Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/23/13
AREA FORECAST DISCUSSION...CORRECTED SYNOPSIS
NWS PHOENIX AZ
249 PM MST WED AUG 21 2013
.SYNOPSIS...
A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE
IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO
THIS WEEKEND. INCREASED PRECIPITATION CHANCES WILL LINGER THROUGH
EARLY NEXT WEEK.
&&
.DISCUSSION...
WELL-DEFINED VORT MAX ACROSS NORTHERN SONORA CONTINUES ITS TREK
WESTWARD THIS AFTERNOON. SEVERAL SMALLER VORTICES ARE ALSO EVIDENT
ON SATELLITE ACROSS AZ...WHICH HAVE CONTRIBUTED TO A CLOUDY DAY
ACROSS SOUTH-CENTRAL AZ. MEANWHILE...TEMPERATURES HAVE STRUGGLED TO
REACH THE ONE HUNDRED DEGREE MARK IN MANY SPOTS INCLUDING THE
PHOENIX AREA. ISOLATED SHOWERS/SPRINKLES ON THE WESTERN FLANK OF THE
VORT HAVE PERSISTED AS WELL...THOUGH LATEST HRRR INDICATES THAT THEY
WILL GRADUALLY DISSIPATE THIS AFTERNOON.
FURTHER EAST WHERE INSOLATION HAS BEEN STRONGER...ISOLATED
CONVECTION HAS INITIATED AND IS LIKELY BEING AIDED BY INCREASING
DIFFERENTIAL VORTICITY ADVECTION IN THE VICINITY OF GILA COUNTY.
SUITE OF CONVECTIVE ALLOWING MODELS SUGGESTS THAT ACTIVITY WILL
MIGRATE WESTWARD INTO THE LOWER DESERTS...WHERE IT WILL BE MET WITH
INHIBITION FROM THE ANTECEDENT CLOUDINESS. NEVERTHELESS...CONDITIONS
REMAIN SUFFICIENTLY MOIST FOR ISOLATED STORMS. MODELS ARE IN GOOD
AGREEMENT THAT THE PLUME OF DEEPER MOISTURE WILL SHIFT WESTWARD
OVERNIGHT TOWARDS THE LOWER CO RIVER VALLEY AND A SLIGHT CHANCE OF
PRECIPITATION WILL PERSIST AFTER MIDNIGHT IN THESE AREAS. ANY STORMS
THAT DEVELOP WILL BE CAPABLE OF PRODUCING STRONG WIND GUSTS AND
AREAS OF BLOWING DUST.
&&
.PREVIOUS DISCUSSION...
A SLIGHT INCREASE IN MOISTURE IS NOTED FROM THE GFS/EUROPEAN MODELS
ACROSS THE DESERTS ON THURSDAY...MEANWHILE A SLIGHT DECREASE IN MID
LEVEL MOISTURE IS ADVERTISED TO MOVE INTO EASTERN ARIZONA THURSDAY
AFTERNOON. MAY END UP SEEING PRECIP DEVELOP ACROSS THE DESERTS WEST
OF PHOENIX TOWARD THE AZ/CA BORDER THURSDAY AFTERNOON...BUT
INSTABILITY REMAINS MEAGER AND AGAIN...NO OBVIOUS TRIGGER ADVERTISED
ASIDE FROM OROGRAPHIC FORCING. EXPECTING A FAIRLY SIMILAR DAY
THURSDAY WITH STORMS EAST OF PHOENIX AND A FEW ISOLATED SHOWERS TO
THE WEST.
CHANGES APPEAR ON THE HORIZON STARTING AS EARLY AS FRIDAY AS SEVERAL
RUNS OF THE EUROPEAN AND THE GFS INDICATE DEEP SOUTHERLY FLOW ACROSS
THE AREA COURTESY OF AN INVERTED TROUGH OVER MEXICO AND A TROPICAL
SYSTEM SOUTH OF BAJA CALIFORNIA. MOISTURE ADVECTION SHOULD BEGIN ON
FRIDAY...WITH THE REAL PUSH OF 2+ INCH PWATS /12-14 G/KG 1000-700MB
MEAN MIXING RATIOS/ ARRIVING DURING THE DAY ON SATURDAY. GFS
INTEGRATED WATER VAPOR TRANSPORT DATA SUGGESTS THE STRONGEST PUSH OF
MOISTURE AS EARLY AS SATURDAY AFTERNOON...HOWEVER THE EUROPEAN MODEL
APPEARS TO BE 12-18 HRS SLOWER. ITS ALWAYS TOUGH TRYING TO FIGURE
OUT WHEN CONVECTION WILL DEVELOP AFTER SUCH A SIGNIFICANT SURGE OF
MOISTURE. TYPICALLY THE BOUNDARY LAYER IS TOO STABLE FOR STORMS
DURING THE SURGE AND NEED ABOUT 12-24HRS TO RECOVER. WITH THE
BIGGEST INCREASE IN MOISTURE NOTED EARLY SATURDAY...THE GREATEST
CHANCE OF STORMS WOULD SEEMINGLY FOLLOW SATURDAY NIGHT INTO SUNDAY.
I WILL CONTINUE WITH THE TREND OF INCREASING POPS STARTING ON FRIDAY
THROUGH THE DAY SUNDAY WITH THE HIGHEST VALUES /ABOVE 40-50 PERCENT
CWA-WIDE/ ON SUNDAY. NONE OF THE OPERATIONAL MODELS ARE EAGER TO GET
RID OF THE MOISTURE EITHER ONCE IT ARRIVES...WITH BOTH EURO/GFS
MODELS KEEPING MIXING RATIOS NORTH OF 10 G/KG WELL INTO THE MIDDLE
OF NEXT WEEK. WITH A COUPLE OF INVERTED TROUGHS ADVERTISED TO MOVE
THROUGH THE AREA NEXT WEEK...COULD EASILY SEE ABOVE NORMAL PRECIP
CHANCES LINGERING THROUGH NEXT WEEK.
HIGHS AND LOWS SHOULD START CREEPING DOWNWARD EACH DAY AS MOISTURE
STEADILY INCREASES. WEEKEND HIGHS /ESPECIALLY ON SUNDAY/ ARE
ANYBODYS GUESS AT THIS POINT. IF EITHER DAY ENDS UP BEING A
RAINY/CLOUDY DAY...HIGHS COULD BE IN THE 80S. WITH BREAKS IN THE
CLOUDS...PROBABLY LOOKING AT MID 90S OR AROUND 100. BELOW NORMAL
TEMPS SEEMS LIKE A SAFE BET FROM SATURDAY ONWARD GIVEN SUCH HIGH
PWATS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXTENSIVE MID-LEVEL CLOUDS AND A FEW LIGHT VIRGA SHOWERS/SPRINKLES
WILL DIMINISH THIS AFTERNOON WHILE SHOWERS AND THUNDERSTORMS DEVELOP
ACROSS THE HIGH TERRAIN EAST OF PHOENIX. AS WITH YESTERDAY...THE
MAIN THREAT TODAY WILL BE MODEST OUTFLOW WINDS AND A SLIGHT
POTENTIAL FOR SOME BLOWING DUST. THE BACKGROUND WIND FLOW WILL
MOSTLY REMAIN EASTERLY TODAY DUE TO THE COOLER AND CLOUDIER
CONDITIONS...BUT WINDS WILL BE VARIABLE OR SWITCH TO A
WESTERLY/NORTHWESTERLY DIRECTION FOR A FEW HOURS LATE THIS
AFTERNOON.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
MOSTLY CLEAR SKIES TO PREVAIL THROUGH THE TAF PERIOD...WITH ONLY
SOME PATCHY MID-HIGH LEVEL CLOUDS EXPECTED. WINDS WILL MAINLY BE ON
THE LIGHT SIDE...AND FOLLOW THE USUAL DIURNAL TRENDS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
A SIGNIFICANT UPSWING IN ATMOSPHERIC MOISTURE CONTENT AND
THUNDERSTORM ACTIVITY IS ANTICIPATED THIS WEEKEND AS MOISTURE FROM
LOW LATITUDES MAKES IT WAY INTO ARIZONA AND SOUTHEAST CALIFORNIA.
THUS HUMIDITIES WILL INCREASE SUBSTANTIALLY. TEMPERATURES WILL ALSO
DECREASE...TO BELOW NORMAL BY SUNDAY...BEFORE INCREASING AGAIN
MONDAY AND TUESDAY TO NEAR NORMAL. STRONGER SOUTHERLY WINDS ARE ALSO
EXPECTED ON SATURDAY...MAINLY OVER SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA...WITH LESS BREEZINESS THEREAFTER EXCEPT FOR
THUNDERSTORM DRIVEN WINDS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...LEINS
AVIATION...KUHLMAN
FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
220 PM MST WED AUG 21 2013
.SYNOPSIS...
A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE
IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO
THIS WEEKEND. INCREASED PRECIP CHANCES WILL LINGER THROUGH EARLY
NEXT WEEK.
&&
.DISCUSSION...
WELL-DEFINED VORT MAX ACROSS NORTHERN SONORA CONTINUES ITS TREK
WESTWARD THIS AFTERNOON. SEVERAL SMALLER VORTICES ARE ALSO EVIDENT
ON SATELLITE ACROSS AZ...WHICH HAVE CONTRIBUTED TO A CLOUDY DAY
ACROSS SOUTH-CENTRAL AZ. MEANWHILE...TEMPERATURES HAVE STRUGGLED TO
REACH THE ONE HUNDRED DEGREE MARK IN MANY SPOTS INCLUDING THE
PHOENIX AREA. ISOLATED SHOWERS/SPRINKLES ON THE WESTERN FLANK OF THE
VORT HAVE PERSISTED AS WELL...THOUGH LATEST HRRR INDICATES THAT THEY
WILL GRADUALLY DISSIPATE THIS AFTERNOON.
FURTHER EAST WHERE INSOLATION HAS BEEN STRONGER...ISOLATED
CONVECTION HAS INITIATED AND IS LIKELY BEING AIDED BY INCREASING
DIFFERENTIAL VORTICITY ADVECTION IN THE VICINITY OF GILA COUNTY.
SUITE OF CONVECTIVE ALLOWING MODELS SUGGESTS THAT ACTIVITY WILL
MIGRATE WESTWARD INTO THE LOWER DESERTS...WHERE IT WILL BE MET WITH
INHIBITION FROM THE ANTECEDENT CLOUDINESS. NEVERTHELESS...CONDITIONS
REMAIN SUFFICIENTLY MOIST FOR ISOLATED STORMS. MODELS ARE IN GOOD
AGREEMENT THAT THE PLUME OF DEEPER MOISTURE WILL SHIFT WESTWARD
OVERNIGHT TOWARDS THE LOWER CO RIVER VALLEY AND A SLIGHT CHANCE OF
PRECIPITATION WILL PERSIST AFTER MIDNIGHT IN THESE AREAS. ANY STORMS
THAT DEVELOP WILL BE CAPABLE OF PRODUCING STRONG WIND GUSTS AND
AREAS OF BLOWING DUST.
&&
.PREVIOUS DISCUSSION...
A SLIGHT INCREASE IN MOISTURE IS NOTED FROM THE GFS/EUROPEAN MODELS
ACROSS THE DESERTS ON THURSDAY...MEANWHILE A SLIGHT DECREASE IN MID
LEVEL MOISTURE IS ADVERTISED TO MOVE INTO EASTERN ARIZONA THURSDAY
AFTERNOON. MAY END UP SEEING PRECIP DEVELOP ACROSS THE DESERTS WEST
OF PHOENIX TOWARD THE AZ/CA BORDER THURSDAY AFTERNOON...BUT
INSTABILITY REMAINS MEAGER AND AGAIN...NO OBVIOUS TRIGGER ADVERTISED
ASIDE FROM OROGRAPHIC FORCING. EXPECTING A FAIRLY SIMILAR DAY
THURSDAY WITH STORMS EAST OF PHOENIX AND A FEW ISOLATED SHOWERS TO
THE WEST.
CHANGES APPEAR ON THE HORIZON STARTING AS EARLY AS FRIDAY AS SEVERAL
RUNS OF THE EUROPEAN AND THE GFS INDICATE DEEP SOUTHERLY FLOW ACROSS
THE AREA COURTESY OF AN INVERTED TROUGH OVER MEXICO AND A TROPICAL
SYSTEM SOUTH OF BAJA CALIFORNIA. MOISTURE ADVECTION SHOULD BEGIN ON
FRIDAY...WITH THE REAL PUSH OF 2+ INCH PWATS /12-14 G/KG 1000-700MB
MEAN MIXING RATIOS/ ARRIVING DURING THE DAY ON SATURDAY. GFS
INTEGRATED WATER VAPOR TRANSPORT DATA SUGGESTS THE STRONGEST PUSH OF
MOISTURE AS EARLY AS SATURDAY AFTERNOON...HOWEVER THE EUROPEAN MODEL
APPEARS TO BE 12-18 HRS SLOWER. ITS ALWAYS TOUGH TRYING TO FIGURE
OUT WHEN CONVECTION WILL DEVELOP AFTER SUCH A SIGNIFICANT SURGE OF
MOISTURE. TYPICALLY THE BOUNDARY LAYER IS TOO STABLE FOR STORMS
DURING THE SURGE AND NEED ABOUT 12-24HRS TO RECOVER. WITH THE
BIGGEST INCREASE IN MOISTURE NOTED EARLY SATURDAY...THE GREATEST
CHANCE OF STORMS WOULD SEEMINGLY FOLLOW SATURDAY NIGHT INTO SUNDAY.
I WILL CONTINUE WITH THE TREND OF INCREASING POPS STARTING ON FRIDAY
THROUGH THE DAY SUNDAY WITH THE HIGHEST VALUES /ABOVE 40-50 PERCENT
CWA-WIDE/ ON SUNDAY. NONE OF THE OPERATIONAL MODELS ARE EAGER TO GET
RID OF THE MOISTURE EITHER ONCE IT ARRIVES...WITH BOTH EURO/GFS
MODELS KEEPING MIXING RATIOS NORTH OF 10 G/KG WELL INTO THE MIDDLE
OF NEXT WEEK. WITH A COUPLE OF INVERTED TROUGHS ADVERTISED TO MOVE
THROUGH THE AREA NEXT WEEK...COULD EASILY SEE ABOVE NORMAL PRECIP
CHANCES LINGERING THROUGH NEXT WEEK.
HIGHS AND LOWS SHOULD START CREEPING DOWNWARD EACH DAY AS MOISTURE
STEADILY INCREASES. WEEKEND HIGHS /ESPECIALLY ON SUNDAY/ ARE
ANYBODYS GUESS AT THIS POINT. IF EITHER DAY ENDS UP BEING A
RAINY/CLOUDY DAY...HIGHS COULD BE IN THE 80S. WITH BREAKS IN THE
CLOUDS...PROBABLY LOOKING AT MID 90S OR AROUND 100. BELOW NORMAL
TEMPS SEEMS LIKE A SAFE BET FROM SATURDAY ONWARD GIVEN SUCH HIGH
PWATS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXTENSIVE MID-LEVEL CLOUDS AND A FEW LIGHT VIRGA SHOWERS/SPRINKLES
WILL DIMINISH THIS AFTERNOON WHILE SHOWERS AND THUNDERSTORMS DEVELOP
ACROSS THE HIGH TERRAIN EAST OF PHOENIX. AS WITH YESTERDAY...THE
MAIN THREAT TODAY WILL BE MODEST OUTFLOW WINDS AND A SLIGHT
POTENTIAL FOR SOME BLOWING DUST. THE BACKGROUND WIND FLOW WILL
MOSTLY REMAIN EASTERLY TODAY DUE TO THE COOLER AND CLOUDIER
CONDITIONS...BUT WINDS WILL BE VARIABLE OR SWITCH TO A
WESTERLY/NORTHWESTERLY DIRECTION FOR A FEW HOURS LATE THIS
AFTERNOON.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
MOSTLY CLEAR SKIES TO PREVAIL THROUGH THE TAF PERIOD...WITH ONLY
SOME PATCHY MID-HIGH LEVEL CLOUDS EXPECTED. WINDS WILL MAINLY BE ON
THE LIGHT SIDE...AND FOLLOW THE USUAL DIURNAL TRENDS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
A SIGNIFICANT UPSWING IN ATMOSPHERIC MOISTURE CONTENT AND
THUNDERSTORM ACTIVITY IS ANTICIPATED THIS WEEKEND AS MOISTURE FROM
LOW LATITUDES MAKES IT WAY INTO ARIZONA AND SOUTHEAST CALIFORNIA.
THUS HUMIDITIES WILL INCREASE SUBSTANTIALLY. TEMPERATURES WILL ALSO
DECREASE...TO BELOW NORMAL BY SUNDAY...BEFORE INCREASING AGAIN
MONDAY AND TUESDAY TO NEAR NORMAL. STRONGER SOUTHERLY WINDS ARE ALSO
EXPECTED ON SATURDAY...MAINLY OVER SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA...WITH LESS BREEZINESS THEREAFTER EXCEPT FOR
THUNDERSTORM DRIVEN WINDS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...LEINS
AVIATION...KUHLMAN
FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS TUCSON AZ
215 PM MST WED AUG 21 2013
.SYNOPSIS...ISOLATED TO SCATTERED MOSTLY AFTERNOON AND EVENING
THUNDERSTORMS WILL PREVAIL THROUGH FRIDAY. THEREAFTER...INCREASING
MOISTURE FROM THE GULF OF CALIFORNIA WILL PROVIDE MORE COVERAGE OF
THUNDERSTORMS THIS WEEKEND. ABOVE NORMAL DAYTIME TEMPERATURES WILL
CONTINUE THROUGH FRIDAY FOLLOWED BY A COOLING TREND THIS WEEKEND.
&&
.DISCUSSION...ISOLATED SHOWERS/TSTMS LIMITED TO MAINLY THE HIGHER
TERRAIN OF SRN GRAHAM/COCHISE/ERN SANTA CRUZ COUNTIES AT THIS TIME.
CONVECTIVE DEBRIS CLOUDINESS CONTINUES TO SLOWLY ERODE ACROSS PIMA/
SOUTH CENTRAL PINAL COUNTIES. 21/19Z RUC HRRR FAVORS ERN SECTIONS
WITH PRECIP ECHOES THRU EARLY THIS EVENING FOLLOWED BY ADDITIONAL
WEAK ECHOES SPREADING WWD INTO PIMA/PINAL COUNTIES LATER TONIGHT.
THIS WILL TRANSLATE INTO SCATTERED SHOWERS/TSTMS THRU THIS EVENING
THEN ISOLATED SHOWERS/TSTMS LATE TONIGHT. EXPECT EVEN LESS COVERAGE
OF SHOWERS/TSTMS THUR AFTERNOON AND THUR EVENING.
FOCUS OF ATTENTION ON FRI TO THEN TURN TOWARD A TROPICAL SYSTEM THAT
IS EXPECTED TO CONTINUE TO DEVELOP SW OF SRN BAJA CALIFORNIA. DEEPER
MOISTURE WILL THEN ADVECT NORTHWARD INTO THIS FORECAST AREA THIS
WEEKEND. HAVE MADE ONLY VERY MINOR ADJUSTMENTS TO THE INHERITED
GRIDDED DATA POP FIELDS FRI-MON. THUS...SCATTERED SHOWERS/TSTMS FOR
MUCH OF SE AZ FRI AFTERNOON AND FRI EVENING WITH LESSER COVERAGE OF
SHOWERS/TSTMS LATE FRI NIGHT AND SAT MORNING. PRECIP CHANCES TO
INCREASE BY LATE SAT INTO SUN...WITH SCATTERED TO PERHAPS NUMEROUS
SHOWERS/TSTMS TO OCCUR.
A DEEP GENERALLY SELY FLOW IS PROGGED TO CONTINUE MON-WED. THIS
PATTERN SHOULD YIELD SCATTERED MAINLY AFTERNOON AND EVENING SHOWERS/
TSTMS GENERALLY FROM TUCSON EWD/SWD...AND ISOLATED COVERAGE OF
SHOWERS/TSTMS ACROSS WRN SECTIONS.
HIGH TEMPS THUR-FRI TO GENERALLY BE A FEW DEGS ABOVE NORMAL FOLLOWED
BY A COOLING TREND THIS WEEKEND. WARMER MON-TUE THEN NO SIGNIFICANT
CHANGE IN DAYTIME TEMPS FOR NEXT WED.
&&
.AVIATION...SCT TSRA/SHRA THRU THIS EVENING THEN ISOLD -TSRA/-SHRA
LATE TONIGHT. DRY CONDITIONS EXPECTED THURSDAY MORNING FOLLOWED BY
SCT TSRA/SHRA THURSDAY AFTERNOON. THE STRONGER TSRA WILL PRODUCE
MVFR CIGS/VSBYS...AND POTENTIALLY WIND GUSTS TO AROUND 45 KTS.
OTHERWISE...CLOUD DECKS 8-12K FT AGL AND SURFACE WIND GENERALLY LESS
THAN 10 KTS THRU THURSDAY MORNING OR 22/18Z. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT ISOLATED TO SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS THROUGH FRIDAY. MOISTURE WILL THEN BE ON THE
INCREASE THIS WEEKEND...RESULTING IN MORE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY. ABOVE NORMAL DAYTIME TEMPERATURES WILL
CONTINUE THROUGH FRIDAY...WITH COOLER TEMPERATURES THIS WEEKEND.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
BF/GZ
AREA FORECAST DISCUSSION
NWS PUEBLO CO
348 PM MDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 347 PM MDT WED AUG 21 2013
...FLASH FLOODING/LANDSPOUT THREAT INCREASING...ESPECIALLY FOR
TOMORROW...
CURRENTLY...
SHOWERS AND STORMS ARE MORE ABUNDANT THEN THIS TIME YESTERDAY...WITH
HUNDREDS OF CG STRIKES OCCURRING DURING THE LAST HOUR OVER THE STATE.
A SFC BOUNDARY IS SEEN IN THE MOSAIC RADAR DATA EXTENDING ACROSS
EAST CENTRAL CO AND BECOMING DIFFUSE OVER THE WESTERN PALMER DIVIDE
REGION. TEMPS HAVE RISEN WELL INTO THE 90S ACROSS THE PLAINS...WITH
TEMPS APPROACHING 100 OUT NEAR KLAA.
REST OF TODAY AND TONIGHT...
UPPER MOISTURE WILL CONTINUE TO INCREASE AND EXPECT SCTD SHOWERS AND
STORMS OVER THE HIGHER TRRN THROUGHOUT THIS AFTERNOON. HRRR IS A BIT
AGGRESSIVE OVER THE PIKES PEAK REGION THIS AFTERNOON AND WILL HAVE
TO WATCH THIS AREA FOR FLASH FLOOD PROBLEMS. THE HRRR AGRESSIVENESS
MAY BE IN RESPONSE TO THE BOUNDARY MENTIONED ABOVE. DWPTS HAVE BEEN
MIXING OUT A BIT BUT 30S AND 40S WERE STILL NOTED ACROSS THE
MTNS...WITH 40S AND 50S OVER THE PLAINS. WE WILL ALSO SEE A BETTER
CHANCE OF TSRA OVER THE PLAINS LATE THIS
AFTERNOON/EVENING...ESPECIALLY OVER THE PALMER DVD AND RATON MESA
REGION. WITH THE BOUNDARY OVER THE PALMER...MAY HAVE TO WATCH OUT
FOR A LANDSPOUT...ALBEIT THE PROBABILITY OF THIS IS LOW.
LATER TONIGHT I ANTICIPATE IT TO BE MAINLY DRY WITH PARTLY CLOUDY
SKIES.
THURSDAY...
BY TOMORROW AFTERNOON...BOUNDARY SHOULD LIE FROM KTAD TO NEAR KLAA.
NORTH OF THE FRONT...MOIST UPSLOPE FLOW WILL BE IN PLACE AND WE WILL
SEE A BETTER CHANCE OF STORMS OVER THE PLAINS. WITH THE BOUNDARY
OVER FAR SE CO...A BETTER CHANCE OF A LANDSPOUT TORNADO WILL BE
POSSIBLE...ESPECIALLY CONSIDERING THIS BOUNDARY WILL BE "COOKING"
ALL DAY TOMORROW AND CAPES SHOULD BE ABOUT 1000 J/KG AND WINDS
THROUGHOUT THE COLUMN WILL BE LIGHT.
FLASH FLOOD THREAT OVER THE BURN SCARS WILL BE HIGHER TOMORROW AS
MOISTURE WILL BE MORE ABUNDANT THROUGHOUT THE COLUMN...CAPES WILL BE
ABOUT 1500-2000 ACROSS THE PIKES PEAK REGION AND FLOW WILL BE RATHER
WEAK. THE LOCAL WRF HAS OVER AN INCH OF RAIN OVER THE WALDO LATE
TOMORROW AFTERNOON. CONTEMPLATED ON ISSUING A FLASH FLOOD WATCH BUT
THOUGHT IT BEST TO LET THE MID CREW ISSUE AS THEY WILL HAVE A COUPLE
MORE GUIDANCE RUNS TO LOOK AT.
EXPECT MAX TEMPS TO BE COOLER TOMORROW AS WE WILL SEE MORE CLOUDS
AND LOW LVL MOISTURE OVER THE REGION. HIGHS SHOULD ONLY BE IN THE
90-96F RANGE OVER THE PLAINS...WITH U80S OVER THE PALMER/RATON MESA
REGION. /HODANISH
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 347 PM MDT WED AUG 21 2013
LONGER TERM METEOROLOGICAL ISSUES REMAIN POPS AND TEMPERATURES.
SOME ADJUSTMENTS NEEDED FOR LONGER CYCLE AS UPPER RIDGE IS NOW
PROJECTED TO NOT PUSH AS FAR EAST AS EARLIER INDICATED...MEANING
THAT PRIMARY MOISTURE PLUME SHOULD REMAIN OVER WESTERN PORTIONS OF
THE FORECAST DISTRICT AND POINTS WEST DURING THE LONGER TERM.
THE UPPER RIDGE OF HIGH PRESSURE CENTERED OVER SOUTHERN COLORADO
THIS AFTERNOON IS STILL EXPECTED TO BECOME CENTERED OVER KANSAS
AND OKLAHOMA BY LATER FRIDAY NIGHT BEFORE SHIFTING INTO
MISSOUR(INSTEAD OF OVER ILLINOIS AS SOME PREVIOUS MODEL RUNS HAVE
INDICATED) BY WEDNESDAY.
AS THE UPPER RIDGE PUSHES EAST...FORECAST DISTRICT SHOULD STILL
EXPERIENCE INCREASING ATMOSPHERIC MOISTURE VALUES AT TIMES
...ESPECIALLY OVER WESTERN HIGHER TERRAIN LOCATIONS DURING THE
LONGER TERM.
AT THIS TIME...IT APPEARS THAT THE PRIMARY DEEPER MOISTURE FROM
THE DEEP TROPICS OFF THE WEST COAST OF MEXICO SHOULD REMAIN
FOCUSED OVER THE NEW MEXICO...UTAH AND WESTERN COLORADO REGION FROM
THIS WEEKEND INTO EARLY NEXT WEEK...THEREFORE WESTERN BURN SCARS
SUCH AS THE WEST FORK COMPLEX SHOULD NOTE THE HIGHEST POTENTIAL OF
BURN SCAR FLASH FLOODING DURING THIS TIME-FRAME. WFO PUEBLO WILL
CONTINUE TO MONITOR THIS POTENTIAL TREND CLOSELY.
FINALLY...CONTINUED ABOVE SEASONAL LATE AUGUST TEMPERATURES(ESPECIALLY
EASTERN SECTIONS) AS WELL AS GENERALLY LOW-GRADE GRADIENT WINDS
ARE ANTICIPATED OVER THE FORECAST DISTRICT THROUGH THE LONGER TERM.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 347 PM MDT WED AUG 21 2013
VFR CONDITIONS ARE ANTICIPATED AT ALL 3 TAF SITES...KPUB...KALS AND
KCOS NEXT 24H. WINDS WILL BE LIGHT AND DIURNALLY DRIVEN. AN ISOLD
TSRA MAY AFFECT THE EACH OF THE TAF SITES LATE TOMORROW AFTERNOON
BUT PROBABILITY OF THIS HAPPENING IS TOO LOW TO MENTION EXPLICITLY
IN TAF PRODUCT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PUEBLO CO
331 PM MDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM MDT WED AUG 21 2013
...FLASH FLOODING/LANDSPOUT THREAT INCREASING...ESPECIALLY FOR
TOMORROW...
CURRENTLY...
SHOWERS AND STORMS ARE MORE ABUNDANT THEN THIS TIME YESTERDAY...WITH
HUNDREDS OF CG STRIKES OCCURRING DURING THE LAST HOUR OVER THE STATE.
A SFC BOUNDARY IS SEEN IN THE MOSAIC RADAR DATA EXTENDING ACROSS
EAST CENTRAL CO AND BECOMING DIFFUSE OVER THE WESTERN PALMER DIVIDE
REGION. TEMPS HAVE RISEN WELL INTO THE 90S ACROSS THE PLAINS...WITH
TEMPS APPROACHING 100 OUT NEAR KLAA.
REST OF TODAY AND TONIGHT...
UPPER MOISTURE WILL CONTINUE TO INCREASE AND EXPECT SCTD SHOWERS AND
STORMS OVER THE HIGHER TRRN THROUGHOUT THIS AFTERNOON. HRRR IS A BIT
AGGRESSIVE OVER THE PIKES PEAK REGION THIS AFTERNOON AND WILL HAVE
TO WATCH THIS AREA FOR FLASH FLOOD PROBLEMS. THE HRRR AGRESSIVENESS
MAY BE IN RESPONSE TO THE BOUNDARY MENTIONED ABOVE. DWPTS HAVE BEEN
MIXING OUT A BIT BUT 30S AND 40S WERE STILL NOTED ACROSS THE
MTNS...WITH 40S AND 50S OVER THE PLAINS. WE WILL ALSO SEE A BETTER
CHANCE OF TSRA OVER THE PLAINS LATE THIS
AFTERNOON/EVENING...ESPECIALLY OVER THE PALMER DVD AND RATON MESA
REGION. WITH THE BOUNDARY OVER THE PALMER...MAY HAVE TO WATCH OUT
FOR A LANDSPOUT...ALBEIT THE PROBABILITY OF THIS IS LOW.
LATER TONIGHT I ANTICIPATE IT TO BE MAINLY DRY WITH PARTLY CLOUDY
SKIES.
THURSDAY...
BY TOMORROW AFTERNOON...BOUNDARY SHOULD LIE FROM KTAD TO NEAR KLAA.
NORTH OF THE FRONT...MOIST UPSLOPE FLOW WILL BE IN PLACE AND WE WILL
SEE A BETTER CHANCE OF STORMS OVER THE PLAINS. WITH THE BOUNDARY
OVER FAR SE CO...A BETTER CHANCE OF A LANDSPOUT TORNADO WILL BE
POSSIBLE...ESPECIALLY CONSIDERING THIS BOUNDARY WILL BE "COOKING"
ALL DAY TOMORROW AND CAPES SHOULD BE ABOUT 1000 J/KG AND WINDS
THROUGHOUT THE COLUMN WILL BE LIGHT.
FLASH FLOOD THREAT OVER THE BURN SCARS WILL BE HIGHER TOMORROW AS
MOISTURE WILL BE MORE ABUNDANT THROUGHOUT THE COLUMN...CAPES WILL BE
ABOUT 1500-2000 ACROSS THE PIKES PEAK REGION AND FLOW WILL BE RATHER
WEAK. THE LOCAL WRF HAS OVER AN INCH OF RAIN OVER THE WALDO LATE
TOMORROW AFTERNOON. CONTEMPLATED ON ISSUING A FLASH FLOOD WATCH BUT
THOUGHT IT BEST TO LET THE MID CREW ISSUE AS THEY WILL HAVE A COUPLE
MORE GUIDANCE RUNS TO LOOK AT.
EXPECT MAX TEMPS TO BE COOLER TOMORROW AS WE WILL SEE MORE CLOUDS
AND LOW LVL MOISTURE OVER THE REGION. HIGHS SHOULD ONLY BE IN THE
90-96F RANGE OVER THE PLAINS...WITH U80S OVER THE PALMER/RATON MESA
REGION. /HODANISH
.LONG TERM...(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 330 PM MDT WED AUG 21 2013
LONGER TERM METEOROLOGICAL ISSUES REMAIN POPS AND TEMPERATURES.
SOME ADJUSTMENTS NEEDED FOR LONGER CYCLE AS UPPER RIDGE IS NOW
PROJECTED TO NOT PUSH AS FAR EAST AS EARLIER INDICATED...MEANING
THAT PRIMARY MOISTURE PLUME SHOULD REMAIN OVER WESTERN PORTIONS OF
THE FORECAST DISTRICT AND POINTS WEST DURING THE LONGER TERM.
THE UPPER RIDGE OF HIGH PRESSURE CENTERED OVER SOUTHERN COLORADO
THIS AFTERNOON IS STILL EXPECTED TO BECOME CENTERED OVER KANSAS
AND OKLAHOMA BY LATER FRIDAY NIGHT BEFORE SHIFTING INTO
NORTH-CENTRAL KANSAS(INSTEAD OF OVER ILLINOIS AS SOME PREVIOUS
MODEL RUNS HAVE INDICATED) BY WEDNESDAY.
AS THE UPPER RIDGE PUSHES EAST...FORECAST DISTRICT SHOULD STILL
EXPERIENCE INCREASING ATMOSPHERIC MOISTURE VALUES AT TIMES
...ESPECIALLY OVER WESTERN HIGHER TERRAIN LOCATIONS DURING THE
LONGER TERM.
AT THIS TIME...IT APPEARS THAT THE PRIMARY DEEPER MOISTURE FROM
THE DEEP TROPICS OFF THE WEST COAST OF MEXICO SHOULD REMAIN
FOCUSED OVER THE NEW MEXICO...UTAH AND WESTERN COLORADO REGION FROM
THIS WEEKEND INTO EARLY NEXT WEEK...THEREFORE WESTERN BURN SCARS
SUCH AS THE WEST FORK COMPLEX SHOULD NOTE THE HIGHEST POTENTIAL OF
BURN SCAR FLASH FLOODING DURING THIS TIME-FRAME. WFO PUEBLO WILL
CONTINUE TO MONITOR THIS POTENTIAL TREND CLOSELY.
FINALLY...CONTINUED ABOVE SEASONAL LATE AUGUST TEMPERATURES(ESPECIALLY
EASTERN SECTIONS) AS WELL AS GENERALLY LOW-GRADE GRADIENT WINDS
ARE ANTICIPATED OVER THE FORECAST DISTRICT THROUGH THE LONGER TERM.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 330 PM MDT WED AUG 21 2013
VFR CONDITIONS ARE ANTICIPATED AT ALL 3 TAF SITES...KPUB...KALS AND
KCOS NEXT 24H. WINDS WILL BE LIGHT AND DIURNALLY DRIVEN. AN ISOLD
TSRA MAY AFFECT THE EACH OF THE TAF SITES LATE TOMORROW AFTERNOON
BUT PROBABILITY OF THIS HAPPENING IS TOO LOW TO MENTION EXPLICITLY
IN TAF PRODUCT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1015 PM EDT THU AUG 22 2013
.SYNOPSIS...
WARM AND MUGGY CONDITIONS CONTINUE TONIGHT AHEAD OF AN APPROACHING
COLD FRONT...ALONG WITH THE RISK OF AN ISOLATED SHOWER/THUNDERSTORM.
THE FRONT WILL MOVE OFFSHORE FRIDAY PROVIDING DRY...COOLER AND LESS
HUMID CONDITIONS INTO THIS WEEKEND. DRY WEATHER LINGERS INTO MONDAY
BUT AN UNSETTLED WEATHER PATTERN MAY SET UP FOR MUCH OF NEXT WEEK AS
THUNDERSTORM COMPLEXES MOVE ACROSS THE GREAT LAKES AND POSSIBLY INTO
NEW ENGLAND. TEMPERATURES NEXT WEEK WILL BE NEAR NORMAL BUT BECOMING
INCREASING HUMID BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1030 PM UPDATE...
CONCERNING SHOWERS AND THUNDERSTORMS...THERE IS A CONTINUED
EXPECTATION OF ACTIVE WEATHER ALONG THE COLD FRONT TO INTERACT
WITH THE STRETCHED DRIER NON-CONVECTIVE AIRMASS FROM THE LOWER
HUDSON VALLEY NORTHEASTWARD ACROSS INTERIOR SOUTHERN NEW ENGLAND
TO THE COASTLINE OF MAINE. FOLLOWING CLOSELY WITH NEAR-TERM MODEL
GUIDANCE /HRRR AND RAP SOLUTIONS/...INSTABILITY AS INDICATED BY
MLCAPES SHOULD DIMINISH AS THE BOUNDARY LAYER DECOUPLES AND ACTIVE
WEATHER INTERACTS WITH THE DRIER AIRMASS /SEE THE 0Z GRAY MAINE
SOUNDING/.
AS TO THE LOW CLOUDS AND FOG ALONG THE SOUTHCOAST...SURFACE
SOUTHERLY COMPONENT TO THE PREVAILING FLOW WILL KEEP HIGH
DEWPOINTS ACROSS THE REGION PRIOR TO COLD FRONTAL PASSAGE TOWARDS
MORNING. THE NOCTURNAL COOLING OF THE BOUNDARY LAYER BENEATH THE
LOW-LEVEL STABLE DRY INVERSION /SEE THE 0Z CHATHAM SOUNDING/ WILL
RESULT IN SURFACE TEMPERATURES TO COOL TO THE DEWPOINT ALLOWING FOR
PERSISTENCE OF PATCHY DENSE FOG DOWN TO A QUARTER MILE OR LESS...
MAINLY ALONG THE SOUTH COAST INCLUDING THE CAPE AND THE ISLANDS. A
DENSE FOG ADVISORY MAY BE NECESSARY.
IMPROVEMENT EXPECTED BEHIND THE COLD FRONT WITH BACKING WINDS OUT
OF THE WEST-NORTHWEST WITH USHERANCE OF DRIER AIR. EXPECTING LOWS
AROUND THE LOW 60S ACROSS NORTHERN AND WESTERN NEW ENGLAND...WHILE
REMAINING MILD AROUND THE UPPER 60S FOR FAR SOTUHERN AND EASTERN
NEW ENGLAND...ESPECIALLY CLOSER TO THE WATER.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
FRIDAY...
COLD FRONT WILL BE ACROSS SOUTHEAST MASS BY THE MORNING HOURS AND
STALL JUST SOUTH OF THE AREA. AS WELL THE UPPER LEVEL TROUGH WILL
CONTINUE TO AMPLIFY WITH THE AXIS OF THE TROUGH MOVING OVER
SOUTHERN NEW ENGLAND. EXPECT ANY ACTIVITY TO DISSIPATE BY THE
MORNING HOURS TOMORROW WITH A CHANCE OF LINGERING SHOWERS ACROSS
SE MASS BY MID- MORNING. EXPECT CLOUDS TO BE AROUND FOR MOST OF
THE DAY EVEN THOUGH MODELS ARE INDICATING A GOOD AMOUNT OF DRY
AIR. WITH THE TROUGH AXIS MOVING THROUGH EXPECT DIURNAL CU TO BE
ABUNDANT. CONCERNED ABOUT THE EAST COAST BEHIND THE FRONTAL
PASSAGE. AS WIND SHIFT TO A MORE NORTHERLY DIRECTION...BELIEVE A
MORE NORTHEAST WIND DIRECTION WILL BE APPARENT ALONG THE COAST.
THIS WILL ALLOW FOR MARINE STRATUS TO MOVE INLAND AND PERHAPS KEEP
TEMPERATURES A LOT COOLER THAN FORECASTED. HAVE A LOW CONFIDENCE
IF THIS WILL OCCUR BUT WANT TO MENTION THE POSSIBILITY FOR NOW.
CONTINUED TO MENTION AN ISOLATED SHOWER FOR TOMORROW AFTERNOON
BEHIND THE FRONT AS STEEPENING LAPSE RATES FROM DIURNAL HEATING AND
SOME LINGERING MOISTURE WILL ALLOW FOR A SPOT SHOWER. BEST LOCATIONS
WILL BE ACROSS THE EASTERN HALF OF THE AREA...CLOSER TO THE FRONT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* DRY WEATHER THIS WEEKEND WITH MILD DAYS AND COOL NIGHTS
* TEMPS SEASONABLY WARM NEXT WEEK BUT BECOMING MORE HUMID
* ACTIVE WEATHER PATTERN POSSIBLE NEXT WEEK
OVERVIEW...
GUIDANCE IN GOOD AGREEMENT ON OVERALL PATTERN DURING THIS FORECAST
PERIOD WHICH FEATURES A STRONG RIDGE ALOFT /591 DAM/ OVER THE
PLAINS/MS VALLEY WITH A MEAN TROUGH OVER THE MARITIMES AND NORTHWEST
ATLANTIC. THERE IS VERY GOOD AGREEMENT/CONTINUITY WITH THESE LARGE
SCALE FEATURES. HOWEVER AS EXPECTED LOTS OF UNCERTAINTY ON THE
AMPLITUDE AND TIMING OF INDIVIDUAL SHORT WAVES AROUND THE PERIPHERY
OF THE RIDGE ACROSS THE GREAT LAKES AND THEN INTO THE NORTHEAST.
THIS IMPACTS THE TIMING OF POTENTIAL PRECIP EVENTS FOR OUR REGION.
IN ADDITION THIS SYNOPTIC CONFIGURATION WILL KEEP THE EXCESSIVE HEAT
SOUTH AND WEST OF NEW ENGLAND BUT ALSO PLACES OUR REGION IN A LOW
RISK AREA FOR TSTM COMPLEXES /RING OF FIRE/ CIRCULATING AROUND THE
NORTHERN PERIPHERY OF THE RIDGE AND INTO THE NORTHEAST. HOWEVER
GIVEN GOOD MODEL AGREEMENT ON THE HIGHER THETA-E AIRMASS TO REMAIN
SOUTH AND WEST OF NEW ENGLAND...ANY CONVECTION /ESPECIALLY STRONG
CONVECTION/ WOULD LIKELY TRACK IN A SIMILAR FASHION YIELDING A LOWER
RISK ACROSS NEW ENGLAND. HOWEVER CAN/T COMPLETELY RULE OUT
WEAKENING MCS CLIPPING WESTERN AND SOUTHERN NEW ENGLAND. GIVEN THIS
UNCERTAINTY WE FOLLOWED THE HIGHER POPS /20-30%/ FROM HPC AS GFS MOS
APPEARED TOO LOW.
DAILY DETAILS...
FRI NIGHT AND SAT/SUN...
FALL-LIKE AIRMASS FRI NIGHT AND SAT MORNING WITH A GUSTY NE WIND
/ESPECIALLY CAPE COD AND ISLANDS/ AND TEMPS IN THE 50S...A FEW U40S
WELL INLAND! VERY COMFORTABLE HUMIDITY WITH DEW PTS IN THE 40S SAT
AND 50S SUN.
FOR SAT...NEARBY MID LEVEL TROF AND COLD POOL ACTING ON LOW LEVEL
MOISTURE WILL LIKELY BRING AT LEAST SCT-BKN CU BUT THE MOISTURE IS
SHALLOW SO DRY WEATHER EXPECTED. LESS CU ON SUNDAY AS MID LEVEL
TEMPS WARM. TEMPS WILL BE A FEW DEGREES BELOW NORMAL SAT...MOSTLY IN
THE MID/UPPER 70S THEN WARMING INTO UPPER 70S AND LOWER 80S SUNDAY
IN RESPONSE TO INCREASING MID LEVEL TEMPS.
NEXT WEEK...
LOTS OF UNCERTAINTY ON TIMING AND AMPLITUDE OF SHORT WAVES EJECTING
SOUTHEAST FROM THE GREAT LAKES. 12Z ECMWF AND 12Z GFS EXHIBITING
FAIRLY LARGE SPREAD HERE AND ENSEMBLES STRUGGLING WITH RESOLVING
THIS SMALL SCALE FEATURES. THUS THERE IS A LOW RISK OF SHOWERS/TSTMS
FROM LATE MON INTO AT LEAST THU. DEFINITELY NOT A WASH OUT BUT SOME
SCATTERED SHOWERS/TSTMS FROM TIME TO TIME. TEMPS NEAR SEASONABLE BUT
WILL BECOME MORE HUMID WITH TIME. RISK OF STRONG TO SEVERE TSTMS IS
VERY LOW AS HIGHER THETA-E AIRMASS/BETTER INSTABILITY SHOULD BE
SHUNTED TO OUR SOUTHWEST ACROSS PA AND NJ. BUT AT THIS TIME RANGE IT
BEARS WATCHING.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...MODERATE CONFIDENCE.
7 PM UPDATE...
MAINLY DRY WITH JUST AN ISOLATED SHOWER/TSTM TONIGHT. BIGGER
CONCERN WILL BE AREAL EXTENT OF LOW CLOUDS FOG ALONG THE SOUTH
COAST. EXPECT THIS AREA OF IFR TO EXPAND ACROSS RI AND SOUTHEAST
MA TONIGHT. HOWEVER FRONTAL PASSAGE WILL IMPROVE CONDITIONS AROUND
06Z WESTERN NEW ENGLAND/09Z BOS-PVD AND AROUND 12Z CAPE
COD/NANTUCKET.
FRIDAY...SHOWER ACTIVITY WILL WANE BY MORNING AS A COLD FRONT
PUSHES THROUGH THE REGION. WINDS WILL SWITCH TO A MORE NORTHERLY
DIRECTION. DIURNAL CU WILL DEVELOP WITH POSSIBLE MVFR/IFR STRATUS
DECK ACROSS THE EAST COAST AS WINDS TAKE A MORE EASTERLY
DIRECTION. A FEW SHOWERS ARE ALSO POSSIBLE IN THE AFTERNOON.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. SOUTHERLY WINDS SWITCH
TO A MORE NORTHERLY/NORTHEAST DIRECTION BY FRIDAY. POSSIBLE
STRATUS DECK ON FRIDAY DROPPING CONDITIONS...LOW CONFIDENCE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHRA POSSIBLE THIS
AFTERNOON AND INTO THE OVERNIGHT HOURS.
OUTLOOK...FRI NIGHT THROUGH TUESDAY...
HIGH CONFIDENCE. MOSTLY VFR WITH SCT-BKN DIURNAL CU. LATE
NIGHT/EARLY MORNING PATCHY MVFR/IFR FOG POSSIBLE IN THE CT VALLEY.
WIDELY SCT SHOWERS/TSTMS POSSIBLE WESTERN AREAS LATE MON INTO TUE.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...MODERATE CONFIDENCE.
WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. GUSTY
WINDS WILL DIMINISH BY EVENING HOWEVER WAVES WILL SLOWLY INCREASE
AS A COLD FRONT APPROACHES THE REGION. FRONTAL PASSAGE WILL OCCUR
OVERNIGHT AND INTO FRIDAY MORNING SWITCHING THE WINDS TO A MORE
NORTHERLY DIRECTION. SEAS WILL INCREASE AS GUSTY WINDS NEAR 20KTS
WILL DEVELOP BEHIND THE FRONT ON FRIDAY.
OUTLOOK...FRI NIGHT THROUGH TUESDAY...
HIGH CONFIDENCE.
GUSTY NE WINDS AROUND 20 KT FRI NIGHT INTO EARLY SAT. DIMINISHING
WIND LATER SAT INTO SUN AS HIGH PRES CREST OVER SOUTHERN NEW
ENGLAND. SW WIND 20-25 KT POSSIBLE LATER MON INTO TUE ON BACK SIDE
OF DEPARTING HIGH. DRY WEATHER PREVAILS WITH A LOW RISK OF
SCATTERED SHOWERS/TSTMS LATE MON INTO TUE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...SIPPRELL
SHORT TERM...DUNTEN
LONG TERM...NOCERA
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN
AREA FORECAST DISCUSSION
NWS NEW YORK NY
827 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THIS EVENING AND MOVE ACROSS OVERNIGHT.
HIGH PRESSURE WILL THEN BUILD IN FROM FRIDAY THROUGH SUNDAY...AND
SETTLE TO THE SOUTH ON MONDAY. A SERIES OF FRONTS WILL MOVE ACROSS
THROUGH THE MID TO LATE PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
MUCH OF THE CWA HAS BEEN WORKED OVER THIS EVE. OUTSIDE OF A FEW
RESIDUAL SPRINKLES OVER THE E END OF LI...RADAR IS QUIET. THE
FRONT IS STILL ONLY ACROSS CNTRL NYSTATE.
THERE IS LIKELY SOME WEAK SUBSIDENCE IN THE WAKE OF THE SUBTLE MID
LVL SHRTWV PASSING OVER THE CWA. FOR THIS REASON...DROPPED PCPN
CHCS TIL ABOUT 00Z WHEN CONDITIONS WILL AGAIN BECOME FAVORABLE FOR
DEVELOPMENT AHEAD OF THE FRONT. EXTREME NWRN ZONES STILL HAVE OVER
2K J/KG OF SBCAPE.
CONVECTION WITH ACTUAL COLD FRONT IS FCST BY 17Z HRRR TO WEAKEN
VIA NIGHTTIME COOLING/STABILIZATION. LEFT IN SLIGHT CHANCE POP IN
SOME AREAS AFTER MIDNIGHT IN CASE ANY OF IT SHOULD SURVIVE THIS
FAR EAST. MOCLDY SKIES SHOULD CLEAR LATE AFTER FROPA...WITH LOWS
MAINLY 65-70.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH 6 PM FRIDAY/...
DRIER AIR WILL MOVE IN ON A N-NW BREEZE...WITH DEWPOINTS DROPPING
INTO THE 50S. HIGHS ON FRIDAY WILL REACH THE MID/UPPER 80S.
MOCLEAR SKIES AND DIMINISHING WINDS AS THE HIGH BUILDS OHD WILL
LEAD TO A COOLER NIGHT...WITH LOWER FRI NIGHT FROM THE MID 50S TO
MID 60S. EXCEPTION TO THIS MAY BE ACROSS LONG ISLAND...WHERE NWP
GUIDANCE HAS ADVERTISED MORE IN THE WAY OF CLOUDS AND POSSIBLE A
FEW LATE NIGHT SHOWERS AS AN UPPER LEVEL VORT MAX MOVES ACROSS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONTROLLING FEATURE ACROSS THE US WILL BE THE LARGE UPPER RIDGE
ACROSS THE CENTRAL US...WHICH WILL BUILD SLIGHTLY EASTWARD TOWARDS
THE EASTERN US BY THE END OF THE WEEKEND. THIS WILL PLACE THE REGION
ON THE NE EDGE OF UPPER RIDGING AND IN THE PATH OF A QUICK UPPER
FLOW FOR MUCH OF NEXT WEEK...WITH A SERIES OF WEAK DISTURBANCE
PASSING THROUGH THE NE.
AT THE SURFACE CANADIAN HIGH PRESSURE WILL BUILD INTO AND THEN SLIDE
ACROSS THE REGION THROUGH THE WEEKEND...PROVIDING FAIR AND
SEASONABLY WARM DAYTIME TEMPS. OVERNIGHT LOWS WILL LIKELY BE A BIT
CHILLY ACROSS FAR OUTLYING AREAS SAT NIGHT WITH GOOD RADIATIONAL
COOLING CONDS...PERHAPS DROPPING INTO THE UPPER 40S.
NEAR TO SLIGHTLY ABOVE SEASONABLE TEMPS AND MORE HUMID CONDITIONS
LIKELY FOR NEXT WEEK AS SURFACE HIGH PRESSURE SETTLES SOUTH OF THE
REGION AND A SERIES OF WEAK FRONTS AFFECT THE AREA. PREDICTABILITY
OF SHORTWAVES AND ASSOCIATED FRONTS IS LOW THIS FAR OUT...BUT
POTENTIAL EXISTS FOR A FEW PERIODS OF SHOWERS AND THUNDERSTORMS FROM
MONDAY AFTERNOON ONWARDS. MOST ACTIVITY WILL LIKELY BE DIURNAL AND
SCATTERED ACROSS THE INTERIOR...BUT PATTERN COULD SUPPORT AN
ORGANIZED CONVECTIVE COMPLEX AT ANY TIME DURING THE MID TO LATE WEEK
PERIOD.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A COLD FRONT WILL MOVE ACROSS THE AREA FROM NW TO SE BETWEEN 03Z
AND 09Z TONIGHT.
LINE OF SHRA/TSTMS APPROACHING KMSV AT 00Z. MODEL GUIDANCE HAS
BEEN INDICATING THAT THIS ACTIVITY WILL WEAKEN AS IT CONTINUES ON
A SE TRAJECTORY...ALTHOUGH KSWF MAY BE IMPACTED BEFORE THAT
OCCURS. THIS IS THE ONLY TERMINAL THAT HAS ANY MENTION OF ACTIVITY
DUE TO THE EXPECTED WEAKENING FORECAST TREND. WILL NEED TO MONITOR
THIS CLOSELY THE NEXT FEW HOURS WITH AMENDMENTS AS NEEDED.
OTHERWISE...PATCHY FOG MAY DEVELOP AT KHPN/KBDR/KISP BEFORE THE
DRIER AIR BEHIND THE FRONT WORKS IN. IFR FOG/STRATUS IS POSSIBLE
AT KGON.
VFR PREVAILS BEHIND THE FRONT...WITH WIND DIRECTIONS BECOMING
RIGHT OF 310 MAGNETIC AT NYC AIRPORTS OVERNIGHT (BEFORE THE
MORNING PUSH). EXPECT GUSTS UP TO 20 KT MAINLY AT NYC TERMINALS
BETWEEN 12Z AND 18Z. MAY NEED TO ADD THEM TO REMAINING TERMINALS
FOR A FEW HOURS AFTER SUNRISE...BUT THEY MAY JUST BE OCNL.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: GUSTS MAY CEASE EARLIER THAN FORECAST ON
FRI. MODERATE TO HIGH CONFIDENCE WIND DIRECTIONS WILL REMAIN RIGHT
OF 310 MAGNETIC.
KJFK FCSTER COMMENTS: GUSTS MAY CEASE EARLIER THAN FORECAST ON
FRI. MODERATE TO HIGH CONFIDENCE WIND DIRECTIONS WILL REMAIN RIGHT
OF 310 MAGNETIC.
KLGA FCSTER COMMENTS: GUSTS MAY CEASE EARLIER THAN FORECAST ON
FRI. MODERATE TO HIGH CONFIDENCE WIND DIRECTIONS WILL REMAIN RIGHT
OF 310 MAGNETIC.
KTEB FCSTER COMMENTS: GUSTS UP TO 20 KT POSSIBLE FROM 13Z TO 18Z FRI.
KHPN FCSTER COMMENTS: GUSTS UP TO 20 KT POSSIBLE FROM 13Z TO 18Z FRI.
KISP FCSTER COMMENTS: GUSTS UP TO 20 KT POSSIBLE FROM 13Z TO 18Z FRI.
OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
.FRI NIGHT-MON...VFR.
.TUE...SUB VFR POSSIBLE IN SHRA/TSRA WITH COLD FRONT.
&&
.MARINE...
TSTM THREAT HAS WANED FOR NOW...BUT WATERS INVOF NYC MAY SEE
ADDITIONAL ACTIVITY AHEAD OF AN APPROACHING COLD FRONT THIS
EVENING. OTHERWISE...POST-FRONTAL FLOW LATE TONIGHT INTO FRI COULD
GUST TO 20 KT AT TIMES ESPECIALLY NEAR SHORE...BUT SCA CONDS NOT
EXPECTED...WITH OCEAN SEAS NO HIGHER THAN 3 FT. QUIET CONDITIONS
SHOULD LAST INTO EARLY NEXT WEEK.
&&
.HYDROLOGY...
SCT SHOWERS AND THUNDERSTORMS MAINLY NORTH/WEST OF NYC THIS
EVENING COULD STILL PRODUCE LOCALIZED HEAVY RAIN AND MINOR
FLOODING.
HEAVY RAIN POTENTIAL MID TO LATE NEXT WEEK WILL BE TIED TO TSTM
ACTIVITY...WHICH HAS LOW PREDICTABILITY IN TIMING AND LOCATION AT
THIS TIME.
&&
.EQUIPMENT...
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW
YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN
TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS
BEING FORMULATED.
DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING
SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
706 PM EDT THU AUG 22 2013
.SYNOPSIS...
WARM AND MUGGY CONDITIONS CONTINUE TONIGHT AHEAD OF AN APPROACHING
COLD FRONT...ALONG WITH THE RISK OF AN ISOLATED SHOWER/THUNDERSTORM.
THE FRONT WILL MOVE OFFSHORE FRIDAY PROVIDING DRY...COOLER AND LESS
HUMID CONDITIONS INTO THIS WEEKEND. DRY WEATHER LINGERS INTO MONDAY
BUT AN UNSETTLED WEATHER PATTERN MAY SET UP FOR MUCH OF NEXT WEEK AS
THUNDERSTORM COMPLEXES MOVE ACROSS THE GREAT LAKES AND POSSIBLY INTO
NEW ENGLAND. TEMPERATURES NEXT WEEK WILL BE NEAR NORMAL BUT BECOMING
INCREASING HUMID BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
7 PM UPDATE...
NOT MUCH CHANGE FROM PREVIOUS FORECAST AS LATEST
OBSERVATIONS/RADAR AND SATELLITE IMAGERY SUPPORT CURRENT FORECAST.
HUMID CONDITIONS COMBINED WITH BOUNDARY LAYER BEGINNING TO COOL
WITH SUNSET HAS LEAD TO LOW CLOUDS AND FOG FORMING ALONG THE CT
COAST INTO COASTAL RI AND MVY/ACK. THIS WILL BECOME MORE
WIDESPREAD LATER TONIGHT AND FOG MAY BECOME LOCALLY DENSE. COLD
FRONT ENTERS WESTERN NEW ENGLAND AROUND 06Z...BOS/PVD CORRIDOR 09Z
AND THEN CAPE COD AND NANTUCKET AROUND 12Z. THEREFORE SHOULD SEE
IMPROVING CONDITIONS FOR THE FRI EARLY MORNING COMMUTE.
CONVECTION UPSTREAM ACROSS NY STATE AND PA NOT VERY STRONG AS
DAYTIME HEATING BEGINS TO WANE. HOWEVER BEST INSTABILITY CURRENTLY
OVER SOUTHERN NEW ENGLAND WITH ML CAPES OF 1500-2500J/KG. HOWEVER
MID LEVEL DRY AIR OVER THE AREA IS LIMITING CONVECTION ACROSS THE
REGION. MOST OF THE LATEST GUIDANCE INCLUDING THE HRRR CONTINUES
THIS THEME WITH LITTLE CONVECTION TONIGHT. HOWEVER CAN/T RULE OUT
AN ISOLATED SHOWER/TSTM WITH THE FRONTAL PASSAGE.
PREVIOUS FORECAST CAPTURES THIS WELL SO LITTLE CHANGE EXPECTED
WITH THIS UPDATE.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
FRIDAY...
COLD FRONT WILL BE ACROSS SOUTHEAST MASS BY THE MORNING HOURS AND
STALL JUST SOUTH OF THE AREA. AS WELL THE UPPER LEVEL TROUGH WILL
CONTINUE TO AMPLIFY WITH THE AXIS OF THE TROUGH MOVING OVER
SOUTHERN NEW ENGLAND. EXPECT ANY ACTIVITY TO DISSIPATE BY THE
MORNING HOURS TOMORROW WITH A CHANCE OF LINGERING SHOWERS ACROSS
SE MASS BY MID- MORNING. EXPECT CLOUDS TO BE AROUND FOR MOST OF
THE DAY EVEN THOUGH MODELS ARE INDICATING A GOOD AMOUNT OF DRY
AIR. WITH THE TROUGH AXIS MOVING THROUGH EXPECT DIURNAL CU TO BE
ABUNDANT. CONCERNED ABOUT THE EAST COAST BEHIND THE FRONTAL
PASSAGE. AS WIND SHIFT TO A MORE NORTHERLY DIRECTION...BELIEVE A
MORE NORTHEAST WIND DIRECTION WILL BE APPARENT ALONG THE COAST.
THIS WILL ALLOW FOR MARINE STRATUS TO MOVE INLAND AND PERHAPS KEEP
TEMPERATURES A LOT COOLER THAN FORECASTED. HAVE A LOW CONFIDENCE
IF THIS WILL OCCUR BUT WANT TO MENTION THE POSSIBILITY FOR NOW.
CONTINUED TO MENTION AN ISOLATED SHOWER FOR TOMORROW AFTERNOON
BEHIND THE FRONT AS STEEPENING LAPSE RATES FROM DIURNAL HEATING AND
SOME LINGERING MOISTURE WILL ALLOW FOR A SPOT SHOWER. BEST LOCATIONS
WILL BE ACROSS THE EASTERN HALF OF THE AREA...CLOSER TO THE FRONT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* DRY WEATHER THIS WEEKEND WITH MILD DAYS AND COOL NIGHTS
* TEMPS SEASONABLY WARM NEXT WEEK BUT BECOMING MORE HUMID
* ACTIVE WEATHER PATTERN POSSIBLE NEXT WEEK
OVERVIEW...
GUIDANCE IN GOOD AGREEMENT ON OVERALL PATTERN DURING THIS FORECAST
PERIOD WHICH FEATURES A STRONG RIDGE ALOFT /591 DAM/ OVER THE
PLAINS/MS VALLEY WITH A MEAN TROUGH OVER THE MARITIMES AND NORTHWEST
ATLANTIC. THERE IS VERY GOOD AGREEMENT/CONTINUITY WITH THESE LARGE
SCALE FEATURES. HOWEVER AS EXPECTED LOTS OF UNCERTAINTY ON THE
AMPLITUDE AND TIMING OF INDIVIDUAL SHORT WAVES AROUND THE PERIPHERY
OF THE RIDGE ACROSS THE GREAT LAKES AND THEN INTO THE NORTHEAST.
THIS IMPACTS THE TIMING OF POTENTIAL PRECIP EVENTS FOR OUR REGION.
IN ADDITION THIS SYNOPTIC CONFIGURATION WILL KEEP THE EXCESSIVE HEAT
SOUTH AND WEST OF NEW ENGLAND BUT ALSO PLACES OUR REGION IN A LOW
RISK AREA FOR TSTM COMPLEXES /RING OF FIRE/ CIRCULATING AROUND THE
NORTHERN PERIPHERY OF THE RIDGE AND INTO THE NORTHEAST. HOWEVER
GIVEN GOOD MODEL AGREEMENT ON THE HIGHER THETA-E AIRMASS TO REMAIN
SOUTH AND WEST OF NEW ENGLAND...ANY CONVECTION /ESPECIALLY STRONG
CONVECTION/ WOULD LIKELY TRACK IN A SIMILAR FASHION YIELDING A LOWER
RISK ACROSS NEW ENGLAND. HOWEVER CAN/T COMPLETELY RULE OUT
WEAKENING MCS CLIPPING WESTERN AND SOUTHERN NEW ENGLAND. GIVEN THIS
UNCERTAINTY WE FOLLOWED THE HIGHER POPS /20-30%/ FROM HPC AS GFS MOS
APPEARED TOO LOW.
DAILY DETAILS...
FRI NIGHT AND SAT/SUN...
FALL-LIKE AIRMASS FRI NIGHT AND SAT MORNING WITH A GUSTY NE WIND
/ESPECIALLY CAPE COD AND ISLANDS/ AND TEMPS IN THE 50S...A FEW U40S
WELL INLAND! VERY COMFORTABLE HUMIDITY WITH DEW PTS IN THE 40S SAT
AND 50S SUN.
FOR SAT...NEARBY MID LEVEL TROF AND COLD POOL ACTING ON LOW LEVEL
MOISTURE WILL LIKELY BRING AT LEAST SCT-BKN CU BUT THE MOISTURE IS
SHALLOW SO DRY WEATHER EXPECTED. LESS CU ON SUNDAY AS MID LEVEL
TEMPS WARM. TEMPS WILL BE A FEW DEGREES BELOW NORMAL SAT...MOSTLY IN
THE MID/UPPER 70S THEN WARMING INTO UPPER 70S AND LOWER 80S SUNDAY
IN RESPONSE TO INCREASING MID LEVEL TEMPS.
NEXT WEEK...
LOTS OF UNCERTAINTY ON TIMING AND AMPLITUDE OF SHORT WAVES EJECTING
SOUTHEAST FROM THE GREAT LAKES. 12Z ECMWF AND 12Z GFS EXHIBITING
FAIRLY LARGE SPREAD HERE AND ENSEMBLES STRUGGLING WITH RESOLVING
THIS SMALL SCALE FEATURES. THUS THERE IS A LOW RISK OF SHOWERS/TSTMS
FROM LATE MON INTO AT LEAST THU. DEFINITELY NOT A WASH OUT BUT SOME
SCATTERED SHOWERS/TSTMS FROM TIME TO TIME. TEMPS NEAR SEASONABLE BUT
WILL BECOME MORE HUMID WITH TIME. RISK OF STRONG TO SEVERE TSTMS IS
VERY LOW AS HIGHER THETA-E AIRMASS/BETTER INSTABILITY SHOULD BE
SHUNTED TO OUR SOUTHWEST ACROSS PA AND NJ. BUT AT THIS TIME RANGE IT
BEARS WATCHING.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...MODERATE CONFIDENCE.
7 PM UPDATE...
MAINLY DRY WITH JUST AN ISOLATED SHOWER/TSTM TONIGHT. BIGGER
CONCERN WILL BE AREAL EXTENT OF LOW CLOUDS FOG ALONG THE SOUTH
COAST. EXPECT THIS AREA OF IFR TO EXPAND ACROSS RI AND SOUTHEAST
MA TONIGHT. HOWEVER FRONTAL PASSAGE WILL IMPROVE CONDITIONS AROUND
06Z WESTERN NEW ENGLAND/09Z BOS-PVD AND AROUND 12Z CAPE
COD/NANTUCKET.
FRIDAY...SHOWER ACTIVITY WILL WANE BY MORNING AS A COLD FRONT
PUSHES THROUGH THE REGION. WINDS WILL SWITCH TO A MORE NORTHERLY
DIRECTION. DIURNAL CU WILL DEVELOP WITH POSSIBLE MVFR/IFR STRATUS
DECK ACROSS THE EAST COAST AS WINDS TAKE A MORE EASTERLY
DIRECTION. A FEW SHOWERS ARE ALSO POSSIBLE IN THE AFTERNOON.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. SOUTHERLY WINDS SWITCH
TO A MORE NORTHERLY/NORTHEAST DIRECTION BY FRIDAY. POSSIBLE
STRATUS DECK ON FRIDAY DROPPING CONDITIONS...LOW CONFIDENCE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHRA POSSIBLE THIS
AFTERNOON AND INTO THE OVERNIGHT HOURS.
OUTLOOK...FRI NIGHT THROUGH TUESDAY...
HIGH CONFIDENCE. MOSTLY VFR WITH SCT-BKN DIURNAL CU. LATE
NIGHT/EARLY MORNING PATCHY MVFR/IFR FOG POSSIBLE IN THE CT VALLEY.
WIDELY SCT SHOWERS/TSTMS POSSIBLE WESTERN AREAS LATE MON INTO TUE.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...MODERATE CONFIDENCE.
WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. GUSTY
WINDS WILL DIMINISH BY EVENING HOWEVER WAVES WILL SLOWLY INCREASE
AS A COLD FRONT APPROACHES THE REGION. FRONTAL PASSAGE WILL OCCUR
OVERNIGHT AND INTO FRIDAY MORNING SWITCHING THE WINDS TO A MORE
NORTHERLY DIRECTION. SEAS WILL INCREASE AS GUSTY WINDS NEAR 20KTS
WILL DEVELOP BEHIND THE FRONT ON FRIDAY.
OUTLOOK...FRI NIGHT THROUGH TUESDAY...
HIGH CONFIDENCE.
GUSTY NE WINDS AROUND 20 KT FRI NIGHT INTO EARLY SAT. DIMINISHING
WIND LATER SAT INTO SUN AS HIGH PRES CREST OVER SOUTHERN NEW
ENGLAND. SW WIND 20-25 KT POSSIBLE LATER MON INTO TUE ON BACK SIDE
OF DEPARTING HIGH. DRY WEATHER PREVAILS WITH A LOW RISK OF
SCATTERED SHOWERS/TSTMS LATE MON INTO TUE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...NOCERA/DUNTEN
SHORT TERM...DUNTEN
LONG TERM...NOCERA
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
859 PM EDT THU AUG 22 2013
.SYNOPSIS...
HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE ATLANTIC
WILL WEAKEN AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL
MOVE THROUGH THE AREA FRIDAY NIGHT AND EARLY SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONVERGING BOUNDARIES HAS HELPED SUPPORT NUMEROUS SHOWERS AND
THUNDERSTORMS IN THE CENTRAL PART OF THE FORECAST AREA. THESE
SHOULD MOVE EASTWARD SLOWLY. THE HRRR INDICATES SHOWERS AND
THUNDERSTORMS IN THE EAST PART UNTIL AROUND 05Z. SLOW MOVEMENT
COULD RESULT IN LOCALIZED FLOODING IN POOR-DRAINAGE AREAS.
MODERATE INSTABILITY HAS SUPPORTED SEVERE WIND GUSTS AND HAIL WITH
A FEW OF THE THUNDERSTORMS. THE CHANCE OF SEVERE THUNDERSTORMS
SHOULD DIMINISH TONIGHT WITH THE LOSS OF HEATING.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
THE MAIN UPPER-LEVEL TROUGH WILL CONTINUE TO PUSH EASTWARD FRIDAY
AS AN UPPER RIDGE BUILDS OVER THE CENTRAL CONUS. A COLD FRONT WILL
MOVE SOUTHEASTWARD TOWARD THE AREA FROM THE GREAT LAKES
REGION...WITH THE MODELS INDICATING INCREASED STORM ACTIVITY
ACROSS THE NORTHERN COUNTIES LATE IN THE AFTERNOON. PRECIPITABLE
WATER VALUES WILL REMAIN ELEVATED AT AROUND 1.8 INCHES.
TEMPERATURES WILL WARM AHEAD OF THE FRONT INTO THE LOWER 90S.
SHOWERS AND THUNDERSTORMS WILL SLOWLY DROP SOUTHWARD FRIDAY NIGHT
WITH SCATTERED ACTIVITY POSSIBLE THROUGHOUT THE NIGHT. ON
SATURDAY...THE MAIN BACKDOOR COLD FRONT WILL DROP DOWN INTO THE
AREA. THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO THE SOUTHERN HALF
OF THE FORECAST AREA AS DRIER AIR TRIES TO FILTER IN ACROSS THE
NORTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID TO
UPPER 80S. OVERNIGHT LOWS FRIDAY NIGHT AROUND 70.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
DRY WEATHER ON TAP SUNDAY AS THE COLD FRONT MOVES SOUTH OF THE
AREA. THE MAIN SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD IN
BEHIND THE FRONT INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. THIS WILL RESULT IN LOW
PRECIPITATION CHANCES AND HIGH TEMPERATURES IN THE MID TO UPPER
80S. OVERNIGHT LOWS WILL BE IN THE 60S.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
THE THUNDERSTORM CHANCE SHOULD DIMINISH OVERNIGHT BECAUSE OF
DIURNAL COOLING. THERE WILL BE AREAS OF EARLY MORNING IFR OR MVFR
FOG...MAINLY AT THE RIVER VALLEY TERMINALS OF AGS AND OGB.
SUFFICIENT MOISTURE AND STRONG HEATING WILL SUPPORT THUNDERSTORMS
AGAIN FRIDAY AFTERNOON. EXPECT SCATTERED COVERAGE WITH THE CHANCE
TOO LOW TO INCLUDE IN THE TERMINAL FORECASTS AT THIS TIME.
EXTENDED AVIATION OUTLOOK...A COLD FRONT WILL MOVE SOUTHWARD
ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY...BRINGING A CHANCE OF
THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
756 PM EDT THU AUG 22 2013
.SYNOPSIS...
HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE ATLANTIC
WILL WEAKEN AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL
MOVE THROUGH THE AREA FRIDAY NIGHT AND EARLY SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONVERGING BOUNDARIES HAS HELPED SUPPORT NUMEROUS SHOWERS AND
THUNDERSTORMS IN THE CENTRAL PART OF THE FORECAST AREA. THESE
SHOULD MOVE EASTWARD SLOWLY. THE HRRR INDICATES SHOWERS AND
THUNDERSTORMS IN THE EAST PART UNTIL AROUND 05Z. SLOW MOVEMENT
COULD RESULT IN LOCALIZED FLOODING IN POOR-DRAINAGE AREAS.
MODERATE INSTABILITY HAS SUPPORTED SEVERE WIND GUSTS AND HAIL WITH
A FEW OF THE THUNDERSTORMS. THE CHANCE OF SEVERE THUNDERSTORMS
SHOULD DIMINISH TONIGHT WITH THE LOSS OF HEATING.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
THE MAIN UPPER-LEVEL TROUGH WILL CONTINUE TO PUSH EASTWARD FRIDAY
AS AN UPPER RIDGE BUILDS OVER THE CENTRAL CONUS. A COLD FRONT WILL
MOVE SOUTHEASTWARD TOWARD THE AREA FROM THE GREAT LAKES
REGION...WITH THE MODELS INDICATING INCREASED STORM ACTIVITY
ACROSS THE NORTHERN COUNTIES LATE IN THE AFTERNOON. PRECIPITABLE
WATER VALUES WILL REMAIN ELEVATED AT AROUND 1.8 INCHES.
TEMPERATURES WILL WARM AHEAD OF THE FRONT INTO THE LOWER 90S.
SHOWERS AND THUNDERSTORMS WILL SLOWLY DROP SOUTHWARD FRIDAY NIGHT
WITH SCATTERED ACTIVITY POSSIBLE THROUGHOUT THE NIGHT. ON
SATURDAY...THE MAIN BACKDOOR COLD FRONT WILL DROP DOWN INTO THE
AREA. THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO THE SOUTHERN HALF
OF THE FORECAST AREA AS DRIER AIR TRIES TO FILTER IN ACROSS THE
NORTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID TO
UPPER 80S. OVERNIGHT LOWS FRIDAY NIGHT AROUND 70.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
DRY WEATHER ON TAP SUNDAY AS THE COLD FRONT MOVES SOUTH OF THE
AREA. THE MAIN SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD IN
BEHIND THE FRONT INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. THIS WILL RESULT IN LOW
PRECIPITATION CHANCES AND HIGH TEMPERATURES IN THE MID TO UPPER
80S. OVERNIGHT LOWS WILL BE IN THE 60S.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
CONVERGING BOUNDARIES HAS RESULTED IN NUMEROUS THUNDERSTORMS WHICH
WILL BE IN THE OGB AREA THIS EVENING. THE THUNDERSTORM CHANCE
SHOULD DIMINISH OVERNIGHT BECAUSE OF DIURNAL COOLING. THERE WILL
BE AREAS OF EARLY MORNING IFR OR MVFR FOG...MAINLY AT THE RIVER
VALLEY TERMINALS OF AGS AND OGB. SUFFICIENT MOISTURE AND STRONG
HEATING WILL SUPPORT THUNDERSTORMS AGAIN FRIDAY AFTERNOON. EXPECT
SCATTERED COVERAGE WITH THE CHANCE TOO LOW TO INCLUDE IN THE
TERMINAL FORECASTS AT THIS TIME.
EXTENDED AVIATION OUTLOOK...A COLD FRONT WILL MOVE SOUTHWARD
ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY...BRINGING A CHANCE OF
THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
712 PM EDT THU AUG 22 2013
.SYNOPSIS...
HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE ATLANTIC
WILL WEAKEN AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL
MOVE THROUGH THE AREA FRIDAY NIGHT AND EARLY SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONVERGING BOUNDARIES HAS HELPED SUPPORT NUMEROUS SHOWERS AND
THUNDERSTORMS IN THE CENTRAL PART OF THE FORECAST AREA. THESE
SHOULD MOVE EASTWARD SLOWLY. THE HRRR INDICATES SHOWERS AND
THUNDERSTORMS IN THE EAST PART UNTIL AROUND 05Z. SLOW MOVEMENT
COULD RESULT IN LOCALIZED FLOODING IN POOR-DRAINAGE AREAS.
MODERATE INSTABILITY HAS SUPPORTED SEVERE WIND GUSTS AND HAIL WITH
A FEW OF THE THUNDERSTORMS. THE CHANCE OF SEVERE THUNDERSTORMS
SHOULD DIMINISH TONIGHT WITH THE LOSS OF HEATING.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
THE MAIN UPPER-LEVEL TROUGH WILL CONTINUE TO PUSH EASTWARD FRIDAY
AS AN UPPER RIDGE BUILDS OVER THE CENTRAL CONUS. A COLD FRONT WILL
MOVE SOUTHEASTWARD TOWARD THE AREA FROM THE GREAT LAKES
REGION...WITH THE MODELS INDICATING INCREASED STORM ACTIVITY
ACROSS THE NORTHERN COUNTIES LATE IN THE AFTERNOON. PRECIPITABLE
WATER VALUES WILL REMAIN ELEVATED AT AROUND 1.8 INCHES.
TEMPERATURES WILL WARM AHEAD OF THE FRONT INTO THE LOWER 90S.
SHOWERS AND THUNDERSTORMS WILL SLOWLY DROP SOUTHWARD FRIDAY NIGHT
WITH SCATTERED ACTIVITY POSSIBLE THROUGHOUT THE NIGHT. ON
SATURDAY...THE MAIN BACKDOOR COLD FRONT WILL DROP DOWN INTO THE
AREA. THE BEST CHANCE FOR PRECIPITATION WILL SHIFT TO THE SOUTHERN HALF
OF THE FORECAST AREA AS DRIER AIR TRIES TO FILTER IN ACROSS THE
NORTH. MAXIMUM TEMPERATURES SLIGHTLY BELOW NORMAL IN THE MID TO
UPPER 80S. OVERNIGHT LOWS FRIDAY NIGHT AROUND 70.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
DRY WEATHER ON TAP SUNDAY AS THE COLD FRONT MOVES SOUTH OF THE
AREA. THE MAIN SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD IN
BEHIND THE FRONT INTO THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE WILL
BUILD ACROSS THE CENTRAL CONUS AND NUDGE EASTWARD AS THE UPPER
TROUGH REMAINS WELL OFF THE EAST COAST. THIS WILL RESULT IN LOW
PRECIPITATION CHANCES AND HIGH TEMPERATURES IN THE MID TO UPPER
80S. OVERNIGHT LOWS WILL BE IN THE 60S.
&&
.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
CONVERGING BOUNDARIES HAS RESULTED IN NUMEROUS THUNDERSTORMS NEAR
CAE AND CUB. EASTWARD MOVEMENT ALSO SUPPORTS THUNDERSTORMS AROUND
ORB THIS EVENING. THE THUNDERSTORM CHANCE SHOULD DIMINISH
OVERNIGHT BECAUSE OF DIURNAL COOLING. THERE WILL BE AREAS OF EARLY
MORNING IFR OR MVFR FOG...MAINLY AT THE RIVER VALLEY TERMINALS OF
AGS AND OGB. SUFFICIENT MOISTURE AND STRONG HEATING WILL SUPPORT
THUNDERSTORMS AGAIN FRIDAY AFTERNOON. EXPECT SCATTERED COVERAGE
WITH THE CHANCE TOO LOW TO INCLUDE IN THE TERMINAL FORECASTS AT
THIS TIME.
EXTENDED AVIATION OUTLOOK...A COLD FRONT WILL MOVE SOUTHWARD
ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY...BRINGING A CHANCE OF
THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1136 AM EDT WED AUG 21 2013
.UPDATE...
LOCALIZED HEAVY RAIN AND THUNDERSTORM DEVELOPMENT HAS PERSISTED
ACROSS PORTIONS OF NORTHEAST GEORGIA THIS MORNING DUE TO PLUME OF
ENHANCED MOISTURE /AND NEAR 2.0 INCH PWATS/ ALONG A WEAK
DISTURBANCE. HAVE MAINLY ADJUSTED MORNING POPS TO BE A BIT HIGHER
IN THE NE AND HAVE BUMPED DAYTIME MAX TEMPS DOWN A BIT PER RECENT
GUIDANCE BLEND WITH LINGERING LOW LEVEL CLOUDS IN THE NORTH AND
WEST CENTRAL PORTIONS OF THE CWA. UNCERTAINTY EXISTS IN FLASH
FLOODING THREAT THROUGH REST OF DAY AS MAJORITY OF GUIDANCE IS
SUGGESTING HIGHER QPF AMOUNTS AND MORE WIDESPREAD PRECIP COVERAGE
IN THE NORTHWESTERN HALF OF THE CWA THIS AFTERNOON...WHILE A
LINGERING BOUNDARY LOOKS TO BISECT THE AREA AND ANY LATE DAY SEA
BREEZE INFLUENCE MAY SHIFT PRECIP COVERAGE ACROSS THE WATCH AREA
IN THE SOUTHEAST. ALL CONSIDERED...WILL CONTINUE WITH CURRENT
FLASH FLOOD WATCH IN THE SOUTHEAST AND MAY EXTEND ACROSS NORTHWEST
IF AFTERNOON DEVELOPMENT RAMPS UP. REST OF FORECAST LOOKS TO BE ON
TRACK AND PREVIOUS DISCUSSION FOLLOWS...
BAKER
&&
.PREV DISCUSSION... /ISSUED 750 AM EDT WED AUG 21 2013/
.SHORT TERM /TODAY THROUGH THURSDAY/...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
LATEST SURFACE MAP CONTINUES TO SHOW A WEAK FRONTAL BOUNDARY STALLED
ACROSS CENTRAL GA... SOMEWHERE JUST SOUTH OF A CSG TO MCN TO AGS
LINE... WHILE A COOL WEDGE OF HIGH PRESSURE WAS STILL NOTED OVER THE
MID ATLANTIC STATES. THE SURFACE RIDGE IS PROGGED BY SHORT RANGE
MODELS TO SETTLE OFF THE CAROLINA`S COASTS THIS AFTERNOON. THIS WILL
PRODUCE A DEEPER SOUTHERLY WIND FLOW... WHICH WILL CONTINUE TO HELP
SPREAD ATLANTIC AND GULF MOISTURE NORTHWARD. SATELLITE WATER VAPOR
SHOWS A DEEP TROPICAL MOISTURE PLUME ANCHORED OVER THE STATE WHILE
AN UPPER LOW PRESSURE SYSTEM SPINS OVER THE OHIO VALLEY. EXPECT THE
WEAK FRONT TO MEANDER ACROSS CENTRAL GA AGAIN TODAY... WITH A MOIST
/2.0+ PW`S/ AND MODERATELY UNSTABLE AIRMASS /2000-2500 CAPE/ ALONG
AND SOUTH OF THE FRONT. THIS COUPLED WITH A SERIES OF DISTURBANCES
SWINGING AROUND THE BASE OF THE UPPER LOW WILL PRODUCE ANOTHER ROUND
OF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THIS AFTERNOON
AND EVENING. ALTHOUGH SCATTERED STORMS COULD OCCUR JUST ABOUT
ANYWHERE TODAY... EXPECT THE GREATER POTENTIAL FOR REOCCURRING
STORMS WITH HEAVY RAINFALL TO BE ACROSS CENTRAL GA WHERE THE DEEPER
MOISTURE AND GREATER INSTABILITIES WILL BE POOLED. WITH THE
POTENTIAL FOR ANOTHER 1 TO 3 INCHES OF RAINFALL OVER AN ALREADY
SATURATED GROUND... DECIDED TO PLAY IT SAFE AND POST ANOTHER FLASH
FLOOD WATCH FOR PARTS OF CENTRAL GA AGAIN TODAY... GENERALLY ALONG
AND SOUTH OF A COLUMBUS TO MACON TO WARRENTON LINE... FROM NOON
THROUGH THIS EVENING. THESE RAINFALL AMOUNTS WILL CAUSE RAPID RISES
ON AREA CREEKS... STREAMS AND RIVERS... AS WELL AS PONDING OF WATER
ACROSS LOW LYING... FLOOD PRONE AREAS IN AND AROUND THE WATCH AREA.
THE FLOOD THREAT WILL GREATLY DIMINISH BY MIDNIGHT AS CONVECTION
DIMINISHES WITH LOSS OF DAYTIME HEATING. ALTHOUGH NO WIDESPREAD
SEVERE STORMS ARE EXPECTED... SOME MID LEVEL DRY AIR SPREADING IN
FROM THE EAST COULD ENHANCE STORM DOWNDRAFT WIND GUSTS. THIS COUPLED
WITH SATURATED SOIL COULD EASILY DOWN TREES. THE OVERALL WET PATTERN
MAY BE LESSENED ON THURSDAY WITH INCREASING UPPER RIDGING FROM THE
WEST AND SURFACE HIGH PRESSURE NOSING IN FROM THE EAST. HOWEVER...
STILL EXPECT ISOLATED TO LOW SCATTERED COVERAGE OF STORMS THURSDAY
AFTERNOON AS DAYTIME TEMPS CLIMB BACK TOWARD MORE SEASONAL NORMALS
OF UPPER 80S TO LOWER 90S.
39
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
THE WET PATTERN CONTINUES INTO THE EXTENDED...BUT THERE IS AN END
IN SIGHT. DEEPER MOISTURE THAT IS OVER THE AREA IN THE SHORT TERM
FINALLY MOVES NORTH AND EAST OF THE REGION BY 00Z FRI. THERE IS
STILL A DECENT AMOUNT OF MOISTURE ACROSS THE AREA THROUGH THE
WEEKEND BUT NO WHERE NEAR AS MUCH AS WE HAVE SEEN OVER THE PAST
WEEK. PRECIPITABLE WATERS FINALLY GET BELOW 1.5 INCHES BY 12Z FRI
AND STAY THERE THROUGH THE REST OF THE EXTENDED. THE MAIN FEATURE
THAT HELPS TO DRY THINGS OUT A BIT IS THE LARGE HIGH PRESSURE
RIDGE THAT BUILDS SOUTH OUT OF THE GREAT LAKE AND NEW ENGLAND
STATES. THIS RIDGE PUSHES DON INTO N GA BEGINNING SAT NIGHT AND
BRINGS WITH IT A MUCH DRIER AIRMASS. THE RIDGE CENTER MOVES OF THE
MID ATLANTIC COAST MON MORNING BUT ITS MAIN AXIS STAYS ACROSS THE
CAROLINAS...GA...AND AL THROUGH TUE/WED. WILL KEEP A SLIGHT CHANCE
OF SHRA/TSRA IN THE FORECAST THROUGH DAY 7 AS THERE IS STILL DECENT
MOISTURE AND SOME INSTABILITY AS THIS RIDGE MOVES IN. WITH JUST
ENOUGH DAY TIME HEATING WE COULD STILL SEE SOME AFTERNOON POP UP
THUNDERSTORMS. TH GOOD NEWS IS ANYTHING THAT DEVELOPS WONT HAVE
THE DEEPER TROPICAL MOISTURE TO WORK WITH SO FLOODING WILL BECOME
LESS OF A FACTOR THROUGH THE END OF THE FORECAST PERIOD.
01
&&
.HYDROLOGY...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
AN UPPER TROUGH TO THE NW WILL INTERACT WITH A STALLED FRONTAL
BOUNDARY ACROSS CENTRAL GA AND DEEP TROPICAL MOISTURE ENTRENCHED
ACROSS THE STATE TO PRODUCE ANOTHER ROUND OF SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS ACROSS MUCH OF CENTRAL GA THIS AFTERNOON
AND EVENING. SLOW MOVING... REDEVELOPING STORMS COULD PRODUCE
ANOTHER 1 TO 3 INCHES OF RAINFALL ACROSS PARTS OF CENTRAL GA
TODAY... THIS OVER AN ALREADY VERY SATURATED GROUND FROM NUMEROUS
STORMS THE PAST SEVERAL DAYS. AS A RESULT... HAVE POSTED ANOTHER
FLASH FLOOD WATCH FOR AREAS GENERALLY ALONG AND SOUTH OF A COLUMBUS
TO MACON TO WARRENTON LINE FROM NOON THROUGH THIS EVENING.
HOWEVER... ITS IMPORTANT TO REMEMBER... LOCALIZED HEAVY RAIN COULD
OCCUR JUST ABOUT ANYWHERE TODAY... AND ALL INTEREST ACROSS NORTH AND
CENTRAL GA AROUND FLOOD PRONE AREAS ARE ENCOURAGED TO MONITOR STORMS
CLOSELY THIS AFTERNOON AND EVENING.
&&
.AVIATION...
12Z UPDATE...
INCREASING INSTABILITIES AND AREA SHOWERS HAVE PREVENTED LIFR/IFR
CIGS FROM DEVELOPING AROUND ATLANTA TAF SITES THIS MORNING. RADAR
SHOWS PATCHES OF -RA/-SHRA DEVELOPING FROM NEAR FFC NEWD ACROSS ATL
AND JUST NORTH OF AHN. THE HRRR MODEL SHOWS THIS AREA BECOMING MORE
ACTIVE THROUGH LATE MORNING-EARLY AFTERNOON WITH A THREAT OF -TSRA
BY 17-18Z AT ATL AND CONTINUING THRU 21-23Z TODAY. HAVE TWEAKED
TAF`S ACCORDINGLY. MODELS INDICATE IFR/MVFR CIGS WILL DEVELOP TOWARD
10-12Z THU... SO WILL SHOW MVFR BY 10Z FOR NOW. EXPECT CURRENT LIGHT
EAST WINDS TO BECOME MORE SE AROUND 7-9KTS TODAY... AND 3-4KTS
TONIGHT.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON MORNING CIGS AND TIMING OF -TSRA THIS
AFTERNOON. HIGH ALL OTHER ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 69 87 70 / 70 40 30 20
ATLANTA 83 71 87 71 / 60 40 30 20
BLAIRSVILLE 79 65 83 64 / 70 40 30 20
CARTERSVILLE 83 68 88 70 / 60 40 30 20
COLUMBUS 87 72 90 72 / 60 40 30 20
GAINESVILLE 81 69 85 69 / 70 40 30 20
MACON 87 71 90 71 / 50 40 30 20
ROME 84 67 89 70 / 60 40 30 20
PEACHTREE CITY 83 68 87 69 / 60 40 30 20
VIDALIA 89 72 90 72 / 50 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES:
BALDWIN...BIBB...BLECKLEY...CHATTAHOOCHEE...CRAWFORD...CRISP...
DODGE...DOOLY...EMANUEL...GLASCOCK...HANCOCK...HOUSTON...
JEFFERSON...JOHNSON...JONES...LAURENS...MACON...MARION...
MONTGOMERY...PEACH...PULASKI...SCHLEY...STEWART...SUMTER...
TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TWIGGS...WARREN...
WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKINSON.
&&
$$
SHORT TERM...39/BAKER
LONG TERM....01
AVIATION...39
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
750 AM EDT WED AUG 21 2013
.SHORT TERM /TODAY THROUGH THURSDAY/...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
LATEST SURFACE MAP CONTINUES TO SHOW A WEAK FRONTAL BOUNDARY STALLED
ACROSS CENTRAL GA... SOMEWHERE JUST SOUTH OF A CSG TO MCN TO AGS
LINE... WHILE A COOL WEDGE OF HIGH PRESSURE WAS STILL NOTED OVER THE
MID ATLANTIC STATES. THE SURFACE RIDGE IS PROGGED BY SHORT RANGE
MODELS TO SETTLE OFF THE CAROLINA`S COASTS THIS AFTERNOON. THIS WILL
PRODUCE A DEEPER SOUTHERLY WIND FLOW... WHICH WILL CONTINUE TO HELP
SPREAD ATLANTIC AND GULF MOISTURE NORTHWARD. SATELLITE WATER VAPOR
SHOWS A DEEP TROPICAL MOISTURE PLUME ANCHORED OVER THE STATE WHILE
AN UPPER LOW PRESSURE SYSTEM SPINS OVER THE OHIO VALLEY. EXPECT THE
WEAK FRONT TO MEANDER ACROSS CENTRAL GA AGAIN TODAY... WITH A MOIST
/2.0+ PW`S/ AND MODERATELY UNSTABLE AIRMASS /2000-2500 CAPE/ ALONG
AND SOUTH OF THE FRONT. THIS COUPLED WITH A SERIES OF DISTURBANCES
SWINGING AROUND THE BASE OF THE UPPER LOW WILL PRODUCE ANOTHER ROUND
OF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THIS AFTERNOON
AND EVENING. ALTHOUGH SCATTERED STORMS COULD OCCUR JUST ABOUT
ANYWHERE TODAY... EXPECT THE GREATER POTENTIAL FOR REOCCURRING
STORMS WITH HEAVY RAINFALL TO BE ACROSS CENTRAL GA WHERE THE DEEPER
MOISTURE AND GREATER INSTABILITIES WILL BE POOLED. WITH THE
POTENTIAL FOR ANOTHER 1 TO 3 INCHES OF RAINFALL OVER AN ALREADY
SATURATED GROUND... DECIDED TO PLAY IT SAFE AND POST ANOTHER FLASH
FLOOD WATCH FOR PARTS OF CENTRAL GA AGAIN TODAY... GENERALLY ALONG
AND SOUTH OF A COLUMBUS TO MACON TO WARRENTON LINE... FROM NOON
THROUGH THIS EVENING. THESE RAINFALL AMOUNTS WILL CAUSE RAPID RISES
ON AREA CREEKS... STREAMS AND RIVERS... AS WELL AS PONDING OF WATER
ACROSS LOW LYING... FLOOD PRONE AREAS IN AND AROUND THE WATCH AREA.
THE FLOOD THREAT WILL GREATLY DIMINISH BY MIDNIGHT AS CONVECTION
DIMINISHES WITH LOSS OF DAYTIME HEATING. ALTHOUGH NO WIDESPREAD
SEVERE STORMS ARE EXPECTED... SOME MID LEVEL DRY AIR SPREADING IN
FROM THE EAST COULD ENHANCE STORM DOWNDRAFT WIND GUSTS. THIS COUPLED
WITH SATURATED SOIL COULD EASILY DOWN TREES. THE OVERALL WET PATTERN
MAY BE LESSENED ON THURSDAY WITH INCREASING UPPER RIDGING FROM THE
WEST AND SURFACE HIGH PRESSURE NOSING IN FROM THE EAST. HOWEVER...
STILL EXPECT ISOLATED TO LOW SCATTERED COVERAGE OF STORMS THURSDAY
AFTERNOON AS DAYTIME TEMPS CLIMB BACK TOWARD MORE SEASONAL NORMALS
OF UPPER 80S TO LOWER 90S.
39
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
THE WET PATTERN CONTINUES INTO THE EXTENDED...BUT THERE IS AN END
IN SIGHT. DEEPER MOISTURE THAT IS OVER THE AREA IN THE SHORT TERM
FINALLY MOVES NORTH AND EAST OF THE REGION BY 00Z FRI. THERE IS
STILL A DECENT AMOUNT OF MOISTURE ACROSS THE AREA THROUGH THE
WEEKEND BUT NO WHERE NEAR AS MUCH AS WE HAVE SEEN OVER THE PAST
WEEK. PRECIPITABLE WATERS FINALLY GET BELOW 1.5 INCHES BY 12Z FRI
AND STAY THERE THROUGH THE REST OF THE EXTENDED. THE MAIN FEATURE
THAT HELPS TO DRY THINGS OUT A BIT IS THE LARGE HIGH PRESSURE
RIDGE THAT BUILDS SOUTH OUT OF THE GREAT LAKE AND NEW ENGLAND
STATES. THIS RIDGE PUSHES DON INTO N GA BEGINNING SAT NIGHT AND
BRINGS WITH IT A MUCH DRIER AIRMASS. THE RIDGE CENTER MOVES OF THE
MID ATLANTIC COAST MON MORNING BUT ITS MAIN AXIS STAYS ACROSS THE
CAROLINAS...GA...AND AL THROUGH TUE/WED. WILL KEEP A SLIGHT CHANCE
OF SHRA/TSRA IN THE FORECAST THROUGH DAY 7 AS THERE IS STILL DECENT
MOISTURE AND SOME INSTABILITY AS THIS RIDGE MOVES IN. WITH JUST
ENOUGH DAY TIME HEATING WE COULD STILL SEE SOME AFTERNOON POP UP
THUNDERSTORMS. TH GOOD NEWS IS ANYTHING THAT DEVELOPS WONT HAVE
THE DEEPER TROPICAL MOISTURE TO WORK WITH SO FLOODING WILL BECOME
LESS OF A FACTOR THROUGH THE END OF THE FORECAST PERIOD.
01
&&
.HYDROLOGY...
/ISSUED AT 443 AM EDT WED AUG 21 2013/
AN UPPER TROUGH TO THE NW WILL INTERACT WITH A STALLED FRONTAL
BOUNDARY ACROSS CENTRAL GA AND DEEP TROPICAL MOISTURE ENTRENCHED
ACROSS THE STATE TO PRODUCE ANOTHER ROUND OF SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS ACROSS MUCH OF CENTRAL GA THIS AFTERNOON
AND EVENING. SLOW MOVING... REDEVELOPING STORMS COULD PRODUCE
ANOTHER 1 TO 3 INCHES OF RAINFALL ACROSS PARTS OF CENTRAL GA
TODAY... THIS OVER AN ALREADY VERY SATURATED GROUND FROM NUMEROUS
STORMS THE PAST SEVERAL DAYS. AS A RESULT... HAVE POSTED ANOTHER
FLASH FLOOD WATCH FOR AREAS GENERALLY ALONG AND SOUTH OF A COLUMBUS
TO MACON TO WARRENTON LINE FROM NOON THROUGH THIS EVENING.
HOWEVER... ITS IMPORTANT TO REMEMBER... LOCALIZED HEAVY RAIN COULD
OCCUR JUST ABOUT ANYWHERE TODAY... AND ALL INTEREST ACROSS NORTH AND
CENTRAL GA AROUND FLOOD PRONE AREAS ARE ENCOURAGED TO MONITOR STORMS
CLOSELY THIS AFTERNOON AND EVENING.
&&
.AVIATION...
12Z UPDATE...
INCREASING INSTABILITIES AND AREA SHOWERS HAVE PREVENTED LIFR/IFR
CIGS FROM DEVELOPING AROUND ATLANTA TAF SITES THIS MORNING. RADAR
SHOWS PATCHES OF -RA/-SHRA DEVELOPING FROM NEAR FFC NEWD ACROSS ATL
AND JUST NORTH OF AHN. THE HRRR MODEL SHOWS THIS AREA BECOMING MORE
ACTIVE THROUGH LATE MORNING-EARLY AFTERNOON WITH A THREAT OF -TSRA
BY 17-18Z AT ATL AND CONTINUING THRU 21-23Z TODAY. HAVE TWEAKED
TAF`S ACCORDINGLY. MODELS INDICATE IFR/MVFR CIGS WILL DEVELOP TOWARD
10-12Z THU... SO WILL SHOW MVFR BY 10Z FOR NOW. EXPECT CURRENT LIGHT
EAST WINDS TO BECOME MORE SE AROUND 7-9KTS TODAY... AND 3-4KTS
TONIGHT.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON MORNING CIGS AND TIMING OF -TSRA THIS
AFTERNOON. HIGH ALL OTHER ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 83 69 87 70 / 50 40 30 20
ATLANTA 84 71 87 71 / 60 40 30 20
BLAIRSVILLE 79 65 83 64 / 60 40 30 20
CARTERSVILLE 85 68 88 70 / 60 40 30 20
COLUMBUS 88 72 90 72 / 50 40 30 20
GAINESVILLE 82 69 85 69 / 60 40 30 20
MACON 87 71 90 71 / 50 40 30 20
ROME 86 67 89 70 / 60 40 30 20
PEACHTREE CITY 85 68 87 69 / 50 40 30 20
VIDALIA 90 72 90 72 / 50 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR
THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CHATTAHOOCHEE...
CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...
HANCOCK...HOUSTON...JEFFERSON...JOHNSON...JONES...LAURENS...
MACON...MARION...MONTGOMERY...PEACH...PULASKI...SCHLEY...
STEWART...SUMTER...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...
TWIGGS...WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...
WILKINSON.
&&
$$
SHORT TERM...39
LONG TERM....01
AVIATION...39
AREA FORECAST DISCUSSION
NWS POCATELLO ID
216 PM MDT WED AUG 21 2013
.DISCUSSION...SHORTWAVE MOVING THROUGH SOUTHEAST IDAHO THIS
AFTERNOON PER SAT IMAGERY WITH STRONGER SHORTWAVE MOVING NORTH
THROUGH NEVADA. LINE OF CONVECTION FROM EARLY THIS MORNING HAS
WEAKENED CONSIDERABLY AS CLOUD BAND HAS SHIFTED NORTH THROUGH
FORECAST AREA. CLEARING BEHIND THE LINE HAS ALLOWED STRONGER
CONVECTION TO FORM IN VERY MOIST AIR MASS. MODELS CONTINUE TO
STRUGGLE EVEN IN SHORT TERM REGARDING INSTABILITY AND PLACEMENT OF
QPF. BEST CHANCES FOR CONVECTION THROUGH THE EVENING APPEAR TO
REMAIN IN SOUTHEAST CORNER WHERE CURRENT STORMS ARE STRONGEST THUS
KEPT POPS HIGHEST THERE. HRRR DEVELOPS SECONDARY WEAKER LINE THROUGH
CENTRAL MOUNTAINS THIS EVENING INTO AREA ALONG DIVIDE LATE. SECOND
PUSH OF CONVECTION SLIDES NORTHEAST INTO EASTERN IDAHO AFTER
MIDNIGHT THOUGH THIS SOLUTION FAVORED ONLY BY GFS DESPITE PLENTY
OF MOISTURE AND CONTINUED WEAK INSTABILITY OVERNIGHT. WILL KEEP
LOW POPS OVER HIGHER ELEVATIONS THROUGH THE NIGHT. UPPER LOW OFF
CALIFORNIA COAST STARTS TO SHIFT NORTHEAST INTO THE CALIFORNIA
COAST BY THURSDAY AFTERNOON. THIS SHOULD BRING ROUND OF CONVECTION
LASTING LATE THURSDAY THROUGH FRIDAY AFTERNOON. TIMING BETWEEN GFS
AND NAM LOOKS SIMILAR WITH BOTH MODELS BRINGING DRY PUSH INTO
WESTERN IDAHO FRIDAY AFTERNOON. MID LEVEL DRY SLOT SLIDES SOMEWHAT
EAST FOR SATURDAY BUT SHOULD BE ENOUGH LOW LEVEL MOISTURE TO KEEP
THE THREAT FOR THUNDERSTORMS GOING PARTICULARLY WITH ENOUGH
CLEARING FOR AFTERNOON. FOR SUNDAY THROUGH WEDNESDAY...GFS
CONTINUES TO ADVERTISE STRONG WET SOUTHERLY FLOW INTO EASTERN
IDAHO. ECMWF SLIGHTLY FURTHER EAST WITH MOISTURE TRAJECTORY. LEFT
AT LEAST WEAK POPS HIGHER ELEVATIONS EACH DAY. DMH
&&
.AVIATION...EXPECT VICINITY THUNDERSTORMS FOR ALL TAF SITES THIS
AFTERNOON INTO EARLY EVENING TODAY AND TOMORROW WITH AN UPPER LEVEL
LOW BRINGING MOISTURE INTO THE AREA. EXPECT GUSTY OUTFLOW WINDS IN
AND AROUND THUNDERSTORMS. KSUN WILL LIKELY BE IMPACTED AGAIN LATE
TONIGHT INTO EARLY MORNING FOR SMOKE. HOWEVER..VISIBILITIES LOOK TO
BE SLIGHTLY GETTING BETTER EACH MORNING. KSUN WILL LIKELY NOT GO
BELOW MVFR TONIGHT INTO TOMORROW MORNING. WYATT
&&
.FIRE WEATHER...MONSOONAL MOISTURE IS IN THE AREA BRINGING ISOLATED
TO SCATTERED THUNDERSTORMS CURRENTLY OVER OUR SOUTHERN AND SOUTHEAST
AREAS. LOOK FOR ISOLATED TO SCATTERED THUNDERSTORMS LATER TODAY FOR
THE REST OF THE AREA PARTICULARLY THE SOUTHERN CENTRAL MOUNTAINS AND
SOUTHWARD. LOOK FOR GUSTY OUTFLOW WINDS AROUND 40 MPH IN AND AROUND
THUNDERSTORMS. ADDITIONALLY...LOCALIZED HEAVY RAIN IS POSSIBLE
CREATING THE POSSIBILITY OF FLASH FLOODING PARTICULARLY OVER BURN
SCAR AREAS. LOOK FOR A REPEAT OF ISOLATED TO SCATTERED THUNDERSTORMS
WITH GUSTY WINDS AND LOCALIZED HEAVY RAIN THURSDAY PARTICULARLY
ACROSS OUR NORTHERN AREAS. EXPECT WINDS TO START TO INCREASE OVER
THE AREA THURSDAY AND PARTICULARLY FRIDAY AS THE UPPER LEVEL LOW
MOVES OVER EASTERN OREGON AND WESTERN IDAHO BY FRIDAY. MODELS
CONTINUE TO SHOW SOUTHEAST IDAHO IN AN ACTIVE PATTERN WITH THE
POSSIBILITY OF AFTERNOON THUNDERSTORMS AIDED BY MONSOON MOISTURE
OVER PORTIONS OF OUR AREA SATURDAY THROUGH THE END OF THE PERIOD.
WYATT
&&
.AIR STAGNATION...AIR QUALITY REMAINS A CONCERN OVER PORTIONS OF
CENTRAL MOUNTAINS DUE TO WILDFIRE SMOKE. WILL CONTINUE AIR QUALITY
ADVISORY AS REQUESTED BY IDAHO DEQ. DMH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ410.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ413-427.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT
IDZ422-475-476.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ425.
&&
$$
AREA FORECAST DISCUSSION
NWS POCATELLO ID
910 AM MDT WED AUG 21 2013
.UPDATE...QUITE A BIT OF UNCERTAINTY REMAINS WITH TODAYS FORECAST.
SHORTWAVE OVER NORTHEAST NEVADA SLOWLY SHEARING NORTHEAST THROUGH
EASTERN IDAHO TODAY WITH LONG BAND OF MOSTLY WEAK CONVECTION
SPREAD WEST TO EAST ACROSS THE FORECAST AREA AND AN OCCASSIONAL
LIGHTNING STRIKE IN SOUTHEAST CORNER. VERY MOIST AIR MASS IN PLACE
WITH UPSTREAM SOUNDING PWAT AROUND ONE INCH AND NAM PWAT WELL OVER
AN INCH BY AFTERNOON. WV SAT IMAGERY SHOWS THAT MOISTURE HAS
PUSHED THROUGH NEARLY THE ENTIRE FORECAST AREA THOUGH NAM MODEL
PWAT CONSIDERABLY LESS AGGRESSIVE OVER PORTIONS OF THE CENTRAL
MOUNTAINS...WHICH HAS BEEN THE THEME FROM THE MODEL THE PAST
SEVERAL DAYS. NAM-BASED LOCAL WRF SPREADS AFTERNOON INSTABILITY
INTO THE CENTRAL MOUNTAINS WITH POCKET OF LIGHT QPF FROM ROUGHLY
KSUN NORTHEAST...BUT CANT QUITE PUSH THE INSTABILITY FURTHER
NORTH. LATEST HRRR SEEMS TO FOLLOW WITH THIS SOLUTION AS WELL WITH
QPF IN NEARLY THE SAME LOCATION. CLOUD COVER FROM CURRENT
CONVECTION MAY BE THE LIMITING FACTOR BUT NORTH HALF OF FORECAST
AREA CLEAR OTHER THAN SMOKE SO SHOULD BE NO HINDERANCE TO VERTICAL
DEVELOPMENT. ALREADY HAD MULTIPLE LIGHTNING STARTS EVEN OUTSIDE
OF HEAVY RAINFALL CORES WITH CONVECTION IN SOUTHERN HIGHLANDS
YESTERDAY SO HAVE A DIFFICULT TIME JUSTIFYING ANY CHANGE IN
THUNDERSTORM COVERAGE OR WITH CURRENT RED FLAG HEADLINES. WILL
MAINTAIN A WATCH AND SEE STANCE...AND STILL OPEN TO FLASH FLOOD
WATCH LATER TODAY FOR SOUTHERN AND PORTIONS OF EASTERN HIGHLANDS
DEPENDING ON DEVELOPMENT. DMH
&&
.PREV DISCUSSION... /ISSUED 213 AM MDT WED AUG 21 2013/
DISCUSSION...A CLOSED LOW OFF THE COAST OF CENTRAL CALIFORNIA IS
PUMPING MONSOONAL MOISTURE INTO THE REGION. NAM/GFS IS SHOWING
BETTER CHANCES FOR STORMS TODAY OVER THE SOUTHEAST HIGHLANDS
WHERE AN UPPER LEVEL VORTICITY MAXIMUM WILL TRACK. SOME STORMS
WILL BE POSSIBLE ELSEWHERE BECAUSE OF THE HIGH MOISTURE CONTENT
OVER THE AREA. CENTRAL MOUNTAINS WILL SEE ISOLATED TO SCATTERED
STORMS TODAY...TOPOGRAPHY MAY AID DEVELOPMENT THERE. HIGH
PRECIPITABLE WATER VALUES OF 0.75 TO 1.15 SUGGEST AN ISOLATED
FLASH FLOOD THREAT ESPECIALLY OVER THE EASTERN HIGHLANDS. ON
THURSDAY THE CLOSED LOW LIFTS INTO OREGON. THIS WILL SHIFT THE
BEST CHANCE FOR STORMS INTO THE CENTRAL MOUNTAINS ALONG WITH THE
FLASH FLOOD THREAT. PRECIPITABLE WATER VALUES DO NOT CHANGE MUCH.
GIVEN THE RECENT FIRE SCARS IN THE CENTRAL MOUNTAINS...A FLASH
FLOOD THREAT INCLUDING MUDSLIDES IS MORE POSSIBLE. LATER SHIFTS
MAY NEED TO REEVALUATE FOR A POSSIBLE FLASH FLOOD WATCH OVER THE
CENTRAL MOUNTAINS FOR THURSDAY. ON FRIDAY THE LOW WEAKENS AND
LIFTS INTO MONTANA. ENOUGH MOISTURE WILL REMAIN OVER THE AREA FOR
FRIDAY AND THROUGH THE WEEKEND TO PRODUCE ISOLATED THUNDERSTORMS.
