Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/01/13


AREA FORECAST DISCUSSION
NWS PHOENIX AZ
935 PM MST THU AUG 29 2013 .UPDATE...UPDATED AVIATION DISCUSSION. && .SYNOPSIS... THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT WEEK. && .DISCUSSION... CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA. LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL AREAS EXCEPT FOR AZZ024. FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN CONSIDERABLY ABOVE CLIMO. && .PREVIOUS DISCUSSION... FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING. THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA. TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT HIGHS NEAR 100 BOTH DAYS. NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER DESERTS. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... ISOLATED THUNDERSTORMS REMAIN A THREAT OVERNIGHT...THOUGH CHANCES ARE CONSIDERABLY HIGHER ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. OTHERWISE...MID CLOUDS WILL PERSIST INTO FRIDAY WITH CIGS AROUND 12-15K FT. CONVECTION IS EXPECTED TO REDEVELOP FRIDAY AFTERNOON ACROSS SOUTH-CENTRAL AZ...THOUGH IT REMAINS HIGHLY UNCERTAIN AS TO EXACTLY WHERE/WHEN THIS WILL OCCUR. CONDITIONS REMAIN EXCEPTIONALLY MOIST SO IT IS MORE LIKELY THAT LIGHTNING AND WET RUNWAYS WILL BE MORE A FACTOR THAN WIND/DUST IMPACTS. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... CONVECTION HAS ENDED ACROSS THE AREA...THOUGH THERE IS A SLIGHT CHANCE THAT ADDITIONAL STORMS WILL AFFECT KBLH OVERNIGHT. FOR FRIDAY...SHOWERS AND THUNDERSTORMS ARE GENERALLY EXPECTED TO REMAIN WELL NORTH OF THE AREA AND ALONG THE PENINSULAR RANGES OF SOUTHERN CA. TAF FORECAST IS CONSEQUENTLY WEIGHTED TOWARDS CLIMO. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY... FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN LOCATIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH PREVIOUS DISCUSSION...KUHLMAN AVIATION...HIRSCH FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
900 PM MST THU AUG 29 2013 .SYNOPSIS... THE REST OF THIS WEEK WILL SEE INCREASED MONSOON ACTIVITY WITH THE POTENTIAL FOR LOCALIZED HEAVY RAINFALL AS A WEATHER DISTURBANCE AND A VERY MOIST AIRMASS AFFECT THE REGION. MUCH COOLER AND CLOUDY CONDITIONS ARE EXPECTED FRIDAY WITH TEMPERATURES REMAINING BELOW NORMAL THROUGH THE WEEKEND. A RETURN TO A MORE TYPICAL MONSOON PERIOD WITH WARMER TEMPERATURES IS EXPECTED FROM SUNDAY INTO NEXT WEEK. && .DISCUSSION... CONVECTION THIS AFTERNOON AND EVENING HAS GENERALLY BEEN SCATTERED IN COVERAGE BUT PREVALENT ACROSS A LARGE AREA AS FAR WEST AS SE CA. LATEST GPS-IPW IN TEMPE MEASURED MORE THAN 2 INCHES AND WITH THE ANOMALOUSLY MOIST AIR MASS IN PLACE...MAIN CONCERN HAS BEEN LOCALIZED HEAVY RAIN AND FLOODING. TEMPERATURES THIS EVENING HAVE DROPPED INTO THE 80S ACROSS THE LOWER DESERTS WHICH HAS CUT DOWN ON THE SURFACE-BASED INSTABILITY. ANOTHER FACTOR WHICH APPEARS TO HAVE INHIBITED CONVECTION IS THE PRESENCE OF WEAK MID-LEVEL LAPSE RATES ASSOCIATED WITH A WARM LAYER NEAR 450 MB EVIDENT ON THE 00Z PSR SOUNDING. LATEST RADAR SHOWS LITTLE IN THE WAY OF SHOWER AND THUNDERSTORM ACTIVITY...EXCEPT FOR SCATTERED CELLS ACROSS THE HIGHER TERRAIN WELL EAST OF PHOENIX. FLOOD WATCH HAS BEEN CANCELLED FOR ALL AREAS EXCEPT FOR AZZ024. FOR THE REMAINDER OF TONIGHT...ISOLATED ACTIVITY FORCED BY A WELL-DEFINED VORT MAX ACROSS EAST-CENTRAL AZ WILL PERSIST ACROSS SOUTHERN GILA COUNTY. THIS WILL LIKELY TRIGGER ADDITIONAL CELLS FURTHER WEST...PERHAPS INTO EASTERN MARICOPA AND PINAL COUNTIES...THOUGH ALL HI-RES GUIDANCE INCLUDING THE HRRR INDICATES THAT STORMS WILL BE ON A DOWNWARD TREND THROUGH MIDNIGHT. LATEST WV IMAGERY ALSO SHOWS A WELL-FORMED MCS NEAR LAKE HAVASU WHICH SUGGESTS THE POTENTIAL FOR GRAVITY WAVE PROPAGATION INTO EASTERN RIVERSIDE COUNTY AND JTNP. DEWPOINTS AS HIGH AS THE UPPER 70S PERSIST ACROSS SE CA AND ADDITIONAL CONVECTION CANNOT BE RULED OUT OVERNIGHT IN THESE AREAS. POPS WERE LOWERED THROUGH MORNING BUT REMAIN CONSIDERABLY ABOVE CLIMO. && .PREVIOUS DISCUSSION... FRIDAY SHOULD ALSO BE AN ACTIVE DAY WITH LITTLE TO NO CHANGE IN AIRMASS CONDITIONS AND MODELS INDICATE THE SHORTWAVE NOW OVER NEW MEXICO SLIDES WESTWARD INTO CENTRAL ARIZONA LATE TONIGHT INTO FRIDAY MORNING. THE COVERAGE OF STORMS ON FRIDAY WILL LIKELY AGAIN DEPEND ON THE AMOUNT OF INSOLATION...BUT AREAWIDE PWATS OF 1.75 TO 2 INCHES SHOULD ALLOW FOR SOME LOCALIZED HEAVY RAINFALL AND FLOODING. THE TROPICAL MOISTURE FEED WILL GRADUALLY SHIFT TO THE SOUTHWEST THIS WEEKEND ALLOWING FOR A GRADUAL DECREASE IN MOISTURE ACROSS THE DESERT SOUTHWEST. BOTH THE GFS AND EUROPEAN INDICATE SOME SORT OF LINGERING INVERTED TROUGH ACROSS THE NORTHERN HALF OF ARIZONA...ALLOWING FOR MUCH OF THE MONSOON ACTIVITY TO BE FOCUSED ALONG THE MOGOLLON RIM AND HIGHER TERRAIN LOCATIONS OF EASTERN ARIZONA. STILL EXPECTING MONSOON ACTIVITY ACROSS SOUTHERN ARIZONA TO BE SOMEWHAT ACTIVE...BUT WILL MOSTLY BE RELIANT ON OUTFLOWS FOR DEVELOPMENT ACROSS THE LOWER DESERTS. A GRADUAL DECREASE IN POPS IS IN THE FORECAST FOR SATURDAY WITH SLIGHT CHANCE POPS FURTHER WEST AND CHANCE POPS ACROSS MUCH OF SOUTH-CENTRAL ARIZONA. SUNDAY SHOULD SEE EVEN LESS STORM CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA AS DRY AIR STARTS TO FILTER IN FROM THE WEST...BUT CHANCE POPS IS AGAIN EXPECTED ACROSS SOUTH-CENTRAL ARIZONA. TEMPERATURES WILL GRADUALLY WARM UP THIS WEEKEND WITH LOWER DESERT HIGHS NEAR 100 BOTH DAYS. NEXT WEEK IS SHAPING UP TO BE A TRANSITION FROM A SEMI-ACTIVE TO NEAR NORMAL MONSOON PERIOD ON MONDAY AND TUESDAY TO DRIER AND WARMER CONDITIONS FOR THE LATER PART OF NEXT WEEK. LONG RANGE MODELS SHOW THE SUB-TROPICAL HIGH CENTERING ITSELF OVER COLORADO AND HEIGHTS BUILDING ACROSS THE REGION. BY LATE NEXT WEEK...HIGH TEMPERATURES COULD BE TOPPING OUT IN THE 105-108 RANGE ACROSS THE LOWER DESERTS. && .AVIATION... SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH... ABUNDANT MOISTURE AVAILABLE FOR SHOWERS TO OCCUR JUST ABOUT ANYWHERE. HOWEVER...AREAS WHERE MORE SUNSHINE REACHES THE GROUND WILL HAVE BETTER INSTABILITY. AS OF 18Z THOSE AREAS WOULD INCLUDE NORTHWEST MARICOPA COUNTY...LA PAZ COUNTY...AND YUMA COUNTY. AN ADDITIONAL FACTOR FOR SHWR/TSTM PRODUCTION WILL BE A CIRCULATION CENTERED NEAR NORTHERN BAJA MEXICO. MODELS INDICATE A SWATH OF ENHANCED LIFT FOR THIS AFTERNOON AND EVENING...ASSOCIATED WITH THE BAJA FEATURE...ACROSS SOUTHWEST MARICOPA COUNTY...YUMA COUNTY...AND IMPERIAL COUNTY. FOR THE ABOVE REASONS...INCLUDED TEMPO SHWRS/TSTMS IN THE TAFS. EVEN WITHOUT A FULL FLEDGED TSTM...CEILINGS AND VISIBILITY WILL BE LOWERED SUBSTANTIALLY BY ANY RAIN SHOWERS. OF NOTE...THERE IS CONSIDERABLE UNCERTAINTY IN THE TIMING AND EXTENT OF THE ABOVE MENTIONED FACTORS INFLUENCING THE CONVECTION. WINDS WILL FAVOR SOUTHWEST DIRECTIONS OVER THE PHOENIX AREA AND SOUTH/SOUTHEAST DIRECTIONS OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... TROPICAL MOISTURE WILL GRADUALLY DIMINISH SATURDAY THROUGH THE MIDDLE OF NEXT WEEK...AS MONSOON CONDITIONS RETURN TO CLIMATIC NORMALS. BELOW SEASONAL NORMAL HIGH TEMPERATURES SATURDAY WILL STEADILY CLIMB AND REACH TO NORMAL VALUES BY ABOUT TUESDAY...AND ELEVATED HUMIDITIES SATURDAY WILL GRADUALLY LOWER DAY TO DAY... FINALLY FALLING INTO THE TEENS BY NEXT WEDNESDAY. WINDS WILL GENERALLY FOLLOW NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON AND EARLY EVENING GUSTINESS...ESPECIALLY OVER FAVORED HIGHER TERRAIN LOCATIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING AZZ024. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH PREVIOUS DISCUSSION...KUHLMAN AVIATION...AJ FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1126 AM MDT FRI AUG 30 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 453 AM MDT FRI AUG 30 2013 CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S ACROSS THE LOWER ELEVATIONS AT THIS TIME. TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN 2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD AT PUB OF 102F IN 1990 LOOKS SAFE. CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE SEASONAL AVERAGES. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 402 AM MDT FRI AUG 30 2013 ...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO MOST AREAS THIS WEEKEND... MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL. ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE... KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY. NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS. SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES... BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON PLUME. LW && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1000 AM MDT FRI AUG 30 2013 VFR CONDITIONS EXPECTED AT THE TAF SITES TODAY WITH ISOLATED THUNDERSTORMS EXPECTED TO DEVELOP OVER THE MOUNTAINS AROUND 17Z. KALS HAS THE BEST CHANCE FOR SEEING VCTS...HOWEVER THERE IS SOME CHANCE THAT KCOS COULD AS WELL. WILL CARRY VCTS IN KALS TAF FOR NOW AND MONITOR LATEST RADAR TRENDS FOR POSSIBLE INCLUSION IN KCOS. GUSTY ERRATIC WINDS WILL BE THE MAIN THREATS WITH THUNDERSTORMS ALONG WITH LIGHTNING. SOME BRIEF MODERATE TO HEAVY RAINFALL WILL BE POSSIBLE WITH STORMS ALONG THE CONTINENTAL DIVIDE THIS AFTERNOON AND EVENING. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MW LONG TERM...LW AVIATION...KT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
454 AM MDT FRI AUG 30 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 453 AM MDT FRI AUG 30 2013 CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING LARGE UPPER HIGH REMAINING IN PLACE ACROSS THE HIGH PLAINS THROUGH THE ROCKIES WITH FASTER ZONAL FLOW NOTED ACROSS THE NORTHERN TIER OF STATES AT THIS TIME. WATER VAPOR IMAGERY AND SATELLITE DATA INDICATING AN INCREASE IN ATMOSPHERIC MOISTURE ACROSS SOUTH CENTRAL AND SOUTHEAST COLORADO ALONG WITH AN EMBEDDED SHORT WAVE TRANSLATING ACROSS THE NORTHERN GREAT BASIN AT THIS TIME. WARM AIR ALOFT ALSO REMAINS IN PLACE UNDERNEATH THE UPPER HIGH WITH CURRENT TEMPS IN THE MID 40S TO MID 50S ACROSS THE HIGHER TERRAIN AND 60S TO LOWER 70S ACROSS THE LOWER ELEVATIONS AT THIS TIME. TODAY AND TONIGHT...WITH A TAD MORE MOISTURE IN PLACE...ALONG WITH TAIL END OF NORTHERN GREAT BASIN SHORT WAVE TRANSLATING ACROSS THE NORTHERN PORTIONS OF THE STATE THIS AFTERNOON...SHOULD SEE AN UPSWING IN CONVECTION OVER AND NEAR THE HIGH TERRAIN THIS AFTERNOON AND EARLY EVENING...WITH BEST COVERAGE EXPECTED ACROSS THE CENTRAL MTS. HAVE ALSO INCREASED POPS ACROSS TELLER COUNTY AND THE PALMER DVD LATE THIS AFTERNOON AND EVENING WITH LATEST RUNS OF THE HIGHER RESOLUTION HRRR AND RAP MODELS COMING MORE IN LINE WITH THE MORE AGGRESSIVE NAM. AT ANY RATE...MODEL SOUNDINGS STILL INDICATING CONVECTION TO BE RATHER HIGH BASED ACROSS THE EASTERN MTS WITH NOT MUCH MEASURABLE PRECIPITATION EXPECTED. TEMPS AGAIN TO WARM RATHER QUICKLY THIS MORNING...THOUGH WITH MORE CONVECTIVE CLOUD COVER...SHOULD SEE HIGHS NEAR OR ONLY SLIGHTLY COOLER THAN YESTERDAYS READINGS. COULD SEE NEAR RECORD HIGHS AT ALS (86F IN 2012) AND COS (94F IN 1990) ONCE AGAIN TODAY...THOUGH CURRENT RECORD AT PUB OF 102F IN 1990 LOOKS SAFE. CONVECTIVE DIMINISHES THROUGH THE EVENING WITH DEBRIS CLOUDS SLOWLY DIMINISHING THROUGH THE OVERNIGHT...KEEPING LOWS GENERALLY ABOVE SEASONAL AVERAGES. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 402 AM MDT FRI AUG 30 2013 ...CHANCE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAIN RETURNING TO MOST AREAS THIS WEEKEND... MODELS INDICATING THAT A SHORTWAVE AND LOW LEVEL FRONTAL SYSTEM WILL DROP SOUTHEAST THROUGH THE CENTRAL PLAINS SATURDAY AFTERNOON AND EVENING...RESULTING IN LOW LEVEL UPSLOPE ON THE PLAINS...AND TAPPING MONSOON MOISTURE ALOFT. THE INTERACTION OF THE 2 WILL RESULT IN FAIRLY WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE AREA SATURDAY AFTERNOON AND EVENING...WITH ENOUGH MOISTURE PRESENT TO PRODUCE LOCALLY HEAVY RAINFALL. SO...THE THREAT OF FLOODING WILL RAMP UP ONCE AGAIN FOR AREA BURN SCARS...AS WELL AS FOR OTHER AREAS...AWAY FROM THE BURN SCARS. OTHER POSSIBLE THREATS WILL INCLUDE LIGHTNING...GUSTY WINDS AND SMALL HAIL. ELEVATED CHANCES FOR RAIN AND FLASH FLOODING WILL PROBABLY CONTINUE FOR A LOT OF AREAS AT LEAST THROUGH SUNDAY. THERE ARE MIXED SIGNALS FOR WHAT TO EXPECT ACROSS THE PLAINS ON SUNDAY. SOME MODEL RUNS SHOW FAIRLY WIDESPREAD SHOWERS AND HEAVY RAIN POTENTIAL ACROSS THE PLAINS ON SUNDAY...WHILE OTHERS HOLD ALL THE SHOWERS AND HEAVY RAIN POTENTIAL BACK OVER THE MOUNTAINS AND HIGH VALLEYS. SO...IT SEEMS PRETTY CLEAR THE MOUNTAINS AND HIGH VALLEYS WILL HAVE ANOTHER ACTIVE DAY...BUT IT IS LESS CLEAR EXACTLY WHAT WILL HAPPEN ON THE PLAINS. FOR NOW...FORECASTS ARE SORT OF SPLITTING THE DIFFERENCE... KEEPING THE COVERAGE OF STORMS SOMEWHERE IN THE MIDDLE...GENERALLY IN THE SCATTERED CATEGORY. IN ANY EVENT...WHATEVER STORMS MANAGE TO FORM WILL ALSO HAVE THE POTENTIAL FOR LOCALLY HEAVY RAIN...SO THE THREAT TO AREA BURN SCARS WILL REMAIN HIGH ON SUNDAY. NEXT WEEK...IT APPEARS UPPER HIGH PRESSURE WILL REORGANIZE AND RECENTER OVER EASTERN COLORADO. THIS WILL PROBABLY RESULT IN CONTINUED MONSOON CONVECTION OVER THE MOUNTAINS...BUT WITH DRIER AND WARMER CONDITIONS AGAIN OVER MOST OF THE PLAINS. SOME ACTIVITY COULD CREEP EAST ACROSS THE PLAINS AT TIMES... BUT THE BULK OF THE ACTIVITY WILL PROBABLY REMAIN OVER THE HIGH COUNTRY. THIS MEANS THAT THE WATCH FOR FLASH FLOODING ON AND NEAR AREA BURN SCARS WILL CONTINUE NEXT WEEK AS ALL OF THE BURN SCARS WILL LIKELY REMAIN UNDER THE MONSOON PLUME. LW && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 402 AM MDT FRI AUG 30 2013 VFR CONDITIONS EXPECTED FOR THE NEXT 24 HRS AT COS...PUB AND ALS WITH LARGE UPPER HIGH IN PLACE ACROSS THE HIGH PLAINS THROUGH THE ROCKIES. ENOUGH MOISTURE REMAINS IN PLACE UNDER RIDGE FOR ISOLATED TO SCATTERED -TSRA OVER AND NEAR THE MOUNTAINS THIS AFTERNOON AND EVENING. BEST COVERAGE OF TSRA EXPECTED ACROSS THE CONTDVD THOUGH LOOKS TO BE BETTER COVERAGE OF STORMS ACROSS THE PIKES PEAK REGION THAN YESTERDAY. STILL TOO LOW OF A CHANCE TO INCLUDE IN TAFS AT THIS TIME. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MW LONG TERM...LW AVIATION...MW
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1015 PM MDT THU AUG 29 2013 .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT) ISSUED AT 242 PM MDT THU AUG 29 2013 SHOWERS AND STORMS DEVELOPED AS EXPECTED AROUND 18Z OVER THE FAVORED HIGHER TERRAIN AREAS PARTICULARLY THE ABAJOS...SAN JUANS...AND FLATTOPS. THE 12Z GJT SOUNDING SHOWED PW VALUES OF 0.95 INCHES WHICH IS MATCHING UP QUITE WELL WITH THE RAP AND THE NAM MODELS. THE GFS PWATS WERE MUCH LOWER SO THINKING THE GFS IS UNDERPLAYING THE AMT OF MOISTURE. WITH HIGH PRESSURE OVERHEAD...LIGHT STEERING FLOW WILL LEAD TO STORMS STAYING RELATIVELY ANCHORED TO THE TERRAIN WITH LITTLE MOVEMENT. SIMILAR PATTERN TO YESTERDAY...SO EXPECT MUCH OF THE SAME WITH CONVECTION ENDING SHORTLY AFTER SUNSET AND SOME STORMS LINGERING TILL MIDNIGHT. BIGGEST CONCERN FOR THE REST OF THIS AFTERNOON INTO THE EVENING IS ANY STORMS THAT FORM OVER ALREADY SATURATED AREAS...ESPECIALLY THE SAN JUANS WHERE FLOODING OCCURRED YESTERDAY IN OURAY AND OVER RED MOUNTAIN PASS. THE 12Z NAM SEEMS TO BE HANDLING THE MOISTURE BETTER THAN THE GFS SO LEANING TOWARDS IT FOR FRIDAY. PW VALUES STAY RELATIVELY THE SAME AT 0.9 INCHES ACROSS MUCH OF WESTERN COLORADO. HOWEVER PWATS INCREASE SOME OVER SE UTAH...WITH SOME OF THE DEEPER MOISTURE ASSOCIATED WITH THE INVERTED TROUGH OVER AZ AND SOCAL CREEPING INTO SE UTAH WHERE PWATS INCREASE TO A LITTLE OVER AN INCH. AN ACTIVE NORTHERN STREAM CAUSES THE RIDGE TO FLATTEN A LITTLE WHICH LAYS A 55KT JET MAX OVER THE CO-WY BORDER. IN ADDITION TO THIS...850-700MB STREAMLINES SHOW A LOW LEVEL CONVERGENCE SIGNATURE THAT MOVES THROUGH SE UTAH AND SW COLORADO FRIDAY AFTERNOON...WITH UPPER LEVEL DIVERGENCE AS INDICATED IN DIVQ FIELDS. THINKING THAT FRIDAY MAY BE A LITTLE MORE ACTIVE AND WIDESPREAD IN TERMS OF CONVECTION AS THERE IS SOME LOW LEVEL AND UPPER LEVEL SUPPORT AND SEVERAL STRONG VORT MAXES THAT MOVE THROUGH THE FLOW THAT CAN ACT AS A TRIGGER ON THE MOISTURE. THINK THERE WILL BE ENOUGH SFC HEATING TO GET THINGS GOING AGAIN AS SKIES BEGIN RELATIVELY CLEAR FRIDAY MORNING. CONVECTION WILL BEGIN FRIDAY AFTERNOON OVER THE HIGHER TERRAIN WITH SOME STORMS FORMING OVER THE VALLEYS LATER IN THE DAY AS DISTURBANCES AND BOUNDARIES INTERACT GIVEN THE ADDITIONAL FORCING. THINGS SHOULD WIND DOWN AFTER SUNSET AGAIN WITH SOME STORMS LINGERING UNTIL MIDNIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 242 PM MDT THU AUG 29 2013 THE UPPER RIDGE STAYS CENTERED OVER THE FOUR CORNERS ON SATURDAY FOR ANOTHER DAY OF MAINLY AFTERNOON THUNDERSTORMS OVER ELEVATED LOCATIONS AS SUFFICIENT 0.60 TO 1.00 PWATS REMAIN TRAPPED UNDER THE RIDGE...WITH THE DRIEST IN NORTHERN AREAS. THINKING THAT THE NORTHERN UT/CO BORDER WILL SEE SOME BETTER ORGANIZED/LONGER LIVING STORMS DESPITE THE LOWER BUT STILL GOOD ENOUGH AVAILABLE MOISTURE SATURDAY AS THE MODELS INDICATE A MODERATE 40-50 KT SPEED MAX AT 250 MB. SE UTAH AND THE SAN JUANS OF COLORADO WILL REMAIN THE MOST LIKELY LOCATION FOR STORM DEVELOPMENT WITH HEAVY RAIN AS THE BIGGEST THREAT. IN SOUTHERN AREAS WITH LOW SHEER...CELLS WILL LIKELY BE SHORT-LIVED BUT COULD CAUSE INTENSE HEAVY RAINFALL IN LOCALIZED AREAS WITHIN A SHORT PERIOD OF TIME. A FEW OF THESE STORMS MAY SURVIVE PAST SUNSET BUT OTHERWISE ARE EXPECTED TO DIMINISH AFTER DARK. A VORT MAX AXIS WILL LIE NW TO SE ACROSS OUR AREA AND HELP WITH STORM DEVELOPMENT AS WELL. DISCREPANCY OVER THE WEEKEND ON THE AMOUNT OF MOISTURE WHICH WILL REMAIN AVAILABLE BUT OVERALL TRENDS ARE SHOWING A SIMILAR PATTERN. SUNDAY IS EXPECTED TO BE SLIGHTLY DRIER UP ALONG THE WYOMING BORDER WITH OUR CWA DUE TO DRY AIR ADVECTION KICKING INTO THE REGION FROM THE NORTHWEST AND MINIMAL FORCING ALOFT...THEREFORE POPS ARE AMPLIFIED TO THE SOUTHERN HALF OF OUR AREA. THIS IS NOT EXPECTED TO LAST LONG AND WILL LIKELY KEEP A SECTION OF THE NORTHERN REGION RAIN-FREE ON SUNDAY. ELSEWHERE...ESPECIALLY DOWN IN THE SAN JUANS...ABAJOS...AND LA SALS...THE ATMOSPHERE WILL REMAIN JUICY AND ALLOW FOR STRONG DIURNAL TSTORMS IN THE AFTERNOON. MONDAY THROUGH WEDNESDAY...UPPER LEVEL HIGH PRESSURE STAYS POSITIONED OVER COLORADO THROUGHOUT THE PERIOD. MONSOONAL MOISTURE CONTINUES TO STREAM AROUND THE WRN PERIPHERY OF THE HIGH ALLOWING FOR DAILY STORM INITIATION. SHORTWAVE ON TUESDAY SLICING THROUGH THE CENTER OF THE HIGH PRESSURE WILL ALLOW FOR ENHANCED ACTIVITY ASSUMING SKIES REMAIN FAIRLY CLEAR DURING THE FIRST HALF OF THE DAY. THURSDAY COULD GET INTERESTING...BUT THIS FAR OUT THERE IS VERY LOW CONFIDENCE IN THE LONG TERM MODELS...ESPECIALLY WITH TWO VERY DIFFERENT SOLUTIONS. THE GFS IS PROGGING A STRONG PACIFIC LOW TO DROP DOWN INTO THE INTERMOUNTAIN WEST THURSDAY SWIPING WITHIN NEAR REACH OF THE REGION...FILTERING UNSEASONALLY COOL AIR INTO NORTHERN BREACHES OF THE CWA. THE EURO KEEPS THIS FEATURE ALONG THE NORTHERN ROCKIES WITHOUT MUCH INTERACTION WITH COLORADO AND UTAH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1015 PM MDT THU AUG 29 2013 VFR CONDITIONS WILL CONTINUE AT ALL TAFS SITES OVERNIGHT. SCATTERED SHOWERS WILL SLOWLY DISSIPATE OVER THE CENTRAL CO MOUNTAINS IN THE KASE AND VAIL PASS VICINITIES...WITH LOCAL MOUNTAIN OBSCURATIONS THROUGH ABOUT 09Z. FRIDAY AFTERNOON ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP AGAIN OVER THE CO CENTRAL AND SOUTHWEST MOUNTAINS...WITH BRIEF MVFR VSBYS IN STRONGER RAIN SHOWERS AT KASE...KEGE...KRIL AND KTEX. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...MDA LONG TERM...JAM AVIATION...CC
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 PM EDT FRI AUG 30 2013 .AVIATION... A WEAK UPPER LOW COMBINED WITH DAYTIME HEATING AND SEA BREEZES WILL MAINTAIN A SLIGHT CHANCE FOR SHOWERS AND STORMS ACROSS THE LOCAL AREA THROUGH THE EVENING HOURS TODAY. THE LATEST HRRR MODEL RUN INDICATES THE BULK OF THIS ACTIVITY REMAINING INLAND OF THE TAF SITES THROUGH THIS TIME. CONDITIONS SHOULD TREND DOWN THROUGH OVERNIGHT HOURS WITH THE BEST RAIN CHANCES REMAINING OVER THE ADJACENT MARINE AREAS THROUGH SATURDAY MORNING. WINDS WILL BECOME CALM OVERNIGHT ACROSS THE AREA. SIMILAR CONDITIONS ARE ANTICIPATED SATURDAY WITH ONSHORE WINDS THROUGH THE LATE MORNING AND AFTERNOON PERIODS. THE BEST RAIN CHANCES WILL REMAIN INLAND OF THE SITES. && .PREV DISCUSSION... /ISSUED 932 AM EDT FRI AUG 30 2013/ UPDATE...A MID-UPPER LEVEL LOW CONTINUES OVER SOUTH FL AS SEEN IN WATER VAPOR IMAGERY. A COMPLEX OF THUNDERSTORMS IS OCCURRING OVER THE FLORIDA STRAITS...DRIVEN BY A VORT LOBE TRAVERSING THE SOUTHERN SIDE OF THIS UPPER LEVEL LOW. THIS VORT WILL MOVE NE AND ACROSS THE BAHAMAS TODAY, KEEPING ORGANIZED CONVECTION TO OUR EAST. HOWEVER, LATEST RADAR IMAGERY SHOWS AN OUTFLOW BOUNDARY ORIGINATING FROM THIS CONVECTION MOVING NORTH AT 25 KNOTS...NOW LOCATED EAST OF THE MIDDLE TO UPPER KEYS. THIS COULD BRING A BRIEF PERIOD OF RAIN TO FAR SE MIAMI-DADE COUNTY AND THE ADJACENT WATERS IF IT HOLDS. HOWEVER, AM EXPECTING A DISSIPATING TREND AS IT ENCOUNTERS DRY LOW LEVEL AIR IN PLACE OVERHEAD. THE MIAMI SOUNDING THIS MORNING SHOWED UNUSUALLY DRY AIR IN THE 1-10K FT LAYER. THIS SHOULD ACT TO LIMIT AND DIMINISH ACTIVITY INCOMING FROM THE SOUTHEAST. HAVE PLACED CHANCE POPS SE MIAMI-DADE COUNTY FOR THE POSSIBILITY OF AT LEAST SOME RAIN MAKING IT IN THERE OVER THE NEXT FEW HOURS. THE REST OF THE FORECAST LOOKS GOOD WITH TSTORMS FOCUSING ACROSS THE LAKE REGION LATER THIS AFTERNOON. SEE PREVIOUS DISCUSSION BELOW FOR FURTHER FORECAST DETAILS BEYOND TODAY. /GREGORIA PREV DISCUSSION... /ISSUED 644 AM EDT FRI AUG 30 2013/ AVIATION... WITH A DRY, WEAK UPPER LEVEL LOW ALMOST DIRECTLY OVER SOUTH FLORIDA, FAIRLY QUIET VFR CONDITIONS AREA EXPECTED THROUGH THE DAY TODAY. THE EXCEPTION MAY BE A BRIEF PASSING SHOWER. HOWEVER, CONFIDENCE IS LOW ON ANY TAF SITES BEING AFFECTED BY ANY SHOWERS, AND WHAT SHOWERS DO DEVELOP WILL MOST LIKELY BE BRIEF. THE MOST LIKELY AREA TO SEE ACTIVITY IS KPBI. THE MAIN AREA TO SEE ANY CONVECTIVE ACTIVITY WILL BE IN THE INTERIOR AREA, CLOSER TO LAKE OKEECHOBEE. THERE IS A CHANCE OF THUNDERSTORMS IN THAT AREA AS WELL. THUS, HAVE LEFT ANY MENTION OF SHOWERS OR THUNDERSTORMS OUT OF THE TAFS AT THIS TIME. LIGHT AND VARIABLE WINDS WILL PERSIST INTO THE MID DAY. AROUND 18Z THEY ARE EXPECTED TO PICK UP OUT OF THE SE BETWEEN 5 AND 10 KTS. THEY WILL BECOME LIGHT AND VARIABLE ONCE AGAIN THIS EVENING. PREV DISCUSSION... /ISSUED 308 AM EDT FRI AUG 30 2013/ ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE FOR THE HOLIDAY WEEKEND... SHORT TERM... AN UPPER LEVEL LOW WILL REMAIN OVER SOUTH FLORIDA TODAY INTO SATURDAY...AS WEAK HIGH PRESSURE REMAINS OVER THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR A STEERING FLOW OVER SOUTH FLORIDA TO BE FROM THE SOUTHERLY DIRECTION WHICH WILL FOCUS THE SHOWER AND THUNDERSTORM ACTIVITY OVER THE LAKE OKEECHOBEE REGION TODAY AND AGAIN ON SATURDAY. THERE IS ALSO SOME DRY AIR LOCATED BETWEEN 850 MB AND 700 MB IN THE 00Z MIA SOUNDING. THIS DRY AIR WILL REMAIN IN PLACE TODAY INTO SATURDAY HELPING TO REDUCE THE SHOWER AND THUNDERSTORM ACTIVITY OVER SOUTH FLORIDA. THEREFORE...THE POPS OVER SOUTH FLORIDA WILL RANGE FROM 20 PERCENT OVER THE SOUTHERN AREAS TO 40 PERCENT OVER THE LAKE OKEECHOBEE AREA FOR TODAY AND AGAIN ON SATURDAY. THE THUNDER THREAT WILL ALSO BE LIMITED TO THE NORTHERN AREAS OF SOUTH FLORIDA FOR TODAY INTO SATURDAY WHERE THE SEA BREEZES AND LAKE BREEZE COLLIDE. THE UPPER LEVEL LOW SHOULD MOVE NORTHEAST LATE THIS LABOR DAY WEEKEND INTO THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR THE DRY AIR BETWEEN THE 700 MB AND 850 MB TO MOISTEN UP ALONG WITH THE STEERING FLOW BECOMING MORE SOUTHEAST. THE SEA BREEZES WILL ALSO DEVELOP EACH DAY AND PUSH INLAND. SO THE POPS WILL BE INCREASED TO SCATTERED COVERAGE WITH THE HIGHEST POPS OVER THE INTERIOR AREAS. LONG TERM... THE HIGH OVER THE WESTERN ATLANTIC WATERS SHOULD STRENGTHEN LATE NEXT WEEK OVER THE WESTERN ATLANTIC WATERS AND EXTEND INTO THE FLORIDA PENINSULA. THIS WILL ALLOW FOR THE EASTERLY WIND FLOW TO REMAIN IN PLACE OVER SOUTH FLORIDA LATE NEXT WEEK ALONG WITH THE DAILY SEA BREEZE DEVELOPMENT. SO WILL CONTINUE THE SCATTERED POPS OVER SOUTH FLORIDA WITH THE BEST COVERAGE OVER THE INTERIOR AREA FOR LATE NEXT WEEK. THERE IS ALSO A TROPICAL WAVE OVER THE CENTRAL ATLANTIC WATERS THAT IS FORECAST BY THE MODELS TO MOVE WEST-NORTHWEST NEXT WEEK AND POSSIBILITY OVER SOUTH FLORIDA BY END OF NEXT WEEK. IF THIS TREND CONDITIONS THEN THE POPS MAY HAVE TO BE RAISED UP FOR NEXT OF NEXT WEEK. MARINE... THE WINDS OVER SOUTH FLORIDA WATERS THIS LABOR DAY WEEKEND WILL BE FROM THE WEST TO SOUTHWEST DIRECTION AT 5 TO 10 KNOTS SWINGING TO A EASTERLY DIRECTION BY LABOR DAY. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS OVER SOUTH FLORIDA THIS LABOR DAY WEEKEND SHOULD BE GOOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS. THE THREAT OF RIP CURRENTS THIS LABOR DAY WEEKEND AT BOTH THE ATLANTIC AND GULF COAST BEACHES OF SOUTH FLORIDA LOOKS LOW AT THIS TIME AS THE WINDS WILL BE 10 KNOTS OR LESS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 76 90 77 90 / 20 30 20 40 FORT LAUDERDALE 78 89 79 89 / 10 20 20 30 MIAMI 77 90 78 90 / 10 20 20 30 NAPLES 74 89 75 89 / 10 20 20 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...57/DG AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS MIAMI FL
201 AM EDT FRI AUG 30 2013 .AVIATION... WITH A DRY, WEAK UPPER LEVEL LOW OVER SOUTH FLORIDA, CONDITIONS WILL BE MOSTLY QUIET FOR ANOTHER DAY, AS MOST CONVECTION WILL BE INLAND FROM THE TAF SITES. CONDITIONS SHOULD REMAIN VFR TODAY, ALTHOUGH THERE COULD BE STRAY SHOWER THAT BRIEFLY IMPACTS CONDITIONS, BUT GIVEN THE LOW CONFIDENCE IN THIS, HAVE KEPT MENTION OUT OF THE TAFS FOR TODAY. WINDS WILL BE LIGHT AND VARIABLE THROUGH EARLY AFTERNOON, THEN BECOME SOUTHEAST BETWEEN 5 AND 10 KTS, GOING LIGHT AND VARIABLE ONCE AGAIN THIS EVENING. && .PREV DISCUSSION... /ISSUED 858 PM EDT THU AUG 29 2013/ UPDATE... A FEW CHANGES WERE MADE TO THE SHORT TERM FORECAST...DUE TO THE LACK OF ACTIVITY THIS AFTERNOON AND EVENING. THE ONLY AREA THAT REMAINED ACTIVE WITH SOME SHOWERS AND THUNDERSTORMS WAS AROUND THE LAKE...AND NOW A FEW SHOWERS DEVELOPED FROM OUTFLOW BOUNDARIES COLLISIONS ACROSS INTERIOR MIAMI-DADE COUNTY. ALL THIS ACTIVITY WILL DISSIPATE QUICKLY AS THE NIGHT PROGRESSES. CURRENT GUIDANCE CONTINUES SHOWING THE STALLED UPPER LEVEL LOW OVER THE WESTERN HALF OF SOUTH FLORIDA THROUGH THE WEEKEND. THEREFORE...SIMILAR WEATHER CONDITIONS ARE EXPECTED THROUGH THE HOLIDAY WEEKEND. PREV DISCUSSION... /ISSUED 308 PM EDT THU AUG 29 2013/ SYNOPSIS... A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA WEAKENS THROUGH THE PERIOD. SHORT TERM...THROUGH SATURDAY NIGHT. UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE. NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION. FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF SHOWERS AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS STILL AN OFF CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING GUSTY WINDS AND LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND LOCAL HIGH RES MODELS. FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES REMAIN DOMINANT. LONG TERM...SUNDAY THROUGH NEXT THURSDAY WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL. MARINE... WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 75 90 78 / 30 20 30 20 FORT LAUDERDALE 91 78 90 81 / 30 20 30 20 MIAMI 92 77 90 79 / 30 20 30 20 NAPLES 91 74 90 75 / 30 20 30 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...17/ERA AVIATION/RADAR...13/SI
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
734 PM EDT SAT AUG 31 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH FLOW INTO THE FORECAST AREA THROUGH SUNDAY. A COLD FRONT WILL MOVE INTO THE AREA TUESDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... SOME SHOWER AND THUNDERSTORM ACTIVITY OVER OUR CENTRAL FA...WITH SCATTERED THUNDERSTORMS ACROSS THE WESTERN CAROLINAS ALONG A WEAK SURFACE TROUGH...DRIFTING SE. QUESTION AS TO HOW FAR SOUTH THIS ACTIVITY WILL GET. LATEST HRRR APPEARS TO BRING SOME OF IT INTO OUR NORTHERN FA BY WHILE INDICATING SLOW WEAKENING OF THE ACTIVITY. WILL MAINTAIN HIGHER POPS NORTHERN FA THROUGH THIS EVENING. TONIGHT...HIGH-LOW LEVEL MOISTURE AND DRY AIR ALOFT SHOULD RESULT IN CONSIDERABLE STRATUS AND OR FOG LATE TONIGHT. TEMPERATURES NEAR MOS CONSENSUS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... WV LOOP SHOWS RIDGE OF HIGH PRESSURE ANCHORED ACROSS THE FOUR CORNERS REGION. THE MODELS HINT AT A WEAK CONVERGENCE AREA/TROUGH ACROSS THE PIEDMONT THAT WILL LINGER ACROSS THE PIEDMONT/MIDLANDS THROUGH MONDAY. MODEL TIME SECTIONS INDICATE INCREASING MOISTURE THROUGH THE PERIOD. THERE WILL BE A SERIES OF SHORTWAVES THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THIS ALONG WITH THE EXPECTED COLD FRONT ARRIVING INTO THE REGION ON TUESDAY. MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS THROUGH MONDAY NIGHT. BEST CHANCE FOR SHOWERS/THUNDERSTORMS APPEARS TO BE WITH FRONT ON TUESDAY. GUIDANCE NUMBERS SHOWING QUITE A RANGE FOR DAYTIME HEIGHTS BUT REASONABLY CLOSE. HAVE STAYED CLOSE TO A CONSENSUS OF THE GUIDANCE WHICH IS CLOSE TO CLIMATOLOGY FOR HIGHS AND ABOVE CLIMO FOR LOWS. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... THE MODELS SHOW SOME DRYING BEHIND THE FRONT FOR TUESDAY NIGHT THROUGH THURSDAY BUT THE FRONT DOES APPEAR TO STALL JUST SOUTH AND EAST OF THE AREA. THE MODELS DISPLAY A MOISTURE INCREASE FOR FRIDAY AS ANOTHER SHORTWAVE/SURFACE FRONT APPROACHES FROM THE NW. THE GFS ENSEMBLE MEANS SUPPORT TEMPERATURES NEAR CLIMATOLOGY FOR TEMPERATURES. POPS DIMINISHING TUESDAY NIGHT BEHIND THE COLD FRONT. NEXT CHANCE FOR PRECIPITATION APPEARS TO BE FRIDAY AND SATURDAY. && .AVIATION /00Z SUNDAY THROUGH FRIDAY/... MAINLY VFR THIS EVENING. SCATTERED THUNDERSTORMS WILL CONTINUE ACROSS THE REGION THROUGH AROUND 04Z. MVFR OR LOWER CONDITIONS DUE TO LOW CEILING AND OR FOG AFTER 06Z...MORE LIKELY TOWARD 12Z. IMPROVING CONDITIONS TO VFR BY 15Z. DIURNALLY DRIVEN SCATTERED CONVECTION EXPECTED SUNDAY AFTERNOON. EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE AREA. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
331 AM CDT FRI AUG 30 2013 .DISCUSSION... 942 PM CDT THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE LAKE MI SHORE NAMELY FOR OVERNIGHT. THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY 7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25 MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF THIS ALREADY AT A HANDFUL OF LOCATIONS. WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT. HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY LOOK ON TRACK. EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID- EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT. MTF //PREV DISCUSSION... 309 PM CDT THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA. THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE LATER TONIGHT. THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE 90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES. DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY. HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30 KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9 INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES. SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID TO UPPER 80S FOR SATURDAY. A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING. ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK INTO THE 70S FOR MONDAY AND TUESDAY. TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE REGION THROUGH THE MIDDLE OF NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK. * SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z. * PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT. BEACHLER //DISCUSSION...UPDATED 06Z... VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA. IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z. CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK SAT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT. * LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN. * MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SATURDAY...VFR. WX NIL. SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE BRIEF LOCAL MVFR/IFR. MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX. TRS && .MARINE... 321 AM CDT A SERIES OF FRONTAL BOUNDARIES WILL TRAVERSE LAKE MICHIGAN OVER THE NEXT FEW DAYS. PATCHY FOG WILL LINGER THROUGH EARLY THIS MORNING...AND SHOULD DISSIPATE BY MID MORNING. FOR TODAY A SOUTHWEST FLOW WILL INCREASE WITH WINDS PUSHING TO 15 TO 25 KT ACROSS THE NORTHERN HALF OF THE LAKE...WHICH WILL QUICKLY BUILD WAVES FOR THE NORTHERN PORTIONS. THEN A FRONTAL BOUNDARY WILL STEADILY PUSH SOUTH ACROSS THE LAKE...WITH WINDS VEERING TO NORTHWEST THEN NORTH. THIS WILL ALLOW A PERIOD OF BETTER FETCH FOR THE SOUTHERN HALF AND BUILDING WAVES FOR SATURDAY. THE GRADIENT WILL TIGHTEN BEHIND THE BOUNDARY AND WAVES SHOULD EASILY BUILD TO 4 TO 6 FT SATURDAY...HOWEVER THIS APPEARS TO BE A NARROW WINDOW AS HIGH PRESSURE WILL PUSH OVER THE LAKE AND LINGER UNTIL SUNDAY MORNING. WHICH WILL ALLOW WAVES TO SUBSIDE BRIEFLY SUNDAY. THEN ANOTHER COLD FRONT WILL ARRIVE SUNDAY NIGHT...WHICH WILL BRING COOLER AIR OF THE WARMER LAKE FOR MONDAY. THE RESULT WILL LIKELY BE A PERIOD OF GUSTY WINDS...WITH BUILDING WAVES FOR MONDAY. BASED ON THE CURRENT FORECAST...MONDAY COULD PRODUCE SMALL CRAFT HEADLINES FOR THE ILLINOIS/INDIANA NEARSHORE WATERS AS WINDS WILL BE NORTHERLY FOR A PROLONGED PERIOD AND GUSTY...ALONG WITH THE COOLER AIR FLOWING OVER THE WARMER LAKE. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1256 AM CDT FRI AUG 30 2013 .DISCUSSION... 942 PM CDT THE MAIN CHANGE TO THE GOING FORECAST WAS TO STRESS THE FOG A BIT MORE OVERNIGHT INTO EARLY FRIDAY MORNING...ESPECIALLY FOR THE SOUTHEAST HALF OF THE FORECAST AREA...AND ONCE AGAIN ALONG THE LAKE MI SHORE NAMELY FOR OVERNIGHT. THE BROAD AREA OF HIGH PRESSURE CENTERED TO OUR EAST CONTINUES TO EVOLVE ITS WAY SOUTHEAST TOWARD THE MID-ATLANTIC. EARLIER FOG OVER THE LAKEFRONT INCLUDING IN DOWNTOWN HAD BASICALLY DISSIPATED BY 7-7:30 PM. HOWEVER LATEST GOES FOG PRODUCT IS INDICATING A RE-BLOSSOMING START OF FOG AND/OR STRATUS EAST OF CHICAGO ABOUT 25 MILES EAST OF CHICAGO. THE BOUNDARY LAYER HAS BEEN ABLE TO DECOUPLE PER AMDAR SOUNDINGS AND SURFACE WIND OBS. LINGERING HIGH DEW POINTS NEAR 70 AND LOW-LEVEL MIXING RATIOS AROUND 15 G/KG ARE DRAPED ACROSS THE SOUTHERN AND WESTERN FORECAST AREA AND CLEAR SKIES HAVE ALLOWED TEMPERATURES TO GET WITHIN A FEW DEGREES OF THIS ALREADY AT A HANDFUL OF LOCATIONS. WHILE THE PRESSURE GRADIENT WILL GRADUALLY BUILD IN FROM THE WEST TONIGHT...MUCH OF THE EASTERN CWA SHOULD REMAIN DECOUPLED ENOUGH FOR SURFACE WINDS TO REMAIN CALM. MODIFIED 00Z ILX SOUNDING AND MODIFIED FORECAST SOUNDINGS FROM THE RAP AND NAM FOR CURRENT CONDITIONS AT IKK/VPZ INDICATE PROFILES FAVORABLE FOR FOG BY MIDNIGHT. HAVE BUMPED UP COVERAGE TO AREAS BUT THINK ANY DENSE FOG WILL REMAIN PATCHY. AS FOR OVER THE LAKE...THE EXPANDING AREA EAST OF CHICAGO WILL LIKELY ADVECT TOWARD THE IL SHORE AND POSSIBLY EXPAND BACK TOWARD IN BEFORE THE RETURN FLOW SETTLES IN OVER THE LAKE AFTER MIDNIGHT. GIVEN WHAT WAS SEEN EARLIER THURSDAY...SOME OF THIS FOG COULD BE DENSE AS IT ROLLS INTO THE IL SHORE OVERNIGHT. HAVE MADE ONLY SLIGHT TWEAKS TO MIN TEMPERATURES...WHICH PRIMARILY LOOK ON TRACK. EARLY LOOK AT 00Z NAM CONTINUES TO SHOW THE LIKELIHOOD OF SCATTERED CONVECTION ON FRI AFTERNOON THROUGH ESPECIALLY MID- EVE...WITH GREATEST CHANCES IN NORTHEAST IL/NORTHWEST IN...INCLUDING ALL OF CHICAGOLAND. HIGH CAPE/MODEST SHEAR ENVIRONMENT...ALONG WITH A SLIGHTLY MORE FAVORABLE VORT PATH THAN PREV RUN...WOULD ALL STILL SUPPORT AN ISOLATED SEVERE THREAT. MTF //PREV DISCUSSION... 309 PM CDT THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA. THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE LATER TONIGHT. THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE 90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES. DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY. HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30 KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9 INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES. SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID TO UPPER 80S FOR SATURDAY. A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING. ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK INTO THE 70S FOR MONDAY AND TUESDAY. TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE REGION THROUGH THE MIDDLE OF NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * PSBL HIGH END MVFR VIS BR/HZ THRU DAYBREAK. * SOUTHWEST WINDS SLOWLY INCREASING WITH GUSTS TO 20 KT AFT 15Z. * PSBL TSRA DEVELOPING AFT 18Z...LINGERING VCSH THRU 00Z SAT. BEACHLER //DISCUSSION...UPDATED 06Z... VERY WARM AND MOIST AIRMASS REMAINS IN PLACE...WITH VERY LITTLE WIND OVERNIGHT. THIS WILL ALLOW MANY AREAS TO BEGIN SEEING A REDUCTION TO VSBYS WITH 3-5SM AND BR/HZ CONDITIONS. AT THIS TIME IT APPEARS MOST TAF SITES WILL REMAIN VFR...WITH THE EXCEPTION OF GYY THAT HAS ALREADY SEEN VSBYS OF 4SM. JUST AFT DAYBREAK WINDS WILL INCREASE FROM THE SOUTHWEST WITH HEATING ALLOWING FOR MIXING AND GUSTS UP TO 20KT. THEN THE FOCUS TURNS TOWARDS DEVELOPMENT OF SHRA/TSRA AFT 18Z. GUIDANCE IS BEGINNING TO POINT TOWARDS A SLIGHTLY EARLIER DEVELOPMENT TO THE CONVECTION...AND HAVE PUSHED UP THE TIME OF THE PROB30 GROUP TO ACCOUNT FOR THIS. THE FRONTAL BOUNDARY THAT WILL APPROACH THE REGION DOES APPEAR TO SLOW THIS EVENING...WHICH COULD TRANSLATE INTO A LONGER PERIOD OF SHRA/TSRA. IN ADDITION WITH A LIGHT GRADIENT AHEAD OF THE FRONTAL PASSAGE...REDUCTION TO VSBY/CIGS WILL LIKELY OCCUR AFT 00Z. CURRENT THINKING IS THAT CIGS WILL NEAR LOW END MVFR CONDS...UNTIL FRONTAL PASSAGE AND SOME DRY AIR FILTERING INTO THE REGION. THEN CIGS WILL SLOWLY COME BACK UP TO 2-3KFT AGL CLOSER TO DAYBREAK SAT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPMENT. * LOW CONFIDENCE IN PRECISE TIME/COVERAGE OF SHRA/TSRA THIS AFTN. * MEDIUM CONFIDENCE IN REDUCED VSBYS/CIGS AFT 00Z SAT. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SATURDAY...VFR. WX NIL. SUNDAY...VFR. CHANCE TSRA AFTERNOON AND NIGHT WHICH COULD PRODUCE BRIEF LOCAL MVFR/IFR. MONDAY THROUGH WEDNESDAY. VFR. NO SIG WX. TRS && .MARINE... 303 PM CDT HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR. THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
703 PM CDT SAT AUG 31 2013 .SYNOPSIS... ISSUED AT 223 PM CDT SAT AUG 31 2013 WEAK LOW PRESSURE OVER WEST CENTRAL IL EARLY THIS AFTERNOON. HOT AND HUMID CONDITIONS WERE FOUND NEAR THE LOW WITH LOW TO MID 90 TEMPERATURES AND DEW POINTS IN THE LOW 70. IN THE LOW EASTERLY FLOW NORTH OF THE LOW TEMPERATURES WERE COOLER BUT DEWPOINTS WERE STILL AROUND 70. A COLD FRONT OVER THE NORTHERN PLAINS WAS THE LEADING EDGE OF COOL DRY AIR MASS. EARLY AFTERNOON TEMPERATURES OVER WESTERN NORTH DAKOTA WERE IN THE 70S WITH DEW POINTS IN THE 50S. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 223 PM CDT SAT AUG 31 2013 THIS FORECAST PERIOD WILL SEE A TRANSITION TO A MUCH MORE COMFORTABLE AIRMASS BY LATE SUNDAY AFTERNOON AS THE NORTHERN PLAINS FRONT MOVES THROUGH THE REGION. RAIN CHANCES WILL ACCOMPANY THE FRONT BUT AT THIS TIME...COVERAGE LOOKS SCATTERED AT BEST. FOR TONIGHT THE AREA OF LOW PRESSURE OVER WEST CENTRAL IL WILL BE THE FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND THIS EVENING. IT APPEARS THAT THE DEVELOPMENT WILL TAKE PLACE JUST EAST OF THE FORECAST AREA BASED CURRENT SATELLITE IMAGERY. HOWEVER WITH AN UPSTREAM VORT...OVER NORTHWEST IL... EXPECT TO MOVE THROUGH NORTHERN MO AND VERY UNSTABLE AIR STILL OVER THE SOUTHERN COUNTIES...A LOW POP WAS MAINTAINED FOR THE EARLY EVENING HOURS. WINDS WILL REMAIN LIGHT OVERNIGHT AND WITH THE HIGH DEWPOINTS STILL IN PLACE WE COULD SEE SOME PATCHY FOG LATE ESPECIALLY EAST OF THE MISSISSIPPI RIVER. THE NORTHERN PLAINS COLD FRONT IS EXPECTED TO REACH THE NORTHWEST CWA BY EARLY SUNDAY MORNING AND WILL EXIT THE EASTERN COUNTIES DURING THE EARLY AFTERNOON. THE BETTER FORCING WITH THIS SYSTEM WILL STAY OVER THE GREAT LAKES...BUT THE MODELS ARE SHOWING SOME UPPER DIFFLUENCE AHEAD OF THE S/W MOVING OVER THE AREA WITH THE COLD FRONT. THERE WILL ALSO BE OF NARROW THETAE RIDGE WITH THE BOUNDARY AND STEEPENING MID LEVEL LAPSE RATES WHICH SHOULD BE ENOUGH FOR SCATTERED STORMS AS THE FRONT MOVES THROUGH. COVERAGE OF THE STORMS SHOULD INCREASE AS THE FRONT MOVES ACROSS THE MISSISSIPPI RIVER WHERE THE AIRMASS HAS A CHANCE TO DESTABILIZE DURING THE MORNING. THE THREAT OF SEVERE STORMS WILL BE LOW ON SUNDAY DUE TO THE EARLY DAY FROPA AND WEAK DEEP LAYER SHEAR. THE HIGH LOW LEVEL MOISTURE WILL KEEP MIN TEMPS IN THE MID 60S TO AROUND 70 TONIGHT. HIGHS SUNDAY WILL STILL BE ON THE WARM SIDE TOPPING OUT AROUND 90 SOUTH TO THE MID 80S IN THE NORTH...BUT WE SHOULD SEE DEW POINTS COME DOWN A LITTLE...ESPECIALLY WEST OF THE MISSISSIPPI RIVER. DLF .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 223 PM CDT SAT AUG 31 2013 ANY LINGERING RAIN ACROSS THE SOUTHEAST THIRD OF THE CWFA SUNDAY EVENING WILL END SHORTLY AFTER SUNSET. HIGH PRESSURE WILL MOVE ACROSS THE MIDWEST SUNDAY NIGHT THROUGH TUESDAY RESULTING IN DRY BUT PLEASANT CONDITIONS. TEMPERATURES SHOULD AVERAGE CLOSE TO NORMAL. TUESDAY NIGHT ON... NORTHWEST FLOW ALOFT WILL PERSIST THROUGH NEXT WEEKEND. SEVERAL ADDITIONAL COLD FRONTS WILL MOVE THROUGH THE AREA BUT MOISTURE IS EXPECTED TO BE LIMITED WITH EACH FRONTAL PASSAGE. WHILE NOT CERTAIN...THE PROBABILITY IS MODERATE TO HIGH THAT MOST OF THE AREA WILL REMAIN DRY. THE MODEL CONSENSUS FOR TUESDAY NIGHT THROUGH SATURDAY IS FOR DRY CONDITIONS THROUGH THE PERIOD WITH TEMPERATURES AVERAGING AT OR SOMEWHAT ABOVE NORMAL. ..08.. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 639 PM CDT SAT AUG 31 2013 MAIN CHALLENGE IS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT INTO SUNDAY. MVFR CIGS STILL FOUND OVER NORTHWEST IL WITHIN MOISTURE CONVERGENCE ALONG INVERTED SURFACE TROUGH EXTENDING NWD FROM LOW PRESSURE OVER CENTRAL IL. THIS TROUGH IS EXPECTED TO SHIFT EAST THIS EVENING AND SHOULD KEEP ANY MVFR CIGS EAST OF THE TERMINALS...BUT WILL HAVE TO WATCH KMLI. OTHERWISE...LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE FAVORABLE FOR DEVELOPMENT OF FOG AND POSSIBLY SOME LOW CLOUDS OVERNIGHT. THE RAP AND HRRR MODELS DO INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS BUT ANTICIPATE INCREASE IN MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT...AND THIS COULD HAVE IMPACT ON MAGNITUDE/EXTENT OF LOW CLOUDS AND FOG. FOR NOW HAVE LOWERED VSBYS INTO IFR TO LOWER MVFR RANGE OVERNIGHT AND HINTED AT LOW CLOUDS WITH MENTION OF SCT CLOUDS BLO 1KFT AGL. ALSO ANTICIPATE SCATTERED SHOWERS AND STORMS TO ACCOMPANY THE COLD FRONT...WHICH IS SLATED TO PASS THROUGH THE TERMINALS FROM 12Z-18Z. CONDITIONS TO IMPROVE TO VFR AFTER PASSAGE OF FRONT WITH WINDS INCREASING FROM NW AT 10-15 KTS WITH GUSTS AROUND 18-22+ KTS DURING THE AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...DLF SHORT TERM...DLF LONG TERM...08 AVIATION...05
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
