. WINDS SHOULD FAVOR TYPICAL DIURNAL PATTERNS.
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...
CLOUDS ARE CLEARING OUT AND HUMIDITIES REMAIN HIGH AT BOTH TAF
SITES...BUT MODELS SUGGESTING CONVECTION SHOULD REMAIN CONFINED TO
THE HIGHER TERRAIN AND STAY MOSTLY OUT OF THE LOWER DESERTS. I WILL
INCLUDE SOME DEBRIS CLOUDS IN THE TAFS LATER THIS AFTERNOON AND
EVENING BUT OTHERWISE NEITHER SITES SHOULD BE DIRECTLY IMPACTED
TODAY. WINDS WILL FAVOR THE USUAL DIURNAL TRENDS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DRIER AIR WILL MOVE INTO THE REGION AS THE WEEK PROGRESSES. WHILE
AFTERNOON SHOWERS AND THUNDERSTORMS WILL REMAIN A POSSIBILITY EACH
AFTERNOON...STORMS SHOULD BECOME INCREASINGLY CONFINED TO THE HIGHER
TERRAIN EAST OF PHOENIX...WITH LITTLE TO NO ACTIVITY ACROSS THE
DESERTS. HUMIDITIES EACH AFTERNOON WILL DROP INTO THE 15 TO 20
PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY ANTICIPATED. WINDS WILL
FAVOR THE TYPICAL UPSLOPE/DOWNVALLEY PATTERNS WITH NO MAJOR WIND
EVENTS ANTICIPATED.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ/VASQUEZ
AVIATION...LEINS
FIRE WEATHER...LEINS
AREA FORECAST DISCUSSION
NWS PUEBLO CO
230 PM MDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 226 PM MDT SUN SEP 1 2013
ABUNDANT MOISTURE IS OVER THE AREA TODAY. THE MONSOON PLUME LIES
OVERHEAD AND SFC DEW POINTS RANGE FROM THE UPR 40S TO LOWER 60S ACRS
MOST OF THE AREA...AND LCL/S ARE LOWER TODAY...ALL LEADING TO A
BETTER POTENTIAL FOR HEAVY RAINFALL TODAY. LOW LEVEL UPSLOPE FLOW
COULD HELP ENHANCE CONVECTION ALONG AND NR THE MTS AND COULD LEAD TO
A TRAINING EFFECT. THE UPR LEVEL FLOW IS NORTHWESTERLY AROUND 15
KTS SO IN GENERAL THE STORMS SHOULD MOVE TOWARD THE SOUTHEAST THIS
EVENING. SHOWERS AND TSTMS OVER THE MOUNTAINS EARLY THIS AFTERNOON
SHOULD INCREASE IN COVERAGE AND SPREAD TO THE LOWER ELEVATIONS.
HOWEVER THE NAM12 AND RAP13 SHOW LITTLE CONVECTION OUT OVR THE SERN PLAINS
THIS EVENING AND QUICKLY END PCPN BY MIDNIGHT OVR ALL AREAS EXCEPT
ALONG THE CONTDVD. THE HRRR SHOWS A LINE OF CONVECTION MOVING OUT
OVR THE SERN PLAINS EARLY IN THE EVENING BUT DOESN/T REALLY MOVE IT
PAST LA JUNTA.
OVERNIGHT THE MODELS SHOW THE MONSOON MSTR PLUME SHIFTING SOUTH OF
THE AREA...AND THEN ON MON THAT PLUME IS EXPECTED TO BE OVR THE
MOUNTAIN AREAS...WITH DRIER UPR LEVELS FROM THE I-25 CORRIDOR AND
WESTWARD. AT THE LOWER LEVELS DEW POINTS ARE STILL EXPECTED TO
REMAIN FAIRLY HIGH...IN THE UPPER 40S AND 50S. LCL/S ARE EXPECTED
TO BE A LITTLE HIGHER ON MON. BEST CHANCES FOR PCPN ON MON WL BE
OVR THE NR THE MTS...WITH SOME STORMS LIKELY MOVING OUT OVR THE I-25
CORRIDOR...BUT MUCH OF THE REST OF THE PLAINS COULD BE DRY. WE COULD
AGAIN SEE SOME LOCALLY HEAVY RAIN ON MON AND IF ANY OF THESE
STRONGER STORMS MOVE OVER THE BURN SCARS...THERE WL AGAIN BE THE
THREAT OF FLASH FLOODING.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 226 PM MDT SUN SEP 1 2013
UPPER LEVEL HIGH PRESSURE WILL REMAIN CENTERED OVER COLORADO THROUGH
AT LEAST FRIDAY. UPPER LOW SLOWLY MOVES ONSHORE IN THE PACIFIC
NORTHWEST FRIDAY/SATURDAY TIMEFRAME. MODELS A BIT SLOWER WITH THIS
FEATURE THAN RUNS FROM 24 HOURS AGO...LIKELY DUE TO THE BLOCKINESS
OF THE PATTERN.
THIS DOMINANT RIDGE MEANS A RETURN TO UNSEASONABLY WARM CONDITIONS.
THUNDERSTORM CHANCES THROUGH THE WORK WEEK WILL BE PRIMARILY
CONFINED TO THE MOUNTAINS AND WEST...ALTHOUGH MODELS HINT AT A SUBTLE
UPPER DISTURBANCE MOVING THROUGH THE HIGH PLAINS AND SENDING A WEAK
FRONTAL BOUNDARY THROUGH THE EAST CENTRAL PLAINS WEDNESDAY AFTERNOON
WHICH COULD TRIGGER SOME CONVECTION ON THE PALMER DIVIDE. LITTLE IN
THE WAY OF MID AND UPPER LEVEL MOISTURE THOUGH...SO FLASH FLOOD
THREAT WILL BE LOWER.
RIDGE GETS FLATTENED AND AXIS SHUNTED OFF TO THE EAST SATURDAY NIGHT
AND SUNDAY AS LOW PRESSURE MOVES EAST ALONG THE US/CANADIAN BORDER.
COULD SEE A DECENT COLD FRONT MOVE THROUGH THE PLAINS NEXT WEEKEND
IF THE MODELS REMAIN CONSISTENT WITH THE TIMING OF THIS SYSTEM. IF
SO, COOLER TEMPERATURES AND A BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS ARE POSSIBLE SOMETIME NEXT WEEKEND.
IN THE MEANTIME, DESPITE TEMPERATURES WARMING TO ABOVE NORMAL LEVELS
THIS WEEK...GUIDANCE NUMBERS REMAIN TOO WARM. WILL CONTINUE TREND OF
SHAVING A FEW DEGREES OFF GUIDANCE HIGHS. STARK
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 226 PM MDT SUN SEP 1 2013
IN GENERAL...VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS.
HOWEVER...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE IN THE EVENING
HOURS AT THE TERMINAL SITES AND COULD BRIEFLY BRING REDUCED
VSBYS/CIGS. THERE IS ALSO THE POTENTIAL FOR STRATUS DEVELOPMENT NR
KCOS LATE TONIGHT. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN
MONDAY AFTERNOON...WITH KCOS AND KALS HAVING A BETTER CHANCE THAN
KPUB.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...STARK
AVIATION...28
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1112 AM MDT SUN SEP 1 2013
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 431 AM MDT SUN SEP 1 2013
SUBTLE CHANGES IN THE RIDGE POSITIONING LEADS TO A WESTWARD SHIFT
OF THE DEEP MONSOONAL MOISTURE PLUME...APPEARS FARTHER WEST THAN
WHAT EARLIER MODELS MAY HAVE SHOWN. THE END RESULT IS FOR LESS
CONVECTIVE POTENTIAL ACROSS THE DESERT VALLEYS (FROM SE UTAH INTO
THE GRAND VALLEY) THIS AFTERNOON.
OBJECTIVE ANALYSIS PLACES SUBTROPICAL WAVE WITH DEEP MOIST LAYER
ACROSS SRN NEVADA/SWRN UTAH/NWRN ARIZONA WITH A VORTICITY LOBE
THAT EXTENDS INTO ERN UTAH. RADAR INDICATING SOME SPOTTY SHOWERS
ASSOCIATED WITH THIS ERN UTAH VORT LOBE. RAP AND HRRR MODEL SHOWS
THIS FEATURE LIFTING NORTH OVER THE BOOKCLIFFS BY LATE MORNING...
ENHANCING CONVECTION OVER THE BOOKCLIFFS THAT EXTENDS INTO WRN
COLORADO AS FAR EAST AS INDEPENDENCE PASS.
RAP/NAM/GFS MODELS SHOW RIDGE AXIS POSITIONED JUST WEST OF THE
COLORADO SPINE AND AMPLIFIES AS THE DAY PROGRESSES. DRIER AIR THAT
HAS ADVECTED INTO ERN ARIZONA WILL BE DRAWN NORTHWARD INTO SERN
UTAH THIS MORNING...REACHING NW COLORADO LATE THIS AFTERNOON. THIS
RIBBON OF MID LEVEL DRIER AIR LIMITS CONVECTIVE POTENTIAL ACROSS
THE WRN HALF OF OUR FORECAST AREA. WITH WATER VAPOR LOOP CONFIRMING
THIS TREND...CANNOT JUSTIFY THE CONTINUATION OF THE FLASH FLOOD
WATCH FOR SOUTHEAST UTAH AS DEEP CONVECTIVE TOWERS WILL NOT
SURVIVE THE PROMINENT DRY AIR INTRUSION.
DIFFERENT ENVIRONMENT OVER THE COLORADO CENTRAL MOUNTAINS WITH
MOISTURE IN PLACE WITH SOME SHEAR IN THE 15-20 KT RANGE...CONVECTION
THAT FIRES OVER THE BOOKCLIFFS/ROAN PLATEAU AND FLAT TOP MOUNTAINS
WILL TRACK ESE ACROSS EAGLE AND PITKIN COUNTY AND THIS AREA GETS
THE HIGHEST POP VALUES FOR THIS AFTERNOON.
MODELS REMAIN CONSISTENT LEAVING THE SUB TROPICAL HIGH CIRCULATION
TO SPIN OVER CENTRAL NEW MEXICO THROUGH THE NEXT 24 TO 36 HOURS.
THIS IS WHERE 00Z HAND ANALYSIS HAS IT LOCATED AS WELL...BUT THE
ARIZONA WAVE IS NOT QUITE AS DISTINCT AS 24 HOURS AGO AND A BIT
FARTHER WEST. PWAT LOOKS TO PEAK THROUGH THE DAY ACROSS THE WESTERN
CWA THEN MODELS SHOW A DECLINING TREND THROUGH THE FIRST OF THE
WEEK...BUT STILL ABOVE NORMAL. WITH THE ARIZONA WAVE LIFTING A BIT
FARTHER WEST...MOISTURE LOOKS TO GET SPLIT APART BY THIS EVENING.
SOME LIFTING WITH THE WAVE AND THE REST WRAPPING TOWARD THE
CIRCULATION OVER NEW MEXICO...LEAVING A PSEUDO-DRY SLOT FROM THE 4
CORNERS TO THE NORTHERN MOUNTAINS GOING INTO LABOR DAY. WEAK ASCENT
ASSOCIATED WITH THE WAVE TO THE WEST PUSHES ACROSS NORTHERN UTAH AND
NORTHWEST COLORADO LATE TONIGHT INTO MONDAY MORNING AND MAY HELP
FOCUS CONVECTION DURING THE TIME. MOISTURE ALSO POOLS NEAR THE
SOUTHERN MOUNTAINS SO THESE TWO AREAS SHOULD HAVE THE BEST CHANCES
FOR PRECIPITATION WHILE IN BETWEEN CONFIDENCE IS LOWER. UPPER FLOW
NOT IMPRESSIVE BUT STORM MOTION TO THE NORTH SHOULD BE MORE APPARENT
THAN THE PAST FEW DAYS AND MAY HELP ALLEVIATE SOME OF THE FLOODING
POTENTIAL. LOCALLY HEAVY RAIN STILL POSSIBLE WITH WARM CLOUD RAIN
PROCESSES STILL IN PLACE. EXPECT A BIT MORE SUNSHINE ON MONDAY SO
PUSHED TEMPS UP A FEW DEGREES MANY AREAS CLOSER TO THE MAV GUIDANCE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 431 AM MDT SUN SEP 1 2013
SHOULD BE A BIT OF DOWNTURN TO THE CONVECTION OVER THE NORTHWEST 2/3
OF THE CWA AS THE UPPER HIGH WOBBLES TO THE NORTHWEST. THIS WILL
LEAVE THE 4 CORNERS TO THE CENTRAL MOUNTAINS UNDER THE CIRCULATION
WHERE RESIDUAL MOISTURE WILL BE POOLING. THEREFORE REFOCUSED THE
HIGH POPS TO OUR SOUTHERN CWA TAPERING OFF TO THE NORTH. HIGH NOT
CHANGING MUCH AND SHOULD REMAIN ABOVE NORMAL MOST AREAS.
TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BE ANCHORED OVER THE
COLORADO ROCKIES. MONSOONAL MOISTURE PLUME WILL BE WEST OF OUR
FORECAST AREA. SOME MONSOONAL MOISTURE WILL BE TRAPPED BENEATH THE
HIGH CORE TO ALLOW FOR DAILY SHOWERS AND THUNDERSTORMS. WITH SHEAR
ESSENTIALLY NON EXISTENT...MOST STORMS WILL STAY PUT OVER THE
MOUNTAINS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1110 AM MDT SUN SEP 1 2013
SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS THIS
AFTERNOON...ESPECIALLY TOWARD THE CONTINENTAL DIVIDE WHERE
MOUNTAIN PEAKS AND RIDGE TOPS WILL BE OBSCURED FROM RAIN SHAFTS
AND LOW CIGS. FARTHER WEST OVER THE LOWER DESERT VALLEYS...AREAL
COVERAGE OF -SHRA/-TSRA WILL BE ISOLATED. SHOWERS AND STORMS
DIMINISH AFTER 02Z.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...PF/15
LONG TERM...15/PF
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS ALBANY NY
155 PM EDT SUN SEP 1 2013
.SYNOPSIS...
A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY
OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 110 PM EDT...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW A
GOOD DEAL OF CLOUDINESS AROUND THE REGION EARLY THIS AFTERNOON. A
DIFFUSE SFC FRONTAL BOUNDARY REMAINS SITUATED NEAR THE FAR
SOUTHEASTERN CORNER OF THE CWA. SHOWER AND THUNDERSTORM ACTIVITY
HAS INCREASED ACROSS MAINLY ULSTER...DUTCHESS AND LITCHFIELD
COUNTIES SO RAISED POPS TO LIKELY IN THESE AREA. SPC RAP ANALYSIS
SHOW A DECENT INSTABILITY GRADIENT ACROSS THE AREA WITH ONLY
AROUND 500 J/KG OF CAPE ACROSS THE ADIRONDACKS...WITH AROUND 2000
J/KG SOUTH AND EAST OF ALBANY. THE MOST UNSTABLE AREA COINCIDES
WITH WHERE THE SURFACE BOUNDARY IS...THUS THE HIGHER POPS. LOWERED
TO SLIGHT CHANCE FOR MUCH OF THE WESTERN/SOUTHERN ADIRONDACKS DUE
TO LACK OF FORCING.
THE DIFFUSE FRONTAL BOUNDARY WILL CREEP BACK NORTHWARD DURING THE
THE REST OF THE DAYLIGHT HOURS...WITH POP-UP SHOWERS AND
THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE ESPECIALLY SOUTH
AND EAST OF ALBANY. THE COVERAGE AREA SHOULD BE A LITTLE LESS
THAN YESTERDAY...WITH THE MOST ACTIVITY FOR SOUTHERN AREAS CLOSER
TO THE BOUNDARY. THE PWAT VALUE ON THE 12Z KALY SOUNDING WAS 1.52
INCHES...WHICH IS SLIGHTLY ABOVE NORMAL...SO ANY THUNDERSTORM WILL
BE CAPABLE OF PRODUCING HEAVY DOWNPOURS IN A SHORT PERIOD OF TIME.
ENHANCED WORDING IN THE GRIDS AND HWO PRODUCT WAS CONTINUED FOR
HEAVY RAINFALL WITH ANY CONVECTION TODAY FOR SOUTHEASTERN PARTS OF
THE AREA...WHICH WILL HAVE BETTER COVERAGE DUE TO BEING MORE
CLOSELY LOCATED TO THE SFC FRONTAL BOUNDARY.
THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY
IN THE 500-1000 J/KG WITH POCKETS OF 1500-2000 J/KG SOUTH OF THE
CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S.
THE PROJECTED VALUE FOR THIS AFTN BASED ON THE 12Z KALY SOUNDING
WAS AROUND 1085 J/KG. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN
WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY
DEEP WELL ORGANIZED CONVECTION.
H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW
HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST
AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE
THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM
THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF
LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE
ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT
THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND
EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN
SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE
DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL
ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL
DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR
LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY
IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS.
LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE
MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN
THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT
ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS
IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME
STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A
BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE
MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY.
PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A
COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM
500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO
25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE
POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT
OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER
LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM
OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET
WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY
HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT
LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE
MONITORED.
OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS
VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND
U60S TO M70S OVER THE HIGH PEAKS.
MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE
PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES
NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND
U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES.
TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE
HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY
COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS
POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS
FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL
HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S
TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS
WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH
SOME U40S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL
REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD.
WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS
IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A
MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS
WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY
THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5
DEGREES BELOW NORMAL.
TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS
FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR
SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP.
HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND
STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW
OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL
BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS
A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW
PASSES TO OUR NORTH.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY IS SITUATED JUST TO THE SOUTH OF THE
REGION...ALLOWING FOR SOME SCT SHOWERS AND THUNDERSTORMS NEAR
KPOU. WITHIN ANY SHOWER OR TSTM...A BRIEF PERIOD OF IFR CONDITIONS
IS POSSIBLE. FURTHER NORTH...KALB/KPSF/KGFL LOOK QUIET FOR THE
NEXT FEW HOURS WITH VFR OR HIGH END MVFR CIGS...BUT THE THREAT
FOR SHOWERS/STORMS WILL RETURN TO THESE SITES FOR THE EVENING AS
THE FRONTAL BOUNDARY BEGINS TO LIFT BACK NORTHWARD. SFC WINDS LOOK
VERY LIGHT...GENERALLY 5 KTS OR LESS THROUGH THE EVENING.
TONIGHT INTO MONDAY MORNING...ADDITIONAL SHOWERS AND THUNDERSTORMS ARE
POSSIBLE ACROSS THE ENTIRE REGION AS A SLOW MOVING COLD FRONT AND
ASSOCIATED UPPER TROUGH APPROACH THE AREA. THIS WILL ALLOW FOR
MVFR CONDITIONS AND POSSIBLE PERIODS OF IFR AS WELL WITHIN
SHOWERS...POSSIBLE THUNDERSTORMS AND LOW CLOUDS. WINDS WILL BE
NEARLY CALM OVERNIGHT...BECOMING SOUTHERLY ON MONDAY AT 5-10 KTS.
SOME IMPROVEMENT IN FLYING CONDITIONS MAY OCCUR TOWARDS MIDDAY
MONDAY...ESP FOR THE VALLEY TERMINALS.
OUTLOOK...
MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID
AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO
TUESDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE
RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND
REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT.
EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY.
LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS
OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR
WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW
INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON
SATURDAY AND THIS MORNING.
ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE
POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN
BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS
OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME.
HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING
THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR
DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING
INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF
THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY.
RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE
THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3
INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW
CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE
SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE
TO MONITORED FOR ANY HYDRO ISSUES.
COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID
WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.CLIMATE...
THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW
NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND
PITTSFIELD.
THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR
ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949.
THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES
ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS.
PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013
AND THE SUMMER.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...FRUGIS/JPV/WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...FRUGIS
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
110 PM EDT SUN SEP 1 2013
.SYNOPSIS...
A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY
OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 110 PM EDT...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW A
GOOD DEAL OF CLOUDINESS AROUND THE REGION EARLY THIS AFTERNOON. A
DIFFUSE SFC FRONTAL BOUNDARY REMAINS SITUATED NEAR THE FAR
SOUTHEASTERN CORNER OF THE CWA. SHOWER AND THUNDERSTORM ACTIVITY
HAS INCREASED ACROSS MAINLY ULSTER...DUTCHESS AND LITCHFIELD
COUNTIES SO RAISED POPS TO LIKELY IN THESE AREA. SPC RAP ANALYSIS
SHOW A DECENT INSTABILITY GRADIENT ACROSS THE AREA WITH ONLY
AROUND 500 J/KG OF CAPE ACROSS THE ADIRONDACKS...WITH AROUND 2000
J/KG SOUTH AND EAST OF ALBANY. THE MOST UNSTABLE AREA COINCIDES
WITH WHERE THE SURFACE BOUNDARY IS...THUS THE HIGHER POPS. LOWERED
TO SLIGHT CHANCE FOR MUCH OF THE WESTERN/SOUTHERN ADIRONDACKS DUE
TO LACK OF FORCING.
THE DIFFUSE FRONTAL BOUNDARY WILL CREEP BACK NORTHWARD DURING THE
THE REST OF THE DAYLIGHT HOURS...WITH POP-UP SHOWERS AND
THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE ESPECIALLY SOUTH
AND EAST OF ALBANY. THE COVERAGE AREA SHOULD BE A LITTLE LESS
THAN YESTERDAY...WITH THE MOST ACTIVITY FOR SOUTHERN AREAS CLOSER
TO THE BOUNDARY. THE PWAT VALUE ON THE 12Z KALY SOUNDING WAS 1.52
INCHES...WHICH IS SLIGHTLY ABOVE NORMAL...SO ANY THUNDERSTORM WILL
BE CAPABLE OF PRODUCING HEAVY DOWNPOURS IN A SHORT PERIOD OF TIME.
ENHANCED WORDING IN THE GRIDS AND HWO PRODUCT WAS CONTINUED FOR
HEAVY RAINFALL WITH ANY CONVECTION TODAY FOR SOUTHEASTERN PARTS OF
THE AREA...WHICH WILL HAVE BETTER COVERAGE DUE TO BEING MORE
CLOSELY LOCATED TO THE SFC FRONTAL BOUNDARY.
THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY
IN THE 500-1000 J/KG WITH POCKETS OF 1500-2000 J/KG SOUTH OF THE
CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S.
THE PROJECTED VALUE FOR THIS AFTN BASED ON THE 12Z KALY SOUNDING
WAS AROUND 1085 J/KG. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN
WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY
DEEP WELL ORGANIZED CONVECTION.
H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW
HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST
AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE
THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM
THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF
LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE
ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT
THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND
EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN
SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE
DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL
ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL
DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR
LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY
IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS.
LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE
MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN
THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT
ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS
IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME
STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A
BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE
MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY.
PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A
COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM
500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO
25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE
POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT
OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER
LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM
OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET
WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY
HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT
LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE
MONITORED.
OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS
VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND
U60S TO M70S OVER THE HIGH PEAKS.
MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE
PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES
NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND
U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES.
TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE
HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY
COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS
POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS
FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL
HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S
TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS
WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH
SOME U40S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL
REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD.
WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS
IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A
MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS
WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY
THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5
DEGREES BELOW NORMAL.
TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS
FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR
SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP.
HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND
STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW
OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL
BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS
A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW
PASSES TO OUR NORTH.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE
REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND
DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY
DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND
EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED
TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK
WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY
MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER
SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION.
MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR
CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS
LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT
KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU
AND KALB.
A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY
SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY
NIGHT.
OUTLOOK...
MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX.
WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID
AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO
TUESDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A
WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO
LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD
SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN
NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE
RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND
REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT.
EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY.
LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS
OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH
LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR
WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW
INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON
SATURDAY AND THIS MORNING.
ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE
POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN
BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS
OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME.
HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING
THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR
DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING
INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF
THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY.
RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE
THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3
INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW
CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE
SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE
TO MONITORED FOR ANY HYDRO ISSUES.
COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID
WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.CLIMATE...
THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW
NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND
PITTSFIELD.
THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR
ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949.
THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES
ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS.
PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013
AND THE SUMMER.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...FRUGIS/JPV/WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA/FRUGIS
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
207 PM EDT SUN SEP 1 2013
.SHORT TERM...
ISOLATED SHOWERS ARE DEVELOPING ACROSS NE FL AND BECOMING MORE
SCATTERED NEAR THE I-75 CORRIDOR IN THE MOIST SWLY FLOW OFF THE
GULF OF MEXICO. AS TEMPS CLIMB TO NEAR 90...STORMS ARE BEGINNING
TO PRODUCE LIGHTNING. THE ACTIVITY WILL PUSH TOWARD THE EAST COAST
AND COLLIDE WITH THE SEA BREEZE THAT IS CURRENTLY PINNED TO THE
COAST. HI-RES MODELS INDICATE AN INCREASE IN COVERAGE AFTER 3 PM
THEN FADE AFTER SUNSET. THESE MODELS AND HRRR INDICATE STORMS WILL
DRIFT BACK INLAND BETWEEN I-95 AND HWY 301 INTO THE EVENING HOURS.
SHOWERS WILL DEVELOP OVER THE OUTER WATERS AFTER MIDNIGHT AND A
FEW MAY MOVE ONSHORE FROM THE GULF IN THE PRE-DAWN HOURS. FAIR
SKIES WITH LOW TEMPS IN THE 70-75 RANGE INLAND AND UPPER 70S COAST
ARE EXPECTED.
.MONDAY THROUGH WEDNESDAY...EASTERN U.S. UPPER TROUGHING WILL
AMPLIFY AGAIN AND BRING A COLD FRONT INTO SE GA BY WEDNESDAY
BEFORE WASHING OUT. SCATTERED AFTERNOON/EVENING THUNDERSTORMS
AND HOT HUMID CONDITIONS WILL CONTINUE. CONVECTION WILL INCREASE
AND REACH THE EAST COAST LATE IN THE DAY DUE TO W TO SW STEERING
FLOW.
.LONG TERM...THURSDAY THROUGH SUNDAY...FAIRLY WEAK FLOW AND MOIST
UNSTABLE AIRMASS WILL RESULT IN DIURNAL SEABREEZE THUNDERSTORMS
EACH DAY. TEMPERATURES WILL REMAIN A FEW DEGREES ABOVE AVERAGE
WITH NEAR CLIMO POPS.
.AVIATION...
PREVAILING VFR IS EXPECTED. HAVE VCSH OR VCTS FOR REMAINDER OF
AFTN. MVFR CONDITIONS ARE EXPECTED BETWEEN 08Z AND 14Z AT GNV AND
VQQ.
&&
.MARINE...
SOUTHWEST FLOW TO CONTINUE THE NEXT FEW DAYS. NOCTURNAL WIND
SURGE OFFSHORE MAY APPROACH SCEC CONDITIONS. SEAS WILL REMAIN 2
TO 3 FEET. OFFSHORE STEERING FLOW WILL PUSH STORMS INTO THE
COASTAL WATERS DURING THE LATE AFTERNOON AND EARLY EVENING.
RIP CURRENTS: LOW RISK THROUGH MONDAY DUE TO OFFSHORE WINDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 72 94 72 94 / 20 40 40 40
SSI 76 92 75 92 / 20 50 50 30
JAX 72 94 72 94 / 30 40 40 40
SGJ 74 91 73 92 / 30 30 30 30
GNV 71 93 71 93 / 20 40 20 30
OCF 71 93 71 94 / 20 30 10 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&
$$
TRABERT/ZIBURA/MCALLISTER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
203 PM EDT SUN SEP 1 2013
.PREV DISCUSSION... /ISSUED 1221 PM EDT SUN SEP 1 2013/
UPDATE...
HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION OVER NORTH GA.
WHILE IT IS SHOWING A LULL AS THE OUTFLOW FROM MCS INTERACTS WITH
INSTABILITY...CAPES 1500-2000 ACROSS PORTIONS OF WEST AND CENTRAL
GA. CURRENT THINKING AS AREA OVER NORTH GA WILL TRANSITION
SOUTHWARD WITHOUT THE LULL AND HAVE ADJUSTED POP/WEATHER TRENDS
ACCORDINGLY. OTHERWISE CURRENT FORECAST TRENDS PRETTY MUCH ON
TRACK EXCEPT FOR MAX TEMPERATURES IN PORTIONS OF NORTH GA WHICH
WERE ALSO TWEAKED. UPDATED FORECAST PRODUCTS WILL BE ISSUED
SHORTLY.
PREV DISCUSSION... /ISSUED 746 AM EDT SUN SEP 1 2013/
UPDATE...
HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A
STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS.
PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY
REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND
SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN
AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC
BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF
FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT
SHOULD BEGIN TO BURN OFF AFTER SUNRISE.
THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/
THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA
DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS
THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE
NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS
UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE
TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR
OUTPUT.
MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS
NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO
FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP
THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL
MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT
HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO
BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS
FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN.
THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP
SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED
DEVELOP...POPS MAY HAVE TO BE RAISED.
FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND
CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW
AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF
SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR
MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION...
LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE
ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING
OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS.
NLISTEMAA
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO...
TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED
COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE
ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE
COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT
AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST
DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE
COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON
THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS
TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING
IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST
MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE
INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS
FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS
DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS
UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE
AREA ON SATURDAY.
AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL
TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A
COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE
NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT
LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY
IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG
SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE
COOLEST DAY OF THE PERIOD.
TDP
&&
.AVIATION...
18Z UPDATE...
LINE OF CONVECTION DEVELOPING OVER THE ATL TO AHN TAF SITES WILL
SLOWLY SINK TO THE SOUTH THROUGH THIS EVENING. ANTICIPATE STORMS
WILL BE SOUTH OF ATL AFTER 20Z AND IMPACT CSG/MCN 20-24Z. VFR
CONDITIONS EXPECTED OUTSIDE OF CONVECTION WITH MVFR AND WIND GUSTS
TO NEAR 30KTS EXPECTED. LOW CLOUDS WILL DEVELOP TOWARD MORNING
AIDED BY THE SATURATED GROUND WITH IFR/LOW MVFR CIGS EXPECTED AT
THIS TIME. WEST WINDS WILL PREVAIL THROUGH THE PERIOD.
//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE IN WINDS...VISIBILITY.