MOIST ATMOSPHERE PERSISTS INTO EARLY NEXT WEEK WITH THE GFS
SUGGESTING ANOTHER STRONG PUSH OF MONSOONAL MOISTURE.
VALLE
AVIATION...SMOKE WILL LIKELY IMPACT KSUN ONCE AGAIN THIS MORNING.
MOISTURE IS WORKING ITS WAY NORTH TODAY BRINGING SHOWERS AND
THUNDERSTORMS TO THE ENTIRE AREA. HAVE VCTS PRESENT FOR ALL SITES
THIS AFTERNOON WITH THE POSSIBILITY OF THUNDERSTORMS ON SITE. EXPECT
MORE WIDESPREAD THUNDERSTORM ACTIVITY ON THURSDAY. EP/DV
FIRE WEATHER...MONSOON MOISTURE IS MOVING IN TO THE AREA FROM THE
SOUTH BRINGING ISOLATED TO SCATTERED THUNDERSTORMS
TODAY...ESPECIALLY IN THE SOUTHERN AND EASTERN HIGHLANDS. MODELS
SHOWING PWAT VALUES OVER ONE INCH IN MANY AREAS WHICH LENDS TO THE
THREAT OF HEAVY RAINFALL CAUSING FLASH FLOODING...ESPECIALLY OVER
BURN SCARS. GUSTY WINDS UNDER AND NEAR THUNDERSTORMS IS POSSIBLE AS
WELL. EXCEPTING A REPEAT ON THURSDAY WITH MORE WIDESPREAD AND
SCATTERED THUNDERSTORMS...WITH THE THREAT OF GUSTY WINDS AND
FLASH FLOODING. A RED FLAG WARNING IS IN EFFECT FOR BOTH WEDNESDAY
AND THURSDAY FOR ALL SE IDAHO FIRE WEATHER ZONES EXCEPT 411 FOR
GUSTY OUTFLOW WINDS AND THUNDERSTORMS. ON FRIDAY... AN INCREASE IN
WINDS IS EXPECTED AS UPPER LOW MOVES ACROSS THE PANHANDLE OF IDAHO.
EP/DV
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ410.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ413-427.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT
IDZ422-475-476.
RED FLAG WARNING UNTIL MIDNIGHT MDT THURSDAY NIGHT IDZ425.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
240 PM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* CHANCE OF SHRA/TSRA EARLY THURSDAY MORNING AND WIND SHIFT
ASSOCIATED WITH A COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING FOR A SHORT PERIOD BEHIND
COLD FRONT.
KREIN
//DISCUSSION...UPDATED 18Z...
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNDER SWLY FLOW
AHEAD OF AN APPROACHING COLD FRONT. THE PRIMARY CONCERN FOR THE
PERIOD CONTINUES TO BE THE CHANCES FOR SHOWERS AND THUNDERSTORMS
EARLY TOMORROW MORNING. THE MAIN CHANGE TO THE GOING FORECAST IS
TO INTRODUCE A VCSH GROUP AS MUCH OF THE SHORT RANGE MODEL
GUIDANCE IS INDICATING A CHANCE FOR PRE-FRONTAL PCPN TO MOVE INTO
NRN IL BY ARND 06Z. THERE ARE STILL SOME CONCERNS AS TO THE
COVERAGE OF THE PRE-FRONTAL PCPN...HENCE THE VCSH RATHER THAN A
PREVAILING GROUP WHICH WOULD IMPLY GREATER CONFIDENCE IN MORE
EXTENSIVE COVERAGE. STILL EXPECTING THE FRONTAL PASSAGE AT RFD BY
ARND 12Z AND THE CHICAGO AREA SHORTLY THEREAFTER AS THE SYSTEM
SHOULD BE FAIRLY PROGRESSIVE. WINDS WILL VEER THROUGH NWLY TO
EVENTUALLY NNELY FOLLOWING THE FROPA. THERE IS STILL A CONCERN FOR
A BRIEF PERIOD OF MVFR CIGS OR VIS FOLLOWING THE FROPA AS SOME OF
THE GUIDANCE IS INDICATED A NEARLY SATURATED LAYER BLW
3KFT...THOUGH WOULD ANTICIPATE THAT RFD/DPA WOULD CLIMATOLOGICALLY
HAVE A GREATER CHANCE FOR REDUCED VISBY THAN ORD/MDW. WITHIN A FEW
HOURS OF THE FROPA...DRY AIR THROUGH A DEEP LAYER SHOULD FILTER IN
BEHIND THE FRONT...AND VFR CONDITIONS WITH NNELY WINDS UNDER 10KT
SHOULD PREVAIL FOR THE REMAINDER OF THE DAY TOMORROW.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
INVOF THE TERMINALS EARLY THURSDAY MORNING.
* MEDIUM CONFIDENCE IN PRE-FRONTAL SHRA.
* MEDIUM TO HIGH CONFIDENCE IN TIMING FRONTAL WIND SHIFT AND WIND
TRENDS FOLLOWING THE FROPA..
* LOW CONFIDENCE IN MVFR CIGS/VIS BEHIND THE FRONT EARLY THURSDAY.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
202 PM CDT
A COLD FRONT EXTENDED FROM NORTHERN QUEBEC SW ACROSS E LAKE
SUPERIOR...N WI AND S MN AT MID AFTERNOON. THIS COLD FRONT WILL
CONTINUE TO MOVE SE...REACHING N LAKE MI THIS EVENING AND S LAKE
MI THU MORNING....SHIFTING WINDS TO OUT OF THE NW AND N. AS THE
COLD FRONT MOVES OFF TO THE SE DURING THU HIGH PRESSURE WILL MOVE
ESE TO ONTARIO AND THE UPPER MIDWEST. THE HIGH THEN GRADUALLY
SHIFTS SE AND WILL BE OVER QUEBEC...THE GREAT LAKES AND THE OH
VALLEY BY SAT MORNING AND THE MID ATLANTIC SEABOARD AND S
APPALACHIANS BY MON MORNING.
HEIGHT OUTPUT BY LOCALLY RUN WAVE MODEL WOULD APPEAR TO BE LOW
GIVEN MODERATELY STRONG N WINDS THOUGH LOCAL OUTPUT IN LINE WITH
GLERL PRODUCED WAVE HEIGHTS. HOWEVER...WAVE GROWTH WILL BE
LIMITED AS THE AIR MASS BEHIND THE COLD FRONT IS STILL WARM
ENOUGH FOR A TEMPERATURE INVERSION AT THE LAKE SURFACE WHICH WILL
LIMIT MOMENTUM TRANSFER ALL THE WAY DOWN TO THE AIR/WATER
INTERFACE.
TRS
&&
.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:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
203 PM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* CHANCE OF SHRA/TSRA EARLY THURSDAY MORNING AND WIND SHIFT
ASSOCIATED WITH A COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING FOR A SHORT PERIOD BEHIND
COLD FRONT.
KREIN
//DISCUSSION...UPDATED 18Z...
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNDER SWLY FLOW
AHEAD OF AN APPROACHING COLD FRONT. THE PRIMARY CONCERN FOR THE
PERIOD CONTINUES TO BE THE CHANCES FOR SHOWERS AND THUNDERSTORMS
EARLY TOMORROW MORNING. THE MAIN CHANGE TO THE GOING FORECAST IS
TO INTRODUCE A VCSH GROUP AS MUCH OF THE SHORT RANGE MODEL
GUIDANCE IS INDICATING A CHANCE FOR PRE-FRONTAL PCPN TO MOVE INTO
NRN IL BY ARND 06Z. THERE ARE STILL SOME CONCERNS AS TO THE
COVERAGE OF THE PRE-FRONTAL PCPN...HENCE THE VCSH RATHER THAN A
PREVAILING GROUP WHICH WOULD IMPLY GREATER CONFIDENCE IN MORE
EXTENSIVE COVERAGE. STILL EXPECTING THE FRONTAL PASSAGE AT RFD BY
ARND 12Z AND THE CHICAGO AREA SHORTLY THEREAFTER AS THE SYSTEM
SHOULD BE FAIRLY PROGRESSIVE. WINDS WILL VEER THROUGH NWLY TO
EVENTUALLY NNELY FOLLOWING THE FROPA. THERE IS STILL A CONCERN FOR
A BRIEF PERIOD OF MVFR CIGS OR VIS FOLLOWING THE FROPA AS SOME OF
THE GUIDANCE IS INDICATED A NEARLY SATURATED LAYER BLW
3KFT...THOUGH WOULD ANTICIPATE THAT RFD/DPA WOULD CLIMATOLOGICALLY
HAVE A GREATER CHANCE FOR REDUCED VISBY THAN ORD/MDW. WITHIN A FEW
HOURS OF THE FROPA...DRY AIR THROUGH A DEEP LAYER SHOULD FILTER IN
BEHIND THE FRONT...AND VFR CONDITIONS WITH NNELY WINDS UNDER 10KT
SHOULD PREVAIL FOR THE REMAINDER OF THE DAY TOMORROW.
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
INVOF THE TERMINALS EARLY THURSDAY MORNING.
* MEDIUM CONFIDENCE IN PRE-FRONTAL SHRA.
* MEDIUM TO HIGH CONFIDENCE IN TIMING FRONTAL WIND SHIFT AND WIND
TRENDS FOLLOWING THE FROPA..
* LOW CONFIDENCE IN MVFR CIGS/VIS BEHIND THE FRONT EARLY THURSDAY.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
202 PM CDT
A COLD FRONT EXTENDED FROM NORTHERN QUEBEC SW ACROSS E LAKE
SUPERIOR...N WI AND S MN AT MID AFTERNOON. THIS COLD FRONT WILL
CONTINUE TO MOVE SE...REACHING N LAKE MI THIS EVENING AND S LAKE
MI THU MORNING....SHIFTING WINDS TO OUT OF THE NW AND N. AS THE
COLD FRONT MOVES OFF TO THE SE DURING THU HIGH PRESSURE WILL MOVE
ESE TO ONTARIO AND THE UPPER MIDWEST. THE HIGH THEN GRADUALLY
SHIFTS SE AND WILL BE OVER QUEBEC...THE GREAT LAKES AND THE OH
VALLEY BY SAT MORNING AND THE MID ATLANTIC SEABOARD AND S
APPALACHIANS BY MON MORNING.
HEIGHT OUTPUT BY LOCALLY RUN WAVE MODEL WOULD APPEAR TO BE LOW
GIVEN MODERATELY STRONG N WINDS THOUGH LOCAL OUTPUT IN LINE WITH
GLERL PRODUCED WAVE HEIGHTS. HOWEVER...WAVE GROWTH WILL BE
LIMITED AS THE AIR MASS BEHIND THE COLD FRONT IS STILL WARM
ENOUGH FOR A TEMPERATURE INVERSION AT THE LAKE SURFACE WHICH WILL
LIMIT MOMENTUM TRANSFER ALL THE WAY DOWN TO THE AIR/WATER
INTERFACE.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1235 PM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* CHANCE OF SHRA/TSRA EARLY THURSDAY MORNING AND WIND SHIFT
ASSOCIATED WITH A COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING FOR A SHORT PERIOD BEHIND
COLD FRONT.
KREIN
//DISCUSSION...UPDATED 18Z...
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNDER SWLY FLOW
AHEAD OF AN APPROACHING COLD FRONT. THE PRIMARY CONCERN FOR THE
PERIOD CONTINUES TO BE THE CHANCES FOR SHOWERS AND THUNDERSTORMS
EARLY TOMORROW MORNING. THE MAIN CHANGE TO THE GOING FORECAST IS
TO INTRODUCE A VCSH GROUP AS MUCH OF THE SHORT RANGE MODEL
GUIDANCE IS INDICATING A CHANCE FOR PRE-FRONTAL PCPN TO MOVE INTO
NRN IL BY ARND 06Z. THERE ARE STILL SOME CONCERNS AS TO THE
COVERAGE OF THE PRE-FRONTAL PCPN...HENCE THE VCSH RATHER THAN A
PREVAILING GROUP WHICH WOULD IMPLY GREATER CONFIDENCE IN MORE
EXTENSIVE COVERAGE. STILL EXPECTING THE FRONTAL PASSAGE AT RFD BY
ARND 12Z AND THE CHICAGO AREA SHORTLY THEREAFTER AS THE SYSTEM
SHOULD BE FAIRLY PROGRESSIVE. WINDS WILL VEER THROUGH NWLY TO
EVENTUALLY NNELY FOLLOWING THE FROPA. THERE IS STILL A CONCERN FOR
A BRIEF PERIOD OF MVFR CIGS OR VIS FOLLOWING THE FROPA AS SOME OF
THE GUIDANCE IS INDICATED A NEARLY SATURATED LAYER BLW
3KFT...THOUGH WOULD ANTICIPATE THAT RFD/DPA WOULD CLIMATOLOGICALLY
HAVE A GREATER CHANCE FOR REDUCED VISBY THAN ORD/MDW. WITHIN A FEW
HOURS OF THE FROPA...DRY AIR THROUGH A DEEP LAYER SHOULD FILTER IN
BEHIND THE FRONT...AND VFR CONDITIONS WITH NNELY WINDS UNDER 10KT
SHOULD PREVAIL FOR THE REMAINDER OF THE DAY TOMORROW.
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
INVOF THE TERMINALS EARLY THURSDAY MORNING.
* MEDIUM CONFIDENCE IN PRE-FRONTAL SHRA.
* MEDIUM TO HIGH CONFIDENCE IN TIMING FRONTAL WIND SHIFT AND WIND
TRENDS FOLLOWING THE FROPA..
* LOW CONFIDENCE IN MVFR CIGS/VIS BEHIND THE FRONT EARLY THURSDAY.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
237 AM CDT
SOUTHWEST WINDS TO AROUND 25 KT WILL CONTINUE THROUGH THE DAY TODAY
ACROSS NORTHERN LAKE MICHIGAN AHEAD OF AN APPROACHING COLD FRONT
WHICH CURRENTLY STRETCHES FROM SOUTHERN MANITOBA INTO THE DAKOTAS.
WINDS WILL BE A LITTLE WEAKER ON THE SOUTH END OF THE LAKE WHERE THE
GRADIENT ISNT QUITE AS TIGHT. STABLE CONDITIONS ARE EXPECTED OVER
THE LAKE WHICH WILL HELP KEEP HIGHER END GUSTS IN CHECK...THOUGH
WOULDNT BE SURPRISED TO SEE SHIPS REPORT OCCASIONAL GUSTS TO 30
KTS. WINDS TURN NORTHERLY LATE TONIGHT AND EARLY THURSDAY...WITH
GUSTS AROUND 25 KT MAINTAINING ACROSS THE SOUTH HALF OF THE LAKE.
WINDS BEGIN TO TAPER THURSDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE WESTERN LAKES REGION. WINDS WILL TURN SOUTHERLY AGAIN
SATURDAY AS ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE CANADIAN
PRAIRIES...AND FRESHEN UP ESPECIALLY ON SUNDAY WHEN WE MAY ONCE
AGAIN BE LOOKING AT 20 TO 25 KT WINDS.
BMD
&&
.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
1100 AM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* CHANCE OF SHRA/TSRA EARLY THURSDAY MORNING AND WIND SHIFT
ASSOCIATED WITH A COLD FRONT PASSAGE.
* CHANCE OF MVFR CIGS THURSDAY MORNING BEHIND COLD FRONT.
KREIN
//DISCUSSION...UPDATED 12Z...
OVERALL EXPECT A FAIRLY QUIET DAY LOCALLY DOMINATED BY SOUTHWEST
WINDS AND VFR CONDITIONS. GUSTS INTO THE MID TO HIGH TEENS CAN BE
EXPECTED LATE THIS MORNING AND INTO THIS EVENING AHEAD OF AN
APPROACHING COLD FRONT. BY 18Z THIS AFTERNOON...EXPECT THE FRONT TO
STRETCH FROM ROUGHLY DLH SOUTHWEST TO FSD WITH MODERATE TO STRONG
INSTABILITY DEVELOPING AHEAD OF THE FRONT ACROSS PORTIONS OF
SOUTHERN MINNESOTA AND CENTRAL WISCONSIN...WHERE CONVECTIVE
INITIATION IS EXPECTED TO TAKE PLACE BY EARLY TO MID AFTERNOON. SOME
CONVECTIVE ALLOWING MODELS ARE SHOWING THUNDERSTORMS DEVELOPING
FARTHER SOUTHEAST...OVER NORTH CENTRAL ILLINOIS AND SOUTHERN
WISCONSIN...BUT EXPECT THIS AREA TO BE MOSTLY CAPPED WITH VERY
ISOLATED ACTIVITY IF ANY.
THE FRONT IS NOT EXPECTED TO PASS INTO ILLINOIS UNTIL AROUND 09Z
TONIGHT..AND INTO THE TERMINALS A COUPLE HOURS THEREAFTER. BY THIS
TIME...EXPECT THUNDERSTORMS PUSHING WELL AHEAD OF THE FRONT AND
INTENSITY TO BE ON A DECLINING TREND GIVEN THE UNFAVORABLE DIURNAL
TIMING AND THE LACK OF ANY SIGNIFICANT UPPER LEVEL SUPPORT. COVERAGE
SHOULD BECOME MORE WIDELY SCATTERED AS THE OVERNIGHT HOURS PROGRESS
LEADING TO UNCERTAINTY IN IMPACTS AT THE TERMINALS. IN FACT SOME
CAMS SUGGEST THAT ACTIVITY MAY DIMINISH COMPLETELY OVER NORTHERN
ILLINOIS...THEN REFORM SOUTH OF THE TERMINALS TOMORROW.
ONCE THE FRONT PASSES THROUGH...THERE MAY BE A BRIEF WINDOW IN THE
MORNING WHERE LOWER MFVR CIGS DEVELOP BEHIND THE FRONT AS THE COOLER
AIR PUSHES INTO THE UPPER 60 DEWPOINTS...BUT SHOULD BE ON THE ORDER
OF AN HOUR OR TWO BEFORE DRIER AIR STARTS TO TRICKLE SOUTH AND
DAYTIME MIXING COMMENCES. WINDS ARE EXPECTED TO BECOME NORTHEASTERLY
AS HIGH PRESSURE BUILDS ACROSS MINNESOTA AND WISCONSIN.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
MOVING INTO THE AREA LATE TONIGHT/EARLY THURSDAY.
* MEDIUM CONFIDENCE IN TIMING FRONTAL WIND SHIFT EARLY THURSDAY.
* LOW CONFIDENCE IN MVFR CIGS BEHIND THE FRONT EARLY THURSDAY.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
237 AM CDT
SOUTHWEST WINDS TO AROUND 25 KT WILL CONTINUE THROUGH THE DAY TODAY
ACROSS NORTHERN LAKE MICHIGAN AHEAD OF AN APPROACHING COLD FRONT
WHICH CURRENTLY STRETCHES FROM SOUTHERN MANITOBA INTO THE DAKOTAS.
WINDS WILL BE A LITTLE WEAKER ON THE SOUTH END OF THE LAKE WHERE THE
GRADIENT ISNT QUITE AS TIGHT. STABLE CONDITIONS ARE EXPECTED OVER
THE LAKE WHICH WILL HELP KEEP HIGHER END GUSTS IN CHECK...THOUGH
WOULDNT BE SURPRISED TO SEE SHIPS REPORT OCCASIONAL GUSTS TO 30
KTS. WINDS TURN NORTHERLY LATE TONIGHT AND EARLY THURSDAY...WITH
GUSTS AROUND 25 KT MAINTAINING ACROSS THE SOUTH HALF OF THE LAKE.
WINDS BEGIN TO TAPER THURSDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE WESTERN LAKES REGION. WINDS WILL TURN SOUTHERLY AGAIN
SATURDAY AS ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE CANADIAN
PRAIRIES...AND FRESHEN UP ESPECIALLY ON SUNDAY WHEN WE MAY ONCE
AGAIN BE LOOKING AT 20 TO 25 KT WINDS.
BMD
&&
.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
902 AM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* CHANCE OF SHRA/TSRA EARLY THURSDAY MORNING AND WIND SHIFT
ASSOCIATED WITH A COLD FRONT PASSAGE.
* POTENTIAL FOR MVFR CIGS THURSDAY MORNING BEHIND COLD FRONT.
KREIN
//DISCUSSION...UPDATED 12Z...
OVERALL EXPECT A FAIRLY QUIET DAY LOCALLY DOMINATED BY SOUTHWEST
WINDS AND VFR CONDITIONS. GUSTS INTO THE MID TO HIGH TEENS CAN BE
EXPECTED LATE THIS MORNING AND INTO THIS EVENING AHEAD OF AN
APPROACHING COLD FRONT. BY 18Z THIS AFTERNOON...EXPECT THE FRONT TO
STRETCH FROM ROUGHLY DLH SOUTHWEST TO FSD WITH MODERATE TO STRONG
INSTABILITY DEVELOPING AHEAD OF THE FRONT ACROSS PORTIONS OF
SOUTHERN MINNESOTA AND CENTRAL WISCONSIN...WHERE CONVECTIVE
INITIATION IS EXPECTED TO TAKE PLACE BY EARLY TO MID AFTERNOON. SOME
CONVECTIVE ALLOWING MODELS ARE SHOWING THUNDERSTORMS DEVELOPING
FARTHER SOUTHEAST...OVER NORTH CENTRAL ILLINOIS AND SOUTHERN
WISCONSIN...BUT EXPECT THIS AREA TO BE MOSTLY CAPPED WITH VERY
ISOLATED ACTIVITY IF ANY.
THE FRONT IS NOT EXPECTED TO PASS INTO ILLINOIS UNTIL AROUND 09Z
TONIGHT..AND INTO THE TERMINALS A COUPLE HOURS THEREAFTER. BY THIS
TIME...EXPECT THUNDERSTORMS PUSHING WELL AHEAD OF THE FRONT AND
INTENSITY TO BE ON A DECLINING TREND GIVEN THE UNFAVORABLE DIURNAL
TIMING AND THE LACK OF ANY SIGNIFICANT UPPER LEVEL SUPPORT. COVERAGE
SHOULD BECOME MORE WIDELY SCATTERED AS THE OVERNIGHT HOURS PROGRESS
LEADING TO UNCERTAINTY IN IMPACTS AT THE TERMINALS. IN FACT SOME
CAMS SUGGEST THAT ACTIVITY MAY DIMINISH COMPLETELY OVER NORTHERN
ILLINOIS...THEN REFORM SOUTH OF THE TERMINALS TOMORROW.
ONCE THE FRONT PASSES THROUGH...THERE MAY BE A BRIEF WINDOW IN THE
MORNING WHERE LOWER MFVR CIGS DEVELOP BEHIND THE FRONT AS THE COOLER
AIR PUSHES INTO THE UPPER 60 DEWPOINTS...BUT SHOULD BE ON THE ORDER
OF AN HOUR OR TWO BEFORE DRIER AIR STARTS TO TRICKLE SOUTH AND
DAYTIME MIXING COMMENCES. WINDS ARE EXPECTED TO BECOME NORTHEASTERLY
AS HIGH PRESSURE BUILDS ACROSS MINNESOTA AND WISCONSIN.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
MOVING INTO THE AREA LATE TONIGHT/EARLY THURSDAY.
* MEDIUM CONFIDENCE IN TIMING FRONTAL WIND SHIFT EARLY THURSDAY.
* LOW CONFIDENCE IN MVFR CIGS BEHIND THE FRONT EARLY THURSDAY.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
237 AM CDT
SOUTHWEST WINDS TO AROUND 25 KT WILL CONTINUE THROUGH THE DAY TODAY
ACROSS NORTHERN LAKE MICHIGAN AHEAD OF AN APPROACHING COLD FRONT
WHICH CURRENTLY STRETCHES FROM SOUTHERN MANITOBA INTO THE DAKOTAS.
WINDS WILL BE A LITTLE WEAKER ON THE SOUTH END OF THE LAKE WHERE THE
GRADIENT ISNT QUITE AS TIGHT. STABLE CONDITIONS ARE EXPECTED OVER
THE LAKE WHICH WILL HELP KEEP HIGHER END GUSTS IN CHECK...THOUGH
WOULDNT BE SURPRISED TO SEE SHIPS REPORT OCCASIONAL GUSTS TO 30
KTS. WINDS TURN NORTHERLY LATE TONIGHT AND EARLY THURSDAY...WITH
GUSTS AROUND 25 KT MAINTAINING ACROSS THE SOUTH HALF OF THE LAKE.
WINDS BEGIN TO TAPER THURSDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE WESTERN LAKES REGION. WINDS WILL TURN SOUTHERLY AGAIN
SATURDAY AS ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE CANADIAN
PRAIRIES...AND FRESHEN UP ESPECIALLY ON SUNDAY WHEN WE MAY ONCE
AGAIN BE LOOKING AT 20 TO 25 KT WINDS.
BMD
&&
.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
641 AM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
//PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* SHRA/TSRA THURSDAY MORNING AND WIND SHIFT ASSOCIATED WITH A COLD
FRONT PASSAGE.
* POTENTIAL FOR MVFR CIGS THURSDAY MORNING BEHIND COLD FRONT.
BMD
//DISCUSSION...UPDATED 12Z...
OVERALL EXPECT A FAIRLY QUIET DAY LOCALLY DOMINATED BY SOUTHWEST
WINDS AND VFR CONDITIONS. GUSTS INTO THE MID TO HIGH TEENS CAN BE
EXPECTED LATE THIS MORNING AND INTO THIS EVENING AHEAD OF AN
APPROACHING COLD FRONT. BY 18Z THIS AFTERNOON...EXPECT THE FRONT TO
STRETCH FROM ROUGHLY DLH SOUTHWEST TO FSD WITH MODERATE TO STRONG
INSTABILITY DEVELOPING AHEAD OF THE FRONT ACROSS PORTIONS OF
SOUTHERN MINNESOTA AND CENTRAL WISCONSIN...WHERE CONVECTIVE
INITIATION IS EXPECTED TO TAKE PLACE BY EARLY TO MID AFTERNOON. SOME
CONVECTIVE ALLOWING MODELS ARE SHOWING THUNDERSTORMS DEVELOPING
FARTHER SOUTHEAST...OVER NORTH CENTRAL ILLINOIS AND SOUTHERN
WISCONSIN...BUT EXPECT THIS AREA TO BE MOSTLY CAPPED WITH VERY
ISOLATED ACTIVITY IF ANY.
THE FRONT IS NOT EXPECTED TO PASS INTO ILLINOIS UNTIL AROUND 09Z
TONIGHT..AND INTO THE TERMINALS A COUPLE HOURS THEREAFTER. BY THIS
TIME...EXPECT THUNDERSTORMS PUSHING WELL AHEAD OF THE FRONT AND
INTENSITY TO BE ON A DECLINING TREND GIVEN THE UNFAVORABLE DIURNAL
TIMING AND THE LACK OF ANY SIGNIFICANT UPPER LEVEL SUPPORT. COVERAGE
SHOULD BECOME MORE WIDELY SCATTERED AS THE OVERNIGHT HOURS PROGRESS
LEADING TO UNCERTAINTY IN IMPACTS AT THE TERMINALS. IN FACT SOME
CAMS SUGGEST THAT ACTIVITY MAY DIMINISH COMPLETELY OVER NORTHERN
ILLINOIS...THEN REFORM SOUTH OF THE TERMINALS TOMORROW.
ONCE THE FRONT PASSES THROUGH...THERE MAY BE A BRIEF WINDOW IN THE
MORNING WHERE LOWER MFVR CIGS DEVELOP BEHIND THE FRONT AS THE COOLER
AIR PUSHES INTO THE UPPER 60 DEWPOINTS...BUT SHOULD BE ON THE ORDER
OF AN HOUR OR TWO BEFORE DRIER AIR STARTS TO TRICKLE SOUTH AND
DAYTIME MIXING COMMENCES. WINDS ARE EXPECTED TO BECOME NORTHEASTERLY
AS HIGH PRESSURE BUILDS ACROSS MINNESOTA AND WISCONSIN.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EARLY
OVERNIGHT HOURS.
* MEDIUM TO HIGH CONFIDENCE IN AT LEAST WIDELY SCATTERED TSRA
MOVING INTO THE AREA LATE TONIGHT/EARLY THURSDAY.
* MEDIUM CONFIDENCE IN TIMING FRONTAL WIND SHIFT EARLY THURSDAY.
* LOW CONFIDENCE IN MVFR CIGS BEHIND THE FRONT EARLY THURSDAY.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY...SLT CHC TSRA.
BMD
&&
.MARINE...
237 AM CDT
SOUTHWEST WINDS TO AROUND 25 KT WILL CONTINUE THROUGH THE DAY TODAY
ACROSS NORTHERN LAKE MICHIGAN AHEAD OF AN APPROACHING COLD FRONT
WHICH CURRENTLY STRETCHES FROM SOUTHERN MANITOBA INTO THE DAKOTAS.
WINDS WILL BE A LITTLE WEAKER ON THE SOUTH END OF THE LAKE WHERE THE
GRADIENT ISNT QUITE AS TIGHT. STABLE CONDITIONS ARE EXPECTED OVER
THE LAKE WHICH WILL HELP KEEP HIGHER END GUSTS IN CHECK...THOUGH
WOULDNT BE SURPRISED TO SEE SHIPS REPORT OCCASIONAL GUSTS TO 30
KTS. WINDS TURN NORTHERLY LATE TONIGHT AND EARLY THURSDAY...WITH
GUSTS AROUND 25 KT MAINTAINING ACROSS THE SOUTH HALF OF THE LAKE.
WINDS BEGIN TO TAPER THURSDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE WESTERN LAKES REGION. WINDS WILL TURN SOUTHERLY AGAIN
SATURDAY AS ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE CANADIAN
PRAIRIES...AND FRESHEN UP ESPECIALLY ON SUNDAY WHEN WE MAY ONCE
AGAIN BE LOOKING AT 20 TO 25 KT WINDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
625 AM CDT WED AUG 21 2013
.DISCUSSION...
625 AM CDT
HAVE UPDATED THE FORECAST EARLY THIS MORNING TO ACCOUNT FOR MORE
MORNING AND EARLY AFTERNOON CLOUD COVER. WHAT IS LEFT OF A SHEARED
OUT SHORT WAVE ON WATER VAPOR CENTERED ACROSS WI IS HELPING TO
CAUSE ENOUGH ASCENT AND FOCUS FOR 5000-8000 FT CLOUDS ACROSS
NORTHERN IL AND WI. THE RAP 750-850MB CAPTURES THE RH DEPICTION
PRETTY WELL...AND THE SPC WRF COLUMN CONDENSATE DOES TOO ALTHOUGH
A BIT LATE WITH IT. BOTH SHOW INDICATIONS OF THE CLOUDS STICKING
AROUND INTO THIS AFTERNOON AND WITH THE SLOW MOVEMENT OF THE
SHEARED WAVE THAT SEEMS MORE PLAUSIBLE THAN EARLIER. SO HAVE
BUMPED UP SKY COVER QUITE A BIT AND EASED THE TEMPERATURE CLIMB
ALONG WITH BUMPING DOWN HIGHS 2-4 DEGREES IN THE NORTHERN HALF OF
THE AREA. ITS POSSIBLE MORE MAY NEED TO BE PEELED AWAY IF CLOUDS
ARE THICK ENOUGH. CONFIDENCE IS NOT THAT HIGH ON HOW THICK THE
CLOUDS WILL REMAIN AS RAP DIAGNOSTIC SOUNDINGS INDICATE THE RH TO
BE FAIRLY SHALLOW. EVEN IF SCATTERED AT TIMES THOUGH IT LIKELY
WILL SLOW THE TEMPERATURE JUMP...SO FELT ENOUGH CONFIDENCE TO
LOWER THEM SOME.
MTF
&&
.PREV DISCUSSION...
328 AM CDT
THE FORECAST FOCUS WAS FIRST ON THE CHANCES FOR STORMS TONIGHT AND
MAINLY EARLY THU...WHICH EVEN THOUGH THE COVERAGE IS NOT EXPECTED
TO BE PARTICULARLY HIGH THIS IS THE BEST CHANCE FOR RAIN IN OVER A
WEEK. THEN ATTENTION TURNED TO TEMPERATURES WITH LIKELY 90 TODAY
IN MANY COMMUNITIES...THEN A SHORT TERM COOL DOWN FOLLOWED BY AN
APPRECIABLE WARM UP INTO THE FINAL WEEK OF METEOROLOGICAL SUMMER
/ALREADY???/.
TODAY...WHAT HAS BEEN A STAGNANT BUT VERY PLEASANT PATTERN OVER
THE REGION IS BEGINNING TO SHOW SOME SHIFTING EARLY THIS
MORNING...WITH WATER VAPOR SHOWING A STRONG 110 KT+ JET ACROSS FAR
SOUTHERN CANADA BUCKLING SLIGHTLY INTO THE UPPER MIDWEST. MULTIPLE
SHORT WAVES ARE NOTED ACROSS THE NORTHERN ROCKIES AND UPPER
MIDWEST ON THE LEADING EDGE OF THE IMPINGING UPPER TROUGH. AREA
SOUNDINGS LAST EVENING AND VARIOUS SATELLITE CHANNELS CONTINUE TO
INDICATE A FAIRLY DRY MID LEVEL AIR MASS OVER OUR AREA WHICH WILL
TAKE TIME TO SATURATE...SO NOT EXPECTING BLOWOFF FROM ANY MORNING
CONVECTION TO THE NORTHWEST TO REALLY SPREAD OVER WITH ONLY SOME
CUMULUS THROUGH EARLY AFTERNOON. THE THERMAL RIDGE AT 850-925MB IN
ADVANCE OF THE TROUGH LEANS ESE TODAY OVER THE AREA AND THESE
VALUES DO SUPPORT 90 ABOUT A QUARTER OF THE TIME BASED ON LOCAL
CLIMATOLOGY. GIVEN LOCAL HIGHS YESTERDAY AT 87-88 IN MOST
PLACES...UPSTREAM HIGHS IN CENTRAL IA WERE AT 90...AND WITH OUR
DRYING GROUND OFFERING SENSIBLE HEAT TO BE A BIGGER
FACTOR...BELIEVE 88 TO 92 SHOULD PREVAIL ACROSS MUCH OF THE AREA.
DEW POINTS FAVORED IN THE MID TO UPPER 60S WILL ALLOW FOR HEAT
INDEX READINGS TO INCH INTO THE MID 90S IN A SOME COMMUNITIES.
TONIGHT INTO THU MORNING...AS PRIMARY HEIGHT FALLS DEVELOP EAST
ACROSS ONTARIO...THE DEVELOPING SURFACE LOW WILL TRACK EAST UP
THERE...WITH A WEAK SECONDARY LOW /1011MB OR SO/ FAVORED IN
GUIDANCE TO MOVE ALONG THE FRONT FROM IA TO CENTRAL LAKE MI
TONIGHT. THIS FEATURE ALONG WITH THE UPPER TO MID JET TURNING MORE
NORTHWEST GIVING THE FRONT A GOOD PUSH SOUTHWARD ACROSS THE AREA
ON THU. SOME GUIDANCE INDICATES CONVECTION INTO THE AREA THIS
EVE...BUT THAT JUST SEEMS TO QUICK GIVEN THE DRY RH AND LIMITED
MOISTURE TRANSPORT IN ADVANCE OF THE SYSTEM. THE FOCUS OF THE
BOUNDARY CONVERGENCE WILL BE IN WI LATE AFTERNOON AND EVE WITH
SCATTERED POSSIBLY STRONG CONVECTION EXPECTED THERE. GIVEN HIGH
INSTABILITY AND ASSOCIATED DCAPE VALUES UPSTREAM A FEW CLUSTERS
MAY MAKE QUICK PROGRESS SE BY MID TO LATE EVE INTO
OVERNIGHT...ESPECIALLY IF OVER THE LAKE. BUT AGAIN COVERAGE LOOKS
SCATTERED. THIS SYSTEM HAS THE MAKINGS OF A LATE SUMMER FRONT BY
OVERNIGHT WITH WEAKENING SURFACE PRESSURES ALONG IT IN THE WAKE OF
THE AFOREMENTIONED LOW...WEAKENING WARM AIR ADVECTION/DIFFERENTIAL
TEMPERATURE ADVECTION IN ADVANCE OF IT...AND AGAIN LIMITED
MOISTURE. THE DEEP LAYER SHEAR ALSO IS MARGINAL WITH VECTORS
ORIENTED POORLY FOR ANY MCS TYPE ORGANIZATION. OVERALL THE MODEL
SUITE SUPPORTS LIMITED AREAL COVERAGE OF QPF GREATER THAN 0.25 IN.
SO KEEP MAINLY CHANCE POPS EVERYWHERE TONIGHT WITH ONLY MINOR
TWEAKS TO WHAT WAS IN THERE...AND MAINTAIN THE HIGHEST OVERNIGHT.
REST OF THU AND FRI....DRY AIR AND SUPPRESSION MOVE QUICKLY
SOUTHWARD BEHIND THE SURFACE COOL FRONT...WHICH LOOKS TO MOVE
DOWN THE LAKE AND THROUGH CHICAGO SOMETIME IN THE MID-MORNING.
THIS MAY CONTINUE TO SUPPORT SCATTERED SHOWERS AND SOME STORMS
ALONG IT...SO MAINTAIN POPS ESPECIALLY FOR THE SOUTHERN CWA
THROUGH THE DAY. THE PATTERN SUPPORTS TEMPS LIKELY FALLING ALONG
THE LAKE SHORE BY LATE MORNING INTO EARLY AFTERNOON AND REACHING
THEIR PEAK IN OUTLYING AREAS EARLY IN THE AFTERNOON AND THEN
HOLDING STEADY. DRIER AIR REALLY WORKS ITS WAY IN WITHIN THE LOW-
LEVELS THU NIGHT. WITH MOSTLY SUNNY CONDITIONS FRI THIS SHOULD
SUPPORT GOOD MIXING OUT WITH RELATIVE HUMIDITY EXPECTED TO DROP TO
AROUND 30 PERCENT FRI AFTERNOON...AN EARLY SIGN THAT THE NEXT
SEASON IS INDEED NOT FAR AWAY. WITH 850MB TEMPERATURES IN THE MID
TEENS...TEMPS ON FRI LOOK TO BE IN THE MID 70S TO LOWER 80S. FRI
NIGHT SHOULD BE THE COOLEST WITH HIGH PRESSURE STILL PRIMARILY
INFLUENCING THE AREA AND LITTLE CIRRUS EXPECTED. WHILE DEW POINTS
IN THE 40S ARE LIKELY DURING FRI AFTERNOON...THESE SHOULD COME
BACK INTO THE EVE AND LOWS RIGHT NOW LOOK TO BOTTOM OUT IN THE
LOWER TO MID 50S IN MOST OUTLYING LOCATIONS.
BEYOND...THE UPPER RIDGE LOOKS TO BUILD BACK NORTHEAST AS THE
WEEKEND PROGRESSES AND INTO NEXT WEEK...SUPPORTING WARMING
TEMPS AS WELL AS LIKELY PRECIP-FREE CONDITIONS WITH THE FOCUS OF
SYSTEMS AGAIN SHIFTING NORTHWARD. WHILE 90 DEGREES OR WARMER LOOKS
POSSIBLE ON MULTIPLE DAYS WITH MID TO UPPER 60S DEW POINTS...THE
SIGNAL IS STRONGEST ON MON AND TUE WITH THEN SOME BUCKLING DUE TO
POSSIBLE SHORT WAVES/UPSTREAM STORMS. HAVE BLENDED BIAS-
CORRECTED DATA FROM MODELS INTO THE GOING FORECAST WHICH SUPPORTS
WARMER TEMPS THAN A STRAIGHT MODEL BLEND.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* SHRA/TSRA THURSDAY MORNING ASSOCIATED WITH A COLD FRONT.
BMD
//DISCUSSION...UPDATED 06Z...
A COLD FRONT STRETCHES FROM SOUTHERN MANITOBA SOUTHWEST ACROSS THE
DAKOTAS LATE THIS EVENING...WHILE A BROAD AREA OF HIGH PRESSURE
SPANS THE EASTERN CONUS. IN BETWEEN THESE SYSTEMS...CONTINUE TO
EXPECT SOUTHWEST FLOW THROUGH THE PERIOD. PATCHY SHALLOW FOG HAS
DEVELOPED THE PAST FEW MORNINGS AND MAY ONCE AGAIN WEDNESDAY MORNING
AT DPA/RFD AND POSSIBLY GYY. BRIEF MVFR CONDITIONS MAY DEVELOP IN
THE SHALLOW GROUND FOG FOR AN HOUR OR TWO AT THESE SITES. WINDS
SHOULD BEGIN TO PICK AFTER SUNRISE WITH GUSTS INTO THE HIGH TEENS BY
LATE MORNING AND THROUGH THE AFTERNOON.
THE COLD FRONT IS EXPECTED TO MOVE INTO THE AREA THURSDAY MORNING.
BEST GUESS NOW IS APPROX 12-14Z TIMING FOR A WINDSHIFT ACROSS THE
NORTHERN ILLINOIS TERMINALS. MODELS DEVELOP SHOWERS AND
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...BUT THERE ARE A LOT OF
INDICATIONS THAT GUIDANCE MAY BE OVERDOING QPF. THE BEST UPPER LEVEL
SUPPORT DEVELOPS WELL NORTH OF THE AREA AND WE LIE UNDER A PRETTY
WEAK FLOW ENVIRONMENT ALOFT...WITH ONLY ABOUT 25KT WINDS AT 500 MB.
MODELS ALSO INDICATE FAIRLY DRY AIR IN THE LOW AND MID LEVELS. THERE
IS LITTLE SIGNAL FOR ROBUST CONVECTION TO CONTINUE WELL INTO THE
OVERNIGHT HOURS. WHILE THERE WILL PROBABLY BE SOME CONVECTION
FOCUSED NEAR AND JUST AHEAD OF THE FRONT WHERE MODERATE ELEVATED
INSTABILITY IS EXPECTED...COVERAGE MAY BE LOW LENDING TO LOWER
CONFIDENCE IN IMPACTS AT THE TERMINALS. WILL INCLUDE A PROB30
MENTION FOR NOW.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* LOW CONFIDENCE IN IMPACTS AT THE TERMINALS FROM SHRA/TSRA IN THE
CURRENT TAF PERIOD.
* HIGH CONFIDENCE IN VFR CONDITIONS THROUGH WEDNESDAY NIGHT.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...CHC TSRA.
FRIDAY THROUGH MONDAY...VFR.
JEE
&&
.MARINE...
237 AM CDT
SOUTHWEST WINDS TO AROUND 25 KT WILL CONTINUE THROUGH THE DAY TODAY
ACROSS NORTHERN LAKE MICHIGAN AHEAD OF AN APPROACHING COLD FRONT
WHICH CURRENTLY STRETCHES FROM SOUTHERN MANITOBA INTO THE DAKOTAS.
WINDS WILL BE A LITTLE WEAKER ON THE SOUTH END OF THE LAKE WHERE THE
GRADIENT ISNT QUITE AS TIGHT. STABLE CONDITIONS ARE EXPECTED OVER
THE LAKE WHICH WILL HELP KEEP HIGHER END GUSTS IN CHECK...THOUGH
WOULDNT BE SURPRISED TO SEE SHIPS REPORT OCCASIONAL GUSTS TO 30
KTS. WINDS TURN NORTHERLY LATE TONIGHT AND EARLY THURSDAY...WITH
GUSTS AROUND 25 KT MAINTAINING ACROSS THE SOUTH HALF OF THE LAKE.
WINDS BEGIN TO TAPER THURSDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE WESTERN LAKES REGION. WINDS WILL TURN SOUTHERLY AGAIN
SATURDAY AS ANOTHER LOW PRESSURE SYSTEM MOVES ACROSS THE CANADIAN
PRAIRIES...AND FRESHEN UP ESPECIALLY ON SUNDAY WHEN WE MAY ONCE
AGAIN BE LOOKING AT 20 TO 25 KT WINDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
729 PM CDT THU AUG 22 2013
.SYNOPSIS...
ISSUED AT 257 PM CDT THU AUG 22 2013
12Z UA ANALYSIS HAS AN 850MB MOISTURE BOUNDARY FROM LAKE HURON INTO
EASTERN NEBRASKA AND A WEAK SHORTWAVE WAS OVER SOUTHWEST WISCONSIN
INTO IOWA. SOUTH OF THE MOISTURE BOUNDARY 850MB DEW POINTS WERE IN
THE MID TEENS. SATELLITE/RADAR TRENDS THROUGH MID AFTERNOON SHOW THE
NOCTURNAL MCS CONTINUING TO DECAY AS IT MOVES INTO INDIANA. DENSE
CI/CS CLOUDS REMAINED ACROSS THE AREA WITH SPOTTY SPRINKLES AND
ISOLATED SHOWERS.
18Z SFC ANALYSIS HAS THE COLD FRONT FROM NORTHEAST WISCONSIN INTO
EASTERN NEBRASKA WITH THE OUTFLOW BOUNDARY FROM THE MCS FROM
NORTHEAST MISSOURI INTO NORTHERN INDIANA. DEW POINTS WERE IN THE 70S
FROM THE OHIO VALLEY INTO THE DEEP SOUTH WITH 60S OVER MUCH OF THE
MIDWEST. DEW POINTS IN THE 40S AND 50S WERE ACROSS THE DAKOTAS INTO
MINNESOTA AND NORTHERN WISCONSIN.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM CDT THU AUG 22 2013
THE DENSE CLOUD COVER FROM THE NOCTURNAL STORM COMPLEX HAS
SUPPRESSED TEMPERATURES. THE LINGERING SHOWERS ARE FROM WEAK
DISTURBANCES ALOFT. RETURN FLOW DEVELOPING ACROSS IOWA THIS
AFTERNOON MAY ALLOW SOME ISOLATED SHOWERS OR SPRINKLES TO DEVELOP
OVER THE SOUTHWEST THIRD TO 40 PERCENT OF THE CWFA LATE THIS
AFTERNOON AND EVENING AND DISSIPATE SHORTLY AFTER MIDNIGHT.
THE HWY 20 CORRIDOR AND FAR EASTERN PARTS OF THE CWFA RECEIVED
COPIOUS AMOUNTS OF RAINFALL THIS MORNING. WITH WINDS BECOMING LIGHT
TONIGHT AND SKIES EVENTUALLY CLEARING...THESE AREAS WOULD BE PRIMED
FOR FOG LATE TONIGHT AND INTO FRIDAY MORNING.
IF FOG DEVELOPS LATE TONIGHT IT WOULD BURN OFF MY MID TO LATE
MORNING ON FRIDAY. THE MCS AND LIFT TOOLS SHOW AN ELEVATED AREA OF
WAA DEVELOPING OVER ROUGHLY THE SOUTHWEST THIRD OF THE CWFA FRIDAY
AFTERNOON WHICH MAY BE JUST ENOUGH TO ALLOW ISOLATED SHOWERS AND A
FEW THUNDERSTORMS TO DEVELOP. ..08..
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM CDT THU AUG 22 2013
LATE SUMMER HEAT AND DRY WEATHER WILL DOMINATE THE FORECAST PERIOD
AS AN UPPER RIDGE BUILDS OVER THE CENTRAL U.S.
ABOUT THE ONLY CHANCE OF RAIN DURING THIS PERIOD WILL BE FRIDAY
NIGHT INTO SATURDAY WHEN MODELS LINGER A LOW LEVEL MOIST AXIS OVER
THE AREA AND A WEAK S/W RIDES OVER THE DEVELOPING UPPER RIDGE. A
THIS POINT IT APPEARS THE ANY FORCING ASSOCIATED WITH THE S/W WILL
BE WEAK SO KEPT POPS IN THE SLIGHT CHANCE CATEGORY AND LIMITED TO THE
WESTERN COUNTIES WHERE THE BEST INSTABILITY WILL BE LOCATED. AFTER
SATURDAY THE UPPER HIGH WILL BE ESTABLISHED OVER THE CENTRAL U.S.
AND WILL REMAIN IN PLACE THROUGH THURSDAY SUPPRESSING ANY
PRECIPITATION FOR MUCH OF NEXT WEEK.
TEMPERATURES WILL BE THE OTHER CONCERN AS A LATE SUMMER HEAT WAVE
DEVELOPS OVER THE REGION. HIGHS SATURDAY AND SUNDAY SHOULD BE IN
THE UPPER 80S TO LOW 90S THEN 90S ARE EXPECTED FOR MONDAY THROUGH
THURSDAY AS H8 TEMPS WARM INTO THE 20-24C RANGE. THE BLENDED
GUIDANCE KEPT HIGHS IN THE 90 TO 95 RANGE THROUGH THE PERIOD BUT
THIS SEEMED LOW CONSIDERING MIXING H8 TEMPS DOWN TO THE SURFACE
PRODUCED MAXT/S IN THE MID AND UPPER 90S. THE ECMWF SEEMED TO
CAPTURE THE WARMER TEMPS BETTER AND RELIED ON IT/S GUIDANCE FOR NEXT
WEEKS HIGH TEMPERATURES. DEWPOINTS IN THE UPPER 60S OR LOW 70S ARE
EXPECTED TO ACCOMPANY THE HOT TEMPERATURES RESULTING IN HEAT INDEX
VALUES AROUND OR JUST OVER 100. WE COULD ALSO SEE SOME RECORD HIGHS
NEXT WEEK. RECORDS ARE IN THE MID AND UPPER 90S MONDAY THROUGH
THURSDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 649 PM CDT THU AUG 22 2013
MAIN CHALLENGE AND CONCERN IS FOG AND LOW CLOUD POTENTIAL OVERNIGHT
THROUGH FRIDAY MORNING. WEAK BOUNDARY NORTH OF I-80 TO SLOWLY SAG
SOUTH OF THE AREA LATE TONIGHT. ABUNDANT LOW LEVEL MOISTURE AND
NEAR CALM TO CALM WINDS SHOULD PROMOTE FOG DEVELOPMENT OVERNIGHT
INTO MID MORNING ON FRI. HAVE HIT THE FOG THE HARDEST AT KDBQ DUE
TO WET GROUND FROM HEAVY RAINS...AND WENT WITH PERIOD OF LIFR VSBYS
WITH POTENTIAL FOR VLIFR. AT THE OTHER TERMINALS WHERE LITTLE TO
NO RAIN WAS OBSERVED... WENT WITH MVFR TO IFR VSBYS. SOME OF THE
LATEST RAP AND HRRR MODEL GUIDANCE HOWEVER IS SUGGESTING LIFR/VLIFR
CONDITIONS IN DENSE FOG AND LOW CLOUDS AFFECTING ALL SITES LATE
TONIGHT THROUGH FRI MORNING IN AXIS OF LOW LEVEL MOISTURE CONVERGENCE
AHEAD OF MUCH DRIER AIR ON EASTERLY WINDS. NOT CONFIDENT ENOUGH ATTM
ON THIS SCENARIO THOUGH TO ADD LIFR/VLIFR CONDITIONS AT THE OTHER TAF
SITES. ANY LOW CLOUDS AND FOG SHOULD LIFT BY 18Z WITH VFR CONDITIONS
THEREAFTER AS WINDS INCREASE FROM THE E/SE AT 5-10 KTS.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION..CORRECTED
NWS QUAD CITIES IA IL
318 PM CDT WED AUG 21 2013
.SYNOPSIS...
ISSUED AT 314 PM CDT WED AUG 21 2013
12Z UA ANALYSIS HAS AN 850MB TROF RUNNING FROM WESTERN LAKE SUPERIOR
INTO WYOMING. AHEAD OF THIS TROF 850MB DEW POINTS WERE IN THE MID
TEENS FROM UPPER MICHIGAN INTO EASTERN NEBRASKA. SATELLITE/RADAR
TRENDS THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF DIURNAL
CLOUDS ACROSS THE AREA BUT CONVECTION HAS FIRED ALONG THE COLD FRONT
FROM NEAR KFSD INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAS A WEAK LOW NEAR KFSD. THE FRONT RAN NORTHEAST
FROM THE LOW INTO WESTERN UPPER MICHIGAN. AROUND THE FRONTAL
BOUNDARY DEW POINTS WERE IN THE LOW 70S WITH 60S ACROSS THE
REMAINDER OF THE MIDWEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
THE CONVECTION THAT HAS DEVELOPED THIS AFTERNOON IS IN AN AREA OF
STEEP 850-700MB LAPSE RATES AND IN THE SLIGHTLY BETTER
FORCING/CONVERGENCE ASSOCIATED WITH THE FRONTAL ZONE. THE RAP TRENDS
KEEP MORE STABLE AIR ACROSS THE IMMEDIATE AREA THROUGH LATE
AFTERNOON SO ANY CONVECTION APPROACHING THE AREA WILL DISSIPATE.
THE MCS AND LIFT TOOLS SUGGEST ISOLATED TO POSSIBLY SCATTERED
CONVECTION ENTERING THE HWY 20 CORRIDOR DURING THE EARLY EVENING. BY
MID TO LATE EVENING NEW CONVECTION SHOULD DEVELOP AND BECOME LOOSELY
ORGANIZED FROM HWY 30 ON NORTH. BOUNDARIES FROM THIS CONVECTION
SHOULD ALLOW ISOLATED SHOWERS AND STORMS TO DEVELOP ALONG AND SOUTH
OF I-80 AFTER MIDNIGHT.
ON THURSDAY...LINGERING NOCTURNAL CONVECTION SHOULD BE OVER THE AREA
AS THE FRONT CONTINUES TO SLOWLY MOVE SOUTH THROUGH THE AREA.
DIFFERENTIAL HEATING WILL THEN ALLOW NEW CONVECTION TO DEVELOP
DURING THE LATE MORNING AND AFTERNOON HOURS. AS THE NEXT CANADIAN
HIGH BUILDS INTO THE GREAT LAKES...THE DRIER AIR WILL SLOWLY FORCE
THE CONVECTION SOUTH THURSDAY AFTERNOON WITH IT ONLY OVER THE
SOUTHWEST THIRD OF THE CWFA BY THURSDAY EVENING. ..08..
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 314 PM CDT WED AUG 21 2013
AN UPPER RIDGE OVER THE WESTERN STATES IS PROGGED TO BUILD EAST AND
STRENGTHEN THROUGH THE MIDDLE OF NEXT WEEK...PROLONGING THE DRY
CONDITIONS AND BRINGING LATE SUMMER HEAT TO THE REGION.
ABOUT THE ONLY CHANCE OF RAIN WILL BE THE POTENTIAL FOR SOME
LINGERING SHRA/TSRA OVER THE SOUTHWEST THURSDAY NIGHT NEAR A
DECAYING FRONT OVER MISSOURI. FORCING WILL NOT BE VERY STRONG GIVEN
THE WEAK FLOW NEAR THE FRONTAL ZONE AND WITH THE UPPER RIDGE
BUILDING INTO THE REGION...POPS WERE KEPT IN THE SLIGHT CHANCE
CATEGORY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE REGION WITH A
594DM-PLUS H5 HIGH CENTERED OVER MO BY SUNDAY NIGHT AND REMAINING
IN PLACE THROUGH THE MIDDLE OF THE WEEK. THE STRONGER MID LEVEL
FLOW WILL BE DIVERTED AROUND THE RIDGE WHICH WILL KEEP THE BETTER
FORCING WELL NORTH OF THE AREA. THE GFS AND 12Z ECMWF SHOW SOME QPF
OVER THE AREA BY NEXT WEDNESDAY OR WEDNESDAY NIGHT ASSOCIATED WITH
A SHORT WAVE AND FRONT MOVING THE THROUGH THE WESTERN GREAT LAKES
AND MISSISSIPPI VALLEY. HOWEVER KEPT POPS OUT OF THE FORECAST FOR
NOW WITH MID LEVEL TEMPS PROGGED TO BE AROUND 12C SUGGESTING THESE
FEATURES WILL BE FIGHTING A CAP.
SUMMERTIME HEAT WILL BE RETURNING TO THE REGION AS H8 TEMPS WARM
INTO THE LOW 20/S BY SUNDAY AND REMAIN THERE THROUGH MID WEEK. THE
BLENDED GUIDANCE WAS WARMING HIGH TEMPERATURES TO AROUND 90 BUT
MIXING DOWN H8 TEMPS EARLY NEXT WEEK YIELDED HIGHS IN THE LOW TO MID
90S. FORECAST HIGHS WERE SKEWED TOWARD THE TEMPS DERIVED FROM MIXING
WHICH SEEM MORE REASONABLE. WITH THESE WARMER TEMPERATURES...AND
DEWPOINTS EXPECTED TO BE NEAR 70...WE WILL PROBABLY SEE HEAT INDICES
CLOSE TO 100 DURING THE HEAT OF THE DAY. AT THIS TIME IT DOESN/T
APPEAR THAT WE WILL BE CLOSE TO ANY RECORD HIGHS...AT LEAST THROUGH
THE 28TH. RECORDS DURING THIS TIME ARE NEAR OR ABOVE 100 AT THE
CLIMATE SITES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1246 PM CDT WED AUG 21 2013
VFR WX IS EXPECTED THROUGH 03Z/22. AFT 03Z/22 THE POTENTIAL EXISTS
FOR TSRA TO MOVE INTO EASTERN IOWA/NORTHERN ILLINOIS ASSOCIATED
WITH A COLD FRONT. IF A TSRA AFFECTS A TAF SITE A BRIEF PERIOD OF
MVFR/IFR CONDITIONS WILL BE POSSIBLE. AFT 06Z/22 MVFR VSBYS ARE
EXPECTED TO DEVELOP AND LAST THROUGH SUNRISE. THE MODELS ARE
SUGGESTING THE POSSIBILITY OF AN ORGANIZED TSRA COMPLEX AFFECTING
EASTERN IOWA AND NORTHERN ILLINOIS THROUGH 18Z/22. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1259 PM CDT WED AUG 21 2013
.UPDATE...
ISSUED AT 1246 PM CDT WED AUG 21 2013
CONVECTION ACROSS NORTHERN IOWA IS MAINLY CONFINED TO AN AREA OF
STEEP LAPSE RATES IN THE 850-700MB LAYER. RAP TRENDS KEEP THESE
STEEP LAPSE RATES TO THE NORTH/NORTHWEST OF THE CWFA THROUGH LATE
AFTERNOON. THUS CONVECTION APPROACHING THE CWFA WILL DISSIPATE OR
QUICKLY FALL APART OVER THE NORTHWEST QUARTER OF THE CWFA.
RAP TRENDS ON FCST SOUNDINGS SHOW THERMALS SHOULD BEGIN SOON WITH
CONVECTIVE TEMPERATURES ACHIEVED AROUND MID TO LATE AFTERNOON.
TRENDS FROM THE MCS AND LIFT TOOLS WITH THE RAP MODEL SUGGEST THE
POSSIBILITY OF SOME WEAK CONVECTION ENTERING THE HWY 20 CORRIDOR
VERY LATE AFTERNOON/EARLY EVENING. THE MORE ORGANIZED CONVECTION
SHOULD BE NORTH/NORTHEAST OF THE CWFA. BY MID TO LATE EVENING
OUTFLOW BOUNDARIES FROM THIS CONVECTION MAY HELP INITIATE NEW
CONVECTION OVER THE NORTHERN THIRD OF THE CWFA. ..08..
UPDATE ISSUED AT 947 AM CDT WED AUG 21 2013
WEAK ISOLATED SHOWERS CONTINUE TO PERSIST AT MID MORNING. THE
SHOWERS BETWEEN KCID AND KDBQ ARE RAPIDLY DISSIPATING WITH NEW
ISOLATED SHOWERS BETWEEN KMLI AND KOTM.
THE RAP MODEL HAS A SUBTLE VORT MAX MOVING THROUGH EASTERN IOWA
WHICH APPEARS TO BE RESPONSIBLE FOR THE ISOLATED SHOWERS. IF THE
RAP TRENDS ARE CORRECT...THESE NEW SHOWERS WILL DISSIPATE WITHIN
THE NEXT SEVERAL HOURS AS THE VORT MAX EXITS THE CWFA AND DOWNWARD
MOTION TAKES OVER.
THE QUESTION THEN BECOMES WHEN WILL NEW CONVECTION DEVELOP. THE
MCS AND LIFT TOOLS SUGGEST NORTH OF THE CWFA BY LATE AFTERNOON
ALONG THE FRONT. THERE ARE DIFFERENCES BETWEEN THE VARIOUS MODEL
SOLUTIONS AS TO WHEN PRECIPITATION WILL ARRIVE IN THE CWFA. THE
OVERALL FORCING REMAINS WEAK AND FCST SOUNDINGS SUGGEST A CAP
REMAINING IN PLACE THROUGH THE DAY. PRECIPITATION MAY HOLD OFF
UNTIL AFTER SUNSET.
WHAT LLJ IS PRESENT IS EXTREMELY WEAK AND GENERALLY WELL WEST OF
THE CWFA. THE CHANCES FOR PRECIPITATION ARE NOT OVERLY GOOD BUT
WILL MAINTAIN THE CURRENT POPS FOR TONIGHT. ..08..
&&
.SYNOPSIS...
ISSUED AT 331 AM CDT WED AUG 21 2013
WARM AIR IS FINALLY IN TOTAL CONTROL OVER THE ENTIRE CWA EARLY
TODAY...WITH TEMPERATURES HOVERING AROUND 70...WITH DEW POINTS IN THE
MID 60S. A COLD FRONT IS MOVING SLOWLY SOUTHEAST THROUGH THE
DAKOTA...SPARKING A FEW AREAS OF SHOWERS AND THUNDERSTORMS. THE AREA
LOCATED IN SOUTH DAKOTA IS ASSOCIATED WITH A WEAK SHORT WAVE THAT
SHOULD INITIATE STORMS CLOSE TO OUR CWA THIS EVENING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT WED AUG 21 2013
FOR THE FIRST TIME IN WEEKS...THERE IS A REASONABLE CHANCE FOR RAIN
TONIGHT. HOWEVER...WITH WEAK DYNAMICS...AND LESS THAN OPTIMAL
FRONTAL TIMING...THERE REMAINS LOW CONFIDENCE ON A
MATURE...BENEFICIAL RAIN PRODUCING MCS. WHILE THIS IS
POSSIBLE...ESPECIALLY IN THE NORTH 1/2...SIGNALS INDICATING A MATURE
MCS ARE JUST NOT COMING TOGETHER IN A CONFIDENT PICTURE. INFLOW AT
850MB TONIGHT APPEARS WEAK..AND LACKING FOCUSED CONVERGENCE. WHILE
MUCAPE VALUES WILL SUPPORT THUNDER...WE WILL LIKELY NEED A
CONVECTIVE OUTFLOW FROM THE NORTH TO RESULT IN WIDESPREAD
CONVECTION. THIS IS TOO MANY IFS TO RESULT IN A LIKELY COVERAGE
FORECAST ISSUANCE...AND I AM LEFT WITH A RANGE OF CHANCE POPS FROM
20 SOUTH TO 50 NORTH TO BEST DESCRIBE THE EVENT POTENTIAL OVERNIGHT.
RAINFALL WHERE IT OCCURS...COULD BE 0.2 TO 0.5...BUT WIDESPREAD
TOTALS MAY NOT EXCEED 0.1 SHOULD MESOSCALE PROCESSES NOT COME
TOGETHER.
TEMPERATURES AND HUMIDITY WILL BOTH BE QUITE HIGH TODAY...WITH
UPSTREAM TRAJECTORIES AND MIX DOWN IN MODELS SUGGESTING UPPER 80S TO
VERY LOW 90S SHOULD BE WIDESPREAD FOR HIGHS TODAY. TONIGHT...UPPER
60S NORTH TO AROUND 70 SOUTH APPEARS MOST LIKELY FOR LOWS...UNLESS
AN ORGANIZED COLD POOL CAN PUSH RAIN COOLED TEMPERATURES TO THE MID
60S.
ERVIN
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 331 AM CDT WED AUG 21 2013
FOCUS IN THE LONG TERM IS WITH WALKING OUT PCPN CHANCES THU/THU
NIGHT AS FRONT CONTINUES TO MOVE SOUTHWARD THROUGH THE AREA AND
DRIER AIR INTRUDES FROM THE NORTH. LOW CHANCE POPS /26-30/
ARE EXPECTED AS THE FRONT SAGS SOUTHWARD INTO MO AND CENTRAL IL
DURING THE DAY THU. LINGERING SLIGHT CHANCES ARE IN THE SOUTH FOR
THU NIGHT. SURFACE HIGH PRESSURE WILL NUDGE INTO THE AREA FRIDAY
BEFORE QUICKLY MOVING OFF TO THE NE. THEN AN UPPER LEVEL RIDGE OF
HIGH PRESSURE IS EXPECTED TO BUILD INTO THE MID MS RIVER VALLEY
REGION ON ITS HEELS. FRIDAY AND BEYOND...DRY CONDITIONS ARE
ANTICIPATED WITH A WARMING TREND...AS A HEAT WAVE COMMENCES SUN...
LASTING THROUGH TUE. HIGHS THU-SAT WILL BE IN THE 80S /POSSIBLY SOME
UPPER 70S NORTH FRI/...WHILE HIGHS SUN-TUE RISE INTO THE UPPER 80S
AND LOWER 90S...WITH HEAT INDICES IN THE 90S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1246 PM CDT WED AUG 21 2013
VFR WX IS EXPECTED THROUGH 03Z/22. AFT 03Z/22 THE POTENTIAL EXISTS
FOR TSRA TO MOVE INTO EASTERN IOWA/NORTHERN ILLINOIS ASSOCIATED
WITH A COLD FRONT. IF A TSRA AFFECTS A TAF SITE A BRIEF PERIOD OF
MVFR/IFR CONDITIONS WILL BE POSSIBLE. AFT 06Z/22 MVFR VSBYS ARE
EXPECTED TO DEVELOP AND LAST THROUGH SUNRISE. THE MODELS ARE
SUGGESTING THE POSSIBILITY OF AN ORGANIZED TSRA COMPLEX AFFECTING
EASTERN IOWA AND NORTHERN ILLINOIS THROUGH 18Z/22. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...14
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
957 AM CDT WED AUG 21 2013
.UPDATE...
ISSUED AT 947 AM CDT WED AUG 21 2013
WEAK ISOLATED SHOWERS CONTINUE TO PERSIST AT MID MORNING. THE
SHOWERS BETWEEN KCID AND KDBQ ARE RAPIDLY DISSIPATING WITH NEW
ISOLATED SHOWERS BETWEEN KMLI AND KOTM.
THE RAP MODEL HAS A SUBTLE VORT MAX MOVING THROUGH EASTERN IOWA
WHICH APPEARS TO BE RESPONSIBLE FOR THE ISOLATED SHOWERS. IF THE
RAP TRENDS ARE CORRECT...THESE NEW SHOWERS WILL DISSIPATE WITHIN
THE NEXT SEVERAL HOURS AS THE VORT MAX EXITS THE CWFA AND DOWNWARD
MOTION TAKES OVER.
THE QUESTION THEN BECOMES WHEN WILL NEW CONVECTION DEVELOP. THE
MCS AND LIFT TOOLS SUGGEST NORTH OF THE CWFA BY LATE AFTERNOON
ALONG THE FRONT. THERE ARE DIFFERENCES BETWEEN THE VARIOUS MODEL
SOLUTIONS AS TO WHEN PRECIPITATION WILL ARRIVE IN THE CWFA. THE
OVERALL FORCING REMAINS WEAK AND FCST SOUNDINGS SUGGEST A CAP
REMAINING IN PLACE THROUGH THE DAY. PRECIPITATION MAY HOLD OFF
UNTIL AFTER SUNSET.
WHAT LLJ IS PRESENT IS EXTREMELY WEAK AND GENERALLY WELL WEST OF
THE CWFA. THE CHANCES FOR PRECIPITATION ARE NOT OVERLY GOOD BUT
WILL MAINTAIN THE CURRENT POPS FOR TONIGHT. ..08..
&&
.SYNOPSIS...
ISSUED AT 331 AM CDT WED AUG 21 2013
WARM AIR IS FINALLY IN TOTAL CONTROL OVER THE ENTIRE CWA EARLY
TODAY...WITH TEMPERATURES HOVERING AROUND 70...WITH DEW POINTS IN THE
MID 60S. A COLD FRONT IS MOVING SLOWLY SOUTHEAST THROUGH THE
DAKOTA...SPARKING A FEW AREAS OF SHOWERS AND THUNDERSTORMS. THE AREA
LOCATED IN SOUTH DAKOTA IS ASSOCIATED WITH A WEAK SHORT WAVE THAT
SHOULD INITIATE STORMS CLOSE TO OUR CWA THIS EVENING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT WED AUG 21 2013
FOR THE FIRST TIME IN WEEKS...THERE IS A REASONABLE CHANCE FOR RAIN
TONIGHT. HOWEVER...WITH WEAK DYNAMICS...AND LESS THAN OPTIMAL
FRONTAL TIMING...THERE REMAINS LOW CONFIDENCE ON A
MATURE...BENEFICIAL RAIN PRODUCING MCS. WHILE THIS IS
POSSIBLE...ESPECIALLY IN THE NORTH 1/2...SIGNALS INDICATING A MATURE
MCS ARE JUST NOT COMING TOGETHER IN A CONFIDENT PICTURE. INFLOW AT
850MB TONIGHT APPEARS WEAK..AND LACKING FOCUSED CONVERGENCE. WHILE
MUCAPE VALUES WILL SUPPORT THUNDER...WE WILL LIKELY NEED A
CONVECTIVE OUTFLOW FROM THE NORTH TO RESULT IN WIDESPREAD
CONVECTION. THIS IS TOO MANY IFS TO RESULT IN A LIKELY COVERAGE
FORECAST ISSUANCE...AND I AM LEFT WITH A RANGE OF CHANCE POPS FROM
20 SOUTH TO 50 NORTH TO BEST DESCRIBE THE EVENT POTENTIAL OVERNIGHT.
RAINFALL WHERE IT OCCURS...COULD BE 0.2 TO 0.5...BUT WIDESPREAD
TOTALS MAY NOT EXCEED 0.1 SHOULD MESOSCALE PROCESSES NOT COME
TOGETHER.
TEMPERATURES AND HUMIDITY WILL BOTH BE QUITE HIGH TODAY...WITH
UPSTREAM TRAJECTORIES AND MIX DOWN IN MODELS SUGGESTING UPPER 80S TO
VERY LOW 90S SHOULD BE WIDESPREAD FOR HIGHS TODAY. TONIGHT...UPPER
60S NORTH TO AROUND 70 SOUTH APPEARS MOST LIKELY FOR LOWS...UNLESS
AN ORGANIZED COLD POOL CAN PUSH RAIN COOLED TEMPERATURES TO THE MID
60S.
ERVIN
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 331 AM CDT WED AUG 21 2013
FOCUS IN THE LONG TERM IS WITH WALKING OUT PCPN CHANCES THU/THU
NIGHT AS FRONT CONTINUES TO MOVE SOUTHWARD THROUGH THE AREA AND
DRIER AIR INTRUDES FROM THE NORTH. LOW CHANCE POPS /26-30/
ARE EXPECTED AS THE FRONT SAGS SOUTHWARD INTO MO AND CENTRAL IL
DURING THE DAY THU. LINGERING SLIGHT CHANCES ARE IN THE SOUTH FOR
THU NIGHT. SURFACE HIGH PRESSURE WILL NUDGE INTO THE AREA FRIDAY
BEFORE QUICKLY MOVING OFF TO THE NE. THEN AN UPPER LEVEL RIDGE OF
HIGH PRESSURE IS EXPECTED TO BUILD INTO THE MID MS RIVER VALLEY
REGION ON ITS HEELS. FRIDAY AND BEYOND...DRY CONDITIONS ARE
ANTICIPATED WITH A WARMING TREND...AS A HEAT WAVE COMMENCES SUN...
LASTING THROUGH TUE. HIGHS THU-SAT WILL BE IN THE 80S /POSSIBLY SOME
UPPER 70S NORTH FRI/...WHILE HIGHS SUN-TUE RISE INTO THE UPPER 80S
AND LOWER 90S...WITH HEAT INDICES IN THE 90S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 606 AM CDT WED AUG 21 2013
A COLD FRONT WILL SLOWLY MOVE TOWARD EASTERN IOWA LATE THIS
EVENING...TRIGGERING A SCATTERED TO BROKEN LINE OF SHOWERS AND
THUNDERSTORMS. THIS LINE MAY BE WIDESPREAD OR SCATTERED...AND THIS
IS NOT YET CLEAR DUE TO THE TIMING OF THE FRONT. IN ANY
CASE...TODAY WILL BE VFR...WITH SOUTH TO SOUTHWEST WINDS AT 10 TO
20 KTS...BECOMING LIGHT SOUTH THIS EVENING...AND AT DBQ AND
CID...AS THE FRONT APPROACHES...THE WINDS WILL SWITCH TO WEST OR
NORTHWEST AFTER 06Z/22. THE FRONT WILL BE SLOW TO MOVE OUT OF THE
AREA...AND A VICINITY SHOWER THREAT CONTINUES THROUGH 12Z/22. AS
DETAILS BECOME MORE CONFIDENT ON FRONTAL TIMING AND CONVECTIVE
TRENDS...WE WILL LIKELY ADD THUNDERSTORMS TO THE MLI AND BRL
TAFS...BUT FOR NOW...A SHOWER CHANCE IS ALL THAT IS INCLUDED DUE
TO POOR CONFIDENCE ON TIMING AND COVERAGE OF STORMS.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...14
AVIATION...ERVIN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1055 PM EDT THU AUG 22 2013
.UPDATE...
ISSUED AT 1055 PM EDT THU AUG 22 2013
WENT AHEAD AND LOWERED POPS A BIT MORE THROUGH THE OVERNIGHT WITH
CONVECTION DYING OFF. THE HRRR AND RAP13 MODELS STILL REGENERATE SOME
ACTIVITY TOWARDS DAWN...AND WILL CONTINUE TO ROLL WITH AN UPTICK IN POPS
FOR NOW.
UPDATE ISSUED AT 836 PM EDT THU AUG 22 2013
CONVECTION SEEMS TO BE ON THE DECLINE BESIDES A MORE ORGANIZED LINE
OF SHOWERS AND THUNDERSTORMS AFFECTING WEST VIRGINIA...AS WELL AS
SOME SLIGHTLY BETTER CLUSTERED CONVECTION GENERATED FROM A PASSING
OUTFLOW BOUNDARY OUT IN NORTH CENTRAL KENTUCKY. AS SUCH...HAVE LOWERED
POPS FOR THE REST OF THIS EVENING. THE LAST FEW HRRR RUNS HAVE ALSO
SHOWN A GENERAL DECLINE THROUGH THE EVENING. ONCE THE REMAINS OF THE
FRONTAL BOUNDARY AND A PASSING SHORT WAVE TROUGH MOVE THROUGH CLOSER
TO DAWN...SOME SLIGHTLY BETTER COVERAGE WILL BE POSSIBLE...MAINLY IN
THE NORTHEAST. STILL...GIVEN THE CURRENT OVERALL DOWNWARD
TREND...FELT IT WARRANTED TO TRIM BACK THE POPS A BIT INTO THE DAY ON
FRIDAY AS WELL.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 337 PM EDT THU AUG 22 2013
ISOLATED TO SCATTERED CONVECTION ACROSS THE AREA HAS REMAINED
UNORGANIZED AND TAME SO FAR TODAY...WITH LITTLE UPPER LEVEL SUPPORT
AVAILABLE. A SHORT WAVE ON WATER VAPOR IMAGERY OVER THE UPPER MS
VALLEY IS MOVING ESE...WHILE AN OLD OUTFLOW BOUNDARY AT THE SURFACE
IS FOCUSING CONVECTIVE DEVELOPMENT ACROSS CENTRAL OH AND INDIANA.
AS THE SHORT WAVE MOVES INTO THE OH VALLEY TONIGHT...THERE WILL BE
BETTER UPPER LEVEL SUPPORT FOR PRECIPITATION ACROSS THE FORECAST
AREA. THE EXACT EVOLUTION OF CONVECTION DEVELOPING ACROSS OH AND
INDIANA IS UNCERTAIN...AND THE 17Z HRRR HAS MOST PRECIPITATION DYING
OUT BY 02Z. HOWEVER IT DOES SHOW REDEVELOPMENT AROUND 05Z MOST
LIKELY IN ASSOCIATION WITH AN UPPER LEVEL SPEED MAX ASSOCIATED WITH
THE UPPER TROF. THE NAM IS MOST SUPPORTIVE OF PRECIPITATION
OVERNIGHT...BUT THE GFS...ECMWF AND GEM ALL POINT TOWARDS A CHANCE
OF SHOWERS AND THUNDERSTORMS. IT DOES APPEAR THE BEST SUPPORT WILL BE
OVER THE NORTHERN AND EASTERN PORTION OF THE FORECAST AREA AND HAVE
ELECTED TO GO WITH LIKELY PROBABILITY OF RAIN CHANCES IN THESE AREAS
WITH A CHANCE IN THE SOUTHWEST. WEAK COLD FRONT WILL NOT CLEAR THE
AREA UNTIL FRIDAY EVENING...SO WILL CONTINUE WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS FRIDAY...BUT DECREASE CHANCES FROM THE NORTH DURING
THE DAY.
WITH PRECIPITABLE WATER AROUND 1.9 INCHES OR NEAR THE 90TH
PERCENTILE...WILL CONTINUE TO MENTION HEAVY RAIN AND FLASH FLOOD
POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK FOR TONIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 337 PM EDT THU AUG 22 2013
OT A LOT OF CHANGE FROM PREVIOUS FORECAST. MODELS ARE STILL IN
RELATIVELY GOOD AGREEMENT THAT THE UPPER AIR PATTERN WILL CONSIST OF
A LARGE 500MB RIDGE ACROSS THE SOUTH CENTRAL CONUS...EXPECTED TO
REMAIN IN PLACE THROUGH THE DURATION OF THE FORECAST PERIOD. WITH
UPPER LEVEL TROUGHING OFF BOTH THE NW AND NE COAST...EASTERN KY WILL
FIND ITSELF WITHIN THE RIDGING PATTERN...BUT ON THE WINDWARD SIDE OF
THE NE TROUGHING PATTERN. ANY SHORTWAVE THAT TRAVELS ALONG THE
TROUGH AXIS WILL MAKE ITS WAY NEAR EASTERN KY DESPITE THE STRONG
RIDGING IN PLACE. HOWEVER...WITH SOMEWHAT LESS AGREEMENT ON THE
SMALLER SCALE...ANY SHORTWAVES AND RESULTING RAIN CHANCES WILL BE
BEST LEFT TO A MODEL CONSENSUS.
WITH A GOOD VEERING WIND PROFILE...AND TEMPERATURES EXPECTED TO BE
WARMER AND MORE HUMID THAN HAVE BEEN OVER THE PAST FEW WEEKS...ALL
MODELS ARE POINTING AT THE POTENTIAL FOR AFTERNOON INSTABILITY AND
CONVECTION ACROSS THE EASTERN PORTION OF THE STATE THROUGH THE
ENTIRE FORECAST PERIOD. THE ONLY CAVEAT TO THIS IS THE FACT THAT
GFS40 SOUNDINGS /BOTH CURRENT AND PREVIOUS/ ARE SHOWING AN ABUNDANT
AMOUNT OF DRY AIR AT ALL LEVELS...WITH ONLY THE POTENTIAL FOR A SCT
THIN LAYER OF DIURNAL CLOUDS. AND THOUGH THERE IS A GOOD VEERING
PATTERN MENTIONED ABOVE...MOST OF THIS TAKES PLACE IN THE MID LEVELS
RATHER THAN THE LOWER LEVELS...WITH A LOW AMOUNT OF CAPE AND A VERY
LIMITED AMOUNT OF TIME IN THE AFTERNOON WHERE THERE IS NOT A CAPPING
INVERSION. ALL THINGS CONSIDERED...DID PUT IN SOME SLIGHT CHANCE
POPS IN THE AFTERNOON TO GO ALONG WITH MODEL CONSENSUS...BUT EXPECT
THUNDERSTORM DEVELOPMENT TO BE EVEN MORE ISOLATED IN COMPARISON TO
SHOWER POTENTIAL.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 836 PM EDT THU AUG 22 2013
SOME ISOLATED TO SCATTERED SHOWERS AND A STRAY THUNDERSTORM WILL
THREATEN THE AREA THROUGH THIS EVENING...BEFORE FOG DEVELOPMENT
BECOMES THE GREATER CONCERN. EXPECT JKL TO ACHIEVE IFR IF NOT WORSE
CONDITIONS OVERNIGHT...WITH A RECENT HEAVY RAINFALL...KNOCKING BACK
THE DEW POINT DEPRESSIONS. AT LOZ AND SME...EXPECT THE FOG TO DEVELOP
SLOWER WITHOUT A DIRECT HIT FROM CONVECTION. SIMILAR TO LAST
NIGHT...THE FOG MAY LIFT INTO AN IFR OR WORSE STRATUS DECK...BEFORE
MIXING OUT BY THE MID-MORNING HOURS ON FRIDAY. A STRAY SHOWER OR
STORM CAN NOT BE COMPLETELY RULED OUT THROUGH FRIDAY MORNING...HOWEVER
WILL NOT INCLUDE A MENTION FOR NOW. DRIER WEATHER AND VFR CONDITIONS
WILL RETURN THEREAFTER AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE
NORTHWEST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...JMW
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
836 PM EDT THU AUG 22 2013
.UPDATE...
ISSUED AT 836 PM EDT THU AUG 22 2013
CONVECTION SEEMS TO BE ON THE DECLINE BESIDES A MORE ORGANIZED LINE
OF SHOWERS AND THUNDERSTORMS AFFECTING WEST VIRGINIA...AS WELL AS
SOME SLIGHTLY BETTER CLUSTERED CONVECTION GENERATED FROM A PASSING
OUTFLOW BOUNDARY OUT IN NORTH CENTRAL KENTUCKY. AS SUCH...HAVE LOWERED
POPS FOR THE REST OF THIS EVENING. THE LAST FEW HRRR RUNS HAVE ALSO
SHOWN A GENERAL DECLINE THROUGH THE EVENING. ONCE THE REMAINS OF THE
FRONTAL BOUNDARY AND A PASSING SHORT WAVE TROUGH MOVE THROUGH CLOSER
TO DAWN...SOME SLIGHTLY BETTER COVERAGE WILL BE POSSIBLE...MAINLY IN
THE NORTHEAST. STILL...GIVEN THE CURRENT OVERALL DOWNWARD
TREND...FELT IT WARRANTED TO TRIM BACK THE POPS A BIT INTO THE DAY ON
FRIDAY AS WELL.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 337 PM EDT THU AUG 22 2013
ISOLATED TO SCATTERED CONVECTION ACROSS THE AREA HAS REMAINED
UNORGANIZED AND TAME SO FAR TODAY...WITH LITTLE UPPER LEVEL SUPPORT
AVAILABLE. A SHORT WAVE ON WATER VAPOR IMAGERY OVER THE UPPER MS
VALLEY IS MOVING ESE...WHILE AN OLD OUTFLOW BOUNDARY AT THE SURFACE
IS FOCUSING CONVECTIVE DEVELOPMENT ACROSS CENTRAL OH AND INDIANA.
AS THE SHORT WAVE MOVES INTO THE OH VALLEY TONIGHT...THERE WILL BE
BETTER UPPER LEVEL SUPPORT FOR PRECIPITATION ACROSS THE FORECAST
AREA. THE EXACT EVOLUTION OF CONVECTION DEVELOPING ACROSS OH AND
INDIANA IS UNCERTAIN...AND THE 17Z HRRR HAS MOST PRECIPITATION DYING
OUT BY 02Z. HOWEVER IT DOES SHOW REDEVELOPMENT AROUND 05Z MOST
LIKELY IN ASSOCIATION WITH AN UPPER LEVEL SPEED MAX ASSOCIATED WITH
THE UPPER TROF. THE NAM IS MOST SUPPORTIVE OF PRECIPITATION
OVERNIGHT...BUT THE GFS...ECMWF AND GEM ALL POINT TOWARDS A CHANCE
OF SHOWERS AND THUNDERSTORMS. IT DOES APPEAR THE BEST SUPPORT WILL BE
OVER THE NORTHERN AND EASTERN PORTION OF THE FORECAST AREA AND HAVE
ELECTED TO GO WITH LIKELY PROBABILITY OF RAIN CHANCES IN THESE AREAS
WITH A CHANCE IN THE SOUTHWEST. WEAK COLD FRONT WILL NOT CLEAR THE
AREA UNTIL FRIDAY EVENING...SO WILL CONTINUE WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS FRIDAY...BUT DECREASE CHANCES FROM THE NORTH DURING
THE DAY.
WITH PRECIPITABLE WATER AROUND 1.9 INCHES OR NEAR THE 90TH
PERCENTILE...WILL CONTINUE TO MENTION HEAVY RAIN AND FLASH FLOOD
POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK FOR TONIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 337 PM EDT THU AUG 22 2013
OT A LOT OF CHANGE FROM PREVIOUS FORECAST. MODELS ARE STILL IN
RELATIVELY GOOD AGREEMENT THAT THE UPPER AIR PATTERN WILL CONSIST OF
A LARGE 500MB RIDGE ACROSS THE SOUTH CENTRAL CONUS...EXPECTED TO
REMAIN IN PLACE THROUGH THE DURATION OF THE FORECAST PERIOD. WITH
UPPER LEVEL TROUGHING OFF BOTH THE NW AND NE COAST...EASTERN KY WILL
FIND ITSELF WITHIN THE RIDGING PATTERN...BUT ON THE WINDWARD SIDE OF
THE NE TROUGHING PATTERN. ANY SHORTWAVE THAT TRAVELS ALONG THE
TROUGH AXIS WILL MAKE ITS WAY NEAR EASTERN KY DESPITE THE STRONG
RIDGING IN PLACE. HOWEVER...WITH SOMEWHAT LESS AGREEMENT ON THE
SMALLER SCALE...ANY SHORTWAVES AND RESULTING RAIN CHANCES WILL BE
BEST LEFT TO A MODEL CONSENSUS.
WITH A GOOD VEERING WIND PROFILE...AND TEMPERATURES EXPECTED TO BE
WARMER AND MORE HUMID THAN HAVE BEEN OVER THE PAST FEW WEEKS...ALL
MODELS ARE POINTING AT THE POTENTIAL FOR AFTERNOON INSTABILITY AND
CONVECTION ACROSS THE EASTERN PORTION OF THE STATE THROUGH THE
ENTIRE FORECAST PERIOD. THE ONLY CAVEAT TO THIS IS THE FACT THAT
GFS40 SOUNDINGS /BOTH CURRENT AND PREVIOUS/ ARE SHOWING AN ABUNDANT
AMOUNT OF DRY AIR AT ALL LEVELS...WITH ONLY THE POTENTIAL FOR A SCT
THIN LAYER OF DIURNAL CLOUDS. AND THOUGH THERE IS A GOOD VEERING
PATTERN MENTIONED ABOVE...MOST OF THIS TAKES PLACE IN THE MID LEVELS
RATHER THAN THE LOWER LEVELS...WITH A LOW AMOUNT OF CAPE AND A VERY
LIMITED AMOUNT OF TIME IN THE AFTERNOON WHERE THERE IS NOT A CAPPING
INVERSION. ALL THINGS CONSIDERED...DID PUT IN SOME SLIGHT CHANCE
POPS IN THE AFTERNOON TO GO ALONG WITH MODEL CONSENSUS...BUT EXPECT
THUNDERSTORM DEVELOPMENT TO BE EVEN MORE ISOLATED IN COMPARISON TO
SHOWER POTENTIAL.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 836 PM EDT THU AUG 22 2013
SOME ISOLATED TO SCATTERED SHOWERS AND A STRAY THUNDERSTORM WILL
THREATEN THE AREA THROUGH THIS EVENING...BEFORE FOG DEVELOPMENT
BECOMES THE GREATER CONCERN. EXPECT JKL TO ACHIEVE IFR IF NOT WORSE
CONDITIONS OVERNIGHT...WITH A RECENT HEAVY RAINFALL...KNOCKING BACK
THE DEW POINT DEPRESSIONS. AT LOZ AND SME...EXPECT THE FOG TO DEVELOP
SLOWER WITHOUT A DIRECT HIT FROM CONVECTION. SIMILAR TO LAST
NIGHT...THE FOG MAY LIFT INTO AN IFR OR WORSE STRATUS DECK...BEFORE
MIXING OUT BY THE MID-MORNING HOURS ON FRIDAY. A STRAY SHOWER OR
STORM CAN NOT BE COMPLETELY RULED OUT THROUGH FRIDAY MORNING...HOWEVER
WILL NOT INCLUDE A MENTION FOR NOW. DRIER WEATHER AND VFR CONDITIONS
WILL RETURN THEREAFTER AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE
NORTHWEST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...JMW
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
1049 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TONIGHT AND WILL BE FOLLOWED BY
HIGH PRESSURE BUILDING IN FROM THE WEST ON FRIDAY. HIGH PRESSURE
WILL CREST OVER THE REGION ON SATURDAY AND WILL SETTLE SOUTH OF THE
REGION ON SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON
MONDAY AND WILL CROSS THE REGION LATE MONDAY NIGHT AND EARLY
TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT TUESDAY AFTERNOON. LOW PRESSURE WILL PASS SOUTHWEST OF THE
FORECAST AREA WEDNESDAY. A WEAK COLD FRONT WILL DROP SOUTH INTO THE
REGION WEDNESDAY NIGHT AND WILL STALL OVER THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
UPDATE...JUST A FEW TWEAKS TO BETTER REFLECT CURRENT OBSERVATIONAL
TRENDS. POTENT S/WV TROF IS CURRENTLY PUSHING INTO WRN
ONTARIO...AND WILL QUICKLY SWEEP THRU NRN NEW ENGLAND TONIGHT.
GREATEST FORCING FOR ASCENT IS LIKELY OCCURRING ATTM...SO EXPECT
COVERAGE OF SHRA AND EMBEDDED THUNDER TO BE ON THE DECREASE IN
GENERAL. FOR MOST AREAS THIS MEANS SCHC TO CHC POP...WITH LIKELY
CONFINED TO THE NRN MTNS.
PREVIOUS DISCUSSION...STRONG SHORT WAVE TROUGH CONTINUES TO PUSH
ACROSS THE NORTHERN GREAT LAKES. ATTENDANT SFC COLD FRONT
CONTINUES TO MOVE EASTWARD IN ADVANCE OF THE SHORT WAVE TROUGH
ACROSS EASTERNMOST ONTARIO AND SOUTHERN QUEBEC. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED IN ADVANCE OF THE COLD FRONT IN
NORTHERNMOST NY AND NORTHWESTERN VT. A FEW STORMS HAVE ALSO
DEVELOPED NEAR THE SOMERSET/PISCATAQUIS COUNTY BORDER IN MAINE AND
ARE MOVING EAST.
AS THE COLD FRONT CONTINUES TO MARCH EASTWARD OVER THE NEXT
SEVERAL HOURS...THE SHOWERS AND STORMS OVER NORTHERN NY AND VT
WILL MOVE EASTWARD INTO NORTHERN NH AND THE WESTERN ME MOUNTAINS.
WHILE DEEP LAYER SHEAR IS QUITE WEAK...ENOUGH INSTABILITY EXISTS
IN TANDEM WITH 20-30 DEGREE SFC DEWPOINT DEPRESSIONS TO ALLOW FOR
A LOW PROB OF ISOLATED STRONG TO DAMAGING WIND GUSTS WITH THIS
ACTIVITY LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS. HIGHEST
POPS HAVE BEEN PLACED IN THIS AREA...MAINLY NORTH OF A LEBANON NH-
SKOWHEGAN ME LINE.
FURTHER SOUTH...ACTIVITY LOOKS TO REMAIN A LOT MORE ISOLATED. THE
ONLY CAVEAT IS IF A LINE OF SHOWERS AND STORMS DEVELOPS ON THE
NOSE OF THE SHORT WAVE TROUGH AND SFC COLD FRONT AND MOVES ACROSS
THE AREA LATE THIS EVENING TO JUST AFTER MIDNIGHT. THE LATEST FEW
RUNS OF THE HRRR HAS SUGGESTED THIS. GIVEN THE STRENGTH OF THE
FORCING...HAVE INCREASED POPS TO ACCOUNT FOR THIS POSSIBILITY
AFTER DARK. JUST WINDS AND HEAVY DOWNPOURS WILL REMAIN POSSIBLE
WITH THIS ACTIVITY. ANY PRECIPITATION SHOULD SWEEP OFFSHORE BEFORE
DAWN.
&&
.SHORT TERM /FRIDAY NIGHT/...
DEEP UPPER TROUGH MOVES ACROSS THE AREA ON FRIDAY. SO EVEN THOUGH
SFC HIGH PRESSURE MOVES INTO THE AREA...THERE SHOULD BE PLENTY OF
STRATOCU AROUND...AS WELL AS THE SLIGHT CHANCE OF SHOWERS AND
PERHAPS A SPRINKLE.
HIGH PRESSURE CONTINUES TO MOVE IN FRIDAY NIGHT. SKIES SHOULD
CLEAR IN THE EVENING AND WINDS SHOULD GO CALM. THIS WILL LEAD TO
STRONG RADIATIONAL COOLING...WITH A FEW AREAS IN NORTHERN NH
POSSIBLY DROPPING INTO THE MID 30S. SCATTERED FROST?
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER NEW ENGLAND SATURDAY AND WILL
GRADUALLY SETTLE SOUTH OF THE REGION ON SUNDAY. BOTH DAYS LOOKING
VERY NICE WITH ABUNDANT SUNSHINE AND LIGHT WINDS. SHOULD SEE HIGHS
SATURDAY RANGING THROUGH THE 70S FROM NORTH TO SOUTH. WILL TACK ON A
DEGREE OR TWO ON SUNDAY. SATURDAY NIGHT LOOKING PRETTY CHILLY WITH
SOME MOUNTAIN VALLEYS DIPPING INTO THE UPPER 30S. SOUTHERN AREAS
WILL RANGE FROM THE MID 40S TO LOWER 50S ALONG THE COAST.
A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY BUT MOST OF
THE DAY WILL BE SUNNY WITH INCREASING HUMIDITY. TEMPERATURES WILL
ALSO BE ON THE INCREASE WITH MOST AREAS AWAY FROM THE COAST GETTING
INTO THE LOWER TO MID 80S. WILL SEE INCREASING CLOUDS IN NORTHWEST
ZONES DURING THE LATTER HALF OF THE AFTERNOON WITH A CHANCE OF A
SHOWER OR THUNDERSTORM BY EVENING.
COLD FRONT WILL SWING THROUGH MONDAY NIGHT AND EARLY TUESDAY
BRINGING A ROUND SHOWERS AND THUNDERSTORMS TO THE AREA. AFTER A
CLOUDY START TO THE DAY WILL SEE GRADUAL CLEARING FROM EAST TO WEST
IN THE AFTERNOON. NOT A BIG PUSH OF COLD AIR BEHIND THE FRONT SO
WILL SEE HIGHS FROM THE MID 70S TO LOWER 80S.
WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST TUESDAY NIGHT AS
LOW PRESSURE APPROACHES FROM THE WEST. LOW PRESSURE FORECAST TO PASS
SOUTHWEST OF THE REGION ON WEDNESDAY. WILL SEE VARIABLE CLOUDINESS
DURING THE DAY BUT AT THIS POINT LOOKS LIKE ANY PRECIP REMAINS SOUTH
OF THE FORECAST AREA ACROSS SOUTHERN NEW ENGLAND.
LOW PRESSURE HEADS OUT TO SEA WEDNESDAY NIGHT AS A WEAK COLD FRONT
DROPS SOUTH INTO NORTHERN ZONES. WILL SEE A CHANCE OF A SHOWER OR
THUNDERSTORM BOTH WEDNESDAY NIGHT AND THURSDAY AS THIS BOUNDARY
STALLS OVER THE REGION.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...LOCAL MVFR OR LOWER CONDITIONS IN SHOWERS AND
THUNDERSTORMS POSSIBLY THROUGH MIDNIGHT TONIGHT...THEN VFR
CONDITIONS EXPECTED LATE TONIGHT THROUGH FRIDAY NIGHT. VALLEY FOG
LIKELY LATE FRIDAY NIGHT.
LONG TERM...VFR SATURDAY THROUGH MONDAY. AREAS MVFR/IFR CEILINGS
MONDAY NIGHT. VFR TUESDAY.
&&
.MARINE...
SHORT TERM...MARGINAL SCA POSSIBLE TONIGHT INTO FRIDAY WITH A FEW
5 FOOTERS POSSIBLE ON THE OCEAN. HOWEVER...HAVE HELD OFF ON ANY
SCA FOR NOW SINCE MODELS TEND TO BE OVERDOING THE SEAS A BIT AT
THE MOMENT.
LONG TERM...SCA`S LIKELY NEEDED ON MONDAY AND MONDAY NIGHT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...LEGRO
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
849 PM EDT THU AUG 22 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TONIGHT AND WILL BE FOLLOWED BY
HIGH PRESSURE BUILDING IN FROM THE WEST ON FRIDAY. HIGH PRESSURE
WILL CREST OVER THE REGION ON SATURDAY AND WILL SETTLE SOUTH OF THE
REGION ON SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON
MONDAY AND WILL CROSS THE REGION LATE MONDAY NIGHT AND EARLY
TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE
FRONT TUESDAY AFTERNOON. LOW PRESSURE WILL PASS SOUTHWEST OF THE
FORECAST AREA WEDNESDAY. A WEAK COLD FRONT WILL DROP SOUTH INTO THE
REGION WEDNESDAY NIGHT AND WILL STALL OVER THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
UPDATE...HAVE FURTHER TRIMMED BACK ON POP FOR COAST AND COASTAL
PLAIN FOR THE OVERNIGHT. TRENDS ARE FOR MORE SCT SHRA...RATHER
THAN A WIDESPREAD PCPN EVENT. BULK OF THE INSTABILITY REMAINS TIED
UP TO OUR S...AND THUS THE HEAVIER TSTMS ALSO LOOK TO SKIRT THE
MA/NH BORDER. FNT IS CROSSING THE ST. LAWRENCE ATTM....AND CURRENT
SPEED PUTS IT INTO THE NRN ZONES BY 03Z OR SO...AND CLEARING THE
COAST BEFORE 12Z. MESOSCALE GUIDANCE HAS A DECENT HANDLE ON
THIS...SO USED THE HRRR AND LOCAL WRF AS A BASE TO START FROM FOR
POP. OTHERWISE JUST SOME MINOR TWEAKS TO TEMPS AND SKY COVER IN
THE FIRST PERIOD.
PREVIOUS DISCUSSION...STRONG SHORT WAVE TROUGH CONTINUES TO PUSH
ACROSS THE NORTHERN GREAT LAKES. ATTENDANT SFC COLD FRONT
CONTINUES TO MOVE EASTWARD IN ADVANCE OF THE SHORT WAVE TROUGH
ACROSS EASTERNMOST ONTARIO AND SOUTHERN QUEBEC. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED IN ADVANCE OF THE COLD FRONT IN
NORTHERNMOST NY AND NORTHWESTERN VT. A FEW STORMS HAVE ALSO
DEVELOPED NEAR THE SOMERSET/PISCATAQUIS COUNTY BORDER IN MAINE AND
ARE MOVING EAST.
AS THE COLD FRONT CONTINUES TO MARCH EASTWARD OVER THE NEXT
SEVERAL HOURS...THE SHOWERS AND STORMS OVER NORTHERN NY AND VT
WILL MOVE EASTWARD INTO NORTHERN NH AND THE WESTERN ME MOUNTAINS.
WHILE DEEP LAYER SHEAR IS QUITE WEAK...ENOUGH INSTABILITY EXISTS
IN TANDEM WITH 20-30 DEGREE SFC DEWPOINT DEPRESSIONS TO ALLOW FOR
A LOW PROB OF ISOLATED STRONG TO DAMAGING WIND GUSTS WITH THIS
ACTIVITY LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS. HIGHEST
POPS HAVE BEEN PLACED IN THIS AREA...MAINLY NORTH OF A LEBANON NH-
SKOWHEGAN ME LINE.
FURTHER SOUTH...ACTIVITY LOOKS TO REMAIN A LOT MORE ISOLATED. THE
ONLY CAVEAT IS IF A LINE OF SHOWERS AND STORMS DEVELOPS ON THE
NOSE OF THE SHORT WAVE TROUGH AND SFC COLD FRONT AND MOVES ACROSS
THE AREA LATE THIS EVENING TO JUST AFTER MIDNIGHT. THE LATEST FEW
RUNS OF THE HRRR HAS SUGGESTED THIS. GIVEN THE STRENGTH OF THE
FORCING...HAVE INCREASED POPS TO ACCOUNT FOR THIS POSSIBILITY
AFTER DARK. JUST WINDS AND HEAVY DOWNPOURS WILL REMAIN POSSIBLE
WITH THIS ACTIVITY. ANY PRECIPITATION SHOULD SWEEP OFFSHORE BEFORE
DAWN.
&&
.SHORT TERM /FRIDAY NIGHT/...
DEEP UPPER TROUGH MOVES ACROSS THE AREA ON FRIDAY. SO EVEN THOUGH
SFC HIGH PRESSURE MOVES INTO THE AREA...THERE SHOULD BE PLENTY OF
STRATOCU AROUND...AS WELL AS THE SLIGHT CHANCE OF SHOWERS AND
PERHAPS A SPRINKLE.
HIGH PRESSURE CONTINUES TO MOVE IN FRIDAY NIGHT. SKIES SHOULD
CLEAR IN THE EVENING AND WINDS SHOULD GO CALM. THIS WILL LEAD TO
STRONG RADIATIONAL COOLING...WITH A FEW AREAS IN NORTHERN NH
POSSIBLY DROPPING INTO THE MID 30S. SCATTERED FROST?
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD OVER NEW ENGLAND SATURDAY AND WILL
GRADUALLY SETTLE SOUTH OF THE REGION ON SUNDAY. BOTH DAYS LOOKING
VERY NICE WITH ABUNDANT SUNSHINE AND LIGHT WINDS. SHOULD SEE HIGHS
SATURDAY RANGING THROUGH THE 70S FROM NORTH TO SOUTH. WILL TACK ON A
DEGREE OR TWO ON SUNDAY. SATURDAY NIGHT LOOKING PRETTY CHILLY WITH
SOME MOUNTAIN VALLEYS DIPPING INTO THE UPPER 30S. SOUTHERN AREAS
WILL RANGE FROM THE MID 40S TO LOWER 50S ALONG THE COAST.
A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY BUT MOST OF
THE DAY WILL BE SUNNY WITH INCREASING HUMIDITY. TEMPERATURES WILL
ALSO BE ON THE INCREASE WITH MOST AREAS AWAY FROM THE COAST GETTING
INTO THE LOWER TO MID 80S. WILL SEE INCREASING CLOUDS IN NORTHWEST
ZONES DURING THE LATTER HALF OF THE AFTERNOON WITH A CHANCE OF A
SHOWER OR THUNDERSTORM BY EVENING.
COLD FRONT WILL SWING THROUGH MONDAY NIGHT AND EARLY TUESDAY
BRINGING A ROUND SHOWERS AND THUNDERSTORMS TO THE AREA. AFTER A
CLOUDY START TO THE DAY WILL SEE GRADUAL CLEARING FROM EAST TO WEST
IN THE AFTERNOON. NOT A BIG PUSH OF COLD AIR BEHIND THE FRONT SO
WILL SEE HIGHS FROM THE MID 70S TO LOWER 80S.
WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST TUESDAY NIGHT AS
LOW PRESSURE APPROACHES FROM THE WEST. LOW PRESSURE FORECAST TO PASS
SOUTHWEST OF THE REGION ON WEDNESDAY. WILL SEE VARIABLE CLOUDINESS
DURING THE DAY BUT AT THIS POINT LOOKS LIKE ANY PRECIP REMAINS SOUTH
OF THE FORECAST AREA ACROSS SOUTHERN NEW ENGLAND.
LOW PRESSURE HEADS OUT TO SEA WEDNESDAY NIGHT AS A WEAK COLD FRONT
DROPS SOUTH INTO NORTHERN ZONES. WILL SEE A CHANCE OF A SHOWER OR
THUNDERSTORM BOTH WEDNESDAY NIGHT AND THURSDAY AS THIS BOUNDARY
STALLS OVER THE REGION.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...LOCAL MVFR OR LOWER CONDITIONS IN SHOWERS AND
THUNDERSTORMS POSSIBLY THROUGH MIDNIGHT TONIGHT...THEN VFR
CONDITIONS EXPECTED LATE TONIGHT THROUGH FRIDAY NIGHT. VALLEY FOG
LIKELY LATE FRIDAY NIGHT.
LONG TERM...VFR SATURDAY THROUGH MONDAY. AREAS MVFR/IFR CEILINGS
MONDAY NIGHT. VFR TUESDAY.
&&
.MARINE...
SHORT TERM...MARGINAL SCA POSSIBLE TONIGHT INTO FRIDAY WITH A FEW
5 FOOTERS POSSIBLE ON THE OCEAN. HOWEVER...HAVE HELD OFF ON ANY
SCA FOR NOW SINCE MODELS TEND TO BE OVERDOING THE SEAS A BIT AT
THE MOMENT.
LONG TERM...SCA`S LIKELY NEEDED ON MONDAY AND MONDAY NIGHT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
949 PM EDT THU AUG 22 2013
.SYNOPSIS...
AN UPPER LOW WILL CROSS THE CHESAPEAKE BAY THIS EVENING. A COLD
FRONT OVER THE EASTERN GREAT LAKES WILL MOVE THROUGH THE MID
ATLANTIC REGION FRIDAY MORNING. HIGH PRESSURE BUILDS OVERHEAD
FOR THE WEEKEND BEFORE DRIFTING SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
*DUE TO COMMS PROBLEMS OUR 00Z SNDG IS YET TO BE AVBL TO THE PUBLIC.
THE MAIN COLD FRONT IS FCST TO JUMP TO THE SOUTH AND EAST. RGNL
RDR SHOWS WKNG STORMS ACROSS CENTRAL PA TRACKING S. HRRR CONTINUE
TO WEAKEN THE STORMS B4 REACHING WRN MD AND THE POTOMAC HIGHLANDS
THIS EVE.
MODELS SHOW THE NLY SURGE OF DRIER AIR LAGGING SEVERAL HOURS IN
WAKE OF THE FROPA ON FRI. PRECIP CHANCES WILL DIMINISH THRUT THE
DAY FROM NORTH TO SOUTH AS THE COLD FRONT ADVANCES FARTHER SOUTH.
LOWS TNGT IN THE 60S W OF I-95...L70S E. HIGHS FRI IN THE LM80S
XCPT 70S IN THE HIGHLANDS.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
SFC HIPRES BUILDS IN FROM THE GREAT LAKES FRI NGT. NLY WINDS
ACCOMPANYING THE PRESSURE SURGE WILL ADVECT DRIER AIR INTO THE
REGION WITH DEWPOINTS IN THE 50S. SKIES WILL CLEAR FRI EVE BEHIND
THE PASSAGE OF A MID-LEVEL TROUGH. MIN TEMPS RANGE FROM THE LOW
50S IN WRN HIGHLANDS TO MID 60S IN THE CITIES AND ALONG THE WRN
SHORE.
TRANQUIL WX PATTERN IN STORE FOR THE WEEKEND WITH THE HIGH MOVING
OVERHEAD. WITH THE SOURCE OF OUR AIRMASS FROM CANADA...TEMPS WILL BE
SLIGHTLY BELOW NORMAL AND MORE REPRESENTATIVE OF CLIMO IN MID SEP
THAN AUG.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
NXT WK NOT AS CLR CUT. THE SFC HIGH SHUD GET PRESSED SWD AS LOPRES
TRACKS SOMEWHERE ALONG THE CONUS-CNDN BRDR. WAA WL PASS N OF CWFA
MON...FLLWD BY A CDFNT DROPPING INTO THE GRTLKS/NEW ENGLAND TUE-
WED. HOW FAR SWD IT DROPS...AND WHAT /IF ANY/ STORMS TRACK ALONG
THIS BNDRY STILL TBD. THE NOAM H5 HGT PTTN FAVORS A WRN ATLC TROF
AND CENTRL CONUS RDG...SO CWFA SHUD BE ON SRN PERIPHERY OF ANY
POTL STORM TRACK...BUT ANY DETAILS WL NEED TO BE WORKED OUT AS THE
TIME NEARS.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR CONDS XPCTD OVRGNT AND FRI.
COLD FROPA FROM N TO S LATE TNGT INTO FRI MRNG. LGT NWLY WINDS AND
CLOUD COVER WILL LIMIT CHANCES FOR FOG DEVELOPMENT OVNGT. A BRIEF
SHOWER POSSIBLE WITH FROPA. LGT WINDS WILL BECOME NWLY BEHIND THE
FRONT AND PICK UP AROUND 10 KT ON FRI.
FRI NGT-MON...VFR WITH HIPRES IN CONTROL.
&&
.MARINE...
WINDS BLO SCA VALUES TNGT.
THE TROUGH WILL PROGRESS EWD TNGT WITH WINDS BECOME W-NW EVERYWHERE
BEHIND THE TROUGH. A FEW GUSTS TO 15 KT POSSIBLE IN WAKE OF THE
TROUGH PASSAGE.
THE TROUGH WILL MOVE SOUTH OF THE WATERS ON FRIDAY WHILE HIPRES
STARTS TO BUILD IN FROM THE NORTH. A PRESSURE SURGE BEHIND THE FRONT
MAY CAUSE NORTHERLY WINDS TO GUST TO NEAR SCA CRITERIA FRIDAY NIGHT
IN THE MAIN STEM OF THE CHSPK BAY. FCST CONFIDENCE NOT HIGH ENOUGH
ATTM TO ISSUE A THIRD PERIOD ADVISORY.
LGT WINDS THIS WEEKEND WITH HIPRES OVERHEAD.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
UPDATE...WOODY!
PRVS...JRK/HTS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
254 PM EDT WED AUG 21 2013
.SYNOPSIS...