624 PM CDT Sat Aug 31 2013 ...Updated aviation discussion... .SYNOPSIS... ISSUED AT 300 PM CDT SAT AUG 31 2013 An upper level center of high pressure was located across New Mexico and the extreme southern High Plains today, as the upper westerly jet was positioned zonally across the northern Rockies and Northern Plains. A shortwave was in place across southern Canada, on the north side of the jet. A hot airmass still encompassed the central part of the country. 850 mb level temperatures in excess of 20 degrees C extended from the entire great plains region eastward to the the Ohio valley. at the surface...a cold front was moving southward across western South Dakota and extreme western Nebraska. Another weak stationary front was positioned from the Texas panhandle northeast into south central Kansas. Easterly surface winds became more southerly across western Kansas as surface low pressure slowly filled across the Oklahoma panhandle and temperatures warmed into the 90`s by early afternoon. && .SHORT TERM...(This evening through Sunday) ISSUED AT 300 PM CDT SAT AUG 31 2013 The immediate concern will revolve around convective chances which are not great, but non-zero as well. The best location appears along the diffuse boundary across south central Kansas. The HRRR runs have somewhat approximated isolated convection occurring by about 23 utc. A lack of upper winds and lack of shear suggest little chances at all of severe thunderstorms, and storms should have short life cycles. A better chance for showers and thunderstorms exists well into the overnight as the Northern Plains cold front enters the area. Probabilities increase from north to south around 6z and after. Very warm temperatures will continue into this evening. The NAM models surface temperatures sill around 100 degrees this evening near the Oklahoma line and low 80s persisting after midnight. Morning lows will likely be warm across all of southwest Kansas, with a few locations having lows in the upper 70s, however rain cooled air form a few vigorous storm cluster might augment the temperatures locally. Thunderstorms chances are again in the forecast during the afternoon Sunday as redevelopment is likely along the frontal boundary, wherever it decides to stall out. .LONG TERM...(Sunday night through Saturday) ISSUED AT 235 PM CDT SAT AUG 31 2013 A cold front will move across Kansas tonight as a vigorous upper level trough moves from southeast Saskatchewan to the Great Lakes, and a brief period of near climatological temperatures should extend into Monday. However, the anticyclone centered over the Rockies will build back into the Central Plains early next week, and several days of warm, quiet weather will follow. Unless rainfall tonight is more widespread than appears likely, vegetation will become increasingly drought stressed next week. Reduced evapotranspiration may allow more solar radiation to covert into sensible heat, and temperatures in the mid to upper 90s can be expected on most days. Tropical thunderstorm activity has been strongly suppressed from about 130E to the dateline, although an area of enhanced thunderstorms has been persistent in the Indian Ocean southwest of India. Most of the numerical models suggest that a coherent tropical cluster that projects onto a Madden Julian Oscillation (MJO) will amplify in Phase 1 of the Wheeler-Hendon Phase Space Diagram early in September and propagate slowly east before losing identity in the Indian Ocean. There is little correlation between the MJO and sensible weather in the central plains at this time of the year, but there may be in increased chance for tropical waves to come off Africa into the eastern Atlantic next week. Global relative angular momentum remains below climatology, but mountain torque has increased in recent days. The atmosphere will be best represented by Phase 4-5 of the Weickmann-Berry Global Wind Oscillation, which correlates with anticyclonic flow in the western and central United States. The deterministic model solutions all favor ridging from the central Rockies across the central and southern United States through the first ten days of September with only minor synoptic scale differences. The 12Z GFS has trended toward the 00Z ECMWF in handling the closed cyclone near 140W that wallows into the northern plains 9-10 September and largely was followed for grid adjustments, although confidence in behavior of this cyclone is low. Upslope flow into the foothills in eastern Colorado Sunday evening should favor thunderstorm development, but the upper level flow will be light and largely meridional over western Kansas. Most of the thunderstorms will remain west of the Colorado border, but there is a nonzero chance that a thunderstorm could reach far southwest Kansas before midnight Sunday night. Cool high pressure with light winds and low level dewpoints in the 50s will allow for strong radiational cooling, and lows will drop into the upper 50s in most areas Tuesday morning. Another minor trough dropping into the mean long wave trough near 80W will support a weak boundary that may survive into northern Kansas Wednesday night, but limited instability and weak flow aloft do not favor an organized thunderstorm event. As the upper level trough near 140W moves across the Northern Plains around 9 September, a cold front will move into Kansas and provide another opportunity for thunderstorm development and a return to more seasonal temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 619 PM CDT SAT AUG 31 2013 Southeasterly winds at less than 10 knots this evening will shift to the northeast late tonight as a cold front moves south across western Kansas. There will also be a chance for some convection along this front as it crosses western Kansas after midnight. Based on 18z Bufr soundings the cloud bases overnight and early Sunday are expected to be at or above 9000ft level so VFR conditions are expected. Evening convection that was occurring across northwest Kansas at 23z may bring a slight chance for thunderstorms near the Hays area between 03z and 06z but confidence is not high enough yet to a mention thunder prior to 06z. && .PRELIMINARY POINT TEMPS/POPS... DDC 75 88 60 89 / 20 20 10 0 GCK 72 88 58 90 / 30 20 10 0 EHA 70 88 64 91 / 20 20 10 10 LBL 72 88 60 92 / 20 20 10 0 HYS 75 88 57 90 / 40 20 0 0 P28 73 95 64 90 / 10 20 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Russell SHORT TERM...Russell LONG TERM...Ruthi AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS GOODLAND KS
500 PM MDT SAT AUG 31 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 150 PM MDT SAT AUG 31 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA. A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER EASTERN WYOMING. AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL. REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO BE FOR LABOR DAY WEEKEND. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 204 PM MDT SAT AUG 31 2013 THE UPPER RIDGE IS IN PLACE AGAIN OVER THE ROCKIES AND HIGH PLAINS FROM SUNDAY NIGHT THROUGH ALL OF NEXT WEEK. DIFFERENCES BEGIN TO SHOW UP IN MODEL PROGRESSIONS OF THE UPPER LOW CENTER RIDING UP OVER THE RIDGE IN THE PACIFIC NORTHWEST AND THE OVERALL FLATTENING OF THE RIDGE IN THE FRIDAY NIGHT THROUGH SATURDAY TIME PERIOD. SURFACE COOLER HIGH PRESSURE AREA STAYS MOSTLY OVER THE CENTRAL PLAINS AND CENTRAL HIGH PLAINS SUNDAY NIGHT AND MONDAY BEFORE PUSHING FURTHER EAST WITH A DEEPENING LEE TROUGH THAT PERSISTS IN THE VICINITY OF THE EASTERN COLORADO BORDER. WITH SOUTHERLY FLOW ACROSS THE FORECAST AREA...EXPECT MORE DRY AND WARM CONDITIONS THROUGH THE UPCOMING WORK WEEK AND NEXT WEEKEND WITH HIGHS IN THE 90S AND LOWS IN THE 60S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 500 PM MDT SAT AUG 31 2013 FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. AT 23Z FRONTAL BOUNDARY LOCATED NEAR K2V5 AND KSYF WHERE SHOWERS AND THUNDERSTORMS ONGOING. WIND GUSTS TO 35KTS REPORTED AT KSYF. FRONT NOT EXPECTED TO PASS THROUGH TERMINALS TIL THE 03Z-07Z TIMEFRAME WHERE NORTHEAST WINDS GUSTING AROUND 20KTS POSSIBLE. THIS WILL CONTINUE THROUGH MUCH OF THE DAY SUNDAY BEFORE DECREASING TO AROUND 10KTS OR LESS BY LATE IN THE AFTERNOON. CANT RULE OUT SOME PRECIPITATION AT EITHER TERMINAL TIL THE FRONT PASSES WITH DRY WEATHER EXPECTED BEHIND IT. DISTANCE SPEED TOOL SUGGESTS CURRENT AREA OF THUNDERSTORMS AT TAF ISSUANCE WILL BE IN THE VICINITY OF KGLD FOR A FEW HOURS SO HAVE ADDED A TEMPO GROUP FOR THUNDERSTORMS THROUGH 02Z. CONFIDENCE NOT QUITE AS HIGH AT KMCK TO INCLUDE A THUNDER/PRECIP GROUP BUT WILL WATCH CLOSELY AND ADD ONCE CONFIDENCE INCREASES SHOULD THAT TERMINAL BE IMPACTED. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
1047 PM EDT SAT AUG 31 2013 .UPDATE... ISSUED AT 1043 PM EDT SAT AUG 31 2013 MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS PERIOD. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 420 PM EDT SAT AUG 31 2013 THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN WITH TIME. ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS. WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY... HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT. HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 437 PM EDT SAT AUG 31 2013 THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY. ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST. ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST DRY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 841 PM EDT SAT AUG 31 2013 SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY... WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS POINT FOR ANYTHING MORE THAN VCTS IN TAFS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...GEOGERIAN LONG TERM...HAL AVIATION...HAL
AREA FORECAST DISCUSSION...CORRECTED
NWS JACKSON KY
844 PM EDT SAT AUG 31 2013 .MESOSCALE DISCUSSION... ISSUED AT 540 PM EDT SAT AUG 31 2013 IN GENERAL...THE LINE ENTERING EASTERN KENTUCKY HAS BEEN WEAKENING. JUST BEFORE THE LINE MOVED INTO THE AREA...AN OUTFLOW BOUNDARY MOVED ACROSS THE AREA FROM NE TO SW AND AND HELPED TO DESTROY SOME OF THE FAVORABLE STORM ENVIRONMENT. SOME TEMPERATURES STILL TO THE EAST OF THE LINE ARE PRETTY WARM...SO DECIDED TO ISSUE A SPECIAL WEATHER STATEMENT FOR THE LINE AS IT MAY STRENGTHEN AS THEY FIND MORE FAVORABLE AIR. THE WARMER TEMPERATURES ARE GENERALLY WEST OF A LINE FROM ROCKCASTLE TO BELL COUNTIES. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 420 PM EDT SAT AUG 31 2013 THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN WITH TIME. ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS. WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY... HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT. HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 437 PM EDT SAT AUG 31 2013 THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY. ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST. ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST DRY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 841 PM EDT SAT AUG 31 2013 SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY... WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS POINT FOR ANYTHING MORE THAN VCTS IN TAFS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE...JJ SHORT TERM...GEOGERIAN LONG TERM...HAL AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
842 PM EDT SAT AUG 31 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 420 PM EDT SAT AUG 31 2013 THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN WITH TIME. ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS. WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY... HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT. HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 437 PM EDT SAT AUG 31 2013 THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY. ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST. ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST DRY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 841 PM EDT SAT AUG 31 2013 SHOWERS AND THUNDERSTORMS LINGERED FROM THE KSME AND KLOZ AREA SOUTHWARD AT THE START OF THE PERIOD...AND WERE MOSTLY ON THE DECLINE AND MOVING OUT OF THE AREA. OUTSIDE OF ISOLATED IFR IN THAT AREA...CONDITIONS WERE MOSTLY VFR WITH HIGH CEILINGS. HOWEVER...THE SURFACE RELATIVE HUMIDITY WAS NEAR SATURATION. SKIES WERE CLOUDY... WHICH WAS INHIBITING FOG FORMATION INITIALLY. FOG TO SOME EXTENT IS EVENTUALLY EXPECTED TONIGHT. HAVE USED GENERALLY LIGHT FOG AT THIS POINT WITH MOSTLY MVFR VISIBILITY...BUT IF CLOUDS SHOULD THIN OUT...MORE SIGNIFICANT FOG CAN NOT BE RULED OUT. ANY FOG SHOULD DISSIPATE DURING SUNDAY MORNING. THERE IS NOT GOOD AGREEMENT IN COMPUTER MODELS FOR THE PRECIP FORECAST...BUT THERE IS AT LEAST SOME POTENTIAL FOR SHOWERS AND THUNDERSTORMS TO REDEVELOP OVERNIGHT. DEVELOPMENT IS ALSO EXPECT DURING THE AFTERNOON ON SUNDAY. CONFIDENCE IS TOO LOW AT THIS POINT FOR ANYTHING MORE THAN VCTS IN TAFS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GEOGERIAN LONG TERM...HAL AVIATION...HAL
AREA FORECAST DISCUSSION
NWS GRAY ME
1206 PM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 1202 PM...MINOR ESTF UPDATE TO 1ST PERIOD GRIDS TO REFLECT 16Z MESONET AND CURRENT SATELLITE TRENDS. PREV DISC... 930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES. I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY. PREV DISC... UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER. LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST. SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS. HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT MENTIONING IN THE GRIDS. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/... LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF CLOUDS AND MILD MIN TEMPS. ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND CENTRAL MAINE AND NEW HAMPSHIRE. THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY. SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING. THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND SAT. LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY. THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN CEILINGS AND VSBYS. && .MARINE... SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT. LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5 FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES
AREA FORECAST DISCUSSION
NWS GRAY ME
937 AM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 930 AM...THE 12Z KGYX RAOB SHOWS THE MOISTURE TRAPPED BELOW THE LOW LEVEL INVERSION. CONSEQUENTLY...I`VE INCREASED SKY GRIDS IN THIS ESTF UPDATE AND LOWERED MAXIMUM TEMPERATURES A FEW DEGREES. I ADJUSTED 1ST PERIOD GRIDS BASED ON SATELLITE TRENDS AND TO REFLECT THE 13Z MESONET. NIL OTHER CHANGES. HAV A GUD DAY. PREV DISC... UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER. LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST. SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS. HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT MENTIONING IN THE GRIDS. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/... LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF CLOUDS AND MILD MIN TEMPS. ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND CENTRAL MAINE AND NEW HAMPSHIRE. THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY. SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING. THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND SAT. LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY. THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN CEILINGS AND VSBYS. && .MARINE... SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT. LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5 FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES
AREA FORECAST DISCUSSION
NWS GRAY ME
659 AM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER. LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST. SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS. HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT MENTIONING IN THE GRIDS. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF CLOUDS AND MILD MIN TEMPS. ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT. && .LONG TERM /SUNDAY THROUGH THURSDAY/... A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND CENTRAL MAINE AND NEW HAMPSHIRE. THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY. SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING. THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND SAT. LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY. THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN CEILINGS AND VSBYS. && .MARINE... SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT. LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5 FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
448 AM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...MINOR CHANGES TO REFLECT CURRENT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION...STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER. LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST. SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS. HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT MENTIONING IN THE GRIDS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF CLOUDS AND MILD MIN TEMPS. ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND CENTRAL MAINE AND NEW HAMPSHIRE. THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY. SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING. THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND SAT. LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY. THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN CEILINGS AND VSBYS. && .MARINE... SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT. LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5 FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
246 AM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE AREA EARLY TODAY. A COLD FRONT WILL DROP SOUTH INTO THE AREA LATE SATURDAY BEFORE STALLING ON SUNDAY. A WARM FRONT LIFTS NORTH THROUGH NEW ENGLAND ON MONDAY WITH A COLD FRONT FOLLOWING ON TUESDAY. && .NEAR TERM /THROUGH TODAY/... STRATUS DECK FILLING BACK IN A LITTLE AS NOCTURNAL COOLING AND WEAK LIFT CONTINUES N OF THE WARM FNT. THIS SHOULD LIMIT MIN TEMPS THIS MORNING...AND IN FACT RAISE TEMPS A FEW DEGREES ACROSS ERN AREAS THAT CLEARED OUT EARLIER. LATER TODAY...S/WV TROF RACING ACROSS SRN CANADA WILL BRUSH THE AREA. HEATING OF A MOIST ENVIRONMENT WILL PROVIDE THE INSTABILITY AND A WEAK FRONTAL BOUNDARY IN THE AREA WILL PROVIDE THE FOCUS FOR AFTERNOON CONVECTION. FNT WILL HAVE A HARD TIME MAKING TOO MUCH PROGRESS SWD...SO EXPECT THAT SHRA/TSTMS WILL REMAIN MOSTLY IN THE NRN MTNS. THIS IS SUPPORTED BY HI-RES MODEL GUIDANCE...INCLUDING THE HRRR AND SPC WRF. AFTER PEAK HEATING...SHRA WILL MOVE EWD AND TEND TO DISSIPATE WITH TIME AS THEY NEAR THE MIDCOAST. SOME DRIER AIR HAS MOVED IN FROM THE NE...SO PWAT VALUES HAVE FALLEN BACK CLOSER TO NORMAL. THEY ARE FORECAST TO INCREASE ONCE AGAIN TODAY...SO SOME HEAVY RNFL IS PSBL IN ANY STRONGER STORMS. HOWEVER...THE THREAT IS NOT WIDESPREAD ENOUGH ATTM TO WARRANT MENTIONING IN THE GRIDS. && .SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/... LOSS OF DAYTIME HEATING WILL BRING ABOUT A DECREASE IN SHOWERS OVERNIGHT...BUT LINGERING FNT NEARBY WILL CONTINUE TO PROVIDE A FOCUS FOR SOME ACTIVITY. EXPECT THIS WILL REMAIN OVER THE MTNS AS WELL. AS WARM FNT CONTINUES ITS NWD PROGRESS WE/LL SEE PLENTY OF CLOUDS AND MILD MIN TEMPS. ON SAT...ANOTHER S/WV WILL HELP TO CONCENTRATE SHRA/TSTMS OVER THE AREA IN THE AFTERNOON. AGAIN THESE WILL BE TIED TO THE BOUNDARY...SO INTERIOR ZONES ARE MOST LIKELY TO SEE PCPN. FURTHER INCREASING PWAT VALUES...TO NEAR 150 PERCENT OF NORMAL...WILL SUPPORT AT LEAST AN ISOLD HEAVY RNFL THREAT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT WILL BE DRAPED ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SATURDAY. AHEAD OF THIS FRONT...A WARM AND VERY MOIST AIRMASS WILL REMAIN IN PLACE WITH HIGH PRECIPITABLE WATER VALUES APPROACHING TWO INCHES IN SOME AREAS OF SOUTHERN AND CENTRAL MAINE AND NEW HAMPSHIRE. THIS FRONT WILL STALL ALONG OR NEAR THE COASTLINE ON SUNDAY. SHOWERS AND SCATTERED THUNDERSTORMS WILL ERUPT ALONG AND AHEAD OF THIS FRONT AS IT REMAINS NEARBY. MORE SCATTERED SHOWERS ARE EXPECTED ON MONDAY AS WINDS INCREASE OFF THE GULF OF MAINE. BY TUESDAY...MORE PRECIPITATION IS EXPECTED AS THE FRONT CROSSES THE REGION. SOME LIMITED HEATING IN NEW HAMPSHIRE MAY TRIGGER A FEW THUNDERSTORMS IN THAT REGION...HOWEVER...WITH THE VERY MOIST AIRMASS...ANY PERSISTENT SHOWERS ACTIVITY MAY LEAD TO FLOODING. THE GFS IS THE MOST AGGRESSIVE MODEL TOWARDS BRINGING DRIER AIR INTO THE REGION. THIS WILL OCCUR DURING THE MIDWEEK PERIOD NEXT WEEK. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... SHORT TERM...MVFR CIGS LINGER INTO THE MORNING...THEN LIFT TO VFR DURING THE DAY. ISOLD BREAKS IN CLOUDS WILL LEAD TO SOME LOCAL IFR CONDS IN FOG EARLY. AFTERNOON SHRA/TSTMS WILL BRING SCT MVFR CONDS...ESPECIALLY ACROSS THE INTERIOR AND MTNS BOTH TODAY AND SAT. LONG TERM...AREAS OF IFR WILL BE LIKELY RIGHT THROUGH TUESDAY. THEREAFTER...A FRONTAL PASSAGE WILL ALLOW FOR SOME IMPROVEMENT IN CEILINGS AND VSBYS. && .MARINE... SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS LATE SAT. LONG TERM...SEAS MAY INCREASE INTO THE SCA CATEGORY FOR WAVES (5 FEET OR HIGHER) OVER THE OUTER WATERS THROUGH MUCH OF THE PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ LEGRO/JC
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
738 PM EDT SAT AUG 31 2013 .SYNOPSIS... WARM AND HUMID CONDITIONS WITH PERIODIC SHOWERS AND THUNDERSTORMS WILL PREVAIL THROUGH THE LABOR DAY WEEKEND. && .NEAR TERM /THROUGH SUNDAY/... AS OF MID-AFTERNOON...CONVECTION HAS GENERALLY BEEN A BUST SO FAR. EXCEPT FOR A FEW ISOLATED SHOWERS ALONG THE INTERSTATE 80 CORRIDOR...ALL LOCATIONS HAVE REMAINED DRY SINCE MID-MORNING. CONSIDERING THE MAIN UPPER LEVEL SHORTWAVE HAS ALREADY PUSHED EAST OF THE REGION...DO NOT REALLY SEE ANYTHING THAT WILL PROVIDE MUCH OF A FORCING MECHANISM UNTIL THE NEXT SHORTWAVE AFFECTING THE AREA LATE TONIGHT INTO SUNDAY. AS A RESULT...HAVE CUT WAY BACK ON POPS EARLY...RAMPING THEM UP AGAIN BY LATE TONIGHT. HOWEVER...CANNOT COMPLETELY DISCOUNT THE POSSIBILITY OF A LINE OF SHOWERS/STORMS DEVELOPING FROM NORTHEAST TO SOUTHWEST ACROSS THE REGION WHICH SEVERAL RUNS OF THE HRRR HAS BEEN INSISTENT WILL DEVELOP JUST BEFORE SUNSET. ANOTHER STICKY NIGHT CAN BE EXPECTED WITH LOWS ONLY DROPPING TO AROUND 70. A BIT OF DISAGREEMENT BETWEEN MODELS FOR TOMORROWS FORECAST. ALL OF THE SYNOPTIC MODELS BRING A DECENT SHORTWAVE FROM EASTERN OHIO IN THE MORNING TO CENTRAL PENNSYLVANIA BY THE AFTERNOON...TRIGGERING WIDESPREAD PRECIPITATION. ON THE OTHER HAND...ALL OF THE HIGH RESOLUTION MODELS SHOW MUCH LESS COVERAGE WITH PRECIP. SEEING AS THE SHORTWAVE IN QUESTION IS CURRENTLY OVER CHICAGO PRODUCING SHOWERS AND THUNDERSTORMS...WILL STICK WITH THE SYNOPTIC MODEL SOLUTIONS. A SCENARIO SIMILAR TO TODAY COULD OCCUR...WITH THE HIGHEST POPS POTENTIALLY ARRIVING IN THE MORNING ACROSS WESTERN PORTIONS OF THE AREA ALONG WITH THE SHORTWAVE AND REMNANT THUNDERSTORMS. HOWEVER...WILL PUT IN LIKELY POPS ALONG THE RIDGES DURING THE EARLY AFTERNOON WHILE THE SHORTWAVE IS PASSING THROUGH. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/... THERE SHOULD BE A BRIEF LULL IN PRECIPITATION SUNDAY EVENING WITH THE UPPER LEVEL SHORTWAVE TO THE EAST AND THE NEXT COLD FRONT OUT TO THE WEST. RAIN SHOULD BEGIN TO OVERTAKE THE EASTERN COUNTIES VERY EARLY MONDAY...AND THE FRONT WILL BE HUGGING THE RIDGES BY MONDAY EVENING. INSTABILITY AND WIND SHEAR SHOULD BE HIGH ENOUGH THAT A FEW STRONGER THUNDERSTORMS ARE POSSIBLE...BUT OVERALL SEVERE THREAT APPEARS TO BE LOW.TEMPERATURES SUNDAY NIGHT AND MONDAY SHOULD BE SIMILAR TO THOSE THROUGH THE EARLIER PORTIONS OF THE WEEKEND. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE CDFNT IS FORECAST TO EXIT THE RGN MON NGT AND END THE SHWR CHCS. BLDG HIGH PRES SHOULD THEN MAINTAIN DRY WEATHER UNTIL PASSAGE OF ANOTHER WEAK CDFNT ON THU. LTD MSTR IS PROGGED WITH THAT FNT...SO ONLY SLGT CHC POPS WERE INCLUDED ATTM. UNDR ERN CONUS TROFG ALOFT...SUB AVG TEMPS ARE EXPD INTO SATURDAY. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS SHOULD PREVAIL OUTSIDE OF ISOLATED CONVECTIVE ACTIVITY THIS EVENING. MORE ORGANIZED TS WILL LIKELY STAY MOSTLY TO THE SOUTHWEST OF THE AREA THROUGH THE EARLY EVENING...WITH ONLY ISOLATED ACTIVITY POSSIBLY CLIPPING KZZV AND KMGW. OTHERWISE...MVFR VIS/CIG RESTRICTIONS ARE POSSIBLE OVERNIGHT TOWARD MORNING BEFORE A MORE POTENT WAVE MOVES THROUGH THE AREA ON SUNDAY...BRINGING A BETTER CHANCE FOR SHOWERS/TS. .OUTLOOK.../MONDAY THROUGH THURSDAY/... A DECISIVE CDFNT PASSAGE IS STILL SLATED FOR MONDAY. RESTRICTIONS MAY THUS BE EXPECTED UNTIL HIGH PRES BUILDS FOR TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
744 PM EDT SAT AUG 31 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 359 PM EDT SAT AUG 31 2013 MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE SHRA/TS CHCS ASSOCIATED WITH SHRTWV NOW NEAR LK WINNIPEG. 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER THE NRN CONUS ON THE NRN FLANK OF SPRAWLING HI PRES CENTERED OVER THE SW CONUS. STUBBORN LO CLDS OVER THE SCENTRAL COUNTIES ARE FINALLY BURNING OFF. THERE IS A SHRTWV TRACKING THRU ONTARIO...BUT THIS DISTURBANCE IS PASSING FAR ENUF TO THE N THAT THE COMMA TAIL -SHRA ARE JUST BRUSHING NEAR ISLE ROYALE. WEAK RDG OF HI PRES OVER THE GRT LKS/SHARP SUBSIDENCE INVRN SHOWN ON LOCAL 12Z RAOBS IS BRINGING QUIET WX TO THE CWA FOR NOW. A STRONGER SHRTWV IS PRESENT ALONG THE NDAKOTA/CNDN BORDER AND MOVING QUICKLY TO THE ESE. WHERE THE SHARP DPVA/DEEP LYR QVECTOR CNVGC IN ADVANCE OF THIS FEATURE IS OVERSPREADING AXIS OF HIER MUCAPE/H85 THETA E AHEAD OF ATTENDANT COLD FNT...NMRS SHRA/TS ARE BREAKING OUT IN MN. TNGT...SHRTWV JUST SW OF LK WINNIPEG IS PROGGED TO MOVE ESE AND OVER NCENTRAL LK SUP BY 12Z SUN. AS THE DPVA/DEEP LYR QVECTOR CNVGC AND AXIS OF HIER INSTABILITY/H85 THETA E MOVE INTO WRN LK SUP THIS EVNG...EXPECT SHRA/TS NOW OVER MN TO SHIFT INTO THE WRN LAND CWA BY 06Z. GIVEN FCST MUCAPE IN EXCESS OF 1000 J/KG...SFC-6KM SHEAR IN THE 40-50KT RANGE /FORTUNATELY THE STORMS WL BECOME ELEVATED SO THIS WL NOT BE THE EFFECTIVE LYR SHEAR/...AND FAIRLY SHARP LLVL CNVGC ALONG ATTENDANT COLD FNT...SOME OF THESE STORMS MAY BE STRONG. BUT WITH LOSS OF DAYTIME HEATING AND WEAKENING H85 THETA E AXIS...EXPECT THE INTENSITY OF THESE SHRA/TS TO DIMINISH AS THEY SPREAD INTO CENTRAL UPR MI LATE. IN FACT...THE MOST RECENT SPC CONVECTIVE OUTLOOK THRU 12Z SUN CONFINES THE SLGT RISK FOR SVR TS TO MN AND FAR WRN LK SUP. WHERE TEMPS HAVE A CHC TO COOL DOWN A BIT OVER THE E HALF BEFORE THE ARRIVAL OF CLDS/A BIT SHARPER PRES GRADIENT...ADDED PATCHY FOG WITH EXPECTATION THAT MIN TEMPS FALLING INTO THE UPR 50S WL FALL THRU THE CROSSOVER DEWPT OBSVD THIS AFTN. SUN...AS SHRTWV OVER NCENTRAL LK SUP IN THE MRNG SHIFTS INTO SE ONTARIO IN THE AFTN...DNVA/DEEP LYR QVECTOR DVGC/VIGOROUS NEGATIVE H85 THETA E ADVCTN IS FCST TO ARRIVE W-E FOLLOWING ATTENDANT COLD FROPA. EXPECT BAND OF SHRA/TS AHD OF COLD FNT TO SHIFT FM THE CNTRL ZNS INTO THE ERN ZNS DURING THE MRNG. SHRA/TS INTENSITY MAY PICK UP OVER THE FAR ERN CWA IN THE EARLY AFTN WITH IMPACT OF DAYTIME HEATING LIFTING MUCAPE TO 500-1000 J/KG AND DEEP LYR SHEAR 30 TO 40 KTS BEFORE THE MORE ROBUST QVECTOR DVGC ARRIVES IN THE AFTN AND BEGINS TO SUPPRESS THE CONVECTION WITH STRENGTHENING INVRN FOLLOWING COLD FROPA AT ERY NEAR 21Z. THIS THREAT WOULD BE GREATER IF THE SOMEWHAT SLOWER GFS VERIFIES...BUT THE PRESENT STEADY SPEED OF SHRTWV INDICATES THE FASTER MODEL FCSTS ARE ON THE RIGHT TRACK. FOLLOWING THE COLD FROPA AND ARRIVAL OF LLVL COOLER AIR...NAM FCST SDNGS SHOW SHARPENING LLVL INVRN/PROSPECT FOR LO CLDS AND SOME SPRINKLES...ESPECIALLY OVER THE W AND NCENTRAL WITH UPSLOPE NW FLOW. SFC TEMPS MAY ACTUALLY FALL AT THESE PLACES DURING THE AFTN. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 359 PM EDT SAT AUG 31 2013 MORE SEASONABLE WEATHER IS EXPECTED THROUGH MUCH OF THE UPCOMING WEEK...WITH CHANCES OF PRECIPITATION MONDAY AND AGAIN WEDNESDAY. SUNDAY NIGHT AND MONDAY...A STRONG AND SHARP MID-LEVEL SHORTWAVE OVER NE LAKE SUPERIOR WILL BE STARTING TO EXIT TO THE EAST AT THE START OF THE PERIOD. THE ASSOCIATED SFC LOW WILL ALSO BE TRACKING EASTWARD AWAY FROM EASTERN LAKE SUPERIOR. THE MAIN FORECAST CONCERN IS HOW LONG MOISTURE WILL LINGER BEHIND THIS SYSTEM...AND HOW WIDESPREAD UPSLOPE DRIZZLE/SHOWERS WILL BE. WITH PLENTY OF LOW-LEVEL MOISTURE WRAPPING BEHIND THE LOW...EXPECT PLENTY OF DRIZZLE AND LIGHT SHOWERS FOR ANY AREA EXPOSED TO NNW WINDS OFF LAKE SUPERIOR. SUBSIDENCE WILL LOWER INVERSION HEIGHTS TO AROUND 1KM ACROSS THE AREA...SO THE SATURATED LAYER WILL BE QUITE SHALLOW. INSOLATION ON MONDAY SHOULD BE STRONG ENOUGH TO START ERODING THIS MOIST LAYER MONDAY MORNING. INCREASINGLY DRIER AIR ADVECTING IN FROM WESTERN ONTARIO SHOULD THEN REMOVE REMAINING CLOUDS/PRECIP FROM WEST TO EAST THROUGHOUT MONDAY AFTERNOON. HAVE INCREASED WINDS SEVERAL KNOTS ACROSS THE EAST HALF OF THE CWA GIVEN A 1020MB SFC HIGH IN THE UPPER MS VALLEY IMPINGING ON THE BACKSIDE OF THE DEPARTING 1002MB LOW. COULD SEE QUITE A BREEZY DAY FOR MUCH OF THE AREA...WITH WINDS GUSTING OVER 30MPH RIGHT NEAR THE LAKE SUPERIOR SHORE FROM BIG BAY EASTWARD. WILL CONTINUE TO RAMP UP WORDING ON A HIGH SWIM RISK GIVEN THE LABOR DAY HOLIDAY. MONDAY NIGHT...AS THE SFC HIGH SETTLES OVER NORTHERN WI MONDAY NIGHT...CLEAR SKIES AND LOW PWAT VALUES OF LESS THAN 0.5 INCHES WILL ALLOW FOR GOOD RADIATIONAL COOLING. HAVE MAINTAINED PREVIOUS FORECAST TEMPS OF LOW 40S INTERIOR WEST HALF TO LOW 50S NEAR THE GREAT LAKES. RESIDUAL STRONGER NW GRADIENT FLOW ACROSS THE EAST HALF SHOULD LIMIT COOLING TO SOME EXTENT. TUESDAY THROUGH THURSDAY...A SHORTWAVE TROUGH CURRENTLY TRACKING EASTWARD ALONG THE ALLUETIAN ISLANDS WILL STALL OVER WESTERN ALASKA AND SEND A SERIES OF WEAK WAVES ACROSS WESTERN CANADA. THE MAIN WAVE OF INTEREST WILL BECOME AMPLIFIED BY ANOTHER STRONGER WAVE OVER THE NORTH SLOPE OF ALAKSA. TIMING AND STRENGTH OF THIS FEATURE HAVE BEEN UNDERSTANDABLY DIFFICULT FOR THE MODELS TO PIN DOWN. THE GFS HAS WAVERED IN STRENGTH OVER THE LAST SEVERAL RUNS...WITH THE LATEST TWO RUNS INDICATING A SLOWER AND WETTER SOLUTION. THIS IS LIKELY A RESULT OF A LONGER PRECEEDING PERIOD OF LOW-LEVEL MOISTURE RETURN. THE GEM IS THE QUICKEST SOLUTION OF THE THREE. HAVE OPTED TO EMPLOY THE ECMWF FOR THE REST OF THE FORECAST GIVEN ITS MIDDLE GROUND AND CONTINUITY OVER THE LAST COUPLE DAYS. THE MAIN MID-LEVEL AND SFC LOWS WILL TRACK WELL NORTH OF THE CWA...POSSIBLY AS FAR NORTH AS SOUTHERN HUDSON BAY. THE 990MB SFC LOW DEPICTED BY THE ECMWF WILL BE STRONG ENOUGH TO SEND A POTENT COLD FRONT SSE-WARD ACROSS THE CWA WEDNESDAY MORNING. HOWEVER...THERE WILL BE A SUBSTANTIAL AMOUNT OF DRY AIR WITH THIS SYSTEM GIVEN ITS ORIGIN. WILL PLACE ONLY SLIGHT CHANCE POPS ACROSS THE FAR NORTH AND EAST CLOSER TO THE STRONGEST FORCING VIA MID-LEVEL Q-VECTOR CONVERGENCE AND THE LEFT EXIT OF A 120KT UPPER JET. MUCH OF UPPER MI...ESPECIALLY THE SOUTHWEST...LOOKS TO BE UNDER SUBSIDENCE FROM THE RIGHT ENTRANCE OF THE JET...AND MAY NOT EVEN SEE MUCH IN THE WAY OF CLOUD COVER. MOST OF THE COOLER AIR BEHIND THE FRONT WILL STAY EAST OF THE AREA...SO ONLY A SLIGHTLY COOLER DAY THAN WEDNESDAY IS EXPECTED FOR THURSDAY. FRIDAY AND SATURDAY...BESIDE DEVELOPING THE IDEA OF DEEPER TROUGHING ACROSS EASTERN CANADA...MODEL AGREEMENT ON SMALLER SCALE FEATURES IS POOR BY THIS POINT IN THE FORECAST. THE GFS/GEM INDICATE STRONG SFC HIGH PRESSURE BUILDING ACROSS THE AREA...WHILE THE ECMWF KEEP THE HIGH MUCH FARTHER NE NEAR JAMES BAY. A WEAK SHORTWAVE DEPICTED BY BOTH THE ECMWF AND GFS COULD BRING SHOWER CHANCES FOR FRIDAY...BUT TIMING THE GFS IS SOMEWHAT SLOWER WITH THIS IDEA. EITHER WAY...VERY LIMITED MOISTURE WILL PRECLUDE ANYTHING MORE THAN SPOTTY SHOWER COVERAGE. HAVE OPTED TO MAINTAIN CONCENSUS FORECAST AT THIS POINT GIVEN UNCERTAINTY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 743 PM EDT SAT AUG 31 2013 EXPECT DRY WX/VFR CONDITIONS AT KIWD/KCMX/KSAW THRU THE EVENING WITH RELATIVELY DRY/STABLE AIR MASS IN PLACE. ONE POSSIBLE EXCEPTION WILL BE AT KCMX LATE THIS EVENING/EARLY OVERNIGHT AS AREA OF FOG HAS DEVELOPED OVER ERN LAKE SUPERIOR. IF WINDS MAINTAIN AN EASTERLY COMPONENT LONG ENOUGH...FOG/STRATUS COULD DEVELOP AT KCMX. CONDITIONS COULD BE AS LOW AS LIFR IF FOG MAKES A STRONG WESTWARD PUSH TO THE KEWEENAW. OTHERWISE...APPROACH OF COLD FRONT/MORE UNSTABLE AIR MASS WILL BRING THREAT OF SHRA AND PERHAPS SOME TS LATER TONIGHT FROM W TO E. SUFFICIENT INSTABILITY IS PRESENT TO RETAIN MENTION OF VCTS. FOLLOWING THE COLD FROPA SUN MORNING... EXPECT LOW CLDS/IFR CONDITIONS TO IMPACT KIWD AND KCMX WITH UPSLOPE NW FLOW UNDER STRENGTHENING SHARP INVERSION. MVFR CONDITIONS SHOULD DEVELOP AT KSAW IN THE AFTN AFTER WIND VEERS TO THE NNW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 359 PM EDT SAT AUG 31 2013 EXPECT SSW WINDS UP TO 20-25 KTS TONIGHT INTO SUN MORNING OVER THE E HALF OF THE LAKE UNDER A SHARPENING PRES GRADIENT AHEAD OF AN APPROACHING COLD FRONT. FOLLOWING THE PASSAGE OF THIS FRONT...THERE WILL BE A WIND SHIFT TO THE NW...WITH WINDS INCREASING UP TO 25 KTS IN THE AFTERNOON. THE COMBINATION OF DECREASING STABILITY WITH THE ARRIVAL OF A COOL AIRMASS AND A SHARPENING PRES GRADIENT BETWEEN A DEPARTING LO PRES SYSTEM AND AN APPROACHING HI WILL RESULT IN NW-N WINDS UP TO 20-30 KTS ON SUN NIGHT INTO MON. THE ARRIVAL OF THE HI AND WEAKER PRES GRADIENT WILL ALLOW WINDS TO DIMINISH UNDER 20 KTS TUE THRU THU. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KLUBER AVIATION...ROLFSON MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
127 PM CDT FRI AUG 30 2013 .AVIATION.../18Z TAF ISSUANCE/ VFR CONDITIONS ARE EXPECTED ACROSS THE NORTHLAND TODAY INTO THIS EVENING. AS THE NIGHT WEARS ON...AREAS OF FOG ARE EXPECTED TO DEVELOP WITH LOCAL IFR/MVFR CONDITIONS. && .PREV DISCUSSION... /ISSUED 1016 AM CDT FRI AUG 30 2013/ UPDATE... REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE FORECAST. PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/ AVIATION...12Z TAFS A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN. WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL. TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM OVER OR AROUND LAKE SUPERIOR. PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/ SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH VERY SLOW REDUCTION IN SFC DEWPOINTS. TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY. POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH AND EAST INTO WISC ZONES DURING THE AFTN. TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST. TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF THE CWA. SATURDAY NIGHT THROUGH THURSDAY. MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT SATURDAY NIGHT. THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER. PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS STRONGER STORMS. THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR SOUTHEAST ZONES. HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE SEVENTIES BY THURSDAY. && .POINT TEMPS/POPS... DLH 78 57 81 61 / 10 0 20 50 INL 79 60 83 57 / 10 20 50 50 BRD 81 60 87 60 / 10 10 30 50 HYR 79 56 85 63 / 20 0 10 60 ASX 74 57 80 63 / 20 0 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...TENTINGER LONG TERM....DAP AVIATION...DAP
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1016 AM CDT FRI AUG 30 2013 .UPDATE... REMOVED MENTION OF PRECIP OVER NRN WI THIS MORNING AND UPDATED WORDING IN ZONE FORECAST. OTHERWISE...NO MAJOR CHANGES MADE TO THE FORECAST. && .PREV DISCUSSION... /ISSUED 643 AM CDT FRI AUG 30 2013/ AVIATION...12Z TAFS A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN. WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL. TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM OVER OR AROUND LAKE SUPERIOR. PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/ SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH VERY SLOW REDUCTION IN SFC DEWPOINTS. TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY. POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH AND EAST INTO WISC ZONES DURING THE AFTN. TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST. TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF THE CWA. SATURDAY NIGHT THROUGH THURSDAY. MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT SATURDAY NIGHT. THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER. PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS STRONGER STORMS. THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR SOUTHEAST ZONES. HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE SEVENTIES BY THURSDAY. && .POINT TEMPS/POPS... DLH 78 57 81 61 / 10 0 50 50 INL 79 60 83 57 / 10 20 50 50 BRD 81 60 87 60 / 10 10 50 50 HYR 79 56 85 63 / 20 0 10 60 ASX 74 57 80 63 / 20 0 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
643 AM CDT FRI AUG 30 2013 .AVIATION...12Z TAFS A MVFR STRATUS DECK COVERED MUCH OF THE NORTHLAND THIS MORNING. THE RAP 900/925MB PRES DEFICITS HAVE A DECENT HANDLE ON THE CLOUDS...ALTHOUGH IT DOES SHOW THE CEILINGS A BIT TOO FAR TO THE NORTH IN ONTARIO. WE SHOULD SEE CEILINGS SLOWLY RISE AND BECOME SCATTERED EITHER LATER THIS MORNING OR THIS AFTERNOON. THEY WILL HANG ON LONGEST OVER NORTHWEST WISCONSIN. WE SHOULD ALSO SEE SOME CU DEVELOP TODAY WITH CONVECTIVE TEMPS AROUND 70F. AFTER THIS STRATUS BREAKS UP...WE DID LEAVE CLOUDS SCATTERED...BUT SOME BROKEN DECKS WILL BE POSSIBLE AS WELL. TONIGHT...A WEDGE OF HIGH PRESSURE WILL CAUSE WINDS TO BE LIGHT. SOME FOG WILL BE POSSIBLE...AND SOME MORE STRATUS MAY FORM OVER OR AROUND LAKE SUPERIOR. && .PREV DISCUSSION... /ISSUED 356 AM CDT FRI AUG 30 2013/ SHORT TERM...SFC LOW OVER CTRL LAKE SUPERIOR WITH TRAILING COLD FRONT ACROSS NWRN WISC. POST FRONTAL CLOUDS ARE MOVING SOUTH UNDER DEEPENING NRLY FLOW. AHEAD OF FRONT RESIDUAL STORMS DIMINISHING OVER IRON COUNTY. MUCH OF CWA STILL UNDER MOIST ATMOSPHERE WITH VERY SLOW REDUCTION IN SFC DEWPOINTS. TODAY...WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION FROM PARENT ANTICYCLONE NEAR HUDSON BAY. SFC DEWPOINTS WILL GRADUALLY LOWER WITH SOME ASSISTANCE FROM BDRY LYR MIXING DURING THE DAY. POST FRONTAL CLOUD COVER WILL TAKE A WHILE TO DIMINISH BASED ON RAP13 925 CPD FCST. GENERAL CLOUD CANOPY SHOULD SLOWLY PUSH SOUTH AND EAST INTO WISC ZONES DURING THE AFTN. TONIGHT...SFC HIGH MOVES EAST OVERNIGHT AS SFC/MID LVL SYSTEM MOVES INTO NRN PLAINS. WARM ADVECTION REGIME BEGINS BY 12Z SAT OVER WRN CWA. MIN TEMPS LOWEST OVER INTERIOR WISC ZONES AND ERN ARROWHEAD WHERE MAX RAD COOLING POTENTIAL EXISTS. TEMPS MAY NEED ADJUSTMENT OVERNIGHT NEAR BORDERLAND AS INITIAL MID LVL WARM ADVECTION CLOUDS MAY BE MORE EXTENSIVE THEN CURRENTLY FCST. TOMORROW...A MID LVL TROF WITH AN ASSOCIATED SFC LOW WILL MOVE INTO ONTARIO WITH A TRAILING COLD FRONT APPROACHING WRN EDGE OF CWA BY LATE AFTN. INCREASING SRLY/SWRLY BDRY LYR FLOW WILL BECOME MORE UNSTABLE IN THE AFTN. RW/TRW WILL DEVELOP OVER KOOCH COUNTY AROUND MIDDAY AND GRADUALLY SPREAD EAST AND SOUTH TOWARDS TWIN PORTS BY LATE AFTN. MAX TEMPS WILL PUSH ABOVE CLIMO ONCE AGAIN OVER MOST OF THE CWA. SATURDAY NIGHT THROUGH THURSDAY. MAIN FOCUS IN THE EXTENDED PERIOD WILL BE A SHORTWAVE AND COLD FRONT SATURDAY NIGHT. THE MODELS ARE IN PRETTY DECENT AGREEMENT WITH A STRONG SHORTWAVE AND COLD FRONT MOVING THROUGH THE REGION SATURDAY NIGHT. THE STRONGEST PORTION OF THE WAVE WILL RIDE THE INTERNATIONAL BORDER. PWAT VALUES AROUND 1.5 INCHES WILL BE OVER THE NORTHLAND AS THESE FEATURES MOVE THROUGH. WE HAVE A GOOD CHANCE FOR SHOWERS AND STORMS OVER MUCH OF THE NORTHLAND SATURDAY NIGHT. SOME OF THESE STORMS COULD BE QUITE STRONG BUT WHETHER OR NOT THEY WILL BE SEVERE IS STILL QUESTIONABLE. ADEQUATE SHEAR IS IN PLACE WHICH SUPPORTS STRONGER STORMS. THE CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS WILL LINGER INTO SUNDAY OVER PORTIONS OF THE NORTHLAND AS THE UPPER TROUGH SWINGS THROUGH AND DUE TO COLDER AIR ALOFT. IT WILL BE MUCH COOLER...WITH HIGHS FROM 65 TO 70 NORTH...AND THE MID SEVENTIES OVER OUR FAR SOUTHEAST ZONES. HIGH PRESSURE WILL TAKE HOLD MONDAY...AND PROVIDE DRY WEATHER INTO THURSDAY. TEMPERATURES WILL SLOWLY INCREASE DURING THIS TIME...GOING FORM THE MID SIXTIES TO LOWER SEVENTIES MONDAY...RISING THROUGH THE SEVENTIES BY THURSDAY. && .POINT TEMPS/POPS... DLH 78 57 81 61 / 10 10 20 50 INL 82 60 83 57 / 10 10 50 50 BRD 84 60 87 60 / 10 0 30 50 HYR 81 56 85 63 / 20 0 10 60 ASX 76 57 80 63 / 20 0 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...CANNON LONG TERM....MELDE AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
104 AM CDT FRI AUG 30 2013 .UPDATE...QUICK UPDATE TO LOWER/DROP POPS OVER MN ZONES AND REDUCE OVER WISC ZONES. NW POST FRONTAL FLOW IS DEEPENING OVER NE MN WITH DRIER AIR FILTERING INTO THE CWA. OPPORTUNITY STILL EXISTS FOR REDEVELOPMENT OF CONVECTION OVER WISC WITH PREFRONTAL LIFT AND MID LVL LAPSE RATES EXCEEDING 7C/KM PER SPC MESOANALYSIS. ALSO HAVE 30/35KT DEEP LAYER SHEAR HOWEVER WITH BDRY LYR DECOUPLED...ELEVATED CONVECTION SHOULD BE THE RESULT WITH LOCALLY GUSTY WINDS AND HEAVY DOWNPOURS. && .PREV DISCUSSION... /ISSUED 1239 AM CDT FRI AUG 30 2013/ AVIATION...06Z TAFS. MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL 08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY 15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10 KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN 10KTS. PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/ SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS. AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN. TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH TO THE 70S SOUTH. THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/ HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS LARGELY STABILIZED THOUGH. FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL BE IN THE 80S FOR THE MOST PART. LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT ADDITIONAL CHANCES FOR SHOWERS. TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS. HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND 70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA && .POINT TEMPS/POPS... DLH 80 58 79 61 / 10 0 20 50 INL 84 62 82 57 / 10 20 50 50 BRD 86 62 86 60 / 10 0 40 50 HYR 83 58 84 63 / 20 0 10 60 ASX 78 59 78 63 / 20 0 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...CANNON
AREA FORECAST DISCUSSION
NWS DULUTH MN
1239 AM CDT FRI AUG 30 2013 .AVIATION...06Z TAFS. MOST OF THE CONVECTION HAS ALREADY MOVED THROUGH THE TERMINALS...WITH THE EXCEPTION OF KHYR...AND THE STORMS SHOULD STAY AWAY FROM THERE...PASSING TO THE SOUTH. HAVE LEFT IN A VCTS UNTIL 08Z...WHEN THEY SHOULD BE WELL OUT OF THERE. SOME IFR CIGS HAVE SWEPT INTO THE AREA BEHIND THE STORMS AND THE COLD FRONT. SO FAR THE CIGS ARE NOT CONSISTENT BUT ARE DOWN IN THE IFR TO LOW END MVFR RANGE WITH THIS STRATOCUMULUS LAYER. THIS STRATUS AND THE OTHER LOW CLOUDS AROUND SHOULD CONTINUE UNTIL MID TO LATE MORNING WHEN MIXING WILL BREAK IT UP. A GRADUAL RETURN TO VFR CIGS EXPECTED BY 15-17Z. WINDS...WHICH WILL HAVE SWITCHED TO NORTHWEST BEHIND THE FRONT WILL GRADUALLY TURN NORTH AND THEN NORTHEAST AT OR BELOW 10 KTS BY MID DAY FRIDAY...AND THEN DROP OFF TO NORTHEAST LESS THAN 10KTS. && PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 29 2013/ SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS. AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN. TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH TO THE 70S SOUTH. THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/ HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS LARGELY STABILIZED THOUGH. FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL BE IN THE 80S FOR THE MOST PART. LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT ADDITIONAL CHANCES FOR SHOWERS. TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS. HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND 70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA && .POINT TEMPS/POPS... DLH 80 58 79 61 / 30 0 20 50 INL 84 62 82 57 / 10 20 50 50 BRD 86 62 86 60 / 10 0 40 50 HYR 83 58 84 63 / 30 0 10 60 ASX 78 59 78 63 / 30 0 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ AVIATION...LE/MELDE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1148 PM CDT Thu Aug 29 2013 .UPDATE: Issued at 930 PM CDT Thu Aug 29 2013 Mid-evening update mainly to remove isolated thunderstorms from the forecast over south central Illinois. The rest of the forecast looks to be in good shape for the rest of the night. Noticed that the RUC is spitting out some precip over parts of west central and central Missouri late tonight in proximity to the upper low now moving through eastern Kansas in an area of weak 850mb warm advection. The new 00Z NAM is dry until after sunrise and then the precip is further to the southwest. Will keep the forecast dry for the rest of the night and let the midnight shift add in some isolated showers or storms if something does indeed pop up. Carney && .SHORT TERM: (Through Late Tonight) Issued at 254 PM CDT Thu Aug 29 2013 The front at midday was located from extreme southeast IA to east of a KUIN-KSLO line into western KY, while a weak north-south surface ridge axis was located through central MO. The front appears to be trying to jump west into a new wind shift line closer to the MS River. However, the more agitated cu field and axis of greatest instability and weak CIN resides along the more eastern location, and present indications are this would be the most favored location for isolated shower/thunderstorm development through early evening. After sunset the threat of any precipitation appears quite low as the air mass will become more stable, diurnal cu will dissipate, and any forcing along the boundary will be quite weak. Otherwise, tonight looks rather uneventful with the upper low dropping southeastward through KS spreading some high clouds into the western half of the CWA, and min temperatures a tad bit warmer. Glass .LONG TERM: (Friday through Next Thursday) Issued at 254 PM CDT Thu Aug 29 2013 Upper level shortwave over southwestern Missouri will continue to slowly slide to the south on Friday. Could see a slight chance of showers and thunderstorms mainly over the Ozarks on Friday. In the meantime the next frontal boundary, currently over South Dakota/western Nebraska, will move into northern Missouri by Friday afternoon. Activity associated with this boundary, very scattered in nature, will move into northeast MO, west central IL Friday evening. There could be some lingering isolated activity associated with upper level system over southern and eastern portions of forecast area as well. As for high temperatures on Friday, it will be a bit warmer than today, but with a few more clouds and dewpts still mixing out, heat indicies will remain in the 100 to 104 range, though a few spots could reach 105. By Saturday, cold front to weaken even more as it slides through region. There is a chance of a few storms, mainly over far eastern portions of forecast area. Otherwise, another hot day in store despite a few more clouds and front moving through. Highs will be in the low to mid 90s with heat indicies between 100 and 104. A more vigorous cold front to approach area late Saturday night with best chances of rain Sunday and Sunday night. Again not a lot of moisture associated with it, so activity to be rather scattered with it. With this front, cooler and less humid air to make its way into region, so will keep heat advisory headline going through Saturday for metro area, no need to extend it beyond this time period. Beyond that, precipitation to taper off very early Monday morning with surface ridge building in and more seasonable temperatures expected through the work week. Byrd && .AVIATION: (For the 06z TAFs through 06z Friday Night) Issued at 1135 PM CDT Thu Aug 29 2013 Stalled trof/boundary over extreme eastern Missouri in the process of dissipating attm as pressure falls from retreating ridge are allowing a gradual return of weak southerly flow across the mid- Mississippi Valley. Due to fairly low T/Td spreads and vsby forecasts on 00z based MET/MAV have added some MVFR vsbys in fog at climatologically favored locations (SUS, CPS), as well as at UIN where the visbility has already started a gradual decline. Some of the 00z guidance is also hinting at some convection developing over mid-Missouri by daybreak, but signal is still fairly weak so have maintained a dry forecast for now...with a few early morning mid clouds followed by another day of diurnal cu development. Will also need to keep an eye on convective potential with approaching cold front Friday night, but attm it appears that primary threat with this feature into Friday evening will remain north of our CWA. Specifics for KSTL: While latest guidance and obs suggest that there will be some vsby restriction at low lying locations (SUS and CPS) in the STL metro believe this will not impact the STL TAF vicinity. So...forecast for the overnight hours maintains VFR conditions with a generally clear sky...with diurnal heating leading to another afternoon of cu with bases aoa 5kft. Truett && .LSX WATCHES/WARNINGS/ADVISORIES: MO...HEAT ADVISORY until 7 PM CDT Saturday FOR St. Charles MO-St. Louis City MO-St. Louis MO. IL...HEAT ADVISORY until 7 PM CDT Saturday FOR Madison IL-St. Clair IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