MEDIUM CONFIDENCE IN CIGS OVERNIGHT...CONVECTIVE TIMING.
ATWELL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 70 90 72 / 60 40 40 30
ATLANTA 89 73 90 74 / 60 40 40 40
BLAIRSVILLE 83 66 84 68 / 60 30 60 40
CARTERSVILLE 89 71 89 71 / 60 40 40 40
COLUMBUS 92 75 93 74 / 60 50 40 30
GAINESVILLE 88 69 88 73 / 60 40 40 40
MACON 91 71 91 72 / 60 50 40 30
ROME 88 70 90 72 / 60 30 60 40
PEACHTREE CITY 90 69 90 71 / 60 40 40 30
VIDALIA 91 74 93 74 / 50 40 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ATWELL
LONG TERM....30
AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
154 PM EDT SUN SEP 1 2013
.SYNOPSIS...
WEAK ATLANTIC HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH MONDAY.
A COLD FRONT WILL PUSH THROUGH TUESDAY NIGHT AND WEDNESDAY WITH WEAK
CANADIAN HIGH PRESSURE BUILDING IN FROM THE NORTH. THE HIGH WILL SHIFT
OFF THE COAST LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS AFTERNOON...ISOLATED SHOWERS ARE STARTING TO DEVELOP
MAINLY UPSTREAM ACROSS THE MIDLANDS WITHIN THE SURFACE TROUGH. A
COUPLE OF SHOWERS HAVE ALSO STARTED TO BUBBLE OVER SOUTHEAST
GEORGIA. THERE IS NO CHANGE IN THE FORECAST THINKING FOR
CONVECTIVE ACTIVITY THIS AFTERNOON/EVENING. PREVIOUS DISCUSSION
FOLLOWS BELOW.
LATE THIS MORNING...THE LACK OF ANY FOG/STRATUS HAS RESULTED IN
CLEAR SKIES ACROSS THE FORECAST AREA. THIS IS ALLOWING TEMPS TO
WARM QUITE RAPIDLY AND SOME AREAS ALREADY IN THE MID 80S. A CU
FIELD SHOULD START DEVELOPING VERY SOON AND WILL ENCOMPASS THE
ENTIRE FORECAST AREA. THE MAIN FORECAST ISSUE FOR TODAY REVOLVES
AROUND THE COVERAGE AND INTENSITY OF DIURNAL CONVECTION. THE
MODELS ACROSS THE SPECTRUM ARE SENDING MIXED SIGNALS. SOME OF THE
HI-RES RUNS SUCH AS THE HRRR SHOW LITTLE MORE THAN ISOLATED WEAK
CONVECTION. ON THE OTHER HAND...THE 12Z NAM HAS COME IN WITH AN
UPWARD TREND IN ITS COVERAGE AND INTENSITY. CURRENTLY...THERE IS A
WELL DEFINED AREA OF NVA ALOFT NOTED ON WATER VAPOR IMAGERY IN
ADVANCE OF THE POTENT SHORTWAVE DRIVING ONGOING CONVECTION OVER
THE TENNESSEE VALLEY. THIS NVA WILL LIKELY HANG ON UNTIL LATE IN
THE AFTERNOON BEFORE THE UPSTREAM ENERGY DISRUPTS IT. ANOTHER
INTERESTING NOTE CONCERNS THE THERMODYNAMIC PARAMETERS FROM THE
MODIFIED 12Z RAOB. USING A TEMP/DP OF SOMETHING AROUND 92/73
RESULTS IN CAPE VALUES AROUND 3000 J/KG...WITH DCAPES GREATER THAN
1000 J/KG THANKS TO A GOOD DEAL OF DRY MID LEVEL AIR. THE MAIN
SOURCE OF LOW LEVEL CONVERGENCE WILL BE THE SEA BREEZE...THE BEST
CONSENSUS SEEMS TO FAVOR ISOLATED TO SCATTERED COVERAGE IN THE
MID/LATE AFTERNOON HOURS. GIVEN THE NEAR STORM ENVIRONMENT...THIS
SEEMS TO BE A DAY WITH LIMITED COVERAGE BUT THE POTENTIAL FOR A
COUPLE STRONG TO SEVERE STORMS DEPENDING ON HOW THE SEA BREEZE AND
OUTFLOW BOUNDARIES INTERACT. AS I SAID EARLIER...TEMPS ARE RISING
QUICKLY AND WITH INCREASED LOW LEVEL THICKNESSES...HIGHS WILL BE
IN THE LOW 90S. SUCH VALUES WILL RUN ABOUT 4-5 DEGREES ABOVE CLIMO
FOR EARLY SEPTEMBER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...MOST AREAS LIKELY TO SEE DRY WEATHER. THE AREA WHERE SOME
ISOLATED NOCTURNAL CONVECTION MAY CROP UP OVERNIGHT COULD BE IN
THE SAME AREAS BORDERING THE MIDLANDS AND PEE DEE WHERE A BIT MORE
MID LEVEL TROFFINESS IS NOTED. COASTAL AREAS WILL KEEP A SLIGHT SW
BREEZE GOING OVERNIGHT AS PATTERN IS FAVORABLE FOR NOCTURNAL
JETTING ALONG THE SOUTH CAROLINA COAST.
A BROAD UPPER TROUGH WILL SIT OVER THE AREA ON MONDAY WITH
SUBSTANTIAL WESTERLY FLOW IN THE LOWER LEVELS. A WELL-DEFINED LEE
TROUGH COMBINED WITH MODEST SURFACE BASED CAPE SHOULD ALLOW FOR
SCATTERED SHOWERS/TSTMS ACROSS INLAND AREAS BY EARLY AFTERNOON.
THE SEABREEZE WILL BE PINNED NEAR THE COAST MUCH OF THE DAY BUT
COULD BECOME A PLAYER LATER IN THE AFTERNOON AS IT STARTS TO NUDGE
INLAND. WESTERLY STEERING FLOW SHOULD BRING INLAND CONVECTION
TOWARD THE COAST AS THE DAY PROGRESSES. OUR BEST COVERAGE LOOKS TO
BE LATE AFTERNOON INTO THE EVENING THOUGH A FEW STORMS COULD
CONTINUE OVERNIGHT GIVEN SUCH A RICH AIRMASS IN PLACE.
THE UPPER TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES ON
TUESDAY WITH A COLD FRONT SLOWLY DROPPING SOUTHEAST TOWARD THE AREA.
DEWPOINTS RISING INTO THE MIDDLE 70S WITH TEMPS PUSHING INTO THE
LOWER 90S WILL YIELD SUBSTANTIAL SURFACE BASED CAPES RANGING FROM
2000 TO 3000 J/KG. ADDITIONALLY SHORTWAVE ENERGY WILL PUSH IN FROM
THE WEST DURING THE AFTERNOON. THUS FAIRLY GOOD COVERAGE OF SHOWERS
AND TSTMS EXPECTED DURING THE DAY TUESDAY...ESPECIALLY LATER IN THE
AFTERNOON ONCE THE CONVECTIVE BOUNDARIES BEGIN INTERACTING WITH THE
SEABREEZE.
SCATTERED CONVECTION MAY CONTINUE INTO TUESDAY NIGHT BEFORE TAPERING
OFF FROM NORTH TO SOUTH. THE FRONT SHOULD PUSH SOUTH OF THE AREA ON
WEDNESDAY WITH SLIGHTLY DRIER AND COOLER CONDITIONS IN ITS WAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
CANADIAN HIGH PRESSURE WILL PREVAIL FOR THE BEGINNING OF THE PERIOD
BUT STEADILY SHIFT EAST WITH A RETURN FLOW SETTING UP ON THE SW
PERIPHERY. MOST AREAS WILL BE DRY WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT. DIURNAL CONVECTION RETURNS TO THE FORECAST FRIDAY THROUGH
SUNDAY AS LOW-LEVEL MOISTURE INCREASES AND ANOTHER UPPER TROUGH SETS
UP SHOP.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
THE BIGGEST TAF CONCERN FOR THE UPCOMING FORECAST PERIOD IS THE
POTENTIAL FOR IMPACTS FROM SHOWERS/THUNDERSTORMS THIS AFTERNOON
AND EVENING. SO FAR...DEVELOPMENT HAS BEEN SLOW AND EVEN THE CU
FIELD HAS BEEN QUITE MUTED THANKS TO SOME SUPPRESSION ALOFT.
MODELS DO SHOW MOST OF THE DEVELOPMENT IN THE LATE AFTERNOON HOURS
AND THAT IS WHAT IS PRESENTED IN THE TAF/S. THE MODELS TEND TO
PLACE THE BEST COVERAGE CLOSEST TO KCHS SO I HAVE ADDED THE MOST
DETAIL THERE WITH PREVAILING VCTS STARTING AT 20Z AND THEN A TEMPO
FOR MVFR TSRA CONDITIONS BETWEEN 21-23Z. I HAVE LEFT KSAV WITH
JUST A VCTS FOR NOW...BUT WILL CONTINUE TO MONITOR RADAR TRENDS
FOR AMENDMENTS AT BOTH SITES. MOST OF THE COVERAGE WILL THEN DRIFT
INLAND LATE THIS EVENING AND THE FORECAST IS VFR THEREAFTER. SOME
GUIDANCE HINTS AT THE POSSIBILITY FOR MVFR CEILINGS
OVERNIGHT...BUT CHANCES ARE TOO LOW TO WARRANT A MENTION AT THIS
POINT.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND TSTMS MONDAY
THROUGH TUESDAY NIGHT WITH OCCASIONAL REDUCTIONS IN CEILING AND
VISIBILITY.
&&
.MARINE...
FAIRLY LIGHT WINDS AND SEAS 2 TO 3 FT EXPECTED THROUGH THE AFTERNOON
HOURS. A STRONGER NOCTURNAL SURGE IS ANTICIPATED TONIGHT AS THE
BOUNDARY LAYER PRES GRADIENT TIGHTENS. THERE MAY BE A SHORT
DURATION WHERE WINDS APPROACH SMALL CRAFT ADVISORY CONDITIONS IN
FREQUENT GUSTS OVER 20 KT BUT WE HAVE CAPPED OFFSHORE FLOW AT 15
TO 20 KT FOR NOW. SEAS WILL BUILD TO NEAR 4 FT BEYOND 20 NM
OFFSHORE.
MONDAY THROUGH FRIDAY...WEATHER CONDITIONS WILL REMAIN BELOW
ADVISORY CRITERIA. SOUTH TO SOUTHWEST WINDS WILL PERSIST UNTIL
TUESDAY AHEAD OF THE COLD FRONT. ONCE THE FRONT PUSHES INTO THE
AREA...WINDS WILL BECOME VARIABLE AND LIGHT...WITH SEAS NO HIGHER
THAN 2-3 FEET.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH
MARINE...JRL
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1221 PM EDT SUN SEP 1 2013
.UPDATE...
HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION OVER NORTH GA.
WHILE IT IS SHOWING A LULL AS THE OUTFLOW FROM MCS INTERACTS WITH
INSTABILITY...CAPES 1500-2000 ACROSS PORTIONS OF WEST AND CENTRAL
GA. CURRENT THINKING AS AREA OVER NORTH GA WILL TRANSITION
SOUTHWARD WITHOUT THE LULL AND HAVE ADJUSTED POP/WEATHER TRENDS
ACCORDINGLY. OTHERWISE CURRENT FORECAST TRENDS PRETTY MUCH ON
TRACK EXCEPT FOR MAX TEMPERATURES IN PORTIONS OF NORTH GA WHICH
WERE ALSO TWEAKED. UPDATED FORECAST PRODUCTS WILL BE ISSUED
SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 746 AM EDT SUN SEP 1 2013/
UPDATE...
HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A
STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS.
PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY
REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND
SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN
AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC
BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF
FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT
SHOULD BEGIN TO BURN OFF AFTER SUNRISE.
THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/
THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA
DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS
THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE
NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS
UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE
TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR
OUTPUT.
MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS
NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO
FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP
THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL
MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT
HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO
BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS
FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN.
THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP
SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED
DEVELOP...POPS MAY HAVE TO BE RAISED.
FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND
CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW
AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF
SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR
MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION...
LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE
ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING
OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS.
NLISTEMAA
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO...
TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED
COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE
ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE
COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT
AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST
DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE
COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON
THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS
TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING
IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST
MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE
INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS
FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS
DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS
UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE
AREA ON SATURDAY.
AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL
TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A
COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE
NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT
LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY
IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG
SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE
COOLEST DAY OF THE PERIOD.
TDP
AVIATION...
12Z UPDATE...
ENHANCED FOG CHANNEL SHOWS A STRIP OF 300 TO 500 FOOT CIGS FROM
CANTON TO WEST OF ATL. THIS AREA IS MOVING EAST. DON`T THINK THE
DECK WILL DISSIPATE BEFORE IT REACHES THE AIRPORT...SO WILL
INCLUDE A BKN005 DECK FOR TWO HOURS. THE LOW DECK WILL SCT OUT TO
A CU DECK AROUND 4500 FT LATE THIS MORNING. CONVECTION HAS BEEN
INCREASING ACROSS N GA THIS MORNING. LATEST RUN OF THE HRRR HAS
THIS ACTIVITY COMING THROUGH THE AIRPORT AROUND 18Z. MOVED UP THE
PRECIP TIMING.
//ATL CONFIDENCE...12Z UPDATE...
LOW-MEDIUM CONFIDENCE ON LOW STRATUS CIGS THROUGH 15Z. MEDIUM
CONFIDENCE ON CONVECTION TIMING TODAY. OTHERWISE...HIGH CONFIDENCE
REMANING ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 71 91 72 / 50 40 40 30
ATLANTA 89 72 89 74 / 50 40 40 40
BLAIRSVILLE 83 67 82 68 / 60 30 60 40
CARTERSVILLE 89 71 90 71 / 60 40 40 40
COLUMBUS 92 73 91 74 / 60 50 40 30
GAINESVILLE 88 71 88 73 / 60 40 40 40
MACON 91 72 91 72 / 60 50 40 30
ROME 88 71 92 72 / 60 30 60 40
PEACHTREE CITY 90 70 90 71 / 50 40 40 30
VIDALIA 91 74 91 74 / 60 40 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ATWELL
LONG TERM....30
AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
252 PM CDT SUN SEP 1 2013
.DISCUSSION...
1045 AM CDT
NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP
TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER.
HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT
THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND
ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS
DURING THE AFTERNOON.
CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT
THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE
MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF
HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND
STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL
CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE
WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE
BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS
BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE
ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW
INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE
THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON
GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION
NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS.
BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH
STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING
THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES
WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS
SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH
MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT
HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS
AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN
BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY
WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND
RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS.
OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY
BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL
CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS
IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST
CWA.
WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG
THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE
BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT
CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL
CONVERGENCE ELSEWHERE.
FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT.
IZZI
//PREV DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GENERALLY WESTERLY WINDS TO ARND 10KT UNTIL FROPA EARLY THIS
EVENING...THEN SHIFT NORTHWEST/NORTH AND STRENGTHENING OVERNIGHT
FOLLOWING FRONTAL PASSAGE.
* NORTH WINDS GUSTING TO 18 KT BY THE EARLY MORNING HOURS.
* ISOLD SHRA/TSRA DEVELOPING ALONG OR JUST AHEAD OF THE FRONTAL
BOUNDARY.
KREIN
//DISCUSSION...UPDATED 18Z...
PRIMARY CONCERN FOR THE PERIOD WILL BE THE CHANCES FOR SHRA/TSRA
LATE THIS AFTERNOON INTO EARLY THIS EVENING. A COLD FRONT IS
DROPPING SEWD INTO THE MIDDLE MISSISSIPPI VALLEY WHICH SHOULD BE
THE FOCUS FOR THE CONVECTIVE ACTIVITY. LATEST SFC ANALYSIS SHOWS A
FAIRLY DIFFUSE BOUNDARY WITH LITTLE WIND SHIFT OR TEMPERATURE
CONTRAST INVOF THE BOUNDARY WITH WINDS ONLY GRADUALLY VEERING FROM
WLY TO NWLY. EARLY MORNING STRATUS AND FOG HAS FINALLY CLEARED AND
INCREASED INSOLATION IS ALLOWING SFC TEMPS TO INCREASE INTO THE
80S WITH DEWPOINTS IN THE UPPER 60S TO LOWER 70S. LATEST VISIBLY
SATELLITE IMAGERY IS ALSO INDICATING ENHANCED CU DEVELOPMENT INVOF
THE FRONTAL BOUNDARY. STILL EXPECTING SCT SHOWERS AND
THUNDERSTORMS AS THE FRONT MOVES THROUGH THE AREA...BUT SINCE
CONVECTIVE ACTIVITY IS EXPECTED TO REMAIN SCATTERED...CONFIDENCE
IN EXACT TIMING AND DURATION IS LOW.
FOLLOWING THE FROPA...COOLER...DRIER AIR WILL GRADUALLY FILTER
INTO THE REGION WITH THE STRONGEST COLD ADVECTION DEVELOPING
DURING THE EARLY MORNING HOURS. EXPECT THAT WINDS SHOULD VEER TO
NORTHERLY AND GUST TO ARND 18KT IN TIME FOR THE MORNING RUSH
HOURS. WINDS SHOULD GRADUALLY TAPER OFF THROUGH THE AFTERNOON
TOMORROW AS HIGH PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI
VALLEY AND INTO THE WESTERN GREAT LAKES.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED.
* LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
252 PM...LOW PRESSURE OVER LAKE SUPERIOR WILL SLOWLY MOVE EAST
INTO QUEBEC MONDAY AFTERNOON. A TRAILING COLD FRONT WILL MOVE
SOUTH ACROSS LAKE MICHIGAN THIS EVENING SHIFTING WINDS BRIEFLY
NORTHWEST AND THEN NORTHERLY OVERNIGHT. PREVAILING SPEEDS IN THE
20-25KT RANGE STILL LOOK ON TRACK THOUGH ITS STILL POSSIBLE FOR
SOME GUSTS TO 30 KT ESPECIALLY MONDAY MORNING. HIGH PRESSURE WILL
BUILD ACROSS THE NORTHERN PLAINS TONIGHT INTO MONDAY AND THEN
SLIDE SOUTHEAST ACROSS THE SOUTHERN LAKES AND OHIO VALLEY MONDAY
NIGHT THROUGH WEDNESDAY. THIS WILL ALLOW THE WINDS TO DIMINISH
FIRST ACROSS THE SOUTHERN END OF THE LAKE BUT AS ANOTHER FRONT
SAGS INTO THE NORTHERN LAKES TUESDAY NIGHT INTO WEDNESDAY...THE
GRADIENT MAY STAY SOMEWHAT TIGHT ACROSS THE NORTHERN HALF OR THIRD
OF THE LAKE TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE SPREADING
ACROSS SOUTHERN CANADA TUESDAY NIGHT WILL WEAKEN AND MERGE WITH
THE HIGH OVER THE OHIO VALLEY WEDNESDAY AND WEDNESDAY NIGHT. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
102 PM CDT SUN SEP 1 2013
.DISCUSSION...
1045 AM CDT
NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP
TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER.
HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT
THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND
ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS
DURING THE AFTERNOON.
CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT
THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE
MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF
HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND
STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL
CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE
WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE
BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS
BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE
ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW
INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE
THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON
GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION
NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS.
BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH
STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING
THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES
WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS
SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH
MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT
HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS
AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN
BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY
WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND
RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS.
OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY
BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL
CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS
IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST
CWA.
WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG
THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE
BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT
CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL
CONVERGENCE ELSEWHERE.
FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT.
IZZI
//PREV DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WEST TO WEST-NORTHWEST WINDS TO ARND 10KT UNTIL FROPA LATE THIS
AFTERNOON...THEN SHIFT NORTHWEST/NORTH AND STRENGTHENING
FOLLOWING FRONTAL PASSAGE.
* NORTH WINDS GUSTING TO 18KT BY THE EARLY MORNING HOURS.
* ISOLD SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY.
KREIN
//DISCUSSION...UPDATED 18Z...
PRIMARY CONCERN FOR THE PERIOD WILL BE THE CHANCES FOR SHRA/TSRA
LATE THIS AFTERNOON INTO EARLY THIS EVENING. A COLD FRONT IS
DROPPING SEWD INTO THE MIDDLE MISSISSIPPI VALLEY WHICH SHOULD BE
THE FOCUS FOR THE CONVECTIVE ACTIVITY. LATEST SFC ANALYSIS SHOWS A
FAIRLY DIFFUSE BOUNDARY WITH LITTLE WIND SHIFT OR TEMPERATURE
CONTRAST INVOF THE BOUNDARY WITH WINDS ONLY GRADUALLY VEERING FROM
WLY TO NWLY. EARLY MORNING STRATUS AND FOG HAS FINALLY CLEARED AND
INCREASED INSOLATION IS ALLOWING SFC TEMPS TO INCREASE INTO THE
80S WITH DEWPOINTS IN THE UPPER 60S TO LOWER 70S. LATEST VISIBLY
SATELLITE IMAGERY IS ALSO INDICATING ENHANCED CU DEVELOPMENT INVOF
THE FRONTAL BOUNDARY. STILL EXPECTING SCT SHOWERS AND
THUNDERSTORMS AS THE FRONT MOVES THROUGH THE AREA...BUT SINCE
CONVECTIVE ACTIVITY IS EXPECTED TO REMAIN SCATTERED...CONFIDENCE
IN EXACT TIMING AND DURATION IS LOW.
FOLLOWING THE FROPA...COOLER...DRIER AIR WILL GRADUALLY FILTER
INTO THE REGION WITH THE STRONGEST COLD ADVECTION DEVELOPING
DURING THE EARLY MORNING HOURS. EXPECT THAT WINDS SHOULD VEER TO
NORTHERLY AND GUST TO ARND 18KT IN TIME FOR THE MORNING RUSH
HOURS. WINDS SHOULD GRADUALLY TAPER OFF THROUGH THE AFTERNOON
TOMORROW AS HIGH PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI
VALLEY AND INTO THE WESTERN GREAT LAKES.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED.
* LOW/MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1143 AM CDT SUN SEP 1 2013
.DISCUSSION...
1045 AM CDT
NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP
TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER.
HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT
THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND
ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS
DURING THE AFTERNOON.
CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT
THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE
MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF
HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND
STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL
CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE
WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE
BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS
BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE
ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW
INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE
THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON
GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION
NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS.
BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH
STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING
THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES
WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS
SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH
MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT
HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS
AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN
BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY
WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND
RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS.
OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY
BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL
CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS
IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST
CWA.
WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG
THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE
BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT
CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL
CONVERGENCE ELSEWHERE.
FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT.
IZZI
//PREV DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* WEST TO WEST-NORTHWEST WINDS TO ARND 10KT. FRONT WILL APPROACH
WITH WINDS TURNING NORTHWEST/NORTH AND STRENGTHENING FOLLOWING
FRONTAL PASSAGE.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 19-22Z.
KREIN
//DISCUSSION...UPDATED 12Z...
SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY
AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR
PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE
BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE
FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO
10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE
REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO
DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT
THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING
AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL
SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE
MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY
TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY
00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY
WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS
INTO THE MID TEENS DEVELOPING OVERNIGHT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED.
* LOW/MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1046 AM CDT SUN SEP 1 2013
.DISCUSSION...
1045 AM CDT
NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP
TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER.
HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT
THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND
ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS
DURING THE AFTERNOON.
CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT
THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE
MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF
HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND
STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL
CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE
WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE
BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS
BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE
ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW
INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE
THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON
GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION
NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS.
BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH
STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING
THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES
WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS
SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH
MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT
HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS
AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN
BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY
WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND
RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS.
OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY
BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL
CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS
IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST
CWA.
WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG
THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE
BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT
CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL
CONVERGENCE ELSEWHERE.
FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT.
IZZI
&&
.PREV DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 10KT LATE MORNING.
FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT
00Z.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z.
KREIN
//DISCUSSION...UPDATED 12Z...
SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY
AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR
PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE
BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE
FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO
10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE
REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO
DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT
THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING
AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL
SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE
MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY
TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY
00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY
WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS
INTO THE MID TEENS DEVELOPING OVERNIGHT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
901 AM CDT SUN SEP 1 2013
.DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 10KT LATE MORNING.
FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT
00Z.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z.
KREIN
//DISCUSSION...UPDATED 12Z...
SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY
AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR
PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE
BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE
FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO
10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE
REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO
DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT
THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING
AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL
SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE
MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY
TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY
00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY
WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS
INTO THE MID TEENS DEVELOPING OVERNIGHT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011-
ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-
ILZ033-ILZ039 UNTIL 10 AM SUNDAY.
BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10
AM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
649 AM CDT SUN SEP 1 2013
.DISCUSSION...
352 AM CDT
MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING
ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE
STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH
COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY.
CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL
SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED
LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG
IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN
RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS
IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY
DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN
RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA.
HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A
LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR
A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO
QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS
ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE
SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES
EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS
MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH
LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE
CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF
SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH
LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO
PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID
SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S
WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA
POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS
MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN
PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT
SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS
WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING
MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT
OUT OF THE QUESTION IN THOSE LOCATIONS.
PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON
REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS
TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR
ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND
TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE
UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS
WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST
TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP
AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP
SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME
SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN
PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM
DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO
ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH
LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT
THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE.
SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY
INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD
COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN
TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF
SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR
THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD
COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE
LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF
SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO
THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL
NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT
LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND
HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS
WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE
LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST
CONVERGENCE CAN OCCUR.
COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL
PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE
70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK
STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN
PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN
THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE
LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER
WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT
INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT
THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* PATCHY GROUND FOG DEVELOPED EARLY THIS MORNING...CURRENTLY IS
HOLDING WEST OF ORD/MDW WHERE VSBYS HAVE REDUCED TO LESS THAN
1/2SM IN SPOTS.
* SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 6-8KT AFT 13Z...THEN
FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT 00Z.
* ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z.
BEACHLER
//DISCUSSION...UPDATED 12Z...
SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY
AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR
PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE
BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE
FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO
10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE
REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO
DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT
THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING
AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL
SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE
MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY
TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY
00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY
WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS
INTO THE MID TEENS DEVELOPING OVERNIGHT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DISSIPATING AROUND 13-14Z.
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS.
TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE.
THURSDAY THROUGH SATURDAY...VFR.
BEACHLER
&&
.MARINE...
358 AM CDT
WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT
LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS
EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE
MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A
STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR
TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD
PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER
WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF
ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH
MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL
REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE.
WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE
SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE
DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL
CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH
MIDDAY TUESDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 AM SUNDAY.
BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM
TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM
TUESDAY.
DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9
AM SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 4 PM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS GOODLAND KS
244 PM MDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 207 PM MDT SUN SEP 1 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW RIDGE BEGINNING TO
RETREAT TOWARD THE FOUR CORNERS REGION WITH POSITIVELY TILTED
TROUGH MIGRATING INTO THE NORTHERN GREAT LAKES REGION. STRONG
SUBSIDENCE IS EVIDENT ACROSS THE NORTHERN PLAINS...AND IS
BEGINNING TO OVERSPREAD OUR CWA FROM THE NORTH-NORTHEAST. AT THE
SURFACE HIGH PRESSURE HAS SETTLED OVER OUR CWA WITH COLD FRONT NOW
ALONG FRONT RANGE EXTENDING SOUTH ACROSS TEXAS PANHANDLE.
THERE HAVE BEEN A FEW LIGHT SHOWERS SLOWLY MOVING ACROSS THE
PLAINS OF EASTERN COLORADO AND LATEST RAP/HRRR SHOW THIS ACTIVITY
FALLING APART THROUGH SUNRISE. AT THIS POINT I AM NOT CONFIDENT WE
WILL SEE ANY MEASURABLE PRECIP OUT OF THIS WITH STABLE/DRY AIR
SPREADING WEST...SO I WILL KEEP MENTION OUT THROUGH THE REMAINDER
OF THE AFTERNOON. WITH STABLE AIR MASS IN PLACE AND SUBSIDENCE
BUILDING IN ALOFT...I AM ANTICIPATING DRY CONDITIONS THROUGH
MONDAY.
REGARDING TEMPS...COOLER AIR MASS REMAINS IN PLACE OVERNIGHT...AND
WITH LOW TD VALUES (45-50F) ADVECTING SOUTH THROUGH THIS EVENING
AND CLEAR/CALM CONDITIONS WE SHOULD SEE VERY GOOD RADIATIONAL
COOLING. I TRIMMED TEMPS A LITTLE WITH LOWS AT SOME LOCATIONS IN
THE LOW 50S. H5 RIDGE WILL BEGIN TO BUILD BACK TO THE EAST MONDAY
AND LEE TROUGH WILL BEGIN TO STRENGTHEN. WE SHOULD SEE WAA ALOFT
WITH UNIDIRECTIONAL SOUTHERLY FLOW...AND HIGHS ABOUT 3-4F WARMER
THAN TODAY (UPPER 80S/NEAR 90F).
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 221 PM MDT SUN SEP 1 2013
FROM MONDAY NIGHT THROUGH SATURDAY...THE UPPER HIGH PRESSURE
CENTER REMAINS OVER THE CENTRAL ROCKIES AND CENTRAL HIGH PLAINS
REGIONS. BY NEXT SUNDAY...THE UPPER LOW CENTER THAT HAS BEEN SLOWLY
MOVING INTO THE PACIFIC NORTHWEST MOVES ACROSS THE NORTHERN
ROCKIES AND NORTHERN HIGH PLAINS...PUSHING THE UPPER TROUGH AXIS
FURTHER EAST OVER THE PLAINS AND WESTERN GREAT LAKES
REGIONS AND TURNING THE FLOW ALOFT TO THE SOUTHWEST ACROSS THE
FORECAST AREA.