AFTER A FRONT MOVES THROUGH THURSDAY NIGHT...EXPECT SUNNY SKIES
AND DRY WEATHER FROM FRIDAY THROUGH MONDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
UPPER TROUGH AXIS IS CURRENTLY OVER WESTERN OHIO AND IS MOVING TO
THE EAST. AS A RESULT...SCATTERED SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED ACROSS MUCH OF SOUTHERN OHIO...EASTERN KENTUCKY...AND
CENTRAL WEST VIRGINIA. HIGH RESOLUTION MODELS SHOW THE BULK OF THIS
ACTIVITY REMAINING TO THE SOUTH OF INTERSTATE 70...CONSIDERING THE
16Z RUN OF THE RAP MODEL KEEPS MOST OF THE UPPER LEVEL ENERGY TO THE
SOUTH OF THE MASON-DIXON LINE. HAVE GONE WITH LIKELY SHOWERS AND
CHANCE THUNDERSTORMS ACROSS THE WV/MD RIDGES DURING THE EVENING
HOURS...THEN THINK COVERAGE WILL MARKEDLY DECREASE AFTER
MIDNIGHT...DUE TO BOTH THE LOSS OF CONVECTIVE HEATING AND THE TROUGH
AXIS BEING ALIGNED NEAR THE NORTHERN WEST VIRGINIA PANHANDLE. WITH
THE RETURN OF WIDESPREAD CLOUD COVER...LOWS SHOULD REMAIN WARMER
THAN LAST NIGHT...IN THE 60S IN ALL LOCATIONS.
BIGGEST CHANGE IN THE FORECAST IS THE TIMING OF THE APPROACHING
FRONT. MESOSCALE AND HIGH-RESOLUTION MODELS HAVE ALL QUICKENED THE
TIMING OF THE FRONT...WITH THE BULK OF THE RAINFALL NOW COMING
DURING THE AFTERNOON. THIS WILL ALLOW FOR GREATER HEATING AND
THEREFORE INSTABILITY. NAM AND GFS SHOW MODEST AMOUNTS OF
INSTABILITY...BUT KEEP EFFECTIVE SHEAR UNDER 30 KTS. THINK THAT
THERE COULD BE AN ISOLATED STRONG/SEVERE THUNDERSTORM...BUT THAT
THE LACK OF STRONG SHEAR SHOULD KEEP THE CHANCES FOR WIDESPREAD
SEVERE TO BE LIMITED. WITH CLOUD COVER REMAINING THROUGHOUT THE
REGION...HIGH TEMPERATURES SHOULD BE NEAR NORMAL OR A COUPLE
DEGREES COOLER.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
WITH THE STRONGEST DYNAMICS WITH THE FRONT REMAINING WELL TO THE
NORTH AND EAST...HAVE CONTINUED THE IDEA OF THE PREVIOUS FORECAST
THAT KEPT POPS ONLY AT HIGH CHANCE AS OPPOSED TO LIKELY TO THE
SOUTH OF THE INTERSTATE 70 CORRIDOR. POPS WILL DIMINISH DURING
OVERNIGHT...AND HAVE KEPT A TOKEN SLIGHT CHANCE THUNDERSTORM
MENTION IN AFTER MIDNIGHT. WITH THE FASTER FRONTAL
PASSAGE...KEEPING SLIGHT CHANCE POPS FRIDAY MORNING AS FAR NORTH
AS ZANESVILLE...WHEELING...AND INDIANA IS LIKELY A BIT
OVERDONE...BUT DO NOT WANT TO COMPLETELY THROW OUT THE ECMWF
SOLUTION...WHICH KEEPS POPS THROUGH MUCH OF THE DAY. MUCH DRIER
AIR MOVING IN BEHIND THE FRONT SHOULD KEEP SKIES MOSTLY SUNNY ON
FRIDAY. HARD TO EVEN CALL THE FRONT A COLD FRONT...CONSIDERING
HIGHS WILL ONLY DROP 2-3 DEGREES FROM THE DAY BEFORE. BY FRIDAY
NIGHT HIGH PRESSURE SHOULD ESTABLISH ITSELF ACROSS THE GREAT
LAKES...ALLOWING FOR CLEAR SKIES AND LIGHT NORTHERLY FLOW. THIS
WILL DROP TEMPERATURES ABOUT 10 DEGREES BELOW NORMAL FRIDAY
NIGHT...AND A COUPLE DEGREES BELOW NORMAL SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A LARGE UPPER LEVEL RIDGE WILL BUILD OVER THE CENTRAL CONUS
THROUGH MUCH OF THE PERIOD. MOST OF THE MODELS SUGGEST THAT WE
WILL REMAIN ON THE EASTERN PERIPHERY OF THIS RIDGE IN NORTHWEST
FLOW WHICH COULD...BY MIDWEEK...BRING THE CHANCE FOR SHOWERS AND
THUNDERSTORMS AS UPPER LEVEL DISTURBANCES DROP SOUTH OVER THE
GREAT LAKES. FOR NOW...WITH MODEL TIMING DIFFERENCES...KEPT POP
CHANCES LOW. TEMPERATURES WERE KEPT NEAR OR JUST ABOVE SEASONAL
AVERAGES.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
GENERAL VFR IS EXPECTED THROUGH THIS EVENING. AN APPROACHING
UPPER LEVEL LOW WILL BRING THE CHANCE FOR SOME SHOWERS ACROSS
POINTS SOUTH OF PIT TOWARD EVENING...BUT WITH COVERAGE EXPECTED TO
BE SCATTERED...NO MENTION IN THE TAFS. ONCE AGAIN PATCHY MVFR FOG
CAN BE EXPECTED LATER TONIGHT TOWARD DAYBREAK THURSDAY.
ON THURSDAY UPPER TROUGH WILL MOVE ACROSS REGION WITH A TRAILING
COLD FRONT. CONFIDENCE NOT HIGH ENOUGH TO INCLUDE MORE THAN VCTS
MIDDAY NORTH REACHING KPIT EARLY AFTERNOON.
SOUTHERLY WIND AT TIMES MAINLY UNDER 5 KTS BEFORE WINDS BECOME
LIGHT WEST BEHIND FROPA THURSDAY AFTERNOON.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
RESTRICTIONS POSSIBLE THURSDAY NIGHT SOUTH OF KPIT AS FRONT MAY
FIRE IN THE EVENING. OTHERWISE HIGH PRESSURE WILL BEGIN TO BUILD
IN FRIDAY AND DOMINATE INTO MONDAY WITH GENERAL VFR.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
341 PM EDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
MAIN FOCUS OF THE FORECAST FOR TODAY IS THE DEVELOPING THUNDERSTORMS
ASSOCIATED WITH A COLD FRONT JUST STARTING TO MOVE INTO WESTERN
UPPER MICHIGAN. THE COLD FRONT HAS BEEN MAKING IT/S WAY
ACROSS WESTERN LAKE SUPERIOR AND NORTHWEST WISCONSIN OVER THE
LAST FEW HOURS AND THERE WAS SOME CONCERN THAT THE STRATUS DECK
THAT DEVELOPED FROM THE FOG NEAR DULUTH WOULD LIMIT COME OF THE
CONVECTION. BUT THE FORCING FROM THE COLD FRONT COMBINED WITH
DIURNAL HEATING HAS BEGAN TO PRODUCE THUNDERSTORMS ALONG THE COLD
FRONT WITH SOME BECOMING FAIRLY STRONG AT THIS WRITTING. WITH A
VERY UNSTABLE ATMOSPHERE (MLCAPE VALUES ANALYZED FROM 2000-3000
J/KG DUE TO SFC DEWPOINTS IN THE UPPER 60S AND LOWER 70S)...THEY
SHOULDN/T HAVE MUCH DIFFICULTY CONTINUING THROUGH THE EARLY EVENING.
AS HAS BEEN MENTIONED OVER THE LAST COUPLE OF DAYS...0-6KM SHEAR
VALUES ARE A LITTLE MARGINAL...BUT LATEST RAP TRENDS SHOW VALUES
APPROACHING 30-35KTS RIGHT ALONG THE COLD FRONT. THIS SHOULD HELP
THE THUNDERSTORMS BECOME A LITTLE MORE TILTED AND BETTER ORGANIZED
OVER THE NEXT FEW HOURS. THINKING THAT THERE IS A DECENT CHANCE OF
THIS CONVECTION BECOMING LINEAR AND MOVING ACROSS MUCH OF UPPER
MICHIGAN LATE THIS AFTERNOON AND INTO THE EVENING. DAMAGING WIND IS
A DECENT THREAT WITH DCAPE VALUES AHEAD OF THE FRONT OF 800-1100
J/KG. WHERE THERE ARE STRONGER STORMS...HAIL IS ALSO A THREAT...BUT
IT WILL LIKELY BE MORE ISOLATED DUE TO THE HIGHER FREEZING LEVELS.
WITH THE BOUNDARIES OVER THE WEST AND LOWER LCL HEIGHTS FROM THE
LEFT OVER STRATUS...THERE COULD BE A ISOLATED TORNADO THREAT...BUT
SHOULD BE CONFINED TO THE LATE AFTERNOON. IN ADDITION...ANOTHER
BOUNDARY (AIDED BY EARLIER CLOUDS/SHOWERS THAT MOVED ACROSS NORTHERN
LAKE SUPERIOR) HAS SETUP FROM WEST TO EAST FROM ONTONAGON THROUGH
MARQUETTE COUNTY. SHOWERS/THUNDERSTORMS HAVE ALSO STARTED TO DEVELOP
ALONG THIS AND ARE SLIDING EAST. SPC HAS JUST ISSUED A SEVERE
THUNDERSTORM WATCH FOR MUCH OF UPPER MICHIGAN THROUGH 4Z. THE COLD
FRONT AND THUNDERSTORMS ARE EXPECTED TO EXIT INTO LAKE MICHIGAN
AROUND 06Z. PREVIOUS FORECAST HAD A GOOD HANDLE ON TIMING...SO ONLY
MADE MINOR ADJUSTMENTS.
THE REST OF THE NIGHT SHOULD BE DRY (DUE TO DRIER AIR SURGING IN
BEHIND THE COLD FRONT)...EVENTHOUGH A FAIRLY POTENT SHORTWAVE WILL
BE SLIDING SOUTHEAST ACROSS THE AREA FROM LAKE WINNIPEG. THIS
SHOULD LEAD TO MOSTLY CLEAR SKIES AND MUCH COOLER TEMPERATURES THAN
LAST NIGHT.
COOLER NORTHERLY FLOW WILL BE IN STORE FOR UPPER MICHIGAN ON
THURSDAY...AS HIGH PRESSURE APPROACHES THE AREA FROM THE UPPER
MISSISSIPPI VALLEY. 850MB TEMPS WILL BE AROUND 10C COOLER THAN
TODAY AND EXPECT A SIMILAR RESPONSE WITH THE HIGHS (IN THE 70S).
COOLEST TEMPERATURES WILL BE NEAR LAKE SUPERIOR...WHERE THE
NORTHERLY WINDS OFF THE LAKE WILL KEEP TEMPS RIGHT AROUND 70. A
SUNNY TO MOSTLY SUNNY SKY IS EXPECTED.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT WED AUG 21 2013
NAM SHOWS A 500 MB RIDGE ACROSS THE ROCKIES AND CENTRAL PLAINS WITH
A TROUGH OVER THE ERN U.S. 00Z FRI. THE 500 MB RIDGE BUILDS INTO THE
CENTRAL PLAINS THIS FORECAST PERIOD WITH THE EDGE OF THE WESTERLIES
OVER THE AREA THIS FORECAST PERIOD. DID PUT IN SLIGHT CHANCE TO
CHANCE POPS IN THE FORECAST FOR THE WEST HALF FOR SAT AFTERNOON AS A
WARM FRONT HEADS TOWARDS THE AREA AND MOISTURE STARTS TO INCREASE.
OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES. LOOKS TO STAY WARM THROUGH THIS PERIOD.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB RIDGE OVER THE CENTRAL
U.S. SAT NIGHT INTO SUN. THE RIDGE REMAINS STATIONARY THROUGH THE
PERIOD WITH THE U.P. IN THE PERIPHERY OF THE RIDGE IN THE RING OF
FIRE SCENARIO WHERE ANY SHORTWAVE CAN SET OFF A ROUND OF
THUNDERSTORMS. WILL BE HARD TO TIME THESE SHORTWAVES AND EASIEST WAY
TO FORECAST THIS WOULD BE TO BROADBRUSH THIS FORECAST PERIOD WITH
CHANCE POPS EVEN THOUGH IT WILL NOT BE A TOTAL WASHOUT. TEMPERATURES
WILL STAY ABOVE NORMAL FOR THIS FORECAST PERIOD ALONG WITH
INCREASING HUMIDITY. ONLY PERIOD THAT LOOKS DRY IS WED WITH A FRONT
MOVING OUT OF THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 146 PM EDT WED AUG 21 2013
VERY TRICKY AVIATION FORECAST FOR KIWD/KSAW THIS AFTERNOON DUE TO
SOME UNCERTAINTY ON TIMING/LOCATION OF THE CONVECTION THIS
AFTERNOON/EVENING. A COLD FRONT CURRENTLY APPROACHING WESTERN UPPER
MICHIGAN AND POTENTIALLY THROUGH KCMX WILL BRING A POTENTIAL FOR
SHOWERS AND THUNDERSTORMS. BUT HAVE SOME CONCERN THAT THE MVFR DECK
NOW MOVING INTO KIWD WILL LIMIT COVERAGE SOME. THE LAST HOUR HAS
SEEN SOME INCREASE IN CU AND SHOWERS WITHIN THE AREA OF
STRATUS...SO OPTED TO LEAVE IN A TS/VCTS MENTION FOR A PERIOD THIS
AFTERNOON AT KIWD. ONCE THE FRONT MOVES THROUGH AROUND
21-22Z...THUNDER POTENTIAL SHOULD END ALONG WITH THE MVFR CEILINGS.
AS THE SHOWERS/THUNDERSTORMS DEVELOP OVER WESTERN UPPER MICHIGAN
THIS AFTERNOON...MAIN QUESTION FOR KSAW IS IF THEY WILL DEVELOP FAR
ENOUGH NORTH TO INFLUENCE THE SITE. THINKING THEY WILL WITH THE CU
FIELD GOING UP FROM THE CITY OF ONTONAGON TO BARAGA AND THE EASTWARD
MOVEMENT WOULD SLIDE IT THROUGH KSAW AFTER 21Z.
BEHIND THE FRONT TONIGHT INTO THURSDAY...VFR CONDITIONS WILL
PREVAIL AS HIGH PRESSURE BUILDS OVER THE AREA. THERE MAY BE A BRIEF
PERIOD OF SCT100 CLOUDS MOVING IN FROM NORTHWEST MN...BUT WILL NOT
EFFECT OPERATIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 PM EDT WED AUG 21 2013
A COLD FRONT CURRENTLY MOVING ACROSS CENTRAL LAKE SUPERIOR WILL
CONTINUE SOUTHEAST THIS EVENING AND LEAD TO NORTHERLY FLOW
(GENERALLY BELOW 15KTS) OVER THE LAKE FOR THE REST OF TONIGHT AND
INTO THURSDAY EVENING. HIGH PRESSURE THAT IS PRODUCING THE LIGHTER
WINDS WILL THEN SHIFT SOUTHEAST INTO THE LOWER GREAT LAKES AND
ALLOW WINDS TO SLOWLY INCREASE FROM THE SOUTH-SOUTHWEST FRIDAY INTO
THE WEEKEND. AT THIS POINT...WOULD EXPECT LAKE STABILITY FACTORS TO
KEEP WINDS AT OR BELOW 20KTS.
ONE FINAL ITEM TO MENTION IS IF THE SHOWERS/THUNDERSTORMS AFFECT
ENOUGH OF EASTERN LAKE SUPERIOR TO DEVELOP FOG. LEFT OUT AT THIS
POINT SINCE VISIBLE SATELLITE INDICATED THE FOG OVER NORTHERN LAKE
SUPERIOR HAS DISSIPATED AND THERE IS SOME UNCERTAINTY ON HOW FAR
THE RAIN WILL GET INTO EASTERN LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
339 PM EDT WED AUG 21 2013
.SHORT TERM...TONIGHT
VIS SATELLITE AND RADAR SHOW VERY SMALL AREAS OF SHOWERS ALONG AN
AREA OF MOISTURE CONVERGENCE FROM JYM TO PTK. THIS WAS DEPICTED WELL
WITH THE HRRR AS A DIURNAL CONVECTIVE SHOWER EVENT THAT WILL SWING
EAST AND SOUTH...DYING WITH THE LOSS OF DAYTIME HEATING. 20-30 POP
GRIDS WERE UPDATED EARLIER TO INCLUDE THIS CHANCE...WHICH WILL END
NLT 00Z.
CLOUDS AND PRECIP CHANCES INCREASE FROM NW TO SE TONIGHT AS A COLD
FRONT APPROACHES FROM THE NORTHWEST. THERE WILL BE SOME ELEVATED
INSTABILITY...ESPECIALLY NORTH OF I-69 OVERNIGHT AS LI/S ARE -2 OR
-3 AND ABOUT 1000 J/KG OF CAPE IS PRESENT ABOVE 800 MB. WINDS WILL
ALSO VEER AND INCREASE WITH HEIGHT IN THE ELEVATED LAYER
OVERNIGHT...LEADING TO HIGHER POPS TO INCLUDE THUNDER IN THE
FORECAST. THESE CONDITIONS WILL SWING SOUTHEASTWARD THROUGH THE
STATE...BUT HIGHER PW/S (2.0 INCHES) AND LESS INSTABILITY BRING THE
FORECAST TO LOWER THUNDER CHANCES SOUTH OF M-59.
&&
.LONG TERM...THURSDAY THROUGH TUESDAY
A WELL-DEFINED 110KT JET IS EVIDENT ALONG THE US/CANADA BORDER THIS
AFTERNOON AS THE UPPER GRADIENT TIGHTENS BETWEEN THE EXPANSIVE
WESTERN U.S. RIDGE AND SHORTWAVE ENERGY DIGGING INTO SOUTHEAST
SASKATCHEWAN AND SOUTHWEST MANITOBA. MESOANALYSIS REVEALS AN
ORGANIZING LOW-LEVEL BAROCLINIC ZONE ASSOCIATED WITH THIS JET THAT
IS BEGINNING TO FEEL ITS WAY SOUTHEAST AS THE LARGE SCALE TROUGH
OVER CENTRAL AND EASTERN CANADA BEGINS TO SWEEP ACROSS THE GREAT
LAKES. RELATIVELY LITTLE HAS CHANGED WITH REGARD TO FORECAST
REASONING. INITIALLY, SOME REMNANT SHOWERS WILL BE POSSIBLE IN
ADVANCE OF THE FRONT IN ASSOCIATION WITH ANY UPSTREAM DEVELOPMENT
OVER WISCONSIN THIS EVENING, ALTHOUGH CONFIDENCE IS NOT PARTICULARLY
HIGH IN THE DEGREE OF COVERAGE EARLY IN THE PERIOD GIVEN THE LACK OF
LARGE SCALE SUPPORT. STILL, EITHER WEAKLY ORGANIZED RIGHT ENTRANCE
SUPPORT, A CONVECTIVELY ENHANCED WAVE EMANATING OUT OF UPSTREAM
ACTIVITY, OR A COMBINATION OF BOTH, STILL WARRANT A CONTINUATION OF
LIKELY POPS ACROSS MUCH OF THE AREA DURING THE FIRST HALF OF THE
DAY.
UNCERTAINTY FURTHER INCREASES FOR THURSDAY AFTERNOON AS BOUNDARY
LAYER RECOVERY WILL BE STRONGLY DEPENDENT ON CLOUD COVER AND
DURATION OF MORNING SHOWERS. THE NAM/GFS REPRESENT THE AGGRESSIVE
SIDE OF THE ENVELOPE WITH UP TO 3000 J/KG SBCAPE DEVELOPING BY MID
AFTERNOON WHEREAS THE GENERAL CONSENSUS OF BOTH HIGHER RESOLUTION
GUIDANCE SUCH AS THE NMM/ARW AS WELL AS THE GEM/ECMWF ALLOW HIGH
PRESSURE TO AGGRESSIVELY BUILD IN WITH LITTLE MORE THAN A LOW
COVERAGE OF AFTERNOON SHOWERS TO SHOW FOR THE FROPA. GIVEN THE
DEGREE OF UNCERTAINTY, FELT IT PRUDENT TO TAPER POPS BACK INTO THE
HIGH CHANCE CATEGORY ESSENTIALLY EVERYWHERE ALONG/NORTH OF I-94,
WHICH REFLECTS THE LATEST FORECAST REASONING BUT STILL LEAVES ROOM
FOR ADJUSTMENT IN EITHER DIRECTION AS NEW DATA BECOMES AVAILABLE.
FOR FAR SOUTHERN AREAS, ENOUGH RECOVERY WILL BE POSSIBLE TO SUPPORT
A PULSE SEVERE THREAT IMMEDIATELY AHEAD OF THE FRONT, BUT WITH THE
BETTER SHEAR LAGGING BEHIND, THE THREAT FOR ORGANIZED SEVERE WEATHER
REMAINS LOW. TEMPERATURES WILL FALL BACK TO NEAR 80 FOR THE WEEKEND
AS COOLER AND DRIER AIR FILTERS INTO SOUTHEAST MI IN THE WAKE OF THE
FRONT AND HIGH PRESSURE SETTLES OVER THE NORTHEASTERN UNITED STATES.
THERE WILL BE NUMEROUS CHANCES FOR THUNDERSTORMS NEXT WEEK AS THE
CWA WILL BE POSITIONED ALONG THE NE PERIPHERY OF THE BUILDING 595DM
RIDGE OVER THE CENTRAL U.S. WHILE REMAINING IN CLOSE PROXIMITY TO
PREVAILING WESTERLY FLOW. THIS WILL SET THE STAGE FOR MULTIPLE
CONVECTIVE COMPLEXES TO AFFECT SOME OR ALL OF THE REGION. INITIAL
EXPECTATIONS ARE THEREFORE FOR THUNDERSTORM ACTIVITY IN THE VICINITY
TO HELP KEEP TEMPERATURES IN CHECK, BUT WITH H5 HEIGHTS IN THE
585-588DM RANGE AND H85 TEMPS NEAR 20C, THE POTENTIAL FOR HIGHS TO
REACH INTO THE 90S WILL EXIST ON BASICALLY ANY DAY FROM MONDAY
ONWARD.
&&
.MARINE...
A PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE MID-ATLANTIC AND
LOW PRESSURE OVER HUDSON BAY WILL PROVIDE INCREASED SW WINDS
TONIGHT. AIR TEMPERATURES WILL STAY PRETTY WARM UNTIL THE COLD FRONT
SWINGS THROUGH EARLY THURSDAY...SO THERE IS NOT MUCH INSTABILITY
OVER THE LAKES UNTIL THEN. OFFSHORE WINDS WILL BECOME MORE ONSHORE
LATE THURSDAY AND WILL HELP INCREASE WAVE HEIGHTS ALONG THE THUMB`S
SHORE TO 3 FEET. WILL WATCH FOR SMALLCRAFT CONDITIONS NEXT FORECAST
PERIOD...BUT IN THE MEANTIME SIG/MAX WAVES SHOULD STAY MANAGEABLE.
&&
.AVIATION...ISSUED 121 PM EDT WED AUG 21 2013
//DISCUSSION...
DIURNAL CU FIELD HAS ENCOMPASSED THE REGION INTO A BLANKET OF VFR
CLOUDS THIS AFTERNOON. THIS WILL GIVE WAY TO MVFR CONDITIONS AS A
COLD FRONT APPROACHES FROM THE NW OVERNIGHT. CIGS APPEAR TO
GENERALLY BE AROUND 5KFT...BUT VSBYS WILL LIKELY DROP TO MVFR WITHIN
RA AND TSRA THAT DEVELOP NEAR THE PRE-FRONTAL TROUGH AND AHEAD OF
THE COLD FRONT. WINDS SHIFT TO THE NORTH THURS WITH PLENTY OF DRY
AIR RETURNING THINGS TO VFR AFTER THE RAIN.
FOR DTW...BEST THUNDERSTORM CHARACTERISTICS APPEAR TO BE FURTHER
NORTH...SO LEFT TS OUT OF THE TAFS THIS PERIOD. WILL UPDATE WITH AMD
IF NEEDED...BUT DTW WILL LIKELY DROP TO 4SM WITH STRONGEST SHOWERS.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE OF CEILINGS BELOW 5000 FEET AFTER 12Z TONIGHT.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...MM
LONG TERM....JVC
MARINE.......MM
AVIATION.....MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 PM EDT WED AUG 21 2013
.UPDATE...
ISSUED AT 1029 AM EDT WED AUG 21 2013
JUST A QUICK UPDATE FOR THE EXPECTATIONS FOR THIS AFTERNOON AND
EARLY EVENING BASED OFF LATEST HIGHER RESOLUTION MODEL RUNS AND
NEWLY ARRIVING 12Z RUNS. OVERALL...FEEL THAT THE EXPECTATIONS OVER
THE LAST COUPLE OF DAYS STILL SEEM VALID. AT THE PRESENT
TIME...COLD FRONT IS STRETCHING SOUTHWEST FROM JUST NORTH OF LAKE
SUPERIOR THROUGH THE MN ARROWHEAD AND INTO WEST CENTRAL MN.
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ALONG THE
FRONT BUT THEN DECAY AS THEY SLIDE AHEAD OF IT. VERY SHARP CONTRAST
IN DEWPOINTS AHEAD (UPPER 60S AND LOWER 70S) OF THE FRONT AND MID
50S BEHIND. THIS FRONT WILL BE THE FOCUS FOR CONVECTION EARLY-MID
AFTERNOON (18-20Z) AS IT MOVES INTO THE WESTERN U.P. AND THEN STORM
MOTIONS AND FRONT MOVING THE THUNDERSTORMS EAST-SOUTHEAST. SEVERE
WEATHER PARAMETERS LOOK TO BE SIMILAR AS MENTIONED IN THE SHORT TERM
DISCUSSION. AM FAIRLY CONFIDENT ON THUNDERSTORM OCCURRENCE...BUT
SEVERE THREAT IS A LITTLE UNCERTAIN...LARGELY DUE TO THE LIMITED
EFFECTIVE AND 0-6KM BULK SHEAR OF 25-30KT. THIS MAY LIMIT SOME OF THE
TILTING/ORGANIZATION OF THE THUNDERSTORMS. LATEST RAP RUN HAS PUSHED
VALUES UP A LITTLE MORE (TOWARDS 35KTS)...ALONG WITH 09Z SREF
PROBABILITIES...WHICH WITH THE PUSH/FORCING OF THE COLD FRONT LEADS
TO A LITTLE HIGHER CONFIDENCE OF SOME ORGANIZATION AND SEVERE THREAT.
WITH THE SLIGHT INCREASE IN SHEAR...OPTED TO ADD DAMAGING WINDS TO
THE WEATHER GRIDS ALONG WITH SMALL HAIL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM EDT WED AUG 21 2013
CURRENTLY /MIDNIGHT EARLY WED/...THE CWA IS BETWEEN A SFC HIGH OVER
THE ERN SEABOARD AND A SFC TROUGH/COLD FRONT FROM HUDSON BAY TO NW
MN TO SD AND CO. ALOFT...THE CWA IS UNDER THE INFLUENCE OF ZONAL
FLOW OVER CANADA AND THE NRN CONUS...WITH AN UPPER TROUGH NW OF THE
SFC TROUGH.
THE SFC TROUGH/COLD FRONT WILL MOVE ACROSS THE CWA TODAY INTO EARLY
TONIGHT...AND MODELS ARE IN PRETTY GOOD AGREEMENT ON THE TIMING OF
THE FRONT SO TIMING OF POPS WILL BE PRETTY EASY. THE SW/NE ORIENTED
FRONT WILL MOVE TO WRN UPPER MI AROUND 18Z WED...THEN TO ERN LAKE
SUPERIOR AND CENTRAL UPPER MI BY 00Z THU...THEN JUST E OF THE CWA BY
06Z THU. WITH 850MB TEMPS AROUND 20C ALONG AND AHEAD OF THE
FRONT...THOSE AREAS THAT DO NOT EXPERIENCE MUCH CLOUD COVER AND
PRECIP BY PEAK HEATING /MAINLY CENTRAL AND ERN UPPER MI/ WILL SEE
HIGH TEMPS AROUND 90F WED...WITH THE EXCEPTION BEING LOCATIONS N/NE
OF LAKE SUPERIOR DUE TO SW WINDS. OTHERWISE...EXPECT HIGHS IN THE
80S OVER WRN UPPER MI WHERE CLOUDS/PRECIP WILL MOVE IN EARLIER IN
THE DAY WITH THE FRONT. SBCAPES OF 2000-3500 J/KG SHOULD RESULT IN
THE WARM SECTOR...BUT 0-6KM WIND SHEAR IS ONLY 20-30KTS AND ALMOST
COMPLETELY UNIDIRECTIONAL. DCAPE VALUES AROUND 1000 J/KG ARE
POSSIBLE...HIGHEST OVER SCENTRAL UPPER MI. WITH ALL THIS IN
MIND...WIND SHEAR LOOKS TO BE THE LIMITING FACTOR FOR SEVERE
STORMS...BUT WITH THE CAPE AND DCAPE SO HIGH...EXPECT ISOLATED TO
SCATTERED SEVERE STORMS IN PRIMARILY MULTICELL STORM CLUSTER/S WITH
A LIMITED POSSIBILITY OF SUPERCELL THUNDERSTORMS /ESPECIALLY ALONG
LAKE BREEZE BOUNDARIES/. GREATEST THREAT STILL LOOKS LIKE DAMAGING
WINDS...WITH ONLY AN ISOLATED SEVERE HAIL THREAT DUE TO THE FREEZING
LEVEL BEING AROUND 12KFT.
CONVECTION SHOULD EXIT E/SE BY AROUND 06Z-09Z THU...WITH SFC HIGH
PRESSURE QUICKLY FILLING IN BEHIND THE TROUGH. THIS WILL RESULT IN
SOME LOCATIONS OVER WRN UPPER MI BEING ABLE TO FALL TO AROUND 50F
FOR LOWS LATE WED NIGHT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 AM EDT WED AUG 21 2013
MAIN FCST CONCERNS IN THE LONGER TERM ARE TEMPS ON THU/FRI WITH DRY
HI PRES DOMINATING. FOCUS FOR THE WEEKEND INTO EARLY NEXT WEEK ALSO
INCLUDES SHRA/TS CHCS AS A MORE ACTIVE SUMMER-LIKE PATTERN EVOLVES
OVER THE UPR LKS ON THE SRN EDGE OF ZONAL FLOW IN SRN CANADA AND N
OF STRONG RDG IN THE CONUS.
THU...ARRIVAL OF VIGOROUS DNVA/DEEP LYR QVECTOR DVGC UNDER CONFLUENT
UPR FLOW/MUCH DRIER AIR WITH PWAT FCST ARND 0.5 INCH /OR 50 PCT OF
NORMAL/ IN THE WAKE OF SHRTWV PASSAGE EARLY IN THE DAY WL BRING
MOSUNNY WX TO THE CWA ON THU. THE DAY WL ALSO BE MUCH COOLER DESPITE
BRIGHT SUNSHINE WITH H85 TEMPS PROGGED TO BE WITHIN A DEGREE OR 2 OF
10C.
THU NGT...ALTHOUGH SOME OF THE MODELS SHOW ANOTHER SHRTWV DROPPING
SEWD THRU THE GRT LKS IN THE NW FLOW ALF...THIS DISTURBANCE WL HAVE
LTL IMPACT DUE TO THE DRYNESS OF THE AIRMASS AND LARGER SCALE ACYC
FLOW ASSOCIATED WITH SFC HI CENTERED OVER THE AREA. THERE COULD BE
SOME PATCHY CLDS OVER MANLY THE NE HALF OF THE CWA CLOSER TO THE
TRACK OF THIS FEATURE...BUT OVERALL LGT WINDS/PWAT STILL 0.50-0.75
INCH WL ALLOW FOR A HEALTHY DIURNAL TEMP FALL WELL INTO THE 40S AT
THE COOLER INTERIOR LOCATIONS.
FRI...AS THE UPR RDG AXIS SHIFTS E INTO THE WRN GRT LKS AND DEEP LYR
QVECTOR DVGC/DRY AIR DOMINATE...EXPECT MOSUNNY SKIES. THE DAY SHOULD
ALSO TURN A BIT WARMER WITH LARGE SCALE SUBSIDENCE/RETURN SLY FLOW
ON THE WRN FLANK OF SFC HI PRES SHIFTING OVER LOWER MI LIFTING H85
TEMPS UP NEAR 15C OVER THE W BY 00Z SAT. LK BREEZES THAT DVLP NEAR
LK MI AND LK SUP E OF THE KEWEENAW UNDER THE WEAKER PRES GRADIENT
CLOSER TO THE DEPARTING SFC HI PRES WL ALLOW FOR SOME COOLING NEAR
THE LK SHORES IN THOSE AREAS.
FRI NGT...STRENGTHENING SSW WIND ON THE WRN FLANK OF SLOWLY
DEPARTING SFC HI PRES WL LIMIT NOCTURNAL COOLING...ESPECIALLY NEAR
LK SUP OVER THE W HALF WHERE THE STRONGER S WIND UNDER SHARPEST PRES
GRADIENT WL DOWNSLOPE AND SOME HI CLDS SPILLING OVER THE SLOWLY
APRCHG UPR RDG AXIS WL ARRIVE THRU THE NGT. EXPECT THE COOLEST
OVERNGT LO TEMPS ACROSS THE INTERIOR CENTRAL AND E.
THIS WEEKEND...UPR RDG IN THE PLAINS IS PROGGED TO BUILD INTO THE
UPR LKS IN WAD PATTERN/SSW FLOW BTWN HI PRES DRIFTING INTO THE MID
ATLANTIC STATES AND LOWER PRES IN CENTRAL CANADA. A NUMBER OF THE
EXTENDED MODELS SHOW H85 TEMPS NEARING 20C AND PWAT REACHING 1.50 TO
1.75 INCHES BY SUN...SO THE WX WL TURN WARMER AND MORE HUMID.
WHETHER SHRTWVS RIDING THRU THE ZONAL FLOW ON THE TOP OF THIS UPR
RDG WL INTERACT WITH THE INCRSGLY UNSTABLE AIRMASS AND GENERATE
SHRA/TS IS A SGNFT FCST CONCERN. SUSPECT THE BEST SHOT AT SHRA/TS WL
BE SAT NGT/SUN FOLLOWING DEPARTURE OF DRY AIRMASS AND OVER THE NRN
TIER CLOSER TO THE SHRTWVS TRACKING THRU ONTARIO AND LOWER HGTS.
EXTENDED...THE CWA IS FCST TO REMAIN NEAR THE SRN FLANK OF ZONAL
FLOW OVER SRN CANADA AND ON TOP OF UPR RDG DOMINATING THE CONUS.
THIS SUMMER-LIKE PATTERN WITH RECENT ECMWF/GFS RUNS SHOWING H85
TEMPS NEAR 20C IN VCNTY OF A STNRY FNT IS ONE THAT FAVORS EPISODES
OF SHRA WITH HEAVY RA/PERHAPS SVR TSRA ACCOMPANYING THE PASSAGE OF
SHRTWVS THRU THE UPR LKS/ONTARIO NEAR EDGE OF CAPPING INVRN
ASSOCIATED WITH THE STRONG RDG TO THE S. SPECIFYING THE DAY-TO-DAY
DETAILS IN THIS PATTERN IS IMPOSSIBLE ATTM...SO WL STICK TO THE
CONSENSUS FCST. THE CURRENT CPC DAY 3-7 OUTLOOK DOES INDICATE A
THREAT OF HEAVY RA FOR UPR MI OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. TEMPS WL BE ABV NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 146 PM EDT WED AUG 21 2013
VERY TRICKY AVIATION FORECAST FOR KIWD/KSAW THIS AFTERNOON DUE TO
SOME UNCERTAINTY ON TIMING/LOCATION OF THE CONVECTION THIS
AFTERNOON/EVENING. A COLD FRONT CURRENTLY APPROACHING WESTERN UPPER
MICHIGAN AND POTENTIALLY THROUGH KCMX WILL BRING A POTENTIAL FOR
SHOWERS AND THUNDERSTORMS. BUT HAVE SOME CONCERN THAT THE MVFR DECK
NOW MOVING INTO KIWD WILL LIMIT COVERAGE SOME. THE LAST HOUR HAS
SEEN SOME INCREASE IN CU AND SHOWERS WITHIN THE AREA OF
STRATUS...SO OPTED TO LEAVE IN A TS/VCTS MENTION FOR A PERIOD THIS
AFTERNOON AT KIWD. ONCE THE FRONT MOVES THROUGH AROUND
21-22Z...THUNDER POTENTIAL SHOULD END ALONG WITH THE MVFR CEILINGS.
AS THE SHOWERS/THUNDERSTORMS DEVELOP OVER WESTERN UPPER MICHIGAN
THIS AFTERNOON...MAIN QUESTION FOR KSAW IS IF THEY WILL DEVELOP FAR
ENOUGH NORTH TO INFLUENCE THE SITE. THINKING THEY WILL WITH THE CU
FIELD GOING UP FROM THE CITY OF ONTONAGON TO BARAGA AND THE EASTWARD
MOVEMENT WOULD SLIDE IT THROUGH KSAW AFTER 21Z.
BEHIND THE FRONT TONIGHT INTO THURSDAY...VFR CONDITIONS WILL
PREVAIL AS HIGH PRESSURE BUILDS OVER THE AREA. THERE MAY BE A BRIEF
PERIOD OF SCT100 CLOUDS MOVING IN FROM NORTHWEST MN...BUT WILL NOT
EFFECT OPERATIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 250 AM EDT WED AUG 21 2013
OVERALL...EXPECT STRONGEST WINDS /TO AROUND 20KTS/ OVER THE NEXT FEW
DAYS TO BE EARLY THIS MORNING INTO TODAY AS THE PRESSURE GRADIENT
TIGHTENS UP AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH LATE THIS
MORNING INTO THIS EVENING...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR
THE COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE THIS AFTERNOON AND EVENING
FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
ANOTHER PERIOD OF STRONGER WINDS /FROM THE SW/ MAY OCCUR ON
SATURDAY NIGHT INTO SUNDAY AS LAKE SUPERIOR SITS BETWEEN A HIGH
PRESSURE SYSTEM TO THE SE AND A TROUGH OF LOW PRESSURE TO THE NW...
BUT HIGH OVERWATER STABILITY WILL REMAIN A LIMITING FACTOR ON HOW
STRONG THE NEAR SURFACE WINDS WILL BECOME.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...SRF
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
123 PM EDT WED AUG 21 2013
.SYNOPSIS...
ISSUED AT 407 AM EDT WED AUG 21 2013
ANOTHER WARM AND MORE HUMID AFTERNOON IS EXPECTED ACROSS NORTHERN
MICHIGAN TODAY...WITH HIGH TEMPERATURES EXPECTED TO RANGE FROM 10
TO 15 DEGREES ABOVE MID AUGUST NORMALS. A COLD FRONT DROPPING IN
FROM THE NORTHWEST WILL BRING THE THREAT FOR THUNDERSTORMS TO
NORTHERN MICHIGAN...MAINLY FROM LATE THIS AFTERNOON INTO TONIGHT.
COOLER AND LESS HUMID CONDITIONS ARE EXPECTED THURSDAY...AS
PRECIPITATION EXITS THE REGION DURING THE MORNING HOURS.
&&
.UPDATE...
ISSUED AT 123 PM EDT WED AUG 21 2013
STILL NOT A WHOLE LOT GOING ON ACROSS THE REGION...JUST SOME
PASSING MID CLOUDS WITH A WEAK WAVE UP AROUND 700MB CROSSING THE
AREA...ACTING ON AN AREA OF ENHANCED MID LEVEL LAPSE RATES TO HELP
BUBBLE UP SOME ACCAS. DID SEE A COUPLE OF LIGHT SHOWERS FIRE
ACROSS LAKE MICHIGAN...WITH A FEW SURVIVING THE TRIP INLAND THE
PAST FEW HOURS...BUT ISOLATED AT BEST. THAT MAY CONTINUE AS THAT
WAVE AND CORE OF BETTER LAPSE RATES SLIPS INTO NORTHEAST LOWER
THROUGH THE AFTERNOON...BUT THE BIGGER ISSUE WILL BE WHAT HAPPENS
UPSTREAM INTO WISCONSIN AND EASTERN MINNESOTA THE NEXT FEW HOURS.
AIRMASS OUT THAT WAY IS STEADILY DESTABILIZING...WITH A NICE AXIS
OF NEAR 70F DEW POINTS POOLING AHEAD OF A COLD FRONT SLIDING
THROUGH WESTERN LAKE SUPERIOR. CURRENT SBCAPE VALUES UP AROUND
3500 J/KG ARE IMPRESSIVE...TIED TO AN AXIS OF QUITE STEEP
700-500MB LAPSE RATES IN THE PREFRONTAL ENVIRONMENT. DEEPER SHEAR
HASN`T QUITE CAUGHT UP TO THOSE AREAS...BUT IT`S ON ITS WAY WITH A
STRONGER WAVE DIVING INTO SOUTHERN MANITOBA AND A CORE OF BETTER
50 KNOT MID LEVEL FLOW ON ITS SOUTHERN FRINGE.
SO THE REST OF THE AFTERNOON SHOULD REMAIN QUIET AROUND THESE
PARTS...SAVE FOR MAYBE A FEW MORE SHOWERS. BUT DO EXPECT TO SEE
CONVECTION UNZIP AHEAD OF THE FRONTAL BOUNDARY FROM THE WESTERN
U.P. TO NORTHEAST IOWA (SOME HINTS OF THIS ALREADY). WILL BE
CLOSELY FOLLOWING THE EVOLUTION OF THAT ACTIVITY AS IT OCCURS...AS
IT WILL HAVE A MAJOR IMPACT ON OUR CHANCES TONIGHT. HRRR HAS BEEN
INSISTENT ON THE BEST CHANCES WORKING FROM NORTHERN WISCONSIN DOWN
THROUGH OUR SOUTHWEST CWA...AND FORECAST STORM PROPAGATION VECTORS
DO FAVOR THAT TYPE OF EVOLUTION. STILL NOT SO SURE ABOUT GOING
LIKELY POPS...EVEN AT THIS RANGE...BUT WILL LOOK AT A FEW MORE
THINGS BEFORE MAKING ANY WHOLESALE CHANGES. IN THE MEANTIME...
ENJOY THE WARMTH!
UPDATE ISSUED AT 959 AM EDT WED AUG 21 2013
A LITTLE BIT OF A NEBULOUS FORECAST PROBLEM WITH REGARD TO CLOUDS
AND A FEW SHOWERS THE NEXT FEW HOURS. FIRST VISIBLE PICS OF THE
DAY SHOW A RATHER EXPANSIVE ELEVATED CU/ACCAS DECK SPREADING UP
THE LAKE MICHIGAN SPINE...TIED TO AN ENHANCED LOWER LEVEL MOISTURE
AXIS (OBVIOUSLY) BUT WITHIN A PLUME OF STEEPER 850-600MB LAPSE
RATES CLEARLY EVIDENT ON THE 12Z GRB RAOB. AIRMASS FARTHER EAST IS
MUCH LESS UNSTABLE...WITH LOTS OF SUNSHINE WELL UNDERWAY AT THE
MOMENT. HAVE SEEN FEW SHOWERS BUBBLE UP UNDER THE ACCAS DECK...AND
SUSPECT THIS TREND WILL CONTINUE FOR A FEW MORE HOURS AS LOCALIZED
ACCELERATION OF THE LOW LEVEL JET REMAINS ACROSS LAKE MICHIGAN.
NOT TOO KEEN ON THIS ACTIVITY SPREADING TOO FAR EAST...AND THE
SAME WITH CLOUDS...AS SAID STEEPER LAPSE RATES ONLY SLOWLY MIGRATE
EASTWARD THROUGH 18Z PER SHORT TERM GUIDANCE TRENDS. AS
SUCH...WILL CONFINE A SMALL 20 POP/ISOLATED WORDING CLOSER TO THE
STRAITS AND INTO PARTS OF EASTERN UPPER...BUT WITH THIS ACTIVITY
LIKELY TO WANE WITH TIME AS THE BETTER JET FORCING ALSO DECREASES.
OTHERWISE...WILL BE WATCHING THE EVOLUTION OF CONVECTIVE DEBRIS
CROSSING THE WESTERN U.P. THE NEXT FEW HOURS...BUT PER LATEST
TRENDS...SUSPECT MUCH OF THIS WILL ALSO DIMINISH AS ITS ASSOCIATED
CONVECTION IS ALL BUT GONE AT THE MOMENT. WILL OF COURSE BE
WATCHING THE LIKELY REDEVELOPMENT OF MORE CONVECTION WELL UPSTREAM
LATER THIS AFTERNOON...SOME OF WHICH MAY TRY TO CLIP PARTS OF
EASTERN UPPER/FAR NORTHWEST LOWER BEFORE 00Z...BUT HAVE GENERALLY
SLOWED THINGS DOWN BY A FEW HOURS. OUTSIDE OF THAT...AND SOME
ADDITIONAL CU PROBABLY FIRING ACROSS THE REGION...LOOKING VERY
SUMMER-LIKE...WITH CURRENT HIGHS WELL INTO THE 80S TO AROUND 90
LOOKING JUST FINE. ELEVATED FIRE DANGER FOR SURE WITH VERY DRY
GROUND AND GUSTY WINDS.
UPDATE ISSUED AT 646 AM EDT WED AUG 21 2013
SPOTTY RADAR RETURNS POPPING UP OVER NORTHERN LAKE MICHIGAN AS MID
CLOUD CONTINUES TO EXPAND EASTWARD. MINNESOTA MCS STARTING TO
WEAKEN...HAS LOST MOST OF ITS CLOUD-GROUND LIGHTNING AND CLOUD
TOPS STARTING TO WARM. NO MAJOR CHANGES FROM EARLIER THINKING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 407 AM EDT WED AUG 21 2013
PATTERN SYNOPSIS/FORECAST...BROAD BELT OF WEAKLY CYCLONIC STRONG
WESTERLIES LIE JUST NORTH OF THE U.S./CANADA BORDER FROM BRITISH
COLUMBIA INTO NORTHWEST ONTARIO...CONTAINING AN ELONGATED SHORT WAVE
TROUGH RUNNING FROM HUDSON BAY SOUTHWEST INTO SASKATCHEWAN. SMALL
UPPER LOWS WERE SPINNING OFF THE CALIFORNIA COAST AS WELL AS OVER
ILLINOIS/INDIANA EARLY THIS MORNING. UPPER LEVEL FLOW RELATIVELY
WEAK ACROSS THE GREAT LAKES...STUCK BETWEEN THE STRONGER HEIGHT
GRADIENT TO THE NORTH AND THE UPPER LOW SOUTH OF THE STATE (10-15KT
500MB WINDS OFF 00Z APX/GRB/DTX/BUF SOUNDINGS). MIDNIGHT SURFACE
ANALYSIS SHOWS A COLD FRONT ASSOCIATED WITH THE CANADIAN UPPER
JET/SHORT WAVE LYING ACROSS NORTHWEST ONTARIO...SOUTHWEST TO A
1003MB FRONTAL WAVE OVER NORTHWEST MINNESOTA AND EXTENDING BACK INTO
THE DAKOTAS. HIGH PRESSURE WAS LOCATED OVER THE MID ATLANTIC...WITH
SOUTH/SOUTHWEST BOUNDARY LAYER FLOW INTO THE GREAT LAKES/UPPER
MIDWEST BETWEEN THESE FEATURES. INCREASINGLY HUMID AIR MASS AHEAD
OF THE COLD FRONT WITH WIDESPREAD 60+ DEW POINTS ACROSS THE GREAT
LAKES/MIDWEST...WITH A POOL OF 70+ DEW POINTS ACROSS THE EASTERN
DAKOTAS/MINNESOTA CLOSER TO THE COLD FRONT. SEVERAL AREAS OF
CONVECTION HAVE SPROUTED UP ALONG THE FRONT FROM THE DAKOTAS INTO
ONTARIO...SUBTLE 700MB SHORT WAVE TROUGH ALSO KICKED OFF A SMALL
AREAS OF SHOWERS OVER CENTRAL WISCONSIN ALONG 850MB MOISTURE
GRADIENT. CLOSER TO HOME...SKIES WERE MAINLY CLEAR EARLY THIS
MORNING ACROSS NORTHERN MICHIGAN.
DECENT COLD ADVECTION OUT AHEAD OF THE CANADIAN SHORT WAVE TROUGH
SUGGEST A CONTINUED EASTWARD PROGRESSION TODAY...AND SOME DIGGING AS
WELL WHICH SHOULD BRING HEIGHT FALLS INTO MICHIGAN BY TONIGHT. THIS
IN TURN WILL PUSH THE COLD FRONT ACROSS THE UPPER MIDWEST AND INTO
WESTERN UPPER MICHIGAN/WISCONSIN BY LATE AFTERNOON...AND EVENTUALLY
ACROSS NORTHERN/CENTRAL LOWER MICHIGAN BY DAYBREAK THURSDAY. SO
SHORT TERM FORECAST ISSUES WILL PRIMARILY BE FOCUSED ON SOME MUCH
NEEDED PRECIPITATION CHANCES AHEAD OF THE APPROACHING COLD FRONT.
TODAY/TONIGHT...WEATHER: FIRST CONCERN IS WEAK 700MB WAVE MOVING
TOWARD LOWER MICHIGAN EARLY THIS MORNING...ALREADY PUSHING SOME MID
CLOUDS INTO LAKE MICHIGAN. CONCERN IS THAT WITH INCREASING LOW
LEVEL MOISTURE WE MAY SEE ENOUGH ELEVATED INSTABILITY TO POP SOME
SHOWERS THIS MORNING MAINLY ACROSS EASTERN UPPER/PERHAPS FAR
NORTHWEST LOWER. CHANCES APPEAR RATHER SUBTLE...WHICH MAKES IT
DIFFICULT TO DETERMINE IF THREAT IS SUFFICIENT TO ADD POPS TO THE
MORNING FORECAST. BUT STARTING TO SEE SOME CONVECTION OVER EASTERN
LAKE SUPERIOR OVER PAST COUPLE OF HOURS...SO THIS IDEA MAY NOT BE
TOO FAR FETCHED. WILL ALSO KEEP AN EYE ON SMALL MCS OVER NORTHERN
MINNESOTA...WHICH IS MOSTLY TRACKING EAST. THINK THIS WILL TEND TO
WEAKEN AS IT REACHES WESTERN LAKE SUPERIOR IN A FEW HOURS. BUT
MAIN SHOW AS FAR AS PRECIP GOES WILL BE ALONG UPSTREAM COLD FRONT
ACROSS WESTERN UPPER MICHIGAN/WISCONSIN/ SOUTHERN MINNESOTA...MLCAPE
VALUES AHEAD OF THE FRONT FORECAST TO EXCEED 3000J/KG THIS
AFTERNOON...WITH FRONTAL FORCING AUGMENTED BY INCREASING DIFLUENCE
ALOFT. SO THUNDERSTORMS EXPECTED TO DEVELOP UPSTREAM THIS AFTERNOON
AND WORK EAST TOWARD THE FORECAST AREA BY LATE AFTERNOON AND (MORE
LIKELY) EARLY EVENING. REMAINING CONVECTIVE ACTIVITY WILL CROSS THE
FORECAST AREA TONIGHT. MAIN SEVERE THREAT WILL BE UPSTREAM ACROSS
WESTERN UPPER/WISCONSIN WHERE INSTABILITY WILL BE GREATEST...STORMS
WILL ARRIVE IN NORTHERN MICHIGAN ON THE DOWNWARD SIDE OF THE DIURNAL
CYCLE. WILL HAVE TO SEE HOW MUCH INERTIA CONVECTION HAS ONCE IT
ARRIVES.
TEMPERATURES: HIGHS TODAY ONCE AGAIN SHOULD BE WELL INTO THE 80S/
AROUND 90 ACROSS NORTHERN LOWER. LOWS THURSDAY MORNING SHOULD BE
MOSTLY 60S.
WINDS: BREEZY DAY ANTICIPATED ACROSS NORTHERN MICHIGAN AHEAD OF THE
COLD FRONT...ESPECIALLY ACROSS UPPER MICHIGAN WHERE WIND GUSTS OF
30+MPH PROBABLE. NORTHERN LOWER WINDS MORE IN THE 10-20G25MPH
RANGE. WINDS WILL DIMINISH THIS EVENING WITH LOSS OF MIXING...
EVENTUALLY SWINGING AROUND TO THE NORTHWEST WITH FRONTAL PASSAGE
OVERNIGHT.
&&
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 407 AM EDT WED AUG 21 2013
THE SURFACE COLD FRONT WILL CONTINUE ITS TREK ACROSS
THE REGION THURSDAY MORNING TAKING ANY LEFTOVER SHOWERS OR STORMS
ACROSS SOUTHEAST COUNTIES ALONG WITH IT. MEANWHILE...A LARGE AREA OF
SURFACE HIGH PRESSURE FROM CANADA WILL BRING COOLER CONDITIONS INTO
THE REGION LATER THURSDAY THROUGH SATURDAY. IN ADDITION...MUCH DRIER
AIR ALONG WITH GUSTY WINDS...WILL LIKELY LEAD TO ELEVATED FIRE
DANGER ONCE AGAIN THURSDAY AFTERNOON. INCREASING RIDGING ALOFT IS
THEN EXPECTED TO RESULT IN ANOTHER WELCOMED WARMING TREND FOR SUNDAY
INTO THE BEGINNING OF NEXT WEEK (IT IS SUMMER AFTER ALL). WARM
ADVECTION DRIVEN SHOWERS AND THUNDERSTORMS ARE POSSIBLE SUNDAY INTO
MONDAY...THOUGH EXTENDED MODELS CONTINUE TO VARY ON THE TIMING AND
COVERAGE OF POSSIBLE CONVECTION. THE MAIN ISSUE IS THE WHEREABOUTS
OF A SURFACE WARM FRONT NEAR OR ACROSS THE REGION...SO CONFIDENCE
CONTINUES TO REMAIN ON THE LOW SIDE. EXTENDED MODELS ARE ADVERTISING
850 MB TEMPERATURES OF WELL INTO THE TEENS TO NEAR 20 C FOR THE
BEGINNING OF NEXT WEEK. SO DEPENDING UPON THE AMOUNT OF CLOUD
COVER...TEMPERATURES MAY APPROACH 90 OR SLIGHTLY HIGHER ACROSS SOME
AREAS...THOUGH LATEST MODEL GUIDANCE IS ONLY IN THE MIDDLE 80S AT
BEST. THIS IS SOMETHING TO MONITOR FOR SURE. FORECAST HIGH
TEMPERATURES WILL RANGE FROM THE LOWER AND MIDDLE 70S NORTH TO THE
UPPER 70S SOUTHEAST FOR BOTH FRIDAY AND SATURDAY. IN
ADDITION...ANOTHER COUPLE OF COOL NIGHTS WITH LOW LYING AREAS LIKELY
FALLING INTO THE LOWER AND MIDDLE 40S EARLY FRIDAY AND SATURDAY
MORNINGS. HIGHS MONDAY THROUGH TUESDAY GENERALLY RANGING FROM THE
MIDDLE 70S NORTH TO THE MIDDLE 80S SOUTH (WHICH AS MENTIONED ABOVE
HAVE THE POTENTIAL TO BE SEVERAL DEGREES WARMER). LOWS IN THE UPPER
50S AND LOWER 60S SUNDAY MORNING THEN MAINLY IN THE 60S FOR THE
REMAINDER OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 123 PM EDT WED AUG 21 2013
VFR THROUGH LATE EVENING...WITH JUST SOME PASSING MID LEVEL
CLOUDS AND CONTINUED GUSTY SOUTHWEST WINDS AT 15 TO 20 KNOTS. WILL
BE WATCHING TO SEE JUST HOW UPSTREAM CONVECTION UNFOLDS THROUGH
THE EVENING HOURS ACROSS WISCONSIN...BUT WHATEVER IS LEFT OF THIS
ACTIVITY WILL CROSS THE TERMINAL SITES ROUGHLY 02-07Z JUST AHEAD
OF A COLD FRONT. BASED ON THE LATEST INDICATIONS...MBL STANDS THE
BEST SHOT TO SEE SOME THUNDER...SO WILL MAINTAIN A LATE TEMPO
MENTION THERE...BUT JUST A VICINITY MENTION FOR APN/TVC/PLN. AS
THE FRONT PASSES...CAN ENVISION A ROUND OF FOG AND LOW STRATUS
DEVELOPING AS MOISTURE LINGERS JUST BEHIND THE SHALLOW
BOUNDARY...WITH A PERIOD OF IFR CONDITIONS EXPECTED FOR ALL SITES.
THAT WILL IMPROVE RAPIDLY THROUGH THURSDAY MORNING AS MUCH DRIER
AIR ARRIVES...WITH A RETURN TO VFR ALL SITES BY 14Z AT THE LATEST
WITH NORTHERLY WINDS 8-12 KNOTS.
&&
.MARINE...
ISSUED AT 407 AM EDT WED AUG 21 2013
SMALL CRAFT ADVISORIES ALREADY UP FOR LAKE MICHIGAN (THROUGH THIS
EVENING) AND LAKE SUPERIOR (THROUGH THIS AFTERNOON) NEARSHORE ZONES
FOR GUSTY WINDS AND BUILDING WAVES ON LAKE MICHIGAN. WINDS WILL
SWING AROUND TO THE NORTHWEST OVERNIGHT WITH A COLD FRONT
PASSAGE...AT THIS POINT PROBABLY REMAINING BELOW SMALL CRAFT
CRITERIA ON TUESDAY.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR LHZ345.
LM...SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR LMZ323-341-342-
344>346.
LS...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LSZ321-322.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...JPB
SHORT TERM...JPB
LONG TERM...AJS
AVIATION...LAWRENCE
MARINE...JPB
AREA FORECAST DISCUSSION...CORRECTED
NWS MARQUETTE MI
1036 AM EDT WED AUG 21 2013
.UPDATE...
ISSUED AT 1029 AM EDT WED AUG 21 2013
JUST A QUICK UPDATE FOR THE EXPECTATIONS FOR THIS AFTERNOON AND
EARLY EVENING BASED OFF LATEST HIGHER RESOLUTION MODEL RUNS AND
NEWLY ARRIVING 12Z RUNS. OVERALL...FEEL THAT THE EXPECTATIONS OVER
THE LAST COUPLE OF DAYS STILL SEEM VALID. AT THE PRESENT
TIME...COLD FRONT IS STRETCHING SOUTHWEST FROM JUST NORTH OF LAKE
SUPERIOR THROUGH THE MN ARROWHEAD AND INTO WEST CENTRAL MN.
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ALONG THE
FRONT BUT THEN DECAY AS THEY SLIDE AHEAD OF IT. VERY SHARP CONTRAST
IN DEWPOINTS AHEAD (UPPER 60S AND LOWER 70S) OF THE FRONT AND MID
50S BEHIND. THIS FRONT WILL BE THE FOCUS FOR CONVECTION EARLY-MID
AFTERNOON (18-20Z) AS IT MOVES INTO THE WESTERN U.P. AND THEN STORM
MOTIONS AND FRONT MOVING THE THUNDERSTORMS EAST-SOUTHEAST. SEVERE
WEATHER PARAMETERS LOOK TO BE SIMILAR AS MENTIONED IN THE SHORT TERM
DISCUSSION. AM FAIRLY CONFIDENT ON THUNDERSTORM OCCURRENCE...BUT
SEVERE THREAT IS A LITTLE UNCERTAIN...LARGELY DUE TO THE LIMITED
EFFECTIVE AND 0-6KM BULK SHEAR OF 25-30KT. THIS MAY LIMIT SOME OF THE
TILTING/ORGANIZATION OF THE THUNDERSTORMS. LATEST RAP RUN HAS PUSHED
VALUES UP A LITTLE MORE (TOWARDS 35KTS)...ALONG WITH 09Z SREF
PROBABILITIES...WHICH WITH THE PUSH/FORCING OF THE COLD FRONT LEADS
TO A LITTLE HIGHER CONFIDENCE OF SOME ORGANIZATION AND SEVERE THREAT.
WITH THE SLIGHT INCREASE IN SHEAR...OPTED TO ADD DAMAGING WINDS TO
THE WEATHER GRIDS ALONG WITH SMALL HAIL. &&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM EDT WED AUG 21 2013
CURRENTLY /MIDNIGHT EARLY WED/...THE CWA IS BETWEEN A SFC HIGH OVER
THE ERN SEABOARD AND A SFC TROUGH/COLD FRONT FROM HUDSON BAY TO NW
MN TO SD AND CO. ALOFT...THE CWA IS UNDER THE INFLUENCE OF ZONAL
FLOW OVER CANADA AND THE NRN CONUS...WITH AN UPPER TROUGH NW OF THE
SFC TROUGH.
THE SFC TROUGH/COLD FRONT WILL MOVE ACROSS THE CWA TODAY INTO EARLY
TONIGHT...AND MODELS ARE IN PRETTY GOOD AGREEMENT ON THE TIMING OF
THE FRONT SO TIMING OF POPS WILL BE PRETTY EASY. THE SW/NE ORIENTED
FRONT WILL MOVE TO WRN UPPER MI AROUND 18Z WED...THEN TO ERN LAKE
SUPERIOR AND CENTRAL UPPER MI BY 00Z THU...THEN JUST E OF THE CWA BY
06Z THU. WITH 850MB TEMPS AROUND 20C ALONG AND AHEAD OF THE
FRONT...THOSE AREAS THAT DO NOT EXPERIENCE MUCH CLOUD COVER AND
PRECIP BY PEAK HEATING /MAINLY CENTRAL AND ERN UPPER MI/ WILL SEE
HIGH TEMPS AROUND 90F WED...WITH THE EXCEPTION BEING LOCATIONS N/NE
OF LAKE SUPERIOR DUE TO SW WINDS. OTHERWISE...EXPECT HIGHS IN THE
80S OVER WRN UPPER MI WHERE CLOUDS/PRECIP WILL MOVE IN EARLIER IN
THE DAY WITH THE FRONT. SBCAPES OF 2000-3500 J/KG SHOULD RESULT IN
THE WARM SECTOR...BUT 0-6KM WIND SHEAR IS ONLY 20-30KTS AND ALMOST
COMPLETELY UNIDIRECTIONAL. DCAPE VALUES AROUND 1000 J/KG ARE
POSSIBLE...HIGHEST OVER SCENTRAL UPPER MI. WITH ALL THIS IN
MIND...WIND SHEAR LOOKS TO BE THE LIMITING FACTOR FOR SEVERE
STORMS...BUT WITH THE CAPE AND DCAPE SO HIGH...EXPECT ISOLATED TO
SCATTERED SEVERE STORMS IN PRIMARILY MULTICELL STORM CLUSTER/S WITH
A LIMITED POSSIBILITY OF SUPERCELL THUNDERSTORMS /ESPECIALLY ALONG
LAKE BREEZE BOUNDARIES/. GREATEST THREAT STILL LOOKS LIKE DAMAGING
WINDS...WITH ONLY AN ISOLATED SEVERE HAIL THREAT DUE TO THE FREEZING
LEVEL BEING AROUND 12KFT.
CONVECTION SHOULD EXIT E/SE BY AROUND 06Z-09Z THU...WITH SFC HIGH
PRESSURE QUICKLY FILLING IN BEHIND THE TROUGH. THIS WILL RESULT IN
SOME LOCATIONS OVER WRN UPPER MI BEING ABLE TO FALL TO AROUND 50F
FOR LOWS LATE WED NIGHT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 AM EDT WED AUG 21 2013
MAIN FCST CONCERNS IN THE LONGER TERM ARE TEMPS ON THU/FRI WITH DRY
HI PRES DOMINATING. FOCUS FOR THE WEEKEND INTO EARLY NEXT WEEK ALSO
INCLUDES SHRA/TS CHCS AS A MORE ACTIVE SUMMER-LIKE PATTERN EVOLVES
OVER THE UPR LKS ON THE SRN EDGE OF ZONAL FLOW IN SRN CANADA AND N
OF STRONG RDG IN THE CONUS.
THU...ARRIVAL OF VIGOROUS DNVA/DEEP LYR QVECTOR DVGC UNDER CONFLUENT
UPR FLOW/MUCH DRIER AIR WITH PWAT FCST ARND 0.5 INCH /OR 50 PCT OF
NORMAL/ IN THE WAKE OF SHRTWV PASSAGE EARLY IN THE DAY WL BRING
MOSUNNY WX TO THE CWA ON THU. THE DAY WL ALSO BE MUCH COOLER DESPITE
BRIGHT SUNSHINE WITH H85 TEMPS PROGGED TO BE WITHIN A DEGREE OR 2 OF
10C.
THU NGT...ALTHOUGH SOME OF THE MODELS SHOW ANOTHER SHRTWV DROPPING
SEWD THRU THE GRT LKS IN THE NW FLOW ALF...THIS DISTURBANCE WL HAVE
LTL IMPACT DUE TO THE DRYNESS OF THE AIRMASS AND LARGER SCALE ACYC
FLOW ASSOCIATED WITH SFC HI CENTERED OVER THE AREA. THERE COULD BE
SOME PATCHY CLDS OVER MANLY THE NE HALF OF THE CWA CLOSER TO THE
TRACK OF THIS FEATURE...BUT OVERALL LGT WINDS/PWAT STILL 0.50-0.75
INCH WL ALLOW FOR A HEALTHY DIURNAL TEMP FALL WELL INTO THE 40S AT
THE COOLER INTERIOR LOCATIONS.
FRI...AS THE UPR RDG AXIS SHIFTS E INTO THE WRN GRT LKS AND DEEP LYR
QVECTOR DVGC/DRY AIR DOMINATE...EXPECT MOSUNNY SKIES. THE DAY SHOULD
ALSO TURN A BIT WARMER WITH LARGE SCALE SUBSIDENCE/RETURN SLY FLOW
ON THE WRN FLANK OF SFC HI PRES SHIFTING OVER LOWER MI LIFTING H85
TEMPS UP NEAR 15C OVER THE W BY 00Z SAT. LK BREEZES THAT DVLP NEAR
LK MI AND LK SUP E OF THE KEWEENAW UNDER THE WEAKER PRES GRADIENT
CLOSER TO THE DEPARTING SFC HI PRES WL ALLOW FOR SOME COOLING NEAR
THE LK SHORES IN THOSE AREAS.
FRI NGT...STRENGTHENING SSW WIND ON THE WRN FLANK OF SLOWLY
DEPARTING SFC HI PRES WL LIMIT NOCTURNAL COOLING...ESPECIALLY NEAR
LK SUP OVER THE W HALF WHERE THE STRONGER S WIND UNDER SHARPEST PRES
GRADIENT WL DOWNSLOPE AND SOME HI CLDS SPILLING OVER THE SLOWLY
APRCHG UPR RDG AXIS WL ARRIVE THRU THE NGT. EXPECT THE COOLEST
OVERNGT LO TEMPS ACROSS THE INTERIOR CENTRAL AND E.
THIS WEEKEND...UPR RDG IN THE PLAINS IS PROGGED TO BUILD INTO THE
UPR LKS IN WAD PATTERN/SSW FLOW BTWN HI PRES DRIFTING INTO THE MID
ATLANTIC STATES AND LOWER PRES IN CENTRAL CANADA. A NUMBER OF THE
EXTENDED MODELS SHOW H85 TEMPS NEARING 20C AND PWAT REACHING 1.50 TO
1.75 INCHES BY SUN...SO THE WX WL TURN WARMER AND MORE HUMID.
WHETHER SHRTWVS RIDING THRU THE ZONAL FLOW ON THE TOP OF THIS UPR
RDG WL INTERACT WITH THE INCRSGLY UNSTABLE AIRMASS AND GENERATE
SHRA/TS IS A SGNFT FCST CONCERN. SUSPECT THE BEST SHOT AT SHRA/TS WL
BE SAT NGT/SUN FOLLOWING DEPARTURE OF DRY AIRMASS AND OVER THE NRN
TIER CLOSER TO THE SHRTWVS TRACKING THRU ONTARIO AND LOWER HGTS.
EXTENDED...THE CWA IS FCST TO REMAIN NEAR THE SRN FLANK OF ZONAL
FLOW OVER SRN CANADA AND ON TOP OF UPR RDG DOMINATING THE CONUS.
THIS SUMMER-LIKE PATTERN WITH RECENT ECMWF/GFS RUNS SHOWING H85
TEMPS NEAR 20C IN VCNTY OF A STNRY FNT IS ONE THAT FAVORS EPISODES
OF SHRA WITH HEAVY RA/PERHAPS SVR TSRA ACCOMPANYING THE PASSAGE OF
SHRTWVS THRU THE UPR LKS/ONTARIO NEAR EDGE OF CAPPING INVRN
ASSOCIATED WITH THE STRONG RDG TO THE S. SPECIFYING THE DAY-TO-DAY
DETAILS IN THIS PATTERN IS IMPOSSIBLE ATTM...SO WL STICK TO THE
CONSENSUS FCST. THE CURRENT CPC DAY 3-7 OUTLOOK DOES INDICATE A
THREAT OF HEAVY RA FOR UPR MI OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. TEMPS WL BE ABV NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 731 AM EDT WED AUG 21 2013
EXPECT VFR CONDITIONS AT ALL 3 TAF SITES DESPITE THE CHANCE FOR
SHRA/TSRA THIS AFTERNOON/EVENING WITH THE PASSAGE OF A COLD FRONT.
EXPECT TSRA/SHRA EARLY THIS AFTERNOON AT KIWD AND KCMX WITH A BETTER
CHANCE LATE THIS AFTERNOON/EARLY EVENING AT KSAW WITH THE FRONTAL
PASSAGE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 250 AM EDT WED AUG 21 2013
OVERALL...EXPECT STRONGEST WINDS /TO AROUND 20KTS/ OVER THE NEXT FEW
DAYS TO BE EARLY THIS MORNING INTO TODAY AS THE PRESSURE GRADIENT
TIGHTENS UP AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH LATE THIS
MORNING INTO THIS EVENING...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR
THE COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE THIS AFTERNOON AND EVENING
FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
ANOTHER PERIOD OF STRONGER WINDS /FROM THE SW/ MAY OCCUR ON
SATURDAY NIGHT INTO SUNDAY AS LAKE SUPERIOR SITS BETWEEN A HIGH
PRESSURE SYSTEM TO THE SE AND A TROUGH OF LOW PRESSURE TO THE NW...
BUT HIGH OVERWATER STABILITY WILL REMAIN A LIMITING FACTOR ON HOW
STRONG THE NEAR SURFACE WINDS WILL BECOME.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1030 AM EDT WED AUG 21 2013
.UPDATE...
ISSUED AT 1029 AM EDT WED AUG 21 2013
JUST A QUICK UPDATE FOR THE EXPECTATIONS FOR THIS AFTERNOON AND
EARLY EVENING BASED OFF LATEST HIGHER RESOLUTION MODEL RUNS AND
NEWLY ARRIVING 12Z RUNS. OVERALL...FEEL THAT THE EXPECTATIONS OVER
THE LAST COUPLE OF DAYS STILL SEEM VALID. AT THE PRESENT
TIME...COLD FRONT IS STRETCHING SOUTHWEST FROM JUST NORTH OF LAKE
SUPERIOR THROUGH THE MN ARROWHEAD AND INTO WEST CENTRAL MN.
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ALONG THE
FRONT BUT THEN DECAY AS THEY SLIDE AHEAD OF IT. VERY SHARP CONTRAST
IN DEWPOINTS AHEAD (UPPER 60S AND LOWER 70S) OF THE FRONT AND MID
50S BEHIND. THIS FRONT WILL BE THE FOCUS FOR CONVECTION EARLY-MID
AFTERNOON (18-20Z) AS IT MOVES INTO THE WESTERN U.P. AND THEN STORM
MOTIONS AND FRONT MOVING THE THUNDERSTORMS EAST-SOUTHEAST. SEVERE
WEATHER PARAMETERS LOOK TO BE SIMILAR AS MENTIONED IN THE SHORT TERM
DISCUSSION. AM FAIRLY CONFIDENT ON THUNDERSTORM OCCURRENCE...BUT
SEVERE THREAT IS A LITTLE UNCERTAIN...LARGELY DUE TO THE LIMITED
EFFECT AND 0-6KM BULK SHEAR OF 25-30KT. THIS MAY LIMIT SOME OF THE
TILTING/ORGANIZATION OF THE THUNDERSTORMS. LATEST RAP RUN HAS PUSHED
VALUES UP A LITTLE MORE (TOWARDS 35KTS)...ALONG WITH 09Z SREF
PROBABILITIES...WHICH WITH THE PUSH/FORCING OF THE COLD FRONT LEADS
TO A LITTLE HIGHER CONFIDENCE OF SOME ORGANIZATION AND SEVERE THREAT.
WITH THE SLIGHT INCREASE IN SHEAR...OPTED TO ADD DAMAGING WINDS TO
THE WEATHER GRIDS ALONG WITH SMALL HAIL. &&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM EDT WED AUG 21 2013
CURRENTLY /MIDNIGHT EARLY WED/...THE CWA IS BETWEEN A SFC HIGH OVER
THE ERN SEABOARD AND A SFC TROUGH/COLD FRONT FROM HUDSON BAY TO NW
MN TO SD AND CO. ALOFT...THE CWA IS UNDER THE INFLUENCE OF ZONAL
FLOW OVER CANADA AND THE NRN CONUS...WITH AN UPPER TROUGH NW OF THE
SFC TROUGH.
THE SFC TROUGH/COLD FRONT WILL MOVE ACROSS THE CWA TODAY INTO EARLY
TONIGHT...AND MODELS ARE IN PRETTY GOOD AGREEMENT ON THE TIMING OF
THE FRONT SO TIMING OF POPS WILL BE PRETTY EASY. THE SW/NE ORIENTED
FRONT WILL MOVE TO WRN UPPER MI AROUND 18Z WED...THEN TO ERN LAKE
SUPERIOR AND CENTRAL UPPER MI BY 00Z THU...THEN JUST E OF THE CWA BY
06Z THU. WITH 850MB TEMPS AROUND 20C ALONG AND AHEAD OF THE
FRONT...THOSE AREAS THAT DO NOT EXPERIENCE MUCH CLOUD COVER AND
PRECIP BY PEAK HEATING /MAINLY CENTRAL AND ERN UPPER MI/ WILL SEE
HIGH TEMPS AROUND 90F WED...WITH THE EXCEPTION BEING LOCATIONS N/NE
OF LAKE SUPERIOR DUE TO SW WINDS. OTHERWISE...EXPECT HIGHS IN THE
80S OVER WRN UPPER MI WHERE CLOUDS/PRECIP WILL MOVE IN EARLIER IN
THE DAY WITH THE FRONT. SBCAPES OF 2000-3500 J/KG SHOULD RESULT IN
THE WARM SECTOR...BUT 0-6KM WIND SHEAR IS ONLY 20-30KTS AND ALMOST
COMPLETELY UNIDIRECTIONAL. DCAPE VALUES AROUND 1000 J/KG ARE
POSSIBLE...HIGHEST OVER SCENTRAL UPPER MI. WITH ALL THIS IN
MIND...WIND SHEAR LOOKS TO BE THE LIMITING FACTOR FOR SEVERE
STORMS...BUT WITH THE CAPE AND DCAPE SO HIGH...EXPECT ISOLATED TO
SCATTERED SEVERE STORMS IN PRIMARILY MULTICELL STORM CLUSTER/S WITH
A LIMITED POSSIBILITY OF SUPERCELL THUNDERSTORMS /ESPECIALLY ALONG
LAKE BREEZE BOUNDARIES/. GREATEST THREAT STILL LOOKS LIKE DAMAGING
WINDS...WITH ONLY AN ISOLATED SEVERE HAIL THREAT DUE TO THE FREEZING
LEVEL BEING AROUND 12KFT.
CONVECTION SHOULD EXIT E/SE BY AROUND 06Z-09Z THU...WITH SFC HIGH
PRESSURE QUICKLY FILLING IN BEHIND THE TROUGH. THIS WILL RESULT IN
SOME LOCATIONS OVER WRN UPPER MI BEING ABLE TO FALL TO AROUND 50F
FOR LOWS LATE WED NIGHT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 AM EDT WED AUG 21 2013
MAIN FCST CONCERNS IN THE LONGER TERM ARE TEMPS ON THU/FRI WITH DRY
HI PRES DOMINATING. FOCUS FOR THE WEEKEND INTO EARLY NEXT WEEK ALSO
INCLUDES SHRA/TS CHCS AS A MORE ACTIVE SUMMER-LIKE PATTERN EVOLVES
OVER THE UPR LKS ON THE SRN EDGE OF ZONAL FLOW IN SRN CANADA AND N
OF STRONG RDG IN THE CONUS.
THU...ARRIVAL OF VIGOROUS DNVA/DEEP LYR QVECTOR DVGC UNDER CONFLUENT
UPR FLOW/MUCH DRIER AIR WITH PWAT FCST ARND 0.5 INCH /OR 50 PCT OF
NORMAL/ IN THE WAKE OF SHRTWV PASSAGE EARLY IN THE DAY WL BRING
MOSUNNY WX TO THE CWA ON THU. THE DAY WL ALSO BE MUCH COOLER DESPITE
BRIGHT SUNSHINE WITH H85 TEMPS PROGGED TO BE WITHIN A DEGREE OR 2 OF
10C.
THU NGT...ALTHOUGH SOME OF THE MODELS SHOW ANOTHER SHRTWV DROPPING
SEWD THRU THE GRT LKS IN THE NW FLOW ALF...THIS DISTURBANCE WL HAVE
LTL IMPACT DUE TO THE DRYNESS OF THE AIRMASS AND LARGER SCALE ACYC
FLOW ASSOCIATED WITH SFC HI CENTERED OVER THE AREA. THERE COULD BE
SOME PATCHY CLDS OVER MANLY THE NE HALF OF THE CWA CLOSER TO THE
TRACK OF THIS FEATURE...BUT OVERALL LGT WINDS/PWAT STILL 0.50-0.75
INCH WL ALLOW FOR A HEALTHY DIURNAL TEMP FALL WELL INTO THE 40S AT
THE COOLER INTERIOR LOCATIONS.
FRI...AS THE UPR RDG AXIS SHIFTS E INTO THE WRN GRT LKS AND DEEP LYR
QVECTOR DVGC/DRY AIR DOMINATE...EXPECT MOSUNNY SKIES. THE DAY SHOULD
ALSO TURN A BIT WARMER WITH LARGE SCALE SUBSIDENCE/RETURN SLY FLOW
ON THE WRN FLANK OF SFC HI PRES SHIFTING OVER LOWER MI LIFTING H85
TEMPS UP NEAR 15C OVER THE W BY 00Z SAT. LK BREEZES THAT DVLP NEAR
LK MI AND LK SUP E OF THE KEWEENAW UNDER THE WEAKER PRES GRADIENT
CLOSER TO THE DEPARTING SFC HI PRES WL ALLOW FOR SOME COOLING NEAR
THE LK SHORES IN THOSE AREAS.
FRI NGT...STRENGTHENING SSW WIND ON THE WRN FLANK OF SLOWLY
DEPARTING SFC HI PRES WL LIMIT NOCTURNAL COOLING...ESPECIALLY NEAR
LK SUP OVER THE W HALF WHERE THE STRONGER S WIND UNDER SHARPEST PRES
GRADIENT WL DOWNSLOPE AND SOME HI CLDS SPILLING OVER THE SLOWLY
APRCHG UPR RDG AXIS WL ARRIVE THRU THE NGT. EXPECT THE COOLEST
OVERNGT LO TEMPS ACROSS THE INTERIOR CENTRAL AND E.
THIS WEEKEND...UPR RDG IN THE PLAINS IS PROGGED TO BUILD INTO THE
UPR LKS IN WAD PATTERN/SSW FLOW BTWN HI PRES DRIFTING INTO THE MID
ATLANTIC STATES AND LOWER PRES IN CENTRAL CANADA. A NUMBER OF THE
EXTENDED MODELS SHOW H85 TEMPS NEARING 20C AND PWAT REACHING 1.50 TO
1.75 INCHES BY SUN...SO THE WX WL TURN WARMER AND MORE HUMID.
WHETHER SHRTWVS RIDING THRU THE ZONAL FLOW ON THE TOP OF THIS UPR
RDG WL INTERACT WITH THE INCRSGLY UNSTABLE AIRMASS AND GENERATE
SHRA/TS IS A SGNFT FCST CONCERN. SUSPECT THE BEST SHOT AT SHRA/TS WL
BE SAT NGT/SUN FOLLOWING DEPARTURE OF DRY AIRMASS AND OVER THE NRN
TIER CLOSER TO THE SHRTWVS TRACKING THRU ONTARIO AND LOWER HGTS.
EXTENDED...THE CWA IS FCST TO REMAIN NEAR THE SRN FLANK OF ZONAL
FLOW OVER SRN CANADA AND ON TOP OF UPR RDG DOMINATING THE CONUS.
THIS SUMMER-LIKE PATTERN WITH RECENT ECMWF/GFS RUNS SHOWING H85
TEMPS NEAR 20C IN VCNTY OF A STNRY FNT IS ONE THAT FAVORS EPISODES
OF SHRA WITH HEAVY RA/PERHAPS SVR TSRA ACCOMPANYING THE PASSAGE OF
SHRTWVS THRU THE UPR LKS/ONTARIO NEAR EDGE OF CAPPING INVRN
ASSOCIATED WITH THE STRONG RDG TO THE S. SPECIFYING THE DAY-TO-DAY
DETAILS IN THIS PATTERN IS IMPOSSIBLE ATTM...SO WL STICK TO THE
CONSENSUS FCST. THE CURRENT CPC DAY 3-7 OUTLOOK DOES INDICATE A
THREAT OF HEAVY RA FOR UPR MI OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. TEMPS WL BE ABV NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 731 AM EDT WED AUG 21 2013
EXPECT VFR CONDITIONS AT ALL 3 TAF SITES DESPITE THE CHANCE FOR
SHRA/TSRA THIS AFTERNOON/EVENING WITH THE PASSAGE OF A COLD FRONT.
EXPECT TSRA/SHRA EARLY THIS AFTERNOON AT KIWD AND KCMX WITH A BETTER
CHANCE LATE THIS AFTERNOON/EARLY EVENING AT KSAW WITH THE FRONTAL
PASSAGE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 250 AM EDT WED AUG 21 2013
OVERALL...EXPECT STRONGEST WINDS /TO AROUND 20KTS/ OVER THE NEXT FEW
DAYS TO BE EARLY THIS MORNING INTO TODAY AS THE PRESSURE GRADIENT
TIGHTENS UP AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH LATE THIS
MORNING INTO THIS EVENING...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR
THE COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE THIS AFTERNOON AND EVENING
FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
ANOTHER PERIOD OF STRONGER WINDS /FROM THE SW/ MAY OCCUR ON
SATURDAY NIGHT INTO SUNDAY AS LAKE SUPERIOR SITS BETWEEN A HIGH
PRESSURE SYSTEM TO THE SE AND A TROUGH OF LOW PRESSURE TO THE NW...
BUT HIGH OVERWATER STABILITY WILL REMAIN A LIMITING FACTOR ON HOW
STRONG THE NEAR SURFACE WINDS WILL BECOME.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
131 AM EDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL
FLOW ACROSS SRN CANADA AND THE NRN CONUS ATOP RIDING OVER THE PLAINS
AND A CUTOFF LOW NEAR KSTL. THE MAIN UPSTREAM SHORTWAVE TROUGH WAS
LOCATED WELL UPSTREAM...FROM SASK INTO ERN ALBERTA. AT THE SFC...SW
FLOW PREVAILED THROUGH THE WRN GREAT LAKES BTWN HIGH PRES OVER THE
ERN OH VALLEY AND A TROUGH FROM NW ONTARIO INTO CNTRL ND. A COLD
FRONT EXTENDED FROM NEAR WINNIPEG INTO SRN SASK. ALTHOUGH VIS LOOP
SHOWED ABUNDANT CU ACROSS THE REGION AND A LAKE BREEZE BOUNDARY OFF
OF LAKE MI...CAPPING EVIDENT ON AREA SOUNDINGS WITH 800-700 MB TEMPS
AROUND 13C HAS SUPPRESSED ANY CONVECTION THAT WOULD PRODUCE ANY
SHRA/TSRA.
TONIGHT...AS THE ALBERTA/SASK MOVES INTO MANITOBA AND THE PLAINS
TROUGH SLIDES TO THE EAST THE STRONGEST LOW LEVEL MOISTURE
ADVECTION...FOCUS OF THE LOW LEVEL JET...AND 310K ISENTROPIC LIFT
THROUGH THE 850-700 MB FRONT WILL REMAIN JUST NORTH OF LAKE SUPERIOR
BUT MAY BRUSH THE NRN PORTION OF THE LAKE. OTHERWISE...THE PERSISTENT
SW FLOW THROUGH THE WRN LAKES WILL KEEP TEMPS WELL ABOVE
NORMAL...ESPECIALLY FOR DOWNSLOPE LOCATIONS NEAR LAKE SUPERIOR. MIN
READINGS IN THE MID 60S TO LOWER 70S...NEAR THE HIGHER END OF
GUIDANCE ARE EXPECTED.
WED...AS THE SHRTWV MOVES THROUGH NRN ONTARIO IT WILL DRAG THE COLD
FRONT THROUGH LAKE SUPERIOR AND UPPER MI. THE COMBINATION OF LOW
LEVEL CONV ALONG THE FRONT...REINFORCED BY THE LAKE SUPERIOR
BREEZE...AND WEAK TO MODERATE MID LEVEL QVECTOR CONV WITH THE TAIL
OF THE SHRTWV SHOULD TRIGGER TSRA OVER WEST UPPER MI IN THE EARLY
AFTERNOON WHICH WILL SPREAD INTO THE CNTRL CWA BY MID AND LATE
AFTERNOON. DEWPOINTS INTO THE UPPER 60S AND TEMPS IN THE UPPER 80S
WILL RESULT IN MLCAPE VALUES INTO THE 2K-3K J/KG RANGE. THE STRONG
INSTABILITY(BY U.P. STANDARDS) ALONG WITH 0-6KM SHEAR TO AROUND 30
KT WILL BE ENOUGH TO SUPPORT MULTICELL CLUSTERS WITH SOME SEVERE
THUNDERSTORMS. WITH DCAPE VALUES OF 1K J/KG...DAMAGING WINDS WILL BE
THE MAIN THREAT. SOME ISOLATED LARGE HAIL MAY ALSO BE POSSIBLE WITH
THE STRONGEST STORMS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
COLD FRONT AND ASSOCIATED SHOWERS/THUNDERSTORMS WILL BE MOVING
SOUTHEAST ACROSS CENTRAL AND EASTERN UPPER MICHIGAN AT THE
START OF THE LONG TERM PERIOD. EXPECT THESE STRONG TO POTENTIALLY
SEVERE THUNDERSTORMS TO BE SLIDING EAST-SOUTHEAST ACROSS THOSE AREAS
DURING THE EVENING HOURS AND BE MOVING INTO LAKE MICHIGAN TOWARDS
MIDNIGHT OR THE EARLY OVERNIGHT HOURS. 12Z MODELS TODAY SEEM TO BE
A LITTLE SLOWER WITH THE FRONTAL PASSAGE THAN YESTERDAY...SO WILL
FOLLOW THE IDEA OF THE MID SHIFT WITH THE TIMING.
A SHORTWAVE DIVING SOUTHEAST FROM LAKE WINNIPEG WEDNESDAY NIGHT
WILL CROSS THE U.P. ON THURSDAY MORNING. WITH THE DRY AIR AND
HIGH PRESSURE THAT ARRIVES BEHIND THE COLD FRONT...SHOULDN/T SEE
MUCH INFLUENCE FROM THE SHORTWAVE ON THE WEATHER AND EXPECT MOSTLY
SUNNY SKIES. HIGHS THURSDAY WILL BE MUCH COOLER (BY 10-15
DEGREES) THAN WEDNESDAY WITH THE NORTHERLY WINDS OFF LAKE SUPERIOR.
FORTUNATELY...MOST AREAS WILL SEE RAIN TOMORROW...OTHERWISE THERE
COULD BE AN ELEVATED FIRE WX RISK WITH NORTH WINDS OF 10-20MPH AND
RH VALUES FALLING TOWARDS 30 PERCENT.
ANOTHER SHORTWAVE ROUNDING THE UPPER RIDGE IN CENTRAL CANADA WILL
DIVE SOUTHEAST ACROSS THE EASTERN CWA ON FRIDAY. AT THIS
TIME...WOULD EXPECT SOME INCREASE IN CLOUD COVER BASED OFF
925-850MB MOISTURE AND DIURNAL HEATING OVER THE EASTERN PART OF THE
CWA (MAINLY FROM MARQUETTE/DICKINSON COUNTIES AND EAST). WON/T GO
TOO HIGH ON CLOUD COVER...BUT AT LEAST GIVE A PERIOD OF PARTLY
CLOUDY SKIES OVER THE EAST AS THAT MOISTURE MOVES THROUGH.
UPPER RIDGE THAT WAS OVER THE NORTHERN PLAINS AND CENTRAL CANADA
WILL THEN SHIFT EAST ON FRIDAY NIGHT WITH THE AXIS OF THE RIDGE
OVER UPPER MICHIGAN BY 12Z SATURDAY. THIS MOVEMENT OF THE RIDGE
WILL ALSO SLIDE THE SURFACE HIGH EAST OF THE AREA AND ALLOW
SOUTHERLY FLOW AND GRADUALLY WARMING TEMPERATURES TO RETURN. MODELS
ARE STILL STRUGGLING TO COME UP WITH A CONSENSUS ON THE SERIES OF
SHORTWAVES MOVING INTO THE UPPER RIDGE AND GRADUALLY BREAKING IT
DOWN FROM SATURDAY AFTERNOON THROUGH THE FIRST HALF OF NEXT WEEK.
THE FIRST WAVE WILL MOVE THROUGH THE AREA SATURDAY AFTERNOON AND
NIGHT (OVER THE NORTH HALF OF THE CWA) AND THE NEXT ONE LATE SUNDAY
AFTERNOON INTO MONDAY MORNING. THE DISCREPANCIES GROW FURTHER ON
MONDAY NIGHT INTO TUESDAY...WITH GFS BRINGING ANOTHER SHORTWAVE
THROUGH ON TUESDAY WHILE THE ECMWF/GEM HAS HIGH PRESSURE OVER THE
AREA. THESE PERIODS OF SHOWERS/THUNDERSTORMS ALSO LEADS TO
UNCERTAINTY WITH HIGHS BUT SHOULD AT LEAST BE ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 130 AM EDT WED AUG 21 2013
EXPECT VFR CONDITIONS AT ALL 3 TAF SITES DESPITE THE CHANCE FOR
SHRA/TSRA WED AFTERNOON/EVENING WITH THE PASSAGE OF A COLD FRONT.
LLWS SHOULD CONTINUE OVERNIGHT WITH STRENGTHENING NOCTURNAL SW LOW
LEVEL JET UNDER A SHARPENING PRES GRADIENT AHEAD OF APPROACHING COLD
FRONT. EXPECT SHRA AND POSSIBLE TSRA EARLY WED AFTERNOON AT KIWD AND
KCMX WITH A BETTER CHANCE LATE WED AFTERNOON/EARLY EVENING AT KSAW
WITH THE FRONTAL PASSAGE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 416 PM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS THE PRES GRADIENT TIGHTENS AHEAD OF THE
APPROACHING COLD FRONT...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE
COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE WED AFTN AND EVENING FOLLOWING A
COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1248 PM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT WED AUG 21 2013
SATELLITE AND LIGHTNING SUGGEST A DISTURBANCE ACROSS NERN UT/NWRN
COLO THIS MORNING. THIS DISTURBANCE SHOULD FIRE OFF THE LARAMIE
RANGE AROUND 18Z MARKING THE START OF CONVECTION LATER THIS
AFTERNOON ACROSS WRN AND EVENTUALLY NCNTL NEB TONIGHT. THE RAP
MODEL SHOWS A TSTM COMPLEX DEVELOPING OFF THE PINE RIDGE AROUND
19Z AND THE HRRR IS VERY BUSY ACROSS THE NEB PANHANDLE AT 20Z. IT
ALSO INDICATES STORM INTENSIFICATION ACROSS HOLT COUNTY IN THE
DEEP MOISTURE SECTOR.
GIVEN THAT THE MODELS ARE SHOWING PRECIPITABLE WATER INCREASING
TO AROUND 1.75 INCHES EAST OF HIGHWAY 83 TONIGHT AND THAT WEAK
WINDS ALOFT WILL PRODUCE STORM MOTION OF 10 KTS OR LESS...LOCALLY
HEAVY RAIN SHOULD DEVELOP IN THIS AREA OF RICH MOISTURE.
ELSEWHERE STORM ACTIVITY SHOULD BE SCATTERED OR LESS. NOTE THAT A
MIDLEVEL COLD FRONT IS OPERATING THIS MORNING ACROSS NRN NEB
WHICH WOULD ACTIVATE SCATTERED CONVECTION EARLY THIS AFTERNOON IN
RESPONSE TO DAYTIME HEATING. A STATIONARY FRONT...CURRENTLY
ACROSS SRN SD SHOULD DRIFT SOUTH INTO NRN NEB AT THE SAME TIME
WITH LOW LEVEL MOISTURE POOLING ALONG THE FRONT ADDING FOCUS TO
THE RAIN EVENT.
WINDS ALOFT ARE WEAK AT 35 KTS OR LESS WHICH WILL LIMIT SEVERE
WEATHER POTENTIAL TO ISOLATED COVERAGE. SCATTERED LIGHT SHOWERS
SHOULD CONTINUE THIS MORNING ALONG THE MID LEVEL FRONT ACROSS NRN
NEB WHICH WOULD THEN INTENSIFY TO THUNDERSTORMS EARLY THIS
AFTERNOON AND PERHAPS APPROACH SEVERE LIMITS LATE THIS AFTERNOON
AS THE DISTURBANCE APPROACHES.
MOISTURE TRANSPORT VECTORS ARE RELATIVELY WEAK THIS AFTERNOON AND
THIS EVENING WHICH WOULD LIMIT THE OVERALL HEAVY RAIN THREAT.
STILL ALL THE GFS ENSEMBLE MEMBERS SHOW A HEAVY RAIN CENTER
DEVELOPING ACROSS NCNTL NEB TONIGHT...LIKELY A RESULT OF THE LOW
LEVEL JET INCREASING TO AROUND 30 KT. NONE OF THE OTHER MODELS
SHOW THIS. THE GEMREG IS THE CLOSEST BUT HAS THE FRONT AND HEAVY
RAIN ACROSS SERN SD WHILE THE NAM AND ECM ARE VERY MODEST WITH
QPF BUT SHOW NCNTL NEB LIKE THE GFS ENSEMBLE.
HIGHS TODAY RANGE FROM THE LOWER 80S NORTH TO MID 90S SOUTH.
EXTENSIVE MID AND HIGH LEVEL CLOUDINESS WILL LIMIT HIGHS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 330 AM CDT WED AUG 21 2013
MAIN CONCERNS WITH THE LONG TERM FOCUS WITH THUNDERSTORM CHANCES
EARLY ON...THEN TRANSITION INTO TEMPERATURES BY THE WEEKEND INTO
NEXT WEEK.
UPPER LEVEL RIDGE WILL BUILD EAST FROM THE SOUTHERN/CENTRAL
ROCKIES OVER THE CENTRAL PLAINS BY THE WEEKEND. MEANWHILE A WEAK
COLD FRONT WILL DRIFT SOUTH ACROSS THE STATE...THEN BECOMES
REPLACED BY A HIGH PRESSURE BUILDING OVER THE UPPER MISS RVR
VALLEY AND THE GREAT LAKES. A SFC LEE TROUGH DEVELOPS ALONG THE
FRONT...AND REMAINS QUASI-STATIONARY THROUGH THE WEEKEND.
THUNDERSTORM CHANCES INITIALLY ON THURSDAY...GENERALLY
ALONG/NORTH OF THE FRONT...WHERE STEEPER LAPSE RATE PERSIST. ALSO
GOING TO BE ALONG THE NORTHERN SIDE OF THE DEVELOPING RIDGE...AND
ASSOCIATED WITH A MID LEVEL DISTURBANCE. AS THE SHORT WAVE PUSHES
EAST...CHANCE FOR STORMS DIMINISHES THURSDAY NIGHT. THE NEXT
CHANCE FOR STORMS IS ALONG THE HIGHER TERRAIN AND THE LEE SIDE
TROUGH GENERALLY TO THE WEST OF THE CWA. MODELS BRING ANOTHER
DISTURBANCE ACROSS THE ROCKIES SATURDAY WHICH HAS THE POTENTIAL TO
SUSTAIN ACTIVITY INTO THE WESTERN ZONES...AND WILL HAVE SOME LOW
POPS. OTHERWISE RIDGE WILL BRING DRY CONDITIONS.
TEMPERATURES ON THURSDAY ARE EXPECTED TO BE COOL WITH SOME CLOUDS
AND COOLER AIR FROM THE COLD FRONT. 00Z MODEL GUIDANCE HAS COME
IN SEVERAL DEGREE ABOVE THE 12Z RUN...HOWEVER FORECAST DOES NOT
JUMP AS FAR AS GUIDANCE YET...AS EXPECT THE CLOUDS TO KEEP TEMPS
IN THE LOWER TO MID 80S. BY FRIDAY THE WARM UP BEGINS...AS HIGH
RETURN TO WELL ABOVE NORMAL 90S FOR THE WEEKEND AND TO START NEXT
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1242 PM CDT WED AUG 21 2013
A COLD FRONT WILL REMAIN NEARLY STATIONARY FROM NEAR KONL TO KOGA
THIS AFTERNOON. SCT TSTMS ARE EXPECTED TO DEVELOP ALONG AND NEAR
THE FRONT BY LATE AFTERNOON. TSTM COVERAGE WILL INCREASE THIS
EVENING AS A 45 KT SOUTHERLY LOW LEVEL JET NOSES INTO THE AREA
FROM WESTERN KS. THE MOST CONCENTRATED AREA FOR STORMS THIS
EVENING WILL EXTEND ALONG A LINE FROM KONL TO KBBW TO KLBF.
OUTSIDE OF ANY TSTM ACTIVITY...VFR CONDITIONS SHOULD RULE. SFC
WINDS WILL BE NORTHEAST AT 5 TO 10 KTS TO THE NORTH OF THE
FRONT...WITH SOUTHEAST WINDS 5 TO 10 KTS AHEAD OF THE FRONT.
VRB AND GUSTY WINDS WILL BE ENCOUNTERED NEAR ANY TSTM ACTIVITY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1244 PM CDT WED AUG 21 2013
.AVIATION...18Z TAFS FOR KOFK...KLNK AND KOMA.
VFR CONDITIONS ARE EXPECTED INTO THE LATE AFTERNOON AND EVENING
AS SOUTH WINDS AROUND 15KT AND SCT/BKN MID/HIGH LEVEL CLOUDS MOVE
ALONG THE NEBRASKA SOUTH DAKOTA BORDER INTO NORTHWEST IOWA. A
COLD FRONT CONTINUES TO SLOWLY DROP INTO NORTHERN NEBRASKA AND
NORTHWEST IOWA...AND WILL APPROACH KOFK BY 04Z. SCATTERED SHOWERS
AND THUNDERSTORMS ARE POSSIBLE ALONG THE FRONT...AFFECTING KOFK
FROM 04Z THROUGH 08Z...AND THE KLNK AND KOMA AREAS AFTER 06Z.
ISOLATED SEVERE THUNDERSTORMS...PRIMARILY IN THE KOFK
AREA...COULD BE POSSIBLE. ATTENDANT MVFR/IFR CONDITIONS COULD
OCCUR IN ANY THUNDERSTORM. SHOWERS AND STORMS WILL LIKELY REMAIN
IN THE AREA INTO THE 14Z TO 16Z TIME PERIOD.
&&
.PREV DISCUSSION... /ISSUED 300 AM CDT WED AUG 21 2013/
DISCUSSION...
TEMPERATURES THROUGH THE PERIOD AND RAIN CHANCES LATE TODAY INTO
FRIDAY WILL BE THE MAIN FORECAST CONCERNS.
WV/IR SATELLITE LOOP SHOWS A PULSING AREA OF CONVECTION FROM
SOUTHEAST SOUTH DAKOTA INTO NORTHWEST NEBRASKA AT 07Z IN ADVANCE
OF A WEAK SURFACE COLD FRONT FROM NORTHWEST MINNESOTA INTO FAR
NORTHWEST NEBRASKA. 00Z MODELS SIMILAR IN PLACING ISOLATED TO
WIDELY SCATTERED CONVECTION IN THE VICINITY OF THE FRONT TODAY AND
ESPECIALLY LATE THIS AFTERNOON AS IT WORKS INTO NORTHERN PORTIONS
OF IOWA AND NEBRASKA WITH RAP FORECAST SOUNDINGS SHOWING LITTLE
CAP IN PLACE. CONVECTION LIKELY TO EXPAND DURING THE EVENING AS
LOW LEVEL JET FEEDS INTO THE COMPLEX. SURFACE FRONT STALLS NEAR
THE SOUTHERN NEBRASKA BORDER BY THURSDAY MORNING THEN BEGINS TO
LIFT BACK NORTH DURING THE DAY WITH A CONTINUED CHANCE OF SHOWERS
AND THUNDERSTORMS NORTH AND EAST OF THE BOUNDARY INTO FRIDAY.
SOME COOLING ON THURSDAY...ESPECIALLY NORTH...ASSOCIATED WITH
CLOUDS AND PRECIP BEFORE THE WARM AIR WORKS BACK INTO THE AREA
ON FRIDAY.
EXTENDED PERIOD STILL HOT AND DRY WITH UPPER LEVEL HIGH PRESSURE
CENTERED OVER THE CENTRAL PART OF THE NATION.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
630 AM CDT WED AUG 21 2013
.AVIATION...12Z TAFS FOR KOFK...KLNK AND KOMA.
VFR CONDITIONS ARE EXPECTED INTO THE EVENING AS SOUTH WINDS NEAR
15KT AND SCT/BKN MID/HIGH LEVEL CLOUDS MOVE OVER EASTERN NEBRASKA.
A COLD FRONT WILL BE MOVING INTO NORTHEAST NEBRASKA LATE IN THE
DAY...AND WILL APPROACH KOFK BY 04Z. SCATTERED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ALONG THE FRONT...AFFECTING KOFK FROM
04Z THROUGH THE END OF THE TAF PERIOD...AND THE KLNK AND KOMA
AREAS AFTER 06Z. ATTENDANT MVFR/IFR CONDITIONS COULD OCCUR IN ANY
THUNDERSTORM. SHOWERS AND STORMS WILL LIKELY REMAIN IN THE AREA
THROUGH AT LEAST MIDDAY ON THURSDAY.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 300 AM CDT WED AUG 21 2013/
DISCUSSION...
TEMPERATURES THROUGH THE PERIOD AND RAIN CHANCES LATE TODAY INTO
FRIDAY WILL BE THE MAIN FORECAST CONCERNS.
WV/IR SATELLITE LOOP SHOWS A PULSING AREA OF CONVECTION FROM
SOUTHEAST SOUTH DAKOTA INTO NORTHWEST NEBRASKA AT 07Z IN ADVANCE
OF A WEAK SURFACE COLD FRONT FROM NORTHWEST MINNESOTA INTO FAR
NORTHWEST NEBRASKA. 00Z MODELS SIMILAR IN PLACING ISOLATED TO
WIDELY SCATTERED CONVECTION IN THE VICINITY OF THE FRONT TODAY AND
ESPECIALLY LATE THIS AFTERNOON AS IT WORKS INTO NORTHERN PORTIONS
OF IOWA AND NEBRASKA WITH RAP FORECAST SOUNDINGS SHOWING LITTLE
CAP IN PLACE. CONVECTION LIKELY TO EXPAND DURING THE EVENING AS
LOW LEVEL JET FEEDS INTO THE COMPLEX. SURFACE FRONT STALLS NEAR
THE SOUTHERN NEBRASKA BORDER BY THURSDAY MORNING THEN BEGINS TO
LIFT BACK NORTH DURING THE DAY WITH A CONTINUED CHANCE OF SHOWERS
AND THUNDERSTORMS NORTH AND EAST OF THE BOUNDARY INTO FRIDAY.
SOME COOLING ON THURSDAY...ESPECIALLY NORTH...ASSOCIATED WITH
CLOUDS AND PRECIP BEFORE THE WARM AIR WORKS BACK INTO THE AREA
ON FRIDAY.
EXTENDED PERIOD STILL HOT AND DRY WITH UPPER LEVEL HIGH PRESSURE
CENTERED OVER THE CENTRAL PART OF THE NATION.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
624 AM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT WED AUG 21 2013
SATELLITE AND LIGHTNING SUGGEST A DISTURBANCE ACROSS NERN UT/NWRN
COLO THIS MORNING. THIS DISTURBANCE SHOULD FIRE OFF THE LARAMIE
RANGE AROUND 18Z MARKING THE START OF CONVECTION LATER THIS
AFTERNOON ACROSS WRN AND EVENTUALLY NCNTL NEB TONIGHT. THE RAP
MODEL SHOWS A TSTM COMPLEX DEVELOPING OFF THE PINE RIDGE AROUND
19Z AND THE HRRR IS VERY BUSY ACROSS THE NEB PANHANDLE AT 20Z. IT
ALSO INDICATES STORM INTENSIFICATION ACROSS HOLT COUNTY IN THE
DEEP MOISTURE SECTOR.
GIVEN THAT THE MODELS ARE SHOWING PRECIPITABLE WATER INCREASING
TO AROUND 1.75 INCHES EAST OF HIGHWAY 83 TONIGHT AND THAT WEAK
WINDS ALOFT WILL PRODUCE STORM MOTION OF 10 KTS OR LESS...LOCALLY
HEAVY RAIN SHOULD DEVELOP IN THIS AREA OF RICH MOISTURE.
ELSEWHERE STORM ACTIVITY SHOULD BE SCATTERED OR LESS. NOTE THAT A
MIDLEVEL COLD FRONT IS OPERATING THIS MORNING ACROSS NRN NEB
WHICH WOULD ACTIVATE SCATTERED CONVECTION EARLY THIS AFTERNOON IN
RESPONSE TO DAYTIME HEATING. A STATIONARY FRONT...CURRENTLY
ACROSS SRN SD SHOULD DRIFT SOUTH INTO NRN NEB AT THE SAME TIME
WITH LOW LEVEL MOISTURE POOLING ALONG THE FRONT ADDING FOCUS TO
THE RAIN EVENT.
WINDS ALOFT ARE WEAK AT 35 KTS OR LESS WHICH WILL LIMIT SEVERE
WEATHER POTENTIAL TO ISOLATED COVERAGE. SCATTERED LIGHT SHOWERS
SHOULD CONTINUE THIS MORNING ALONG THE MID LEVEL FRONT ACROSS NRN
NEB WHICH WOULD THEN INTENSIFY TO THUNDERSTORMS EARLY THIS
AFTERNOON AND PERHAPS APPROACH SEVERE LIMITS LATE THIS AFTERNOON
AS THE DISTURBANCE APPROACHES.
MOISTURE TRANSPORT VECTORS ARE RELATIVELY WEAK THIS AFTERNOON AND
THIS EVENING WHICH WOULD LIMIT THE OVERALL HEAVY RAIN THREAT.
STILL ALL THE GFS ENSEMBLE MEMBERS SHOW A HEAVY RAIN CENTER
DEVELOPING ACROSS NCNTL NEB TONIGHT...LIKELY A RESULT OF THE LOW
LEVEL JET INCREASING TO AROUND 30 KT. NONE OF THE OTHER MODELS
SHOW THIS. THE GEMREG IS THE CLOSEST BUT HAS THE FRONT AND HEAVY
RAIN ACROSS SERN SD WHILE THE NAM AND ECM ARE VERY MODEST WITH
QPF BUT SHOW NCNTL NEB LIKE THE GFS ENSEMBLE.
HIGHS TODAY RANGE FROM THE LOWER 80S NORTH TO MID 90S SOUTH.
EXTENSIVE MID AND HIGH LEVEL CLOUDINESS WILL LIMIT HIGHS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 330 AM CDT WED AUG 21 2013
MAIN CONCERNS WITH THE LONG TERM FOCUS WITH THUNDERSTORM CHANCES
EARLY ON...THEN TRANSITION INTO TEMPERATURES BY THE WEEKEND INTO
NEXT WEEK.
UPPER LEVEL RIDGE WILL BUILD EAST FROM THE SOUTHERN/CENTRAL
ROCKIES OVER THE CENTRAL PLAINS BY THE WEEKEND. MEANWHILE A WEAK
COLD FRONT WILL DRIFT SOUTH ACROSS THE STATE...THEN BECOMES
REPLACED BY A HIGH PRESSURE BUILDING OVER THE UPPER MISS RVR
VALLEY AND THE GREAT LAKES. A SFC LEE TROUGH DEVELOPS ALONG THE
FRONT...AND REMAINS QUASI-STATIONARY THROUGH THE WEEKEND.
THUNDERSTORM CHANCES INITIALLY ON THURSDAY...GENERALLY
ALONG/NORTH OF THE FRONT...WHERE STEEPER LAPSE RATE PERSIST. ALSO
GOING TO BE ALONG THE NORTHERN SIDE OF THE DEVELOPING RIDGE...AND
ASSOCIATED WITH A MID LEVEL DISTURBANCE. AS THE SHORT WAVE PUSHES
EAST...CHANCE FOR STORMS DIMINISHES THURSDAY NIGHT. THE NEXT
CHANCE FOR STORMS IS ALONG THE HIGHER TERRAIN AND THE LEE SIDE
TROUGH GENERALLY TO THE WEST OF THE CWA. MODELS BRING ANOTHER
DISTURBANCE ACROSS THE ROCKIES SATURDAY WHICH HAS THE POTENTIAL TO
SUSTAIN ACTIVITY INTO THE WESTERN ZONES...AND WILL HAVE SOME LOW
POPS. OTHERWISE RIDGE WILL BRING DRY CONDITIONS.