218 PM MDT FRI AUG 30 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY... NOT AS WARM THIS WEEKEND WITH WIND SATURDAY. LOW PRESSURE OVER SASK THIS AFTERNOON WILL BEGIN TO SEND A COLD FRONT OUR WAY TONIGHT WHEN AN UPPER LEVEL SYSTEM TO IT/S WEST CATCHES UP. THIS FRONT IS EXPECTED TO PUSH SOUTHEAST THROUGH NE MT SATURDAY MORNING. 850 MB TEMPS FALL A FEW DEGREES SATURDAY AND ATMOSPHERE MIXES TO ABOUT 750 MB. WINDS AT THAT LEVEL LOOK TO BE ABOUT 25-30 KTS SO 20 TO 30 MPH SURFACE WINDS CAN BE EXPECTED. THESE WINDS ARE LOOKING TO OCCUR FROM ABOUT NOON TO 8 PM OVER FORT PECK LAKE...SO WILL GO AHEAD AND ISSUE A LAKE WIND ADVISORY FOR THIS PERIOD. OTHERWISE...SOME MID-LEVEL INSTABILITY MAY BUBBLE UP A SHOWER/STORM LATE THIS AFTERNOON. THE HRRR AS USUAL IS EXCITED ABOUT IT WHILE THE OTHER MODELS (INCLUDING THE RUC) ARE MUCH DRIER. THE NAM IS SHOWING THIS TO OCCUR LATER TONIGHT IN THE SOUTHERN ZONES...FINALLY EXITING INTO THE DAKOTAS SATURDAY AFTERNOON. SURFACE HIGH PRESSURE THEN BUILDS INTO THE AREA SATURDAY NIGHT PROVIDING LIGHT WINDS...NEAR NORMAL TEMPS AND CLEAR SKIES THROUGH SUNDAY. ENJOY! TFJ .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... THE LONG TERM FORECAST PERIOD IS CHARACTERIZED BY A SIGNIFICANT AND AMPLIFIED WEATHER PATTERN...BASICALLY SPLIT BETWEEN TWO DIFFERENT WEATHER REGIMES. SUNDAY NIGHT THROUGH WEDNESDAY AFTERNOON...THE CENTRAL CONUS RIDGE AND THE PACIFIC NORTHWEST LOW BUTT UP AGAINST EACH OTHER IN A STRUGGLE FOR DOMINANCE THAT DOES NOT COME TO A RESOLUTION UNTIL LATE WEDNESDAY NIGHT. IT SHOULD BE NOTED THAT THE LARGE SCALE MODELS HINT AT A SHORT WAVE DISTURBANCE RIDING UP AND AROUND THE RIDGE OF HIGH PRESSURE MAKING ITS WAY THROUGH EASTERN MONTANA TUESDAY MORNING THROUGH TUESDAY AFTERNOON...LIKELY BRINGING ONLY ISOLATED PRECIPITATION TO THE AREA. THE BIGGER STORY BEGINS OVERNIGHT WEDNESDAY NIGHT AS THE LARGE UPPER LEVEL LOW PRESSURE SYSTEM FINALLY MOVES INLAND OVER THE PACIFIC NORTHWEST...TURNING OUR FLOW ALOFT FROM THE SOUTHWEST AND SOUTH. THIS WILL LIKELY PUMP SIGNIFICANT AMOUNTS OF PACIFIC MOISTURE OVER THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS. WITH EACH MODEL RUN...THE CONSENSUS IMPROVES REGARDING THE TIMING AND PLACEMENT OF THIS UPPER LOW INTO THE INTER-MOUNTAIN NORTHWEST. AT THIS TIME...SIGNIFICANT DIFFERENCES WITH THIS WEATHER REGIME CHANGE BEGIN TO EMERGE EARLY THURSDAY MORNING AS THE AGGRESSIVE GEM PUSHES FASTER AHEAD...FOLLOWED BY THE SLOWER GFS AND THEN THE SLOWEST EC. FOR NOW...CAN ONLY BROAD-BRUSH THE END OF THE EXTENDED FORECAST PERIOD WITH A WETTER WEATHER PATTERN. WOULD EXPECT THINGS TO COME MORE INTO FOCUS OVER THE NEXT FEW DAYS. BMICKELSON PREVIOUS LONG TERM DISCUSSION... UPPER RIDGE WILL BE OVER THE AREA MOST OF THE WEEK WITH WARM AND MAINLY DRY WEATHER. THERE WILL BE SUMMER LIKE TEMPERATURES NEAR 90 MONDAY AND TUESDAY. ECMWF STILL WANTS TO BRING A BACK DOOR COLD FRONT THROUGH THE AREA TUESDAY NIGHT WHILE THE GFS KEEP THE FRONT TO THE EAST. THIS HAS THE ECMWF FORECASTING COOLER TEMPERATURES ON WEDNESDAY. WILL GO SOMEWHAT COOLER ON WEDNESDAY FOR NOW. MODELS EVENTUALLY WANT TO BRING AN UPPER LOW/TROUGH INLAND TOWARDS THE END OF NEXT WEEK. THE FLOW ALOFT IS EXPECTED TO TURN TO THE SOUTHWEST AROUND THURSDAY ALLOWING FOR SOME INCREASE IN MOISTURE. WILL MENTION A SLIGHT CHANCE OF THUNDERSTORMS STARTING THURSDAY AFTERNOON IN THE WEST AND SPREADING TO THE ENTIRE AREA BY FRIDAY. FORRESTER && .AVIATION... MAINLY VFR CONDITIONS WILL PREVAIL FOR ALL TAF SITES. LATELY RIVER VALLEY FOG HAS BEEN ABLE TO MAKE ITS WAY INTO KOLF BUT SEEMS LESS LIKELY NOW OVER THE NEXT FEW DAYS AS NORTHWESTERLY SURFACE WINDS AND DRIER ARE ARE EXPECTED TO MOVE THROUGH THE AREA WITH A COLD FRONT. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE TODAY AND TONIGHT. WIND SPEEDS WILL BE 10 KNOTS OR LESS TODAY AND TONIGHT. EXPECT WINDY NORTHWEST WINDS LATER ON SATURDAY...AROUND 20G30KT. BMICKELSON && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM NOON TO 8 PM MDT SATURDAY FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
430 PM CDT FRI AUG 30 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 430 PM CDT FRI AUG 30 2013 THE MAIN HIGHLIGHTS OF THE NEXT 36 HOURS INCLUDE ONE MORE DAY OF NOTABLE LATE SUMMER HEAT ON SATURDAY BEFORE READINGS RETURN TO MORE SEASONAL LEVELS FOR SUNDAY...ALONG WITH STILL HIGHLY- UNCERTAIN THUNDERSTORM CHANCES BOTH TONIGHT AND ESPECIALLY FOR SATURDAY NIGHT. WANT TO STATE OFF THE TOP THAT MODELS VARY CONSIDERABLY ON THE PROBABILITY/COVERAGE OF CONVECTION SATURDAY NIGHT...AND THUS POPS CONTINUE TO BE CAPPED AT NO MORE THAN 30-40 PERCENT ACROSS THE CWA. STARTING OFF LATE THIS AFTERNOON...20Z OBJECTIVE SURFACE ANALYSIS DEPICTS A SURFACE TROUGH/VERY WEAK COLD FRONT STRETCHED FROM NORTHWEST KS INTO CENTRAL IA...WITH THE VAST MAJORITY OF THE CWA POSITIONED JUST NORTH OF THIS BOUNDARY. AS A RESULT...BREEZES THIS AFTERNOON HAVE PREVAILED FROM THE EAST-NORTHEAST AT SPEEDS GENERALLY AROUND 10 MPH WITH OCCASIONAL HIGHER GUSTS. HOWEVER...THIS HAS BY NO MEANS BEEN A COOLING NORTHERLY WIND COMPONENT...AS HIGH TEMPS ARE ON TARGET TO RANGE FROM THE LOW-MID 90S CENTRAL/NORTHEAST...TO THE UPPER 90S TO AROUND 104 IN SOUTHERN ZONES. FURTHERMORE...THE FAIRLY LIGHT EAST-NORTHEAST BREEZE HAS ALLOWED DEWPOINTS ACROSS MAINLY THE NORTHEAST 2/3 OF THE CWA TO REMAIN WELL UP AROUND 70...RESULTING IN POSSIBLY THE MOST WIDESPREAD COVERAGE OF 100-105 HEAT INDEX VALUES WE HAVE SEEN ALL WEEK...WITH VALUES IN ALL AREAS LIKELY SAFELY UNDER 100 BY 01Z/8PM. ALOFT...WATER VAPOR IMAGERY SHOWS THE CWA LOCATED NORTHEAST OF THE CENTER OF THE EXPANSIVE MID/UPPER RIDGE AXIS CENTERED OVER CO...RESULTING IN NORTH/NORTHWEST FLOW OVERHEAD. WHILE WATER VAPOR AND MODELED VORTICITY FIELDS HINT AT SOME SUBTLE PERTURBATIONS HELPING KICK OFF HIGH PLAINS CONVECTION OFF TO OUR WEST AT THIS HOUR...BY FAR THE MOST NOTABLE SHORTWAVE OF INTEREST FOR THE NEXT FEW DAYS WEATHER IS SHIFTING EAST INTO SOUTHERN ALBERTA AT THIS TIME. VISIBLE SATELLITE LATE THIS AFTERNOON SHOWS ESSENTIALLY CLOUD-FREE SKIES OVER THE VAST MAJORITY OF THE CWA...WITH ONLY SOME VERY HIGH BASED CUMULUS DEVELOPING FROM INTENSE HEATING IN OUR FAR SOUTHERN KS ZONES. TURNING TO THE EVENING/OVERNIGHT HOURS...FROM A BASIC SENSE HAVE MADE VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. HAVE KEPT LOW END 20-30 PERCENT STORM CHANCES CONFINED TO ROUGHLY THE NORTHWEST 1/3 OF THE CWA...WITH TWO POSSIBLE SCENARIOS ENVISIONED AND PORTRAYED BY VARIOUS MODELS. STARTING WITH THE BIG PICTURE ALOFT...VERY SUBTLE HEIGHT FALLS WILL OCCUR AS THE LARGE RIDGE AXIS FLATTENS JUST A BIT IN RESPONSE TO THE AFOREMENTIONED CANADIAN SHORTWAVE TROUGH SHIFTING EAST TO JUST NORTH OF THE MT/ND BORDER BY SUNRISE. CLOSER TO HOME...VERY SUBTLE MID LEVEL PERTURBATIONS...POSSIBLY CONVECTIVELY DRIVEN...WILL CONTINUE SHIFTING EAST TOWARD/INTO THE CWA FROM THE CENTRAL HIGH PLAINS. SOME MODELS...NAMELY THE HRRR AND 12Z 4KM WRF-NMM...ARE SURPRISINGLY AGGRESSIVE IN DRIVING HIGH PLAINS CONVECTION EASTWARD INTO AT LEAST WESTERN PORTIONS OF THE CWA THIS EVENING...BUT WITH A GENERAL TREND OF KILLING OFF CONVECTION AS IT GETS TOWARD CENTRAL PORTIONS OF THE CWA LIKELY IN RESPONSE TO INCREASING CINH. ALTHOUGH A FEW STORMS ARE ALREADY EVIDENT 100+ MILES WEST OF THE CWA...UNCERTAINTY IS QUITE HIGH WHETHER OR NOT ANY OF THIS WILL ACTUALLY SLIP INTO OUR AREA...AND THUS OPTED TO KEEP LOW POPS CONFINED TO WESTERN COUNTIES AND NOT ADVERTISE ANYTHING ACROSS THE MAJORITY OF THE AREA...BUT THIS WILL NEED WATCHED. LATER IN THE NIGHT...MODELS SUCH AS THE RAP KICK OFF A POTENTIALLY SEPARATE AREA OF HIGH-BASED CONVECTION IN OUR NORTHWEST COUNTIES POSSIBLY IN RESPONSE TO MID-LEVEL THETA-E ADVECTION...BUT AGAIN THIS IS MAINLY IN THE AREA ALREADY COVERED WITH LOW POPS. IF STORMS DEVELOP/MOVE IN THIS EVENING/OVERNIGHT...WOULD BE SURPRISED TO SEE MORE THAN SMALL SUB-SEVERE HAIL. OTHERWISE...BREEZES TONIGHT WILL AVERAGE VERY LIGHT/EASTERLY...AND MADE LITTLE IF ANY CHANGE TO OVERNIGHT LOWS WITH MAINLY 66-71. TURNING TO THE SATURDAY DAYTIME/SATURDAY NIGHT HOURS...AGAIN ON THE SURFACE THERE HAS BEEN LITTLE NOTICEABLE CHANGE FROM THE PREVIOUS FORECAST...WITH THE OVERALL BEST CHANCES FOR RAIN/STORMS DURING THE CURRENT VALID 7-DAY FORECAST ARRIVING SATURDAY NIGHT...ALTHOUGH BY FAR FROM A SURE THING. ON THE LARGE SCALE...THE FAIRLY VIGOROUS SHORTWAVE TROUGH ALONG CENTRAL PORTIONS OF THE U.S./CANADIAN BORDER ON SATURDAY MORNING WILL SLIDE EAST-SOUTHEAST TO OVER/NEAR LAKE SUPERIOR BY SUNRISE SUNDAY MORNING...WITH THIS WAVE LOWERING HEIGHTS FURTHER OVER THE LOCAL AREA AND SHUNTING THE RIDGE SLIGHTLY OFF TO THE SOUTHWEST A BIT. AT THE SURFACE...BY FAR THE BIG STORY IS A LEGITIMATE COLD FRONT THAT WILL BE FORCED SOUTHWARD INTO THE CENTRAL PLAINS FROM THIS WAVE. DURING THE DAYTIME HOURS...THERE IS GOOD AGREEMENT THIS FRONT WILL BE POSITIONED AT LEAST SLIGHTLY NORTHWEST OF THE CWA THROUGH LATE AFTERNOON...BEFORE PASSING THROUGH SOMEWHAT AGGRESSIVELY DURING THE NIGHT AS FAR AS SUMMER COLD FRONTS GO...WITH ALL AREAS EXPECTED TO HAVE A STEADY 10+ MPH NORTH BREEZE AND INCREASINGLY COOLER/DRIER AIR BY SUNRISE SUNDAY MORNING. DUE TO THE CWA REMAINING AHEAD OF THE FRONT DURING THE DAY...ONE MORE HOT/STEAMY AFTERNOON IS IN STORE...WITH MAYBE ONLY A BIT MORE IN THE WAY OF MID/HIGH CLOUDS POSSIBLE HOLDING SOME AREAS A TAD COOLER THAN TODAY...BUT STILL AIMING FOR LOW-MID 90S CENTRAL/NORTHEAST TO NEAR 100 SOUTH/SOUTHWEST...WITH HEAT INDEX VALUES AGAIN AROUND 100 OR SLIGHTLY HIGHER. AS FOR DAYTIME CONVECTIVE CHANCES...THERE IS ADMITTEDLY SOME UNCERTAINTY HERE...AS SOME MODELS SUCH AS THE NAM SUGGEST THAT ESPECIALLY THE WESTERN 1/2 OF THE CWA COULD SEE SOME LIKELY HIGH-BASED DAYTIME CONVECTION...EVEN IN THE MORNING...POSSIBLY A CONTINUATION OF SOME ACTIVITY THAT MIGHT DEVELOP LATE TONIGHT. HOWEVER...FORECAST SOUNDINGS AND A CONCEPTUAL MODEL OF THIS PATTERN SUGGEST THAT VERY WARM MID LEVEL TEMPERATURES ARE MORE LIKELY TO INHIBIT DAYTIME CONVECTION THAN SUPPORT IT. SO ALTHOUGH ITS NO GUARANTEE...LEFT POPS BELOW THE MENTIONABLE 15+ PERCENT THRESHOLD IN THE MORNING AND THROUGH MID-AFTERNOON...BUT LEFT SLIGHT CHANCES MAINLY IN THE WESTERN 1/2 DURING THE LATE AFTERNOON JUST IN CASE SOMETHING CAN GET GOING IN THE HOT/DEEPLY MIXED AIRMASS AHEAD OF THE FRONT. CERTAINLY THE BETTER LARGE-SCALE SUPPORT TO BREAK THROUGH THE CAP AND SUPPORT CONVECTION COMES SATURDAY NIGHT...AS THE SURFACE COLD FRONT PASSES THROUGH AND IS ACCOMPANIED/FOLLOWED BY A DECENT AXIS OF MID LEVEL FRONTOGENESIS. EVEN SO...WITH THE MAIN TRACK OF THE PARENT SHORTWAVE TROUGH TRACKING HUNDREDS OF MILES NORTHEAST OF THE CWA...THERE ARE PLENTY OF QUESTIONS ABOUT HOW WIDESPREAD THIS CONVECTION WILL BE. FOR EXAMPLE...WILL IT SWEEP THROUGH FROM NORTHWEST-SOUTHEAST IN A FAIRLY SOLID LINE AS THE 12Z NAM WOULD SUGGEST...OR WILL IT BE VERY HIT-AND-MISS AND IN FACT MISS THE MAJORITY OF THE AREA ALTOGETHER AS THE 12Z 4KM-WRF NMM REFLECTIVITY PROG WOULD SUGGEST. WITH THIS STILL BEING 24+ HOURS OUT...OPTED TO PLAY POPS FAIRLY STATUS QUO FOR NOW...CAPPING THEM IN THE 30-40 PERCENT RANGE GIVEN THIS DEGREE OF UNCERTAINTY. IF/WHEN STORM FORM...CERTAINLY CANNOT RULE OUT AT LEAST A MARGINAL SEVERE THREAT...WITH THE NAM ADVERTISING 2000+ J/KG OF CAPE IN THE 850-700MB LAYER IN THE EVENING...BUT IN THE PRESENCE OF ONLY 25-30KT OF DEEP LAYER SHEAR. ITS CERTAINLY POSSIBLE THAT IF ENOUGH STORMS FORM AND DEVELOP INTO A FORWARD-PROPAGATING LINE THAT AN ENHANCED WIND THREAT COULD MATERIALIZE...BUT THIS IS ALL PREDICATED ON HOW WIDESPREAD DEVELOPMENT ULTIMATELY IS. NO MATTER WHAT...ROUGHLY THE NORTHWEST 1/3 TO 1/2 OF THE CWA SHOULD BE CLEAR OF STORM CHANCES BY AROUND MIDNIGHT OR SHORTLY THEREAFTER...WITH THE LATE NIGHT FOCUS IN THE SOUTHEASTERN 1/2. LOW TEMPS BY SUNRISE SUNDAY ARE FORECAST TO RANGE LOW 60S NORTH TO NEAR 70 FAR SOUTHEAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 430 PM CDT FRI AUG 30 2013 MAIN CONCERNS ARE CHANCES FOR THUNDERSTORMS SUNDAY MORNING AND WEDNESDAY EVENING. ON THE LARGE SCALE...THE WEATHER PATTERN WILL BE SWINGING TO A NORTHWEST FLOW REGIME AS THE UPPER LEVEL RIDGE THAT HAS BEEN PERSISTENT OVER THE AREA THE LAST WEEK OR SO RETROGRADES WEST. THIS CHANGE IN FLOW WILL RESULT IN TEMPERATURES ABOUT 10 DEGREES COOLER THAN THIS WEEK AND SOME LOW CHANCES FOR RAIN AS FRONTAL BOUNDARIES INTERMITTENTLY MOVE THROUGH THE AREA. MODELS SUGGESTING LINGERING STORMS POSSIBLE EARLY SUNDAY MORNING BEFORE CONVECTION EXITS SOUTHEAST OF THE AREA. WE LEFT SMALL CHANCES OF RAIN IN OVER THE EXTREME SOUTHEAST CORNER OF THE CWA SUNDAY MORNING AS THE FRONT SAGS OUT OF THE AREA. ALL MODELS SUGGEST A CHANCE FOR STORMS WEDNESDAY EVENING AS ANOTHER COOL FRONT MOVES THROUGH THE AREA. THERE IS A MARGINAL THREAT THAT A FEW OF THE STORMS MAY PRODUCE SMALL HAIL AND GUSTY WINDS WEDNESDAY NIGHT DUE TO LOW TO MARGINAL INSTABILITY AND WEAK SHEAR. OTHER THAN THOSE TWO PERIODS...HIGH PRESSURE SHOULD BE THE DOMINANT WEATHER FEATURE. SO DRY AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS WILL BE THE RULE MOST DAYS. && .AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1218 PM CDT FRI AUG 30 2013 EXPECT NORTHEASTERLY FLOW TODAY AS A WEAK SURFACE TROUGH HAS TRANSITED THE AREA. BOTH CEILINGS AND VISIBILITIES ARE EXPECTED TO REMAIN VFR THROUGH THE PERIOD. A FEW MODELS ARE HINTING AT A CHANCE FOR PRECIPITATION OVERNIGHT. CONFIDENCE IS CURRENTLY LOW AS TO WHETHER IT WILL REACH THE GRI AIRPORT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...EDDY AVIATION...BEDA
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
308 PM CDT FRI AUG 30 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 307 PM CDT FRI AUG 30 2013 TONIGHT THROUGH SATURDAY...A WEAK UPPER LEVEL DISTURBANCE... CURRENTLY ACROSS THE WYOMING...WILL MOVE ACROSS THE FCST AREA TONIGHT SPAWNING A FAIRLY ORGANIZED AREA OF TSTMS. ALL MODELS SHOW K INDICES INCREASING TO AROUND 40C OR GREATER. THE RAP AND OTHER MODELS SHOW PRECIPITABLE WATER INCREASING TO 1.50 INCHES OR GREATER. FCST STORM MOTION OF 10KT OR LESS WOULD SUPPORT LOCALLY HEAVY RAINFALL AND WEAK WINDS ALOFT 30KT OR LESS AT AND BELOW 300MB SUGGEST OUTFLOW DOMINANT COLD POOL DRIVEN BOW SEGMENTS CAPABLE OF GUSTY WINDS. LOW LEVEL EASTERLIES AND WEAK WESTERLIES ALOFT PRODUCE BULK SHEAR OF 35 TO 40 KT SO SOME STORMS THIS EVENING COULD BECOME SEVERE WITH WIND DAMAGE AND LARGE HAIL. SPC PROVIDED THIS DISCUSSION AT 227 PM CDT...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE NEXT HOUR OR TWO. THE STORM COMPLEX COULD MOVE MOSTLY EAST ACCORDING TO THE RAP MODEL OR TAKE A SOUTHEAST TURN AS INDICATED BY THE HRRR. EITHER WAY THE CONVECTION WILL AFFECT MOST OF THE FCST AREA AND EXIT SOUTH OR EAST BY AROUND 12Z. THIS TSTM COMPLEX SHOULD SET UP A FRONTAL BOUNDARY FOR ADDITIONAL STORM DEVELOPMENT SATURDAY AFTN AND BEYOND WITH THE BEST SHEAR AND INSTABILITY ACROSS NCNTL NEB NEAR KANW AND KONL. THE MODELS HAVE A TOTALLY DIFFERENT IDEA IN MIND WITH THE FRONT AND LIFT IT RAPIDLY NORTH BY 15Z SATURDAY MORNING AND THEN DROP ANOTHER COLD FRONT THROUGH DURING THE AFTN. SO THERE IS A DISCONNECT IN CONVENTIONAL STORM THEORY VS THE MODELS. IF THE FRONT IS DOES NOT RETREAT NORTH AS QUICKLY THAN STORM DEVELOPMENT COULD BE MUCH FARTHER SOUTH...PERHAPS OVER KS. THE FCST USES A BLEND OF NAM...GEMREG...GFS AND ECM FOR A 30 POP FROM 20Z ONWARD...MAINLY SOUTH AND EAST OF KVTN/KIML. TEMPERATURES ARE A BLEND OF TRIED AND TRUE MODEL DATA PLUS BIAS CORRECTION FOR HIGHS IN THE LOWER 90S NORTH TO UPPER 90S SOUTH. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 307 PM CDT FRI AUG 30 2013 SATURDAY NIGHT THROUGH LABOR DAY... COLD FRONT SHOULD STRETCH FROM NEAR ANW THROUGH LBF AND IML EARLY SATURDAY EVENING. DO EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THE FRONT. COVERAGE MAY END UP LESS ACROSS SWRN NEBR WHICH WILL BE FURTHER REMOVED FROM COOLER TEMPERATURES ALOFT ASSOCIATED WITH MAIN UPPER TROUGH ACROSS MINNESOTA. ONLY A SLIGHT CHANCE FOR THUNDERSTORMS FAR SOUTHEAST AFTER MIDNIGHT. DRY AND LESS HOT SUNDAY AND LABOR DAY. HIGHS SUNDAY FORECAST VERY NEAR PREVIOUS FROM NEAR 83 NCTRL AND 85 TO 88 SOUTHWEST. NORTHERLY WINDS SUNDAY LOOK FAIRLY LIGHT FROM 5 TO 15 MPH WEST AND 10 TO 20 MPH EAST. ON LABOR DAY...NORTHWEST FLOW ALOFT WILL CONTINUE WITH A RETURN SOUTHEAST FLOW AT THE SURFACE AND HIGHS FROM NEAR 83 NORTHEAST TO NEAR 90 WEST TIER. SOUTHERLY WINDS MONDAY FROM 10 TO 20 MPH WEST TO 5 TO 15 MPH EAST. ON TUESDAY THROUGH FRIDAY... A HEAT UP AGAIN LIKELY AS UPPER RIDGE PERSISTS OVER COLORADO AND TROUGHING INCREASES ACROSS THE PAC NW AND NORTHEASTERN U.S. A WEAK COLD FRONT AND DISTURBANCE IN NORTHWEST FLOW ALOFT INDICATED BY THE GFS AND ECMWF. THIS FRONT ASSOCIATED WITH A DEEP UPPER LOW MOVING ACROSS HUDSON BAY. AS A RESULT OF ECMWF CONSISTENCY AND FAIR AGREEMENT BY THE GFS...WILL INTRODUCE A SLIGHT CHANCE FOR THUNDERSTORMS WEDNESDAY NIGHT. AN OTHERWISE DRY EXTENDED. HIGHS FORECAST IN THE UPPER 80S TO LOW 90S MOST AREAS WITH MID 90S PARTS OF SWRN NEBR. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1221 PM CDT FRI AUG 30 2013 ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALESCE NORTH AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CDC LONG TERM...ROBERG AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1222 PM CDT FRI AUG 30 2013 .SYNOPSIS... ISSUED AT 345 AM CDT FRI AUG 30 2013 A STAGNANT H5 PATTERN REMAINS IN PLACE ACROSS THE CENTRAL CONUS TONIGHT WITH A BROAD RIDGE OF HIGH PRESSURE EXTENDING FROM THE SRN ROCKIES WELL INTO CENTRAL CANADA. WV IMAGERY ATTM IS INDICATING A COUPLE OF SHORTWAVES...THE FIRST OVER EASTERN KANSAS...AND A SECOND OVER UTAH AND SWRN WYOMING. AT THE SURFACE...A WEAK FRONTAL BOUNDARY HAS PUSHED INTO NORTH CENTRAL AND WESTERN NEBRASKA THIS EVENING...WHICH HAS INCREASED DEW POINTS INTO THE MID AND UPPER 60S...AND RESULTED IN LIGHT NORTHERLY WINDS. TEMPERATURES AS OF 3 AM CDT...RANGED FROM 65 AT NORTH PLATTE...TO 74 AT ONEILL AND AINSWORTH. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CDT FRI AUG 30 2013 TODAY AND TONIGHT...FORECAST CHALLENGES OVER THE NEXT 24 HOURS ARE TEMPERATURES TODAY...AND PRECIPITATION CHANCES TONIGHT. FOR TODAY...SOME LIMITED RELIEF FROM THE TRIPLE DIGIT HEAT WILL BE SEEN NORTH OF THE FRONTAL BOUNDARY ACROSS NORTHERN NEBRASKA THIS AFTERNOON...AS HIGHS TOP OUT IN THE MIDDLE 90S. SOUTH OF THE FRONT...TEMPS WILL SURGE TOWARD THE CENTURY MARK...TOPPING OUT AT 99 FOR NORTH PLATTE AND OGALLALA AND 102 FOR IMPERIAL. LATER THIS AFTERNOON...THE BEFORE MENTIONED FRONTAL BOUNDARY...WILL LIFT TO THE EAST AS A WEAK WARM FRONT. MID LEVEL LIFT WILL BEGIN TO INCREASE LATE THIS AFTERNOON AND THIS EVENING AS MID LEVEL WARM AIR ADVECTION INCREASES IN ADVANCE OF AN APPROACHING SHORT WAVE TROUGH. MID LEVEL LIFT...COMBINED WITH LOW LEVEL CONVERGENCE INVOF OF THE FRONT...WILL INCREASE THE THREAT FOR THUNDERSTORMS LATER THIS AFTERNOON IN THE NORTHWEST...TRANSITIONING EAST TO THE REMAINDER OF THE FORECAST AREA THIS EVENING. THE ONE LIMITING FACTOR...MAY BE CAP STRENGTH...ESPECIALLY IN THE SRN CWA...AND FOR THAT REASON...WILL LIMIT POPS TO SLIGHT CHANCE ATTM...AS THUNDERSTORM INITIATION IS CONDITIONAL ATTM. ONE DISCLAIMER THOUGH...IF STORMS CAN FIRE...SURFACE TO H400 SHEAR TOPS OUT AT 40 KTS THIS EVENING...SO SOME STRONG TO LOW END SEVERE STORMS MAY BE POSSIBLE...ESPECIALLY OVER NORTHERN NEBRASKA. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 345 AM CDT FRI AUG 30 2013 SATURDAY IS EXPECTED TO BEGIN WITH PARTLY TO MOSTLY SUNNY SKIES. COLD FRONT WILL BE PUSHING INTO FAR NW NEB. BY AFTERNOON HEATING ALONG AND AHEAD OF THE FRONT SHOULD BE ENOUGH TO BREAK THROUGH THE CAP. WITH THE INCREASING OF CLOUDS BY MID TO LATER AFTERNOON...HAVE TEMPS ONLY GOING INTO THE LOWER TO MID 90S NORTHERN AND UPPER 90S SOUTH. FRONT IS SLOWER WITH THE 00Z RUN SO HAVE DELAYED ONSET OF POPS UNTIL THE AFTERNOON. SATURDAY NIGHT THE FRONT WILL BE CROSSING THE REST OF THE CWA...WITH DECREASING CLOUDS AND AN END TO POPS BEHIND THE FRONT. SUNDAY AND LABOR DAY WILL BE PLEASANT DAYS AS COOLER HIGH PRESSURE SETTLES IN BEHIND THE FRONT. 850 MB TEMPS DROP TO AROUND 20 DEGREES WITH GUIDANCE SHOWING HIGHS IN THE 80S...WHICH IS SEASONAL. SUBSIDENCE BEHIND THE FRONT WILL LIMIT CLOUDS AND HIGH PRESSURE WILL KEEP AFTERNOON WINDS AROUND 15 MPH OR LESS. BY TUESDAY THE MODELS ARE IN GOOD AGREEMENT BRINGING AN UPPER LEVEL CLOSED LOW TOWARDS THE PAC NW WEST...WHICH STALLS THROUGH MID WEEK...DUE TO THE BLOCKING RIDGE. SOME DIVERGENCE OF THE MODELS THEN AS THE GFS BRINGS IT ONSHORE INTO WA/OR...WHILE THE EC LIFTS THE LOW INTO SW CANADA. DOWN STREAM IS A PERSISTENT/BLOCKING RIDGE WHICH REPOSITIONS ITSELF OVER THE CENTRAL ROCKIES INTO THE HIGH PLAINS. HEIGHTS INCREASE QUICKLY FOR TUESDAY AND TEMPS SHOULD WARM BACK INTO THE 90S FOR MOST AREAS. RIDGE THAT REDEVELOPS IS NOT QUITE AS STRONG AS CURRENT AND THINK HIGHS WILL GENERALLY REMAIN BELOW 100. ALSO WE ARE GETTING INTO THE FIRST WEEK OF SEPTEMBER WITH SHORTER DAYLIGHT HOURS AND LESS OCCURRENCES OF TRIPLE DIGITS. STILL HAVE A FEW RECORDS AT 100 OR ABOVE SO IT WILL BE POSSIBLE AND NEED TO BE WATCHED. CURRENT FORECAST IS CLOSE TO GUIDANCE WHICH IS HIGHEST IN THE SW NEB...WITH MID 90S. THE STORM TRACK LOOKS TO RIDE THE RIDGE AND CROSS THE DAKOTAS SO A DRY FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1221 PM CDT FRI AUG 30 2013 ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALECSE NORTH AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...CLB LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
915 AM PDT FRI AUG 30 2013 .SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO DECREASE SLIGHTLY FROM MONDAY ONWARD. && .UPDATE...HAVE GONE AHEAD AND EXPANDED THE FLASH FLOOD WATCH TO INCLUDE ALL OF SAN BERNARDINO COUNTY...THE SOUTHERN AREAS OF THE COLORADO RIVER VALLEY AND THE WHITE MOUNTAINS OF INYO COUNTY. PLENTY OF MOISTURE AVAILABLE WITH MOST OF THE PW SENSORS READING BETWEEN 1.75 AND 2.00 INCHES. SO FAR THIS MORNING SHOWERS AND THUNDERSTORMS HAVE MAINLY BEEN CONFINED TO CENTRAL CLARK COUNTY WHERE THERE HAS BEEN SOME ENHANCEMENT FROM A DISTURBANCE MOVING THROUGH ARIZONA. ONLY ISOLATED ACTIVITY ELSEWHERE...BUT COVERAGE IS EXPECTED TO INCREASE THIS AFTERNOON ESPECIALLY IN AREAS THAT ARE SEEING PLENTY OF SUNSHINE THIS MORNING WHICH IS BASICALLY THE FAR WESTERN AND NORTHERN AREAS OF THE CWA. AREAS UNDER THE CLOUD COVER COULD BE DELAYED IN SEEING CONVECTION UNTIL LATER THIS AFTERNOON. && .PREV DISCUSSION... 225 AM PDT FRI AUG 30 2013 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA. AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL. SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA, WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15 ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN 75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS, THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING, HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD IMPACT THE FORECAST FOR SATURDAY. AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH. FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY, BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN WILL BE FLASH FLOODING. TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS. DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW ON PICKING UP ON THIS. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST. SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND. THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY. && .AVIATION...FOR MCCARRAN... FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE, CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES. SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA. && && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ016>022. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR CAZ519>527. && $$ UPDATE...GORELOW SHORT TERM/AVIATION...STACHELSKI LONG TERM...HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
638 AM PDT FRI AUG 30 2013 .SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO DECREASE SLIGHTLY FROM MONDAY ONWARD. && .UPDATE...SHOWERS AND THUNDERSTORMS HAVE DEVELOPED FARTHER WEST THAN EXPECTED THIS MORNING WITH MEASURABLE RAIN HAVING MOVED INTO HENDERSON. UPDATED THE FORECAST TO ACCOUNT FOR THIS TREND. && .PREV DISCUSSION... 225 AM PDT FRI AUG 30 2013 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA. AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL. SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA, WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15 ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN 75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS, THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING, HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD IMPACT THE FORECAST FOR SATURDAY. AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH. FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY, BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN WILL BE FLASH FLOODING. TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS. DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW ON PICKING UP ON THIS. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST. SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND. THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY. && .AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE, CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES. SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ016>022. AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS EVENING FOR AZZ001-003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519-520-522-524. && $$ UPDATE...HARRISON SHORT TERM/AVIATION...STACHELSKI LONG TERM...HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
225 AM PDT FRI AUG 30 2013 .SYNOPSIS...A MOIST AND UNSTABLE ATMOSPHERE WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE AREA THROUGH THIS WEEKEND WITH THE GREATEST CHANCES IN THE AFTERNOON AND EVENING HOURS. THE PRIMARY HAZARD WITH THUNDERSTORMS WILL BE HEAVY RAINFALL THAT COULD RESULT IN FLASH FLOODING. THUNDERSTORM CHANCES ARE EXPECTED TO DECREASE SLIGHTLY FROM MONDAY ONWARD. && .SHORT TERM...TODAY THROUGH SATURDAY NIGHT. WHAT WAS LEFT OF THE CONVECTIVE COMPLEX THAT DEVELOPED OVER MOHAVE COUNTY YESTERDAY AFTERNOON WAS GONE, HOWEVER, THE FOCUS EARLY THIS MORNING ON RADAR NOW SHIFTS TO ONGOING CONVECTION ACROSS YAVAPAI AND COCONINO COUNTIES IN ARIZONA THAT WAS MOVING WESTWARD. THE HRRR MODEL DID NOT DO A BAD JOB INDICATING THIS. THUS USING A BLEND OF THIS MODEL AND THE LATEST RADAR TRENDS, I WENT AHEAD AND ADJUSTED UP POPS ACROSS MUCH OF MOHAVE COUNTY FOR EARLY THIS MORNING AS IT APPEARS MUCH OF THIS ACTIVITY SHOULD HAVE A CHANCE AT MAKING IT OVER THE BORDER INTO OUR AREA. THE CLOUD COVER ASSOCIATED WITH THIS AS WELL AS WHAT REMAINS FROM THE CLOUD COVER FROM THE CONVECTIVE COMPLEX THAT FORMED ON THURSDAY AFTERNOON WILL PRESENT A BIT OF A CHALLENGE AS THIS COULD LIMIT HEATING LATER TODAY OVER MOHAVE COUNTY WHICH MAY DELAY OR INHIBIT CONVECTION ALTOGETHER IN THIS AREA. AS FAR AS WHAT GOES ON THIS AFTERNOON AND EVENING, ACTIVITY WILL BE DRIVEN BY HEATING WITH PERHAPS SOME HELP FROM A WEAK DISTURBANCE AND INVERTED TROUGH IN THE MID-LEVELS WORKING NORTHWEST ACROSS SOCAL. SERIOUS MOISTURE REMAINS IN PLACE ACROSS OUR ENTIRE AREA WITH PWATS REMAINING IN THE UPPER REACHES OF CLIMATOLOGY FOR THIS AREA, WITH VALUES AT OR ABOVE 1.75 INCHES FORECAST TO BE AROUND FROM I-15 ON SOUTH. FORECASTED 700-300 MB THETA E VALUES ARE SHOWN TO BE AT LEAST 340 K ACROSS MOST OF AREA AS WELL. A LOOK AT INSTABILITY PARAMETERS OFF THE MODELS SHOWS INSTABILITY IN PLACE ACROSS OUR ENTIRE AREA, HOWEVER, BOTH THE GFS AND ECMWF SHOW THE GREATEST LI`S OF -2 TO -4 ACROSS MOHAVE, CLARK AND SOUTHERN NYE COUNTIES. SO WHILE WE COULD SEE SHOWERS AND THUNDERSTORMS ACROSS ANY PORTION OF THE AREA THIS AFTERNOON AND EVENING, ODDS LOOK TO FAVOR AN AREA WITHIN 75 MILES ON EITHER SIDE OF A LINE FROM NEAR LONE PINE TO LAS VEGAS TO KINGMAN AS THE MOST ACTIVE LOCATIONS. THUS I WENT AHEAD AND ISSUED A FLASH FLOOD WATCH FOR MOST OF MOHAVE, ALL OF CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND ALL OF INYO COUNTY EXCEPT THE WHITE MOUNTAINS FROM LATE THIS MORNING THROUGH THIS EVENING AS WITH SO MUCH MOISTURE IN PLACE THE UNLOAD POTENTIAL WILL BE THERE IN ANY STRONGER OR SLOWER MOVING STORMS. THE STEERING FLOW SHOWN BY THE WRF AND GFS IS GENERALLY LIGHT AND FROM THE EAST TODAY, HOWEVER, BY THIS EVENING IT DOES TAKE ON MORE OF A NORTHEAST COMPONENT. THUS, THIS MAY BE ONE OF THOSE DAYS WHERE STORMS DO NOT AFFECT THE LAS VEGAS VALLEY UNTIL LATER THIS EVENING AS WE MAY HAVE TO WAIT FOR ACTIVITY TO HEAD IN FROM NORTHWEST ARIZONA, NORTHEAST CLARK COUNTY OR SOUTHWEST UTAH. ACTIVITY SHOULD DECREASE LATER THIS EVENING, HOWEVER, CLOUDS MAY NOT COMPLETELY CLEAR OUT TONIGHT, WHICH COULD IMPACT THE FORECAST FOR SATURDAY. AS FAR AS SATURDAY GOES, RIDGING ALOFT WILL REMAIN CENTERED OVER THE SOUTHWEST AND THIS WILL KEEP OUR AREA IN A SOUTHEAST FLOW ALOFT WHICH WILL ALLOW FOR WHATEVER MOISTURE IS IN PLACE TO REMAIN WITH THE POTENTIAL FOR ADDITIONAL MOISTURE TO WORK INTO THE AREA. ACTIVITY ON SATURDAY WILL DEPEND ON HEATING AND THUS IF WE START OFF TOO CLOUDY THIS COULD LIMIT WHAT WE SEE WITH RESPECT TO SHOWER AND THUNDERSTORM ACTIVITY. THE 00Z RUNS OF THE WRF, GFS, ECMWF AS WELL AS OUR LOCAL HI-RESOLUTION MODELS FAVORED ACTIVITY DEVELOPING MAINLY ACROSS SOUTHERN NEVADA, INYO AND NORTHERN AND CENTRAL MOHAVE COUNTY WITH LESS ACTIVITY FURTHER SOUTH ON THE BACK SIDE OF THE INVERTED TROUGH. FOR NOW WE HAVE HELD OFF ON ANY FLASH FLOOD WATCHES FOR SATURDAY, BUT WITH SO MUCH MOISTURE IN PLACE, THE MAIN CONCERN IN STORMS AGAIN WILL BE FLASH FLOODING. TEMPS WILL CONTINUE TO REMAIN BELOW NORMAL FOR HIGHS AND AT OR ABOVE NORMAL FOR LOWS. I USED A BLEND OF PERSISTENCE, THE SREF AND ECMWF FOR MAX TEMPS AND CONTINUITY AND MOS GUIDANCE FOR MIN TEMPS. DEWPOINTS WERE ADJUSTED UP SLIGHTLY OVER GUIDANCE GIVEN HOW MOIST WE HAVE BEEN THE PAST 2 DAYS AND IT SEEMS MODELS HAVE BEEN A LITTLE LOW ON PICKING UP ON THIS. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS IN PRETTY GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY WITH A PRETTY GENERIC MONSOON PATTERN AND NO SIGNIFICANT WAVES IMPACTING THE AREA. HIGH PRESSURE IS FORECAST ROUGHLY OVER THE COLORADO AND NEW MEXICO BORDER AREA WITH AN AREA OF LOW PRESSURE OFF THE PACIFIC NORTHWEST COAST. SOUTHERLY FLOW OVER THE FORECAST AREA WILL KEEP MONSOON MOISTURE AROUND WITH THE DEEPEST MOISTURE OVER THE EASTERN PORTION OF THE FORECAST AREA AS IS TYPICAL WITH THIS PATTERN. AS A RESULT WE ARE STILL LOOKING AT A CHANCE OF THUNDERSTORMS EAST WITH A SLIGHT CHANCE WEST. MODELS DIFFER FOR WEDNESDAY THROUGH THURSDAY WITH THE GFS AND TO A LESSER EXTENT THE GEM MOVING THE AREA OF LOW PRESSURE INLAND. THIS WOULD BRING DRIER AIR INTO THE AREA FROM THE WEST. THE ECMWF IS EXPANDING THE HIGH WESTWARD WHICH MAY KEEP A BIT MORE MOISTURE IN PLACE BUT ALSO COULD LEAD TO WARMING AND SOME STABILIZING. BASICALLY GOING WITH A BLEND...I MADE LITTLE CHANGE TO THE INHERITED GRIDS AND KEPT AT LEAST A SLIGHT CHANCE OVER THE EASTERN TWO THIRDS OF THE FORECAST AREA WHILE DRYING THE WEST BY THURSDAY. ALSO WENT WITH A WARMING TREND AND ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY. && .AVIATION...FOR MCCARRAN...SHRA/TSRA ARE EXPECTED TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY. SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION THIS AFTERNOON AND EVENING SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z TODAY WITH THE GREATEST COVERAGE ACROSS MOHAVE, CLARK, SOUTHERN NYE, NORTHEAST SAN BERNARDINO AND INYO COUNTIES. SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH THIS EVENING BUT COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. SCT-BKN CLOUDS AOA 10K-15K FEET AWAY FROM ANY SHRA/TSRA. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ016>022. AZ...FLASH FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS EVENING FOR AZZ001-003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519-520-522-524. && $$ STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
941 PM PDT THU AUG 29 2013 .SYNOPSIS...A FAVORABLE UPPER LEVEL FLOW PATTERN WILL CONTINUE TO BRING MONSOON MOISTURE INTO THE AREA THROUGH THE MIDDLE OF NEXT WEEK AND RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. THE PRIMARY HAZARD WITH STORMS...ESPECIALLY THROUGH SUNDAY...WILL BE HEAVY RAINFALL THAT COULD RESULT IN DANGEROUS FLASH FLOODING. && .UPDATE...THE LATEST RADAR SHOWS THE CONVECTIVE COMPLEX THAT GOT GOING OVER MOHAVE COUNTY HAS PUSHED INTO SAN BERNARDINO COUNTY BUT DECREASED IN AREAL COVERAGE. THIS ACTIVITY WILL CONTINUE TO MOVE WESTWARD BUT BASED ON THE HRRR AND RADAR TRENDS SHOULD START TO FALL FURTHER APART AS IT REACHES CENTRAL SAN BERNARDINO COUNTY. THE MAIN THREAT WILL CONTINUE TO BE HEAVY RAINFALL AND I WILL LEAVE THE FLASH FLOOD WATCH UP UNTIL IT EXPIRES AS THIS CONVECTION IS STILL OUT THERE. BEHIND THE LEADING EDGE OF THUNDERSTORMS...MAINLY LIGHT RAIN WAS FALLING ACROSS MOHAVE AND FAR EASTERN SAN BERNARDINO COUNTY AND THIS SHOULD GRADUALLY WIND DOWN OVERNIGHT. I WENT AHEAD AND REMOVED POPS OR LOWERED THEM GREATLY ACROSS THE NORTHERN TWO-THIRDS OF THE AREA FOR THE REST OF TONIGHT AS WE HAVE LOST HEATING AND THERE IS NO ORGANIZED FEATURE CLOSE ENOUGH TO INITIATE CONVECTION IN THESE AREAS. VERY STICKY AIR IS IN PLACE ACROSS OUR AREA WITH DEW POINTS WELL INTO THE 60S AND EVEN 70S ACROSS THE MOJAVE DESERT. JUST OUTSIDE OF OUR AREA THE DEW POINT AT BLYTHE, CALIFORNIA SPIKED TO 79 DEGREES THIS EVENING WHICH IS ABOUT AS HIGH AS ONE WILL SEE OUT HERE IN THE WEST AND EVEN VERY IMPRESSIVE FOR OUT EAST. I WENT AHEAD AND ADJUSTED DEW POINTS UP OVERNIGHT A FEW DEGREES BASED ON CURRENT OBSERVATIONS. WITH RESPECT TO TOMORROW, I WILL TAKE A CLOSER LOOK AT THIS FOR THE MORNING PACKAGE. FROM WHAT I HAVE LOOKED AT SO FAR, THE WRF SUGGESTS LOTS OF LIGHT QPF ACROSS ALL OF MOHAVE COUNTY WHICH SEEMS WACKY BUT MAY NOT BE TOO FAR OFF IF WE WIND UP STAYING CLOUDY THERE OVERNIGHT AND FRIDAY MORNING. THE STEERING FLOW FROM THE WRF AND GFS IS SHOWN TO BE LIGHT EAST WHICH WOULD FAVOR CONVECTION HEADING IN FROM WHAT DEVELOPS OVER NW ARIZONA AND SW UTAH. THE LATEST MODELS ALSO FAVOR ACTIVITY DEVELOPING OVER THE SPRING MOUNTAINS AND ACROSS INTO COUNTY. AGAIN WITH SO MUCH MOISTURE AVAILABLE, FLASH FLOODING WILL BE THE MAJOR CONCERN WITH STORMS, THE BIG QUESTION IS WHAT HAPPENS TO ALL THE DEBRIS CLOUDS IN PLACE TONIGHT. IF THEY CAN CLEAR BY THE LATE MORNING, WE WILL HAVE AMPLE HEATING AND SUFFICIENT INSTABILITY FOR THUNDERSTORMS TO POP-UP ACROSS THE ENTIRE AREA. I WILL HOLD OFF ON ANY NEW FLASH FLOOD WATCHES AT THIS TIME UNTIL I HAVE A BETTER CHANCE TO INSPECT THE MODELS. && .AVIATION...FOR MCCARRAN...DRY CONDITIONS ARE EXPECTED OVERNIGHT WITH WINDS FAVORING TYPICAL DIURNAL TRENDS. SHRA/TSRA ARE EXPECTED TO BE AROUND THE VALLEY MAINLY AFTER 18Z AND ESPECIALLY AFTER 20Z. SHRA AND TSRA ARE EXPECTED TO MOVE IN A WEST TO SOUTHWEST DIRECTION IN THE AFTERNOON SO ACTIVITY THAT DEVELOPS OVER NW AZ OR NORTHEAST CLARK COUNTY WILL NEED TO BE WATCHED - ESPECIALLY FOR ANY OUTFLOW BOUNDARIES. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS BUT OTHERWISE COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA OR OUTFLOW BOUNDARIES WHICH COULD IMPACT AIRPORT CONFIGURATIONS. MAINLY SCT-BKN CLOUDS AOA 10K-15K FEET WITH LOWER CIGS AND VSBY IN AND NEAR ANY SHRA/TSRA. ACTIVITY SHOULD DECREASE BETWEEN 03Z AND 06Z SATURDAY. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SHRA/TSRA SHOULD MAINLY BE ACROSS MOHAVE AND SAN BERNARDINO COUNTIES OVERNIGHT WITH LITTLE TO NO ACTIVITY ELSEWHERE. SCT-BKN CLOUDS AOA 10K-15K FEET SOUTH OF KDAG-KLAS-KSGU LINE WITH FEW IF ANY CLOUDS TO THE NORTH. ON FRIDAY...SHRA/TSRA ARE EXPECTED ACROSS THE AREA AFTER 18Z AND ESPECIALLY AFTER 20Z WITH THE GREATEST COVERAGE ACROSS MOHAVE, CLARK AND INYO COUNTIES. SHRA AND TSRA SHOULD FAVOR A SLOW WESTWARD MOVEMENT ACROSS MOST OF THE AREA. SHRA/TSRA COULD REDUCE VSBY AND CIGS TO MVFR OR LOWER. WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS THROUGH FRIDAY EVENING BUT COULD BE GUSTY AND ERRATIC IN AND NEAR ANY SHRA/TSRA. && .PREVIOUS UPDATE... ISSUED AT 629 PM PDT THU AUG 29 2013 .UPDATE...MOST OF THE ACTION RIGHT NOW IS ACROSS MOHAVE COUNTY WHERE CONVECTION IS PROPAGATING WESTWARD. A PSEUDO-LINE OF CONVECTION PRESENTLY STRETCHED FROM NEAR DOLAN SPRINGS SOUTHWEST TOWARD ALAMO DAM AND LOOKS TO HAVE ENOUGH MOMENTUM TO KEEP GOING TOWARD THE COLORADO RIVER VALLEY. I WENT AHEAD AND INCREASED POPS BY 20-30 PERCENT IN THIS AREA BASED ON THE LATEST RADAR TRENDS. HEAVY RAIN WILL BE THE PRIMARY HAZARD WITH STORMS IN THIS AREA, HOWEVER, GUSTY WINDS WILL ALSO BE A CONCERN IN SPOTS. ELSEWHERE ACTIVITY IS IN THE ISOLATED RANGE AND SHOULD START TO WIND DOWN AS WE LOOSE DAYTIME HEATING. WE WILL NEED TO KEEP AN EYE ON SOUTHERN CLARK AND EASTERN SAN BERNARDINO COUNTY LATER THIS EVENING TO SEE WHAT GOES ON ONCE THE CONVECTION IN MOHAVE COUNTY GETS CLOSER TO THE BORDER. && .PREVIOUS DISCUSSION... ISSUED AT 237 PM PDT THU AUG 29 2013 .SHORT TERM...MAINLY ISOLATED THUNDERSTORMS SO FAR THIS AFTERNOON HOWEVER EXPECTATIONS ARE FOR SOUTHERN MOHAVE AND EASTERN SAN BERNARDINO COUNTIES TO FILL IN BASED ON STORM ACTIVITY JUST OUTSIDE OF THE CWA AND LATEST SATELLITE TRENDS. REGARDING THESE ISOLATED STORMS...IT IS VERY APPARENT THEY ARE LOW MOVING AND EFFICIENT RAIN PRODUCERS. THE RADAR ESTIMATED RAIN RATES AND OBSERVED GAGE DATA ARE QUITE IMPRESSIVE. ANY STORM THAT DEVELOPS HAS THE POTENTIAL TO UNLOAD AND CREATE PROBLEMS QUICKLY SO REMAIN AWARE. TONIGHT THROUGH SUNDAY...SCATTERED TO NUMEROUS HEAVY RAIN PRODUCING SHOWERS AND THUNDERSTORMS ARE EXPECTED IN THE WATCH AREAS THIS EVENING WITH MORE ISOLATED...BUT EQUALLY INTENSE...STORM COVERAGE ELSEWHERE. STORMS EVERYWHERE ARE EXPECTED TO DIMINISH IN INTENSITY AND COVERAGE OVERNIGHT. SIMILAR CONDITIONS ARE IN PLACE FOR SATURDAY AND SUNDAY REGARDING AVAILABLE MOISTURE AND INSTABILITY. HOWEVER... OVERALL COVERAGE COULD BE REDUCED IF FORECASTED THICKER CLOUD COVER BECOMES A REALITY AND LIMITS DAYTIME HEATING. HOPEFULLY THIS WILL BE CLEARER BY MORNING AND HELP DIMINISH THE CURRENT UNCERTAINTY FOR ISSUING ANY ADDITIONAL FLASH FLOOD WATCHES FOR FRIDAY AND SATURDAY. TEMPERATURES ARE GENERALLY EXPECTED TO BE BELOW NORMAL FRIDAY AND SATURDAY BASED ON EXPECTED LACK OF SUNSHINE BUT COULD EXCEED FORECASTED NUMBERS IF CLOUD COVER THINS. .LONG TERM...MONDAY THROUGH THURSDAY...MINIMAL CHANGES MADE TO THE EXTENDED SINCE OVERALL THINKING IS UNCHANGED. MONSOON MOISTURE WILL REMAIN IN PLACE THROUGH THE PERIOD...WITH THE DEEPEST MOISTURE FORECAST OVER MOHAVE COUNTY. THERE REMAINS SOME MODEL AGREEMENT THAT A BIG RIDGE OVER THE CENTRAL STATES WILL GRADUALLY SHIFT WESTWARD BY THE MIDDLE OF THE WEEK...RESULTING IN RISING HEIGHTS THAT COULD HELP WARM TEMPERATURES ALOFT AND CAP THE AIRMASS. OTHERWISE...TYPICAL MONSOON CONDITIONS ARE EXPECTED EACH AFTERNOON/EVENING MINUS ANY TROPICAL INFLUENCE. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...FLASH FLOOD WATCH FROM NOON MST TODAY THROUGH THIS EVENING FOR AZZ002-003. CA...FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING FOR CAZ524>527. && $$ UPDATE...STACHELSKI PREVIOUS...SALMEN FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
751 PM EDT SAT AUG 31 2013 .SYNOPSIS... WARM...HUMID AND UNSETTLED WEATHER IS ON TAP FOR THE HOLIDAY WEEKEND WITH SHOWERS AND THUNDERSTORMS EXPECTED...BEING MOST NUMEROUS THIS AFTERNOON AND THEN AGAIN ON MONDAY. SOME OF THE THUNDERSTORMS WILL BRING LOCALLY HEAVY DOWNPOURS...ALONG WITH THE POSSIBILITY OF STRONG WINDS AND HAIL MONDAY. DRIER AND COOLER WEATHER WILL RETURN FOR THE LATER HALF OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... AS OF 739 PM EDT SATURDAY...PREVIOUS FORECAST IS IN GOOD SHAPE. MAIN CONCERN NEXT SEVERAL HOURS IS POTENTIAL FOR SHOWERS WITH LOCALLY HEAVY RAINFALL...MAINLY ACROSS CENTRAL/S-CENTRAL VT. LATEST RAP SHOWS VERY HIGH PW VALUES (1.8-1.9") ACROSS RUTLAND AND WINDSOR COUNTIES...AND IT APPEARS A WEAK WARM FRONTAL BNDRY EXTENDS EWD FROM WAVE LOW OVER ESSEX COUNTY NY ACROSS S-CENTRAL VT. 2-M DEWPOINTS ALSO REFLECT VERY HUMID AIR MASS IN PLACE WITH DEWPOINTS OF 70F AT BTV AND IN THE LOWER 70S ACROSS S-CENTRAL VT. HEAVIEST RAINFALL SHOULD BE THRU 03-04Z AS WAVE LOW PUSHES EWD ACROSS S-CNTRL VT WITH TRAILING WIND SHIFT LINE SWD ACROSS E-CENTRAL VT. WHILE BETTER INSTABILITY AND ONGOING CONVECTIVE ACTIVITY IS FOCUSING MORE WIDESPREAD STORMS FURTHER SOUTH...CONTINUE TO SEE SCATTERED SHOWERS ACROSS CENTRAL AND S-CENTRAL VT. DESPITE WEAK LAPSE RATES AND LIMITED CAPE...WARM RAIN PROCESSES FAVORING HEAVY DOWNPOURS WITH THIS ACTIVITY. DUAL- POL RAINFALL ESTIMATES SHOW LOCALLY 1.5-1.75" AROUND RUTLAND AND ACROSS N-CENTRAL WINDSOR COUNTY DURING PAST COUPLE OF HRS. WILL CONTINUE TO MONITOR FOR LOCALIZED FLOODING POSSIBLE ACROSS RUTLAND/WINDSOR NEXT FEW HOURS. WITH SATURATED AIRMASS...LOTS OF FOG TONIGHT WITH LIGHT WINDS, HIGH DEWPOINTS, AND LOW TEMPERATURES ONLY IN THE 60S TO AROUND 70. COULD BE SOME BREAKS IN THE CLOUDS LATE TO JUST ADD TO FOG POTENTIAL. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... AS OF 409 PM EDT SATURDAY... SUNDAY THERE WILL BE LOTS OF LOW LEVEL MOISTURE AND FOG EARLY GIVING WAY TO PARTLY SUNNY SKIES BY AFTERNOON. WITH THE WEAK FRONTAL SYSTEM OVER/NEAR OUR AREA A FEW SHOWERS OR THUNDERSTORMS MAY POP ACROSS PORTIONS OF THE AREA, BUT IN GENERAL EXPECTING MORE SUN THAN SATURDAY AND WARMER TEMPERATURES IN THE UPPER 70S TO LOWER 80S. SUNDAY NIGHT...WARM/MUGGY CONDITIONS CONTINUE WITH LOWS ONLY IN THE MID TO UPPER 60S. MODELS SHOWING A SHORTWAVE WITH FALLING HGTS WITH MOISTURE ADVECTING BACK IN LATE SUNDAY NIGHT ALONG WHATEVER WEAK BOUNDARY REMAINS. THIS WILL BE AFFECTING US MAINLY 06-12Z MONDAY SO HAVE GONE ALONG WITH INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVERNIGHT TOWARD 12Z MONDAY. ON MONDAY...MODELS CONTINUE TO BE FAIRLY CONSISTENT SHOWING WIDESPREAD SHOWERS AND THUNDERSTORMS A POTENT SHORTWAVE TROUGH SHIFTS EASTWARD OF GREAT LAKES REGION ALONG WITH A COLD FRONT. NORTH COUNTRY CONTINUES TO BE SITUATED IN A VERY WARM/MOIST AIRMASS WITH SURFACE DEWPOINTS IN THE MID TO UPPER 60S AND FORECAST MAX TEMPS IN THE UPPER 70S TO MID 80S. THIS WILL PROVIDE MODEST SURFACE INSTABILITY WITH SBCAPES ON THE ORDER OF 1000-1500 J/KG AND 0-6KM SHEAR GENERALLY 25-30 KTS. THERE CONTINUES TO BE THE POSSIBILITY OF A COUPLE OF SEVERE STORMS. PWATS REMAIN HIGH IN THE 1.5-2" RANGE SO LOCALLY HEAVY RAINFALL CONTINUES TO BE A THREAT. FRONT IS RATHER SLOW TO MOVE THROUGH THE REGION MONDAY NIGHT SO A DIMINISHING CHANCE OF SHOWERS AND THUNDERSTORMS OVERNIGHT ALONG WITH TEMPERATURES IN THE 60S. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 414 PM EDT SATURDAY...SFC LOW PRESSURE TO OUR NORTH WILL CONTINUE TO BRING A COLD FRONT THROUGH THE ERN HALF OF THE FA ON TUESDAY WITH SOME SCT SHOWERS CONTINUING IN THE FRONTS WAKE AS A WEAKENING SFC TROUGH MOVES IN BEHIND IT. EXPECT DRYING TREND TUESDAY NIGHT WITH SOME SLGT SFC RIDGING. 850MB TEMPS OF 10-14C EARLY TUESDAY WILL COOL TO THE SINGLE DIGITS BY WEDNESDAY MORNING. SFC MAX TEMPS WILL BE IN THE 70S WITH TUESDAY NGT MIN TEMPS IN THE 50S. WEDNESDAY WILL BE DRY WITH CONTINUED SFC RIDGING...BUT CLOUDS STILL PREVALENT...ESP OVER THE HIGH TRRN AS ANOTHER...STRONGER FRONT APPROACHES FROM THE WEST. THIS FRONT WILL BRING MORE RAIN SHOWERS WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. NOT AS MUCH MOISTURE ASSOCIATED WITH THIS FRONT AS IT DRIES UP EARLY THURSDAY. LARGE UPPER LEVEL TROUGH WILL CONTINUE TO PRODUCE CLOUDS OVER THE AREA ON THURSDAY WITH GENERAL NW FLOW KEEPING AT LEAST SLGT CHC OF SHOWERS OVER THE AREA...ESP THE HIGH TRRN. WEDNESDAY MAX TEMPS IN THE 70S WITH NOTICEABLY COOLER MIN TEMPS WEDNESDAY NGT IN THE 40S- M50S. HIGH PRESSURE BUILDS IN OVER THE SRN GREAT LAKES REGION THURSDAY NGT...WITH CLEARING SKIES...DRY WEATHER AND MUCH COOLER TEMPS AS NW FLOW PERSISTS. THE HIGH WILL SLIDE SOUTH AND EAST THRU THE END OF THE WORK WEEK...ALLOWING FOR DRY MOSTLY CLEAR CONDITIONS OVER THE NORTH COUNTRY. 850MB TEMPS WILL DROP TO -2C TO 2C EXPECTED ON THURSDAY. AT THE SFC...MAX TEMPS WILL BE IN THE 60S THURSDAY AND FRIDAY WITH MIN TEMPS IN THE U30S-NEAR 50 THURSDAY AND FRIDAY NIGHTS. LATE FRIDAY NIGHT INTO SATURDAY...ANOTHER COLD FRONT WILL APPROACH FROM THE NORTHWEST...BRINGING YET ANOTHER CHANCE FOR SHOWERS...FOLLOWED BY ANOTHER RIDGE OF HIGH PRESSURE SATURDAY NIGHT INTO SUNDAY. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... THROUGH 00Z MONDAY...WIDESPREAD REDUCTIONS TO MVFR OR LOWER EXPECTED THIS EVENING AND INTO SUNDAY MORNING...IMPROVING TO VFR LATE SUNDAY MORNING. AN ABUNDANCE OF LOW LEVEL MOISTURE WILL ALLOW FOR THE CONTINUANCE OF LOW CEILINGS AND REDUCED VISIBILITIES THROUGH THE NIGHT. SCATTERED RAIN SHOWERS WILL END FOR THE MOST PART AFTER 03Z. WILL KEEP VCSH IN THROUGH 12Z AS A LINGERING ISOLATED RAIN SHOWER OR AREA OF DRIZZLE REMAINS POSSIBLE. OTHERWISE...EXPECTING LARGELY MVFR CEILINGS AT BTV/PBG...IFR OR LOWER CEILINGS CONTINUING OR DEVELOPING AT MPV/SLK/RUT...AND PREDOMINANTLY VFR CEILINGS AT MSS. TRICKY VISIBILITY FORECAST WITH AREAS OF FOG/BR LIKELY...HOWEVER COVERAGE AND DENSITY IS QUESTIONABLE GIVEN WIDESPREAD CLOUD COVER. BTV/PBG SHOULD KEEP VISIBILITIES AT 6SM OR ABOVE FOR THE MAJORITY OF THE NIGHT...WITH SOME IFR/LIFR FOG LIKELY AT MPV/SLK/MSS/RUT AT LEAST FOR A TIME TONIGHT. CONDITIONS START IMPROVING AFTER 12Z SUNDAY WITH VFR EXPECTED AFTER 14Z AT ALL TAF SITES. WINDS WILL BE GENERALLY LIGHT AND VARIABLE THROUGH THE PERIOD. 00Z MONDAY THROUGH THURSDAY... 00Z MONDAY THROUGH 00Z WEDNESDAY...SCT SHOWERS/STORMS THROUGH TUESDAY WITH MVFR/IFR POSSIBLE IN HEAVIER ACTIVITY. HIGHEST THREAT OF PCPN MONDAY/MONDAY EVENING. PATCHY IFR IN BR/FG ALSO POSSIBLE EACH NIGHT...ESPECIALLY AT MPV/SLK. 00Z WEDNESDAY THROUGH 06Z THURSDAY...TRENDING VFR WITH HIGH PRESSURE. PATCHY IFR IN FG AT KMPV/KSLK 06-12Z WED. 06Z THURSDAY ONWARD...INCREASING THREAT FOR SHOWERS AND TSTMS AS COLD FRONT MOVES THROUGH THE AREA FROM NORTHWEST TO SOUTHEAST. && .EQUIPMENT... AS OF 354 AM EDT SATURDAY...NOAA WEATHER RADIO STATION WXM 44... BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE INCONVENIENCE. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...SISSON NEAR TERM...BANACOS/SISSON SHORT TERM...NASH LONG TERM...KGM AVIATION...MUCCILLI EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