THE SURFACE HIGH PRESSURE AREA IN PLACE OVER THE PLAINS STATES
MOVES FURTHER TO THE EAST AS THE SURFACE TROUGH MOVES INTO
POSITION NEAR THE EASTERN COLORADO BORDER BY WEDNESDAY MORNING. A
WEAK SURFACE TROUGH REMAINS NEARLY STATIONARY OVER THE EASTERN
COLORADO BORDER THROUGH SUNDAY WITH MAINLY WESTERLY FLOW ALOFT
OVER THE ROCKIES. DURING THIS TIME...ISOLATED SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN TO THE WEST EACH
AFTERNOON WITH A STRAY STORM OR TWO MOVING INTO THE WESTERN
PORTION OF THE FORECAST AREA LATE EACH DAY. OTHERWISE...HAVE KEPT
THE EXTENDED FORECAST PERIOD DRY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1118 AM MDT SUN SEP 1 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH KGLD AND
KMCK TERMINALS. NORTHEAST WINDS GUSTING TO 20KT WILL BE POSSIBLE
EARLY IN THE TAF BEFORE THE SURFACE GRADIENT BEGINS TO RELAX
BEHIND A COLD FRONT CURRENTLY SOUTH OF BOTH TERMINALS. BY MID
AFTERNOON WINDS SHOULD BE BELOW 12KT AT BOTH TERMINALS WITH LIGHT
AND VARIABLE WINDS OVERNIGHT. WINDS WILL SHIFT TO THE SOUTH AND
INCREASE ONCE AGAIN AROUND SUNRISE MONDAY MORNING IN RESPONSE TO
DEEPENING SURFACE TROUGH.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
207 PM MDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 207 PM MDT SUN SEP 1 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW RIDGE BEGINNING TO
RETREAT TOWARD THE FOUR CORNERS REGION WITH POSITIVELY TILTED
TROUGH MIGRATING INTO THE NORTHERN GREAT LAKES REGION. STRONG
SUBSIDENCE IS EVIDENT ACROSS THE NORTHERN PLAINS...AND IS
BEGINNING TO OVERSPREAD OUR CWA FROM THE NORTH-NORTHEAST. AT THE
SURFACE HIGH PRESSURE HAS SETTLED OVER OUR CWA WITH COLD FRONT NOW
ALONG FRONT RANGE EXTENDING SOUTH ACROSS TEXAS PANHANDLE.
THERE HAVE BEEN A FEW LIGHT SHOWERS SLOWLY MOVING ACROSS THE
PLAINS OF EASTERN COLORADO AND LATEST RAP/HRRR SHOW THIS ACTIVITY
FALLING APART THROUGH SUNRISE. AT THIS POINT I AM NOT CONFIDENT WE
WILL SEE ANY MEASURABLE PRECIP OUT OF THIS WITH STABLE/DRY AIR
SPREADING WEST...SO I WILL KEEP MENTION OUT THROUGH THE REMAINDER
OF THE AFTERNOON. WITH STABLE AIR MASS IN PLACE AND SUBSIDENCE
BUILDING IN ALOFT...I AM ANTICIPATING DRY CONDITIONS THROUGH
MONDAY.
REGARDING TEMPS...COOLER AIR MASS REMAINS IN PLACE OVERNIGHT...AND
WITH LOW TD VALUES (45-50F) ADVECTING SOUTH THROUGH THIS EVENING
AND CLEAR/CALM CONDITIONS WE SHOULD SEE VERY GOOD RADIATIONAL
COOLING. I TRIMMED TEMPS A LITTLE WITH LOWS AT SOME LOCATIONS IN
THE LOW 50S. H5 RIDGE WILL BEGIN TO BUILD BACK TO THE EAST MONDAY
AND LEE TROUGH WILL BEGIN TO STRENGTHEN. WE SHOULD SEE WAA ALOFT
WITH UNIDIRECTIONAL SOUTHERLY FLOW...AND HIGHS ABOUT 3-4F WARMER
THAN TODAY (UPPER 80S/NEAR 90F).
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 214 AM MDT SUN SEP 1 2013
UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR
THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM TEMPERATURES AND
DRY CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA
WILL BE CENTERED OVER COLORADO FOR WEDNESDAY AS RIDGE BECOMES MORE
AMPLIFIED INTO THE NORTHERN HIGH PLAINS FOR THURSDAY AND FRIDAY. THE
RIDGE WILL DEAMPLIFY AND RETROGRADE WESTWARD INTO THE DESERT
SOUTHWEST REGION NEXT WEEKEND AS AN UPPER LEVEL LOW MOVES OUT OF
ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE TROUGHS LOOK TO
DEVELOP LATE INTO NEXT WEEKEND AND MOVE INTO THE HIGH PLAINS WITH
THE MAIN ASSOCIATED UPPER LEVEL TROUGH...WHICH COULD PROVIDE
ENOUGH LIFT FOR THUNDERSTORM DEVELOPMENT FOR SUNDAY.
STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE
EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE
LOWER 90S. LOW TEMPERATURES FOR THE EXTENDED PERIOD WILL BE IN THE
UPPER 60S FOR MOST LOCATIONS. MODEL SOUNDINGS SHOW STABLE UPPER AIR
PROFILE THROUGH THE PERIOD...WITH MARGINAL INSTABILITY PARAMETERS AT
BEST AND A GENERAL LACK OF MOISTURE IN THE UPPER AIR PROFILES.
MODEL FORECASTS DIFFER ON PRECIPITATION CHANCES FOR NEXT
SUNDAY...BUT ENCROACHING FRONTAL CLIPPER SYSTEM WILL LIKELY
PROVIDE SOME CHANCES FOR STORM DEVELOPMENT. BESIDES SLIGHT
PRECIPITATION CHANCES NEXT WEEKEND...THE MAIN WEATHER PATTERN FOR
THE EXTENDED FORECAST PERIOD CONTINUES TO BE WARM TEMPERATURES AND
MAINLY DRY CONDITIONS FOR THE TRI STATE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1118 AM MDT SUN SEP 1 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH KGLD AND
KMCK TERMINALS. NORTHEAST WINDS GUSTING TO 20KT WILL BE POSSIBLE
EARLY IN THE TAF BEFORE THE SURFACE GRADIENT BEGINS TO RELAX
BEHIND A COLD FRONT CURRENTLY SOUTH OF BOTH TERMINALS. BY MID
AFTERNOON WINDS SHOULD BE BELOW 12KT AT BOTH TERMINALS WITH LIGHT
AND VARIABLE WINDS OVERNIGHT. WINDS WILL SHIFT TO THE SOUTH AND
INCREASE ONCE AGAIN AROUND SUNRISE MONDAY MORNING IN RESPONSE TO
DEEPENING SURFACE TROUGH.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...MK
AVIATION...DR
AREA FORECAST DISCUSSION
NWS WICHITA KS
1245 PM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 1108 AM CDT SUN SEP 1 2013
COOL FRONTAL BOUNDARY CONTINUES TO SLOWLY PUSH INTO SRN KS AT
THIS TIME. CURRENTLY LOCATED FROM KDDC-KPTT TO JUST SOUTH OF KICT
TO NEAR KCNU. SOME WIDELY SCT SHOWERS OR SPRINKLES ARE LOCATED
ALONG THE FRONT...WITH MORE WIDESPREAD SHOWERS OVER ERN KS. EXPECT
THIS FRONTAL BOUNDARY TO CONTINUE TO PUSH SOUTH INTO EXTREME SRN
KS EARLY THIS AFTERNOON...AND EVENTUALLY PUSH INTO OK BY LATE THIS
AFTERNOON/EARLY THIS EVENING. THE DRIER AIR ASSOCIATED WITH THIS
BOUNDARY IS LAGGING BEHIND SOMEWHAT...WITH SFC DEWPOINTS IN CEN KS
FALLING INTO THE LOW 60S. STILL SEEING SOME HIGHER SFC DWPTS OVER
SOUTHEAST KS...CLOSER TO THE MAIN BOUNDARY.
EXPECT THE MAIN SHORTWAVE OVER NE NEB TO DROP SOUTHEAST INTO ERN KS
AS THE AFTERNOON PROGRESSES. AS THIS INCREASED LIFT MOVES INTO SERN
KS...THINK SOME REINVIGORATED SHOWERS/STORMS WILL DEVELOP WHERE THIS
HIGHER SFC DWPT AIR AND UNSTABLE AIRMASS WILL BE LOCATED. SO WILL
KEEP THE HIGHEST POPS ALONG THE KS/OK BORDER AND ESPECIALLY FOR SERN
KS FOR THE LATE AFTERNOON HOURS. THINK THERE IS A SMALL WINDOW OF
OPPORTUNITY FOR STORMS TO DEVELOP...AS THE DRIER AIR PUSHES INTO SRN
KS...AND EVENTUALLY WITH THE FRONT DROPPING SOUTH INTO OK. SO
THINK BY THE LATE AFTERNOON/EARLY EVENING HOURS...MOST OF THE
CONVECTIVE CHANCES WILL DROP SOUTH OF THE AREA INTO OK. CURRENT
POPS/GRIDS HAVE THIS TREND WILL IN HAND...WITH ONLY SOME MINOR
TWEAKS FOR TIMING.
KETCHAM
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION
OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS
EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS
EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN
NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM
PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR
TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH
CENTRAL/SOUTHEAST KS.
THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT
MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL
MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A
RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE
FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD
OF THE FRONT.
COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO
TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY
NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS.
JMC
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL
ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO
THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES
TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN
RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS
VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH.
THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME.
JMC
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1244 PM CDT SUN SEP 1 2013
A WEAK COOL FRONT OVER SRN KS WILL CONTINUE TO PUSH SOUTH INTO OK
LATE THIS AFTERNOON. EXPECTING VFR CONDITIONS EVEN WITH THE CLOUD
COVER ACROSS THE AREA ASSOCIATED WITH THE BOUNDARY...WITH MOST
LOCATIONS ALREADY SEEING A WIND SHIFT TO THE NORTH OR NORTHEAST.
COULD ALSO SEE SOME SCATTERED SHRA FOR AREAS MAINLY EAST OF THE KS
TURNPIKE...WITH A FEW RUMBLES OF THUNDER POSSIBLE GIVEN SOME
LINGERING INSTABILITY IN THIS AREA. SO WILL GO WITH A VCTS FOR THE
KCNU TAF FOR THE AFTN HOURS. WILL SEE VFR CONDITIONS EVEN WITH THE
TSRA CHANCES.
THINK CHANCES OF TSRA WILL END QUICKLY AFTER 02Z/MON AS THE BOUNDARY
CONTINUES TO PUSH SOUTH INTO OK...WITH DRIER AIR PUSHING INTO MOST
LOCATIONS. THIS DRIER AIR WILL ALSO LEAD TO A DIMINISHING CLOUD
TREND FOR MOST OF CEN KS LATE AFTN INTO THIS EVE.
KETCHAM
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 90 64 88 64 / 100 10 0 0
HUTCHINSON 89 63 87 63 / 100 10 0 0
NEWTON 89 63 86 62 / 100 10 0 0
ELDORADO 90 64 86 62 / 90 10 0 0
WINFIELD-KWLD 95 65 89 64 / 30 10 0 0
RUSSELL 87 59 87 62 / 40 0 0 0
GREAT BEND 88 62 88 62 / 40 0 0 0
SALINA 89 61 87 62 / 30 0 0 0
MCPHERSON 89 62 87 62 / 30 0 0 0
COFFEYVILLE 95 66 88 64 / 30 10 0 0
CHANUTE 92 64 86 63 / 30 10 0 0
IOLA 91 63 86 62 / 30 10 0 0
PARSONS-KPPF 94 65 87 63 / 30 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1109 AM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 1108 AM CDT SUN SEP 1 2013
COOL FRONTAL BOUNDARY CONTINUES TO SLOWLY PUSH INTO SRN KS AT
THIS TIME. CURRENTLY LOCATED FROM KDDC-KPTT TO JUST SOUTH OF KICT
TO NEAR KCNU. SOME WIDELY SCT SHOWERS OR SPRINKLES ARE LOCATED
ALONG THE FRONT...WITH MORE WIDESPREAD SHOWERS OVER ERN KS. EXPECT
THIS FRONTAL BOUNDARY TO CONTINUE TO PUSH SOUTH INTO EXTREME SRN
KS EARLY THIS AFTERNOON...AND EVENTUALLY PUSH INTO OK BY LATE THIS
AFTERNOON/EARLY THIS EVENING. THE DRIER AIR ASSOCIATED WITH THIS
BOUNDARY IS LAGGING BEHIND SOMEWHAT...WITH SFC DEWPOINTS IN CEN KS
FALLING INTO THE LOW 60S. STILL SEEING SOME HIGHER SFC DWPTS OVER
SOUTHEAST KS...CLOSER TO THE MAIN BOUNDARY.
EXPECT THE MAIN SHORTWAVE OVER NE NEB TO DROP SOUTHEAST INTO ERN KS
AS THE AFTERNOON PROGRESSES. AS THIS INCREASED LIFT MOVES INTO SERN
KS...THINK SOME REINVIGORATED SHOWERS/STORMS WILL DEVELOP WHERE THIS
HIGHER SFC DWPT AIR AND UNSTABLE AIRMASS WILL BE LOCATED. SO WILL
KEEP THE HIGHEST POPS ALONG THE KS/OK BORDER AND ESPECIALLY FOR SERN
KS FOR THE LATE AFTERNOON HOURS. THINK THERE IS A SMALL WINDOW OF
OPPORTUNITY FOR STORMS TO DEVELOP...AS THE DRIER AIR PUSHES INTO SRN
KS...AND EVENTUALLY WITH THE FRONT DROPPING SOUTH INTO OK. SO
THINK BY THE LATE AFTERNOON/EARLY EVENING HOURS...MOST OF THE
CONVECTIVE CHANCES WILL DROP SOUTH OF THE AREA INTO OK. CURRENT
POPS/GRIDS HAVE THIS TREND WILL IN HAND...WITH ONLY SOME MINOR
TWEAKS FOR TIMING.
KETCHAM
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION
OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS
EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS
EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN
NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM
PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR
TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH
CENTRAL/SOUTHEAST KS.
THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT
MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL
MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A
RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE
FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD
OF THE FRONT.
COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO
TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY
NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS.
JMC
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 239 AM CDT SUN SEP 1 2013
THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL
ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO
THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES
TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN
RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS
VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH.
THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME.
JMC
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 640 AM CDT SUN SEP 1 2013
SCATTERED SHOWERS/THUNDERSTORMS ARE WEAKENING AT 12Z TAF ISSUANCE.
HAVE INCLUDED A BRIEF PERIOD OF -SHRA IN TEMPO GROUPS FOR KRSL AND
KSLN...BUT THE OUTLOOK FOR WIDESPREAD RAIN IS NOT GOOD. THE HRRR
CONTINUES TO DIMINISH THE PRECIPITATION EXPANSE AS THE FRONT MOVES
SOUTHWARD. THUS...IF KHUT/KICT OR KCNU SEES PRECIPITATION AN
AMENDMENT WILL BE NEEDED.
THE FRONT IS JUST BEHIND THE MAIN CONVECTION/SHOWER LINE. WINDS
WILL SWITCH AROUND TO THE NORTH THIS MORNING AND ARE EXPECTED TO
STAY FROM THE NORTH SWITCHING FROM NORTHWEST TO NORTHEAST THROUGH
THE DAY. MID-HIGH CLOUDS WILL PERSIST UNTIL EVENING AS THE FRONT
EXITS TO THE SOUTH. VFR CONDITIONS ARE EXPECTED TO PREVAIL.
BILLINGS
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 90 64 88 64 / 100 10 0 0
HUTCHINSON 89 63 87 63 / 100 10 0 0
NEWTON 89 63 86 62 / 100 10 0 0
ELDORADO 90 64 86 62 / 90 10 0 0
WINFIELD-KWLD 95 65 89 64 / 30 10 0 0
RUSSELL 87 59 87 62 / 40 0 0 0
GREAT BEND 88 62 88 62 / 40 0 0 0
SALINA 89 61 87 62 / 30 0 0 0
MCPHERSON 89 62 87 62 / 30 0 0 0
COFFEYVILLE 95 66 88 64 / 30 10 0 0
CHANUTE 92 64 86 63 / 30 10 0 0
IOLA 91 63 86 62 / 30 10 0 0
PARSONS-KPPF 94 65 87 63 / 30 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1236 PM CDT Sun Sep 1 2013
.UPDATE...
ISSUED AT 1235 PM CDT SUN SEP 1 2013
Beginning to be concerned for severe weather potential across
southern Illinois this afternoon. Although the original convection
moving through central Missouri has dissipated, the convective
mesoscale vort center is now very obviously moving east southeast
toward our region, and a few strong cells have developed just
ahead it just southwest St Louis. Lots of sunshine and warming
over the northern half of the southern Illinois should provide
plenty of instability for the convectively generate disturbance to
work with this afternoon. Increased pops to around 40 percent for
scattered storms over much of southern Illinois. Also backed off
temperatures a few degrees over much of southern Illinois and the
Evansville Tri State area.
UPDATE ISSUED AT 1212 PM CDT SUN SEP 1 2013
Update for 18z aviation.
UPDATE ISSUED AT 1208 PM CDT SUN SEP 1 2013
Major update to all public products has just been sent. Looks like
southeast Missouri may see scattered showers and thunderstorms
through much of the day, as west southwesterly low-level flow
continues to bang into the old outflow boundary. The severe storm
complex over central Missouri is finally weakening, and would
expect that trend to continue per the latest HRRR forecast. May
see some anvil debris spread into our northwest counties through
early afternoon, but do not expect this area to bodily move into
our region this afternoon.
The other concern is the Heat Advisory. Used a combination of the
HRRR, which has a decent handle on the hot temperatures in the
sunny northern portions of the area, and the 00Z ARW WRF which has
the best handle I could find on the clouds, convection and
temperatures over the south/southwest.
Tried to indicate some decrease in cloud cover over the southwest,
but kept temperatures in the middle 80s. Of course if the
convection continues to stream over that area, the associated
cloud cover may hold them down even more. Feel that the chance of
a massive outbreak of sunshine over in that area is not likely, so
have removed much of that area from the Heat Advisory.
Over the north, not sure how much of an impact last night`s
convection will have on high temperature potential with plentiful
sunshine this afternoon. Decided to use the HRRR as a guide and
go with mid 90s over this area, which leads to heat indices in the
100 to 105 range.
Further adjustments will likely be needed this afternoon, so stay
tuned. Also, not sure what impact the persistent Missouri
convection will have on the thunderstorm potential across the area
tonight.
&&
.SHORT TERM...(Today through Tuesday Night)
ISSUED AT 306 AM CDT SUN SEP 1 2013
A slight challenge with forecast package through 7 am CDT, as
decent southwesterly flow aiding in decent surface thet-a
convergence along western edge of complex. This should support
renewed convective cell development westward along the upshear
component over the expanding cold pool. The NAM-WRF and SREF
guidance hint at this feature and continue to extend precipitation
chances to the south and west through the morning hours. As CAPE
increases duri9ng the afternoon, the focus of convection should
shift to just south of the frontal boundary by late afternoon,
aided by differential heating.
For tonight, was a little more generous with the coverage and PoPs
during the evening and early overnight hours. Once the forcing and
instability shift southward before daybreak on Monday, rain
chances should drop off quite rapidly along with significant
clearing.
The remainder of the short term forecast period should be dry and
slightly cooler as northerly flow builds into the region.
The last day of the heat advisory still looks good. Heat index
values should spike into the low 100`s between 1 pm and 6 pm CDT
ahead of the frontal boundary. See no reason to adjust the current
advisory in effect.
Anticipate the greatest severe threat will be late this afternoon and
into the early evening over Southern IL/Southeast MO. Main concern
for the remainder of the pre-dawn hours will be locally heavy
rain and isolated strong winds gusts.
.LONG TERM...(Wednesday through Saturday)
ISSUED AT 306 AM CDT SUN SEP 1 2013
The mid level flow pattern will be more typical of what we have
seen much of the summer, with the mean trof position over the east
CONUS and the ridge over the west U.S. Generally dry weather is
expected with temperatures slowly moderating each day back toward
normal for this time of year. A front is forecast to backdoor the
area Thur/Fri. But moisture profiles in both the GFS and ECMWF are
not too impressive at this time.
&&
.AVIATION...
ISSUED AT 1209 PM CDT SUN SEP 1 2013
Placed thunder mention in kevv and kowb for this afternoon with
clearing skies and mcv headed that way could see storms pre
frontal. Kept mention of thunder tonight for fropa all sites.
Low confidence in timing and coverage of precip. Also have wind
shift this evening for fropa and some fog mention mainly at kevv
and kowb due to the heavy rain that had already fallen there.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091.
MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076.
IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088.
KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016-
018>020.
&&
$$
UPDATE...DRS
SHORT TERM...Smith
LONG TERM...CN
AVIATION...KH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1212 PM CDT Sun Sep 1 2013
.UPDATE...
ISSUED AT 1208 AM CDT SUN SEP 1 2013
Update for 18z aviation.
Major update to all public products has just been sent. Looks like
southeast Missouri may see scattered showers and thunderstorms
through much of the day, as west southwesterly low-level flow
continues to bang into the old outflow boundary. The severe storm
complex over central Missouri is finally weakening, and would
expect that trend to continue per the latest HRRR forecast. May
see some anvil debris spread into our northwest counties through
early afternoon, but do not expect this area to bodily move into
our region this afternoon.
The other concern is the Heat Advisory. Used a combination of the
HRRR, which has a decent handle on the hot temperatures in the
sunny northern portions of the area, and the 00Z ARW WRF which has
the best handle I could find on the clouds, convection and
temperatures over the south/southwest.
Tried to indicate some decrease in cloud cover over the southwest,
but kept temperatures in the middle 80s. Of course if the
convection continues to stream over that area, the associated
cloud cover may hold them down even more. Feel that the chance of
a massive outbreak of sunshine over in that area is not likely, so
have removed much of that area from the Heat Advisory.
Over the north, not sure how much of an impact last night`s
convection will have on high temperature potential with plentiful
sunshine this afternoon. Decided to use the HRRR as a guide and
go with mid 90s over this area, which leads to heat indices in the
100 to 105 range.
Further adjustments will likely be needed this afternoon, so stay
tuned. Also, not sure what impact the persistent Missouri
convection will have on the thunderstorm potential across the area
tonight.
&&
.SHORT TERM...(Today through Tuesday Night)
ISSUED AT 306 AM CDT SUN SEP 1 2013
A slight challenge with forecast package through 7 am CDT, as
decent southwesterly flow aiding in decent surface thet-a
convergence along western edge of complex. This should support
renewed convective cell development westward along the upshear
component over the expanding cold pool. The NAM-WRF and SREF
guidance hint at this feature and continue to extend precipitation
chances to the south and west through the morning hours. As CAPE
increases duri9ng the afternoon, the focus of convection should
shift to just south of the frontal boundary by late afternoon,
aided by differential heating.
For tonight, was a little more generous with the coverage and PoPs
during the evening and early overnight hours. Once the forcing and
instability shift southward before daybreak on Monday, rain
chances should drop off quite rapidly along with significant
clearing.
The remainder of the short term forecast period should be dry and
slightly cooler as northerly flow builds into the region.
The last day of the heat advisory still looks good. Heat index
values should spike into the low 100`s between 1 pm and 6 pm CDT
ahead of the frontal boundary. See no reason to adjust the current
advisory in effect.
Anticipate the greatest severe threat will be late this afternoon and
into the early evening over Southern IL/Southeast MO. Main concern
for the remainder of the pre-dawn hours will be locally heavy
rain and isolated strong winds gusts.
.LONG TERM...(Wednesday through Saturday)
ISSUED AT 306 AM CDT SUN SEP 1 2013
The mid level flow pattern will be more typical of what we have
seen much of the summer, with the mean trof position over the east
CONUS and the ridge over the west U.S. Generally dry weather is
expected with temperatures slowly moderating each day back toward
normal for this time of year. A front is forecast to backdoor the
area Thur/Fri. But moisture profiles in both the GFS and ECMWF are
not too impressive at this time.
&&
.AVIATION...
ISSUED AT 1209 PM CDT SUN SEP 1 2013
Placed thunder mention in kevv and kowb for this afternoon with
clearing skies and mcv headed that way could see storms pre
frontal. Kept mention of thunder tonight for fropa all sites.
Low confidence in timing and coverage of precip. Also have wind
shift this evening for fropa and some fog mention mainly at kevv
and kowb due to the heavy rain that had already fallen there.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091.
MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076.
IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088.
KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016-
018>020.
&&
$$
UPDATE...DRS
SHORT TERM...Smith
LONG TERM...CN
AVIATION...KH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1108 AM CDT Sun Sep 1 2013
.UPDATE...
ISSUED AT 1108 AM CDT SUN SEP 1 2013
Major update to all public products has just been sent. Looks like
southeast Missouri may see scattered showers and thunderstorms
through much of the day, as west southwesterly low-level flow
continues to bang into the old outflow boundary. The severe storm
complex over central Missouri is finally weakening, and would
expect that trend to continue per the latest HRRR forecast. May
see some anvil debris spread into our northwest counties through
early afternoon, but do not expect this area to bodily move into
our region this afternoon.
The other concern is the Heat Advisory. Used a combination of the
HRRR, which has a decent handle on the hot temperatures in the
sunny northern portions of the area, and the 00Z ARW WRF which has
the best handle I could find on the clouds, convection and
temperatures over the south/southwest.
Tried to indicate some decrease in cloud cover over the southwest,
but kept temperatures in the middle 80s. Of course if the
convection continues to stream over that area, the associated
cloud cover may hold them down even more. Feel that the chance of
a massive outbreak of sunshine over in that area is not likely, so
have removed much of that area from the Heat Advisory.
Over the north, not sure how much of an impact last night`s
convection will have on high temperature potential with plentiful
sunshine this afternoon. Decided to use the HRRR as a guide and
go with mid 90s over this area, which leads to heat indices in the
100 to 105 range.
Further adjustments will likely be needed this afternoon, so stay
tuned. Also, not sure what impact the persistent Missouri
convection will have on the thunderstorm potential across the area
tonight.
&&
.SHORT TERM...(Today through Tuesday Night)
ISSUED AT 306 AM CDT SUN SEP 1 2013
A slight challenge with forecast package through 7 am CDT, as
decent southwesterly flow aiding in decent surface thet-a
convergence along western edge of complex. This should support
renewed convective cell development westward along the upshear
component over the expanding cold pool. The NAM-WRF and SREF
guidance hint at this feature and continue to extend precipitation
chances to the south and west through the morning hours. As CAPE
increases duri9ng the afternoon, the focus of convection should
shift to just south of the frontal boundary by late afternoon,
aided by differential heating.
For tonight, was a little more generous with the coverage and PoPs
during the evening and early overnight hours. Once the forcing and
instability shift southward before daybreak on Monday, rain
chances should drop off quite rapidly along with significant
clearing.
The remainder of the short term forecast period should be dry and
slightly cooler as northerly flow builds into the region.
The last day of the heat advisory still looks good. Heat index
values should spike into the low 100`s between 1 pm and 6 pm CDT
ahead of the frontal boundary. See no reason to adjust the current
advisory in effect.
Anticipate the greatest severe threat will be late this afternoon and
into the early evening over Southern IL/Southeast MO. Main concern
for the remainder of the pre-dawn hours will be locally heavy
rain and isolated strong winds gusts.
.LONG TERM...(Wednesday through Saturday)
ISSUED AT 306 AM CDT SUN SEP 1 2013
The mid level flow pattern will be more typical of what we have
seen much of the summer, with the mean trof position over the east
CONUS and the ridge over the west U.S. Generally dry weather is
expected with temperatures slowly moderating each day back toward
normal for this time of year. A front is forecast to backdoor the
area Thur/Fri. But moisture profiles in both the GFS and ECMWF are
not too impressive at this time.
&&
.AVIATION...
ISSUED AT 709 AM CDT SUN SEP 1 2013
With the 12z Sunday TAF issuance, kept all of the WFO PAH TAF
sites in VFR category at this time. Until convective activity
appears later on this afternoon and this evening, it is difficult
to pinpoint at this time for lowered visibilities and ceilings.
Utilized vicinity thunderstorm to approximate the time for
convective activity near the sites. Slightly lower cloud decks or
MVFR visibilities were added the KEVV/KOWB TAF`s to account for
the approach of the frontal boundary.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091.
MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076.
IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088.
KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016-
018>020.
&&
$$
UPDATE...DRS
SHORT TERM...Smith
LONG TERM...CN
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
146 PM EDT SUN SEP 1 2013
.SYNOPSIS...
A WEAK TROUGH OF LOW PRESSURE WILL PERSIST OVER THE AREA THROUGH
TONIGHT...AS HIGH PRESSURE REMAINS WELL OFF THE COAST. A COLD
FRONT WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL
PUSH ACROSS THE AREA TUESDAY MORNING. HIGH PRESSURE WILL BUILD
OVER THE MID ATLANTIC STATES LATE TUESDAY AND WEDNESDAY...BRINGING
COOLER AND LESS HUMID CONDITIONS TO THE AREA BY MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1 PM UPDATE...A SMALL CONVECTIVE VORT MAX APPEARS ON STLT TO BE
MOVING ACROSS THE LOWER EASTERN SHORE. THIS MAY TRIGGER A FEW
SHOWERS OR TSTMS THROUGH 18Z NEAR THE MD COAST WITH 30 POP THROUGH
18Z THEN 20 POP REST THE AFTN. A SIGNIFICANT CU FIELD HAS DEVELOPED
ACRS NE NORTH CAROLINA AND EXTREME SOUTHEAST VIRGINIA IN THE SAME
AREA THAT HRRR AND ARW HAVE TSTMS DEVELOP EARLY THIS AFTN, HAVE
PLACED 30 PERCENT POPS FOR THE AFTN ACROSS A LARGE PART OF
SOUTHEAST VIRGINIA AND OUR NORTHEAST NORTH CAROLINA COUNTIES.
TEMPERATURES ARE RUNNING A BIT COOLER THAN EXPECTED OVER THE
PIEDMONT AREA AND CU FIELD HAD NOT BEGUN TO FORM AS OF 16Z. .
LOWERED MAX TEMPERATURES 1 TO 2 DEGREES AND LOWERED POPS TO 20
PERCENT THROUGH 20Z.
PREVIOUS DISCUSSION...
THE MAIN SHORT WAVE THAT WILL IMPACT THE AREA TOWARD EVENING WAS
PUSHING INTO EXTREME SOUTHWEST VIRGINIA AS OF 16Z. SIMILAR TO
SATURDAY...LEESIDE TROUGH WILL DEVELOP AS THE SHORT WAVE MOVES IN
FROM THE WEST, EXPECT TSTMS TO DEVELOP NEAR THE BLUE RIDGE WITH
CONVECTION SPREADING TO THE EAST TOWARD EVENING. CONTINUED WITH
POPS 30-40 PERCENT W OF INTERSTATE 95 DECREASING TOWARD THE COAST.