TEMPERATURES ON THURSDAY ARE EXPECTED TO BE COOL WITH SOME CLOUDS
AND COOLER AIR FROM THE COLD FRONT. 00Z MODEL GUIDANCE HAS COME
IN SEVERAL DEGREE ABOVE THE 12Z RUN...HOWEVER FORECAST DOES NOT
JUMP AS FAR AS GUIDANCE YET...AS EXPECT THE CLOUDS TO KEEP TEMPS
IN THE LOWER TO MID 80S. BY FRIDAY THE WARM UP BEGINS...AS HIGH
RETURN TO WELL ABOVE NORMAL 90S FOR THE WEEKEND AND TO START NEXT
WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 620 AM CDT WED AUG 21 2013
THERE IS NO CHANGE TO THE FORECAST THINKING THROUGH 06Z TONIGHT.
SCATTERED TO OCCASIONALLY NUMEROUS TSTMS ARE EXPECTED TO DEVELOP
FROM ROUGHLY 21Z THIS AFTN ONWARD THROUGH 06Z TONIGHT. MOST OF THE
TSTM ACTIVITY SHOULD BE LOCATED EAST OF HIGHWAY 83 WITH COVERAGE
DECREASING WESTWARD. OTHERWISE VFR IS EXPECTED WITH MID AND HIGH
LEVEL CLOUDINESS.
AFTER 06Z...THE LATEST MODEL GUIDANCE SUGGESTS STORM ACTIVITY WILL
BECOME ISOLATED WEST OF HIGHWAY 83 BUT CONTINUE IN ERNEST EAST OF
HIGHWAY 83.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
331 AM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT WED AUG 21 2013
SATELLITE AND LIGHTNING SUGGEST A DISTURBANCE ACROSS NERN UT/NWRN
COLO THIS MORNING. THIS DISTURBANCE SHOULD FIRE OFF THE LARAMIE
RANGE AROUND 18Z MARKING THE START OF CONVECTION LATER THIS
AFTERNOON ACROSS WRN AND EVENTUALLY NCNTL NEB TONIGHT. THE RAP
MODEL SHOWS A TSTM COMPLEX DEVELOPING OFF THE PINE RIDGE AROUND
19Z AND THE HRRR IS VERY BUSY ACROSS THE NEB PANHANDLE AT 20Z. IT
ALSO INDICATES STORM INTENSIFICATION ACROSS HOLT COUNTY IN THE
DEEP MOISTURE SECTOR.
GIVEN THAT THE MODELS ARE SHOWING PRECIPITABLE WATER INCREASING
TO AROUND 1.75 INCHES EAST OF HIGHWAY 83 TONIGHT AND THAT WEAK
WINDS ALOFT WILL PRODUCE STORM MOTION OF 10 KTS OR LESS...LOCALLY
HEAVY RAIN SHOULD DEVELOP IN THIS AREA OF RICH MOISTURE.
ELSEWHERE STORM ACTIVITY SHOULD BE SCATTERED OR LESS. NOTE THAT A
MIDLEVEL COLD FRONT IS OPERATING THIS MORNING ACROSS NRN NEB
WHICH WOULD ACTIVATE SCATTERED CONVECTION EARLY THIS AFTERNOON IN
RESPONSE TO DAYTIME HEATING. A STATIONARY FRONT...CURRENTLY
ACROSS SRN SD SHOULD DRIFT SOUTH INTO NRN NEB AT THE SAME TIME
WITH LOW LEVEL MOISTURE POOLING ALONG THE FRONT ADDING FOCUS TO
THE RAIN EVENT.
WINDS ALOFT ARE WEAK AT 35 KTS OR LESS WHICH WILL LIMIT SEVERE
WEATHER POTENTIAL TO ISOLATED COVERAGE. SCATTERED LIGHT SHOWERS
SHOULD CONTINUE THIS MORNING ALONG THE MID LEVEL FRONT ACROSS NRN
NEB WHICH WOULD THEN INTENSIFY TO THUNDERSTORMS EARLY THIS
AFTERNOON AND PERHAPS APPROACH SEVERE LIMITS LATE THIS AFTERNOON
AS THE DISTURBANCE APPROACHES.
MOISTURE TRANSPORT VECTORS ARE RELATIVELY WEAK THIS AFTERNOON AND
THIS EVENING WHICH WOULD LIMIT THE OVERALL HEAVY RAIN THREAT.
STILL ALL THE GFS ENSEMBLE MEMBERS SHOW A HEAVY RAIN CENTER
DEVELOPING ACROSS NCNTL NEB TONIGHT...LIKELY A RESULT OF THE LOW
LEVEL JET INCREASING TO AROUND 30 KT. NONE OF THE OTHER MODELS
SHOW THIS. THE GEMREG IS THE CLOSEST BUT HAS THE FRONT AND HEAVY
RAIN ACROSS SERN SD WHILE THE NAM AND ECM ARE VERY MODEST WITH
QPF BUT SHOW NCNTL NEB LIKE THE GFS ENSEMBLE.
HIGHS TODAY RANGE FROM THE LOWER 80S NORTH TO MID 90S SOUTH.
EXTENSIVE MID AND HIGH LEVEL CLOUDINESS WILL LIMIT HIGHS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 330 AM CDT WED AUG 21 2013
MAIN CONCERNS WITH THE LONG TERM FOCUS WITH THUNDERSTORM CHANCES
EARLY ON...THEN TRANSITION INTO TEMPERATURES BY THE WEEKEND INTO
NEXT WEEK.
UPPER LEVEL RIDGE WILL BUILD EAST FROM THE SOUTHERN/CENTRAL
ROCKIES OVER THE CENTRAL PLAINS BY THE WEEKEND. MEANWHILE A WEAK
COLD FRONT WILL DRIFT SOUTH ACROSS THE STATE...THEN BECOMES
REPLACED BY A HIGH PRESSURE BUILDING OVER THE UPPER MISS RVR
VALLEY AND THE GREAT LAKES. A SFC LEE TROUGH DEVELOPS ALONG THE
FRONT...AND REMAINS QUASI-STATIONARY THROUGH THE WEEKEND.
THUNDERSTORM CHANCES INITIALLY ON THURSDAY...GENERALLY
ALONG/NORTH OF THE FRONT...WHERE STEEPER LAPSE RATE PERSIST. ALSO
GOING TO BE ALONG THE NORTHERN SIDE OF THE DEVELOPING RIDGE...AND
ASSOCIATED WITH A MID LEVEL DISTURBANCE. AS THE SHORT WAVE PUSHES
EAST...CHANCE FOR STORMS DIMINISHES THURSDAY NIGHT. THE NEXT
CHANCE FOR STORMS IS ALONG THE HIGHER TERRAIN AND THE LEE SIDE
TROUGH GENERALLY TO THE WEST OF THE CWA. MODELS BRING ANOTHER
DISTURBANCE ACROSS THE ROCKIES SATURDAY WHICH HAS THE POTENTIAL TO
SUSTAIN ACTIVITY INTO THE WESTERN ZONES...AND WILL HAVE SOME LOW
POPS. OTHERWISE RIDGE WILL BRING DRY CONDITIONS.
TEMPERATURES ON THURSDAY ARE EXPECTED TO BE COOL WITH SOME CLOUDS
AND COOLER AIR FROM THE COLD FRONT. 00Z MODEL GUIDANCE HAS COME
IN SEVERAL DEGREE ABOVE THE 12Z RUN...HOWEVER FORECAST DOES NOT
JUMP AS FAR AS GUIDANCE YET...AS EXPECT THE CLOUDS TO KEEP TEMPS
IN THE LOWER TO MID 80S. BY FRIDAY THE WARM UP BEGINS...AS HIGH
RETURN TO WELL ABOVE NORMAL 90S FOR THE WEEKEND AND TO START NEXT
WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1223 AM CDT WED AUG 21 2013
SCATTERED TO OCCASIONALLY NUMEROUS TSTMS ARE EXPECTED TO DEVELOP
FROM ROUGHLY 21Z THIS AFTN ONWARD THROUGH 06Z TONIGHT. MOST OF
THE TSTM ACTIVITY SHOULD BE LOCATED EAST OF HIGHWAY 83 WITH
COVERAGE DECREASING WESTWARD. OTHERWISE VFR IS EXPECTED WITH MID
AND HIGH LEVEL CLOUDINESS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
300 AM CDT WED AUG 21 2013
.DISCUSSION...
TEMPERATURES THROUGH THE PERIOD AND RAIN CHANCES LATE TODAY INTO
FRIDAY WILL BE THE MAIN FORECAST CONCERNS.
WV/IR SATELLITE LOOP SHOWS A PULSING AREA OF CONVECTION FROM
SOUTHEAST SOUTH DAKOTA INTO NORTHWEST NEBRASKA AT 07Z IN ADVANCE
OF A WEAK SURFACE COLD FRONT FROM NORTHWEST MINNESOTA INTO FAR
NORTHWEST NEBRASKA. 00Z MODELS SIMILAR IN PLACING ISOLATED TO
WIDELY SCATTERED CONVECTION IN THE VICINITY OF THE FRONT TODAY AND
ESPECIALLY LATE THIS AFTERNOON AS IT WORKS INTO NORTHERN PORTIONS
OF IOWA AND NEBRASKA WITH RAP FORECAST SOUNDINGS SHOWING LITTLE
CAP IN PLACE. CONVECTION LIKELY TO EXPAND DURING THE EVENING AS
LOW LEVEL JET FEEDS INTO THE COMPLEX. SURFACE FRONT STALLS NEAR
THE SOUTHERN NEBRASKA BORDER BY THURSDAY MORNING THEN BEGINS TO
LIFT BACK NORTH DURING THE DAY WITH A CONTINUED CHANCE OF SHOWERS
AND THUNDERSTORMS NORTH AND EAST OF THE BOUNDARY INTO FRIDAY.
SOME COOLING ON THURSDAY...ESPECIALLY NORTH...ASSOCIATED WITH
CLOUDS AND PRECIP BEFORE THE WARM AIR WORKS BACK INTO THE AREA
ON FRIDAY.
EXTENDED PERIOD STILL HOT AND DRY WITH UPPER LEVEL HIGH PRESSURE
CENTERED OVER THE CENTRAL PART OF THE NATION.
&&
.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.
VFR CONDITIONS SHOULD PERSIST THROUGH THE TAF PERIOD AT KOMA AND
KLNK. INCLUDED A PROB30 GROUP AT KOFK FOR -TSRA AND MVFR VSBY AFTER
00Z AS A COLD FRONT APPROACHES. SOUTHERLY WINDS WILL CONTINUE AHEAD
OF THE FRONT...MAINLY UNDER 14 KNOTS.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT/MILLER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1140 PM CDT TUE AUG 20 2013
.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.
VFR CONDITIONS SHOULD PERSIST THROUGH THE TAF PERIOD AT KOMA AND
KLNK. INCLUDED A PROB30 GROUP AT KOFK FOR -TSRA AND MVFR VSBY AFTER
00Z AS A COLD FRONT APPROACHES. SOUTHERLY WINDS WILL CONTINUE AHEAD
OF THE FRONT...MAINLY UNDER 14 KNOTS.
MILLER
&&
.PREV DISCUSSION... /ISSUED 1006 PM CDT TUE AUG 20 2013/
UPDATE...
INCLUDED PRECIP MENTION IN THE FAR NORTH AND ADJUSTED CLOUDS DUE
TO CONVECTIVE DEBRIS AND TWEAKS TO DEWPOINTS AND LOW TEMPS.
DISCUSSION...
THUNDERSTORMS IN WESTERN NEBRASKA INTO SOUTH CENTRAL SOUTH DAKOTA
PROVIDING SOME CONVECTIVE DEBRIS/CLOUDS FOR PARTS OF NEBRASKA
THIS EVENING WITH A SHORTWAVE TROF. THIS SHORTWAVE IS FORECAST TO
CONTINUE TO PUSH EAST THRU 12Z. THE BULK OF THE PRECIPITATION SHOULD
REMAIN TO THE NORTH...HOWEVER THE 12Z 4KM WRF/ AND LATEST HRRR AND
00Z NAM ARE TRYING TO DEVELOP SOME SHRA/TSRA INTO NORTHEAST
NEBRASKA AND PARTS OF WESTERN IOWA...HOWEVER IT WILL HAVE A TOUGH
TIME WITH WARM MID LEVEL TEMPERATURES IN PLACE. WITH A DECENT
45KT LOW LEVEL JET AND THETA-E ADVECTION...FORECAST SOUNDINGS ARE
MOIST ABOVE H85 AND COULD SEE SOME ELEVATED SHRA/TSRA TRY TO GET
GOING. WITH LIMITED COVERAGE...ONLY MENTIONED ISOLATED POPS IN THE
FAR NORTH.
ZAPOTOCNY
PREV DISCUSSION... /ISSUED 331 PM CDT TUE AUG 20 2013/
DISCUSSION...
MAIN FORECAST CONCERNS IN THE NEAR TERM ARE TEMPERATURES AND
DEWPOINTS WITH FOCUS THEN TURNING TO TSTM CHANCES WED AFTERNOON
INTO THURSDAY.
LOW LEVEL WARM AIR ADVECTION IS UNDERWAY ACROSS THE FORECAST
AREA. TEMPERATURES BY MID AFTERNOON HAVE RISEN INTO THE UPPER 80S
TO LOWER 90S. IN ADDITION...AN AXIS OF HIGHER DEWPOINTS INTO THE
MID 70S ARE OCCURRING OVER OUR NORTHERN CWA THIS AFTERNOON.
OTHERWISE...UPPER LEVEL HIGH PRESSURE CONTINUES TO DOMINATE A GOOD
PORTION OF THE CENTRAL U.S.
850MB TEMPS WILL BE A DEGREE OR TWO WARMER ON WEDNESDAY SO WILL
RAISE HIGHS JUST A BIT. A COLD FRONT IS PROGGED TO MOVE INTO THE
NORTHERN CWA BY WEDNESDAY AFTERNOON. A FEW STORMS COULD DEVELOP IN
THE AFTERNOON...BUT BULK SHEAR WILL BE RELATIVELY WEAK AND SOME
CONVECTIVE INHIBITION WILL NEED TO BE OVERCOME IN ORDER TO GET
ANY SEVERE STORMS. BETTER CHANCE FOR PCPN WILL BE INTO THE
EVENING HOURS AND OVERNIGHT INTO THURSDAY MORNING. ALL MODELS ARE
COMING INTO GOOD CONSENSUS...INCLUDING THE 12Z ECMWF...IN THAT
PCPN AREA WILL GENERALLY REMAIN POST FRONTAL AND MOVE SOUTH TOWARD
I-80 THROUGH EARLY THURSDAY. HAVE COOLED TEMPS IN THE NORTH FOR
WEDNESDAY BEHIND THE FRONT.
THE UPPER RIDGE AXIS WILL MOVE OVER THE CENTRAL PLAINS REGION BY
FRIDAY ALLOWING A WARM AND HUMID AIRMASS TO RETURN TO ALL OF THE
FORECAST AREA INTO THE WEEKEND.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
525 PM MDT THU AUG 22 2013
.AVIATION...
00Z TAF CYCLE
VFR CONDITIONS TO PERSIST THROUGH THE TAF PERIOD OUTSIDE OF
ISOLATED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE
FORECAST AREA. TERMINALS MOST LIKELY TO BE IMPACTED ARE KGUP AND
KFMN BOTH THIS EVENING AND AGAIN FRIDAY AFTERNOON.
11
&&
.PREV DISCUSSION...254 PM MDT THU AUG 22 2013...
NOT MUCH CHANGE TO THE FORECAST. AS EXPECTED...EVEN LESS CONVECTION
HAS POPPED UP THIS AFTERNOON AS THE DRY WEDGE AHEAD OF THE EASTERLY
WAVE MOVES ACROSS THE STATE. ALSO OF NOTE IS A PRETTY HEALTHY
INVERSION AROUND 550 MB ON THE 12Z ABQ SOUNDING. BEST CHANCES FOR
STORMS FOR THE REST OF THE EVENING WILL BE ACROSS THE NORTHERN
MTNS...AND IF THE HRRR IS CORRECT...MOST OF THE PRECIPITATION WILL
BE DONE BY 03Z.
THE DRY WEDGE SHOULD BE OVER NORTHERN NM TOMORROW. MEANWHILE...THE
UPPER HIGH WILL CONTINUE TO CREEP EASTWARD...AND WILL BE CENTERED
OVER OK/KS BY TOMORROW AFTN. THIS WILL ALLOW SOME OF THE MOISTURE
ASSOCIATED WITH THE EASTERLY WAVE TO CREEP UP INTO NM FRIDAY
AFTN/NIGHT. THIS SHOULD ALLOW FOR AN UPTICK IN SHOWER AND
THUNDERSTORM COVERAGE ON SATURDAY...MAINLY ACROSS THE HIGHER
TERRAIN.
BY SUNDAY AFTN...THE UPPER HIGH STRENGTHENS TO 596DAM AND THE
WESTWARD EXTENSION OF THE HIGH WILL BUILD BACK INTO NM. THIS WILL
KEEP THE BULK OF THE MOISTURE ASSOCIATED WITH AND AHEAD OF NOW
TROPICAL DEPRESSION NINE-E TO THE WEST OF THE STATE. INSTEAD...IT
APPEARS SOME RELATIVELY DRIER AIR WILL CIRCLE IN OVER NM.
THE GFS WANTS TO BRING ANOTHER WEAK WAVE ROUNDING THE SOUTH SIDE OF
THE UPPER HIGH INTO THE STATE ON MONDAY. THERE IS SOME MODEST
MOISTURE ASSOCIATED WITH THIS... SO THERE MAY BE A FEW MORE STORMS
THAN ON SUNDAY. HOWEVER THE ECMWF DOES NOT REALLY SHOW THIS FEATURE
OR THE MOISTURE MOVING UP INTO NM UNTIL AT LEAST 24 HOURS LATER. SO
FOR NOW...MONDAY-WEDNESDAY LOOKS FAIRLY MINIMAL PRECIPITATION-WISE.
LATER IN THE WEEK...MODELS LOOK TO WEAKEN THE WESTWARD EXTENSION OF
THE HIGH...WHICH MAY ALLOW FOR SOME RICHER MONSOON MOISTURE TO MOVE
INTO WESTERN AND CENTRAL NM...ESPECIALLY IF THERE IS INDEED A SECOND
TROPICAL SYSTEM LURKING SOUTH OF THE BAJA AS MODELS ARE INDICATED.
34
.FIRE WEATHER...
A MORE STABLE AND DRIER AIRMASS HAS INFILTRATED A LARGE PORTION OF
THE FORECAST AREA TODAY. THE RESULT IS ISOLATED SMALLER FOOTPRINTS
OF WETTING RAIN. THE STEERING FLOW FOR THE STORMS THE REST OF TODAY
WILL BE TOWARDS THE NORTHEAST.
THE HEART OF THE DRIER AIRMASS WILL SHIFT TO THE NORTH AND NORTHEAST
ON FRIDAY. THUNDERSTORM COVERAGE WILL INCREASE BUT THE WETTING RAIN
FOOTPRINT WONT INCREASE TOO MUCH. HIGH TEMPERATURES WILL BE NEAR TO
SLIGHTLY BELOW NORMAL SOUTH AND NEAR TO SLIGHTLY ABOVE NORMAL NORTH.
VENTILATION RATES WILL BE PRETTY GOOD AS SOUTH/SOUTHEAST WINDS
INCREASE ACROSS THE AREA. SOME BREEZES WILL BE OBSERVED ACROSS THE
EASTERN PLAINS...ESPECIALLY NORTHEAST WHERE A LEE SURFACE TROUGH
STRENGTHENS.
THE UPPER HIGH WILL STRENGTHEN AND BECOME DOMINATE OVER THE SOUTHERN
PLAINS AND MID MISSISSIPPI VALLEY REGION DURING THE WEEKEND.
CONFIDENCE IS PRETTY HIGH FOR THAT PATTERN. DUE TO THE ABOVE NORMAL
STRENGTH TO THE UPPER HIGH...THUNDERSTORM COVERAGES WILL VARY.
SATURDAY STILL LOOKS TO BE A MORE ACTIVE WETTING THUNDERSTORM DAY.
THE CONTINENTAL DIVIDE AND TO A LESSER EXTENT THE CENTRAL MTN CHAIN
WOULD BE FAVORED. THERE IS SOME DISCREPANCY IN THE MODELS AS FAR AS
CENTRAL MOUNTAINS ARE CONCERNED. STEERING FLOW ON SATURDAY WOULD
TAKE THE STORMS TOWARDS THE NORTH AND NORTHEAST. A DRIER AND MORE
STABLE AIRMASS PIVOTING AROUND THE UPPER HIGH IS STILL EXPECTED TO
INVADE PORTIONS OF THE AREA ON SUNDAY. THE ECMWF/GFS AND NAM
MODELS DEPICT THIS. BREEZES WOULD ENHANCE ACROSS THE EASTERN
PLAINS DURING THE WEEKEND. THIS IS A RESULT OF AN UNUSUALLY STRONG
LEE SIDE SURFACE TROUGH THAT IS EXPECTED TO STRENGTHEN DURING THE
PERIOD. THE PEAK WIND PERIOD WOULD BE ON SATURDAY.
THE LONGER RANGE MODELS STILL SHOW THE MAIN MONSOONAL PLUME WRAPPING
AROUND THE UPPER HIGH OVER ARIZONA AND FAR WEST NEW MEXICO DURING
THE EARLIER HALF OF NEXT WEEK. THE DRIER AND MORE STABLE AIRMASS
WOULD GET SHIFTED SOME TOWARDS THE EAST SO THUNDERSTORM COVERAGE
EACH DAY SHOULD INCREASE SLIGHTLY FROM WEST TO EAST. AGAIN...MAINLY
KEEPING STORMS WEST OF THE CENTRAL MTNS AND ESPECIALLY FAVORING THE
CONTINENTAL DIVIDE. TEMPERATURES WOULD BE ABOVE NORMAL EAST AND NEAR
NORMAL WEST. THE LEE TROUGH WILL REMAIN ACROSS THE EASTERN PLAINS
BUT IS EXPECTED TO WEAKEN SOME AS TIME PROGRESSES. THUS LOOK FOR THE
OVERALL WIND FLOW TO LESSEN SOME. GUSTY OUTFLOW WINDS WOULD REMAIN A
CONCERN HOWEVER...ACROSS WESTERN AND CENTRAL AREAS.
THE ECMWF AND GFS REMAINS PRETTY STEADFAST IN KEEPING THE MAIN UPPER
HIGH CENTER TO THE EAST OF THE STATE THE LATTER HALF OF NEXT WEEK.
THE HIGH ALSO LOOKS TO BE QUITE STRONG AND SIMILAR TO THE STRENGTH
AND POSITION IT WAS AUGUST 2011. MOISTURE WOULD CONTINUE TO OOZE
EASTWARD DUE TO OUTFLOW BOUNDARIES FROM CONVECTION ACROSS THE WEST
BUT THE FAVORED AREAS FOR WETTING RAIN WOULD REMAIN WEST. THE
EASTERN PLAINS ONCE AGAIN LOOK TO BE ON THE DRIER AND WARMER SIDE.
THE CURING OF NEW GRASS GROWTH ACROSS THE EAST WOULD MOST LIKELY
START UP DURING THIS PERIOD.
50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
52
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
254 PM MDT THU AUG 22 2013
.DISCUSSION...
NOT MUCH CHANGE TO THE FORECAST. AS EXPECTED...EVEN LESS CONVECTION
HAS POPPED UP THIS AFTERNOON AS THE DRY WEDGE AHEAD OF THE EASTERLY
WAVE MOVES ACROSS THE STATE. ALSO OF NOTE IS A PRETTY HEALTHY
INVERSION AROUND 550 MB ON THE 12Z ABQ SOUNDING. BEST CHANCES FOR
STORMS FOR THE REST OF THE EVENING WILL BE ACROSS THE NORTHERN
MTNS...AND IF THE HRRR IS CORRECT...MOST OF THE PRECIPITATION WILL
BE DONE BY 03Z.
THE DRY WEDGE SHOULD BE OVER NORTHERN NM TOMORROW. MEANWHILE...THE
UPPER HIGH WILL CONTINUE TO CREEP EASTWARD...AND WILL BE CENTERED
OVER OK/KS BY TOMORROW AFTN. THIS WILL ALLOW SOME OF THE MOISTURE
ASSOCIATED WITH THE EASTERLY WAVE TO CREEP UP INTO NM FRIDAY
AFTN/NIGHT. THIS SHOULD ALLOW FOR AN UPTICK IN SHOWER AND
THUNDERSTORM COVERAGE ON SATURDAY...MAINLY ACROSS THE HIGHER
TERRAIN.
BY SUNDAY AFTN...THE UPPER HIGH STRENGTHENS TO 596DAM AND THE
WESTWARD EXTENSION OF THE HIGH WILL BUILD BACK INTO NM. THIS WILL
KEEP THE BULK OF THE MOISTURE ASSOCIATED WITH AND AHEAD OF NOW
TROPICAL DEPRESSION NINE-E TO THE WEST OF THE STATE. INSTEAD...IT
APPEARS SOME RELATIVELY DRIER AIR WILL CIRCLE IN OVER NM.
THE GFS WANTS TO BRING ANOTHER WEAK WAVE ROUNDING THE SOUTH SIDE OF
THE UPPER HIGH INTO THE STATE ON MONDAY. THERE IS SOME MODEST
MOISTURE ASSOCIATED WITH THIS... SO THERE MAY BE A FEW MORE STORMS
THAN ON SUNDAY. HOWEVER THE ECMWF DOES NOT REALLY SHOW THIS FEATURE
OR THE MOISTURE MOVING UP INTO NM UNTIL AT LEAST 24 HOURS LATER. SO
FOR NOW...MONDAY-WEDNESDAY LOOKS FAIRLY MINIMAL PRECIPITATION-WISE.
LATER IN THE WEEK...MODELS LOOK TO WEAKEN THE WESTWARD EXTENSION OF
THE HIGH...WHICH MAY ALLOW FOR SOME RICHER MONSOON MOISTURE TO MOVE
INTO WESTERN AND CENTRAL NM...ESPECIALLY IF THERE IS INDEED A SECOND
TROPICAL SYSTEM LURKING SOUTH OF THE BAJA AS MODELS ARE INDICATED.
34
&&
.FIRE WEATHER...
A MORE STABLE AND DRIER AIRMASS HAS INFILTRATED A LARGE PORTION OF
THE FORECAST AREA TODAY. THE RESULT IS ISOLATED SMALLER FOOTPRINTS
OF WETTING RAIN. THE STEERING FLOW FOR THE STORMS THE REST OF TODAY
WILL BE TOWARDS THE NORTHEAST.
THE HEART OF THE DRIER AIRMASS WILL SHIFT TO THE NORTH AND NORTHEAST
ON FRIDAY. THUNDERSTORM COVERAGE WILL INCREASE BUT THE WETTING RAIN
FOOTPRINT WONT INCREASE TOO MUCH. HIGH TEMPERATURES WILL BE NEAR TO
SLIGHTLY BELOW NORMAL SOUTH AND NEAR TO SLIGHTLY ABOVE NORMAL NORTH.
VENTILATION RATES WILL BE PRETTY GOOD AS SOUTH/SOUTHEAST WINDS
INCREASE ACROSS THE AREA. SOME BREEZES WILL BE OBSERVED ACROSS THE
EASTERN PLAINS...ESPECIALLY NORTHEAST WHERE A LEE SURFACE TROUGH
STRENGTHENS.
THE UPPER HIGH WILL STRENGTHEN AND BECOME DOMINATE OVER THE SOUTHERN
PLAINS AND MID MISSISSIPPI VALLEY REGION DURING THE WEEKEND.
CONFIDENCE IS PRETTY HIGH FOR THAT PATTERN. DUE TO THE ABOVE NORMAL
STRENGTH TO THE UPPER HIGH...THUNDERSTORM COVERAGES WILL VARY.
SATURDAY STILL LOOKS TO BE A MORE ACTIVE WETTING THUNDERSTORM DAY.
THE CONTINENTAL DIVIDE AND TO A LESSER EXTENT THE CENTRAL MTN CHAIN
WOULD BE FAVORED. THERE IS SOME DISCREPANCY IN THE MODELS AS FAR AS
CENTRAL MOUNTAINS ARE CONCERNED. STEERING FLOW ON SATURDAY WOULD
TAKE THE STORMS TOWARDS THE NORTH AND NORTHEAST. A DRIER AND MORE
STABLE AIRMASS PIVOTING AROUND THE UPPER HIGH IS STILL EXPECTED TO
INVADE PORTIONS OF THE AREA ON SUNDAY. THE ECMWF/GFS AND NAM
MODELS DEPICT THIS. BREEZES WOULD ENHANCE ACROSS THE EASTERN
PLAINS DURING THE WEEKEND. THIS IS A RESULT OF AN UNUSUALLY STRONG
LEE SIDE SURFACE TROUGH THAT IS EXPECTED TO STRENGTHEN DURING THE
PERIOD. THE PEAK WIND PERIOD WOULD BE ON SATURDAY.
THE LONGER RANGE MODELS STILL SHOW THE MAIN MONSOONAL PLUME WRAPPING
AROUND THE UPPER HIGH OVER ARIZONA AND FAR WEST NEW MEXICO DURING
THE EARLIER HALF OF NEXT WEEK. THE DRIER AND MORE STABLE AIRMASS
WOULD GET SHIFTED SOME TOWARDS THE EAST SO THUNDERSTORM COVERAGE
EACH DAY SHOULD INCREASE SLIGHTLY FROM WEST TO EAST. AGAIN...MAINLY
KEEPING STORMS WEST OF THE CENTRAL MTNS AND ESPECIALLY FAVORING THE
CONTINENTAL DIVIDE. TEMPERATURES WOULD BE ABOVE NORMAL EAST AND NEAR
NORMAL WEST. THE LEE TROUGH WILL REMAIN ACROSS THE EASTERN PLAINS
BUT IS EXPECTED TO WEAKEN SOME AS TIME PROGRESSES. THUS LOOK FOR THE
OVERALL WIND FLOW TO LESSEN SOME. GUSTY OUTFLOW WINDS WOULD REMAIN A
CONCERN HOWEVER...ACROSS WESTERN AND CENTRAL AREAS.
THE ECMWF AND GFS REMAINS PRETTY STEADFAST IN KEEPING THE MAIN UPPER
HIGH CENTER TO THE EAST OF THE STATE THE LATTER HALF OF NEXT WEEK.
THE HIGH ALSO LOOKS TO BE QUITE STRONG AND SIMILAR TO THE STRENGTH
AND POSITION IT WAS AUGUST 2011. MOISTURE WOULD CONTINUE TO OOZE
EASTWARD DUE TO OUTFLOW BOUNDARIES FROM CONVECTION ACROSS THE WEST
BUT THE FAVORED AREAS FOR WETTING RAIN WOULD REMAIN WEST. THE
EASTERN PLAINS ONCE AGAIN LOOK TO BE ON THE DRIER AND WARMER SIDE.
THE CURING OF NEW GRASS GROWTH ACROSS THE EAST WOULD MOST LIKELY
START UP DURING THIS PERIOD.
50
&&
.AVIATION...
18Z TAF CYCLE
A DRIER AND MORE STABLE AIRMASS ALOFT WILL BE OVER MOST OF THE
FORECAST AREA TODAY. THIS WILL LIMIT SH/TS DVLPMENT. THE BEST
CHANCE OF TS OR SH EFFECTS WILL BE ACROSS THE FAR WEST. THIS
INCLUDES IMPACTS TO FMN AND GUP. HAVE VFR CONDITIONS PREDICTED FOR
THE TERMINAL SITES.
50
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 61 90 62 87 / 20 20 20 30
DULCE........................... 50 85 49 82 / 30 20 30 40
CUBA............................ 52 87 52 83 / 20 20 30 40
GALLUP.......................... 55 85 57 81 / 20 20 30 50
EL MORRO........................ 51 79 51 76 / 20 30 30 50
GRANTS.......................... 52 82 53 80 / 10 10 20 40
QUEMADO......................... 54 82 54 79 / 10 30 20 50
GLENWOOD........................ 55 86 54 83 / 5 20 20 30
CHAMA........................... 46 79 46 77 / 40 30 30 50
LOS ALAMOS...................... 57 82 57 79 / 20 20 30 40
PECOS........................... 55 79 55 77 / 20 20 20 40
CERRO/QUESTA.................... 53 79 53 78 / 30 20 30 40
RED RIVER....................... 43 74 46 72 / 40 30 30 50
ANGEL FIRE...................... 39 77 41 76 / 30 20 30 50
TAOS............................ 49 84 51 81 / 20 10 20 30
MORA............................ 51 78 52 77 / 20 10 20 40
ESPANOLA........................ 61 87 60 84 / 20 10 20 30
SANTA FE........................ 55 82 55 79 / 10 10 20 30
SANTA FE AIRPORT................ 58 86 58 83 / 10 10 20 30
ALBUQUERQUE FOOTHILLS........... 63 88 63 85 / 0 10 20 30
ALBUQUERQUE HEIGHTS............. 65 89 65 86 / 0 5 20 30
ALBUQUERQUE VALLEY.............. 63 90 64 87 / 0 5 20 30
ALBUQUERQUE WEST MESA........... 65 89 64 86 / 0 5 20 30
LOS LUNAS....................... 61 88 62 85 / 0 5 20 30
RIO RANCHO...................... 64 91 64 87 / 0 5 20 30
SOCORRO......................... 63 89 63 88 / 0 10 20 30
SANDIA PARK/CEDAR CREST......... 57 86 58 84 / 5 10 30 30
TIJERAS......................... 57 85 58 83 / 5 10 20 30
MORIARTY/ESTANCIA............... 55 84 56 80 / 5 10 30 30
CLINES CORNERS.................. 56 83 55 79 / 5 10 20 40
GRAN QUIVIRA.................... 56 81 56 80 / 5 20 20 30
CARRIZOZO....................... 57 83 60 82 / 5 20 20 30
RUIDOSO......................... 52 77 54 75 / 5 40 30 40
CAPULIN......................... 54 84 54 81 / 10 10 10 20
RATON........................... 54 87 55 85 / 10 10 20 20
SPRINGER........................ 55 86 55 86 / 10 0 10 20
LAS VEGAS....................... 51 83 54 81 / 5 10 20 20
CLAYTON......................... 62 91 61 88 / 5 5 5 10
ROY............................. 59 84 58 83 / 5 5 10 10
CONCHAS......................... 64 90 66 90 / 5 0 10 10
SANTA ROSA...................... 61 88 63 88 / 5 0 10 10
TUCUMCARI....................... 65 93 67 93 / 0 5 10 10
CLOVIS.......................... 61 88 64 87 / 0 5 10 20
PORTALES........................ 61 88 65 88 / 0 10 10 20
FORT SUMNER..................... 63 88 63 88 / 0 5 10 10
ROSWELL......................... 64 90 67 91 / 0 5 10 10
PICACHO......................... 56 84 60 85 / 5 10 20 20
ELK............................. 53 77 56 78 / 5 30 40 30
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
34
AREA FORECAST DISCUSSION
NWS RALEIGH NC
945 PM EDT THU AUG 22 2013
.SYNOPSIS...
A PRE-FRONTAL TROUGH WILL LINGER OVER THE REGION THROUGH EARLY
FRIDAY. A COLD FRONT WILL PUSH SOUTH THROUGH NORTH CAROLINA FRIDAY
NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BRING COOLER AND DRIER
AIR FOR THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 945 PM THURSDAY...
SEVERAL CLUSTERS OF PROBLEMATIC STORMS HAVE AFFECTED MAINLY THE
EASTERN CWA SINCE LATE AFTERNOON... BUT ISOLATED STORM CLUSTERS
PERSIST AROUND THE ENTIRE AREA AS A MODERATELY UNSTABLE AIR MASS
(MLCAPE VALUES STILL 1500-2000 J/KG) LINGERS. DEEP LAYER SHEAR
REMAINS RESPECTABLE AT 25-30 KTS IN THE BASE OF THE MID LEVEL
SHORTWAVE TROUGH NOW SWINGING THROUGH NY/DE/ERN VA/ERN NC... BUT
THIS SHOULD BE WANING OVERNIGHT AS THE TROUGH PROGRESSES OFFSHORE.
INSTABILITY IS LIKEWISE EXPECTED TO FALL BELOW 1000 J/KG
OVERNIGHT... AND WITH PRECIP WATER VALUES HAVING DROPPED TO AT OR
UNDER 1.5 INCHES OVER MUCH OF CENTRAL NC ACCORDING TO BLENDED TPW
IMAGERY... WE SHOULD SEE EVEN THE ISOLATED STORM CLUSTERS LESSEN IN
COVERAGE AND INTENSITY OVER THE NEXT SEVERAL HOURS AS WE LOSE BOTH
DYNAMIC AND THERMODYNAMIC SUPPORT. WILL RETAIN THE ISOLATED STORM
MENTION FOR ANOTHER FEW HOURS BEFORE DROPPING SHOWER/STORM CHANCES
TO UNDER 15 PERCENT LATE TONIGHT. THIS FOLLOWS RECENT HRRR MODEL
OUTPUT TRENDS. FAIR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL
FACILITATE PATCHY FOG DEVELOPMENT LATE. LOW 68-72... IN LINE WITH
STATISTICAL GUIDANCE AND PERSISTENCE. -GIH
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
AS OF 300 PM THURSDAY...
BY FRIDAY MORNING...THE COLD FRONT THAT IS NOW MOVING INTO THE
OHIO VALLEY WILL BEGIN TO CROSS THE APPALACHIAN MOUNTAINS DROPPING
SOUTHWARD THROUGH VA. OVERALL THE 12Z NAM/ 12 GFS AND 00 ECMWF ARE
ALL IN GOOD AGREEMENT WITH THAT TIMING. THE FRONT WILL CONTINUE TO
PUSH SOUTHWARD DURING THE DAY AND WITH STRONG SHORTWAVE ENERGY
DROPPING SE THROUGH THE BROAD UPPER TROUGH...EXPECT TO SEE SOME
CONVECTION DEVELOP ALONG THE FRONTAL BOUNDARY DURING THE AFTERNOON
AND EVENING HOURS. WITH PLENTY OF LOW LEVEL INSTABILITY AHEAD OF
THE FRONT DUE TO WARM HUMID AIR MASS...SO STRONGER STORMS ARE
POSSIBLE WITH GUSTY WINDS THE LIKELIEST THREAT. BASED ON THE
TIMING OF THE FRONT...SHOULD BE ABLE TO GET ENOUGH HEATING DURING
THE DAY TO AGAIN PUSH HIGHS INTO THE MID TO UPPER 80S.
THE FRONT CONTINUES TO PUSH SW TOWARD SC ON FRIDAY NIGHT AND WILL
PUSH THE LINGERING CONVECTION SOUTHEASTWARD TOWARD THE COAST. HAVE
GRADUALLY DIMINISHED POPS FROM NORTH TO SOUTH FRIDAY NIGHT. ONCE
THE FRONT CLEARS...WILL BEGIN TO SEE DRIER AIR SINK SOUTHWARD. FOR
LOWS OVERNIGHT EXPECT LOWS IN THE MID TO UPPER 60S.
ON SATURDAY...THE STRONG HIGH PRESSURE OVER THE GREAT LAKES AND
NORTHEAST WILL CONTINUE TO SINK SOUTHWARD ALONG THE EASTERN
SEABOARD...PUSHING THROUGH NORTH CAROLINA. THIS WILL ALLOW THE
DRIER AND COOLER AIR TO CONTINUE TO MOVE SOUTHWARD. EXPECT HIGH
TEMPERATURES IN THE LOW TO MID 80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...
A LARGE-SCALE AREA OF HIGH PRESSURE THAT ORIGINATED NEAR HUDSON BAY
CANADA SETTLES INTO THE REGION SATURDAY NIGHT THROUGH AT LEAST
MONDAY...BRINGING A COOLER AND DRIER AIRMASS TO THE AREA.
MEANWHILE...A MID/UPPER LEVEL RIDGE CENTERED OVER THE CENTRAL U.S.
WILL EXTEND INTO THE AREA FROM THE WEST AND FURTHER SUPPORT THE
COOLING/DRYING TREND. EXPECT HIGH TEMPERATURES ON SUNDAY/MONDAY TO
RUN ABOUT 5 DEGREES BELOW NORMAL (LOW-MID 80S) AND LOW TEMPERATURES
SUNDAY THROUGH TUESDAY MORNINGS TO RUN ABOUT 5-10 DEGREES BELOW
NORMAL (GENERALLY LOW-MID 60S...POSSIBLY UPPER 50S NORTH OF A LINE
FROM ROCKY MOUNT TO RALEIGH TO ASHEBORO ON MONDAY MORNING).
CONDITIONS BEGIN TO SLOWLY REBOUND ON MONDAY AND GRADUALLY WARM
TOWARDS NORMAL THROUGH THE REST OF THE WEEK...ESPECIALLY ONCE THE
SURFACE HIGH SLIDES SOUTH OF THE AREA DURING THE DAY ON MONDAY. ON
TUESDAY...A BACKDOOR FRONT CROSSING TO THE NORTHEAST ACROSS VIRGINIA
IS EXPECTED TO BREAKDOWN THE MID/UPPER RIDGE AND LET WEATHER
DISTURBANCES ROUND THE EASTERN PERIPHERY OF THE RIDGE AS TROUGHING
DEVELOPS OVER THE NE CONUS. LATEST MODEL GUIDANCE INDICATES THAT THE
NEXT SYSTEM TO REACH THE AREA HAS SLOWED AND HAVE THEREFORE DELAYED
THE NEXT ONSET OF PRECIPITATION UNTIL WEDNESDAY AFTN/EVENING...WITH
SHOWERS CONTINUING INTO THURSDAY.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 730 PM THURSDAY...
A SURFACE TROUGH...AS WELL AS VARIOUS OUTFLOW BOUNDARIES...AND
LINGERING INSTABILITY ARE KEEPING A FEW STORMS GOING AROUND CENTRAL
NC THIS EVENING...THOUGH MOST OF THE STORMS ARE OCCURRING AWAY FROM
TAF SITES AND SHOULD COME TO AN END BY MIDNIGHT. A LIGHT
WEST-SOUTHWESTERLY SURFACE WIND AND MOSTLY VFR CONDITIONS ARE
EXPECTED...THOUGH A FEW AREAS MAY SEE MVFR VSBYS BY DAYBREAK.
AN APPROACHING COLD FRONT WILL INITIATE SCATTERED STORMS BY EARLY
FRIDAY AFTERNOON...FIRST AROUND THE TRIAD THEN MOVING SOUTH AND EAST
TOWARD KRDU..KRWI AND KFAY. THE OCCURRENCE AND TIMING OF STORMS AT
INDIVIDUAL TERMINALS IS STILL UNCERTAIN AT THIS POINT...BUT THE
PRESENCE OF THE COLD FRONT AND UPPER LEVEL TROUGH LENDS ENOUGH
FORECAST CONFIDENCE FOR A MENTION OF THUNDERSTORMS IN THE TAFS AFTER
18Z.
LOOKING AHEAD:
AFTER THE PASSAGE OF THE COLD FRONT...HIGH PRESSURE WILL SLOWLY
BUILD INTO THE REGION AND STRENGTHEN...LEADING TO A TREND TOWARD
VFR CONDITIONS THROUGH EARLY NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...KC
NEAR TERM...HARTFIELD
SHORT TERM...ESS
LONG TERM...BMD
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
754 PM EDT THU AUG 22 2013
.SYNOPSIS...
RIDGE OF HIGH PRESSURE OFFSHORE WILL SLOWLY GIVE WAY TO A COLD FRONT
APPROACHING FROM THE NORTHWEST ON FRIDAY. THIS FRONT WILL CROSS THE AREA
BY EARLY SATURDAY. THE COLD FRONT WILL USHER IN COOLER AND DRIER
CONDITIONS FOR THE WEEKEND INTO EARLY NEXT WEEK. A WARMING TREND WILL
TAKE PLACE MID WEEK NEXT WEEK AS HIGH PRESSURE SHIFTS OFFSHORE.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 3 PM THURSDAY...WATER VAPOR IMAGERY IS SHOWING THE SHORTWAVE
CONTINUING TO MOVE ACROSS THE MID-ATLANTIC AND EASTERN CAROLINAS.
LINES OF CONVECTION HAVE FORMED AND ARE MOVING TOWARD THE
EAST-SOUTHEAST. AT THIS TIME THE CONVECTION IS STAYING BELOW SEVERE
LIMITS AND IS MOVING AROUND 10 KNOTS. WITH THE LINEAR CONFIGURATION
THAT HAS DEVELOPED IT APPEARS THAT ANY THREAT FOR FLOODING IS SMALL.
THE
LATEST HRRR IS SHOWING THE CONVECTION CONTINUING TO THE COAST AND
DYING AS IT MOVES OUT OVER THE WATERS. EXPECT THE CONVECTION TO
CONTINUE THROUGH THE EARLY EVENING HOURS.
OVERNIGHT MINIMUM TEMPERATURES ARE EXPECTED TO FALL BACK INTO THE
LOWER 70S INLAND AND MID 70S AT THE BEACHES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...CONCERN THROUGH THE SHORT TERM REVOLVES
AROUND A COLD FRONT WHICH WILL DROP THROUGH THE AREA LATE FRIDAY
NIGHT INTO SATURDAY...AND ITS RELATED CONVECTION POTENTIAL.
FRIDAY WILL BEGIN RATHER NICE...AND WILL BE A WARM DAY. SUBSIDENCE
BEHIND A DEPARTING SHORTWAVE WITH SUBTLE HEIGHT INCREASES ALOFT WILL
CREATE SUBSTANTIAL EARLY SUNSHINE. THIS WILL DRIVE TEMPS UP TO
AROUND 90 AWAY FROM THE BEACHES. THESE WARM TEMPS COMBINED LOW-LEVEL
SW FLOW AROUND RETREATING HIGH PRESSURE OFFSHORE WILL CREATE
SIGNIFICANT INSTABILITY...WITH SBCAPE AND MLCAPE APPROACHING 2000
J/KG FRIDAY AFTN. IN ADDITION...LOW-LEVEL LAPSE RATES FROM SURFACE
TO 850MB WILL BE QUITE STEEP...AND DCAPE REACHES 600-1000 J/KG
FRIDAY EVE. THESE ALL SUGGEST TSTM POTENTIAL. HOWEVER...BULK SHEAR
IS QUITE LOW...AND PWATS ARE ONLY ABOUT 1.8 INCHES...LIMITING SEVERE
POTENTIAL. SPC HAS PLACED THE AREA IN A "SEE TEXT" FOR THE SWODY2 AS
THE FRONT APPROACHES INTO THIS UNSTABLE ENVIRONMENT. HOWEVER...FEEL
SEVERE POTENTIAL IS QUITE LOW HERE SINCE THE FRONT WILL NOT CROSS
UNTIL VERY LATE FRIDAY NIGHT...AND SOUNDINGS ARE NOT SO SATURATED
THAT WET-MICROBURSTS ARE FAVORABLE. STILL...WITH THE STEEP LOW-LEVEL
LAPSE RATES AND HIGH INSTABILITY...AN ISOLATED STRONG WIND GUST
CANNOT BE RULED OUT IN ANY AFTN PULSE STORM OR NIGHTTIME CONVECTION
BEFORE THE SURFACE LAYER STABILIZES. THIS MEANS THE MOST LIKELY
PLACE FOR A STRONGER WIND GUST WOULD BE ALONG THE SEA BREEZE
CONVECTION...IF ANY...FRIDAY AFTN...OR ALONG THE FAR NORTHERN TIER
AS THE FRONT APPROACHES FRIDAY NIGHT. WILL NOT MENTION SEVERE IN
GRIDS OR ZONE FORECAST PRODUCT.
FROPA WILL OCCUR OVERNIGHT FRIDAY...AND BY SATURDAY MORNING WILL
HAVE CLEARED THE CWA. COOL HIGH PRESSURE BUILDS IN BEHIND THIS
FRONT...BUT AS NE WINDS DEVELOP...MOISTURE ADVECTION WILL COMMENCE
OFF THE OCEAN...AND IT WILL TAKE MUCH OF SATURDAY BEFORE DRYING OF
THE COLUMN BELOW 700MB OCCURS. THIS CREATES SHOWERS AND CLOUDS MOST
OF THE DAY...WITH CLEARING OCCURRING ONLY BY SATURDAY NIGHT FROM
NORTH TO SOUTH.
TEMPS FRIDAY NIGHT WILL BE TRICKY DUE TO TIMING OF THE FRONT...BUT
IT APPEARS NEGATIVE 850MB THERMAL ADVECTION HOLDS OFF UNTIL
SATURDAY...SO FRIDAY NIGHT TEMPS WILL BE ABOVE 70 CWA-WIDE. HIGHS
SATURDAY WILL REACH INTO THE LOW 80S...AND HAVE UNDERCUT MOS NUMBERS
A BIT. LOWS SATURDAY NIGHT WILL FALL WELL INTO THE 60S AS A MUCH
DRIER AIRMASS MOVES INTO THE REGION.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...MID LEVEL PATTERN WILL BE DOMINATED BY
MASSIVE RIDGING CENTER ACROSS KANSAS WITH AN EASTWARD
EXTENSION/AXIS ACROSS THE CAROLINAS. AT THE SURFACE...HIGH
PRESSURE AXIS WILL INITIALLY BE OVER THE MID ATLANTIC AND IN TIME
WILL BECOME ELONGATED EAST/WEST ACROSS THE SOUTHEAST. THE EASTERN
EDGE OF THE RIDGE WILL WEAKEN AS SEVERAL SHORTWAVES RIDE THE
PERIPHERY AND DIP SOUTHWARD. THERE WILL ALMOST CERTAINLY BE
SEVERAL MESOSCALE CONVECTIVE SYSTEMS WITH THIS PATTERN AND ONE IF
NOT MORE MAY BE A FACTOR LATE IN THE PERIOD BUT ALL BUT IMPOSSIBLE
TO PINPOINT THIS FAR OUT IN TIME. THUS...THE FORECAST REMAINS DRY
THROUGHOUT.
THE ONLY INTERESTING NOTE REGARDING TEMPERATURES IS THE MEX GUIDANCE
HAS DECREASED SOMEWHAT WITH 61 IN WILMINGTON FOR MONDAY MORNING.
THIS SEEMS LIKE A REASONABLE TREND...COOLER AS CLIMATOLOGY BECOMES
LESS OF A FACTOR WITH TIME AND GEFS 850MB TEMPERATURES ARE 2-3
STANDARD DEVIATIONS BELOW NORMAL.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 00Z...VFR WITH BRIEF PERIODS OF MVFR POSSIBLE IN ASSOCIATION
WITH SCATTERED SHOWERS AND THUNDERSTORMS OVER THE NEXT FEW HOURS.
MVFR/POSSIBLE IFR DUE TO FOG LATE OVERNIGHT INTO THE EARLY MORNING
HOURS. CHANCE FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS AGAIN
ON FRIDAY. OTHERWISE EXPECT VFR.
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE ACROSS PORTIONS
OF THE FORECAST AREA...MAINLY AFFECTING THE INLAND SITES...WITH
ISOLATED SHOWERS ALSO REACHING THE COASTAL SITES. ANTICIPATE
ACTIVITY TO CONTINUE ON ITS DOWN SPIRAL TO TAPER OFF OVER THE NEXT
FEW HOURS. VFR IS EXPECTED TO PREVAIL INTO THE EARLY OVERNIGHT HOURS
WITH LIGHT WEST-SOUTHWEST WINDS. GIVEN RECENT RAINFALL AND FAVORABLE
CONDITIONS...EXPECT FOG DEVELOPMENT LATE OVERNIGHT INTO THE EARLY
MORNING HOURS ACROSS MOST OF THE AREA...CREATING MVFR/POSSIBLE IFR
RESTRICTIONS INLAND...AND VFR/MARGINAL MVFR ALONG THE COAST. AFTER
DAYBREAK...EXPECT VFR TO PREVAIL WITH WEST-SOUTHWEST WINDS
INCREASING TO AOB 10 KTS. COULD NOT RULE OUT ISOLATED SHOWERS AND
THUNDERSTORMS FRIDAY AFTERNOON...THUS HAVE OPTED TO INTRODUCE VCSH ATTM.
EXTENDED OUTLOOK...CHANCE FOR ISOLATED SHOWERS AND THUNDERSTORMS
INTO SATURDAY MORNING IN ASSOCIATION WITH AN APPROACHING COLD FRONT.
OTHERWISE EXPECT VFR THROUGH THE EXTENDED.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE CONTINUES TO RIDGE BACK
ACROSS THE COASTAL WATERS. THE WINDS WILL CONTINUE TO BE AT OR
LESS THAN 10 KNOTS FROM THE SOUTHWEST AND THIS WILL CONTINUE THE
BENIGN CONDITIONS WITH SEAS OF 2 TO 3 FEET. WITH A WEST-NORTHWEST
FLOW...WE MAY SEE A FEW THUNDERSTORMS TRYING TO WORK THEIR WAY
BACK OVER THE WATERS BUT THEY SHOULD ONLY BE AT OR NEAR THE
COASTLINE.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...PRE-FRONTAL AIRMASS FRIDAY WILL TRANSITION
TO POST-FRONTAL SATURDAY THANKS TO A COLD FRONT WHICH WILL DROP
SOUTHWARD ACROSS THE WATERS OVERNIGHT FRIDAY. SW WINDS WILL BE 10-15
KTS MOST OF FRIDAY...BEFORE RAPIDLY SHIFTING TO THE NORTH BY
SATURDAY MORNING AT LESS THAN 10 KTS...WITH A NE SURGE DEVELOPING AT
THE END OF THE PERIOD...INCREASING WINDS TO 15 KTS OR MORE. WAVES
WILL BE NEARLY ENTIRELY FORMED BY THE WIND-WAVE GROUP...WITH 2-3 FT
SEAS FRIDAY CREATED BY SW WIND CHOP...THEN BECOMING 2-4 FT LATE
SATURDAY THANKS TO THE DEVELOPING NE WIND WAVE.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 300 PM THURSDAY...A FAIRLY BRISK NORTHEASTERLY FLOW WILL
PREVAIL FOR MOST OF THE DAY SUNDAY WITH SPEEDS 10-15 KNOTS AND
PROBABLY HOVERING MORE TOWARD THE HIGHER END OF THE RANGE. AS HIGH
PRESSURE WEAKENS AND MOVES TO THE SOUTH...WINDS WILL DIMINISH TO
TEN KNOTS OR LESS BY MONDAY AFTERNOON. A FURTHER SHIFTING OF THE
HIGH TO BASICALLY OVERHEAD WILL LEAD TO WINDS BASICALLY LIGHT AND
VARIABLE TUESDAY. OVERALL SEAS ARE NEVER REALLY IMPRESSIVE WITH
3-4 FEET SUNDAY TRENDING DOWN TO AROUND TWO FEET TUESDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 125 PM THURSDAY...THE LATEST TIDE FORECAST FOR THE CAPE FEAR
RIVER IN WILMINGTON IS SHOWING THE RIVER REACHING LEVELS OF MINOR
COASTAL FLOODING. THE PEAK OF THE TIDE IS FORECASTED TO REACH 5.5
FEET BETWEEN 11 PM AND MIDNIGHT. THUS A COASTAL FLOOD ADVISORY FOR THE
CAPE FEAR RIVER AROUND DOWNTOWN WILMINGTON HAS BEEN ISSUED BETWEEN
10 PM AND 1 AM.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY UNTIL 1 AM EDT FRIDAY FOR NCZ107.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DRH
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...SGL
MARINE...JDW/SHK/DRH
TIDES/COASTAL FLOODING...DRH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
150 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH THE CAROLINAS FROM THE WEST THIS
EVENING...THEN TRACK EAST ACROSS THE REGION ON THURSDAY. SURFACE
HIGH PRESSURE WILL STRENGTHEN ACROSS THE OHIO VALLEY IN THE WAKE OF
THE UPPER LEVEL TROUGH...DRIVING A COLD FRONT SOUTHWARD INTO THE
CAROLINAS DURING THE DAY FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1025 AM WEDNESDAY...
THE LATEST SURFACE ANALYSIS SHOWED A DIFFUSE FRONT ALONG THE
CAROLINA COAST WITH WEAK HIGH PRESSURE REMAINING OVER CENTRAL NORTH
CAROLINA WEST OF THE FRONT. IN THE SOUTHWEST FLOW ALOFT...WEAK
DIFFLUENCE ON WATER VAPOR AND A MID-LEVEL SHORTWAVE IN A MOIST FLOW
ALOFT HELPED TO PRODUCE SCATTERED TO NUMEROUS SHOWERS MAINLY ALONG
AND NORTH OF U.S. 64 THIS MORNING. THESE SHOWERS WILL CONTINUE TO
MOVE NORTHEAST LEAVING A PERIOD OF ISOLATED TO SCATTERED SHOWERS AS
THE MID-LEVEL WAVE CONTINUES TO MOVE NORTHEAST. DURING THE
AFTERNOON...PRECIPITABLE WATER VALUES WILL REMAIN NEAR TWO INCHES...
AND MODEST HEATING SHOULD BE SUFFICIENT TO RESULT IN MLCAPE IN THE
LOWEST KM FROM 500J/KG TO 1500J/KG...GREATEST TOWARD THE COASTAL
PLAIN. 1000-500MB LAPSE RATES ARE ONLY FORECAST TO BE 6C/KM OR LESS.
THE RUC ACTUALLY FORECASTS WEAK SUBSIDENCE THIS AFTERNOON IN THE
WAKE OF THE MID-LEVEL SHORTWAVE...AND THE GFS BUFR SOUNDINGS ARE
SOMEWHAT CAPPED TO DEEP CONVECTION. ON THE OTHER HAND...MODIFIED
MORNING SOUNDINGS AND RUC AND NAM BUFR SOUNDINGS SUGGEST ENOUGH
INSTABILITY TO PROVIDE FOR ISOLATED-TO-SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO EARLY THIS EVENING. THE HIGHEST
PROBABILITY OF ANY SHOWERS SHOULD BE OVER THE NORTHWEST PIEDMONT
WHERE 850MB THETA-E AND K INDICES ARE HIGHEST...CLOSER TO WHERE THE
BETTER 0-3KM SHEAR WILL BE FOR MOST OF THE AFTERNOON RELATIVE TO THE
REST OF CENTRAL NORTH CAROLINA...AND WHERE THE RUC SHOWS AN SLIGHT
INCREASE IN 850MB WINDS. TEMPERATURES STILL MOSTLY BELOW NORMAL WITH
HIGHS IN THE 80S.
TONIGHT...EXPECT CHANCES FOR SHOWERS TO DIMINISH WITHIN A FEW HOURS
AFTER SUNSET...THOUGH A TOKEN SLIGHT CHANCE WILL PERSIST GIVEN SUCH
DEEP MOISTURE AND MARGINAL HEIGHT FALLS ALOFT AS THE UPPER LEVEL
WAVE TRACKS INTO THE MID-ATLANTIC TO THE NORTH OF CENTRAL NORTH
CAROLINA. LOWS TONIGHT SIMILAR TO PREVIOUS NIGHTS IN THE 68-73F
RANGE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...
A PRE-FRONTAL TROUGH WILL SET UP OVER THE EASTERN PIEDMONT/SANDHILLS
THURSDAY AS THE MEAN FLOW BECOMES MORE WESTERLY IN THE REAR OF THE
DEPARTING MID/UPPER TROUGH OFFSHORE. THIS SHOULD LEAD TO A REDUCTION
IN THE CHANCE OF CONVECTION EXCEPT ALONG AND EAST OF THE TROUGH
THURSDAY AFTERNOON INTO THE EVENING. QPF OF AROUND 0.25 WILL BE
FORECAST FROM AROUND KFAY NE TO KRDU AND RWI (AREAL AVERAGE)... WITH
0.01 TO THE WEST OVER THE TRIAD REGION. CHANCE POP ALL ZONES BUT
ONLY LOW CHANCE (25-30 PERCENT) NW... TO 50 IN THE SE. HIGHS SHOULD
REBOUND INTO THE MID TO UPPER 80S EXCEPT AROUND 90 IN THE SE. PW`S
WILL ALSO REDUCE TO LESS THAN 1.25 IN THE NW TO AROUND 1.5 IN THE
EAST. DEW POINTS SHOULD MIX OUT INTO THE LOWER TO MID 60S NW...
ENHANCING CONFIDENCE IN THE LOWER POP FORECAST.
THURSDAY NIGHT AND FRIDAY... THE COLD FRONT SHOULD EVENTUALLY
OVERTAKE THE PRE-FRONTAL TROUGH OVER THE SOUTHERN AND EASTERN ZONES
FRIDAY. UNTIL THEN... ANOTHER DAY OF MOSTLY SCATTERED SHOWERS AND
THUNDERSTORMS IS EXPECTED... MAINLY IN THE SOUTH AND EAST (WHERE
PW`S REMAIN NEARLY 1.5 INCHES)... ALONG AND AHEAD OF THE CONVERGENCE
ZONE. THE CHANCE OF SHOWERS/STORMS WILL DIMINISH OVERNIGHT FRIDAY
NIGHT AS THE FRONT SETTLES NEAR THE SC BORDER 12Z SATURDAY. LOWS
65-70. HIGHS FRIDAY WITH A WIND SHIFT TO THE NE... 86-91.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...
A LARGE UPPER TROUGH IS FORECAST TO BE ANCHORED IN THE WESTERN
ATLANTIC AS AN UPPER RIDGE BECOMES ESTABLISHED OVER THE PLAINS THIS
PERIOD. AN ANOMALOUS MEAN NORTHERLY FLOW WILL RESULT FROM THE GREAT
LAKES AND NEW ENGLAND SOUTHWARD DEEP INTO SC/GA. THIS WILL BE A DRY
AND COOL FLOW FOR LATE AUGUST. SURFACE CAA WILL BE MOST PRONOUNCED
SATURDAY AND SUNDAY AS STRONG (~1026+ MB) SURFACE HIGH PRESSURE
BUILDS INTO NC FROM NY/PA. SATURDAY WILL BE THE DAY WITH THE
STRONGEST DAA AS THE MAIN COLD FRONT WILL BEGIN THE DAY NEAR THE SC
BORDER... BUT SHIFT DEEP INTO SC/GA BY LATE SATURDAY. SENSIBLE
WEATHER... PARTLY TO MOSTLY SUNNY SATURDAY. MOSTLY SUNNY SUNDAY.
CLEAR SATURDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE ONLY 80-85
(A GOOD 5-8 DEGREES BELOW NORMAL). LOWS SUNDAY AND MONDAY SHOULD BE
IN THE 50S NORTH... AND LOWER 60S SOUTH (ALMOST 10 DEGREES BELOW
NORMAL).
FOR MONDAY THROUGH TUESDAY... A GRADUAL WARMING TREND BUT STILL DRY.
SURFACE HIGH PRESSURE SHOULD BECOME ANCHORED OVER THE APPALACHIANS
AS THE UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY REMAINS STRONG.
SENSIBLE WEATHER... MOSTLY CLEAR/MOSTLY SUNNY. LOWS 58-65. HIGHS IN
THE 80S.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 150 PM WEDNESDAY...
24-HR TAF PERIOD:
AREAS OF MVFR CEILINGS WILL CONTINUE TO SLOWLY LIFT AND IMPROVE TO
VFR BETWEEN 18 TO 20Z. SCATTERED SHOWERS AND THUNDERSTORMS WILL HAVE
TO POTENTIAL TO IMPACT ALL TERMINALS THIS AFTERNOON AND INTO THE
EVENING WITH THE BEST CHANCE TOWARD THE TRIAD AND KINT AND KGSO.
WHILE SHOWERS SHOULD DIMINISH IN COVERAGE THIS EVENING...THERE WILL
BE A CHANCE OF SHOWERS WELL INTO THE OVERNIGHT HOURS WITH THE
APPROACH OF THE TROUGH INTO THE REGION.
WHILE ONE CANNOT TOTALLY RULE OUT THE POTENTIAL FOR SUB-VFR CEILINGS
TO DEVELOP OVERNIGHT...THE MOISTEN LADEN BOUNDARY LAYER IN PLACE
WILL BEGIN TO DRY IN RESPONSE TO INCREASING LOW-LEVEL WESTERLY FLOW.
LOOKING AHEAD:
ISOLATED TO SCATTERED SHOWERS AND STORMS CAN BE EXPECTED
THURSDAY/FRIDAY AS A COLD FRONT SLOWLY APPROACHES FROM THE NORTH.
VFR CONDITIONS ARE THEN EXPECTED IN THE WAKE OF THE FRONT SAT
THROUGH EARLY NEXT WEEK AS DRY HIGH PRESSURE BUILDS INTO THE
MID-ATLANTIC.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...DJF/VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1027 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH THE CAROLINAS FROM THE WEST THIS
EVENING...THEN TRACK EAST ACROSS THE REGION ON THURSDAY. SURFACE
HIGH PRESSURE WILL STRENGTHEN ACROSS THE OHIO VALLEY IN THE WAKE OF
THE UPPER LEVEL TROUGH...DRIVING A COLD FRONT SOUTHWARD INTO THE
CAROLINAS DURING THE DAY FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1025 AM WEDNESDAY...
THE LATEST SURFACE ANALYSIS SHOWED A DIFFUSE FRONT ALONG THE
CAROLINA COAST WITH WEAK HIGH PRESSURE REMAINING OVER CENTRAL NORTH
CAROLINA WEST OF THE FRONT. IN THE SOUTHWEST FLOW ALOFT...WEAK
DIFFLUENCE ON WATER VAPOR AND A MID-LEVEL SHORTWAVE IN A MOIST FLOW
ALOFT HELPED TO PRODUCE SCATTERED TO NUMEROUS SHOWERS MAINLY ALONG
AND NORTH OF U.S. 64 THIS MORNING. THESE SHOWERS WILL CONTINUE TO
MOVE NORTHEAST LEAVING A PERIOD OF ISOLATED TO SCATTERED SHOWERS AS
THE MID-LEVEL WAVE CONTINUES TO MOVE NORTHEAST. DURING THE
AFTERNOON...PRECIPITABLE WATER VALUES WILL REMAIN NEAR TWO INCHES...
AND MODEST HEATING SHOULD BE SUFFICIENT TO RESULT IN MLCAPE IN THE
LOWEST KM FROM 500J/KG TO 1500J/KG...GREATEST TOWARD THE COASTAL
PLAIN. 1000-500MB LAPSE RATES ARE ONLY FORECAST TO BE 6C/KM OR LESS.
THE RUC ACTUALLY FORECASTS WEAK SUBSIDENCE THIS AFTERNOON IN THE
WAKE OF THE MID-LEVEL SHORTWAVE...AND THE GFS BUFR SOUNDINGS ARE
SOMEWHAT CAPPED TO DEEP CONVECTION. ON THE OTHER HAND...MODIFIED
MORNING SOUNDINGS AND RUC AND NAM BUFR SOUNDINGS SUGGEST ENOUGH
INSTABILITY TO PROVIDE FOR ISOLATED-TO-SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO EARLY THIS EVENING. THE HIGHEST
PROBABILITY OF ANY SHOWERS SHOULD BE OVER THE NORTHWEST PIEDMONT
WHERE 850MB THETA-E AND K INDICES ARE HIGHEST...CLOSER TO WHERE THE
BETTER 0-3KM SHEAR WILL BE FOR MOST OF THE AFTERNOON RELATIVE TO THE
REST OF CENTRAL NORTH CAROLINA...AND WHERE THE RUC SHOWS AN SLIGHT
INCREASE IN 850MB WINDS. TEMPERATURES STILL MOSTLY BELOW NORMAL WITH
HIGHS IN THE 80S.
TONIGHT...EXPECT CHANCES FOR SHOWERS TO DIMINISH WITHIN A FEW HOURS
AFTER SUNSET...THOUGH A TOKEN SLIGHT CHANCE WILL PERSIST GIVEN SUCH
DEEP MOISTURE AND MARGINAL HEIGHT FALLS ALOFT AS THE UPPER LEVEL
WAVE TRACKS INTO THE MID-ATLANTIC TO THE NORTH OF CENTRAL NORTH
CAROLINA. LOWS TONIGHT SIMILAR TO PREVIOUS NIGHTS IN THE 68-73F
RANGE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...
A PRE-FRONTAL TROUGH WILL SET UP OVER THE EASTERN PIEDMONT/SANDHILLS
THURSDAY AS THE MEAN FLOW BECOMES MORE WESTERLY IN THE REAR OF THE
DEPARTING MID/UPPER TROUGH OFFSHORE. THIS SHOULD LEAD TO A REDUCTION
IN THE CHANCE OF CONVECTION EXCEPT ALONG AND EAST OF THE TROUGH
THURSDAY AFTERNOON INTO THE EVENING. QPF OF AROUND 0.25 WILL BE
FORECAST FROM AROUND KFAY NE TO KRDU AND RWI (AREAL AVERAGE)... WITH
0.01 TO THE WEST OVER THE TRIAD REGION. CHANCE POP ALL ZONES BUT
ONLY LOW CHANCE (25-30 PERCENT) NW... TO 50 IN THE SE. HIGHS SHOULD
REBOUND INTO THE MID TO UPPER 80S EXCEPT AROUND 90 IN THE SE. PW`S
WILL ALSO REDUCE TO LESS THAN 1.25 IN THE NW TO AROUND 1.5 IN THE
EAST. DEW POINTS SHOULD MIX OUT INTO THE LOWER TO MID 60S NW...
ENHANCING CONFIDENCE IN THE LOWER POP FORECAST.
THURSDAY NIGHT AND FRIDAY... THE COLD FRONT SHOULD EVENTUALLY
OVERTAKE THE PRE-FRONTAL TROUGH OVER THE SOUTHERN AND EASTERN ZONES
FRIDAY. UNTIL THEN... ANOTHER DAY OF MOSTLY SCATTERED SHOWERS AND
THUNDERSTORMS IS EXPECTED... MAINLY IN THE SOUTH AND EAST (WHERE
PW`S REMAIN NEARLY 1.5 INCHES)... ALONG AND AHEAD OF THE CONVERGENCE
ZONE. THE CHANCE OF SHOWERS/STORMS WILL DIMINISH OVERNIGHT FRIDAY
NIGHT AS THE FRONT SETTLES NEAR THE SC BORDER 12Z SATURDAY. LOWS
65-70. HIGHS FRIDAY WITH A WIND SHIFT TO THE NE... 86-91.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...
A LARGE UPPER TROUGH IS FORECAST TO BE ANCHORED IN THE WESTERN
ATLANTIC AS AN UPPER RIDGE BECOMES ESTABLISHED OVER THE PLAINS THIS
PERIOD. AN ANOMALOUS MEAN NORTHERLY FLOW WILL RESULT FROM THE GREAT
LAKES AND NEW ENGLAND SOUTHWARD DEEP INTO SC/GA. THIS WILL BE A DRY
AND COOL FLOW FOR LATE AUGUST. SURFACE CAA WILL BE MOST PRONOUNCED
SATURDAY AND SUNDAY AS STRONG (~1026+ MB) SURFACE HIGH PRESSURE
BUILDS INTO NC FROM NY/PA. SATURDAY WILL BE THE DAY WITH THE
STRONGEST DAA AS THE MAIN COLD FRONT WILL BEGIN THE DAY NEAR THE SC
BORDER... BUT SHIFT DEEP INTO SC/GA BY LATE SATURDAY. SENSIBLE
WEATHER... PARTLY TO MOSTLY SUNNY SATURDAY. MOSTLY SUNNY SUNDAY.
CLEAR SATURDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE ONLY 80-85
(A GOOD 5-8 DEGREES BELOW NORMAL). LOWS SUNDAY AND MONDAY SHOULD BE
IN THE 50S NORTH... AND LOWER 60S SOUTH (ALMOST 10 DEGREES BELOW
NORMAL).
FOR MONDAY THROUGH TUESDAY... A GRADUAL WARMING TREND BUT STILL DRY.
SURFACE HIGH PRESSURE SHOULD BECOME ANCHORED OVER THE APPALACHIANS
AS THE UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY REMAINS STRONG.
SENSIBLE WEATHER... MOSTLY CLEAR/MOSTLY SUNNY. LOWS 58-65. HIGHS IN
THE 80S.
&&
.AVIATION /14 WEDNESDAY THROUGH SUNDAY/...
AS OF 1025 AM WEDNESDAY...
24-HR TAF PERIOD:
AREAS OF IFR CEILINGS WILL CONTINUE TO SLOWLY LIFT AND IMPROVE TO
MVFR BY 16Z...BECOMING VFR IN MANY AREAS THEREAFTER THOUGH MOISTURE
WILL PERSIST TO ALLOW SCATTERED MVFR CEILINGS INTO THE AFTERNOON.
EXPECT AN INCREASING POTENTIAL FOR SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THIS AFTERNOON...WITH THE BEST CHANCE TOWARD THE TRIAD
AND KINT AND KGSO. SHOWERS SHOULD DIMINISH IN COVERAGE THIS EVENING.
AREAS OF SUB-VFR FOG AND CEILINGS CAN BE EXPECTED AGAIN LATE TONIGHT
INTO THURSDAY MORNING GIVEN A MOIST AIRMASS AND SIMILAR PATTERN.
LOOKING AHEAD:
AN INCREASED POTENTIAL FOR SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
THURSDAY/FRIDAY AS A COLD FRONT SLOWLY APPROACHES FROM THE NORTH.
VFR CONDITIONS AND A NORTHEAST BREEZE ARE EXPECTED TO PREVAIL IN THE
WAKE OF THE FRONT SAT/SUN AS DRY HIGH PRESSURE BUILDS INTO THE
MID-ATLANTIC.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...DJF/VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...DJF/VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
655 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH THE CAROLINAS FROM THE WEST THIS
EVENING...THEN TRACK EAST ACROSS THE REGION ON THURSDAY. SURFACE
HIGH PRESSURE WILL STRENGTHEN ACROSS THE OHIO VALLEY IN THE WAKE OF
THE UPPER LEVEL TROUGH...DRIVING A COLD FRONT SOUTHWARD INTO THE
CAROLINAS DURING THE DAY FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 330 AM WEDNESDAY...
OVERVIEW:
AN UPPER LEVEL LOW CENTERED OVER INDIANA AT 06Z WILL TRACK EASTWARD
INTO EASTERN OH/KY BY 00Z THIS EVENING...AND INTO THE MID-ATLANTIC
BY 12Z THU. SW FLOW ALOFT TODAY WILL STRENGTHEN AND VEER TOWARD THE
WEST ACROSS THE REGION TONIGHT AS THE UPPER LEVEL WAVE TRACKS INTO
THE MID-ATLANTIC...WITH 30 METER H5 HEIGHT FALLS PROGGED BETWEEN
00-12Z THU. THE BERMUDA RIDGE EXTENDING WESTWARD INTO THE CAROLINAS
WILL WEAKEN THIS AFTERNOON INTO TONIGHT AS A LOW-LEVEL TROUGH
ATTENDANT THE AFOREMENTIONED UPPER LEVEL WAVE PROGRESSES INTO THE
MID-ATLANTIC.
PRECIPITATION CHANCES:
SHOWER ACTIVITY EXTENDING WSW-ENE FROM VUJ-HBI-RDU-RWI AT 07Z THIS
MORNING APPEARS TO BE ASSOCIATED WITH WEAK DPVA FROM SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN SW FLOW ALOFT IN THE PRESENCE OF A VERY
MOIST (2.00" PWAT) AND MARGINALLY UNSTABLE (500-1000 J/KG MUCAPE)
ENVIRONMENT. LATEST RAP GUIDANCE SUGGESTS THE AFOREMENTIONED
SHORTWAVE ENERGY SHOULD LIFT NORTHWARD TOWARD THE N/NW PIEDMONT THIS
MORNING...AND EXPECT THE BEST CHANCE OF SHOWER ACTIVITY ALONG AND
NORTH OF THE I-85 CORRIDOR THROUGH 15Z. THIS AFT/EVE INTO TONIGHT...
CONFIDENCE IN CONVECTIVE COVERAGE...TIMING AND LOCATION IS LOWER
THAN NORMAL. GIVEN A VERY MOIST AIRMASS...500-1500 J/KG MLCAPE AT
PEAK HEATING AND A GOOD PROBABILITY OF SMALL AMPLITUDE WAVES IN SW
(INCREASINGLY WSW) FLOW ALOFT ACROSS THE NORTHERN AND WESTERN
PIEDMONT...ONE WOULD EXPECT ABOVE AVERAGE CHANCES FOR PRECIP... ESP
IN THE N/NW PIEDMONT. THE LATEST CONVECTION ALLOWING MODELS DIFFER
IN TIMING AND COVERAGE...BUT ALL SEEM TO INDICATE A BETTER POTENTIAL
FOR CONVECTION IN THE N/NW PIEDMONT AND PERHAPS ALSO IN THE SE
COASTAL PLAIN IN ASSOC/W THE SEABREEZE AND LIGHT ONSHORE FLOW...
WITH THE BEST CHANCE BETWEEN 20-03Z. THIS SEEMS PRETTY REASONABLE
GIVEN THE SETUP. EXPECT CHANCES TO DIMINISH WITHIN A FEW HRS AFTER
SUNSET...THOUGH A TOKEN SLIGHT CHANCE WILL PERSIST GIVEN SUCH DEEP
MOISTURE AND MARGINAL HEIGHT FALLS ALOFT AS THE UPPER LEVEL WAVE
TRACKS INTO THE MID-ATLANTIC TO THE NORTH OF CENTRAL NC.
TEMPERATURES:
HIGHS TODAY SOMEWHAT CHALLENGING AS IN PREVIOUS DAYS WITH TEMPS
PRIMARILY DEPENDENT ON CLOUD COVER AND CONVECTION. EXPECT HIGHS
GENERALLY IN THE LOWER/MID 80S...WARMEST IN THE COASTAL PLAIN AND
COOLEST IN THE N/NW PIEDMONT WHERE HIGHS IN THE UPPER 70S (SIMILAR
TO WINSTON-SALEM YESTERDAY) ARE NOT OUT OF THE QUESTION. LOWS
TONIGHT SIMILAR TO PREVIOUS NIGHTS IN THE 68-73F RANGE. -VINCENT
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...
A PRE-FRONTAL TROUGH WILL SET UP OVER THE EASTERN PIEDMONT/SANDHILLS
THURSDAY AS THE MEAN FLOW BECOMES MORE WESTERLY IN THE REAR OF THE
DEPARTING MID/UPPER TROUGH OFFSHORE. THIS SHOULD LEAD TO A REDUCTION
IN THE CHANCE OF CONVECTION EXCEPT ALONG AND EAST OF THE TROUGH
THURSDAY AFTERNOON INTO THE EVENING. QPF OF AROUND 0.25 WILL BE
FORECAST FROM AROUND KFAY NE TO KRDU AND RWI (AREAL AVERAGE)... WITH
0.01 TO THE WEST OVER THE TRIAD REGION. CHANCE POP ALL ZONES BUT
ONLY LOW CHANCE (25-30 PERCENT) NW... TO 50 IN THE SE. HIGHS SHOULD
REBOUND INTO THE MID TO UPPER 80S EXCEPT AROUND 90 IN THE SE. PW`S
WILL ALSO REDUCE TO LESS THAN 1.25 IN THE NW TO AROUND 1.5 IN THE
EAST. DEW POINTS SHOULD MIX OUT INTO THE LOWER TO MID 60S NW...
ENHANCING CONFIDENCE IN THE LOWER POP FORECAST.
THURSDAY NIGHT AND FRIDAY... THE COLD FRONT SHOULD EVENTUALLY
OVERTAKE THE PRE-FRONTAL TROUGH OVER THE SOUTHERN AND EASTERN ZONES
FRIDAY. UNTIL THEN... ANOTHER DAY OF MOSTLY SCATTERED SHOWERS AND
THUNDERSTORMS IS EXPECTED... MAINLY IN THE SOUTH AND EAST (WHERE
PW`S REMAIN NEARLY 1.5 INCHES)... ALONG AND AHEAD OF THE CONVERGENCE
ZONE. THE CHANCE OF SHOWERS/STORMS WILL DIMINISH OVERNIGHT FRIDAY
NIGHT AS THE FRONT SETTLES NEAR THE SC BORDER 12Z SATURDAY. LOWS
65-70. HIGHS FRIDAY WITH A WIND SHIFT TO THE NE... 86-91.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...
A LARGE UPPER TROUGH IS FORECAST TO BE ANCHORED IN THE WESTERN
ATLANTIC AS AN UPPER RIDGE BECOMES ESTABLISHED OVER THE PLAINS THIS
PERIOD. AN ANOMALOUS MEAN NORTHERLY FLOW WILL RESULT FROM THE GREAT
LAKES AND NEW ENGLAND SOUTHWARD DEEP INTO SC/GA. THIS WILL BE A DRY
AND COOL FLOW FOR LATE AUGUST. SURFACE CAA WILL BE MOST PRONOUNCED
SATURDAY AND SUNDAY AS STRONG (~1026+ MB) SURFACE HIGH PRESSURE
BUILDS INTO NC FROM NY/PA. SATURDAY WILL BE THE DAY WITH THE
STRONGEST DAA AS THE MAIN COLD FRONT WILL BEGIN THE DAY NEAR THE SC
BORDER... BUT SHIFT DEEP INTO SC/GA BY LATE SATURDAY. SENSIBLE
WEATHER... PARTLY TO MOSTLY SUNNY SATURDAY. MOSTLY SUNNY SUNDAY.
CLEAR SATURDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE ONLY 80-85
(A GOOD 5-8 DEGREES BELOW NORMAL). LOWS SUNDAY AND MONDAY SHOULD BE
IN THE 50S NORTH... AND LOWER 60S SOUTH (ALMOST 10 DEGREES BELOW
NORMAL).
FOR MONDAY THROUGH TUESDAY... A GRADUAL WARMING TREND BUT STILL DRY.
SURFACE HIGH PRESSURE SHOULD BECOME ANCHORED OVER THE APPALACHIANS
AS THE UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY REMAINS STRONG.
SENSIBLE WEATHER... MOSTLY CLEAR/MOSTLY SUNNY. LOWS 58-65. HIGHS IN
THE 80S.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 645 AM WEDNESDAY...
24-HR TAF PERIOD:
AS OF 11Z THIS MORNING...CONDITIONS RANGED FROM VFR AT THE INT/GSO
TERMINALS TO IFR (CEILINGS) AT RDU TO VLIFR (FOG) AT FAY/RWI. LOW
CEILINGS AND FOG WILL GRADUALLY LIFT AND IMPROVE TO MVFR BETWEEN
12-14Z...BECOMING VFR IN MOST AREAS BY 14-16Z...THOUGH ISOLD/SCT
SHOWER ACTIVITY MAY ALLOW SUB-VFR CONDITIONS TO PERSIST INTO EARLY
AFTERNOON...PRIMARILY AT THE INT/GSO TERMINALS. EXPECT AN INCREASING
POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON (18-21Z)...
WITH THE BEST CHANCE LATE THIS AFT/EVE BETWEEN 21-04Z AS AN UPPER
LEVEL DISTURBANCES TRACKS EAST INTO THE MID-ATLANTIC. AREAS OF
SUB-VFR FOG AND CEILINGS CAN BE EXPECTED AGAIN LATE TONIGHT INTO
THURSDAY MORNING GIVEN A MOIST AIRMASS AND SIMILAR PATTERN.
LOOKING AHEAD:
AN INCREASED POTENTIAL FOR SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
THURSDAY/FRIDAY AS A COLD FRONT SLOWLY APPROACHES FROM THE NORTH.
VFR CONDITIONS AND A NORTHEAST BREEZE ARE EXPECTED TO PREVAIL IN THE
WAKE OF THE FRONT SAT/SUN AS DRY HIGH PRESSURE BUILDS INTO THE
MID-ATLANTIC. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
356 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL APPROACH THE CAROLINAS FROM THE WEST THIS
EVENING...THEN TRACK EAST ACROSS THE REGION ON THURSDAY. SURFACE
HIGH PRESSURE WILL STRENGTHEN ACROSS THE OHIO VALLEY IN THE WAKE OF
THE UPPER LEVEL TROUGH...DRIVING A COLD FRONT SOUTHWARD INTO THE
CAROLINAS DURING THE DAY FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 330 AM WEDNESDAY...
OVERVIEW:
AN UPPER LEVEL LOW CENTERED OVER INDIANA AT 06Z WILL TRACK EASTWARD
INTO EASTERN OH/KY BY 00Z THIS EVENING...AND INTO THE MID-ATLANTIC
BY 12Z THU. SW FLOW ALOFT TODAY WILL STRENGTHEN AND VEER TOWARD THE
WEST ACROSS THE REGION TONIGHT AS THE UPPER LEVEL WAVE TRACKS INTO
THE MID-ATLANTIC...WITH 30 METER H5 HEIGHT FALLS PROGGED BETWEEN
00-12Z THU. THE BERMUDA RIDGE EXTENDING WESTWARD INTO THE CAROLINAS
WILL WEAKEN THIS AFTERNOON INTO TONIGHT AS A LOW-LEVEL TROUGH
ATTENDANT THE AFOREMENTIONED UPPER LEVEL WAVE PROGRESSES INTO THE
MID-ATLANTIC.
PRECIPITATION CHANCES:
SHOWER ACTIVITY EXTENDING WSW-ENE FROM VUJ-HBI-RDU-RWI AT 07Z THIS
MORNING APPEARS TO BE ASSOCIATED WITH WEAK DPVA FROM SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN SW FLOW ALOFT IN THE PRESENCE OF A VERY
MOIST (2.00" PWAT) AND MARGINALLY UNSTABLE (500-1000 J/KG MUCAPE)
ENVIRONMENT. LATEST RAP GUIDANCE SUGGESTS THE AFOREMENTIONED
SHORTWAVE ENERGY SHOULD LIFT NORTHWARD TOWARD THE N/NW PIEDMONT THIS
MORNING...AND EXPECT THE BEST CHANCE OF SHOWER ACTIVITY ALONG AND
NORTH OF THE I-85 CORRIDOR THROUGH 15Z. THIS AFT/EVE INTO TONIGHT...
CONFIDENCE IN CONVECTIVE COVERAGE...TIMING AND LOCATION IS LOWER
THAN NORMAL. GIVEN A VERY MOIST AIRMASS...500-1500 J/KG MLCAPE AT
PEAK HEATING AND A GOOD PROBABILITY OF SMALL AMPLITUDE WAVES IN SW
(INCREASINGLY WSW) FLOW ALOFT ACROSS THE NORTHERN AND WESTERN
PIEDMONT...ONE WOULD EXPECT ABOVE AVERAGE CHANCES FOR PRECIP... ESP
IN THE N/NW PIEDMONT. THE LATEST CONVECTION ALLOWING MODELS DIFFER
IN TIMING AND COVERAGE...BUT ALL SEEM TO INDICATE A BETTER POTENTIAL
FOR CONVECTION IN THE N/NW PIEDMONT AND PERHAPS ALSO IN THE SE
COASTAL PLAIN IN ASSOC/W THE SEABREEZE AND LIGHT ONSHORE FLOW...
WITH THE BEST CHANCE BETWEEN 20-03Z. THIS SEEMS PRETTY REASONABLE
GIVEN THE SETUP. EXPECT CHANCES TO DIMINISH WITHIN A FEW HRS AFTER
SUNSET...THOUGH A TOKEN SLIGHT CHANCE WILL PERSIST GIVEN SUCH DEEP
MOISTURE AND MARGINAL HEIGHT FALLS ALOFT AS THE UPPER LEVEL WAVE
TRACKS INTO THE MID-ATLANTIC TO THE NORTH OF CENTRAL NC.
TEMPERATRUES:
HIGHS TODAY SOMEWHAT CHALLENGING AS IN PREVIOUS DAYS WITH TEMPS
PRIMARILY DEPENDENT ON CLOUD COVER AND CONVECTION. EXPECT HIGHS
GENERALLY IN THE LOWER/MID 80S...WARMEST IN THE COASTAL PLAIN AND
COOLEST IN THE N/NW PIEDMONT WHERE HIGHS IN THE UPPER 70S (SIMILAR
TO WINSTON-SALEM YESTERDAY) ARE NOT OUT OF THE QUESTION. LOWS
TONIGHT SIMILAR TO PREVIOUS NIGHTS IN THE 68-73F RANGE. -VINCENT
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...
A PRE-FRONTAL TROUGH WILL SET UP OVER THE EASTERN PIEDMONT/SANDHILLS
THURSDAY AS THE MEAN FLOW BECOMES MORE WESTERLY IN THE REAR OF THE
DEPARTING MID/UPPER TROUGH OFFSHORE. THIS SHOULD LEAD TO A REDUCTION
IN THE CHANCE OF CONVECTION EXCEPT ALONG AND EAST OF THE TROUGH
THURSDAY AFTERNOON INTO THE EVENING. QPF OF AROUND 0.25 WILL BE
FORECAST FROM AROUND KFAY NE TO KRDU AND RWI (AREAL AVERAGE)... WITH
0.01 TO THE WEST OVER THE TRIAD REGION. CHANCE POP ALL ZONES BUT
ONLY LOW CHANCE (25-30 PERCENT) NW... TO 50 IN THE SE. HIGHS SHOULD
REBOUND INTO THE MID TO UPPER 80S EXCEPT AROUND 90 IN THE SE. PW`S
WILL ALSO REDUCE TO LESS THAN 1.25 IN THE NW TO AROUND 1.5 IN THE
EAST. DEW POINTS SHOULD MIX OUT INTO THE LOWER TO MID 60S NW...
ENHANCING CONFIDENCE IN THE LOWER POP FORECAST.
THURSDAY NIGHT AND FRIDAY... THE COLD FRONT SHOULD EVENTUALLY
OVERTAKE THE PRE-FRONTAL TROUGH OVER THE SOUTHERN AND EASTERN ZONES
FRIDAY. UNTIL THEN... ANOTHER DAY OF MOSTLY SCATTERED SHOWERS AND
THUNDERSTORMS IS EXPECTED... MAINLY IN THE SOUTH AND EAST (WHERE
PW`S REMAIN NEARLY 1.5 INCHES)... ALONG AND AHEAD OF THE CONVERGENCE
ZONE. THE CHANCE OF SHOWERS/STORMS WILL DIMINISH OVERNIGHT FRIDAY
NIGHT AS THE FRONT SETTLES NEAR THE SC BORDER 12Z SATURDAY. LOWS
65-70. HIGHS FRIDAY WITH A WIND SHIFT TO THE NE... 86-91.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...
A LARGE UPPER TROUGH IS FORECAST TO BE ANCHORED IN THE WESTERN
ATLANTIC AS AN UPPER RIDGE BECOMES ESTABLISHED OVER THE PLAINS THIS
PERIOD. AN ANOMALOUS MEAN NORTHERLY FLOW WILL RESULT FROM THE GREAT
LAKES AND NEW ENGLAND SOUTHWARD DEEP INTO SC/GA. THIS WILL BE A DRY
AND COOL FLOW FOR LATE AUGUST. SURFACE CAA WILL BE MOST PRONOUNCED
SATURDAY AND SUNDAY AS STRONG (~1026+ MB) SURFACE HIGH PRESSURE
BUILDS INTO NC FROM NY/PA. SATURDAY WILL BE THE DAY WITH THE
STRONGEST DAA AS THE MAIN COLD FRONT WILL BEGIN THE DAY NEAR THE SC
BORDER... BUT SHIFT DEEP INTO SC/GA BY LATE SATURDAY. SENSIBLE
WEATHER... PARTLY TO MOSTLY SUNNY SATURDAY. MOSTLY SUNNY SUNDAY.
CLEAR SATURDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE ONLY 80-85
(A GOOD 5-8 DEGREES BELOW NORMAL). LOWS SUNDAY AND MONDAY SHOULD BE
IN THE 50S NORTH... AND LOWER 60S SOUTH (ALMOST 10 DEGREES BELOW
NORMAL).
FOR MONDAY THROUGH TUESDAY... A GRADUAL WARMING TREND BUT STILL DRY.
SURFACE HIGH PRESSURE SHOULD BECOME ANCHORED OVER THE APPALACHIANS
AS THE UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY REMAINS STRONG.
SENSIBLE WEATHER... MOSTLY CLEAR/MOSTLY SUNNY. LOWS 58-65. HIGHS IN
THE 80S.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 230 AM WEDNESDAY...
24-HR TAF PERIOD:
A WIDE VARIETY OF CONDITIONS ARE EXPECTED ACROSS CENTRAL NC THIS
MORNING...RANGING FROM LIFR CEILINGS/FOG AT THE FAY TERMINAL TO MVFR
CEILINGS AND LIGHT RAIN AT THE INT/GSO TERMINALS TO VFR CEILINGS
WITH OCCASIONAL MVFR CEILINGS AT THE RDU/RWI TERMINALS. SUB-VFR
CONDITIONS WILL IMPROVE TO MVFR AND EVENTUALLY VFR IN MOST AREAS
BETWEEN 12-16Z AS INSOLATION/MIXING STRENGTHENS...THOUGH ISOLD/SCT
SHOWER ACTIVITY MAY ALLOW MVFR CONDITIONS TO PERSIST A WHILE
LONGER...PRIMARILY AT THE INT/GSO TERMINALS. EXPECT AN INCREASING
POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON
(18-21Z)...WITH THE BEST CHANCE LATE THIS AFT/EVE BETWEEN 21-04Z AS
AN UPPER LEVEL DISTURBANCES TRACKS EAST INTO THE MID-ATLANTIC. AREAS
OF SUB-VFR FOG AND CEILINGS CAN BE EXPECTED AGAIN LATE TONIGHT INTO
THURSDAY MORNING GIVEN A MOIST AIRMASS AND SIMILAR PATTERN.
LOOKING AHEAD:
AN INCREASED POTENTIAL FOR SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
THURSDAY/FRIDAY AS A COLD FRONT SLOWLY APPROACHES FROM THE NORTH.
VFR CONDITIONS AND A NORTHEAST BREEZE ARE EXPECTED TO PREVAIL IN THE
WAKE OF THE FRONT SAT/SUN AS DRY HIGH PRESSURE BUILDS INTO THE
MID-ATLANTIC. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
946 PM EDT THU AUG 22 2013
.SYNOPSIS...
COLD FRONT TONIGHT AND FRIDAY. HIGH PRESSURE FOR THE WEEKEND.
SEVERAL WEAK UPPER DISTURBANCES NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
945 PM UPDATE...NO MAJOR CHANGES WERE NEEDED TO THE PREVIOUS
FORECAST. HAVE DECIDED NOT TO CANCEL THE FLOOD WATCH EARLY. BULK
OF CONVECTION THIS EVENING IS WINDING DOWN...BUT THERE IS STILL
ACTIVITY TO OUR NORTH ACROSS OHIO/PA ASSOCIATED WITH THE COLD
FRONT...WHICH WILL MOVE INTO THE CWA BY EARLY TOMORROW. HRRR IS
STILL INDICATING A LINE FORMING AS THIS FRONTAL BOUNDARY PUSHES
INTO THE CWA. SLOWED DOWN THE PROGRESSION OF POPS TOMORROW MORNING
FROM NORTH TO SOUTH AS THE FRONTAL BOUNDARY PUSHES IN BASED ON
TIMING OF THE HRRR BY JUST A BIT. WILL ALLOW THE NIGHT SHIFT TO
EVALUATE WHETHER OR NOT THE WATCH CAN BE DROPPED EARLY.
PREVIOUS DISCUSSION FOLLOWS...
MODELS AGREE COLD FRONT WILL NOT ARRIVE UNTIL EARLY FRIDAY
MORNING...AND THEN QUICKLY MOVE SOUTHEAST DURING FRIDAY. PRIOR TO
THAT...MODELS FOCUS ON BAND OF HIGH RH`S DROPPING SOUTHEAST IN
NORTHWEST FLOW ALOFT...WELL AHEAD OF THE COLD FRONT FOR THE BEST
CHANCE OF CONVECTION. THERE ARE TIMING DIFFERENCES IN THIS WITH
THE NAM BEING SLOWEST TO MOVE THIS THRU AND COINCIDE CLOSER TO THE
COLD FRONT...TO THE OTHER MODELS BEING GENERALLY FASTER AND WELL
AHEAD OF THE COLD FRONT. ALL THIS SUGGESTS THE BEST CHANCE OF POPS
WILL MOSTLY BE SOMETIME AFTER 00Z...OUTSIDE THE MORE DISORGANIZED
AFTERNOON AND EVENING CONVECTION THAT IS CURRENTLY BUBBLING UP. ON
THE OTHER HAND...LATEST RADAR AND SATELLITE SUGGESTS AN ORGANIZED
ENE-WSW ORIENTED BAND OF CONVECTION ALREADY FORMING JUST NORTH OF
OUR AREA. ALONG WITH THE TENDENCY FOR CONVECTIVE COMPLEXES TO FORM
IN THE AFTERNOON AND ORGANIZE...FOLLOWED BY ACCELERATING MORE THAN
MODELS NORMALLY SUGGEST...WILL GO WITH A QUICKER SCENARIO OF
HAVING THIS OBSERVED SEMI ORGANIZED BAND OF CONVECTION INTENSIFY
AND DROP SOUTHEAST ACROSS MUCH OF THE AREA LATER THIS AFTERNOON
AND EARLY TONIGHT. THEREAFTER...SOME UNCERTAINTY GIVEN WHAT THE
CONVECTIVE COMPLEX CURRENTLY AROUND CHICAGO WILL DO FOR THE
OVERNIGHT HOURS. SO...WILL KEEP CHANCE POPS IN MOST OF THE
NIGHT...ESPECIALLY SINCE THE MODELS ARE APPARENTLY KEYING IN ON
THIS OR ITS SUPPORTING SHORT WAVE TO RIDE ALONG THE BAND OF HIGH
RH. THIS SUPPORTING SHORT WAVE WILL BE THE ONE TO PUSH THE FRONT
SOUTHEAST ACROSS THE AREA FRIDAY.
WITH PW`S AROUND 2 INCHES INTO EARLY TONIGHT ASSOCIATED WITH THIS
FIRST CONVECTIVE BATCH DROPPING THROUGH...AND PW`S STILL ABOVE
NORMAL UNTIL THE FRONT ARRIVES FRIDAY MORNING...HAVE POSTED A FLASH
FLOOD WATCH UNTIL 11 AM FRIDAY MORNING FOR THE MOST VULNERABLE AREAS
PER PRIOR RAINFALL AND FFG.
TAKING A BLEND DO MODEL GUIDANCE FOR TEMPS THIS PERIOD.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
COLD FRONT SHOULD BE JUST CLEARING SW VA ZONES AT THE START OF THE
PERIOD...WITH PRECIP COMING TO AND END ACROSS SOUTHERN ZONES AS
WELL. DRIER AIR ARRIVES BEHIND THE FRONT...WITH A NICE WEEKEND IN
STORE AS A SURFACE HIGH DROPS THROUGH THE EASTERN GREAT LAKES DOWN
THROUGH PA. NAM TRIES TO PRINT OUT SOME QPF WITH CAA SHOWERS ACROSS
THE MOUNTAINS SATURDAY...BUT DO NOT THINK ENOUGH MOISTURE WILL BE LEFT
TO WORK WITH...PLUS HAVE INCREASING SURFACE PRESSURE AS HIGH
APPROACHES. SO LEFT POPS OUT.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
LONG TERM DOMINATED BY UPPER RIDGE OVER THE SOUTHERN PLAINS. THIS
LEAVES US IN NW FLOW ON THE NORTHEAST EDGE OF THE RIDGE...AND WITH
SEVERAL WEAK VORT MAXES CRESTING THE RIDGE AND DROPPING ACROSS THE
REGION HAVE CHANCE POPS IN FORECAST. FOR NOW TIED TO DIURNAL
TREND...BUT EVENTUALLY MAY BE ABLE TO HOP MORE ON VORT MAX TIMING.
TEMPS WILL RETURN TO ABOVE NORMAL WITH THE THE UPPER RIDGE TO THE
WEST. WARMEST DAYS MAY BE TOWARD THE END OF THE WEEK AS HEIGHTS
SLIGHTLY RISE AS THE 500MB HIGH DRIFTS EAST FROM KS INTO MO.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
00Z FRIDAY THRU 00Z SATURDAY...
COLD FRONT AT 00Z FRIDAY STILL WELL TO THE NORTH ACROSS NORTHERN
OHIO. STILL EXPECTED TO ENTER SOUTHEAST OHIO ZONES AROUND 06-09Z.
CONVECTION THIS EVENING OUT AHEAD OF THE FRONT SHOULD GRADUALLY DIE
OFF/MOVE EAST OF THE WV MOUNTAINS AFTER 03-04Z...WITH A REVAMP IN
ACTIVITY AFTER 08Z...PARTICULARLY ACROSS SOUTHEAST OHIO AND
NORTHERN WV AS COLD FRONT ENTERS THE AREA. EXPECT BRIEF MVFR
CONDITIONS AND GUSTY WINDS IN VICINITY OF STORMS.
OVERNIGHT...GENERALLY AFTER 06Z...COULD SEE EITHER WIDESPREAD
STRATUS...OR FOG DEVELOPMENT...WITH MVFR AND ISOLD IFR
CONDITIONS...GENERALLY IMPROVING TO VFR AFTER 13-14Z FRIDAY.
SHOWERS AND THUNDERSTORMS REVAMPING BACK UP AGAIN AFTER 16Z
FRIDAY...WITH MVFR/IFR CONDITIONS IN VICINITY OF STORMS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF CONVECTION THRU THE PERIOD DEPENDS
HIGHLY ON MESOSCALE COMPLEXES COMPLEXES. FOG WILL VARY DEPENDING ON
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.
DATE FRI 08/23/13
UTC 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
EDT 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09
CRW CONSISTENCY H H H H H H L L L L M H
HTS CONSISTENCY H H H H H H L L L L M H
BKW CONSISTENCY M H H M M H H H H H H H
EKN CONSISTENCY M H M H H H L H M M L M
PKB CONSISTENCY H H H M H H L L L L M H
CKB CONSISTENCY H H H M M H L L L L H H
AFTER 00Z SATURDAY...
AREAS OF IFR IN DENSE FOG/LOW STRATUS MOST MORNINGS THIS
WEEK...ESPECIALLY ALONG THE RIVERS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR WVZ006>011-
013>020-026>032-038>040-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/MZ
NEAR TERM...JMV/SL
SHORT TERM...MZ
LONG TERM...MZ
AVIATION...SL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
521 PM EDT WED AUG 21 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC STATES WILL MAINTAIN
CONTROL OF OUR WEATHER INTO THURSDAY. A COLD FRONT WILL CROSS THE
REGION LATE THURSDAY INTO EARLY FRIDAY...FOLLOWED BY CANADIAN HIGH
PRESSURE. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE ALONG AND
AHEAD OF THE FRONT...FOLLOWED BY SUNNY AND DRIER CONDITIONS FRIDAY
INTO THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
REGIONAL RADAR LOOP SHOWING CONVECTION INCREASING IN COVERAGE AND
SPREADING NORTH OF THE MASON DIXON LINE IN RESPONSE TO DIURNAL
HEATING AND INCREASING LG SCALE FORCING AHEAD OF UPPER LOW
APPROACHING FROM OHIO. MDL SIMULATED REFLECTIVITY...WHICH USUALLY
PERFORMS WELL IN STRONGLY FORCED SCENARIOS SUCH AS THIS...SUGGESTS
SHRA AND TSRA WILL OVERSPREAD THE SOUTHERN COUNTIES THIS
EVENING...WITH THE GREATEST COVERAGE BTWN 23Z AND 02Z. HAVE
ADJUSTED POPS ACCORDINGLY WITH POPS INCREASED TO ARND 50 PCT OVR
THE SOUTHERN COUNTIES. SPC MESOANALYSIS INDICATES CAPES ARND 2500
J/KG LATE THIS AFTN...SO WILL HAVE TO WATCH FOR A LOCALLY SVR
PULSE TYPE STORM ACROSS THE SOUTH THIS EVENING. RAP SHOWS WIND
SHEAR IS WEAK...SO ANYTHING MORE THAN ISOLD SVR UNLIKELY.
WILL GRADUALLY TAPER OFF POPS TONIGHT...AS WEAKENING SHORTWAVE
MOVES INTO THE AREA AND BLYR COOLS/STABILIZES. BLYR ACROSS
NORTHERN PA WILL LIKELY REMAIN TOO DRY TO SUPPORT ANY CONVECTION.
HOWEVER...WILL MENTION AT LEAST A SLIGHT CHC ACROSS ALL OF CENTRAL
AND SOUTHERN PA...WHERE SOUTHERLY FLOW AHEAD OF SHORTWAVE WILL
PUSH DWPTS WELL INTO THE 60S.
TONIGHT WILL BE MILDER THAN RECENT NIGHTS...WITH HIGH DEWPOINTS
AND SCT/BKN CLOUD COVER.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
A PERIOD OF WEAK RIDGING SHOULD BRING A PERIOD OF DRY CONDITIONS
TO MOST OF CENTRAL PENN ON THURS BEFORE AN APPROACHING COLD FRONT
FROM THE GLAKES BRINGS ANOTHER THREAT OF CONVECTION.
A RIBBON OF HIGHER PWATS BETWEEN 1.5 AND 1.75 INCHES AND SLIGHTLY
STEEPER MID-LEVEL LAPSE RATES SHOULD SUPPORT SCT SHRA/TSRA
DEVELOPING ACROSS THE NW MTNS THURSDAY AFTN AND SLIDING SE THRU
THE EVENING AND EARLY OVERNIGHT.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
OVERVIEW...THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS IN VERY
GOOD AGREEMENT IN THE LARGE SCALE MEAN FLOW PATTERN CONSISTING OF
A BUILDING/STRONG UPPER RIDGE OVER THE PLAINS/MS VLY WITH TROUGHS
JUST OFF THE WEST AND EAST COASTS. HOWEVER...THE PCPN PATTERN OVER
THE LOCAL AREA WILL BE MODULATED BY SHORTWV IMPULSES DIVING ESEWD
DOWN THE NERN/FRONT SIDE OF THE RIDGE WITHIN A NWLY FLOW ALOFT.
THEREFORE DESPITE ABOVE AVG CONFIDENCE IN THE MEAN PATTERN...THE
SMALLER SCALE EMBEDDED SYSTEM TIMING AND LOCAL QPF/SENSIBLE WX
IMPACT IS MORE UNCERTAIN. AS SUCH...THE FINAL DAY 3-7 GRIDS WERE
DERIVED USING A CONSENSUS BLEND IN AN EFFORT TO MITIGATE THE LOWER
CONFIDENCE IN THE SFC DETAILS AND TO BEHOLD REASONABLE CONTINUITY
THE FCST.
HIGHLIGHTS...PUSH OF ABNORMALLY DRY AIR WITH BELOW NORMAL PWS
BEHIND THE THUR NGT FROPA APPEARS DELAYED BY ABOUT 6 HRS ON THE
12Z CYCLE...SUGGESTING A LOW CHC FOR SHOWERS ALONG THE SRN TIER
ZONES EARLY FRI. OTHERWISE...A MODIFIED CANADIAN HIGH PRESSURE
SYSTEM WILL DOMINATE THE PATTERN THROUGH THE WEEKEND..BRINGING
RELATIVELY COOL NIGHTS WITH VALLEY FOG AND COMFORTABLE HUMIDITY
DURING THE DAY. EXPECT A MORE UNSETTLED AND INCREASINGLY HUMID
PATTERN TO EVOLVE THRU THE FIRST PART OF NEXT WEEK..AS THE FOCUS
SHIFTS TO UPPER-LEVEL DISTURBANCES CRESTING THE PLAINS RIDGE AND
DIVING ESEWD THRU THE GREAT LAKES TAKING AIM ON THE NE STATES.
MODELS SUGGEST THIS ENERGY MAY TRIGGER ONE OR MORE ORGANIZED TSTM
COMPLEXES AS THEY ROLL DOWN THE FRONT-SIDE OF THE RIDGE.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
WIDELY SCT SHRA/TSRA WILL CONTINUE TO DEVELOP THIS AFTN ACROSS
FAR SRN PA. ADDED VCSH TO ALL SRN TAF SITES THRU THIS EVE.
A FEW SHRA/TSRA REMAIN POSS INTO TONIGHT...PRIMARILY ACROSS SRN
PA. SOME LIGHT FOG/HAZE IS POSSIBLE AS WELL.
SLIGHTLY BETTER CHC FOR SHRA/TSRA STATEWIDE ON THURS AS A COLD
FRONT APPROACHES FROM THE GREAT LAKES. THIS FRONT SHOULD PASS
SOUTH OF THE REGION THURS NIGHT...WITH IMPROVING FLYING CONDS FOR
FRI INTO THIS WEEKEND.
OUTLOOK...
THU-THU NIGHT...MVFR POSSIBLE WITH SCT SHRA/TSRA.
FRI-MON...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...EVANEGO
NEAR TERM...FITZGERALD/EVANEGO
SHORT TERM...EVANEGO
LONG TERM...STEINBUGL
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1252 PM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION ACROSS CENTRAL SOUTH DAKOTA RUNNING INTO THE CAP AS IT
WORKS EAST OF THE JAMES RIVER VALLEY. THE DYING CONVECTION HAS
PRODUCED HEAT BURSTS OVER THE PAST FEW HOURS IN BOTH CHAMBERLAIN
AND MITCHELL. HRRR SHOWS CONVECTION DEVELOPING IN THE NEXT FEW
HOURS ALONG WEAK BOUNDARY SLOWLY EAKING SOUTH THROUGH THE NORTHERN
CWA THIS MORNING. HAVE SOME 20 POPS TO COVER THE POTENTIAL OF
THIS...BUT STILL NOT CONVINCED THAT STORMS ARE GOING TO BE ABLE TO
GET AROUND THE CAP. AHEAD OF THE BOUNDARY...WILL BE ANOTHER WARM
AND HUMID DAY WITH HEAT INDEX VALUES A FEW DEGREES SHY OF ADVISORY
CRITERIA. MODELS INDICATE THAT A WEAK SHORTWAVE MOVING OUT OF
WESTERN SOUTH DAKOTA THIS MORNING MAY TRY TO INTERACT WITH THE
BOUNDARY POTENTIALLY PRODUCING THUNDERSTORMS ACROSS MAINLY
NORTHWEST IOWA. STEEP MID LEVEL LAPSE RATES LEAD TO MOST UNSTABLE
CAPE VALUES OF 2000-2500 J/KG....THOUGH STILL FAIRLY STRONG CAP TO
OVERCOME. IF STORMS ARE ABLE TO DEVELOP...VEERING PROFILE MAY AID
IN STORM ORGANIZATION...THOUGH WIND SPEEDS ARE SOMEWHAT WEAK. AS
SUCH...THE SEE TEXT SEVERE WEATHER OUTLOOK SEEMS REASONABLE WITH
CHANCE OF CONVECTION BEING VERY CONDITIONAL.