354 PM EDT FRI AUG 30 2013 .SYNOPSIS... THE LABOR DAY HOLIDAY WEEKEND WILL FEATURE WARM, HUMID AND UNSETTLED WEATHER. SHOWERS AND THUNDERSTORMS ARE EXPECTED, BEING MOST NUMEROUS SATURDAY AFTERNOON AND MONDAY. SOME OF THE THUNDERSTORMS WILL BRING LOCALLY HEAVY DOWNPOURS. DRIER AND COOLER WEATHER WILL RETURN FOR THE LATER HALF OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 330 PM EDT FRIDAY...STILL MONITORING THE APPROACH OF THE CONVECTIVE CLUSTER MOVING ACROSS EASTERN ONTARIO AND THE GREAT LAKES. RADAR SHOWING A FEW SMALL T-STORMS DEVELOPING BETWEEN MASSENA AND OTTAWA, WHICH IS ALSO AN AREA THAT LOCAL ANALYSIS INDICATES IS MOST UNSTABLE (CAPE APPROACHING 2000 J/KG AND LIFTED INDEX VALUES LESS THAN -4). ELSEWHERE ACROSS THE REGION, CAPE VALUES ARE A LITTLE LOWER (1000-1500 J/KG) ALONG WITH SUB-ZERO LIFTED INDEX VALUES. HOWEVER, HAVEN`T YET SEEN SHOWER DEVELOPMENT. LIKELY DUE TO MID-LEVEL DRY AIR. HOWEVER WATER VAPOR SHOWS INCREASING MOISTURE MOVING IN, SO WOULD THINK WE SHOULD BE ABLE TO POP A FEW INSTABILITY SHOWERS YET THIS AFTERNOON. HAVE KEPT IN SOME SMALL POPS FOR THE EARLY EVENING FOR THE HIGHER TERRAIN. OTHERWISE, THE FORECAST REALLY HINGES ON HOW THE CONVECTIVE CLUSTER WILL EVOLVE TONIGHT AS IT MOVES INTO OUR AREA. MODELS CONTINUE TO STRUGGLE WITH ALL THE DETAILS, AND THIS LEADS TO LOW CONFIDENCE IN OVERALL FORECAST DETAILS. DO THINK THE 15Z HRRR HAD A DECENT HANDLE ON THINGS AND SO HAVE TRIED TO PAINT ITS SCENARIO IN. BASICALLY ITS FOR CONVECTION TO REACH THE ST LAWRENCE VALLEY ABOUT 5PM AND WORK ITS WAY EASTWARD DURING THE MID EVENING. HOWEVER SHORTWAVE SUPPORT APPEARS TO BE WEAKENING AND WITH LOSS OF SUN, CONVECTION SHOULD DIMINISH AFTER SUNSET AS IT GETS TOWARD VERMONT. BY MIDNIGHT EXPECT A BROKEN BAND OF SHOWERS -- PERHAPS AN ISOLATED THUNDERSHOWER -- TO BE DISSIPATING ACROSS THE REGION. NOT LOOKING FOR ANYTHING STRONG OR SEVERE OR MUCH IN THE WAY OF HEAVY RAIN (OUTSIDE LOCALIZED DOWNPOUR). SEMI-BROADBRUSHED THE GRIDDED FORECAST AS SPECIFIC LOCATION AND TIMING IS STILL TOO FUZZY. SKIES OVERNIGHT WILL TREND MOSTLY CLOUDY. THE DEBRIS CLOUDS WILL KEEP TEMPERATURES IN THE 60S FOR PRETTY MUCH EVERYONE. ADD ON DEWPOINTS IN THE 60S, IT WILL BE RATHER MUGGY. THE CLOUDS SHOULD PRECLUDE MUCH IN THE WAY OF ANY DENSE FOG FROM FORMING. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 330 PM EDT FRIDAY...SATURDAY THE REGION WILL BE SMACK DAB IN THE CONTINUE WARM AIRMASS THAT WILL ALSO HAVE BECOME JUICED FROM INCREASED MOISTURE. PRECIPITABLE WATER VALUES SHOULD BE UP AROUND 1.75". A WEAK SURFACE BOUNDARY WILL BE STRUNG OUT JUST TO OUR NORTH AND ADD IN OTHER WEAK BOUNDARIES FROM THE LEFTOVER CONVECTIVE COMPLEX, WE WILL CERTAINLY HAVE PLENTY OF FOCUS MECHANISMS FOR CONVECTIVE DEVELOPMENT. SHOULD BE ABLE TO SQUEAK OUT A BIT OF SUNSHINE DURING THE MORNING, SO TEMPERATURES SHOULD CLIMB QUICKLY THROUGH THE 70S AND PERHAPS INTO THE LOW 80S IN A FEW SPOTS. THIS WILL PRODUCE ABUNDANT SURFACE BASED INSTABILITY WITH CAPE VALUES OVER 1500 J/KG AND NEGATIVE LIFTED INDEX VALUES. TOSS IN A LITTLE UPPER LEVEL ENERGY ZIPPING BY DURING MID- DAY, AND ALL THE INGREDIENTS ARE IN PLACE FOR DEVELOPMENT OF WIDESPREAD THUNDERSTORMS. WIND FIELDS ARE NOT ALL THAT STRONG, NOR IS THERE MUCH SHEAR, SO THE STORMS WILL BE MORE DISORGANIZED BUT CAPABLE OF PRODUCING SOME LOCALLY HEAVY DOWNPOURS. THIS COULD CAUSE A LITTLE BIT OF MINOR FLOODING PROBLEMS. SATURDAY NIGHT - STORMS SHOULD WIND DOWN IN THE EVENING, BUT LOTS OF CLOUDS WILL REMAIN. ANOTHER WARM/MUGGY NIGHT WITH TEMPERATURES IN THE MID-UPPER 60S FOR MOST OF US. SUNDAY - LOOKS LIKE THE QUIETEST WEATHER FOR THE WEEKEND. THAT SURFACE BOUNDARY SLIDES TO A POINT JUST SOUTH OF HERE, SO EVER SO SLIGHTLY MORE STABLE CONDITIONS. NO IDENTIFIABLE TRIGGER ALOFT EITHER. SO THAT SAID, SURFACE DEWPOINTS WILL STILL BE WELL INTO THE 60S, SO ITS CONTINUED HUMID. SUNSHINE WILL AGAIN RESULT IN CONVECTION STARTING TO BUBBLE UP BY MID-DAY. HAVE PAINTED INTO THE GRIDS SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS. COVERAGE WONT BE AS STUPENDOUS AS ON SATURDAY AND MOST OF US MAY MANAGE TO STAY DRY. SUNDAYS TEMPERATURES SHOULD RISE INTO THE LOWER TO PERHAPS 80S AS SUNSHINE OFFSETS A SLIGHTLY COOLER AIRMASS (925MB TEMPERATURES SHOULD BE 17-19C VS 20-22C THAT WERE OVERHEAD ON SATURDAY) SUNDAY NIGHT - FAIRLY SIGNIFICANT UPPER TROUGH BEGINS TO DEVELOP SOMEWHERE TO OUR WEST. SO ALTHOUGH ANY DAYTIME HEATING CONVECTION SHOULD WIND DOWN IN THE EVENING, BY LATE NIGHT WE MAY SEE SHOWERS/ISOLATED THUNDERSTORM RETURN TO THE AREA ALL THANKS TO SOUTHERLY FLOW BECOMING DEEPER AND MORE ESTABLISHED. STILL A SWEATY/WARM/MUGGY NIGHT WITH ALL THE CLOUDS AND HIGH DEWPOINTS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 330 PM EDT FRIDAY...CHANGEABLE WEATHER EXPECTED THROUGH THE EXTENDED FCST PERIOD AS THE PATTERN TRANSITIONS FROM A WARM AND HUMID AIR MASS WITH WIDESPREAD SHOWERS AND TSTMS ON MONDAY TO QUIET...DRY CONDITIONS AND BELOW AVERAGE TEMPERATURES BY THE END OF THE WORK WEEK. IN FACT...CURRENT INDICATIONS ARE THAT THE FIRST FROST OF THE SEASON IS POSSIBLE THURSDAY NIGHT OR FRIDAY NIGHT ACROSS THE NRN ADIRONDACKS AND ESSEX COUNTY VT. THE 12Z GFS REMAINS CONSISTENT WITH PREVIOUS RUNS SHOWING POTENTIAL FOR WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY AFTN INTO MONDAY EVENING. UPSTREAM 700-500MB SHORTWAVE TROUGH IS PROGGED TO AMPLIFY ACROSS THE ERN GREAT LAKES REGION WITH INCREASING SWLY DEEP-LAYER SHEAR TO 30-35 KTS ACROSS THE NORTH COUNTRY. PRE-EXISTING AIR MASS SHOULD REMAIN MODERATELY HUMID WITH BOUNDARY LAYER DEWPOINTS IN THE MID-UPR 60S AND HIGH TEMPS IN THE LOWER 80S IN VALLEY LOCATIONS. THIS WILL CONTRIBUTE TO MODERATE SURFACE-BASED INSTABILITY WITH CAPE VALUES 1000-2000 J/KG. MID-LEVEL LAPSE RATES AND LOW-LEVEL SHEAR NOT GREAT...BUT OVERALL CONDITIONS FAVOR A FEW SVR STORMS MONDAY AFTN/EARLY EVE WITH LOCALLY DAMAGING WINDS AND MARGINALLY SVR HAIL. PW VALUES PEAK AROUND 1.70 INCHES 00Z TUESDAY AND SUPPORT LOCALLY HEAVY DOWNPOURS WITH THE CONVECTIVE STORMS. SURFACE TROUGH TRANSLATES EWD ACROSS THE AREA DURING MONDAY NIGHT AND AS INSTABILITY DIMINISHING SHOULD SEE CONTINUED CHANCES FOR SHOWER ACTIVITY...GRADUALLY LESSENING FROM WEST TO EAST OVERNIGHT. NOT A FRONT...SO WITH LITTLE LOW-LEVEL CAA AND CONTINUED CLOUDS SHOULD SEE LOWS MAINLY IN THE LOW-MID 60S. LINGERING UPPER TROUGH ON TUESDAY...MAY GENERATE ISOLD/SCT SHOWERS DURING THE AFTN HOURS. STILL WARM WITH HIGHS IN THE MID 70S TO NEAR 80...WITH SLIGHTLY LESS HUMIDITY. ONCE THE UPR TROUGH CLEARS THE AREA LATE TUESDAY/TUESDAY NIGHT...SHOULD TRANSITION TO MOSTLY CLEAR CONDITIONS. PROSPECTS GOOD FOR VALLEY FOG ON TUESDAY NIGHT/WED MORNING AS A RESULT WITH LOWS IN THE 50S TO AROUND 60. WED-FRI: WEDNESDAY...LOOKS DRY AND MOSTLY SUNNY WITH SW-NE ORIENTED LOW-LEVEL RIDGE AXIS IN PLACE. SHOULD SEE NEAR SEASONABLE HIGHS IN THE MID 70S. A COLD FRONT SLIDES SEWD ACROSS THE REGION ON THURSDAY...AND SHOULD BE ASSOCIATED WITH A NARROW BAND OF SHOWERS THURSDAY AFTN. SHOWING 30 POPS WITH THIS FEATURE FOR THURSDAY AFTN. IN THE WAKE OF THE COLD FRONT...STRONGER CAA AND SHOULD SEE LOWS DOWN INTO THE 40S THURSDAY NIGHT WITH HIGHS 62-68F ON FRIDAY. LARGER SFC ANTICYCLONE BUILDS IN THU NIGHT THRU FRIDAY...AND OVERALL PATTERN MAY ALLOW A FROST TO OCCUR THU NIGHT OR FRIDAY NIGHT IN THE COLDER SPOTS WITHIN THE NRN ADIRONDACKS AND IN THE SHELTERED VALLEYS OF THE NORTHEAST KINGDOM...ESPECIALLY IN ESSEX COUNTY VT. GOOD POTENTIAL AGAIN FOR RIVER VALLEY FOG THURSDAY NIGHT AND FRIDAY NIGHT BASED ON SYNOPTIC PATTERN AND ASSOCIATED CLIMATOLOGY. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... THROUGH 18Z SATURDAY...VFR AT ALL TERMINALS EARLY THIS AFTN AS LOW CLOUDS HAVE MIXED OUT WITH DAYTIME HEATING. MAIN FOCUS NOW IS ON UPSTREAM SHOWER ACTIVITY IN ADVANCE OF SHORTWAVE TROUGH CROSSING LAKE HURON AND SERN ONTARIO AT 17Z. SCATTERED SHOWERS WILL LIKELY IMPACT SLK/MSS BETWEEN 20-23Z...WITH A SLIGHT CHANCE OF A TSTM. A BIT MORE DIFFICULT TO TELL IF TAF SITES FROM THE CHAMPLAIN VALLEY EWD WILL BE AFFECTED...BUT CERTAINLY A CHANCE 22-02Z OF A SHOWER OR T-STORM WITH BRIEF MVFR CONDITIONS. HAVE OPTED TO LEAVE OUT OF THE TAFS ATTM FROM PBG EASTWARD GIVEN GREATER UNCERTAINTY. WINDS THRU THIS EVENING WILL BE FROM THE S-SW AT 5-10 KTS...EXCEPT LOCALLY SE 10 KTS AT PBG WITH THE ONGOING LAKE BREEZE. GREATER POTENTIAL FOR MID-LEVEL CLOUDS TONIGHT...SO OPTED NOT TO INCLUDE FOG MENTION GIVING BKN-OVC100-120. ADDITIONAL SHORTWAVE TROUGH AND ASSOCIATED SFC TROUGH MOVE THRU WITH POTENTIAL FOR MORE WIDESPREAD SHOWERS AND TSTMS...ESPECIALLY DURING SATURDAY AFTN. AT THIS POINT...INCLUDED MORNING MENTION OF SHRA AT SLK/MSS...AS THEY WILL LIKELY SEE SOME ACTIVITY BEFORE THE END OF THE TAF PERIOD. REMAINING SITES HAVE BEST CHANCE FOR SHOWERS/TSTMS AFTER 18Z SATURDAY. 18Z SATURDAY THROUGH WEDNESDAY...SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THRU THE AVIATION OUTLOOK PERIOD. FIRST SFC/UPR TROUGH BRINGS WIDESPREAD SHOWERS AND T-STORMS DURING SATURDAY AFTN AND EVENING. SHOULD SEE BRIEF INTERVALS OF MVFR AND POSSIBLE BRIEF IFR AT ALL TAF LOCATIONS ASSOCIATED WITH THE CONVECTIVE ACTIVITY. ANY PRECIPITATION SHOULD BE ISOLD SUNDAY...WITH MAINLY VFR CONDITIONS DURING THE DAYLIGHT HRS. ANOTHER STRONG UPR TROUGH APPROACHES THE REGION FROM THE WEST DURING MONDAY/MONDAY NIGHT...LIKELY RESULTING IN NUMEROUS ADDITIONAL SHOWERS AND TSTMS...ESPECIALLY MONDAY AFTN/EVE. DURING THESE HIGHER THREAT PERIODS A FEW OF THE STORMS COULD TREND STRONG WITH GUSTY WINDS/TURBULENCE/FRQ LIGHTNING. SCATTERED SHOWERS POSSIBLE TUESDAY AND TRENDING DRIER FOR WEDNESDAY. PATCHY BR/FG AND ASSOC MVFR/IFR CONDS ALSO POSSIBLE FROM 06-12Z EACH MORNING...WITH HIGHEST CONFIDENCE AT MPV AND SLK. && .EQUIPMENT... AS OF 342 AM EDT FRIDAY...NOAA WEATHER RADIO STATION WXM 44... BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE INCONVENIENCE. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...NASH SHORT TERM...NASH LONG TERM...BANACOS AVIATION...BANACOS EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
332 PM EDT FRI AUG 30 2013 .SYNOPSIS... RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER- LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY MUGGY...THROUGHOUT THE HOLIDAY WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1015 AM UPDATE... FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS CONVECTION INTO FA LATE THIS AFTN. A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE HWO ACCORDINGLY. PREV DISCO BLO... 4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z). BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION). OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS. AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... 420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z). FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN CONVECTIVE WAVES. ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST. WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70). && .LONG TERM /MONDAY THROUGH FRIDAY/... 315 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO PREVIOUS FORECASTS. MODELS THIS AFTERNOON AGAIN ARE IN GOOD AGREEMENT WITH MID WEEK BUT DISAGREE GREATLY IN THE EXTENDED. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THROUGH LATE TUESDAY NIGHT. WENT WITH MORE OF A ECMWF/CMC BLEND. LEANED MORE TOWARDS ECMWF GUIDANCE SINCE THIS MODEL HAS BEEN MOST CONSISTENT WITH PREVIOUS RUNS. TUESDAY A COLD FRONT WILL PASS THROUGH THE REGION BRINGING CAA TO THE NE PA AND C NY. MODELS STILL DIFFER GREATLY IN THE EXTENDED SO WENT WITH A CONSERVATIVE PERSPECTIVE TO TEMPS WITH LOWS IN THE UPPER 40S TO LOW 50S AND HIGHS IN THE UPPER 60S TO LOW 70S WED THRU FRIDAY. PREVIOUS UPDAT... 430 AM FRI... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL. THE PREVIOUS AFD IS BELOW... && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... 145 PM EDT UPDATE... THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW. TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT. OUTLOOK... SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MLJ NEAR TERM...MLJ/PVN SHORT TERM...MLJ LONG TERM...KAH/EH AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
209 PM EDT FRI AUG 30 2013 .SYNOPSIS... RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER- LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY MUGGY...THROUGHOUT THE HOLIDAY WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1015 AM UPDATE... FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS CONVECTION INTO FA LATE THIS AFTN. A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE HWO ACCORDINGLY. PREV DISCO BLO... 4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z). BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION). OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS. AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... 420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z). FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN CONVECTIVE WAVES. ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST. WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70). && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL. THE PREVIOUS AFD IS BELOW... PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT. THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW. THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY BRINGING A COLD FRONT TO THE AREA. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... 145 PM EDT UPDATE... THE FOG/LOW STRATUS DECK HAS FINALLY ERODED THIS AFTERNOON ACROSS THE CWA. VFR CONDITIONS HAVE RETURNED AND EXPECT THESE CONDITIONS TO PREVAIL THROUGH MUCH OF THE AFTERNOON. A LINE OF LIGHT SHOWERS OVER WESTERN NEW YORK ARE SLOWLY MOVING EAST AND MAY AFFECT THE TAF SITES. CONFIDENCE IS NOT HIGH ABOUT THIS LINE REMAINING INTACT...THUS HAVE LEFT IT OUT OF THE TAF FOR NOW. TONIGHT WILL BE A CHALLENGING FORECAST. DO NOT BELIEVE FOG WILL DEVELOP LIKE PREVIOUS NIGHTS AS STRONG MID AND LOW LEVEL MIXING IS PRESENT...BUT RAIN SHOWERS WILL MOVE INTO THE REGION FROM WEST TO EAST LATE TONIGHT MAKING THE FORECAST DIFFICULT. THESE SHOWERS ARE EXPECTED TO START OUT LIGHT WITH VFR CLOUD HEIGHTS THEN TRANSITION TO MVFR AND BECOME HEAVY AT TIMES. SHOWERS ARE EXPECTED TO CONTINUE THROUGH LATE AFTERNOON ON SATURDAY. EMBEDDED THUNDERSTORMS ARE POSSIBLE WITH ISOLATED IFR CONDITIONS BUT CONFIDENCE IS NOT HIGH WITH TIMING SO DECIDED TO LEAVE IT OUT. OUTLOOK... SAT-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MLJ NEAR TERM...MLJ/PVN SHORT TERM...MLJ LONG TERM...HEDEN/KAH AVIATION...KAH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1030 AM EDT FRI AUG 30 2013 .SYNOPSIS... RAIN-FREE CONDITIONS ARE EXPECTED TODAY...ALONG WITH A CONTINUATION OF WARM TEMPERATURES...AS A RIDGE OF HIGH PRESSURE RESIDES ALONG THE EAST COAST. STARTING TONIGHT...AND THEN LASTING THROUGH THE WEEKEND...OUR WEATHER WILL BECOME MORE UNSETTLED...AS A SLOWLY APPROACHING FRONTAL BOUNDARY...ALONG WITH PASSING UPPER- LEVEL DISTURBANCES...BRING PERIODIC BOUTS OF SHOWERS AND THUNDERSTORMS. IT WILL ALSO REMAIN QUITE WARM...AND INCREASINGLY MUGGY...THROUGHOUT THE HOLIDAY WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1015 AM UPDATE... FOG IS BURNING OFF AND IS EXPECTED TO RESULT IN PARTLY-MOSTLY SUNNY SKIES THIS AFTN. THIS WL ALLOW TEMPS TO RISE CLOSE TO YDA`S VALUES IN THE L/M 80S. WL KEEP AN EYE ON AREA OF SHOWERS MVNG INTO LKS ERIE AND ONTARTIO AHD OF WK INITIAL S/WV. THIS WV WL PROPAGATE INTO WRN PART OF CWA AFT 21Z AND LATEST HRRR BRINGS CONVECTION INTO FA LATE THIS AFTN. A STRONG S/WV IS NOW ROTATING ACRS LK SUPERIOR AND IS MAKING A BEELINE FOR THE CWA FOR THE OVRNGT HRS. CURRENT THINKING IS THAT WIND SHEAR VALUES WL INCREASE BTWN 03Z AND 06Z AND WL LOOK TO UP POPS WITH THE AFTN PACKAGE. POTENTIAL EXISTS FOR STRONG WINDS AND TORRENTIAL DOWNPOURS TONIGHT, ESPECIALLY FOR NRN ZONES. PW VALUES INCREASE TO NEAR 1.60 INCHES WHICH IS 1-2 STANDARD DEVIATIONS ABV NORMAL. H8 FLOW ONLY INCREASES TO NEAR 20KTS BY THIS TIME SO THINK THE BIGGEST THREAT WL BE LOCALLY HVY RAINFALL AND PLAN TO UPDATE HWO ACCORDINGLY. PREV DISCO BLO... 4 AM FRI UPDATE... LWR STRATUS CLDS AND FOG HAVE BECOME WIDESPREAD ONCE AGN EARLY THIS MRNG. MUCH LIKE YDY...GIVEN A MOIST BLYR ENVIR...AND WEAK FLOW/VERT MIXING...IT WILL LIKELY TAKE A WHILE FOR THE FOG TO LIFT...AND THE CLDS TO BREAK UP (13-15Z). BY MIDDAY/EARLY AFTN...THE EARLIER MRNG STRATUS LYR SHOULD EVOLVE INTO A SCT-BKN CU FIELD...WITH OCNL HIGHER-LVL CLOUD DEBRIS ALSO COMING IN FROM THE NW (EMANATING FROM UPSTREAM CONVECTION). OVERALL...PTLY SUNNY SEEMS LIKE A GOOD SKY COVER DESCRIPTOR. GIVEN SIMILAR 925-850 MB TEMPS TO THU...AND ALSO A FAIRLY SIMILAR DEGREE OF INSOLATION...MAX TEMPS SHOULD ONCE AGN RANGE FROM THE UPR 70S OVER THE HIGHER TERRAIN OF THE CATSKILLS...TO THE UPR 80S IN PTNS OF THE FINGER LKS RGN...AND OUR LAKE PLAIN CNTYS. AS FAR AS CONVECTIVE POTENTIAL...WE THINK THE VAST MAJORITY OF THE DAY...IF NOT THE ENTIRE DAY...WILL BE DEVOID OF ANY SHWRS/TSTMS. THE S/WV WHICH PASSED THROUGH OUR RGN EARLY LAST EVE...IS NOW DOWN OVER ERN VA...WITH DVM ALOFT/MID-LVL CAPPING EXPECTED TO REMAIN OVER CNY/NE PA FOR A GOOD PTN OF THE DAY. THE NEXT S/WV UPSTREAM (SEEN ON WATER VAPOR IMAGERY OVER NRN MI ATTM) IS NOT EXPECTED TO APPROACH/BEGIN IMPACTING THE FA TIL ARND...OR AFTER 00Z. GIVEN THE LIKELIHOOD OF 1000-1500 ML CAPES LTR TDY...WE CAN`T COMPLETELY RULE OUT AN ISOLD TSTM OVER THE CATSKILLS/POCONOS...OR NEAR ANY LAKE CONV BNDRYS DURG PEAK HEATING. HOWEVER..WE DON`T FEEL SUCH COVERAGE/POTENTIAL (UNDER 10-15%) JUSTIFIES INCLUSION IN THE FCST. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... 420 AM FRI UPDATE... THE ABV REFERENCED S/WV OVER THE NRN LKS RGN EARLY THIS MRNG...IS PROGGED TO TRACK NEAR LK ONT/UPSTATE NY THIS EVE. FORCING FROM THIS FEATURE SHOULD CAUSE AN INCREASE IN CONVECTIVE COVERAGE AFTER DARK....AND WE`LL THUS CARRY SCTD SHWRS/TSTMS MOST AREAS...WITH A SMALL WINDOW FOR THE LIKELIHOOD OF SUCH ACTIVITY IN OUR FAR NRN ZNS (03-09Z). FOR THE NEXT COUPLE OF DAYS (SAT-SUN)...WE`RE EXPECTING A SCENARIO FEATURING THE PASSAGE OF SVRL S/WVS (SOME PERHAPS CONVECTIVELY INDUCED FROM UPSTREAM)...AND ALSO THE GRADUAL APPROACH OF A SFC FRONTAL BNDRY...ULTIMATELY EXPECTED TO LIE JUST N/W OF THE CWA BY SAT NGT/SUN. AFTER TNT`S ROUND OF SHWRS/TSTMS (FAIRLY HIGH CONFIDENCE FCST)...THE TIMING OF SUBSEQUENT CONVECTIVE ROUNDS BCMS DIFFICULT TO PIN DOWN THIS FAR OUT. THUS...FOR NOW...WE`LL SIMPLY MAINTAIN CONTINUITY...AND RETAIN OUR FCST OF SCTD SHWRS/TSTMS...WITH THIS ACTIVITY LIKELY TO PEAK DURG MAX HEATING/DESTABILIZATION EACH AFTN/EARLY EVE. SOMEWHAT HIGHER POPS WILL BE INDICATED FOR NRN/WRN PTNS OF THE FA (40-50%...VERSUS 20-30% DOWN OVER NE PA)...CLOSER TO THE ABV MENTIONED FRNT. ALL OF THIS BEING SAID...THIS WEEKEND WILL NOT BE A COMPLETE WASHOUT (SHWRS/TSTMS SCTD IN NATURE)...WITH SIG RAIN-FREE PDS ANTICIPATED...IN BETWEEN CONVECTIVE WAVES. ALTHOUGH THE ENVIR IS LIKELY TO BECOME QUITE UNSTABLE BOTH SAT AND SUN AFTNS (ML CAPES OF 1500-2500)...MODEL CONSENSUS SHOWS THE DEEP-LYRD SHEAR TO BE FAIRLY WEAK (0-6 KM VALUES OF ONLY 15-20 KT MUCH OF THE TIME). THUS...TSTMS SHOULD BE LARGELY NON-SVR (GARDEN VARIETY)...WITH PERHAPS AN ISOLD PULSE-TYPE SVR STORM AT WORST. WARM MUGGY CONDS WILL REMAIN AT PLAY THIS PD (DAYTIME HIGHS WELL INTO THE 80S...AND NIGHT-TIME LOWS IN THE 60S-NEAR 70). && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM FRI UPDATE... LITTLE TO CHANGE FROM THE PREVIOUS FORECAST FROM YESTERDAY AFTERNOON. THE LONGER RANGE MODELS ARE IN GOOD AGREEMENT WITH A TROF EARLY IN THE PERIOD ALONG WITH A SHOT OF COOLER WEATHER THROUGH MID-WEEK. BY THURSDAY ANOTHER FRONT MOVES THROUGH THE AREA WITH A CHANCE OF SHOWERS. IT WILL BE INTERESTING WITH RESPECT TO WHAT HAPPENS WITH THIS SECOND TROF LATER IN THE WEEK. THE NEW 0Z EURO IS MUCH SHARPER WITH THE TROF WITH 850 TEMPS AS CHILLY AS -2C BY 12Z FRIDAY ACROSS NY STATE. MEANWHILE THE GFS HAS 850 TEMPS OF +16C DURING THE SAME TIME. TALK ABOUT A DIFFERENCE! NO CLEAR SIGN WHICH WAY TO LEAN AT THIS POINT WITH THE CANADIAN FAVORING THE GFS...WHILE SOME OF THE GFS ENSEMBLES FAVORING THE EURO. WILL BE FUN TO WATCH AS WE TURN TOWARD FALL. THE PREVIOUS AFD IS BELOW... PREV DISC... 3 PM EDT UPDATE... MADE MINOR ADJUSTMENTS TO THE PREVIOUS FORECAST. A STRONG UPPER LEVEL TROUGH DIPS SOUTH OUT OF CANADA ON SUNDAY ACROSS THE UPPER GREAT PLAINS AND THEN MOVES EASTWARD TOWARDS THE GREAT LAKES ON MONDAY. THE INFLUENCE FROM THIS SYSTEM WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS MONDAY NIGHT THROUGH WEDNESDAY. THE UPPER LOW WILL CONTINUE TO MIGRATE EASTWARD AND MOVE OFF THE EAST COAST BY WEDNESDAY NIGHT. THE ECMWF IS SLIGHTLY STRONGER THAN THE GFS...HOWEVER BOTH ARE IN PRETTY GOOD AGREEMENT ON THE PLACEMENT OF THE TRACK OF UPPER LOW. THURSDAY ANOTHER UPPER LOW WILL MOVE NORTH OF THE REGION POSSIBLY BRINGING A COLD FRONT TO THE AREA. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... 700 AM UPDATE... DENSE FOG WILL PRODUCE WIDESPREAD RESTRICTIONS FOR THE NEXT FEW HOURS OUTSIDE OF KSYR. WORST CONDITIONS WILL BE AT KITH AND BGM. LIFR CONDITIONS CONTINUE HERE THROUGH 13Z BEFORE SLOW IMPROVEMENT TO VFR BY 15Z. KAVP AND KRME...IFR CIGS AND VSBYS WILL SLOWLY IMPROVE TO VFR BY 15Z. AFTER MID MORNING VFR IS EXPECTED THE REST OF TODAY. NEAR CALM CONDITIONS THROUGH DAYBREAK. WINDS INCREASE TO 4 TO 8 KTS 13 TO 16Z AND REMAIN THROUGH THE AFTN. OUTLOOK... FRI NGT...GENERALLY VFR SOME MVFR POSSIBLE NORTHERN TERMINALS IN SHOWERS/STORMS. SAT-TUES...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MLJ NEAR TERM...MLJ/PVN SHORT TERM...MLJ LONG TERM...KAH AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
858 PM EDT SAT AUG 31 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL PREVAIL THROUGH THE REST OF THE WEEKEND. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON MONDAY...THEN PUSH SLOWLY EAST THROUGH THE CAROLINAS ON TUESDAY. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY AND LINGER THROUGH THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 200 PM SATURDAY... OVERVIEW: LIGHT NW FLOW ALOFT WILL PREVAIL ACROSS THE REGION THROUGH TONIGHT...IN A WEAKNESS BETWEEN AN UPSTREAM RIDGE OVER THE SOUTHERN PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST. 17Z WV IMAGERY AND RAP DATA INDICATED SMALL AMPLITUDE DISTURBANCES UPSTREAM ACROSS OH/KY/WV...TRACKING SOUTHEAST TOWARD THE MID- ATLANTIC AND NORTHERN PORTIONS OF NC. PRECIPITATION CHANCES: THE LOW-LEVEL RIDGE EXTENDING WESTWARD INTO CENTRAL NC THIS MORNING HAS FURTHER WEAKENED...GIVING WAY TO AN INCREASINGLY MOIST SOUTHERLY RETURN FLOW FROM THE SFC-925 MB...WITH ADDITIONAL MOISTURE ADVECTING INTO THE AREA FROM THE WEST/WNW AT H85. SEASONABLY STRONG INSOLATION WILL RESULT IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION BY PEAK HEATING WITH MLCAPE VALUES RANGING FROM 1500-2000 J/KG IN THE WESTERN PIEDMONT TO 500-1000 J/KG IN THE EAST WHERE THE LOW-LEVELS ARE DRIER AS NOTED ABOVE. THE PRIMARY UNCERTAINTY W/REGARD TO CONVECTION WILL BE FORCING. VERY LITTLE IF ANY LOW-LEVEL FORCING WILL BE PRESENT THIS AFT/EVE WITH LARGELY UNIDIRECTIONAL SFC-925 MB FLOW OVER CENTRAL NC. ADDITIONALLY...UPPER LEVEL FORCING /DPVA/ IS EXPECTED TO REMAIN N/NW OF CENTRAL NC THIS AFT/EVE AS SMALL AMPLITUDE DISTURBANCES TRACK SLOWLY E/ESE FROM THE OH VALLEY INTO THE WV AND CENTRAL/WESTERN VA. AN MCV AND A ROBUST COLD POOL ASSOC/W AN ONGOING MCS UPSTREAM OVER EASTERN KY AND SOUTHWEST VA AT 17Z IS LIKELY TO TRACK SOUTHEASTWARD TOWARD NORTHWEST NC AND MAY PROVIDE SUFFICIENT FORCING FOR CONVECTION TO DEVELOP IN THE NW PIEDMONT LATE THIS AFT/EVE (22-04Z). WITH THE ABOVE IN MIND...WILL INDICATE PRECIP CHANCES OF 20-30% WEST OF THE HWY 1 CORRIDOR WITH THE RELATIVE BEST CHANCE IN THE TRIAD. EAST OF HWY 1...GIVEN A PROFOUND LACK OF FORCING AND A DRIER LOW-LEVEL AIRMASS /MARGINAL DESTABILIZATION/... WILL KEEP THE FCST DRY. CHANCES FOR CONVECTION WILL DECREASE BY MIDNIGHT IN ASSOC/W INCREASING NOCTURNAL STABILIZATION...THOUGH IF SMALL AMPLITUDE DISTURBANCES AND/OR THE AFOREMENTIONED MCV GRAZE OR TRACK ACROSS NORTHERN PORTIONS OF CENTRAL NC THERE MAY BE SUFFICIENT MOISTURE/INSTABILITY TO SUPPORT ISOLD CONVECTION OVERNIGHT...AND THIS WILL BE THE BASIS FOR A 20% CHANCE OF SHOWERS NORTH OF HWY 64 AFTER MIDNIGHT. TEMPERATURES: EXPECT HIGHS TODAY SLIGHTLY ABOVE NORMAL...IN THE MID/UPPER 80S TO NEAR 90F. LOWS TONIGHT A FEW DEGREES ABOVE NORMAL DUE TO INCREASING LOW-LEVEL MOISTURE AND PERHAPS MID/UPPER LEVEL CLOUD COVER...IN THE UPPER 60S TO NEAR 70F. SEVERE POTENTIAL: A VERY SMALL (ALBEIT CONDITIONAL) THREAT OF AN ISOLD SEVERE DOWNBURST EXISTS IN THE FAR W/NW PIEDMONT LATE THIS AFT/EVE WHERE MODERATE INSTABILITY (1500-2000 J/KG) AND MODERATE DCAPE (1000 J/KG) ARE PRESENT IN ADVANCE OF THE MCS /COLD POOL/ APPROACHING THE NORTHWEST NC MOUNTAINS. CONFIDENCE IS LOW WITH REGARD TO HOW THE AFOREMENTIONED COLD POOL WILL EVOLVE AND WHETHER OR NOT IT WILL AFFECT THE NW PIEDMONT IN VICINITY OF PEAK HEATING...AND HAVE OPTED TO LEAVE OUT ANY MENTION OF SVR WX IN THE HWO. -VINCENT && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... AS OF 215 PM SATURDAY... CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000 J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW... THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40% CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY... PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 255 PM SATURDAY... THE LONG TERM WILL BE CHARACTERIZED BY A FAIRLY STAGNANT UPPER LEVEL PATTERN CONSISTING OF STRONG HIGH PRESSURE OVER THE SOUTHWESTERN UNITED STATES AND A NEAR STATIONARY UPPER LEVEL TROUGH OVER THE EAST COAST. THE FIRST HALF OF THE LONG TERM WILL SEE A SLOW DEEPENING OF THE TROUGH THROUGH WEDNESDAY BEFORE A GRADUAL LIFTING FOR THE END OF THE WEEK AND INTO THE WEEKEND. AT THE SURFACE A LOW PRESSURE SYSTEM OVER THE NORTHERN GREAT LAKES WILL TRACK VERY SLOWLY EASTWARD THROUGH SOUTHERN QUEBEC WITH A COUPLE OF ASSOCIATED COLD FRONTS STRETCHED ACROSS THE EASTERN CONUS. EARLY IN THE PERIOD THE BERMUDA HIGH WILL HELP TRANSPORT MOISTURE OUT OF THE GULF OF MEXICO AND CARIBBEAN SEA INTO THE SOUTHEASTERN US BEFORE IT MOVES FURTHER OUT TO SEA...HELPING TO DRY CONDITIONS OUT BY THE END OF THE WEEK. MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW 90S...LOWS UPPER 70S. ALTHOUGH THERE IS SOME DISCREPANCIES IN MODEL TIMING AND LOCATION...THE NEWEST RUN OF THE GFS SUGGESTS THE FRONT WILL BE SOMEWHERE IN BETWEEN RALEIGH AND FAYETTEVILLE BY PEAK HEATING AND WHILE ISOLATED TO SCATTERED CONVECTION CANT BE RULED OUT IN THE EXTREME SOUTHEAST IT LOOKS LIKE A MUCH DRIER AIRMASS WILL TAKE OVER MOST OF THE CWA WITH VERY LIMITED INSTABILITY AND SHEAR. COOLER AND DRIER CONDITIONS WILL BEGIN TO FILTER INTO THE AREA...HIGHS MID TO UPPER 80S. LOWS LOWER 60S NW TO UPPER 60S SE. WEDNESDAY THROUGH FRIDAY SHOULD REMAIN QUIET AS SURFACE HIGH PRESSURE OVER THE OHIO VALLEY KEEPS THE COLD FRONT EAST OF THE AREA. A SUPPORTING MIGRATORY HIGH DROPPING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS WILL HELP TO PROPEL A SECONDARY COLD FRONT THROUGH THE REGION THAT WILL REINFORCE DRY CONDITIONS THROUGH AT LEAST FRIDAY MORNING. MOISTURE SLOWLY INCREASES FRIDAY AFTERNOON AND EASTERLY FLOW OFF THE ATLANTIC COULD HELP AID SOME DIURNAL CONVECTION FRIDAY AFTERNOON...PRIMARILY FOCUSED ON THE SEA BREEZE. SATURDAY WILL FEATURE INCREASED MOISTURE WITH A GREATER CHANCE FOR DIURNAL CONVECTION. HIGHS DURING THIS PERIOD WILL BE LOW TO MID 80S WITH LOWS IN THE LOWER TO MID 60S. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... AS OF 835 PM SATURDAY... 24-HR TAF PERIOD: MOST OF THE AFTERNOON/EARLY EVENING SHOWERS AND STORMS HAVE DISSIPATED THIS EVENING WITH THE LOSS OF DAYTIME HEATING. HOWEVER... A FEW MORE SHOWERS AND/OR STORMS WILL BE POSSIBLE OVER THE NEXT SEVERAL HOURS ALONG ANY REMNANT OUTFLOW BOUNDARIES ACROSS THE NORTHERN PIEDMONT (KGSO/KINT/KRDU). WILL HANDLE THIS THREAT WITH AMENDMENTS. OTHERWISE EXPECT VFR CONDITIONS TO CONTINUE FOR THE REMAINDER OF THIS EVENING INTO THE OVERNIGHT HOURS. WILL CONTINUE TO MENTION A TEMPO GROUP FOR MVFR VISBYS AT ALL SITES FOR THE PRE-DAWN HOURS FOR SUNDAY. HOWEVER... CONFIDENCE IS RATHER LOW GIVEN AN UPPER LEVEL DISTURBANCE CURRENTLY OVER EASTERN KY WILL MOVE INTO OUR REGION AFTER MIDNIGHT (GENERALLY AFTER 06Z). THIS SHOULD AT LEAST SPREAD MID AND HIGH LEVEL CLOUD COVER INTO OUR REGION... WITH POSSIBLY SOME SHOWERS AND STORMS. GIVEN THE NOCTURNAL TIMING WILL NOT MENTION ANY SHOWERS AND STORMS IN THE TAFS AT THIS TIME FOR THE OVERNIGHT (BEST CHANCE NORTHWEST PIEDMONT... KGSO/KINT). EXPECT WE WILL SEE ISOLATED TO SCATTERED SHOWERS AND STORMS DEVELOP SUNDAY AFTERNOON AND EVENING. THINK WE WILL SEE SHOWERS AND STORMS FIRST DEVELOP WHERE THE REMNANT OUTFLOW FROM TODAYS ACTIVITY STALLS THIS EVENING.... CURRENTLY EXPECTED TO RANGE FROM THE SW PIEDMONT TO NE COASTAL PLAIN. THUS... WILL ADD VCTS TO THE TAFS STARTING AT 18Z FOR KRDU/KFAY/KRWI... WITH SHOWERS AND STORMS EXPECTED A BIT LATER IN THE DAY AT KGSO/KINT... AS SHOWERS AND STORMS DEVELOP ACROSS THE HIGHER TERRAIN AND MOVE INTO THE NORTHWEST PIEDMONT. ANY SHOWERS AND STORMS WILL HAVE THE POTENTIAL TO PRODUCE SUB VFR CONDITIONS AND GUSTY WINDS. -BSD LOOKING AHEAD: THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE MON/MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...ELLIS AVIATION...BSD/VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 205 AM FRIDAY... OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST. THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 245 AM FRIDAY... IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG (GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20 KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 300 AM FRIDAY... THE PATTERN FOR THE LONG TERM PORTION OF THE FORECAST WILL CONTINUE TO FEATURE A STRONG RIDGE ACROSS THE ROCKY MOUNTAIN STATES AND AN AMPLIFYING EASTERN U.S./CANADA TROUGH DURING THE MID TO LATE WORK WEEK. SUNDAY WILL FEATURE INCREASING DEEP LEVEL MOISTURE AS PRECIPITABLE WATER VALUES INCREASE FROM AROUND 1.25 INCHES ON SATURDAY MORNING TO BETWEEN 1.9 AND 2.0 INCHES ON SUNDAY MORNING. THE AIR MASS WILL BE SOMEWHAT UNSTABLE BUT WILL BE LACKING A STRONG FOCUS FOR ASCENT. A WEAKNESS/SHEAR AXIS IN THE MID LEVELS IS EXPECTED TO BE DRIFTING EAST ACROSS THE SOUTHERN MOUNTAINS ON SUNDAY AFTERNOON WHICH WILL SUPPORT SLIGHTLY HIGHER POPS IN THE CHANCE RANGE IN THE WEST. HIGHS SUNDAY WILL BE SLIGHTLY ABOVE NORMAL IN THE UPPER 80S WITH LOWS AROUND 70. THE MAIN WEATHER EVENT OF THE LONGER TERM PERIOD ARRIVES MONDAY AND PERSISTS INTO TUESDAY AS A DIGGING SHORT WAVE TROUGH DIVES INTO THE OHIO VALLEY ON MONDAY. THE SHORTWAVE ASSOCIATED WITH A 70KT JET ALOFT LINGERS ACROSS THE MID ATLANTIC MONDAY NIGHT AND TUESDAY BEFORE ANOTHER DISTURBANCE GIVES THE TROUGH AXIS A PUSH AND MOVES IT EAST OF CENTRAL NC ON TUESDAY. A LEE TOUGH DEVELOPS OVER CENTRAL NC ON MONDAY WHILE THE COLD FRONT MOVES INTO THE REGION ON TUESDAY AFTERNOON AND FINALLY PUSHES TOWARD THE COAST BY AROUND WEDNESDAY MORNING. THE AIR MASS ACROSS CENTRAL NC WILL BE VERY MOIST WITH PW VALUES AROUND 2.0 AND CAPE VALUES WILL CLIMB INTO THE 1500-2500 J/KG RANGE ON MONDAY AFTERNOON ACROSS CENTRAL NC WITH THE INSTABILITY SHIFTING EAST ON TUESDAY AFTERNOON AS A CAPPING INVERSION MOVES INTO THE PIEDMONT. WHILE INSTABILITY IS PRESENT AND MECHANISMS TO INITIATE AND FOCUS CONVECTION ARE IN PLACE...THE WIND FIELD IS RATHER LIMITED WITH BULK SHEAR VALUES PROGGED TO BE AROUND OR A LITTLE LESS THAN 20KS. SO AT THIS POINT EXPECT A PRETTY GOOD COVERAGE OF CONVECTION...MAINLY DURING THE AFTERNOON AND EVENING. SOME OF THE CONVECTION COULD BE STRONG BUT A WIDESPREAD SEVERE WEATHER EVENT ISN`T EXPECTED. WILL INCLUDE HIGH CHANCE POPS DURING THE AFTERNOON AND EVENING PERIODS WITH LINGERING LOW CHANCE POPS OVERNIGHT. THE FOCUS FOR PRECIPITATION...ESPECIALLY THUNDERSTORMS SHIFTS TO THE EAST ON TUESDAY AND HAVE ADJUSTED POPS UPWARD IN THOSE LOCATIONS. HIGHS ON MONDAY WILL RANGE IN THE UPPER 80S AND A JUST A BIT COOLER IN THE MID 80S ON TUESDAY WITH LOWS NEAR 70. THE COLD FRONT IS PROGGED TO REACH THE COAST BY WEDNESDAY MORNING WITH WEAK HIGH PRESSURE OVER THE WESTERN OHIO VALLEY ON WEDNESDAY MORNING SLOWLY BUILDING EAST ON THURSDAY. THIS SHOULD RESULT IN FAIR AND DRY WEATHER WITH COOLER TEMPERATURES. HIGHS WEDNESDAY SHOULD BE IN THE 80-85 RANGE WITH SLIGHTLY WARMER TEMPERATURES ON THURSDAY IN THE LOWER TO MID 80S. MORNING LOWS WILL RANGE IN THE LOWER TO MID 60S. -BLAES && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 1245 AM FRIDAY... CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING. SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING. MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z... REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z. HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY WEATHER TODAY. LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING (09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...BLAES AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
245 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 205 AM FRIDAY... OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST. THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 245 AM FRIDAY... IT STILL APPEARS THAT SATURDAY WILL REMAIN DRY FOR MOST OF CENTRAL NC. A SHORTWAVE TROUGH THAT CROSSES THE NRN GREAT LAKES THIS AFTERNOON IS EXPECTED TO DAMPEN AS IT TRACKS ESE (AND INTO THE LIGHTER STEERING FLOW) TOWARD THE CENTRAL/SRN APPALACHIANS BY SAT MORNING. THIS FEATURE IS LIKELY TO CONTRIBUTE TO OVERALL INCREASE IN EXTENT AND DEPTH OF MOISTURE OVER THE MOUNTAINS... ALTHOUGH THE DYNAMIC FORCING FOR ASCENT SHOULD REMAIN QUITE WEAK. AS THIS WAVE TRACKS INTO THE NORTHEAST STATES STRETCHING INTO WV/VA LATE SAT INTO SAT NIGHT... A VERY WEAK LONGWAVE TROUGH FORMS OVER THE EASTERN CONUS... WHICH SHOULD LEAD TO INCREASED CLOUDINESS EAST OF THE MOUNTAINS BUT LITTLE ELSE. MODELS DEPICT MINIMAL INSTABILITY OVER MUCH OF CENTRAL/ERN NC WITH AFTERNOON MLCAPE VALUES UNDER 1000 J/KG (GFS SHOWS VALUES AT OR ABOVE 2000 J/KG JUST TO OUR WEST OVER THE MOUNTAINS/FOOTHILLS)... AND DEEP LAYER SHEAR WILL PEAK AT JUST 15-20 KTS AT MOST. WILL MENTION AN ISOLATED SHOWER OR STORM OVER THE WRN CWA (FAR WRN PIEDMONT) SAT AFTERNOON INTO THE EVENING. MODELS SHOW PW VALUES OF 1.8-2.0 INCHES STREAMING FROM THE MOUNTAINS INTO CENTRAL NC SAT NIGHT... AND FORECAST SOUNDINGS SHOW A STEADY DEEP MOISTENING OVERNIGHT ESPECIALLY OVER THE WRN PIEDMONT. WILL RETAIN A LOW CHANCE OF A SHOWER IN THIS AREA OVERNIGHT... ALTHOUGH THE LACK OF MECHANISMS TO INSTIGATE LIFT SUPPORTS MOST OF THE AREA STAYING DRY... ESPECIALLY FROM THE TRIANGLE EAST. HIGHS 85-90. LOWS 68-72. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 235 PM THURSDAY... SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90. MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE... 84 NORTHWEST TO 88 SOUTHEAST. WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A BIT ON THURSDAY...MOSTLY MID 80S. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 1245 AM FRIDAY... CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING. SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING. MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z... REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z. HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY WEATHER TODAY. LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING (09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...MLM AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 205 AM FRIDAY... OBSERVATIONS AND MODEL DATA ALL SUPPORT A QUIET AND GENERALLY DRY DAY WITH PLENTY OF SUNSHINE. THE LATEST SURFACE MAP SHOWS THE WEAK SURFACE FRONT STRETCHING ACROSS SC AND SW NC... WITH SURFACE HIGH PRESSURE NOSING IN FROM THE NE... WHILE NNW MID LEVEL FLOW AND DEEP LAYER SUBSIDENCE PERSISTS OVER THE REGION. EXPECT A SMATTERING OF SHALLOW LOW CLOUDS THROUGH DAYBREAK ACROSS CENTRAL NC... AS THE LACK OF HIGHER-LEVEL MOISTURE/CLOUDS AND LIGHT EASTERLY FLOW HAS ALLOWED FOR GOOD RADIATIONAL COOLING... WHILE HIGH DEW POINTS HOLD ON NEAR THE SURFACE. THESE CLOUDS SHOULD MIX OUT AND DISSIPATE QUICKLY WITH THE ONSET OF SURFACE HEATING. FORECAST SOUNDINGS SUGGESTS THAT THERE WILL BE ENOUGH MOISTURE SUPPRESSED BENEATH THE WARM/STABLE LAYER ALOFT TO SUPPORT SCATTERED FLAT DAYTIME CUMULUS... MORE NUMEROUS OVER THE COASTAL PLAIN AS LOWER LEVEL MOISTURE REMAINS BETTER HERE... AND WE MAY SEE SOME OF THE BETTER 850 MB MOISTURE NOTED OVER AND JUST OFF THE NORTHEAST/MIDATLANTIC COAST WORKING SSW INTO ERN NC DURING THE DAY. THE DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS OF 84-89... SO LITTLE CHANGE IS NEEDED FROM THE EARLIER FORECAST. THE SURFACE HIGH CENTER SHIFTS OFF THE VA/NC COAST LATER THIS AFTERNOON THROUGH TONIGHT... RESULTING IN A VEERING OF LIGHT SURFACE FLOW TO BE FROM THE SSE AND SOUTH... WHILE ALOFT... ANTICYCLONIC MID LEVEL FLOW BECOMES LIGHTER AND FLATTENS OUT WITH NO FORCING MECHANISMS EVIDENT. BUT WE SHOULD STILL SEE AN INCREASE IN HIGH THIN CLOUDS AS BLOWOFF FROM ORGANIZED CONVECTION TODAY OVER THE NRN GREAT LAKES ADVECTS INTO THE MIDATLANTIC REGION OVERNIGHT. LOW LEVEL MOISTURE INCREASES AS WELL WITH THE LIGHT ATLANTIC AND GULF SOURCE INFLOW... AND EXPECT PATCHY FOG AND A FEW LOW STRATUS CLOUDS TO FORM ONCE AGAIN LATE TONIGHT. LOWS 65-69. -GIH && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 230 PM THURSDAY... TO BE UPDATED SHORTLY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 235 PM THURSDAY... SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90. MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE... 84 NORTHWEST TO 88 SOUTHEAST. WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A BIT ON THURSDAY...MOSTLY MID 80S. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 1245 AM FRIDAY... CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING. SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING. MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z... REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z. HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY WEATHER TODAY. LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING (09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...HARTFIELD SHORT TERM... LONG TERM...MLM AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1250 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY. && .NEAR TERM /OVERNIGHT/... AS OF 815 PM THURSDAY... OVERVIEW: NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/ ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC. PRECIPITATION CHANCES: ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY DIFFLUENT FLOW ALOFT. TEMPERATURES: LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO NEAR 70F FAR S/SW. -VINCENT && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 230 PM THURSDAY... QUIET WEATHER-WISE. WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S. SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT. SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 235 PM THURSDAY... SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90. MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE... 84 NORTHWEST TO 88 SOUTHEAST. WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A BIT ON THURSDAY...MOSTLY MID 80S. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 1245 AM FRIDAY... CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING. SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING. MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z... REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z. HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY WEATHER TODAY. LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING (09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...VINCENT SHORT TERM...CBL LONG TERM...MLM AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1245 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC WILL EXTEND INTO OUR REGION THROUGH TONIGHT. AN INCREASINGLY MOIST SOUTHERLY FLOW WILL DEVELOP ON SATURDAY AND PERSIST THROUGH MONDAY. A COLD FRONT WILL CROSS THE REGION MONDAY NIGHT AND EARLY TUESDAY. && .NEAR TERM /OVERNIGHT/... AS OF 815 PM THURSDAY... OVERVIEW: NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE OVER THE CENTRAL PLAINS/ ROCKIES AND AN H5 TROUGH OFFSHORE THE EASTERN SEABOARD. SFC HIGH PRESSURE WILL STRENGTHEN OVER THE MID-ATLANTIC...WITH INCREASINGLY NORTHEAST LOW-LEVEL FLOW OVER CENTRAL NC. PRECIPITATION CHANCES: ASIDE FROM A CHANCE FOR ISOLD LOW-TOPPED CONVECTION WEST OF A LINE FROM FAY-RDU-HNZ THROUGH MIDNIGHT...EXPECT NO ADDITIONAL POTENTIAL FOR PRECIPITATION AS A DRIER AIRMASS ADVECTS INTO THE REGION FROM THE EAST/ENE AND SUBSIDENCE STRENGTHENS IN ASSOC/W INCREASINGLY DIFFLUENT FLOW ALOFT. TEMPERATURES: LOWS WILL PRIMARILY DEPEND ON CLOUD COVER AND THE ADVECTION OF A COOLER MARITIME AIRMASS INTO THE REGION VIA NORTHEAST FLOW IN THE LOWER LEVELS. EXPECT LOWS RANGING FROM THE MID/UPPER 60S N/NE TO NEAR 70F FAR S/SW. -VINCENT && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 230 PM THURSDAY... QUIET WEATHER-WISE. WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FRIDAY MORNING...WHILE CONTINUED NWLY FLOW ALOFT LOOKS TO BE VOID OF ANY SHORTWAVE DISTURBANCES. BELOW NORMAL PWATS OF AROUND 1.0" WITH CAPPING ALOFT WILL RESULT IN DRY CONDITIONS WITH AMPLE SUNSHINE SUPPORTING SEASONABLE TEMPERATURES IN THE MID TO UPPER 80S. SURFACE HIGH WILL THEN SHIFT OFFSHORE FRIDAY EVENING WITH SURFACE WINDS VEERING TO EAST-SOUTHEASTERLY FRIDAY NIGHT. SIGNALS ARE MIXED ON WHETHER WE WILL SEE FOG...STRATUS...OR A MIX OF BOTH. LOWS IN THE MID 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 235 PM THURSDAY... SIGNIFICANT AMPLIFICATION IN THE LONGWAVE PATTERN OVER NOAM THROUGH THE EXTENDED FORECAST PERIOD WILL RESULT IN A PROGRESSIVE TROF MOVING ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SATURDAY AND SUNDAY...WILL SEE INCREASING MOISTURE AS RETURN FLOW DEVELOPS AND STRENGTHENS OVER THE WEEKEND. INITIAL WESTERLY LOW LEVEL FLOW WILL PROMOTE DEVELOPMENT OF LEE TROFFING SATURDAY WITH SMALL CHANCES OF CONVECTION...MAINLY IN THE WEST WHERE SURFACE TROF INFLUENCE AND DIFFERENTIAL HEATING ON THE SLOPES AND SUBSEQUENT MIGRATION OF CELLS EAST WILL BE THE MAJOR INFLUENCES. WILL HAVE A BETTER CHANCE OF CONVECTION...WITH A LATE DAY/DIURNAL INFLUENCE...ON SUNDAY AS BOTH THE GFS AND ECMWF INDICATE A SHORT WAVE GRAZING THE AREA AS IT ROUNDS THE UPPER TROF. HIGHS BOTH DAYS WILL BE MAINLY 85-90. MONDAY AND TUESDAY...PW`S WILL BE ON THE ORDER OF 2 INCHES AND THE EAST COAST TROF AXIS WILL BE JUST WEST OF THE AREA ON MONDAY WITH A 70KT UPPER JETLET LIFTING NORTH UP THE EASTERN RIM OF THE TROF TO ADD SOME UPPER DIFFLUENCE TO ENHANCE CONVECTION. SEEING SOME CONVECTIVE FEEDBACK PROBLEMS IN THE GFS VORTICITY FIELDS WHICH DIMINISHES CONFIDENCE ENOUGH TO PREVENT ME FROM INCREASING POPS TO LIKELY AT THIS POINT. HIGHS MONDAY WILL BE SIMILAR TO THE WEEKEND WITH NO AIRMASS CHANGE...85 TO 90...PERHAPS A SHADE LOWER IF CLOUD AND SHOWER COVERAGE ARE MORE SIGNIFICANT EARLY IN THE DAY. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL BE MERGING INTO THE PERSISTENT LEE TROF MONDAY NIGHT AND PROGRESSING SLOWLY EAST ACROSS THE AREA TUESDAY. WILL HAVE CHANCE POPS FOR MAINLY SHOWERS OVERNIGHT AND TUESDAY MORNING...WITH BETTER CHANCES OF THUNDER ON TUESDAY AFTERNOON/EVENING...ESPECIALLY IN THE EAST. COOL AIR ADVECTION WILL BE DELAYED UNTIL TUESDAY NIGHT...AND HIGHS TUESDAY WILL BE MAINLY TEMPERED A BIT BY HEAVY CLOUD AND MORE WIDESPREAD SHOWER COVERAGE... 84 NORTHWEST TO 88 SOUTHEAST. WEDNESDAY AND THURSDAY...SURFACE FRONT WILL BE ALONG THE COAST TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE MIDWEST ON WEDNESDAY. WILL HAVE CLEARING SKIES AND A COOLER AIRMASS IN PLACE...HIGHS WEDNESDAY WILL BE IN THE 80-85 RANGE AFTER A MORNING LOW IN THE LOW-MID 60S. MAINLY CLEAR WITH INSOLATION WARMING US A BIT ON THURSDAY...MOSTLY MID 80S. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 1245 AM FRIDAY... CONFIDENCE IN THE DEVELOPMENT OF ADVERSE AVIATION CONDITIONS AS WE APPROACH DAYBREAK THIS MORNING REMAINS AVERAGE BUT IS INCREASING. SCATTERED SHOWERS AND STORMS HAVE HELD WELL WEST OF CENTRAL NC OVER THE LAST SEVERAL HOURS -- OVER THE MOUNTAINS/FOOTHILLS -- AND WILL REMAIN WEST OF INT/GSO AS THEY WEAKEN/DISSIPATE EARLY THIS MORNING. MVFR CLOUDS HAVE ALREADY FORMED OVER THE CENTRAL NC COASTAL SECTIONS AND ARE SLOWLY CREEPING WESTWARD... EXPECTED TO PUSH INTO THE FAY/RWI AREAS AFTER 07Z. MEANWHILE... MVFR AND IFR CIGS ARE ALREADY STARTING TO FORM OVER SOUTH CENTRAL VA... AND THE HRRR MODEL SHOWS IFR CLOUDS EXPANDING SOUTHWARD INTO INT/GSO/RDU AFTER 09Z... REASONABLE CONSIDERING THE LINGERING HIGH NEAR-SURFACE RH AND LIGHT SURFACE WINDS FROM THE NE (FAVORING MORE STRATUS THAN FOG). THE MVFR TO IFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 13Z... LIFTING UP TO MAINLY MVFR CIGS AREAWIDE BRIEFLY BEFORE BECOMING VFR BY 15Z. HIGH CONFIDENCE IN VFR CONDITIONS AFTER 15Z THIS MORNING THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY SAT MORNING) AS SURFACE HIGH PRESSURE SITS OVER THE REGION... BRINGING PLENTY OF SUNSHINE AND DRY WEATHER TODAY. LOOKING BEYOND 06Z EARLY SAT MORNING: WE MAY SEE REDEVELOPMENT OF IFR CIGS ESPECIALLY AT INT/GSO LATE TONIGHT INTO SATURDAY MORNING (09Z-13Z) AS SURFACE WINDS BECOME SOUTHERLY AND BRING IN GREATER MOISTURE FROM THE SOUTH. BRIEF SHALLOW IFR CLOUDS WILL BE POSSIBLE EARLY SUNDAY AND MONDAY MORNINGS AS WELL... WITH MAINLY VFR CONDIIONS DURING THE DAY. ISOLATED SHOWERS/STORMS ARE POSSIBLE SAT AFTERNOON WITH A LITTLE MORE COVERAGE EXPECTED SUNDAY. NUMEROUS SHOWERS/STORMS AND ATTENDANT SUB-VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY IN ASSOCIATION WITH AN INCOMING COLD FRONT AND STRENGTHENING MID LEVEL TROUGH OVER THE EASTERN U.S. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...VINCENT SHORT TERM...CBL LONG TERM...MLM AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