HIGH TEMPERATURES RANGE FROM THE UPR 80S TO AROUND 90 ACROSS MOST
AREAS,
PRECIPITIBLE WATER OF AROUND AN INCH AND THREE QUARTERS AND WEAK
STEERING CURRENTS MAY RESULT IN LOCALLY HEAVY RAINFALL AND MINOR
FLOODING. SOME TSTMS MAY PRODUCE GUSTY WINDS IN THE RANGE OF 30 TO
40 MPH. DUE TO RELATIVELY WEAK SHEAR...TSTMS SHOULD REMAIN
SCATTERED. AFT 00Z...SHOWERS AND SCATTERED TSTMS WILL LINGER INTO
THE EVENING AS THE SHORT WAVE MOVES ACRS NRN PORTIONS OF THE AREA.
KEPT POPS OF 30 TO 40 PERCENT N OF INTERSTATE 64 AND ACROSS THE
LOWER EASTERN SHORE THROUGH MIDNIGHT, BY MORNING...LOW TEMPERATURES
RANGE FROM 70 TO 75.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
INCREMENTAL INCREASE IN POPS CONTINUES ON MONDAY, AS UPPER TROUGH
PERSISTS AND SFC FRONT SLOWLY APPROACHES FROM THE W-NW. ONCE AGAIN
EXPECT SHOWERS TO FIRE UPSTREAM AND FILL IN ALONG PRE-FRONTAL
TROUGH, THOUGH DEVELOPING DOWNSLOPE FLOW AND CONTINUED ANEMIC DEEP
LAYER SHEAR VALUES WOULD ARGUE FOR WEAKER/LESS ORGANIZED CELLS.
EITHER WAY, DEEPER MOISTURE AND STRONGER DYNAMICS SUPPORT
INCREASED CHC FOR SHOWERS AND TSTMS BY LABOR DAY
AFTN/EVENING...AND WILL CARRY 50% POPS DURING THIS PERIOD.
TEMPERATURES ARE A BIT OF A CHALLENGE CONSIDERING INCREASING AFTN
CLOUDS AND RATHER STARK DIFFERENCE IN NUMERICAL GUIDANCE. ATTM,
THINKING IS THAT MAV (GFS) GUIDANCE IS TOO HIGH...AS IT HAS BEEN
NUMEROUS TIMES IN SIMILAR PRE-FRONTAL SITUATIONS. INCREASING
CLOUDS/AFTN PCPN SHOULD KEEP MAXIMA BELOW THESE VALUES, AND CLOSER
TO COOLER MET NUMBERS. DID ADJUST TEMPS UPWARD SLIGHTLY GIVEN
SLOWER FRONTAL TIMING...WITH HIGHS MONDAY GENERALLY IN THE LOWER
90S (MID-UPPER 80S ALONG IMMEDIATE COASTAL AREAS). WARM AND MUGGY
ONCE AGAIN MONDAY NIGHT, WITH EARLY MORNING LOWS IN THE LOWER TO
MIDDLE 70S.
TUESDAY...
HAVE GONE CLOSEST TO THE ECMWF SOLUTION FOR FRONTAL TIMING, WHICH
IS A GENERAL CONSENSUS OF THE MORE PROGRESSIVE 00Z GFS AND SLOWER
NAM SOLUTION. EXPECT THE FRONT TO BE ORIENTED FROM THE MD ERN
SHORE SW THROUGH SOUTH CENTRAL VA AT 12Z/8A TUE, WITH THE FRONT
SLOWLY SLIDING SE OFF THE COAST BY TUE EVENING (00Z WED/8PM TUES
NGT). UPPER JET LINGERS ALONG THE COAST HOWEVER, AND WITH UPPER
TROUGH AXIS PIVOTING OFFSHORE DURING THIS PERIOD, EXPECT THAT AT
LEAST SCATTERED SHRAS/TSTMS WL CONTINUE ACRS SE HALF OF THE AREA
THROUGH TUE AFTN...WITH LESS COVERAGE FARTHER N/W AS COOLER/DRIER
AIRMASS OF CANADIAN ORIGIN FILTERS IN FROM THE NW. HIGHS TUE WILL
AVG IN THE MID-UPPER 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY
STRONG MID LVL RIDGE OVER THE ROCKIES AND A MID LEVEL TROUGH OVER
THE EASTERN CONUS. HIGH PRESSURE BUILDS IN FROM THE NW TUE NIGHT-WED
IN THE WAKE OF SFC FROPA...AND PERSISTS OVER THE REGION INTO THU
AS THE DEEP UPPER TROUGH BECOMES ANCHORED OVER EASTERN CANADA.
EXPECT COOLER AND DRIER/MORE COMFORTABLE CONDITIONS WED WITH HIGHS
MAINLY 80-85. FLOW BRIEFLY TURNS BACK TO THE SW ON THU ALLOWING FOR
SOMEWHAT WARMER TEMPS INTO THE MIDDLE 80S AHEAD OF THE NEXT FRONT.
THIS FRONT LOOKS TO COME THROUGH THU NIGHT/EARLY FRI WITH MINIMAL
DYNAMICS SO WILL KEEP FORECAST DRY WITH JUST SOME INCREASE IN
CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/ HIGHS 80-84. MOISTURE MAY
START TO INCREASE AGAIN NEXT WEEKEND FOR SLIGHT CHC POPS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
NUMEROUS SHOWERS WITH EMBEDDED TSTRMS QUICKLY DVLPNG AS WEAK S/W
MOVES CROSS THE DELMARVA ALONG WITH A SFC TROF EXTENDING SW ACROSS
SERN VA / NC. THUS...HAVE INCLUDED VCSH ACROSS COASTAL TAF SITES
NEXT SEVRAL HRS. ADDITIONAL CONVECTION EXPECTED TO DVLP ACROSS THE
MTS THEN MOVE SE LATER THIS AFTRN. TIMING OF ANY CONVECTION AT RIC
PROBLEMATIC ATTM SO KEPT THEM DRY FOR NOW.
CONVECTION EXPECTED TO DISSIPATE AFTER SUNSET WITH VFR CONDITIONS
THROUGH THE NIGHT. HOWEVER...MODELS HINTING THAT SOME LATE NIGHT
FOG DEVELOPING...ESPECIALLY WHERE IT DOES RAIN. SO ADDED SOME MVFR
VSBYS FOR BR OVER INLAND TAF SITES.
ANOTHER ROUND OF SHOWERS / TSTRMS EXPECTED MONDAY AHEAD OF A COLD
FRONT THAT WILL BRING IN A LESS HUID AIRMASS INTO THE REGION BY
MID WEEK.
&&
.MARINE...
SURFACE AND MID LEVEL TROUGHING WILL RESIDE OVER THE REGION TODAY.
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE
INLAND TROUGH AND ARE EXPECTED TO MOVE OVER THE WATERS MAINLY THIS
EVENING...AND AFTER MIDNIGHT BECOMING MORE FOCUSED OVER NRN CHES
BAY/NRN COASTAL WATERS. S-SW WINDS OVER ALL WATERS WILL AVERAGE
10-15 KT TODAY AND TONIGHT...AND WAVES/SEAS WILL AVERAGE 1-3 FT
(POSSIBLY UP TO 4 FT OUT NEAR 20 NM EARLY MONDAY MORNING).
A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON
MONDAY. THIS WILL RESULT IN INCREASING SHOWER/THUNDERSTORM ACTIVITY
BY MONDAY EVENING AS THE FRONT BEGINS TO PUSH OVER THE WATERS. THE
FRONT SLOWLY PUSHES ACROSS THE WATERS ON TUESDAY AND STALLS ALONG
THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL ALSO BE POSSIBLE ON
TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW WINDS
MONDAY AND TUESDAY WILL AVERAGE 10-15 KT (UP TO 20 KT AT TIMES FOR
COASTAL WATERS)...THEN FINALLY VEER TO THE W-NW BEHIND THE FRONT
TUESDAY NIGHT. A COOL NW-N SURGE TUESDAY NIGHT INTO WEDNESDAY
MORNING MAY RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON
THIS REMAINS UNCERTAIN. HIGH PRESSURE RE-ESTABLISHES ITSELF OVER THE
MID ATLANTIC STATES FROM WEDNESDAY THROUGH AT LEAST SATURDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MAM
NEAR TERM...LSA
SHORT TERM...LKB/MAM
LONG TERM...JDM
AVIATION...MPR
MARINE...BMD
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1256 PM EDT SUN SEP 1 2013
.SYNOPSIS...
A WEAK TROUGH OF LOW PRESSURE WILL PERSIST OVER THE AREA THROUGH
TONIGHT...AS HIGH PRESSURE REMAINS WELL OFF THE COAST. A COLD
FRONT WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL
PUSH ACROSS THE AREA TUESDAY MORNING. HIGH PRESSURE WILL BUILD
OVER THE MID ATLANTIC STATES LATE TUESDAY AND WEDNESDAY...BRINGING
COOLER AND LESS HUMID CONDITIONS TO THE AREA BY MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1 PM UPDATE...A SMALL CONVECTIVE VORT MAX APPEARS ON STLT TO BE
MOVING ACROSS THE LOWER EASTERN SHORE. THIS MAY TRIGGER A FEW
SHOWERS OR TSTMS THROUGH 18Z NEAR THE MD COAST WITH 30 POP THROUGH
18Z THEN 20 POP REST THE AFTN. A SIGNIFICANT CU FIELD HAS DEVELOPED
ACRS NE NORTH CAROLINA AND EXTREME SOUTHEAST VIRGINIA IN THE SAME
AREA THAT HRRR AND ARW HAVE TSTMS DEVELOP EARLY THIS AFTN, HAVE
PLACED 30 PERCENT POPS FOR THE AFTN ACROSS A LARGE PART OF
SOUTHEAST VIRGINIA AND OUR NORTHEAST NORTH CAROLINA COUNTIES.
TEMPERATURES ARE RUNNING A BIT COOLER THAN EXPECTED OVER THE
PIEDMONT AREA AND CU FIELD HAD NOT BEGUN TO FORM AS OF 16Z. .
LOWERED MAX TEMPERATURES 1 TO 2 DEGREES AND LOWERED POPS TO 20
PERCENT THROUGH 20Z.
PREVIOUS DISCUSSION...
THE MAIN SHORT WAVE THAT WILL IMPACT THE AREA TOWARD EVENING WAS
PUSHING INTO EXTREME SOUTHWEST VIRGINIA AS OF 16Z. SIMILAR TO
SATURDAY...LEESIDE TROUGH WILL DEVELOP AS THE SHORT WAVE MOVES IN
FROM THE WEST, EXPECT TSTMS TO DEVELOP NEAR THE BLUE RIDGE WITH
CONVECTION SPREADING TO THE EAST TOWARD EVENING. CONTINUED WITH
POPS 30-40 PERCENT W OF INTERSTATE 95 DECREASING TOWARD THE COAST.
HIGH TEMPERATURES RANGE FROM THE UPR 80S TO AROUND 90 ACROSS MOST
AREAS,
PRECIPITIBLE WATER OF AROUND AN INCH AND THREE QUARTERS AND WEAK
STEERING CURRENTS MAY RESULT IN LOCALLY HEAVY RAINFALL AND MINOR
FLOODING. SOME TSTMS MAY PRODUCE GUSTY WINDS IN THE RANGE OF 30 TO
40 MPH. DUE TO RELATIVELY WEAK SHEAR...TSTMS SHOULD REMAIN
SCATTERED. AFT 00Z...SHOWERS AND SCATTERED TSTMS WILL LINGER INTO
THE EVENING AS THE SHORT WAVE MOVES ACRS NRN PORTIONS OF THE AREA.
KEPT POPS OF 30 TO 40 PERCENT N OF INTERSTATE 64 AND ACROSS THE
LOWER EASTERN SHORE THROUGH MIDNIGHT, BY MORNING...LOW TEMPERATURES
RANGE FROM 70 TO 75.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
INCREMENTAL INCREASE IN POPS CONTINUES ON MONDAY, AS UPPER TROUGH
PERSISTS AND SFC FRONT SLOWLY APPROACHES FROM THE W-NW. ONCE AGAIN
EXPECT SHOWERS TO FIRE UPSTREAM AND FILL IN ALONG PRE-FRONTAL
TROUGH, THOUGH DEVELOPING DOWNSLOPE FLOW AND CONTINUED ANEMIC DEEP
LAYER SHEAR VALUES WOULD ARGUE FOR WEAKER/LESS ORGANIZED CELLS.
EITHER WAY, DEEPER MOISTURE AND STRONGER DYNAMICS SUPPORT
INCREASED CHC FOR SHOWERS AND TSTMS BY LABOR DAY
AFTN/EVENING...AND WILL CARRY 50% POPS DURING THIS PERIOD.
TEMPERATURES ARE A BIT OF A CHALLENGE CONSIDERING INCREASING AFTN
CLOUDS AND RATHER STARK DIFFERENCE IN NUMERICAL GUIDANCE. ATTM,
THINKING IS THAT MAV (GFS) GUIDANCE IS TOO HIGH...AS IT HAS BEEN
NUMEROUS TIMES IN SIMILAR PRE-FRONTAL SITUATIONS. INCREASING
CLOUDS/AFTN PCPN SHOULD KEEP MAXIMA BELOW THESE VALUES, AND CLOSER
TO COOLER MET NUMBERS. DID ADJUST TEMPS UPWARD SLIGHTLY GIVEN
SLOWER FRONTAL TIMING...WITH HIGHS MONDAY GENERALLY IN THE LOWER
90S (MID-UPPER 80S ALONG IMMEDIATE COASTAL AREAS). WARM AND MUGGY
ONCE AGAIN MONDAY NIGHT, WITH EARLY MORNING LOWS IN THE LOWER TO
MIDDLE 70S.
TUESDAY...
HAVE GONE CLOSEST TO THE ECMWF SOLUTION FOR FRONTAL TIMING, WHICH
IS A GENERAL CONSENSUS OF THE MORE PROGRESSIVE 00Z GFS AND SLOWER
NAM SOLUTION. EXPECT THE FRONT TO BE ORIENTED FROM THE MD ERN
SHORE SW THROUGH SOUTH CENTRAL VA AT 12Z/8A TUE, WITH THE FRONT
SLOWLY SLIDING SE OFF THE COAST BY TUE EVENING (00Z WED/8PM TUES
NGT). UPPER JET LINGERS ALONG THE COAST HOWEVER, AND WITH UPPER
TROUGH AXIS PIVOTING OFFSHORE DURING THIS PERIOD, EXPECT THAT AT
LEAST SCATTERED SHRAS/TSTMS WL CONTINUE ACRS SE HALF OF THE AREA
THROUGH TUE AFTN...WITH LESS COVERAGE FARTHER N/W AS COOLER/DRIER
AIRMASS OF CANADIAN ORIGIN FILTERS IN FROM THE NW. HIGHS TUE WILL
AVG IN THE MID-UPPER 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY
STRONG MID LVL RIDGE OVER THE ROCKIES AND A MID LEVEL TROUGH OVER
THE EASTERN CONUS. HIGH PRESSURE BUILDS IN FROM THE NW TUE NIGHT-WED
IN THE WAKE OF SFC FROPA...AND PERSISTS OVER THE REGION INTO THU
AS THE DEEP UPPER TROUGH BECOMES ANCHORED OVER EASTERN CANADA.
EXPECT COOLER AND DRIER/MORE COMFORTABLE CONDITIONS WED WITH HIGHS
MAINLY 80-85. FLOW BRIEFLY TURNS BACK TO THE SW ON THU ALLOWING FOR
SOMEWHAT WARMER TEMPS INTO THE MIDDLE 80S AHEAD OF THE NEXT FRONT.
THIS FRONT LOOKS TO COME THROUGH THU NIGHT/EARLY FRI WITH MINIMAL
DYNAMICS SO WILL KEEP FORECAST DRY WITH JUST SOME INCREASE IN
CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/ HIGHS 80-84. MOISTURE MAY
START TO INCREASE AGAIN NEXT WEEKEND FOR SLIGHT CHC POPS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
SURFACE TO MID LEVEL TROUGHING RESIDES OVER THE MID ATLANTIC REGION
EARLY THIS MORNING AND IS EXPECTED TO REMAIN STEADFAST THROUGH TODAY.
THERE ARE PLENTY OF HIGH DEBRIS CLOUDS AND FEW-SCT MID LEVEL CU LEFT
FROM SHOWERS ON SATURDAY EVENING. VERY DIFFUSE DRY SLOTTING CAN BE
SEEN IN WATER VAPOR IMAGERY AND MAY LEAD TO SOME THINNING OF THE
BKN-OVC CIRRUS THROUGH THE MORNING. HOWEVER ONCE DAYTIME HEATING
BEGINS...EXPECT MORE CU DEVELOPMENT TO OCCUR FROM LATE MORNING INTO
THE AFTERNOON.
MEANWHILE...SHORTWAVE ENERGY FROM THE OHIO VALLEY WILL SLIDE CLOSER
TO THE APPALACHIANS AND INTERACT WITH THE TROUGHING CURRENTLY IN
PLACE. THIS WILL PROMOTE SHOWER/THUNDERSTORM DEVELOPMENT LATE THIS
AFTERNOON INTO THE EVENING...AND SHOULD RESULT IN PRECIPITATION
SHIFTING FARTHER EAST THAN THE DAY BEFORE. SHOWERS/STORMS MAY HAVE A
TOUGH TIME REACHING ALL THE WAY TO THE COAST DUE TO THE LOSS OF
DAYTIME HEATING BY THE TIME THE MOISTURE ARRIVES AND ALSO DUE TO
POSSIBLE DRY SLOTTING. KRIC AND KSBY HAVE THE BEST CHANCE OF
EXPERIENCING THUNDERSTORMS TODAY INTO TONIGHT...WHILE KPHF/KORF/KECG
MAY SEE A SHOWER OR TWO BUT THAT SHOULD BE IT. SHOWERS AND STORMS
SHOULD TAPER OFF QUICKLY AFTER MIDNIGHT...WITH LINGERING SHOWERS
POSSIBLE OVERNIGHT IN AREAS NE OF INTERSTATE 64 (INCLUDING THE MD/VA
EASTERN SHORE). SOUTH WINDS WILL BECOME BREEZY BY MID TO LATE
MORNING AS THE PRESSURE GRADIENT TIGHTENS UP AGAIN THROUGH THE
AFTERNOON.
A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON
MONDAY. THIS WILL RESULT IN INCREASED SHOWER/THUNDERSTORM CHANCES
AND COVERAGE BY MONDAY EVENING AS THE FRONT STARTS TO PUSH INTO THE
REGION. THE FRONT SLOWLY PUSHES ACROSS THE AREA ON TUESDAY AND
STALLS ALONG THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL BE POSSIBLE
ON TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW
WINDS FINALLY VEER TO THE W-NW BEHIND THE FRONT LATE TUESDAY. HIGH
PRESSURE RE-ESTABLISHES ITSELF OVER THE MID ATLANTIC STATES FROM
WEDNESDAY THROUGH AT LEAST SATURDAY.
&&
.MARINE...
SURFACE AND MID LEVEL TROUGHING WILL RESIDE OVER THE REGION TODAY.
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE
INLAND TROUGH AND ARE EXPECTED TO MOVE OVER THE WATERS MAINLY THIS
EVENING...AND AFTER MIDNIGHT BECOMING MORE FOCUSED OVER NRN CHES
BAY/NRN COASTAL WATERS. S-SW WINDS OVER ALL WATERS WILL AVERAGE
10-15 KT TODAY AND TONIGHT...AND WAVES/SEAS WILL AVERAGE 1-3 FT
(POSSIBLY UP TO 4 FT OUT NEAR 20 NM EARLY MONDAY MORNING).
A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON
MONDAY. THIS WILL RESULT IN INCREASING SHOWER/THUNDERSTORM ACTIVITY
BY MONDAY EVENING AS THE FRONT BEGINS TO PUSH OVER THE WATERS. THE
FRONT SLOWLY PUSHES ACROSS THE WATERS ON TUESDAY AND STALLS ALONG
THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL ALSO BE POSSIBLE ON
TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW WINDS
MONDAY AND TUESDAY WILL AVERAGE 10-15 KT (UP TO 20 KT AT TIMES FOR
COASTAL WATERS)...THEN FINALLY VEER TO THE W-NW BEHIND THE FRONT
TUESDAY NIGHT. A COOL NW-N SURGE TUESDAY NIGHT INTO WEDNESDAY
MORNING MAY RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON
THIS REMAINS UNCERTAIN. HIGH PRESSURE RE-ESTABLISHES ITSELF OVER THE
MID ATLANTIC STATES FROM WEDNESDAY THROUGH AT LEAST SATURDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MAM
NEAR TERM...LSA
SHORT TERM...LKB/MAM
LONG TERM...JDM
AVIATION...BMD
MARINE...BMD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
402 PM EDT SUN SEP 1 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 401 PM EDT SUN SEP 1 2013
12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PAIR OF VIGOROUS
SHRTWVS DIGGING THRU ONTARIO/LK SUP IN THE NW FLOW ALF BTWN RDG OVER
THE ROCKIES AND A TROF OVER ERN NAMERICA. WHILE DRYING ALF UNDER
DNVA/UPR CONFLUENCE/DEEP LYR QVECTOR DVGC IN THE WAKE OF THE MOST
IMPRESSIVE SHRTWV MOVING ACRS NRN LK SUP HAS ENDED THE SHRA OVER THE
SW CWA...MORE NMRS SHRA/TS IN THE COMMA TAIL IN ADVANCE OF RATHER
WEAK ATTENDANT COLD FNT...WHERE RUC ANALYSIS SHOWS KINX NOT FAR FM
40/STEEPER MID LVL LAPSE RATES/MUCAPE IN THE 500-1000J/KG RANGE...
ARE MOVING THRU THE ERN ZNS. MORE NMRS SHRA/TS ALSO IMPACTED THE
KEWEENAW EARLIER IN THE DAY CLOSER TO THE COMMA HEAD ASSOCIATED WITH
THIS SHRTWV. THE MAIN HAZARD FM ALL THE SHRA/TS HAVE BEEN HEAVY
DOWNPOURS...WHICH PROMPTED THE ISSUANCE OF AN URBAN/SMALL STREAM
FLOOD ADVY FOR THE KEWEENAW EARLIER IN THE AFTN FOLLOWING A REPORT
OF 2 INCHES OF RA IN AN HOUR NEAR CALUMET. EVEN THOUGH THERE HAS
BEEN DRYING ALF OVER THE W IN THE WAKE OF THE WEAK SFC COLD
FROPA...A FEW -SHRA HAVE DVLPD IN THIS AREA ALONG WITH SOME LO CLDS
AS LLVL MSTR SHOWN ON THE 12Z INL RAOB HAS OVERSPREAD THE AREA IN
THE NW LLVL FLOW IN THE WAKE OF THE SHRTWV. LARGE SCALE QVECTOR
DVGC/SUBSIDENCE IN THE WAKE OF THE DEPARTING SHRTWV HAVE TENDED TO
LIMIT THE INTENSITY OF THESE -SHRA. THERE IS A SHARPER SURGE OF COOL
AIR ASSOCIATED WITH THE SECOND SHRTWV DROPPING SSEWD IN NW ONTARIO.
LO CLDS ARE WIDESRPEAD TO THE NW OF LK SUP WITH SOME -RA/-DZ
REPORTED IN THE CYC FLOW ON THE NW FLANK OF SFC LO PRES MOVING THRU
LK SUP THAT ASSOCIATED WITH THE FIRST SHRTWV.
REST OF THIS AFTN/TNGT...EXPECT LINGERING SHRA/TS OVER THE ERN ZNS
LATE THIS AFTN TO SHIFT TO THE E FOLLOWING DEPARTURE OF AXIS OF HIER
RH/DEEP LYR QVECTOR CNVGC AND UNDER DEEP LYR QVECTOR DVGC BEHIND
DEPARTING FIRST SHRTWV. FOLLOWING THE PASSAGE OF REINFORCING COLD
FNT EARLY THIS EVNG ASSOCIATED WITH THE SECOND SHRTWV DIGGING THRU
ONTARIO...EXPECT WIDESPREAD LO CLD/SOME -DZ TO DVLP ESPECIALLY IN
THE UPSLOPE AREAS NEAR LK SUP AS LLVL NNW FLOW DRIVES NEAR SFC COOL
AIR INTO THE AREA AND SHARPENS INVRN BASE NEAR H9 AS SHOWN ON 12Z
LOCAL WRF ARW FCST SDNGS. THE COMBINATION OF GUSTY WINDS WITH H925
WINDS FCST UP TO 25-30 KTS AND THE ARRIVAL OF THE COOLER AIR WL MAKE
THE NGT FEEL QUITE CHILLY AS COMPARED TO THE WARM WX IN RECENT WEEKS.
LABOR DAY...MON WL FEATURE A CONFLUENT NW FLOW OVER THE UPR LKS/DEEP
LYR QVECTOR DVGC. MAIN FCST CONCERN IS HOW QUICKLY LO CLDS/-DZ WITH
SHALLOW MOIST LYR BLO SHARP LLVL INVRN WL DEPART. GIVEN THE
INTENSITY OF THE DISTURBANCES IN PLAY TODAY...PREFERRED TO FOLLOW
THE 12Z LOCAL WRF-ARW FCST SCENARIO...WHICH SHOWS MORE PERSISTENT
LLVL MSTR MAINTAINED BY STRONGER N WIND. BUT EVEN THIS MODEL
INDICATES SOME IMPROVEMENT IN THE AFTN ESPECIALLY OVER THE W HALF
WITH CLOSER APRCH OF SFC HI PRES/WEAKER AND MORE ACYC FLOW. EXPECT
THE RETURN OF AT LEAST SOME SUNSHINE IN THAT AREA AFT 18Z. TEMPS WL
RUN BLO NORMAL FOR THE FIRST TIME IN QUITE AWHILE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 401 PM EDT SUN SEP 1 2013
QUITE A TRANQUIL PERIOD OF WEATHER EXPECTED OVER THE NEXT WEEK AS
LARGE SCALE FEATURES TREND BACK TO THE EARLY SUMMER SET-UP OF A
WESTERN RIDGE AND EASTERN TROUGH. TEMPERATURES SHOULD BE AT TO
SLIGHTLY ABOVE NORMAL THROUGH THE WEEK.
MONDAY NIGHT THROUGH TUESDAY NIGHT...A STRONG MID-LEVEL SHORTWAVE
TROUGH AND AN ACCOMPANYING SFC LOW WILL BE OVER THE SOUTHEAST
ONTARIO AND QUEBEC BORDER AT THE START OF THE PERIOD...AND WILL BE
CONTINUING TO MOVE EAST MONDAY NIGHT. MEANWHILE...MID-LEVEL RIDGING
WILL BE BUILDING INTO THE UPPER MS VALLEY AS A SFC HIGH PRESSURE
SETTLES OVER OVER NW TO CENTRAL WI. MAIN QUESTIONS IN THIS TIME
FRAME REVOLVE AROUND DEPARTING LOW CLOUD COVER IN THE EAST...AND MIN
TEMPS FOR THE WEST.
INCREASINGLY DRIER AIR WILL CONTINUE ADVECTING INTO THE REGION FROM
THE NW AHEAD OF THE SFC HIGH. ATTM...IT APPEARS THAT LOW-CLOUDS
UNDER AN H8 INVERSION SHOULD DISSIPATE ENOUGH FROM INSOLATION AND
INCOMING DRY AIR TO RESULT IN MOSTLY CLEAR SKIES FOR THE WEST HALF.
THE EAST HALF IS A BIT MORE TRICKY...WITH THE NAM NON-SURPRISINGLY
KEEPING LOW STRATUS ACROSS THE AREA WELL INTO THE OVERNIGHT HOURS.
OVERALL...FEELING IS THAT CLOUDS WILL CLEAR OUT BY MIDNIGHT FOR THE
EAST.
WITH THE GRADIENT FLOW WEAKENING ACROSS THE WEST...AND PWAT VALUES
AROUND 0.5 INCHES...GOOD RADIATIONAL COOLING IS EXPECTED. HAVE
FORECAST TEMPS IN THE LOW 40S INTERIOR WEST...WITH EVEN A COUPLE
POCKETS OF UPPER 30S. LOWS SHOULD REMAIN AROUND 50 ALONG THE GREAT
LAKES...AND ACROSS THE EAST HALF WHERE GRADIENT FLOW REMAINS
STRONGER THROUGHOUT THE NIGHT.
BROAD RIDGING MOVES ACROSS THE UPPER GREAT LAKES ON TUESDAY...AND
WILL BRING SUNNY SKIES WITH TEMPS WARMING TO THE MID 70S. RETURN
FLOW ON THE BACKSIDE OF THE SFC HIGH ALONG WITH INCREASING MID-LEVEL
CLOUDS SHOULD KEEP TEMPS FROM FALLING OFF TOO MUCH TUESDAY...WITH
COLDEST LOWS ONLY IN THE UPPER 40S. PLENTY OF DRY AIR ABOVE THE
INVERSION SHOULD ALLOW RH VALUES TO FALL INTO THE MID 30S TO AROUND
40 FOR INTERIOR LOCATIONS...THOUGH WINDS WILL BE QUITE LIGHT.
WEDNESDAY...A STRENGTHENING SHORTWAVE ACROSS NORTHERN CANADA WILL
QUICKLY TRACK SOUTHEAST ACROSS NORTHERN MANITOBA ON TUESDAY...AND
SOUTHERN HUDSON BAY TUESDAY NIGHT INTO WEDNESDAY MORNING. AN
ASSOCIATED STRENGTHENING SFC LOW WILL SEND A COLD FRONT FROM NORTH
TO SOUTH ACROSS THE CWA LATE TUESDAY NIGHT INTO WEDNESDAY. NEARLY
ALL FORCING BY WAY OF MID-LEVEL Q-VECTOR CONVERGENCE WILL STAY WELL
NORTH AND EAST OF THE AREA. GIVEN LIMITED MOISTURE WITH THIS
SYSTEM...DO NOT EXPECT ANYTHING MORE THAN SOME SCATTERED TO BROKEN
MID-LEVEL CLOUDINESS. ONE EXCEPTION COULD BE A BRIEF BOUT OF
POST-FRONTAL UPSLOPE DRIZZLE ACROSS THE NORTH-CENTRAL CWA...BUT WITH
DRY AIR MOVING IN QUICKLY BEHIND THE FRONT...LEFT OUT OF THE FCST
FOR NOW.