BOUNDARY IS EXPECTED TO STALL ACROSS THE SOUTHERN EDGE OF THE
FORECAST AREA TONIGHT CREATING ADDITIONAL CHANCES FOR
THUNDERSTORMS. TRIMMED BACK THE NORTHERN EXTENT OF POPS TONIGHT
WITH DRIER AIRMASS BEHIND THE FRONT MAKING IT DIFFICULT FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP. EXPECT QUITE A THERMAL
GRADIENT ACROSS THE AREA FROM THE UPPER 50S ACROSS SOUTHWEST
MINNESOTA TO NEAR 70 ACROSS THE SOUTHERN EDGE OF THE FORECAST AREA
NEAR THE FRONT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION CHANCES ARE SOMEWHAT TRICKY ON THURSDAY AS
BOUNDARY/THEATE ADVECTION LIFTS BACK TO THE NORTH. FORCING APPEARS
TO OUTRUN THE MOISTURE...AS LOW LEVEL MOISTURE APPEARS TO BE HARD TO COME
BY ACROSS THE NORTHERN CWA. THEREFORE...HAVE LIMITED CONVECTION CHANCES TO
SOUTHERN EDGE OF THE FORECAST AREA WHERE THE SLIGHTLY DEEPER
MOISTURE EXISTS.
HUMID CONDITIONS RETURN ON FRIDAY AS THE GULF OPENS BACK UP WITH
SOUTHERLY FLOW FEEDING INTO THE PLAINS. 850 HPA TEMPS WARM TO NEAR
20C DURING THE DAY LEADING TO HIGHS IN THE 80S TO NEAR 90.
STRONG LOW LEVEL JET OF 40-50 KNOTS IS EXPECTED TO DEVELOP FRIDAY
NIGHT. HAVE RAISED LOWS IN SW MN ALONG THE BUFFALO RIDGE AS
EXPOSED LOCATIONS WILL LIKELY HAVE TROUBLE COOLING OFF.
IN THE EXTENDED...SATURDAY THROUGH TUESDAY OF NEXT WEEK...A BROAD
UPPER LEVEL RIDGE REMAINS PARKED OVER THE CENTRAL PORTION OF THE
U.S. THROUGH THE PERIOD. WITH OUR AREA IN A SOUTHERLY FLOW IN
RESPONSE TO SURFACE RIDGING PARKED OVER THE EASTERN PART OF THE
NATION...MUCH ABOVE NORMAL TEMPERATURES WILL BE THE RULE. WITH
PROGGED 850 MB TEMPERATURES IN THE MID AND UPPER 20S C HIGHS WILL
GENERALLY RUN LOWER TO MID 90S EACH DAY...WITH HUMIDITY RETURNING AS
DEWPOINTS CLIMB INTO THE MID AND UPPER 60S. 925 MB TEMPERATURES
WOULD SUPPORT LOWS IN THE UPPER 60S TO LOWER 70S. IN TERMS OF
PRECIPITATION CHANCES DURING THE EXTENDED...MODELS HAVING USUAL
DIFFERENCES WITH REGARD TO MINOR SHORTWAVES ROUNDING THE UPPER THE
LEVEL RIDGE...THOUGH KEPT IT DRY THROUGH THE PERIOD WITH SUPPORT
FROM BOTH THE 00Z ECMWF AND GEM.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1245 PM CDT WED AUG 21 2013
PREDOMINATE VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SCATTERED
LIGHT HIGH BASED CONVECTION WILL CONTINUE TO PUSH EASTWARD THROUGH
AROUND 21Z. SLOW MOVING WEAK FRONT SINKING SOUTHEAST THROUGH OUR
EASTERN FORECAST AREA WILL BECOME QUITE DIFFUSE AND EXIT THE AREA BY
AROUND 09Z. ADDITIONAL CONVECTION IS EXPECTED TO DEVELOP AFTER 21Z
ALONG THE FRONT AND IS EXPECTED TO TRACK PRIMARILY THROUGH THE
MISSOURI VALLEY AND NORTHWEST IOWA. ACTIVITY WILL BE SCATTERED AND IS
MOST LIKELY TO IMPACT KSUX. LEFT A TEMPO MENTION OF BRIEF MVFR
VISIBILITY IN THE THUNDERSTORM LATE THIS EVENING. SOME STORMS COULD
POTENTIALLY PRODUCE SQUALL WIND CONDITIONS THIS EVENING INTO THE
EARLY MORNING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...JM
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
633 AM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION ACROSS CENTRAL SOUTH DAKOTA RUNNING INTO THE CAP AS IT
WORKS EAST OF THE JAMES RIVER VALLEY. THE DYING CONVECTION HAS
PRODUCED HEAT BURSTS OVER THE PAST FEW HOURS IN BOTH CHAMBERLAIN
AND MITCHELL. HRRR SHOWS CONVECTION DEVELOPING IN THE NEXT FEW
HOURS ALONG WEAK BOUNDARY SLOWLY EAKING SOUTH THROUGH THE NORTHERN
CWA THIS MORNING. HAVE SOME 20 POPS TO COVER THE POTENTIAL OF
THIS...BUT STILL NOT CONVINCED THAT STORMS ARE GOING TO BE ABLE TO
GET AROUND THE CAP. AHEAD OF THE BOUNDARY...WILL BE ANOTHER WARM
AND HUMID DAY WITH HEAT INDEX VALUES A FEW DEGREES SHY OF ADVISORY
CRITERIA. MODELS INDICATE THAT A WEAK SHORTWAVE MOVING OUT OF
WESTERN SOUTH DAKOTA THIS MORNING MAY TRY TO INTERACT WITH THE
BOUNDARY POTENTIALLY PRODUCING THUNDERSTORMS ACROSS MAINLY
NORTHWEST IOWA. STEEP MID LEVEL LAPSE RATES LEAD TO MOST UNSTABLE
CAPE VALUES OF 2000-2500 J/KG....THOUGH STILL FAIRLY STRONG CAP TO
OVERCOME. IF STORMS ARE ABLE TO DEVELOP...VEERING PROFILE MAY AID
IN STORM ORGANIZATION...THOUGH WIND SPEEDS ARE SOMEWHAT WEAK. AS
SUCH...THE SEE TEXT SEVERE WEATHER OUTLOOK SEEMS REASONABLE WITH
CHANCE OF CONVECTION BEING VERY CONDITIONAL.
BOUNDARY IS EXPECTED TO STALL ACROSS THE SOUTHERN EDGE OF THE
FORECAST AREA TONIGHT CREATING ADDITIONAL CHANCES FOR
THUNDERSTORMS. TRIMMED BACK THE NORTHERN EXTENT OF POPS TONIGHT
WITH DRIER AIRMASS BEHIND THE FRONT MAKING IT DIFFICULT FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP. EXPECT QUITE A THERMAL
GRADIENT ACROSS THE AREA FROM THE UPPER 50S ACROSS SOUTHWEST
MINNESOTA TO NEAR 70 ACROSS THE SOUTHERN EDGE OF THE FORECAST AREA
NEAR THE FRONT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION CHANCES ARE SOMEWHAT TRICKY ON THURSDAY AS
BOUNDARY/THEATE ADVECTION LIFTS BACK TO THE NORTH. FORCING APPEARS
TO OUTRUN THE MOISTURE...AS LOW LEVEL MOISTURE APPEARS TO BE HARD TO COME
BY ACROSS THE NORTHERN CWA. THEREFORE...HAVE LIMITED CONVECTION CHANCES TO
SOUTHERN EDGE OF THE FORECAST AREA WHERE THE SLIGHTLY DEEPER
MOISTURE EXISTS.
HUMID CONDITIONS RETURN ON FRIDAY AS THE GULF OPENS BACK UP WITH
SOUTHERLY FLOW FEEDING INTO THE PLAINS. 850 HPA TEMPS WARM TO NEAR
20C DURING THE DAY LEADING TO HIGHS IN THE 80S TO NEAR 90.
STRONG LOW LEVEL JET OF 40-50 KNOTS IS EXPECTED TO DEVELOP FRIDAY
NIGHT. HAVE RAISED LOWS IN SW MN ALONG THE BUFFALO RIDGE AS
EXPOSED LOCATIONS WILL LIKELY HAVE TROUBLE COOLING OFF.
IN THE EXTENDED...SATURDAY THROUGH TUESDAY OF NEXT WEEK...A BROAD
UPPER LEVEL RIDGE REMAINS PARKED OVER THE CENTRAL PORTION OF THE
U.S. THROUGH THE PERIOD. WITH OUR AREA IN A SOUTHERLY FLOW IN
RESPONSE TO SURFACE RIDGING PARKED OVER THE EASTERN PART OF THE
NATION...MUCH ABOVE NORMAL TEMPERATURES WILL BE THE RULE. WITH
PROGGED 850 MB TEMPERATURES IN THE MID AND UPPER 20S C HIGHS WILL
GENERALLY RUN LOWER TO MID 90S EACH DAY...WITH HUMIDITY RETURNING AS
DEWPOINTS CLIMB INTO THE MID AND UPPER 60S. 925 MB TEMPERATURES
WOULD SUPPORT LOWS IN THE UPPER 60S TO LOWER 70S. IN TERMS OF
PRECIPITATION CHANCES DURING THE EXTENDED...MODELS HAVING USUAL
DIFFERENCES WITH REGARD TO MINOR SHORTWAVES ROUNDING THE UPPER THE
LEVEL RIDGE...THOUGH KEPT IT DRY THROUGH THE PERIOD WITH SUPPORT
FROM BOTH THE 00Z ECMWF AND GEM.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 623 AM CDT WED AUG 21 2013
ISOLATED CONVECTION ACROSS SOUTH CENTRAL SOUTH DAKOTA/LOWER JAMES
RIVER VALLEY EARLY THIS MORNING CONTINUES TO WEAKEN...AND EXPECT
THIS TREND TO CONTINUE OVER THE NEXT COUPLE OF HOURS.
OTHERWISE...LOW LEVEL WIND SHEAR IS POSSIBLE AT KSUX THROUGH 14Z
WITH SOUTHWESTERLY LOW LEVEL JET OVER THE AREA. FOR THE REMAINDER
OF THE DAY...EXPECTING VFR CONDITIONS WITH ONLY ISOLATED
THUNDERSTORMS POSSIBLE WITH THE PASSAGE OF A COLD FRONT. THE FRONT
WILL SETTLE JUST TO THE SOUTH OF THE AREA BY TONIGHT...WITH A
BETTER CHANCE OF THUNDERSTORMS MAINLY ALONG THE LOWER MISSOURI
RIVER CORRIDOR INTO NORTHWESTERN IOWA. BRIEF MVFR VISIBILITIES
WILL BE POSSIBLE IN ANY HEAVIER CONVECTIVE ACTIVITY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...JM
AVIATION...JM
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
429 AM CDT WED AUG 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION ACROSS CENTRAL SOUTH DAKOTA RUNNING INTO THE CAP AS IT
WORKS EAST OF THE JAMES RIVER VALLEY. THE DYING CONVECTION HAS
PRODUCED HEAT BURSTS OVER THE PAST FEW HOURS IN BOTH CHAMBERLAIN
AND MITCHELL. HRRR SHOWS CONVECTION DEVELOPING IN THE NEXT FEW
HOURS ALONG WEAK BOUNDARY SLOWLY EAKING SOUTH THROUGH THE NORTHERN
CWA THIS MORNING. HAVE SOME 20 POPS TO COVER THE POTENTIAL OF
THIS...BUT STILL NOT CONVINCED THAT STORMS ARE GOING TO BE ABLE TO
GET AROUND THE CAP. AHEAD OF THE BOUNDARY...WILL BE ANOTHER WARM
AND HUMID DAY WITH HEAT INDEX VALUES A FEW DEGREES SHY OF ADVISORY
CRITERIA. MODELS INDICATE THAT A WEAK SHORTWAVE MOVING OUT OF
WESTERN SOUTH DAKOTA THIS MORNING MAY TRY TO INTERACT WITH THE
BOUNDARY POTENTIALLY PRODUCING THUNDERSTORMS ACROSS MAINLY
NORTHWEST IOWA. STEEP MID LEVEL LAPSE RATES LEAD TO MOST UNSTABLE
CAPE VALUES OF 2000-2500 J/KG....THOUGH STILL FAIRLY STRONG CAP TO
OVERCOME. IF STORMS ARE ABLE TO DEVELOP...VEERING PROFILE MAY AID
IN STORM ORGANIZATION...THOUGH WIND SPEEDS ARE SOMEWHAT WEAK. AS
SUCH...THE SEE TEXT SEVERE WEATHER OUTLOOK SEEMS REASONABLE WITH
CHANCE OF CONVECTION BEING VERY CONDITIONAL.
BOUNDARY IS EXPECTED TO STALL ACROSS THE SOUTHERN EDGE OF THE
FORECAST AREA TONIGHT CREATING ADDITIONAL CHANCES FOR
THUNDERSTORMS. TRIMMED BACK THE NORTHERN EXTENT OF POPS TONIGHT
WITH DRIER AIRMASS BEHIND THE FRONT MAKING IT DIFFICULT FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP. EXPECT QUITE A THERMAL
GRADIENT ACROSS THE AREA FROM THE UPPER 50S ACROSS SOUTHWEST
MINNESOTA TO NEAR 70 ACROSS THE SOUTHERN EDGE OF THE FORECAST AREA
NEAR THE FRONT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 349 AM CDT WED AUG 21 2013
CONVECTION CHANCES ARE SOMEWHAT TRICKY ON THURSDAY AS
BOUNDARY/THEATE ADVECTION LIFTS BACK TO THE NORTH. FORCING APPEARS
TO OUTRUN THE MOISTURE...AS LOW LEVEL MOISTURE APPEARS TO BE HARD TO COME
BY ACROSS THE NORTHERN CWA. THEREFORE...HAVE LIMITED CONVECTION CHANCES TO
SOUTHERN EDGE OF THE FORECAST AREA WHERE THE SLIGHTLY DEEPER
MOISTURE EXISTS.
HUMID CONDITIONS RETURN ON FRIDAY AS THE GULF OPENS BACK UP WITH
SOUTHERLY FLOW FEEDING INTO THE PLAINS. 850 HPA TEMPS WARM TO NEAR
20C DURING THE DAY LEADING TO HIGHS IN THE 80S TO NEAR 90.
STRONG LOW LEVEL JET OF 40-50 KNOTS IS EXPECTED TO DEVELOP FRIDAY
NIGHT. HAVE RAISED LOWS IN SW MN ALONG THE BUFFALO RIDGE AS
EXPOSED LOCATIONS WILL LIKELY HAVE TROUBLE COOLING OFF.
IN THE EXTENDED...SATURDAY THROUGH TUESDAY OF NEXT WEEK...A BROAD
UPPER LEVEL RIDGE REMAINS PARKED OVER THE CENTRAL PORTION OF THE
U.S. THROUGH THE PERIOD. WITH OUR AREA IN A SOUTHERLY FLOW IN
RESPONSE TO SURFACE RIDGING PARKED OVER THE EASTERN PART OF THE
NATION...MUCH ABOVE NORMAL TEMPERATURES WILL BE THE RULE. WITH
PROGGED 850 MB TEMPERATURES IN THE MID AND UPPER 20S C HIGHS WILL
GENERALLY RUN LOWER TO MID 90S EACH DAY...WITH HUMIDITY RETURNING AS
DEWPOINTS CLIMB INTO THE MID AND UPPER 60S. 925 MB TEMPERATURES
WOULD SUPPORT LOWS IN THE UPPER 60S TO LOWER 70S. IN TERMS OF
PRECIPITATION CHANCES DURING THE EXTENDED...MODELS HAVING USUAL
DIFFERENCES WITH REGARD TO MINOR SHORTWAVES ROUNDING THE UPPER THE
LEVEL RIDGE...THOUGH KEPT IT DRY THROUGH THE PERIOD WITH SUPPORT
FROM BOTH THE 00Z ECMWF AND GEM.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1103 PM CDT TUE AUG 20 2013
VFR CONDITIONS EXPECTED TO DOMINATE THROUGH THE FORECAST PERIOD...
ALTHOUGH WITH HIGH BOUNDARY LAYER MOISTURE LEVELS...PATCHY FOG AGAIN
POSSIBLE THROUGH SHORTLY AFTER SUNRISE WEDNESDAY. NOT EXPECTING THE
WIDESPREAD IFR-LIFR CONDITIONS AS WAS SEEN TUESDAY MORNING...BUT
PATCHY MVFR VISIBILITY POSSIBLE IN AREAS WHERE WINDS DROP OFF AND
HAVE ADDED TO KHON FOR A FEW HOURS AROUND SUNRISE. SOUTHWESTERLY LOW
LEVEL JET OF 30-35KT DEVELOPING AHEAD OF THE BOUNDARY TONIGHT COULD
CREATE LOW LEVEL WIND SHEAR CONDITIONS AT KSUX. LATEST SHORT RANGE
MODELS STARTING TO SHOW THIS MORE THAN PREVIOUS RUNS...SO HAVE ADDED
LLWS TO KSUX THROUGH THE EARLY MORNING.
SCATTERED HIGH BASED THUNDERSTORMS IN FAR WESTERN CWA AT START OF
THE PERIOD EXPECTED TO WEAKEN AS THEY TRY TO MOVE EAST AWAY FROM
WEAK COLD FRONT IN CENTRAL SD. EXPECT THIS ACTIVITY TO REMAIN SOUTH
OF KHON AND WEAKEN BEFORE IT REACHES I-29 CORRIDOR. CHANCE OF SPOTTY
THUNDERSTORMS THEN SHIFTS INTO SOUTHWEST MINNESOTA AND SOUTH OF I-90
BY LATE WEDNESDAY AFTERNOON AS THE COLD FRONT MOVES INTO THAT AREA.
CAPPING LIKELY TO LIMIT DEVELOPMENT THROUGH 22/00Z...BUT CHANCE WILL
INCREASE THROUGH THE MISSOURI RIVER VALLEY AS LOW LEVEL JET IMPINGES
ON THE BOUNDARY WHICH STALLS NEAR FAR SOUTHERN CWA. HAVE ADDED A FEW
HOURS OF THUNDER TO KSUX WEDNESDAY EVENING...BUT TIMING/LOCATION IS
STILL UNCERTAIN...SO TIMING MAY CHANGE IN LATER FORECASTS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...JM
AVIATION...JH
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
103 PM CDT WED AUG 21 2013
.AVIATION...
QUIET SO FAR THIS MORNING WITH LIGHT NE TO E FLOW BUT THIS WILL
BECOME MORE SOUTHEAST WITH HEATING TODAY. SHOWERS HAVE BEEN FEW
AND FAR BETWEEN BUT SOME AREAS OF LOCALIZED CONVERGENCE EAST OF
GALVESTON AROUND SMITH POINT AND FROM AROUND LBX TO PSX. EXPECTING
A SLOW INLAND PENETRATION GIVEN THE LL FLOW THROUGH MID AFTERNOON
THEN SHOULD ACCELERATE BUT MAY OUTRUN THE AVAILABLE MOISTURE AND
WEAKEN INLAND DURING THE AFTERNOON. FOR NOW WILL ONLY MENTION
VCSH/VCTS FOR HOU TERMINALS SOUTHWARD EARLY THIS AFTERNOON. SKIES
SHOULD CLEAR OUT TONIGHT BUT MOISTURE INCREASES FURTHER TOMORROW
TO AROUND 2-2.1" AND THE S/W OVER LA AND LA GULF WATERS SHOULD
MOVE WEST AND GIVE THE AREA SOME BROAD LIFT AND COMBINED WITH THE
PW AND SEABREEZE EXPECT GREATER COVERAGE SCATTERED TOMORROW
STARTING NEAR THE COAST AROUND 08-09Z AND SPREADING WEST AND NORTH
THROUGH THE MORNING HOURS. WILL CARRY VCSH/VCTS FOR IAH SOUTHWARD
AND PROB30 FOR HOU SOUTHWARD. THIS MAY BE NEEDED FOR IAH/CXO AFTER
18Z BUT WILL LIKELY WAIT UNTIL THE 00Z PACKAGE TO ADD IT THAT FAR
NORTH.
45
&&
.PREV DISCUSSION... /ISSUED 958 AM CDT WED AUG 21 2013/
UPDATE...
MORNING FORECAST UPDATE.
DISCUSSION...
LATEST RADAR IMAGERY SHOWS A FEW SHOWERS WAY OUT IN THE GULF BUT
REALLY NOT MUCH ACTIVITY THIS MORNING COMPARED TO YESTERDAY.
MOISTURE LEVELS SEEM TO BE LOWER WITH PRECIP WATER VALUES AROUND
1.8-1.9 INCHES PER GOES SOUNDER IMAGERY. SFC ANALYSIS SHOWS A WEAK
RIDGE AXIS FROM HIGH PRESSURE OVER THE SE U.S. WILL DECREASE POPS
THIS MORNING TO 20 PERCENT AS SHOULD GET A FEW SHOWERS LATER THIS
MORNING WITH DAY TIME HEATING. WILL KEEP 30 POPS FOR THE AFTERNOON
AS HEATING INCREASES MORE. LATEST 12Z HRRR KEEPS MOST OF THE
CONVECTION TO SW OF HOUSTON BUT CONVECTION DOES DISSIPATE AROUND
23Z SIMILAR TO YESTERDAY. THINK THAT WILL BE MORE LIKELY THE CASE.
UPDATED FORECAST HAS BEEN ISSUED.
39/45
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 74 96 75 95 / 20 10 40 30 20
HOUSTON (IAH) 95 73 94 75 94 / 30 10 40 20 30
GALVESTON (GLS) 90 79 88 80 88 / 30 20 40 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...33
AVIATION/MARINE...45
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1238 PM CDT WED AUG 21 2013
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH THE NEXT 24 HOURS WITH GENERALLY
SOUTH WINDS CONTINUING.
SIMPSON
&&
.PREV DISCUSSION... /ISSUED 615 AM CDT WED AUG 21 2013/
AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF
PERIOD...WITH ONLY FEW TO SCT HIGH CLOUDS. ANY TSRA SHOULD STAY IN
THE HIGHER TERRAIN OF NM AND CO...WELL WEST OF THE TAF SITES. EXPECT
WINDS GENERALLY SOUTHERLY WITH A DIURNAL TREND ON SPEEDS.
JOHNSON
PREV DISCUSSION... /ISSUED 331 AM CDT WED AUG 21 2013/
DISCUSSION...
UPPER HIGH WILL PREVAIL ACROSS THE PANHANDLES AND THE CENTRAL PLAINS
STATES THROUGH THE END OF THE WEEK AND EARLY THIS WEEKEND...THEN THE
UPPER HIGH SHIFTS EASTWARD OVER THE MID MISSISSIPPI RIVER VALLEY AREA
BY LATE IN THE WEEKEND THROUGH THE MIDDLE OF NEXT WEEK. SUBSIDENCE
WILL DOMINATE THE FORECAST AREA THROUGH EARLY AND MID NEXT WEEK
KEEPING THE PANHANDLES DRY WITH ABOVE NORMAL TEMPERATURES. ALTHOUGH A
ROGUE THUNDERSTORM DEVELOPED ACROSS THE SOUTHWEST TEXAS PANHANDLE THE
LAST COUPLE OF DAYS DURING THE LATE AFTERNOON AND EARLY EVENING
HOURS...THE NMM MODEL DID FORECAST THIS SCENARIO ON TUESDAY.
HOWEVER...THE NMM...ARW...THE NAM...GFS...RUC AND ECMWF ALONG WITH
THE TTU-WRF AND THE HRRR ARE ALL CONVECTION-FREE AND WILL CONTINUE
WITH A DRY FORECAST. NO MAJOR CHANGES TO THE PREVIOUS GRIDS AND
FORECAST.
SCHNEIDER
FIRE WEATHER...
NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED ACROSS
THE TEXAS AND OKLAHOMA PANHANDLES THROUGH THE MIDDLE OF NEXT WEEK.
EITHER THE MINIMUM AFTERNOON RELATIVE HUMIDITIES WILL REMAIN AT OR
ABOVE 20 PERCENT...OR THE 20 FOOT WIND SPEEDS WILL REMAIN AT OR BELOW
15 TO 20 MPH.
SCHNEIDER
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
09/08
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
958 AM CDT WED AUG 21 2013
.UPDATE...
MORNING FORECAST UPDATE.
&&
.DISCUSSION...
LATEST RADAR IMAGERY SHOWS A FEW SHOWERS WAY OUT IN THE GULF BUT
REALLY NOT MUCH ACTIVITY THIS MORNING COMPARED TO YESTERDAY.
MOISTURE LEVELS SEEM TO BE LOWER WITH PRECIP WATER VALUES AROUND
1.8-1.9 INCHES PER GOES SOUNDER IMAGERY. SFC ANALYSIS SHOWS A WEAK
RIDGE AXIS FROM HIGH PRESSURE OVER THE SE U.S. WILL DECREASE POPS
THIS MORNING TO 20 PERCENT AS SHOULD GET A FEW SHOWERS LATER THIS
MORNING WITH DAY TIME HEATING. WILL KEEP 30 POPS FOR THE AFTERNOON
AS HEATING INCREASES MORE. LATEST 12Z HRRR KEEPS MOST OF THE
CONVECTION TO SW OF HOUSTON BUT CONVECTION DOES DISSIPATE AROUND
23Z SIMILAR TO YESTERDAY. THINK THAT WILL BE MORE LIKELY THE CASE.
UPDATED FORECAST HAS BEEN ISSUED.
39/45
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 74 96 75 95 / 20 20 40 30 20
HOUSTON (IAH) 95 73 94 75 94 / 30 30 40 20 30
GALVESTON (GLS) 90 79 88 80 88 / 30 20 40 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
615 AM CDT WED AUG 21 2013
.AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF
PERIOD...WITH ONLY FEW TO SCT HIGH CLOUDS. ANY TSRA SHOULD STAY IN
THE HIGHER TERRAIN OF NM AND CO...WELL WEST OF THE TAF SITES. EXPECT
WINDS GENERALLY SOUTHERLY WITH A DIURNAL TREND ON SPEEDS.
JOHNSON
&&
.PREV DISCUSSION... /ISSUED 331 AM CDT WED AUG 21 2013/
DISCUSSION...
UPPER HIGH WILL PREVAIL ACROSS THE PANHANDLES AND THE CENTRAL PLAINS
STATES THROUGH THE END OF THE WEEK AND EARLY THIS WEEKEND...THEN THE
UPPER HIGH SHIFTS EASTWARD OVER THE MID MISSISSIPPI RIVER VALLEY AREA
BY LATE IN THE WEEKEND THROUGH THE MIDDLE OF NEXT WEEK. SUBSIDENCE
WILL DOMINATE THE FORECAST AREA THROUGH EARLY AND MID NEXT WEEK
KEEPING THE PANHANDLES DRY WITH ABOVE NORMAL TEMPERATURES. ALTHOUGH A
ROGUE THUNDERSTORM DEVELOPED ACROSS THE SOUTHWEST TEXAS PANHANDLE THE
LAST COUPLE OF DAYS DURING THE LATE AFTERNOON AND EARLY EVENING
HOURS...THE NMM MODEL DID FORECAST THIS SCENARIO ON TUESDAY.
HOWEVER...THE NMM...ARW...THE NAM...GFS...RUC AND ECMWF ALONG WITH
THE TTU-WRF AND THE HRRR ARE ALL CONVECTION-FREE AND WILL CONTINUE
WITH A DRY FORECAST. NO MAJOR CHANGES TO THE PREVIOUS GRIDS AND
FORECAST.
SCHNEIDER
FIRE WEATHER...
NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED ACROSS
THE TEXAS AND OKLAHOMA PANHANDLES THROUGH THE MIDDLE OF NEXT WEEK.
EITHER THE MINIMUM AFTERNOON RELATIVE HUMIDITIES WILL REMAIN AT OR
ABOVE 20 PERCENT...OR THE 20 FOOT WIND SPEEDS WILL REMAIN AT OR BELOW
15 TO 20 MPH.
SCHNEIDER
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
16/11
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
156 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST BY LATE THURSDAY. A COLD FRONT WILL MOVE FROM THE
GREAT LAKES ON THURSDAY INTO THE CAROLINAS BY SATURDAY. DRIER AND
COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1240 PM EDT WEDNESDAY...
NOT A LOT OF CHANGES FOR THE AFTERNOON UPDATE. WE WILL STILL HAVE
THE GENERAL FORECAST IN PLACE FOR A GREATER CONCENTRATION OF
SHOWERS AND STORMS THIS AFTERNOON ACROSS THE MOUNTAINS WITH LESSER
COVERAGE IN THE EAST UNTIL TOWARD EVENING. WHAT HAS BEEN ADJUSTED
IS THE PRECIPITATION CHANCES IN THE VERY NEAR FUTURE. HAVE RAMPED
PRECIPITATION CHANCES TO CATEGORICAL ACROSS THE FAR SOUTHWEST PART
OF THE FORECAST AREA WHERE SHOWERS AND STORMS WERE ONGOING.
CURRENT TRACK AND SPEED WOULD SUGGEST THIS AREA WILL REMAIN A HOT
SPOT FOR AT LEAST THE NEXT TWO TO THREE HOURS.
ANOTHER ADJUSTMENT INCLUDES THE FORECAST HIGH TEMPERATURES.
READINGS IN THE EAST LOOK TO EXCEED THE EARLIER FORECAST SO HAVE
INCREASED VALUES BY A FEW DEGREES IN ANTICIPATION OF HIGHER HIGH
TEMPERATURES. NO OTHER SIGNIFICANT CHANGES.
AS OF 950 AM EDT WEDNESDAY...
THE FORECAST THIS MORNING FOR THE MOST PART HAS BEEN ON TRACK. THE
GREATEST CONCENTRATION OF PRECIPITATION HAS BEEN ALONG AND SOUTH
OF THE NC/VA BORDER. OTHER ISOLATED SHOWERS HAVE BEEN NEAR THE
I-64 CORRIDOR OF WV/VA...HOWEVER...MUCH OF THIS DISSIPATED AROUND
930 AM. CURRENTLY...THE NEAR TERM MODEL OF CHOICE IS THE RNK WFR-
ARW. IS HOURLY DEPICTION OF THE PRECIPITATION IN NC HAS MATCHED
VERY WELL THIS MORNING. HAVE USED ITS OUTPUT AS A ROUGH
EXTRAPOLATION OF WHAT IS TO COME THROUGH THE REMAINDER OF THE
MORNING AND THIS AFTERNOON. ITS OUTPUT IS ALSO COMPARABLE TO THE
ONGOING FORECAST FOR TODAY.
WE ARE ANTICIPATING THE WEAK ACTIVITY NEAR THE NC/VA BORDER TO
DECREASE IN SIGNIFICANCE HEADING INTO THE AFTERNOON...WITH OUR
FOCUS SHIFTING TO THE WESTERN HALF OF THE REGION. HERE SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP AND TO COVER 50 TO 70
PERCENT OF THIS REGION THROUGHOUT THE AFTERNOON...WITH COVERAGE
INCREASING ITS GREATEST BETWEEN ROUGHLY 100 PM AND 200 PM.
ELSEWHERE...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
THROUGH THE MID-AFTERNOON...AND THEN LOOK FOR A SHIFT EASTWARD OF
THE MAIN AREA OF PRECIPITATION THAT WILL IMPACT AREAS PRIMARILY
ALONG AND NORTH OF THE ROUTE 460 CORRIDOR OF VA.
AS OF 410 AM EDT WEDNESDAY...
WHEN I FIRST JOINED THE NATIONAL WEATHER SERVICE MY ELDERS TOLD ME
A CODE THEY WOULD USE WHEN THERE WAS LOW CONFIDENCE IN THE
FORECAST. THEY WOULD APPEND A NUMBER 9 TO THE END OF THEIR NAME
WHEN ISSUING THE FORECAST. TODAY IS DEFINITELY A 9 DAY.
MODELS SHOWING SIGNIFICANT DIFFERENCES IN THE TIMING AND LOCATION
OF PRECIPITATION FOR TODAY AND TONIGHT. HOWEVER...THE LATEST RAP
AND HRRR GUIDANCE HAVE SOMEWHAT OF A REASONABLE TREND WITH THE
PRECIPITATION MOVING NORTH FROM THE CAROLINAS AND THE 00Z LOCAL
WRF SHOWED DECENT CONTINUITY WITH THE PRECIPITATION IN WEST
VIRGINIA.
EXPECT A MAJORITY OF THE PRECIPITATION FROM THE CAROLINAS TO MOVE
THROUGH THE FORECAST AREA THIS MORNING. BY LATE THIS
AFTERNOON...THE UPPER LOW TRACKING WEST OUT OF THE OHIO VALLEY
SHOULD BE TRIGGERING SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS.
AS THIS FEATURE MOVES EAST THIS EVENING...THE COUNTY WARNING AREA
WILL BE IN A FAVORABLE QUADRANT OF THE ASSOCIATED UPPER JET. NET
RESULT IS NOT MUCH CHANGE IN THE PROBABILITY OF PRECIPITATION FOR
TODAY AND TONIGHT.
BUFKIT SHOWED WINDS THROUGH MID LAYERS OF THE ATMOSPHERE LESS THAN
15 KNOTS...WHICH SUGGESTS INDIVIDUAL STORMS THAT DEVELOP MAY BE
MOVING SLOWLY. FLASH FLOOD GUIDANCE IS LESS THAN 2 INCHES FROM THE
NEW RIVER VALLEY AND SOUTHEAST WEST VIRGINIA INTO NORTHWEST NORTH
CAROLINA. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES TODAY
AND TONIGHT HEAVY RAIN REMAINS A THREAT.
TRENDED TOWARD GRIDDED LAMP GUIDANCE FOR MAXIMUM TEMPERATURES
TODAY...BUT WITH CLOUDS AND PRECIPITATION THIS MORNING...WITH BE
COUNTING ON SOME BREAKS IN THE CLOUDS FOR THIS AFTERNOON.
MILD SURFACE DEW POINTS AND CLOUD COVER WILL LIMIT COOLING
OVERNIGHT. LEANED TOWARD WARMER NUMBERS FOR OVERNIGHT LOWS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 AM EDT WEDNESDAY...
UPPER LOW CENTER AROUND LAFAYETTE INDIANA THIS MORNING WILL TRAVEL
EAST AND REACH THE EAST COAST ON FRIDAY. THIS LOW CENTER MOVES INTO
THE ATLANTIC BY SATURDAY...ALLOWING A SURFACE HIGH TO PUSH INTO THE
REGION JUST IN TIME FOR THE WEEKEND.
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE COLD FRONT ON
THURSDAY. KEPT THE ISOLATED TO SCATTERED POPS IN FOR THURSDAY. WENT
WITH HIGH TEMPERATURES CLOSER TO THE COOLER ADJMET WITH READINGS
FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
A COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT INTO FRIDAY.
PLACED THE HIGHEST POPS (GOOD CHANCE TO LIKELY) IN THE WEST THURSDAY
NIGHT INTO FRIDAY. LEANED TOWARDS THE WARMER MOS LOW TEMPERATURES
THURSDAY NIGHT WITH READINGS FROM THE LOWER 60S IN THE MOUNTAINS TO
NEAR 70 DEGREES IN THE PIEDMONT. HIGHS ON FRIDAY WILL VARY FROM THE
LOWER 70S IN THE WEST TO THE UPPER 80S IN THE SOUTHEAST. LOWERED
POPS FRIDAY NIGHT FROM NORTH TO SOUTH. USED THE ENSEMBLE LOWS FRIDAY
NIGHT WITH VALUES FROM LOWER 50S IN THE NORTHWEST TO THE LOWER 60S
IN THE SOUTH. UNDER THE UPPER RIDGE...PLEASANT SATURDAY ON TAP WITH
SUNSHINE AND HIGH TEMPERATURES GENERALLY FROM MID 70S TO THE LOWER
80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DURING SUNDAY...FLOW AROUND THE SURFACE HIGH WILL BRING SOUTHEAST
FLOW INTO THE SOUTHWEST PART OF THE REGION. THIS MAY YIELD SOME
ISOLATED UPSLOPE SHOWERS. A COLD FRONT IS PROGGED TO TRY TO MAKE ITS
WAY INTO THE NORTHERN PART OF THE AREA MONDAY NIGHT INTO TUESDAY.
THERE MAY BE SOME ISOLATED SHOWERS IN ADVANCE OF THIS FRONT THAT
REACH NORTHERN PARTS OF THE AREA LATE IN THE DAY MONDAY. SEVERAL
WEAK SHORTWAVES WILL DROP SOUTH IN THE NORTHWEST FLOW ALOFT ACROSS
NORTHERN PORTIONS OF OUR REGION TUESDAY INTO WEDNESDAY.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 150 PM EDT WEDNESDAY...
THE ASSOCIATED DYNAMICS WITH THE APPROACH OF A SHORTWAVE TROUGH
IS ENTERING THE REGION CURRENTLY. SURFACE TEMPERATURES CONTINUE TO
WARM AND HELP THE LOW LEVELS BECOME UNSTABLE. THE RESULT IS
DEVELOPMENT OF SHOWERS AND STORMS ACROSS THE AREA. THE GREATEST
CONCENTRATION THROUGH THE AFTERNOON HOURS IS EXPECTED TO BE ACROSS
THE MOUNTAINS. COVERAGE IS EXPECTED TO TRANSLATE EASTWARD HEADING
INTO THE EVENING HOURS. MOST AREAS WILL CONTINUE TO EXPERIENCE VFR
CONDITIONS THE REMAINDER OF THE AFTERNOON AND THROUGH THE EARLY
EVENING. THE EXCEPTION WILL BE THOSE LOCALIZED AREAS WITH MODERATE
TO HEAVE SHRA/TSRA. HERE BRIEF PERIODS OF IFR/MVFR CONDITIONS ARE
LIKELY ALONG WITH VARIABLE AND GUSTY WIND CONDITIONS.
THROUGH THE OVERNIGHT HOURS...CEILINGS WILL TREND TO A MIX OF
MVFR AND LOW END VFR CONDITIONS BY 06Z/2AM WITH A MIX OF IFR/MVFR
CEILINGS BY 12Z/8AM. VISIBILITIES WILL TREND TO IFR IN THOSE
LOCATIONS THAT RECEIVED RAIN TODAY AND EARLY THIS EVENING ALSO
SHELTERED VALLEYS ALSO WILL TREND TOWARD HAVING FOG.
THE TROUGH AXIS PASSES AROUND 12Z/8AM THURSDAY. THIS WILL ALLOW
WINDS TO VEER MORE WESTERLY AND INCREASE IN SPEED. ANY SUB-VFR
CONDITIONS SHOULD IMPROVE FAIRLY RAPIDLY TO VFR.
A BROADER LONGWAVE TROUGH AND ASSOCIATED COLD FRONT WILL PROGRESS
ACROSS THE EASTERN U.S. THURSDAY NIGHT INTO FRIDAY. LOOK FOR A
RETURN OF ORGANIZED SHOWERS AND STORMS IN ADVANCE...DURING...AND
IMMEDIATELY BEHIND ITS PASSAGE. SUB-VFR CONDITIONS WILL ACCOMPANY
THE HEAVIER SHRA/TSRA.
DRIER HIGH PRESSURE BUILDS IN TO THE AREA FOR THE WEEKEND. OTHER
THAN SOME LATE NIGHT AND EARLY MORNING MOUNTAIN AND RIVER VALLEY
FOG...VFR CONDITIONS ARE EXPECTED INTO MONDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/DS
SHORT TERM...KK
LONG TERM...DS/KK
AVIATION...DS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1243 PM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST BY LATE THURSDAY. A COLD FRONT WILL MOVE FROM THE
GREAT LAKES ON THURSDAY INTO THE CAROLINAS BY SATURDAY. DRIER AND
COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1240 PM EDT WEDNESDAY...
NOT A LOT OF CHANGES FOR THE AFTERNOON UPDATE. WE WILL STILL HAVE
THE GENERAL FORECAST IN PLACE FOR A GREATER CONCENTRATION OF
SHOWERS AND STORMS THIS AFTERNOON ACROSS THE MOUNTAINS WITH LESSER
COVERAGE IN THE EAST UNTIL TOWARD EVENING. WHAT HAS BEEN ADJUSTED
IS THE PRECIPITATION CHANCES IN THE VERY NEAR FUTURE. HAVE RAMPED
PRECIPITATION CHANCES TO CATEGORICAL ACROSS THE FAR SOUTHWEST PART
OF THE FORECAST AREA WHERE SHOWERS AND STORMS WERE ONGOING.
CURRENT TRACK AND SPEED WOULD SUGGEST THIS AREA WILL REMAIN A HOT
SPOT FOR AT LEAST THE NEXT TWO TO THREE HOURS.
ANOTHER ADJUSTMENT INCLUDES THE FORECAST HIGH TEMPERATURES.
READINGS IN THE EAST LOOK TO EXCEED THE EARLIER FORECAST SO HAVE
INCREASED VALUES BY A FEW DEGREES IN ANTICIPATION OF HIGHER HIGH
TEMPERATURES. NO OTHER SIGNIFICANT CHANGES.
AS OF 950 AM EDT WEDNESDAY...
THE FORECAST THIS MORNING FOR THE MOST PART HAS BEEN ON TRACK. THE
GREATEST CONCENTRATION OF PRECIPITATION HAS BEEN ALONG AND SOUTH
OF THE NC/VA BORDER. OTHER ISOLATED SHOWERS HAVE BEEN NEAR THE
I-64 CORRIDOR OF WV/VA...HOWEVER...MUCH OF THIS DISSIPATED AROUND
930 AM. CURRENTLY...THE NEAR TERM MODEL OF CHOICE IS THE RNK WFR-
ARW. IS HOURLY DEPICTION OF THE PRECIPITATION IN NC HAS MATCHED
VERY WELL THIS MORNING. HAVE USED ITS OUTPUT AS A ROUGH
EXTRAPOLATION OF WHAT IS TO COME THROUGH THE REMAINDER OF THE
MORNING AND THIS AFTERNOON. ITS OUTPUT IS ALSO COMPARABLE TO THE
ONGOING FORECAST FOR TODAY.
WE ARE ANTICIPATING THE WEAK ACTIVITY NEAR THE NC/VA BORDER TO
DECREASE IN SIGNIFICANCE HEADING INTO THE AFTERNOON...WITH OUR
FOCUS SHIFTING TO THE WESTERN HALF OF THE REGION. HERE SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP AND TO COVER 50 TO 70
PERCENT OF THIS REGION THROUGHOUT THE AFTERNOON...WITH COVERAGE
INCREASING ITS GREATEST BETWEEN ROUGHLY 100 PM AND 200 PM.
ELSEWHERE...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
THROUGH THE MID-AFTERNOON...AND THEN LOOK FOR A SHIFT EASTWARD OF
THE MAIN AREA OF PRECIPITATION THAT WILL IMPACT AREAS PRIMARILY
ALONG AND NORTH OF THE ROUTE 460 CORRIDOR OF VA.
AS OF 410 AM EDT WEDNESDAY...
WHEN I FIRST JOINED THE NATIONAL WEATHER SERVICE MY ELDERS TOLD ME
A CODE THEY WOULD USE WHEN THERE WAS LOW CONFIDENCE IN THE
FORECAST. THEY WOULD APPEND A NUMBER 9 TO THE END OF THEIR NAME
WHEN ISSUING THE FORECAST. TODAY IS DEFINITELY A 9 DAY.
MODELS SHOWING SIGNIFICANT DIFFERENCES IN THE TIMING AND LOCATION
OF PRECIPITATION FOR TODAY AND TONIGHT. HOWEVER...THE LATEST RAP
AND HRRR GUIDANCE HAVE SOMEWHAT OF A REASONABLE TREND WITH THE
PRECIPITATION MOVING NORTH FROM THE CAROLINAS AND THE 00Z LOCAL
WRF SHOWED DECENT CONTINUITY WITH THE PRECIPITATION IN WEST
VIRGINIA.
EXPECT A MAJORITY OF THE PRECIPITATION FROM THE CAROLINAS TO MOVE
THROUGH THE FORECAST AREA THIS MORNING. BY LATE THIS
AFTERNOON...THE UPPER LOW TRACKING WEST OUT OF THE OHIO VALLEY
SHOULD BE TRIGGERING SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS.
AS THIS FEATURE MOVES EAST THIS EVENING...THE COUNTY WARNING AREA
WILL BE IN A FAVORABLE QUADRANT OF THE ASSOCIATED UPPER JET. NET
RESULT IS NOT MUCH CHANGE IN THE PROBABILITY OF PRECIPITATION FOR
TODAY AND TONIGHT.
BUFKIT SHOWED WINDS THROUGH MID LAYERS OF THE ATMOSPHERE LESS THAN
15 KNOTS...WHICH SUGGESTS INDIVIDUAL STORMS THAT DEVELOP MAY BE
MOVING SLOWLY. FLASH FLOOD GUIDANCE IS LESS THAN 2 INCHES FROM THE
NEW RIVER VALLEY AND SOUTHEAST WEST VIRGINIA INTO NORTHWEST NORTH
CAROLINA. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES TODAY
AND TONIGHT HEAVY RAIN REMAINS A THREAT.
TRENDED TOWARD GRIDDED LAMP GUIDANCE FOR MAXIMUM TEMPERATURES
TODAY...BUT WITH CLOUDS AND PRECIPITATION THIS MORNING...WITH BE
COUNTING ON SOME BREAKS IN THE CLOUDS FOR THIS AFTERNOON.
MILD SURFACE DEW POINTS AND CLOUD COVER WILL LIMIT COOLING
OVERNIGHT. LEANED TOWARD WARMER NUMBERS FOR OVERNIGHT LOWS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 AM EDT WEDNESDAY...
UPPER LOW CENTER AROUND LAFAYETTE INDIANA THIS MORNING WILL TRAVEL
EAST AND REACH THE EAST COAST ON FRIDAY. THIS LOW CENTER MOVES INTO
THE ATLANTIC BY SATURDAY...ALLOWING A SURFACE HIGH TO PUSH INTO THE
REGION JUST IN TIME FOR THE WEEKEND.
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE COLD FRONT ON
THURSDAY. KEPT THE ISOLATED TO SCATTERED POPS IN FOR THURSDAY. WENT
WITH HIGH TEMPERATURES CLOSER TO THE COOLER ADJMET WITH READINGS
FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
A COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT INTO FRIDAY.
PLACED THE HIGHEST POPS (GOOD CHANCE TO LIKELY) IN THE WEST THURSDAY
NIGHT INTO FRIDAY. LEANED TOWARDS THE WARMER MOS LOW TEMPERATURES
THURSDAY NIGHT WITH READINGS FROM THE LOWER 60S IN THE MOUNTAINS TO
NEAR 70 DEGREES IN THE PIEDMONT. HIGHS ON FRIDAY WILL VARY FROM THE
LOWER 70S IN THE WEST TO THE UPPER 80S IN THE SOUTHEAST. LOWERED
POPS FRIDAY NIGHT FROM NORTH TO SOUTH. USED THE ENSEMBLE LOWS FRIDAY
NIGHT WITH VALUES FROM LOWER 50S IN THE NORTHWEST TO THE LOWER 60S
IN THE SOUTH. UNDER THE UPPER RIDGE...PLEASANT SATURDAY ON TAP WITH
SUNSHINE AND HIGH TEMPERATURES GENERALLY FROM MID 70S TO THE LOWER
80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DURING SUNDAY...FLOW AROUND THE SURFACE HIGH WILL BRING SOUTHEAST
FLOW INTO THE SOUTHWEST PART OF THE REGION. THIS MAY YIELD SOME
ISOLATED UPSLOPE SHOWERS. A COLD FRONT IS PROGGED TO TRY TO MAKE ITS
WAY INTO THE NORTHERN PART OF THE AREA MONDAY NIGHT INTO TUESDAY.
THERE MAY BE SOME ISOLATED SHOWERS IN ADVANCE OF THIS FRONT THAT
REACH NORTHERN PARTS OF THE AREA LATE IN THE DAY MONDAY. SEVERAL
WEAK SHORTWAVES WILL DROP SOUTH IN THE NORTHWEST FLOW ALOFT ACROSS
NORTHERN PORTIONS OF OUR REGION TUESDAY INTO WEDNESDAY.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 135 AM EDT WEDNESDAY...
AREAS OF IFR CIG/VIS WILL DISSIPATE THIS MORNING BY 14Z. LEADING
EDGE OF PRECIPITATION COMING OUT OF THE SOUTHWEST WAS JUST
REACHING THE VIRGINIA/NORTH CAROLINA BORDER AT 7AM. EXPECT
EXPANDING COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH
16Z EAST OF THE BLUE RIDGE. BEST CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE MOUNTAINS WILL BE AFTER 18Z/2PM BUT WILL
CONTINUE THROUGH THE EVENING.
PATTERN WILL TRANSITION TO MORE TYPICAL OF MID AUGUST THURSDAY...WITH
SOUTHWEST FLOW AND DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS.
SCATTERED LOW CLOUDS WILL LINGER DURING THE MORNING IN AREAS...
RESULTING IN A MIXTURE OF MVFR AND VFR CONDITIONS...BEFORE
IMPROVING TO MOSTLY VFR BY EARLY AFTERNOON. PATCHY DENSE FOG
WILL ALSO BE AN ISSUE EACH NIGHT.
A FRONTAL BOUNDARY SHOULD MOVE THROUGH BY FRIDAY...POSSIBLY
PROVIDING BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS. BEHIND
THIS FRONT DRIER AIR AND VFR CONDITIONS ARE EXPECTED SATURDAY AND
SUNDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/DS
SHORT TERM...KK
LONG TERM...DS/KK
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
957 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST BY LATE THURSDAY. A COLD FRONT WILL MOVE FROM THE
GREAT LAKES ON THURSDAY INTO THE CAROLINAS BY SATURDAY. DRIER AND
COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 AM EDT WEDNESDAY...
THE FORECAST THIS MORNING FOR THE MOST PART HAS BEEN ON TRACK. THE
GREATEST CONCENTRATION OF PRECIPITATION HAS BEEN ALONG AND SOUTH
OF THE NC/VA BORDER. OTHER ISOLATED SHOWERS HAVE BEEN NEAR THE
I-64 CORRIDOR OF WV/VA...HOWEVER...MUCH OF THIS DISSIPATED AROUND
930 AM. CURRENTLY...THE NEAR TERM MODEL OF CHOICE IS THE RNK WFR-
ARW. IS HOURLY DEPICTION OF THE PRECIPITATION IN NC HAS MATCHED
VERY WELL THIS MORNING. HAVE USED ITS OUTPUT AS A ROUGH
EXTRAPOLATION OF WHAT IS TO COME THROUGH THE REMAINDER OF THE
MORNING AND THIS AFTERNOON. ITS OUTPUT IS ALSO COMPARABLE TO THE
ONGOING FORECAST FOR TODAY.
WE ARE ANTICIPATING THE WEAK ACTIVITY NEAR THE NC/VA BORDER TO
DECREASE IN SIGNIFICANCE HEADING INTO THE AFTERNOON...WITH OUR
FOCUS SHIFTING TO THE WESTERN HALF OF THE REGION. HERE SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP AND TO COVER 50 TO 70
PERCENT OF THIS REGION THROUGHOUT THE AFTERNOON...WITH COVERAGE
INCREASING ITS GREATEST BETWEEN ROUGHLY 100 PM AND 200 PM.
ELSEWHERE...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
THROUGH THE MID-AFTERNOON...AND THEN LOOK FOR A SHIFT EASTWARD OF
THE MAIN AREA OF PRECIPITATION THAT WILL IMPACT AREAS PRIMARILY
ALONG AND NORTH OF THE ROUTE 460 CORRIDOR OF VA.
AS OF 410 AM EDT WEDNESDAY...
WHEN I FIRST JOINED THE NATIONAL WEATHER SERVICE MY ELDERS TOLD ME
A CODE THEY WOULD USE WHEN THERE WAS LOW CONFIDENCE IN THE
FORECAST. THEY WOULD APPEND A NUMBER 9 TO THE END OF THEIR NAME
WHEN ISSUING THE FORECAST. TODAY IS DEFINITELY A 9 DAY.
MODELS SHOWING SIGNIFICANT DIFFERENCES IN THE TIMING AND LOCATION
OF PRECIPITATION FOR TODAY AND TONIGHT. HOWEVER...THE LATEST RAP
AND HRRR GUIDANCE HAVE SOMEWHAT OF A REASONABLE TREND WITH THE
PRECIPITATION MOVING NORTH FROM THE CAROLINAS AND THE 00Z LOCAL
WRF SHOWED DECENT CONTINUITY WITH THE PRECIPITATION IN WEST
VIRGINIA.
EXPECT A MAJORITY OF THE PRECIPITATION FROM THE CAROLINAS TO MOVE
THROUGH THE FORECAST AREA THIS MORNING. BY LATE THIS
AFTERNOON...THE UPPER LOW TRACKING WEST OUT OF THE OHIO VALLEY
SHOULD BE TRIGGERING SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS.
AS THIS FEATURE MOVES EAST THIS EVENING...THE COUNTY WARNING AREA
WILL BE IN A FAVORABLE QUADRANT OF THE ASSOCIATED UPPER JET. NET
RESULT IS NOT MUCH CHANGE IN THE PROBABILITY OF PRECIPITATION FOR
TODAY AND TONIGHT.
BUFKIT SHOWED WINDS THROUGH MID LAYERS OF THE ATMOSPHERE LESS THAN
15 KNOTS...WHICH SUGGESTS INDIVIDUAL STORMS THAT DEVELOP MAY BE
MOVING SLOWLY. FLASH FLOOD GUIDANCE IS LESS THAN 2 INCHES FROM THE
NEW RIVER VALLEY AND SOUTHEAST WEST VIRGINIA INTO NORTHWEST NORTH
CAROLINA. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES TODAY
AND TONIGHT HEAVY RAIN REMAINS A THREAT.
TRENDED TOWARD GRIDDED LAMP GUIDANCE FOR MAXIMUM TEMPERATURES
TODAY...BUT WITH CLOUDS AND PRECIPITATION THIS MORNING...WITH BE
COUNTING ON SOME BREAKS IN THE CLOUDS FOR THIS AFTERNOON.
MILD SURFACE DEW POINTS AND CLOUD COVER WILL LIMIT COOLING
OVERNIGHT. LEANED TOWARD WARMER NUMBERS FOR OVERNIGHT LOWS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 AM EDT WEDNESDAY...
UPPER LOW CENTER AROUND LAFAYETTE INDIANA THIS MORNING WILL TRAVEL
EAST AND REACH THE EAST COAST ON FRIDAY. THIS LOW CENTER MOVES INTO
THE ATLANTIC BY SATURDAY...ALLOWING A SURFACE HIGH TO PUSH INTO THE
REGION JUST IN TIME FOR THE WEEKEND.
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE COLD FRONT ON
THURSDAY. KEPT THE ISOLATED TO SCATTERED POPS IN FOR THURSDAY. WENT
WITH HIGH TEMPERATURES CLOSER TO THE COOLER ADJMET WITH READINGS
FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
A COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT INTO FRIDAY.
PLACED THE HIGHEST POPS (GOOD CHANCE TO LIKELY) IN THE WEST THURSDAY
NIGHT INTO FRIDAY. LEANED TOWARDS THE WARMER MOS LOW TEMPERATURES
THURSDAY NIGHT WITH READINGS FROM THE LOWER 60S IN THE MOUNTAINS TO
NEAR 70 DEGREES IN THE PIEDMONT. HIGHS ON FRIDAY WILL VARY FROM THE
LOWER 70S IN THE WEST TO THE UPPER 80S IN THE SOUTHEAST. LOWERED
POPS FRIDAY NIGHT FROM NORTH TO SOUTH. USED THE ENSEMBLE LOWS FRIDAY
NIGHT WITH VALUES FROM LOWER 50S IN THE NORTHWEST TO THE LOWER 60S
IN THE SOUTH. UNDER THE UPPER RIDGE...PLEASANT SATURDAY ON TAP WITH
SUNSHINE AND HIGH TEMPERATURES GENERALLY FROM MID 70S TO THE LOWER
80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DURING SUNDAY...FLOW AROUND THE SURFACE HIGH WILL BRING SOUTHEAST
FLOW INTO THE SOUTHWEST PART OF THE REGION. THIS MAY YIELD SOME
ISOLATED UPSLOPE SHOWERS. A COLD FRONT IS PROGGED TO TRY TO MAKE ITS
WAY INTO THE NORTHERN PART OF THE AREA MONDAY NIGHT INTO TUESDAY.
THERE MAY BE SOME ISOLATED SHOWERS IN ADVANCE OF THIS FRONT THAT
REACH NORTHERN PARTS OF THE AREA LATE IN THE DAY MONDAY. SEVERAL
WEAK SHORTWAVES WILL DROP SOUTH IN THE NORTHWEST FLOW ALOFT ACROSS
NORTHERN PORTIONS OF OUR REGION TUESDAY INTO WEDNESDAY.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AS OF 135 AM EDT WEDNESDAY...
AREAS OF IFR CIG/VIS WILL DISSIPATE THIS MORNING BY 14Z. LEADING
EDGE OF PRECIPITATION COMING OUT OF THE SOUTHWEST WAS JUST
REACHING THE VIRGINIA/NORTH CAROLINA BORDER AT 7AM. EXPECT
EXPANDING COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH
16Z EAST OF THE BLUE RIDGE. BEST CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE MOUNTAINS WILL BE AFTER 18Z/2PM BUT WILL
CONTINUE THROUGH THE EVENING.
PATTERN WILL TRANSITION TO MORE TYPICAL OF MID AUGUST THURSDAY...WITH
SOUTHWEST FLOW AND DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS.
SCATTERED LOW CLOUDS WILL LINGER DURING THE MORNING IN AREAS...
RESULTING IN A MIXTURE OF MVFR AND VFR CONDITIONS...BEFORE
IMPROVING TO MOSTLY VFR BY EARLY AFTERNOON. PATCHY DENSE FOG
WILL ALSO BE AN ISSUE EACH NIGHT.
A FRONTAL BOUNDARY SHOULD MOVE THROUGH BY FRIDAY...POSSIBLY
PROVIDING BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS. BEHIND
THIS FRONT DRIER AIR AND VFR CONDITIONS ARE EXPECTED SATURDAY AND
SUNDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/DS
SHORT TERM...KK
LONG TERM...DS/KK
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
744 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST BY LATE THURSDAY. A COLD FRONT WILL MOVE FROM THE
GREAT LAKES ON THURSDAY INTO THE CAROLINAS BY SATURDAY. DRIER AND
COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT WEDNESDAY...
WHEN I FIRST JOINED THE NATIONAL WEATHER SERVICE MY ELDERS TOLD ME
A CODE THEY WOULD USE WHEN THERE WAS LOW CONFIDENCE IN THE
FORECAST. THEY WOULD APPEND A NUMBER 9 TO THE END OF THEIR NAME
WHEN ISSUING THE FORECAST. TODAY IS DEFINITELY A 9 DAY.
MODELS SHOWING SIGNIFICANT DIFFERENCES IN THE TIMING AND LOCATION
OF PRECIPITATION FOR TODAY AND TONIGHT. HOWEVER...THE LATEST RAP
AND HRRR GUIDANCE HAVE SOMEWHAT OF A REASONABLE TREND WITH THE
PRECIPITATION MOVING NORTH FROM THE CAROLINAS AND THE 00Z LOCAL
WRF SHOWED DECENT CONTINUITY WITH THE PRECIPITATION IN WEST
VIRGINIA.
EXPECT A MAJORITY OF THE PRECIPITATION FROM THE CAROLINAS TO MOVE
THROUGH THE FORECAST AREA THIS MORNING. BY LATE THIS
AFTERNOON...THE UPPER LOW TRACKING WEST OUT OF THE OHIO VALLEY
SHOULD BE TRIGGERING SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS.
AS THIS FEATURE MOVES EAST THIS EVENING...THE COUNTY WARNING AREA
WILL BE IN A FAVORABLE QUADRANT OF THE ASSOCIATED UPPER JET. NET
RESULT IS NOT MUCH CHANGE IN THE PROBABILITY OF PRECIPITATION FOR
TODAY AND TONIGHT.
BUFKIT SHOWED WINDS THROUGH MID LAYERS OF THE ATMOSPHERE LESS THAN
15 KNOTS...WHICH SUGGESTS INDIVIDUAL STORMS THAT DEVELOP MAY BE
MOVING SLOWLY. FLASH FLOOD GUIDANCE IS LESS THAN 2 INCHES FROM THE
NEW RIVER VALLEY AND SOUTHEAST WEST VIRGINIA INTO NORTHWEST NORTH
CAROLINA. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES TODAY
AND TONIGHT HEAVY RAIN REMAINS A THREAT.
TRENDED TOWARD GRIDDED LAMP GUIDANCE FOR MAXIMUM TEMPERATURES
TODAY...BUT WITH CLOUDS AND PRECIPITATION THIS MORNING...WITH BE
COUNTING ON SOME BREAKS IN THE CLOUDS FOR THIS AFTERNOON.
MILD SURFACE DEW POINTS AND CLOUD COVER WILL LIMIT COOLING
OVERNIGHT. LEANED TOWARD WARMER NUMBERS FOR OVERNIGHT LOWS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 AM EDT WEDNESDAY...
UPPER LOW CENTER AROUND LAFAYETTE INDIANA THIS MORNING WILL TRAVEL
EAST AND REACH THE EAST COAST ON FRIDAY. THIS LOW CENTER MOVES INTO
THE ATLANTIC BY SATURDAY...ALLOWING A SURFACE HIGH TO PUSH INTO THE
REGION JUST IN TIME FOR THE WEEKEND.
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE COLD FRONT ON
THURSDAY. KEPT THE ISOLATED TO SCATTERED POPS IN FOR THURSDAY. WENT
WITH HIGH TEMPERATURES CLOSER TO THE COOLER ADJMET WITH READINGS
FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
A COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT INTO FRIDAY.
PLACED THE HIGHEST POPS (GOOD CHANCE TO LIKELY) IN THE WEST THURSDAY
NIGHT INTO FRIDAY. LEANED TOWARDS THE WARMER MOS LOW TEMPERATURES
THURSDAY NIGHT WITH READINGS FROM THE LOWER 60S IN THE MOUNTAINS TO
NEAR 70 DEGREES IN THE PIEDMONT. HIGHS ON FRIDAY WILL VARY FROM THE
LOWER 70S IN THE WEST TO THE UPPER 80S IN THE SOUTHEAST. LOWERED
POPS FRIDAY NIGHT FROM NORTH TO SOUTH. USED THE ENSEMBLE LOWS FRIDAY
NIGHT WITH VALUES FROM LOWER 50S IN THE NORTHWEST TO THE LOWER 60S
IN THE SOUTH. UNDER THE UPPER RIDGE...PLEASANT SATURDAY ON TAP WITH
SUNSHINE AND HIGH TEMPERATURES GENERALLY FROM MID 70S TO THE LOWER
80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DURING SUNDAY...FLOW AROUND THE SURFACE HIGH WILL BRING SOUTHEAST
FLOW INTO THE SOUTHWEST PART OF THE REGION. THIS MAY YIELD SOME
ISOLATED UPSLOPE SHOWERS. A COLD FRONT IS PROGGED TO TRY TO MAKE ITS
WAY INTO THE NORTHERN PART OF THE AREA MONDAY NIGHT INTO TUESDAY.
THERE MAY BE SOME ISOLATED SHOWERS IN ADVANCE OF THIS FRONT THAT
REACH NORTHERN PARTS OF THE AREA LATE IN THE DAY MONDAY. SEVERAL
WEAK SHORTWAVES WILL DROP SOUTH IN THE NORTHWEST FLOW ALOFT ACROSS
NORTHERN PORTIONS OF OUR REGION TUESDAY INTO WEDNESDAY.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 135 AM EDT WEDNESDAY...
AREAS OF IFR CIG/VIS WILL DISSIPATE THIS MORNING BY 14Z. LEADING
EDGE OF PRECIPITATION COMING OUT OF THE SOUTHWEST WAS JUST
REACHING THE VIRGINIA/NORTH CAROLINA BORDER AT 7AM. EXPECT
EXPANDING COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH
16Z EAST OF THE BLUE RIDGE. BEST CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE MOUNTAINS WILL BE AFTER 18Z/2PM BUT WILL
CONTINUE THROUGH THE EVENING.
PATTERN WILL TRANSITION TO MORE TYPICAL OF MID AUGUST THURSDAY...WITH
SOUTHWEST FLOW AND DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS.
SCATTERED LOW CLOUDS WILL LINGER DURING THE MORNING IN AREAS...
RESULTING IN A MIXTURE OF MVFR AND VFR CONDITIONS...BEFORE
IMPROVING TO MOSTLY VFR BY EARLY AFTERNOON. PATCHY DENSE FOG
WILL ALSO BE AN ISSUE EACH NIGHT.
A FRONTAL BOUNDARY SHOULD MOVE THROUGH BY FRIDAY...POSSIBLY
PROVIDING BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS. BEHIND
THIS FRONT DRIER AIR AND VFR CONDITIONS ARE EXPECTED SATURDAY AND
SUNDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...KK
LONG TERM...DS/KK
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
428 AM EDT WED AUG 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE FROM THE OHIO VALLEY TO THE MID
ATLANTIC COAST BY LATE THURSDAY. A COLD FRONT WILL MOVE FROM THE
GREAT LAKES ON THURSDAY INTO THE CAROLINAS BY SATURDAY. DRIER AND
COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT WEDNESDAY...
WHEN I FIRST JOINED THE NATIONAL WEATHER SERVICE MY ELDERS TOLD ME
A CODE THEY WOULD USE WHEN THERE WAS LOW CONFIDENCE IN THE
FORECAST. THEY WOULD APPEND A NUMBER 9 TO THE END OF THEIR NAME
WHEN ISSUING THE FORECAST. TODAY IS DEFINITELY A 9 DAY.
MODELS SHOWING SIGNIFICANT DIFFERENCES IN THE TIMING AND LOCATION
OF PRECIPITATION FOR TODAY AND TONIGHT. HOWEVER...THE LATEST RAP
AND HRRR GUIDANCE HAVE SOMEWHAT OF A REASONABLE TREND WITH THE
PRECIPITATION MOVING NORTH FROM THE CAROLINAS AND THE 00Z LOCAL
WRF SHOWED DECENT CONTINUITY WITH THE PRECIPITATION IN WEST
VIRGINIA.
EXPECT A MAJORITY OF THE PRECIPITATION FROM THE CAROLINAS TO MOVE
THROUGH THE FORECAST AREA THIS MORNING. BY LATE THIS
AFTERNOON...THE UPPER LOW TRACKING WEST OUT OF THE OHIO VALLEY
SHOULD BE TRIGGERING SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS.
AS THIS FEATURE MOVES EAST THIS EVENING...THE COUNTY WARNING AREA
WILL BE IN A FAVORABLE QUADRANT OF THE ASSOCIATED UPPER JET. NET
RESULT IS NOT MUCH CHANGE IN THE PROBABILITY OF PRECIPITATION FOR
TODAY AND TONIGHT.
BUFKIT SHOWED WINDS THROUGH MID LAYERS OF THE ATMOSPHERE LESS THAN
15 KNOTS...WHICH SUGGESTS INDIVIDUAL STORMS THAT DEVELOP MAY BE
MOVING SLOWLY. FLASH FLOOD GUIDANCE IS LESS THAN 2 INCHES FROM THE
NEW RIVER VALLEY AND SOUTHEAST WEST VIRGINIA INTO NORTHWEST NORTH
CAROLINA. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES TODAY
AND TONIGHT HEAVY RAIN REMAINS A THREAT.
TRENDED TOWARD GRIDDED LAMP GUIDANCE FOR MAXIMUM TEMPERATURES
TODAY...BUT WITH CLOUDS AND PRECIPITATION THIS MORNING...WITH BE
COUNTING ON SOME BREAKS IN THE CLOUDS FOR THIS AFTERNOON.
MILD SURFACE DEW POINTS AND CLOUD COVER WILL LIMIT COOLING
OVERNIGHT. LEANED TOWARD WARMER NUMBERS FOR OVERNIGHT LOWS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 330 AM EDT WEDNESDAY...
UPPER LOW CENTER AROUND LAFAYETTE INDIANA THIS MORNING WILL TRAVEL
EAST AND REACH THE EAST COAST ON FRIDAY. THIS LOW CENTER MOVES INTO
THE ATLANTIC BY SATURDAY...ALLOWING A SURFACE HIGH TO PUSH INTO THE
REGION JUST IN TIME FOR THE WEEKEND.
SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE COLD FRONT ON
THURSDAY. KEPT THE ISOLATED TO SCATTERED POPS IN FOR THURSDAY. WENT
WITH HIGH TEMPERATURES CLOSER TO THE COOLER ADJMET WITH READINGS
FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
A COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT INTO FRIDAY.
PLACED THE HIGHEST POPS (GOOD CHANCE TO LIKELY) IN THE WEST THURSDAY
NIGHT INTO FRIDAY. LEANED TOWARDS THE WARMER MOS LOW TEMPERATURES
THURSDAY NIGHT WITH READINGS FROM THE LOWER 60S IN THE MOUNTAINS TO
NEAR 70 DEGREES IN THE PIEDMONT. HIGHS ON FRIDAY WILL VARY FROM THE
LOWER 70S IN THE WEST TO THE UPPER 80S IN THE SOUTHEAST. LOWERED
POPS FRIDAY NIGHT FROM NORTH TO SOUTH. USED THE ENSEMBLE LOWS FRIDAY
NIGHT WITH VALUES FROM LOWER 50S IN THE NORTHWEST TO THE LOWER 60S
IN THE SOUTH. UNDER THE UPPER RIDGE...PLEASANT SATURDAY ON TAP WITH
SUNSHINE AND HIGH TEMPERATURES GENERALLY FROM MID 70S TO THE LOWER
80S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 115 PM EDT TUESDAY...
DURING SUNDAY...FLOW AROUND THE SURFACE HIGH WILL BRING SOUTHEAST
FLOW INTO THE SOUTHWEST PART OF THE REGION. THIS MAY YIELD SOME
ISOLATED UPSLOPE SHOWERS. A COLD FRONT IS PROGGED TO TRY TO MAKE ITS
WAY INTO THE NORTHERN PART OF THE AREA MONDAY NIGHT INTO TUESDAY.
THERE MAY BE SOME ISOLATED SHOWERS IN ADVANCE OF THIS FRONT THAT
REACH NORTHERN PARTS OF THE AREA LATE IN THE DAY MONDAY. SEVERAL
WEAK SHORTWAVES WILL DROP SOUTH IN THE NORTHWEST FLOW ALOFT ACROSS
NORTHERN PORTIONS OF OUR REGION TUESDAY INTO WEDNESDAY.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AS OF 135 AM EDT WEDNESDAY...
WITH MORE CLOUDS EARLY THIS MORNING...AREAS OF IFR CIG/VIS MAY BE
LESS EXPANSIVE AND PERSISTENT THAN TUESDAY MORNING. MID AND HIGH
CLOUDS STRETCH FROM THE MID ATLANTIC ALL THE WAY INTO THE GULF
COAST STATES. AS USUAL LWB SEEMS THE MOST LIKELY TO EXPERIENCE
LIFR/IFR CONDS.
A BETTER UPPER SHORT WAVE IS EXPECTED TO MOVE IN EARLY TODAY...AND
THIS SHOULD RESULT IN BETTER COVERAGE OF SHOWERS AND
THUNDERSTORMS...ESPECIALLY IN THE MOUNTAINS...PERHAPS AS EARLY AS
MID MORNING...SOME WELL BEFORE 18Z. CLOSET PRECIPITATION WITH THIS
SHORT WAVE AT 1AM WAS IN CENTRAL GEORGIA...SO FUTURE TAF UPDATES
MAY END UP SLOWING DOWN ARRIVAL TIME OF SHOWERS AND THUNDERSTORMS.
PATTERN WILL TRANSITION TO MORE TYPICAL OF MID AUGUST THURSDAY...WITH
SOUTHWEST FLOW AND DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS.
SCATTERED LOW CLOUDS WILL LINGER DURING THE MORNING IN AREAS...
RESULTING IN A MIXTURE OF MVFR AND VFR CONDITIONS...BEFORE
IMPROVING TO MOSTLY VFR BY EARLY AFTERNOON. PATCHY DENSE FOG WILL
ALSO BE AN ISSUE EACH NIGHT. A FRONTAL BOUNDARY SHOULD MOVE
THROUGH BY FRIDAY...POSSIBLY PROVIDING BETTER COVERAGE OF SHOWERS
AND THUNDERSTORMS. BEHIND THIS FRONT DRIER AIR AND VFR CONDITIONS
ARE EXPECTED SATURDAY AND SUNDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS9
SHORT TERM...KK
LONG TERM...DS/KK
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS SPOKANE WA
752 PM PDT Thu Aug 22 2013
.SYNOPSIS...
A potent storm system will bring scattered showers and
thunderstorms through the region tonight into Friday. Unsettled
conditions will continue across the Inland Northwest over the
weekend and majority of next week as a moist southwest flow
pattern remains in place.
&&
.DISCUSSION...
Update: A very active night is expected across eastern WA and in
the ID Panhandle. It appears there will be two focuses of
convection tonight into Friday. The first area of convection is
beginning to nudge northward into the region out of northeastern
OR. High resolution models, including the HRRR and 4 km NAM,
suggests a band of convection will push northward across the
region this evening into the overnight hours. This convection will
be forced by a deformation zone wrapping around the northeast
quadrant of the upper level low pressure system. The center of the low
can be seen on satellite spinning its way into southwest OR at
7:30 PM. Models are in general agreement that the best mid and
upper level instability will lie across the eastern two-thirds of
the forecast area and especially across the southeastern portion.
This is where we will see the best chances for seeing more
scattered thunderstorm activity with this first wave. I do believe
that showers will wrap around into the east slopes of the northern
Cascades with scattered showers expected, but instability
parameters would suggest that the lightning activity will be more
isolated in coverage.
The second focus of convection will come with the upper level low
as it ejects across the region. The center of the low is expected
to enter southwest WA late tonight with a vorticity maximum at the
base of the trough swinging northward across the region through
Friday morning. This will likely produce more thunderstorms out
ahead of the trough. The best instability will continue to lie
across the eastern portions of the forecast area where the best
chances of thunderstorms will be; however, some isolated
thunderstorms will be possible as far weest as the Cascade crest.
Thunderstorm chances will be decreasing from southwest to
northeast behind the upper level trough through Friday and is
expected to exit the region during the early afternoon hours. The
Red Flag Warning will remain as is for now as most of the lighting
appears it will occur where we currently have the highlight out.
We will see a surface low pressure system spin up out ahead of the
upper level trough tonight over eastern WA. This low will then
push east through Friday. A tightening pressure gradient with the
possibility of some gusty winds from collapsing thunderstorms could
result some stronger wind gusts tonight into Friday morning. /SVH
&&
.AVIATION...
00Z TAFS: The only possible MVFR condition will be from wildfire
smoke around KEAT, but the threat is not significant enough at this
time to include in the TAF forecast. A low pressure system moving
northward toward the region is expected to kick off some higher
based thunderstorms through Friday morning. Two waves of convection
will be possible. The first wave will move through this evening from
the south along a deformation axis that will span west to east
across eastern WA and the ID Panhandle. A second batch of
thunderstorms will be possible as the upper level low moves through
from southwest to northeast Friday morning into early Friday
afternoon. Thunderstorms will be capable of frequent cloud to ground
lightning strikes and gusty outflow winds. Thunderstorms are
expected to taper off near the TAF sites through Friday afternoon,
but will leave some breezy southwesterly winds in its wake. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 81 59 83 61 81 / 40 50 10 10 30 20
Coeur d`Alene 57 79 54 84 57 82 / 40 50 10 10 30 20
Pullman 57 80 55 83 55 81 / 50 50 10 10 20 20
Lewiston 66 87 62 90 62 87 / 50 50 10 10 20 20
Colville 55 85 52 85 56 85 / 20 50 10 20 20 20
Sandpoint 53 77 49 82 53 80 / 30 50 10 10 30 30
Kellogg 56 77 52 83 54 81 / 40 50 10 10 20 20
Moses Lake 65 87 59 83 61 83 / 30 40 10 20 20 20
Wenatchee 65 86 60 82 61 81 / 40 30 10 20 10 30
Omak 61 87 57 84 59 84 / 30 40 10 20 20 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning from 11 PM this evening to 2 PM PDT Friday for
Northern and Central Idaho Panhandle (Zone 101).
WA...Red Flag Warning from 11 PM this evening to 2 PM PDT Friday for
East Washington Northeast (Zone 686)-East Washington
Northern Columbia Basin (Zone 673)-East Washington Okanogan
Highlands (Zone 687)-East Washington Palouse and Spokane
Area (Zone 674).
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1035 PM CDT THU AUG 22 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...
ISSUED AT 908 PM CDT THU AUG 22 2013
A MAJOR COMMUNICATIONS DISRUPTION AT THE NWS TELECOMMUNICATIONS
GATEWAY HAS RESULTED IN PRETTY MUCH A TOTAL LOSS OF SFC DATA FM
ACRS THE RGN. 00Z RAOB AVAILABILITY FOR AT LEAST THE NAM HAS ALSO
BEEN AFFECTED.
USERS OF OUR CLIMATE PRODUCTS SHOULD NOTE THAT THE THE ORIGINAL
EVENING TEMPERATURE AND PRECIPITATION SUMMARY PRODUCT /MKERTPGRB
A.K.A. ASUS63/ DID NOT CONTAIN THE CORRECT MAXIMUM TEMPERATURES
FOR GRB...AUW...RHI...OSH...ISW...MFI...Y50... AND SUE. A
CORRECTED VERSION WAS ISSUED AT 856 PM.
VALUES LISTED IN THE DAILY CLIMATE SUMMARY PRODUCTS /MKECLIGRB AND
MKECLIRHI A.K.A. CDUS43/ FOR GRB AND RHI ARE CORRECT. THE VALUE
LISTED IN THE AUW PRODUCT WAS INCORRECT...AND AN UPDATED PRODUCT
WAS ISSUED AT 922 PM. WE APOLOGIZE FOR ANY INCONVENIENCE THE
INITIALLY INCORRECT DATA MAY CAUSE.
MANUALLY DIALING AROUND TO THE ASOS/AWOS SENSORS IN THE FCST AREA
AROUND 02Z INDICATED SFC DWPT DEPRESSIONS RANGING FROM 8 C DEG
/RHI/ TO 0 C DEG /Y50/. GIVEN THE CLEAR SKIES AND LGT WINDS
EXPECTED OVERNIGHT...THE SPREADS WERE FAIRLY SMALL AND IT SEEMED
LIKE FOG MAY BE A BIGGER ISSUE OVERNIGHT THAN ORIGINALLY
ANTICIPATED. WL HIT FOG A LITTLE HARDER IN THE FCST AND ADD A
MENTION IN THE HWO. UPDATE PRODUCT SUITE WL BE OUT ASAP.
&&
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SLOWLY
WEAKENING MCS MOVING OVER SOUTHERN LAKE MICHIGAN EARLY THIS
AFTERNOON. BACK EDGE OF THE CLOUD SHIELD ASSOCIATED WITH THIS MCS
IS MOVING SE OVER CENTRAL AND NORTHEAST WISCONSIN. DEWPOINTS ACROSS
NORTHERN WISCONSIN HAVE MIXED OUT INTO THE MIDDLE 40S...WHILE THE
DRIER AIR IS SLOWLY MOVING INTO EAST-CENTRAL WISCONSIN WHERE
READINGS ARE STILL IN THE UPPER 50S. PLENTY OF CLEAR SKIES UPSTREAM
OVER THE NORTHERN PLAINS AND SOUTH-CENTRAL CANADA WHERE SURFACE HIGH
PRESSURE IS SHIFTING TO THE SOUTHEAST. AS HIGH PRESSURE MOVES
TOWARDS THE REGION...FOG POTENTIAL TONIGHT AND TEMPS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE
NORTHERN GREAT LAKES. AS THIS OCCURS...SKIES WILL BECOME CLEAR AND
WINDS WILL TURN LIGHT AND VARIABLE...SETTING UP GOOD RADIATIONAL
COOLING CONDITIONS. DEWPOINTS HAVE FALLEN INTO THE MIDDLE 40S
ACROSS NORTHERN WISCONSIN THIS AFTERNOON...WHILE THEY REMAIN IN THE
MIDDLE 50S TO LOWER 60S OVER CENTRAL AND EAST-CENTRAL WISCONSIN.
SOME MIXING OUT IS STILL EXPECTED...LOW TEMPS ARE EXPECTED TO
FALL NEAR OR BELOW THESE READINGS ACROSS MOST LOCATIONS. WITH THE
RECENT RAINFALL...WILL ADD PATCHY FOG TO THE FORECAST. LOWS NEAR 40
DEGREES AT THE COLD SPOTS OF N-C WISCONSIN AND THE MID 50S SOUTH.
FRIDAY...HIGH PRESSURE WILL REMAIN ACROSS THE AREA. OUTSIDE OF SCT
DIURNAL CU...SHOULD SEE PLENTY OF SUN AND LOW RELATIVE HUMIDITY.
HIGHS MOSTLY IN THE UPPER 70S TO LOWER 80S...LOCALLY COOLER NEAR
LAKE MICHIGAN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
CONCERNS THIS PERIOD WILL BE HEAT...WITH TEMPS EXPECTED TO RUN
WELL ABOVE NORMAL AND HUMIDITY LEVELS INCREASING THROUGH THE
PERIOD. MEDIUM RANGE MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT
THROUGH THE EXTENDED WITH THE LARGE SCALE. STRONG RIDGE ANCHORED
BY 596 CENTER EXPECTED TO BE FOUND OVER THE CENTRAL PORTION OF THE
U.S. DIFFERENCES OCCUR WITH SMALL SCALE FEATURES...S/W`S MOVING
THROUGH SW FLOW OVER RIDGE AND WITH EXPECTED LOCATION OF SURFACE
BOUNDARY. OVERALL 850 TEMPS TO RUN WELL ABOVE NORMAL BY AT LEAST
TWO STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCAL TEMPERATURE
TOOLS WOULD SUGGEST TEMPS INTO THE 90`S MONDAY ONWARD.
FOR MUCH OF THIS FORECAST USED A BLEND OF GFS/ECMWF...THOUGH WENT
MORE WITH EC TUE ONWARD AS GFS APPEARS TO BE TOO STRONG WITH
SURFACE FEATURES. WARM MID LEVEL TEMPS WOULD ALSO SUGGEST
ATMOSPHERE WOULD BE CAPPED FOR CONVECTION THOUGH SFC FRONT
EXPECTED TO MOVE NORTH THROUGH REGION SAT NIGHT/SUN. BOTH GFS AND
ECMWF DROP FRONT BACK SOUTH INTO NORTHERN WI WED/THU BEFORE
LIFTING IT BACK NORTH BEYOND THIS FORECAST PERIOD. WILL ONLY GO
WITH SLIGHT CHANCE/CHANCE POPS THROUGH PERIOD. OVERALL BEST CHANCE
FOR STRONG TO SEVERE STORMS...IF ANY..WOULD BE WED/THU TIME FRAME
AS SHEER INCREASES AS JET DROPS SOUTH.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1030 PM CDT THU AUG 22 2013
NEW MET GUID STILL NOT DOING MUCH WITH FG OVERNIGHT. BUT IT ALSO
SHOWS 4-6 KTS OF WIND AT MOST SITES...WHILE THE MAJORITY OF OB
SITES ARE ALREADY CALM. FOG PRODUCTS IN BUFKIT SUGGEST HYDRO
LAPSE RATES WL BE UNFAVORABLE FOR FG IN GRB...BUT MARGINALLY
FAVORABLE IN C/N-C WI. WL CONT TO CARRY SOME FG LATE TNGT AS IN
PREV COUPLE TAF ISSUANCES. VFR CONDITIONS EXPECTED ONCE ANY FOG
BURNS OFF TOMORROW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
930 PM CDT THU AUG 22 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 908 PM CDT THU AUG 22 2013
A MAJOR COMMUNICATIONS DISRUPTION AT THE NWS TELECOMMUNICATIONS
GATEWAY HAS RESULTED IN PRETTY MUCH A TOTAL LOSS OF SFC DATA FM
ACRS THE RGN. 00Z RAOB AVAILABILITY FOR AT LEAST THE NAM HAS ALSO
BEEN AFFECTED.
USERS OF OUR CLIMATE PRODUCTS SHOULD NOTE THAT THE THE ORIGINAL
EVENING TEMPERATURE AND PRECIPITATION SUMMARY PRODUCT /MKERTPGRB
A.K.A. ASUS63/ DID NOT CONTAIN THE CORRECT MAXIMUM TEMPERATURES
FOR GRB...AUW...RHI...OSH...ISW...MFI...Y50... AND SUE. A
CORRECTED VERSION WAS ISSUED AT 856 PM.
VALUES LISTED IN THE DAILY CLIMATE SUMMARY PRODUCTS /MKECLIGRB AND
MKECLIRHI A.K.A. CDUS43/ FOR GRB AND RHI ARE CORRECT. THE VALUE
LISTED IN THE AUW PRODUCT WAS INCORRECT...AND AN UPDATED PRODUCT
WAS ISSUED AT 922 PM. WE APOLOGIZE FOR ANY INCONVENIENCE THE
INITIALLY INCORRECT DATA MAY CAUSE.
MANUALLY DIALING AROUND TO THE ASOS/AWOS SENSORS IN THE FCST AREA
AROUND 02Z INDICATED SFC DWPT DEPRESSIONS RANGING FROM 8 C DEG
/RHI/ TO 0 C DEG /Y50/. GIVEN THE CLEAR SKIES AND LGT WINDS
EXPECTED OVERNIGHT...THE SPREADS WERE FAIRLY SMALL AND IT SEEMED
LIKE FOG MAY BE A BIGGER ISSUE OVERNIGHT THAN ORIGINALLY
ANTICIPATED. WL HIT FOG A LITTLE HARDER IN THE FCST AND ADD A
MENTION IN THE HWO. UPDATE PRODUCT SUITE WL BE OUT ASAP.
&&
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SLOWLY
WEAKENING MCS MOVING OVER SOUTHERN LAKE MICHIGAN EARLY THIS
AFTERNOON. BACK EDGE OF THE CLOUD SHIELD ASSOCIATED WITH THIS MCS
IS MOVING SE OVER CENTRAL AND NORTHEAST WISCONSIN. DEWPOINTS ACROSS
NORTHERN WISCONSIN HAVE MIXED OUT INTO THE MIDDLE 40S...WHILE THE
DRIER AIR IS SLOWLY MOVING INTO EAST-CENTRAL WISCONSIN WHERE
READINGS ARE STILL IN THE UPPER 50S. PLENTY OF CLEAR SKIES UPSTREAM
OVER THE NORTHERN PLAINS AND SOUTH-CENTRAL CANADA WHERE SURFACE HIGH
PRESSURE IS SHIFTING TO THE SOUTHEAST. AS HIGH PRESSURE MOVES
TOWARDS THE REGION...FOG POTENTIAL TONIGHT AND TEMPS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE
NORTHERN GREAT LAKES. AS THIS OCCURS...SKIES WILL BECOME CLEAR AND
WINDS WILL TURN LIGHT AND VARIABLE...SETTING UP GOOD RADIATIONAL
COOLING CONDITIONS. DEWPOINTS HAVE FALLEN INTO THE MIDDLE 40S
ACROSS NORTHERN WISCONSIN THIS AFTERNOON...WHILE THEY REMAIN IN THE
MIDDLE 50S TO LOWER 60S OVER CENTRAL AND EAST-CENTRAL WISCONSIN.
SOME MIXING OUT IS STILL EXPECTED...LOW TEMPS ARE EXPECTED TO
FALL NEAR OR BELOW THESE READINGS ACROSS MOST LOCATIONS. WITH THE
RECENT RAINFALL...WILL ADD PATCHY FOG TO THE FORECAST. LOWS NEAR 40
DEGREES AT THE COLD SPOTS OF N-C WISCONSIN AND THE MID 50S SOUTH.
FRIDAY...HIGH PRESSURE WILL REMAIN ACROSS THE AREA. OUTSIDE OF SCT
DIURNAL CU...SHOULD SEE PLENTY OF SUN AND LOW RELATIVE HUMIDITY.
HIGHS MOSTLY IN THE UPPER 70S TO LOWER 80S...LOCALLY COOLER NEAR
LAKE MICHIGAN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
CONCERNS THIS PERIOD WILL BE HEAT...WITH TEMPS EXPECTED TO RUN
WELL ABOVE NORMAL AND HUMIDITY LEVELS INCREASING THROUGH THE
PERIOD. MEDIUM RANGE MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT
THROUGH THE EXTENDED WITH THE LARGE SCALE. STRONG RIDGE ANCHORED
BY 596 CENTER EXPECTED TO BE FOUND OVER THE CENTRAL PORTION OF THE
U.S. DIFFERENCES OCCUR WITH SMALL SCALE FEATURES...S/W`S MOVING
THROUGH SW FLOW OVER RIDGE AND WITH EXPECTED LOCATION OF SURFACE
BOUNDARY. OVERALL 850 TEMPS TO RUN WELL ABOVE NORMAL BY AT LEAST
TWO STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCAL TEMPERATURE
TOOLS WOULD SUGGEST TEMPS INTO THE 90`S MONDAY ONWARD.
FOR MUCH OF THIS FORECAST USED A BLEND OF GFS/ECMWF...THOUGH WENT
MORE WITH EC TUE ONWARD AS GFS APPEARS TO BE TOO STRONG WITH
SURFACE FEATURES. WARM MID LEVEL TEMPS WOULD ALSO SUGGEST
ATMOSPHERE WOULD BE CAPPED FOR CONVECTION THOUGH SFC FRONT
EXPECTED TO MOVE NORTH THROUGH REGION SAT NIGHT/SUN. BOTH GFS AND
ECMWF DROP FRONT BACK SOUTH INTO NORTHERN WI WED/THU BEFORE
LIFTING IT BACK NORTH BEYOND THIS FORECAST PERIOD. WILL ONLY GO
WITH SLIGHT CHANCE/CHANCE POPS THROUGH PERIOD. OVERALL BEST CHANCE
FOR STRONG TO SEVERE STORMS...IF ANY..WOULD BE WED/THU TIME FRAME
AS SHEER INCREASES AS JET DROPS SOUTH.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 606 PM CDT THU AUG 22 2013
LITTLE CHG TO PREV THINKING FOR AVIATION FCST. MOS GUIDANCE STILL
NOT INDICATING ANY FOG...AND LATE AFTN SFC DWPT DEPRESSIONS QUITE
LARGE. HOWEVER WITH CLR SKIES AND LGT WINDS...TEMPS SHOULD BE
ABLE TO FALL TO DWPTS BY LATE TNGT. WL CONT TREND OF PREV FCST IN
HAVING SOME FOG IN FOR A FEW HRS BEFORE SUNRISE...THEN VFR
CONDITIONS THEREAFTER.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
610 PM CDT THU AUG 22 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SLOWLY
WEAKENING MCS MOVING OVER SOUTHERN LAKE MICHIGAN EARLY THIS
AFTERNOON. BACK EDGE OF THE CLOUD SHIELD ASSOCIATED WITH THIS MCS
IS MOVING SE OVER CENTRAL AND NORTHEAST WISCONSIN. DEWPOINTS ACROSS
NORTHERN WISCONSIN HAVE MIXED OUT INTO THE MIDDLE 40S...WHILE THE
DRIER AIR IS SLOWLY MOVING INTO EAST-CENTRAL WISCONSIN WHERE
READINGS ARE STILL IN THE UPPER 50S. PLENTY OF CLEAR SKIES UPSTREAM
OVER THE NORTHERN PLAINS AND SOUTH-CENTRAL CANADA WHERE SURFACE HIGH
PRESSURE IS SHIFTING TO THE SOUTHEAST. AS HIGH PRESSURE MOVES
TOWARDS THE REGION...FOG POTENTIAL TONIGHT AND TEMPS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE
NORTHERN GREAT LAKES. AS THIS OCCURS...SKIES WILL BECOME CLEAR AND
WINDS WILL TURN LIGHT AND VARIABLE...SETTING UP GOOD RADIATIONAL
COOLING CONDITIONS. DEWPOINTS HAVE FALLEN INTO THE MIDDLE 40S
ACROSS NORTHERN WISCONSIN THIS AFTERNOON...WHILE THEY REMAIN IN THE
MIDDLE 50S TO LOWER 60S OVER CENTRAL AND EAST-CENTRAL WISCONSIN.
SOME MIXING OUT IS STILL EXPECTED...LOW TEMPS ARE EXPECTED TO
FALL NEAR OR BELOW THESE READINGS ACROSS MOST LOCATIONS. WITH THE
RECENT RAINFALL...WILL ADD PATCHY FOG TO THE FORECAST. LOWS NEAR 40
DEGREES AT THE COLD SPOTS OF N-C WISCONSIN AND THE MID 50S SOUTH.
FRIDAY...HIGH PRESSURE WILL REMAIN ACROSS THE AREA. OUTSIDE OF SCT
DIURNAL CU...SHOULD SEE PLENTY OF SUN AND LOW RELATIVE HUMIDITY.
HIGHS MOSTLY IN THE UPPER 70S TO LOWER 80S...LOCALLY COOLER NEAR
LAKE MICHIGAN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 243 PM CDT THU AUG 22 2013
CONCERNS THIS PERIOD WILL BE HEAT...WITH TEMPS EXPECTED TO RUN
WELL ABOVE NORMAL AND HUMIDITY LEVELS INCREASING THROUGH THE
PERIOD. MEDIUM RANGE MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT
THROUGH THE EXTENDED WITH THE LARGE SCALE. STRONG RIDGE ANCHORED
BY 596 CENTER EXPECTED TO BE FOUND OVER THE CENTRAL PORTION OF THE
U.S. DIFFERENCES OCCUR WITH SMALL SCALE FEATURES...S/W`S MOVING
THROUGH SW FLOW OVER RIDGE AND WITH EXPECTED LOCATION OF SURFACE
BOUNDARY. OVERALL 850 TEMPS TO RUN WELL ABOVE NORMAL BY AT LEAST
TWO STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCAL TEMPERATURE
TOOLS WOULD SUGGEST TEMPS INTO THE 90`S MONDAY ONWARD.
FOR MUCH OF THIS FORECAST USED A BLEND OF GFS/ECMWF...THOUGH WENT
MORE WITH EC TUE ONWARD AS GFS APPEARS TO BE TOO STRONG WITH
SURFACE FEATURES. WARM MID LEVEL TEMPS WOULD ALSO SUGGEST
ATMOSPHERE WOULD BE CAPPED FOR CONVECTION THOUGH SFC FRONT
EXPECTED TO MOVE NORTH THROUGH REGION SAT NIGHT/SUN. BOTH GFS AND
ECMWF DROP FRONT BACK SOUTH INTO NORTHERN WI WED/THU BEFORE
LIFTING IT BACK NORTH BEYOND THIS FORECAST PERIOD. WILL ONLY GO
WITH SLIGHT CHANCE/CHANCE POPS THROUGH PERIOD. OVERALL BEST CHANCE
FOR STRONG TO SEVERE STORMS...IF ANY..WOULD BE WED/THU TIME FRAME
AS SHEER INCREASES AS JET DROPS SOUTH.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 606 PM CDT THU AUG 22 2013
LITTLE CHG TO PREV THINKING FOR AVIATION FCST. MOS GUIDANCE STILL
NOT INDICATING ANY FOG...AND LATE AFTN SFC DWPT DEPRESSIONS QUITE
LARGE. HOWEVER WITH CLR SKIES AND LGT WINDS...TEMPS SHOULD BE
ABLE TO FALL TO DWPTS BY LATE TNGT. WL CONT TREND OF PREV FCST IN
HAVING SOME FOG IN FOR A FEW HRS BEFORE SUNRISE...THEN VFR
CONDITIONS THEREAFTER.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
340 PM CDT WED AUG 21 2013
.VERY SHORT TERM...TONIGHT AND THURSDAY.
CONVECTION IS FIRING UP ALONG THE SURFACE COLD FRONT FROM NORTHWEST
WI THROUGH THE TWIN CITIES AREA. THIS LINES UP WELL WITH THE NCEP
4KM WRF-NMM SIMULATED RADAR REFLECTIVITY. THAT MODEL BRINGS A LINE
OF CONVECTION SOUTHEAST INTO THE MKX FORECAST AREA 01Z-02Z...THEN
ALLOWS IT TO WEAKEN. IT SHOWS A SLIGHTLY STRONGER AREA OF CONVECTION
CONTINUING IN SOUTHEAST WI BUT MUCH LESS CONVECTION IN SOUTH CENTRAL
WI. SOME OF THE OTHER MODELS ARE SHOWING THIS SPLIT AS WELL..SO IT
WILL BE SOMETHING TO WATCH OUT FOR. MEANWHILE...THE 18Z HRRR MODEL
RUN SHOWS THAT CONVECTION IN NORTHWEST WI...BRINGS IT EASTWARD AS A
BLOB...AND NEVER EXTENDS ANY CONVECTION DOWN INTO SOUTHERN WI AT
ALL.
MOST CONVECTION WILL LIKELY BE ALONG THE IL BORDER BY 06Z AND ENDING
SHORTLY THEREAFTER. MID LEVEL DRY AIR MOVES IN QUICKLY BEHIND THE
FRONT AND ANY SEVERE THREAT WILL BE GONE BY 06Z.
AS FOR SEVERE POTENTIAL...THE BEST RISK OF SEVERE WEATHER WILL BE
OVER NORTH CENTRAL WI. THIS IS WHERE THE SPC STORM SCALE ENSEMBLE OF
OPPORTUNITY BULLSEYES THE HIGHEST 24-HOUR PROBABILITY OF HIGH
UPDRAFT HELICITY AND HIGH UPDRAFT SPEED. THIS IS ALSO WHERE THERE IS
A SEVERE THUNDERSTORM WATCH IN EFFECT RIGHT NOW.
SPC HAS THE SLIGHT RISK INCLUDING MADISON AND WEST BEND. THIS SEEMS
REASONABLE BASED ON MODEL FORECAST REFLECTIVITIES. ANY STRONGER AND
ORGANIZED STORMS THAT DEVELOP OVER CENTRAL WI COULD SWEEP SOUTH AND
SOUTHEAST WITH A DAMAGING STRAIGHT-LINE WIND THREAT INTO THE
NORTHERN MKX FORECAST AREA. WITH CAPE VALUES EXCEEDING 3000 J/KG AND
MODERATE 0-3 AND 0-6KM SHEAR...LARGE HAIL WILL BE POSSIBLE AS WELL.
AS STORMS MAKE IT FURTHER INTO SOUTH CENTRAL AND SOUTHEAST WI LATER
THIS EVENING...SURFACE BASED CAPE AND BULK SHEAR VALUES DECREASE
GIVEN THE TIME OF DAY AND THE SURFACE TROUGH LOSING DEFINITION. ALSO
THE 850MB LEADING EDGE OF THE LOW LEVEL JET AND WARM AIR ADVECTION
WILL BE SHIFTING EAST OVER LAKE MICHIGAN.
THERE IS ANOTHER SHORTWAVE THAT WILL TRACK ALONG THE 850MB
BAROCLINIC ZONE THROUGH NORTHERN IOWA AND EVENTUALLY INTO NORTHERN
IL LATE TONIGHT/THU MORNING. CONVECTION WITH THIS FEATURE MAY CLIP
SOUTHERN WI SO LEFT A SMALL CHANCE FOR THUNDER THROUGH THU MORNING.
SUNSHINE IS EXPECTED LATER THURSDAY...ALLOWING MAX TEMPS IN THE
UPPER 70S AND LOWER 80S WITH A NORTH TO NORTHEAST BREEZE.
.SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY.
A QUIET PERIOD IS ANTICIPATED AS HIGH PRESSURE AT THE SURFACE AND
ALOFT CONTINUES TO BUILD INTO THE WESTERN GREAT LAKES TO CENTRAL MS
VALLEY. LIGHT WINDS BELOW SHALLOW INVERSION SHOULD ALLOW PATCHY FOG
TO DEVELOP IN THE WI RIVER VLY LATER THU NIGHT. BOUNDARY LAYER
MIXING JUST ABOVE INVERSION SHOULD PREVENT SIGNIFICANT FOG ELSEWHERE
HOWEVER. WARMER AIR STARTS TO RETURN ON SATURDAY AS LOW LEVEL WINDS
TURN MORE SOUTH. ANY CONVECTION ASSOCIATED WITH PUSH OF WARM AIR
AND WEAK SHORT WAVE IS EXPECTED TO REMAIN TO THE NORTH OF CWA ON
SAT.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY.
MEDIUM RANGE GUIDANCE IN GOOD AGREEMENT ON EXPANSIVE HIGH PRESSURE
RIDGE OVER SOUTHERN CONUS EXPANDING NORTHWARD AND ENVELOPING
SOUTHERN WI ON SATURDAY AND PERSISTING THROUGH THE FIRST PORTION OF
NEXT WEEK. 500H HEIGHTS INCREASE TO AROUND 591 METERS WHILE 85H
TEMPS INCREASE TO 19 TO 22C. HENCE A VERY WARM PERIOD IS EXPECTED
WITH DAYTIME READINGS MOSTLY IN THE UPPER 80S TO MIDDLE 90S.
DAYTIME HEAT INDICIES MAY REACH 95 TO 100 SEVERAL DAYS.
500H GFS 5 DAY ANOMOLIES SHOW HEIGHTS 50-70 METERS ABOVE NORMAL
THROUGH THE END OF AUGUST...WITH MORE ZONAL FLOW SETTLING OVER
NORTHERN CONUS FOR START OF SEPT.
STILL A POTENTIAL FOR SEVERAL MID-LEVEL SHORT WAVES BREAKING THROUGH
CAPPING INVERSION OVER NORTHERN/CENTRAL WI...WITH CONVECTION
CARRYING SWD INTO PORTIONS OF SRN WI FROM SAT NIGHT INTO TUE. MOST
OF THE PERIOD WILL REMAIN DRY AND WARM HOWEVER.
&&
.AVIATION /00Z TAFS/...THUNDERSTORMS ARE LIKELY ALONG A COLD FRONT
MOVING SOUTHEAST ACROSS CENTRAL AND SOUTHERN WI THIS EVENING. SOME
IFR CONDITIONS IN STORMS. STORMS WILL BE MORE WIDESPREAD EARLY THIS
EVENING AND THEN BECOME MORE SCATTERED LATER IN THE EVENING. SEVERE
THUNDERSTORMS POSSIBLE NORTH OF A LINE FROM PLATTEVILLE TO MADISON
TO WEST BEND. DAMAGING WINDS AND SMALL HAIL ARE THE THREATS. SEVERE
POTENTIAL DIMINISHES AFTER 06Z AND PRECIP CHANCES DIMINISH SHORTLY
THEREAFTER AS WELL.
THERE COULD BE A PERIOD OF MVFR CIGS AND VSBYS JUST BEHIND FRONT
OVERNIGHT. DRIER AIR WITH WINDS OUT OF THE NORTHEAST WILL SETTLE
INTO SOUTHERN WI BY EARLY THU AFTERNOON.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
.CONFIDENCE...
TONIGHT AND THURSDAY...MEDIUM TO HIGH.
THURSDAY NIGHT THROUGH SATURDAY...HIGH.
SATURDAY NIGHT THROUGH WEDNESDAY...MEDIUM.
$$
VERY SHORT TERM/AVIATION...MRC
SHORT TERM/LONG TERM...MBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
323 PM CDT WED AUG 21 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 323 PM CDT WED AUG 21 2013
MAIN FOCUS WILL BE ON THE FRONTAL PASSAGE TONIGHT AND THE
ASSOCIATED RAIN CHANCES.
COLD FRONT EXTENDS FROM NORTHERN WISCONSIN INTO NORTHEAST NEBRASKA
AT MID AFTERNOON. REGIONAL RADARS SHOW CONVECTIVE ACTIVITY ALONG
THE FRONT FROM NORTHERN WISCONSIN ACROSS MINNESOTA.
WATER VAPOR SATELLITE SHOWS THE MAIN SHORT WAVE TROUGH IS ALONG
THE CANADIAN BORDER MOVING INTO ONTARIO WITH A SECONDARY WAVE OVER
CENTRAL MINNESOTA. THE BEST PV ADVECTION IN THE 500-300 MB LAYER
WILL STAY TO THE NORTH OF THE AREA TONIGHT BUT THE EXPECTATION IS
THAT THE WAVE OVER MINNESOTA WILL PROVIDE JUST ENOUGH FORCING TO
HELP MAINTAIN THE CONVECTION ALONG THE FRONT AS IT COMES THROUGH.
ML CAPES AHEAD OF THE FRONT CURRENTLY ARE AROUND 3000 J/KG AND
WHILE THESE WILL DECREASE THROUGH THE EVENING WITH THE LOSS OF
HEATING...THE 21.18Z NAM INDICATES THESE WILL STAY AT OR ABOVE
1500 J/KG THROUGH THE EVENING AHEAD OF THE FRONT. THE BEST 0-6KM
SHEAR WILL REMAIN NORTH OF THE AREA CLOSER TO THE MAIN SHORT WAVE
TROUGH. HOWEVER...THE 0-3KM SHEAR WILL BE AROUND 30 KNOTS AND WILL
BE MORE THAN SUFFICIENT TO SUPPORT SOME SEVERE STORMS THROUGH THE
EVENING. LARGE HAIL AND DAMAGING WINDS STILL LOOK TO BE THE MAIN
THREATS. WILL BE INTERESTING TO SEE HOW THE CURRENT ACTIVITY
SOUTH OF THE TWIN CITIES EVOLVES THROUGH THE REMAINDER OF THE
AFTERNOON. THE 21.18Z RAP BUFKIT SOUNDINGS SUGGEST THE CAP IN
PLACE BETWEEN 750 AND 800 MB AT KRST WILL HOLD TIGHT UNTIL THE
FRONT MOVES THROUGH. IF THIS HAPPENS...THE ACTIVITY TO THE WEST
SHOULD DIMINISH AS IT MOVES IN AND THIS IS WHAT SEVERAL OF THE
SHORT RANGE MESO MODELS SUGGESTS. BASED ON THIS...HAVE TRIMMED
BACK THE RAIN CHANCES HEADING THROUGH THE EVENING ACROSS THE
WESTERN SECTIONS OF THE FORECAST AREA. FARTHER EAST...THE CAP IS
WEAKER AND IS EXPECTED TO ERODE AS THE FRONT MOVES IN...SO HAVE
MAINTAINED THE 60 TO 80 PERCENT CHANCES EAST OF THE MISSISSIPPI RIVER.
ALL THE MODELS ALSO SUGGEST THE FRONT AND CONVECTION WILL MOVE
THROUGH PRETTY QUICK THIS EVENING TO THE POINT THAT MOST IF NOT
ALL OF THE FORECAST AREA SHOULD BE DRY BY 06Z. THUS SPED UP THE
FORECAST TO REFLECT THIS FASTER TIMING WITH JUST SOME 20 TO 40
PERCENT RAIN CHANCES ACROSS THE SOUTH FOR AFTER MIDNIGHT. HAVE
HELD ON TO SOME SMALL RAIN CHANCES ACROSS THE SOUTH FOR THURSDAY
MORNING. ALL THE MODELS INDICATE A CONVECTIVE COMPLEX WILL DEVELOP
ACROSS NEBRASKA THIS EVENING AND THEN MOVE EAST ALONG THE FRONT
TOWARD THE AREA OVERNIGHT WITH SOME SUGGESTIONS THAT THE NORTHERN
PART OF THE COMPLEX COULD SLIDE ACROSS THE SOUTHERN PARTS OF THE
AREA. OTHERWISE FOR THURSDAY...HIGH PRESSURE WILL MOVE IN FROM THE
NORTH WITH MUCH DRIER AIR SPREADING IN. NAM BUFKIT SOUNDING ACROSS
THE NORTHERN SECTIONS SHOW GOOD SUBSIDENCE OCCURRING AND WITH LOTS
OF DRY ALOFT TO MIX DOWN...DEW POINTS ARE EXPECTED TO DROP INTO
THE 40S FOR THE AFTERNOON. THIS HIGH WILL REMAIN THE DOMINANT
FEATURE FOR THE REMAINDER OF THE SHORT TERM HELPING TO KEEP
TEMPERATURES CLOSER TO NORMAL THROUGH FRIDAY WITH HIGHS IN THE
UPPER 70S TO LOWER 80S.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED AUG 21 2013
CONSIDERABLE UNCERTAINTY IN THE EXTENDED IN REGARDS TO THE RAIN
CHANCES. THE UPPER LEVEL RIDGE WILL BE ANCHORED OVER THE CENTRAL
PART OF THE COUNTRY WITH ALL THE MODELS SHOWING SHORT WAVE TROUGHS
EXPECTED TO RIDE UP THE BACK SIDE AND OVER THE TOP OF THE RIDGE.