955 PM CDT SAT AUG 31 2013 .UPDATE... ISSUED AT 954 PM CDT SAT AUG 31 2013 CLEAR SKIES ACROSS ALL BUT THE FAR NORTHWEST THIS EVENING WITH DIMINISHING NORTH TO NORTHWEST WINDS. EXTENSIVE CLOUD COVER ACROSS SOUTHERN SASKATCHEWAN AND MANITOBA IS PUSHING SOUTH AND IS EXPECTED TO DROP SOUTH ACROSS WESTERN AND CENTRAL NORTH DAKOTA LATE TONIGHT. LATEST 01 SEP 00Z NAM AND RUC GUIDANCE SUGGESTS HIGHEST 925-850MB RH SHOULD CONTINUE TO PUSH SOUTH THROUGH EASTERN PORTIONS OF THE CWA...BUT LINGER IN THE WEST...MAINLY FROM ISN TO BETWEEN BISMARCK AND DICKINSON ON THE BACK SIDE OF THE SURFACE HIGH. ADJUSTED CLOUD COVER BASED ON LATEST LOW LEVEL RH GUIDANCE. OTHERWISE A QUIET NIGHT WITH DIMINISHING WINDS AND COMFORTABLE TEMPERATURES MAINLY IN THE 50S. UPDATE ISSUED AT 638 PM CDT SAT AUG 31 2013 MUCH COOLER AIR BEHIND AN EXITING COLD FRONT WILL CONTINUE TO SPILL ACROSS WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. AN UPPER LEVEL LOW ACROSS MANITOBA HAS MOVED FAR ENOUGH EAST THAT EARLY EVENING SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL. OTHER THAN REMOVING POPS NORTH CENTRAL AND MINOR CLOUD COVER ADJUSTMENTS...THE CURRENT FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 250 PM CDT SAT AUG 31 2013 DRIER AND COOLER AIR WILL HIGHLIGHT THE SHORT TERM FORECAST. AS OF 20 UTC...THE COLD FRONT HAS CLEARED THE CWA WITH LOW LEVEL DRY AND COLD AIR ADVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA AND WIDESPREAD WIND GUSTS OF 25-30 KTS IN POST FRONTAL MIXING. DID ADD A MENTION OF ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL THIS AFTERNOON AND EARLY EVENING WITH THE UPPER LEVEL LOW THAT IS PROPAGATING SOUTHEAST OUT OF FAR SOUTHEAST SASKATCHEWAN. ANY CONVECTION THAT DOES FORM WILL FADE WITH SUNSET. AN EXPANSE OF STRATUS IS EXPECTED TO OVERSPREAD AREAS ALONG AND NORTH OF I-94 TONIGHT...WHICH WILL HELP TO KEEP OVERNIGHT LOWS IN THE 50S. A QUIET A REFRESHINGLY COOL DAY IS EXPECTED SUNDAY WITH HIGHS IN THE 70S WITH HIGH PRESSURE IN PLACE. GIVEN GOOD AGREEMENT...A BLEND OF THE 12 UTC GUIDANCE SUITE WAS USED FOR ALL FIELDS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 250 PM CDT SAT AUG 31 2013 AFTER A COOL AND DRY SUNDAY...WILL SEE A WARMING TREND BACK TO ABOVE NORMAL TEMPERATURES THROUGH THE COMING WORK WEEK AS THE CENTRAL U.S. UPPER RIDGE REBUILDS/AMPLIFIES FROM ACROSS THE ROCKIES NORTH INTO THE CANADIAN HIGH PLAINS...BRINGING WAA BACK EAST INTO THE DAKOTAS. EXPECT MOSTLY DRY CONDITIONS OVER NORTH DAKOTA THROUGH THURSDAY NIGHT WITH A DRY NORTHWEST FLOW ALOFT. THE EXCEPTION MAY BE THE TUESDAY AFTERNOON THROUGH WEDNESDAY NIGHT PERIOD WHEN MODELS PROJECT AN EMBEDDED S/WV IMPULSE MOVING THROUGH THE RIDGE FROM ACROSS SOUTHERN MONTANA EAST INTO THE DAKOTAS. HAVE CONFINED SLIGHT CHANCE POPS FOR NOW TUESDAY NIGHT THROUGH WED NIGHT. THE LATEST ECMWF (12Z) NOW BRINGS THIS FEATURE TO THE ND/MT BORDER BY 00Z WED...SO FUTURE UPDATED FORECASTS MAY NEED TO ADD SOME MENTION OF THUNDERSTORMS STARTING TUESDAY AFTERNOON ACROSS THE WEST. AS WE HEAD INTO THE LATER PORTIONS OF THE WORK WEEK AND THE FIRST HALF OF NEXT WEEKEND...MODELS PROJECT THE RIDGE TO BREAKDOWN AS A CLOSED UPPER LOW (NOW OFF THE NORTHWEST U.S. COAST) MOVES INLAND SOMETIME THURSDAY NIGHT OR FRIDAY...THEN EAST TOWARDS THE NORTHERN PLAINS SOMETIME FRI-SUN. LATEST GFS/ECMWF DIFFER ON THE TIMING OF THIS FEATURE...SO LOTS OF UNCERTAINTY STILL IN PLAY. EVENTUALLY THIS FEATURE WILL BE THE FOCUS OF LATER FORECASTS AS IT IS EXPECTED TO BRING COOLER WEATHER AND INCREASED CHANCES FOR PRECIPITATION TO OUR REGION. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 954 PM CDT SAT AUG 31 2013 LATEST GUIDANCE IS STILL SUGGESTING LOW VFR TO MVFR CEILINGS DROPPING SOUTH INTO THE FORECAST AREA LATE TONIGHT AND SUNDAY MORNING. THEN IMPROVING CEILINGS LATE SUNDAY MORNING WITH A NORTH FLOW SHIFTING EAST ACROSS THE WEST SUNDAY AFTERNOON. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...AYD LONG TERM...NH AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1258 PM CDT FRI AUG 30 2013 .UPDATE... ISSUED AT 1258 PM CDT FRI AUG 30 2013 NO SIGNIFICANT CHANGES WITH THIS FORECAST UPDATE. THE THINKING REMAINS UNCHANGED FROM THE 1021 AM CDT UPDATE BELOW REGARDING EXPECTED CONVECTION. THIS IS CONFIRMED BY THE 16 UTC HRRR AND 12 UTC 4 KM WRF. UPDATE ISSUED AT 1021 AM CDT FRI AUG 30 2013 CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE 15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS THE AREA. THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83 BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A LOCALIZED THREAT FOR TORNADOES. UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013 QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS AND WEBCAMS. UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013 UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83 CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST TONIGHT...SOME POSSIBLY SEVERE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 335 AM CDT FRI AUG 30 2013 CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA. AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND SOUTH CENTRAL SASKATCHEWAN. THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA. FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT. ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS TONIGHT IN THE 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 335 AM CDT FRI AUG 30 2013 ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1258 PM CDT FRI AUG 30 2013 VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST THROUGH THE EVENING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1022 AM CDT FRI AUG 30 2013 .UPDATE... ISSUED AT 1021 AM CDT FRI AUG 30 2013 CANCELLED THE DENSE FOG ADVISORY FOR CENTRAL NORTH DAKOTA AS THE 15 UTC OBSERVATIONS AND WEBCAMS SHOW ALL FOG HAS BURNED OFF ACROSS THE AREA. THE FOCUS REMAINS ON SEVERE CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND INTO THE EVENING. THE 13 UTC HRRR CONTINUES THE TREND SUPPORTED BY THE 00 UTC 4 KM WRF AND SPC SSEO OF INITIATING CONVECTION ALONG THE PRE-FRONTAL TROUGH BETWEEN HIGHWAY 85 AND 83 BETWEEN 20-22 UTC. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A LOCALIZED THREAT FOR TORNADOES. UPDATE ISSUED AT 714 AM CDT FRI AUG 30 2013 QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR MUCH OF CENTRAL NORTH DAKOTA GIVEN THE 12 UTC FOG CHANNEL...SURFACE OBSERVATIONS AND WEBCAMS. UPDATE ISSUED AT 624 AM CDT FRI AUG 30 2013 UPDATE TO ADD AREAS OF DENSE FOG FROM HARVEY THROUGH JAMESTOWN...AND PATCHY DENSE FOG WESTWARD THROUGH THE HIGHWAY 83 CORRIDOR. DENSE FOG NOT CONSIDERED WIDESPREAD ENOUGH FOR ADVISORY AT THIS TIME. OTHERWISE...CURRENT FORECAST IN GOOD SHAPE. SCATTERED THUNDERSTORMS EXPECTED WEST THIS AFTERNOON...SPREADING EAST TONIGHT...SOME POSSIBLY SEVERE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 335 AM CDT FRI AUG 30 2013 CURRENTLY...SURFACE HIGH PRESSURE EXTENDED FROM MANITOBA SOUTHWARD ACROSS CENTRAL NORTH DAKOTA INTO WESTERN SOUTH DAKOTA. A SURFACE FRONT EXTENDED FROM A LOW OVER SOUTHERN ALBERTA TO CENTRAL MONTANA. AT UPPER LEVELS...A SHORTWAVE EXTENDED FROM NORTHERN ALBERTA/SASKATCHEWAN SOUTHWARD ACROSS CENTRAL MONTANA. THIS UPPER LEVEL SHORTWAVE FEATURE WAS ASSOCIATED WITH A SCATTERED LINE OF SHOWERS AND THUNDERSTORMS MOVING EASTWARD ACROSS CENTRAL MONTANA AND SOUTH CENTRAL SASKATCHEWAN. THE LATEST MODEL RUNS DEPICT THE UPPER LEVEL SHORTWAVE LIFTING NORTHEASTWARD THIS MORNING SUCH THAT THE STRONGER FORCING REMAINS NORTH OF THE CANADIAN BORDER AFTER DAYBREAK. HOWEVER THIS AFTERNOON THE SHORTWAVE GAINS STRENGTH AND DEVELOPS SOUTHWARD ACROSS WESTERN/CENTRAL NORTH DAKOTA...MOVING EAST INTO THE RED RIVER VALLEY LATE THIS EVENING. IN RESPONSE...THE SURFACE FRONT IS FORECAST TO MOVE INTO WESTERN NORTH DAKOTA LATE THIS AFTERNOON AND PROGRESS EASTWARD SLOWLY...BEFORE STALLING OVER CENTRAL NORTH DAKOTA. FORECAST CAPE VALUES OF 1000 TO OVER 2000 ARE FORECAST OVER WESTERN AND CENTRAL NORTH DAKOTA THIS AFTERNOON...COMBINED WITH 0-6KM BULK SHEAR VALUES OF 35 TO 50 KNOTS. THE LARGE AMOUNT OF AVAILABLE CONVECTIVE ENERGY...ALONG WITH THE STRONG SHEAR...SUGGESTS THUNDERSTORMS COULD REACH SEVERE LIMITS. THUS THE STORM PREDICTION CENTER HAS PLACED MOST OF THE FORECAST AREA IS IN A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THIS AFTERNOON AND TONIGHT. ANOTHER VERY WARM DAY TODAY WITH HIGHS PROGGED TO BE IN THE MID TO UPPER 80S FROM THE NORTH THROUGH THE JAMES RIVER VALLEY...AND INTO THE LOWER 90S ALONG AND SOUTH/WEST OF THE MISSOURI RIVER. LOWS TONIGHT IN THE 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 335 AM CDT FRI AUG 30 2013 ON SATURDAY...THUNDERSTORMS ARE EXPECTED TO LINGER...ESPECIALLY SOUTHEAST IN THE VICINITY OF A COLD FRONT. THE EXTREME SOUTHEAST WILL LIKELY BE ON THE FRINGE OF THE MOST FAVORABLE AREA FOR ISOLATED SEVERE STORMS. DRIER AIR WILL PUSH INTO THE SOUTHWEST...DROPPING DEWPOINTS INTO THE 40S AND MINIMUM AFTERNOON RH BETWEEN 25-30 PERCENT. THE GRASSLAND FIRE DANGER INDEX IS FORECAST TO BE IN THE HIGH CATEGORY. THE CHANCE OF ADDITIONAL RAIN BEYOND SATURDAY IS LOW. SUNDAY WILL LIKELY BE THE COOLEST DAY OF THE WEEK...WITH HIGHS MAINLY IN THE 70S. A WARMING TREND WILL BEGIN ON LABOR DAY...WITH HIGHS FROM THE UPPER 70S EAST TO MID 80S WEST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 182 SATURDAY) ISSUED AT 1021 AM CDT FRI AUG 30 2013 VFR CONDITIONS OUTSIDE OF THUNDERSTORMS ARE EXPECTED FOR THE UPCOMING 18 UTC TAFS. SCATTERED THUNDERSTORMS ARE EXPECTED TO INITIATE BETWEEN THE WESTERN TAF SITES OF KISN/KDIK AND THE CENTRAL SITES OF KMOT/KBIS BETWEEN 20-22 UTC...AND MOVE EAST THROUGH THE EVENING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
918 AM CDT FRI AUG 30 2013 .UPDATE... ISSUED AT 917 AM CDT FRI AUG 30 2013 VISIBILITIES OUTSIDE OF THE CENTRAL AND NORTHERN RED RIVER VALLEY HAVE BEGUN TO RAPIDLY INCREASE. I WILL EXTEND THE DENSE FOG ADVISORY FROM HILLSBORO NORTH TO THE CANADIAN BORDER AND ALLOW OTHER COUNTIES TO EXPIRE AT 9 AM CDT. WILL NEED TO FINE TUNE SKY AND TEMP TRENDS PRIOR TO ANOTHER GRID/ZONE FORECAST AT 10 AM CDT. UPDATE ISSUED AT 710 AM CDT FRI AUG 30 2013 VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE FOG ADVISORY. UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013 OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED. UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013 ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT STILL A GOOD IDEA TO HEIGHTEN AWARENESS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT NOT QUITE AS WARM AS PREVIOUS DAYS. LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY. WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR WILL BE STRONG (FAVORABLE FOR SEVERE STORMS). .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER (EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES. MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 635 AM CDT FRI AUG 30 2013 DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF NEEDED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NDZ008-016- 027-030. MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ001-002- 004-007. && $$ UPDATE...SPEICHER SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
710 AM CDT FRI AUG 30 2013 .UPDATE... ISSUED AT 710 AM CDT FRI AUG 30 2013 VSBY AT THE OBSERVATION SITE IN VALLEY CITY AND FARGO HAS DROPPED TO 1/4SM...AS WELL AS JAMESTOWN. WILL ADD THIS AREA TO THE DENSE FOG ADVISORY. UPDATE ISSUED AT 635 AM CDT FRI AUG 30 2013 OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED. UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013 ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT STILL A GOOD IDEA TO HEIGHTEN AWARENESS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT NOT QUITE AS WARM AS PREVIOUS DAYS. LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY. WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR WILL BE STRONG (FAVORABLE FOR SEVERE STORMS). .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER (EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES. MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 635 AM CDT FRI AUG 30 2013 DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF NEEDED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008- 014>016-024-026>030-038-039-054. MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001>009- 013>016. && $$ UPDATE...TG SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
635 AM CDT FRI AUG 30 2013 .UPDATE... ISSUED AT 635 AM CDT FRI AUG 30 2013 OTHER THAN THE FOG...SKY WILL BE A CHALLENGE THIS MORNING. LOW STRATUS HAS DEVELOPED OR MOVED INTO THE EASTERN FA. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL BREAK APART RATHER QUICKLY THIS MORNING. MUCH OF THIS IS LIKELY THIN...SO WILL GO WITH THIS THINKING. UPDATED THE SKY GRIDS ACCORDINGLY. IF THIS THINKING IS CORRECT THAN MAX TEMPS WILL NOT BE AFFECTED. UPDATE ISSUED AT 606 AM CDT FRI AUG 30 2013 ISSUED A DENSE FOG ADVISORY FOR A FEW HOURS THIS MORNING. THE FOG IS REALLY THICK LOCALLY AT THE OFFICE...AND JUDGING FROM OBSERVATIONS SIMILAR CONDITIONS LIKELY EXIST ELSEWHERE ACROSS THE NORTHERN FA. COVERAGE MAY BE MORE AREAS THAN WIDESPREAD...BUT STILL A GOOD IDEA TO HEIGHTEN AWARENESS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 THE MAIN CHALLENGE WILL BE THUNDER AND SEVERE POTENTIAL TONIGHT AND SATURDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL VALUES...BUT NOT QUITE AS WARM AS PREVIOUS DAYS. LOW LEVEL RIDGING WILL MOVE ACROSS THE REGION TODAY. THERE WILL BE PATCHY DENSE FOG THIS MORNING FOR LOCATIONS THAT RECEIVED RAINFALL YESTERDAY...AND WILL NEED TO MONITOR EXTEND FOR POSSIBLE ADVISORY. WATER VAPOR IMAGERY INDICATES A COUPLE SHORTWAVES UPSTREAM. THE STRONGEST WAVE IS JUST NOW CRASHING ONSHORE ACROSS THE PACIFIC NW...AND WILL TRACK NEAR THE INTERNATIONAL BORDER...PASSING THIS REGION ON SATURDAY. THE NAM IS SLIGHTLY SLOWER THAN THE GEM/GFS/ECMWF...BUT HAS A SIMILAR IDEA. THERE WILL BE STORMS THIS AFTERNOON ACROSS WESTERN/CENTRAL NORTH DAKOTA WITHIN AN AXIS OF MOISTURE AHEAD OF A LOW LEVEL TROUGH. THIS FEATURE WILL MOVE INTO THE FA TONIGHT. ALTHOUGH THUNDERSTORMS ARE EXPECTED...INSTABILITY SHOULD WEAKEN ENOUGH THAT THE POTENTIAL FOR SEVERE STORMS WILL BE LIMITED (INSTABILITY IS MUCH WEAKER THAN LAST NIGHT). WOULD NOT BE SURPRISED TO SEE SOME STRONGER STORMS ENTER THE DEVILS LAKE BASIN LATER THIS EVENING...AND WEAKEN AS THEY MOVE INTO THE VALLEY. THE MAIN COLD FRONT WILL MOVE THROUGH ON SATURDAY...WITH THUNDERSTORMS AGAIN POSSIBLE. STILL NOT EXACTLY SURE ABOUT TIMING...AND INSTABILITY VALUES AHEAD OF THIS FEATURE. THESE TWO FACTORS WILL HAVE THE MOST INFLUENCE ON SEVERE POTENTIAL AS DEEP LAYER SHEAR WILL BE STRONG (FAVORABLE FOR SEVERE STORMS). .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 343 AM CDT FRI AUG 30 2013 SATURDAY NIGHT-SUNDAY NIGHT...REGION WILL BE WITHIN A COOLER AIRMASS FOLLOWING THE PASSAGE OF THE COLD FRONT. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE REGION. ANTICIPATE DRY WEATHER (EXCEPT FOR A PORTION OF NW MN WHICH MAY BE WITHIN THE TRACK OF ANOTHER SHORTWAVE WITHIN THE NW FLOW ALOFT) WITH TEMPERATURES NEAR OR EVEN SLIGHTLY BELOW NORMAL VALUES. MONDAY-THURSDAY...00 UTC GFS/ECMWF SHOW 500 HPA RIDGE AXIS MAINLY ACROSS EASTERN MT AND THE WESTERN DAKOTAS...KEEPING THE FORECAST AREA IN NORTHWEST FLOW ALOFT. MODELS DIFFER GREATLY WITH A CANADIAN TROUGH MID-WEEK WITH THE ECMWF MUCH DEEPER ACROSS THE GREAT LAKES COMPARED TO THE GFS. WITH THE GFS/S TROUGH POSITION FARTHER NORTH...THERE IS A NORTHWARD SURGE OF MOISTURE INTO THE NORTHERN PLAINS ON WEDNESDAY. FOR THIS...ALLBLEND GUIDANCE ADDED SPORADIC 20 POPS ACROSS THE FORECAST AREA. WILL REMOVE ALL POPS FOR NOW GIVEN THE PREVIOUS DRY FORECAST...THE CURRENT PROLONGED DRY-SPELL AND MODEL VARIANCE. BEING ON THE COOLER SIDE OF THE THERMAL AXIS...HIGH TEMPERATURES SHOULD RANGE FROM THE 70S TO LOWER 80S AND NIGHTTIME LOWS FROM THE MID 50S TO LOWER 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 635 AM CDT FRI AUG 30 2013 DENSE FOG AROUND THE REGION WILL DISSIPATE BY MID-MORNING. IN ADDITION...THERE ARE LOW CIGS ALONG AND EAST OF THE RED RIVER VALLEY. 09Z RAP GUIDANCE SUGGESTS THAT THESE CIGS WILL DISSIPATE BY 15Z. WILL GO WITH THIS THINKING...BUT MONITOR AND AMEND IF NEEDED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NDZ006>008- 014>016-024-026>030-054. MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ001- 004>009-013>016. && $$ UPDATE...TG SHORT TERM...TG LONG TERM...TG/ROGERS AVIATION...TG
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
335 PM EDT FRI AUG 30 2013 .SYNOPSIS... LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NWRN PA. RADAR HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NWRN OHIO AND THE LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH LOWS IN THE UPPER 60S. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY. TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD. && .LONG TERM /TUESDAY THROUGH THURSDAY/... HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW 70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA. HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD INSOLATION ON WEDNESDAY. 12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF THE COLDER SOLUTION. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... VFR CONDITIONS WILL CONTINUE THROUGH ABOUT 04Z WHEN HZ/BR WILL START TO DEVELOP WITH HIGH BOUNDARY LAYER MOISTURE IN PLACE. LOW PRESSURE WILL MOVE FROM THE UPPER GREAT LAKES TO NEAR LAKE ONTARIO OVERNIGHT. SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR AHEAD OF THE ASSOCIATED FRONT THAT WILL PUSH SOUTH OVER THE AREA LATE TONIGHT INTO SATURDAY MORNING. FOR NOW HAVE PUT VCSH INTO ALL SITES BUT HAVE NOT INCLUDED THUNDERSTORMS GIVEN THE UNCERTAINTY IN COVERAGE. A SCT-BKN MVFR CLOUD DECK WILL LIKELY DEVELOP BEHIND THE FRONT ON SATURDAY MORNING WITH SOME POTENTIAL FOR IFR CLOUDS/VISIBILITY. OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH MONDAY. && .MARINE... A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO 10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL OHIO. WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON MONDAY NIGHT AND TUESDAY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...TK NEAR TERM...TK SHORT TERM...TK LONG TERM...KEC AVIATION...KEC MARINE...KEC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1137 PM EDT SAT AUG 31 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL DRIFT SOUTH ACROSS THE REGION TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... MESO ANAL STILL SHOWS A WEAK LOW LEVEL CONVERGENCE ZONE PRETTY MUCH BISECTING THE FCST AREA FROM NEAR CLEARFIELD ENE TO JUST NORTH OF WILLIAMSPORT. THIS HAS ACTED AS THE FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH HAS CAUSED LOCALLY HEAVY RAIN...BUT ACTIVITY FINALLY SEEMS TO BE SHOWING SIGNS OF WINDING DOWN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT QUICKLY. RADAR TRENDS SUGGEST SHOWERS WILL CONTINUE TO MOVE ONLY SLOWLY EASTWARD WHILE SAGGING SOUTH A BIT...BUT STILL THINK MOST ACTIVITY WILL REMAIN MAINLY NORTH OF RTE 80. OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW. TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY FOG DURING THE PREDAWN HOURS. LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER 60S IN THE SOUTHERN VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION. AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON. DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE PRIMARY/ANTICIPATED STORM TYPE. HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL 4-5F ABOVE NORMAL IN MANY LOCATIONS/. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH PLAINS. AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE NEXT WEEK. THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU THE END NEXT WEEK. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... SCT SHRA/TSRA CONTINUE TO FIRE ACROSS CENTRAL PA LATE THIS EVENING IN VICINITY OF STALLED FRONTAL BOUNDARY. AS ATMOS CONTINUES TO COOL/STABILIZE OVERNIGHT...EXPECT THE SHRA/TSRA TO DIMINISH. THE BIG AVIATION CONCERN WILL THEN BECOME FOG LATE TONIGHT. ABUNDANT LOW LVL MOISTURE AND A NEARLY CALM WIND COULD PRODUCE DENSE FOG OVER PARTS OF THE AREA. AM CURRENTLY FORECASTING A PERIOD OF IFR CONDS AT ALL AIRFIELDS EARLY SUN AM. HOWEVER...CONFIDENCE HIGHEST ACROSS NORTHERN PA...BASED ON LATEST SREF AND OPER MDL SFC RH FIELDS. ACROSS THE SOUTHERN AIRFIELDS...HIGH CLOUD COVER COULD POTENTIALLY LIMIT RAD COOLING AND FOG POTENTIAL. EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE RIDES EAST ALONG STALLED FRONTAL BOUNDARY. OUTLOOK... MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA. TUE...AM LOW CIGS/FOG POSS W MTNS. WED...AM FOG PSBL WEST AND CNTRL. THU...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...DANGELO/LA CORTE/LAMBERT LONG TERM...CERU/STEINBUGL AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1018 PM EDT SAT AUG 31 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL DRIFT SOUTH ACROSS THE REGION TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... MESO ANAL STILL SHOWS A WEAK LOW LEVEL CONVERGENCE ZONE PRETTY MUCH BISECTING THE FCST AREA FROM NEAR CLEARFIELD ENE TO JUST NORTH OF WILLIAMSPORT. THIS HAS ACTED AS THE FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH HAS CAUSED LOCALLY HEAVY RAIN...BUT ACTIVITY FINALLY SEEMS TO BE SHOWING SIGNS OF WINDING DOWN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT QUICKLY. RADAR TRENDS SUGGEST SHOWERS WILL CONTINUE TO MOVE ONLY SLOWLY EASTWARD WHILE SAGGING SOUTH A BIT...BUT STILL THINK MOST ACTIVITY WILL REMAIN MAINLY NORTH OF RTE 80. OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW. TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY FOG DURING THE PREDAWN HOURS. LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER 60S IN THE SOUTHERN VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION. AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON. DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE PRIMARY/ANTICIPATED STORM TYPE. HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL 4-5F ABOVE NORMAL IN MANY LOCATIONS/. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH PLAINS. AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE NEXT WEEK. THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU THE END NEXT WEEK. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF SHRA AROUND LNS AT 2330Z...WHILE A BAND OF SLOW MOVING TSRA ASSOC WITH A DYING COLD FRONT IS AFFECTING THE N MTNS. LOW DWPT DEPRESSION...COMBINED WITH ARRIVAL OF ADDITIONAL SHRA...WILL LIKELY KEEP VSBY AT LNS IN THE MVFR CATEGORY THIS EVENING. LINE OF TSRA OVR THE N MTNS IS EXPECTED TO WEAKEN AFTER SUNSET...AS IT PRESSES SLOWLY SE...POSSIBLY PRODUCING A BRIEF TSRA IMPACT AT UNV OR IPT BTWN 01Z-04Z. COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 06Z-13Z TIME FRAME. BASED ON LATEST SREF AND OPER MDL SFC RH FIELDS...BFD APPEARS MOST LIKELY TO EXPERIENCE DENSE FOG OVERNIGHT. EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE RIDES EAST ALONG STALLED FRONTAL BOUNDARY. OUTLOOK... MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA. TUE...AM LOW CIGS/FOG POSS W MTNS. WED...AM FOG PSBL WEST AND CNTRL. THU...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...DANGELO/LA CORTE/LAMBERT LONG TERM...CERU/STEINBUGL AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
802 PM EDT SAT AUG 31 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE REGION TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... MESO ANAL SHOWS A WEAK COLD FRONT OR OUTFLOW BOUNDARY FROM NEAR DUBOIS NE TO AROUND ELMIRA AND BINGHAMTON. THIS HAS ACTED AS THE FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH IS CAUSING LOCALLY HEAVY RAIN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT AFTER 00Z. RADAR TRENDS SUGGEST IT WILL MOVE MORE EASTWARD AS IT FADES...REMAINING MAINLY NORTH OF RTE 80. OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW. TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY FOG DURING THE PREDAWN HOURS. LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER 60S IN THE SOUTHERN VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION. AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON. DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE PRIMARY/ANTICIPATED STORM TYPE. HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL 4-5F ABOVE NORMAL IN MANY LOCATIONS/. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH PLAINS. AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE NEXT WEEK. THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU THE END NEXT WEEK. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF SHRA AROUND LNS AT 2330Z...WHILE A BAND OF SLOW MOVING TSRA ASSOC WITH A DYING COLD FRONT IS AFFECTING THE N MTNS. LOW DWPT DEPRESSION...COMBINED WITH ARRIVAL OF ADDITIONAL SHRA...WILL LIKELY KEEP VSBY AT LNS IN THE MVFR CATEGORY THIS EVENING. LINE OF TSRA OVR THE N MTNS IS EXPECTED TO WEAKEN AFTER SUNSET...AS IT PRESSES SLOWLY SE...POSSIBLY PRODUCING A BRIEF TSRA IMPACT AT UNV OR IPT BTWN 01Z-04Z. COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 06Z-13Z TIME FRAME. BASED ON LATEST SREF AND OPER MDL SFC RH FIELDS...BFD APPEARS MOST LIKELY TO EXPERIENCE DENSE FOG OVERNIGHT. EARLY LOW CIGS/FOG SHOULD LIFT TO VFR CONDS BY MIDDAY. HOWEVER...SCT TSRA IMPACTS ARE EXPECTED IN THE AFTN...AS ANOTHER DISTURBANCE RIDES EAST ALONG STALLED FRONTAL BOUNDARY. OUTLOOK... MON...AM LOW CIGS/FOG POSS AT BFD. SCT PM TSRA IMPACTS. FROPA. TUE...AM LOW CIGS/FOG POSS W MTNS. WED...AM FOG PSBL WEST AND CNTRL. THU...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...LA CORTE/LAMBERT SHORT TERM...DANGELO/LA CORTE/LAMBERT LONG TERM...CERU/STEINBUGL AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
731 PM EDT SAT AUG 31 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE REGION TONIGHT AND EARLY SUNDAY...BEFORE LIFTING BACK NORTH AS A WARM FRONT DURING THE DAY SUNDAY. A STRONGER COLD FRONT WILL MOVE THROUGH THE AREA LATER MONDAY AND MONDAY NIGHT...SETTING THE STAGE FOR SEVERAL DAYS OF COOLER AND DRIER WEATHER. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... MESO ANAL SHOWS A WEAK COLD FRONT OR OUTFLOW BOUNDARY FROM NEAR DUBOIS NE TO AROUND ELMIRA AND BINGHAMTON. THIS HAS ACTED AS THE FOCUS FOR THE MOST PERSISTENT CONVECTION WHICH IS CAUSING LOCALLY HEAVY RAIN. THE HRRR SAGS THE CONVECTION SLOWLY SE WHILE WEAKENING IT AFTER 00Z. RADAR TRENDS SUGGEST IT WILL MOVE MORE EASTWARD AS IT FADES...REMAINING MAINLY NORTH OF RTE 80. OVER THE REMAINDER OF SRN PA...JUST A SMALL CHANCE OF A STRAY SHOWER OR STORM OVERNIGHT. THE BEST CHANCE OF THIS WILL BE OVER THE FAR SE WHERE A LEE SIDE TROUGH FEATURE IS BACKED UP BY DEEPEST MOISTURE AND IMPRESSIVE MID LEVEL LAPSE RATES. CONVECTIVE DEBRIS FROM EARLIER THIS AFTERNOON IS CREATING A FAIR AMOUNT OF CIN ACCORDING TO THE LATEST RAP PLOTS...SO CONCERNS FOR SEVERE ARE LOW. TEMPS WILL EASILY COOL TO NEAR THE HIGH DEWPOINTS AFTER MIDNIGHT TONIGHT. COMBINE THIS WITH PARTIAL CLEARING...LIGHT WINDS AND JUST ISOLATED SHOWERS...AND THE STAGE WILL BE SET FOR AT LEAST PATCHY FOG DURING THE PREDAWN HOURS. LOW TEMPS WILL VARY FROM NEAR 60F ACROSS THE NORTH...TO THE UPPER 60S IN THE SOUTHERN VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... THE AFOREMENTIONED...WASHED OUT FRONT WILL BE STRETCHED OUT SOUTHERN AND ERN SECTION OF THE CWA TO START THE DAY. THIS BOUNDARY WILL LIFT NE AS A WARM FRONT DURING THE DAY SUNDAY AS THE MEAN...DEEP-LAYER FLOW BACK TO THE SOUTHWEST AHEAD OF A PAIR OF SHORTWAVES ACROSS THE OHIO VALLEY AND UPPER GLAKES REGION. AN AXIS OF RELATIVELY WARM AIR ALOFT /7-8C AT 700 MB/ AND FAIRLY WIDESPREAD CLOUD COVER TO START THE DAY SHOULD LEAD TO SLIGHTLY LESS AREAL COVERAGE OF CONVECTION THAN WE EXPERIENCED SATURDAY AFTERNOON. DEEP LAYER SHEAR WILL STILL BE QUITE WEAK...AND PWATS WILL HOLD AROUND 1.5 INCHES...SO PULSE/BRIEF MULTI-CELL CLUSTERS ARE THE PRIMARY/ANTICIPATED STORM TYPE. HIGH TEMPS SUNDAY AFTERNOON WILL BE SIMILAR TO SATURDAY`S /STILL 4-5F ABOVE NORMAL IN MANY LOCATIONS/. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE MODELS ARE IN CONSENSUS OF A DEEPENING UPPER LEVEL TROUGH MOVING THROUGH THE NORTHERN GREAT LAKES REGION AND INTO SOUTHERN CANADA AS HEIGHTS CONTINUE TO FALL SUNDAY NIGHT. THE TROUGH SHOULD REACH ITS DEEPEST MONDAY NIGHT INTO TUESDAY MORNING...WITH THE AXIS JUST TO THE WEST AT THAT TIME. OUT AHEAD OF THE AXIS THERE WILL BE STRONG SOUTHEASTERLY FLOW THAT SHOULD BRING A DECENT DRAW OF GULF MOISTURE. HAVE INCREASED POPS SLIGHTLY...THOUGH THERE IS STILL VARIABILITY IN THE TIMING...SO HAVE LEFT BROAD POPS THAT MAY NEED TO BE RAISED AS WE GET CLOSER. SO...SHOWERS AND STORMS ARE STILL EXPECTED MONDAY...AND WILL PROBABLY CONTINUE THROUGH MONDAY NIGHT INTO TUESDAY. AS THE MODELS CONTINUE TO SHOW A STALLING THE DRIER AIR SHOULD PUSH INTO THE AREA LATE TUESDAY AS DRYING NORTHWESTERLY FLOW AS HIGH PRESSURE BUILDS OVER THE HIGH PLAINS. AFTER 18Z TUESDAY THE MODELS BEGIN TO DIVERGE. THE EC AND THE CANADIAN ARE IN THE BEST AGREEMENT. MODELS SHOW PERSISTENT UPPER RIDGING OVER THE ROCKIES/HIGH PLAINS AND A DOWNSTREAM MEAN TROUGH ACROSS ERN NOAM. A POSITIVE HEIGHT ANOMALY EXTENDING FROM THE CENTRAL ATLC NWD INTO GREENLAND SUGGESTS THAT THIS PATTERN WILL BE SLOW TO EVOLVE AND STAY LARGELY IN-PLACE THROUGH THE END OF NEXT WEEK. THIS SHOULD ALLOW FOR COLD AIR ADVECTION THAT SHOULD LOWER TEMPERATURES TO...AND SLIGHTLY BELOW...SEASONABLE AVERAGES...LATE NEXT WEEK. THIS WILL BE BEHIND A MOISTURE- STARVED COLD FRONT THAT SHOULD REINFORCE THE FALL-LIKE AIRMASS. OVERALL...THE PATTERN FAVORS NEAR TO BELOW NORMAL TEMPERATURES AND BELOW MEDIAN PRECIPITATION THRU THE END NEXT WEEK. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... UPPER LVL DISTURBANCE PUSHING THRU SE PA IS PRODUCING AN AREA OF SHRA/TSRA AROUND MDT/LNS THIS EVENING...WHILE A BAND OF SLOW MOVING TSRA ASSOC WITH A DYING COLD FRONT IS AFFECTING THE N MTNS. THE SHRA OVR THE SE COULD PRODUCE A BRIEF MVFR VIS RESTRICTION AT MDT OR LNS BTWN 22Z-01Z. LINE OF TSRA OVR THE N MTNS IS EXPECTED TO WEAKEN AFTER SUNSET...AS IT PRESSES SLOWLY SE...POSSIBLY PRODUCING A BRIEF TSRA IMPACT AT JST/AOO/UNV/IPT. COOLING/STABILIZING SHOULD RESULT IN ANY LINGERING CONVECTION DISSIPATING BY ARND MIDNIGHT. THE BIG AVIATION CONCERN WILL THEN BECOME FOG LATE TONIGHT. IFR CONDS POSSIBLE IN THE 08Z-13Z TIME FRAME...ESP IN THOSE SPOTS THAT RECEIVE RAINFALL THIS EVENING. EARLY LOW CIGS/FOG WILL LIFT TO VFR CONDS BY AFTN. HOWEVER...SCT TSRA IMPACTS ARE EXPECTED IN THE AFTN IN VICINITY OF STALLED FRONTAL BOUNDARY. OUTLOOK... MON...AM FOG. SCT PM TSRA IMPACTS. FROPA. TUE...MVFR CIGS WEST/VFR CNTRL AND EAST. WED...AM FOG PSBL WEST AND CNTRL. NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...LA CORTE/LAMBERT SHORT TERM...DANGELO/LA CORTE/LAMBERT LONG TERM...CERU/STEINBUGL AVIATION...FITZGERALD/LAMBERT
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
212 PM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE RETURNS ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM...I WILL ISSUE A QUICK UPDATE TO INCREASE SKY COVER AND REDUCE POPS OVER THE NEXT COUPLE OF HOURS. TEMPERATURES UNDER THE CLOUD COVER HAS MANAGED TO AGREE FAIRLY WELL WITH THE FORECAST...BUT I WILL MAKE SEVERAL MINOR ADJUSTMENTS. AS OF NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN. 630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS FROM THE WRN UPSTATE UP TO THE MTNS. AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY CORRESPONDINGLY GREATER. UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT. COVERAGE BOTH DAYS WILL FAVOR THE MOUNTAINS WITH LOWER...BUT STILL SCATTERED COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL BOTH DAYS WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL. A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT. HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH FLOODING BOTH SUN AND MON DUE TO SLOW MOVING STORMS. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT TUE NIGHT INTO THU. A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI. THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD FRONT MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT WILL HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW. TEMPS WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AT KCLT AND ELSEWHERE...A U SHAPED BAND OF MVFR CLOUDS REMAINS ACROSS THE EASTERN SLOPES OF THE MTNS AND THE UPSTATE OF SC THIS AFTERNOON. RECENT SATELLITE TRENDS SHOWS SLOW ADVECTION OF DRIER AIR SW ACROSS THE NC/SC LINE NEAR THE I-77 CORRIDOR. DIURNAL HEATING AND INCREASING DRY AIR SHOULD RESULT IN PREVAILING VFR BASED CLOUDS BY 19Z...THEN REMAIN VFR THROUGH THIS EVENING. THE CHALLENGE OVERNIGHT WILL BE THE POTENTIAL FOR ANOTHER ROUND OF RESTRICTIVE CEILINGS. MODELS HAVE DONE A POOR JOB WITH THIS MORNINGS CLOUD COVER. GIVEN THE LINGERING LLVL MOISTURE ACROSS THE SAVANNAH RIVER VALLEY...COMBINED WITH VEERING LLVL FLOW...MOISTURE SHOULD INCREASE ACROSS THE REGION OVERNIGHT. I WILL INDICATE THE REDEVELOPMENT OF MVFR CEILINGS BY 7Z...PERSISTING THROUGH MID MORNING SAT. VFR CONDITIONS ARE EXPECTED FROM 15Z ON. CLT MAY REMAIN VFR UNTIL MORNING HEATING DEVELOPS MVFR CLOUDS. CONVECTION SHOULD REMAIN WEST OF THE TERMINALS THROUGH 18Z SAT. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 18-24Z 00-06Z 06-12Z 12-18Z KCLT HIGH 100% HIGH 100% HIGH 98% HIGH 82% KGSP HIGH 100% HIGH 100% HIGH 91% MED 60% KAVL HIGH 85% HIGH 81% LOW 38% LOW 59% KHKY HIGH 100% HIGH 100% HIGH 83% MED 69% KGMU HIGH 100% HIGH 100% HIGH 91% MED 64% KAND HIGH 94% HIGH 100% MED 69% LOW 53% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JOH NEAR TERM...NED SHORT TERM...LG LONG TERM...LG AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1212 PM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE RETURNS ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS NOON...SATELLITE AND SFC OBS INDICATED THAT A WEAK WEDGE OF STABLE AIR HAS SETTLED ACROSS THE WESTERN CAROLINAS. HOWEVER...A BAND UNSTABLE AIR REMAINS POOLS ACROSS THE UPPER SAVANNAH RIVER VALLEY AND WESTERN NC MTNS THIS MORNING. LLVL ENE WINDS COUPLED WITH WEST WINDS ALOFT HAS RESULTED IN VERY SLOW STORM MOTIONS THIS MORNING. AN ISOLATED SHOWER HAS REMAINED OVER OCONEE COUNTY THIS MORNING...RESULTING IN MULTIPLE FLOODED ROADS. HOWEVER...NAM INDICATES THAT LLVL WINDS WILL VEER THIS MORNING...LIKELY RESULTING IN THE SHOWER TO DRIFT SE INTO MORE STABLE AIR. THE REST OF THE DAY SHOULD FEATURE WEDGE-LIKE CLOUD PATTER ACROSS THE EAST FACING SLOPES...NE GA...AND THE SC UPSTATE THROUGH THIS AFTERNOON. I WILL UPDATE THE FORECAST TO LOWER TEMPS UNDER THE CLOUD COVER. POPS WILL HIGHLIGHT LATE AFTERNOON CONVECTION ACROSS THE HIGH TERRAIN. 630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS FROM THE WRN UPSTATE UP TO THE MTNS. AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY CORRESPONDINGLY GREATER. UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 215 PM FRI...UPPER HEIGHTS ARE FORECAST TO GRADUALLY FALL ACROSS THE EASTERN U.S LATE IN THE WEEKEND INTO THE NEW WORK WEEK AS AN UPPER TROUGH DIGS OVER THE GREAT LAKES. IN THE DEVELOPING NW FLOW...A WEAK SHORT WAVE WILL MOVE EAST OF THE AREA SAT NIGHT...WHILE A SECOND WAVE IS FORECAST TO REACH THE AREA LATE SUNDAY AFTERNOON...AND THEN ANOTHER LATE MON. IN THE BOUNDARY LAYER...WEAK S/SW FLOW WILL KEEP COPIOUS MOISTURE OVER THE AREA WITH PW VALUES IN THE 1.75-2 INCH RANGE. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SUN AND MON AFTERNOONS....WITH THE USUAL DECREASE IN COVERAGE OVERNIGHT. COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT COVERAGE OVER THE PIEDMONT. HIGHS WILL BE CLOSE TO NORMAL BOTH DAYS WITH LOWS ABOUT 5 DEGREES ABOVE NORMAL. A WEAK COLD FRONT WILL APPROACH THE AREA LATE MONDAY. FORECAST SOUNDINGS INDICATE BETTER INSTABILITY MONDAY AFTERNOON...AND A LITTLE BETTER SHEAR WHICH WILL GIVE A LOW END SEVERE THREAT. HOWEVER...IT LOOKS LIKE THE LARGEST THREAT IS FOR ISOLATED FLASH FLOODIND BOTH SUN AND MON DUE TO SLOW MOVING STORMS. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 200 PM FRI...THE EXTENDED PERIOD WILL FEATURE AN UPPER TROUGH AMPLIFYING OVER THE EASTERN U.S. AND AN UPPER HIGH OVER THE WEST. AT THE SURFACE...A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA MON NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WED INTO THU. A SECONDARY COLD FRONT WILL REACH THE REGION ON FRI. THE NW FLOW ALOFT WILL PROMOTE GENERALLY DRY CONDITIONS. THE EXCEPTION IS ON TUE WHEN SOME LINGERING INSTABILITY BEHIND THE COLD FRONT TUE MAY TRIGGER SOME SCATTERED THUNDERSTORMS. THE FRI FRONT WILL HAVE LITTLE MOISTURE TO WORK WITH...SO POPS WILL REMAIN LOW. TEMPS WILL BE SLIGHTLY BELOW NORMAL THROUGH THE PERIOD. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW. ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO SUPPORTING MVFR FOG ACRS MUCH OF THE AREA. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 16-22Z 22-04Z 04-10Z 10-16Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 87% KGSP HIGH 100% HIGH 100% HIGH 88% HIGH 95% KAVL HIGH 99% HIGH 100% MED 74% HIGH 87% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% MED 79% KAND HIGH 94% HIGH 100% HIGH 94% MED 79% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...NED SHORT TERM...RWH LONG TERM...RWH AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
658 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE RETURNS ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... 630 AM UPDATE...REGARDING PRECIP IN THE SAVANNAH RIVER VALLEY...THE CURRENT TRENDS SUGGEST THE ACTIVITY WILL DIMINISH AS INSTABILITY BOTTOMS OUT AT DIURNAL MINIMUM. HOWEVER RAP CAPE TRENDS BEGIN RAMPING BACK UP OVER THE NEXT COUPLE HOURS. LAPSE RATES AND PROG SOUNDINGS STILL LOOK UNIMPRESSIVE TODAY AWAY FROM THE BLUE RIDGE...BUT THESE CELLS ARE IN AN AREA FAVORED BY THE OVERNIGHT NAM RUNS AS WELL AS THE RAP SO I HAVE MADE A GRADUAL TRANSITION OF POPS FROM THE WRN UPSTATE UP TO THE MTNS. AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY CORRESPONDINGLY GREATER. UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL. A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH PRESSURE MOVING IN. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AT KCLT...SOME UNCERTAINTY AS TO WHETHER LOW MVFR STRATOCU WILL REACH THE FIELD IN EASTERLY FLOW INTO THE PIEDMONT EARLY THIS MORNING. WILL MAINTAIN SCT010 FOR FIRST HOUR. OTHERWISE VFR CUMULUS WILL BE THE DOMINANT CLOUDS BY MID MORNING. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN PER CONSENSUS OF LATEST GUIDANCE. THE SELY FLOW WITH ATLANTIC FETCH MAY CAUSE LOW STRATUS TO MOVE IN TONIGHT SIMILAR TO WHAT IS HAPPENING THIS MORNING. GUIDANCE HAS HANDLED THIS MORNING/S CIGS POORLY SO WILL KEEP TONIGHT VFR FOR NOW. ELSEWHERE...PATCHY STRATOCU WILL PLAGUE THE TAF SITES EARLY THIS MORNING. THE CLOUDS ARE MOSTLY LOW VFR TO MVFR BUT OBS SUGGEST SOME BASES MAY BE AT IFR LEVEL. SHRA IN THE SAVANNAH RIVER VALLEY WILL CAUSE EVEN MORE RESTRICTIVE CONDITIONS EARLY TODAY AS WELL. AWAY FROM PRECIP CIGS SHOULD EASILY BE ABLE TO MIX UP TO VFR BY MID MORNING. ISOLD TO WIDELY SCT CONVECTION MAY DEVELOP BY MIDDAY NEAR THE BLUE RIDGE BUT CHCS TOO LOW FOR A TAF MENTION ATTM. LIGHT NE TO ENE WINDS WILL VEER TO GENERALLY SE BY AFTERNOON AND REMAIN THERE INTO THE EVENING. THE SE WINDS WILL BRING IN ATLANTIC MOISTURE AND MAY ALLOW CIGS TO LOWER ONCE AGAIN TONIGHT...WITH GUIDANCE ALSO SUPPORTING MVFR FOG ACRS MUCH OF THE AREA. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 11-17Z 17-23Z 23-05Z 05-11Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 97% KGSP HIGH 84% HIGH 100% HIGH 100% HIGH 94% KAVL HIGH 90% HIGH 98% HIGH 100% HIGH 86% KHKY HIGH 85% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 81% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 87% HIGH 100% HIGH 100% HIGH 90% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
500 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE RETURNS ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... 415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED. EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY. AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY CORRESPONDINGLY GREATER. UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL. A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH PRESSURE MOVING IN. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... AT KCLT /09Z UPDATE/...PATCHY VFR STRATOCU OVER THE FOOTHILLS AND WRN PIEDMONT WILL LIKELY LAST INTO THE MORNING. OBS SUGGEST A FEW LOWER CLOUDS ARE UNDERNEATH THE MAIN DECK AND I CANNOT RULE OUT BRIEF RESTRICTIONS ENTIRELY THRU DAYBREAK. GUIDANCE PERFORMING POORLY AND NOT PROVIDING MUCH CONFIDENCE...BUT FEEL VFR LIKELY TO CONTINUE. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN PER 06Z NAM AND CONSENSUS OF PREVIOUS NAM/GFS RUNS. ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 09-15Z 15-21Z 21-03Z 03-09Z KCLT HIGH 89% HIGH 100% HIGH 100% HIGH 100% KGSP LOW 58% HIGH 95% HIGH 100% HIGH 100% KAVL MED 75% HIGH 88% HIGH 100% HIGH 91% KHKY MED 75% HIGH 98% HIGH 100% HIGH 83% KGMU MED 62% HIGH 95% HIGH 100% HIGH 100% KAND MED 78% HIGH 96% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
427 AM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH A MOIST EASTERLY FLOW. THE HIGH SLOWLY SLIDES OFF SHORE THROUGH THE WEEKEND WITH A SOUTHERLY FLOW DEVELOPING. A COLD FRONT APPROACHES FROM THE NORTHWEST ON MONDAY AND CROSSES THE AREA TUESDAY. DRY HIGH PRESSURE RETURNS ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... 415 AM UPDATE...PRECIP COVERAGE HAS INCREASED OVER THE PAST HOUR AS SUGGESTED BY EARLIER HRRR RUNS...HOWEVER NOT QUITE AS EXPECTED. EASTERLY FLOW DOES CONTINUE TO PLAY A PART IN DRIVING LIGHT SHOWER ACTIVITY IN THE FOOTHILLS...BUT STRONGER CELLS NOW FAVOR THE WRN PORTION OF THE UPSTATE WHERE SPC MESOANALYSIS INDICATES GREATEST SFC INSTABILITY IS PRESENT LIKELY DUE TO HIGHER DEWPOINTS. MAINTAINED POP MENTION ALL ALONG THE BLUE RIDGE BUT NOW FEATURE BEST CHANCES IN THE UPSTATE. RAIN RATES ARE RATHER HIGH AND REFLECTIVE OF ABUNDANT MOISTURE...BUT CELL MOTION SO FAR HAS BEEN ENOUGH TO PRECLUDE FLASH FLOOD THREAT. LLVL FLOW SHOWN TO WEAKEN SLIGHTLY TOWARD DAWN ON 06Z NAM SO IT IS WISE TO CONTINUE TO MONITOR CLOSELY. AS OF 3 AM FRIDAY...SFC HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MAINTAIN LIGHT EASTERLY FLOW IN LOW LEVELS THRU TODAY. POOR LLVL LAPSE RATES WILL LIMIT DIURNALLY DRIVEN CONVECTION THROUGHOUT THE REGION TODAY...BUT THE UPSLOPE FLOW MAY PROVIDE ENOUGH LIFT TO KICK OFF A FEW CELLS IN THE MORE FAVORABLE ENVIRONMENT NEAR THE BLUE RIDGE...WHERE LLVL MOISTURE IS A BIT BETTER AND INSTABILITY CORRESPONDINGLY GREATER. UPPER PATTERN THRU THE PERIOD WILL BE DOMINATED BY ANTICYCLONE OVER THE SOUTHERN ROCKIES...BUT AS A SHORTWAVE ROUNDS IT AND MOVES ACROSS THE ERN GREAT LAKES HEIGHTS WILL FALL SLIGHTLY AND THE LOW TO MIDLEVEL FLOW WILL BECOME MORE SOUTHERLY BY TONIGHT. THAT FLOW CONTINUES TO PROVIDE LIFT BUT IS NOT IMPRESSIVE. MOISTURE REMAINS CONCENTRATED IN THE LOW LEVELS TONIGHT...AND PROG SOUNDINGS SUGGEST CIN WILL BE GREAT ENOUGH TO ALLOW CONVECTION TO GRADUALLY WANE OVER THE EVENING...LEAVING THE CWFA DRY FOR THE SECOND HALF OF THE NIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 225 AM FRI...THE CWFA WILL REMAIN IN A WEAKNESS BETWEEN THE RIDGING OVER THE CENTRAL CONUS AND THE ATLANTIC. THIS ALLOWS WEAK SHORT WAVES MOVING THRU THE WESTERLIES TO DIG A SHALLOW TROF OVER THE ERN CONUS EARLY IN THE PERIOD AND A STRONGER TROF BY MONDAY AS AN UPPER LOW MOVES INTO THE GREAT LAKES REGION. WEAK S TO SWLY LOW LEVEL FLOW KEEPS COPIOUS MOISTURE OVER THE AREA WITH PW VALUES AS HIGH AS 2 INCHES. THIS COMBINED WITH MODERATE INSTABILITY WILL LEAD TO DIURNAL CONVECTION BOTH SAT AND SUN AFTERNOONS. COVERAGE BOTH DAYS WILL FAVOR THE MTNS WITH LOWER...BUT STILL SCT...CHC OVER THE PIEDMONT. HIGHS WILL BE NEARLY STEADY NEAR NORMAL BOTH DAYS WITH LOWS NEARLY STEADY ABOUT 5 DEGREES ABOVE NORMAL. A WEAK FRONT MOVES IN WITH THE STRONGER TROF ON MON. EVEN WITH THE FRONT AND TROF...CONVECTIVE COVERAGE WILL FAVOR THE MTNS AND TAPER OFF TO THE PIEDMONT. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. WITH COPIOUS MOISTURE AND SLOW MOVING STORMS...HEAVY RAINFALL IS POSSIBLE...POTENTIALLY LEADING TO ISOLATED FLASH FLOODING EACH DAY. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 310 AM FRI...AN UPPER TROF STARTS OUT OVER THE ERN CONUS ON TUE THEN SLIDES OFF SHORE WED. THE CWFA REMAINS IN LIGHT NWLY FLOW THRU THE END OF THE PERIOD WITH LITTLE IN THE WAY OF SHORT WAVE ACTIVITY DROPPING THRU THE FLOW. AT THE SFC...A COLD FRONT STARTS OUT OVER THE AREA TUE THEN SLIDES SOUTH AND EAST OF THE AREA WED AS HIGH PRESSURE BUILDS IN FROM THE NW THU. ALL THIS LEADS TO DIURNAL SCT CONVECTION TUE. THERE IS SOME INDICATION THAT MOISTURE COULD LINGER OVER THE SAV RIVER VALLEY OR SWRN NC MTNS ON WED WITH DRIER AIR MOVING IN ELSEWHERE. HOWEVER...HAVE KEPT FCST DRY FOR NOW. DRY FCST CONTINUES THU. TEMPERATURES FALL BELOW NORMAL WITH COOLER HIGH PRESSURE MOVING IN. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN. ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 08-14Z 14-20Z 20-02Z 02-08Z KCLT HIGH 87% HIGH 100% HIGH 100% HIGH 100% KGSP MED 66% HIGH 93% HIGH 100% HIGH 100% KAVL MED 76% HIGH 87% HIGH 100% HIGH 93% KHKY HIGH 80% HIGH 93% HIGH 100% HIGH 87% KGMU MED 73% HIGH 93% HIGH 100% HIGH 100% KAND HIGH 84% HIGH 97% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