THE ECMWF HAS BEEN ON THE FASTER END OF GUIDANCE WITH THE PASSAGE OF
THE FRONT...CLEARING MUCH OF THE CWA BY NOON. THE GFS HAD BEEN
SEVERAL HOURS SLOWER...NOT CLEARING THE CWA UNTIL MID TO LATE
AFTERNOON. HOWEVER...IT HAS TRENDED 3 TO 5 HOURS QUICKER OVER THE
LAST SEVERAL RUNS...AND NOW LINES UP MUCH BETTER WITH THE ECMWF.
WILL FOLLOW THE IDEA OF A QUICKER FRONTAL PASSAGE. STRENGTHENING
HIGH PRESSURE TRACKING SOUTHEASTWARD INTO THE UPPER MS VALLEY BEHIND
THE FRONT WILL INDUCE A MODEST ISALLOBARIC WIND COMPONENT AND BRING
A WINDOW OF BREEZY CONDITIONS WEDNESDAY MORNING...PRODUCING AN
ELEVATED SWIM RISK FOR WEDNESDAY.
WEDNESDAY NIGHT THROUGH SUNDAY...HIGH PRESSURE WILL SETTLE OVER THE
AREA WEDNESDAY NIGHT AND ALLOW TEMPS TO ONCE AGAIN FALL WELL INTO
THE 40S FOR INTERIOR LOCATIONS. DEEP TROUGHING IN THE WEST WILL
DEVELOP BY LATE IN THE WEEK AND DOMINATE THE PATTERN ACROSS THE NE
CONUS. A COUPLE OF WEAK SHORTWAVES WILL TRACK ALONG THE BACKSIDE OF
THIS TROUGH AND AFFECT THE CWA. TIMING AND STRENGTH ARE TYPICALLY
DIFFICULT TO PIN DOWN IN THIS TYPE OF FLOW REGIME...SO WILL USE
CONSENSUS FORECAST THROUGH THE WEEKEND. WITH THAT SAID...BEST CHANCE
TO SEE SOME ISOLATED SHOWERS AND A FEW THUNDERSTORMS WILL BE FRIDAY
AND FRIDAY NIGHT AS A COLD FRONT DROPS SOUTH THROUGH THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 123 PM EDT SUN SEP 1 2013
OVERALL MVFR/VFR CONDITIONS THIS AFTN WL FALL TO IFR AT ALL 3 SITES
BY THIS EVNG FOLLOWING THE PASSAGE OF A COLD FNT AND THE DVLPMNT OF
A GUSTY UPSLOPE NNW WIND UNDER A SHARPENING PRES GRADIENT. SOME
-DZ/SPRINKLES ARE LIKELY AS WELL. AS THE GRADIENT/ UPSLOPE WIND
COMPONENT DIMINISH LATE TNGT/MON MRNG...CONDITIONS WL GRDLY IMPROVE
TO MVFR AND ANY LGT PCPN WL END.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 401 PM EDT SUN SEP 1 2013
FOLLOWING A COLD FRONTAL PASSAGE LATE THIS AFTERNOON/EARLY
EVENING...EXPECT NNW WINDS UP TO 30 KTS TO DEVELOP OVER THE LAKE AND
CONTINUE INTO MON...WHEN A HI PRES APPROACHING THE UPPER LAKES WILL
CAUSE THE WINDS TO DIMINISH WEST-TO-EAST THRU MON NIGHT. LOOK FOR
LIGHTER WINDS ON TUE AS THE HI PRES MOVES OVER THE UPPER LAKES.
STRONGER NNW WINDS UP TO 25 KTS WILL DEVELOP OVER THE E HALF ON WED
FOLLOWING ANOTHER COLD FRONTAL PASSAGE. THEN WINDS SHOULD DIMINISH
QUICKLY THE REST OF THE WEEK AS ANOTHER HI PRES/WEAK PRES GRADIENT
MOVE OVER THE LAKE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
BEACH HAZARDS STATEMENT FROM 8 PM EDT THIS EVENING THROUGH LATE
MONDAY NIGHT FOR MIZ005-006.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GAYLORD MI
158 PM EDT SUN SEP 1 2013
.SYNOPSIS...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE
FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN
RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH
MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED
FOR THE REMAINDER OF THE WEEK.
&&
.UPDATE...
ISSUED AT 158 PM EDT SUN SEP 1 2013
POTENT SHORT WAVE AND ATTENDING SFC LOW CONTINUES TO ADVANCE
THROUGH UPPER MICHIGAN/LAKE SUPERIOR THIS AFTERNOON...ASSOCIATED
COLD FRONT TRAILS DOWN THROUGH EAST-CENTRAL WISCONSIN. NICE BATCH
OF SHOWERS/THUNDER ADVANCING INTO ROUGHLY THE NRN HALF OF THE CWA
RIGHT ALONG THE EASTERN FRINGE OF THE SHORT WAVE...AND WITHIN A
NARROW CORRIDOR OF INSTABILITY ABOUT TO PUSH THROUGH THE REGION.
CONVECTION IS WEAKENING...RUNNING OUT AHEAD OF THE STRONGEST
FORCING AND INTO DECREASED INSTABILITY DOWNSTREAM. BUT HAVE LONG
AGO UPDATED POPS TO HAVE A PERIOD OF CATEGORICAL PRECIP ACROSS THE
NRN PART OF THE CWA...TRAILING OFF TO NOTHING SOUTH OF M-72.
REST OF THE AFTERNOON...INITIAL BATCH OF PRECIP WILL WORK THROUGH
THE NORTH OVER THE NEXT FEW HOURS. COLD FRONT STILL HAS TO COME
THROUGH THE REGION. STRATUS IS STARTING TO THIN ACROSS NRN LOWER
MICHIGAN WITH TEMPS STARTING TO WARM NICELY. STILL THINK THERE
WILL BE A WINDOW OF OPPORTUNITY FOR CONVECTION LATER THIS
AFTERNOON AS THE FRONT/COOLING ALOFT PRESSES THROUGH THE REGION...
PARTICULARLY OVER NE LOWER MICHIGAN WHERE CONVERGENCE WILL BE
MAXIMIZED.
UPDATE ISSUED AT 1032 AM EDT SUN SEP 1 2013
OVERVIEW: COMPACT SHORT WAVE NOW ADVANCING THROUGH THE WESTERN
U.P./WESTERN LAKE SUPERIOR. ATTENDING SFC LOW LOCATED OVER THE
KEWEENAW PENINSULA AS OF 14Z WITH A COLD FRONT STRETCHING DOWN
THROUGH CENTRAL WISCONSIN. AHEAD OF THE FRONT...12Z GRB/APX
SOUNDINGS REVEAL A FAIRLY DRY LOWER LEVEL AIRMASS IN PLACE AND
SFC BASED CAP UP THROUGH AROUND 800 MB OR SO.
BUT...THERE IS A THIN RIBBON OF MODEST LOW LEVEL MOISTURE (850
THETA-E RIDGE) JUST ALONG THE FRONT IN CENTRAL WISCONSIN...
WRAPPING INTO THE LOW OVER LAKE SUPERIOR. COUPLED WITH COOLING
LOWER LEVELS WITH THE SFC FRONT AND UPPER WAVE...HAS PRODUCED A
NARROW CORRIDOR OF INSTABILITY THAT IS ADVANCING EASTWARD...
EVIDENCED BY THE BKN LINE OF CONVECTION THAT WRAPS ALONG THE
LEADING EDGE OF THE SHORT WAVE.
FORECAST FOR THIS AFTERNOON/EVENING IS COMPLICATED BY A NUMBER OF
FACTORS...INCLUDING...BUT NOT LIMITED TO...MORNING STRATUS AND FOG
THAT WILL MOST CERTAINLY INHIBIT HEATING AND INSTABILITY AT LEAST
FOR AWHILE...AS WELL AS SMALLER SCALE AFFECTS ON THE LOW LEVEL
WIND FIELD INDUCED BY THE LAKES THAT WILL IMPACT FRONTAL POSITION
AND ULTIMATELY LOW LEVEL CONVERGENCE.
THROUGH EARLY AFTERNOON...ONGOING CONVECTION UPSTREAM SHOULD
BASICALLY HIT A "CINH" WALL AS IT TRIES TO ADVANCE INTO THIS
CWA...ESSENTIALLY OUTRUNNING THE FORCING AND AFOREMENTIONED NARROW
CORRIDOR OF INSTABILITY. SO...EXPECT MUCH OF THE CURRENT ACTIVITY
TO FIZZLE. MAIN EXCEPTION...ACROSS UPPER MICHIGAN ALONG THE SHORT
WAVE TRACK WHERE STRONGEST QG-FORCING WILL PROBABLY SUSTAIN
SHOWERS INTO EASTERN UPPER MICHIGAN PAST LUNCH TIME.
THEN...UPSTREAM SFC FRONT WILL TRY TO ADVANCE INTO THE CWA DURING
THE COURSE OF THE AFTERNOON...ALTHOUGH DUE TO LAKE INDUCED CHANGES
IN THE LOW LEVEL WIND FIELD...FRONT AND ASSOCIATED LOW LEVEL
CONVERGENCE WILL LIKELY LOSE IT/S IDENTITY. FRONT MAY "JUMP" INTO
NORTHEAST LOWER MICHIGAN THIS AFTERNOON AIDED BY SE FLOW OF LAKE
HURON. PROVIDED WE CAN EVENTUALLY THIN OUT THE STRATUS AND FOG BY
EARLY-MID AFTERNOON...WE MIGHT BE ABLE TO GENERATE SOME
INSTABILITY AS THE AFOREMENTIONED LOWER LEVEL MOISTURE AXIS NOSES
UP THROUGH NE LOWER MICHIGAN ALONG THE FRONT. WILL SEE HOW THIS
GOES.
BUT AT THIS POINT...THE BEST PRECIP CHANCES THROUGH THIS EVENING
ARE SETTING UP FOR EASTER UPPER MICHIGAN (ALONG THE SHORT WAVE
TRACK)...AS WELL AS NORTHEAST LOWER...THAT IS IF WE CAN MUSTER
SOME HEATING AND DESTABILIZATION. CERTAINLY NOT A RAIN OUT EVENT
BY ANY STRETCH. BUT FOLKS MAKING OUTDOOR HOLIDAY PLANS SHOULD AT
LEAST PLAN FOR THE POTENTIAL FOR A PERIOD OF SHOWERS AND SOME
THUNDER...ESPECIALLY IN EASTERN UPPER AND NORTHEAST LOWER.
SEVERE THREAT...AGAIN INSTABILITY DEPENDENT. WIDESPREAD SEVERE WEATHER
NOT ANTICIPATED. BUT...MID LEVEL FLOW DOES INCREASE TO 35 TO 4O
KNOTS ALONG THE FRONT...LEADING TO SOME BULK SHEAR TO CAPITALIZE
ON. COMBINED WITH BACKED FLOW OFF LAKE HURON...ANY STORMS THAT
MANAGE TO DEVELOP IN NE LOWER MICHIGAN WILL BEAR SCRUTINY.
UPDATE ISSUED AT 703 AM EDT SUN SEP 1 2013
STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE
HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS
COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL
LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM
THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM
NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF
CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE
EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8
WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE
WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS
WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID
MORNING FOR EASTERN UPPER.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 352 AM EDT SUN SEP 1 2013
CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD
FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER
WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK.
MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH
THE FRONT.
CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR
NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD
FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR
NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE
ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS
SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A
WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN
UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL
CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS
WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING
TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR
MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN
SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS
ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK
ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A
MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY
AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER
50S TO LOWER HALF OF THE 60S FOR MOST.
TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS
WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN
UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN
MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO
START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z
BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET
TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S
IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS
LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD
THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL
CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE
WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE
EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN
LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL
HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS.
PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER
CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK
OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG)
FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL
THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS
AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE
FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT
30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT
HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A
LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH
STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT
NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT.
THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY
INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING
COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD
DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY.
LOW TEMPS TO FALL INTO THE 50S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT SUN SEP 1 2013
INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH
MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN
LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT
WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE
IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT
TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP
BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG
TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH
TEMPERATURES MONDAY THEN POPS TO END THE PERIOD.
LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS
AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS.
THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS
NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST.
ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD
COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE
LOWER 60S NORTH TO AROUND 70 SOUTHEAST.
MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED
AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S
TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE
70S.
WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE
AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO
PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM
AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH
HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S.
FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD
INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING
TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME
INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE
AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE
CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS
TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR
NORTH TO AROUND 80 SOUTH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 158 PM EDT SUN SEP 1 2013
LINE OF SHOWERS/THUNDER WILL IMPACT PLN OVER THE NEXT 1 TO 2
HOURS. OTHERWISE...VFR CIGS SLOWLY EMERGING ACROSS NRN LOWER
MICHIGAN. COLD FRONT EXPECTED TO SWING THROUGH THE REGION LATE
THIS AFTERNOON/EARLY EVENING AND MAY YET SPARK ADDITIONAL SHOWERS
AND STORMS ACROSS NRN LOWER MICHIGAN...ESPECIALLY NE LOWER
MICHIGAN. BEHIND THE FRONT...MUCH COOLER AIR WILL SPREAD INTO THE
REGION TONIGHT. THIS WILL LEAD TO ABUNDANT STATUS EXPANDING DOWN
INTO THE REGION DURING THE OVERNIGHT PERIOD THAT WILL PERSIST
THROUGH MUCH OF LABOR DAY.
WINDS TURN NORTHWEST TONIGHT WITH SOME GUSTINESS THROUGH THE DAY
MONDAY.
&&
.MARINE...
ISSUED AT 352 AM EDT SUN SEP 1 2013
A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL
TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE
BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF
SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD
FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE
NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE
GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE
LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS.
THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN
NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER
BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EDT MONDAY
FOR LMZ323-342-344>346.
LS...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EDT MONDAY
FOR LSZ321.
&&
$$
UPDATE...BA
SYNOPSIS...AS
SHORT TERM...SD
LONG TERM...AS
AVIATION...BA
MARINE...SD
AREA FORECAST DISCUSSION
NWS ELKO NV
200 PM PDT SUN SEP 1 2013
.SYNOPSIS...MONSOON MOISTURE WILL INCREASE ACROSS NEVADA TONIGHT
THROUGH MONDAY...WITH SHOWERS AND THUNDERSTORMS BECOMING
INCREASINGLY LIKELY. SOME STORMS WILL PRODUCE HEAVY RAIN AND
LOCALIZED FLOODING. MONSOON MOISTURE IS EXPECTED TO LINGER FOR
MUCH OF THIS WEEK.
&&
.SHORT TERM...TONIGHT THROUGH TUESDAY.
AN IMPRESSIVE SURGE OF MONSOON MOISTURE IS ORGANIZING ACROSS
CENTRAL AND SOUTHERN NEVADA THIS AFTERNOON, WHERE YET ANOTHER CROP
OF SCATTERED THUNDERSTORMS IS GETTING UNDERWAY. 12Z NAM AND THE
3KM-HRRR BOTH SPREAD NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHERN HALF OF THE CWA /WHITE PINE, NYE, SOUTHERN LANDER/EUREKA
COUNTIES/ THROUGH THIS EVENING. VISIBLE SATELLITE REVEALS
PERCOLATING CUMULUS ON THE HIGHER TERRAIN OF CENTRAL NEVADA, WITH
SPC MESOANALYSIS REVEALING LIFTED INDEX TO -5 AND CAPE TO
1500 J/KG, AND THAT`S ONLY AS OF NOON. EXTRA MOISTURE IN THE AIR
SEEMS TO BE SLOWING HEATING SOMEWHAT, AND SOME WARMER AIR ALOFT IS
NOT HELPING EITHER. BUT THUNDERSTORMS ARE EXPECTED THROUGH THIS
EVENING NONETHELESS. WILL MAINTAIN FLASH FLOOD WATCH FOR CENTRAL
NEVADA THROUGH 11 PM, WHERE THE GREATEST CONCENTRATION OF STORMS
WILL BE LOCATED. 3KM HRRR FORECASTS A COMPLEX OF THUNDERSTORMS
ENTERING SOUTHERN ELKO COUNTY WITH THE MAIN MOISTURE SURGE AROUND
MIDNIGHT TONIGHT. KEPT SHOWER AND THUNDERSTORM COVERAGE MUCH
HIGHER TONIGHT THAN IS TYPICAL, WITH LOCALLY HEAVY RAIN LIKELY.
WILL LET THE FLASH FLOOD WATCH EXPIRE AT 11 PM FOR NOW, BUT
CONFIDENT THE CONVECTION WILL NOT END THEN, SO THE EVENING SHIFT
WILL NEED TO DETERMINE WHETHER TO EXTEND THE WATCH THROUGH
TONIGHT. MOISTURE QUALITY WILL BE INCREASING DRAMATICALLY TONIGHT
THROUGH MONDAY MORNING, AND WITH GFS/NAM BOTH FORECASTING
SIGNIFICANT INSTABILITY OVERNIGHT INTO MONDAY MORNING, NOCTURNAL
CONVECTION IS LIKELY. FURTHER AIDING THE THUNDERSTORMS WILL BE THE
ADVERTISED WEAK SHORTWAVE, ROTATING NORTH THROUGH EASTERN NEVADA
IN THE MOIST MONSOON FLOW, AND APPROACHING ELKO COUNTY AROUND 5 AM
MONDAY. THIS IS THE MOST STABLE TIME OF DAY /THE CONVECTIVE
MINIMUM/ BUT DESPITE THIS, EXPECT SOME THUNDERSTORMS WILL SURVIVE
THE NIGHT.
WITH THE CLOUDS, RAIN, AND RAPIDLY INCREASING HUMIDITY LOW
TEMPERATURES LABOR DAY MORNING WILL BE VERY MILD AND WAY ABOVE
NORMAL, IN THE UPPER 50S AND LOWER 60S. SOME RECORD WARM OVERNIGHT
LOWS ARE LIKELY, ELKO`S RECORD FOR SEP 2ND IS 59 SET IN 1960. MY
FORECASTED LOW IS 61 DEGREES.
LABOR DAY...CLOUDY AND MOIST WITH SHOWERS AND THUNDERSTORMS
LIKELY. MOISTURE WILL BE PLENTIFUL WITH PRECIPITABLE WATER VALUES
NEAR RECORD LEVELS FOR EARLY SEPTEMBER, RANGING FROM 1-1.2 INCHES.
ANY STORMS THAT DEVELOP MONDAY WILL PRODUCE EXCESSIVE RAINFALL.
THE QUESTION IS, WILL THERE BE ENOUGH INSTABILITY FOR
THUNDERSTORMS TO REDEVELOP MONDAY? THE ANSWER FROM MANY MODELS,
THE 12/18Z NAM, 12Z GFS AND ECMWF IS A UNANIMOUS YES. ALL GUIDANCE
ALLOWS SCATTERED TO NUMEROUS THUNDERSTORMS TO REDEVELOP ACROSS
NEVADA MONDAY AFTERNOON AND EVENING, EVEN ALL THE WAY INTO
HUMBOLDT COUNTY. SOME FORECASTER CONCERNS REGARDING THIS SCENARIO:
1) THE SHORTWAVE THAT WILL HELP TRIGGER STORMS TONIGHT IS COMING
THROUGH NE NEVADA LATE TONIGHT AND EARLY MONDAY, NOT A GREAT TIME
TO GET STORMS GOING. IN FACT, SUBSIDENCE BEHIND THE DEPARTING WAVE
AND THE SINKING AIR ASSOCIATED WITH IT MAY HINDER THUNDERSTORM
GROWTH MONDAY AFTERNOON, AND 2) WE ARE GOING TO BE VERY MOIST.
SKIES WILL BE MOSTLY CLOUDY TO CLOUDY ALL DAY, AND IT MAY PROVE
DIFFICULT TO GET THE SUNSHINE NEEDED FOR NEW STORM INITIATION.
DESPITE THESE CONCERNS, FORECASTED SCATTERED TO NUMEROUS
THUNDERSTORMS FOR ALL ZONES MONDAY. BECAUSE OF THE UNCERTAINTIES,
WILL NOT ISSUE ANOTHER FLASH FLOOD WATCH FOR MONDAY, BUT THIS WILL
REQUIRE CAREFUL WATCHING, ESPECIALLY GIVEN THE OUTDOOR HOLIDAY
ACTIVITIES. FOR NOW, SORT OF TOOK A MIDDLE GROUND AND MENTIONED
HEAVY RAIN IN THE GRIDS FOR NE NEVADA. AGAIN, WITH NEAR RECORD PW
IN THE ATMOSPHERE, ANY STORM WILL PRODUCE VERY HEAVY RAIN.
NOT THE BEST FORECAST FOR LABOR DAY PLANS, BUT DOUBT MANY WILL
COMPLAIN AS THE NEVADA DROUGHT CONTINUES.
TUESDAY...CONTINUED MOIST AND UNSTABLE. PW REMAINS VERY HEALTHY,
RANGING FROM 0.80-1.2 INCH. 12Z GFS FORECASTS WIDESPREAD NEGATIVE
LIFTED INDICES AT 5 PM TUESDAY, SO INCREASED THUNDERSTORM COVERAGE IN
THE GRIDS ACCORDINGLY. TURNER
.LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY. MODELS AGREE FAIRLY
WELL WITH THE OVERALL PATTERN THROUGH THE PERIOD. THE CWA IS UNDER
THE INFLUENCE OF THE "MONSOON" MOISTURE TUESDAY NIGHT THROUGH
THURSDAY...HOWEVER UPPER TROF PUSHES INLAND SHOVING THE TSTM
ACTIVITY TO EASTERN NV ON THURSDAY. BY FRIDAY TROF WEAKENS OVER
THE CWA AS IT MOVES NORTH INTO THE PACIFIC NORTHWEST. AGAIN THE
TSTM ACTIVITY IS EXPECTED TO BE CONFINED TO EASTERN NV. BY
SATURDAY INSTABILITY IS PUSHED INTO WHITE PINE COUNTY AS TROF
MOVES TO THE NORTH OF NEVADA. THEN EXPECT DRY CONDITIONS NEXT
SUNDAY AS FOUR CORNER HIGH GETS SUPPRESSED. JH
&&
.AVIATION...VFR ALL TERMINALS. KWMC AND KEKO WILL SEE PERIODIC SMOKY
CONDITIONS...BUT IS NOT EXPECTED TO REDUCE SURFACE VSBY. KEKO WILL
ALSO HAVE VCTS THIS EVENING AND MONDAY AFTERNOON. KTPH AND KELY MAY
HAVE -TSRA THROUGH EARLY EVENING. KELY MAY SEE HEAVY RAIN AT
TIMES. JH
&&
.FIRE WEATHER...SCATTERED TO NUMEROUS THUNDERSTORMS THIS AFTERNOON
THROUGH MONDAY. WHILE LIGHTNING WILL BE PLENTIFUL, WETTING RAINS
AND MUCH HIGHER RH WILL MINIMIZE THE RISK FOR NEW LIGHTNING
IGNITIONS. RETURNING MONSOON MOISTURE WILL ALLOW FOR MUCH HIGHER
MAX/MIN RH AND GREAT OVERNIGHT RECOVERIES. TURNER
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 11 PM PDT THIS EVENING FOR NORTHEASTERN
NYE COUNTY...NORTHWESTERN NYE COUNTY...SOUTHERN LANDER COUNTY
AND SOUTHERN EUREKA COUNTY...WHITE PINE COUNTY.
&&
$$
99/87/87/99
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
957 AM PDT SUN SEP 1 2013
.SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY
ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS
OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN
BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE
END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS
VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL
LEVELS BY THE MIDDLE OF THE WEEK.
&&
.UPDATE...MAIN CONCERN FOR TODAY IS WHETHER TO EXPAND THE FLASH
FLOOD WATCH INTO DEATH VALLEY NATIONAL PARK. WATER VAPOR LOOP SHOWED
MID LEVEL MOISTURE GRADIENT SURGING NORTH...POSSIBLY FOCUSING STORMS
FARTHER NORTH THAN DVNP LATER IN THE DAY. CONFIDENCE IS NOT HIGH
ENOUGH TO JUSTIFY EXPANSION...SO WILL STAND PAT FOR NOW. NO CHANGES
AT THIS TIME.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 304 AM PDT SUN SEP 1 2013
.SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS
MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS
ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT
PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME
HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS
MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN
WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE
COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH
THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE
FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS
CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH
THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF
THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER
TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY
CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH
OF THE NORTHWEST CWFA.
FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST
COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE
THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE
IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO
DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING
INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB
THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K
ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO
MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE
CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A
WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A
POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST
ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH
MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN
KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE
SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS
FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF
TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST
EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW
THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL
REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL
DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY,
AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY
TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO
THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1
FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS.
ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST
THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE
MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE
COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE
TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER
SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH
WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE
SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN
SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS
EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE
WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS
MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE
VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN.
TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT
WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER.
FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW
ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE
ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST
OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER,
IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT
WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE
MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER.
ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS
GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE
THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO
WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL
PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH
FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS
WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED
THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR
A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM
FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A
WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE
FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE
THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA.
GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR
MOST OF THE LONG TERM.
.AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS
AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K
FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP
IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON
TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND
ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY
SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS.
THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH
TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING
MOUNTAINS TOWARD THE AIRPORT COMPLEX.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS
FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY
SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND
NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED
AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY
MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND
WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH
TONIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022.
FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR NVZ014.
AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036.
CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS
EVENING FOR CAZ519>521.
&&
$$
MORGAN/STACHELSKI/HARRISON
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1140 AM MDT SUN SEP 1 2013
.AVIATION...
18Z TAF CYCLE
MORE CONVECTIVE ACTIVITY EXPECTED TODAY AS BACKDOOR SFC FRONT
GETS STORMS GOING ERN PLAINS AND CENTRAL MTNS EARLY THIS AFTERNOON AND
STORMS AND SFC FRONT DEVELOP WWD INTO RG VALLEY LATE THIS AFTN AND
INTO WRN NM THIS EVENING/TONIGHT. ISOLD TO WDLY SCT MVFR CIGS/VSBY IN
SHRA/TSRA TO OCCASIONALLY OBSCURE HIGHER TERRAIN. CELL MOVEMENT
WILL BE SLOW AND SOMEWHAT ERRATIC DUE TO UPPER LEVEL HIGH PRESSURE
CENTER OVERHEAD. STORMS IN WRN NM WILL CONTINUE UNTIL BTWN 6Z-9Z
MONDAY AS A SOMEWHAT ORGANIZED LINE DEVELOPS AND PROPAGATES SLOWLY
WWD.
33
&&
.PREV DISCUSSION...324 AM MDT SUN SEP 1 2013...
...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR
DAY...
COLD FRONT APPEARS TO BE IN NORTHEASTERN CO
STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY
WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE
LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP
A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET
SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF
OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE
NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER
MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL
BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY
STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE
SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH
ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW
WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE
ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE
BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A
SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE
BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD
HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED.
LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS
EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS
CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY
MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH
SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING
THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR
WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR
DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE
SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40.
WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL
ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE
CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER
BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE
SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL
MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH
SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF
400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL
MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST
TOWARD TX.
TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT
MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH
THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO
CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING
TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT
WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH
WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE
MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED
ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP
SUBTROPICAL MOISTURE INTRUSIONS.
52
.FIRE WEATHER...
UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND
FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING
SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY.
WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS
STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM.
NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST
LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING
ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS
BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON.
NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES
TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO
THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE
RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO
REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS
OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH
RECOVERIES ANTICIPATED.
CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE
CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A
BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO
SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO
POOR VENTILATION LIKELY OVER THE WEST AND NORTH.
A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY
PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING
WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER
HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING
TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES.
AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL
AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY.
WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST.
HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND
CENTRAL NM.
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHY
AREA FORECAST DISCUSSION
NWS RALEIGH NC
246 PM EDT SUN SEP 1 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...
THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE
WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM SUNDAY...
UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING
CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE
INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A
VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED
CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH
STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE
DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST
CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR
AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE
COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY
LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE
(IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE
NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE
INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO
MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL
THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT
CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP
LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF
CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA
BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S
TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS
TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 245 PM SUNDAY...
OVERVIEW:
CYCLONIC FLOW ALOFT WILL FURTHER STRENGTHEN ACROSS THE MID-
ATLANTIC AND CAROLINAS ON MON/MON NIGHT AS AN UPPER LEVEL LOW
AMPLIFIES ACROSS THE NORTHERN GREAT LAKES. AN ATTENDANT SFC LOW
WILL BE PRESENT ACROSS THE LOWER GREAT LAKES AND NORTHERN MID-
ATLANTIC...WITH A COLD FRONT EXTENDING SOUTHWEST FROM THE OH
VALLEY INTO THE LOWER MS RIVER VALLEY. THE COLD FRONT WILL
APPROACH THE SOUTHERN APPALACHIANS FROM THE NORTHWEST BY 12Z TUE.
PRECIP CHANCES:
EXPECT A THERMODYNAMIC ENVIRONMENT LARGELY SIMILAR TO TODAY ON MON
AFT/EVE...WITH THE POSSIBLE EXCEPTION OF SLIGHTLY STEEPER MID-
LEVEL LAPSE RATES ON THE ORDER OF 6.0-6.5 C/KM IN ADDITION TO A DRIER
MID-LEVEL AIRMASS...WHICH SHOULD CONTRIBUTE TO MLCAPE VALUES OF
1500-2500 J/KG AND DCAPE OF 1000-1250 J/KG AT PEAK HEATING.