AT THE SURFACE...THE EXPECTATION IS THAT A WEAK SURFACE BOUNDARY
WILL APPROACH FROM THE WEST SATURDAY BUT STALL OUT AND BECOME
NEARLY STATIONARY BEFORE IT REACHES THE AREA. IT SHOULD THEN
WAFFLE NORTH/SOUTH AS SHORT WAVE TROUGHS MOVE AROUND THE RIDGE AND
CAUSE ROUNDS OF CONVECTION TO FORM. THE UNCERTAINTY COMES IN WHERE
THESE COMPLEXES WILL BE AND WHETHER THEY WILL IMPACT THE NORTHERN
PARTS OF THE FORECAST AREA OR NOT. AFTER THE INITIAL SHORT WAVE
TROUGH GOES BY SATURDAY WILL GENERALLY LIMIT THE RAIN CHANCES TO
THE I94 CORRIDOR FOR THE REMAINDER OF THE EXTENDED PERIOD AS THIS
AREA WILL BE CLOSEST TO THE FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1150 AM CDT WED AUG 21 2013
A COLD FRONT STRETCHING FROM WESTERN LAKE SUPERIOR THROUGH
KMSP/KFSD LATE THIS MORNING WILL CONTINUE TO TRACK SOUTHEAST
THROUGH THIS AFTERNOON. SHOWERS AND STORMS ARE EXPECTED TO FORM
ALONG THIS FRONT WITH THE HIGHEST LIKELIHOOD EAST OF THE
MISSISSIPPI RIVER. EXPECTING TSRA IN THE VICINITY OF KRST/KLSE
AERODROMES WITH PERHAPS A BRIEF REDUCTION INTO IFR BETWEEN 21-24Z
TIME FRAME. THE FRONT AND ASSOCIATED STORMS ARE THEN EXPECTED TO
SLIP SOUTHEAST OF THE AREA AFTER MIDNIGHT. LINGERING MID-
LEVEL/VFR CLOUDS WILL LIKELY BE SEEN DURING THE OVERNIGHT HOURS
INTO THURSDAY MORNING AS THE FRONT HANGS UP ACROSS NORTHERN IL
THROUGH CENTRAL IA. OTHERWISE...HIGH PRESSURE BUILDING IN ON
THURSDAY SHOULD KEEP RAIN CHANCES SOUTH OF THE AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...DAS
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG COLD
FRONT MOVING OVER THE FAR WESTERN UPPER PENINSULA AND NORTHWEST
WISCONSIN EARLY THIS AFTERNOON. MOISTURE CONVERGENCE ALONG THE
FRONT LOOKS GOOD...AND ML CAPES ARE BUILDING BETWEEN 2K-3K J/KG
AHEAD OF THE BOUNDARY. RETURNS ON RADAR ARE PICKING UP ALONG THE
FRONT AS INHIBITION ERODES BELOW 50 J/KG. WITH 0-6KM BULK SHEAR
VALUES AROUND 25-30 KTS...CONDITIONS REMAIN CONDUCIVE FOR SEVERE
THUNDERSTORMS TO DEVELOP LATER THIS AFTERNOON. THE NSSL WRF SEEMS
TO BE DOING THE BEST OUT OF THE MESOMODELS...AND SHOWS CONVECTION
RAMPING UP IN A LINEAR FASHION BETWEEN 19-21Z. BY THE END OF THIS
PERIOD...CONVECTION WILL BE MOVING INTO N-C WISCONSIN BEFORE
PROGRESSING INTO CENTRAL AND NORTHEAST WISCONSIN BY 00Z. STILL
LOOKING AT MULTI-CELLS AND SMALL BOWING SEGMENTS AS THE STORM
MODE...WHICH WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND
LARGE HAIL. ANOTHER WRINKLE IS THE WEAK LITTLE SHORTWAVE OVER
SOUTHERN MINNESOTA. THE RUC TAKES THIS FEATURE INTO SW WISCONSIN
THIS EVENING...AND NOT SURE HOW MUCH THIS WILL IMPACT THUNDERSTORMS
ALONG THE FRONT. SEVERE WEATHER IS THE OBVIOUS FORECAST CONCERN.
TONIGHT...SHORTWAVE TROUGH MOVING ACROSS ONTARIO WILL PUSH A COLD
FRONT SOUTHEAST ACROSS CENTRAL AND NORTHEAST WISCONSIN THIS
EVENING. SOUTH SOUTHWEST FLOW AHEAD OF THE FRONT WITH PWATS UPWARDS
OF 1.75 INCHES WILL PREVENT TEMPS FROM FALLING TOO FAST THIS
EVENING...WHICH SHOULD PROLONG THE SEVERE THREAT UNTIL THE FRONT
CLEARS THE AREA. BECAUSE INSTABILITY WILL BE DECREASING...THE LARGE
HAIL THREAT WILL DIMINISH AS WELL THROUGH THE EVENING. BUT THINK
THERE IS ENOUGH POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS TO REACH
EAST-CENTRAL AND NORTHEAST WISCONSIN. PRECIP WILL BE EXITING
EAST-CENTRAL EARLY OVERNIGHT AS MUCH DRIER AIR WILL FILTER SOUTH
BEHIND THE FRONT. TEMPS WILL BE A LITTLE SLOWER TO COOL OFF...BUT
LOWS SHOULD STILL FALL INTO THE LOWER OR MIDDLE 50S NORTH...BUT HANG
IN THE MID 60S SOUTH.
THURSDAY...THE COLD FRONT WILL MOVE TO THE SOUTHERN GREAT LAKES BY
THE START OF THE PERIOD WHILE CANADIAN HIGH PRESSURE WILL BE
BUILDING SOUTHEAST FROM THE NORTHERN PLAINS. THIS AIRMASS WILL BE
COOLER AND SIGNIFICANTLY LESS HUMID THAN THE ONE IT REPLACED. UNDER
PLENTY OF SUN...HIGH TEMPS WILL REACH FROM THE MID 70S NORTH TO THE
LOW 80S SOUTH.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 206 PM CDT WED AUG 21 2013
PATTERN TO BECOME RATHER AMPLIFIED AS MOVE THROUGH THIS PERIOD AS
UPPER RIDGE BUILDS OVER THE CENTRAL US...INTO WESTERN LAKES.
MODELS HAVE GOOD CONTINUITY IN BIG PICTURE...BUT TEND TO DIFFER IN
CONVECTIVE DETAILS SUN ONWARD. MAIN ISSUE WILL BE HEAT LATER
PERIODS. ILL-DEFINED WARM FRONT EXPECTED TO LIFT NORTH
INTO/THROUGH STATE SUN. 850 MB TEMPS EXPECTED TO WARM SAT ONWARD
HITTING 20C EARLY IN WORK WEEK. IF MODELS SOUNDINGS
CORRECT...WOULD MIX UP TO THAT LEVEL YIELDING TEMPS AROUND 90 NEXT
MON THROUGH WED. QUESTION IS EFFECTS OF CLOUDS AND PCPN. LIKELY
TO BE ON EDGE OF CAP WITH CONVECTION NEAR OR OVER REGION. HAVE
TRENDED HIGHER POPS OVER NORTHERN WI WHERE ECMWF LINGERS FRONT.
HAVE USED BEST PERFORMING BLEND FOR TEMPS...BUMPING THEM UP A
DEGREE TO LESSEN CLIMO BIAS.
EARLY PERIODS/THU NIGHT INTO FRI NIGHT/PLEASANT WITH COOLER HIGH
PRESSURE AT THE SURFACE OVER REGION. CLEAR SKIES AND DRY
CONDITIONS TO LEAD TO COOLER NIGHTS AND MILD DAYS. HAVE SLOWED
APPROACH OF PCPN SAT GIVEN MODEL TRENDS.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT WED AUG 21 2013
MAINLY VFR WEATHER EXPECTED TODAY UNTIL A COLD FRONT
ARRIVES IN NORTH CENTRAL WISCONSIN DURING THE AFTERNOON HOURS AND
MOVES ACROSS THE EASTERN PART OF THE STATE BY EARLY EVENING. IT WILL
BE ACCOMPANIED BY SHOWERS AND THUNDERSTORMS WITH GUSTY WINDS AND
BRIEF IFR CEILINGS AND VISIBILITIES. THE FRONT WILL EXIT TONIGHT
WITH CLEARING EXPECTED BY THURSDAY MORNING. GOOD FLYING WEATHER IS
EXPECTED THURSDAY THROUGH FRIDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1210 PM CDT WED AUG 21 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.UPDATE...
ISSUED AT 1038 AM CDT WED AUG 21 2013
NO BIG CHANGES TO THE FORECAST FOR THE REST OF TODAY. A STRONG
COLD FRONT EXTENDS FROM WESTERN LAKE SUPERIOR TO CENTRAL
MINNESOTA. THE FRONT HAS BEEN MOSTLY QUIET SO FAR THIS MORNING
OUTSIDE OF A FEW BLIPS ON THE RADAR. SKIES ARE MOSTLY CLEAR TO
PARTLY CLOUDY AHEAD OF THE FRONT...WHICH SHOULD ALLOW FOR GOOD
HEATING. TEMPS ARE LAGGING BEHIND THE PREVIOUS FORECAST SO DROPPED
THEM A DEGREE. LOOKING AT THE MODELS THIS MORNING...THE NAM AND SREF HAVE
SPED UP THE TIMING OF THE FRONT...HAVING IT REACH NORTHEAST
WISCONSIN AND THE FOX VALLEY LATE IN THE AFTERNOON. THE RUC IS NOT
TOO DIFFERENT...SO THIS MAY BE POSSIBLE. REGARDLESS...ML CAPES
WILL REACH 3K J/KG IF A PARCEL CAN REACH 88/68. WITH TEMPS LAGGING
A LITTLE BIT...2K-3K J/KG SEEMS REASONABLE. SUFFICIENT 0-6KM BULK
SHEAR OF 25-30 KTS WILL BE GOOD ENOUGH TO PRODUCE STORMS
CONTAINING LARGE HAIL AND DAMAGING WINDS. TRIED TO FOLLOW THE NSSL
WRF FOR THE CONVECTIVE EVOLUTION FOR THIS FORECAST. CONVECTIVE
INITIATION LOOKS TO OCCUR AROUND THE 19-20Z TIME PERIOD OVER
NORTHWEST WISCONSIN. STORMS ARE THEN PROJECTED TO REACH THE FOX
VALLEY EARLY THIS EVENING.
&&
.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 407 AM CDT WED AUG 21 2013
A SMALL AREA OF SHOWERS AND THUNDERSTORMS WILL MOVE
ACROSS PARTS OF THE FOX VALLEY EARLY THIS MORNING IN AN AREA OF
MID LEVEL WARM ADVECTION AND CONVERGENCE. IT SHOULD EXIT THE AREA
BY SUNRISE OR SHORTLY THEREAFTER. VERY WARM AND HUMID WEATHER
EXPECTED TODAY BEFORE THE ARRIVAL OF A COLD FRONT DURING THE LATE
AFTERNOON AND EVENING HOURS. HEAT INDICES WILL RISE INTO THE 90S
WITH TEMPERATURES IN THE MIDDLE 80S TO LOW 90S.
THE POTENTIAL FOR SEVERE THUNDERSTORMS CERTAINLY EXISTS THIS
AFTERNOON AND EVENING. SIGNIFICANT INSTABILITY...UPPER
DIFFLUENCE...LOW LEVEL WARM ADVECTION AND MOISTURE CONVERGENCE
SHOULD COMBINE TO CREATE AN ENVIRONMENT FAVORABLE FOR STRONG TO
SEVERE STORMS. MID LEVEL WINDS ARE NOT TOO IMPRESSIVE AND
TEMPERATURES ALOFT ARE NOT VERY COLD...BUT INSTABILITY WILL BE
SUBSTANTIAL AND SHOULD HELP PRODUCE STORMS WITH STRONG UPDRAFTS.
THE DAY ONE SEVERE THUNDERSTORM OUTLOOK LOOKS VERY REASONABLE AND
FITS WELL WITH CURRENT THINKING AND HISTORICAL ANALOGS FOR SIMILAR
EVENTS.
THE COLD FRONT WILL EXIT TONIGHT AND PRECIPITATION WILL END FROM
WEST TO EAST. THE AIR BEHIND THE FRONT IS MORE DRY THAN COLD SO
EXPECT LOWS TONIGHT TO BE NEAR OR JUST ABOVE NORMAL BUT WITH MUCH
MORE COMFORTABLE DEW POINTS. TOMORROW SHOULD BE SUNNY AND
SEASONABLE TEMPERATURES AND LOW HUMIDITY.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 407 AM CDT WED AUG 21 2013
SOMEWHAT OF AN AMPLIFIED FLOW TO TAKE SHAPE INTO EARLY NEXT WEEK
WITH UPR TROFS ALONG THE WEST COAST/NE CONUS AND A BROAD UPR RDG
OVER THE CNTRL/E-CNTRL CONUS. THIS RDG TO INTENSIFY BY THE WEEKEND
WITH BOTH TEMPS AND DEW POINTS GOING ABOVE CLIMATOLOGICAL NORMS
FOR LATE AUGUST. MAIN FCST ISSUE REMAINS LOCATION OF CONVECTIVE
COMPLEXES RIDING THE RIM OF THIS UPR RDG AND WHETHER ANY BACKDOOR
CDFNTS MAY REACH NE WI.
HI PRES IS EXPECTED TO STRETCH FROM ERN ONTARIO SWWD THRU THE
GREAT LAKES BY THU NGT SETTING UP MOSTLY CLEAR SKIES...LIGHT WINDS
AND A DRY ATMOSPHERE WITH DEW POINTS IN THE 40S TO LWR 50S. NEAR
IDEAL RADIATIONAL CONDITIONS WL ALLOW FOR TEMPS TO QUICKLY FALL
THU NGT WITH A FEW LOCATIONS OVER THE NORTH FLIRTING WITH THE 40
DEG MARK. MAY NEED TO TWEAK VALUES DOWN A COUPLE OF DEGS FROM THE
PREVIOUS FCST.
PLEASANT CONDITIONS WL CONT INTO FRI AS THE CENTER OF THIS SFC RDG
SLOWLY SLIDES TO THE EAST...BUT REMAINS THE DOMINANT FEATURE FOR
NE WI. EVEN WITH A COOL START TO THE DAY...MAINLY SUNNY SKIES
COUPLED WITH A DRY AIR MASS IN PLACE...WL STILL ALLOW TEMPS TO
MAKE A PRETTY GOOD JUMP DURING THE DAY. LOOK FOR MAX TEMPS TO
APPROACH THE 80 DEG MARK FOR INLAND AREAS...WHILE LAKESHORE AREAS
TO ONLY REACH THE MID 70S AS THE LAKEBREEZE DEVELOPS AND MOVES
INLAND.
AS THE SFC RDG HEADS INTO THE ERN GREAT LAKES FRI NGT...RETURN
FLOW BEGINS OVER WI AS WINDS JUST ABOVE THE SFC TURN S-SW AND
INCREASE TO AROUND 20 KTS. PRIMARY LOW-LEVEL JET AIMED OVER THE
NRN PLAINS/UPR MS VALLEY WHERE ELEVATED CONVECTION IS EXPECTED.
ANOTHER QUIET NGT FOR THE FCST AREA WITH MIN TEMPS NOT AS COLD AND
THE AIR MASS NOT AS DRY AS THU NGT. LOOK FOR MIN TEMPS TO BE IN
THE LWR 50S NORTH/MID 50S ELSEWHERE.
THE SPRAWLING UPR RDG OVER THE CNTRL CONUS IS PROGGED TO EXPAND
NWD TOWARD THE UPR MS VALLEY/GREAT LAKES REGIONS STARTING THIS
WEEKEND. AS THIS OCCURS...AN INCREASE IN BOTH TEMPS AND DEW POINTS
WL TAKE PLACE AS WELL AS THE POTENTIAL FOR A WRMFNT TO LIFT NORTH
TOWARD/INTO WI. IN ADDITION...A PIECE OF ENERGY IS FCST TO RIDE
THE FRINGE OF THIS UPR RDG ON SAT. WHILE BETTER INSTABILITY AND
DEEPER MOISTUREWL BE TO OUR WEST...CANNOT RULE OUT A CONVECTIVE
COMPLEX MOVING INTO PARTS OF NE WI BY SAT AFTERNOON. MAY NEED TO
RAISE POPS A BIT AS A RESULT. ONCE THE WRMFNT LIFTS TO OUR NORTH
AND THE IMPULSE (ENERGY) SHIFTS TO OUR EAST SAT NGT...PCPN CHCS
LOOK MINIMAL HEADED INTO SUNDAY AS THE UPR RDG REMAINS IN PLACE
AND THE ATMOSPHERE BECOMES CAPPED. 8H TEMPS PUSHING +20C COULD
EASILY SEND MAX TEMPS WELL INTO THE 80S WITH DEW POINTS CLIMBING
INTO THE 60S.
STILL HAVE QUESTIONS AS TO HOW FAR NORTH THIS WRMFNT CAN GET
SUNDAY NGT INTO MON AS THIS FEATURE WL BE THE PRIMARY FOCUSING
MECHANISM FOR ADDITIONAL SHWRS/TSTMS. SOME MDLS KEEP THIS FNT TO
OUR NORTH...THUS ADVERTISING A DRY FCST. HOWEVER...OTHER MDLS
APPEAR TO SHOW CONVECTION HELPING TO SHOVE THIS BOUNDARY A BIT
SOUTH AND LEAVE MUCH OF THE FCT AREA VULNERABLE TO MORE PCPN. TOO
MUCH UNCERTAINTY HERE...THUS HAVE FAVORED THE CONSENUS SOLUTION
WHICH KEEPS CHC POPS IN THE FCST ALONG WITH VERY WARM/MUGGY
CONDITIONS. UNCERTAINTY CARRIES OVER INTO TUE AS THE LONG-TERM
MDLS DIFFER ON HOW LONG THE UPR RDG WL BE ABLE TO MAINTAIN ITSELF.
THERE IS POTENTIAL FOR ANOTHER COMPLEX TO DEVELOP ON THE EDGE OF
THIS UPR RDG...THUS A CONTINUED CHC POP WL ALSO BE NEEDED FOR TUE.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT WED AUG 21 2013
MAINLY VFR WEATHER EXPECTED TODAY UNTIL A COLD FRONT
ARRIVES IN NORTH CENTRAL WISCONSIN DURING THE AFTERNOON HOURS AND
MOVES ACROSS THE EASTERN PART OF THE STATE BY EARLY EVENING. IT WILL
BE ACCOMPANIED BY SHOWERS AND THUNDERSTORMS WITH GUSTY WINDS AND
BRIEF IFR CEILINGS AND VISIBILITIES. THE FRONT WILL EXIT TONIGHT
WITH CLEARING EXPECTED BY THURSDAY MORNING. GOOD FLYING WEATHER IS
EXPECTED THURSDAY THROUGH FRIDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........MPC
SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1049 AM CDT WED AUG 21 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 1038 AM CDT WED AUG 21 2013
NO BIG CHANGES TO THE FORECAST FOR THE REST OF TODAY. A STRONG
COLD FRONT EXTENDS FROM WESTERN LAKE SUPERIOR TO CENTRAL
MINNESOTA. THE FRONT HAS BEEN MOSTLY QUIET SO FAR THIS MORNING
OUTSIDE OF A FEW BLIPS ON THE RADAR. SKIES ARE MOSTLY CLEAR TO
PARTLY CLOUDY AHEAD OF THE FRONT...WHICH SHOULD ALLOW FOR GOOD
HEATING. TEMPS ARE LAGGING BEHIND THE PREVIOUS FORECAST SO DROPPED
THEM A DEGREE. LOOKING AT THE MODELS THIS MORNING...THE NAM AND SREF HAVE
SPED UP THE TIMING OF THE FRONT...HAVING IT REACH NORTHEAST
WISCONSIN AND THE FOX VALLEY LATE IN THE AFTERNOON. THE RUC IS NOT
TOO DIFFERENT...SO THIS MAY BE POSSIBLE. REGARDLESS...ML CAPES
WILL REACH 3K J/KG IF A PARCEL CAN REACH 88/68. WITH TEMPS LAGGING
A LITTLE BIT...2K-3K J/KG SEEMS REASONABLE. SUFFICIENT 0-6KM BULK
SHEAR OF 25-30 KTS WILL BE GOOD ENOUGH TO PRODUCE STORMS
CONTAINING LARGE HAIL AND DAMAGING WINDS. TRIED TO FOLLOW THE NSSL
WRF FOR THE CONVECTIVE EVOLUTION FOR THIS FORECAST. CONVECTIVE
INITIATION LOOKS TO OCCUR AROUND THE 19-20Z TIME PERIOD OVER
NORTHWEST WISCONSIN. STORMS ARE THEN PROJECTED TO REACH THE FOX
VALLEY EARLY THIS EVENING.
&&
.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 407 AM CDT WED AUG 21 2013
A SMALL AREA OF SHOWERS AND THUNDERSTORMS WILL MOVE
ACROSS PARTS OF THE FOX VALLEY EARLY THIS MORNING IN AN AREA OF
MID LEVEL WARM ADVECTION AND CONVERGENCE. IT SHOULD EXIT THE AREA
BY SUNRISE OR SHORTLY THEREAFTER. VERY WARM AND HUMID WEATHER
EXPECTED TODAY BEFORE THE ARRIVAL OF A COLD FRONT DURING THE LATE
AFTERNOON AND EVENING HOURS. HEAT INDICES WILL RISE INTO THE 90S
WITH TEMPERATURES IN THE MIDDLE 80S TO LOW 90S.
THE POTENTIAL FOR SEVERE THUNDERSTORMS CERTAINLY EXISTS THIS
AFTERNOON AND EVENING. SIGNIFICANT INSTABILITY...UPPER
DIFFLUENCE...LOW LEVEL WARM ADVECTION AND MOISTURE CONVERGENCE
SHOULD COMBINE TO CREATE AN ENVIRONMENT FAVORABLE FOR STRONG TO
SEVERE STORMS. MID LEVEL WINDS ARE NOT TOO IMPRESSIVE AND
TEMPERATURES ALOFT ARE NOT VERY COLD...BUT INSTABILITY WILL BE
SUBSTANTIAL AND SHOULD HELP PRODUCE STORMS WITH STRONG UPDRAFTS.
THE DAY ONE SEVERE THUNDERSTORM OUTLOOK LOOKS VERY REASONABLE AND
FITS WELL WITH CURRENT THINKING AND HISTORICAL ANALOGS FOR SIMILAR
EVENTS.
THE COLD FRONT WILL EXIT TONIGHT AND PRECIPITATION WILL END FROM
WEST TO EAST. THE AIR BEHIND THE FRONT IS MORE DRY THAN COLD SO
EXPECT LOWS TONIGHT TO BE NEAR OR JUST ABOVE NORMAL BUT WITH MUCH
MORE COMFORTABLE DEW POINTS. TOMORROW SHOULD BE SUNNY AND
SEASONABLE TEMPERATURES AND LOW HUMIDITY.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 407 AM CDT WED AUG 21 2013
SOMEWHAT OF AN AMPLIFIED FLOW TO TAKE SHAPE INTO EARLY NEXT WEEK
WITH UPR TROFS ALONG THE WEST COAST/NE CONUS AND A BROAD UPR RDG
OVER THE CNTRL/E-CNTRL CONUS. THIS RDG TO INTENSIFY BY THE WEEKEND
WITH BOTH TEMPS AND DEW POINTS GOING ABOVE CLIMATOLOGICAL NORMS
FOR LATE AUGUST. MAIN FCST ISSUE REMAINS LOCATION OF CONVECTIVE
COMPLEXES RIDING THE RIM OF THIS UPR RDG AND WHETHER ANY BACKDOOR
CDFNTS MAY REACH NE WI.
HI PRES IS EXPECTED TO STRETCH FROM ERN ONTARIO SWWD THRU THE
GREAT LAKES BY THU NGT SETTING UP MOSTLY CLEAR SKIES...LIGHT WINDS
AND A DRY ATMOSPHERE WITH DEW POINTS IN THE 40S TO LWR 50S. NEAR
IDEAL RADIATIONAL CONDITIONS WL ALLOW FOR TEMPS TO QUICKLY FALL
THU NGT WITH A FEW LOCATIONS OVER THE NORTH FLIRTING WITH THE 40
DEG MARK. MAY NEED TO TWEAK VALUES DOWN A COUPLE OF DEGS FROM THE
PREVIOUS FCST.
PLEASANT CONDITIONS WL CONT INTO FRI AS THE CENTER OF THIS SFC RDG
SLOWLY SLIDES TO THE EAST...BUT REMAINS THE DOMINANT FEATURE FOR
NE WI. EVEN WITH A COOL START TO THE DAY...MAINLY SUNNY SKIES
COUPLED WITH A DRY AIR MASS IN PLACE...WL STILL ALLOW TEMPS TO
MAKE A PRETTY GOOD JUMP DURING THE DAY. LOOK FOR MAX TEMPS TO
APPROACH THE 80 DEG MARK FOR INLAND AREAS...WHILE LAKESHORE AREAS
TO ONLY REACH THE MID 70S AS THE LAKEBREEZE DEVELOPS AND MOVES
INLAND.
AS THE SFC RDG HEADS INTO THE ERN GREAT LAKES FRI NGT...RETURN
FLOW BEGINS OVER WI AS WINDS JUST ABOVE THE SFC TURN S-SW AND
INCREASE TO AROUND 20 KTS. PRIMARY LOW-LEVEL JET AIMED OVER THE
NRN PLAINS/UPR MS VALLEY WHERE ELEVATED CONVECTION IS EXPECTED.
ANOTHER QUIET NGT FOR THE FCST AREA WITH MIN TEMPS NOT AS COLD AND
THE AIR MASS NOT AS DRY AS THU NGT. LOOK FOR MIN TEMPS TO BE IN
THE LWR 50S NORTH/MID 50S ELSEWHERE.
THE SPRAWLING UPR RDG OVER THE CNTRL CONUS IS PROGGED TO EXPAND
NWD TOWARD THE UPR MS VALLEY/GREAT LAKES REGIONS STARTING THIS
WEEKEND. AS THIS OCCURS...AN INCREASE IN BOTH TEMPS AND DEW POINTS
WL TAKE PLACE AS WELL AS THE POTENTIAL FOR A WRMFNT TO LIFT NORTH
TOWARD/INTO WI. IN ADDITION...A PIECE OF ENERGY IS FCST TO RIDE
THE FRINGE OF THIS UPR RDG ON SAT. WHILE BETTER INSTABILITY AND
DEEPER MOISTUREWL BE TO OUR WEST...CANNOT RULE OUT A CONVECTIVE
COMPLEX MOVING INTO PARTS OF NE WI BY SAT AFTERNOON. MAY NEED TO
RAISE POPS A BIT AS A RESULT. ONCE THE WRMFNT LIFTS TO OUR NORTH
AND THE IMPULSE (ENERGY) SHIFTS TO OUR EAST SAT NGT...PCPN CHCS
LOOK MINIMAL HEADED INTO SUNDAY AS THE UPR RDG REMAINS IN PLACE
AND THE ATMOSPHERE BECOMES CAPPED. 8H TEMPS PUSHING +20C COULD
EASILY SEND MAX TEMPS WELL INTO THE 80S WITH DEW POINTS CLIMBING
INTO THE 60S.
STILL HAVE QUESTIONS AS TO HOW FAR NORTH THIS WRMFNT CAN GET
SUNDAY NGT INTO MON AS THIS FEATURE WL BE THE PRIMARY FOCUSING
MECHANISM FOR ADDITIONAL SHWRS/TSTMS. SOME MDLS KEEP THIS FNT TO
OUR NORTH...THUS ADVERTISING A DRY FCST. HOWEVER...OTHER MDLS
APPEAR TO SHOW CONVECTION HELPING TO SHOVE THIS BOUNDARY A BIT
SOUTH AND LEAVE MUCH OF THE FCT AREA VULNERABLE TO MORE PCPN. TOO
MUCH UNCERTAINTY HERE...THUS HAVE FAVORED THE CONSENUS SOLUTION
WHICH KEEPS CHC POPS IN THE FCST ALONG WITH VERY WARM/MUGGY
CONDITIONS. UNCERTAINTY CARRIES OVER INTO TUE AS THE LONG-TERM
MDLS DIFFER ON HOW LONG THE UPR RDG WL BE ABLE TO MAINTAIN ITSELF.
THERE IS POTENTIAL FOR ANOTHER COMPLEX TO DEVELOP ON THE EDGE OF
THIS UPR RDG...THUS A CONTINUED CHC POP WL ALSO BE NEEDED FOR TUE.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 639 AM CDT WED AUG 21 2013
MAINLY VFR WEATHER EXPECTED TODAY UNTIL A COLD FRONT
ARRIVES IN CENTRAL WISCONSIN DURING THE AFTERNOON HOURS AND MOVES
ACROSS THE EASTERN PART OF THE STATE BY EARLY EVENING. IT WILL BE
ACCOMPANIED BY SHOWERS AND THUNDERSTORMS WITH GUSTY WINDS AND
BRIEF IFR CEILINGS AND VISIBILITIES. THE FRONT WILL EXIT TONIGHT
WITH CLEARING EXPECTED BY THURSDAY MORNING. GOOD FLYING WEATHER IS
EXPECTED THURSDAY THROUGH FRIDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........MPC
SHORT TERM.....RDM
LONG TERM......KALLAS
AVIATION.......RDM
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
246 AM MST FRI AUG 23 2013
.SYNOPSIS...
A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE
IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO
THIS WEEKEND. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH
EARLY NEXT WEEK.
&&
.DISCUSSION...
EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST
AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD
OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA
OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE
STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO
THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL
WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS
MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS
SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL
MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY
IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT
EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING.
TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF
THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS
WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL
AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF
EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL
AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM
THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER.
NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA
PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED
WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN
THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED.
INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS
STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF
PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL
MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG.
LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL.
THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE
REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE
3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE
IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12
G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2
INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE
ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON
SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE
SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW
THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A
PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY
SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE
REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT
RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE
FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING.
UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I
THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE
MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY
WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS
GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND
EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT
WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER
GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY
AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS
ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE
LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
THICKER MID/HIGH CLOUDS WILL PREVAIL THROUGH FRIDAY MORNING...WITH
PRIMARY AVIATION IMPACT BEING POTENTIAL WIND SHIFTS AND THE OUTSIDE
CHANCE OF SHRA/TSRA REACHING TERMINALS THROUGH FRIDAY MORNING.
OUTFLOW BOUNDARIES HAVE LARGELY DISSIPATED THIS EVENING...THOUGH AN
EVENTUAL EASTERLY DRAINAGE WIND SHOULD DEVELOP BY THE OVERNIGHT
HOURS. RENEWED SHRA/TSRA MAY BE POSSIBLE FRIDAY AFTERNOON THOUGH
CONFIDENCE IS TOO LOW TO INCLUDE ANY MENTION AT THIS TIME.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
OUTFLOW AND VCTS MAY CONTINUE TO AFFECT APPROACHES INTO KBLH BEFORE
MIDNIGHT...WITH ONLY SHIFTING WINDS AND RESIDUAL DUST AFFECTING
KIPL. A MORE GENERAL CALM IN WEATHER CONDITIONS SHOULD BE EXPECTED
THROUGH FRIDAY MORNING...THOUGH SFC WINDS MAY CONTINUE TO REMAIN
RATHER VARIABLE THROUGH THE PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
MODELS CONTINUE TO DEPICT MOISTURE FROM TROPICAL ORIGINS MAKING ITS
WAY INTO THE DESERT SOUTHWEST THIS WEEKEND. THUS HUMIDITIES WILL
INCREASE SUBSTANTIALLY ALONG WITH PRECIPITATION CHANCES.
TEMPERATURES WILL DECREASE...TO WELL BELOW NORMAL BY SUNDAY...BEFORE
INCREASING TO NEAR NORMAL BY TUESDAY AND WEDNESDAY. STRONGER
SOUTHERLY WINDS ARE ALSO EXPECTED ON SATURDAY...MAINLY OVER
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...WITH LESS BREEZINESS
THEREAFTER EXCEPT FOR THUNDERSTORM DRIVEN WINDS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...LEINS
AVIATION...MO
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
338 AM MDT FRI AUG 23 2013
.SHORT TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL AS THE UPPER LEVEL
HIGH SHIFTS EASTWARD TODAY. A LOW PRESSURE SYSTEM WILL FORM OVER
SOUTHERN ALBERTA DURING THE DAY AND A LOW PRESSURE TROUGH WILL
EXTEND SOUTHWARD ALONG THE LEE SIDE OF THE ROCKIES AND INTO
COLORADO. THIS WILL PRODUCE SOUTHERLY WINDS OVER EASTERN COLORADO.
DRIER OVER NEW MEXICO WILL BE PULLED NORTHWARD THROUGH THE DAY.
THE LATEST RAP SHOWS THE AIRMASS WILL STAY MOIST TODAY WITH
PRECIPITABLE WATER VALUES OF AN INCH TO 1.25 AND CAPES OF 1000 TO
1500 J/KG. THIS WOULD SUPPORT ANOTHER ROUND OF STRONG THUNDERSTORMS.
THE NAM AND GFS HAS PRECIPITABLE WATER VALUES OF 0.75 TO ONE INCH
WITH CAPES LESS THAN 700 J/KG. WHAT ACTUALLY HAPPENS WILL PROBABLY
BE SOMEWHERE IN BETWEEN THESE SOLUTIONS. WILL HAVE THE HIGHEST POPS
OVER THE MOUNTAINS AND ACROSS THE NORTHERN ZONES. ALL THE MODELS
HAVE SOME DRYING OVER THE SOUTHEAST ZONES AND IT SPREADS NORTH
DURING THE EVENING...THUS WILL HAVE THE LOWEST POPS HERE. EXPECT THE
CONVECTION TO END DURING THE EVENING HOURS AS DRIER AIR MOVES INTO
THE AREA.
TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY. CLEARING SKIES THIS
MORNING AND EARLY AFTERNOON SHOULD ALLOW ENOUGH SUN TO PUSH HIGHS IN
THE UPPER 80S AND PERHAPS LOWER 90S. AS DRIER MOVES INTO THE AREA
TONIGHT...TEMPERATURES WILL FALL INTO THE 50S.
.LONG TERM...MODELS SHOW THE UPPER RIDGE CENTERED OVER CENTRAL
KANSAS SATURDAY MORNING. IT MOVES INTO EASTERN KANSAS BY SUNDAY
NIGHT. THE FLOW ALOFT STAYS SOUTHWESTERLY OVER THE FORECAST AREA
ALL FOUR PERIODS. THE QG VERTICAL VELOCITY FIELD KEEP BENIGN
SYNOPTIC SCALE ENERGY OVER THE CWA THROUGH THE PERIOD. THE
BOUNDARY LAYER FLOW IS PROGGED TO BE PRETTY MUCH NORMAL DIURNAL
PATTERNS THROUGH SUNDAY NIGHT. FOR MOISTURE...MODELS SHOW A FAIR
AMOUNTS LATE DAY SATURDAY AND LATE DAY SUNDAY...BUT IT IS IN THE
MID AND UPPER LEVELS. THE BOUNDARY LAYER DEW POINT VALUES ARE
PROGGED IN THE 40S TO LOWER 50S F FOR THE PLAINS LATE DAY
SATURDAY...AND A TAD HIGHER LATE DAY SUNDAY. PRECIPITABLE WATER
VALUES ARE IN THE 0.65 TO 1.10 INCH RANGE OVER THE PLAINS SATURDAY
THROUGH SUNDAY NIGHT. THE HIGHEST VALUES ARE OUT EAST. THE CAPE IS
PRETTY LOW FOR LATE DAY SATURDAY...WITH THE HIGHEST VALUES OVER
THE FOOTHILLS. THEY GET UP 750 J/KG AT BEST THERE...WITH VALUES
OVER THE PLAINS FROM 100-500 J/KG. THERE IS EVEN LESS CAPE LATE
DAY SUNDAY FOR ALL AREAS. MEASURABLE RAINFALL IS PRETTY SPARSE ON
THE QPF FIELDS. THERE IS SOME LATE DAY SATURDAY OVER THE WESTERN
HALF OF THE CWA...THEN A TAD BIT LESS LATE DAY SUNDAY. FOR
POPS...20-30%S IN THE MOUNTAINS SHOULD DO FOR THE LATE DAYS AND
0-10%S OVER THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE
1-2 C WARMER THAN TODAY`S EXPECTED HIGHS. SUNDAY`S ARE CLOSE TO
SATURDAY`S. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS
KEEP THE UPPER RIDGE CENTERED OVER KANSAS ALL FOUR DAYS. THE
SOUTHWESTERLY FLOW ALOFT STAYS AROUND FOR THE CWA AS WELL...BUT
MOISTURE IS SPARSE. TEMPERATURES LOOK TO STAY A BIT ABOVE SEASONAL
NORMALS.
&&
.AVIATION...SLIGHT CHANCE FOR PATCHY FOG AND LOW CLOUDS THIS
MORNING...NOT ENOUGH OF A CHANCE TO MENTION IN THE TAFS. THERE WILL
BE A CHANCE FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 20-01Z.
HEAVY RAIN AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE
STRONGER STORMS. DRIER AIR WILL MOVE INTO THE AREA TONIGHT AND BRING
CLEARING SKIES. SOUTHERLY WINDS ARE EXPECTED FOR MOST OF THE DAY.
&&
.HYDROLOGY...ANOTHER ROUND OF THUNDERSTORMS WILL FORM OVER THE
HIGHER TERRAIN AND SPREAD EASTWARD. HEAVY RAIN WILL AGAIN BE
POSSIBLE WITH THE STORMS WITH 1 INCH IN 15 TO 20 MINUTES OCCURRING.
FLASHING FLOODING COULD OCCUR IF A STRONG STORM FORMS OVER THE BURN
AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MEIER
LONG TERM....RJK
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
348 AM EDT FRI AUG 23 2013
.SHORT TERM /TODAY THROUGH SATURDAY/...
LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING
FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK
RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER
FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT
LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF
THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR
IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG
WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL
OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK
AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD
CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA
INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM
THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW
BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED.
FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT
FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS
AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM
MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY
DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH
PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN
THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000
J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO
FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW
1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO
ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A
COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG
VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA.
OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH
RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA.
ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE
SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS
ENHANCED DEVELOPMENT DURING THE AFTERNOON.
DEESE
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS
SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER
LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM
CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE
LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED
TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY
EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE
INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N
GA.
PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE
SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND
THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP
AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE
MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED.
GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE
EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW
POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS
ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH
THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE
FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY.
BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY.
TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL
DURING THIS PERIOD.
BDL
&&
.AVIATION...
06Z UPDATE...
MOISTURE PROFILES FROM VARIOUS MODEL PROJECTIONS SHOW BEST FOG
CHANCES ACROSS EXTREME NORTH GA TO INCLUDE RYY AND PDK BUT
REMAINING JUST OUTSIDE THE REMAINING ATL ARE TAF SITES. WILL BE A
CLOSE CALL BUT WILL KEEP IFR OUT FOR NOW AND MONITOR CLOSELY
THROUGH SUNRISE. ADDITIONAL LOW CLOUDS AND VSBY WILL BE POSSIBLE
OVER THE SOUTHERN SECTIONS AS WELL TO INCLUDE MCN AND CSG.
OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS
AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS
POINT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON PRECIP TIMING AND EARLY MORNING VSBYS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 91 73 84 67 / 40 40 40 20
ATLANTA 89 75 86 70 / 40 40 40 20
BLAIRSVILLE 86 67 81 65 / 50 50 50 20
CARTERSVILLE 90 72 87 69 / 30 30 40 20
COLUMBUS 90 77 88 72 / 50 50 50 20
GAINESVILLE 88 73 83 69 / 40 40 40 20
MACON 91 74 87 71 / 50 50 50 20
ROME 91 72 87 69 / 40 40 40 20
PEACHTREE CITY 88 72 85 69 / 40 40 40 20
VIDALIA 89 75 88 71 / 50 50 50 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
314 AM CDT FRI AUG 23 2013
.DISCUSSION...
829 PM CDT
A FEW LIGHT SHOWERS CONTINUE TO MOVE SOUTHWARD OUT OF THE EXTREME
SOUTHERN CWA THIS EVENING. SATELLITE IMAGERY AND A LOOK OUT THE
WINDOW SHOWS CLOUDS CLEARING FROM THE NORTHWEST. WINDS HAVE
DIMINISHED ACROSS THE AREA WITH DEWPOINTS REMAINING IN THE MID AND
UPPER 60S. HAVE MADE A FEW ADJUSTMENTS TO THE FORECAST MAINLY TO
ADD FOG MENTION TO MOST AREAS. DRIER AIR WILL SLOWLY FILTER
SOUTHWARD INTO THE AREA TONIGHT BUT THE LIGHT WINDS AND CLEARING
SKIES WILL ALLOW FOR GOOD RADIATIONAL COOLING SO EXPECT SMALL T/TD
SPREADS WITH WET TO EVEN SATURATED GROUND PROMOTING FOG
DEVELOPMENT. SOME OF THIS MAY BE DENSE SO WILL NEED TO MONITOR
TRENDS EARLY TONIGHT FOR A POSSIBLE ADVISORY IF COVERAGE BECOMES
GREAT ENOUGH. THE MAIN AREA OF CONCERN WILL BE INLAND OF THE LAKE
AND ACROSS THE OUTER CHICAGO SUBURBS TO POINTS SOUTH AND WEST. FOG
MAY LINGER PAST DAYBREAK WITH WINDS SLOWLY COMING UP AMID THE
PRESENCE OF HIGH PRESSURE.
MDB
//PREV DISCUSSION...
329 PM CDT
TONIGHT THROUGH FRIDAY NIGHT...CANADIAN HIGH PRESSURE WILL SETTLE
INTO THE GREAT LAKES REGION BEHIND A COLD FRONT. THAT FRONT IS
STILL NOT QUITE THROUGH NORTHERN IL YET. IT IS RIGHT ALONG THE
WI/IL BORDER AT 330 THIS AFTERNOON AND WILL SLOWLY DROP SOUTHWARD
THROUGH THE LOT FORECAST AREA. UNTIL THAT FRONT GETS COMPLETELY
OUT OF THE AREA...THERE WILL BE JUST ENOUGH INSTABILITY AND LOW
LEVEL CONVERGENCE TO KEEP THE MENTION OF A CHANCE FOR SHOWERS IN
THE NORTH AND SHOWERS AND THUNDERSTORMS ROUGHLY SOUTH OF CHICAGO.
THE BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS FROM LATE THIS
AFTERNOON THROUGH LATE EVENING WILL BE IN FAR SOUTHERN LOT FORECAST
AREA WHERE SHORTWAVE ENERGY WILL STILL BE IN THE VICINITY.
DRIER AIR WILL FINALLY SPILL INTO NORTHERN IL AFTER MIDNIGHT AND
HANG AROUND THROUGH FRIDAY AND FRIDAY NIGHT WITH DRY WEATHER.
EXPECTING MUCH MORE SUNSHINE FRIDAY THAN TODAY...SO MAX TEMPS WILL
BE IN THE LOWER 80S...EXCEPT A FEW DEGREES COOLER NEAR THE LAKE WITH
NORTHEAST WINDS.
MRC
SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE SLIDES OVER THE
EASTERN US DURING THIS PERIOD WHILE A 591 TO 594 DM 500 MB HIGH
PRESSURE BUILDS ACROSS THE CENTRAL US. SOME MODELS SHOW A
SHORTWAVE MOVING THROUGH SATURDAY AFTERNOON AND EVENING...BRINGING
A SHOT AT PRECIP. HOWEVER...THE MODELS ARE GENERALLY KEEPING THE
PRECIP TO THE WEST AND NORTHWEST. WILL KEEP THE PRECIP OUT OF THE
FORECAST...AS THE BEST WARM AIR ADVECTION AND COINCIDING Q VECTOR
CONVERGENCE DOES LOOK TO BE TO THE WEST AND NORTHWEST.
THE DRY FORECAST CONTINUES FOR SUNDAY...WITH THE PRECIPITATION
STAYING TO THE NORTH...OVER NORTHERN WISCONSIN...THE UPPER PENINSULA
AND NORTHERN LAKE MICHIGAN.
TEMPS ON SATURDAY WARM A BIT TO THE LOWER TO MID 80S. THEN AT 00Z
ON MONDAY 925 TEMPS REACH ABOUT 23 TO 25 C...BRINGING TEMPS IN THE
UPPER 80S TO AROUND 90 ON SUNDAY.
MONDAY THROUGH THURSDAY...A QUIET AND TOASTY FORECAST IS IN
STORE FOR NEXT WEEK. THE LOWER TO MID 90S LOOK TO STICK AROUND
THROUGH AT LEAST THURSDAY AS THE 500 MB HIGH LINGERS OVER THE
CENTRAL US AND 925 MB TEMPS STAY IN THE UPPER 20S TO AROUND 30 C.
HOWEVER...SOME MODELS CONTINUE TO HINT AT A BACKDOOR COLD FRONT
SLIDING THROUGH WEDNESDAY. THE ECMWF IS CONTINUALLY TRENDING AWAY
FROM THIS THOUGH...SO STICKING WITH THE WARM FORECAST.
TWO PASSING SURFACE LOW PRESSURES COUPLED WITH A FEW WEAK WAVES
RIDING ALONG THE NORTHERN EDGE OF THE 500 MB HIGH WILL BRING PRECIP
CHANCES TO THE NORTH OF ILLINOIS DURING THIS TIME.
MEB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* FOG...MAINLY SHALLOW...THROUGH 13Z.
* ENE WINDS AROUND 10 KT LATE THIS MORNING AND AFTERNOON.
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OOZING ITS WAY SOUTHWARD ACROSS THE UPPER MIDWEST
EARLY THIS MORNING. THE LACK OF A STRONG GRADIENT ON ITS LEADING
EDGE AND THE WET GROUND CONDITIONS LOCALLY HAVE ALLOWED FOR FOG
DEVELOPMENT. THIS WILL CONTINUE THROUGH DAYBREAK AND LIKELY AN
HOUR OR SO AFTER. THE FOG IS LIKELY TO BE SHALLOW AT FIRST BUT MAY
SETTLE IN TOWARD DAYBREAK AS THICKER. A SLIGHT NORTHEAST WIND
COMPONENT OFF THE LAKE SHOULD HELP THE PREVAILING VISIBILITY AT
ORD AND MDW REMAIN UP. WINDS WILL PICK UP DURING THE MID TO LATE
MORNING...WITH THE NORTHEAST COMPONENT OFF THE LAKE APPROACHING 10
KT. CLIMATOLOGY POINTS TO THIS BEING CLOSER TO ENE OR EVEN E BY
AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY IN THE EVE. FOG WILL BE
LESS OF A THREAT FRI NIGHT DUE TO DRYING IN THE LOW-LEVELS...BUT
STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT
SAW MORE APPRECIABLE RAIN DURING THURSDAY.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE ON PREVAILING VISIBILITIES REMAINING 5SM OR
GREATER THIS MORNING.
* MEDIUM CONFIDENCE ON WIND SPEEDS ATTAINING 10KT OR HIGHER.
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT THROUGH WED...VFR. WX NIL.
MTF
&&
.MARINE...
306 AM CDT
HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO
NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS
OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL
STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS.
THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED
SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON
SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES
LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF
THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON
NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS
LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE
MIDWEEK PERIOD.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019-
ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 AM
FRIDAY.
BEACH HAZARDS STATEMENT...ILZ014 UNTIL 9 AM FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 9 AM FRIDAY.
DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9
AM FRIDAY.
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
[top]
Area Forecast Discussion
National Weather Service Lincoln IL
243 AM CDT Fri Aug 23 2013
.DISCUSSION...
ISSUED 240 AM CDT Fri Aug 23 2013
SHORT TERM...Today through Saturday...
Initial frontal passage has taken place over all of central and
southeast Illinois early this morning, but drier air lingers a bit
further back as lower 60s dew points now starting to enter the far
northern CWA. A cluster of thunderstorms developed from
Springfield to Decatur along the remnants of an old boundary from
earlier, in an area with MUCAPE`s of around 1000 J/kg, and the
cluster has been increasing a bit over the last hour or so as it
moves south-southeast. Latest model guidance suggesting scattered
showers/storms through about mid morning over about the southeast
third of the forecast area.
Further north, fog has been thickening and increasing over the
northeast third of the state, where skies have cleared and the
drier air has arrived. So far visibilities in our area have been
staying up as a band of altocumulus has persisted, but clearing
has been taking place from Galesburg to Lacon. However, the lower
visibilities have been in areas that had quite a bit of rain on
Thursday, and much of our forecast area had a quarter inch or less
except in isolated spots. So, the question is how much of the
forecast area, if any, will see dense fog this morning. HRRR
guidance is the most pessimistic with it fairly widespread along
and north of I-74, while the most recent RAP has scaled back and
went mainly patchy dense fog in the same area. Currently have
mention of 1/2 mile visibility in fog in this area through about 9
am, but will have to monitor for any significant advection from
the northeast.
Once the fog and rain moves out, quiet weather expected through
the first part of the weekend. High pressure drifting through the
Great Lakes will advect some drier air in from the east, but
should still see highs in the mid-upper 80s.
LONG TERM...Sunday through Thursday...
Main weather story over the coming week continues to be with the
expanding heat over the center of the nation, as a large dome of
high pressure aloft drifts eastward. Any MCS ridge riders will be
well to our north, and will continue the dry forecast for next
week. Highs to rise through the 90s much of the week as thermal
ridge builds eastward. Core of this ridge will be in the area on
Wednesday. Latest ECMWF showing upper 90s over most of the
forecast area that day. Have continued to trend temperatures up a
degree or two from blended guidance with mid 90s widespread on
Wednesday. Heat index values of just over 100 likely across the
western CWA Monday-Tuesday and everywhere Wednesday. On Thursday,
the thermal ridge starts shifting westward again, but should still
see highs in the 93-95 range.
Geelhart
&&
.AVIATION...
ISSUED 1149 PM CDT Thu Aug 22 2013
A couple of convective updrafts developed along the cold front just
southeast of DEC in the last hour. MLCAPE values of 1000-1500 J/kg
will keep enough elevated instability in place for a few lightning
strikes from the stronger updrafts. Still, coverage will be
isolated and we only included a VCTS for DEC and SPI where the
front will linger the next few hours.
MVFR/IFR fog is expected to develop farther north where skies may
clear out under light winds. BMI/CMI were closer to the rainfall
from early today, so fog formation may become thicker in those
areas. We included tempos for 1SM BR 10-13z, but localized 1/4SM
FG will be possible toward sunrise. PIA fog may dip to IFR, but
the HRRR shows 1/4SM FG for all 3 northern TAF sites between 08z
and 14z. We did not hit fog that hard yet, but will monitor trends
closely.
Shimon
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1253 AM CDT FRI AUG 23 2013
.DISCUSSION...
829 PM CDT
A FEW LIGHT SHOWERS CONTINUE TO MOVE SOUTHWARD OUT OF THE EXTREME
SOUTHERN CWA THIS EVENING. SATELLITE IMAGERY AND A LOOK OUT THE
WINDOW SHOWS CLOUDS CLEARING FROM THE NORTHWEST. WINDS HAVE
DIMINISHED ACROSS THE AREA WITH DEWPOINTS REMAINING IN THE MID AND
UPPER 60S. HAVE MADE A FEW ADJUSTMENTS TO THE FORECAST MAINLY TO
ADD FOG MENTION TO MOST AREAS. DRIER AIR WILL SLOWLY FILTER
SOUTHWARD INTO THE AREA TONIGHT BUT THE LIGHT WINDS AND CLEARING
SKIES WILL ALLOW FOR GOOD RADIATIONAL COOLING SO EXPECT SMALL T/TD
SPREADS WITH WET TO EVEN SATURATED GROUND PROMOTING FOG
DEVELOPMENT. SOME OF THIS MAY BE DENSE SO WILL NEED TO MONITOR
TRENDS EARLY TONIGHT FOR A POSSIBLE ADVISORY IF COVERAGE BECOMES
GREAT ENOUGH. THE MAIN AREA OF CONCERN WILL BE INLAND OF THE LAKE
AND ACROSS THE OUTER CHICAGO SUBURBS TO POINTS SOUTH AND WEST. FOG
MAY LINGER PAST DAYBREAK WITH WINDS SLOWLY COMING UP AMID THE
PRESENCE OF HIGH PRESSURE.
MDB
//PREV DISCUSSION...
329 PM CDT
TONIGHT THROUGH FRIDAY NIGHT...CANADIAN HIGH PRESSURE WILL SETTLE
INTO THE GREAT LAKES REGION BEHIND A COLD FRONT. THAT FRONT IS
STILL NOT QUITE THROUGH NORTHERN IL YET. IT IS RIGHT ALONG THE
WI/IL BORDER AT 330 THIS AFTERNOON AND WILL SLOWLY DROP SOUTHWARD
THROUGH THE LOT FORECAST AREA. UNTIL THAT FRONT GETS COMPLETELY
OUT OF THE AREA...THERE WILL BE JUST ENOUGH INSTABILITY AND LOW
LEVEL CONVERGENCE TO KEEP THE MENTION OF A CHANCE FOR SHOWERS IN
THE NORTH AND SHOWERS AND THUNDERSTORMS ROUGHLY SOUTH OF CHICAGO.
THE BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS FROM LATE THIS
AFTERNOON THROUGH LATE EVENING WILL BE IN FAR SOUTHERN LOT FORECAST
AREA WHERE SHORTWAVE ENERGY WILL STILL BE IN THE VICINITY.
DRIER AIR WILL FINALLY SPILL INTO NORTHERN IL AFTER MIDNIGHT AND
HANG AROUND THROUGH FRIDAY AND FRIDAY NIGHT WITH DRY WEATHER.
EXPECTING MUCH MORE SUNSHINE FRIDAY THAN TODAY...SO MAX TEMPS WILL
BE IN THE LOWER 80S...EXCEPT A FEW DEGREES COOLER NEAR THE LAKE WITH
NORTHEAST WINDS.
MRC
SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE SLIDES OVER THE
EASTERN US DURING THIS PERIOD WHILE A 591 TO 594 DM 500 MB HIGH
PRESSURE BUILDS ACROSS THE CENTRAL US. SOME MODELS SHOW A
SHORTWAVE MOVING THROUGH SATURDAY AFTERNOON AND EVENING...BRINGING
A SHOT AT PRECIP. HOWEVER...THE MODELS ARE GENERALLY KEEPING THE
PRECIP TO THE WEST AND NORTHWEST. WILL KEEP THE PRECIP OUT OF THE
FORECAST...AS THE BEST WARM AIR ADVECTION AND COINCIDING Q VECTOR
CONVERGENCE DOES LOOK TO BE TO THE WEST AND NORTHWEST.
THE DRY FORECAST CONTINUES FOR SUNDAY...WITH THE PRECIPITATION
STAYING TO THE NORTH...OVER NORTHERN WISCONSIN...THE UPPER PENINSULA
AND NORTHERN LAKE MICHIGAN.
TEMPS ON SATURDAY WARM A BIT TO THE LOWER TO MID 80S. THEN AT 00Z
ON MONDAY 925 TEMPS REACH ABOUT 23 TO 25 C...BRINGING TEMPS IN THE
UPPER 80S TO AROUND 90 ON SUNDAY.
MONDAY THROUGH THURSDAY...A QUIET AND TOASTY FORECAST IS IN
STORE FOR NEXT WEEK. THE LOWER TO MID 90S LOOK TO STICK AROUND
THROUGH AT LEAST THURSDAY AS THE 500 MB HIGH LINGERS OVER THE
CENTRAL US AND 925 MB TEMPS STAY IN THE UPPER 20S TO AROUND 30 C.
HOWEVER...SOME MODELS CONTINUE TO HINT AT A BACKDOOR COLD FRONT
SLIDING THROUGH WEDNESDAY. THE ECMWF IS CONTINUALLY TRENDING AWAY
FROM THIS THOUGH...SO STICKING WITH THE WARM FORECAST.
TWO PASSING SURFACE LOW PRESSURES COUPLED WITH A FEW WEAK WAVES
RIDING ALONG THE NORTHERN EDGE OF THE 500 MB HIGH WILL BRING PRECIP
CHANCES TO THE NORTH OF ILLINOIS DURING THIS TIME.
MEB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* FOG...MAINLY SHALLOW...THROUGH 13Z.
* ENE WINDS AROUND 10 KT LATE THIS MORNING AND AFTERNOON.
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OOZING ITS WAY SOUTHWARD ACROSS THE UPPER MIDWEST
EARLY THIS MORNING. THE LACK OF A STRONG GRADIENT ON ITS LEADING
EDGE AND THE WET GROUND CONDITIONS LOCALLY HAVE ALLOWED FOR FOG
DEVELOPMENT. THIS WILL CONTINUE THROUGH DAYBREAK AND LIKELY AN
HOUR OR SO AFTER. THE FOG IS LIKELY TO BE SHALLOW AT FIRST BUT MAY
SETTLE IN TOWARD DAYBREAK AS THICKER. A SLIGHT NORTHEAST WIND
COMPONENT OFF THE LAKE SHOULD HELP THE PREVAILING VISIBILITY AT
ORD AND MDW REMAIN UP. WINDS WILL PICK UP DURING THE MID TO LATE
MORNING...WITH THE NORTHEAST COMPONENT OFF THE LAKE APPROACHING 10
KT. CLIMATOLOGY POINTS TO THIS BEING CLOSER TO ENE OR EVEN E BY
AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY IN THE EVE. FOG WILL BE
LESS OF A THREAT FRI NIGHT DUE TO DRYING IN THE LOW-LEVELS...BUT
STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT
SAW MORE APPRECIABLE RAIN DURING THURSDAY.
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE ON PREVAILING VISIBILITIES REMAINING 5SM OR
GREATER THIS MORNING.
* MEDIUM CONFIDENCE ON WIND SPEEDS ATTAINING 10KT OR HIGHER.
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT THROUGH WED...VFR. WX NIL.
MTF
&&
.MARINE...
329 PM CDT
HIGH PRESSURE OF 30.1 INCHES BUILDING ACROSS THE UPPER MIDWEST WILL
SHIFT EAST OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN
LAKES SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES
WILL DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY
AND MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH
MIDWEEK.
NORTH TO NORTHEAST WINDS WILL BUILD HIGHER WAVES IN SOUTHERN LAKE
MICHIGAN THROUGH FRIDAY NIGHT...THEN WINDS WILL SHIFT TO SOUTHERLY
ON SATURDAY AND BUILD HIGHER WAVES OVER THE NORTHERN LAKE ZONES
THROUGH MONDAY NIGHT.
MRC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ014 UNTIL 7 PM FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM FRIDAY.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1149 PM CDT Thu Aug 22 2013
.DISCUSSION...
ISSUED 900 PM CDT Thu Aug 22 2013
Showers along the cold front have diminished significantly over
the last hour, and redevelopment the rest of the night will
isolated at best as the front progresses farther south across our
forecast area. We diminished pops to just slights in the east and
south, but confidence is low than any one location will get additional
measurable rain tonight.
Clouds will begin to thin out behind the front per satellite
trends, which will help fog formation across our northern areas
that received rain. We added a mention of some fog for portions of
Marshall county to McLean county...where some of our higher
rainfall totals were.
Temps should have enough time under clearing skies to dip into the
low to mid 60s...while southern areas remain clouded and in the
upper 60s.
Updated the weather and pop grids to the latest trends. The
remainder of the forecast grids were in good shape. Updated info
will be available shortly.
Shimon
&&
.AVIATION...
ISSUED 1149 PM CDT Thu Aug 22 2013
A couple of convective updrafts developed along the cold front just
southeast of dec in the last hour. MLcape values of 1000-1500 J/kg
will keep enough elevated instability in place for a few lightning
strikes from the stronger updrafts. Still, coverage will be
isolated and we only included a vcts for dec and spi where the
front will linger the next few hours.
mvfr/ifr fog is expected to develop farther north where skies may
clear out under light winds. bmi/cmi were closer to the rainfall
from early today...so fog formation may become thicker in those
areas. We included tempos for 1sm br 10-13z, but localized 1/4sm
fg will be possible toward sunrise. PIA fog may dip to ifr, but
the HRRR shows 1/4sm fg for all 3 northern taf sites between 08z
and 14z. We did not hit fog that hard yet, but will monitor trends
closely.
Shimon
&&
.PREV DISCUSSION...
ISSUED 230 PM CDT Thu Aug 22 2013
Forecast problem of today is the convection for tonight, and then
the warming late in the weekend through the middle of next week.
SHORT TERM...Tonight through Saturday night.
Frontal zone over northern IL with upper level wave over eastern
IA to northern MO. Wave triggered convective complex over northern
IL. Airmass over central IL with MUCAPE values around 2500 and
number of outflow boundaries has triggered scattered convection
over north central cwa, with widely scattered convection in the
southeast regions due to the instability. Expect the pcpn to
gradually work its way to the south through evening, and in the
southeast possible overnight.
Boundary should be south of region Friday, and so will be pcpn
free. High pressure to keep air a little drier Saturday.
LONG TERM...Sunday through Thursday.
Upper level ridge start the building process into the our region
Sunday. Southerly surface flow will continue hot and humid air
moving into region, which will continue through mid week. Will
remain dry through forecast period.
Goetsch
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
319 AM CDT FRI AUG 23 2013
.SYNOPSIS...
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN
THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST.
AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN
ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED
ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20
CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE
1+ INCHES OF RAIN FELL YESTERDAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED
DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED
IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING
OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG
AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON.
ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN
WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA
OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA
THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE
RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE
STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA
THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS
IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR
AREA THIS AFTERNOON.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED
PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK.
THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY...
WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH
THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL
LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF
PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE
THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS
AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE
CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S.
SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE
AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK.
OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER
HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS
TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR
NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE
SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24
C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S.
SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES
SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES
TOPPING OUT IN THE UPPER 80S TO AROUND 90.
MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE
THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE
FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND
POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL
KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH
THU.
HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH
ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU.
THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEWPOINTS...
WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE
MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY
SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR
EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL
CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED
FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1145 PM CDT THU AUG 22 2013
ABUNDANT LOW LEVEL MOISTURE...MAINLY CLEAR SKIES AND LIGHT WINDS WILL
CONTINUE TO PROMOTE SOME STRATUS AND FOG DEVELOPMENT OVERNIGHT
UNTIL MID MORNING. SHALLOW STEEP LOW LEVEL INVERSION SUPPORTIVE OF
VSBYS BEING QUITE VARIABLE 1-5SM... WITH SOME PATCHY 1/4-1/2SM.
HAVE CONTINUED WITH THE LOWEST VSBYS OF LIFR AT KDBQ DUE TO WET
GROUND FROM RECENT RAINS. CANT RULE OUT VLIFR THOUGH AT KDBQ...
AND SOME OF THE LATEST HI-RES GUIDANCE CONTINUES TO SUGGEST
LIFR/VLIFR MORE WIDESPREAD ALSO AFFECTING KCID...KMLI AND KBRL BUT
HELD OFF ON MENTION AT THESE TAF SITES DUE TO LOWER CONFIDENCE.
ALSO...AREAS OF MVFR CIGS MOST PREVALENT AT KBRL OVERNIGHT WHERE
THE HIGHER SURFACE DEWPTS ARE LOCATED. COULD SEE A BRIEF PERIOD OF
MVFR CIGS AT ALL SITES DEVELOP BY MID MORNING WITH HEATING OF
LOW LEVEL MOISTURE...BUT ANY LOW CLOUDS AND FOG TO LIFT BY 18Z
WITH VFR CONDITIONS THEREAFTER AS WINDS INCREASE FROM THE E/SE AT
5-10 KTS.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUCHANAN-
CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES.
IL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUREAU-
CARROLL-JO DAVIESS-PUTNAM-STEPHENSON-WHITESIDE.
MO...NONE.
&&
$$
SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...SHEETS
AVIATION...05
AREA FORECAST DISCUSSION
NWS TOPEKA KS
340 AM CDT Fri Aug 23 2013
.SHORT TERM...(Today and Tonight)
Issued at 335 AM CDT FRI AUG 23 2013
A broad upper level ridge of high pressure will be centered over the
state of Kansas for the next 24 hours.
early this morning, elevated showers were developing due to weak
isentropic lift north of an old outflow boundary across west central
KS. At this time I think the showers should remain just west of the
cwa...though some isolated showers may develop near sunrise across
the southwest and northern counties of the CWA, but should dissipate
by mid morning. May place a 10 to 14 pop across the southwest and
northern counties in case any isolated showers develop.
Widespread convection along the foothills of CO will cause periods
of high clouds to move across the CWA Today. The 06Z NAM is the only
numerical model that breaks out deep moist convection across north
central KS late this afternoon and into the early evening hours. The
NAM may be trying to bring the MCV from the CO foothill convective
complex too far south across the center of the H5 ridge axis. The
GFS, arw, nmm and RAP show the the mcv rotating farther northeast
across western and central NE and show no qpf developing across
north central KS this afternoon. Just in case the NAM solution may
be accurate I inserted 10 to 14 pops for late this afternoon and
early evening across the northwest counties of the CWA.
High temperatures Today may be dependent on the amount of high
clouds. if the high clouds thin out this afternoon then highs will
reach into the lower to mid 90s. If we keep a thicker veil of high
clouds through the afternoon hours, then highs may only reach the
upper 80s to around 90.
Tonight, if any showers or isolated thunderstorms develop across
north central KS they should dissipate after sunset. skies should
become mostly clear through the night. overnight lows will drop into
the upper 60s to lower 70s.
.LONG TERM...(Saturday through Thursday)
Issued at 335 AM CDT FRI AUG 23 2013
Medium range models are very similar in building upper ridge
eastward through the weekend with axis over MO before retrogressing
slightly and amplifying across KS through most of next week. This
will allow for only weak inhibition by peak heating over the
weekend...but a strengthening cap into next week. However with the
exception of diurnal heating...no significant forcing evident to
warrant any pops at this point...and even less confidence into next
week. Therefore will keep the fcst through the extended dry. The
llvl thermal fields only warm slightly from the weekend into the
middle of next week...so the current fcst of only minor high temp
increases thru the middle 90s into next week looks good for now.
There is some concern that soil conditions steadily drying out and
some hint of more veering llvl windfields by the middle of next week
could lead to higher temps in the western cwa. A slight increase in
dewpoints into next week with the slightly warmer temps should inch
heat indices to around the century mark for most areas through next
week.
&&
.AVIATION...(For the 06Z TAFs through 06Z Friday Night)
Issued at 1148 PM CDT THU AUG 22 2013
Light to calm winds and mostly clear skies may lead to some MVFR
VSBYS at TOP and MHK from 10 to 13Z and have added a tempo group
for now. Outside of any fog VFR conditions are expected. South
southeast winds will increase to around 10 kts by 16Z, then
decrease after 01Z Saturday.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...53
AREA FORECAST DISCUSSION
NWS JACKSON KY
147 AM EDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 1055 PM EDT THU AUG 22 2013
WENT AHEAD AND LOWERED POPS A BIT MORE THROUGH THE OVERNIGHT WITH
CONVECTION DYING OFF. THE HRRR AND RAP13 MODELS STILL REGENERATE SOME
ACTIVITY TOWARDS DAWN...AND WILL CONTINUE TO ROLL WITH AN UPTICK IN POPS
FOR NOW.
UPDATE ISSUED AT 836 PM EDT THU AUG 22 2013
CONVECTION SEEMS TO BE ON THE DECLINE BESIDES A MORE ORGANIZED LINE
OF SHOWERS AND THUNDERSTORMS AFFECTING WEST VIRGINIA...AS WELL AS
SOME SLIGHTLY BETTER CLUSTERED CONVECTION GENERATED FROM A PASSING
OUTFLOW BOUNDARY OUT IN NORTH CENTRAL KENTUCKY. AS SUCH...HAVE LOWERED
POPS FOR THE REST OF THIS EVENING. THE LAST FEW HRRR RUNS HAVE ALSO
SHOWN A GENERAL DECLINE THROUGH THE EVENING. ONCE THE REMAINS OF THE
FRONTAL BOUNDARY AND A PASSING SHORT WAVE TROUGH MOVE THROUGH CLOSER
TO DAWN...SOME SLIGHTLY BETTER COVERAGE WILL BE POSSIBLE...MAINLY IN
THE NORTHEAST. STILL...GIVEN THE CURRENT OVERALL DOWNWARD
TREND...FELT IT WARRANTED TO TRIM BACK THE POPS A BIT INTO THE DAY ON
FRIDAY AS WELL.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 337 PM EDT THU AUG 22 2013
ISOLATED TO SCATTERED CONVECTION ACROSS THE AREA HAS REMAINED
UNORGANIZED AND TAME SO FAR TODAY...WITH LITTLE UPPER LEVEL SUPPORT
AVAILABLE. A SHORT WAVE ON WATER VAPOR IMAGERY OVER THE UPPER MS
VALLEY IS MOVING ESE...WHILE AN OLD OUTFLOW BOUNDARY AT THE SURFACE
IS FOCUSING CONVECTIVE DEVELOPMENT ACROSS CENTRAL OH AND INDIANA.
AS THE SHORT WAVE MOVES INTO THE OH VALLEY TONIGHT...THERE WILL BE
BETTER UPPER LEVEL SUPPORT FOR PRECIPITATION ACROSS THE FORECAST
AREA. THE EXACT EVOLUTION OF CONVECTION DEVELOPING ACROSS OH AND
INDIANA IS UNCERTAIN...AND THE 17Z HRRR HAS MOST PRECIPITATION DYING
OUT BY 02Z. HOWEVER IT DOES SHOW REDEVELOPMENT AROUND 05Z MOST
LIKELY IN ASSOCIATION WITH AN UPPER LEVEL SPEED MAX ASSOCIATED WITH
THE UPPER TROF. THE NAM IS MOST SUPPORTIVE OF PRECIPITATION
OVERNIGHT...BUT THE GFS...ECMWF AND GEM ALL POINT TOWARDS A CHANCE
OF SHOWERS AND THUNDERSTORMS. IT DOES APPEAR THE BEST SUPPORT WILL BE
OVER THE NORTHERN AND EASTERN PORTION OF THE FORECAST AREA AND HAVE
ELECTED TO GO WITH LIKELY PROBABILITY OF RAIN CHANCES IN THESE AREAS
WITH A CHANCE IN THE SOUTHWEST. WEAK COLD FRONT WILL NOT CLEAR THE
AREA UNTIL FRIDAY EVENING...SO WILL CONTINUE WITH A CHANCE OF SHOWERS
AND THUNDERSTORMS FRIDAY...BUT DECREASE CHANCES FROM THE NORTH DURING
THE DAY.
WITH PRECIPITABLE WATER AROUND 1.9 INCHES OR NEAR THE 90TH
PERCENTILE...WILL CONTINUE TO MENTION HEAVY RAIN AND FLASH FLOOD
POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK FOR TONIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 337 PM EDT THU AUG 22 2013
OT A LOT OF CHANGE FROM PREVIOUS FORECAST. MODELS ARE STILL IN
RELATIVELY GOOD AGREEMENT THAT THE UPPER AIR PATTERN WILL CONSIST OF
A LARGE 500MB RIDGE ACROSS THE SOUTH CENTRAL CONUS...EXPECTED TO
REMAIN IN PLACE THROUGH THE DURATION OF THE FORECAST PERIOD. WITH
UPPER LEVEL TROUGHING OFF BOTH THE NW AND NE COAST...EASTERN KY WILL
FIND ITSELF WITHIN THE RIDGING PATTERN...BUT ON THE WINDWARD SIDE OF
THE NE TROUGHING PATTERN. ANY SHORTWAVE THAT TRAVELS ALONG THE
TROUGH AXIS WILL MAKE ITS WAY NEAR EASTERN KY DESPITE THE STRONG
RIDGING IN PLACE. HOWEVER...WITH SOMEWHAT LESS AGREEMENT ON THE
SMALLER SCALE...ANY SHORTWAVES AND RESULTING RAIN CHANCES WILL BE
BEST LEFT TO A MODEL CONSENSUS.
WITH A GOOD VEERING WIND PROFILE...AND TEMPERATURES EXPECTED TO BE
WARMER AND MORE HUMID THAN HAVE BEEN OVER THE PAST FEW WEEKS...ALL
MODELS ARE POINTING AT THE POTENTIAL FOR AFTERNOON INSTABILITY AND
CONVECTION ACROSS THE EASTERN PORTION OF THE STATE THROUGH THE
ENTIRE FORECAST PERIOD. THE ONLY CAVEAT TO THIS IS THE FACT THAT
GFS40 SOUNDINGS /BOTH CURRENT AND PREVIOUS/ ARE SHOWING AN ABUNDANT
AMOUNT OF DRY AIR AT ALL LEVELS...WITH ONLY THE POTENTIAL FOR A SCT
THIN LAYER OF DIURNAL CLOUDS. AND THOUGH THERE IS A GOOD VEERING
PATTERN MENTIONED ABOVE...MOST OF THIS TAKES PLACE IN THE MID LEVELS
RATHER THAN THE LOWER LEVELS...WITH A LOW AMOUNT OF CAPE AND A VERY
LIMITED AMOUNT OF TIME IN THE AFTERNOON WHERE THERE IS NOT A CAPPING
INVERSION. ALL THINGS CONSIDERED...DID PUT IN SOME SLIGHT CHANCE
POPS IN THE AFTERNOON TO GO ALONG WITH MODEL CONSENSUS...BUT EXPECT
THUNDERSTORM DEVELOPMENT TO BE EVEN MORE ISOLATED IN COMPARISON TO
SHOWER POTENTIAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 146 AM EDT FRI AUG 23 2013
FOG WILL CONTINUE TO DEVELOP TONIGHT...THICKENING IN THE DEEPER
VALLEYS AND SPREADING OUT FROM THERE. NOT CONFIDENT IN EVENTUAL
OUTCOMES AT TAF SITES...BUT AT LEAST MVFR CAN BE EXPECTED AT TIMES...
AND POSSIBLY IFR. ISOLATED SHOWERS COULD ALSO REDEVELOP TOWARD
DAWN...ESPECIALLY IN THE NE PART OF THE AREA. FOG WILL THEN DISSIPATE
WELL AFTER SUNRISE...POSSIBLY BRIEFLY LIFTING INTO AN IFR OR LOW MVFR
CLOUD DECK BEFORE RISING FURTHER AND SCATTERING LATER IN THE MORNING.
WITH DAYTIME HEATING...SCATTERED THUNDERSTORMS MAY BE A THREAT DURING
THE MID-LATE AFTERNOON HOURS. OUTSIDE OF PRECIP IN THE AFTERNOON AND
EVENING...VFR IS EXPECTED.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...JMW
AVIATION...HAL
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1118 PM MDT THU AUG 22 2013
.AVIATION...
06Z TAF CYCLE
VFR CONDITIONS TO PERSIST THROUGH THE TAF PERIOD OUTSIDE OF
ISOLATED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE
FORECAST AREA FRIDAY AFTERNOON AND EVENING. TERMINALS MOST LIKELY
TO BE IMPACTED ARE KGUP AND KFMN LATE FRIDAY. BRIEF MVFR
CONDITIONS LIKELY WITH THUNDERSTORMS FRIDAY AFTERNOON/EVENING.
11
&&
.PREV DISCUSSION...254 PM MDT THU AUG 22 2013...
NOT MUCH CHANGE TO THE FORECAST. AS EXPECTED...EVEN LESS CONVECTION
HAS POPPED UP THIS AFTERNOON AS THE DRY WEDGE AHEAD OF THE EASTERLY
WAVE MOVES ACROSS THE STATE. ALSO OF NOTE IS A PRETTY HEALTHY
INVERSION AROUND 550 MB ON THE 12Z ABQ SOUNDING. BEST CHANCES FOR
STORMS FOR THE REST OF THE EVENING WILL BE ACROSS THE NORTHERN
MTNS...AND IF THE HRRR IS CORRECT...MOST OF THE PRECIPITATION WILL
BE DONE BY 03Z.
THE DRY WEDGE SHOULD BE OVER NORTHERN NM TOMORROW. MEANWHILE...THE
UPPER HIGH WILL CONTINUE TO CREEP EASTWARD...AND WILL BE CENTERED
OVER OK/KS BY TOMORROW AFTN. THIS WILL ALLOW SOME OF THE MOISTURE
ASSOCIATED WITH THE EASTERLY WAVE TO CREEP UP INTO NM FRIDAY
AFTN/NIGHT. THIS SHOULD ALLOW FOR AN UPTICK IN SHOWER AND
THUNDERSTORM COVERAGE ON SATURDAY...MAINLY ACROSS THE HIGHER
TERRAIN.
BY SUNDAY AFTN...THE UPPER HIGH STRENGTHENS TO 596DAM AND THE
WESTWARD EXTENSION OF THE HIGH WILL BUILD BACK INTO NM. THIS WILL
KEEP THE BULK OF THE MOISTURE ASSOCIATED WITH AND AHEAD OF NOW
TROPICAL DEPRESSION NINE-E TO THE WEST OF THE STATE. INSTEAD...IT
APPEARS SOME RELATIVELY DRIER AIR WILL CIRCLE IN OVER NM.
THE GFS WANTS TO BRING ANOTHER WEAK WAVE ROUNDING THE SOUTH SIDE OF
THE UPPER HIGH INTO THE STATE ON MONDAY. THERE IS SOME MODEST
MOISTURE ASSOCIATED WITH THIS... SO THERE MAY BE A FEW MORE STORMS
THAN ON SUNDAY. HOWEVER THE ECMWF DOES NOT REALLY SHOW THIS FEATURE
OR THE MOISTURE MOVING UP INTO NM UNTIL AT LEAST 24 HOURS LATER. SO
FOR NOW...MONDAY-WEDNESDAY LOOKS FAIRLY MINIMAL PRECIPITATION-WISE.
LATER IN THE WEEK...MODELS LOOK TO WEAKEN THE WESTWARD EXTENSION OF
THE HIGH...WHICH MAY ALLOW FOR SOME RICHER MONSOON MOISTURE TO MOVE
INTO WESTERN AND CENTRAL NM...ESPECIALLY IF THERE IS INDEED A SECOND
TROPICAL SYSTEM LURKING SOUTH OF THE BAJA AS MODELS ARE INDICATED.
34
.FIRE WEATHER...
A MORE STABLE AND DRIER AIRMASS HAS INFILTRATED A LARGE PORTION OF
THE FORECAST AREA TODAY. THE RESULT IS ISOLATED SMALLER FOOTPRINTS
OF WETTING RAIN. THE STEERING FLOW FOR THE STORMS THE REST OF TODAY
WILL BE TOWARDS THE NORTHEAST.
THE HEART OF THE DRIER AIRMASS WILL SHIFT TO THE NORTH AND NORTHEAST
ON FRIDAY. THUNDERSTORM COVERAGE WILL INCREASE BUT THE WETTING RAIN
FOOTPRINT WONT INCREASE TOO MUCH. HIGH TEMPERATURES WILL BE NEAR TO
SLIGHTLY BELOW NORMAL SOUTH AND NEAR TO SLIGHTLY ABOVE NORMAL NORTH.
VENTILATION RATES WILL BE PRETTY GOOD AS SOUTH/SOUTHEAST WINDS
INCREASE ACROSS THE AREA. SOME BREEZES WILL BE OBSERVED ACROSS THE
EASTERN PLAINS...ESPECIALLY NORTHEAST WHERE A LEE SURFACE TROUGH
STRENGTHENS.
THE UPPER HIGH WILL STRENGTHEN AND BECOME DOMINATE OVER THE SOUTHERN
PLAINS AND MID MISSISSIPPI VALLEY REGION DURING THE WEEKEND.
CONFIDENCE IS PRETTY HIGH FOR THAT PATTERN. DUE TO THE ABOVE NORMAL
STRENGTH TO THE UPPER HIGH...THUNDERSTORM COVERAGES WILL VARY.
SATURDAY STILL LOOKS TO BE A MORE ACTIVE WETTING THUNDERSTORM DAY.
THE CONTINENTAL DIVIDE AND TO A LESSER EXTENT THE CENTRAL MTN CHAIN
WOULD BE FAVORED. THERE IS SOME DISCREPANCY IN THE MODELS AS FAR AS
CENTRAL MOUNTAINS ARE CONCERNED. STEERING FLOW ON SATURDAY WOULD
TAKE THE STORMS TOWARDS THE NORTH AND NORTHEAST. A DRIER AND MORE
STABLE AIRMASS PIVOTING AROUND THE UPPER HIGH IS STILL EXPECTED TO
INVADE PORTIONS OF THE AREA ON SUNDAY. THE ECMWF/GFS AND NAM
MODELS DEPICT THIS. BREEZES WOULD ENHANCE ACROSS THE EASTERN
PLAINS DURING THE WEEKEND. THIS IS A RESULT OF AN UNUSUALLY STRONG
LEE SIDE SURFACE TROUGH THAT IS EXPECTED TO STRENGTHEN DURING THE
PERIOD. THE PEAK WIND PERIOD WOULD BE ON SATURDAY.
THE LONGER RANGE MODELS STILL SHOW THE MAIN MONSOONAL PLUME WRAPPING
AROUND THE UPPER HIGH OVER ARIZONA AND FAR WEST NEW MEXICO DURING
THE EARLIER HALF OF NEXT WEEK. THE DRIER AND MORE STABLE AIRMASS
WOULD GET SHIFTED SOME TOWARDS THE EAST SO THUNDERSTORM COVERAGE
EACH DAY SHOULD INCREASE SLIGHTLY FROM WEST TO EAST. AGAIN...MAINLY
KEEPING STORMS WEST OF THE CENTRAL MTNS AND ESPECIALLY FAVORING THE
CONTINENTAL DIVIDE. TEMPERATURES WOULD BE ABOVE NORMAL EAST AND NEAR
NORMAL WEST. THE LEE TROUGH WILL REMAIN ACROSS THE EASTERN PLAINS
BUT IS EXPECTED TO WEAKEN SOME AS TIME PROGRESSES. THUS LOOK FOR THE
OVERALL WIND FLOW TO LESSEN SOME. GUSTY OUTFLOW WINDS WOULD REMAIN A
CONCERN HOWEVER...ACROSS WESTERN AND CENTRAL AREAS.
THE ECMWF AND GFS REMAINS PRETTY STEADFAST IN KEEPING THE MAIN UPPER
HIGH CENTER TO THE EAST OF THE STATE THE LATTER HALF OF NEXT WEEK.
THE HIGH ALSO LOOKS TO BE QUITE STRONG AND SIMILAR TO THE STRENGTH
AND POSITION IT WAS AUGUST 2011. MOISTURE WOULD CONTINUE TO OOZE
EASTWARD DUE TO OUTFLOW BOUNDARIES FROM CONVECTION ACROSS THE WEST
BUT THE FAVORED AREAS FOR WETTING RAIN WOULD REMAIN WEST. THE
EASTERN PLAINS ONCE AGAIN LOOK TO BE ON THE DRIER AND WARMER SIDE.
THE CURING OF NEW GRASS GROWTH ACROSS THE EAST WOULD MOST LIKELY
START UP DURING THIS PERIOD.
50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
52
AREA FORECAST DISCUSSION
NWS RALEIGH NC
252 AM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTH THIS AFTERNOON...THEN PUSH
SOUTH THROUGH THE REGION TONIGHT AS AN UPPER LEVEL TROUGH DIGS
SOUTHEAST ACROSS THE MID ATLANTIC. COOL AND DRY HIGH PRESSURE WILL
BUILD INTO THE CAROLINAS FROM THE NORTH IN THE WAKE OF THE COLD
FRONT ON SATURDAY AND SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 945 PM THURSDAY...
SEVERAL CLUSTERS OF PROBLEMATIC STORMS HAVE AFFECTED MAINLY THE
EASTERN CWA SINCE LATE AFTERNOON... BUT ISOLATED STORM CLUSTERS
PERSIST AROUND THE ENTIRE AREA AS A MODERATELY UNSTABLE AIR MASS
(MLCAPE VALUES STILL 1500-2000 J/KG) LINGERS. DEEP LAYER SHEAR
REMAINS RESPECTABLE AT 25-30 KTS IN THE BASE OF THE MID LEVEL
SHORTWAVE TROUGH NOW SWINGING THROUGH NY/DE/ERN VA/ERN NC... BUT
THIS SHOULD BE WANING OVERNIGHT AS THE TROUGH PROGRESSES OFFSHORE.
INSTABILITY IS LIKEWISE EXPECTED TO FALL BELOW 1000 J/KG
OVERNIGHT... AND WITH PRECIP WATER VALUES HAVING DROPPED TO AT OR
UNDER 1.5 INCHES OVER MUCH OF CENTRAL NC ACCORDING TO BLENDED TPW
IMAGERY... WE SHOULD SEE EVEN THE ISOLATED STORM CLUSTERS LESSEN IN
COVERAGE AND INTENSITY OVER THE NEXT SEVERAL HOURS AS WE LOSE BOTH
DYNAMIC AND THERMODYNAMIC SUPPORT. WILL RETAIN THE ISOLATED STORM
MENTION FOR ANOTHER FEW HOURS BEFORE DROPPING SHOWER/STORM CHANCES
TO UNDER 15 PERCENT LATE TONIGHT. THIS FOLLOWS RECENT HRRR MODEL
OUTPUT TRENDS. FAIR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL
FACILITATE PATCHY FOG DEVELOPMENT LATE. LOW 68-72... IN LINE WITH
STATISTICAL GUIDANCE AND PERSISTENCE. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 239 AM FRIDAY...
MUCH DRIER AND COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND
COURTESY OF THE MODERATELY STRONG SURFACE HIGH PRESSURE (1026+ MB)
THAT WILL BUILD FROM NEW ENGLAND DOWN THE ATLANTIC SEABOARD INTO
SC/GA THROUGH SUNDAY NIGHT. THE ONLY ISSUE REALLY WILL BE THE AMOUNT
OF CLOUDINESS THAT WILL AFFECT OUR REGION SATURDAY. MODELS AGREE IN
PUSHING THE COLD FRONT WELL THROUGH THE REGION BY 12Z/SAT. DAA/CAA
WILL OCCUR WITH THE NE FLOW AT THE SURFACE. HOWEVER... SOME MODEL
SOLUTIONS INDICATE A TEMPERATURE INVERSION WITH MOISTURE BECOMING
TRAPPED UNDER THAT INVERSION IMMEDIATELY BEHIND THE FRONT SATURDAY
MORNING INTO THE EARLY AFTERNOON. ALTHOUGH MEASURABLE RAIN IS NOT
EXPECTED... VARIABLY CLOUDY SKIES SHOULD RESULT ESPECIALLY IN THE
SOUTH AND WEST THROUGH SATURDAY AFTERNOON. EXPECT DECREASING
CLOUDINESS FROM N TO S SAT AFTERNOON INTO SAT NIGHT. MOSTLY SUNNY
SKIES SUNDAY. HIGHS 80-85 BOTH DAYS. LOWS 55-63 SUNDAY AND MONDAY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 239 AM FRIDAY...
THE BUILDING UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY NEXT WEEK
POSES A BIT OF A PROBLEM FOR OUR REGION... THE RETURN OF THE NW FLOW
ALOFT. THIS SHOULD BE MOST PRONOUNCED TUESDAY AND BEYOND WHEN
SEVERAL VORTICITY MAXIMUMS IN THE NW FLOW (WHICH WILL BE HARD TO
TIME) MAY AFFECT OUR REGION. EXPECT INCREASING HEAT... HUMIDITY...
AND THE CHANCE OF THUNDERSTORMS MID TO LATE WEEK. STILL... NO HEAT
WAVE CONDITIONS ARE ANTICIPATED ALONG OR EAST OF THE APPALACHIANS
WITH THIS PATTERN. MONDAY... MOSTLY SUNNY. LOWS 55-62. HIGHS 80-85.
TUESDAY AND WEDNESDAY... PARTLY SUNNY. A SLIGHT CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS IN THE NW TUESDAY... THEN A CHANCE ALL
ZONES WEDNESDAY AND THURSDAY. LOWS MODERATING INTO THE LOWER 70S BY
THURSDAY. HIGHS 85-90.
&&
.AVIATION /06Z FRIDAY THROUGH WEDNESDAY/...
AS OF 230 AM FRIDAY...
24-HR TAF PERIOD:
ANTICIPATE A CHANCE FOR MVFR FOG AT ALL TAF SITES BETWEEN 08-11Z
THIS MORNING. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THROUGH
EARLY AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED
TO DEVELOP BY EARLY/MID AFTERNOON IN ADVANCE OF AN UPPER LEVEL
DISTURBANCE AND ASSOCIATED COLD FRONT APPROACHING THE REGION FROM
THE NORTHWEST...WITH SCATTERED CONVECTION TRACKING SOUTHEAST ACROSS
CENTRAL NC DURING THE MID/LATE AFTERNOON (18-00Z) HOURS. ALL TAF
SITES WILL LIKELY BE AFFECTED BY CONVECTION...THOUGH THE TERMINALS
WITH THE BEST OVERALL CHANCE FOR SHOWERS/STORMS (AND BEST CHANCE FOR
AN ISOLD SEVERE STORM) WILL BE RDU/RWI/FAY. WINDS WILL VEER FROM
W/NW TO NORTHEAST AT 5-10 KT IN THE WAKE OF THE FRONT BETWEEN SUNSET
AND MIDNIGHT...OR THE 00-04Z TIME FRAME. A BRIEF PERIOD OF MVFR/IFR
CEILINGS CANNOT BE RULED OUT OVERNIGHT BETWEEN 04-12Z SAT AS
LOW-LEVEL FLOW INITIALLY STRENGTHENS OUT OF THE NORTHEAST...THOUGH
PROBABILITIES ARE TOO LOW TO MENTION AND ANY SUB-VFR CEILINGS WOULD
BE SHORT-LIVED AS A MUCH DRIER AIRMASS ADVECTS INTO CENTRAL NC BY OR
SHORTLY AFTER SUNRISE SAT.
LOOKING AHEAD:
EXCELLENT (VFR) AVIATION CONDITIONS WILL PREVAIL SAT-MON IN ASSOC/W
DRY HIGH PRESSURE EXTENDING INTO AND EVENTUALLY SETTLING OVER THE
CAROLINAS FROM THE NORTH. A BRIEF PERIOD OF SUB-VFR FOG CANNOT BE
RULED OUT AROUND SUNRISE MONDAY MORNING. ANTICIPATE AN INCREASING
CHANCE FOR PRIMARILY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
TUE-THU. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
239 AM EDT FRI AUG 23 2013
.SYNOPSIS...
A PRE-FRONTAL TROUGH WILL LINGER OVER THE REGION TODAY. A COLD FRONT
WILL PUSH SOUTH THROUGH NORTH CAROLINA FRIDAY NIGHT AND EARLY
SATURDAY. HIGH PRESSURE WILL BRING COOLER AND DRIER AIR FOR THE
WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 945 PM THURSDAY...
SEVERAL CLUSTERS OF PROBLEMATIC STORMS HAVE AFFECTED MAINLY THE
EASTERN CWA SINCE LATE AFTERNOON... BUT ISOLATED STORM CLUSTERS
PERSIST AROUND THE ENTIRE AREA AS A MODERATELY UNSTABLE AIR MASS
(MLCAPE VALUES STILL 1500-2000 J/KG) LINGERS. DEEP LAYER SHEAR
REMAINS RESPECTABLE AT 25-30 KTS IN THE BASE OF THE MID LEVEL
SHORTWAVE TROUGH NOW SWINGING THROUGH NY/DE/ERN VA/ERN NC... BUT
THIS SHOULD BE WANING OVERNIGHT AS THE TROUGH PROGRESSES OFFSHORE.
INSTABILITY IS LIKEWISE EXPECTED TO FALL BELOW 1000 J/KG
OVERNIGHT... AND WITH PRECIP WATER VALUES HAVING DROPPED TO AT OR
UNDER 1.5 INCHES OVER MUCH OF CENTRAL NC ACCORDING TO BLENDED TPW
IMAGERY... WE SHOULD SEE EVEN THE ISOLATED STORM CLUSTERS LESSEN IN
COVERAGE AND INTENSITY OVER THE NEXT SEVERAL HOURS AS WE LOSE BOTH
DYNAMIC AND THERMODYNAMIC SUPPORT. WILL RETAIN THE ISOLATED STORM
MENTION FOR ANOTHER FEW HOURS BEFORE DROPPING SHOWER/STORM CHANCES
TO UNDER 15 PERCENT LATE TONIGHT. THIS FOLLOWS RECENT HRRR MODEL
OUTPUT TRENDS. FAIR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL
FACILITATE PATCHY FOG DEVELOPMENT LATE. LOW 68-72... IN LINE WITH
STATISTICAL GUIDANCE AND PERSISTENCE. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 239 AM FRIDAY...
MUCH DRIER AND COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND
COURTESY OF THE MODERATELY STRONG SURFACE HIGH PRESSURE (1026+ MB)
THAT WILL BUILD FROM NEW ENGLAND DOWN THE ATLANTIC SEABOARD INTO
SC/GA THROUGH SUNDAY NIGHT. THE ONLY ISSUE REALLY WILL BE THE AMOUNT
OF CLOUDINESS THAT WILL AFFECT OUR REGION SATURDAY. MODELS AGREE IN
PUSHING THE COLD FRONT WELL THROUGH THE REGION BY 12Z/SAT. DAA/CAA
WILL OCCUR WITH THE NE FLOW AT THE SURFACE. HOWEVER... SOME MODEL
SOLUTIONS INDICATE A TEMPERATURE INVERSION WITH MOISTURE BECOMING
TRAPPED UNDER THAT INVERSION IMMEDIATELY BEHIND THE FRONT SATURDAY
MORNING INTO THE EARLY AFTERNOON. ALTHOUGH MEASURABLE RAIN IS NOT
EXPECTED... VARIABLY CLOUDY SKIES SHOULD RESULT ESPECIALLY IN THE
SOUTH AND WEST THROUGH SATURDAY AFTERNOON. EXPECT DECREASING
CLOUDINESS FROM N TO S SAT AFTERNOON INTO SAT NIGHT. MOSTLY SUNNY
SKIES SUNDAY. HIGHS 80-85 BOTH DAYS. LOWS 55-63 SUNDAY AND MONDAY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 239 AM FRIDAY...
THE BUILDING UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY NEXT WEEK
POSES A BIT OF A PROBLEM FOR OUR REGION... THE RETURN OF THE NW FLOW
ALOFT. THIS SHOULD BE MOST PRONOUNCED TUESDAY AND BEYOND WHEN
SEVERAL VORTICITY MAXIMUMS IN THE NW FLOW (WHICH WILL BE HARD TO
TIME) MAY AFFECT OUR REGION. EXPECT INCREASING HEAT... HUMIDITY...
AND THE CHANCE OF THUNDERSTORMS MID TO LATE WEEK. STILL... NO HEAT
WAVE CONDITIONS ARE ANTICIPATED ALONG OR EAST OF THE APPALACHIANS
WITH THIS PATTERN. MONDAY... MOSTLY SUNNY. LOWS 55-62. HIGHS 80-85.
TUESDAY AND WEDNESDAY... PARTLY SUNNY. A SLIGHT CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS IN THE NW TUESDAY... THEN A CHANCE ALL
ZONES WEDNESDAY AND THURSDAY. LOWS MODERATING INTO THE LOWER 70S BY
THURSDAY. HIGHS 85-90.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 730 PM THURSDAY...
A SURFACE TROUGH...AS WELL AS VARIOUS OUTFLOW BOUNDARIES...AND
LINGERING INSTABILITY ARE KEEPING A FEW STORMS GOING AROUND CENTRAL
NC THIS EVENING...THOUGH MOST OF THE STORMS ARE OCCURRING AWAY FROM
TAF SITES AND SHOULD COME TO AN END BY MIDNIGHT. A LIGHT
WEST-SOUTHWESTERLY SURFACE WIND AND MOSTLY VFR CONDITIONS ARE
EXPECTED...THOUGH A FEW AREAS MAY SEE MVFR VSBYS BY DAYBREAK.
AN APPROACHING COLD FRONT WILL INITIATE SCATTERED STORMS BY EARLY
FRIDAY AFTERNOON...FIRST AROUND THE TRIAD THEN MOVING SOUTH AND EAST
TOWARD KRDU..KRWI AND KFAY. THE OCCURRENCE AND TIMING OF STORMS AT
INDIVIDUAL TERMINALS IS STILL UNCERTAIN AT THIS POINT...BUT THE
PRESENCE OF THE COLD FRONT AND UPPER LEVEL TROUGH LENDS ENOUGH
FORECAST CONFIDENCE FOR A MENTION OF THUNDERSTORMS IN THE TAFS AFTER
18Z.
LOOKING AHEAD:
AFTER THE PASSAGE OF THE COLD FRONT...HIGH PRESSURE WILL SLOWLY
BUILD INTO THE REGION AND STRENGTHEN...LEADING TO A TREND TOWARD
VFR CONDITIONS THROUGH EARLY NEXT WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...HARTFIELD
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
250 AM CDT FRI AUG 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM
POTENTIAL AND AREAL COVERAGE.
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER
SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW
PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL
SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND
HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR
CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE
NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN
SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE
LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT
FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE
ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT
APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE
CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR
AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH
INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN
SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS
TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON
INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE
TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH
FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH
CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST
INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN
CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN
NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG
WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S.
FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS
AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE
IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND
INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN
THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT
CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC
THUNDERSTORM CHANCES.
THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH
FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN
TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S
TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH
SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS
THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON
HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY
ACROSS THE SOUTH.
EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING
SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE
WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA.
THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD.
MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY
NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS
THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC
SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE
WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL
LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY.
THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN
THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE.
THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS
THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE
ENERGY CONTINUING TO TRAVERSE THE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1222 AM CDT FRI AUG 23 2013
VFR CIGS EXPECTED FOR THIS FORECAST PERIOD...ALTHOUGH RELATIVE
HUMIDITY AND CLOUD CROSS SECTIONS SHOW A MOIST SOUTHEAST FLOW MAY
YIELD A SCT TO BKN LOW VFR CIG TOWARD SUNRISE AT KDIK AND KBIS.
OTHERWISE...AS MENTIONED ABOVE SCT/BKN VFR CIGS EXPECTED FRIDAY
WITH A SLIGHT CHANCE FOR THUNDERSTORMS TOWARD 00Z AND INTO THE 06Z
SATURDAY TIME FRAME. A LOT OF UNCERTAINTY BOTH IN REGARDS TO WHERE
THE THUNDERSTORMS MAY INITIATE AND WHAT WILL BE THE AREAL COVERAGE.
THUS HAVE MENTIONED A VCTS AT THOSE AERODROMES WHEN THE THUNDERSTORM
THREAT INCREASES AND WILL CONTINUE TO MONITOR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
343 AM CDT FRI AUG 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 258 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES
TONIGHT.
CURRENTLY AS OF 07Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE
PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL
RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE
U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER
OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND
TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED
WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG
WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER
VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER
THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90
AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS
ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING
CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM
EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG
IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG
ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS
RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL.
HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE
SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA.
SYNOPTIC OVERVIEW...
MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY
EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE
RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED
OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL
SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS
SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA
TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE
FORECAST AREA.
DETAILS...
QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF
THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES
START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN
SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO
DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING
HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG
SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM.
HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS...
DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM
THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO
CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING...
ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET.
THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST
THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z
SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN
PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE
EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z
NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE
TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER
NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 258 AM CDT FRI AUG 23 2013
HAZARDS...
THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS
LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF
THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY
ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT
THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY
FOR MONDAY AND TUESDAY.
SYNOPTIC OVERVIEW...
23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84
HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY
LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG
TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER
MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS
AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL
ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE...
MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN
MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A
PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE
BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE
DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO
THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE.
PRECIPITATION DETAILS...
FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE
850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST
ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE
MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN
ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE
COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY
ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE
COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE...
HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF
20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH
INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME
LOCALLY HEAVY RAIN.
PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT
WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT
CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA
BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z
GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS
DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN
NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS
IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT
CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER
MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY
BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z
ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE...
FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR
SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND
BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY
ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE.
FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES
NEEDED EACH DAY IN THIS AREA.
TEMPERATURE DETAILS...
FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS
OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR
MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST
WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE
AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER.
TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB
TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY
PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING
TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S.
HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE.
MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER
THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN
30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF
90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO
SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE
DAYS WILL NEED AT LEAST A HEAT ADVISORY.
WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z
ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND
WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST
AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS
EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE
COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR
NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT
ADVISORY CONDITIONS.
LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW
TO MID 70S EVERY NIGHT.
GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY
MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS
AT THIS TIME.
NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1155 PM CDT THU AUG 22 2013
CHALLENGING RIVER VALLEY FOG SETUP FOR KLSE AS A FEW COMPETING
FACTORS COULD LEAD TO 1/4SM...OR NOTHING AT ALL. AS HIGH PRESSURE
SETTLES TO THE NORTH...SOUTHEASTERLY SURFACE WINDS WILL REMAIN
GENERALLY 5 MPH OR LESS. HOWEVER...925 TO 900 MB WINDS ARE EXPECTED
TO INCREASE FROM 5 TO 7 MPH THIS EVENING...TO NEARLY 15 TO 20 MPH BY
10Z ACCORDING TO VARIOUS MODEL SOUNDINGS. THIS WIND INCREASE DOES
NOT SUPPORT A DENSE FOG EVENT. HOWEVER...THE LATE ARRIVAL OF THIS
SPEED MAX COULD ALLOW FOG TO FORM IN THE CHANNEL...THEN TRAP IT
BELOW THE INVERSION. ALSO...TRENDS IN THE MODEL SOUNDINGS ARE NOT AS
CONSISTENT...AND SOME PREVIOUS RUNS SHOWED A LIGHTER WIND LAYER. ALL
IN ALL...WHILE THE WIND ISSUE MAY HURT DENSE FOG CHANCES...NOT SOLD
YET THAT IT WILL PRECLUDE DENSE FOG FORMATION. T/TD IS DOWN TO 5 F
AS OF 04Z...WITH SFC WINDS REMAINING LIGHT. BOTH FAVORABLE FOR DENSE
FOG. KLSE TAF WAS UPDATED BEFORE 03Z TO INCLUDE A PERIOD OF
1/4SM...AND WILL CONTINUE THIS. EXPECT RAPID IMPROVEMENT/CLEARING
AROUND 14Z. REST OF THE DAY SHOULD BE VFR...WITH CLOUDS INCREASING
OVERNIGHT FRIDAY...AND THE CHANCE FOR SCT SHRA/TS ON SAT.
&&
.CLIMATE...
ISSUED AT 343 AM CDT FRI AUG 23 2013
GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR
LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE
INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055-
061.
MN...NONE.
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....ZT/RIECK
CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
258 AM CDT FRI AUG 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 258 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES
TONIGHT.
CURRENTLY AS OF 07Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE
PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL
RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE
U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER
OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND
TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED
WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG
WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER
VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER
THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90
AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS
ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING
CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM
EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG
IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG
ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS
RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL.
HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE
SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA.
SYNOPTIC OVERVIEW...
MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY
EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE
RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED
OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL
SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS
SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA
TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE
FORECAST AREA.
DETAILS...
QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF
THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES
START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN
SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO
DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING
HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG
SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM.
HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS...
DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM
THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO
CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING...
ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET.
THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST
THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z
SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN
PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE
EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z
NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE
TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER
NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 258 AM CDT FRI AUG 23 2013
HAZARDS...
THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS
LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF
THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY
ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT
THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY
FOR MONDAY AND TUESDAY.
SYNOPTIC OVERVIEW...
23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84
HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY
LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG
TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER
MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS
AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL
ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE...
MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN
MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A
PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE
BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE
DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO
THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE.
PRECIPITATION DETAILS...
FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE
850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST
ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE
MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN
ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE
COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY
ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE
COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE...
HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF
20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH
INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME
LOCALLY HEAVY RAIN.
PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT
WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT
CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA
BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z
GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS
DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN
NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS
IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT
CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER
MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY
BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z
ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE...
FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR
SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND
BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY
ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE.
FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES
NEEDED EACH DAY IN THIS AREA.
TEMPERATURE DETAILS...
FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS
OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR
MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST
WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE
AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER.
TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB
TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY
PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING
TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S.
HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE.
MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER
THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN
30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF
90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO
SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE
DAYS WILL NEED AT LEAST A HEAT ADVISORY.
WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z
ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND
WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST
AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS
EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE
COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR
NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT
ADVISORY CONDITIONS.
LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW
TO MID 70S EVERY NIGHT.
GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY
MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS
AT THIS TIME.
NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1155 PM CDT THU AUG 22 2013
CHALLENGING RIVER VALLEY FOG SETUP FOR KLSE AS A FEW COMPETING
FACTORS COULD LEAD TO 1/4SM...OR NOTHING AT ALL. AS HIGH PRESSURE
SETTLES TO THE NORTH...SOUTHEASTERLY SURFACE WINDS WILL REMAIN
GENERALLY 5 MPH OR LESS. HOWEVER...925 TO 900 MB WINDS ARE EXPECTED
TO INCREASE FROM 5 TO 7 MPH THIS EVENING...TO NEARLY 15 TO 20 MPH BY
10Z ACCORDING TO VARIOUS MODEL SOUNDINGS. THIS WIND INCREASE DOES
NOT SUPPORT A DENSE FOG EVENT. HOWEVER...THE LATE ARRIVAL OF THIS
SPEED MAX COULD ALLOW FOG TO FORM IN THE CHANNEL...THEN TRAP IT
BELOW THE INVERSION. ALSO...TRENDS IN THE MODEL SOUNDINGS ARE NOT AS
CONSISTENT...AND SOME PREVIOUS RUNS SHOWED A LIGHTER WIND LAYER. ALL
IN ALL...WHILE THE WIND ISSUE MAY HURT DENSE FOG CHANCES...NOT SOLD
YET THAT IT WILL PRECLUDE DENSE FOG FORMATION. T/TD IS DOWN TO 5 F
AS OF 04Z...WITH SFC WINDS REMAINING LIGHT. BOTH FAVORABLE FOR DENSE
FOG. KLSE TAF WAS UPDATED BEFORE 03Z TO INCLUDE A PERIOD OF
1/4SM...AND WILL CONTINUE THIS. EXPECT RAPID IMPROVEMENT/CLEARING
AROUND 14Z. REST OF THE DAY SHOULD BE VFR...WITH CLOUDS INCREASING
OVERNIGHT FRIDAY...AND THE CHANCE FOR SCT SHRA/TS ON SAT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055-
061.
MN...NONE.
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....ZT/RIECK
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
555 AM MST FRI AUG 23 2013
.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.
&&
.SYNOPSIS...
A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE
IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO
THIS WEEKEND. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH
EARLY NEXT WEEK.
&&
.DISCUSSION...
EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST
AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD
OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA
OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE
STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO
THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL
WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS
MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS
SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL
MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY
IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT
EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING.
TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF
THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS
WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL
AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF
EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL
AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM
THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER.
NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA
PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED
WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN
THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED.
INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS
STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF
PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL
MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG.
LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL.
THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE
REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE
3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE
IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12
G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2
INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE
ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON
SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE
SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW
THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A
PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY
SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE
REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT
RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE
FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING.
UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I
THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE
MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY
WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS
GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND
EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT
WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER
GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY
AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS
ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE
LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
A WEATHER DISTURBANCE OVER WESTERN ARIZONA WILL KEEP CLOUDINESS...AT
OR ABOVE 12 KFT MSL...IN PLACE BETWEEN PHOENIX AND FAR SOUTHEAST
CALIFORNIA THROUGH THE MORNING BEFORE DECREASING THIS AFTERNOON.
SHOWERS WILL BE POSSIBLE IN THAT AREA WITH MORE ACTIVITY OVER
NORTHERN ARIZONA AND SOUTHERN NEVADA. ONCE AGAIN...OUTFLOW WINDS
FROM DISTANT STORMS WILL BE A DISTINCT POSSIBILITY LATER TODAY/THIS
EVENING. THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS AT EACH OF
THE TAF SITES BUT LESS ACTIVITY IS ANTICIPATED OVER THE LOWER
COLORADO RIVER VALLEY AND THE IMPERIAL VALLEY THAN ON THURSDAY.
CONFIDENCE IN STORMS OCCURRING OVER ANY GIVEN TAF SITE TOO LOW TO
REFLECT IN THE TAFS AT THIS POINT. APART FROM THUNDERSTORMS...WINDS
WILL BE LIGHT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1008 AM EDT Fri Aug 23 2013
...LOCALLY HEAVY RAIN AND STORMY WEATHER EXPECTED LATER TODAY...
.NEAR TERM [Rest of Today]...
The large scale longwave pattern is highlighted by a broad ridge
over Cntrl Conus with high over OK, flanked by troughs along the
Pac and Atlc coasts (with base over N GA). Closer to home,
weakening TUTT moving Wwd across w/Cntrl gulf and high just off SE
FL coast. This places local area in a weakness between all these
systems. At surface, high pressure remains in place with ridge from
from high in Atlc east of N FL Wwd to high over FL Panhandle
creating ELY flow. Looking Nwd, frontal boundary extends across
Carolina and extreme Nrn GA. Looking SW, a tropical wave continues
to move Wwd across W/Cntrl gulf. A weak MCV was noted just south of
Pensacola moving Wwd with moist SELY flow in its wake. Latest radar
pix show a fair amount of marine convection moving Nwd.
During the rest of today, Ern mid/upper trough will dig Swd reaching
N FL by tonight. This will displace high Swd and allow front to dip
SWD. With digging trough and local area on back side of MCV,
PWATS will remain above 2 inches. HI RES models like HRRR have a
current good handle on weather which like yesterday shows marine
convection moving Nwd overland by midday and proceeding Nwd reaching
over Nrn tier counties during the mid-late aftn. The mean 1000-700mb
flow will light from the SE so storms that develop will be slow
movers with the potential for very heavy downpours. The combination
of the digging front, approaching surface front and seabreeze-
mesoscale interactions will favor strong to isold severe storms with
damaging wind gusts. Toward sundown, focus will shift towards I-75
corridor and the merging of Gulf and east coast seabreeze. The main
difference from yesterday is that lack of clouds will favor early
diurnal heating with a better destabilization and strong to severe
storms. This reflected in model soundings, i.e. RAP13 19Z TAE with
Cpae 3134 j/kg and 2.20 inch PWAT. Will go with 70-40% S-N POP
gradient. Max temps will once again be held below seasonal levels,
mid 80s south to near 90 NE GA counties.