153 AM EDT FRI AUG 30 2013 .SYNOPSIS... HIGH PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A MOIST EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH SOUTHERLY FLOW WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT INTO TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... 1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE RIDGE SEES UPTICK. REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY. I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS. EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75 INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH. WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING. MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON ANALOGS. THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY. SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY OF NORMAL. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN. ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 06-12Z 12-18Z 18-24Z 00-06Z KCLT HIGH 91% HIGH 91% HIGH 100% HIGH 100% KGSP MED 74% MED 78% HIGH 100% HIGH 100% KAVL MED 79% HIGH 80% HIGH 100% HIGH 97% KHKY MED 68% HIGH 88% HIGH 100% HIGH 88% KGMU HIGH 86% HIGH 82% HIGH 100% HIGH 100% KAND HIGH 91% HIGH 83% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JOH NEAR TERM...NED/WIMBERLEY SHORT TERM...LG LONG TERM...LG AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
150 AM EDT FRI AUG 30 2013 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE SOUTH ACROSS THE REGION TODAY. HIGH PRESSURE WILL NOSE IN FROM THE NORTH ON FRIDAY...BUT WITH A MOIST EASTERLY FLOW IN PLACE. WEAK HIGH PRESSURE ALONG WITH SOUTHERLY FLOW WILL LINGER THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON MONDAY...CROSS THE AREA MONDAY NIGHT INTO TUESDAY...WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... 1 AM UPDATE...LLVL EASTERLY FLOW NORTH OF FRONTAL BOUNDARY...NOW STRETCHING ACROSS CENTRAL GA AND SRN SC...CONTINUES TO SUPPORT CONVECTIVE PRECIP NEAR THE BLUE RIDGE WITH A FEW HUNDRED JOULES OF MLCAPE STILL AVAILABLE. 03Z HRRR PICKED UP RECENT ACTIVITY AND SHOWS IT DIMINISHING WITH A SECOND WAVE FIRING UP AS MOISTURE CONTINUES TO COLLECT AND FLOW VEERS SLIGHTLY BECOMING MORE PERPENDICULAR TO THE MTN CHAIN. THAT SEEMS LIKE A REASONABLE ASSUMPTION AS CLOUD COVER ALREADY IS INCREASING IN PORTIONS OF THE CENTRAL/NRN MTNS PER SATELLITE FOG PRODUCT. ADJUSTED POPS TO TAKE THE SC ACTIVITY ON A SWLY COURSE...DIMINISHING OVER THE NEXT COUPLE HRS BEFORE WHOLE BLUE RIDGE SEES UPTICK. REMAINDER OF PREV DISCUSSION...FRIDAY...DRIER AIR WILL CONTINUE TO ADVECT SW ACROSS THE FOOTHILL AND PIEDMONT REGIONS. THE MTN ENVIRONMENT MAY POOL HIGHER DEWPOINTS...SUPPORTING WEAK INSTABILITY. I WILL KEEP A MENTION OF SCHC TO CHC CONVECTION ACROSS THE MTNS. EAST...I WILL REDUCE POPS BELOW SCHC. FRESH CAA SHOULD KEEP HIGH TEMPERATURES ONE TO TWO DEGREES BELOW NORMAL. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... AS OF 200 PM EDT THU...THE WESTERN EXTENSION OF THE BERMUDA HIGH WILL WEAKLY DOMINATE THE WEATHER REGIME THROUGH THE WEEKEND. IN THE UPPER LEVELS...AN UPPER RIDGE TO THE WEST AND WEAK TROUGHING TO OUR NORTH WILL RESULT IN WEAKLY DIFLUENT FLOW OVER THE SE U.S. WITH A WEAK SHORT WAVE TRAVERSING THE REGION ON SUN. MODEL TIME HEIGHTS INDICATE THAT MOISTURE WILL BE PLENTIFUL WITH PWATS AROUND 1.75 INCHES. THIS WILL SET THE STAGE FOR DIURNALLY DRIVEN THUNDERSTORMS TO DEVELOP BOTH SAT AND SUN AFTERNOONS. ON SAT...THE MOST COVERAGE WILL BE OVER THE CENTRAL AND SOUTHERN NC MOUNTAINS...INTO THE WESTERN UPSTATE AND NE GA WHERE WEAK UPSLOPE FLOW WILL EXIST. ON SUNDAY AFTERNOON...EXPECT COVERAGE TO BE GREATER THAN ON SAT WITH NUMEROUS SHOWERS/STORMS OVER THE MOUTNAINS/FOOTHILLS WITH SCATTERED STORMS OUT OVER THE PIEDMONT AS A WEAK SHORT WAVE MOVES THROUGH. WITH WEAK FLOW ALOFT AND HIGH PWATS...THE MAIN THREAT OVER THE WEEKEND WILL BE FOR LOCALLY HEAVY RAIN AND LOCALIZED FLASH FLOODING. MAX TEMPS BOTH SAT AND SUN WILL TOP OUT NEAR CLIMO. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 215 PM EDT THU...UPPER HEIGHTS ARE FORECAST TO FALL ACROSS THE SE U.S. THE FIRST PART OF THE NEW WORK WEEK AS AN EASTERN U.S. LONGWAVE TROUGH DEVELOPS. LAPSE RATES WILL IMPROVE ON MONDAY AS A COLD FRONT APPROACHES FROM THE WEST AND UPPER LEVEL HEIGHTS FALL. EXPECT THAT THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE NUMEROUS OVER THE MOUNTAINS WITH SCATTERED STORMS OUT OVER THE PIEDMONT. LOW END SEVERE AND FLASH FLOOD THREATS WILL EXIST MON AFTERNOON INTO THE EVENING HOURS SUPPORTED BY CIPS WARM SEASON ANALOGS. THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY. SHEAR AND INSTABILITY IN THE PROFILES DO NOT LOOK PARTICULARLY THREATENING...ESPECIALLY IN LIGHT OF THE THE UNFAVORABLE TIME OF FRONTAL PASSAGE. SOME LINGERING INSTABILITY ESPECIALLY OVER THE PIEDMONT AREAS COULD ALLOW FOR SOME SHOWERS/THUNDERSTORMS ON TUE...BUT GENERALLY EXPECT LOWERING DEWPOINTS AND AND LOWERING POPS ON TUE. HIGH PRESSURE IS FORECAST TO BUILD OVER THE REGION ON WED AND THU PRODUCING GENERALLY DRY CONDITIONS AND TEMPS A CATEGORY SHY OF NORMAL. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AT KCLT...CLOUDS WILL CONTINUE TO RESULT OVERHEAD AS LLVL EASTERLY FLOW PERSISTS INTO TOMORROW. GUIDANCE NOT PROVIDING A CLEAR SIGNAL BUT MODELS GENERALLY HAVE OVERDONE CIGS SO FAR...SO HAVE KEPT VFR THRU DAYBREAK...WITH HIGHER CONFIDENCE FOR VFR THEREAFTER. SCT VFR CUMULUS WILL BE THE DOMINANT CLOUDS FRI. LIGHT ENE WINDS SHOULD VEER TO SE BY AFTN. ELSEWHERE...EASTERLY UPSLOPE FLOW NORTH OF WEAK COLD FRONT WILL SUPPORT CLOUDS OVERNIGHT. RESTRICTIONS ARE ESPECIALLY FAVORED NEAR THE BLUE RIDGE. GUIDANCE CONSENSUS DOES BRING MVFR CIG TO ALL SITES EXCEPT KAVL WHERE IFR STILL EXPECTED. MTN VALLEY FOG LIKELY ONCE AGAIN WITH VERY HUMID CONTDITIONS IN PLACE. KHKY SAW A PERIOD OF HVY RA THU EVENING AND THE WET SOILS THERE WILL LIKELY SUPPORT IFR FOG AS WELL. CIGS SHOULD BE SLOWER TO LIFT THE LOWER THEY BOTTOM OUT...BUT WITH MOST SITES STAYING MVFR RESTRICTIONS SHOULD LIFT BY MID MORNING AT THE LATEST. VFR CU WILL PERSIST THRU THE DAY IN SOME FASHION WITH THE BLUE RIDGE AGAIN FAVORABLE FOR TS DEVELOPMENT. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED EACH DAY THRU THE WEEKEND. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. CONFIDENCE TABLE... 05-11Z 11-17Z 17-23Z 23-05Z KCLT HIGH 98% HIGH 85% HIGH 100% HIGH 100% KGSP MED 75% MED 70% HIGH 100% HIGH 100% KAVL HIGH 84% MED 79% HIGH 99% HIGH 100% KHKY MED 76% HIGH 83% HIGH 100% HIGH 91% KGMU HIGH 92% MED 76% HIGH 100% HIGH 100% KAND HIGH 98% MED 70% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JOH NEAR TERM...NED/WIMBERLEY SHORT TERM...LG LONG TERM...LG AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
324 PM CDT FRI AUG 30 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT DESTABILIZATION OCCURRING THIS AFTERNOON ACROSS THE WESTERN DAKOTAS WITH MESOANALYSIS INDICATING AROUND 2000 J/KG MLCAPE. SHEAR VALUES RANGE FROM AROUND 35 TO 40 KNOTS OVER WESTERN SD. A SEVERE STORM IS AFFECTING THE BLACK HILLS AT THIS TIME...WITH VIS SATELLITE IMAGERY SHOWING THE BEGINNINGS OF A CU FIELD EXTENDING NORTHWARD INTO DICKINSON ND. HI RES MODELS DO SHOW ISOLD/WDLY SCT CONVECTION OCCURRING OVER THE NEXT FEW HOURS AND LASTING INTO THE EVENING HOURS...SOME OF WHICH MAY AFFECT THE FAR WESTERN CWA. LATEST HRRR RUN HAS THE CONVECTION OVER THE BLACK HILLS NAILED RIGHT NOW AND SHOWS SMALL BUT POTENT CELLS DEVELOPING ALONG THE CURRENT CU FIELD OVER THE NEXT COUPLE HOURS...THEN PUSHES THINGS INTO CORSON/DEWEY COUNTIES. NOT SURE AREAL COVERAGE WILL BE AS GREAT AS THE HRRR...BUT IN SOME FORM OR ANOTHER...DO EXPECT ISOLD TO WDLY SCT STORMS OVER THE NEXT FEW HOURS. SVR WATCH 505 WAS RECENTLY ISSUED TO COVER THIS THREAT. WITH THE LACK OF ANY APPRECIABLE LOW LEVEL JET OVERNIGHT...DO NOT EXPECT THIS ACTIVITY TO SURVIVE MUCH PAST THE MISSOURI RIVER AND SHOULD WANE WITH THE LOSS OF DAYTIME HEATING. FOCUS WILL THEN TURN TO THE ADVANCING COLD FRONT ON SATURDAY. FRONT WILL SET UP ACROSS THE EASTERN CWA BY PEAK HEATING...WITH MODERATE INSTABILITY AND SHEAR DEVELOPING. ALTHOUGH BEST UPPER LEVEL SUPPORT IS NORTH OF THE REGION...CONVERGENCE ALONG THE SHARP FRONTAL BOUNDARY ALONG WITH SUFFICIENT LOW LEVEL MOISTURE AND STEEP LAPSE RATES IS EXPECTED TO LEAD TO MID/LATE AFTERNOON THUNDERSTORM DEVELOPMENT ALONG THE FRONT. SPEED OF THE FRONT WILL BE KEY IN DETERMINING BEST CHANCE FOR STORMS. GIVEN PLACEMENT OF THE FRONT BY AFTERNOON...CONVECTIVE INITIATION COULD OCCUR BETWEEN THE JAMES VALLEY AND I-29...WITH MORE CONSOLIDATION/BETTER STORM CHANCES CLOSER TO I-29 AND POINTS EAST BY LATE AFTERNOON AND INTO THE EVENING. DAY TWO SLIGHT RISK IS NOW INCLUDING EASTERN PORTIONS OF THE FORECAST AREA. BEHIND THIS FRONT WILL BE MUCH COOLER AIR...WITH HIGHS ON SUNDAY EXPECTED TO DROP BACK INTO THE 70S FOR MOST AREAS. SFC HIGH WILL BUILD SOUTH INTO THE AREA SUNDAY NIGHT...AND WITH THE COOLER AND DRIER AIR MASS IN PLACE...LOWS BY MONDAY MORNING COULD ACTUALLY DIP INTO THE UPPER 40S. .LONG TERM...MONDAY THROUGH FRIDAY THE LONG TERM LOOKS TO REMAIN ON THE DRY SIDE WITH UPPER LEVEL RIDGING AND SUBSIDENT FLOW DOMINATING THE WEATHER. THE MODELS SHOW THE UPPER LEVEL RIDGE AXIS OUT WEST TO BEGIN THE LONG TERM PUSHING EAST THROUGH FRIDAY OVER OUR REGION. ANY SHORT WAVES MOVING OVER THE RIDGE SHOULD BE MOISTURE STARVED WITH ONLY SOME CLOUDS MOVING IN. AFTER A COOLER DAY ON MONDAY...WARMER AIR WILL RETURN FOR TUESDAY AND REMAIN THROUGH FRIDAY. SHOULD HAVE MID 70S EAST ON MONDAY WARMING TO THE 80S TO THE LOWER 90S ACROSS ALL OF THE CWA THROUGH THE REST OF THE WEEK. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH TONIGHT AND SATURDAY MORNING. A COLD FRONT COMING ACROSS THE REGION LATER TONIGHT AND SATURDAY WILL BRING SOME SHOWERS AND STORMS ALONG IT WHICH MAY AFFECT THE TERMINALS. WILL WATCH FOR DEVELOPMENT. ALSO...EXPECT SOME FOG TO FORM AT ATY LATER TONIGHT WITH THE LIGHT WINDS AND CLEAR SKIES. LIGHT FOG MAY ALSO BE POSSIBLE AT ABR. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...MOHR AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
153 PM EDT FRI AUG 30 2013 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC TODAY WILL SHIFT OFFSHORE BY THIS EVENING. A WARM FRONT ENTERS THE MOUNTAINS SATURDAY...FOLLOWED BY A COLD FRONT ARRIVING SOMETIME MONDAY. DURING THIS PERIOD...SHOWER AND THUNDERSTORM CHANCES REMAIN. && .NEAR TERM /THROUGH TONIGHT/... AS OF 148 PM EDT FRIDAY... WEAK INSITU WEDGE WILL MOVE OFF SHORE THROUGH THIS EVENING. AS THIS WEDGE MOVES OUT OF THE AREA...ANY LINGERING LOW STRATUS DECK WILL ALSO EXIT THE AREA. LIGHT SOUTHERLY FLOW WILL THEN BRING WARM HUMID AIR BACK INTO THE REGION OVER THE NEXT 24 HOURS. HRRR AND 06Z RNK WRF PICKING UP ON A THETA-E BOUNDARY ACROSS THE AREA FROM SUMMERS COUNTY WV TO THE WESTERN PART OF GRAYSON COUNTY NC. THE LOCATION OF THIS BOUNDARY AND POINTS WEST WILL BE THE AREA THAT SHOULD SEE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON. ISOLATED SEVERE THREAT IS POSSIBLE WITH DRY AIR ABOVE 700 MB. HOWEVER...SATURATED SOUNDING BELOW 700 MB MAY ONLY GENERATE LOW TOP CONVECTION WITH THE POTENTIAL FOR SOME STRONGER STORMS TO PRODUCE HEAVY RAIN. STORMS THAT DEVELOP WITH THE HEATING OF THE DAY WILL BE SLOW MOVING. THEREFORE...THE BIGGEST THREAT WILL BE LOCALIZED FLOODING...ESPECIALLY IN AREAS THAT HAVE SEEN RAIN THE PAST COUPLE OF DAYS. BREAKS IN THE CLOUDS TODAY WILL ALLOW TEMPERATURES TO MAX OUT NEAR NORMAL...WIDESPREAD 80S. DEW POINTS WILL REMAIN HIGH WITH READINGS IN THE MID 60S TO LOWER 70S. TONIGHT...THERE SHOULD BE A QUICKER DROP OFF IN PRECIP THAN THIS PAST EVENING AS THE HIGHER THETA-E AIR MOVES INTO TN/KY. WITH CLEARING SKIES AND LIGHT WINDS...SHOULD SEE PATCHY FOG OVER MOST OF THE AREA...ESPECIALLY RIVER VALLEYS. LOWS ARE GOING TO BE IN THE 60S STILL. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 400 AM EDT FRIDAY... HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE ATLANTIC COAST SATURDAY MORNING...WITH A WEAK WARM FRONT CROSSING OUR AREA FROM THE SOUTHWEST. WILL SEE ANOTHER ROUND OF SPOTTY SHOWERS AND THUNDERSTORMS DEVELOP WITH DAYTIME HEATING...MAINLY ACROSS THE MOUNTAINS STARTING IN EARLY AFTERNOON...AND THEN SPILLING OVER INTO THE PIEDMONTS DURING THE EARLY EVENING AS WINDS AND ATMOSPHERIC MIXING BEGINS TO WEAKEN. A LEE SIDE TROUGH SETTING UP ACROSS THE PIEDMONTS WILL CAUSE WINDS ACROSS THE MOUNTAINS TO SHIFT MORE WESTERLY AND THEREFORE DOWNSLOPE...WHICH WILL HELP LIMIT INSTABILITY SOMEWHAT...BUT STILL CANNOT RULE OUT A FEW STRONG STORMS. THINK THE BIGGER ISSUE TO KEEP WATCH FOR WILL BE THE POTENTIAL FOR LOCALLY HEAVY RAIN DUE TO ABUNDANT TROPICAL MOISTURE...AND SLOW MOVEMENT OF STORMS DUE TO LIGHT UPPER LEVEL WINDS. LOOKING AT A SIMILAR WEATHER PATTERN FOR SUNDAY...WITH SHOWERS AND THUNDERSTORMS DEVELOPING IN THE WEST DURING EARLY AFTERNOON AND SPREADING EAST LATER IN THE DAY. HOWEVER...BELIEVE COVERAGE OF RAINFALL WILL BE GREATER AS AN UPPER LEVEL TROUGH APPROACHES FROM THE GREAT LAKES...FURTHER DESTABILIZING THE ATMOSPHERE. ON MONDAY...A DEEP LOW PRESSURE SYSTEM WILL CROSS THE GREAT LAKES...DRAGGING A COLD FRONT RAPIDLY EASTWARD FROM THE MISSISSIPPI RIVER VALLEY. WILL AGAIN SEE SCATTERED SHOWERS AND THUNDERSTORMS DEVELOP...WHICH WILL LINGER INTO LATE EVENING AS THE COLD FRONT MAKES ITS WAY ACROSS OUR AREA AFTER SUNSET. THIS COLD FRONT WILL USHER IN A MUCH DRIER CANADIAN AIRMASS...WHICH WILL BRING AND END TO ALL BUT LINGERING SHOWERS ACROSS OUR WESTERN RIDGELINES BY TUESDAY MORNING. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 246 AM EDT FRIDAY... BY TUESDAY...THE COLD FRONT WILL BE SITUATED ALONG THE EAST COAST...WITH HIGH PRESSURE BUILDING INTO THE REGION FOR THE REMAINDER OF THE WORK WEEK. TEMPERATURES IN THIS HIGH PRESSURE AIRMASS WILL RUN COOLER THAN NORMAL FOR OUR AREA...RANGING FROM THE MID 70S IN THE WEST TO LOWER 80S IN THE EAST FOR DAILY HIGHS. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 127 PM EDT FRIDAY... AREAS EAST OF THE BLUE RIDGE STILL UNDER THE INFLUENCE OF A WEAK INSITU WEDGE. MVFR VISIBILITIES WERE SLOW TO LIFT AND SO IS THE MVFR CEILINGS. ENOUGH MIXING AND SUNSHINE WILL EVENTUALLY LIFT/ERODE THESE CLOUDS TO VFR THIS AFTERNOON. WEDGE MAY LINGER ACROSS THE SOUTHERN HALF OF RNK CWA OVERNIGHT. THIS MAY BRING A RETURN TO SUB- MVFR FOG AND CLOUDS TO AREAS ALONG THE VA/NC BORDER (DAN) POSSIBLY AGAIN TO ROA/LYH. IF ENOUGH CLEARING TAKES PLACE OVERNIGHT...RADIATIONAL IFR OR LOWER VALLEY FOG LIKELY AT LWB/BCB EARLY SATURDAY MORNING. RAIN CHANCE THIS AFTERNOON ARE BETTER FOCUS WEST OF THE THETA-E BOUNDARY ACROSS THE MOUNTAINS. SCATTERED SLOW MOVING STORMS ARE POSSIBLE AT BLF THROUGH THIS EVENING. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT LWB/BCB LATE THIS AFTERNOON AND EVENING. AREAL COVERAGE SPOTTY THEREFORE WILL ONLY HAVE VICINITY SHOWERS AT EACH OF THESE AIRPORTS THIS AFTERNOON. MORE AREAL COVERAGE OF SHOWERS AND STORMS EXPECTED SATURDAY...ESPECIALLY ACROSS THE MOUNTAINS. THE AREA WILL BE IN A WARM SECTOR WITH THE DAILY THREAT FOR SHOWERS/STORMS SUNDAY. A COLD FRONT WILL WORK ACROSS BY LATE MONDAY WITH DRIER AIR MOVING IN BY THE MIDDLE OF NEXT WEEK. OVERALL OUTSIDE OF LATE NIGHT FOG/STRATUS AND SUB VFR CONDITIONS IN SHOWERS/STORMS WILL BE SEEING VFR SAT-TUE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...RCS/WP SHORT TERM...NF LONG TERM...RCS AVIATION...JH/KK/RCS/WP
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
1035 PM PDT Thu Aug 29 2013 .SYNOPSIS... Warm late-summer weather is expected over the Inland Northwest through the upcoming holiday weekend. The passage of a cold front late tonight will deliver a few showers and thunderstorms with a small chance returning on Friday to the for a small portion of northeast Washington and the Idaho Panhandle. The Labor Day weekend is looking warmer than average with an abundance of sunshine. A transition to a showery weather pattern is expected to begin Monday and could persist through much of next week. && .DISCUSSION... Update this evening is to freshen the shower and thunderstorm potential. The fast moving negatively tilted shortwave has quickly moved out of the area and we are currently void of any showers and thunderstorms in our area. There are some pretty decent showers and thunderstorms developing across western WA and OR and may move up the Cascades later this evening. So have taken out all evening weather wording except for in the Cascades. Cold front passes overnight. HRRR suggests a line of showers and possible thunderstorms developing from eastern Columbia Basin after midnight and moving into eastern WA and ID Panhandle overnight into the early morning hours on Friday. /Nisbet && .AVIATION... 06Z TAFS: Cold front passes overnight with a thin line of showers and an isolated thunderstorm possible...impacting KGEG...KSFF...KCOE btwn 07-12z. Post frontal southwesterly winds 10-15 mph with gusts up to 25 mph can be expected Friday afternoon. VFR conditions expected at all TAF sites. && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 78 56 82 57 91 / 20 10 0 0 0 0 Coeur d`Alene 57 78 54 81 53 90 / 20 20 0 0 0 0 Pullman 53 78 48 83 49 93 / 10 10 0 0 0 0 Lewiston 64 86 59 89 61 99 / 10 10 0 0 0 0 Colville 56 83 50 85 49 93 / 20 10 0 0 0 0 Sandpoint 54 77 47 79 45 86 / 20 20 0 0 0 0 Kellogg 56 75 53 80 53 88 / 10 20 0 0 0 0 Moses Lake 58 84 54 86 56 93 / 10 10 0 0 0 0 Wenatchee 62 82 59 84 61 89 / 10 0 0 0 0 0 Omak 58 82 55 85 55 91 / 10 10 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
616 PM CDT SAT AUG 31 2013 .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) ISSUED AT 325 PM CDT SAT AUG 31 2013 MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT INTO SUN...TEMPERATURES. AT 18Z...WEAK HIGH PRESSURE WAS CENTERED OVER NORTHERN LOWER MI WITH RIDGING SOUTHWEST INTO NORTHERN IA. LOW PRESSURE WAS OVER SOUTHEAST MANITOBA WITH A TRAILING COLD FRONT INTO THE EASTERN DAKOTAS. CONVECTION SLOWLY DEVELOPING ALONG THIS FRONT EARLY THIS AFTERNOON. SHALLOW LOWER LEVEL MOISTURE/STRATO-CU TRAPPED UNDER AN INVERSION NEAR 900MB CONTINUED TO PLAGUE SOUTHERN WI/SOUTHEAST MN/EASTERN IA... BUT CONTINUED TO SLOWLY DISSIPATING WITH DIURNAL WARMING/MIXING AS OF MID-DAY. MORE COMFORTABLE DAY ACROSS MUCH OF MN/IA/WI...WITH SFC DEW POINTS IN THE 60S AND TEMPS IN THE MID 70S TO MID 80S. FOR THE MOST PART...31.12Z MODELS INITIALIZED WELL. GFS WITH ITS USUAL QUIRKY SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS VALLEY BUT NAM 850-500MB HGTS DO NOT PROVIDE THE BEST FIT TO THE RA-OBS HGTS ACROSS MUCH OF CENTRAL NOAM THIS CYCLE. NAM WITH TOO MUCH 850- 500MB SHORTWAVE TROUGHING OVER NORTHEAST MT PER THE GLASGOW MT RA-OB. DESPITE THIS...SOLUTIONS REMAIN QUITE SIMILAR FOR TONIGHT THRU SUN NIGHT AS THE SOUTHERN SASKAT SHORTWAVE DROPS SOUTHEAST ACROSS THE AREA AND INTO THE CENTRAL GREAT LAKES BY 12Z MON. DPROG/DT OF 500MB HGTS AT 31.12Z SHOWED THE MODEL RUNS OF 29.12Z AND VERIFIED WELL ACROSS NOAM/EASTERN PAC WITH BETTER RUN-TO-RUN CONSISTENCY TO ECMWF. TREND THRU TONIGHT/SUN FAVORS FASTER OF AS THE TROUGH DROPS ACROSS THE REGION THEN FAVORS A TIGHTENING COMPROMISE OF THE EARLIER RUNS WITH THE TROUGH INTO THE CENTRAL LAKES SUN NIGHT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL TO BE REASONABLE WITH THE SOUTHEAST MAN LOW/EASTERN DAKOTAS COLD FRONT. GFS REMAINED ON THE DRY SIDE WITH SFC DEW POINTS OVER THE MID/UPPER MS VALLEY. PER WV IMAGERY...ECMWF/GFS/GEM APPEARED BETTER THAN NAM WITH THE STRENGTH/ POSITION OF THE SOUTHEAST SASKAT SHORTWAVE. GIVEN THIS AND THE INITIALIZATIONS...FAVORED A NON-NAM CONSENSUS OF THE MODELS FOR TONIGHT THRU SUN NIGHT. SHORT TERM CONFIDENCE REMAINS ABOVE AVERAGE. IN THE SHORT TERM...MAIN SHORTWAVE AND MID/UPPER LEVEL DYNAMICS/LIFT WITH IT TO PASS TO NORTH OF OR ACROSS THE NORTH END OF THE FCST TONIGHT/EARLY SUNDAY. MAIN LOWER LEVEL THERMO-DYNAMIC FORCING WITH THE COLD FRONT PEAKS AROUND 00Z THIS EVENING...THEN GRADUALLY WEAKENS AS IT COMES EAST AND CROSSES THE FCST AREA LATER THIS EVENING THRU SUN MORNING. MU CAPE OF 2K-3K J/KG COINCIDENT WITH THE FRONT/THERMO-DYNAMIC FORCING EARLY THIS EVENING WANES AS WELL AS THE FRONT/FORCING/LIFT APPROACH/CROSS THE FCST AREA. PW VALUES STILL PROGGED TO BE AROUND 1.5 INCHES AHEAD OF THE FRONT TONIGHT. RATHER CONTINUOUS LINE OF CONVECTION EXPECTED TO BE IN PROGRESS FROM NORTH- CENTRAL MN TO EASTERN SD EARLY THIS EVENING...GRADUALLY WEAKENING/ BECOMING MORE SCT/BKN OVERNIGHT AS IT MOVES INTO ACROSS THE FCST AREA. CARRIED HIGHEST SHRA/TSRA CHANCES DURING THE LATE EVENING OVER THE NORTHWEST END OF THE FCST AREA WHEN/WHERE THE LINE OF CONVECTION WOULD STILL HAVE MORE INSTABILITY/FORCING/LIFT TO WORK WITH. CONTINUED/TRENDED SHRA/TSRA CHANCES MORE IN THE 20-40 PERCENT RANGE AFTER MIDNIGHT/SUN MORNING WITH LESS INSTABILITY/FORCING. WITH THE FASTER MOVEMENT OF THE MID LEVEL TROUGH...TRENDED SHRA/TSRA CHANCES DOWN/OUT OF THE FCST AREA MORE QUICKLY SUN AFTERNOON. QUESTION FOR SUN AFTERNOON ONCE THE FRONT/FORCING ARE EAST OF THE AREA IS EXTENT OF CLOUDS WITH SOME 925-850MB MOISTURE WRAPPING AROUND THE SFC-MID LEVEL LOW IN DEEP CYCLONIC FLOW...ESPECIALLY OVER THE NORTH/EAST PORTIONS OF THE FCST AREA. INCREASED CLOUD COVER FOR SUN AFTERNOON THESE AREAS. CLEARING SUN NIGHT AS THE MID LEVEL LOW QUICKLY PULLS AWAY AND LOWER LEVEL ANTICYCLONIC FLOW/HIGH PRESSURE BUILDS INTO THE AREA. 925MB TEMPS IN THE 10C-13C RANGE BY 12Z MON... FOR COOLER...MORE NEAR NORMAL LOWS MON MORNING. USED A BLEND OF THE NUMERICAL GUIDANCE LOWS/HIGHS FOR TONIGHT THRU SUN NIGHT. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 325 PM CDT SAT AUG 31 2013 MAIN FORECAST CONCERNS FOR MON THRU TUE NIGHT...FOG POTENTIAL CENTERED ON DAYBREAK TUE...TEMPERATURES THRU THE PERIOD. MODELS REMAIN IN GOOD AGREEMENT MON THRU TUE NIGHT AS THE TROUGH PROGRESSES INTO THE EASTERN CONUS...HGTS RISE AND SHORTWAVE RIDGING BUILDS INTO THE UPPER MIDWEST. FCST CONFIDENCE IN THIS PERIOD IS GOOD. THE CENTER OF THE CANADIAN HIGH DRIFTS FROM NORTHERN MN MON MORNING TO IL/IN BY WED MORNING. A WEAKENING COLD FRONT SLIDES INTO NORTHERN WI/CENTRAL MN BY WED MORNING...BUT LIMITED MOISTURE AND MINIMAL INSTABILITY AHEAD OF IT. THE MON-TUE NIGHT PERIOD CONTINUES TO TREND DRY/QUIET WITH COOLER/MORE SEASONABLE TEMPS. MONDAY STILL APPEARS AS THE COOLEST DAY WITH SLOWLY MODERATING TEMPS TUE. COOLEST 925MB OVER THE AREA AROUND 12Z MON...BUT SOME NORTH GRADIENTS TO KEEP THE BOUNDARY LAYER STIRRED AND LOWS MON MORNING MOSTLY IN THE 50S. MON NIGHT THE CENTER OF THE HIGH DRIFTS OVERHEAD WITH LIGHT WINDS/CLEAR SKIES. 925MB TEMPS TUE MORNING IN THE 12C-15C RANGE...BUT THE LIGHT/CALM WINDS AND STRONG RADIATIONAL COOLING LOOK TO MAKE TUE MORNING THE COOLER OF THE MORNINGS...WITH LOWS IN THE MID 40S TO LOW 50S. RADIATIONAL LATE NIGHT/EARLY MORNING VALLEY FOG REMAINS A CONCERN CENTERED ON 12Z TUE. PREVIOUS FCST GRID SET ALREADY INCLUDED THIS AND APPEARS WELL TRENDED. USED A BLEND OF THE NUMERICAL GUIDANCE HIGHS/LOWS FOR MON...TUE/TUE NIGHT. TRENDED TOWARD COOLER OF GUIDANCE LOWS MON NIGHT WITH THE HIGH OVERHEAD. FOR WEDNESDAY THROUGH SATURDAY.../DAYS 4-7/... MEDIUM RANGE MODEL COMING INTO BETTER AGREEMENT WITH A SHORTWAVE TO DROP SOUTHEAST ACROSS THE EASTERN GREAT LAKES WED...KEEPING THE REGION UNDER NORTHWEST FLOW ALOFT AND THE RIDGE AXIS OVER THE WESTERN PLAINS INTO ALB/SASKAT. PATTERN SLOWLY PROGRESSES THU-SAT WITH RISING HGTS OVER THE UPPER MIDWEST...WHILE THE TROUGHING MOVING ACROSS THE NORTHERN ROCKIES DEVELOP STRONGER LEE TROUGHING BY LATE IN THE WEEK. DAY 4-7 FCST CONFIDENCE IS AVERAGE. IMPROVING MODEL CONSENSUS MOVES A COLD FRONT INTO THE AREA ON WED... DURING PEAK HEATING. MOISTURE REMAINS IN QUESTION...BUT TREND IS TOWARD MORE OF AN 850-700MB MOISTURE TRANSPORT/THETA-E CONVERGENCE SIGNAL...WITH INCREASING PW VALUES INTO THE AREA. MAY YET NEED A SMALL SHRA/TSRA CHANCE CENTERED ON WED AFTERNOON/EVENING BUT LEFT THESE PERIODS DRY FOR NOW. POST-FRONTAL CAN HIGH PRESSURE TO SETTLE ACROSS THE REGION FOR THU. MIXED SIGNALS BY FRI/SAT WITH THE STRENGTHENING LEE TROUGHING AND SOUTHWEST FLOW AHEAD OF IT PUSHING INCREASING MOISTURE/INSTABILITY INTO THE UPPER MIDWEST. MAY YET NEED SHRA/TSRA CHANCES FRI/SAT...DEPENDING ON WHERE ANY LOWER LEVEL THERMAL/MOISTURE RIDGING AND LOWER LEVEL TOUGHS/BOUNDARIES MAY END UP. LEFT THU NIGHT THRU SAT DRY FOR NOW PER THE MODEL/ENSEMBLE CONSENSUS. A WARM-UP ON WED AHEAD OF THE FRONT THEN A BIT OF A COOL- DOWN ON THU BEHIND THE FRONT...TEMPS GRADUALLY WARM FRI/SAT WITH THE LOWER LEVEL FLOW BECOMING SOUTH/SOUTHWEST AND THE RISING HGTS ALOFT. USED THE MODEL/ENSEMBLE CONSENSUS OF NUMERICAL GUIDANCE FOR HIGHS/ LOWS ON WED THRU SAT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 615 PM CDT SAT AUG 31 2013 THE COLD FRONT IS MAKING GOOD EASTWARD PROGRESS AND IS NOW MOVING INTO WESTERN MINNESOTA. LINE OF CONVECTION OUT AHEAD OF THE FRONT IS PRIMARILY MOVING EAST AND IF IT CONTINUES ON THIS PATH WOULD TRACK NORTH OF BOTH TAF SITES. MOST OF THE SHORT RANGE MESO MODELS CONTINUE TO INDICATE THIS LINE WILL DIMINISH AS IT MOVES EAST WITH WEAKENING CAPE AND AS IT GETS FARTHER AWAY FROM THE MAIN SHORT WAVE TROUGH. THIS WAS THE TREND SET FORTH IN THE PREVIOUS FORECASTS AND FOR NOW WILL STAY WITH THIS BUT WILL CLOSELY MONITOR THROUGH THE EVENING TO SEE IF THIS OCCURS OR NOT. THE FRONT DOES APPEAR TO BE MOVING FASTER THAN THE PREVIOUS FORECAST SO BROUGHT IN THE REMAINS OF THE CONVECTIVE LINE AS SHOWERS FOR THE LATE EVENING FOR A COUPLE OF HOURS. THE 31.21Z RAP AND 31.21Z HRRR TRY TO GENERATE MORE SHOWERS OVERNIGHT ALONG THE FRONT AS IT COMES THROUGH AND TO HONOR THIS...HAVE INCLUDED A VCSH FOR A COUPLE OF HOURS AFTER THE FRONTAL PASSAGE WHICH SHOULD OCCUR LATE TONIGHT. WINDS EXPECTED TO COME AROUND TO THE NORTHWEST AND INCREASE TO OVER 10 KNOTS BEHIND THE FRONT. A LARGE AREA OF CLOUDS BEHIND THE MAIN SURFACE LOW IS COVERING MUCH OF MANITOBA AND SASKATCHEWAN AND IS JUST STARTING TO MOVE ACROSS THE BORDER. PREVIOUS FORECAST HAD THESE COMING IN BY 12Z FOR BOTH TAF SITES WITH MVFR CEILINGS. LOOKING AT THE 850 MB RELATIVE HUMIDITY CHARTS FOR BOTH THE RAP AND 31.18Z NAM SUGGESTS THIS WAS TOO FAST AND THE MOISTURE IS NOT EXPECTED TO ARRIVE UNTIL EARLY TO MID AFTERNOON. BY THAT TIME...THE MIXING BEHIND THE FRONT MAY BE TOO STRONG AND DEEP TO ALLOW FOR MORE THAN JUST SCATTERED CLOUDS...SO HAVE REMOVED THE MVFR CEILINGS FOR NOW. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...RRS LONG TERM....RRS AVIATION...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
354 PM CDT FRI AUG 30 2013 .VERY SHORT TERM...TONIGHT AND SATURDAY. TONIGHT - CONFIDENCE...MEDIUM PLENTY OF CAPE POOLING AHEAD OF SOUTHWARD MOVING FRONTAL BOUNDARY. STORMS ARE ORGAN ZING AS BEST AS THEY CAN GIVEN THE LACK OF DECENT 0-6KM SHEAR AND SUSPECT MID LEVEL LAPSE RATES. HOWEVER PLENTY OF CAPE IN THE LOW LEVELS WITH GOOD LOW LEVEL LAPSE RATES WITH SURFACE/925 CONVERGENCE ALLOWING FOR SOME STRONGER WINDS AND HAIL. WATER VAPOR/RUC COMBO DOES SHOW A WEAK UPSTREAM WAVE RIDING IN FROM SRN MN AND NRN IA. HRRR SHOWING STORMS CLEARING THE FAR SOUTH AROUND 00Z OR SO. HOWEVER 4KM WRF-SPC AND 12Z ECMWF LINGER PRECIP ACROSS PORTIONS OF SC WI DEEPER INTO THE EVENING. BASED ON FRONTAL PROGRESSION WILL BANK ON A QUICKER EXIT OF PRECIP BASED ON OTHER MODELS. SO FRONTAL BOUNDARY EXITS TO THE SOUTH THIS EVENING TAKING ANY LINGERING STORMS WITH IT. WILL RETAIN HEAT ADVISORY FOR SOUTHERN TIER ONLY AS I-94 CORRIDOR AFFECTED BY OUTFLOW AND STORMS. SURFACE/925 COOL AIR ADVECTION THEN TAKES HOLD. NOT SO MUCH UP TO 850 MILLIBARS...BUT FROM 925 AND ON DOWN PRETTY STRONG SIGNAL AND THIS IS PLAUSIBLE GIVEN CONDITIONS UPSTREAM IN NORTHERN WISCONSIN. EXPECTING COOLER AND DRIER DEW POINTS TO ADVECT INTO THE AREA WITH THE EVOLVING POST-FRONTAL NORTH WINDS. LOW LEVEL WIND FLOW/DEGREE OF MIXING SUGGESTS THE EVOLUTION OF DENSE FOG NOT LIKELY. LOOKS MORE LIKE STRATUS POTENTIAL. SATURDAY - CONFIDENCE...MEDIUM HIGH PRESSURE SETTLES IN. MORNING FOG/LOW STRATUS POTENTIAL WILL GRADUALLY BURN OFF. NOT A BIG DROP OFF IN 850 TEMPS. NEVERTHELESS CU RULE SUPPORTIVE OF SCT COVERAGE AFTER MORNING STRATUS. 925 TEMPS PROGGD TO 20-23C. COMFORTABLY COOLER AND LESS HUMID. SO LOW TO MID 80S WITH MID/UPPER 70S IN THE FAR EAST WITH THE SUSTAINED ONSHORE FLOW. .SHORT TERM...SATURDAY NIGHT THROUGH MONDAY. SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. NEXT BEST CHANCE OF PRECIPITATION COMES WITH SHORT WAVE TROUGH AND COLD FRONT. STILL SOME DIFFERENCES IN CONFIGURATION OF SHORT WAVE THAT IMPACTS TIMING OF SURFACE TROUGH/COLD FRONT THROUGH REGION. WILL GO WITH BLENDED SOLUTION THAT BRINGS A CHANCE TO THE NW CWA BETWEEN 06Z AND 12Z SUNDAY...THEN HIGH CHANCE POPS ACROSS THE ENTIRE FORECAST AREA DURING THE DAY SUNDAY. SHOULD SEE LOW TO MID 80S HIGHS PRIOR TO ONSET OF PCPN. SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH. PRECIPITATION CHANCES LINGER INTO SUNDAY EVENING IN THE EAST WITH HIGH PRESSURE BUILDING IN BEHIND. LABOR DAY MORE FALL-LIKE WITH LOW TO MID 70 HIGHS. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. DRY WEATHER AS HIGH PRESSURE DOMINATES THE WESTERN GREAT LAKES REGION UNDER NORTHWEST FLOW REGIME. MODELS TRY TO BRUSH SW/SOUTHERN CWA WITH LIGHT QPF WITH A WEAK WAVE/WARM AIR ADVECTION BUT FOR NOW WILL LEAVE DRY. BELOW NORMAL TEMPERATURES WILL WARM BACK TOWARD NORMAL LEVELS...OR SLIGHTLY ABOVE...WEDNESDAY THROUGH THE REST OF THE EXTENDED. && .AVIATION/00Z TAFS/... THUNDERSTORM POTENTIAL THROUGH 00Z WITH FRONTAL BOUNDARY DROPPING IN FROM THE NORTH. WINDS WILL SHIFT TO THE NORTH IN THE WAKE OF THE FRONT WITH THE EVENING FROPA. WILL MONITOR STRATUS TRENDS IN THE COOL ADVECTION REGIME. EXPECT MVFR CEILINGS AND POTENTIAL FOR IFR LATER TONIGHT INTO EARLY SATURDAY. THINKING ENOUGH MIXING WILL INHIBIT DENSE FOG FORMATION. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR WIZ067>072. LM...NONE. && $$ TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR SATURDAY NIGHT THROUGH FRIDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 AM CDT FRI AUG 30 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 320 AM CDT FRI AUG 30 2013 MAIN FORECAST CONCERNS INCLUDE SHOWER/THUNDERSTORM CHANCES TODAY...THEN AREAS OF FOG LATE TONIGHT. WATER VAPOR IMAGERY SHOWING A WELL-DEFINED MID-LEVEL TROUGH MAKING ITS WAY THROUGH WESTERN LAKE SUPERIOR/NORTHWEST WI. AT THE SURFACE...A COLD FRONT EXTENDED FROM FROM WESTERN LAKE SUPERIOR TO JUST EAST OF THE TWIN CITIES...AND INTO SOUTHWEST MN. RADAR MOSAIC SHOWING ISOLATED-SCATTERED ELEVATED SHOWERS AND THUNDERSTORMS ALONG THIS FRONTAL BOUNDARY AS IT SINKS SOUTHEASTWARD INTO THE AREA. FOR TODAY...WILL BE WATCHING THE COLD FRONT AS IT MAKES PASSAGE THROUGH THE AREA. SHOULD BE SOME ONGOING ISOLATED-SCATTERED SHOWERS/THUNDERSTORMS ALONG THE FRONT AS IT PRESSES INTO THE AREA. GFS/NAM DETERMINISTIC MODELS ALONG WITH THE HRRR/HIRES ARW-EAST WRF MODELS SHOWING THIS CONVECTION UPSCALING A BIT ACROSS PORTIONS OF FAR SOUTHERN WI INTO NORTHEAST IA THIS AFTERNOON AS THE FRONT PUSHES INTO A VERY MUGGY AIRMASS WITH 0-1KM MLCAPE OF 2500-3500J/KG ALONG WITH 0-3KM BULK SHEAR IN THE 20 TO 30KT RANGE. BASED ON THIS SIGNAL...CANNOT RULE OUT THE THREAT FOR A FEW SEVERE THUNDERSTORMS ACROSS THIS AREA WITH DAMAGING WINDS AND HAIL BEING THE MAIN THREATS. ALSO WILL BE GOING WITH A HEAT ADVISORY THIS AFTERNOON FOR PORTIONS OF FAR SOUTHWEST WI INTO NORTHEAST IA BASED ON HEAT INDICES CREEPING INTO THE 100-105 DEGREE RANGE. OTHERWISE BEHIND THE FRONT/ACROSS THE REST OF THE FORECAST AREA...LOOK FOR SOME RELIEF TO THE MUGGY CONDITIONS WITH DEW POINTS LOWERING INTO THE 65-70 DEGREE RANGE AND TEMPERATURES TOPPING OFF IN THE 80-90 DEGREE RANGE. LOOK FOR THE COLD FRONT/SHOWER AND THUNDERSTORM CHANCES TO PUSH SOUTHWARD OUT OF THE AREA THIS EVENING WITH A RIDGE OF HIGH PRESSURE BUILDING OVERHEAD THROUGH THE OVERNIGHT HOURS. LIGHT-CALM WINDS ALONG WITH COOLING LOWER BOUNDARY LAYER WILL SET UP FAVORABLE CONDITIONS FOR AREAS OF FOG...MAINLY ALONG AND NORTH OF I-94 WHERE RECENT RAINS HAVE FALLEN AND IN RIVER VALLEYS ACROSS THE REST OF THE AREA. OVERNIGHT LOWS ARE EXPECTED TO DROP OFF IN THE UPPER 50S TO THE MIDDLE AND UPPER 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 320 AM CDT FRI AUG 30 2013 NORTHWEST FLOW ALOFT BRINGS ANOTHER FAIRLY VIGOROUS MID-LEVEL SHORTWAVE TROUGH/SURFACE COLD FRONT INTO THE REGION SATURDAY THROUGH SUNDAY FOR A DECENT CHANCE OF SHOWERS AND THUNDERSTORMS. TIMING OF THE FRONTAL PASSAGE BY LATE MORNING/EARLIER IN THE AFTERNOON SHOULD MITIGATE SEVERE POTENTIAL. WILL HAVE TO KEEP AN EYE ON THE TIMING OF THE FRONT AS ANY SLOWING TO LATER IN THE AFTERNOON COULD INCREASE THE SEVERE POTENTIAL. OTHERWISE...HIGH SUNDAY ARE EXPECTED TO TOP OFF ONLY IN THE MIDDLE 70S TO THE MIDDLE 80S...OR JUST A FEW DEGREES ABOVE NORMAL. COOLER TEMPERATURES ON TAP FOR SUNDAY NIGHT BEHIND THE FRONTAL PASSAGE WITH OVERNIGHT LOWS DROPPING INTO THE MIDDLE TO UPPER 50S. FOR MONDAY THROUGH THURSDAY...GFS AND ECMWF SHOW THE MIDDLE/UPPER LEVEL RIDGE BUILDING ACROSS THE INTERMOUNTAIN WEST WITH OUR AREA IN DRY NORTHWEST FLOW ALOFT. COOLER SHOT OF AIR WITH 850MB TEMPERATURES IN THE 5-10C RANGE MOVES OVER THE AREA ON MONDAY FOR HIGHS IN THE UPPER 60S TO THE MIDDLE 70S. TEMPERATURES LOOK TO HOLD RIGHT AROUND NORMAL LEVELS FOR TUESDAY THROUGH THURSDAY WITH HIGHS IN THE MIDDLE 70S TO AROUND 80S AND OVERNIGHT LOWS MAINLY IN THE 50S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1143 PM CDT THU AUG 29 2013 AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE DIMINISHING FRIDAY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING FOR WIZ061. MN...NONE. IA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS EVENING FOR IAZ018-019-029-030. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT THU AUG 29 2013 .SHORT TERM...(TONIGHT THROUGH FRIDAY TONIGHT) ISSUED AT 328 PM CDT THU AUG 29 2013 MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT/ FRI...TEMPS/HEAT/HUMIDITY FRIDAY. DATA ANALYSIS AT 18Z HAD HIGH PRESSURE OVER LOWER MI AND LOW PRESSURE OVER EASTERN ND WITH TOUGHING FROM LK WINNIPEG TO EASTERN CO. DIFFUSE/ILL-DEFINED WARM FRONT WAS LOCATED FROM THE ND LOW TO NEAR THE MS RIVER THRU THE FCST AREA. MAIN FORCING/LIFT/MOISTURE CONVERGENCE WAS INTO NORTHERN MN...WHERE A MATURE CONVECTIVE COMPLEX WAS MOVING INTO WESTERN LK SUPERIOR. ACROSS WI/IA/REST OF MN...WARM TEMPS IN THE 800-700MB LAYER CONTINUED TO CAP THE AIRMASS EARLY THIS AFTERNOON...EVEN WITH SFC DEW POINTS IN THE UPPER 60S/LOW 70S AND TEMPS IN THE MID 80S/LOW 90S. LAPS SOUNDINGS SHOWING CONVECTIVE TEMPS IN THE 98F-108F RANGE. NO BIG PROBLEMS NOTED WITH 29.12Z INITIALIZATIONS. GFS WITH ITS USUAL SLIGHTLY OFF SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS VALLEY. SOLUTIONS REASONABLY SIMILAR FOR TONIGHT THRU FRI NIGHT WITH THE MAIN FORCING/LIFT SHRA/TSRA CHANCE PASSING NORTH OF THE FCST AREA THEN A WEAK COLD FRONT TO SLIDE ACROSS THE AREA FRI. DPROG/DT OF 500MB HGTS AT 29.12Z SHOWED THE MODEL RUNS OF 27.12Z AND 28.12Z VERIFIED QUITE WELL ACROSS NOAM...WITH STRONGER OF EARLIER RUNS BETTER ON THE SHORTWAVE APPROACHING LK WINNIPEG. TREND FAVORS STRONGER OF EARLIER RUNS AS THE LK WINNIPEG WAVE CROSSES LK SUPERIOR THRU TONIGHT...AND STRONGER WITH THE NEXT WAVE TO TOP THE MID NOAM RIDGE MOVING INTO WA/SOUTHERN BC. TREND CONTINUES TO FAVOR STRONGER/FASTER OF EARLIER MODELS AS THIS WAVE MOVES INTO SASKAT/ EASTERN MT BY 12Z SAT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL TO BE REASONABLE WITH THE SFC MASS FIELDS OVER THE CENTRAL CONUS. PER WV IMAGERY...NON-NAM MODELS LOOKED BETTER WITH THE SHORTWAVE PASSING ACROSS SOUTHERN MANITOBA. MODELS ALL GENERALLY TOO FAR SOUTH WITH THE 12-18Z PRECIP IN EASTERN MN/WESTERN WI...AND NOT STRONG ENOUGH WITH THE TSRA COMPLEX NEAR KDLH. NO ONE MODEL LOOKED PREFERRED THIS CYCLE. WITH A RATHER TIGHT CONSENSUS AMONG THE MODELS...EVEN WITH THE TRENDS ON THE SHORTWAVES OF INTEREST... FAVORED THE MODEL/ENSEMBLE CONSENSUS. SHORT-TERM FCST CONFIDENCE IS GOOD THIS CYCLE. IN THE SHORT TERM...FIRST SHORTWAVE TRACKS EAST/SOUTHEAST AND ACROSS LK SUPERIOR TONIGHT. BULK OF FORCING/CONVERGENCE/LIFT WITH THIS FEATURE...AND HIGHER SHRA/TSRA CHANCES PASS NORTHEAST OF OR JUST CLIP THE NORTHEAST END OF THE FCST AREA. ATTENDANT SFC LOW/TROUGH DRAGS A COLD FRONT INTO THE AREA LATER TONIGHT...TO NEAR A KAUW-KLSE- KMCW LINE BY 12Z FRI. NOT MUCH FOR LOWER LEVEL THERMO-DYNAMIC FORCING WITH THIS FRONT/BOUNDARY AS IT PUSHES INTO/ACROSS THE FCST AREA LATE TONIGHT/FRI MORNING. SOME WEAK 925MB THETA-E CONVERGENCE... BUT THESE PARCELS FIGHTING CIN TO 650MB OR NO CAPE AT ALL. THUS MODELS ONLY GENERATE SOME ISOLATED/WDLY SCT SHRA/TSRA WITH THIS FRONTAL PASSAGE. LEFT SOME 20-40 PERCENT SHRA/TSRA CHANCES OVER THE NORTHEAST END OF THE FCST AREA TONIGHT. ONLY CARRIED 20 PERCENT SHRA/TSRA CHANCES OVER THE CENTRAL/WEST PARTS OF THE FCST AREA WITH THE FRONTAL PASSAGE LATE TONIGHT/FRI MORNING. LEFT SOME 20-40 PERCENT SHRA/TSRA CHANCES OVER THE SOUTHEAST HALF OF THE FCST AREA FRI AFTERNOON INTO FRI EVENING...DUE TO PROXIMITY OF THE BOUNDARY AND ML CAPE VALUES RISING INTO THE 1.5. TO 2.5 K J/KG RANGE. 0-6KM BULK SHEAR IN THE 25-30KT RANGE FRI AFTERNOON...ISOLATED SEVERE STORMS WITH A HAIL OR WIND THREAT CANNOT BE RULED OUT. AHEAD OF THE FRONT...HEAT INDICES WILL AGAIN CLIMB INTO THE 90-100 RANGE OVER THE SOUTHEAST THIRD OF THE FCST AREA FRI AFTERNOON/EARLY FRI EVENING. MAY YET NEED A HEAT ADVISORY FOR THE SOUTHEAST END OF THE FCST AREA CENTERED ON FRI AFTERNOON...BUT IF SCT SHRA/TSRA DEVELOP AND SKIES BECOME MORE CLOUDY THAN SUNNY...HEAT INDICES WOULD NOT REACH 100...AT LEAST FOR MORE THAN AN HOUR AT ANY ONE SPOT. WEAK BUBBLE HIGH SETTLES OVER THE AREA FRI NIGHT. WITH LIGHT WINDS... CLEAR/MOSTLY CLEAR SKIES...COOLER 925-850MB TEMPS AND STRONG RADIATIONAL COOLING EXPECTED...CONTINUED THE MENTION OF PATCHY TO AREAS OF FOG IN GRIDS FOR LATER FRI NIGHT INTO EARLY SAT MORNING. USED A MODEL/ENSEMBLE CONSENSUS OF LOWS/HIGHS FOR TONIGHT THRU FRI NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 328 PM CDT THU AUG 29 2013 MAIN FORECAST CONCERNS FOR SAT THRU SUN NIGHT...TEMPERATURES/HEAT POTENTIAL SATURDAY...SHRA/TSRA CHANCES SAT NIGHT/SUN. THE STRONGER/TREND WITH THE MT/SASKAT SHORTWAVE CONTINUES SAT/SAT NIGHT AS IT MOVE INTO MN/WESTERN ONT BY 12Z SUN...THEN PASSES ACROSS THE REGION SUN...PUSHING A RATHER STRONG COLD FRONT THRU THE AREA. AGAIN WITH A RATHER TIGHT CONSENSUS/SHIFT BY ALL MODELS... FAVORED THE MODEL/ENSEMBLE CONSENSUS FOR SAT THRU SUN NIGHT. WEAK HIGH PRESSURE REMAINS OVER THE AREA SAT. WITH DIURNAL WARMING/ MIXING...AND SOME DRIER 925-850MB AIR OVER THE REGION...SFC DEW POINTS LOOKING TO BE MORE IN THE LOW-MID 60S SAT AFTERNOON. SAT AFTERNOON HEAT INDICES TRENDING TO TOP OUT MORE IN THE 85-90 RANGE... FOR A LITTLE MORE RELIEF FROM THE RECENT HEAT/HUMIDITY. MOISTURE TRANSPORT INCREASES INTO THE AREA SAT NIGHT WITH PW VALUES BACK IN THE 1.5 INCH RANGE BY 12Z SUN. STRONGER/DEEPER LOWER LEVEL THERMO- DYNAMIC FORCING INDICATED WITH APPROACH/PASSAGE OF THE TROUGH/FRONT LATE SAT NIGHT/SUN MORNING. THIS ALONG WITH SOME 400-200MB PV ADVECTION AHEAD OF THE STRONGER SHORTWAVE...AND MU CAPE VALUES OF AROUND 1K J/KG LIFTING 900-800MB PARCELS. CONTINUED/RAISED SHRA/ TSRA CHANCES CENTERED ON LATE SAT NIGHT/SUN MORNING IN THE 30- 50 PERCENT RANGE. TRENDED SHRA/TSRA CHANCES DOWN SUN AFTERNOON WITH PASSAGE OF THE FRONT/LIFT AND LOWER LEVEL COLD ADVECTION/DRYING SPREADING SOUTHEAST ACROSS THE AREA. SOME BRISK/GUSTY NORTHWEST WINDS SUN AFTERNOON WITH THE COLD ADVECTION AND MIXING TO AT LEAST 850MB. DRY/COOLER SUN NIGHT AS CAN HIGH PRESSURE SETTLES INTO THE NORTHERN PLAINS/WESTERN GREAT LAKES AND 850MB TEMPS FALL INTO THE 8C-12C RANGE BY MON MORNING. AGAIN USED A MODEL/ENSEMBLE CONSENSUS OF THE NUMERICAL GUIDANCE FOR HIGHS/LOWS SAT THRU SUN NIGHT. FOR MONDAY/LABOR DAY THROUGH THURSDAY.../DAYS 4-7/... LATEST MEDIUM RANGE MODEL RUNS REMAIN IN GOOD AGREEMENT MONDAY WITH RATHER STRONG TROUGHING TO BE OVER ONT/GREAT LAKES AND RIDGING TO BE BUILDING NORTHWARD INTO SASKAT/MANITOBA. GOOD CONSISTENCY FOR HGTS TO RISE OVER THE REGION TUE AS THE TROUGHING MOVES INTO EASTERN NOAM...BUT MN/WI/IA TO REMAIN UNDER RATHER STRONG NORTHWEST FLOW ALOFT. 29.00Z WERE DIFFERENT FOR WED/THU...WITH STRENGTH OF A SHORTWAVE TROUGH TO DROP DOWN THE EAST SIDE OF THE RIDGE AND INTO THE EASTERN NOAM TROUGH. 29.12Z MODELS HAVE TRENDED TOWARD A COMPROMISE ON THE TIMING/STRENGTH OF THIS FEATURE AND THE TROUGHING OVER EASTERN NOAM WED/THU. 29.12Z GFS/ECMWF WITH BETTER CONSENSUS ON THE NEXT TROUGHING MOVING INTO THE NORTHWEST CONUS/WESTERN CAN ON DAYS 6/7 TOO. FCST CONFIDENCE GOOD FOR MON/TUE THEN AVERAGE WED/THU. STRONG PASSING COLD FROM SUNDAY USHERS A COOLER/DRIER CAN HIGH PRESSURE SYSTEM INTO THE UPPER MIDWEST FOR MON/TUE. BY LABOR DAY MORNING...925MB TEMPS IN THE 11C-14C RANGE ACROSS THE FCST AREA. THESE TEMPS SLOWLY MODERATE THRU MON/TUE BUT ONLY RECOVER TO THE 19C- 21C RANGE BY TUE EVENING. MON/TUE STILL LOOKING LIKE A A COUPLE OF COOLER...COMFORTABLE DAYS COMPARED TO THE PAST SEVERAL DAYS. LIKE PREVIOUS FORECASTER STATED...MAY NEED A VALLEY FOG MENTION CENTERED ON DAYBREAK TUE...BUT WILL LEAVE THAT OUT OF THE GRIDS FOR NOW GIVEN THE SENSITIVITY OF VALLEY FOG TO LOWER LEVEL/BOUNDARY LAYER NUANCES. EVEN WITH SHORTWAVE/TROUGH STRENGTH DIFFERENCES BY WED...BOTH GFS/ ECMWF PUSH A COLD FRONT SOUTHEAST ACROSS THE REGION WED. MOISTURE/ CAPE CONTINUE TO LOOK LIMITED AHEAD OF/WITH THIS FEATURE. SMALL SHRA/TSRA CHANCE AT BEST WED BUT WILL LEAVE THIS PERIOD DRY FOR NOW PER THE MODEL/ENSEMBLE CONSENSUS. NORTHWEST FLOW ALOFT SENDS ANOTHER CAN HIGH SOUTH INTO THE REGION FOR THU BUT CORE OF THE COOLEST 925-850MB AIR WITH THIS HIGH REMAINS NORTH/EAST OF THE FCST AREA AS IT BUILDS IN. EVEN WITH SOME MODEL DIFFERENCES... GUIDANCE HIGHS/LOWS FOR MON-THU NOT THAT DIFFERENT AND USED THE MODEL/ENSEMBLE CONSENSUS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1143 PM CDT THU AUG 29 2013 AN AREA OF SURFACE LOW PRESSURE WAS OVER WESTERN LAKE SUPERIOR LATE THIS EVENING WITH A COLD FRONT FROM NORTHEAST MINNESOTA INTO SOUTHEAST SOUTH DAKOTA. ALMOST ALL THE CONVECTION IS NOW WELL OUT AHEAD OF THE SURFACE LOW ALONG THE WARM FRONT OVER NORTHEAST WISCONSIN. ONE LAST AREA OF CONVECTION JUST AHEAD OF THE COLD FRONT OVER NORTHWEST WISCONSIN IS CLOSELY TIED TO THE UPPER LEVEL SHORT WAVE TRACKING ACROSS MINNESOTA. THIS WAVE WILL CONTINUE TO MOVE OFF TO THE EAST THROUGH THE NIGHT WITH THE AREA OF CONVECTION SLIPPING TO THE SOUTHEAST. WILL BE INTERESTING TO SEE HOW FAR THIS CONVECTION CAN SURVIVE AS IT GETS FARTHER AWAY FROM THE WAVE...DEEPER INTO THE CAPPING AND WITH THE LOW LEVEL JET FEEDING THE NORTHEAST WISCONSIN COMPLEX. EVEN IF IT DOES SURVIVE...CURRENT MOVEMENT WOULD TAKE IT NORTHEAST OF BOTH TAF SITES. SOME DIFFERENCES BETWEEN THE 31.00Z NAM AND 31.03Z RAP ON WHETHER THE CAP WILL REMAIN IN PLACE AHEAD OF THE FRONT. THE NAM INDICATES IT WILL WITH THE FRONT PASSING THROUGH DRY WHILE THE RAP WANTS TO WEAKEN THE CAP WITH SOME SHOWERS FORMING ALONG AS IT PASSES THROUGH. CURRENT SATELLITE SHOWS A GENERAL LACK OF CLOUDS ALONG MUCH OF THE FRONT ACROSS CENTRAL AND SOUTHWEST MINNESOTA INDICATING THE CAP IS STILL IN PLACE SO WILL LEAN TOWARD THE NAM AND MAINTAIN CONTINUITY WITH THE FRONT PASSING THROUGH DRY WITH JUST SOME SCATTERED CLOUDS ALONG IT. NORTHWEST WINDS BEHIND THE FRONT WILL INCREASE TO AROUND 10 KNOTS DURING THE AFTERNOON BEFORE DIMINISHING FRIDAY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...RRS LONG TERM....RRS AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1030 AM MDT FRI AUG 30 2013 .UPDATE... ISSUED AT 1022 AM MDT FRI AUG 30 2013 STILL SEEING LOW TO MID 60 DEWPOINTS IN THE PANHANDLE THIS AFTERNOON. LATEST HRRR RADAR COMPOSITE FORECAST SHOWING SHOWERS DEVELOPING OVER THE LARAMIE RANGE AROUND 20Z AND THEN DRIFTING OFF AND MOVING EAST INTO THE PANHANDLE AROUND THE 22Z TO 02Z TIME FRAME. WENT AHEAD AND INCREASED POPS IN THE PANHANDLE TO CHANCE/SCATTERED CATEGORY FOR THIS TIME FRAME. THOUGH PWATS ARE NOT FORECAST TO BE TOO HIGH...GENERALLY AROUND .8 INCHES...FORECAST STORM MOTIONS ARE FAIRLY SLOW...GENERALLY UNDER 6KTS...SO WE COULD SEE SOME ISOLATED HEAVY RAIN SHOWERS OUT THAT WAY. ALSO A FEW STRONG TO SEVERE THUNDERSTORMS ARE NOT TOTALLY OUT OF THE QUESTION WITH AFTERNOON CAPE VALUES AROUND 1500 TO 200 J/KG. UPDATES HAVE BEEN SENT. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 335 AM MDT FRI AUG 30 2013 ANOTHER HOT DAY TO END THE WORK WEEK WITH HIGH TEMPERATURES MAINLY IN THE 90S ACROSS THE PLAINS AND AROUND 100 DEGREES FOR SOME LOCATIONS. HIGHER ELEVATIONS WILL GENERALLY SEE HIGH TEMPERATURES IN THE 80S. THE UPPER LEVEL RIDGE WHICH IS RESPONSIBLE FOR THE ABOVE NORMAL TEMPERATURES WILL TEMPORARILY BREAK DOWN THIS WEEKEND...PROVIDING A LITTLE RELIEF TO THE HOT WEATHER BUT THE RIDGE WILL REBUILD EARLY NEXT WEEK WITH DAYTIME TEMPERATURES WELL ABOVE NORMAL WITH SOME RECORD HIGHS A GOOD POSSIBILITY. A SUBTLE SHORTWAVE CURRENTLY MOVING ACROSS NIOBRARA COUNTY AND FAR SOUTHWEST SOUTH DAKOTA HAS PRODUCED A FEW SHOWERS AND EVEN SOME LIGHTING STRIKES EARLY THIS MORNING. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL MAINLY PUSH EAST OF THE AREA AFTER SUNRISE AS THE WAVE EXITS THE FORECAST AREA. MODELS DO SHOW AND WEAK MID LEVEL FRONT HANGING OVER THE NEBRASKA PANHANDLE AT 12Z BUT FORCING WEAK ENOUGH THAT NOT EXPECTING MUCH MORE THAN SOME ACCAS CLOUDS...MAYBE A FEW SPRINKLES. MAIN CHANCE FOR PRECIPITATION WILL HOLD OFF UNTIL THIS AFTERNOON AS CONVECTIVE TEMPERATURES ARE REACHED. SHOULD SEE CONVECTION INITIATE FIRST OVER THE MOUNTAINS THEN MOVING OFF THE MOUNTAINS BY MID AFTERNOON. MAY ALSO SEE STORMS FIRE OFF OVER THE NEBRASKA PANHANDLE MID AFTERNOON. SEVERE THUNDERSTORM POTENTIAL IS LOW BUT NOT COMPLETELY OUT OF THE QUESTION INTO THE NEBRASKA PANHANDLE. 0-6 KM SHEAR MAY PUSH 40 KTS OVER NORTHERN PORTIONS OF THE FORECAST AREA WITH SURFACE BASED CAPE 1000-1500 J/KG INTO THE NEBRASKA PANHANDLE. IF THUNDERSTORMS DEVELOP OVER THE PANHANDLE...ONE OR TWO MARGINALLY SEVERE THUNDERSTORMS POSSIBLE. GUSTY WINDS WILL BE THE MAIN CONCERN FARTHER WEST WHERE THE TYPICAL INVERTED-V SOUNDING WILL ONCE AGAIN BE IN PLACE. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 335 AM MDT FRI AUG 30 2013 QUITE WARM CONDITIONS EXPECTED ACROSS THE CWA DURING THE PERIOD AS AN UPPER HIGH DRIFTS OVER THE SOUTHERN AND CENTRAL ROCKIES EARLY IN THE WEEK THEN SHIFTS EAST OVER THE PLAINS THURSDAY. ISOLATED MAINLY MTN CONVECTION POSSIBLE EARLY IN THE WEEK WHERE BEST INSTABILITY SHOULD BE REALIZED THEN AS THE WEEK PROGRESSES SOME SUBTROPICAL MOISTURE SHOULD SPREAD OVER AT LEAST SE WYOMING ALLOWING FOR AN UPTICK IN CONVECTION THERE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 515 PM MDT THU AUG 29 2013 VFR CONDITIONS EXPECTED OVERALL THROUGH THE TAF PERIOD. ISOLATED SHOWERS AND A FEW STORMS WILL MOVE ACROSS THE AREA THIS AFTERNOON INTO THIS EVENING. BRIEF GUSTY WINDS AND MVFR VSBYS POSSIBLE WITH ANY STORMS. && .FIRE WEATHER... ISSUED AT 335 AM MDT FRI AUG 30 2013 FIRE WEATHER CONCERNS ARE MINIMAL AS WINDS WILL REMAIN ON THE LIGHT SIDE THE NEXT SEVERAL DAYS. THE HOT AND DRY CONDITIONS DOES MAKE THE POTENTIAL FOR FIRE STARTS A GREATER RISK...SUCH THAT LIGHTNING WITH THUNDERSTORMS DOES POSE SOME FIRE START THREAT THE NEXT FEW AFTERNOONS. NOT EXPECTING WIDESPREAD DRY LIGHTNING BUT A FEW DRY STRIKES ARE POSSIBLE MAINLY INTO SOUTHEAST WYOMING WEST OF THE LARAMIE RANGE. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...CLAYCOMB SHORT TERM...LIEBL LONG TERM...RE AVIATION...RE FIRE WEATHER...LIEBL