FORCING FOR ASCENT MON AFT/EVE WILL CONSIST OF WEAK/SHALLOW LOW-
LEVEL CONVERGENCE ASSOCIATED WITH A SHARPENING LEE TROUGH...AND
DPVA ASSOC/W SMALL AMPLITUDE DISTURBANCES IN CYCLONIC FLOW
ALOFT...WHICH SHOULD BE MORE THAN ENOUGH TO RESULT IN SCATTERED TO
WIDESPREAD CONVECTION GIVEN MODERATE DIURNAL DESTABILIZATION AND
DEEP MOISTURE WITH PWAT VALUES OF ~1.75". THE EXACT TIMING AND
COVERAGE OF CONVECTION REMAINS DIFFICULT TO ASCERTAIN GIVEN THAT
IT WILL HIGHLY DEPEND ON THE PRECISE TIMING OF SMALL AMPLITUDE
DISTURBANCES ALOFT...AND PERHAPS FURTHER COMPLICATED BY THE
REMNANTS OF ANY UPSTREAM MCS ACTIVITY (IF SUCH ACTIVITY DEVELOPS
OVER THE TN VALLEY) LATE TONIGHT AND MONDAY MORNING...SIMILAR TO
THE PAST FEW DAYS. AT THIS TIME WILL MAKE LITTLE CHANGE TO THE
PREVIOUS FCST WITH PRECIP CHANCES ~50%. CHANCES SHOULD DECREASE
WITHIN SEVERAL HOURS AFTER SUNSET...THOUGH A SLIGHT TO LOW CHANCE
OF SHOWERS (PERHAPS AN ISOLD STORM) WILL PERSIST AFTER MIDNIGHT
GIVEN DEEP MOISTURE...MARGINAL NOCTURNAL INSTABILITY AND CYCLONIC
FLOW ALOFT.
TEMPERATURES:
HIGHS ON MON WILL BE SIMILAR TO BUT PERHAPS SLIGHTLY WARMER THAN
TODAY DEPENDING ON CLOUD COVER AND CONVECTION...IN THE UPPER 80S
TO LOWER 90S...OR 88-93F...WARMEST IN THE EAST. LOWS MON NIGHT
ABOVE NORMAL IN THE LOWER TO MID 70S GIVEN CLOUD COVER AND LIGHT
SOUTHERLY FLOW IN ADVANCE OF THE COLD FRONT APPROACHING THE
SOUTHERN APPALACHIANS.
SEVERE THREAT:
THE OVERALL ENVIRONMENT ON MON AFT/EVE WILL BE SIMILAR TO TODAY...
WITH SLIGHTLY STRONGER DEEP LAYER SHEAR (~20 KT) AND...PERHAPS MORE
IMPORTANTLY...SLIGHTLY STEEPER MID-LEVEL LAPSE RATES AND A DRIER
MID-LEVEL AIRMASS THAT WILL CONTRIBUTE TO STRONGER DCAPE DURING
PEAK HEATING. WITH THE ABOVE IN MIND...WILL INCLUDE MENTION IN THE
HAZARDOUS WEATHER OUTLOOK OF A POTENTIAL FOR ISOLD SEVERE STORMS
CAPABLE OF PRODUCING DAMAGING WINDS DURING THE AFT/EVE. IF FORCING
FOR ASCENT IS JUXTAPOSED WELL WITH PEAK HEATING AND DEVELOPMENT IS
LARGELY DELAYED UNTIL MID/LATE AFTERNOON...A BETTER SEVERE WIND
THREAT COULD EMERGE VIA ORGANIZATION ASSOC/W OUTFLOW GIVEN AN
ENVIRONMENT THAT WOULD FAVOR ROBUST COLD POOLS. -VINCENT
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 200 PM SUNDAY...
MORE AND MORE THE LONG TERM IS SHAPING UP TO BE AN EXTENDED PERIOD
OF DRY WEATHER CHARACTERIZED BY NEAR NORMAL TEMPERATURES FOR EARLY
SEPTEMBER. THE BEST CHANCE FOR RAIN COULD BE VERY EARLY ON IN THE
PERIOD AS AN UPPER TROUGH SITS OVER THE EAST COAST WITH A SURFACE
LOW MOVING THROUGH SOUTHERN QUEBEC. ON TUESDAY AFTERNOON THE MAIN
FRONTAL SYSTEM ASSOCIATED WITH THIS LOW SHOULD BE JUST EAST OF THE
CWA WITH REINFORCING BOUNDARY OVER THE APPALACHIANS. GFS FORECAST
SOUNDINGS IN BUFKIT INDICATE THAT AN ELEVATED MIXED LAYER WILL STILL
EXIST BUT WILL BECOME INCREASING CAPPED AS THE DAY GOES ON. THE BEST
CONDITIONS FOR ANY KIND OF SUSTAINED CONVECTION SHOULD BE FROM
FAYETTEVILLE SOUTH AND EAST. BACK TO THE WEST A LARGE SURFACE HIGH
WILL SLOWLY BUILD EASTWARD...ENFORCING MORE STABLE CONDITIONS WITH
TIME. WILL KEEP CHANCE POPS IN THE SOUTHEAST WITH SLIGHT CHANCE BACK
TO THE WEST. THIS SHOULD BE THE HOTTEST DAY OF THE LONG TERM AS THE
FULL EFFECTS OF THE FRONT WILL NOT BE REALIZED UNTIL WEDNESDAY.
HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES. LOWS IN THE LOWER 60S NW
TO UPPER 60S SOUTH.
WEDNESDAY THROUGH FRIDAY CENTRAL NC WILL BE UNDER A DOMINANT SURFACE
HIGH PRESSURE AND A VERY WEAK UPPER LEVEL FLOW REGIME BETWEEN THE
UPPER TROUGH TO THE NORTH AND THE VERY STRONG UPPER HIGH OVER THE
SOUTHWESTERN CONUS. WEATHER SHOULD REMAIN DRY AND HIGHS WILL BE IN
THE MID 80S WITH LOWS IN THE LOW TO MID 60S.
THE STRONG HIGH OVER THE SOUTHWESTERN CONUS WILL BEGIN TO BREAK DOWN
OVER THE WEEKEND AND A WEAK UPPER LEVEL LOW OVER THE DEEP SOUTH WILL
SLOWLY BEGIN TO ADVECT MOISTURE TOWARDS THE SOUTHWESTERN PORTIONS OF
OUR CWA. IT IS VERY POSSIBLE AT THIS POINT THAT THE WEEKEND COULD
REMAIN DRY BUT THE CHANCES FOR PRECIPITATION WILL CERTAINLY BE
GREATER THAN MIDWEEK. WILL CARRY SLIGHT CHANCE POPS SATURDAY AND
SUNDAY AFTERNOON WITH HIGHEST VALUES IN THE SOUTHWEST BUT STILL FEEL
LIKE SURFACE HIGH WILL KEEP WEATHER LARGELY DRY THROUGH THE END OF
THE LONG TERM. MAY SEE A VERY GRADUAL WARMING TOWARDS THE UPPER 80S
BY THE WEEKEND WITH LOWS TRENDING TOWARDS THE UPPER 60S.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 1200 PM SUNDAY...
24-HR TAF PERIOD:
MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS
CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT
THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL
CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W
SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE
POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY
MORNING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH
STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE
REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS
SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST
CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN
TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR
FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR
CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE
REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...RTE
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 PM EDT SUN SEP 01 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...
THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE
WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM SUNDAY...
UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING
CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE
INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A
VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED
CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH
STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE
DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST
CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR
AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE
COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY
LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE
(IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE
NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE
INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO
MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL
THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT
CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP
LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF
CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA
BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S
TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS
TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SUNDAY...
SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG
DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI
SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC
MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST
LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE...
THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY
NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID
LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL
MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT
1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW
DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES
TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR
INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG
FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW
CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW
AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY
AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS...
WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS
SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS...
ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15
KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY
CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY
AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN
CONVECTION DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF
COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR
TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS
MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430
M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR
90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A
LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 200 PM SUNDAY...
MORE AND MORE THE LONG TERM IS SHAPING UP TO BE AN EXTENDED PERIOD
OF DRY WEATHER CHARACTERIZED BY NEAR NORMAL TEMPERATURES FOR EARLY
SEPTEMBER. THE BEST CHANCE FOR RAIN COULD BE VERY EARLY ON IN THE
PERIOD AS AN UPPER TROUGH SITS OVER THE EAST COAST WITH A SURFACE
LOW MOVING THROUGH SOUTHERN QUEBEC. ON TUESDAY AFTERNOON THE MAIN
FRONTAL SYSTEM ASSOCIATED WITH THIS LOW SHOULD BE JUST EAST OF THE
CWA WITH REINFORCING BOUNDARY OVER THE APPALACHIANS. GFS FORECAST
SOUNDINGS IN BUFKIT INDICATE THAT AN ELEVATED MIXED LAYER WILL STILL
EXIST BUT WILL BECOME INCREASING CAPPED AS THE DAY GOES ON. THE BEST
CONDITIONS FOR ANY KIND OF SUSTAINED CONVECTION SHOULD BE FROM
FAYETTEVILLE SOUTH AND EAST. BACK TO THE WEST A LARGE SURFACE HIGH
WILL SLOWLY BUILD EASTWARD...ENFORCING MORE STABLE CONDITIONS WITH
TIME. WILL KEEP CHANCE POPS IN THE SOUTHEAST WITH SLIGHT CHANCE BACK
TO THE WEST. THIS SHOULD BE THE HOTTEST DAY OF THE LONG TERM AS THE
FULL EFFECTS OF THE FRONT WILL NOT BE REALIZED UNTIL WEDNESDAY.
HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES. LOWS IN THE LOWER 60S NW
TO UPPER 60S SOUTH.
WEDNESDAY THROUGH FRIDAY CENTRAL NC WILL BE UNDER A DOMINANT SURFACE
HIGH PRESSURE AND A VERY WEAK UPPER LEVEL FLOW REGIME BETWEEN THE
UPPER TROUGH TO THE NORTH AND THE VERY STRONG UPPER HIGH OVER THE
SOUTHWESTERN CONUS. WEATHER SHOULD REMAIN DRY AND HIGHS WILL BE IN
THE MID 80S WITH LOWS IN THE LOW TO MID 60S.
THE STRONG HIGH OVER THE SOUTHWESTERN CONUS WILL BEGIN TO BREAK DOWN
OVER THE WEEKEND AND A WEAK UPPER LEVEL LOW OVER THE DEEP SOUTH WILL
SLOWLY BEGIN TO ADVECT MOISTURE TOWARDS THE SOUTHWESTERN PORTIONS OF
OUR CWA. IT IS VERY POSSIBLE AT THIS POINT THAT THE WEEKEND COULD
REMAIN DRY BUT THE CHANCES FOR PRECIPITATION WILL CERTAINLY BE
GREATER THAN MIDWEEK. WILL CARRY SLIGHT CHANCE POPS SATURDAY AND
SUNDAY AFTERNOON WITH HIGHEST VALUES IN THE SOUTHWEST BUT STILL FEEL
LIKE SURFACE HIGH WILL KEEP WEATHER LARGELY DRY THROUGH THE END OF
THE LONG TERM. MAY SEE A VERY GRADUAL WARMING TOWARDS THE UPPER 80S
BY THE WEEKEND WITH LOWS TRENDING TOWARDS THE UPPER 60S.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 1200 PM SUNDAY...
24-HR TAF PERIOD:
MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS
CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT
THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL
CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W
SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE
POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY
MORNING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH
STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE
REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS
SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST
CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN
TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR
FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR
CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE
REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...ELLIS
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1234 PM EDT SUN SEP 01 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...
THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE
WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM SUNDAY...
UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING
CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE
INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A
VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED
CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH
STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE
DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST
CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR
AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE
COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY
LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE
(IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE
NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE
INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO
MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL
THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT
CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP
LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF
CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA
BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S
TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS
TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SUNDAY...
SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG
DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI
SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC
MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST
LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE...
THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY
NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID
LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL
MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT
1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW
DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES
TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR
INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG
FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW
CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW
AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY
AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS...
WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS
SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS...
ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15
KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY
CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY
AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN
CONVECTION DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF
COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR
TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS
MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430
M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR
90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A
LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 215 AM SUNDAY...
THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE
SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S.
TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE
THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL
WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND
SATURDAY.
THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND
TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM
IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL
TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT.
GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE
FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL
PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE
WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE
THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE
COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH
A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL
RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE
SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER
AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS
STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE
LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON
PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR
THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE
COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS
WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S.
FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH
PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT
PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC.
THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND
SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE
A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS
WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED
AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES
SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA
BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING
FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING
THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING
LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 1200 PM SUNDAY...
24-HR TAF PERIOD:
MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS
CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT
THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL
CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W
SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE
POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY
MORNING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH
STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE
REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS
SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST
CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN
TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR
FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR
CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE
REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS BISMARCK ND
118 PM CDT SUN SEP 1 2013
.UPDATE...
ISSUED AT 118 PM CDT SUN SEP 1 2013
NO SIGNIFICANT CHANGES WITH THIS FORECAST UPDATE. THE MORNING
STRATUS FIELD CONTINUES TO SLOWLY LIFT AND SCATTER AND EXPECT THIS
TREND TO CONTINUE THROUGH THE AFTERNOON...SUPPORTED BY THE 12 UTC
DETERMINISTIC LOW LEVEL MOISTURE FIELDS. OTHERWISE...THE FORECAST
IS ON TRACK.
UPDATE ISSUED AT 1013 AM CDT SUN SEP 1 2013
GIVEN VISIBLE SATELLITE TRENDS THROUGH 15 UTC...INCREASED CLOUD
COVER THROUGH 18 UTC AS THE BREAK UP AND LIFTING OF THE STRATUS
FIELD IS TAKING LONGER THAN PREVIOUSLY FORECAST. THIS IS
CONFIRMED BY THE 12 UTC HRRR LOW LEVEL CLOUD COVER FORECASTS.
OTHERWISE...THE REMAINDER OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 655 AM CDT SUN SEP 1 2013
NO SIGNIFICANT CHANGES MADE TO THE FORECAST. TEMPERATURES ARE
RUNNING A LITTLE WARMER THAN FORECAST AT LOCATIONS UNDER CLOUD
COVER. OTHERWISE...THE FORECAST IS ON TRACK. SATELLITE CONTINUES
TO SHOW CLOUDS PUSHING SOUTHWARD...ALMOST TO BISMARCK AT THIS
TIME. OBS INDICATING CEILINGS WITH THESE CLOUDS AROUND 1000-1500
FEET.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 301 AM CDT SUN SEP 1 2013
DRIER AND COOLER WEATHER WILL HIGHLIGHT THE SHORT TERM FORECAST.
CLOUD COVER EXTENT AND TIMING IS THE MAIN FORECAST CONCERN...AS THIS
WILL IMPACT MAXIMUM TEMPERATURES.
CURRENTLY...HIGH PRESSURE WAS CENTERED OVER SOUTHERN SASKATCHEWAN
WITH THE HIGH AXIS EXTENDING INTO EASTERN MONTANA. AN AREA OF
VFR/MVFR CLOUDS OVER SOUTHERN SASKATCHEWAN AND MANITOBA HAD EDGED
INTO NORTHERN NORTH DAKOTA.
MODELS WERE SUGGESTING THESE CLOUDS WILL MOVE SOUTH ACROSS THE STATE
THIS MORNING. THE HIGH CENTER IS FORECAST TO MOVE SOUTHEAST AND BY
EARLY AFTERNOON BE CENTERED OVER LAKE WINNIPEG INTO THE JAMES/RED
RIVER VALLEYS. NORTHWEST WINDS SHOULD BECOME NORTH...THEN NORTHEAST
INTO THE LATER MORNING HOURS. AS THE HIGH MOVES SOUTHEAST...MODELS
ARE SUGGESTING CLEARING SKIES NEAR THE HIGH CENTER AND ASSOCIATED
CLOUDS REMAINING ON THE WESTERN/SOUTHERN PERIPHERY OF THE HIGH LATER
THIS MORNING AND EARLY AFTERNOON TODAY BEFORE FINALLY DISSIPATING
DURING THE MID-LATE AFTERNOON HOURS. THIS WOULD RESULT IN CLEARING
SKIES OVER THE TURTLE MOUNTAINS...WITH PARTLY TO MOSTLY CLOUDY SKIES
OVER MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THROUGH EARLY
AFTERNOON...THEN SCATTERING OUT DURING THE MID-LATE AFTERNOON. THIS
RESULTS IN AFTERNOON HIGH TEMPERATURES A TAD LOWER THAN THE PREVIOUS
FORECAST. SO...HIGHS FROM THE UPPER 60S IN THE TURTLE MOUNTAINS TO
THE UPPER 70S IN THE SOUTHWEST.
TONIGHT CLEAR SKIES ARE EXPECTED. THE HIGH CENTER IS FORECAST TO
SETTLE OVER MINNESOTA AND THE FAR EASTERN DAKOTAS...WITH RETURN
SOUTHEASTERLY FLOW DEVELOPING OVER THE WESTERN DAKOTAS. THUS LOWER
MINIMUM TEMPERATURES OVER THE JAMES RIVER BASIN - CLEAR SKIES AND
LIGHT WINDS CLOSER TO THE HIGH CENTER - EXPECTING LOWS IN THE MID
40S. LOW TO MID 50S FOR LOWS IN THE WEST FARTHER FROM THE HIGH
CENTER AND WHERE SOUTHEASTERLY WINDS SHOULD KEEP THE LOWER
ATMOSPHERE MIXED SOMEWHAT AND KEEP THE TEMPERATURES FROM LOWERING
INTO THE 40S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 301 AM CDT SUN SEP 1 2013
MAJORITY OF THE EXTENDED PERIOD WILL BE DOMINATED BY STRONG RIDGE
THAT EXTENDS FROM AROUND NEW MEXICO THROUGH ALBERTA/SASKATCHEWAN.
LITTLE CHANGE IN THE PATTERN EXPECTED THROUGH MUCH OF THE WEEK
WITH THE RIDGE LOCATED BETWEEN DEEP UPPER LOW JUST OFF PAC NW
COAST AND TROUGH OVER EASTERN NORTH AMERICA. THIS WILL RESULT IN
MOSTLY DRY CONDITIONS AND TEMPERATURES RUNNING WELL ABOVE NORMAL
WITH HIGHS IN THE 80S TO LOW 90S.
TOWARD THE END OF THE WEEK THE PAC NW LOW BEGINS MOVING INLAND
REACHING MONTANA BY SAT NIGHT PER 00Z GFS/ECMWF. ONE WAVE
DEPICTED BY GFS/ECMWF RIDES RIDGE AND APPROACHES ND BY TUESDAY
RESULTING IN SOME LOW POPS FOR MAINLY WESTERN ND TUE AND TUE
NIGHT. BETTER LIKELIHOOD OF PRECIPITATION BY SATURDAY AS THE UPPER
LOW APPROACHES THE REGION. GFS/ECMWF INDICATE SURFACE LOW IN
VICINITY OF EASTERN MONTANA SATURDAY AFTERNOON LEAVING NORTH
DAKOTA IN WARM SECTOR WITH GFS INDICATING AXIS OF INSTABILITY
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 118 PM CDT SUN SEP 1 2013
THE MORNING STRATUS FIELD ACROSS WESTERN AND CENTRAL NORTH DAKOTA
CONTINUES TO LIFT AND SCATTER. THIS TREND WILL CONTINUE WITH VFR
CONDITIONS FOR THE 18 UTC TAFS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...JV
LONG TERM...JNS
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
303 PM EDT SUN SEP 1 2013
.SYNOPSIS...
UPPER LEVEL DISTURBANCES TODAY. COLD FRONT MONDAY NIGHT. COOLER
AND DRIER AIRMASS MID WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
WE WILL CONTINUE IN A WEST TO NORTHWEST FLOW ALOFT REGIME WITH UPPER
DISTURBANCES ROTATING ACROSS THE REGION. ALTHOUGH THE ATMOSPHERE IS
VERY MOIST AND CONDITIONALLY UNSTABLE...THE PROSPECT FOR CONVECTION
STILL DEPENDS ON MESOSCALE INFLUENCES. THE MOST DOMINANT INFLUENCE
WITH THIS OVERALL PATTERN OVER THE PAST 36 HOURS HAS BEEN THE VERY
WELL DEFINED LOW LEVEL BOUNDARY FROM PREVIOUS CONVECTION THAT HAS
BEEN LAID OUT WELL TO THE SOUTH OVER THE TENNESSEE VALLEY REGION
ON INTO SOUTHWEST VIRGINIA. THIS HAS ESTABLISHED THE MAIN BAND OF
CONVECTION WITHIN THIS PATTERN TO REMAIN MOSTLY SOUTH OF OUR AREA.
THUS...EVEN WITH A WELL DEFINED VORT MAX LIFTING UP ACROSS THE
AREA THIS AFTERNOON AND EARLY EVENING...MOST OF THE ORGANIZED
CONVECTION WITH THIS FEATURE WILL REMAIN OVER THE SOUTHERN AND
CENTRAL MOUNTAINS. ELSEWHERE...ONLY SCATTERED AFTERNOON CONVECTION
CAN BE EXPECTED. THERE ARE A LOT OF CLOUDS WITH THIS VORT SO THAT
CONVECTION MAY BE FURTHER LIMITED IN SCOPE AND INTENSITY THIS
AFTERNOON AND EVENING. STRONGLY WENT WITH THE HRRR MODEL THROUGH
THIS EVENING.
IN ANY CASE...THE VORT QUICKLY EXITS INTO VIRGINIA THIS EVENING...AND
WITH LOSS OF HEATING...ANY CONVECTION WILL QUICKLY DIE DOWN.
STILL...WILL LEAVE MIN POPS OVERNIGHT FOR NOCTURNAL POTENTIAL IN THE
MOIST ATMOSPHERE.
FOR MONDAY...A COLD FRONT WILL APPROACH FROM THE WEST...BUT WILL NOT
REACH OUR AREA UNTIL JUST AFTER THIS PERIOD. SO AGAIN...CONVECTION
WILL BE DEPENDENT ON FEATURES AHEAD OF THE MAIN SHORT WAVE
SUPPORTING THE FRONT. WILL KEEP THE BEST POPS AGAIN...SIMILAR TO
TODAY...IN THE SOUTH AND EAST IN THE AFTERNOON AS THE ONGOING
CONVECTIVE SURFACE BOUNDARY STRUGGLES TO LIFT NORTHWARD. AND
AGAIN...CLOUDS WILL BE A BIG FACTOR TO POTENTIALLY CURB CONVECTION.
FOR TEMPS...TOOK A BLEND OF THE MODELS...WHICH HAS BEEN THE BEST WAY
SO FAR.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
COLD FRONT FINALLY DEPARTS MONDAY NIGHT WITH HIGH PRESSURE BUILDING
IN BEHIND THE SYSTEM. VERY DRY AIR TO ADVECT IN BEHIND THE FRONT FOR
TUESDAY...ALTHOUGH MAY START OUT WITH SOME LOW LEVEL STRATUS IN
PLACE AS NAM BUFR SOUNDINGS SUGGEST SATURATION BELOW 875MB AND
NORTHERLY FLOW AT 925MB. LOW STRATUS DECK SHOULD LIFT AND DISSOLVE
BY LATE MORNING TUESDAY AND BE REPLACED IN THE AFTERNOON BY DIURNAL
CUMULUS AS A RESULT OF BOUNDARY LAYER MIXING. WILL BE COMPLETELY
DEVOID OF ANY MOISTURE ALL THE WAY THROUGH WEDNESDAY...LESS SOME
PATCHY THIN CIRRUS DRIFTING THROUGH ON WEDNESDAY AFTERNOON.
WITH A NEW AIRMASS IN PLACE...CAN EXPECT MORE TYPICAL LATE SUMMER
CONDITIONS IN TERMS OF TEMPERATURES AND DEWPOINTS AT THE SURFACE.
DRIER AIR AND INSOLATION WILL ALLOW TEMPERATURES TO DROP INTO THE
50S TUESDAY NIGHT...WITH SOME ISOLATED 40S IN THE LOWLANDS...AND
MORE PREVALENT IN THE MOUNTAINS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
EXTENDED FORECAST REMAINS PRIMARILY DRY. HIGH PRESSURE IN CONTROL
INTO THE EARLY PART OF THE WEEKEND...BUT MAY GET THE TAIL END OF A
COLD FRONT FOR THE END OF THE WEEK. THIS WOULD HAVE LITTLE AFFECT ON
THE MIDDLE OHIO VALLEY AND CENTRAL APPALACHIANS OTHER THAN A LITTLE
CLOUD COVER. LONG RANGE MODELS DEVELOP A SURFACE LOW IN THE CENTRAL
PLAINS FOR THE END OF THE WEEKEND WITH A WARM FRONT TO OUR NORTH. IN
THE END...HEIGHTS MAKE A RECOVERY FROM THE MILDER AIRMASS AT THE
BEGINNING OF THE LONG TERM FORECAST...AND WILL PUSH TO SLIGHTLY
ABOVE NORMAL TEMPERATURES AGAIN BY DAY 7.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
18Z SUNDAY THROUGH 18Z MONDAY...
SHORT WAVE CROSSES AREA THIS AFTERNOON...WITH MOST OF THE CONVECTION IN
THE MOUNTAINS...SCATTERED AFTERNOON DIURNAL CONVECTION
ELSEWHERE. EXPECT VFR OUTSIDE OF CONVECTION...EXCEPT WILL INCLUDE
PREVAILING MVFR IN CENTRAL AND SOUTHERN MOUNTAINS...ESPECIALLY AT
BKW GIVEN THE SUSTAINED HIGH POPS.
BULK OF CONVECTION WILL DIE DOWN AFTER 03Z...BUT STILL CANNOT
TOTALLY PULL POPS GIVEN THE MAIN SHORT WAVE AND FRONT ARE STILL TO
THE WEST. WILL KEEP ISOLATED. FOG DEVELOPMENT TONIGHT WILL DEPEND ON
THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE
DAY...BUT THINK MOST SITES WILL SEE ENOUGH STARS TO BRING IN MVFR TO
IFR FOG AFTER 05Z...ESPECIALLY ALONG RIVERS AND IN VALLEYS WHERE IT
RAINS TODAY.
AFTER 12Z...VFR CEILINGS PREVAILING WITH SCATTERED SHOWERS SPREADING
FROM WEST TO EAST.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG DEVELOPMENT AND DENSITY TONIGHT MAY VARY
DUE MAINLY TO CLOUD COVER.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H M H H H H H H H
EKN CONSISTENCY H H H M H H H H H M H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...26
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
248 PM EDT SUN SEP 1 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING
MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE
FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
WE WILL CONTINUE IN A WEST TO NORTHWEST FLOW ALOFT REGIME WITH UPPER
DISTURBANCES ROTATING ACROSS THE REGION. ALTHOUGH THE ATMOSPHERE IS
VERY MOIST AND CONDITIONALLY UNSTABLE...THE PROSPECT FOR CONVECTION
STILL DEPENDS ON MESOSCALE INFLUENCES. THE MOST DOMINANT INFLUENCE
WITH THIS OVERALL PATTERN OVER THE PAST 36 HOURS HAS BEEN THE VERY
WELL DEFINED LOW LEVEL BOUNDARY FROM PREVIOUS CONVECTION THAT HAS
BEEN LAYED OUT WELL TO THE SOUTH OVER THE TENNESSEE VALLEY REGION ON
INTO SOUTHWEST VIRGINIA. THIS HAS ESTABLISHED THE MAIN BAND OF
CONVECTION WITHIN THIS PATTERN TO REMAIN MOSTLY SOUTH OF OUR AREA.
THUS...EVEN WITH A WELL DEFINED VORT MAX LIFTING UP ACROSS THE AREA
THIS AFTERNOON AND EARLY EVENING...MOST OF THE ORGANIZED CONVECTION
WITH THIS FEATURE WILL REMAIN OVER THE SOUTHERN AND CENTRAL
MOUNTAINS. ELSEWHERE...ONLY SCATTERED AFTERNOON CONVECTION CAN BE
EXPECTED. THERE ARE A LOT OF CLOUDS WITH THIS VORT SO THAT
CONVECTION MAY BE FURTHER LIMITED IN SCOPE AND INTENSITY THIS
AFTERNOON AND EVENING. STRONGLY WENT WITH THE HRRR MODEL THROUGH
THIS EVENING.
IN ANY CASE...THE VORT QUICKLY EXITS INTO VIRGINIA THIS EVENING...AND
WITH LOSS OF HEATING...ANY CONVECTION WILL QUICKLY DIE DOWN.
STILL...WILL LEAVE MIN POPS OVERNIGHT FOR NOCTURNAL POTENTIAL IN THE
MOIST ATMOSPHERE.
FOR MONDAY...A COLD FRONT WILL APPROACH FROM THE WEST...BUT WILL NOT
REACH OUR AREA UNTIL JUST AFTER THIS PERIOD. SO AGAIN...CONVECTION
WILL BE DEPENDENT ON FEATURES AHEAD OF THE MAIN SHORT WAVE
SUPPORTING THE FRONT. WILL KEEP THE BEST POPS AGAIN...SIMILAR TO
TODAY...IN THE SOUTH AND EAST IN THE AFTERNOON AS THE ONGOING
CONVECTIVE SURFACE BOUNDARY STRUGGLES TO LIFT NORTHWARD. AND
AGAIN...CLOUDS WILL BE A BIG FACTOR TO POTENTIALLY CURB CONVECTION.
FOR TEMPS...TOOK A BLEND OF THE MODELS...WHICH HAS BEEN THE BEST WAY
SO FAR.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT
INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS
BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED
TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER
LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET.
INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW
VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT
DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS
THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV
HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN.
ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE
IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS
NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION.
THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS
SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL
EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF
THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT
LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING
REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE
MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH.
TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH
PRESSURE MOVES INTO THE AREA FROM THE NW.
RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE
MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE
WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT
THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE
START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND
DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR
DAY WEEKEND.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH
PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK.
TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL
SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW
TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE
WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED
PRECIPITATION.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
18Z SUNDAY THROUGH 18Z MONDAY...
SHORT WAVE CROSSES AREA THIS AFTERNOON...WITH MOST OF THE CONVECTION IN
THE MOUNTAINS...SCATTERED AFTERNOON DIURNAL CONVECTION
ELSEWHERE. EXPECT VFR OUTSIDE OF CONVECTION...EXCEPT WILL INCLUDE
PREVAILING MVFR IN CENTRAL AND SOUTHERN MOUNTAINS...ESPECIALLY AT
BKW GIVEN THE SUSTAINED HIGH POPS.