&&
.SHORT TERM [Tonight through Sunday]...
A backdoor "cold front" will translate slowly southward along the GA
& Northeast FL coast this weekend, though any significant cooling
and/or drying will remain well to our northeast. With ample deep
layer moisture in place through the weekend, persistent, weak Q-G
forcing associated with this front will maintain above-average rain
chances across much of our forecast area, especially during the
daytime hours over land (and overnight & morning hours over the
coastal waters). The above-average cloud cover may help keep high
temperatures a few degrees below climo.
&&
.LONG TERM [Sunday Night through Thursday]...
The long term period begins a bit of unsettled with a stalled
frontal boundary across our southern CWA. Through the day on
Sunday and into Monday deep layer ridging builds over the Plains,
with surface high pressure advancing southwestward through the
southeast US. A significantly drier air mass gets advected around
the surface high pressure reducing PoPs around normal in our
southern zones, and below normal for our northern zones. Any
shower and thunderstorm activity through the period will primarily
be driven by the afternoon sea breeze.
&&
.AVIATION [Through 12Z Saturday]...
VFR conditions are expected into the aftn hours. Scattered to
numerous showers and thunderstorms are expected this afternoon
spreading from the coast rest of this mornnig inland through the
morning and into the afternoon. MVFR CIGS/VSBYS likely in any
stronger storms and heavier rain. Will go with VCTS transitioning
to TSRA ending during the eve from S-N. Then VFR returns until
after 07z-08z with MVFR VSBYS and possibly CIGS except for IFR
CIGS likely at VLD towards sunrise.
&&
.MARINE...
We are going on the assumption (backed by the agreement of the GFS
and ECMWF) that the broad, weak low pressure trough (currently in
the north central Gulf of Mexico) will not intensify significantly,
keeping our local pressure gradient fairly "loose". This means east
winds generally less than 15 KT and seas less than 4 feet.
&&
.FIRE WEATHER...
No fire weather concerns.
&&
.HYDROLOGY...
With Precip Water values continuing above average and Flash Flood
Guidance still below average, we still have to think about any
potential for flash flooding. Fortunately, the Convection Allowing
Models (CAM) consensus doesn`t forecast much in the way of
sustained, organized convection today. So although rainfall rates
could be very high (3-4 inches/hour), the expected lack of
organization makes issuing a watch unnecessary at this time. If
flooding occurs, it would most likely be limited to urban areas
and/or low-lying areas that already have standing water.
Several of our local rivers continued with high flows/stages,
mainly in the lower portions of the basins. Of these, the Chipola
River at Altha, Choctawhatchee River at Bruce, and Ochlockonee
River at Concord and Havana were at moderate flood stage or
higher. Please refer to our web page for details, under the "Rivers
& Lakes" tab.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 88 71 89 71 89 / 70 30 50 30 40
Panama City 85 75 87 76 86 / 70 40 50 30 40
Dothan 87 72 88 72 89 / 50 20 40 30 30
Albany 90 72 91 72 89 / 50 20 40 30 30
Valdosta 89 72 89 70 88 / 60 20 50 30 40
Cross City 88 73 88 72 88 / 70 30 50 30 40
Apalachicola 85 75 86 77 86 / 70 40 50 30 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM/Aviation/Marine...Block
SHORT TERM...Fournier
LONG TERM...Navarro/DVD
FIRE WEATHER...Barry
HYDROLOGY...Fournier
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1128 AM EDT FRI AUG 23 2013
.UPDATE...
HAVE MADE SEVERAL MAINLY MINOR TWEAKS TO GRIDS THIS MORNING...
MAINLY TO UPDATE TRENDS. DID REDUCE POPS FOR THE MORNING AND EARLY
AFTERNOON HOURS BUT EXCEPT FOR SENDING THE NEW GRIDS TO THE WEB...
NO UPDATED PRODUCTS NECESSARY WITH THAT SINCE AFTERNOON POPS
REMAIN THE SAME. AS CONVECTION FIRES...MAY HAVE TO REEVALUATE
LOCATION OF HIGHEST POPS THROUGH THE AFTERNOON BUT FOR THE MOST
PART GRIDS LOOK GOOD. NO UPDATE PLANNED.
TDP
&&
.PREV DISCUSSION... /ISSUED 748 AM EDT FRI AUG 23 2013/
PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/
SHORT TERM /TODAY THROUGH SATURDAY/...
LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING
FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK
RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER
FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT
LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF
THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR
IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG
WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL
OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK
AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD
CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA
INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM
THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW
BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED.
FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT
FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS
AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM
MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY
DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH
PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN
THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000
J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO
FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW
1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO
ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A
COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG
VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA.
OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH
RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA.
ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE
SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS
ENHANCED DEVELOPMENT DURING THE AFTERNOON.
DEESE
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS
SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER
LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM
CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE
LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED
TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY
EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE
INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N
GA.
PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE
SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND
THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP
AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE
MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED.
GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE
EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW
POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS
ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH
THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE
FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY.
BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY.
TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL
DURING THIS PERIOD.
BDL
AVIATION...
12Z UPDATE... FOG CONTINUES TO BUILD OVER CENTRAL GEORGIA AS WELL
AS EXTREME NORTH GEORGIA BUT REMAINING OUTSIDE MOST ATL TERMINALS
AT THIS TIME. WILL HOLD FOR NOW WITH VFR CONDITIONS.
OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS
AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS
POINT.
//ATL CONFIDENCE...12Z UPDATE... HIGH ON ALL ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 91 73 84 67 / 40 40 40 20
ATLANTA 89 75 86 70 / 40 40 40 20
BLAIRSVILLE 86 67 81 65 / 50 50 50 20
CARTERSVILLE 90 72 87 69 / 30 30 40 20
COLUMBUS 90 77 88 72 / 50 50 50 20
GAINESVILLE 88 73 83 69 / 40 40 40 20
MACON 91 74 87 71 / 50 50 50 20
ROME 91 72 87 69 / 40 40 40 20
PEACHTREE CITY 88 72 85 69 / 40 40 40 20
VIDALIA 89 75 88 71 / 50 50 50 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
748 AM EDT FRI AUG 23 2013
.PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/
SHORT TERM /TODAY THROUGH SATURDAY/...
LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING
FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK
RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER
FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT
LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF
THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR
IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG
WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL
OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK
AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD
CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA
INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM
THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW
BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED.
FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT
FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS
AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM
MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY
DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH
PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN
THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000
J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO
FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW
1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO
ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A
COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG
VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA.
OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH
RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA.
ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE
SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS
ENHANCED DEVELOPMENT DURING THE AFTERNOON.
DEESE
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS
SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER
LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM
CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE
LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED
TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY
EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE
INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N
GA.
PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE
SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND
THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP
AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE
MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED.
GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE
EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW
POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS
ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH
THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE
FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY.
BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY.
TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL
DURING THIS PERIOD.
BDL
.AVIATION...
12Z UPDATE... FOG CONTINUES TO BUILD OVER CENTRAL GEORGIA AS WELL
AS EXTREME NORTH GEORGIA BUT REMAINING OUTSIDE MOST ATL TERMINALS
AT THIS TIME. WILL HOLD FOR NOW WITH VFR CONDITIONS.
OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS
AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS
POINT.
//ATL CONFIDENCE...12Z UPDATE... HIGH ON ALL ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 91 73 84 67 / 40 40 40 20
ATLANTA 89 75 86 70 / 40 40 40 20
BLAIRSVILLE 86 67 81 65 / 50 50 50 20
CARTERSVILLE 90 72 87 69 / 30 30 40 20
COLUMBUS 90 77 88 72 / 50 50 50 20
GAINESVILLE 88 73 83 69 / 40 40 40 20
MACON 91 74 87 71 / 50 50 50 20
ROME 91 72 87 69 / 40 40 40 20
PEACHTREE CITY 88 72 85 69 / 40 40 40 20
VIDALIA 89 75 88 71 / 50 50 50 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
Area Forecast Discussion
National Weather Service Lincoln IL
950 AM CDT Fri Aug 23 2013
.DISCUSSION...
ISSUED 949 AM CDT Fri Aug 23 2013
Areas of dense fog north of I-74 has been lifting into a stratus
deck this morning, and should continue to thin from the edges over
the next couple hours as diurnal mixing increases. Otherwise, high
pressure north of Lake Superior will bring a 5-10 mph northeast
wind flow to the region causing dewpoints will gradually fall into
the low/mid 60s from north to south by late afternoon. Subsidence
on the south side of the ridge should provide mostly sunny skies
and seasonable highs in the mid 80s.
25
&&
.AVIATION...
ISSUED 657 AM CDT Fri Aug 23 2013
Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
Patchy fog/stratus may briefly cause MVFR/IFR conditions for a
couple hours this morning, but otherwise cloud cover should be
minimal. While light fog can not be ruled out overnight tonight,
the drier air filtering into the area around the south side of a
an area high pressure should keep the risk to a minimum.
Bak
&&
.PREV DISCUSSION...
ISSUED 240 AM CDT Fri Aug 23 2013
SHORT TERM...Today through Saturday...
Initial frontal passage has taken place over all of central and
southeast Illinois early this morning, but drier air lingers a bit
further back as lower 60s dew points now starting to enter the far
northern CWA. A cluster of thunderstorms developed from
Springfield to Decatur along the remnants of an old boundary from
earlier, in an area with MUCAPE`s of around 1000 J/kg, and the
cluster has been increasing a bit over the last hour or so as it
moves south-southeast. Latest model guidance suggesting scattered
showers/storms through about mid morning over about the southeast
third of the forecast area.
Further north, fog has been thickening and increasing over the
northeast third of the state, where skies have cleared and the
drier air has arrived. So far visibilities in our area have been
staying up as a band of altocumulus has persisted, but clearing
has been taking place from Galesburg to Lacon. However, the lower
visibilities have been in areas that had quite a bit of rain on
Thursday, and much of our forecast area had a quarter inch or less
except in isolated spots. So, the question is how much of the
forecast area, if any, will see dense fog this morning. HRRR
guidance is the most pessimistic with it fairly widespread along
and north of I-74, while the most recent RAP has scaled back and
went mainly patchy dense fog in the same area. Currently have
mention of 1/2 mile visibility in fog in this area through about 9
am, but will have to monitor for any significant advection from
the northeast.
Once the fog and rain moves out, quiet weather expected through
the first part of the weekend. High pressure drifting through the
Great Lakes will advect some drier air in from the east, but
should still see highs in the mid-upper 80s.
LONG TERM...Sunday through Thursday...
Main weather story over the coming week continues to be with the
expanding heat over the center of the nation, as a large dome of
high pressure aloft drifts eastward. Any MCS ridge riders will be
well to our north, and will continue the dry forecast for next
week. Highs to rise through the 90s much of the week as thermal
ridge builds eastward. Core of this ridge will be in the area on
Wednesday. Latest ECMWF showing upper 90s over most of the
forecast area that day. Have continued to trend temperatures up a
degree or two from blended guidance with mid 90s widespread on
Wednesday. Heat index values of just over 100 likely across the
western CWA Monday-Tuesday and everywhere Wednesday. On Thursday,
the thermal ridge starts shifting westward again, but should still
see highs in the 93-95 range.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
913 AM CDT FRI AUG 23 2013
.DISCUSSION...
352 AM CDT
SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE
GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH
HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE.
TODAY...
HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT
CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES
OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED
IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE
EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG
DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO
BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH
HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS
WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN
THE UPPER 70S TO AROUND 80.
REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE
BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG
THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE
MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE
COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL
THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY
TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM
THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM.
SATURDAY THROUGH MONDAY...
THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO
SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL
PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH
PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT
INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE
SOUTHEAST ATLANTIC COAST MONDAY NIGHT.
MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE
RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT.
ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE
NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS
DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH
AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST.
HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT
CWA.
UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON
MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY
REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE
DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING.
THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT
INDICES IN THE UPPER 90S TO AROUND 100.
LONG TERM...TUESDAY THROUGH THURSDAY...
THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A
BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION.
GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK
AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL
EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND
EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH
TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING
IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL
TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON
WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT.
A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY
INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED.
TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER
CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* NE/ENE WINDS AROUND 10 KT LATE THIS MORNING THEN SPEEDS MAY
INCREASE TO 12-14KT BY EARLY THIS AFTERNOON.
BEACHLER
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE UPPER
MISSISSIPPI VALLEY. DRIER AIR OOZING IN FROM THIS HAS HELPED TO
ABATE THE FOG ACROSS MOST OF THE TAF SITES EARLY THIS MORNING.
SOME STRATUS ACROSS GYY AND JUST SOUTH OF MDW SHOULD QUICKLY TURN
INTO A CU FIELD THIS MORNING. THE HIGH WILL TRANSLATE SLOWLY EAST
THROUGH THE TAF PERIOD. WINDS WILL PICK UP DURING THE MID TO LATE
MORNING WITH THE VAD WIND PROFILE INDICATING 10-15KT WITHIN 2000
FT OF THE SURFACE. THE WINDS WILL BE OFF THE LAKE AS WELL...AND
CLIMATOLOGY POINTS TO THE DIRECTION BEING CLOSER TO ENE OR EVEN E
BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY COME THIS EVE. FOG
WILL BE LESS OF A THREAT TONIGHT DUE TO DRYING IN THE LOW-
LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE
AREAS THAT SAW MORE OF AN APPRECIABLE RAIN DURING THURSDAY /LIKE
RFD/.
MTF
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE THAT BROKEN STRATUS WILL STAY JUST SOUTH OF
MDW.
* MEDIUM CONFIDENCE IN WIND SPEEDS STAY AOB 10KT TODAY.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT-MONDAY...VFR.
TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF
STORMS WED NIGHT.
THURSDAY...VFR.
MTF
&&
.MARINE...
306 AM CDT
HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO
NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS
OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL
STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS.
THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED
SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON
SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES
LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF
THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON
NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS
LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE
MIDWEEK PERIOD.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ014 UNTIL 7 PM FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001 UNTIL 7 PM FRIDAY.
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
National Weather Service Lincoln IL
657 AM CDT Fri Aug 23 2013
.DISCUSSION...
ISSUED 240 AM CDT Fri Aug 23 2013
SHORT TERM...Today through Saturday...
Initial frontal passage has taken place over all of central and
southeast Illinois early this morning, but drier air lingers a bit
further back as lower 60s dew points now starting to enter the far
northern CWA. A cluster of thunderstorms developed from
Springfield to Decatur along the remnants of an old boundary from
earlier, in an area with MUCAPE`s of around 1000 J/kg, and the
cluster has been increasing a bit over the last hour or so as it
moves south-southeast. Latest model guidance suggesting scattered
showers/storms through about mid morning over about the southeast
third of the forecast area.
Further north, fog has been thickening and increasing over the
northeast third of the state, where skies have cleared and the
drier air has arrived. So far visibilities in our area have been
staying up as a band of altocumulus has persisted, but clearing
has been taking place from Galesburg to Lacon. However, the lower
visibilities have been in areas that had quite a bit of rain on
Thursday, and much of our forecast area had a quarter inch or less
except in isolated spots. So, the question is how much of the
forecast area, if any, will see dense fog this morning. HRRR
guidance is the most pessimistic with it fairly widespread along
and north of I-74, while the most recent RAP has scaled back and
went mainly patchy dense fog in the same area. Currently have
mention of 1/2 mile visibility in fog in this area through about 9
am, but will have to monitor for any significant advection from
the northeast.
Once the fog and rain moves out, quiet weather expected through
the first part of the weekend. High pressure drifting through the
Great Lakes will advect some drier air in from the east, but
should still see highs in the mid-upper 80s.
LONG TERM...Sunday through Thursday...
Main weather story over the coming week continues to be with the
expanding heat over the center of the nation, as a large dome of
high pressure aloft drifts eastward. Any MCS ridge riders will be
well to our north, and will continue the dry forecast for next
week. Highs to rise through the 90s much of the week as thermal
ridge builds eastward. Core of this ridge will be in the area on
Wednesday. Latest ECMWF showing upper 90s over most of the
forecast area that day. Have continued to trend temperatures up a
degree or two from blended guidance with mid 90s widespread on
Wednesday. Heat index values of just over 100 likely across the
western CWA Monday-Tuesday and everywhere Wednesday. On Thursday,
the thermal ridge starts shifting westward again, but should still
see highs in the 93-95 range.
Geelhart
&&
.AVIATION...
ISSUED 657 AM CDT Fri Aug 23 2013
Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
Patchy fog/stratus may briefly cause MVFR/IFR conditions for a
couple hours this morning, but otherwise cloud cover should be
minimal. While light fog can not be ruled out overnight tonight,
the drier air filtering into the area around the south side of a
an area high pressure should keep the risk to a minimum.
Bak
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1008 AM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 1003 AM CDT FRI AUG 23 2013
THE FOG HAS BURNED OFF AND THE LOW CLOUDS WILL CONTINUE LIFT
THROUGH EARLY AFTERNOON.
RAIN CHANCES DO NOT LOOK OVERLY GREAT FOR THE AFTERNOON HOURS. THE
BETTER MOISTURE LIES JUST WEST OF THE CWFA AS DOES THE PROJECTED
CONVERGENCE. THE EARLY MORNING FOG HAS ALSO STABILIZED THE WESTERN
CWFA SO IT WILL TAKE LONGER TO GENERATE THERMALS. WHAT IS BEING
SUGGESTED BY THE MODELS IS ISOLATED TO PERHAPS VERY LOW END
SCATTERED SHOWERS AND SOME STORMS IN THE EXTREME WESTERN/SOUTHWEST
PARTS OF THE CWFA DURING PEAK HEATING. IF THIS CONVECTION
DEVELOPS...IT WILL DISSIPATE WITH SUNSET. ..08..
&&
.SYNOPSIS...
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN
THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST.
AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN
ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED
ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20
CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE
1+ INCHES OF RAIN FELL YESTERDAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED
DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED
IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING
OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG
AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON.
ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN
WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA
OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA
THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE
RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE
STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA
THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS
IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR
AREA THIS AFTERNOON.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED
PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK.
THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY...
WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH
THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL
LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF
PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE
THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS
AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE
CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S.
SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE
AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK.
OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER
HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS
TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR
NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE
SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24
C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S.
SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES
SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES
TOPPING OUT IN THE UPPER 80S TO AROUND 90.
MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE
THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE
FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND
POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL
KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH
THU.
HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH
ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU.
THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS...
WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE
MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY
SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR
EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL
CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED
FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 627 AM CDT FRI AUG 23 2013
PATCHY DENSE FOG IS AFFECTING AREA TAF SITES THIS MORNING WITH
MOST EXPERIENCING IFR OR LIFR CONDITIONS. FOG WILL LIFT RAPIDLY WITHIN THE
NEXT 2 HOURS AS THE RISING SUN BEGINS TO PERCOLATE THE BOUNDARY
LAYER. ONCE THE FOG LIFTS...EXPECT VFR CONDITIONS WITH SCATTERED
AFTERNOON CUMULUS ABOVE 3000FT. OTHERWISE...LIGHT SURFACE WINDS
WILL SHIFT TO THE EAST THEN SOUTHEAST THROUGH THE DAY AS THE
SURFACE HIGH PRESSURE RIDGE SLIDES EASTWARD ACROSS THE GREAT LAKES.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...SHEETS
AVIATION...DMD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
641 AM CDT FRI AUG 23 2013
.SYNOPSIS...
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN
THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST.
AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN
ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED
ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20
CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE
1+ INCHES OF RAIN FELL YESTERDAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED
DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED
IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING
OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG
AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON.
ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN
WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA
OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA
THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE
RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE
STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA
THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS
IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR
AREA THIS AFTERNOON.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED
PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK.
THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY...
WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH
THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL
LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF
PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE
THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS
AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE
CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S.
SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE
AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK.
OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER
HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS
TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR
NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE
SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24
C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S.
SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES
SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES
TOPPING OUT IN THE UPPER 80S TO AROUND 90.
MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE
THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE
FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND
POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL
KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH
THU.
HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH
ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU.
THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS...
WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE
MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY
SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR
EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL
CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED
FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 627 AM CDT FRI AUG 23 2013
PATCHY DENSE FOG IS AFFECTING AREA TAF SITES THIS MORNING WITH
MOST EXPERIENCING IFR OR LIFR CONDITIONS. FOG WILL LIFT RAPIDLY WITHIN THE
NEXT 2 HOURS AS THE RISING SUN BEGINS TO PERCOLATE THE BOUNDARY
LAYER. ONCE THE FOG LIFTS...EXPECT VFR CONDITIONS WITH SCATTERED
AFTERNOON CUMULUS ABOVE 3000FT. OTHERWISE...LIGHT SURFACE WINDS
WILL SHIFT TO THE EAST THEN SOUTHEAST THROUGH THE DAY AS THE
SURFACE HIGH PRESSURE RIDGE SLIDES EASTWARD ACROSS THE GREAT LAKES.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BENTON-
BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES-LINN-
SCOTT.
IL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUREAU-
CARROLL-HENRY IL-JO DAVIESS-PUTNAM-ROCK ISLAND-STEPHENSON-
WHITESIDE.
MO...NONE.
&&
$$
SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...SHEETS
AVIATION...DMD
AREA FORECAST DISCUSSION
NWS GOODLAND KS
605 AM MDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 559 AM MDT FRI AUG 23 2013
JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE
OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT
CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE
SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT
CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS
TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST
HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER
SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL
STAY CONSERVATIVE WITH THIS UPDATE.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 251 AM MDT FRI AUG 23 2013
LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER
THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED
FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO
THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY
THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH
GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM
LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT
HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS
NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA.
WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS
INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD
AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY
NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT
RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER
IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF
OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS.
OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE
HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH
VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG
DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE
INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS
BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS
NORTHERN PART OF CWA THIS MORNING.
AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH
SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE
OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH
WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS
EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR
CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE
UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS
FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON
AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG
CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT
WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT
WE WILL NEED TO MONITOR.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 251 AM MDT FRI AUG 23 2013
WHILE THE PAST FEW EXTENDED RANGE FORECASTS HAVE SOUNDED LIKE A
BROKEN RECORD - HOT AND DRY - IT APPEARS AN END IS IN SIGHT. EARLY
NEXT WEEK AN UPPER LEVEL RIDGE WILL BE CENTERED OVER KANSAS...WITH A
A NORTH-SOUTH ORIENTED SURFACE TROUGH DEVELOP ALONG EASTERN
COLORADO. THE ECMWF HAD PREVIOUSLY BEEN A BIT MORE CONSERVATIVE WITH
TEMPS BUT NOW HAS COME AROUND TO BETTER MATCH THE GFS AND GEM WITH
TEMPS IN THE LOW 30S C...TRANSLATING TO MID TO UPPER 90S IN THE
FIRST HALF OF THE WEEK. TRIPLE-DIGIT TEMPS LOOK ALMOST LIKELY ON
MONDAY AND TUESDAY FOR THE NORMAL HOT SPOTS...PLACES LIKE
TRIBUNE...HILL CITY...AND MCCOOK...APPROACHING /BUT PROBABLY NOT
EXCEEDING/ RECORDS IN SOME SPOTS. LATER IN THE WEEK THE RIDGE WILL
SLOWLY NUDGE FARTHER EAST BRINGING RELIEF TO THE HEAT...SOMETHING
THE OPERATIONAL GFS IS A BIT SLOW TO REALIZE BUT THE GEFS MEAN AND
ECMWF HAVE BEEN CONSISTENT WITH THE PAST FEW RUNS. PRECIP CHANCES
ARE NEAR NIL WITH THE RIDGE OVER US...BUT AS IT MOVES EAST WE COULD
SEE CHANCES INCREASE TOWARDS THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 529 AM MDT FRI AUG 23 2013
SHOWERS/THUNDERSTORMS WILL LINGER WITHIN VICINITY OF KMCK
TERMINAL THROUGH MID MORNING BEFORE ACTIVITY DISSIPATES OR SHIFTS
NORTH/EAST. CANT COMPLETELY RULE OUT ADDITIONAL ACTIVITY
REDEVELOPING LATER TODAY WITH SMALL SCALE LOW IN EASTERN
COLORADO...HOWEVER WILL HOLD THIS OUT OF TAFS FOR NOW. OTHER
AVIATION CONCERN THIS MORNING WITH BE PATCHY FOG. MVFR CIGS HAVE
BEEN REPORTED AT TIMES AT KMCK...THOUGH WITH PRECIP IN VICINITY
AND WINDS SHIFTING TO THE SOUTH I DONT THINK THIS WILL PREVAIL.
KGLD SHOULD REMAIN WITHIN VFR...THOUGH WITH BETTER CHANCE TO SEE
CLEARING SKIES AROUND SUNRISE I DONT WANT TO COMPLETELY RULE OUT
MVFR VIS DEVELOPING FOR A SHORT PERIOD THIS MORNING. WILL LEAVE
TEMPO IN PLACE AT KMCK FOR NOW...AND KEEP KGLD AT 6SM. BEYOND THIS
MORNING VFR CONDITIONS SHOULD PREVAIL. LIGHTS WINDS WILL BEGIN TO
INCREASE OUT OF THE THE SOUTH THIS AFTERNOON WITH LEE TROUGH
DEVELOPMENT...WITH SUSTAINED WINDS GENERALLY AROUND 13-15KT...AND
OCCASIONAL GUSTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...DR
LONG TERM...JJM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS TOPEKA KS
623 AM CDT Fri Aug 23 2013
.SHORT TERM...(Today and Tonight)
Issued at 335 AM CDT FRI AUG 23 2013
A broad upper level ridge of high pressure will be centered over the
state of Kansas for the next 24 hours.
early this morning, elevated showers were developing due to weak
isentropic lift north of an old outflow boundary across west central
KS. At this time I think the showers should remain just west of the
cwa...though some isolated showers may develop near sunrise across
the southwest and northern counties of the CWA, but should dissipate
by mid morning. May place a 10 to 14 pop across the southwest and
northern counties in case any isolated showers develop.
Widespread convection along the foothills of CO will cause periods
of high clouds to move across the CWA Today. The 06Z NAM is the only
numerical model that breaks out deep moist convection across north
central KS late this afternoon and into the early evening hours. The
NAM may be trying to bring the MCV from the CO foothill convective
complex too far south across the center of the H5 ridge axis. The
GFS, arw, nmm and RAP show the the mcv rotating farther northeast
across western and central NE and show no qpf developing across
north central KS this afternoon. Just in case the NAM solution may
be accurate I inserted 10 to 14 pops for late this afternoon and
early evening across the northwest counties of the CWA.
High temperatures Today may be dependent on the amount of high
clouds. if the high clouds thin out this afternoon then highs will
reach into the lower to mid 90s. If we keep a thicker veil of high
clouds through the afternoon hours, then highs may only reach the
upper 80s to around 90.
Tonight, if any showers or isolated thunderstorms develop across
north central KS they should dissipate after sunset. skies should
become mostly clear through the night. overnight lows will drop into
the upper 60s to lower 70s.
.LONG TERM...(Saturday through Thursday)
Issued at 335 AM CDT FRI AUG 23 2013
Medium range models are very similar in building upper ridge
eastward through the weekend with axis over MO before retrogressing
slightly and amplifying across KS through most of next week. This
will allow for only weak inhibition by peak heating over the
weekend...but a strengthening cap into next week. However with the
exception of diurnal heating...no significant forcing evident to
warrant any pops at this point...and even less confidence into next
week. Therefore will keep the fcst through the extended dry. The
llvl thermal fields only warm slightly from the weekend into the
middle of next week...so the current fcst of only minor high temp
increases thru the middle 90s into next week looks good for now.
There is some concern that soil conditions steadily drying out and
some hint of more veering llvl windfields by the middle of next week
could lead to higher temps in the western cwa. A slight increase in
dewpoints into next week with the slightly warmer temps should inch
heat indices to around the century mark for most areas through next
week.
&&
.AVIATION...(For the 12Z TAFs through 12Z Saturday Morning)
Issued at 619 AM CDT FRI AUG 23 2013
Expect VFR conditions for the next 24 hours at the TAF sites. The mid
level clouds should prevent widespread ground fog at both KMHK and
KTOP this morning. FEW to SCT CU will develop this afternoon and
should dissipate after sunset. FEW-SCT mid and high clouds
Tonight.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...Gargan
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
932 AM CDT FRI AUG 23 2013
.DISCUSSION...
UPDATED GRIDS THIS MORNING FOR ONGOING VERY ISOLATED SHOWERS.
INCREASED THE DURATION FOR THE REST OF THE MORNING AS SHOWERS ARE
HANGING IN THERE. RAP INDICATES BOTH MID-LEVEL LAPSE RATES AND
MUCAPE ARE RATHER LIMITED ACROSS THE AREA...AND WITH NO LIGHTNING
YET IN THIS ACTIVITY...HAVE REMOVED THUNDER MENTION FOR TODAY.
ALSO INCREASED SKY COVER WITH BROKEN TO OVERCAST SKIES OVER MOST
OF THE CWA. CHANCE OF SHOWERS...WITH MAYBE AN ISOLATED RUMBLE OF
THUNDER...DOES RETURN TONIGHT AS THE LOW-LEVEL JET PICKS UP...MOST
LIKELY TO THE NORTHERN CWA...BUT LIKELY WILL BE A BREAK BETWEEN
THE ONGOING SHOWERS AND THE OVERNIGHT ACTIVITY.
MAYES
&&
.PREV DISCUSSION... /ISSUED 632 AM CDT FRI AUG 23 2013/
AVIATION...12Z TAFS FOR KOFK...KOMA AND KLNK.
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE TAF CYCLE. A FEW
ISOLATED SHOWERS ARE FLOATING AROUND THE AREA THIS MORNING BUT
SHOULD REMAIN ISOLATED ENOUGH TO LEAVE A MENTION OUT OF THE TAFS.
EXPECT MORE SCATTERED ACTIVITY TO DEVELOP TOWARD THE END OF THE
TAF CYCLE SATURDAY MORNING...BUT DUE TO LACK OF COVERAGE...WILL
KEEP OUT OF THIS SET OF TAFS.
KERN
PREV DISCUSSION... /ISSUED 349 AM CDT FRI AUG 23 2013/
DISCUSSION...
STRONG UPPER LEVEL RIDGING WILL DOMINATE THE WEATHER PATTERN FOR
NEXT SEVERAL DAYS. THIS WILL KEEP PRECIPITATION CHANCES MEAGER AND
TEMPERATURES SOME 8 TO 10 DEGREES ABOVE NORMAL.
TODAY AND TONIGHT...THE MAIN FORECAST CONCERN FOR THIS PERIOD WILL
BE THE CHANCE FOR PRECIPITATION THIS MORNING AND AGAIN TONIGHT.
THE LATEST 88D SCANS SHOW SOME LIGHT SHOWERS ARE DEVELOPING ALONG
THE SOUTHEAST NEBRASKA/KANSAS BORDER. THESE SHOWERS SHOULDN`T
AMOUNT TO MUCH AND ARE FORCED BY WEAK WARM AIR ADVECTION ALOFT.
DECIDED TO MAINTAIN SLIGHT CHANCE POPS THROUGH MID MORNING TO
ACCOUNT FOR THIS. FOR TONIGHT...A STRENGTHENING LOW LEVEL JET AND
850MB FRONT WILL ACT TO GENERATE PRECIPITATION ACROSS MUCH OF
EASTERN SOUTH DAKOTA...WHICH MAY BRUSH THE NORTHERN HALF OF THE
COUNTY WARNING AREA.
SATURDAY ONWARD...SOME COMPUTER MODELS WANT TO MAINTAIN SOME OF
THE OVERNIGHT PRECIPITATION INTO WESTERN IOWA ON SATURDAY
MORNING. IT DOESN`T APPEAR THERE IS MUCH FORCING TO SUPPORT THIS.
IN FACT 500MB HEIGHTS ARE ON THE RISE...SO WENT WITH A DRY
FORECAST FROM SATURDAY ONWARD. TEMPERATURES WILL REMAIN WARM...LOW
TO MID 90S...THROUGH THE REST OF THE FORECAST. WITH DEW POINTS
REMAINING STEADY IN THE MID TO UPPER 60S APPARENT TEMPERATURES
WILL PUSH 100...WHICH IS BELOW HEAT ADVISORY CRITERIA.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS HASTINGS NE
546 AM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 539 AM CDT FRI AUG 23 2013
LATEST HRRR AND 06Z GFS ARE COMING IN WETTER TODAY...WHICH IS ALSO
BEING BACKED UP BY RADAR TRENDS THAT SHOW INCREASING CONVECTIVE
ACTIVITY ACROSS PORTIONS OF OUR FORECAST AREA. SHOWERS AND
THUNDERSTORMS REMAIN FAIRLY ISOLATED...BUT MAY LINGER LONGER THIS
MORNING THAN ORIGINALLY ANTICIPATED. IN ADDITION...THESE LATEST
MODEL RUNS ARE MORE BULLISH ON SEEING AFTERNOON REDEVELOPMENT AND
THUS WE MAY NEED TO EVENTUALLY INCLUDE POPS FOR THIS AFTERNOON IF
12Z MODEL RUNS CONTINUE TO TREND TOWARDS NEEDING PRECIPITATION
CHANCES.
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT FRI AUG 23 2013
THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL
CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY
ACROSS NORTH CENTRAL KANSAS.
THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS
MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN
ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN
KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS
HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF
THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES
DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE
SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN
TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET
GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND
SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS
RATHER MARGINAL.
THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS
DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY
TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN
ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS
NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE
POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST
AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING
INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN
ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE
THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE
STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY
A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON.
HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE
SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL
LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH
CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND
WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO
THE 90S ACROSS KANSAS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 334 AM CDT FRI AUG 23 2013
PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH
TEMPERATURES.
MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST
PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS
INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE
PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST.
THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR
ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF
THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT
CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY
FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK
WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL
DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST
COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER
THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY
DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL
CAPPED.
AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS
THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH
PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS
TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT
EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE
20 TO 25 MPH RANGE WITH HIGHER GUSTS.
AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS
INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE
IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT
COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN
SWRN LOCATION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 516 AM CDT FRI AUG 23 2013
THE MAIN THING TO WATCH OUT FOR TODAY WILL BE THE
DEVELOPING SHOWERS AND ISOLATED THUNDERSTORMS. LATEST 06Z GFS AND
MOST RECENT HRRR MODEL RUN ARE BOTH MORE AGGRESSIVE WITH
GETTING PRECIPITATION TODAY. WILL CONTINUE TO LEAVE THUNDER AND
PRECIPITATION OUT OF THE TAF FOR NOW...BUT THE TAF MAY NEED TO BE
AMENDED DEPENDING ON RADAR TRENDS AND WHERE THESE ISOLATED
THUNDERSTORMS DEVELOP. THE WIND WILL REMAIN OUT OF THE SOUTHEAST
TODAY AND THEN BECOME MORE SOUTHERLY LATE TONIGHT. EXPECT A
SCATTERED TO BROKEN MID DECK OF CLOUDS THROUGH THE MORNING AND
POSSIBLY THROUGH MUCH OF THE DAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...WESELY
SHORT TERM...WESELY
LONG TERM...ADO
AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
953 AM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 937 AM CDT FRI AUG 23 2013
WARM H500 RIDGE REMAINS OVER THE NORTHERN PLAINS TODAY. WITHIN THE
RIDGE THERE IS A WEAK VORT LOBE MOVING THROUGH WHICH...AIDED BY THE
DIURNAL LOW LEVEL JET...(30 KTS ON 12Z KBIS SOUNDING) SPONSORING
SOME WEAK CONVECTION CROSS THE SOUTH CENTRAL THIS MORNING.
CONVECTION EXPECTED TO DIMINISH AS THE LOW LEVEL FEATURES MIX OUT
THIS AM. THEN SYNOPTIC SCALE FORCING WILL PREVAIL THIS AFTERNOON
AND EVENING AS WARM FRONT IN EASTERN MONTANA MOVES EAST. THE WARM
FRONT WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS SOUTHWEST AND
WEST CENTRAL THIS AFTERNOON/EVENING. MADE SOME CHANGES TO CLOUDS
AND POPS THIS AM TO FOCUS ON THE ON GONG CONVECTION. OTHERWISE NO
OTHER CHANGES.
UPDATE ISSUED AT 643 AM CDT FRI AUG 23 2013
WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED
SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA.
HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS
NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER
EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED
OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT
FORECAST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM
POTENTIAL AND AREAL COVERAGE.
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER
SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW
PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL
SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND
HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR
CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE
NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN
SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE
LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT
FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE
ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT
APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE
CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR
AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH
INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN
SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS
TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON
INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE
TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH
FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH
CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST
INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN
CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN
NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG
WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S.
FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS
AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE
IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND
INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN
THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT
CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC
THUNDERSTORM CHANCES.
THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH
FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN
TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S
TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH
SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS
THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON
HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY
ACROSS THE SOUTH.
EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING
SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE
WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA.
THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD.
MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY
NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS
THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC
SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE
WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL
LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY.
THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN
THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE.
THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS
THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE
ENERGY CONTINUING TO TRAVERSE THE AREA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 937 AM CDT FRI AUG 23 2013
AT 9 AM CDT...WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WERE ACROSS
SOUTH CENTRAL NORTH DAKOTA IMPACTING KBIS. THUNDERSTORM HAZARD
WILL BE TREATED WITH A VCTS (VICINITY) FORECAST FOR THUNDERSTORMS
THROUGH 17Z. OTHERWISE...A WARM FRONT IN EASTERN MONTANA WILL MOVE
SLOWLY EAST THIS AFTERNOON AND TONIGHT, THE WARM FRONT WILL BE THE
FOCUS FOR SCATTERED TO WIDELY SCATTERED THUNDERSTORMS THIS
AFTERNOON AND NIGHT AT KISN-KDIK-KBIS-KJMS. DUE TO UNCERTAINTY WILL
KEEP THE VCTS FOR THIS SITES. VFR AT ALL TAF SITES.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...KS
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
643 AM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 643 AM CDT FRI AUG 23 2013
WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED
SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA.
HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS
NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER
EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED
OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT
FORECAST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM
POTENTIAL AND AREAL COVERAGE.
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER
SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW
PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL
SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND
HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR
CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE
NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN
SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE
LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT
FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE
ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT
APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE
CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR
AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH
INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN
SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS
TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON
INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE
TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH
FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH
CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST
INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN
CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN
NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG
WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S.
FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS
AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE
IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND
INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN
THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT
CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC
THUNDERSTORM CHANCES.
THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH
FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN
TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S
TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH
SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS
THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON
HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY
ACROSS THE SOUTH.
EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING
SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE
WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA.
THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD.
MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY
NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS
THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC
SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE
WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL
LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY.
THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN
THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE.
THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS
THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE
ENERGY CONTINUING TO TRAVERSE THE AREA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 643 AM CDT FRI AUG 23 2013
THE LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW SCT/BKN
LOW VFR CIGS AT KBIS/KJMS WITH MID/HIGH LEVEL CLOUDS ELSEWHERE.
LOCAL RADAR WAS INDICATING A LINE OF VERY LIGHT SHOWERS APPROACHING
KBIS AND THIS MIGHT MAKE IT INTO KJMS BY MID TO LATE
MORNING...OTHERWISE EXPECT SCT/BKN VFR CIGS WITH A CHANCE FOR
SHOWERS AND THUNDERSTORMS THROUGH THE TAF PERIOD. UNCERTAINTY
CONTINUES IN REGARDS TO WHERE THE THUNDERSTORMS WILL INITIATE AND
THEIR AREAL COVERAGE. THUS HAVE MAINTAINED A VCTS AT THOSE
AERODROMES FROM THE PREVIOUS TAF ISSUANCE...AND WILL CONTINUE TO
MONITOR FOR THUNDERSTORM DEVELOPMENT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS TULSA OK
907 AM CDT FRI AUG 23 2013
.DISCUSSION...
UPPER AIR DATA AT 12Z SHOWS COOLER AND MORE MOIST CONDITIONS IN
THE MID LVLS COMPARED TO 24 HRS AGO...FROM 700MB UP TO 500MB. IN
THE LATE NIGHT AND EARLY MORNING...THIS MID LVL MOISTURE CREATES
SOME INSTABILITY DUE TO NOCTURNAL COOLING ABOVE THIS MOIST LAYER.
THIS HAS PRODUCED A FEW HIGH BASED SHOWERS AND A LIGHTNING STRIKE
OR TWO OVER EASTERN OKLAHOMA. HOWEVER...AS THE DAY CONTINUES THIS
MID LEVEL INSTABILITY WANES AND THUS THE SHOWERS SHOULD DISSIPATE
BY MIDDAY AS THE HRRR AND LOCAL WRF MODEL SUGGEST. GRIDS HAVE BEEN
UPDATED TO ACCOUNT FOR THE SMALL AREA OF PRECIP DOWN OVER EAST
CENTRAL OKLAHOMA.
LACY
&&
.PREV DISCUSSION... /ISSUED 709 AM CDT FRI AUG 23 2013/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
PATCHY FOG AT TAF SITES KBVO/KXNA/KFYV TO MIX AWAY BY 15Z.
VFR ALL SITES UNTIL PATCHY FOG RETURNS AGAIN LATE TONIGHT
GENERALLY AFTER 06Z WITH POTENTIAL VISIBILITY BELOW 3 MILES
KFYV/KXNA.
PREV DISCUSSION... /ISSUED 339 AM CDT FRI AUG 23 2013/
DISCUSSION...
A STRONG RIDGE OF HIGH PRESSURE ALOFT WILL REMAIN OVER THE AREA
THROUGH THE ENTIRE FORECAST PERIOD. THIS WILL LEAD TO AN EXTENDED
STRETCH OF HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN. AN
ISOLATED SHOWER OR THUNDERSTORM WILL BE POSSIBLE THE NEXT FEW
AFTERNOONS...MAINLY OVER THE HIGHER TERRAIN AREAS...BUT AREAL
COVERAGE WILL BE MUCH TOO LOW TO MENTION IN THE FORECAST.
AFTERNOON TEMPERATURES MAY INCH UP A BIT NEXT WEEK AS LOW LEVEL
WINDS LOSE THE EASTERLY COMPONENT THAT WILL BE PRESENT THE NEXT
FEW DAYS.
STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 94 73 94 74 / 10 0 10 0
FSM 95 73 95 74 / 10 0 10 0
MLC 95 72 95 73 / 10 10 10 10
BVO 93 69 93 70 / 10 0 10 0
FYV 91 67 91 68 / 10 0 10 0
BYV 91 69 91 70 / 10 0 10 0
MKO 94 71 94 72 / 10 0 10 0
MIO 92 70 92 71 / 10 0 10 0
F10 95 71 95 72 / 30 10 10 10
HHW 96 73 96 74 / 10 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...30
AREA FORECAST DISCUSSION
NWS SPOKANE WA
815 AM PDT Fri Aug 23 2013
.SYNOPSIS...
A potent storm system will bring scattered showers and
thunderstorms through the region today. Unsettled conditions will
continue across the Inland Northwest over the weekend and majority
of next week as a moist southwest flow pattern remains in place.
&&
.DISCUSSION...
Update to the forecast to increase the chances of showers and
thunderstorms. Upper low is currently spinning over our area and
will eject northward through the day. Shower and thunderstorm
coverage will gradually advance northward through the day as well,
with clearing skies moving up from Oregon later this afternoon.
I will be looking at the potential for stronger thunderstorms this
afternoon. Right now the HRRR does show moderately strong storms
this afternoon over the north. But the extensive cloud cover would
likely limit heating, so that HRRR idea may be overdone. Will
address this issue in another hour or 2. RJ
&&
.AVIATION...
12Z TAFS: Scattered showers and embedded thunderstorms will
continue to expand across central and eastern WA and north ID
this morning as an upper shortwave trof tracks northeast from
the Cascades. Primarily VFR conditions are expected, though brief
MVFR conditions and gusty winds are possible in heavy
showers/storms. As morning transitions to afternoon the
showers/thunderstorm threat is expected to translate northward,
with the west and southern TAF sites drying out and eventually all
TAF sites dry out by late afternoon. However look for breezy
conditions, with occasional gusts to 20kts. Winds abate in the
00-06Z time frame. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 81 58 82 60 81 58 / 60 10 10 20 20 20
Coeur d`Alene 81 54 83 57 82 55 / 40 10 10 20 20 20
Pullman 82 52 82 54 81 51 / 30 10 10 20 20 20
Lewiston 88 61 90 62 87 61 / 20 10 10 20 20 20
Colville 83 52 86 55 86 52 / 70 20 10 30 20 30
Sandpoint 80 49 81 51 80 51 / 60 10 10 20 20 20
Kellogg 79 53 83 55 81 54 / 40 10 10 20 20 20
Moses Lake 85 58 83 60 82 57 / 20 10 10 30 20 20
Wenatchee 85 60 82 62 80 59 / 50 10 20 20 20 20
Omak 83 57 84 59 85 57 / 70 10 20 20 20 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 2 PM PDT this afternoon for Northern and
Central Idaho Panhandle (Zone 101).
WA...Red Flag Warning until 2 PM PDT this afternoon for East
Washington Northeast (Zone 686)-East Washington Northern
Columbia Basin (Zone 673)-East Washington Okanogan
Highlands (Zone 687)-East Washington Palouse and Spokane
Area (Zone 674).
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
644 AM PDT Fri Aug 23 2013
.SYNOPSIS...
A potent storm system will bring scattered showers and
thunderstorms through the region today. Unsettled conditions will
continue across the Inland Northwest over the weekend and majority
of next week as a moist southwest flow pattern remains in place.
&&
.DISCUSSION...
Early morning update: a shortwave trough is coming into the
Cascades of Washington and Columbia Basin and, combined with a
theta-e ridge bent across the northern mountains through the
Basin, scattered showers have been on the increase over the past
several hours. There have been a few embedded thunderstorms too.
The recent short-range RUC and HRRR keep a fair amount of the
activity along and north of the I-90 corridor, with more isolated
activity across the Palouse southward. I have updated the forecast
to reduce the PoPs in that latter locations as well as to slightly
delay the increase into the Spokane/C`dA areas.
However radar trends do show increasing activity, with "popcorn
showers" and thunderstorms expanding across the Moses Lake and
Upper Columbia Basin zones, skirting western Spokane county at
this hour. While most areas won`t see the day "washed-out", be
prepared for isolated to widely scattered showers or thunderstorm.
There is a fair amount of clear skies south and east of this
region, so the heating of the day and incoming trough should help
increase the shower/thunderstorm threat in areas where it is not
yet occurring. However the speed of the shortwave trough passage
may keep this activity isolated to widely scattered. Yet storms
may still be capable of producing abundant lightning with little
significant precipitation amounts. So the Red Flag Warning
continues. /J. Cote`
&&
.AVIATION...
12Z TAFS: Scattered showers and embedded thunderstorms will
continue to expand across central and eastern WA and north ID
this morning as an upper shortwave trof tracks northeast from
the Cascades. Primarily VFR conditions are expected, though brief
MVFR conditions and gusty winds are possible in heavy
showers/storms. As morning transitions to afternoon the
showers/thunderstorm threat is expected to translate northward,
with the west and southern TAF sites drying out and eventually all
TAF sites dry out by late afternoon. However look for breezy
conditions, with occasional gusts to 20kts. Winds abate in the
00-06Z time frame. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 81 58 82 60 81 58 / 20 10 10 20 20 20
Coeur d`Alene 81 54 83 57 82 55 / 20 10 10 20 20 20
Pullman 82 52 82 54 81 51 / 20 10 10 20 20 20
Lewiston 88 61 90 62 87 61 / 20 10 10 20 20 20
Colville 83 52 86 55 86 52 / 40 10 10 30 20 30
Sandpoint 80 49 81 51 80 51 / 40 20 10 20 20 20
Kellogg 79 53 83 55 81 54 / 20 10 10 20 20 20
Moses Lake 85 58 83 60 82 57 / 30 10 10 30 20 20
Wenatchee 85 60 82 62 80 59 / 40 10 20 20 20 20
Omak 83 57 84 59 85 57 / 40 10 20 20 20 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 2 PM PDT this afternoon for Northern and
Central Idaho Panhandle (Zone 101).
WA...Red Flag Warning until 2 PM PDT this afternoon for East
Washington Northeast (Zone 686)-East Washington Northern
Columbia Basin (Zone 673)-East Washington Okanogan
Highlands (Zone 687)-East Washington Palouse and Spokane
Area (Zone 674).
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
657 AM CDT FRI AUG 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 258 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES
TONIGHT.
CURRENTLY AS OF 07Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE
PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL
RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE
U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER
OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND
TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED
WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG
WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER
VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER
THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90
AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS
ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING
CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM
EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG
IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG
ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS
RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL.
HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE
SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA.
SYNOPTIC OVERVIEW...
MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY
EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE
RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED
OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL
SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS
SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA
TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE
FORECAST AREA.
DETAILS...
QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF
THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES
START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN
SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO
DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING
HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG
SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM.
HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS...
DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM
THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO
CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING...
ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET.
THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST
THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z
SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN
PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE
EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z
NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE
TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER
NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 258 AM CDT FRI AUG 23 2013
HAZARDS...
THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS
LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF
THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY
ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT
THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY
FOR MONDAY AND TUESDAY.
SYNOPTIC OVERVIEW...
23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84
HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY
LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG
TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER
MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS
AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL
ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE...
MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN
MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A
PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE
BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE
DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO
THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE.
PRECIPITATION DETAILS...
FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE
850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST
ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE
MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN
ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE
COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY
ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE
COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE...
HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF
20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH
INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME
LOCALLY HEAVY RAIN.
PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT
WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT
CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA
BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z
GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS
DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN
NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS
IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT
CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER
MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY
BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z
ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE...
FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR
SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND
BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY
ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE.
FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES
NEEDED EACH DAY IN THIS AREA.
TEMPERATURE DETAILS...
FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS
OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR
MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST
WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE
AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER.
TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB
TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY
PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING
TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S.
HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE.
MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER
THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN
30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF
90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO
SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE
DAYS WILL NEED AT LEAST A HEAT ADVISORY.
WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z
ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND
WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST
AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS
EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE
COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR
NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT
ADVISORY CONDITIONS.
LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW
TO MID 70S EVERY NIGHT.
GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY
MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS
AT THIS TIME.
NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 654 AM CDT FRI AUG 23 2013
THE COMBINATION OF LIGHT WINDS AND CLEAR SKIES RESULTED IN THE
DEVELOPMENT OF VALLEY FOG OVERNIGHT. AS HAS BEEN THE CASE DURING
THE PAST WEEK...THE RECENT DRYNESS HAS BEEN CAUSING WIDE RANGING
VISIBILITIES IN VALLEY AS IT MEANDERS THROUGH RIVER CHANNLE. KLSE
HAS RANGED FROM LITTLE AS A HALF MILE TO NOW 8 MILES...SO
CONFIDENCE IS ABOUT 60 PERCENT THAT A QUARTER MILE OR LESS WILL
MAKE IT BACK OVER THE AIR FIELD. BASED ON THE TIME OF
YEAR...EXPECT THAT THIS FOG WILL DISSIPATE RAPIDLY BETWEEN 23.14Z
AND 23.15Z.
FOR LATE TONIGHT...EXPECT A 4-5K DECK OF CLOUDS TO MOVE INTO THE
AREA AFTER 24.06Z AS A WARM FRONT APPROACHES THE AREA FROM WESTERN
MINNESOTA AND WESTERN IOWA. A FEW SHOWERS AND THUNDERSTORMS MAY
AFFECT KRST AFTER 24.10Z. HOWEVER CONFIDENCE WAS TOO LOW TO
INCLUDE IN THE TAF AT THIS TIME.
&&
.CLIMATE...
ISSUED AT 343 AM CDT FRI AUG 23 2013
GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR
LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE
INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055-
061.
MN...NONE.
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1235 PM MST FRI AUG 23 2013
.SYNOPSIS...
INCREASING MOISTURE AND PRECIPITATION CHANCES TODAY THROUGH
MONDAY...AS WELL AS A DECREASE IN TEMPERATURES. INCREASED
PRECIPITATION CHANCES WILL CONTINUE THROUGH MOST OF NEXT WEEK.
&&
.DISCUSSION...
MORNING SATELLITE IMAGERY LOOKS SIMILAR TO YESTERDAY...HOWEVER A BIT
LESS CLOUD COVER ACROSS THE STATE. LAST EVENING/S LARGE AREA OF
CONVECTION CAN BE SEEN ON RADAR MOVING INTO SOUTHWEST UTAH...AND
SOME STREAMS OF LINGERING SHOWERS ACROSS WESTERN MARICOPA COUNTY AT
10 AM MST. 12Z RAOB SOUNDING PWAT VALUES SHOW LITTLE CHANGE FROM
YESTERDAY WITH SLIGHT DRYING IN THE MID AND LOW LEVELS ACROSS THE
DESERT SOUTHWEST...VALUES 0.7 - 1.4 INCHES ACROSS ARIZONA. WITH THE
BOUNDARY LAYER WORKED OVER QUITE WELL IN THE SOUTHWEST CORNER OF
ARIZONA LAST EVENING...CONFIDENCE IS HIGHER MOST OF THE CONVECTIVE
ACTIVITY WILL REMAIN ACROSS MARICOPA COUNTY AND POINTS EASTWARD.
MADE SOME CHANGES TO THE POP GRIDS FOR THE REMAINDER OF
TODAY...INCREASING SPACIAL COVERAGE FOR SLIGHT CHANCES TO CHANCES
ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD BE SET FOR NOW...ON
TRACK TO REACH SEASONAL NORMAL. MORE UPDATES LATER...AS THE PREVIOUS
DISCUSSION STILL APPLIES.
.PREVIOUS DISCUSSION.../246 AM MST/...
EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST
AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD
OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA
OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE
STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO
THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL
WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS
MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS
SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL
MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY
IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT
EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING.
TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF
THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS
WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL
AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF
EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL
AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM
THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER.
NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA
PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED
WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN
THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED.
INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS
STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF
PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL
MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG.
LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL.
THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE
REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE
3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE
IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12
G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2
INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE
ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON
SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE
SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW
THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A
PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY
SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE
REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT
RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE
FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING.
UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I
THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE
MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY
WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS
GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND
EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT
WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER
GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY
AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS
ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE
LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
CONDITIONS REMAIN MOIST AND ISOLATED SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP THIS AFTERNOON ACROSS MUCH OF THE AREA. ACROSS
SOUTH-CENTRAL AZ...CONVECTION WILL BE CONCENTRATED ACROSS THE HIGHER
TERRAIN MAINLY EAST OF PHOENIX. AT THE PHOENIX TERMINALS...AN
OUTFLOW BOUNDARY IS LIKELY TO PRODUCE A WIND SHIFT THIS
EVENING...RESULTING IN AN EARLIER ONSET TO THE DRAINAGE FLOW.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...DEWEY
PREVIOUS DISCUSSION...LEINS
AVIATION...HIRSCH
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
1015 AM MST FRI AUG 23 2013
.SYNOPSIS...
INCREASING MOISTURE AND PRECIPITATION CHANCES TODAY THROUGH
MONDAY...AS WELL AS A DECREASE IN TEMPERATURES. INCREASED
PRECIPITATION CHANCES WILL CONTINUE THROUGH MOST OF NEXT WEEK.
&&
.DISCUSSION...
MORNING SATELLITE IMAGERY LOOKS SIMILAR TO YESTERDAY...HOWEVER A BIT
LESS CLOUD COVER ACROSS THE STATE. LAST EVENING/S LARGE AREA OF
CONVECTION CAN BE SEEN ON RADAR MOVING INTO SOUTHWEST UTAH...AND
SOME STREAMS OF LINGERING SHOWERS ACROSS WESTERN MARICOPA COUNTY AT
10 AM MST. 12Z RAOB SOUNDING PWAT VALUES SHOW LITTLE CHANGE FROM
YESTERDAY WITH SLIGHT DRYING IN THE MID AND LOW LEVELS ACROSS THE
DESERT SOUTHWEST...VALUES 0.7 - 1.4 INCHES ACROSS ARIZONA. WITH THE
BOUNDARY LAYER WORKED OVER QUITE WELL IN THE SOUTHWEST CORNER OF
ARIZONA LAST EVENING...CONFIDENCE IS HIGHER MOST OF THE CONVECTIVE
ACTIVITY WILL REMAIN ACROSS MARICOPA COUNTY AND POINTS EASTWARD.
MADE SOME CHANGES TO THE POP GRIDS FOR THE REMAINDER OF
TODAY...INCREASING SPACIAL COVERAGE FOR SLIGHT CHANCES TO CHANCES
ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD BE SET FOR NOW...ON
TRACK TO REACH SEASONAL NORMAL. MORE UPDATES LATER...AS THE PREVIOUS
DISCUSSION STILL APPLIES.
.PREVIOUS DISCUSSION.../246 AM MST/...
EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST
AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD
OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA
OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE
STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO
THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL
WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS
MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS
SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL
MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY
IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT
EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING.
TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF
THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS
WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL
AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF
EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL
AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM
THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER.
NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA
PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED
WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN
THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED.
INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS
STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF
PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL
MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG.
LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL.
THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE
REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE
3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE
IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12
G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2
INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE
ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON
SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE
SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW
THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A
PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY
SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE
REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT
RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE
FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING.
UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I
THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE
MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY
WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS
GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND
EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT
WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER
GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY
AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS
ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE
LOOKED INTO FURTHER AS THE EVENT GETS CLOSER.
&&
.AVIATION...
SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH...
A WEATHER DISTURBANCE OVER WESTERN ARIZONA WILL KEEP CLOUDINESS...AT
OR ABOVE 12 KFT MSL...IN PLACE BETWEEN PHOENIX AND FAR SOUTHEAST
CALIFORNIA THROUGH THE MORNING BEFORE DECREASING THIS AFTERNOON.
SHOWERS WILL BE POSSIBLE IN THAT AREA WITH MORE ACTIVITY OVER
NORTHERN ARIZONA AND SOUTHERN NEVADA. ONCE AGAIN...OUTFLOW WINDS
FROM DISTANT STORMS WILL BE A DISTINCT POSSIBILITY LATER TODAY/THIS
EVENING. THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS AT EACH OF
THE TAF SITES BUT LESS ACTIVITY IS ANTICIPATED OVER THE LOWER
COLORADO RIVER VALLEY AND THE IMPERIAL VALLEY THAN ON THURSDAY.
CONFIDENCE IN STORMS OCCURRING OVER ANY GIVEN TAF SITE TOO LOW TO
REFLECT IN THE TAFS AT THIS POINT. APART FROM THUNDERSTORMS...WINDS
WILL BE LIGHT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE
EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND
SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO
MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME
LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC
MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY
AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE
TEMPERATURES TREND UPWARD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...DEWEY
PREVIOUS DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1013 AM MDT FRI AUG 23 2013
.UPDATE...WITH LINGERING CLOUD COVER...HAVE ADJUSTED MAX
TEMPERATURES DOWN A COUPLE DEGREES...MAINLY OVER THE DENVER METRO
AREA AND FOOTHILLS.
WATER VAPOR SATELLITE STILL SHOWING PLENTY OF MOISTURE ROTATING
AROUND THE STATE...HOWEVER PRECIPITABLE WATER VALUES OVER
NORTHEAST CO ARE DOWN 0.3 INCHES FROM YESTERDAY AT THE SAME TIME.
MODELS STILL ADVERTISING DRIER AIR MOVING NORTH FROM NEW
MEXICO...HOWEVER BELIEVE LAST NIGHTS/THIS MORNINGS MCS OVER THE
STATE MAY HAVE DELAYED IT A BIT. STILL EXPECTING DRIER AIR TO
BEGIN TO MOVE UP FROM THE SOUTH LATER TODAY WHICH WILL LIMIT
STORM ACTIVITY OVER THE PLAINS...MAINLY SOUTH OF I76. ENOUGH
INSTABILITY OVER THE MOUNTAINS AND OVER CHEYENNE RIDGE WILL ALLOW
SCATTERED STORMS TO ONCE AGAIN FORM TODAY.
&&
.AVIATION...LIGHT WINDS NEAR THE AIRPORT SHOULD BEGIN
TRANSITIONING TO BE OUT OF THE NORTHEAST AS SOUTHERLY WINDS OVER
THE EASTERN PLAINS CYCLONE INTO THE AREA. THERE WILL BE A CHANCE
FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 21-01Z. HEAVY RAIN
AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE STRONGER
STORMS. HIGH-RES MODELS POINTING TO THE HIGHER TERRAIN OF PARK AND
JEFFERSON COUNTIES WITH SLIGHTLY MORE COVERAGE EARLIER ON THEN
BRING IT NORTHEAST TOWARD THE METRO AREAS. THIS WOULD LIKELY TURN
WINDS BACK FROM THE SOUTH. DRIER AIR WILL MOVE INTO THE AREA
TONIGHT AND BRING CLEARING SKIES.
&&
.PREV DISCUSSION... /ISSUED 338 AM MDT FRI AUG 23 2013/
SHORT TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL AS THE UPPER LEVEL
HIGH SHIFTS EASTWARD TODAY. A LOW PRESSURE SYSTEM WILL FORM OVER
SOUTHERN ALBERTA DURING THE DAY AND A LOW PRESSURE TROUGH WILL
EXTEND SOUTHWARD ALONG THE LEE SIDE OF THE ROCKIES AND INTO
COLORADO. THIS WILL PRODUCE SOUTHERLY WINDS OVER EASTERN COLORADO.
DRIER OVER NEW MEXICO WILL BE PULLED NORTHWARD THROUGH THE DAY.
THE LATEST RAP SHOWS THE AIRMASS WILL STAY MOIST TODAY WITH
PRECIPITABLE WATER VALUES OF AN INCH TO 1.25 AND CAPES OF 1000 TO
1500 J/KG. THIS WOULD SUPPORT ANOTHER ROUND OF STRONG THUNDERSTORMS.
THE NAM AND GFS HAS PRECIPITABLE WATER VALUES OF 0.75 TO ONE INCH
WITH CAPES LESS THAN 700 J/KG. WHAT ACTUALLY HAPPENS WILL PROBABLY
BE SOMEWHERE IN BETWEEN THESE SOLUTIONS. WILL HAVE THE HIGHEST POPS
OVER THE MOUNTAINS AND ACROSS THE NORTHERN ZONES. ALL THE MODELS
HAVE SOME DRYING OVER THE SOUTHEAST ZONES AND IT SPREADS NORTH
DURING THE EVENING...THUS WILL HAVE THE LOWEST POPS HERE. EXPECT THE
CONVECTION TO END DURING THE EVENING HOURS AS DRIER AIR MOVES INTO
THE AREA.
TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY. CLEARING SKIES THIS
MORNING AND EARLY AFTERNOON SHOULD ALLOW ENOUGH SUN TO PUSH HIGHS IN
THE UPPER 80S AND PERHAPS LOWER 90S. AS DRIER MOVES INTO THE AREA
TONIGHT...TEMPERATURES WILL FALL INTO THE 50S.
LONG TERM...MODELS SHOW THE UPPER RIDGE CENTERED OVER CENTRAL
KANSAS SATURDAY MORNING. IT MOVES INTO EASTERN KANSAS BY SUNDAY
NIGHT. THE FLOW ALOFT STAYS SOUTHWESTERLY OVER THE FORECAST AREA
ALL FOUR PERIODS. THE QG VERTICAL VELOCITY FIELD KEEP BENIGN
SYNOPTIC SCALE ENERGY OVER THE CWA THROUGH THE PERIOD. THE
BOUNDARY LAYER FLOW IS PROGGED TO BE PRETTY MUCH NORMAL DIURNAL
PATTERNS THROUGH SUNDAY NIGHT. FOR MOISTURE...MODELS SHOW A FAIR
AMOUNTS LATE DAY SATURDAY AND LATE DAY SUNDAY...BUT IT IS IN THE
MID AND UPPER LEVELS. THE BOUNDARY LAYER DEW POINT VALUES ARE
PROGGED IN THE 40S TO LOWER 50S F FOR THE PLAINS LATE DAY
SATURDAY...AND A TAD HIGHER LATE DAY SUNDAY. PRECIPITABLE WATER
VALUES ARE IN THE 0.65 TO 1.10 INCH RANGE OVER THE PLAINS SATURDAY
THROUGH SUNDAY NIGHT. THE HIGHEST VALUES ARE OUT EAST. THE CAPE IS
PRETTY LOW FOR LATE DAY SATURDAY...WITH THE HIGHEST VALUES OVER
THE FOOTHILLS. THEY GET UP 750 J/KG AT BEST THERE...WITH VALUES
OVER THE PLAINS FROM 100-500 J/KG. THERE IS EVEN LESS CAPE LATE
DAY SUNDAY FOR ALL AREAS. MEASURABLE RAINFALL IS PRETTY SPARSE ON
THE QPF FIELDS. THERE IS SOME LATE DAY SATURDAY OVER THE WESTERN
HALF OF THE CWA...THEN A TAD BIT LESS LATE DAY SUNDAY. FOR
POPS...20-30%S IN THE MOUNTAINS SHOULD DO FOR THE LATE DAYS AND
0-10%S OVER THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE
1-2 C WARMER THAN TODAY`S EXPECTED HIGHS. SUNDAY`S ARE CLOSE TO
SATURDAY`S. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS
KEEP THE UPPER RIDGE CENTERED OVER KANSAS ALL FOUR DAYS. THE
SOUTHWESTERLY FLOW ALOFT STAYS AROUND FOR THE CWA AS WELL...BUT
MOISTURE IS SPARSE. TEMPERATURES LOOK TO STAY A BIT ABOVE SEASONAL
NORMALS.
AVIATION...SLIGHT CHANCE FOR PATCHY FOG AND LOW CLOUDS THIS
MORNING...NOT ENOUGH OF A CHANCE TO MENTION IN THE TAFS. THERE WILL
BE A CHANCE FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 20-01Z.
HEAVY RAIN AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE
STRONGER STORMS. DRIER AIR WILL MOVE INTO THE AREA TONIGHT AND BRING
CLEARING SKIES. SOUTHERLY WINDS ARE EXPECTED FOR MOST OF THE DAY.
HYDROLOGY...ANOTHER ROUND OF THUNDERSTORMS WILL FORM OVER THE
HIGHER TERRAIN AND SPREAD EASTWARD. HEAVY RAIN WILL AGAIN BE
POSSIBLE WITH THE STORMS WITH 1 INCH IN 15 TO 20 MINUTES OCCURRING.
FLASHING FLOODING COULD OCCUR IF A STRONG STORM FORMS OVER THE BURN
AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MEIER
LONG TERM....RJK
UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS ALBANY NY
421 PM EDT FRI AUG 23 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD EASTWARD FROM THE GREAT LAKES REGION
INTO THE NORTHEAST THROUGH SATURDAY...WITH A NORTHERLY FLOW
BRINGING COOLER TEMPERATURES AND COMFORTABLE HUMIDITY LEVELS. THE
SURFACE ANTICYCLONE WILL DRIFT EAST OF NEW JERSEY ON SUNDAY WITH
CONTINUED FAIR WEATHER BUT WITH A SOUTHWEST FLOW AND SLIGHTLY
WARMER TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 415 PM EDT...PARTLY TO MOSTLY SUNNY SKIES PREVAIL ACROSS THE
REGION...WITH MOST OF THE CLOUDS CONFINED TO HIGHER TERRAIN WEST
AND EAST OF THE HUDSON RIVER VALLEY.
THESE CLOUDS SHOULD GRADUALLY DISSIPATE AROUND...OR JUST AFTER
SUNSET...LEAVING MOSTLY CLEAR TO CLEAR SKIES FOR THE OVERNIGHT
HOURS. THE LATEST RUC13 SUGGESTS A SECONDARY SURGE OF LOW
LEVEL...DRY AIR ADVECTING SOUTHWARD EARLY TONIGHT. THIS MAY ACT TO
KEEP THE BOUNDARY LAYER SOMEWHAT MIXED...PARTICULARLY IN THE
HUDSON VALLEY REGION...WITH A N/NE WIND PERSISTING WELL INTO THE
OVERNIGHT HOURS...WHICH MAY PRECLUDE FOG FORMATION AND ALSO VERY
COOL TEMPS FROM OCCURRING. THEREFORE...HAVE KEPT OUT MENTION OF
PATCHY FOG...AND HAVE INDICATED MIN TEMPS IN THE MID 40S TO LOWER
50S IN MOST AREAS...WITH SOME LOWER 40S POSSIBLE ACROSS PORTIONS
OF THE WESTERN ADIRONDACKS.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
SAT-SUN...HIGH PRESSURE SHOULD PROVIDE GENERALLY CLEAR/SUNNY SKIES
FOR SAT...WITH JUST OCCASIONAL PASSING HIGH CLOUDS POSSIBLE LATE
SAT NT INTO SUNDAY. MIXING DEPTHS MAY BE SOMEWHAT SHALLOW FOR
SAT...COMPARED TO RECENT DAYS...GENERALLY UP TO BETWEEN 900 AND
875 MB. THIS SHOULD ALLOW FOR MAX TEMPS TO REACH 75-80 IN MOST
VALLEY AREAS...AND UPPER 60S TO LOWER/MID 70S ACROSS HIGHER
ELEVATIONS. FOR SAT NT/SUN AM...MIN TEMPS COULD BE A BIT COOLER
THAN TONIGHT...ESP SHOULD ANY HIGH CLOUDS HOLD OFF OR REMAIN VERY
THIN. HOWEVER...WITH LESS MIXING AND WIND COMPARED TO
TONIGHT...THE POTENTIAL FOR AT LEAST PATCHY GROUND FOG WILL BE
GREATER...WHICH COULD KEEP AREAS IMMEDIATELY ADJACENT TO BODIES OF
WATER A BIT WARMER. HAVE GENERALLY SIDED A BIT CLOSER TO THE
COOLER MAV MOS IN MOST AREAS...WITH MIN TEMPS FALLING INTO THE MID
40S TO LOWER 50S IN MOST VALLEY AREAS...AND MAINLY LOWER/MID 40S
ACROSS HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND...AND THE
EASTERN CATSKILLS/WESTERN ADIRONDACKS. ACROSS SOME SHELTERED
PORTIONS OF THE SOUTHERN ADIRONDACKS...AND EASTERN
CATSKILLS...SOME UPPER 30S COULD EVEN OCCUR BY DAYBREAK SUNDAY.
AFTER THE CHILLY START...EXPECT SLIGHTLY DEEPER MIXING WITH A
DEVELOPING SOUTHWEST LOW LEVEL FLOW TO ALLOW FOR WARMER MAX TEMPS
ON SUNDAY...WITH UPPER 70S TO LOWER 80S IN MOST VALLEYS...AND
70-75 FOR HIGHER ELEVATIONS.
SUN NT-MON NT...FORECAST UNCERTAINTY INCREASES DURING THIS PERIOD
AS LOW/MID LEVEL WARM ADVECTION STRENGTHENS LATE SUN NT INTO
MONDAY...IN RESPONSE TO A POTENTIAL MID LEVEL DISTURBANCE
APPROACHING FROM THE GREAT LAKES REGION. THIS PATTERN SHOULD ALLOW
FOR INCREASING CLOUDS LATE SUN NT...WITH THE POSSIBILITY OF
SHOWERS FOR MON-MON NT. SOME THUNDERSTORMS COULD OCCUR AS
WELL...ESP LATE MON INTO MON NT AS ELEVATED INSTABILITY DEVELOPS.
EXPECT OVERNIGHT MIN TEMPS TO BE WARMER...WITH MAINLY LOWER/MID
60S FOR VALLEY AREAS...AND 55-60 ACROSS HIGHER ELEVATIONS. MON MAX
TEMPS SHOULD REACH THE MID 70S TO LOWER 80S...ALTHOUGH SHOULD
WIDESPREAD SHOWERS OR A PERIOD OF STEADIER RAIN OCCUR...EVEN
COOLER MAX TEMPS COULD OCCUR.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
A CONTINUOUS PATTERN OF DISTURBANCES THAT ARE POTENTIAL RIDGE
ROLLERS SHOULD FLOW FROM NORTHWEST TO SOUTHEAST ON THE NORTHEAST
SIDE OF A BROAD UPPER LEVEL HIGH PRESSURE...CENTERED OVER THE
CENTRAL PLAINS...WHICH WILL AFFECT OUR WEATHER FOR THE EXTENDED
PERIOD. CURRENT THINKING IS THAT THE 12Z MODELS ARE A BIT
DISORGANIZED DUE TO THE EXTENT OF THE RIDGE ITSELF THAT WILL DICTATE
THE SYNOPTIC TRACK OF THESE LOW PRESSURE IMPULSES AS THEY MOVE ON
THE OUTSKIRTS OF THE HIGH PRESSURE SYSTEM. CHANCE POPS WILL BE
THROUGHOUT THE EXTENDED PERIOD TO INCORPORATE THE DIFFERENT
PROBABILITY BLENDS IN THE FORECAST. OUR BEST CHANCE FOR SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH AN UPPER LEVEL POSITIVE TILTED TROUGH
WITH A POSSIBLE DEVELOPING SURFACE LOW PRESSURE NEAR THE US/CANADA
BORDER WILL BE ON WEDNESDAY NIGHT INTO THURSDAY MORNING. THE GENERAL
CONSENSUS AS OF NOW SHOWS CLEARING IN THE AREA LATE THURSDAY MORNING
AS THE RIDGE FROM THE CENTRAL PLAINS SHIFTS EAST AND HAS MORE OF AN
INFLUENCE ON OUR WEATHER PATTERN...GIVING TRANQUIL CONDITIONS FOR
THE DAY ON FRIDAY. A WARM UP TO ABOVE AVERAGE TEMPERATURES GOING
FROM FRIDAY INTO NEXT WEEKEND IS POSSIBLE AS THE RIDGE CONTINUES TO
MOVE EAST NORTHEAST INTO OUR REGION.
HIGH TEMPERATURES THROUGHOUT THE EXTENDED PERIOD WILL RANGE FROM
THE MID AND UPPER 70S IN THE HIGH TERRAIN TO LOWER 80S IN VALLEY
LOCATIONS. LOW TEMPERATURES WILL RANGE FROM THE UPPER 50S TO MID 60S
FOR THE ENTIRE REGION.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
THE MAJORITY OF THE UPCOMING TAF PERIOD WILL BE VFR. SOME MORNING
FOG IS POSSIBLE AT KGFL...WHERE IT COULD BE LOCALLY DENSE
RESULTING IN LIFR CONDITIONS...AND AT KPSF WHERE MVFR IS MORE
LIKELY. A LIGHT NORTHERLY FLOW AND DRY AIR ADVECTION WILL RESULT
IN MODERATE MIXING OVERNIGHT SO FOG IS NOT EXPECTED AT KALB AND KPOU.
NORTHWEST TO NORTH WINDS AROUND 10 KNOTS TODAY WILL DIMINISH THIS
EVENING BECOMING CALM OVERNIGHT. LIGHT NORTHERLY WINDS ARE AGAIN
EXPECTED ON SATURDAY.
OUTLOOK...
SATURDAY NIGHT: NO OPERATIONAL IMPACT. PATCHY FG.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...TSRA.
TUESDAY NIGHT: LOW OPERATIONAL IMPACT. ISOLATED SHRA...TSRA.
WEDNESDAY: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...TSRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE ANTICIPATED THE NEXT FEW DAYS. HIGH
PRESSURE WILL BUILD EASTWARD FROM THE GREAT LAKES REGION AND
SOUTHEASTERN CANADA ACROSS THE NORTHEAST TODAY INTO
SATURDAY...WITH COOLER TEMPERATURES AND COMFORTABLE HUMIDITY
LEVELS. THE SURFACE ANTICYCLONE WILL DRIFT SOUTH AND EAST OF THE
NORTHEAST ON SUNDAY WITH TEMPERATURES MODERATING SLIGHTLY ABOVE
NORMAL WITH CONTINUED FAIR WEATHER.
RELATIVE HUMIDITY VALUES WILL RECOVER TO 90 TO 100 PERCENT
TONIGHT WITH SOME DEW FORMATION POSSIBLE. THE RH VALUES WILL FALL
TO 30 TO 45 PERCENT SATURDAY AFTERNOON...THEN RECOVER TO 90-100
PERCENT FOR SAT NT WITH WIDESPREAD DEW FORMATION LIKELY.
NORTH TO NORTHEAST WINDS AT 10-15 MPH WILL DECREASE TO 5-10 MPH
OVERNIGHT. WINDS WILL BE NORTHEAST TO EAST AT 5-15 MPH
SATURDAY...THEN BECOME LIGHT AND VARIABLE FOR SAT NT.
&&
.HYDROLOGY...
DRY WEATHER IS EXPECTED THROUGH THE WEEKEND. THE WEATHER BECOMES
MORE UNSETTLED SUNDAY NIGHT INTO TUESDAY WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS AS A LOW PRESSURE SYSTEM AND ITS
ASSOCIATED FRONTAL BOUNDARIES APPROACHES FROM THE GREAT LAKES
REGION. PRECIPITATION AMOUNTS WILL BE HIGHLY VARIABLE DEPENDING ON
ANY CONVECTION.
OVERALL FOR THE NEXT 5 DAYS...NO WIDESPREAD HYDRO PROBLEMS ARE
EXPECTED. RIVER FLOWS...AND RESERVOIR LEVELS CONTINUE AT NORMAL TO
SLIGHTLY BELOW NORMAL LEVELS FOR LATE AUGUST.
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...KL/WASULA
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...LFM
AVIATION...SND
FIRE WEATHER...KL/WASULA
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS NEW YORK NY
230 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL APPROACH FROM THE EAST THIS
EVENING...AND PASS TO THE SOUTH TONIGHT. HIGH PRESSURE WILL THEN
BUILD IN THIS WEEKEND...AND SETTLE TO THE SOUTH EARLY NEXT WEEK.
MULTIPLE LOWS WILL IMPACT THE NORTHEAST NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH CLOUD DEBRIS FROM MID ATLANTIC MCS HAS DRIFTED IN...MAKING
FOR WITH A PTCLDY AFTERNOON AND EVENING. MEANWHILE...SUBTLE
FRONTAL BOUNDARY/CONVERGENCE ZONE IS MOVING IN FROM THE EAST...
MARKED ATTM BY CLOUD LINE CUTTING NE-SW ACROSS RHODE ISLAND...
WITH NE FLOW ON THE COOL EAST SIDE OF THE BOUNDARY. THE BOUNDARY
SHOULD GRADUALLY DRIFT SW INTO THE AREA...WITH HRRR SHOWING
POTENTIAL FOR A FEW SHOWERS OVER FAR ERN CT/LONG ISLAND. HRRR IS
USUALLY TOO QUICK TO INITIATE CONVECTION SO INTRODUCED SLIGHT
CHANCE POP FOR THESE AREAS INTO THIS EVENING RATHER THAN LATE
AFTERNOON. BOUNDARY COULD SPARK A FEW ADDITIONAL SHOWERS
TONIGHT...BUT THINK THESE WILL BE MAINLY OVER THE OCEAN AND IN
TANDEM WITH A MID LEVEL SHORTWAVE TROUGH MOVING OHD TONIGHT.
OTHERWISE...SKIES SHOULD BECOME MOSTLY CLEAR WITH DIMINISHING N-NE
WINDS FOR MOST OF THE NIGHT...THEN PICKING UP A LITTLE TOWARD
DAYBREAK ALONG THE COAST AS THE PRESSURE GRADIENT TIGHTENS BETWEEN
HIGH PRESSURE BUILDING FROM THE NW AND LOW PRESSURE FORMING ALONG
A FRONTAL ZONE SE OF CAPE COD. LOWS TONIGHT ARE A GUIDANCE
BLEND...WITH 50S FOR INLAND SECTIONS...COASTAL SE CT AND THE LONG
ISLAND PINE BARRENS...AND 60S ELSEWHERE.
&&
.SHORT TERM /SATURDAY INTO SATURDAY NIGHT/...
SUNNY AND MILD ON SAT AS NORTHERLY WINDS CONTINUE TO USHER IN
SLIGHTLY COOLER AND DRIER AIR....WITH HIGHS 1-2 DEG EITHER SIDE
OF 80. AS THE HIGH BUILDS TO THE NORTH...FLOW ALONG THE COAST
SHOULD TURN E-SE IN THE AFTERNOON.
COOLER SAT NIGHT WITH MOCLEAR SKIES AND LIGHT WINDS. LOWS WILL BE
60-65 IN NYC METRO...IN THE 50S MOST ELSEWHERE...AND 45-50 IN THE
INTERIOR VALLEYS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A GENERALLY QUIET BEGINNING TO THE COMING WEEK...WITH INCREASING
CHANCES OF ACTIVITY THROUGH THE WEEK WITH MULTIPLE SYSTEMS PASSING
THROUGH. UPPER LEVEL PATTERN REMAINS FAIRLY CONSISTENT AS RIDGING
SETS UP OVER THE CENTRAL US...KEEPING THE NORTHEAST REGION ON THE
OUTER PERIPHERY OF THE RIDGE AND IN LINE FOR THE PASSING OF
MULTIPLE SHORTWAVES.
SUNDAY QUIET WITH THE CENTER OF THE SURFACE HIGH SITTING OHD AND
SUBSIDENCE ALOFT PRODUCING MOSTLY CLEAR/SUNNY SKIES. INCREASING
CLOUD COVERAGE SUNDAY NIGHT INTO MONDAY AS THE FIRST OF MANY
SHORTWAVES ROUNDS THE RIDGE. BEGAN INTRODUCING POPS BY LATE AFTN
MONDAY AS THE SURFACE HIGH SLIPS TO THE SOUTH AHEAD OF AN
APPROACHING FRONTAL SYSTEM AND MORE PROMINENT SHORTWAVES ROUND THE
RIDGE. SOME MODEL DIVERGENCE ON THE HANDLING OF THE LOW PRESSURE
SYSTEM...HOW STRONG AND HOW QUICKLY IT PROGRESSES THROUGH AND
WHETHER A SECONDARY LOW FORMS ALONG THE FRONT BY THURS. THE 00Z
GFS/CMC HAVE A MORE PRONOUNCED LOW AND THE 00Z ECMWF A BIT QUICKER
WITH THE INTRODUCTION OF PCPN MONDAY AS WELL AS LINGERING IT
LONGER INTO MID WEEK WITH THE DEVELOPMENT OF THE SECOND LOW AND
LINGERING IT OFF THE NE COAST. WITH SUCH DIFFERENCES IN THE MODELS
AT THIS TIME...WILL MAINTAIN LOWER END CHC POPS MON NIGHT-
WED...WITH DRYING CONDITIONS FOR NOW FOR THE END OF THE WEEK IN
THE WAKE OF A PASSING COLD FRONT AND SUBSIDENCE ATTEMPTING TO
BUILD IN ALOFT. ANY ACTIVITY THAT DOES DEVELOP EARLIER IN THE WEEK
AT THE MOMENT LOOKS TO BE MORE SCATTERED IN NATURE.
AFTER A WEEKEND OF NEAR NORMAL TEMPS...WAA WILL LEAD TO INCREASED
TEMPS AND DEWPTS...RESULTING IN MORE HUMID CONDITIONS AND ABOVE
NORMAL TEMPS. THIS WILL AID IN INCREASING THE INSTABILITY AS
WELL...SO WILL KEEP MENTION OF THUNDER IN FOR THE FIRST HALF OF
THE WEEK.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS INTO THE TERMINALS THROUGH SATURDAY.
VFR. A BRIEF SHOWER IS POSSIBLE 05Z TO 10Z IN THE VICINITY OF KJFK
AND KISP.
NORTHERLY WIND GRADUALLY BECOMES MORE NORTH TO NORTHEAST...020 TO
030...THIS AFTERNOON WITH ANY GUSTS SUBSIDING BY 22Z. WIND REMAINS
NORTHEAST OVERNIGHT AND INTO SATURDAY AFTERNOON.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: OCCASIONAL GUSTS UP TO 20 KT POSSIBLE THROUGH
21Z.
KJFK FCSTER COMMENTS: OCCASIONAL GUSTS UP TO 20 KT POSSIBLE THROUGH
21Z.
KLGA FCSTER COMMENTS: GUSTS TO AROUND 20 KT CONTINUE THROUGH 21Z. AN
OCCASIONAL GUSTS TO 23Z WILL BE POSSIBLE.
KTEB FCSTER COMMENTS: AN OCCASIONAL GUST TO AROUND 15 KT WILL BE
POSSIBLE THROUGH 21Z.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
.SATURDAY AFTERNOON-MONDAY...VFR.
.MONDAY NIGHT-WEDNESDAY...SUB-VFR POSSIBLE IN SHRA/TSRA WITH LOW
PRESSURE MOVING THROUGH THE AREA.
&&
.MARINE...
N FLOW SHOULD TURN E-NE THIS EVENING AS A WEAK FRONTAL BOUNDARY
MOVES IN FROM THE EAST...AND THEN MORE NE LATE TONIGHT AS THE
PRESSURE GRADIENT TIGHTENS BETWEEN HIGH PRESSURE BUILDING FROM
THE NW AND LOW PRESSURE FORMING ALONG A FRONTAL ZONE SE OF CAPE
COD. WIND GUSTS AND OCEAN SEAS SHOULD APPROACH BUT FALL SHY OF SCA
CRITERIA OF 25 KT AND 5 FT LATE TONIGHT INTO EARLY SAT MORNING.
OTHERWISE...QUIET THROUGH SAT NIGHT AS HIGH PRESSURE BUILDS IN.
A WEAK PRESSURE GRADIENT RESULTING FROM HIGH PRESSURE KEEPS SUB-
SCA CONDITIONS ON ALL WATERS TO END THE WEEKEND AND BEGIN THE
COMING WEEK. POSSIBLE 5 FT SEAS ON THE OCEAN WATERS BY TUESDAY
WITH PERSISTENT AND INCREASING SW FLOW AHEAD OF AN APPROACHING
FRONTAL SYSTEM. SEAS ARE EXPECTED TO SUBSIDE BY WED AND SHOULD
REMIND SUB-SCA THEN FOR THE REST OF THE WEEK. THUNDERSTORMS IN THE
FIRST HALF OF THE WEEK MAY BRING SOME STRONGER GUSTS...BUT
OTHERWISE WINDS SHOULD REMAIN BELOW 25 KT FOR THE PERIOD.
&&
.HYDROLOGY...
THERE IS SOME HEAVY RAIN POTENTIAL FOR NEXT WEEK. IT IS STILL TOO
EARLY TO BE SPECIFIC ON EXACT TIMING/LOCATION.
&&
.EQUIPMENT...
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW
YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN
TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS
BEING FORMULATED.
DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING
SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GOODMAN/MPS
NEAR TERM...GOODMAN
SHORT TERM...GOODMAN
LONG TERM...SEARS
AVIATION...MET
MARINE...GOODMAN/MPS
HYDROLOGY...GOODMAN/MPS
EQUIPMENT...GOODMAN
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
150 PM EDT FRI AUG 23 2013
.PREV DISCUSSION... /ISSUED 1128 AM EDT FRI AUG 23 2013/
UPDATE...
HAVE MADE SEVERAL MAINLY MINOR TWEAKS TO GRIDS THIS MORNING...
MAINLY TO UPDATE TRENDS. DID REDUCE POPS FOR THE MORNING AND EARLY
AFTERNOON HOURS BUT EXCEPT FOR SENDING THE NEW GRIDS TO THE WEB...
NO UPDATED PRODUCTS NECESSARY WITH THAT SINCE AFTERNOON POPS
REMAIN THE SAME. AS CONVECTION FIRES...MAY HAVE TO REEVALUATE
LOCATION OF HIGHEST POPS THROUGH THE AFTERNOON BUT FOR THE MOST
PART GRIDS LOOK GOOD. NO UPDATE PLANNED.
TDP
PREV DISCUSSION... /ISSUED 748 AM EDT FRI AUG 23 2013/
PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/
SHORT TERM /TODAY THROUGH SATURDAY/...
LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING
FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK
RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER
FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT
LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF
THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR
IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG
WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL
OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK
AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD
CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA
INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM
THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW
BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED.
FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT
FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS
AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM
MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY
DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH
PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN
THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000
J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO
FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW
1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO
ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A
COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG
VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA.
OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH
RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA.
ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE
SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS
ENHANCED DEVELOPMENT DURING THE AFTERNOON.
DEESE
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS
SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER
LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM
CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE
LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED
TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY
EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE
INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N
GA.
PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE
SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND
THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP
AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE
MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED.
GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE
EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW
POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS
ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH
THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE
FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY.
BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY.
TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL
DURING THIS PERIOD.
BDL
&&
.AVIATION...
18Z UPDATE...
VFR EVERYWHERE THIS AFTERNOON. HAVE KEPT FORMER PROB30 TIMING AND
JUST CHANGED TO TEMPO AT ATL...WILL MONITOR FOR OTHER SITES.
EXPECT MVFR FOG TO DEVELOP AGAIN IN THE MORNING WITH WIND SHIFT TO
NE AFTER 06Z. MAY SEE LOWER CONDITIONS AGAIN AT MCN LIKE THIS
MORNING. CLEARING AFTER 14Z. ADDED ANOTHER PROB30 FOR ATL SATURDAY
AFTERNOON.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON AFTERNOON CONVECTION.
MEDIUM ON VSBY SATURDAY MORNING.
HIGH ON ALL OTHER ELEMENTS.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 91 73 84 67 / 40 30 30 20
ATLANTA 89 75 86 70 / 40 20 30 20
BLAIRSVILLE 86 67 81 65 / 50 20 30 10
CARTERSVILLE 90 72 87 69 / 30 20 20 20
COLUMBUS 90 77 88 72 / 50 30 30 20
GAINESVILLE 88 73 83 69 / 40 20 30 20
MACON 91 74 87 71 / 50 30 30 20
ROME 91 72 87 69 / 40 20 20 20
PEACHTREE CITY 88 72 85 69 / 40 20 30 20
VIDALIA 89 75 88 71 / 50 30 40 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1256 PM CDT FRI AUG 23 2013
.DISCUSSION...
352 AM CDT
SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE
GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH
HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE.
TODAY...
HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT
CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES
OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED
IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE
EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG
DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO
BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH
HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS
WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN
THE UPPER 70S TO AROUND 80.
REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE
BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG
THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE
MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE
COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL
THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY
TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM
THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM.
SATURDAY THROUGH MONDAY...
THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO
SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL
PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH
PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT
INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE
SOUTHEAST ATLANTIC COAST MONDAY NIGHT.
MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE
RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT.
ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE
NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS
DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH
AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST.
HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT
CWA.
UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON
MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY
REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE
DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING.
THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT
INDICES IN THE UPPER 90S TO AROUND 100.
LONG TERM...TUESDAY THROUGH THURSDAY...
THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A
BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION.
GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK
AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL
EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND
EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH
TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING
IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL
TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON
WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT.
A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY
INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED.
TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER
CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* EAST TO NORTHEAST WINDS ARND 10-14KT THIS AFTERNOON DIMINISH
ARND SUNSET TO 3-5KT.
BEACHLER
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE OVERHEAD WILL CONTINUE TO PROVIDE OPTIMAL FLYING
CONDITIONS TO NORTHERN IL/NORTHWEST IN AIRFIELDS. VISIBLE IMAGERY
CONTINUES TO INDICATE NEAR CLOUDLESS SKIES FOR THE AREA
AIRFIELDS...AND IS EXPECTED TO PERSIST OVERNIGHT INTO SATURDAY.
EAST WINDS WITH SPEEDS GENERALLY AROUND 10-14KT WILL QUICKLY
DIMINISH TO ARND 3-5KT OVERNIGHT...THEN BEGIN TO TURN SLIGHTLY TO
THE SOUTHEAST. A FEW LOCATIONS COULD SEE SOME PATCHY GROUND FOG
DEVELOP AGAIN OVERNIGHT...HOWEVER THIS SHOULD BE LIMITED AND NOT
IMPACT THE TAF SITES. THEN AFTER DAYBREAK SATURDAY WINDS WILL
SLOWLY INCREASE FROM THE SOUTHEAST/EAST TO ARND 10KT.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT-MONDAY...VFR.
TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF
STORMS WED NIGHT.
THURSDAY...VFR.
MTF
&&
.MARINE...
306 AM CDT
HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO
NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS
OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL
STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS.
THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED
SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON
SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES
LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF
THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON
NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS
LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE
MIDWEEK PERIOD.
MTF
&&
.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:
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Area Forecast Discussion
National Weather Service Lincoln IL
1216 PM CDT Fri Aug 23 2013
.DISCUSSION...
ISSUED 949 AM CDT Fri Aug 23 2013
Areas of dense fog north of I-74 has been lifting into a stratus
deck this morning, and should continue to thin from the edges over
the next couple hours as diurnal mixing increases. Otherwise, high
pressure north of Lake Superior will bring a 5-10 mph northeast
wind flow to the region causing dewpoints will gradually fall into
the low/mid 60s from north to south by late afternoon. Subsidence
on the south side of the ridge should provide mostly sunny skies
and seasonable highs in the mid 80s.
&&
.AVIATION...
ISSUED 1216 PM CDT Fri Aug 23 2013
High pressure over the northern Great Lakes will bring mostly
clear skies and east winds under 10 kts to the terminals through
18z/Sat. MVFR fog will be possible within a few hours of sunrise.
25
&&
.PREV DISCUSSION...
ISSUED 240 AM CDT Fri Aug 23 2013
SHORT TERM...Today through Saturday...
Initial frontal passage has taken place over all of central and
southeast Illinois early this morning, but drier air lingers a bit
further back as lower 60s dew points now starting to enter the far
northern CWA. A cluster of thunderstorms developed from
Springfield to Decatur along the remnants of an old boundary from
earlier, in an area with MUCAPE`s of around 1000 J/kg, and the
cluster has been increasing a bit over the last hour or so as it
moves south-southeast. Latest model guidance suggesting scattered
showers/storms through about mid morning over about the southeast
third of the forecast area.
Further north, fog has been thickening and increasing over the
northeast third of the state, where skies have cleared and the
drier air has arrived. So far visibilities in our area have been
staying up as a band of altocumulus has persisted, but clearing
has been taking place from Galesburg to Lacon. However, the lower
visibilities have been in areas that had quite a bit of rain on
Thursday, and much of our forecast area had a quarter inch or less
except in isolated spots. So, the question is how much of the
forecast area, if any, will see dense fog this morning. HRRR
guidance is the most pessimistic with it fairly widespread along
and north of I-74, while the most recent RAP has scaled back and
went mainly patchy dense fog in the same area. Currently have
mention of 1/2 mile visibility in fog in this area through about 9
am, but will have to monitor for any significant advection from
the northeast.
Once the fog and rain moves out, quiet weather expected through
the first part of the weekend. High pressure drifting through the
Great Lakes will advect some drier air in from the east, but
should still see highs in the mid-upper 80s.
LONG TERM...Sunday through Thursday...
Main weather story over the coming week continues to be with the
expanding heat over the center of the nation, as a large dome of
high pressure aloft drifts eastward. Any MCS ridge riders will be
well to our north, and will continue the dry forecast for next
week. Highs to rise through the 90s much of the week as thermal
ridge builds eastward. Core of this ridge will be in the area on
Wednesday. Latest ECMWF showing upper 90s over most of the
forecast area that day. Have continued to trend temperatures up a
degree or two from blended guidance with mid 90s widespread on
Wednesday. Heat index values of just over 100 likely across the
western CWA Monday-Tuesday and everywhere Wednesday. On Thursday,
the thermal ridge starts shifting westward again, but should still
see highs in the 93-95 range.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1114 AM CDT FRI AUG 23 2013
.DISCUSSION...
352 AM CDT
SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE
GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH
HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE.
TODAY...
HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT
CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES
OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED
IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE
EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG
DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO
BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH
HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS
WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN
THE UPPER 70S TO AROUND 80.
REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE
BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG
THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE
MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE
COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL
THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY
TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM
THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM.
SATURDAY THROUGH MONDAY...
THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO
SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL
PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH
PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT
INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE
SOUTHEAST ATLANTIC COAST MONDAY NIGHT.
MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE
RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT.
ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE
NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS
DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH
AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST.
HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT
CWA.
UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON
MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY
REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE
DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING.
THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT
INDICES IN THE UPPER 90S TO AROUND 100.
LONG TERM...TUESDAY THROUGH THURSDAY...
THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A
BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION.
GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK
AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL
EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND
EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH
TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING
IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL
TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON
WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT.
A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY
INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED.
TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER
CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* NE/ENE WINDS AROUND 10 KT MAY INCREASE TO 12-14KT BY EARLY THIS
AFTERNOON.
BEACHLER
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE UPPER
MISSISSIPPI VALLEY. DRIER AIR OOZING IN FROM THIS HAS HELPED TO
ABATE THE FOG ACROSS MOST OF THE TAF SITES EARLY THIS MORNING.
SOME STRATUS ACROSS GYY AND JUST SOUTH OF MDW SHOULD QUICKLY TURN
INTO A CU FIELD THIS MORNING. THE HIGH WILL TRANSLATE SLOWLY EAST
THROUGH THE TAF PERIOD. WINDS WILL PICK UP DURING THE MID TO LATE
MORNING WITH THE VAD WIND PROFILE INDICATING 10-15KT WITHIN 2000
FT OF THE SURFACE. THE WINDS WILL BE OFF THE LAKE AS WELL...AND
CLIMATOLOGY POINTS TO THE DIRECTION BEING CLOSER TO ENE OR EVEN E
BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY COME THIS EVE. FOG
WILL BE LESS OF A THREAT TONIGHT DUE TO DRYING IN THE LOW-
LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE
AREAS THAT SAW MORE OF AN APPRECIABLE RAIN DURING THURSDAY /LIKE
RFD/.
MTF
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE THAT BROKEN STRATUS WILL STAY JUST SOUTH OF
MDW.
* MEDIUM CONFIDENCE IN WIND SPEEDS STAY AOB 10KT TODAY.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT-MONDAY...VFR.
TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF
STORMS WED NIGHT.
THURSDAY...VFR.
MTF
&&
.MARINE...
306 AM CDT
HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO
NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS
OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL
STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS.
THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED
SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON
SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES
LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF
THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON
NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS
LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE
MIDWEEK PERIOD.
MTF
&&
.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:
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Area Forecast Discussion
National Weather Service Lincoln IL
950 AM CDT Fri Aug 23 2013
.DISCUSSION...
ISSUED 949 AM CDT Fri Aug 23 2013
Areas of dense fog north of I-74 has been lifting into a stratus
deck this morning, and should continue to thin from the edges over
the next couple hours as diurnal mixing increases. Otherwise, high
pressure north of Lake Superior will bring a 5-10 mph northeast
wind flow to the region causing dewpoints will gradually fall into
the low/mid 60s from north to south by late afternoon. Subsidence
on the south side of the ridge should provide mostly sunny skies
and seasonable highs in the mid 80s.
25
&&
.AVIATION...
ISSUED 657 AM CDT Fri Aug 23 2013
Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
Patchy fog/stratus may briefly cause MVFR/IFR conditions for a
couple hours this morning, but otherwise cloud cover should be
minimal. While light fog can not be ruled out overnight tonight,
the drier air filtering into the area around the south side of a
an area high pressure should keep the risk to a minimum.
Bak
&&
.PREV DISCUSSION...
ISSUED 240 AM CDT Fri Aug 23 2013
SHORT TERM...Today through Saturday...
Initial frontal passage has taken place over all of central and
southeast Illinois early this morning, but drier air lingers a bit
further back as lower 60s dew points now starting to enter the far
northern CWA. A cluster of thunderstorms developed from
Springfield to Decatur along the remnants of an old boundary from
earlier, in an area with MUCAPE`s of around 1000 J/kg, and the
cluster has been increasing a bit over the last hour or so as it
moves south-southeast. Latest model guidance suggesting scattered
showers/storms through about mid morning over about the southeast
third of the forecast area.
Further north, fog has been thickening and increasing over the
northeast third of the state, where skies have cleared and the
drier air has arrived. So far visibilities in our area have been
staying up as a band of altocumulus has persisted, but clearing
has been taking place from Galesburg to Lacon. However, the lower
visibilities have been in areas that had quite a bit of rain on
Thursday, and much of our forecast area had a quarter inch or less
except in isolated spots. So, the question is how much of the
forecast area, if any, will see dense fog this morning. HRRR
guidance is the most pessimistic with it fairly widespread along
and north of I-74, while the most recent RAP has scaled back and
went mainly patchy dense fog in the same area. Currently have
mention of 1/2 mile visibility in fog in this area through about 9
am, but will have to monitor for any significant advection from
the northeast.
Once the fog and rain moves out, quiet weather expected through
the first part of the weekend. High pressure drifting through the
Great Lakes will advect some drier air in from the east, but
should still see highs in the mid-upper 80s.
LONG TERM...Sunday through Thursday...
Main weather story over the coming week continues to be with the
expanding heat over the center of the nation, as a large dome of
high pressure aloft drifts eastward. Any MCS ridge riders will be
well to our north, and will continue the dry forecast for next
week. Highs to rise through the 90s much of the week as thermal
ridge builds eastward. Core of this ridge will be in the area on
Wednesday. Latest ECMWF showing upper 90s over most of the
forecast area that day. Have continued to trend temperatures up a
degree or two from blended guidance with mid 90s widespread on
Wednesday. Heat index values of just over 100 likely across the
western CWA Monday-Tuesday and everywhere Wednesday. On Thursday,
the thermal ridge starts shifting westward again, but should still
see highs in the 93-95 range.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1246 PM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 1240 PM CDT FRI AUG 23 2013
BASED ON TRENDS UP THROUGH MID DAY...THE POTENTIAL FOR ANY DIURNAL
CONVECTION IN THE FAR WEST/SOUTHWEST PARTS OF THE CWFA IS BECOMING
DOUBTFUL.
SATELLITE SHOWS DIURNAL CLOUDS DEVELOPING INDICATING THE BETTER
MOISTURE IS GENERALLY WEST OF THE CWFA. ADDITIONALLY...CONVECTIVE
TEMPERATURES FROM TRENDS IN THE RAP ARE GENERALLY AT OR ABOVE THE
FCST MAX TEMPERATURES FOR THE AFTERNOON. THUS DRY CONDITIONS
SHOULD BE SEEN THIS AFTERNOON AND EVENING. ..08..
UPDATE ISSUED AT 1003 AM CDT FRI AUG 23 2013
THE FOG HAS BURNED OFF AND THE LOW CLOUDS WILL CONTINUE LIFT
THROUGH EARLY AFTERNOON.
RAIN CHANCES DO NOT LOOK OVERLY GREAT FOR THE AFTERNOON HOURS. THE
BETTER MOISTURE LIES JUST WEST OF THE CWFA AS DOES THE PROJECTED
CONVERGENCE. THE EARLY MORNING FOG HAS ALSO STABILIZED THE WESTERN
CWFA SO IT WILL TAKE LONGER TO GENERATE THERMALS. WHAT IS BEING
SUGGESTED BY THE MODELS IS ISOLATED TO PERHAPS VERY LOW END
SCATTERED SHOWERS AND SOME STORMS IN THE EXTREME WESTERN/SOUTHWEST
PARTS OF THE CWFA DURING PEAK HEATING. IF THIS CONVECTION
DEVELOPS...IT WILL DISSIPATE WITH SUNSET. ..08..
&&
.SYNOPSIS...
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN
THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST.
AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN
ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED
ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20
CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE
1+ INCHES OF RAIN FELL YESTERDAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 318 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED
DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED
IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING
OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG
AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON.
ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN
WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA
OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA
THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE
RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE
STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA
THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS
IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR
AREA THIS AFTERNOON.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 318 AM CDT FRI AUG 23 2013
UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED
PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK.
THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY...
WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH
THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL
LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF
PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE
THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS
AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE
CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S.
SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE
AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK.
OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER
HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS
TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR
NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE
SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24
C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S.
SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES
SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES
TOPPING OUT IN THE UPPER 80S TO AROUND 90.
MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE
THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE
FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND
POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL
KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH
THU.
HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH
ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU.
THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS...
WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE
MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY
SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR
EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL
CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED
FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1240 PM CDT FRI AUG 23 2013
VFR WX IS EXPECTED THROUGH 06Z/24 AS HIGH PRESSURE REMAINS OVER
THE GREAT LAKES. AFT 06Z/24 INCREASING LOW LEVEL MOISTURE SHOULD
ALLOW MVFR VSBYS TO DEVELOP PRIOR TO SUNRISE. AFT SUNRISE SATURDAY
CONDITIONS WILL AGAIN IMPROVE TO VFR. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...SHEETS
AVIATION...08
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
549 PM CDT Fri Aug 23 2013
...Updated for Aviation...
.SYNOPSIS...
ISSUED AT 1208 PM CDT FRI AUG 23 2013
At 12z Friday a 500mb trough was located over northern California
and the pacific northwest. A 500mb high was located across western
Oklahoma. An upper level ridge axis extended from this upper high
northward into south central Canada. 700mb temperatures at 12z
this morning across the central high plains ranged from 11c at
Dodge City and North Platte to +16c at Denver. A 850mb BAROCLINIC
zone extended from southwest Nebraska to northeast Oklahoma.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 202 PM CDT FRI AUG 23 2013
Water Vapor loop indicating an upper level disturbance was moving
north across east central Colorado earlier this morning. The 12z
RAP, NAM,and GFS 400-450mb potential vorticity field picked up on
this feature fairly well and currently moves this feature across
northern Kansas early this evening. NAM and to a lesser degree RAP
and HRRR even hints at some precipitation this evening near and
north of I70 as this wave passes. Given the late day instability
expected ahead of this wave the chance for an isolated
thunderstorm or two can not be ruled out...especially near the
Nebraska border. At this time am leaning towards leaving mention
of thunderstorms out of the forecast near the interstate 70
corridor given the better instability and forcing is forecast to
be further north. Will however insert a mention of isolated
thunderstorms if convection appears to be developing further south
than anticipated.
Skies are expected to clear from west to east as this upper wave
passes north central Kansas after midnight. Given surface
dewpoints in the 60s and surface winds at 10kts will stay close
to the previous forecast with overnight ranging from the mid 60s
in far western Kansas to around 70 in north central and south
central Kansas.
On Saturday an upper high will slowly move east across southwest
Kansas and 800mb temperatures at 00z Sunday are forecast range
from 24c to 28c. This suggests highs Saturday afternoon mainly in
the mid 90s given full sun.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 340 PM CDT FRI AUG 23 2013
The medium range forecast models continue to develop a large broad
upper height ridge across the central section of the nation through
next weekend. This will promote large scale subsidence aloft and
southerly surface winds across western Kansas. Although technically
not zero percent, very little chance for convection is expected
during this period. The only opportunity for convection would be
late evening or overnight near the Colorado line as localized high
terrain convection can feed on steep mid level lapse rates far
enough east. The flow however doesn`t support this. Beside the lack
of precipitation, the period will be marked by a few breezy to
marginally windy days and very warm conditions. High surface
pressure across the eastern states will setup a pressure gradient to
the lee of the Rockies creating diurnally mixed out gusty south winds.
The models in addition to the MOS products have trended temperatures
warmer in recent runs. Highs during the period will likely be at
least 5 degrees to as much as 10 degrees warmer than normal.
Persistence or intensification of the drought conditions are
expected to the west of highway 283.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 545 PM CDT FRI AUG 23 2013
VFR conditions will continue into Saturday with light south to
southeast winds increasing to 15-25kt after 15-17Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 68 95 72 96 / 0 0 0 0
GCK 67 96 71 96 / 0 0 0 0
EHA 66 94 70 94 / 0 0 0 0
LBL 66 96 72 96 / 0 0 0 0
HYS 70 96 72 97 / 10 0 0 0
P28 71 95 73 96 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Burgert
SHORT TERM...Burgert
LONG TERM...Russell
AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
341 PM CDT Fri Aug 23 2013
...UPDATED LONG TERM...
.SYNOPSIS...
ISSUED AT 1208 PM CDT FRI AUG 23 2013
At 12z Friday a 500mb trough was located over northern California
and the pacific northwest. A 500mb high was located across western
Oklahoma. An upper level ridge axis extended from this upper high
northward into south central Canada. 700mb temperatures at 12z
this morning across the central high plains ranged from 11c at
Dodge City and North Platte to +16c at Denver. A 850mb baroclinic
zone extended from southwest Nebraska to northeast Oklahoma.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 202 PM CDT FRI AUG 23 2013
Water Vapor loop indicating an upper level disturbance was moving
north across east central Colorado earlier this morning. The 12z
RAP, NAM,and GFS 400-450mb potential vorticity field picked up on
this feature fairly well and currently moves this feature across
northern Kansas early this evening. NAM and to a lesser degree RAP
and HRRR even hints at some precipitation this evening near and
north of I70 as this wave passes. Given the late day instability
expected ahead of this wave the chance for an isolated
thunderstorm or two can not be ruled out...especially near the
Nebraska border. At this time am leaning towards leaving mention
of thunderstorms out of the forecast near the interstate 70
corridor given the better instability and forcing is forecast to
be further north. Will however insert a mention of isolated
thunderstorms if convection appears to be developing further south
than anticipated.