AREA FORECAST DISCUSSION
NWS ALBANY NY
439 AM EDT SUN SEP 1 2013 .SYNOPSIS... A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 435 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG IT HAS SHIFTED DOWN STREAM INTO SRN NEW ENGLAND. SOME DUAL POL QPE VALUES OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE SRN TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND. THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS REMAIN MUGGY FOR THE OPENING DAY OF SEPT. THE MORNING SHOULD BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST 3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL /1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED CONVECTION. ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS. LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY. PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM 500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO 25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE MONITORED. OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND U60S TO M70S OVER THE HIGH PEAKS. MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES. TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH SOME U40S OVER THE MTNS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD. WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5 DEGREES BELOW NORMAL. TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP. HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW PASSES TO OUR NORTH. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE BOUNDARY. THE RADAR IS QUIET ACROSS THE FORECAST AREA AT THIS TIME AND A LULL IN THE CONVECTION IS EXPECTED ACROSS THE LOCAL AREA INTO THIS AFTERNOON. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND DISSIPATE. CHANCES FOR CONVECTION WILL INCREASE MID TO LATE AFTERNOON AND ESPECIALLY TONIGHT AS A STRONGER SHORT WAVE APPROACHES WITH HEIGHT FALLS OCCURRING ACROSS THE REGION. MVFR TO LIFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE TO FOG AND CIGS. CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASES. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY NIGHT. OUTLOOK... MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO TUESDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT. EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY. LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON SATURDAY AND THIS MORNING. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY. RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3 INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE TO MONITORED FOR ANY HYDRO ISSUES. COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...IAA FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
153 AM EDT SUN SEP 1 2013 .SYNOPSIS... A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW PRESSURE OVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30 KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW SPOTS. THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING CONVECTION. A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER COUNTY AS OF 05Z. PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES. THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED. THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO SLIGHTLY BELOW NORMAL. FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT. WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES. ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS ON SATURDAY WITH THE FRONTAL PASSAGE. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE BOUNDARY. A CLUSTER OF SHOWERS AND THUNDERSTORMS BETWEEN KPSF AND KPOU WILL CONTINUE TO MOVE EASTWARD IN ASSOCIATION WITH A SHORT WAVE TROUGH WITH ADDITIONAL SCATTERED CONVECTION DEVELOPING JUST TO THE NORTH WHICH WILL IMPACT KPSF. ONCE THE SHORT WAVE TROUGH MOVES OFF TO THE EAST EXPECTING A LULL IN THE CONVECTION WELL INTO THIS AFTERNOON. GUIDANCE INDICATES THE BOUNDARY WILL WEAKEN AND DISSIPATE OVER THE AREA. CHANCES FOR CONVECTION WILL INCREASE MID/LATE THIS AFTERNOON AND ESPECIALLY THIS EVENING AS A STRONGER SHORT WAVE APPROACHES CAUSING HEIGHT FALLS ACROSS THE REGION. MVFR/IFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE TO FOG AND CIGS WITH AN IMPROVEMENT BY LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING TO MVFR AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASES. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN TONIGHT. OUTLOOK... TUE: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. TUE NIGHT-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL. THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND MONDAY. THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING. HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING. THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20 MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE WEEKEND. RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE OF THE RAIN. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SND/WASULA NEAR TERM...HWJIV/WASULA SHORT TERM...SND LONG TERM...SND AVIATION...IAA FIRE WEATHER...SND HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
140 AM EDT SUN SEP 1 2013 .SYNOPSIS... A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW PRESSURE OVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30 KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW SPOTS. THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING CONVECTION. A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER COUNTY AS OF 05Z. PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES. THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED. THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO SLIGHTLY BELOW NORMAL. FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT. WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES. ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS ON SATURDAY WITH THE FRONTAL PASSAGE. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS REGION WITH THE MORE UNSTABLE AIR LOCATED TO THE SOUTH AND EAST OF THE BOUNDARY. A CLUSTER OF SHOWERS AND THUNDERSTORMS BETWEEN KPSF AND KPOU WILL CONTINUE TO MOVE EASTWARD IN ASSOCIATION WITH A SHORT WAVE TROUGH. ONCE THE SHORT WAVE TROUGH MOVES OFF TO THE EAST EXPECTING A LULL IN THE CONVECTION WELL INTO THIS AFTERNOON. GUIDANCE INDICATES THE BOUNDARY WILL WEAKEN AND DISSIPATE OVER THE AREA. CHANCES FOR CONVECTION WILL INCREASE MID/LATE THIS AFTERNOON AND ESPECIALLY THIS EVENING AS A STRONGER SHORT WAVE APPROACHES CAUSING HEIGHT FALLS ACROSS THE REGION. MVFR/IFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS DUE TO FOG AND CIGS WITH AN IMPROVEMENT BY LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING TO MVFR AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASES. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN TONIGHT. OUTLOOK... TUE: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. TUE NIGHT-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL. THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND MONDAY. THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING. HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING. THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20 MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE WEEKEND. RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE OF THE RAIN. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SND/WASULA NEAR TERM...HWJIV/WASULA SHORT TERM...SND LONG TERM...SND AVIATION...IAA FIRE WEATHER...SND HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
124 AM EDT SUN SEP 1 2013 .SYNOPSIS... A WARM AND HUMID AIR MASS WILL REMAIN OVER EASTERN NEW YORK AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A WEAK DISTURBANCE WILL PRODUCE SHOWERS AND THUNDERSTORMS THIS MORNING WELL SOUTH AND EAST OF THE CAPITAL DISTRICT WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 122 AM EDT...A CLUSTER OF STRONG THUNDERSTORMS DEVELOPED OVER THE MID HUDSON VALLEY...SRN TACONICS...NW CT AND SRN BERKSHIRES AHEAD OF A SFC TROUGH...AND A PASSING WEAK WAVE OF LOW PRESSUREOVER THE PAST FEW HOURS. THE LATEST SPC MESO PAGE SHOWED A RESPECTABLE INSTABILITY AXIS OF 1000-1500 J/KG WHICH THIS LIFTING MECHANISM TAPPED INTO. NARROW 50 DBZ REF CORES HAVE REACHED 25-30 KFT AGL OCCASIONALLY WITH SOME VERY HVY RAINFALL...AS PWATS IN THIS CORRIDOR ARE IN THE 1.50 TO 1.90 INCH RANGE. THE POPS HAVE BEEN RAISED TO HIGH CHC AND LIKELY IN THESE AREAS FOR ANOTHER HOUR OR TWO...AND THIS CLUSTER WILL PASS EAST INTO THE CT RIVER VALLEY AND SRN NEW ENGLAND. SEVERAL SPS STATEMENTS HAVE BEEN USED TO ADDRESS THIS CLUSTER OF THUNDERSTORMS...AS WELL AS A FEW FLOOD ADVISORIES WHERE A QUICK COUPLE OF INCHES HAVE OCCURRED IN A FEW SPOTS. THE LATEST 3KM HRRR FINALLY CAUGHT ONTO THIS CONVECTION...AND DOES HAVE IT DIMINISHING BY 07Z OR SO. THE POPS HAVE BEEN REDUCED TO SLIGHT CHC OR NOTHING FURTHER NORTH AND WEST OF THE ONGOING CONVECTION. A FEW SHOWERS/SPRINKLES HAVE POPPED UP IN RENSSELAER COUNTY AS OF 05Z. PATCHY FOG HAS BEEN ADDED TO THE FCST AREA WITH THE WATER VAPOR LOOP SHOWING NOTABLE DRYING ALOFT WITH THE PASSAGE OF THE SFC TROUGH AND MID LEVEL SHORT-WAVE. LOWS TEMPS WILL BE ON THE BALMY SIDE IN THE HUMID AIR MASS...WITH WIDESPREAD 60S TO L70S. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... SHOWERS AND THUNDERSTORMS SHOULD DIMINISH BY MIDNIGHT. SOME CLEARING OVER WESTERN NY NOW SHOWING UP ON SATELLITE SHOULD WORK ITS WAY EAST AND LEAD TO PATCHY CLOUDS LATE TONIGHT. SOME DENSE FOG LIKELY WHERE CLOUDS BREAK AS AIRMASS IS VERY MOIST AND NIGHTS ARE GETTING LONGER. FOR SUNDAY...CLOUDS AND FOG EXPECTED DURING THE MORNING...BUT WEAK RIDGING ALOFT SHOULD PROVIDE FOR SOME SUBSIDENCE AND BREAKS IN THE CLOUDS. NO STRONG TRIGGER FOR THUNDERSTORMS ON SUNDAY...BUT WITH WARM HUMID AIRMASS IN PLACE...THERE IS A CHANCE OF AFTERNOON POP UP SHOWERS AND THUNDERSTORMS. FOR SUNDAY NIGHT...MODELS INDICATE A STRONG SHORTWAVE WILL ROTATE AROUND THE UPPER LEVEL LOW OVER THE UPPER GREAT LAKES. THIS SHORTWAVE WILL CROSS THE ALBANY FORECAST AREA LATE SUNDAY NIGHT AND MONDAY MORNING. DYNAMICS LOOK STRONG WITH THIS FEATURE AND WITH MOIST UNSTABLE AIRMASS IN PLACE SHOWERS AND STORMS CAN BE EXPECTED. THERE MAY BE A LULL DURING THE MIDDLE OF THE DAY ON MONDAY BEFORE THE COLD FRONT APPROACHES FROM THE WEST LATER IN THE DAY PROVIDING LIFT FOR ANOTHER ROUND OF SHOWERS AND STORMS. AT THIS TIME...RAINFALL FROM THESE SYSTEMS DOES NOT LOOK EXCESSIVE WITH A WIDESPREAD 1-2 INCHES POSSIBLE. HOWEVER...WITH THE MOIST AIRMASS OVERHEAD...LOCALIZED HEAVY DOWNPOURS ARE POSSIBLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... MODEL AGREEMENT FOR OUR PART OF THE COUNTRY IS EXCELLENT THROUGH THE LONG TERM PERIOD. OVERALL...A LONG WAVE TROUGH IS EXPECTED IN THE EASTERN UNITED STATES LEADING TO TEMPERATURES AVERAGING NEAR TO SLIGHTLY BELOW NORMAL. FOR TUESDAY...THE LOW PRESSURE SYSTEM THAT BROUGHT UNSETTLED WEATHER ON LABOR DAY...WILL BE OVER EASTERN CANADA WITH A COLD FRONT ALONG THE EASTERN SEABOARD. UPPER LEVEL TROUGH EXTENDS SOUTH ALONG THE SPINE OF THE APPALACHIANS. MODELS ARE IN GOOD AGREEMENT THAT CLOUDS AND AND A FEW SHOWERS MAY LINGER ON TUESDAY. HIGHEST POPS SOUTHEAST OF ALBANY CLOSER TO DEPARTING COLD FRONT. WEDNESDAY...HIGH PRESSURE RIDGES IN FROM THE OHIO VALLEY WITH FAIR WEATHER EXPECTED. A COLD FRONT LOOKS TO PUSH THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING...BUT MOISTURE LOOKS LIMITED SO ONLY CHANCE POPS FOR RAIN SHOWERS LATER WEDNESDAY NIGHT INTO THURSDAY. COOL BREEZY CONDITIONS EXPECTED ON THURSDAY. BY FRIDAY...HIGH PRESSURE RIDGES IN THE MID ATLANTIC REGION WITH FAIR WEATHER AND A SOUTHWEST FLOW OF AIR AND MODERATING TEMPERATURES. ON SATURDAY...YET ANOTHER REINFORCING SHOT OF COOLER AIR LOOK TO PUSH INTO THE ALBANY FORECAST AREA. CHANCE POPS FOR RAIN SHOWERS ON SATURDAY WITH THE FRONTAL PASSAGE. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... AS OF 1015 PM EDT...A FEW MORE SHOWERS AND THUNDERSTORMS HAVE POPPED UP NEAR THE POUGHKEEPSIE AREA. OTHERWISE...THE CONVECTION HAS PRETTY MUCH WEATHER DOWN. PLACED A VCTS FOR AN HOUR OR SO THERE ALONG WITH AN HOUR LONG TEMPO FOR MVFR THUNDERSTORM THROUGH 03Z. ANY PARTIAL CLEARING HAS COME TO A HALT AS THERE WERE PLENTY OF HIGH AND MID LEVEL CLOUDS. LOW STRATUS HAS ALREADY TAKEN PLACE AT KGFL AT KPSF WILL LIKELY FORM AT THE OTHER TAF SITES IN THE NEXT COUPLE OF HOURS. RIGHT NOW WE STILL FEEL THE BEST FOR IFR WILL BE KGFL (ALREADY HAPPENING) AND KPSF...WITH LOW MVFR AT KPOU AND HIGH END MVFR AT KALB. HOWEVER...THIS IS A MODERATE CONFIDENCE FORECAST SO PLEASE CHECK BACK IF YOU PLAN TO FLY TOWARD DAYBREAK! IT WILL PROBABLY TAKE UNTIL AROUND 14Z TO LOOSE THE STRATUS AND FOG. AFTER THAT...WE EXPECT VFR CONDITIONS TO PREVAIL. WE DID PLACE IN A VCSH AS WE EXPECT SCATTERED CONVECTION TO DEVELOP IN THE AFTERNOON...BUT IT DOES NOT LOOK TO BE AS NUMEROUS AS TODAY/S. AS A POTENT UPPER LEVEL DISTURBANCE APPROACHES SUNDAY...CONVECTION LOOKS TO RAMP UP. THE VERY LIGHT SURFACE WIND WILL BECOME SOUTHERLY 5-10KTS ON SUNDAY. OUTLOOK... SUNDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA. LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL. THE BEST CHANCES FOR WIDESPREAD RAINFALL ARE SATURDAY AFTERNOON AND EVENING AND AGAIN ON LABOR DAY. A WEAK SURFACE FRONT WILL CROSS THE AREA THIS AFTERNOON AND EVENING WITH NUMEROUS SHOWERS AND STORMS. SOME CLEARING BEHIND THE FRONT WILL LEAD TO FOG AND CLOUDS SUNDAY MORNING. PARTIAL CLEARING IS EXPECTED SUNDAY AFTERNOON WITH ISOLATED POP UP SHOWERS AND THUNDERSTORMS EXPECTED IN THE STEAMY AIRMASS. A STRONGER LOW PRESSURE SYSTEM WILL BRING ANOTHER CHANCE FOR WIDESPREAD SHOWERS AND STORMS SUNDAY NIGHT AND MONDAY. THE RH VALUES RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING. HIGH RH VALUES OF 60 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON. RH VALUES NEAR 100 PERCENT ARE FORECAST AGAIN MONDAY MORNING. THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT AROUND 5 MPH TONIGHT. TOMORROW...EXPECT WINDS FROM THE SOUTHEAST AT 10 TO 20 MPH. SOUTHEAST WINDS OF 5 TO 10 MPH ARE FORECAST FOR SUNDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THIS WEEKEND. SOME MODERATE WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING DURING THE WEEKEND. RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE OF THE RAIN. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SND/WASULA NEAR TERM...WASULA SHORT TERM...SND LONG TERM...SND AVIATION...HWJIV FIRE WEATHER...SND HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
324 AM EDT SUN SEP 1 2013 .SHORT TERM /TODAY THROUGH MONDAY/... HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT SHOULD BEGIN TO BURN OFF AFTER SUNRISE. THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/ THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR OUTPUT. MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN. THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED DEVELOP...POPS MAY HAVE TO BE RAISED. FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION... LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS. NLISTEMAA .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO... TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE AREA ON SATURDAY. AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE COOLEST DAY OF THE PERIOD. TDP && AVIATION... 06Z UPDATE... PATCHY FOG HAS DEVELOPED AT QUITE A FEW OF THE TERMINAL SITES THIS MORNING. FOR THE NORTHERN TERMINAL SITES...VSBYS/CIGS SHOULD REMAIN IN THE MVFR RANGE. EVEN ATL HAS A CHANCE AT 4SM AND BKN012 AFTER RECEIVING RAINFALL TODAY. MCN WILL HAVE THE BEST CHANCE AT SEEING 1/2SM IN FG TOWARDS SUNRISE. BKN DIURNAL CU BTWN 040 AND 050 EXPECTED TODAY. BEST TIMES FOR CONVECTION ARE BETWEEN 19Z AND 01Z. LOW CIGS A POSSIBILITY FOR OVERNIGHT SUN/EARLY MON. //ATL CONFIDENCE...06Z UPDATE... MEDIUM CONFIDENCE ON CIGS/VSBYS THROUGH 13Z. OTHERWISE...HIGH CONFIDENCE ALL ELEMENTS. NLISTEMAA && .PRELIMINARY POINT TEMPS/POPS... ATHENS 89 70 90 70 / 50 40 40 40 ATLANTA 89 73 88 72 / 50 40 30 40 BLAIRSVILLE 83 66 84 65 / 60 50 50 30 CARTERSVILLE 90 70 89 70 / 50 50 40 50 COLUMBUS 92 74 90 74 / 40 30 30 20 GAINESVILLE 86 71 87 70 / 50 50 50 30 MACON 92 71 89 71 / 40 30 30 30 ROME 92 71 90 69 / 50 50 50 40 PEACHTREE CITY 88 71 89 70 / 50 40 30 30 VIDALIA 91 73 90 73 / 40 30 30 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...NLISTEMAA LONG TERM....TDP AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
359 AM CDT SUN SEP 1 2013 .DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * PATCHY GROUND FOG CONTINUES TO DEVELOP WITH VSBY REDUCTIONS EXPECTED THROUGH DAYBREAK. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY AFT 21Z. BEACHLER //DISCUSSION...UPDATED 06Z... VERY MOIST AND CALM AIRMASS OVERHEAD...WITH THINNING STRATUS CLOUD COVER. THIS ALL POINTS TOWARDS PATCHY FOG DEVELOPING AND REDUCING VSBYS TO MVFR AND A FEW AREAS OF IFR. WITH THE LACK OF A GRADIENT OVERNIGHT...WINDS WILL BECOME NEARLY CALM IN A FEW LOCATIONS. THIS SHOULD AID IN FOG FORMATION ALONG WITH RECENT RAINFALL. THEN AFT DAYBREAK HEATING SHOULD PROVIDE SOME INSTABILITY...HOWEVER NOT EXPECTING ANY SHRA/TSRA TO DEVELOP UNTIL THE FRONTAL BOUNDARY APPROACHES THE REGION FROM THE NORTHWEST. AT THIS TIME CURRENT GUIDANCE WOULD SUGGEST LIGHT WINDS FROM THE SOUTHWEST THRU MUCH OF THE DAY...THEN AS THE BOUNDARY NEARS AROUND 20-22Z SHRA/TSRA WILL BEGIN TO DEVELOP. THEN THE BOUNDARY PASSAGE IS POISED FOR 00-02Z AND WILL ALLOW WINDS TO VEER TO NORTHWEST/NORTH. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DEVELOPING. * MEDIUM CONFIDENCE IN ORD/MDW REMAINING MVFR VSBYS FROM FOG. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...VFR. NORTH-NORTHEAST WINDS. TUESDAY...VFR. LAKE BREEZE LIKELY. WEDNESDAY...VFR. THURSDAY...VFR. NORTHEAST WINDS. FRIDAY...VFR. RC && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
353 AM CDT SUN SEP 1 2013 .DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * PATCHY MVFR CIGS SLOWLY DISSIPATING...WITH PSBL GROUND FOG DEVELOPING AFT 08Z. * PATCHY FOG MAY REDUCE VSBYS TO MVFR TO IFR THRU DAYBREAK. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY AFT 21Z. BEACHLER //DISCUSSION...UPDATED 06Z... VERY MOIST AND CALM AIRMASS OVERHEAD...WITH THINNING STRATUS CLOUD COVER. THIS ALL POINTS TOWARDS PATCHY FOG DEVELOPING AND REDUCING VSBYS TO MVFR AND A FEW AREAS OF IFR. WITH THE LACK OF A GRADIENT OVERNIGHT...WINDS WILL BECOME NEARLY CALM IN A FEW LOCATIONS. THIS SHOULD AID IN FOG FORMATION ALONG WITH RECENT RAINFALL. THEN AFT DAYBREAK HEATING SHOULD PROVIDE SOME INSTABILITY...HOWEVER NOT EXPECTING ANY SHRA/TSRA TO DEVELOP UNTIL THE FRONTAL BOUNDARY APPROACHES THE REGION FROM THE NORTHWEST. AT THIS TIME CURRENT GUIDANCE WOULD SUGGEST LIGHT WINDS FROM THE SOUTHWEST THRU MUCH OF THE DAY...THEN AS THE BOUNDARY NEARS AROUND 20-22Z SHRA/TSRA WILL BEGIN TO DEVELOP. THEN THE BOUNDARY PASSAGE IS POISED FOR 00-02Z AND WILL ALLOW WINDS TO VEER TO NORTHWEST/NORTH. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DEVELOPING. * MEDIUM CONFIDENCE IN ORD/MDW REMAINING MVFR VSBYS FROM FOG. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...VFR. NORTH-NORTHEAST WINDS. TUESDAY...VFR. LAKE BREEZE LIKELY. WEDNESDAY...VFR. THURSDAY...VFR. NORTHEAST WINDS. FRIDAY...VFR. RC && .MARINE... 335 PM...A WEAK RIDGE OF HIGH PRESSURE OVER THE NORTHERN LAKES WILL MOVE EAST TONIGHT AS LOW PRESSURE MOVES ACROSS ONTARIO AND LAKE SUPERIOR ON SUNDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. THE GRADIENT WILL TIGHTEN BEHIND THIS FRONT AND COMBINED WITH MUCH COOLER AIR SPREADING ACROSS REGION...NORTHERLY WINDS WILL INCREASE TO 20 TO 25 KTS WITH SOME HIGHER GUSTS POSSIBLE. THESE WINDS WILL SLOWLY DIMINISH MONDAY NIGHT INTO TUESDAY AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN PLAINS MONDAY NIGHT AND ACROSS THE LAKES REGION TUESDAY AND TUESDAY NIGHT. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
403 AM CDT SUN SEP 1 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 252 AM CDT SUN SEP 1 2013 TODAY...HAVE HANDLED OVERNIGHT FOG DEVELOPMENT WITH A SPECIAL WX STATEMENT AND HOPE ARRIVING FRONTAL PROCESSES AND HIGH CLOUD COVER WILL LIMIT ADDITIONAL DEVELOPMENT TO PREVENT A NEED FOR AN ADVISORY. CURRENT EXTRAPOLATION OF UPSTREAM INCOMING FRONT GENERALLY AGREES WITH SREF PLACEMENT OF THIS FEATURE CROSSING THE MS RVR AT AROUND 17-18Z OR SO TODAY. MORE IMPORTANTLY WHEN LOOKING AT UPSTREAM CONVECTIVE TRENDS AND PRESSURE FALLS...IT APPEARS THAT SOME OF THE MCS WEST OF THE DSM AREA WILL CONTINUE TO PROPAGATE TOWARD/ ALONG BETTER INSTABILITY AND LLVL MOISTURE GRADIENTS AND MAKE IT ACRS AT LEAST THE SOUTHWESTERN THIRD OF THE DVN CWA THIS MORNING. NORTHEAST OF THAT AN ACRS THE REST OF THE DVN CWA...MAY JUST HAVE DECAYING DEBRIS OR DWINDLING AREAS OF STRATI-FORMING OUT PRECIP. SEVERAL OF THE HIGH-RES MODELS DRY THE INCOMING PRECIP UP ENOUGH THE BULK OF THE CWA WILL REMAIN DRY THROUGH 18Z. BUT WITH THE INCOMING FRONT...DEEPER FORCING UNDER DIFFLUENT NORTHWESTERLIES AND EMBEDDED WAVE ALOFT... WILL KEEP CHC POPS GOING THROUGH 18Z EXCEPT FOR THE FAR SOUTHWEST WHERE WILL GO WITH HIGH CHC TO LIKELY POPS FOR NOW AND MAY HAVE TO UPDATE LATER TO CATEGORICAL. MAY ALSO HAVE TO EXPAND HIGHER POPS FURTHER TO THE NORTH AND EAST. THUS SOME HOPE FOR RAIN FOR LOCALIZED DROUGHT AREAS THIS MORNING. CHALLENGING TEMP FCST AND AFTERNOON INSTABILITY SCENARIO DEPENDING ON WHAT HAPPENS THIS MORNING AND LINGERING AFFECTS OF CONVECTIVE DEBRIS. THTA-E ADVECTION FROM THE SOUTH AND PRE-FRONTAL WARM AIR SURGE WOULD SUGGEST TEMPS ACRS THE SOUTHERN AND SOUTHEASTERN CWA IN THE UPPER 80S TO AROUND 90 DEGREES WITH DPTS AT LEAST IN THE UPPER 60 TO AROUND 70. THIS WOULD MAKE FOR INSTABILITY AND CAPES CAPABLE OF SUPPORTING STRONG TO A FEW SVR STORMS THIS AFTERNOON IN CENTRAL IL AND POSSIBLY EXTENDING WESTWARD BACK INTO THE SOUTHEASTERN AND EAST CENTRAL DVN FCST AREA. BUT AGAIN...MUCH UNCERTAINTY WITH CLOUDS/DEBRIS FORM THE MORNING/UPSTREAM CONVECTIVE ACTIVITY POSSIBLY HAMPERING THE TRUE HEAT UP ABILITY AND INSTABILITY AND FCST TEMPS MAY BE WELL TOO WARM ESPECIALLY ACRS THE SOUTH/ SOUTHEAST. WILL STILL KEEP HIGHER AFTERNOON POPS FOR THIS POTENTIAL ACRS THE SOUTHEASTERN THIRD OF THE FCST AREA THIS AFTERNOON...BUT IF THIS MORNING/S SHOWER/STORM CHANCES INCREASE AND CONTINUE TO DEVELOP ACRS THESE AREAS THIS MORNING...THAT MAY BE IT FOR THE LOCAL AREA AND THE AFTERNOON RE-DEVELOPMENT WILL OCCUR OFF TO THE EAST OF THE DVN CWA. OTHERWISE POST-FRONTAL CLEARING PROCESSES THIS AFTERNOON AND EVENING ACRS THE REST OF THE DVN CWA. TONIGHT...SEASONABLY STRONG CANADIAN SFC ANTICYCLONE/HIGH STILL ON TRACK TO DUMP DOWN THE NORTHERN PLAINS AND UPPER MS RVR VALLEY WITH ASSOCIATED AIRMASS RELIEF FROM THE NORTH. WILL BANK ON INHERENT NORTHERLY SFC FLOW AND LOWER SFC DPT INFLUX TO PREVENT MORE FOG DEVELOPMENT TONIGHT DESPITE CLEAR OUT AND SFC TEMP COOL DOWN. LOW TEMPS IN THE 50S TO LOWER 60S...SOME MID 50S POSSIBLE NORTH OF I80. ..12.. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 252 AM CDT SUN SEP 1 2013 TURNING COOLER WITH CONTINUED DRY CONDITIONS THROUGH THE WEEK. OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH NORMAL POOR HANDLING OF BL MOISTURE AND ALSO SOME LOW LEVEL THERMAL FIELDS DISCREPANCIES. VERIFICATION AND RUN TO RUN CONTINUITY SUGGEST A 50/50 MIX OF THE UKMET/GEM-RH WITH GFS. HI-RES ECMWF HAS SOME CONTINUITY AND BL THERMAL FEEDBACK ISSUES. MINOR SENSIBLE WEATHER ISSUES SINCE DRY. IF WASN/T FOR THE FACT WE NEED RAIN...THE WEATHER THIS WEEK WILL BE ENJOYABLE. MONDAY AND TUESDAY...COMFORTABLE AND REFRESHING EARLY FALL WEATHER AS CANADIAN HIGH PRESSURE MOVES ACROSS THE REGION. HIGHS MIDDLE 70S NORTH TO LOWER 80S FAR SOUTH. MINS MAY STILL NEED TRIMMING A DEGREE OR TWO WITH LIGHT WINDS...CLEAR SKIES AND DRY GROUND FROM GOOD RADIATIONAL COOLING CONDITIONS. WEDNESDAY THROUGH SATURDAY...NW UPPER FLOW CONTINUES WITH WEAK HIGH PRESSURE TO CONTINUE. LATER SHIFTS MAY BE ABLE TO GO COMPLETELY DRY WEDNESDAY NIGHT IN FAR NW SECTIONS. HIGHS SHOULD RISE BACK WELL INTO THE 80S WITH LOWS UPPER 50S TO MIDDLE 60S. OVERALL...SLIGHTLY ABOVE NORMAL CONDITIONS WITH A SLIGHTLY HUMID BY NEXT WEEKEND BUT HEAT INDICES STAYING AT OR BELOW 90 DEGREES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1150 PM CDT SAT AUG 31 2013 MAIN CHALLENGE REMAINS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT INTO SUNDAY. LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE FAVORABLE FOR DEVELOPMENT OF FOG OVERNIGHT WITH VISIBILITIES POTENTIALLY FLUCTUATING QUITE A BIT SHALLOW LOW LEVEL INVERSION. THE RAP AND HRRR MODELS DO INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS ESPECIALLY EAST OF THE MISSISSIPPI RIVER. INCREASING MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT COULD HAVE IMPACT ON MAGNITUDE/EXTENT OF FOG AND POSSIBLY EVEN SOME LOW CLOUDS...THUS WILL BE A CHALLENGING SET OF TAFS. HAVE HIT THE FOG THE HARDEST WITH LIFR CONDITIONS AT KDBQ WHERE RECENT RAINS PAST 24+ HRS. ELSEWHERE...HAVE IFR TO MVFR VSBYS. COULD SEE SOME STRATUS WITH CIGS BLO 1KFT AGL AND HAVE HINTED AT THIS STILL AT ALL SITES. ANTICIPATE SCATTERED SHOWERS AND STORMS TO ACCOMPANY THE COLD FRONT...WHICH IS SLATED TO PASS THROUGH THE TERMINALS FROM 13Z-19Z. CONDITIONS TO IMPROVE TO VFR AFTER PASSAGE OF FRONT WITH WINDS INCREASING FROM NW AT 10-15 KTS WITH GUSTS AROUND 18-22+ KTS DURING THE AFTERNOON...THEN DIMINISH BLO 10 KTS BY 00Z. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SHORT TERM...12 LONG TERM...NICHOLS AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1200 AM CDT SUN SEP 1 2013 .SYNOPSIS... ISSUED AT 223 PM CDT SAT AUG 31 2013 WEAK LOW PRESSURE OVER WEST CENTRAL IL EARLY THIS AFTERNOON. HOT AND HUMID CONDITIONS WERE FOUND NEAR THE LOW WITH LOW TO MID 90 TEMPERATURES AND DEW POINTS IN THE LOW 70. IN THE LOW EASTERLY FLOW NORTH OF THE LOW TEMPERATURES WERE COOLER BUT DEWPOINTS WERE STILL AROUND 70. A COLD FRONT OVER THE NORTHERN PLAINS WAS THE LEADING EDGE OF COOL DRY AIR MASS. EARLY AFTERNOON TEMPERATURES OVER WESTERN NORTH DAKOTA WERE IN THE 70S WITH DEW POINTS IN THE 50S. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 223 PM CDT SAT AUG 31 2013 THIS FORECAST PERIOD WILL SEE A TRANSITION TO A MUCH MORE COMFORTABLE AIRMASS BY LATE SUNDAY AFTERNOON AS THE NORTHERN PLAINS FRONT MOVES THROUGH THE REGION. RAIN CHANCES WILL ACCOMPANY THE FRONT BUT AT THIS TIME...COVERAGE LOOKS SCATTERED AT BEST. FOR TONIGHT THE AREA OF LOW PRESSURE OVER WEST CENTRAL IL WILL BE THE FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND THIS EVENING. IT APPEARS THAT THE DEVELOPMENT WILL TAKE PLACE JUST EAST OF THE FORECAST AREA BASED CURRENT SATELLITE IMAGERY. HOWEVER WITH AN UPSTREAM VORT...OVER NORTHWEST IL... EXPECT TO MOVE THROUGH NORTHERN MO AND VERY UNSTABLE AIR STILL OVER THE SOUTHERN COUNTIES...A LOW POP WAS MAINTAINED FOR THE EARLY EVENING HOURS. WINDS WILL REMAIN LIGHT OVERNIGHT AND WITH THE HIGH DEWPOINTS STILL IN PLACE WE COULD SEE SOME PATCHY FOG LATE ESPECIALLY EAST OF THE MISSISSIPPI RIVER. THE NORTHERN PLAINS COLD FRONT IS EXPECTED TO REACH THE NORTHWEST CWA BY EARLY SUNDAY MORNING AND WILL EXIT THE EASTERN COUNTIES DURING THE EARLY AFTERNOON. THE BETTER FORCING WITH THIS SYSTEM WILL STAY OVER THE GREAT LAKES...BUT THE MODELS ARE SHOWING SOME UPPER DIFFLUENCE AHEAD OF THE S/W MOVING OVER THE AREA WITH THE COLD FRONT. THERE WILL ALSO BE OF NARROW THETAE RIDGE WITH THE BOUNDARY AND STEEPENING MID LEVEL LAPSE RATES WHICH SHOULD BE ENOUGH FOR SCATTERED STORMS AS THE FRONT MOVES THROUGH. COVERAGE OF THE STORMS SHOULD INCREASE AS THE FRONT MOVES ACROSS THE MISSISSIPPI RIVER WHERE THE AIRMASS HAS A CHANCE TO DESTABILIZE DURING THE MORNING. THE THREAT OF SEVERE STORMS WILL BE LOW ON SUNDAY DUE TO THE EARLY DAY FROPA AND WEAK DEEP LAYER SHEAR. THE HIGH LOW LEVEL MOISTURE WILL KEEP MIN TEMPS IN THE MID 60S TO AROUND 70 TONIGHT. HIGHS SUNDAY WILL STILL BE ON THE WARM SIDE TOPPING OUT AROUND 90 SOUTH TO THE MID 80S IN THE NORTH...BUT WE SHOULD SEE DEW POINTS COME DOWN A LITTLE...ESPECIALLY WEST OF THE MISSISSIPPI RIVER. DLF .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 223 PM CDT SAT AUG 31 2013 ANY LINGERING RAIN ACROSS THE SOUTHEAST THIRD OF THE CWFA SUNDAY EVENING WILL END SHORTLY AFTER SUNSET. HIGH PRESSURE WILL MOVE ACROSS THE MIDWEST SUNDAY NIGHT THROUGH TUESDAY RESULTING IN DRY BUT PLEASANT CONDITIONS. TEMPERATURES SHOULD AVERAGE CLOSE TO NORMAL. TUESDAY NIGHT ON... NORTHWEST FLOW ALOFT WILL PERSIST THROUGH NEXT WEEKEND. SEVERAL ADDITIONAL COLD FRONTS WILL MOVE THROUGH THE AREA BUT MOISTURE IS EXPECTED TO BE LIMITED WITH EACH FRONTAL PASSAGE. WHILE NOT CERTAIN...THE PROBABILITY IS MODERATE TO HIGH THAT MOST OF THE AREA WILL REMAIN DRY. THE MODEL CONSENSUS FOR TUESDAY NIGHT THROUGH SATURDAY IS FOR DRY CONDITIONS THROUGH THE PERIOD WITH TEMPERATURES AVERAGING AT OR SOMEWHAT ABOVE NORMAL. ..08.. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1150 PM CDT SAT AUG 31 2013 MAIN CHALLENGE REMAINS STRATUS/FOG POTENTIAL AND RAIN CHANCES OVERNIGHT INTO SUNDAY. LIGHT WIND AND ABUNDANT LOW LEVEL MOISTURE FAVORABLE FOR DEVELOPMENT OF FOG OVERNIGHT WITH VISIBILITIES POTENTIALLY FLUCTUATING QUITE A BIT SHALLOW LOW LEVEL INVERSION. THE RAP AND HRRR MODELS DO INDICATE POTENTIAL FOR LIFR/VLIFR CONDITIONS ESPECIALLY EAST OF THE MISSISSIPPI RIVER. INCREASING MID/HIGH CLOUDS OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT COULD HAVE IMPACT ON MAGNITUDE/EXTENT OF FOG AND POSSIBLY EVEN SOME LOW CLOUDS...THUS WILL BE A CHALLENGING SET OF TAFS. HAVE HIT THE FOG THE HARDEST WITH LIFR CONDITIONS AT KDBQ WHERE RECENT RAINS PAST 24+ HRS. ELSEWHERE...HAVE IFR TO MVFR VSBYS. COULD SEE SOME STRATUS WITH CIGS BLO 1KFT AGL AND HAVE HINTED AT THIS STILL AT ALL SITES. ANTICIPATE SCATTERED SHOWERS AND STORMS TO ACCOMPANY THE COLD FRONT...WHICH IS SLATED TO PASS THROUGH THE TERMINALS FROM 13Z-19Z. CONDITIONS TO IMPROVE TO VFR AFTER PASSAGE OF FRONT WITH WINDS INCREASING FROM NW AT 10-15 KTS WITH GUSTS AROUND 18-22+ KTS DURING THE AFTERNOON...THEN DIMINISH BLO 10 KTS BY 00Z. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...DLF SHORT TERM...DLF LONG TERM...08 AVIATION...05
AREA FORECAST DISCUSSION
NWS GOODLAND KS
218 AM MDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 150 PM MDT SAT AUG 31 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA. A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER EASTERN WYOMING. AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM ACTIVITY. HOWEVER...I`M NOT SURE ABOUT HOW WIDESPREAD THAT THREAT WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL. REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO BE FOR LABOR DAY WEEKEND. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 214 AM MDT SUN SEP 1 2013 UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM TEMPERATURES AND DRY CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA WILL BE CENTERED OVER COLORADO FOR WEDNESDAY AS RIDGE BECOMES MORE AMPLIFIED INTO THE NORTHERN HIGH PLAINS FOR THURSDAY AND FRIDAY. THE RIDGE WILL DEAMPLIFY AND RETROGRADE WESTWARD INTO THE DESERT SOUTHWEST REGION NEXT WEEKEND AS AN UPPER LEVEL LOW MOVES OUT OF ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE TROUGHS LOOK TO DEVELOP LATE INTO NEXT WEEKEND AND MOVE INTO THE HIGH PLAINS WITH THE MAIN ASSOCIATED UPPER LEVEL TROUGH...WHICH COULD PROVIDE ENOUGH LIFT FOR THUNDERSTORM DEVELOPMENT FOR SUNDAY. STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE LOWER 90S. LOW TEMPERATURES FOR THE EXTENDED PERIOD WILL BE IN THE UPPER 60S FOR MOST LOCATIONS. MODEL SOUNDINGS SHOW STABLE UPPER AIR PROFILE THROUGH THE PERIOD...WITH MARGINAL INSTABILITY PARAMETERS AT BEST AND A GENERAL LACK OF MOISTURE IN THE UPPER AIR PROFILES. MODEL FORECASTS DIFFER ON PRECIPITATION CHANCES FOR NEXT SUNDAY...BUT ENCROACHING FRONTAL CLIPPER SYSTEM WILL LIKELY PROVIDE SOME CHANCES FOR STORM DEVELOPMENT. BESIDES SLIGHT PRECIPITATION CHANCES NEXT WEEKEND...THE MAIN WEATHER PATTERN FOR THE EXTENDED FORECAST PERIOD CONTINUES TO BE WARM TEMPERATURES AND MAINLY DRY CONDITIONS FOR THE TRI STATE AREA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1100 PM MDT SAT AUG 31 2013 FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. POST FRONTAL NORTHEAST WINDS EXPECTED TO GUST CLOSE TO 25KTS OR SO AFTER 13Z-15Z THROUGH 20Z BEFORE DECREASING TOWARD 10KTS FROM THE EAST THEN LIGHT EAST/SOUTHEAST 5KTS OR SO BY 02Z AS SFC HIGH MOVES IN. LATEST MODELS HINTING AT SOME IFR CIGS FOR KGLD IN THE 12Z-16Z TIME FRAME. HAVE INTRODUCED A SCATTERED GROUP AROUND 500FT TO ACCOUNT FOR THIS AND WILL ALLOW NEXT SHIFT TO RE-EVALUATE POTENTIAL NEED FOR PREVAILING IFR/VLIFR CONDITIONS. NO PRECIPITATION EXPECTED. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...MK AVIATION...99
AREA FORECAST DISCUSSION
NWS WICHITA KS
242 AM CDT SUN SEP 1 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH CENTRAL/SOUTHEAST KS. THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD OF THE FRONT. COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS. JMC .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH. THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME. JMC && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1129 PM CDT SAT AUG 31 2013 A FRONTAL BOUNDARY WILL SINK SOUTHWARD INTO CENTRAL KANSAS TOWARDS DAYBREAK...THEN PUSH SLOWLY SOUTHWARD INTO SOUTHERN KANSAS BY SUNDAY AFTERNOON. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG THE FRONTAL BOUNDARY. JAKUB && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 94 65 88 64 / 30 10 0 0 HUTCHINSON 92 64 87 63 / 40 10 0 0 NEWTON 92 64 86 62 / 30 10 0 0 ELDORADO 94 65 86 62 / 30 10 0 0 WINFIELD-KWLD 97 66 89 64 / 20 10 0 0 RUSSELL 89 60 87 62 / 40 0 0 0 GREAT BEND 90 63 88 62 / 40 0 0 0 SALINA 91 62 87 62 / 30 0 0 0 MCPHERSON 92 63 87 62 / 30 0 0 0 COFFEYVILLE 97 67 88 64 / 20 10 0 0 CHANUTE 94 65 86 63 / 30 10 0 0 IOLA 94 64 86 62 / 30 10 0 0 PARSONS-KPPF 96 66 87 63 / 20 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1243 AM CDT Sun Sep 1 2013 ...Updated for Aviation... .SYNOPSIS... ISSUED AT 300 PM CDT SAT AUG 31 2013 An upper level center of high pressure was located across New Mexico and the extreme southern High Plains today, as the upper westerly jet was positioned zonally across the northern Rockies and Northern Plains. A shortwave was in place across southern Canada, on the north side of the jet. A hot airmass still encompassed the central part of the country. 850 mb level temperatures in excess of 20 degrees C extended from the entire great plains region eastward to the the Ohio valley. at the surface...a cold front was moving southward across western South Dakota and extreme western Nebraska. Another weak stationary front was positioned from the Texas panhandle northeast into south central Kansas. Easterly surface winds became more southerly across western Kansas as surface low pressure slowly filled across the Oklahoma panhandle and temperatures warmed into the 90`s by early afternoon. && .SHORT TERM...(This evening through Sunday) ISSUED AT 300 PM CDT SAT AUG 31 2013 The immediate concern will revolve around convective chances which are not great, but non-zero as well. The best location appears along the diffuse boundary across south central Kansas. The HRRR runs have somewhat approximated isolated convection occurring by about 23 utc. A lack of upper winds and lack of shear suggest little chances at all of severe thunderstorms, and storms should have short life cycles. A better chance for showers and thunderstorms exists well into the overnight as the Northern Plains cold front enters the area. Probabilities increase from north to south around 6z and after. Very warm temperatures will continue into this evening. The NAM models surface temperatures sill around 100 degrees this evening near the Oklahoma line and low 80s persisting after midnight. Morning lows will likely be warm across all of southwest Kansas, with a few locations having lows in the upper 70s, however rain cooled air form a few vigorous storm cluster might augment the temperatures locally. Thunderstorms chances are again in the forecast during the afternoon Sunday as redevelopment is likely along the frontal boundary, wherever it decides to stall out. .LONG TERM...(Sunday night through Saturday) ISSUED AT 235 PM CDT SAT AUG 31 2013 A cold front will move across Kansas tonight as a vigorous upper level trough moves from southeast Saskatchewan to the Great Lakes, and a brief period of near climatological temperatures should extend into Monday. However, the anticyclone centered over the Rockies will build back into the Central Plains early next week, and several days of warm, quiet weather will follow. Unless rainfall tonight is more widespread than appears likely, vegetation will become increasingly drought stressed next week. Reduced evapotranspiration may allow more solar radiation to covert into sensible heat, and temperatures in the mid to upper 90s can be expected on most days. Tropical thunderstorm activity has been strongly suppressed from about 130E to the dateline, although an area of enhanced thunderstorms has been persistent in the Indian Ocean southwest of India. Most of the numerical models suggest that a coherent tropical cluster that projects onto a Madden Julian Oscillation (MJO) will amplify in Phase 1 of the Wheeler-Hendon Phase Space Diagram early in September and propagate slowly east before losing identity in the Indian Ocean. There is little correlation between the MJO and sensible weather in the central plains at this time of the year, but there may be in increased chance for tropical waves to come off Africa into the eastern Atlantic next week. Global relative angular momentum remains below climatology, but mountain torque has increased in recent days. The atmosphere will be best represented by Phase 4-5 of the Weickmann-Berry Global Wind Oscillation, which correlates with anticyclonic flow in the western and central United States. The deterministic model solutions all favor ridging from the central Rockies across the central and southern United States through the first ten days of September with only minor synoptic scale differences. The 12Z GFS has trended toward the 00Z ECMWF in handling the closed cyclone near 140W that wallows into the northern plains 9-10 September and largely was followed for grid adjustments, although confidence in behavior of this cyclone is low. Upslope flow into the foothills in eastern Colorado Sunday evening should favor thunderstorm development, but the upper level flow will be light and largely meridional over western Kansas. Most of the thunderstorms will remain west of the Colorado border, but there is a nonzero chance that a thunderstorm could reach far southwest Kansas before midnight Sunday night. Cool high pressure with light winds and low level dewpoints in the 50s will allow for strong radiational cooling, and lows will drop into the upper 50s in most areas Tuesday morning. Another minor trough dropping into the mean long wave trough near 80W will support a weak boundary that may survive into northern Kansas Wednesday night, but limited instability and weak flow aloft do not favor an organized thunderstorm event. As the upper level trough near 140W moves across the Northern Plains around 9 September, a cold front will move into Kansas and provide another opportunity for thunderstorm development and a return to more seasonal temperatures. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) ISSUED AT 1235 AM CDT SUN SEP 1 2013 Scattered thunderstorms at KDDC and KGCK with west to northwest winds of 25-38kt will continue through 08-10z this morning, then winds shifting to the northeast at 10-15kt after 15z. Vfr conditions will prevail after the thunderstorms. KHYS will likely stay out of the thunderstorm activity. && .PRELIMINARY POINT TEMPS/POPS... DDC 60 89 61 91 / 10 0 0 0 GCK 58 90 61 91 / 10 0 0 0 EHA 64 91 65 91 / 10 10 10 0 LBL 60 92 62 92 / 10 0 0 0 HYS 57 90 59 91 / 0 0 0 0 P28 64 90 62 91 / 10 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Russell SHORT TERM...Russell LONG TERM...Ruthi AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1102 PM MDT SAT AUG 31 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 150 PM MDT SAT AUG 31 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA. A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER EASTERN WYOMING. AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL. REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO BE FOR LABOR DAY WEEKEND. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 204 PM MDT SAT AUG 31 2013 THE UPPER RIDGE IS IN PLACE AGAIN OVER THE ROCKIES AND HIGH PLAINS FROM SUNDAY NIGHT THROUGH ALL OF NEXT WEEK. DIFFERENCES BEGIN TO SHOW UP IN MODEL PROGRESSIONS OF THE UPPER LOW CENTER RIDING UP OVER THE RIDGE IN THE PACIFIC NORTHWEST AND THE OVERALL FLATTENING OF THE RIDGE IN THE FRIDAY NIGHT THROUGH SATURDAY TIME PERIOD. SURFACE COOLER HIGH PRESSURE AREA STAYS MOSTLY OVER THE CENTRAL PLAINS AND CENTRAL HIGH PLAINS SUNDAY NIGHT AND MONDAY BEFORE PUSHING FURTHER EAST WITH A DEEPENING LEE TROUGH THAT PERSISTS IN THE VICINITY OF THE EASTERN COLORADO BORDER. WITH SOUTHERLY FLOW ACROSS THE FORECAST AREA...EXPECT MORE DRY AND WARM CONDITIONS THROUGH THE UPCOMING WORK WEEK AND NEXT WEEKEND WITH HIGHS IN THE 90S AND LOWS IN THE 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1100 PM MDT SAT AUG 31 2013 FOR KGLD AND KMCK VFR CONDITIONS EXPECTED. POST FRONTAL NORTHEAST WINDS EXPECTED TO GUST CLOSE TO 25KTS OR SO AFTER 13Z-15Z THROUGH 20Z BEFORE DECREASING TOWARD 10KTS FROM THE EAST THEN LIGHT EAST/SOUTHEAST 5KTS OR SO BY 02Z AS SFC HIGH MOVES IN. LATEST MODELS HINTING AT SOME IFR CIGS FOR KGLD IN THE 12Z-16Z TIMEFRAME. HAVE INTRODUCED A SCATTERED GROUP AROUND 500FT TO ACCOUNT FOR THIS AND WILL ALLOW NEXT SHIFT TO RE-EVALUATE POTENTIAL NEED FOR PREVAILING IFR/VLIFR CONDITIONS. NO PRECIPITATION EXPECTED. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
345 AM EDT SUN SEP 1 2013 .UPDATE... ISSUED AT 240 AM EDT SUN SEP 1 2013 THE BULK OF THE CONVECTION HAS DIED OUT OVER EAST KENTUCKY...THOUGH ADDITIONAL STORMS LOOK TO BE TRACKING INTO THE CUMBERLAND VALLEY OVER THE NEXT SEVERAL HOURS. RAN A QUICK UPDATE MAINLY TO THE POP/WX AND SKY GRIDS THROUGH DAWN TO REFLECT THESE CONVECTIVE...AND FOG... TRENDS. ALSO FINE TUNED THE T AND TD GRIDS THROUGH 12Z BASED ON THE CURRENT OBS. THE GRID UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 1043 PM EDT SAT AUG 31 2013 MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS PERIOD. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 420 PM EDT SAT AUG 31 2013 THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN WITH TIME. ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS. WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY... HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT. HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 AM EDT SUN SEP 1 2013 A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN. AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIRMASS...WITH WINDS AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY REACH NEAR 80 TUESDAY. THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIRMASS IN PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE 50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER GREAT LAKES SATURDAY. ACCORDING THE ECWMF...WARM AIR PULLING IN AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL SOMEWHAT UNKNOWN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 300 AM EDT SUN SEP 1 2013 THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH MOST OF THE AREA...BUT AN ADDITIONAL ROUND OF STORMS MAY AFFECT SME AND LOZ FROM NOW UNTIL 12Z. OUTSIDE OF THE CUMBERLAND VALLEY...PATCHY FOG WILL BE THE MAIN AVN CONCERN INTO DAWN. DO EXPECT ADDITIONAL STORMS TO DEVELOP AND AFFECT THE ENTIRE AREA LATER ON SUNDAY WITH A PEAK OF COVERAGE ANTICIPATED DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. HAVE REFLECTED THIS IN THE TAFS VIA A PREVAILING SHRA AND VCTS DURING THIS TIME. LATE ON...BACKED THESE OFF TO JUST VCSH MENTIONS AFTER 02Z AS INSTABILITY WANES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY STORMS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...JMW AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