BULK OF CONVECTION WILL DIE DOWN AFTER 03Z...BUT STILL CANNOT
TOTALLY PULL POPS GIVEN THE MAIN SHORT WAVE AND FRONT ARE STILL TO
THE WEST. WILL KEEP ISOLATED. FOG DEVELOPMENT TONIGHT WILL DEPEND ON
THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE
DAY...BUT THINK MOST SITES WILL SEE ENOUGH STARS TO BRING IN MVFR TO
IFR FOG AFTER 05Z...ESPECIALLY ALONG RIVERS AND IN VALLEYS WHERE IT
RAINS TODAY.
AFTER 12Z...VFR CEILINGS PREVAILING WITH SCATTERED SHOWERS SPREADING
FROM WEST TO EAST.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG DEVELOPMENT AND DENSITY TONIGHT MAY VARY
DUE MAINLY TO CLOUD COVER.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H M H H H H H H H
EKN CONSISTENCY H H H M H H H H H M H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...TRM
LONG TERM...26
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
139 PM EDT SUN SEP 1 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING
MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE
FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE. ADJUSTED POPS WITH SHORT WAVE CROSSING AREA TODAY PER
RADAR...SATELLITE...SURFACE ANALYSIS TREND AND THE HRRR MODEL. LOOKS
LIKE THE HRRR MODEL HAS A VERY GOOD GRASP ON WHAT IS CURRENTLY GOING
ON MESOSCALE WISE PER THE CURRENT TRENDS...WHEREAS OTHER MODELS ARE
ACCOUNTING MORE FOR GENERAL SYNOPTIC SCALE FORCING AND JUST PAINTING
THE ARE WITH QPF. CONVECTION TO OUR SOUTH AND SOUTHWEST...WHICH HAS
KEPT THINGS QUIET AROUND HERE...HAS WEAKENED TO THE POINT WHERE NEW
CONVECTION DEVELOPING OVER SOUTHERN KENTUCKY IS STARTING TO LIFT
NORTHEAST. THIS WILL BRING THE HIGHEST POPS...PER HRRR...INTO THE
MOUNTAINS THROUGH THIS AFTERNOON. ELSEWHERE...LACK OF FOCUSING AND
UNIMPRESSIVE INSTABILITY SUGGESTS THAT EVEN WITH
SUNSHINE...CONVECTION OF A MORE SCATTERED NATURE CAN BE EXPECTED.
THUS...UPDATED TO LIKELY MOUNTAINS AND SCATTERED ELSEWHERE...WITH A
BIT LESS CLOUDS OUTSIDE OF MOUNTAINS. TEMPS STILL LOOK GOOD.
PREVIOUS DISCUSSION...
THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT
AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z
MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH
SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK
HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7
TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY
DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL
SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF
THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN
BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES
TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE
TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE
POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN
ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT.
SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST
OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG
DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON
LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT
OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE
PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION.
WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP
A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST
FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO
AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT
INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS
BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED
TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER
LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET.
INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW
VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT
DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS
THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV
HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN.
ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE
IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS
NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION.
THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS
SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL
EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF
THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT
LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING
REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE
MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH.
TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH
PRESSURE MOVES INTO THE AREA FROM THE NW.
RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE
MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE
WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT
THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE
START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND
DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR
DAY WEEKEND.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH
PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK.
TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL
SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW
TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE
WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED
PRECIPITATION.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
18Z SUNDAY THROUGH 18Z MONDAY...
SHORT WAVE CROSSES AREA THIS AFTERNOON...WITH MOST OF THE CONVECTION IN
THE MOUNTAINS...SCATTERED AFTERNOON DIURNAL CONVECTION
ELSEWHERE. EXPECT VFR OUTSIDE OF CONVECTION...EXCEPT WILL INCLUDE
PREVAILING MVFR IN CENTRAL AND SOUTHERN MOUNTAINS...ESPECIALLY AT
BKW GIVEN THE SUSTAINED HIGH POPS.
BULK OF CONVECTION WILL DIE DOWN AFTER 03Z...BUT STILL CANNOT
TOTALLY PULL POPS GIVEN THE MAIN SHORT WAVE AND FRONT ARE STILL TO
THE WEST. WILL KEEP ISOLATED. FOG DEVELOPMENT TONIGHT WILL DEPEND ON
THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE
DAY...BUT THINK MOST SITES WILL SEE ENOUGH STARS TO BRING IN MVFR TO
IFR FOG AFTER 05Z...ESPECIALLY ALONG RIVERS AND IN VALLEYS WHERE IT
RAINS TODAY.
AFTER 12Z...VFR CEILINGS PREVAILING WITH SCATTERED SHOWERS SPREADING
FROM WEST TO EAST.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG DEVELOPMENT AND DENSITY TONIGHT MAY VARY
DUE MAINLY TO CLOUD COVER.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H M H H H H H H H
EKN CONSISTENCY H H H M H H H H H M H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z MONDAY...
IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE
TUESDAY AND WEDNESDAY MORNINGS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...JMV/SL
SHORT TERM...TRM
LONG TERM...26
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
204 PM EDT SUN SEP 1 2013
.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH
PRESSURE SLOWLY SLIDES OFFSHORE THIS EVENING. THIS MOIST FLOW WILL HELP TO
KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT
WILL CROSS THE CAROLINAS ON TUESDAY WITH DRY HIGH PRESSURE RETURNING
ON WEDNESDAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
RETURN BY NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM...I WILL INCREASE NEAR TERM POPS TO MATCH RECENT RADAR
IMAGES. BASED ON OBS...I WILL INCREASE DWPTS THROUGH THE REST OF THE
AFTERNOON. CURRENT HWO REMAINS REPRESENTATIVE.
AS OF NOON...REGIONAL RADAR SHOWS A FADING LINE OF SHRA/TSRA IS
CROSSING THE NRN MTNS AS AN AREA OF SHOWERS AND TSRA OVER NRN GA.
THE CONVECTION APPEARS TO BE SUPPORTED BY THE APPROACH OF A S/W
RIPPLING ACROSS EASTERN KY/TN. LATEST MESOSCALE ANALYSIS SHOWS THAT
CAPES ACROSS THE CWA RANGE FROM 1000 J/KG ACROSS THE MTNS TO
EXCEEDING 2500 J/KG ACROSS THE UPPER SAVANNAH RIVER VALLEY. SIMILAR
TO SATURDAY...THE FORECAST AREA WILL LIKELY SEE AFTERNOON DEWPOINTS
IN THE LOW TO MID 70S WITH HIGHS IN THE U80S. OBSERVED SOUNDING AT
KFFC THIS MORNING INDICATED THAT THIS AFTERNOON CAPES COULD APPROACH
3500 J/KG...THIS MAY APPLY TO OUR FOOTHILLS AND PIEDMONT. DCAPE
VALUES MAY CONTINUE TO RANGE BELOW 1000 J/KG. KFFC AND KGSO FZL
ABOVE 14 KFT/WBZ ABOVE 12 KFT AND WEAK SHEAR WILL NOT FAVOR SVR WX.
HOWEVER...THE MODERATELY UNSTABLE ENVIRONMENT COUPLED WITH
INCREASING UPPER SUPPORT WILL LIKELY RESULT IN A BROAD BAND OF TSRA
FORMING OVER THE MTNS THIS AFTERNOON...TRACKING EAST DURING THE
EVENING. THESE STORMS COULD PRODUCE GUSTY WINDS AND TORRENTIAL
RAINFALL...HIGHLIGHTED WELL IN THE HWO.
I WILL UPDATE THE FORECAST TO ADJUST SKY/POP/AND TEMPS TO THE LATEST
THINKING. THE MOST NOTABLE CHANGES WILL BE CARRYING SOLID CHC POPS
WELL INTO THE EVENING HOURS ACROSS THE FOOTHILLS AND PIEDMONT.
5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE
PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED
INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING
SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST
AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T
HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD
IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG.
AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING
THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST
TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE
INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE
CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE
TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN
MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD
THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA.
ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP
CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE
WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON
ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND
SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH
TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE
FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE
NEEDED.
STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO
YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW
EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING
THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR
TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE
MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED
WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY
FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL.
THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT
POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY
DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE
HIGHEST CHANCES BY MID AFTN.
TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM
NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY
EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL
SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS
OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS
TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES.
SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT
GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS
PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE
HEAVY RAIN AND FLASH FLOODING STILL A THREAT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 140 PM SUNDAY...UPPER LEVEL L/WV TROUGH AXIS IS SLATED FOR
PASSAGE SOME TIME TUESDAY MORNING WITH THE BETTER LARGE SCALE FORCING
DEVELOPING TOWARD THE COAST TUESDAY AFTERNOON. AT THE SFC...WEAK
COLD FRONT NW OF THE MTNS MONDAY NIGHT REMAINS PROGGED TO JUMP INTO
EXISTING LEE TROUGH POSITION ON TUESDAY. WITHIN THE BROAD UVV/S ALONG
FRONT SIDE OF UPPER TROUGH...AT LEAST SMALL POP WILL NEED TO BE IN
THE FCST ALL NIGHT INTO TUESDAY MORNING. AS TUESDAY WEARS ON...THE
INFLUX OF DRIER LLVL AIR WOULD SEEM TO INCREASINGLY LIMIT DIURNAL
DEEP CONVECTIVE CHANCES TO AREAS E/SE OF THE BLUE RIDGE...ROUGHLY
COINCIDENT WITH THE EASTWARD PROGRESSION OF THE FRONTAL BOUNDARY.
DEEP LAYERED DRY AIR AND WEAK RIDGING ARE STILL EXPECTED TO SPREAD
INTO THE REGION THROUGH WEDNESDAY RESULTING IN QUIET WX CONDS AND
MAX TEMPERATURES A COUPLE OF DEG F BELOW THE EARLY SEPT CLIMO.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 1 PM SUNDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
THURSDAY WITH THE STEEP UPPER RIDGE PERSISTING OVER THE WESTERN
CONUS AND BROAD UPPER TROFFING OVER THE EAST. THIS PATTERN WILL
LARGELY MAINTAIN ITSELF UNTIL A CLOSED H5 LOW SPINS UP OVER THE
PACIFIC NW ON FRI AND THEN GRADUALLY SLIDES EASTWARD AND UP OVER THE
RIDGE. THE LONG RANGE MODELS SUGGEST THAT THIS LOW WILL ACT TO
FLATTEN THE UPPER RIDGE TOWARDS THE END OF THE PERIOD ON
SUN...LEAVING A MORE ZONAL SYNOPTIC PATTERN OVER MOST OF THE CONUS.
AT THE SFC...DRY CANADIAN HIGH PRESSURE WILL BE SLIDING OVER THE
REGION WITH WEAK FLOW AT THE SFC AND ALOFT. AS WE MOVE INTO FRI AND
THE WEEKEND...THE BERMUDA HIGH WILL GRADUALLY SPREAD MOIST SLY FLOW
OVER THE FCST AREA WITH INCREASING CHANCES FOR SCT SH AND TS EACH
DAY/EVENING. TEMPS SHOULD START THE PERIOD NEAR CLIMO AND DROP A
DEGREE OR 2 BY DAYS 6 AND 7.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AT KCLT...LATEST VISIBLE SATELLITE IMAGES AND WEB CAMS INDICATE
WEAKLY DEVELOPED CU ACROSS THE TERMINAL AT TAF ISSUANCE TIME.
REGIONAL RADARS INDICATE A FEW TSRA BANDS EXITING THE
FOOTHILLS...ON A TRACK TO MOVE NORTH AND SOUTH OF THE TERMINAL.
HOWEVER...THE SPC SSEO INDICATES THAT CONVECTION WILL RAPIDLY
DEVELOP OVER THE MTNS LATER THIS AFTERNOON AS A MODERATE S/W MOVES
TOWARD THE SOUTHERN APPALACHIANS. STEERING FLOW SHOULD BRING THE
CONVECTION ACROSS THE TERMINAL BETWEEN 22Z TO 2Z. SFC WINDS AHEAD OF
THE CONVECTION SHOULD REMAIN SW AROUND 10 KTS. FOLLOWING THE PASSAGE
OF THE STORMS...THICK DEBRIS CLOUDS SHOULD REMAIN OVER THE REGION
FOR MOST OF THE NIGHT. VFR FOG MAY DEVELOP OVER RAIN SOAKED AREAS
AROUND DAWN. ONE OR TWO HOURS AFTER SUNRISE MONDAY...WITH SHOULD
INCREASE TO AROUND 5 KTS FROM THE WSW WITH SCT CU BASES AROUND 030.
ELSEWHERE...KAND/KGSP/KGMU/KAVL WILL HAVE A GOOD CHANCE FOR
OBSERVING A SHRA OR TSRA DURING THE BEGINNING HOURS OF THE 18Z TAF.
I WILL INCLUDE A MENTION OF TEMPO FOR TS OR VCTS FOR EACH SITE. KHKY
SHOULD SEE VCTS BY 21Z. THE SPC SSEO INDICATES THAT CONVECTION WILL
RAPIDLY DEVELOP OVER THE MTNS LATER THIS AFTERNOON AS A MODERATE S/W
MOVES TOWARD THE SOUTHERN APPALACHIANS. STEERING FLOW SHOULD BRING
THE CONVECTION ACROSS THE TERMINALS THROUGH EARLY EVENING. SFC WINDS AHEAD
OF THE CONVECTION SHOULD REMAIN SW AROUND 10 KTS. FOLLOWING THE
PASSAGE OF THE STORMS...THICK DEBRIS CLOUDS SHOULD REMAIN OVER THE
REGION FOR MOST OF THE NIGHT. MVFR FOG MAY DEVELOP OVER RAIN SOAKED
AREAS AROUND DAWN. FORECAST SOUNDINGS INDICATE THAT KAVL WILL LIKELY
SEE ANOTHER PERIOD AROUND DAWN OF LIFR FOG AND CEILINGS. ONE OR TWO
HOURS AFTER SUNRISE MONDAY...WITH SHOULD INCREASE TO AROUND 5 KTS
FROM THE WSW WITH SCT CU WITH VFR BASES.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN
MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND
WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON
TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER
AIR WILL FOLLOW THE FRONT.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 85% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 97% HIGH 83% HIGH 100%
KAVL HIGH 100% HIGH 97% MED 68% HIGH 85%
KHKY HIGH 85% HIGH 100% HIGH 83% HIGH 94%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 97%
KAND HIGH 100% HIGH 100% HIGH 99% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...NED/WIMBERLEY
SHORT TERM...CSH
LONG TERM...JPT
AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1201 PM EDT SUN SEP 1 2013
.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH
PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO
KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT
CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON
WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF NOON...REGIONAL RADAR SHOWS A FADING LINE OF SHRA/TSRA IS
CROSSING THE NRN MTNS AS AN AREA OF SHOWERS AND TSRA OVER NRN GA.
THE CONVECTION APPEARS TO BE SUPPORTED BY THE APPROACH OF A S/W
RIPPLING ACROSS EASTERN KY/TN. LATEST MESOSCALE ANALYSIS SHOWS THAT
CAPES ACROSS THE CWA RANGE FROM 1000 J/KG ACROSS THE MTNS TO
EXCEEDING 2500 J/KG ACROSS THE UPPER SAVANNAH RIVER VALLEY. SIMILAR
TO SATURDAY...THE FORECAST AREA WILL LIKELY SEE AFTERNOON DEWPOINTS
IN THE LOW TO MID 70S WITH HIGHS IN THE U80S. OBSERVED SOUNDING AT
KFFC THIS MORNING INDICATED THAT THIS AFTERNOON CAPES COULD APPROACH
3500 J/KG...THIS MAY APPLY TO OUR FOOTHILLS AND PIEDMONT. DCAPE
VALUES MAY CONTINUE TO RANGE BELOW 1000 J/KG. KFFC AND KGSO FZL
ABOVE 14 KFT/WBZ ABOVE 12 KFT AND WEAK SHEAR WILL NOT FAVOR SVR WX.
HOWEVER...THE MODERATELY UNSTABLE ENVIRONMENT COUPLED WITH
INCREASING UPPER SUPPORT WILL LIKELY RESULT IN A BROAD BAND OF TSRA
FORMING OVER THE MTNS THIS AFTERNOON...TRACKING EAST DURING THE
EVENING. THESE STORMS COULD PRODUCE GUSTY WINDS AND TORRENTIAL
RAINFALL...HIGHLIGHTED WELL IN THE HWO.
I WILL UPDATE THE FORECAST TO ADJUST SKY/POP/AND TEMPS TO THE LATEST
THINKING. THE MOST NOTABLE CHANGES WILL BE CARRYING SOLID CHC POPS
WELL INTO THE EVENING HOURS ACROSS THE FOOTHILLS AND PIEDMONT.
5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE
PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED
INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING
SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST
AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T
HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD
IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG.
AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING
THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST
TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE
INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE
CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE
TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN
MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD
THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA.
ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP
CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE
WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON
ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND
SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH
TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE
FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE
NEEDED.
STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO
YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW
EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING
THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR
TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE
MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED
WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY
FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL.
THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT
POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY
DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE
HIGHEST CHANCES BY MID AFTN.
TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM
NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY
EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL
SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS
OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS
TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES.
SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT
GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS
PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE
HEAVY RAIN AND FLASH FLOODING STILL A THREAT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY
WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING
WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A
MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS
INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP
MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO
ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER
CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS
INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO
PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY.
CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING.
WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE
LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE
ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED.
LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE
NITE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT
THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW
OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF
OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE
STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE
AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP
DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI
WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL
CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING
BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR
NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW
NORMAL AND RISE TO NEAR NORMAL.
&&
.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
AT KCLT...SMALL POSSIBILITY OF A LOW CIG SETTLING IN AROUND DAYBREAK
AND KEEPING A RESTRICTION AFTER 12Z...BUT PRETTY CONFIDENT IN VFR TO
START THE TAF. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND
HAVE THEM IN A TEMPO IN THE EARLY TO MID AFTN...AND A VCSH
SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD.
FOLLOWING THE END OF THE DIURNAL CONVECTION VFR WILL PREVAIL...BUT
GUIDANCE SUGGESTS SOME FOG POSSIBLE LATE TONIGHT ONCE AGAIN. THIS IS
ESPECIALLY LIKELY IF THE FIELD IS HIT BY A SHOWER OR TSTM TODAY.
ELSEWHERE...EARLY MORNING DENSE FOG AND LIFR TO VLIFR CLOUD BASES
EXPECTED ACROSS THE MTNS TO THE WESTERN PIEDMONT EARLY THIS MORNING.
CLIMO INDICATES THAT CONDITIONS MAY NOT IMPROVE TO VFR UNTIL 14Z.
SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST EARLY TODAY
THOUGH CURRENT TRENDS SUGGEST LITTLE DIRECT THREAT TO KAVL OR ANY
OTHER TAF SITE. HOWEVER DIURNAL INSTABILITY WILL GROW QUICKLY ONCE
THE LOW CIGS BURN OFF. KAVL AND THE MTNS WILL LIKELY SEE SHRA/TSRA
THIS AFTN. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL
KEEP TEMPOS DURING THE AFTERNOON AS WELL AS A VCSH/VCTS AS NECESSARY
TO INDICATE LESSER PROBABILITY IN THE SURROUNDING TIMEFRAME. FLOW
REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT
KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR
NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH RESTRICTIONS WILL MAINLY
COME FROM FOG. SITES AFFECTED BY TSRA/SHRA TODAY ARE MOST LIKELY TO
GO DOWN TONIGHT...BUT IN GENERAL MOST SITES HAVE A GOOD SHOT AT
SEEING AT LEAST MVFR VSBY BEFORE DAYBREAK.
OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN
MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND
WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON
TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER
AIR WILL FOLLOW THE FRONT.
CONFIDENCE TABLE...
16-22Z 22-04Z 04-10Z 10-16Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 93% HIGH 100% HIGH 82% MED 75%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...NED/WIMBERLEY
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1227 PM CDT SUN SEP 1 2013
.AVIATION...
PRIMARY AVIATION CONCERNS NEXT 24 HOURS INVOLVE TIMING AND
COVERAGE OF CONVECTIVE ACTIVITY NEAR TERMINALS.
EXPECT GENERALLY VFR CONDITIONS TO CONTINUE INTO MONDAY. THERE WILL
BE ISOLATED THUNDERSTORMS THIS AFTERNOON AND EARLY THIS EVENING
ACROSS MOST OF NORTH TEXAS...BUT COVERAGE IS EXPECTED TO REMAIN
VERY LIMITED AND WILL NOT MENTION IN ANY OF THE TAFS AT THIS
TIME.
BETTER CHANCES FOR CONVECTION WILL ARRIVE TONIGHT IN THE
METROPLEX AS A COLD FRONT IN OKLAHOMA CROSSES THE RED RIVER THIS
EVENING AND APPROACHES DFW JUST AFTER MIDNIGHT. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS ARE EXPECTED TO ACCOMPANY THE
FRONT...AND WILL CARRY VCTS AFTER 08Z /3 AM CDT/ AT DFW AND OTHER
METROPLEX TAF SITES. THE FRONT IS EXPECTED TO STALL ACROSS THE
METROPLEX OR PERHAPS JUST SOUTH OF THE METROPLEX...SO THE
CONVECTIVE CHANCES WILL REMAIN VERY LOW IN THE KACT AREA THROUGH
18Z /100 PM CDT/ MONDAY.
09
&&
.UPDATE...
FORT WORTH SOUNDING SHOWS SLIGHT COOLING DURING THE LAST 24 HOURS IN
THE LOWEST 50MB...SO TEMPS SHOULD BE A DEGREE OR SO COOLER THAN
YESTERDAY. HOWEVER HIGHS WILL ONCE AGAIN REACH THE CENTURY MARK
ACROSS MOST OF NORTH TEXAS TODAY AND DID RAISE THEM A BIT FROM THE
PREVIOUS FORECAST IN A FEW LOCATIONS. THE MORNING SOUNDING ALSO
INDICATED HIGHER PRECIPITABLE WATER WITH NOTABLE
COOLING/MOISTENING OCCURRING IN THE MID LEVELS...SUGGESTING WEAK
UPPER LEVEL LIFT IS NOW SPREADING ACROSS NORTH TEXAS. AS HEATING
OCCURS TODAY WOULD EXPECT ISOLATED CONVECTION TO DEVELOP. HI-RES
AND SHORT-TERM GUIDANCE DOES NOT FAVOR ANY PARTICULAR AREA FOR
THIS POP-UP ACTIVITY...AND THUS WILL MENTION ISOLATED
SHOWERS/STORMS EVERYWHERE THIS AFTERNOON WITH A 10 POP SINCE
COVERAGE WILL BE LOW WITHOUT A SURFACE FOCUSING MECHANISM. A COLD
FRONT WILL ARRIVE INTO THE NORTHERN ZONES AFTER 00Z...AND NORTHERN
AND WESTERN ZONES WILL BE THE FAVORED AREA FOR MORE SIGNIFICANT
RAINFALL COVERAGE TONIGHT.
TR.92
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SUN SEP 1 2013/
NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW
DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN
ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID
ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS
ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST
TOWARD THE UPPER TEXAS COAST.
ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH
OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE
RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109
AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS
EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A
SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER
SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON.
IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP
SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND
TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS
EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER
LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND
TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE
DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM.
SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED
RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z
LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN
THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH
INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS.
MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE
INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES
WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR.
LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH
STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER
DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A
SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS
THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE
SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE
RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING
BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM
CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS.
THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING
WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS.
THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE
DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW
CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE
SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL
COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE
ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST
TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE
CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER
HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO
SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH
POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY
DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD
TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE
AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON
WHERE THIS FEATURE TRACKS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 103 79 98 77 98 / 10 30 20 20 10
WACO, TX 102 77 100 75 98 / 10 20 20 20 20
PARIS, TX 101 74 96 71 96 / 10 30 20 10 10
DENTON, TX 103 77 97 72 97 / 10 40 20 10 10
MCKINNEY, TX 102 76 97 73 98 / 10 30 20 10 10
DALLAS, TX 104 80 98 78 99 / 10 30 20 20 10
TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10
CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10
TEMPLE, TX 100 74 98 74 97 / 10 10 20 20 20
MINERAL WELLS, TX 103 74 95 73 96 / 10 40 30 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
359 PM EDT SUN SEP 1 2013
.SYNOPSIS...
UPPER AIR DISTURBANCES WILL MOVE EAST ACROSS THE AREA THIS EVENING
AND AGAIN MONDAY WITH A COLD FRONT MOVING THROUGH BY TUESDAY.
THIS FRONT WILL BRING A DRIER AIRMASS TO THE REGION THROUGH THE
END OF NEXT WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 250 PM EDT SUNDAY...
BANDS OF SHRA/TSRA CONTINUE TO SPREAD EAST ACROSS THE REGION
LATE THIS AFTERNOON AHEAD OF A WEAK VORT LOBE THAT LOOKS TO SWING
ACROSS THE MOUNTAINS BY THIS EVENING BEFORE EXITING TO THE EAST
OVERNIGHT. BEST INSTABILITY REMAINS ALONG/EAST OF THE BLUE RIDGE
WHERE SUPPORTED BY HIGHER LOW LEVEL THETA-E AND WEAK CONVERGENCE.
LATEST HRRR AND SIMILAR NAM SOLUTIONS EVENTUALLY PUSH BEST
COVERAGE OF STORMS INTO THE NE CWA BY THIS EVENING FOLLOWED BY
DECENT DRYING BEHIND THE WAVE OVERNIGHT. HOWEVER WITH POTENTIAL
FOR SEVERAL BANDS OF SHRA INTO THE EVENING WILL HAVE THE HIGHER
LIKELY POPS BLUE RIDGE WEST EARLY WITH MAINLY HIGH CHANCES TO THE
EAST. CUT PRECIP BACK OVERNIGHT AS THE AREA SLIPS IN BETWEEN
IMPULSES WITH ONLY ISOLATED COVERAGE LIKELY AT THIS POINT. HOWEVER
SHOULD BE PLENTY OF FOG AROUND AS CLOUDS CLEAR SOME LATER ON AND
TEMPS FALL BACK INTO THE 60S MOST SPOTS.
5H TROF WILL SLOWLY SAG INTO THE AREA ON MONDAY WITH THE
ASSOCIATED SURFACE COLD FRONT STILL WEST OF THE MOUNTAINS
THROUGH LATE IN THE DAY. THIS COMBO WITH MORE WESTERLY FLOW TO
INIT SHOULD LIMIT SHRA EARLY ON FOLLOWED BY INCREASING AFTERNOON
COVERAGE FAR WEST...AND ALONG THE BLUE RIDGE AS THE LOW LEVEL FLOW
SLOWLY BACKS. MODELS GIVEN MORE INSOLATION AND LESS EARLY
SHRA...NOW SHOWING MORE INSTABILITY ALTHOUGH WIND FIELDS ALOFT
LOOK RATHER WEAK. THUS HAVE CUT BACK ON POPS DURING THE MORNING TO
LOW CHANCE OR SLIGHTS...WITH A GRADUAL INCREASE TO LIKELYS OVER
THE FAR WEST LATER IN THE AFTERNOON. MAY SEE THE PIEDMONT ACTUALLY
GO DRY FOR THE MOST PART UNTIL LATE BUT LEFT CHANCE COVERAGE THERE
FOR NOW GIVEN HEATING. WILL BE A HOT LABOR DAY WITH 85H TEMPS NEAR
+20C WHICH SHOULD ALLOW MOST OUTSIDE THE HIGHER RIDGES TO TOP 80
WITH PERHAPS LOW 90S EAST PENDING EARLY CLOUDS AND LATER TSRA.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 330 PM EDT SUNDAY...
COLD FRONT MOVES THROUGH MONDAY NIGHT BUT WITH A FEW DISTURBANCES
BEHIND IT AND REMAINING MOISTURE...STILL A GOOD CHANCE OF SHOWERS
FOR THE FIRST HALF OF THE NIGHT...ESPECIALLY IN THE WEST.
IMPRESSIVE PUNCH OF DRIER AIR ARRIVES ON DOWNSLOPING WINDS AS
SKIES BEGIN TO CLEAR INTO TUESDAY MORNING. ALTHOUGH THERE IS SOME
POSITIVE ENERGY IN THE SOUNDING TUESDAY AFTERNOON...APPEARS TO BE
JUST TOO MUCH DRY AIR ABOVE H85 TO GET ANY STORMS GOING. MOISTURE
HANGS A BIT CLOSER TO THE FRONT ACROSS THE SOUTHSIDE SO LEFT SOME
POPS THERE. FOR SOME REASON...THE NAM SOUNDINGS ARE FAR TOO
AGGRESSIVE WITH CAPE ON TUESDAY...MOST LIKELY BECAUSE DEWPOINTS
FROM THE NAM AND THE MET MOS ARE 6-8F WARMER THAN THE
GFS/MAV/ECMWF. WITH LOW TO MID 50S DEWPOINTS ARRIVING LATE
TUESDAY...SOME OF THE COLDEST SPOTS OF SE WEST VA AND EXTREME SW
VA MAY TOUCH THE UPPER 40S TUESDAY NIGHT. AT THIS POINT...COOL
AND DRY HIGH PRESSURE WILL RULE THE REST OF THE SHORT TERM WITH
ONLY PASSING HIGH CLOUDS. WEDNESDAY NIGHT HAS THE POTENTIAL TO BE
JUST AS CHILLY AS TUESDAY NIGHT...ALTHOUGH MORE HIGH CLOUDS MAY
KEEP TEMPS UP A TAD. FOR HIGH TEMPS WEDNESDAY...THE ONLY PLACE 80S
WILL BE FOUND WILL BE THE LOWEST ELEVATIONS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 330 PM EDT SUNDAY...
THE DRY PATTERN CONTINUES AS TEMPS SLOWLY WARM...ALTHOUGH NOT AS
FAST AS WHAT THE OPERATIONAL GFS HAS. H85 TEMPS FROM THAT MODEL
ARE SEVERAL DEGREES WARMER THAN THE ECMWF. AGREE WITH THE SLOWER
WARMUP BUT NOT AS COOL AS THE ECMWF MOS. NONETHELESS...BOTH
MODELS ARE MOSTLY DRY...UNTIL AN EASTERN TROUGH ONCE AGAIN
DEEPENS. SUBTLE INDICATIONS IN THE MASS FIELDS FROM THE ECMWF THAT
A BACKDOOR FRONT MAY CROSS SATURDAY OR SUNDAY. WITH THAT
SAID...THERE STILL REALLY ISN`T MUCH QPF TO BE FOUND ON EITHER
MODEL THROUGH DAY 7.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AS OF 100 PM EDT SUNDAY...