Skies are expected to clear from west to east as this upper wave
passes north central Kansas after midnight. Given surface
dewpoints in the 60s and surface winds at 10kts will stay close to
the previous forecast with overnight ranging from the mid 60s in
far western Kansas to around 70 in north central and south central
Kansas.
On Saturday an upper high will slowly move east across southwest
Kansas and 800mb temperatures at 00z Sunday are forecast range
from 24c to 28c. This suggests highs Saturday afternoon mainly in
the mid 90s given full sun.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 340 PM CDT FRI AUG 23 2013
The medium range forecast models continue to develop a large broad
upper height ridge across the central section of the nation through
next weekend. This will promote large scale subsidence aloft and
southerly surface winds across western Kansas. Although technically
not zero percent, very little chance for convection is expected
during this period. The only opportunity for convection would be
late evening or overnight near the Colorado line as localized high
terrain convection can feed on steep mid level lapse rates far
enough east. The flow however doesn`t support this. Beside the lack
of precipitation, the period will be marked by a few breezy to
marginally windy days and very warm conditions. High surface
pressure across the eastern states will setup a pressure gradient to
the lee of the Rockies creating diurnally mixed out gusty south winds.
The models in addition to the MOS products have trended temperatures
warmer in recent runs. Highs during the period will likely be at
least 5 degrees to as much as 10 degrees warmer than normal.
Persistence or intensification of the drought conditions are
expected to the west of highway 283.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1208 PM CDT FRI AUG 23 2013
VFR conditions can be expected through tonight at all TAF sites. As
surface troughing persist on the lee side of the Rockies, winds will
remain southerly this afternoon and evening from 10 to 15 kt. A few
gusts around 25 kt could be possible this afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 68 95 72 96 / 0 0 0 0
GCK 67 96 71 96 / 0 0 0 0
EHA 66 94 70 94 / 0 0 0 0
LBL 66 96 72 96 / 0 0 0 0
HYS 70 96 72 97 / 10 0 0 0
P28 71 95 73 96 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Burgert
SHORT TERM...Burgert
LONG TERM...Russell
AVIATION...Scott
AREA FORECAST DISCUSSION
NWS GOODLAND KS
158 PM MDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 559 AM MDT FRI AUG 23 2013
JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE
OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT
CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE
SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT
CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS
TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST
HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER
SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL
STAY CONSERVATIVE WITH THIS UPDATE.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 251 AM MDT FRI AUG 23 2013
LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER
THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED
FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO
THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY
THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH
GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM
LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT
HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS
NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA.
WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS
INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD
AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY
NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT
RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER
IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF
OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS.
OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE
HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH
VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG
DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE
INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS
BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS
NORTHERN PART OF CWA THIS MORNING.
AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH
SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE
OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH
WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS
EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR
CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE
UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS
FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON
AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG
CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT
WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT
WE WILL NEED TO MONITOR.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 158 PM MDT FRI AUG 23 2013
SATURDAY NIGHT-MONDAY...596 DM H5 RIDGE WILL BE THE DOMINANT FEATURE
IN PLACE ACROSS MUCH OF THE AREA WITH THE RIDGE CENTER EXPECTED TO
GRADUALLY RETROGRADE THROUGH THE PERIOD. PRESENCE OF LARGE AREA OF
SUBSIDENCE AND ONLY WEAK AFTERNOON INSTABILITY PROFILES LEADS ME TO
THINK QUIET WEATHER WILL CONTINUE THROUGH THE PERIOD WITH MAIN AREA
OF CONCERNS BEING TEMPERATURES AND POSSIBLY FIRE WEATHER CONCERNS
WITH THE DRY CONDITIONS.
TEMPERATURES WILL WARM THROUGH THE PERIOD WITH SFC TROUGH EXPECTED
TO KEEP WINDS UP DURING THE OVERNIGHT HOURS WHICH WILL GIVE
TEMPERATURES A RUNNING START EACH DAY AS RADIATIONAL COOLING WILL BE
SOMEWHAT INHIBITED. LOOKS LIKE MID/UPPER 90S TO NEAR 100 CAN BE
EXPECTED BY MONDAY ALTHOUGH RECENT VERIFICATION INDICATES VARIOUS
TEMP FORECASTS HAVE BEEN ON THE WARM SIDE THINGS WHICH DOES LOWER
CONFIDENCE A BIT. GUSTY SOUTHERLY WINDS EXPECTED EACH AFTERNOON AS
SFC TROUGH REMAINS NEARLY STATIONARY. WARM TEMPS WILL HELP PUSH
HUMIDITIES DOWN TO AROUND 20 PERCENT...BUT MIXED LEVEL FORECASTS DO
NOT SUPPORT A STRONG DROP IN DEWPOINTS AT THIS TIME SO POTENTIAL FOR
A CRITICAL FIRE WEATHER DAY APPEAR TO BE LOW.
IN THE EXTENDED (MON NIGHT-FRI)...GENERAL CONSENSUS OF MEDIUM RANGE
MODELS SUPPORTS STRONG H5 RIDGE RETROGRADING SLIGHTLY WITH RIDGE
CENTER NEARING THE CWA AND PERSISTING THERE THROUGH THE WEEK.
CONTINUED WARM AND DRY CONDITIONS CAN BE EXPECTED AND WILL HAVE TO
WATCH WIND SPEEDS CLOSELY AS HUMIDITIES WILL NEAR CRITICAL FIRE
WEATHER VALUES EACH AFTERNOON.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1100 AM MDT FRI AUG 23 2013
VFR CONDITIONS EXPECTED AT KGLD AND KMCK. A MESOSCALE CONVECTIVE
VORTICE...LEFTOVER FROM SHOWERS AND THUNDERSTORMS ACROSS THE
COLORADO FRONT RANGE YESTERDAY...IS SPINNING OVER THE AREA THIS
MORNING. THIS SYSTEM IS EXPECTED TO CONTINUE TO SLOWLY MOVE
EAST/NORTHEAST THROUGH THE REST OF THE DAY EXITING THE AREA EARLY
TONIGHT. THE COMBINATION OF DIURNAL HEATING AND THIS DISTURBANCE
SHOULD PRODUCE SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EARLY EVENING. MOST LIKELY LOCATION TO POTENTIALLY BE IMPACTED
WOULD BE KMCK. HOWEVER...CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN
TAF AT PRESENT TIME. OTHERWISE...BOTH TERMINALS CAN EXPECT AN
INCREASE IN WINDS THIS AFTERNOON AND EVENING WHERE GUSTS AROUND
20KTS POSSIBLE. SOUTHERLY WINDS WILL INCREASE IN SPEED DURING THE
DAY SATURDAY WITH GUSTS OF 25-30KTS POSSIBLE AT BOTH TERMINALS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...DR
LONG TERM...JRM
AVIATION...99
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
204 PM CDT Fri Aug 23 2013
...Updated Short term discussion...
.SYNOPSIS...
ISSUED AT 1208 PM CDT FRI AUG 23 2013
At 12z Friday a 500mb trough was located over northern California
and the pacific northwest. A 500mb high was located across western
Oklahoma. An upper level ridge axis extended from this upper high
northward into south central Canada. 700mb temperatures at 12z
this morning across the central high plains ranged from 11c at
Dodge City and North Platte to +16c at Denver. A 850mb baroclinic
zone extended from southwest Nebraska to northeast Oklahoma.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 202 PM CDT FRI AUG 23 2013
Water Vapor loop indicating an upper level disturbance was moving
north across east central Colorado earlier this morning. The 12z
RAP, NAM,and GFS 400-450mb potential vorticity field picked up on
this feature fairly well and currently moves this feature across
northern Kansas early this evening. NAM and to a lesser degree RAP
and HRRR even hints at some precipitation this evening near and
north of I70 as this wave passes. Given the late day instability
expected ahead of this wave the chance for an isolated
thunderstorm or two can not be ruled out...especially near the
Nebraska border. At this time am leaning towards leaving mention
of thunderstorms out of the forecast near the interstate 70
corridor given the better instability and forcing is forecast to
be further north. Will however insert a mention of isolated
thunderstorms if convection appears to be developing further south
than anticipated.
Skies are expected to clear from west to east as this upper wave
passes north central Kansas after midnight. Given surface
dewpoints in the 60s and surface winds at 10kts will stay close to
the previous forecast with overnight ranging from the mid 60s in
far western Kansas to around 70 in north central and south central
Kansas.
On Saturday an upper high will slowly move east across southwest
Kansas and 800mb temperatures at 00z Sunday are forecast range
from 24c to 28c. This suggests highs Saturday afternoon mainly in
the mid 90s given full sun.
.LONG TERM...(Saturday through Thursday)
ISSUED AT 226 AM CDT FRI AUG 23 2013
For the extended period from Saturday night through next Friday,
very little has change has shown up in the medium and long range
models. A upper level high pressure area will essentially be
anchored over the Sunflower State through the foreseeable future.
This upper high will bring a lot of sunshine to western Kansas,
resulting in afternoon highs in the mid to upper 90s. Will the 100F
degree mark be reached? Possibly by Wednesday or beyond. The
prolonged pattern of upper high pressure and a long southwest fetch
of warming winds at the surface may be just enough for a couple of
spots in western Kansas to peak near or over 100F. For now, have
accepted what the CR_Extended tool produced, with 97F-98F max temps
ranges. The only clouds expected through Friday are mid and high
level in nature. These clouds will not alter or slow down the
surface heating. Furthermore, a lee side trough will form each
afternoon across eastern Colorado, and will edge eastward nearly
every day into western Kansas. Unfortunately, there will be little
or no substantial moisture to work with, and thus there are no
precipitation chances included in the extended period.
Minimum temperatures will basically be in the lower to mid 70s, but
creep slowly upward with time. By Friday, expect lows in the mid
70s in our eastern zones of Barber, Comanche and Pratt counties, and
around the 70F degree mark along the Colorado border. In general,
winds will be from the south to southwest, dipping to 10 to 15 mph
overnight, and then increasing by late mornings into the 15 to 25
mph and gusty range.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1208 PM CDT FRI AUG 23 2013
VFR conditions can be expected through tonight at all TAF sites. As
surface troughing persist on the lee side of the Rockies, winds will
remain southerly this afternoon and evening from 10 to 15 kt. A few
gusts around 25 kt could be possible this afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 69 94 72 94 / 0 0 0 0
GCK 68 94 71 95 / 0 0 0 0
EHA 64 94 70 93 / 0 0 0 0
LBL 67 95 72 95 / 0 0 0 0
HYS 70 94 72 95 / 0 0 0 0
P28 71 94 73 94 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Burgert
SHORT TERM...Burgert
LONG TERM...Burke
AVIATION...Scott
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1220 PM CDT Fri Aug 23 2013
.SHORT TERM...(Today and Tonight)
Issued at 335 AM CDT FRI AUG 23 2013
A broad upper level ridge of high pressure will be centered over the
state of Kansas for the next 24 hours.
early this morning, elevated showers were developing due to weak
isentropic lift north of an old outflow boundary across west central
KS. At this time I think the showers should remain just west of the
cwa...though some isolated showers may develop near sunrise across
the southwest and northern counties of the CWA, but should dissipate
by mid morning. May place a 10 to 14 pop across the southwest and
northern counties in case any isolated showers develop.
Widespread convection along the foothills of CO will cause periods
of high clouds to move across the CWA Today. The 06Z NAM is the only
numerical model that breaks out deep moist convection across north
central KS late this afternoon and into the early evening hours. The
NAM may be trying to bring the MCV from the CO foothill convective
complex too far south across the center of the H5 ridge axis. The
GFS, arw, nmm and RAP show the the mcv rotating farther northeast
across western and central NE and show no qpf developing across
north central KS this afternoon. Just in case the NAM solution may
be accurate I inserted 10 to 14 pops for late this afternoon and
early evening across the northwest counties of the CWA.
High temperatures Today may be dependent on the amount of high
clouds. if the high clouds thin out this afternoon then highs will
reach into the lower to mid 90s. If we keep a thicker veil of high
clouds through the afternoon hours, then highs may only reach the
upper 80s to around 90.
Tonight, if any showers or isolated thunderstorms develop across
north central KS they should dissipate after sunset. skies should
become mostly clear through the night. overnight lows will drop into
the upper 60s to lower 70s.
.LONG TERM...(Saturday through Thursday)
Issued at 335 AM CDT FRI AUG 23 2013
Medium range models are very similar in building upper ridge
eastward through the weekend with axis over MO before retrogressing
slightly and amplifying across KS through most of next week. This
will allow for only weak inhibition by peak heating over the
weekend...but a strengthening cap into next week. However with the
exception of diurnal heating...no significant forcing evident to
warrant any pops at this point...and even less confidence into next
week. Therefore will keep the fcst through the extended dry. The
llvl thermal fields only warm slightly from the weekend into the
middle of next week...so the current fcst of only minor high temp
increases thru the middle 90s into next week looks good for now.
There is some concern that soil conditions steadily drying out and
some hint of more veering llvl windfields by the middle of next week
could lead to higher temps in the western cwa. A slight increase in
dewpoints into next week with the slightly warmer temps should inch
heat indices to around the century mark for most areas through next
week.
&&
.AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon)
Issued at 1216 PM CDT FRI AUG 23 2013
Will keep vfr conditions through the period and monitor for some
outside chances for convection toward the end of the taf cycle,
but at this time seems to stay north of the terminals. 67
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...67
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1100 AM MDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 559 AM MDT FRI AUG 23 2013
JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE
OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT
CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE
SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT
CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS
TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST
HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER
SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL
STAY CONSERVATIVE WITH THIS UPDATE.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 251 AM MDT FRI AUG 23 2013
LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER
THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED
FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO
THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY
THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH
GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM
LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT
HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS
NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA.
WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS
INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD
AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY
NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT
RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER
IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF
OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS.
OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE
HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH
VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG
DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE
INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS
BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS
NORTHERN PART OF CWA THIS MORNING.
AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH
SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE
OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH
WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS
EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR
CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE
UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS
FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON
AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG
CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT
WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT
WE WILL NEED TO MONITOR.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 251 AM MDT FRI AUG 23 2013
WHILE THE PAST FEW EXTENDED RANGE FORECASTS HAVE SOUNDED LIKE A
BROKEN RECORD - HOT AND DRY - IT APPEARS AN END IS IN SIGHT. EARLY
NEXT WEEK AN UPPER LEVEL RIDGE WILL BE CENTERED OVER KANSAS...WITH A
A NORTH-SOUTH ORIENTED SURFACE TROUGH DEVELOP ALONG EASTERN
COLORADO. THE ECMWF HAD PREVIOUSLY BEEN A BIT MORE CONSERVATIVE WITH
TEMPS BUT NOW HAS COME AROUND TO BETTER MATCH THE GFS AND GEM WITH
TEMPS IN THE LOW 30S C...TRANSLATING TO MID TO UPPER 90S IN THE
FIRST HALF OF THE WEEK. TRIPLE-DIGIT TEMPS LOOK ALMOST LIKELY ON
MONDAY AND TUESDAY FOR THE NORMAL HOT SPOTS...PLACES LIKE
TRIBUNE...HILL CITY...AND MCCOOK...APPROACHING /BUT PROBABLY NOT
EXCEEDING/ RECORDS IN SOME SPOTS. LATER IN THE WEEK THE RIDGE WILL
SLOWLY NUDGE FARTHER EAST BRINGING RELIEF TO THE HEAT...SOMETHING
THE OPERATIONAL GFS IS A BIT SLOW TO REALIZE BUT THE GEFS MEAN AND
ECMWF HAVE BEEN CONSISTENT WITH THE PAST FEW RUNS. PRECIP CHANCES
ARE NEAR NIL WITH THE RIDGE OVER US...BUT AS IT MOVES EAST WE COULD
SEE CHANCES INCREASE TOWARDS THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1100 AM MDT FRI AUG 23 2013
VFR CONDITIONS EXPECTED AT KGLD AND KMCK. A MESOSCALE CONVECTIVE
VORTICE...LEFTOVER FROM SHOWERS AND THUNDERSTORMS ACROSS THE
COLORADO FRONT RANGE YESTERDAY...IS SPINNING OVER THE AREA THIS
MORNING. THIS SYSTEM IS EXPECTED TO CONTINUE TO SLOWLY MOVE
EAST/NORTHEAST THROUGH THE REST OF THE DAY EXITING THE AREA EARLY
TONIGHT. THE COMBINATION OF DIURNAL HEATING AND THIS DISTURBANCE
SHOULD PRODUCE SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EARLY EVENING. MOST LIKELY LOCATION TO POTENTIALLY BE IMPACTED
WOULD BE KMCK. HOWEVER...CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN
TAF AT PRESENT TIME. OTHERWISE...BOTH TERMINALS CAN EXPECT AN
INCREASE IN WINDS THIS AFTERNOON AND EVENING WHERE GUSTS AROUND
20KTS POSSIBLE. SOUTHERLY WINDS WILL INCREASE IN SPEED DURING THE
DAY SATURDAY WITH GUSTS OF 25-30KTS POSSIBLE AT BOTH TERMINALS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...DR
LONG TERM...JJM
AVIATION...99
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
328 PM CDT FRI AUG 23 2013
.SYNOPSIS...
ISSUED AT 326 PM CDT FRI AUG 23 2013
RAP H5 ANALYSIS THIS AFTERNOON SHOWS HEIGHT RISES DOMINATING THE
CENTRAL CONUS...AS THE UPPER HIGH THAT WILL BE BRINGING US THE HEAT
WAVE COME SUNDAY IS STARTING TO STRENGTHEN OVER KANSAS...WITH THE
RIDGE AXIS BUILDING NORTH INTO THE RED RIVER VALLEY. WATER VAPOR
SHOWS A COUPLE OF WEAK WAVE ACROSS THE DAKOTAS THAT WILL BE
ROUNDING THE TOP OF THE RIDGE TONIGHT.
AT THE SFC...HIGH PRESSURE HAS NOW MOVED INTO THE GREAT LAKES...WITH
RETURN FLOW BECOMING ESTABLISHED ACROSS THE AREA. FRONT THAT SETTLED
ALONG THE IOWA BORDER THURSDAY HAS COMPLETELY WASHED OUT...WITH THE
HIGH DEWPOINTS THAT HAD POOLED OVER IOWA LAST NIGHT NOW SURGING
NORTH ON THE SOUTH WINDS...WITH CU FIELD MOVING NORTH OUT OF SRN MN
ALSO DENOTING WHERE DEWPOINT GO FROM THE 50S BACK UP TO THE UPPER
60S TO AROUND 70.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 326 PM CDT FRI AUG 23 2013
MAIN CONCERN RIGHT OFF THE BAT WILL BE THE POTENTIAL FOR
THUNDERSTORMS WITHIN THE NEXT COUPLE OF HOURS OVER SW MN. 19Z SPC
MESOANALYSIS SHOWS A BUBBLE OF 3000-4000 J/KG OF MLCAPE HAS
DEVELOPED IN THE MN/SD/NEB/IA BORDERS REGION. IN ADDITION...LLJ AND
ASSOCIATED MOISTURE TRANSPORT IS BEGINNING TO INCREASE ACROSS NE NEB
AND SE SODAK. IN THIS REGION...THE HRRR ALONG WITH ALL MEMBERS OF
THE 15Z HOPWRF SHOW AN AREA OF SCT TSTMS DEVELOPING AROUND SIOUX
FALLS...THEN DRIFTING NNE TOWARD THE UPPER MN RIVER VALLEY. HAVE
SOME ISO THUNDER WORDING OUT THERE BETWEEN 22 AND 02Z AS A RESULT.
INTERESTINGLY...BOTH THE HRRR AND HOPWRF SHOW THIS ACTIVITY BEING
DIURNALLY DRIVEN...WITH IT MOSTLY DISSIPATED BY 03Z.
FOR TONIGHT...STILL LOTS OF UNCERTAINTY AS TO HOW THINGS WILL UNFOLD
FOR PRECIP AS WE GET INTO A WAA REGIME...BUT IT IS STARTING TO LOOK
UNLIKELY THAT MUCH IS SEEN. LOOKING AT TEMP/MOISTURE ADVECTION
AROUND THE H7 LEVEL...THE GFS/NAM SHOW TWO AREAS OF ENHANCED FORCING
IN THE REGION TONIGHT...ONE DOWN ACROSS IOWA AND THE OTHER UP ACROSS
NRN MN. THE 23.12 ECMWF ONLY HAS THE NRN FORCING SOURCE. GIVEN THAT
THE NOSE OF THE LLJ LOOKS TO BE DIRECTED INTO NRN MN...CONFIDENCE IS
HIGHEST IN SOMETHING TRACKING ACROSS NRN MN /PER THE NMM AND SPCWRF
REFLECTIVITY FORECASTS/. HOWEVER...GIVEN THE BROAD ZONE OF
WAA/MOISTURE TRANSPORT MOVING ACROSS THE AREA CAN NOT RULE OUT
GETTING SOME AT LEAST SCT SHRA/TSRA AS THE LLJ WORKS ACROSS THE AREA
OVERNIGHT INTO SATURDAY MORNING. FOR THE POP GRIDS...DID NUDGE THEM
DOWN SOME...AND ALSO SLOWED DOWN THE ERN PROGRESSION OF
THINGS...CLOSER TO A NAM TIMING. DURING THE DAY ON SATURDAY...A
STRONG CAPPING INVERSION WILL BE MOVING IN...WHICH SHOULD SHUT DOWN
THE PRECIP FOR MOST OF MN BY THE AFTERNOON...WITH CHANCES LINGERING
ACROSS WRN WI.
LAST QUESTION MARK FOR THIS FORECAST IS HOW WARM DO WE GET ON
SATURDAY. THIS WILL DEPEND HIGHLY ON HOW QUICKLY SKIES CAN CLEAR OUT
FROM WEST TO EAST FROM THE MORNING INTO THE AFTERNOON. ERN MN/WRN WI
WILL LIKELY ENJOY THE CLOUD COVER FOR A GOOD CHUNK OF THE
DAY...WHICH SHOULD HELP HOLD HIGHS BACK INTO LOW/MID 80S...THOUGH
WITH DEWPS UP AROUND 70...IT WON`T EXACTLY FEEL COMFORTABLE. OUT IN
WRN MN...CLOUDS SHOULD CLEAR OUT EARLY ENOUGH TO ALLOW THE RETURN OF
90S...THOUGH DEPENDING ON HOW QUICKLY THE SUN ARRIVES...THE WEST
COULD SEE HIGHS ANYWHERE FROM THE UPPER 80S /MORE CLOUDS/ TO THE
UPPER 90S /VERY LITTLE CLOUD COVER/.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 PM CDT FRI AUG 23 2013
MAIN CONCERN IN THE EXTENDED IS WELL ADVERTISED HEAT WAVE THAT IS
FORECAST TO BRING NEAR RECORD TEMPERATURES BEGINNING SUNDAY...AND
LASTING THROUGH AT LEAST THE MIDDLE OF THIS WEEK. THE LONG DURATION
OF THIS HEAT...WITH THE WARM OVERNIGHT MIN TEMPS IS THE REASON
BEHIND THE EXCESSIVE HEAT WATCH THAT WAS ISSUED EARLIER THIS
MORNING. MASS TEMPERATURE FIELDS FROM THE H925/H850 LAYER...TOGETHER
WITH THE 500MB HEIGHTS SUPPORT THIS HEAT WATCH...BUT IF ANY DEBRIS
CLOUDS FROM AN OVERNIGHT MCS SPREAD ACROSS THE REGION...OR IF THE
MCS ITSELF BUILDS TO THE SOUTH AS INDICATED BY THE GFS AND ECMWF
23.12...THEN FORECAST MAX TEMPERATURES WILL BE OVERDONE BY SEVERAL
DEGREES.
AT THE START OF THE PERIOD LOW LEVEL WARM AIR ADVECTION WITH
SOUTHWEST FLOW WILL BE WELL ESTABLISHED ACROSS THE CWA...SO HAVE
RAISED MIN TEMPERATURES SATURDAY NIGHT/SUNDAY MORNING. ALSO HAVE
INCREASED THE WINDS HIGHER THAN GUIDANCE AS WELL...ESPECIALLY ALONG
THE UPPER MINNESOTA RIVER VALLEY WHERE THE DOWNSLOPE COMPONENT OFF
THE BUFFALO RIDGE WILL ADD A FEW EXTRA KNOTS. THESE WARMER LOW
TEMPERATURES WILL TRANSLATE INTO AFTERNOON HIGHS IN THE MID TO UPPER
90S ON SUNDAY AS THE BOUNDARY LAYER MIXES UP TO 850MB AS SHOWN VIA
THE BUFR SOUNDINGS. ANOTHER RESULT OF THIS DEEP MIXING WILL BE
DEWPOINT DROPPING INTO THE MID 60S DURING THE AFTERNOON. IF THE NAM
23.12 VERIFIES...DEWPOINTS COULD FALL INTO THE UPPER 50S AT A FEW
LOCATIONS. USED THE MIXDOWN TOOL TOGETHER WITH BIAS CORRECTED MODEL
BLEND TO POPULATE BOTH T AND TD ON SUNDAY. LOOKING AHEAD...INCREASED
LOW LEVEL MOISTURE WILL BRING HIGHER TDS ON MONDAY WITH AFTERNOON
MAX TEMPS ONCE AGAIN IN THE MID TO UPPER 90S.
THIS WILL BE THE TREND THROUGH THE EXTENDED...WITH THE ONCE CAVEAT
BEING THE CONVECTIVE POTENTIAL. AS ALLUDED TO EARLIER...OVERNIGHT
CONVECTION WILL DEVELOP AS SHORTWAVES PERIODICALLY ROUND THE BASE
OF THE UPPER LEVEL RIDGE ACROSS THE INTERNATIONAL BORDER. THE 23.12Z
GFS AND ECMWF DEVELOP CONVECTION ACROSS THE ARROWHEAD SATURDAY
NIGHT...AND OVER LAKE SUPERIOR SUNDAY NIGHT...WITH THE SECOND
FEATURE BUILDING SOUTHWEST AS IT IS FED BY THE LOW LEVEL JET. A
SHORTWAVE THAT IS CURRENTLY LOCATED OFF THE BAJA PENINSULA IS
FORECAST TO MOVE ACROSS THE UPPER MIDWEST MONDAY NIGHT...AND PUSH A
FRONTAL BOUNDARY THROUGH CENTRAL MN AND NORTHERN WI. THIS ALSO COULD
GIVE SOME REPRIEVE FROM THE HEAT BY MID WEEK...BUT CONFIDENCE IN THE
SOUTHERN EXTEND OF THIS FRONTAL BOUNDARY IS LOW AT THIS TIME.
THEREFORE FEEL THE POTENTIAL FOR DANGEROUS HEAT WAVE MERITS THE
EXCESSIVE HEAT WATCH IN CENTRAL MN AND FAR WESTERN WI.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1238 PM CDT FRI AUG 23 2013
MOISTURE BEGINNING TO SURGE NORTH IN ERNEST...AS EVIDENCED BY CU
FIELD MOVING OUT OF SRN MN. MODEST INSTABILITY HAS DEVELOPED WITHIN
THIS MOIST PLUME OVER SRN MN...WITH THE HRRR CONTINUING TO
GENERATE AN AREA OF SCT TSTMS OVER SW MN THIS AFTERNOON. AS A
RESULT...INCLUDED A VCTS FOR RWF BETWEEN 22Z AND 01Z. STILL NOT
MUCH CONFIDENCE WITH HOW THINGS WILL UNFOLD TONIGHT INTO SATURDAY
MORNING WITH RESPECT TO TSTM CHANCES. BOTH THE NAM/GFS WARM AIR
AND MOISTURE ADVECTION AROUND 700 MB INDICATES A COUPLE OF AREAS
OF ENHANCED FORCING FOR TSTMS TONIGHT...ONE DOWN INTO IA AND THE
UP IN NRN MN...NICELY SPLITTING THE MPX AREA. BIG REASON FOR NOTHING
MORE THAN A VCSH MENTION STILL IS THAT BY THE END OF THE HOPWRF
AND HRRR /06Z TONIGHT/...NEITHER MODEL SHOWS ANYTHING DEVELOPING
NEAR MN/WI AT THAT POINT...VERY POSSIBLE THAT THIS BIT OF WARM
ADVECTION DOES NOT DO MUCH MORE THAN BRING IN A FIELD OF ACCUS.
CONFIDENCE IS BETTER WITH WINDS. LOW LEVEL WINDS ARE FORECAST TO
INCREASE DRAMATICALLY TONIGHT...AND ONCE MIXING PICKS UP ON
SATURDAY...SHOULD HAVE TO PROBLEM MIXING DOWN BETTER THAN 20 KT
GUSTS...WITH GUSTS OVER 30KTS NOT OUT OF THE QUESTION FOR WRN MN
BY THE AFTERNOON.
KMSP...LOW CONFIDENCE IN PRECIP POTENTIAL TONIGHT. AT THE VERY
LEAST...FAVORED THE LATER TIMING DEPICTED BY THE NAM. FOR WINDS
SATURDAY AFTERNOON...MIX DOWN TOOL ON THE NAM INDICATING GUSTS
OVER 30 KTS POSSIBLE DURING THE AFTERNOON...BUT THAT WILL BE
DEPENDENT IF WE CAN BREAK OUT INTO SOME SUNSHINE.
/OUTLOOK FOR KMSP/
SUN...VFR. SW WIND 10-15 G25 KT.
MON...VFR. SW WIND 10 KT.
TUE...VFR. SW WIND 5 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR MNZ047>051-054>070-073>078-082>085-091>093.
WI...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR WIZ023-024.
&&
$$
SYNOPSIS...MPG
SHORT TERM...MPG
LONG TERM...JRB
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
105 PM CDT FRI AUG 23 2013
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 231 AM CDT FRI AUG 23 2013
MOISTURE GRADIENT INDICATED EARLY THIS MORNING ACROSS IA...INTO
SD/FAR SW MN WHERE DEW PTS REMAIN IN THE 60S. THIS GRADIENT IS
MOST LIKELY THE REMNANTS OF THE OLD FRONTAL BOUNDARY THAT MOVED
INTO IA ON THURSDAY. IN ADDITION...DENSE FOG FORMED IN AREAS THAT
RECEIVED LOTS OF RAINFALL IN NE IA/SW WI. THIS AREA WILL LIKELY
MIX OUT AND DEEPEN THE MOISTURE ACROSS FAR SW/SC MN DURING THE DAY
AS WINDS SHIFT TO THE S/SE. DUE TO THIS MOISTURE GRADIENT AND THE
FACT THAT WINDS BEGIN TO INCREASE AND POOL IN SW MN...ISOLATED
TSRA WILL BE POSSIBLE...ESPECIALLY IF A SFC BOUNDARY DEVELOPS
WHICH IS LIKELY THE FORMATION OF THE WARM FRONT. SOME OF THE LOCAL
MODELS /HOPWRF/ HAVE ISOLATED REFLECTIVITY RETURNS ALONG THIS
MOISTURE GRADIENT THIS AFTN. THE BEST CHC/S OF RAINFALL WILL
DEVELOP LATER TONIGHT AS THE LLJ BEGINS TO INCREASE ACROSS
SD/IA/SW MN. THE PROXIMITY OF THIS LLJ...OR THE APEX OF THE JET
WILL BE THE FOCUS OF TSRA DEVELOPMENT. THE LOCATION REMAINS IN
QUESTION...BUT ENOUGH TRENDS IN THE SHORT TERM MODELS INDICATE
SOMEWHERE IN EASTERN SD/WC OR SW MN. ANY DEVIATION TO THIS JET
WILL LEAD TO THE DEVELOPMENT OF THE SHRA/TSRA FARTHER TO THE NORTH
OR SOUTH.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CDT FRI AUG 23 2013
...SIGNIFICANT HEAT WAVE NEXT WEEK WITH RECORD-SETTING TEMPS POSSIBLE...
THE FOCUS IN THE LONG TERM PORTION OF THE FORECAST CONTINUES TO BE
ON HOT TEMPERATURES THROUGH MUCH OF THE UPCOMING WEEK. IN
FACT...IT COULD BE THE LONGEST DURATION OF CONSECUTIVE DAYTIME HIGH
TEMPERATURES IN THE MID 90S THAT MINNEAPOLIS HAS EXPERIENCED
DURING THE LAST WEEK OF AUGUST SINCE 1948.
PRIOR TO THE ARRIVAL OF THE HEAT...SATURDAY WILL FEATURE SCATTERED
SHOWERS AND THUNDERSTORMS LIFTING NORTHEAST ACROSS THE AREA DURING
THE MORNING...WITH AFTERNOON/EVENING CONVECTION PRIMARILY CONFINED
TO WEST CENTRAL WI ALONG/NORTH OF THE WARM FRONT.
BY SUNDAY...THE ENTIRE FORECAST AREA IS IN THE WARM SECTOR AHEAD
OF THE EASTERN DAKOTAS TROUGH. 925-850MB TEMPERATURES CLIMB TO
AROUND +27C TO +30C. WITH DEEP MIXING PROGGED TO ENSUE WITH BREEZY
SOUTH/SOUTHWEST WINDS...EXPECT LOW/MID 90S TO BE EASILY ACHIEVED.
SAID TEMPERATURES COMBINED WITH ANTICIPATED DEWPOINTS AROUND 70
DEGREES WOULD YIELD MAX HEAT INDEX VALUES OF 95-100
DEGREES...POSSIBLY EVEN A TAD HIGHER. ALTHOUGH THE DAYTIME
PRECIPITATION CHANCES WILL BE DISPLACED TO THE NORTH OF THE
FORECAST AREA...COULD SEE WIDELY SCATTERED ACTIVITY IN CENTRAL
MN/WI ON SUNDAY NIGHT INTO MONDAY AS THE TROUGH SAGS INTO THE
AREA.
THE THERMAL RIDGE HOLDS FIRMLY IN PLACE ACROSS THE FORECAST AREA
FROM MONDAY THROUGH THURSDAY PER THE GFS...WHICH WOULD MEAN
CONTINUANCE OF HIGHS IN THE MID 90S. HOWEVER...THE 00Z ECMWF
DIFFERED NOTABLY...IN THAT IT REDUCED HEIGHTS/TEMPS FOR WEDNESDAY
AND THURSDAY /YIELDING HIGHS IN THE 80S/. THEREFORE HAVE A TINGE
OF LOWERED CONFIDENCE THAT WE/D MEET HEAT ADVISORY CRITERIA FOR
THE 4+ CONSECUTIVE DAYS NEEDED TO WARRANT AN EXCESSIVE HEAT
WATCH/WARNING. WILL CONTINUE TO HIGHLIGHT THE EXCESSIVE HEAT
THREAT IN THE HWO...AND SEE IF THE 12Z ECMWF TREND CONTINUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1238 PM CDT FRI AUG 23 2013
MOISTURE BEGINNING TO SURGE NORTH IN ERNEST...AS EVIDENCED BY CU
FIELD MOVING OUT OF SRN MN. MODEST INSTABILITY HAS DEVELOPED WITHIN
THIS MOIST PLUME OVER SRN MN...WITH THE HRRR CONTINUING TO
GENERATE AN AREA OF SCT TSTMS OVER SW MN THIS AFTERNOON. AS A
RESULT...INCLUDED A VCTS FOR RWF BETWEEN 22Z AND 01Z. STILL NOT
MUCH CONFIDENCE WITH HOW THINGS WILL UNFOLD TONIGHT INTO SATURDAY
MORNING WITH RESPECT TO TSTM CHANCES. BOTH THE NAM/GFS WARM AIR
AND MOISTURE ADVECTION AROUND 700 MB INDICATES A COUPLE OF AREAS
OF ENHANCED FORCING FOR TSTMS TONIGHT...ONE DOWN INTO IA AND THE
UP IN NRN MN...NICELY SPLITTING THE MPX AREA. BIG REASON FOR NOTHING
MORE THAN A VCSH MENTION STILL IS THAT BY THE END OF THE HOPWRF
AND HRRR /06Z TONIGHT/...NEITHER MODEL SHOWS ANYTHING DEVELOPING
NEAR MN/WI AT THAT POINT...VERY POSSIBLE THAT THIS BIT OF WARM
ADVECTION DOES NOT DO MUCH MORE THAN BRING IN A FIELD OF ACCUS.
CONFIDENCE IS BETTER WITH WINDS. LOW LEVEL WINDS ARE FORECAST TO
INCREASE DRAMATICALLY TONIGHT...AND ONCE MIXING PICKS UP ON
SATURDAY...SHOULD HAVE TO PROBLEM MIXING DOWN BETTER THAN 20 KT
GUSTS...WITH GUSTS OVER 30KTS NOT OUT OF THE QUESTION FOR WRN MN
BY THE AFTERNOON.
KMSP...LOW CONFIDENCE IN PRECIP POTENTIAL TONIGHT. AT THE VERY
LEAST...FAVORED THE LATER TIMING DEPICTED BY THE NAM. FOR WINDS
SATURDAY AFTERNOON...MIX DOWN TOOL ON THE NAM INDICATING GUSTS
OVER 30 KTS POSSIBLE DURING THE AFTERNOON...BUT THAT WILL BE
DEPENDENT IF WE CAN BREAK OUT INTO SOME SUNSHINE.
/OUTLOOK FOR KMSP/
SUN...VFR. SW WIND 10-15 G25 KT.
MON...VFR. SW WIND 10 KT.
TUE...VFR. SW WIND 5 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR MNZ047>051-054>070-073>078-082>085-091>093.
WI...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR WIZ023-024.
&&
$$
SHORT TERM...JLT
LONG TERM...LS
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1248 PM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 539 AM CDT FRI AUG 23 2013
LATEST HRRR AND 06Z GFS ARE COMING IN WETTER TODAY...WHICH IS ALSO
BEING BACKED UP BY RADAR TRENDS THAT SHOW INCREASING CONVECTIVE
ACTIVITY ACROSS PORTIONS OF OUR FORECAST AREA. SHOWERS AND
THUNDERSTORMS REMAIN FAIRLY ISOLATED...BUT MAY LINGER LONGER THIS
MORNING THAN ORIGINALLY ANTICIPATED. IN ADDITION...THESE LATEST
MODEL RUNS ARE MORE BULLISH ON SEEING AFTERNOON REDEVELOPMENT AND
THUS WE MAY NEED TO EVENTUALLY INCLUDE POPS FOR THIS AFTERNOON IF
12Z MODEL RUNS CONTINUE TO TREND TOWARDS NEEDING PRECIPITATION
CHANCES.
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT FRI AUG 23 2013
THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL
CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY
ACROSS NORTH CENTRAL KANSAS.
THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS
MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN
ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN
KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS
HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF
THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES
DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE
SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN
TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET
GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND
SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS
RATHER MARGINAL.
THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS
DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY
TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN
ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS
NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE
POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST
AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING
INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN
ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE
THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE
STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY
A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON.
HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE
SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL
LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH
CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND
WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO
THE 90S ACROSS KANSAS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 334 AM CDT FRI AUG 23 2013
PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH
TEMPERATURES.
MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST
PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS
INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE
PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST.
THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR
ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF
THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT
CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY
FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK
WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL
DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST
COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER
THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY
DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL
CAPPED.
AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS
THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH
PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS
TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT
EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE
20 TO 25 MPH RANGE WITH HIGHER GUSTS.
AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS
INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE
IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT
COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN
SWRN LOCATION.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT FRI AUG 23 2013
THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL
CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY
ACROSS NORTH CENTRAL KANSAS.
THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS
MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN
ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN
KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS
HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF
THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES
DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE
SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN
TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET
GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND
SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS
RATHER MARGINAL.
THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS
DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY
TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN
ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS
NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE
POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST
AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING
INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN
ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE
THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE
STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY
A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON.
HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE
SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL
LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH
CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND
WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO
THE 90S ACROSS KANSAS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 334 AM CDT FRI AUG 23 2013
PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH
TEMPERATURES.
MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST
PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS
INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE
PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST.
THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR
ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF
THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT
CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY
FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK
WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL
DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST
COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER
THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY
DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL
CAPPED.
AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS
THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH
PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS
TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT
EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE
20 TO 25 MPH RANGE WITH HIGHER GUSTS.
AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS
INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE
IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT
COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN
SWRN LOCATION.
&&
.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1245 PM CDT FRI AUG 23 2013
PREVAILING VFR CONDITIONS WILL CONTINUE AT KGRI FOR THE NEXT 24
HOURS...WITH OCCASIONALLY GUSTY SOUTHERLY WINDS CONTINUING
THROUGHOUT. EXPECT A LINE OF STORMS STARTING TO DEVELOP ON
SATELLITE NEAR LBF...TO CONTINUE TO BUILD AND SHIFT EAST...BUT
MODEL GUIDANCE IS NOT PICKING UP ON THIS WELL. LATEST RAP/12Z WRF
ARE TRYING TO DEVELOP SOME CONVECTION AND LIFT IT NORTHEAST
THROUGH THE LATE AFTERNOON HOURS...BUT EVEN SO...CONFIDENCE IS LOW
DUE TO THE DIFFERENCES BETWEEN CURRENT RETURNS AND MODEL DATA THAT
IS TRYING TO CAPTURE THIS. LATEST SPC MESO ANALYSIS DOES SHOW
MODERATE INSTABILITY BUILDING AHEAD OF THIS LINE...SO DO THINK WE
COULD SEE SOME SHRA OR TSRA IN THE VICINITY OF KGRI AS EARLY AS
22Z...BUT WITH CONFIDENCE LOW...DECIDED TO ONLY GO WITH A CB FOR
THE TIME BEING. OTHERWISE...ONCE THIS BOUNDARY SHIFTS
EAST...CLEARING SKIES AND GUSTY SOUTHERLY WINDS WILL PERSIST
THROUGH THE END OF THE VALID TAF PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...WESELY
SHORT TERM...WESELY
LONG TERM...ADO
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1221 PM CDT FRI AUG 23 2013
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE. SOUTHEAST WINDS
AT 10-14KT SHOULD MAINTAIN SPEEDS FOR MOST OF TONIGHT...WITH WINDS
INCREASING OUT OF THE SOUTH BY MID-MORNING TO AROUND 15-19KT. SOME
INTERMITTENT MID-LEVEL CLOUDS ARE POSSIBLE. COULD SEE A FEW
SHOWERS IN NORTHEAST NEB TONIGHT...MAINLY NEAR KOFK...BUT HAVE
KEPT MENTION OF TAFS FOR NOW DUE TO LOW CONFIDENCE IN COVERAGE.
MAYES
&&
.PREV DISCUSSION... /ISSUED 932 AM CDT FRI AUG 23 2013/
DISCUSSION...
UPDATED GRIDS THIS MORNING FOR ONGOING VERY ISOLATED SHOWERS.
INCREASED THE DURATION FOR THE REST OF THE MORNING AS SHOWERS ARE
HANGING IN THERE. RAP INDICATES BOTH MID-LEVEL LAPSE RATES AND
MUCAPE ARE RATHER LIMITED ACROSS THE AREA...AND WITH NO LIGHTNING
YET IN THIS ACTIVITY...HAVE REMOVED THUNDER MENTION FOR TODAY.
ALSO INCREASED SKY COVER WITH BROKEN TO OVERCAST SKIES OVER MOST
OF THE CWA. CHANCE OF SHOWERS...WITH MAYBE AN ISOLATED RUMBLE OF
THUNDER...DOES RETURN TONIGHT AS THE LOW-LEVEL JET PICKS UP...MOST
LIKELY TO THE NORTHERN CWA...BUT LIKELY WILL BE A BREAK BETWEEN
THE ONGOING SHOWERS AND THE OVERNIGHT ACTIVITY.
MAYES
PREV DISCUSSION... /ISSUED 349 AM CDT FRI AUG 23 2013/
DISCUSSION...
STRONG UPPER LEVEL RIDGING WILL DOMINATE THE WEATHER PATTERN FOR
NEXT SEVERAL DAYS. THIS WILL KEEP PRECIPITATION CHANCES MEAGER AND
TEMPERATURES SOME 8 TO 10 DEGREES ABOVE NORMAL.
TODAY AND TONIGHT...THE MAIN FORECAST CONCERN FOR THIS PERIOD WILL
BE THE CHANCE FOR PRECIPITATION THIS MORNING AND AGAIN TONIGHT.
THE LATEST 88D SCANS SHOW SOME LIGHT SHOWERS ARE DEVELOPING ALONG
THE SOUTHEAST NEBRASKA/KANSAS BORDER. THESE SHOWERS SHOULDN`T
AMOUNT TO MUCH AND ARE FORCED BY WEAK WARM AIR ADVECTION ALOFT.
DECIDED TO MAINTAIN SLIGHT CHANCE POPS THROUGH MID MORNING TO
ACCOUNT FOR THIS. FOR TONIGHT...A STRENGTHENING LOW LEVEL JET AND
850MB FRONT WILL ACT TO GENERATE PRECIPITATION ACROSS MUCH OF
EASTERN SOUTH DAKOTA...WHICH MAY BRUSH THE NORTHERN HALF OF THE
COUNTY WARNING AREA.
SATURDAY ONWARD...SOME COMPUTER MODELS WANT TO MAINTAIN SOME OF
THE OVERNIGHT PRECIPITATION INTO WESTERN IOWA ON SATURDAY
MORNING. IT DOESN`T APPEAR THERE IS MUCH FORCING TO SUPPORT THIS.
IN FACT 500MB HEIGHTS ARE ON THE RISE...SO WENT WITH A DRY
FORECAST FROM SATURDAY ONWARD. TEMPERATURES WILL REMAIN WARM...LOW
TO MID 90S...THROUGH THE REST OF THE FORECAST. WITH DEW POINTS
REMAINING STEADY IN THE MID TO UPPER 60S APPARENT TEMPERATURES
WILL PUSH 100...WHICH IS BELOW HEAT ADVISORY CRITERIA.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
329 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA LATE TONIGHT INTO SATURDAY MORNING
BRINGING SCATTERED SHOWERS AND THUNDERSTORMS. THIS FRONT WILL PUSH
SOUTH OF THE AREA DURING SATURDAY...AS HIGH PRESSURE BUILDS DOWN
FROM THE NORTH. COOLER AND DRIER CONDITIONS WILL DEVELOP SUNDAY
INTO NEXT WEEK. A WARMING TREND WILL TAKE PLACE BY THE MIDDLE OF
NEXT WEEK AS HIGH PRESSURE SHIFTS OFFSHORE.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 130 PM FRIDAY...CONVECTION HAS STARTED TO DEVELOP IN THE PAST
HALF HOUR. AS MENTIONED EARLIER THE MORE ORGANIZED CONVECTION IS
EXPECTED AFTER 21 UTC WITH THE APPROACHING SHORT WAVE LOCATED IN
NORTHWEST VIRGINIA. THE NAM AND 15 UTC RUC MOVE THIS FEATURE
TOWARDS THE AREA JUST AFTER 20 UTC. SO EXPECT TO SEE UNORGANIZED
CONVECTION WITH A FEW BOUNDARY INTERACTIONS BEFORE 20 UTC. THEN AS
THE HIGH RESOLUTION MODELS ARE SHOWING...A LINE OR LINE SEGMENTS
OF CONVECTION...WILL DEVELOP OR ADVECT FROM THE THE NORTHWEST AND
INTO THE REGION.
TIMING OF THE FRONTAL PASSAGE APPEARS TO BE ALONG A LINE FROM
LUMBERTON TO BURGAW BY 06 UTC AND THE FRONT SHIFTS TO A LINE NEAR
A MYRTLE BEACH TO KINGSTREE LINE. WITH THIS FRONTAL PASSAGE LOW
TEMPERATURES ARE EXPECTED TO REACH THE UPPER 60S IN THE NORTH AND
THE LOWER 70S IN THE SOUTH.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 300 PM FRIDAY...COLD FRONT WILL CROSS THE AREA AND BE JUST
SOUTH OF THE CWA AT THE START OF THE PERIOD. THIS LEAVES NE FLOW
ACROSS THE CWA AS HIGH PRESSURE RIDGES DOWN THE COAST...BECOMING
ALIGNED JUST WEST OF THE CWA THROUGH THE WKND. WHILE SATURDAY WILL
SHOW SLOW IMPROVEMENTS...LOW LEVEL MOISTURE WILL BE TOUGH TO
ERODE...ESPECIALLY NEAR THE COAST. THIS IS ECHOED IN FORECAST
PROFILES AND EVIDENT BY WEAK CONTINUATION OF 850-925MB THETA-E RIDGE
THROUGH SAT NIGHT. SCHC/ISOLATED SHOWERS WILL BE POSSIBLE THE FIRST
HALF OF SATURDAY BEHIND THE FRONT...BUT CLEARING/DRYING WILL OCCUR
LATE IN THE DAY...AND PWATS DROP TO ONE INCH OR LESS (PRETTY
INCREDIBLE FOR AUGUST) BY SUNDAY MORNING. DRY HIGH PRESSURE ENVELOPS
THE AREA SUNDAY...AND A BEAUTIFUL LATE-SUMMER DAY ON TAP WITH AMPLE
SUNSHINE AND WARM BUT BELOW NORMAL TEMPS.
HIGHS THROUGH THE WKND WILL BE ONLY IN THE LOW/MID 80S...COOLER
SUNDAY...WITH LOWS FALLING INTO THE LOW 60S...WITH POSSIBLY A FEW
58S AND 59S SUNDAY NIGHT IN THE COLD SPOTS THANKS TO THIS INCREDIBLY
DRY AIR MASS!
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...LARGE UPPER LEVEL RIDGE OVER THE CENTER OF THE
NATION ON MONDAY. A SLIGHT RETROGRESSION OF THIS FEATURE WILL ALLOW
FOR A NW FLOW TO DEVELOP LOCALLY BY MID WEEK...ONLY TO BE
STRENGTHENED THURSDAY AND FRIDAY AS AN UPPER TROUGH FORMS OFF THE
NEW ENGLAND COAST. SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH
WILL KEEP TEMPS A LITTLE BELOW CLIMO UNTIL AROUND WEDNESDAY WHEN
THE CENTER OF THE WEAKENING HIGH DRIFTS TO OUR SOUTH AND A PIEDMONT
TROUGH DEVELOPS. THE LATE PERIOD SHARPENING OF THE UPPER TROUGH
DRIVES A COOL FRONT THROUGH ON THURSDAY. MODELS SHOWING A FAIR
AMOUNT OF PRECIP WITH ITS PASSAGE BUT GIVEN THE NEARLY NONEXISTENT
MOISTURE FLUX AHEAD OF IT PREFER TO KEEP POPS AT SLIGHT CHANCE.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...A COLD FRONT WILL DROP SOUTHEAST THIS AFTERNOON...WITH
MODERATE CONFIDENCE FOR A BAND OF CONVECTION ON THE LEADING EDGE.
MODERATE CONVERGENCE AND MODERATE TO STRONG CAPE SHOULD PRODUCE
THUNDERSTORMS WITH GUSTY WINDS AS THEY DROP SOUTHEAST AROUND 20
MPH. SMALL HAIL COULD ALSO OCCUR...GIVEN THE NORTHWEST FLOW.
TIMING MAY BE A BIT FAST AT THIS TIME...BUT FEEL THIS COULD BE
MORE SQUALLY IN NATURE...AND THEY TEND TO OUTRUN THEIR SUPPORT.
THERE WILL PROBABLY BE SEVERAL HOURS OF LIGHT SHOWERS BEHIND THE
FRONT. WINDS WILL SHIFT FROM SOUTHWEST TO WEST NORTHWEST AS THE
STORMS MOVE IN. CEILINGS WILL BE VFR FOR THE MOST PART...WITH SOME
BRIEF IFR VISIBILITIES IN THE HEAVIER CONVECTION. OVERNIGHT...WINDS
WILL CONTINUE TO VEER TO THE NORTHWEST AS THE RAIN SLOWLY ENDS
AFTER 05Z. A POST FRONTAL VFR STRATA CU CEILING IS EXPECTED.
SATURDAY...VFR WITH A CONTINUED STRATA CU CEILING AND LIGHT NORTHERLY
WINDS.
EXTENDED OUTLOOK...VFR SATURDAY AFTERNOON THROUGH MONDAY. SCATTERED
CONVECTION TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM FRIDAY...WEST TO SOUTHWESTERLY WINDS OF 10 TO 15 KNOTS
ARE BLOWING OVER THE WATERS THIS AFTERNOON. AS A FRONTAL BOUNDARY
NEARING THE VIRGINIA AND NORTH CAROLINA BORDER SHIFTS SOUTHWARD
WINDS WILL BECOME MORE SOUTHWESTERLY THROUGH THE EVENING. THE
WIND SHIFT WITH THE FRONT IS EXPECTED TO BEGIN JUST AFTER 06 UTC
NEAR SURF CITY AND AFTER 12 UTC BY THE LOWER SANTEE RIVER. SEAS
ARE EXPECTED TO REMAIN IN THE 2 TO 3 FOOT RANGE THROUGH SATURDAY
MORNING.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 PM FRIDAY...COLD FRONT SOUTH OF THE AREA AT THE START OF
THE PERIOD WILL PUSH FURTHER SOUTH THROUGH THE DAY IN RESPONSE TO A
HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. HIGH PRESSURE AXIS
REMAINS WEST OF THE LOCAL AREA...SO WATERS BECOME ALIGNED WITHIN A
PINCHED GRADIENT AND A NE SURGE DEVELOPS LATE SATURDAY AND MUCH OF
SUNDAY. WINDS INCREASE FROM NORTH AT 10 KTS TO START THE PERIOD...TO
NE UP TO 20 KTS ON SUNDAY...BEFORE FALLING BACK TO NE AT 10-15 KTS
LATE. SEAS BUILD IN RESPONSE TO THE INCREASING WINDS...FROM 2-3 FT
SATURDAY UP TO 3-5 FT SUNDAY...AND A SCEC WILL LIKELY BE NEEDED FOR
THE WATERS THE SECOND HALF OF THE SHORT TERM.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...BROAD SWATH OF NE WINDS ALONG THE SOUTHEAST
COAST ON MONDAY AS HIGH PRESSURE DIVES IN FROM POINTS NORTH. THE
FLOW WILL EASE AS THE DAY WEARS ON AND THE GRADIENT RELAXES. WIND
WILL TURN LIGHT AND VARIABLE MONDAY NIGHT AND THEN A SOUTHERLY
COMPONENT BECOMES PREDOMINANT ON TUESDAY DUE TO FORMATION OF A
PIEDMONT TROUGH. SW FLOW INCREASES ON WEDNESDAY ALLOWING FOR
BUILDING SEAS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DRH
SHORT TERM...JDW
LONG TERM...MBB
AVIATION...DRH
MARINE...JDW/MBB/DRH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
131 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT APPROACHING FROM THE NORTHWEST THIS EVENING WILL
PUSH SOUTH OF THE AREA BY EARLY SATURDAY. THE COLD FRONT WILL
USHER IN COOLER AND DRIER CONDITIONS FOR THE WEEKEND INTO EARLY
NEXT WEEK. A WARMING TREND WILL TAKE PLACE BY THE MIDDLE OF NEXT
WEEK AS HIGH PRESSURE SHIFTS OFFSHORE AND COLD FRONT APPROACHES
THE CAROLINAS FROM THE NORTHWEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM FRIDAY...CONVECTION HAS STARTED TO DEVELOP IN THE PAST
HALF HOUR. AS MENTIONED EARLIER THE MORE ORGANIZED CONVECTION IS
EXPECTED AFTER 21 UTC WITH THE APPROACHING SHORT WAVE LOCATED IN
NORTHWEST VIRGINIA. THE NAM AND 15 UTC RUC MOVE THIS FEATURE
TOWARDS THE AREA JUST AFTER 20 UTC. SO EXPECT TO SEE UNORGANIZED
CONVECTION WITH A FEW BOUNDARY INTERACTIONS BEFORE 20 UTC. THEN AS
THE HIGH RESOLUTION MODELS ARE SHOWING A LINE OR LINE SEGMENTS OF
CONVECTION DEVELOPING OR ADVECT FROM THE THE NORTHWEST AND INTO THE
REGION.
TIMING OF THE FRONTAL PASSAGE APPEARS TO BE ALONG A LINE FROM
LUMBERTON TO BURGAW BY 06 UTC AND THE FRONT SHIFTS TO A LINE NEAR
A MYRTLE BEACH TO KINGSTREE LINE. WITH THIS FRONTAL PASSAGE LOW
TEMPERATURES ARE EXPECTED TO REACH THE UPPER 60S IN THE NORTH AND
THE LOWER 70S IN THE SOUTH.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...THE H5 TROUGH WILL PUSH FRONT SOUTH BY SAT
MORNING...BUT WILL KEEP POTENTIAL FOR SHWRS ON SAT WITH BEST
CONVERGENCE FROM THE TIP OF CAPE FEAR SOUTH...WHERE BEST
CONVERGENCE AND RESIDUAL MOISTURE WILL BE.
DEEP N-NW FLOW DEVELOPING BEHIND FRONT AS MID TO UPPER TROUGH
AXIS SHIFTS FARTHER OFF THE COAST AND HIGH PRESSURE BUILDS IN
THROUGH SATURDAY. PCP WATER VALUES WILL DROP FROM CLOSE TO 2
INCHES AHEAD OF FRONT TO LESS THAN AN INCH BY END OF PERIOD OR
EARLY SUNDAY. THEREFORE EXPECT CLEARING THROUGH SAT NIGHT FROM
NORTH TO SOUTH. RESIDUAL LOW LEVEL MOISTURE FROM PCP MAY PRODUCE FOG
ACROSS THE AREA SAT NIGHT.
HIGHS SATURDAY WILL REACH INTO THE LOW 80S AFTER A FAIRLY WARM
START DUE TO CLOUDS AND SHOWERS ASSOCIATED WITH THE COLD FRONT.
LOWS SATURDAY NIGHT WILL FALL DOWN INTO THE 60S AS A MUCH DRIER
AIRMASS MOVES INTO THE REGION. SUNDAY WILL RUN BELOW NORMAL AS
RELATIVELY COOLER AND DRIER AIR MASS BUILDS DOWN OVER AREA.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...RIDGE PUSHES IN FROM THE WEST THROUGH THE
MID TO UPPER LEVELS WHILE HIGH PRESSURE NOSES DOWN FROM THE NORTH
MONDAY AS IT SHIFTS EAST OFF THE MID ATLANTIC COAST THROUGH
TUESDAY. THE RIDGE RETREATS WESTWARD THROUGH MID WEEK AS
SHORTWAVES RIDE AROUND IT REACHING INTO THE SOUTHEAST ON
WEDNESDAY AS IT PUSHES A COLD FRONT SOUTHEAST. THIS MAY PRODUCE
INCREASED CLOUDS AND CHC OF SHWRS ON WED BEFORE HIGH PRESSURE
BUILDS IN BEHIND IT BY LATE THURS INTO FRI.
OVERALL EXPECT PLENTY OF SUNSHINE WITH TEMPS MODERATING FROM
BELOW NORMAL MONDAY TO ABOVE NORMAL BY WED AS MID TO UPPER RIDGE
BUILDS EAST INTO THE CAROLINAS PRODUCING H5 HEIGHT RISES. GRADIENT
WINDS WILL WEAKEN AS HIGH SHIFTS SOUTH AND EAST WITH MAINLY
DIURNAL SHIFTS DUE TO SEA BREEZE/LAND BREEZE. 850 TEMPS WILL
BOTTOM OUT AROUND 13C IN COOLER AIR ADVECTING IN BEHIND FRONT
AND WILL RISE UP TO 18C BY TUES INTO WED. THE DIURNAL SWINGS IN
TEMPS WILL BE FAIRLY LARGE WITH DRY AIR IN PLACE AND DEWPOINT
TEMPS REACHING DOWN INTO THE 50S OVER NORTHERN TIER ZONES MONDAY
AND TUES. AS HIGH PRESSURE SHIFTS OFF SHORE AND COLD FRONT MAKES
ITS WAY SOUTHEAST BY WED EXPECT WARMER SOUTHERLY FLOW BRINGING
TEMPS BACK UP TOWARD NORMAL WITH READINGS IN THE MID 80S AND
AROUND 90 BY THURS.
&&
.AVIATION /18Z FRIDAY THROUGH TUESDAY/...
AS OF 18Z...A COLD FRONT WILL DROP SOUTHEAST THIS AFTERNOON...WITH
MODERATE CONFIDENCE FOR A BAND OF CONVECTION ON THE LEADING EDGE.
MODERATE CONVERGENCE AND MODERATE TO STRONG CAPE SHOULD PRODUCE
THUNDERSTORMS WITH GUSTY WINDS AS THEY DROP SOUTHEAST AROUND 20
MPH. SMALL HAIL COULD ALSO OCCUR...GIVEN THE NORTHWEST FLOW.
TIMING MAY BE A BIT FAST AT THIS TIME...BUT FEEL THIS COULD BE
MORE SQUALLY IN NATURE...AND THEY TEND TO OUTRUN THEIR SUPPORT.
THERE WILL PROBABLY BE SEVERAL HOURS OF LIGHT SHOWERS BEHIND THE
FRONT. WINDS WILL SHIFT FROM SOUTHWEST TO WEST NORTHWEST AS THE
STORMS MOVE IN. CEILINGS WILL BE VFR FOR THE MOST PART...WITH SOME
BRIEF IFR VISIBILITIES IN THE HEAVIER CONVECTION. OVERNIGHT...WINDS
WILL CONTINUE TO VEER TO THE NORTHWEST AS THE RAIN SLOWLY ENDS
AFTER 05Z. A POST FRONTAL VFR STRATA CU CEILING IS EXPECTED.
SATURDAY...VFR WITH A CONTINUED STRATA CU CEILING AND LIGHT NORTHERLY
WINDS.
EXTENDED OUTLOOK...VFR SATURDAY AFTERNOON THROUGH MONDAY. SCATTERED
CONVECTION TUESDAY AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM FRIDAY...WEST TO SOUTHWESTERLY WINDS OF 10 TO 15 KNOTS
ARE BLOWING OVER THE WATERS THIS AFTERNOON. AS A FRONTAL BOUNDARY
NEARING THE VIRGINIA AND NORTH CAROLINA BORDER SHIFTS SOUTHWARD
WINDS WILL BECOME MORE SOUTHWESTERLY THROUGH THE EVENING. THE
WIND SHIFT WITH THE FRONT IS EXPECTED TO BEGIN JUST AFTER 06 UTC
NEAR SURF CITY AND AFTER 12 UTC BY THE LOWER SANTEE RIVER. SEAS
ARE EXPECTED TO REMAIN IN THE 2 TO 3 FOOT RANGE THROUGH SATURDAY
MORNING.
SHORT TERM /SATURDAY THROUGH SUNDAY
NIGHT/... AS OF 3 AM FRIDAY...WINDS WILL SHIFT RAPIDLY TO THE
NORTH SATURDAY MORNING BEHIND COLD FRONT. WINDS MAY INCREASE UP TO
A SOLID 15 KTS OR POSSIBLY UP TO 20 KTS OVERNIGHT SATURDAY INTO
SUNDAY IN NORTHEAST SURGE BEHIND FRONT. SEAS WILL INCREASE IN
NORTHEAST SURGE BEHIND FRONT THROUGH SATURDAY NIGHT INTO THE
LATTER HALF OF THE WEEKEND...FROM 2 TO 3 FT WITH 2 TO 4 FT RANGE
LATE SATURDAY AND MAYBE SLIGHTLY HIGHER AS CAA INCREASES.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...THE WINDS WILL LIGHTEN AS HIGH PRESSURE SHIFTS
SOUTH AND WEAKENS AND AIR MASS BEGINS TO MODIFY THROUGH LATE
MONDAY. OVERALL SEAS WILL BE 2 TO 4 FT MOST WATERS. A FURTHER
SHIFTING OF THE HIGH TO BASICALLY OVERHEAD WILL LEAD TO WINDS
BASICALLY LIGHT AND VARIABLE TUESDAY. OVERALL SEAS WILL TREND DOWN
TO AROUND TWO FEET TUESDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HAWKINS
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...DL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
111 PM CDT FRI AUG 23 2013
.UPDATE...
ISSUED AT 105 PM CDT FRI AUG 23 2013
EARLY THIS AFTERNOON...WARM FRONT ACROSS EASTERN MONTANA. EAST OF
THIS TROUGH A GOOD SOUTHEAST FLOW WAS BRING INCREASING DEW POINTS
INTO THE REGION. SOUNDING FORECAST SHOWS CENTRAL AND EAST WELL
CAPPED THIS AFTERNOON. THE WEST BECOMES UNCAPPED LATE IN THE DAY.
SO REMOVED MENTION OF THUNDERSTORMS THROUGH THE AFTERNOON. EXPECT
THE START OF CONVECTION THIS EVENING. OTHER ASPECTS OF THE
FORECAST LOOK GOOD.
UPDATE ISSUED AT 937 AM CDT FRI AUG 23 2013
WARM H500 RIDGE REMAINS OVER THE NORTHERN PLAINS TODAY. WITHIN THE
RIDGE THERE IS A WEAK VORT LOBE MOVING THROUGH WHICH...AIDED BY THE
DIURNAL LOW LEVEL JET...(30 KTS ON 12Z KBIS SOUNDING) SPONSORING
SOME WEAK CONVECTION CROSS THE SOUTH CENTRAL THIS MORNING.
CONVECTION EXPECTED TO DIMINISH AS THE LOW LEVEL FEATURES MIX OUT
THIS AM. THEN SYNOPTIC SCALE FORCING WILL PREVAIL THIS AFTERNOON
AND EVENING AS WARM FRONT IN EASTERN MONTANA MOVES EAST. THE WARM
FRONT WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS SOUTHWEST AND
WEST CENTRAL THIS AFTERNOON/EVENING. MADE SOME CHANGES TO CLOUDS
AND POPS THIS AM TO FOCUS ON THE ON GONG CONVECTION. OTHERWISE NO
OTHER CHANGES.
UPDATE ISSUED AT 643 AM CDT FRI AUG 23 2013
WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED
SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA.
HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS
NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER
EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED
OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT
FORECAST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM
POTENTIAL AND AREAL COVERAGE.
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER
SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW
PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL
SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND
HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR
CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE
NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN
SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE
LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT
FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE
ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT
APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE
CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR
AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH
INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN
SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS
TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON
INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE
TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH
FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH
CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST
INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN
CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN
NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG
WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S.
FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS
AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE
IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND
INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN
THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT
CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM CDT FRI AUG 23 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC
THUNDERSTORM CHANCES.
THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH
FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN
TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS
WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S
TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH
SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS
THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON
HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY
ACROSS THE SOUTH.
EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING
SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE
WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA.
THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD.
MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY
NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS
THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC
SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE
WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL
LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY.
THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN
THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE.
THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS
THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE
ENERGY CONTINUING TO TRAVERSE THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 105 PM CDT FRI AUG 23 2013
AT 1 PM CDT...A WARM FRONT ACROSS EASTERN MONTANA IS FORECAST TO
MOVE INTO WESTERN NORTH DAKOTA TONIGHT. THE FRONT WILL BE THE
FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS. AHEAD OF THIS FRONT
SOUTHEAST FLOW WILL BRING 15 TO 25 KT WINDS INTO CENTRAL NORTH
DAKOTA. THIS WINDS WILL DIMINISH TO LESS THAN 10 KTS TONIGHT AND
SATURDAY. DUE TO UNCERTAINTY IN THE TIMING AND AREA OF WIDELY
SCATTERED THUNDERSTORMS...HANDLED THE THREAT USING THE VICINITY
OPTION FOR THUNDERSTORMS...MAINLY BETWEEN 02Z-12Z TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...KS
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS TULSA OK
1227 PM CDT FRI AUG 23 2013
.DISCUSSION...
THE 18Z TAF DISCUSSION IS INCLUDED BELOW.
&&
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
BAND OF HIGH BASED SHOWERS SHOULD DISSIPATE BY 19 OR 20Z...AND VFR
CONDITIONS WILL PREVAIL AT ALL TAF SITES THRU MUCH OF THE PERIOD.
A STRAY SHOWER OR STORM COULD IMPACT ANY AIRPORT...BUT CHANCES ARE
TOO LOW TO MENTION. PERSISTENCE SUGGESTS FOG WILL REDUCE VSBYS AT
KBVO AND KFYV DOWN TO IFR RANGE ANYWHERE FROM 06Z TO 14Z TONIGHT
AND EARLY SATURDAY.
LACY
&&
.PREV DISCUSSION... /ISSUED 907 AM CDT FRI AUG 23 2013/
DISCUSSION...
UPPER AIR DATA AT 12Z SHOWS COOLER AND MORE MOIST CONDITIONS IN
THE MID LVLS COMPARED TO 24 HRS AGO...FROM 700MB UP TO 500MB. IN
THE LATE NIGHT AND EARLY MORNING...THIS MID LVL MOISTURE CREATES
SOME INSTABILITY DUE TO NOCTURNAL COOLING ABOVE THIS MOIST LAYER.
THIS HAS PRODUCED A FEW HIGH BASED SHOWERS AND A LIGHTNING STRIKE
OR TWO OVER EASTERN OKLAHOMA. HOWEVER...AS THE DAY CONTINUES THIS
MID LEVEL INSTABILITY WANES AND THUS THE SHOWERS SHOULD DISSIPATE
BY MIDDAY AS THE HRRR AND LOCAL WRF MODEL SUGGEST. GRIDS HAVE BEEN
UPDATED TO ACCOUNT FOR THE SMALL AREA OF PRECIP DOWN OVER EAST
CENTRAL OKLAHOMA.
LACY
PREV DISCUSSION... /ISSUED 709 AM CDT FRI AUG 23 2013/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
PATCHY FOG AT TAF SITES KBVO/KXNA/KFYV TO MIX AWAY BY 15Z.
VFR ALL SITES UNTIL PATCHY FOG RETURNS AGAIN LATE TONIGHT
GENERALLY AFTER 06Z WITH POTENTIAL VISIBILITY BELOW 3 MILES
KFYV/KXNA.
PREV DISCUSSION... /ISSUED 339 AM CDT FRI AUG 23 2013/
DISCUSSION...
A STRONG RIDGE OF HIGH PRESSURE ALOFT WILL REMAIN OVER THE AREA
THROUGH THE ENTIRE FORECAST PERIOD. THIS WILL LEAD TO AN EXTENDED
STRETCH OF HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN. AN
ISOLATED SHOWER OR THUNDERSTORM WILL BE POSSIBLE THE NEXT FEW
AFTERNOONS...MAINLY OVER THE HIGHER TERRAIN AREAS...BUT AREAL
COVERAGE WILL BE MUCH TOO LOW TO MENTION IN THE FORECAST.
AFTERNOON TEMPERATURES MAY INCH UP A BIT NEXT WEEK AS LOW LEVEL
WINDS LOSE THE EASTERLY COMPONENT THAT WILL BE PRESENT THE NEXT
FEW DAYS.
STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 73 94 74 94 / 0 10 0 10
FSM 73 95 74 95 / 0 10 0 10
MLC 72 95 73 95 / 10 10 10 10
BVO 69 93 70 93 / 0 10 0 10
FYV 67 91 68 91 / 0 10 0 10
BYV 69 91 70 91 / 0 10 0 10
MKO 71 94 72 94 / 0 10 0 10
MIO 70 92 71 92 / 0 10 0 10
F10 71 95 72 95 / 10 10 10 10
HHW 73 96 74 96 / 10 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...30
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
435 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS
AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND.
HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE
WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW
WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF
COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING
RAIN CHANCES FURTHER.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 430 PM...AREA OF CONVECTION IS SHIFTING TO THE WRN CWFA AND
DYING OFF EAST OF I-77. HAVE UPDATED AFTERNOON AND EVENING POP TO
REFLECT THESE TRENDS. NOW HAVE HIGHEST POP FOLLOWING THE TRACK OF
THE CURRENT OUTFLOW BOUNDARY AND SPREADING ACROSS THE UPSTATE INTO
NE GA. ALSO HAVE HIGH POP SPREADING SW ACROSS THE NC MTNS AS WELL.
POP SIGNIFICANTLY REDUCED OVER THE I-77 CORRIDOR. SVR STORMS REMAIN
POSSIBLE AS THE STORMS MOVE INTO AN AREA WITH SIGNIFICANTLY HIGHER
DCAPE VALUES. TEMPS FELL SIGNIFICANTLY WITH THE LINE OF TSRA AND
HAVE FOLLOWED THESE TRENDS AS WELL...ALTHOUGH NOT AS DRAMATICALLY.
AS OF 230 PM EDT FRIDAY...A LINE OF SHOWERS AND THUNDERSTORMS HAS
DEVELOPED OVER THE WRN NC FOOTHILLS AND PIEDMONT. THE LINE IS BEING
FORCED BY LLVL SFC CONVERGENCE AND DIFFERENTIAL HEATING RESULTING
FROM THE APPROACH OF AN H5 SHORT WAVE WHICH THE RAP CURRENTLY HAS
LOCATED OVER NE TN AND SW VA. THE DEEP LAYER SHEAR ISN/T
STRONG...BUT THE AIRMASS AHEAD OF THE LINE IS QUITE UNSTABLE AND IT
ALREADY HAS A WELL ESTABLISHED REAR INFLOW JET PER THE TERMINAL
DOPPLER RADAR AT CHARLOTTE. THE NAM AND GFS BOTH STRENGTHEN SFC
CONVERGENCE AHEAD OF THE LINE. THEREFORE IT SHOULD CONTINUE TO MOVE
TO THE SOUTHEAST AND AT LEAST MAINTAIN ITSELF IF NOT GET STRONGER.
BUT IT SHOULD ALSO BUILD TO THE SOUTHWEST...OR NEW STORMS MAY
ORIGINATE OVER THE SC MTNS...AS THE LLVL WINDS BACK ACROSS MOST OF
THE UPSTATE AND EVEN INTO NE GA OVER THE NEXT COUPLE HOURS. AT THIS
RATE MOST LOCATIONS OVER THE FOOTHILLS AND PIEDMONT SHOULD GET INTO
THE ACT OVER THE NEXT 4 TO 6 HOURS AND POPS HAVE BEEN RAISED TO
LIKELY TO CATEGORICAL FOR THE REST OF THE DAY. DCAPE VALUES ARE HIGH
OVER THE UPSTATE...BUT DROP OFF RAPIDLY INTO NORTH CAROLINA. SO AS
THE LINE MOVE SOUTHWARD...IT/S TENDENCY TO PRODUCE STRONG OUTFLOW
SHOULD INCREASE.
STORMS SHOULD DIMINISH FROM NORTH TO SOUTH THIS EVENING. I THINK
THERE WILL ENOUGH CONVECTIVE DEBRIS AND MIXING EAST OF THE MTNS TO
PREVENT FOG FROM FORMING AGAIN. OVER THE MOUNTAINS WINDS ARE
EXPECTED TO DECOUPLE OVERNIGHT AS THE LLVL GRADIENT WINDS WILL BE
ORIENTED OUT OF THE NE...ORTHOGONAL TO THE HIGHER NC MTN CHAINS.
THEREFORE...THE MTN VALLEYS SHOULD SEE FOG AND STRATUS ONCE AGAIN.
COLD AIR DAMMING DEVELOPS FOR SATURDAY. THE MODELS STILL HAVE
1000-2000 SBCAPE VALUES OVER THE SOUTHERN ZONES. I/VE KEPT LOW END
CHANCE POPS ALONG THE UPPER SAVANNAH RIVER VALLEY AND OVER THE
SOUTHWEST AND CENTRAL NC MTNS. TYPICALLY IN THESE SITUATIONS MOST OF
THE DEVELOPMENT IS OVER THE SW MTNS AND ALONG THE EASTERN ESCARPMENT
OF THE BLUE RIDGE. CLOUDS MAY DISSIPATE IN THE DRIER AIR OVER THE
PIEDMONT AND ALONG THE TN LINE...WITH GENERALLY MOSTLY CLOUDY SKIES
EXPECTED ELSEWHERE.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AT 230 PM EDT FRIDAY...A STRONG UPPER HIGH WILL BE CENTERED OVER MO
ON SATURDAY NIGHT....WHILE A POSITIVELY TILTED UPPER TROUGH WILL BE
JUST OFF THE EAST COAST. THIS TROUGH MOVES FARTHER OFF THE EAST
COAST ON SUNDAY...WHILE THE UPPER RIDGE REMAINS CENTERED OVER MO. ON
MONDAY THE UPPER RIDGE RETROGRESSES INTO KS.
A COLD FRONT TO OUR SOUTH WILL DRIFT FARTHER SOUTH ACROSS FL
SATURDAY NIGHT AND SUNDAY...WHILE DRIER AIR AND HIGH PRESSURE SPREAD
ACROSS THE CAROLINAS AND GA FROM THE NE. MODEL TIME HEIGHTS SHOW A
THINNING...LINGERING LAYER OF MOISTURE AT AROUND 850 MB BEHIND THE
FRONT. WITH JUST A WEAK EASTERLY UPSLOPE FLOW DEVELOPING AS WINDS
VEER IN THE LOW LEVELS...ONLY VERY SMALL POPS WILL BE CARRIED SUNDAY
EVENING AND LATE MONDAY. TEMPERATURES WILL RUN BELOW NORMAL THROUGH
THE PERIOD...WITH A SLIGHT WARMING TREND ON MONDAY AS HEIGHTS RISE
ALOFT WITH THE PROGRESSION OF THE ATLANTIC TROUGH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE
EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER
RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY
NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE
ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A
WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A
HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE
APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL
FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS
OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL
PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE
END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS
DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO
MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST
OF NEXT WEEK.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...THE LINE OF THUNDERSTORMS WEAKENED AND SPLIT THE AIRFIELD.
CHC FOR ADDITIONAL ACTIVITY NEAR THE AIRPORT IS LOW THIS EVENING...
SO WILL REMOVE MENTION...BUT WATCH FOR NEEDED AMD. WINDS SHUD STAY
LIGHT FROM THE NORTH INTO THE EVENING. IN FACT...SHOULD ONLY SEE SCT
LOW VFR CLOUDS UNLESS MORE CELLS DEVELOP. LATER TONIGHT AN MVFR
STRATO-CU DECK MAY MOVE IN AS THE TRUE SFC OLD FRONT ARRIVES. THE
RAP AND OUR LOCAL WRF ARW DO THIS AND I/VE ADDED A PERIOD OF MVFR
CIGS FROM 09-14 UTC TONIGHT AND TMRW. WINDS WILL VEER FROM NW TO NE
AS THE FRONT MOVES THROUGH.
ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST AND SHUD
AFFECT KGSP/KGMU THIS AFTERNOON AND POSSIBLY KAVL/KAND. KHKY LOOKS
TO BE OUT OF DANGER...BUT AN ADDITIONAL CELL COULD DEVELOP LATER.
WINDS WILL GO NORTH BEHIND THE GUST FRONT ASSOCIATED WITH THE LINE
OF STORMS. THEN LOW VFR CLEARS OUT UNTIL LATER TONIGHT. LATER
TONIGHT MVFR CIGS WILL DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT
INTO THE UPSTATE. THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH
CAROLINA TAF SITES. AT KAVL THE WINDS SHOULD BE COME LIGHT LATE
TONIGHT AS THE FRONT IS MOVING IN FROM THE NE. THIS WILL SUPPORT
ANOTHER NIGHT WITH STRATUS AND FOG. WINDS WILL BECOME RATHER BRISK
OUT OF THE NORTHEAST AFTER SUNRISE. I WOULDN/T BE SURPRISED TO SEE
SOME GUSTS UP TO 20 KTS OVER THE UPSTATE AND AT KCLT.
OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY
BUILDS IN FROM THE NORTH OVER THE WEEKEND.
CONFIDENCE TABLE...
20-02Z 02-08Z 08-14Z 14-20Z
KCLT HIGH 100% HIGH 100% HIGH 81% HIGH 95%
KGSP HIGH 100% HIGH 91% HIGH 100% HIGH 100%
KAVL HIGH 100% MED 67% LOW 56% MED 67%
KHKY HIGH 100% HIGH 80% LOW 52% HIGH 95%
KGMU HIGH 100% HIGH 91% HIGH 95% 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...VISIN
NEAR TERM...MCAVOY/RWH
SHORT TERM...JAT
LONG TERM...VISIN
AVIATION...MCAVOY/RWH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
229 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS
AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND.
HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE
WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW
WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF
COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING
RAIN CHANCES FURTHER.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 230 PM EDT FRIDAY...A LINE OF SHOWERS AND THUNDERSTORMS HAS
DEVELOPED OVER THE WRN NC FOOTHILLS AND PIEDMONT. THE LINE IS BEING
FORCED BY LLVL SFC CONVERGENCE AND DIFFERENTIAL HEATING RESULTING
FROM THE APPROACH OF AN H5 SHORT WAVE WHICH THE RAP CURRENTLY HAS
LOCATED OVER NE TN AND SW VA. THE DEEP LAYER SHEAR ISN/T
STRONG...BUT THE AIRMASS AHEAD OF THE LINE IS QUITE UNSTABLE AND IT
ALREADY HAS A WELL ESTABLISHED REAR INFLOW JET PER THE TERMINAL
DOPPLER RADAR AT CHARLOTTE. THE NAM AND GFS BOTH STRENGTHEN SFC
CONVERGENCE AHEAD OF THE LINE. THEREFORE IT SHOULD CONTINUE TO MOVE
TO THE SOUTHEAST AND AT LEAST MAINTAIN ITSELF IF NOT GET STRONGER.
BUT IT SHOULD ALSO BUILD TO THE SOUTHWEST...OR NEW STORMS MAY
ORIGINATE OVER THE SC MTNS...AS THE LLVL WINDS BACK ACROSS MOST OF
THE UPSTATE AND EVEN INTO NE GA OVER THE NEXT COUPLE HOURS. AT THIS
RATE MOST LOCATIONS OVER THE FOOTHILLS AND PIEDMONT SHOULD GET INTO
THE ACT OVER THE NEXT 4 TO 6 HOURS AND POPS HAVE BEEN RAISED TO
LIKELY TO CATEGORICAL FOR THE REST OF THE DAY. DCAPE VALUES ARE HIGH
OVER THE UPSTATE...BUT DROP OFF RAPIDLY INTO NORTH CAROLINA. SO AS
THE LINE MOVE SOUTHWARD...IT/S TENDENCY TO PRODUCE STRONG OUTFLOW
SHOULD INCREASE.
STORMS SHOULD DIMINISH FROM NORTH TO SOUTH THIS EVENING. I THINK
THERE WILL ENOUGH CONVECTIVE DEBRIS AND MIXING EAST OF THE MTNS TO
PREVENT FOG FROM FORMING AGAIN. OVER THE MOUNTAINS WINDS ARE
EXPECTED TO DECOUPLE OVERNIGHT AS THE LLVL GRADIENT WINDS WILL BE
ORIENTED OUT OF THE NE...ORTHOGONAL TO THE HIGHER NC MTN CHAINS.
THEREFORE...THE MTN VALLEYS SHOULD SEE FOG AND STRATUS ONCE AGAIN.
COLD AIR DAMMING DEVELOPS FOR SATURDAY. THE MODELS STILL HAVE
1000-2000 SBCAPE VALUES OVER THE SOUTHERN ZONES. I/VE KEPT LOW END
CHANCE POPS ALONG THE UPPER SAVANNAH RIVER VALLEY AND OVER THE
SOUTHWEST AND CENTRAL NC MTNS. TYPICALLY IN THESE SITUATIONS MOST OF
THE DEVELOPMENT IS OVER THE SW MTNS AND ALONG THE EASTERN ESCARPMENT
OF THE BLUE RIDGE. CLOUDS MAY DISSIPATE IN THE DRIER AIR OVER THE
PIEDMONT AND ALONG THE TN LINE...WITH GENERALLY MOSTLY CLOUDY SKIES
EXPECTED ELSEWHERE.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AT 230 PM EDT FRIDAY...A STRONG UPPER HIGH WILL BE CENTERED OVER MO
ON SATURDAY NIGHT....WHILE A POSITIVELY TILTED UPPER TROUGH WILL BE
JUST OFF THE EAST COAST. THIS TROUGH MOVES FARTHER OFF THE EAST
COAST ON SUNDAY...WHILE THE UPPER RIDGE REMAINS CENTERED OVER MO. ON
MONDAY THE UPPER RIDGE RETROGRESSES INTO KS.
A COLD FRONT TO OUR SOUTH WILL DRIFT FARTHER SOUTH ACROSS FL
SATURDAY NIGHT AND SUNDAY...WHILE DRIER AIR AND HIGH PRESSURE SPREAD
ACROSS THE CAROLINAS AND GA FROM THE NE. MODEL TIME HEIGHTS SHOW A
THINNING...LINGERING LAYER OF MOISTURE AT AROUND 850 MB BEHIND THE
FRONT. WITH JUST A WEAK EASTERLY UPSLOPE FLOW DEVELOPING AS WIDNS
VEER IN THE LOW LEVELS...ONLY VERY SMALL POPS WILL BE CARRIED LATE
MONDAY. TEMPERATURES WILL RUN BELOW NORMAL THROUGH THE PERIOD...WITH
A SLIGHT WARMING TREND ON MONDAY AS HEIGHTS RISE ALOFT WITH THE
PROGRESSION OF THE ATLANTIC TROUGH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE
EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER
RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY
NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE
ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A
WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A
HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE
APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL
FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS
OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL
PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE
END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS
DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO
MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST
OF NEXT WEEK.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...A LINE OF THUNDERSTORMS IS ORGANIZING 40 TO 50 MILES
NORTHWEST OF THE AIRFIELD. IT SHOULD CONTINUE MOVING SOUTHEAST AND
WILL LIKELY ACCELERATE A LITTLE AS IT DOES. TEMPO THUNDER HAS BEEN
MOVED UP AN HOUR...FROM 19-22 UTC. STORMS ARE SHOWING 30-35KT
INBOUNDS ON TDWR. THE LINE SHOULD STRENGTHEN SOME AS IT APPROACHES
AND I/VE ADDED A PERIOD OF 35 KT GUSTS TO THE TAF. I WENT
VARIABLE...THOUGH THE STRONGEST WINDS ARE LIKELY TO BE ORIENTED OUT
OF THE NORTH. SCT SHRA AND A FEW TSTMS WILL PERSIST INTO THE LATE
EVENING HOURS. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS
THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO
THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND
TWRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH.
ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST ACROSS THE
NC AND SC PIEDMONT THIS AFTERNOON AND EVENING. THE QUESTION IS HOW
FAR TO THE SOUTHWEST THE LINE WILL BUILD. THE MODELS HAVE GOOD
CONVERGENCE WELL INTO THE UPSTATE...SO I THINK THE LINE WILL BUILD
TO THE SOUTHWEST AND I/VE ADDED TEMPO THUNDER IN AT KGMU/KGSP
STARTING AT 20 UTC. THE LINE IS PRACTICALLY ON TOP OF HKY AND THEY
HAVE A TEMPO FOR THE NEXT COUPLE HOURS. I/M NOT AS CONFIDENT OF KAND
AND TEMPO WAS LEFT OUT OF THAT SITE. KAVL WILL PROBABLY SEE
SOMETHING SO THEY GOT A TEMPO AS WELL. LATER TONIGHT MVFR CIGS WILL
DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE.
THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES.
AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS
MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS
AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER
SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER
THE UPSTATE AND AT KCLT.
OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY
BUILDS IN FROM THE NORTH OVER THE WEEKEND.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 85% HIGH 85%
KGSP HIGH 100% HIGH 100% HIGH 80% HIGH 97%
KAVL HIGH 100% MED 77% LOW 51% LOW 56%
KHKY HIGH 100% HIGH 94% LOW 42% HIGH 81%
KGMU HIGH 100% HIGH 100% HIGH 83% 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...VISIN
NEAR TERM...MCAVOY
SHORT TERM...JAT
LONG TERM...VISIN
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
201 PM EDT FRI AUG 23 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS
AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND.
HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE
WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW
WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF
COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING
RAIN CHANCES FURTHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 AM EDT FRIDAY...FOG AND STRATUS CONTINUES TO BURN OFF THIS
MORNING...THOUGH IT IS LINGERING ACROSS THE NC MTN VALLEYS AND OVER
A FEW LOW SPOTS OUT ACROSS THE FOOTHILLS AND PIEDMONT. FORECAST
REASONING FOR THE AFTERNOON HOURS HASN/T CHANGED MUCH. A SHORT WAVE
WILL CROSS THE REGION BETWEEN 21-00 UTC. CAPE VALUES WILL BE FAIRLY
HIGH...THOUGH LAPSE RATES WILL BE WEAK. ALSO...THE SPC FORECAST
MESOANALYSIS FOR THE FORECAST AREA HAS EFFECTIVE BULK SHEAR VALUES
UNDER 20 KTS THROUGH THE MID AFTN HOURS. THE VARIOUS CONVECTIVE
ALLOWING MODELS DON/T HAVE MUCH OVER OUR AREA...FAVORING MORE
VIGOROUS DEVELOPMENT OVER ERN NC AND SRN VA WHERE THE DEEP LAYER
SHEAR IS STRONGER. CONSIDERING ALL THIS I AM NOT GOING TO UP POPS
INTO THE LIKELY RANGE THIS AFTN. I THINK WE WILL SEE DECENT
COVERAGE...BUT I DON/T THINK THE FORCING SUPPORTS ANY ESCALATION OF
WHAT WE HAVE IN THERE ALREADY.
AS OF 700 AM EDT...THE FOG FORECAST REMAINS CHALLENGING THIS
MORNING...WITH MANY LOCATIONS THAT HAVE WET GROUND SEEING VSBY QUITE
VARIABLE AND DIPPING INTO DENSE FOG RANGE...ESPECIALLY THE FOOTHILLS
AND MTN VALLEYS. HOWEVER...MID AND HIGH CLOUDS ARE THICKENING ALOFT
WHICH COULD PUT THE BREAKS ON MORE WIDESPREAD FOG DEVELOPMENT...AND
MUCH OF THE 1/4SM VSBY HAS BEEN SHALLOWER GROUND FOG. AN SPS HAS
BEEN ISSUED FOR MTNS/FOOTHILLS...AND ADDITIONAL FOG/PATCHY DENSE
WORDING HAS BEEN ADDED TO THE FORECAST.
OTHERWISE...THE FORECAST REMAINS ON TRACK WITH WATER VAPOR IMAGERY
SHOWING A SHORTWAVE MOVING SE FROM THE OH VALLEY EARLY THIS
MORNING...ATOP AN ASSOCIATED SFC COLD FRONT. THE BOUNDARY WILL MOVE
INTO THE FORECAST AREA THROUGH THE DAY...WITH UPPER JET DIVERGENCE
GRADUALLY SHARPENING UP OVERHEAD...ALONG WITH IMPROVING LOW LEVEL
CONVERGENCE ALONG THE FRONTAL ZONE. THIS FORCING SHOULD COMBINE WITH
SFC BASED INSTABILITY REACHING 2500 TO 3000 J/KG CAPE THIS AFTN
ACROSS THE SE HALF OF THE FORECAST AREA. ANTICIPATE FAIRLY DECENT
SCATTERED COVERAGE THROUGHOUT THIS AFTN...BUT WITH THE BEST CHANCE
OF STRONG TO SEVERE THUNDERSTORMS ALONG AND SE OF THE INTERSTATE 85
CORRIDOR. WIND SHEAR WILL BE FAIRLY LIMITED UP THE COLUMN...BUT WITH
JUST ENOUGH DIRECTIONAL/SPEED SHEAR FOR WEAK MULTI CELL DEVELOPMENT
IN THE DEEP LAYER FORCING. WILL HIGHLIGHT THE POTENTIAL IN THE HWO.
TEMPS AHEAD OF THE FRONTAL ZONE THIS AFTN WILL REACH MAXES AT OR
SLIGHTLY ABOVE CLIMATE AVERAGES.
THE BOUNDARY WILL SETTLE S OF THE FORECAST AREA TONIGHT. DEEP LAYER
N TO NW FLOW WILL SET UP BEHIND THE FRONT OVERNIGHT...WITH DRYING AT
MID AND UPPER LEVELS. HOWEVER...SOME BL TO 850 MB MOISTURE WILL
LIKELY LINGER IN THE NRLY FLOW FOR SOME ATTENDANT CLOUDS TO DEVELOP
AND KEEP MINS ABOVE NORMAL VALUES.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 200 AM EDT FRIDAY...AS UPPER TROF CONTINUES TO MOVE OFF THE
EAST COAST...SURFACE COLD FRONT WILL HAVE PUSHED INTO THE EXTREME
SOUTHEAST NEAR THE I10 CORRIDOR. SFC HIGH PRESSURE WILL BEGIN TO
BUILD IN ACROSS THE GREAT LAKES REGION BEHIND THE EXITING UPPER
TROF. DUE TO THE WEAK NATURE OF THE BOUNDARY THAT PASSED THROUGH
THE PREVIOUS DAY...SFC DEWPOINTS WILL STILL BE IN THE UPPER 60S
ACROSS THE NC/SC PIEDMONT REGIONS THUS KEEPING POTENTIAL FOR SOME
SCATTERED SHOWERS ELEVATED DURING THE DAY ON SATURDAY. FURTHER WEST
ACROSS THE MOUNTAINS...EVEN THOUGH MOISTURE IS SLIGHTLY
LOWER...DYNAMIC UPSLOPE FORCING COULD PROVIDE ENOUGH LIFT FOR SOME
CONVECTION INTO THE AFTERNOONS HOURS. THUS FOR SATURDAY...KEPT
SLIGHT CHANCE POPS ACROSS THE PIEDMONT REGIONS AS DIURNAL HEATING
WILL COMBINE WITH ABOVE MENTIONED UPPER 60S DEWPOINTS TO CREATE AT
LEAST SOME SURFACE BASED INSTABILITY...THEREFORE SHOWERS COULD NOT
BE RULED OUT. AS FOR THE HIGH TERRAIN...HIGHLIGHTED SLIGHTLY HIGHER
CHANCE POPS DUE TO UPSLOPE COMPONENT. TAPERED POPS BACK DURING THE
OVERNIGHT HOURS ACROSS THE ENTIRE REGION. TEMPERATURES ON SATURDAY
LOOK TO BE A FEW DEGREES BELOW NORMAL.
SUNDAY IS LOOKING LIKE A RATHER NICE DAY ACROSS THE REGION. SFC
HIGH PRESSURE WILL SLOWLY DRIFT SOUTHEAST DURING THE EARLY MORNING
HOURS...THUS STRENGTHENING NORTHEAST FLOW ALLOWING A WEAK WEDGE TO
DOMINATE THE REGION. AS DRIER AIR IS ADVECTED IN...MODEL GUIDANCE
REMAINS IN GOOD AGREEMENT WITH REGARDS TO LACK OF INSTABILITY AS
MOISTURE AXIS SHIFTS SOUTH. THEREFORE KEPT POPS OUT OF THE FORECAST
FOR SUNDAY ACROSS THE ENTIRE REGION. ALTHOUGH TEMPERATURES WILL
REMAIN IN THE LOWER 80S ON SUNDAY...IT SHOULD FEEL MORE PLEASANT
OUTSIDE AS LOWER DEWPOINTS REDUCE HUMIDITY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE
EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER
RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY
NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE
ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A
WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A
HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE
APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL
FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS
OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL
PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE
END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS
DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO
MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST
OF NEXT WEEK.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...A LINE OF THUNDERSTORMS IS ORGANIZING 40 TO 50 MILES
NORTHWEST OF THE AIRFIELD. IT SHOULD CONTINUE MOVING SOUTHEAST AND
WILL LIKELY ACCELERATE A LITTLE AS IT DOES. TEMPO THUNDER HAS BEEN
MOVED UP AN HOUR...FROM 19-22 UTC. STORMS ARE SHOWING 30-35KT
INBOUNDS ON TDWR. THE LINE SHOULD STRENGTHEN SOME AS IT APPROACHES
AND I/VE ADDED A PERIOD OF 35 KT GUSTS TO THE TAF. I WENT
VARIABLE...THOUGH THE STRONGEST WINDS ARE LIKELY TO BE ORIENTED OUT
OF THE NORTH. SCT SHRA AND A FEW TSTMS WILL PERSIST INTO THE LATE
EVENING HOURS. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS
THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO
THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND
TWRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH.
ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST ACROSS THE
NC AND SC PIEDMONT THIS AFTERNOON AND EVENING. THE QUESTION IS HOW
FAR TO THE SOUTHWEST THE LINE WILL BUILD. THE MODELS HAVE GOOD
CONVERGENCE WELL INTO THE UPSTATE...SO I THINK THE LINE WILL BUILD
TO THE SOUTHWEST AND I/VE ADDED TEMPO THUNDER IN AT KGMU/KGSP
STARTING AT 20 UTC. THE LINE IS PRACTICALLY ON TOP OF HKY AND THEY
HAVE A TEMPO FOR THE NEXT COUPLE HOURS. I/M NOT AS CONFIDENT OF KAND
AND TEMPO WAS LEFT OUT OF THAT SITE. KAVL WILL PROBABLY SEE
SOMETHING SO THEY GOT A TEMPO AS WELL. LATER TONIGHT MVFR CIGS WILL
DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE.
THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES.
AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS
MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS
AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER
SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER
THE UPSTATE AND AT KCLT.
OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY
BUILDS IN FROM THE NORTH OVER THE WEEKEND.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 85% HIGH 85%
KGSP HIGH 100% HIGH 100% HIGH 80% HIGH 97%
KAVL HIGH 100% MED 77% LOW 51% LOW 56%
KHKY HIGH 100% HIGH 94% LOW 42% HIGH 81%
KGMU HIGH 100% HIGH 100% HIGH 83% 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...CDG
NEAR TERM...HG/MCAVOY
SHORT TERM...CDG
LONG TERM...VISIN
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
600 PM CDT FRI AUG 23 2013
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 307 PM CDT FRI AUG 23 2013
MAIN SHORT TERM CONCERN IS SHOWER/THUNDERSTORM CHANCES.
WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON SHOWING A PERSISTENT
DEEP TROUGHS OF LOW PRESSURE ALONG THE WEST AND EAST COASTS WHILE
AMPLIFYING RIDGE WAS BUDGING SLOWLY FROM THE INTERMOUNTAIN WEST INTO
THE CENTRAL CONUS. AT THE SURFACE...HIGH PRESSURE WAS CENTERED OVER
THE GREAT LAKES REGION. INCREASING SOUTH/SOUTHEAST FLOW WAS NOTED
ACROSS OUR AREA ON THE BACKSIDE OF THE HIGH WITH TEMPERATURES IN THE
UPPER 70S TO LOWER 80S.
CURRENTLY WATCHING WATER VAPOR CLOSELY GIVEN MONSOONAL FLOW TAP INTO
THE INTERMOUNTAIN WEST WITH EMBEDDED SHORTWAVE TROUGH/MCV ACTIVITY.
ONE SUCH WAVE WAS NOTED MOVING OUT OF WY INTO SD AT THIS TIME. THIS
WAVE IS EXPECTED TO PROPAGATE EASTWARD TO THE AREA LATE TONIGHT INTO
SATURDAY AND INTERACT WITH AN APPROACHING WARM FRONT. ALSO OF NOTE
WILL BE EASTERN PERIPHERY OF INCREASING ISENTROPIC LIFT AND MOISTURE
TRANSPORT IMPINGING ON THE AREA. BOTTOM LINE WILL BE INCREASING
MID-LEVEL CLOUD COVER ALONG WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE MISSISSIPPI RIVER AFTER MIDNIGHT...
AND THEN ACROSS THE REST OF THE AREA SATURDAY. NAM HAS MLCAPE VALUES
IN THE 1000-1500J/KG RANGE ACROSS WESTERN WI INTO SOUTHEAST
MN/NORTHEAST IA WITH 1-6KM BULK SHEAR VALUES IN THE 20-25KT RANGE.
GIVEN THIS FACT...WILL HAVE TO WATCH FOR AN ISOLATED VIGOROUS STORM
WITH HEAVIER DOWNPOUR/SMALL HAIL THREAT. OTHERWISE...LOWS
TONIGHT ARE EXPECTED TO BOTTOM OUT IN THE UPPER 50S TO THE MIDDLE
60S WITH HIGHS SATURDAY IN THE 80-85 DEGREE RANGE.
APPEARS BULK OF SHOWER/THUNDERSTORM ACTIVITY SHOULD PUSH NORTHEAST
OF THE AREA WIT THE PASSAGE OF THE WARM FRONT. HOWEVER...MOISTURE
TRANSPORT VECTORS STILL FOCUS ACROSS PORTION OF THE AREA MAINLY
NORTH OF I-94 THROUGH THE NIGHT. AS SUCH...KEPT A 20-30 PERCENT
PROBABILITY OF SHOWERS/THUNDERSTORMS ACROSS THAT AREA. WITH
INCREASING HUMIDITY AND GETTING INTO THE WARM SECTOR...LOWS SATURDAY
NIGHT EXPECTED TO BOTTOM OUT IN THE UPPER 60S TO LOWER 70S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 23 2013
MAIN TOPIC OF CONCERN THROUGH THE LONG TERM PERIOD WILL BE
INCREASING HEAT WITH BUILDING MID/UPPER LEVEL RIDGE OVER THE CENTRAL
CONUS AND UPPER MISSISSIPPI RIVER VALLEY REGION. HOWEVER...MAY SEE A
COUPLE WEAK TROUGH PASSAGES WITH SHOWER/THUNDERSTORM CHANCES. AS A
RESULT...NOT OVERLY CONFIDENT ON HEAT HAZARD HEADLINE AREA PLACEMENT
AT THIS TIME. IT APPEARS AT THIS TIME...THE HIGHEST LIKELIHOOD FOR
HEAT HAZARD HEADLINES WOULD BE FROM I-94 AND SOUTH...WHICH IS
ENTRENCHED MORE INTO THE RIDGE. AREAS NORTH AND EAST OF THIS WILL BE
SUSCEPTIBLE TO THESE WEAK TROUGH PASSAGES AND POTENTIAL FOR
THUNDERSTORM COMPLEXES ROLLING THROUGH. IT APPEARS HEAT INDEX
CRITERIA FOR HEADLINES //100 DEGREES +// WILL BE MET MONDAY AND
TUESDAY AFTERNOONS AND EARLY EVENINGS. AS A RESULT...WILL PROBABLY
HOLD OFF ON ANY HEAT HEADLINE ISSUANCE FOR NOW.
TEMPERATURE/HEAT DETAILS...
ECMWF AND GFS BEGIN TO HEAT THINGS UP ON SUNDAY. GOOD
MIXING/SOUTHWEST BREEZE WILL COMBINE WITH 925 TEMPERATURES IN THE
27-29C RANGE FOR HIGHS IN THE 90-95F DEGREE RANGE. GOOD MIXING
SHOULD DECREASE HUMIDITY SOMEWHAT WITH HEAT INDICES TOPPING OFF IN
THE 95-100 DEGREE RANGE.
HIGHER HUMIDITY WITH TEMPERATURES TOPPING OFF IN THE LOWER/MIDDLE
90S MONDAY AND TUESDAY WILL PUSH HEAT INDICES INTO THE 100-105
DEGREE RANGE...ESPECIALLY SOUTHWEST OF I-94. THESE DAYS WILL NEED AT
LEAST A HEAT ADVISORY.
WEDNESDAY/THURSDAY/FRIDAY LOOKING A BIT MORE UNCERTAIN WITH THE
23.12Z ECMWF/GFS SHOWING COOLING 925MB TEMPERATURES WITH TROUGH
PASSAGE THROUGH PARTS OF THE AREA/GREAT LAKES REGION. THIS WOULD
KEEP THE AREA BELOW HEAT ADVISORY CRITERIA WITH THE POSSIBLE
EXCEPTION OF NORTHEAST IA INTO FAR SOUTHWEST WI WEDNESDAY AFTERNOON.
MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 600 PM CDT FRI AUG 23 2013
A WARM FRONT WILL GRADUALLY LIFT NORTHEAST ACROSS THE REGION LATER
TONIGHT/EARLY SAT. NOT A BIG SHIFT IN THE WINDS...AND NOT MUCH
CONVERGENCE AROUND IT. HOWEVER...MESO MODELS POINT TO SOME LOW LEVEL
WARM AIR/ISENTROPIC CONVERGENCE WITH IT...ALTHOUGH NOT A WHOLE LOT
OF SATURATION THROUGH THE COLUMN PER BUFKIT SOUNDINGS. SEE SOME
SCT-BKN CLOUDS...BUT NOT MUCH IN THE WAY OF PCPN AT THIS TIME. THAT
SAID...THE HRRR SUGGESTS A THIN LINE OF SCT-BKN -SHRA COULD TRACK
ACROSS KLSE NEAR 12Z. OVERALL...THINK THE BETTER CHANCES FOR
KRST/KLSE WILL COME LATER IN THE DAY SAT/SAT NIGHT...AS THE TAF
SITES GET UNDER STRONGER SOUTHERLY FLOW. BULK OF THE MOISTURE
TRANSPORT SHIFTS NORTH BY THE THEN THOUGH...AS DOES THE STRONGEST
THERMODYNAMICS. PLUS...WITH AMPLE LOW LEVEL WARM AIR COMES A
CAP...SERVING TO INHIBIT CONVECTION. BEST SHRA/TS WILL LIKELY HOLD
NORTH OF KRST/KLSE THROUGH SAT NIGHT AS A RESULT.
HIGH PRESSURE EXITS EAST TONIGHT...WITH A TIGHTENING PRESSURE
GRADIENT WORKING IN OVERNIGHT. SFC WINDS SHOULD NOT LIGHTEN UP TOO
MUCH AS A RESULT...WITH BUFKIT SOUNDINGS INDICATING GOOD STIRRING BY
200 FT. THUS...WINDS WILL BE THE MAIN LIMITING FACTOR TO ANY FOG
POTENTIAL. EXPECT HIGHER GUSTS SAT AFTERNOON AS WINDS BEGIN TO MIX.
&&
.CLIMATE...
ISSUED AT 307 PM CDT FRI AUG 23 2013
HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR
DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE
INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
CLIMATE......DAS/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1220 PM CDT FRI AUG 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 258 AM CDT FRI AUG 23 2013
MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES
TONIGHT.
CURRENTLY AS OF 07Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE
PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL
RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE
U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER
OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND
TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED
WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG
WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER
VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER
THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90
AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS
ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING
CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM
EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG
IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG
ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS
RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL.
HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE
SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA.
SYNOPTIC OVERVIEW...
MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY
EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE
RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED
OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL
SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS
SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA
TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE
FORECAST AREA.
DETAILS...
QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF
THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES
START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN
SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO
DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING
HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG
SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM.
HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS...
DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL
INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM
THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO
CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING...
ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET.
THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST
THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z
SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN
PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE
EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z
NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE
TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER
NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 258 AM CDT FRI AUG 23 2013
HAZARDS...
THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS
LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF
THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY
ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT
THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY
FOR MONDAY AND TUESDAY.
SYNOPTIC OVERVIEW...
23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84
HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY
LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG
TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER
MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS
AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL
ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE...
MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN
MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A
PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE
BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE
DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO
THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE.
PRECIPITATION DETAILS...
FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE
850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST
ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE
MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN
ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE
COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY
ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE
COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE...
HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF
20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH
INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME
LOCALLY HEAVY RAIN.
PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT
WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT
CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA
BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z
GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS
DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN
NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS
IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT
CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER
MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY
BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z
ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE...
FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR
SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND
BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY
ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE.
FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES
NEEDED EACH DAY IN THIS AREA.
TEMPERATURE DETAILS...
FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS
OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR
MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST
WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE
AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER.
TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB
TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY
PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING
TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S.
HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE.
MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER
THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN
30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF
90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO
SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE
DAYS WILL NEED AT LEAST A HEAT ADVISORY.
WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z
ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND
WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST
AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS
EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE
COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR
NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT
ADVISORY CONDITIONS.
LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW
TO MID 70S EVERY NIGHT.
GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY
MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS
AT THIS TIME.
NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1220 PM CDT FRI AUG 23 2013
RESIDUAL LOWER LEVEL MOISTURE TRAPPED UNDER A SHALLOW INVERSION
CONTINUES TO IMPACT THE TAF SITES EARLY THIS AFTERNOON WITH SCT-BKN
MVFR CLOUDS/CIGS. DIURNAL WARMING/MIXING IS GRADUALLY RAISING THE
CLOUD/CIG HGTS...BUT DISTANCE-SPEED TOOL AND WEAK LOW LEVEL WINDS
SHOWS THIS MOISTURE/CLOUDS TO CONTINUE IMPACTING THE TAF SITES INTO
MID AFTERNOON. HAVE ADDED SOME SCT-BKN CU/STRATO-CU DECKS TO TAFS
THRU 20Z. GOOD VFR THEN EXPECTED LATER THIS AFTERNOON/EVENING AS
THESE CLOUDS/MOISTURE MOVE NORTH OF THE TAF SITES. SOME MVFR VSBYS
IN HZ/BR EXPECTED LATER TONIGHT...WITH SOUTH TO SOUTHEAST GRADIENT
WINDS KEEPING BOUNDARY LAYER STIRRED ENOUGH TO KEEP LATE NIGHT/EARLY
MORNING IFR VSBYS IN BR/FG ISOLATED.
A WARM FRONT AND INCREASING MOISTURE/LIFT IN THE 850-700MB LAYER
SPREADS NORTHEAST ACROSS THE AREA LATER TONIGHT/SAT. WIDELY SCT TO
SCT SHRA AND A FEW TSRA EXPECTED AS THIS FRONT/FORCING MOVE ACROSS
THE TAF SITES. LEFT THIS VCSH AT BOTH KRST/KLSE WITH BKN CIGS IN THE
4K-5K FT RANGE AS THE FRONT PASSES. ANY CLOUDS/CIGS BEHIND THE WARM
FRONT ON SAT SHOULD REMAIN ABOVE THE 4K-5K FT LEVEL.
&&
.CLIMATE...
ISSUED AT 343 AM CDT FRI AUG 23 2013
GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR
LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE
INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
SUN 8/25 97/1948 97/1948
MON 8/26 96/1991 95/1955
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS
CLIMATE......AJ