BAND OF SHRA/TSRA HEADING ACROSS THE WEST WILL CONTINUE TO PUSH
EAST AND LIKELY STRENGTHEN UPON NEARING THE BLUE RIDGE IN THE NEXT
HOUR OR TWO. THUS ADDING MORE PREVAILING LOWERING OF CIGS/VSBYS
TO MVFR FROM KROA WEST THROUGH MID AFTERNOON ALTHOUGH EXPECTING
HEAVIER COVERAGE TO PASS JUST SOUTH OF THESE TAF SITES. ALSO GIVEN
INCREASING INSTABILITY ACROSS THE EAST WILL GO AHEAD AND INCLUDE A
VCTS MENTION ACROSS THE EASTERN SITES AFTER 3 OR 4 PM. THIS COULD
BRIEFLY DROP THESE LOCATIONS INTO IFR PENDING IF THEY SEE A
HEAVIER SHRA/TSRA. THINK COVERAGE WILL BECOME MORE SCATTERED OVER
THE WEST ONCE THE CURRENT BATCH OF SHRA/TSRA MOVES THROUGH BUT
LIKELY NOT UNTIL LATE THIS AFTERNOON AT THIS POINT.
WEAKENING IN THE CONVECTION THIS EVENING WITH FOG AGAIN FORMING
OVERNIGHT AT MOST SITES...WITH FOG BECOMING DENSE AT
KLWB/KBCB...AND MAYBE KLYH IF SHOWERS OCCUR NEARBY.
TRUE FRONT EXPECTED TO NOT MOVE INTO AND THRU THE CWA UNTIL
TUESDAY MORNING...SO MONDAY WILL BE ANOTHER DAY OF SCATTERED
CONVECTION WITH THE LAST IN THE UPPER LEVEL SHORTWAVES MOVING
ACROSS INTERACTING WITH HUMID SFC CONDITIONS AND LOW LVL
CONVERGENCE. HOWEVER SINCE MOST WIDESPREAD COVERAGE NOT EXPECTED
UNTIL NEAR OR AFTER THE END OF THE VALID TAF PERIOD WONT INCLUDE
ANY SHRA/TSRA MENTION AFTER FOG/STRATUS FADES. ANTICIPATE MORE
FOG TUESDAY MORNING WITH DRIER AIR NOSING IN DURING THE DAY
TUESDAY. MOSTLY VFR EXPECTED THROUGH LATE WEEK OUTSIDE OF ANY
OVERNIGHT FOG.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/RCS/WP
NEAR TERM...JH
SHORT TERM...KM
LONG TERM...KM
AVIATION...DS/JH/RCS/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
327 PM EDT SUN SEP 1 2013
.SYNOPSIS...
UPPER AIR DISTURBANCES WILL MOVE EAST ACROSS THE AREA THIS EVENING
AND AGAIN MONDAY WITH A COLD FRONT MOVING THROUGH BY TUESDAY.
THIS FRONT WILL BRING A DRIER AIRMASS TO THE REGION FOR THE MIDDLE
OF THE WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 250 PM EDT SUNDAY...
BANDS OF SHRA/TSRA CONTINUE TO SPREAD EAST ACROSS THE REGION
LATE THIS AFTERNOON AHEAD OF A WEAK VORT LOBE THAT LOOKS TO SWING
ACROSS THE MOUNTAINS BY THIS EVENING BEFORE EXITING TO THE EAST
OVERNIGHT. BEST INSTABILITY REMAINS ALONG/EAST OF THE BLUE RIDGE
WHERE SUPPORTED BY HIGHER LOW LEVEL THETA-E AND WEAK CONVERGENCE.
LATEST HRRR AND SIMILAR NAM SOLUTIONS EVENTUALLY PUSH BEST
COVERAGE OF STORMS INTO THE NE CWA BY THIS EVENING FOLLOWED BY
DECENT DRYING BEHIND THE WAVE OVERNIGHT. HOWEVER WITH POTENTIAL
FOR SEVERAL BANDS OF SHRA INTO THE EVENING WILL HAVE THE HIGHER
LIKELY POPS BLUE RIDGE WEST EARLY WITH MAINLY HIGH CHANCES TO THE
EAST. CUT PRECIP BACK OVERNIGHT AS THE AREA SLIPS IN BETWEEN
IMPULSES WITH ONLY ISOLATED COVERAGE LIKELY AT THIS POINT. HOWEVER
SHOULD BE PLENTY OF FOG AROUND AS CLOUDS CLEAR SOME LATER ON AND
TEMPS FALL BACK INTO THE 60S MOST SPOTS.
5H TROF WILL SLOWLY SAG INTO THE AREA ON MONDAY WITH THE
ASSOCIATED SURFACE COLD FRONT STILL WEST OF THE MOUNTAINS
THROUGH LATE IN THE DAY. THIS COMBO WITH MORE WESTERLY FLOW TO
INIT SHOULD LIMIT SHRA EARLY ON FOLLOWED BY INCREASING AFTERNOON
COVERAGE FAR WEST...AND ALONG THE BLUE RIDGE AS THE LOW LEVEL FLOW
SLOWLY BACKS. MODELS GIVEN MORE INSOLATION AND LESS EARLY
SHRA...NOW SHOWING MORE INSTABILITY ALTHOUGH WIND FIELDS ALOFT
LOOK RATHER WEAK. THUS HAVE CUT BACK ON POPS DURING THE MORNING TO
LOW CHANCE OR SLIGHTS...WITH A GRADUAL INCREASE TO LIKELYS OVER
THE FAR WEST LATER IN THE AFTERNOON. MAY SEE THE PIEDMONT ACTUALLY
GO DRY FOR THE MOST PART UNTIL LATE BUT LEFT CHANCE COVERAGE THERE
FOR NOW GIVEN HEATING. WILL BE A HOT LABOR DAY WITH 85H TEMPS NEAR
+20C WHICH SHOULD ALLOW MOST OUTSIDE THE HIGHER RIDGES TO TOP 80
WITH PERHAPS LOW 90S EAST PENDING EARLY CLOUDS AND LATER TSRA.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 AM EDT SATURDAY...
MODELS ARE IN DECENT AGREEMENT THAT AN ASSOCIATED COLD FRONT WILL
ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES TUESDAY MORNING...AND
CONTINUE SOUTHEAST...EXITING OUR AREA DURING THE AFTERNOON. THE
TRULY DRIER AIR IN THE LOW LEVELS WILL LAG A FEW HOURS BEHIND THE
FRONT...SO EXPECT WE WILL STILL SEE A COUPLE SHOWERS AND
THUNDERSTORMS SOUTH OF INTERSTATE 81 THROUGH SUNSET...AT WHICH
POINT INSTABILITY WILL DISAPPEAR.
CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...BRINGING WITH IT A HINT OF AUTUMN AS
TEMPERATURES FOR MID WEEK ARE EXPECTED TO BE SLIGHTLY BELOW NORMAL
FOR EARLY SEPTEMBER.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SATURDAY...
A STRONG RIDGE CONTINUES IN THE WEST...WHILE AMPLIFYING TROUGH
ANTICIPATED IN THE EAST. HIGH PRESSURE WILL CONTROL OUR WEATHER
PATTERN FOR THURSDAY...RESULTING IN DRY CONDITIONS WITH MOSTLY
CLEAR SKIES...OUTSIDE OF EARLY MORNING FOG. ANOTHER COLD FRONT
WILL DROP SOUTHEAST ACROSS THE REGION FRIDAY WITH SOME MOISTURE
AND INSTABILITY...KEPT THE MENTION OF ISOLATED TO SCATTERED
SHOWERS WITH FRONTAL BOUNDARY. ISOLATED AFTERNOON CONVECTION IS
POSSIBLE SATURDAY AFTERNOON WITH BEST CHANCES ACROSS THE HIGHER
TERRAIN. TEMPERATURES INITIALLY START BELOW NORMAL THEN SLOWLY
MODERATE INTO THE WEEKEND.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AS OF 100 PM EDT SUNDAY...
BAND OF SHRA/TSRA HEADING ACROSS THE WEST WILL CONTINUE TO PUSH
EAST AND LIKELY STRENGTHEN UPON NEARING THE BLUE RIDGE IN THE NEXT
HOUR OR TWO. THUS ADDING MORE PREVAILING LOWERING OF CIGS/VSBYS
TO MVFR FROM KROA WEST THROUGH MID AFTERNOON ALTHOUGH EXPECTING
HEAVIER COVERAGE TO PASS JUST SOUTH OF THESE TAF SITES. ALSO GIVEN
INCREASING INSTABILITY ACROSS THE EAST WILL GO AHEAD AND INCLUDE A
VCTS MENTION ACROSS THE EASTERN SITES AFTER 3 OR 4 PM. THIS COULD
BRIEFLY DROP THESE LOCATIONS INTO IFR PENDING IF THEY SEE A
HEAVIER SHRA/TSRA. THINK COVERAGE WILL BECOME MORE SCATTERED OVER
THE WEST ONCE THE CURRENT BATCH OF SHRA/TSRA MOVES THROUGH BUT
LIKELY NOT UNTIL LATE THIS AFTERNOON AT THIS POINT.
WEAKENING IN THE CONVECTION THIS EVENING WITH FOG AGAIN FORMING
OVERNIGHT AT MOST SITES...WITH FOG BECOMING DENSE AT
KLWB/KBCB...AND MAYBE KLYH IF SHOWERS OCCUR NEARBY.
TRUE FRONT EXPECTED TO NOT MOVE INTO AND THRU THE CWA UNTIL
TUESDAY MORNING...SO MONDAY WILL BE ANOTHER DAY OF SCATTERED
CONVECTION WITH THE LAST IN THE UPPER LEVEL SHORTWAVES MOVING
ACROSS INTERACTING WITH HUMID SFC CONDITIONS AND LOW LVL
CONVERGENCE. HOWEVER SINCE MOST WIDESPREAD COVERAGE NOT EXPECTED
UNTIL NEAR OR AFTER THE END OF THE VALID TAF PERIOD WONT INCLUDE
ANY SHRA/TSRA MENTION AFTER FOG/STRATUS FADES. ANTICIPATE MORE
FOG TUESDAY MORNING WITH DRIER AIR NOSING IN DURING THE DAY
TUESDAY. MOSTLY VFR EXPECTED THROUGH LATE WEEK OUTSIDE OF ANY
OVERNIGHT FOG.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/RCS/WP
NEAR TERM...JH
SHORT TERM...NF
LONG TERM...KK
AVIATION...DS/JH/RCS/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
112 PM EDT SUN SEP 1 2013
.SYNOPSIS...
UPPER AIR DISTURBANCES WILL MOVE EAST ACROSS THE AREA THROUGH
MONDAY WITH A COLD FRONT MOVING THROUGH BY TUESDAY. THIS FRONT
WILL BRING A DRIER AIRMASS TO THE REGION FOR THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EDT SUNDAY...
BAND OF SHRA/TSRA APPROACHING FROM THE SW WILL BE PUSHING NE INTO
THE FAR WESTERN AREAS AROUND 11 AM...AND THEN LIKELY AID NEW
DEVELOPMENT FARTHER EAST AS INSTABILITY INCREASES PER EARLY
HEATING. EARLY ARRIVAL OF CONVECTION MAY TEND TO LIMIT THE WESTERN
SEVERE THREAT TO SOME DEGREE ESPCLY GIVEN WEAKER WINDS ALOFT OFF
MORNING RAOBS AND DEEP MOISTURE TO 6H. HOWEVER LATEST SHORT RANGE
GUIDANCE REMAINS VARIED ON LATER TRENDS WITH SOME TAKING BETTER
LIFT TO THE SW OF THE AREA WITH THE OLD OUTFLOW UNFOLDING INTO THE
TN VALLEY...WHILE THE HRRR BRINGS A SWATH OF SHRA/TSRA EAST ALONG
THE RESIDUAL VORT AXIS. THIS LOOKS BEST IN LINE WITH THE CURRENT
SCENARIO ESPCLY GIVEN DECENT INSTABILITY OFF MODIFIED RAOBS WEST
AND BETTER HEATING EAST WHERE INITIAL LIFT MAY GET WEAKENED SOME
VIA DOWNSLOPE. THUS HAVE UPPED POPS TO LIKELYS A BIT SOONER FAR
WEST AND EXTENDED EAST TO THE BLUE RIDGE FOR NOW. LEFT CHANCE POPS
IN THE EAST FOR LATER DEVELOPMENT ALTHOUGH MAY NEED TO RAISE LATER
PENDING TRENDS. KEPT HIGHS A LITTLE COOLER...75-80 OVER THE SW
GIVEN EARLIER ARRIVAL OF SHRA...WITH THE EAST PUSHING 90 UNDER
WEAK WESTERLY FLOW AND 85H TEMPS OF +18C.
PREVIOUS VALID DISCUSSION...
HAVE ADJUSTED POPS DOWNWARD EARLY THEN BLEND INTO THE HIGHER POPS
BY MIDDAY OVER THE WEST. THINK ANY OUTFLOW AND HIGHER THETA-E
ACROSS THE MTNS WILL BE ENOUGH TO GET SHRA/TSRA GOING BEFORE NOON
ACROSS SE WV/FAR SW VA. THE 06Z NAM/00Z ECMWF CONTINUE TO
ADVERTISE MORE ORGANZIED CONVECTION MOVING FROM NRN KY INTO ERN
WV/SHENANDOAH VALLEY OF VA THIS AFTERNOON WITH 6Z GFS SINGLING OUT
THE MOUNTAINS OF NC/FAR SW VA. OVERALL KEPT THE LIKELY POPS OVER
THE WEST BY EARLY AFTERNOON TAPERING TO SCATTERED EAST OF THE BLUE
RIDGE. ANY FOG EARLY WILL BURN OFF BY 10 AM.
PREVIOUS DISCUSSION AT 330 AM...
EARLY THIS MORNING...SEEING SOME DENSE FOG ACROSS THE AREA
RESULTING FROM LACK OF LOWER OR MID CLOUDS AND WET GROUND FROM
SATURDAYS RAINS. WILL MAINTAIN SPECIAL WX STATEMENTS FOR
THIS...GIVEN THAT WILL SEE UPSTREAM CLOUDINESS ARRIVING THAT MAY
CAUSE VSBYS TO FLUCTUATE ENOUGH TO KEEP THE COVERAGE OF DENSE FOG
TO A LOCALIZED/PATCHY STATE.
HAVE STAYED CLOSER TO THE 00Z GFS SOLUTION THIS PERIOD AS IT WAS
HANDLING THE UPPER SHORTWAVE ACROSS OHIO AND STORMS OVER KY THIS
MORNING BETTER THAN THE OTHER MODELS. THE LOCAL WRF/HRRR NOT ALL
THAT BAD EITHER BUT APPEAR TO BE OVERDOING PRECIP IN THE EAST AS
RADAR IS CLEAR.
SO FOR TODAY...STILL LOOKS LIKELY THAT SHOWERS AND STORMS WILL
IMPACT THE MOUNTAINS BY MIDDAY...THEN SHIFT ENE ACROSS THE REST OF
THE AREA THRU THE AFTERNOON. THE FLOW WILL BE SW TO WEST WHICH MAY
LIMIT COVERAGE AS WE HEAD DOWNSTREAM OF THE BLUE RIDGE SO LEFT POPS
IN THE FOOTHILLS PIEDMONT AREAS TO 30/4O WHILE GOING LIKELY OR HIGH
CHANCE WEST. PWATS REMAINING HIGH WILL FAVOR HEAVY RAINERS AS STORM
MOTION WILL BE IN THE 10-20 MPH RANGE. SEVERE THREAT WILL BE
ISOLATED TO WIND DAMAGE FROM OUTFLOW/DOWNBURSTS. WILL CONTINUE TO
MENTION THE RAIN/SVR THREAT IN THE HWO.
AS THE WAVE PASSES THIS EVENING...THE CENTRAL/ERN CWA SHOULD SEE
DRYING TREND. NEXT UPSTREAM WAVE WILL BE WEAKENING AS IT MOVES FROM
KY INTO WV OVERNIGHT...BUT ENOUGH THETA-E/HIGH MOISTURE AHEAD OF THE
FRONT TO KEEP HIGHER POPS ACROSS THE SE WV/FAR SW VA AFTER MIDNIGHT
BUT ONLY ABOUT 30/40 POPS.
WITH MAINLY A MIX OF CLOUDS/SUN TODAY WILL STILL SEE WARM TEMPS IN
THE MAV/MET BLEND RANGE FROM UPPER 70S/LOWER 80S MOUNTAINS...TO NEAR
90 PIEDMONT.
TONIGHT...MUGGY CONDITIONS REMAIN WITH TEMPS FALLING INTO THE 60S.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 400 AM EDT SATURDAY...
LOOKING AHEAD TO MONDAY...THE APPALACHIAN CHAIN WILL BE SITUATED AT
THE BASE OF A BROAD UPPER LEVEL TROUGH EXTENDING SOUTHWARD FROM THE
GREAT LAKES...RESULTING IN WESTERLY WINDFLOW ACROSS OUR AREA. ASIDE
FROM A FEW SHOWERS SPILLING OVER OUR FAR WESTERN RIDGELINES...THIS
WEST WIND WILL KEEP A LID ON CONVECTION DURING THE MORNING AND MUCH
OF THE AFTERNOON...BEFORE AN UPPER LEVEL DISTURBANCE APPROACHES
DURING THE EVENING. CLOUD COVER WILL BE SCATTERED EAST OF THE BLUE
RIDGE...MAINLY CONFINED TO MID AND HIGH CLOUDS...AND BELIEVE THE
COMBINATION OF THE DOWNSLOPE WIND AND FILTERED SUNSHINE REACHING THE
SURFACE WILL BE SUFFICIENT TO ALLOW TEMPERATURES TO REACH INTO THE
LOWER 90S IN A FEW AREA OF THE PIEDMONTS.
AS MENTIONED...AN UPPER LEVEL DISTURBANCE IS EXPECTED TO MOVE IN
FROM THE WEST DURING THE EVENING...INCREASING THE COVERAGE OF
SHOWERS AND THUNDERSTORMS ACROSS OUR AREA. INSTABILITY ASSOCIATED
WITH THE DISTURBANCE WILL BE SUFFICIENT TO ALLOW A FEW THUNDERSTORMS
TO BECOME SEVERE...AND EXPECT THE BIGGER THREAT TO COME IN THE FORM
OF DAMAGING WINDS. ATMOSPHERIC MOISTURE WILL REMAIN ABUNDANT...AND
EXPECT WE WILL ALSO SEE A FEW STORMS PRODUCE HEAVY RAIN...AND
POSSIBLY LOCALIZED FLASH FLOODING. THUNDERSTORM ACTIVITY WILL
DECREASE LATE MONDAY NIGHT/EARLY TUESDAY AS THIS DISTURBANCE
MOVES EAST.
MODELS ARE IN DECENT AGREEMENT THAT AN ASSOCIATED COLD FRONT WILL
ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES TUESDAY MORNING...AND
CONTINUE SOUTHEAST...EXITING OUR AREA DURING THE AFTERNOON. THE TRULY
DRIER AIR IN THE LOW LEVELS WILL LAG A FEW HOURS BEHIND THE
FRONT...SO EXPECT WE WILL STILL SEE A COUPLE SHOWERS AND
THUNDERSTORMS SOUTH OF INTERSTATE 81 THROUGH SUNSET...AT WHICH POINT
INSTABILITY WILL DISAPPEAR.
CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...BRINGING WITH IT A HINT OF AUTUMN AS
TEMPERATURES FOR MID WEEK ARE EXPECTED TO BE SLIGHTLY BELOW NORMAL
FOR EARLY SEPTEMBER.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 400 PM EDT SATURDAY...
A STRONG RIDGE CONTINUES IN THE WEST...WHILE AMPLIFYING TROUGH
ANTICIPATED IN THE EAST. HIGH PRESSURE WILL CONTROL OUR WEATHER
PATTERN FOR THURSDAY...RESULTING IN DRY CONDITIONS WITH MOSTLY
CLEAR SKIES...OUTSIDE OF EARLY MORNING FOG. ANOTHER COLD FRONT
WILL DROP SOUTHEAST ACROSS THE REGION FRIDAY WITH SOME MOISTURE
AND INSTABILITY...KEPT THE MENTION OF ISOLATED TO SCATTERED
SHOWERS WITH FRONTAL BOUNDARY. ISOLATED AFTERNOON CONVECTION IS
POSSIBLE SATURDAY AFTERNOON WITH BEST CHANCES ACROSS THE HIGHER
TERRAIN. TEMPERATURES INITIALLY START BELOW NORMAL THEN SLOWLY
MODERATE INTO THE WEEKEND.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
AS OF 100 PM EDT SUNDAY...
BAND OF SHRA/TSRA HEADING ACROSS THE WEST WILL CONTINUE TO PUSH
EAST AND LIKELY STRENGTHEN UPON NEARING THE BLUE RIDGE IN THE NEXT
HOUR OR TWO. THUS ADDING MORE PREVAILING LOWERING OF CIGS/VSBYS
TO MVFR FROM KROA WEST THROUGH MID AFTERNOON ALTHOUGH EXPECTING
HEAVIER COVERAGE TO PASS JUST SOUTH OF THESE TAF SITES. ALSO GIVEN
INCREASING INSTABILITY ACROSS THE EAST WILL GO AHEAD AND INCLUDE A
VCTS MENTION ACROSS THE EASTERN SITES AFTER 3 OR 4 PM. THIS COULD
BRIEFLY DROP THESE LOCATIONS INTO IFR PENDING IF THEY SEE A
HEAVIER SHRA/TSRA. THINK COVERAGE WILL BECOME MORE SCATTERED OVER
THE WEST ONCE THE CURRENT BATCH OF SHRA/TSRA MOVES THROUGH BUT
LIKELY NOT UNTIL LATE THIS AFTERNOON AT THIS POINT.
WEAKENING IN THE CONVECTION THIS EVENING WITH FOG AGAIN FORMING
OVERNIGHT AT MOST SITES...WITH FOG BECOMING DENSE AT
KLWB/KBCB...AND MAYBE KLYH IF SHOWERS OCCUR NEARBY.
TRUE FRONT EXPECTED TO NOT MOVE INTO AND THRU THE CWA UNTIL
TUESDAY MORNING...SO MONDAY WILL BE ANOTHER DAY OF SCATTERED
CONVECTION WITH THE LAST IN THE UPPER LEVEL SHORTWAVES MOVING
ACROSS INTERACTING WITH HUMID SFC CONDITIONS AND LOW LVL
CONVERGENCE. HOWEVER SINCE MOST WIDESPREAD COVERAGE NOT EXPECTED
UNTIL NEAR OR AFTER THE END OF THE VALID TAF PERIOD WONT INCLUDE
ANY SHRA/TSRA MENTION AFTER FOG/STRATUS FADES. ANTICIPATE MORE
FOG TUESDAY MORNING WITH DRIER AIR NOSING IN DURING THE DAY
TUESDAY. MOSTLY VFR EXPECTED THROUGH LATE WEEK OUTSIDE OF ANY
OVERNIGHT FOG.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS/WP
NEAR TERM...JH/WP
SHORT TERM...NF
LONG TERM...KK
AVIATION...DS/JH/RCS/WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1132 AM CDT SUN SEP 1 2013
.AVIATION/18Z TAFS/...LINGERING IFR/MVFR STRATUS FIELD ACROSS SC
WI WITH COLD FRONT APPROACHING FROM SW WI. EXPECTING SCT TSRA
DEVELOPMENT. HRRR HAS A PRETTY GOOD HANDLE ON TRENDS...SHOWING
WINDOW FOR STORMS 18-00Z...NW-SE ACROSS THE CWA. LOW SVR THREAT
PER SWODY1...BUT ISOLD STG/SVR PLAUSIBLE. COLD ADVECTION KICKS IN
TONIGHT WITH LOW LEVEL THERMAL TROUGH ACROSS WI ON MONDAY. EXPECT
DECENT AMOUNT OF STRATOCU IN THIS REGIME. 850 TEMPS 8-10C.
PC
&&
.PREV DISCUSSION... /ISSUED 330 AM CDT SUN SEP 1 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
WEBCAMS AND SURFACE OBS SHOWING EXPANDING AREAS OF DENSE FOG OVER
SOUTHEAST CWA LAST SEVERAL HOURS. ALSO SEVERAL COUNTY SHERIFFS
REPORTING AREAS OF DENSE FOG CENTERED ON WASHINGTON AND WAUKESHA
COUNTIES. UPSTREAM MID-HIGH CLOUDS FROM MN CONVECTION CONTINUING TO
THIN SO THINKING AREAS OF DENSE FOG WILL PERSIST THROUGH 13Z OR SO
IN THE EASTERN CWA. HENCE POSTED DENSE FOG ADVY FOR NOW. HELD OFF
ON INCLUDING AREAS FURTHER WEST DUE TO MORE CLOUDS AND SOME INCREASE
IN BOUNDARY LAYER MIXING.
STRONG FORCING ASSOCIATED WITH VIGOROUS SHORT WAVE OVER NE MN/WRN LK
SUPERIOR WILL REMAIN MOSTLY NORTH OF CWA TODAY...HOWEVER WEAKER LIFT
ASSOCIATED WITH LOBE OF DIFFERENTIAL VORTICITY WILL PASS THROUGH
DURING THE DAY. AXIS OF Q-VECTOR CONVERGENCE DOES COINCIDE WITH LOW
LEVEL MOISTURE FLUX CONVERGENCE PASSING THRU WESTERN CWA THIS
MORNING...AND LATE MORNING AND EARLY AFTN IN THE EAST. WITH LOW
LEVEL FRONTOGENETICAL FORCING SPLITTING TO THE NORTH AND SOUTH AS
FRONT PASSES THRU SRN WI...WL CONTINUE WITH HIGH CHANCE POPS TODAY.
BULK SHEAR INCREASES TO AROUND 30 KNOTS WITH CAPES AROUND 2000 J.
CAN NOT RULE OUT MULTI-CELLS WITH A FEW SUPERCELLS VICINITY OF
FRONT...ESPECIALLY IN THE SOUTHEAST CWA THIS AFTN. EXPC ANY
CONVECTION TO END BY EARLY EVENING EXCEPT A FEW STRAGGLERS MAY HANG
ON IN THE FAR EAST. OTHER DRIER AND LESS HUMID CONDITIONS WILL
SETTLE IN TONIGHT. MAY BE SOME LOW CLOUDS ACCOMPANYING COLD AIR
ADVECTION OVERNIGHT.
LABOR DAY AND TUESDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
HIGH PRESSURE WILL BUILD INTO THE AREA ON LABOR DAY. THE MAIN
ISSUE AT THIS POINT IS FIGURING OUT HOW MUCH SKY COVER THERE WILL
BE. MODELS DO TRY AND HOLD ONTO SOME LOW LEVEL MOISTURE THROUGH
MUCH OF THE DAY...WITH SOUNDINGS SUGGESTING AT LEAST SCATTERED TO
MAYBE EVEN BROKEN CLOUDS INTO THE AFTERNOON. MOISTURE IS PRETTY
THIN THOUGH...SO MAY NOT TAKE MUCH TO SCATTER OUT THE CLOUDS AS
THE HIGH MOVES IN. BUMPED SKY COVER UP A BIT FROM MOSTLY CLEAR
SKIES. OTHERWISE...STILL LOOKS LIKE A PRETTY PLEASANT DAY WITH
TEMPS A FEW DEGREES BELOW NORMAL.
THE HIGH WILL BE ABOUT RIGHT OVERHEAD BY TUESDAY MORNING...SO KEPT
PATCHY TO AREAS OF FOG IN THE FORECAST FOR LATE MONDAY NIGHT AND
EARLY TUESDAY MORNING. SHOULD THEN SEE MOSTLY SUNNY SKIES THROUGH
THE DAY TUESDAY UNDER THE HIGH...WITH TEMPS RECOVERING BACK TO
AROUND NORMAL FOR EARLY SEPTEMBER.
WEDNESDAY THROUGH SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
HIGH PRESSURE WILL PERSIST THOUGH THURSDAY...WITH MOSTLY CLEAR TO
PARTLY CLOUDY SKIES LIKELY. LOOKS LIKE TEMPS MAY CREEP BACK TO A
COUPLE OR FEW DEGREES ABOVE NORMAL THROUGH MID WEEK.
LATEST MODELS SUGGEST IT MAY BE EVEN MILDER FRIDAY AND SATURDAY AS
UPPER RIDGING BUILDS IN FROM THE WEST. WITH THE SFC HIGH PUSHING ON
TO THE SOUTH...THE DOOR MAY OPEN BACK UP FOR SHOWER/STORM CHANCES.
NOT REALLY SEEING ANYTHING TO GRAB ONTO IN THE MODELS AT THIS POINT
THOUGH...SO KEPT THE FORECAST MAINLY DRY.
AVIATION/12Z TAFS/...A BLEND OF LOW CLOUDS AND FOG WILL AFFECT TAF
SITES EARLY THIS MORNING. WL BE WATCHING COLD FRONT SLIDE ACROSS
SOUTHERN WI LATER THIS MORNING THROUGH MID-AFTERNOON. BETTER CHANCE
FOR A 1-2 HOUR DURATION OF THUNDER AFFECTING EASTERN TAF SITES
DURING THE AFTN. PERIOD OF MVFR CLOUDS MAY ACCOMPANY COOLER AIR
SAGGING SOUTH ACROSS SOUTHERN WI TONIGHT INTO EARLY MONDAY.
MARINE...STEEPENING LOW LEVEL LAPSE RATES ASSOCIATED WITH COLDER
AIR SAGGING SOUTH ACROSS LAKE MI TONIGHT BEHIND COLD FRONT WILL
RESULT IN GUSTY NORTH WINDS REACHING LAKE SURFACE. THESE GUSTS WILL
LIKELY REACH SMALL CRAFT ADVISORY LEVELS FOR A TIME. THE GUSTS WILL
DIMINISH ON MONDAY...HOWEVER HIGHER WAVE HEIGHTS WILL LINGER THROUGH
THE DAY. POSTED SMALL CRAFT ADVISORY BEGINNING IN THE NORTH THIS
EVENING...AND IN THE SOUTH AROUND MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 AM TO 7 PM CDT MONDAY FOR LMZ645-646.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM CDT MONDAY
FOR LMZ643-644.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...MBK
MONDAY THROUGH SATURDAY...DDV