300 AM EDT SUN SEP 1 2013 .UPDATE... ISSUED AT 240 AM EDT SUN SEP 1 2013 THE BULK OF THE CONVECTION HAS DIED OUT OVER EAST KENTUCKY...THOUGH ADDITIONAL STORMS LOOK TO BE TRACKING INTO THE CUMBERLAND VALLEY OVER THE NEXT SEVERAL HOURS. RAN A QUICK UPDATE MAINLY TO THE POP/WX AND SKY GRIDS THROUGH DAWN TO REFLECT THESE CONVECTIVE...AND FOG... TRENDS. ALSO FINE TUNED THE T AND TD GRIDS THROUGH 12Z BASED ON THE CURRENT OBS. THE GRID UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 1043 PM EDT SAT AUG 31 2013 MADE A COUPLE OF UPDATES TO ACCOUNT FOR ONGOING CONVECTION AND ITS EXPECTED COURSE DURING THE OVERNIGHT. LATEST HRRR SEEMS TO HAVE A FAIRLY GOOD HANDLE ON THE SITUATION...WITH THE BEST CONVECTION/THUNDERSTORMS TO OUR WEST CONTINUING TO DIVE MORE SOUTHWARD...ONLY INFLUENCING OUR SOUTHWESTERN COUNTIES. UNFORTUNATELY THIS AREA HAS ALREADY BEEN IMPACTED WITH HEAVY RAINS AND THUNDERSTORMS EARLIER IN THE EVENING...SO THE BIGGEST CONCERN IS THE POTENTIAL FOR MORE FLASH FLOODING WITH ANY HEAVY SHOWER OR THUNDERSTORM THAT PASSES OVER. THE ENTIRE WESTERN HALF OF THE CWA CAN STILL EXPECT SOME RAINFALL AND SCT THUNDERSTORMS THROUGHOUT THE NEXT FEW HOURS AS WELL. A MAJORITY OF THE CONVECTION IS PROJECTED TO DISSIPATE LATE TONIGHT...SO DID NOT MAKE ANY CHANGES PAST THIS PERIOD. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 420 PM EDT SAT AUG 31 2013 THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN WITH TIME. ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS. WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY... HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT. HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 437 PM EDT SAT AUG 31 2013 THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY. ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST. ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST DRY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 300 AM EDT SUN SEP 1 2013 THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH MOST OF THE AREA...BUT AN ADDITIONAL ROUND OF STORMS MAY AFFECT SME AND LOZ FROM NOW UNTIL 12Z. OUTSIDE OF THE CUMBERLAND VALLEY...PATCHY FOG WILL BE THE MAIN AVN CONCERN INTO DAWN. DO EXPECT ADDITIONAL STORMS TO DEVELOP AND AFFECT THE ENTIRE AREA LATER ON SUNDAY WITH A PEAK OF COVERAGE ANTICIPATED DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. HAVE REFLECTED THIS IN THE TAFS VIA A PREVAILING SHRA AND VCTS DURING THIS TIME. LATE ON...BACKED THESE OFF TO JUST VCSH MENTIONS AFTER 02Z AS INSTABILITY WANES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY STORMS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...HAL AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
359 AM EDT SUN SEP 1 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM OVER LAKE SUPERIOR WILL CONTINUE TO DEVELOP AND MOVE EAST INTO NORTHERN QUEBEC THROUGH EARLY THIS WEEK. A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE THROUGH THE MID- ATLANTIC MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE BUILDS IN FROM THE NORTHWEST MID TO LATE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEBRIS CLOUDS LEFT OVER FROM YDA`S CONVECTION HAS LIMITED EXTENT OF FOG FORMATION ERY THIS MRNG. SOME PATCHY FOG WILL STILL DEVELOP THRU DAYBREAK PRIMARILY WITHIN THE SHELTERED VLYS IN CENTRAL VA...WHERE THE GROUND IS WET FROM YDA`S STORMS. HIPRES WILL REMAIN PARKED OVER THE WRN ATLANTIC TDA. WITH PERSISTENT SLY RETURN FLOW OVER THE ERN SEABOARD...THE AIRMASS WILL BE SIMILAR TO YDA...WARM AND HUMID /DESPITE THE CALENDAR CHANGING FROM METEOROLOGICAL SUMMER TO FALL/. MAX TEMPS ARE FCST IN MID TO UPPER 80S ALONG AND WEST OF THE BLUE RIDGE AND UPPER 80S TO LOWER 90S FARTHER EAST. ONE MID-LVL SHORTWAVE TROUGH EXITS THE MID-ATLANTIC REGION ERY THIS MRNG AS ANOTHER ONE APPROACHES FROM THE OH VLY. THE REMNANTS OF THIS UPSTREAM MCS WILL PROGRESS EWD THRU THE NRN MID-ATLANTIC STATES THIS AFTN/EVE. THE CWA WILL HAVE FILTERED SUNSHINE BEFOREHAND...PROVIDING AN OPPORTUNITY FOR THE ATMOSPHERE TO DESTABILIZE. SIMILAR TO YDA...SCT SHOWERS AND STORMS SHOULD DEVELOP OVER THE MTS THIS AFTN AS MODEST LIFT FROM THE SHORTWAVE TROUGH REACHES THE WRN CWA. WITH THE MID-LVL SUBSIDENCE INVERSION WEAKER THAN YDA...DEEPER CONVECTION WILL HAVE A BETTER CHANCE TO MAKE IT EAST OF THE MTS. THE BEST CHANCE FOR SHOWERS AND STORMS APPEAR TO BE LATE THIS AFTN AND EVE WHEN THE SHORTWAVE TROUGH MOVES THRU. LIMITED POPS TO CHANCE ACROSS THE ENTIRE CWA THOUGH AS CONVECTION MAY HAVE DIFFICULTY ORGANIZING DUE TO WEAK SHEAR PROFILES AND LIFT FROM THE TROUGH. FCST PARAMETERS FROM THE LATEST RAP INDICATE ABOUT 1500-2000 J/KG OF SBCAPE THIS AFTN. CANNOT RULE OUT A COUPLE OF PULSE SEVERE STORMS ESPECIALLY IN THE MTS GIVEN THE THERMODYNAMIC PROFILES. ONGOING CONVECTION WILL DIMINISH LATE THIS EVE WITH THE LOSS OF HEATING AND AS THE SHORTWAVE TROUGH LIFTS NEWD TNGT. DRY SLOT MOVES IN FROM THE WEST TNGT WHILE THE LLVL FLOW VEERS OUT OF THE WEST. THIS COULD ALLOW FOR BREAKS IN THE CLOUD COVER AND FOR FOG TO DEVELOP LATE TNGT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... LABOR DAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN APPROACHING COLD FRONT FROM THE WEST. A PREFRONTAL TROUGH WILL DEVELOP IN THE LEE OF THE APPALACHIANS WHICH SHOULD PROVIDE A FOCUS FOR ISOLATED/SCATTERED AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT. IT WILL BE A HOT DAY WITH MAX TEMPS IN THE LOW 90S. NAM AND GFS HAVE SBCAPE AROUND 2500 J/KG WITH BULK SHEAR UNDER 30 KT. MONDAY NIGHT...LINES OF CONVECTION SHOULD DEVELOP AHEAD OF THE FRONT AND PUSH EAST THROUGH THE AREA MONDAY EVENING/THROUGH MIDNIGHT. INCREASED LIKELY POP COVERAGE TO ACROSS THE BALT-WASH METRO FOR THE EVENING HOURS. THIS IS JUST ABOVE MOST GUIDANCE WHICH IS AROUND 50 POP. WITH AMPLE AVAILABLE ENERGY AND A STRAIGHT-LINE HODOGRAPH... EXPECT ORGANIZED ACTIVITY. SEVERE THREAT OF LARGE HAIL AND DAMAGING WIND. SPEAKING OF HAIL...THERE HAVE ONLY BEEN FOUR 1 INCH HAIL REPORTS SINCE JULY 4. WITH TALL AND FAT CAPE DEPICTED BY THE NAM/GFS SOUNDINGS...THIS HAIL DEARTH MAY END SOON. FRONT DRIFTS EAST THROUGH THE NIGHT...MIN TEMPS AROUND 60F IN THE ALLEGHENY HIGHLANDS...CLOSER TO 70F EAST OF THE BLUE RIDGE PER MAV/MET/SREF BLEND. TUESDAY...FRONT IS SLOW TO CLEAR THE AREA...MAY STALL OVER SRN MD CONTINUING A THUNDERSTORM THREAT DOWN THERE. OTW...NRN CONUS (NOT QUITE CANADIAN...AND THUS NOT AS COOL) HIGH PRESSURE BUILDS IN FROM THE NW...WITH SUNNY CONDITIONS ON TAP IN WRN PARTS OF THE CWA. MAX TEMPS GENERALLY 80S AT LOW ELEVATIONS...MID 80S I-95 AND EAST. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... DRY CONDITIONS AS HIGH PRESSURE DOMINATES THROUGH FRIDAY. WEAK SFC TROUGH DROPS SOUTH INTO THE CWA WEDNESDAY NIGHT...PUSHING SOUTH THURSDAY. PROBABLY JUST SOME MID LEVEL CLOUDS ASSOCIATED WITH THIS DISTURBANCE. MAX TEMPS CLOSE TO NORMAL...LOW 80S WED-FRI. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... LGT SLY WINDS AND MID TO HI CLOUDS HAVE LIMITED THE COVERAGE OF FOG ERY THIS MRNG. AS OF 0730Z...ALL TERMINALS ARE VFR. CHO HAS THE BEST OPPORTUNITY FOR A BRIEF PERIOD OF FOG TOWARD SUNRISE AS THE SOIL IS SATURATED FROM YDA`S STORMS. VFR CONDITIONS FOR MUCH OF TDA. SCT SHOWERS AND STORMS ARE EXPECTED TO INITIALLY DEVELOP OVER THE MTS THIS AFTN AND MOVE EWD TOWARD THE TERMINALS APPROX BETWEEN 20Z-01Z. TEMPORARY FLGT RESTRICTIONS POSSIBLE WITH THESE STORMS. PATCHY FOG POSSIBLE AGAIN LATE TNGT...ESPECIALLY AT THE FOG-PRONE LOCATIONS AT CHO AND MRB. THUNDERSTORMS INCREASE MONDAY AFTERNOON/CONTINUE THROUGH THE NIGHT AS A COLD FRONT DRIFTS EAST ACROSS THE TERMINALS. SLY FLOW AROUND 10 KT...THOUGH DAMAGING WINDS ARE POSSIBLE IN THUNDERSTORMS. HIGH PRESSURE THEN BUILDS TUESDAY AND DOMINATES REST OF THE WORK WEEK WITH VFR CONDS OUTSIDE OF MORNING FOG. && .MARINE... SLY CHANNELING HAS ENHANCED WINDS TO NEAR SCA THRESHOLD IN THE TANGIER SOUND ERY THIS MRNG. HAVE AN MARINE WX STATEMENT FOR THIS ZONE PUT OPTED TO NOT ISSUE A SCA AS THE PRESSURE GRADIENT WILL CONTINUE TO WEAKEN OVER THE NEXT COUPLE OF HRS. OTHERWISE...SLY WINDS BETWEEN 10-15 KT WILL CONTINUE TDA AND TNGT. SCT STORMS EXPECTED LATE IN THE DAY. LOCALLY STRONG WINDS WITH THESE STORMS COULD BECOME HAZARDOUS TO MARINERS AND HOLIDAY BOATERS. 10-15 KT SLY FLOW AHEAD OF A COLD FRONT ACROSS THE WATERS MONDAY. SPECIAL MARINE WARNINGS POSSIBLE FROM THUNDERSTORMS LATE MONDAY AFTERNOON THROUGH THE NIGHT. FLOW BECOMES NWLY BY TUESDAY EVENING...SOME CHANNELING GUSTS MAY APPROACH 18 KT. VARIABLE FLOW AND HIGH PRESSURE WEDNESDAY THROUGH FRIDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BAJ/JRK NEAR TERM...JRK SHORT TERM...BAJ LONG TERM...BAJ AVIATION...BAJ/JRK MARINE...BAJ/JRK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
152 AM EDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 359 PM EDT SAT AUG 31 2013 MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE SHRA/TS CHCS ASSOCIATED WITH SHRTWV NOW NEAR LK WINNIPEG. 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER THE NRN CONUS ON THE NRN FLANK OF SPRAWLING HI PRES CENTERED OVER THE SW CONUS. STUBBORN LO CLDS OVER THE SCENTRAL COUNTIES ARE FINALLY BURNING OFF. THERE IS A SHRTWV TRACKING THRU ONTARIO...BUT THIS DISTURBANCE IS PASSING FAR ENUF TO THE N THAT THE COMMA TAIL -SHRA ARE JUST BRUSHING NEAR ISLE ROYALE. WEAK RDG OF HI PRES OVER THE GRT LKS/SHARP SUBSIDENCE INVRN SHOWN ON LOCAL 12Z RAOBS IS BRINGING QUIET WX TO THE CWA FOR NOW. A STRONGER SHRTWV IS PRESENT ALONG THE NDAKOTA/CNDN BORDER AND MOVING QUICKLY TO THE ESE. WHERE THE SHARP DPVA/DEEP LYR QVECTOR CNVGC IN ADVANCE OF THIS FEATURE IS OVERSPREADING AXIS OF HIER MUCAPE/H85 THETA E AHEAD OF ATTENDANT COLD FNT...NMRS SHRA/TS ARE BREAKING OUT IN MN. TNGT...SHRTWV JUST SW OF LK WINNIPEG IS PROGGED TO MOVE ESE AND OVER NCENTRAL LK SUP BY 12Z SUN. AS THE DPVA/DEEP LYR QVECTOR CNVGC AND AXIS OF HIER INSTABILITY/H85 THETA E MOVE INTO WRN LK SUP THIS EVNG...EXPECT SHRA/TS NOW OVER MN TO SHIFT INTO THE WRN LAND CWA BY 06Z. GIVEN FCST MUCAPE IN EXCESS OF 1000 J/KG...SFC-6KM SHEAR IN THE 40-50KT RANGE /FORTUNATELY THE STORMS WL BECOME ELEVATED SO THIS WL NOT BE THE EFFECTIVE LYR SHEAR/...AND FAIRLY SHARP LLVL CNVGC ALONG ATTENDANT COLD FNT...SOME OF THESE STORMS MAY BE STRONG. BUT WITH LOSS OF DAYTIME HEATING AND WEAKENING H85 THETA E AXIS...EXPECT THE INTENSITY OF THESE SHRA/TS TO DIMINISH AS THEY SPREAD INTO CENTRAL UPR MI LATE. IN FACT...THE MOST RECENT SPC CONVECTIVE OUTLOOK THRU 12Z SUN CONFINES THE SLGT RISK FOR SVR TS TO MN AND FAR WRN LK SUP. WHERE TEMPS HAVE A CHC TO COOL DOWN A BIT OVER THE E HALF BEFORE THE ARRIVAL OF CLDS/A BIT SHARPER PRES GRADIENT...ADDED PATCHY FOG WITH EXPECTATION THAT MIN TEMPS FALLING INTO THE UPR 50S WL FALL THRU THE CROSSOVER DEWPT OBSVD THIS AFTN. SUN...AS SHRTWV OVER NCENTRAL LK SUP IN THE MRNG SHIFTS INTO SE ONTARIO IN THE AFTN...DNVA/DEEP LYR QVECTOR DVGC/VIGOROUS NEGATIVE H85 THETA E ADVCTN IS FCST TO ARRIVE W-E FOLLOWING ATTENDANT COLD FROPA. EXPECT BAND OF SHRA/TS AHD OF COLD FNT TO SHIFT FM THE CNTRL ZNS INTO THE ERN ZNS DURING THE MRNG. SHRA/TS INTENSITY MAY PICK UP OVER THE FAR ERN CWA IN THE EARLY AFTN WITH IMPACT OF DAYTIME HEATING LIFTING MUCAPE TO 500-1000 J/KG AND DEEP LYR SHEAR 30 TO 40 KTS BEFORE THE MORE ROBUST QVECTOR DVGC ARRIVES IN THE AFTN AND BEGINS TO SUPPRESS THE CONVECTION WITH STRENGTHENING INVRN FOLLOWING COLD FROPA AT ERY NEAR 21Z. THIS THREAT WOULD BE GREATER IF THE SOMEWHAT SLOWER GFS VERIFIES...BUT THE PRESENT STEADY SPEED OF SHRTWV INDICATES THE FASTER MODEL FCSTS ARE ON THE RIGHT TRACK. FOLLOWING THE COLD FROPA AND ARRIVAL OF LLVL COOLER AIR...NAM FCST SDNGS SHOW SHARPENING LLVL INVRN/PROSPECT FOR LO CLDS AND SOME SPRINKLES...ESPECIALLY OVER THE W AND NCENTRAL WITH UPSLOPE NW FLOW. SFC TEMPS MAY ACTUALLY FALL AT THESE PLACES DURING THE AFTN. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 359 PM EDT SAT AUG 31 2013 MORE SEASONABLE WEATHER IS EXPECTED THROUGH MUCH OF THE UPCOMING WEEK...WITH CHANCES OF PRECIPITATION MONDAY AND AGAIN WEDNESDAY. SUNDAY NIGHT AND MONDAY...A STRONG AND SHARP MID-LEVEL SHORTWAVE OVER NE LAKE SUPERIOR WILL BE STARTING TO EXIT TO THE EAST AT THE START OF THE PERIOD. THE ASSOCIATED SFC LOW WILL ALSO BE TRACKING EASTWARD AWAY FROM EASTERN LAKE SUPERIOR. THE MAIN FORECAST CONCERN IS HOW LONG MOISTURE WILL LINGER BEHIND THIS SYSTEM...AND HOW WIDESPREAD UPSLOPE DRIZZLE/SHOWERS WILL BE. WITH PLENTY OF LOW-LEVEL MOISTURE WRAPPING BEHIND THE LOW...EXPECT PLENTY OF DRIZZLE AND LIGHT SHOWERS FOR ANY AREA EXPOSED TO NNW WINDS OFF LAKE SUPERIOR. SUBSIDENCE WILL LOWER INVERSION HEIGHTS TO AROUND 1KM ACROSS THE AREA...SO THE SATURATED LAYER WILL BE QUITE SHALLOW. INSOLATION ON MONDAY SHOULD BE STRONG ENOUGH TO START ERODING THIS MOIST LAYER MONDAY MORNING. INCREASINGLY DRIER AIR ADVECTING IN FROM WESTERN ONTARIO SHOULD THEN REMOVE REMAINING CLOUDS/PRECIP FROM WEST TO EAST THROUGHOUT MONDAY AFTERNOON. HAVE INCREASED WINDS SEVERAL KNOTS ACROSS THE EAST HALF OF THE CWA GIVEN A 1020MB SFC HIGH IN THE UPPER MS VALLEY IMPINGING ON THE BACKSIDE OF THE DEPARTING 1002MB LOW. COULD SEE QUITE A BREEZY DAY FOR MUCH OF THE AREA...WITH WINDS GUSTING OVER 30MPH RIGHT NEAR THE LAKE SUPERIOR SHORE FROM BIG BAY EASTWARD. WILL CONTINUE TO RAMP UP WORDING ON A HIGH SWIM RISK GIVEN THE LABOR DAY HOLIDAY. MONDAY NIGHT...AS THE SFC HIGH SETTLES OVER NORTHERN WI MONDAY NIGHT...CLEAR SKIES AND LOW PWAT VALUES OF LESS THAN 0.5 INCHES WILL ALLOW FOR GOOD RADIATIONAL COOLING. HAVE MAINTAINED PREVIOUS FORECAST TEMPS OF LOW 40S INTERIOR WEST HALF TO LOW 50S NEAR THE GREAT LAKES. RESIDUAL STRONGER NW GRADIENT FLOW ACROSS THE EAST HALF SHOULD LIMIT COOLING TO SOME EXTENT. TUESDAY THROUGH THURSDAY...A SHORTWAVE TROUGH CURRENTLY TRACKING EASTWARD ALONG THE ALLUETIAN ISLANDS WILL STALL OVER WESTERN ALASKA AND SEND A SERIES OF WEAK WAVES ACROSS WESTERN CANADA. THE MAIN WAVE OF INTEREST WILL BECOME AMPLIFIED BY ANOTHER STRONGER WAVE OVER THE NORTH SLOPE OF ALAKSA. TIMING AND STRENGTH OF THIS FEATURE HAVE BEEN UNDERSTANDABLY DIFFICULT FOR THE MODELS TO PIN DOWN. THE GFS HAS WAVERED IN STRENGTH OVER THE LAST SEVERAL RUNS...WITH THE LATEST TWO RUNS INDICATING A SLOWER AND WETTER SOLUTION. THIS IS LIKELY A RESULT OF A LONGER PRECEEDING PERIOD OF LOW-LEVEL MOISTURE RETURN. THE GEM IS THE QUICKEST SOLUTION OF THE THREE. HAVE OPTED TO EMPLOY THE ECMWF FOR THE REST OF THE FORECAST GIVEN ITS MIDDLE GROUND AND CONTINUITY OVER THE LAST COUPLE DAYS. THE MAIN MID-LEVEL AND SFC LOWS WILL TRACK WELL NORTH OF THE CWA...POSSIBLY AS FAR NORTH AS SOUTHERN HUDSON BAY. THE 990MB SFC LOW DEPICTED BY THE ECMWF WILL BE STRONG ENOUGH TO SEND A POTENT COLD FRONT SSE-WARD ACROSS THE CWA WEDNESDAY MORNING. HOWEVER...THERE WILL BE A SUBSTANTIAL AMOUNT OF DRY AIR WITH THIS SYSTEM GIVEN ITS ORIGIN. WILL PLACE ONLY SLIGHT CHANCE POPS ACROSS THE FAR NORTH AND EAST CLOSER TO THE STRONGEST FORCING VIA MID-LEVEL Q-VECTOR CONVERGENCE AND THE LEFT EXIT OF A 120KT UPPER JET. MUCH OF UPPER MI...ESPECIALLY THE SOUTHWEST...LOOKS TO BE UNDER SUBSIDENCE FROM THE RIGHT ENTRANCE OF THE JET...AND MAY NOT EVEN SEE MUCH IN THE WAY OF CLOUD COVER. MOST OF THE COOLER AIR BEHIND THE FRONT WILL STAY EAST OF THE AREA...SO ONLY A SLIGHTLY COOLER DAY THAN WEDNESDAY IS EXPECTED FOR THURSDAY. FRIDAY AND SATURDAY...BESIDE DEVELOPING THE IDEA OF DEEPER TROUGHING ACROSS EASTERN CANADA...MODEL AGREEMENT ON SMALLER SCALE FEATURES IS POOR BY THIS POINT IN THE FORECAST. THE GFS/GEM INDICATE STRONG SFC HIGH PRESSURE BUILDING ACROSS THE AREA...WHILE THE ECMWF KEEP THE HIGH MUCH FARTHER NE NEAR JAMES BAY. A WEAK SHORTWAVE DEPICTED BY BOTH THE ECMWF AND GFS COULD BRING SHOWER CHANCES FOR FRIDAY...BUT TIMING THE GFS IS SOMEWHAT SLOWER WITH THIS IDEA. EITHER WAY...VERY LIMITED MOISTURE WILL PRECLUDE ANYTHING MORE THAN SPOTTY SHOWER COVERAGE. HAVE OPTED TO MAINTAIN CONCENSUS FORECAST AT THIS POINT GIVEN UNCERTAINTY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 151 AM EDT SUN SEP 1 2013 STRONG DISTURBANCE AND ASSOCIATED SFC LOW AND COLD FRONT WILL AFFECT THE REGION THRU THIS FCST PERIOD. ALTHOUGH SHRA/TSRA HAVE DIMINISHED IN COVERAGE OVER THE LAST SEVERAL HRS...STRENGTH OF DISTURBANCE SUGGESTS THERE WILL BE SHRA AND A FEW TSRA SCATTERED AROUND THE AREA THRU THE NIGHT INTO THE MORNING HRS. UNLESS MORE ORGANIZED PCPN DEVELOPS...ONLY VCSH WILL BE UTILIZED AT KIWD/KCMX/KSAW OVERNIGHT. VFR CONDITIONS SHOULD GENERALLY PREVAIL...EXCEPT AT KCMX WHERE SOME BR HAS DEVELOPED WITH LIGHT UPSLOPE. NOT OUT OF THE QUESTION THAT IFR OR EVEN LIFR COULD DEVELOP THERE. AS WINDS VEER THEN SHIFT TO GUSTY NW WITH PASSAGE OF COLD FRONT...EXPECT CONDITIONS TO DETERIORATE TO IFR AT KIWD/KCMX THIS MORNING. LATER FRONTAL PASSAGE AND INITIALLY POST FRONTAL DOWNSLOPE NW WINDS SHOULD RESULT IN ONLY MVFR CIGS AT KSAW MID/LATE AFTN. WITH LATER FRONTAL PASSAGE...IT`S POSSIBLE TSRA COULD AFFECT KSAW EARLY IN THE AFTN. MVFR CIGS SHOULD PREVAIL AT ALL TERMINALS INTO THE EVENING HRS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 359 PM EDT SAT AUG 31 2013 EXPECT SSW WINDS UP TO 20-25 KTS TONIGHT INTO SUN MORNING OVER THE E HALF OF THE LAKE UNDER A SHARPENING PRES GRADIENT AHEAD OF AN APPROACHING COLD FRONT. FOLLOWING THE PASSAGE OF THIS FRONT...THERE WILL BE A WIND SHIFT TO THE NW...WITH WINDS INCREASING UP TO 25 KTS IN THE AFTERNOON. THE COMBINATION OF DECREASING STABILITY WITH THE ARRIVAL OF A COOL AIRMASS AND A SHARPENING PRES GRADIENT BETWEEN A DEPARTING LO PRES SYSTEM AND AN APPROACHING HI WILL RESULT IN NW-N WINDS UP TO 20-30 KTS ON SUN NIGHT INTO MON. THE ARRIVAL OF THE HI AND WEAKER PRES GRADIENT WILL ALLOW WINDS TO DIMINISH UNDER 20 KTS TUE THRU THU. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KLUBER AVIATION...ROLFSON MARINE...KC
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
324 AM MDT SUN SEP 1 2013 ...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR DAY... .DISCUSSION...COLD FRONT APPEARS TO BE IN NORTHEASTERN CO STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED. LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40. WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF 400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST TOWARD TX. TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP SUBTROPICAL MOISTURE INTRUSIONS. 52 && .FIRE WEATHER... UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY. WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM. NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON. NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH RECOVERIES ANTICIPATED. CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO POOR VENTILATION LIKELY OVER THE WEST AND NORTH. A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES. AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY. WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST. HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND CENTRAL NM. && .AVIATION... 06Z TAF CYCLE ISOLD -SHRA AND POSSIBLY A -TSRA WILL LINGER INTO THE LATE NIGHT HOURS MAINLY NORTH OF I-40 AND EAST OF HIGHWAY 550 TO THE BORDER WITH TX/OK. A BACK DOOR COLD FRONT WILL SAG INTO THE NE PLAINS TONIGHT AND THE REST OF THE EASTERN PLAINS ON SUNDAY...BEFORE PUSHING THROUGH GAPS IN THE CENTRAL MOUNTAIN CHAIN WITH A SOMEWHAT GUSTY E CANYON WIND IN THE RIO GRANDE VALLEY LATE SUNDAY AFTN INTO THE NIGHT. THE FRONT WILL BRING MOISTURE AND A TRIGGER FOR TS AND SHRA WITH MORE WDSPRD CONVECTION SUNDAY AFTN AND EVENING. WITH THE FRONT PROGRESSING UP THE EAST SLOPES OF THE CONTDVD...THE CONTDVD REGION COULD REMAIN ACTIVE WITH STORMS INTO THE LATE NIGHT HOURS. 44 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 90 65 90 62 / 20 40 20 20 DULCE........................... 83 51 80 51 / 40 50 50 40 CUBA............................ 85 56 82 54 / 50 40 60 60 GALLUP.......................... 86 57 86 55 / 20 40 40 40 EL MORRO........................ 84 54 82 52 / 30 50 60 50 GRANTS.......................... 88 57 85 54 / 40 50 60 50 QUEMADO......................... 86 57 85 55 / 40 40 50 50 GLENWOOD........................ 90 62 89 61 / 20 20 30 30 CHAMA........................... 80 47 79 45 / 50 60 60 60 LOS ALAMOS...................... 86 58 83 56 / 50 40 50 50 PECOS........................... 83 56 81 55 / 60 60 60 60 CERRO/QUESTA.................... 79 51 77 49 / 70 50 60 50 RED RIVER....................... 69 40 66 41 / 80 60 70 60 ANGEL FIRE...................... 74 39 72 39 / 80 60 70 60 TAOS............................ 83 55 81 52 / 50 50 50 50 MORA............................ 78 53 74 51 / 70 70 60 60 ESPANOLA........................ 91 60 87 59 / 40 30 40 40 SANTA FE........................ 87 59 83 57 / 50 40 50 50 SANTA FE AIRPORT................ 91 60 86 59 / 40 30 40 40 ALBUQUERQUE FOOTHILLS........... 91 66 87 64 / 40 30 40 40 ALBUQUERQUE HEIGHTS............. 93 70 89 69 / 30 30 30 40 ALBUQUERQUE VALLEY.............. 95 64 91 62 / 20 30 30 40 ALBUQUERQUE WEST MESA........... 95 65 90 65 / 20 30 30 40 LOS LUNAS....................... 96 67 93 65 / 20 30 30 40 RIO RANCHO...................... 94 68 90 67 / 30 30 30 40 SOCORRO......................... 95 67 91 66 / 20 20 20 30 SANDIA PARK/CEDAR CREST......... 85 54 82 55 / 50 50 50 50 TIJERAS......................... 89 59 85 58 / 50 40 50 40 MORIARTY/ESTANCIA............... 91 56 87 56 / 50 30 50 50 CLINES CORNERS.................. 85 58 80 58 / 60 60 70 60 GRAN QUIVIRA.................... 88 60 82 59 / 40 30 40 50 CARRIZOZO....................... 91 61 86 59 / 30 20 40 40 RUIDOSO......................... 82 56 74 53 / 30 40 60 60 CAPULIN......................... 82 54 80 53 / 70 50 50 40 RATON........................... 84 56 81 55 / 60 50 50 40 SPRINGER........................ 88 56 83 56 / 70 50 50 40 LAS VEGAS....................... 84 55 79 55 / 70 70 50 50 CLAYTON......................... 90 62 86 63 / 50 40 30 20 ROY............................. 88 60 82 61 / 60 50 50 40 CONCHAS......................... 94 66 89 66 / 50 50 40 40 SANTA ROSA...................... 94 65 87 64 / 40 50 40 40 TUCUMCARI....................... 96 66 89 65 / 50 50 40 30 CLOVIS.......................... 94 64 86 63 / 20 40 40 30 PORTALES........................ 94 67 87 64 / 20 30 40 30 FORT SUMNER..................... 95 67 89 65 / 30 40 40 40 ROSWELL......................... 98 69 91 67 / 10 20 40 40 PICACHO......................... 92 64 86 62 / 20 20 40 50 ELK............................. 86 60 79 57 / 20 20 50 60 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 52
AREA FORECAST DISCUSSION
NWS RALEIGH NC
302 AM EDT SUN SEP 01 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT... THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND TUESDAY NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST WEDNESDAY INTO THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 220 AM SUNDAY... WE`RE STILL EXPECTING SCATTERED SHOWERS/STORMS TODAY INTO THIS EVENING... ALTHOUGH DETAILS AS TO WHO WILL SEE THE BEST CHANCES AND WHEN REMAIN MURKY. LATEST SURFACE MAP SHOWS THE SYNOPTIC FRONTAL ZONE EXTENDING FROM A LOW OVER THE UPPER MIDWEST ACROSS THE LOWER GREAT LAKES AND ST LAWRENCE VALLEY... WHILE WEAK LEE SURFACE TROUGHING HOLDS OVER CENTRAL VA/NC. TWO PRIMARY FORCING FEATURES ARE EXPECTED TO DRIVE OUR PRECIP CHANCES TODAY. FIRST IS A MID LEVEL SHORTWAVE -- A REFLECTION OF YESTERDAY`S CONVECTION TO THE WEST OVER THE MOUNTAINS -- NOW TRACKING THROUGH MD/VA/NC AND EXPECTED TO SHIFT SLOWLY ESE THEN EAST INTO ERN VA/NC THIS MORNING. THIS SHOULD ENCOUNTER A MOIST (AND INCREASINGLY SO... WITH PW VALUES EXPECTED TO QUICKLY JUMP UP TOWARD 1.8-1.9 IN.) ENVIRONMENT OVER THE COASTAL PLAIN AND COASTAL AREA. WITH DEW POINTS IN THE 70-75 RANGE AND GOOD MORNING HEATING ALLOWING THE CONVECTIVE TEMP TO BE REACHED BY MID-LATE MORNING... EXPECT EARLY DEVELOPMENT OF SHOWERS/STORMS OVER THE COASTAL PLAIN AND SANDHILLS... AUGMENTED BY AN INLAND-MOVING SEA BREEZE BY AFTERNOON. THE SECOND FEATURE OF INTEREST IS AN MCV RESULTING FROM THE ORGANIZED STORMS NOW OVER SRN IN/IL EXTENDING THROUGH THE OH VALLEY. THIS WAVE SHOULD FOLLOW IN THE TRACKS OF THE PREVIOUS ONE... SHIFTING ESE THEN EAST DURING THE DAY... POTENTIALLY ENHANCING CONVECTION OVER THE CENTRAL/SRN APPALACHIANS WHICH WOULD THEN DRIFT EASTWARD OFF THE HIGHER TERRAIN INTO THE FOOTHILLS AND WRN PIEDMONT LATER IN THE DAY INTO EARLY EVENING. THE NAM/GFS GENERALLY FIT WITH THE SCENARIO OUTLINED HERE FOR THE TWO FEATURES... SO WHILE THE OVERALL FORECAST WILL REFLECT SCATTERED STORMS (30-50% POPS) OVER ALL OF CENTRAL NC... THE FORECAST TIMING WILL SHOW GREATER POPS SOUTHEAST OF RALEIGH STARTING IN THE LATE MORNING... THEN PEAKING LATER (MID AFTERNOON) OVER THE WRN PIEDMONT... SHIFTING EAST INTO THE ERN PIEDMONT AND WRN SANDHILLS BEFORE DISSIPATING BY MID TO LATE EVENING WITH LOSS OF HEATING AND WEAK POST-WAVE SUBSIDENCE. REGARDING STORM STRENGTH... MLCAPE IS EXPECTED TO TOP OUT AT 1500-2000 J/KG MAINLY OVER THE ERN CWA... BUT DEEP LAYER SHEAR REMAINS WEAK AT AROUND 15 KTS. WE MAY SEE A FEW STRONG GUSTS WITH ISOLATED CELLS BASED ON THE FORECAST SOUNDING PROFILES... BUT WIDESPREAD STRONG/SEVERE STORMS ARE NOT EXPECTED. TEMPS ARE TOUGH AS ABOVE-NORMAL THICKNESSES (BY ABOUT 10-12 M) WILL BE MODULATED BY SOME MORNING STRATUS AND CONVECTIVE CLOUD COVER THIS AFTERNOON. GRIDDED LAMP GUIDANCE INDICATES HIGHS OF 88-92... CLOSE TO THAT INDICATED BY A DRY ADIABATIC LAPSE RATE... AND ABOUT A DEGREE ABOVE EARLIER FORECAST HIGHS. EXPECT GENERALLY PARTLY CLOUDY SKIES TONIGHT WITH VARYING DEGREES OF CONVECTIVE DEBRIS CLOUDINESS OVER THE REGION. LOWS 69-73. -GIH && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SUNDAY... SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE... THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT 1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS... WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS... ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15 KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN CONVECTIONS DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430 M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR 90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 215 AM SUNDAY... THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S. TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND SATURDAY. THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT. GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE SOUTHERN COASTAL PLAIN. THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S. FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC. THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 120 AM SUNDAY... CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR -- SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING). LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE NW WITH MUCH DRIER AIR. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...BLAES AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
224 AM EDT SUN SEP 01 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND TUESDAY NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST WEDNESDAY INTO THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 220 AM SUNDAY... WE`RE STILL EXPECTING SCATTERED SHOWERS/STORMS TODAY INTO THIS EVENING... ALTHOUGH DETAILS AS TO WHO WILL SEE THE BEST CHANCES AND WHEN REMAIN MURKY. LATEST SURFACE MAP SHOWS THE SYNOPTIC FRONTAL ZONE EXTENDING FROM A LOW OVER THE UPPER MIDWEST ACROSS THE LOWER GREAT LAKES AND ST LAWRENCE VALLEY... WHILE WEAK LEE SURFACE TROUGHING HOLDS OVER CENTRAL VA/NC. TWO PRIMARY FORCING FEATURES ARE EXPECTED TO DRIVE OUR PRECIP CHANCES TODAY. FIRST IS A MID LEVEL SHORTWAVE -- A REFLECTION OF YESTERDAY`S CONVECTION TO THE WEST OVER THE MOUNTAINS -- NOW TRACKING THROUGH MD/VA/NC AND EXPECTED TO SHIFT SLOWLY ESE THEN EAST INTO ERN VA/NC THIS MORNING. THIS SHOULD ENCOUNTER A MOIST (AND INCREASINGLY SO... WITH PW VALUES EXPECTED TO QUICKLY JUMP UP TOWARD 1.8-1.9 IN.) ENVIRONMENT OVER THE COASTAL PLAIN AND COASTAL AREA. WITH DEW POINTS IN THE 70-75 RANGE AND GOOD MORNING HEATING ALLOWING THE CONVECTIVE TEMP TO BE REACHED BY MID-LATE MORNING... EXPECT EARLY DEVELOPMENT OF SHOWERS/STORMS OVER THE COASTAL PLAIN AND SANDHILLS... AUGMENTED BY AN INLAND-MOVING SEA BREEZE BY AFTERNOON. THE SECOND FEATURE OF INTEREST IS AN MCV RESULTING FROM THE ORGANIZED STORMS NOW OVER SRN IN/IL EXTENDING THROUGH THE OH VALLEY. THIS WAVE SHOULD FOLLOW IN THE TRACKS OF THE PREVIOUS ONE... SHIFTING ESE THEN EAST DURING THE DAY... POTENTIALLY ENHANCING CONVECTION OVER THE CENTRAL/SRN APPALACHIANS WHICH WOULD THEN DRIFT EASTWARD OFF THE HIGHER TERRAIN INTO THE FOOTHILLS AND WRN PIEDMONT LATER IN THE DAY INTO EARLY EVENING. THE NAM/GFS GENERALLY FIT WITH THE SCENARIO OUTLINED HERE FOR THE TWO FEATURES... SO WHILE THE OVERALL FORECAST WILL REFLECT SCATTERED STORMS (30-50% POPS) OVER ALL OF CENTRAL NC... THE FORECAST TIMING WILL SHOW GREATER POPS SOUTHEAST OF RALEIGH STARTING IN THE LATE MORNING... THEN PEAKING LATER (MID AFTERNOON) OVER THE WRN PIEDMONT... SHIFTING EAST INTO THE ERN PIEDMONT AND WRN SANDHILLS BEFORE DISSIPATING BY MID TO LATE EVENING WITH LOSS OF HEATING AND WEAK POST-WAVE SUBSIDENCE. REGARDING STORM STRENGTH... MLCAPE IS EXPECTED TO TOP OUT AT 1500-2000 J/KG MAINLY OVER THE ERN CWA... BUT DEEP LAYER SHEAR REMAINS WEAK AT AROUND 15 KTS. WE MAY SEE A FEW STRONG GUSTS WITH ISOLATED CELLS BASED ON THE FORECAST SOUNDING PROFILES... BUT WIDESPREAD STRONG/SEVERE STORMS ARE NOT EXPECTED. TEMPS ARE TOUGH AS ABOVE-NORMAL THICKNESSES (BY ABOUT 10-12 M) WILL BE MODULATED BY SOME MORNING STRATUS AND CONVECTIVE CLOUD COVER THIS AFTERNOON. GRIDDED LAMP GUIDANCE INDICATES HIGHS OF 88-92... CLOSE TO THAT INDICATED BY A DRY ADIABATIC LAPSE RATE... AND ABOUT A DEGREE ABOVE EARLIER FORECAST HIGHS. EXPECT GENERALLY PARTLY CLOUDY SKIES TONIGHT WITH VARYING DEGREES OF CONVECTIVE DEBRIS CLOUDINESS OVER THE REGION. LOWS 69-73. -GIH && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 215 PM SATURDAY... MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW 90S...LOWS UPPER 70S. -MLM && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 215 AM SUNDAY... THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S. TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND SATURDAY. THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT. GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE SOUTHERN COASTAL PLAIN. THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S. FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC. THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 120 AM SUNDAY... CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR -- SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING). LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE NW WITH MUCH DRIER AIR. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...MLM LONG TERM...BLAES AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
215 AM EDT SUN SEP 01 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL CONTINUE THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT...THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS TUESDAY AND TUESDAY NIGHT. BEHIND THE FRONT... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST WEDNESDAY INTO THURSDAY. && .NEAR TERM /OVERNIGHT/... AS OF 1025 PM SATURDAY... BAND OF SHOWERS AND THUNDERSTORMS WHICH ENTERED THE NW PIEDMONT AROUND 21Z DIMINISHED AS IT DRIFTED EAST. AIR MASS OVER BULK OF THE PIEDMONT NOT AS UNSTABLE AS THE FOOTHILLS AND WESTERN PIEDMONT PLUS LACK OF DECENT SHEAR AND LACK OF UPPER LEVEL SUPPORT LED TO THE DISSIPATION OF MOST OF THE SHOWERS. ANOTHER UPPER LEVEL DISTURBANCE IS APPROACHING WESTERN NC FROM THE EASTERN TN VALLEY. THIS FEATURE PROJECTED TO CROSS OUR REGION OVERNIGHT (AFTER 06Z). WITH PRECIP WATER VALUES 1.8-2 INCHES AND A FEW SFC TROUGHS/OUTFLOW BOUNDARIES EXISTING ACROSS THE REGION...COULD SEE A REGENERATION IN SHOWER/ISOLATED THUNDERSTORM ACTIVITY OVERNIGHT-EARLY SUNDAY MORNING. PLAN TO MAINTAIN A SMALL CHANCE POP ACROSS THE FAR NW-NORTHERN PIEDMONT...AND SLIGHT CHANCE ACROSS MOST OF THE REMAINDER OF CENTRAL NC. OVERNIGHT MIN TEMPS SHOULD BE FAIRLY UNIFORM AROUND 70. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 215 PM SATURDAY... CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000 J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW... THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40% CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY... PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW 90S...LOWS UPPER 70S. -MLM && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 215 AM SUNDAY... THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S. TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND SATURDAY. THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT. GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE SOUTHERN COASTAL PLAIN. THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S. FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC. THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 120 AM SUNDAY... CURRENT VFR CONDITIONS ARE EXPECTED TO YIELD TO IFR CONDITIONS LATE TONIGHT... BUT CONFIDENCE IN THE TIMING AND EXTENT OF LOW CIGS/VSBYS IS LOWER THAN USUAL. THE SURFACE MAP SHOWS THE LARGE SCALE COLD FRONT STILL WELL TO OUR NORTH (EAST-WEST ACROSS THE LOWER GREAT LAKES) WITH A WEAK LEE TROUGH EAST OF THE APPALACHIANS EXTENDING THROUGH CENTRAL NC... AND THIS SETUP SHOULD CHANGE LITTLE THROUGH THE NEXT 24 HOURS. A WARM/MOIST LOW LEVEL FLOW FROM THE SW CONTINUES TO PUMP INCREASING LOW LEVEL MOISTURE INTO THE AREA... AND THIS WILL LIKELY LEAD TO FORMATION OF IFR STRATUS AND MVFR FOG AS THE LOW LEVELS STABILIZE FURTHER AND DECOUPLE. THE RESIDUAL CLOUDS FROM EARLIER STORMS OVER THE MOUNTAINS/FOOTHILLS HAVE MOVED EAST OF THE TRIAD AND INTO THE ERN AND SRN PIEDMONT... AND THE BRIEF CLEARING SKIES AND MOIST GROUND AT INT/GSO (THE ONLY CENTRAL NC TAF SITES THAT SAW RAIN TODAY) SHOULD FACILITATE DEVELOPMENT OF LOW CLOUDS AND FOG. THIS IS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL INDICATING POSSIBLE VSBYS UNDER A HALF MILE AT INT/GSO. FARTHER EAST... THE RESIDUAL CLOUDS DRIFTING EASTWARD SHOULD LIMIT FOG FORMATION AND DELAY (IF NOT LIMIT) LOW CLOUD DEVELOPMENT... HOWEVER THE NAM/GFS STATISTICAL GUIDANCE SUGGESTS THAT ALMOST THE OPPOSITE WILL OCCUR -- SHOWING CIGS DROPPING TO UNDER 1000 FT LATE TONIGHT AT THE EASTERN TAF SITES OF RDU/RWI/FAY OVERNIGHT. WILL INDICATE A TREND TO PREVAILING IFR CIGS/VSBYS AT INT/GSO THROUGH DAYBREAK... WITH JUST TEMPORARY IFR CONDITIONS AT RDU/FAY/RWI FOR NOW UNTIL THE PICTURE BECOMES CLEARER. EXPECT VFR CONDITIONS TO RESUME AT ALL SITES WITH DAYTIME HEATING AFTER 14Z. SCATTERED SHOWERS/STORMS EXPECTED FROM LATE MORNING THROUGH THE AFTERNOON HOURS MAY PRODUCE LOCALLY HEAVY DOWNPOURS AND GUSTY WINDS WITH BRIEF IFR/LIFR CONDITIONS AT ANY SITE. OTHERWISE... VFR CONDITIONS SHOULD DOMINATE THROUGH THE END OF THE TAF VALID PERIOD (06Z EARLY MONDAY MORNING). LOOKING BEYOND 06Z EARLY MONDAY MORNING... SHALLOW IFR FOG IS POSSIBLE 08Z-12Z AT ALL FIVE TAF SITES AS WE MAINTAIN A LIGHT SW SURFACE FLOW. ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED ACROSS CENTRAL NC BOTH MONDAY AND TUESDAY AFTERNOON/EVENING... AHEAD OF A COLD FRONT APPROACHING SLOWLY FROM THE NW... AND ANY OF THESE SHOWERS/STORMS COULD GENERATE GUSTY WINDS AND SUB-VFR CONDITIONS WITH BRIEF HEAVY RAIN. VFR CONDITIONS ARE LIKELY TO RETURN FOR WEDNESDAY/THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE NW WITH MUCH DRIER AIR. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...WSS SHORT TERM...VINCENT/MLM LONG TERM...BLAES AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CDT SUN SEP 1 2013 .UPDATE... ISSUED AT 1245 AM CDT SUN SEP 1 2013 CURRENTLY...HIGH PRESSURE WAS CENTERED OVER CENTRAL/SOUTHERN SASKATCHEWAN WITH THE HIGH AXIS EXTENDING INTO EASTERN MONTANA. AN AREA OF VFR/MVFR CLOUDS OVER SOUTHERN SASKATCHEWAN AND MANITOBA HAD EDGED INTO FAR NORTHERN NORTH DAKOTA. MODELS STILL SUGGESTING THESE CLOUDS WILL MOVE SOUTH ACROSS THE STATE OVERNIGHT. THE HIGH IS FORECAST TO MOVE SOUTHEAST AND BY EARLY AFTERNOON BE CENTERED OVER LAKE WINNIPEG INTO THE JAMES/RED RIVER VALLEYS. NORTHWEST WINDS SHOULD BECOME NORTH...THEN NORTHEAST OVERNIGHT INTO THE LATER MORNING HOURS. LOWERED OVERNIGHT LOWS A BIT...ESPECIALLY IN THE SOUTH WHICH SHOULD REMAIN CLOUD-FREE UNTIL LATER TONIGHT. CURRENT FORECAST LOOKS ON TRACK. UPDATE ISSUED AT 954 PM CDT SAT AUG 31 2013 CLEAR SKIES ACROSS ALL BUT THE FAR NORTHWEST THIS EVENING WITH DIMINISHING NORTH TO NORTHWEST WINDS. EXTENSIVE CLOUD COVER ACROSS SOUTHERN SASKATCHEWAN AND MANITOBA IS PUSHING SOUTH AND IS EXPECTED TO DROP SOUTH ACROSS WESTERN AND CENTRAL NORTH DAKOTA LATE TONIGHT. LATEST 01 SEP 00Z NAM AND RUC GUIDANCE SUGGESTS HIGHEST 925-850MB RH SHOULD CONTINUE TO PUSH SOUTH THROUGH EASTERN PORTIONS OF THE CWA...BUT LINGER IN THE WEST...MAINLY FROM ISN TO BETWEEN BISMARCK AND DICKINSON ON THE BACK SIDE OF THE SURFACE HIGH. ADJUSTED CLOUD COVER BASED ON LATEST LOW LEVEL RH GUIDANCE. OTHERWISE A QUIET NIGHT WITH DIMINISHING WINDS AND COMFORTABLE TEMPERATURES MAINLY IN THE 50S. UPDATE ISSUED AT 638 PM CDT SAT AUG 31 2013 MUCH COOLER AIR BEHIND AN EXITING COLD FRONT WILL CONTINUE TO SPILL ACROSS WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. AN UPPER LEVEL LOW ACROSS MANITOBA HAS MOVED FAR ENOUGH EAST THAT EARLY EVENING SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL. OTHER THAN REMOVING POPS NORTH CENTRAL AND MINOR CLOUD COVER ADJUSTMENTS...THE CURRENT FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 250 PM CDT SAT AUG 31 2013 DRIER AND COOLER AIR WILL HIGHLIGHT THE SHORT TERM FORECAST. AS OF 20 UTC...THE COLD FRONT HAS CLEARED THE CWA WITH LOW LEVEL DRY AND COLD AIR ADVECTION ACROSS WESTERN AND CENTRAL NORTH DAKOTA AND WIDESPREAD WIND GUSTS OF 25-30 KTS IN POST FRONTAL MIXING. DID ADD A MENTION OF ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE NORTH CENTRAL THIS AFTERNOON AND EARLY EVENING WITH THE UPPER LEVEL LOW THAT IS PROPAGATING SOUTHEAST OUT OF FAR SOUTHEAST SASKATCHEWAN. ANY CONVECTION THAT DOES FORM WILL FADE WITH SUNSET. AN EXPANSE OF STRATUS IS EXPECTED TO OVERSPREAD AREAS ALONG AND NORTH OF I-94 TONIGHT...WHICH WILL HELP TO KEEP OVERNIGHT LOWS IN THE 50S. A QUIET A REFRESHINGLY COOL DAY IS EXPECTED SUNDAY WITH HIGHS IN THE 70S WITH HIGH PRESSURE IN PLACE. GIVEN GOOD AGREEMENT...A BLEND OF THE 12 UTC GUIDANCE SUITE WAS USED FOR ALL FIELDS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 250 PM CDT SAT AUG 31 2013 AFTER A COOL AND DRY SUNDAY...WILL SEE A WARMING TREND BACK TO ABOVE NORMAL TEMPERATURES THROUGH THE COMING WORK WEEK AS THE CENTRAL U.S. UPPER RIDGE REBUILDS/AMPLIFIES FROM ACROSS THE ROCKIES NORTH INTO THE CANADIAN HIGH PLAINS...BRINGING WAA BACK EAST INTO THE DAKOTAS. EXPECT MOSTLY DRY CONDITIONS OVER NORTH DAKOTA THROUGH THURSDAY NIGHT WITH A DRY NORTHWEST FLOW ALOFT. THE EXCEPTION MAY BE THE TUESDAY AFTERNOON THROUGH WEDNESDAY NIGHT PERIOD WHEN MODELS PROJECT AN EMBEDDED S/WV IMPULSE MOVING THROUGH THE RIDGE FROM ACROSS SOUTHERN MONTANA EAST INTO THE DAKOTAS. HAVE CONFINED SLIGHT CHANCE POPS FOR NOW TUESDAY NIGHT THROUGH WED NIGHT. THE LATEST ECMWF (12Z) NOW BRINGS THIS FEATURE TO THE ND/MT BORDER BY 00Z WED...SO FUTURE UPDATED FORECASTS MAY NEED TO ADD SOME MENTION OF THUNDERSTORMS STARTING TUESDAY AFTERNOON ACROSS THE WEST. AS WE HEAD INTO THE LATER PORTIONS OF THE WORK WEEK AND THE FIRST HALF OF NEXT WEEKEND...MODELS PROJECT THE RIDGE TO BREAKDOWN AS A CLOSED UPPER LOW (NOW OFF THE NORTHWEST U.S. COAST) MOVES INLAND SOMETIME THURSDAY NIGHT OR FRIDAY...THEN EAST TOWARDS THE NORTHERN PLAINS SOMETIME FRI-SUN. LATEST GFS/ECMWF DIFFER ON THE TIMING OF THIS FEATURE...SO LOTS OF UNCERTAINTY STILL IN PLAY. EVENTUALLY THIS FEATURE WILL BE THE FOCUS OF LATER FORECASTS AS IT IS EXPECTED TO BRING COOLER WEATHER AND INCREASED CHANCES FOR PRECIPITATION TO OUR REGION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1245 AM CDT SUN SEP 1 2013 LATEST GUIDANCE IS STILL SUGGESTING LOW VFR TO MVFR CEILINGS DROPPING SOUTH INTO THE FORECAST AREA OVERNIGHT AND SUNDAY MORNING. THEN IMPROVING CEILINGS LATE SUNDAY MORNING WITH A NORTH FLOW SHIFTING EAST TO SOUTHEAST SUNDAY AFTERNOON. BROUGHT VFR CIGS TO KISN/KMOT AT 06Z...THEN MVFR BY 09Z...THEN IMPROVING TO VFR CIGS BY AROUND 16Z. SOUTHERN TAF SITES KDIK/KBIS/KJMS...BROUGHT VFR CIGS BY 09Z/10Z THEN MVFR BY AROUND 12Z...IMPROVING TO VFR BY 18Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...AYD LONG TERM...NH AVIATION...JV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
401 AM EDT SUN SEP 1 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7 TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT. SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION. WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET. INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN. ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION. THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH. TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH PRESSURE MOVES INTO THE AREA FROM THE NW. RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR DAY WEEKEND. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK. TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED PRECIPITATION. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... ISOLD SHOWERS/STORMS CONTINUING TO LINGER THROUGH ABOUT 11Z...WITH BRIEF MVFR/IFR CONDITIONS IN VICINITY. OTHERWISE...PATCHY MVFR/IFR FOG...BUT MOST AREAS SHOULD REMAIN VFR UNDER EXTENSIVE CLOUD SHIELD. CONVECTION WILL INCREASE IN COVERAGE AGAIN AFTER 12Z...AS AN UPPER DISTURBANCE MOVES EAST THROUGH THE AREA. EXPECT BRIEF MVFR/IFR CONDITIONS AND GUSTY WINDS IN VICINITY OF STORMS. BULK OF CONVECTION WILL DIE DOWN AFTER 03Z. FOG DEVELOPMENT TONIGHT WILL DEPEND ON THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE DAY. BEST LOCATION FOR POTENTIAL FOG DEVELOPMENT WILL BE EASTERN KENTUCKY AND SOUTHEAST OHIO WHERE BETTER CLEARING IS EXPECTED. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND POTENTIAL FOR CONVECTION DEPENDS ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG TIMING AND DENSITY MAY VARY FROM CURRENT FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SUN 09/01/13 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY M M L L H H H H H H H H HTS CONSISTENCY M M L L M H H H H H H M BKW CONSISTENCY H H H H M H H H H H H H EKN CONSISTENCY M L L L M M L H H H H H PKB CONSISTENCY M M L L H H H H H H H M CKB CONSISTENCY M M L L H H H H H H H H AFTER 06Z MONDAY... IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE TUESDAY AND WEDNESDAY MORNINGS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL SHORT TERM...TRM LONG TERM...26 AVIATION...SL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
518 AM EDT SUN SEP 1 2013 .SYNOPSIS... MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... 5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG. AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA. ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE NEEDED. STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL. THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE HIGHEST CHANCES BY MID AFTN. TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES. SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE HEAVY RAIN AND FLASH FLOODING STILL A THREAT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY. CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING. WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED. LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE NITE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW NORMAL AND RISE TO NEAR NORMAL. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... AT KCLT /09Z UPDATE/...SPOTTY MVFR TO IFR FOG ACCOMPANIED BY LOW CIGS OBSERVED NEARBY...BUT SO FAR THE FIELD HAS AVOIDED ANY RESTRICTIONS. MOST RELIABLE NEAR TERM GUIDANCE /08Z LAMP/ TAKES KCLT DOWN TO MVFR NEAR DAYBREAK. I THINK ALL IT WILL TAKE TO GET MVFR FOG IS A TINY DROP IN TEMPS...BUT THAT MAY NOT OCCUR SO JUST PUT MVFR IN TEMPO. A GREATER RISK IS FOR SOME LOW CIGS TO DRIFT IN...SO WILL KEEP MONITORING. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL KEEP A PROB30 DURING THE AFTERNOON...AND A VCSH SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD. FOLLOWING THE END OF THE DIURNAL CONVECTION GUIDANCE SUPPORTS VFR FCST THRU 06Z WITH MAINLY MID CLOUDS. WINDS WILL REMAIN LIGHT SW THRU THE PERIOD. ELSEWHERE...SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST EARLY TODAY THOUGH CURRENT TRENDS SUGGEST LITTLE THREAT TO KAVL OR ANY OTHER TAF SITE. MOIST CONDITIONS AND IN SOME CASES WET SOILS FROM SAT AFTN RAIN HAS ALREADY ALLOWED MVFR TO IFR FOG ACRS MUCH OF THE AREA. SOME LOWERING STILL POSSIBLE THOUGH CIRRUS DEBRIS MOVING OVERHEAD WILL BE A MITIGATING FACTOR IN FOG/CIGS...AND INDEED A FEW SITES HAVE IMPROVED SLIGHTLY UNDER THE CIRRUS. LIFR AT KAVL AND IN OTHER MTN VALLEYS. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL KEEP A PROB30 DURING THE AFTERNOON AS WELL AS A VCSH/VCTS AS NECESSARY TO INDICATE LESSER PROBABILITY INTO THE EVENING. FLOW REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH VFR IS EXPECTED THRU 06Z EXCEPT FOR MVFR FOG DEVELOPING PRIOR TO THEN AT KAVL. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER AIR WILL FOLLOW THE FRONT. CONFIDENCE TABLE... 09-15Z 15-21Z 21-03Z 03-09Z KCLT MED 77% HIGH 85% HIGH 100% HIGH 100% KGSP HIGH 80% MED 78% HIGH 100% HIGH 100% KAVL MED 65% HIGH 85% HIGH 100% HIGH 100% KHKY HIGH 86% MED 64% HIGH 100% HIGH 100% KGMU MED 76% MED 78% HIGH 100% HIGH 100% KAND MED 72% HIGH 85% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
319 AM CDT SUN SEP 1 2013 .DISCUSSION... NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST TOWARD THE UPPER TEXAS COAST. ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109 AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON. IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM. SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS. MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS. THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS. THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON WHERE THIS FEATURE TRACKS. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 102 79 98 77 98 / 10 40 20 20 10 WACO, TX 101 77 100 75 98 / 5 20 20 20 20 PARIS, TX 101 74 96 71 96 / 20 30 20 10 10 DENTON, TX 103 77 97 72 97 / 20 40 20 10 10 MCKINNEY, TX 102 76 97 73 98 / 20 40 20 10 10 DALLAS, TX 103 80 98 78 99 / 10 40 20 20 10 TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10 CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10 TEMPLE, TX 99 74 98 74 97 / 5 10 20 20 20 MINERAL WELLS, TX 102 74 95 73 96 / 10 40 30 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119. && $$ 05/
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1146 PM CDT SAT AUG 31 2013 .AVIATION... IN THE SHORT TERM A CLUSTER OF THUNDERSTORMS OVER SOUTHWEST KANSAS IS SHOWING SOME TENDENCY TO DRIFT TO THE SOUTH-SOUTHEAST AND MAY YET END UP IN THE SOUTHEAST PANHANDLE LATER TONIGHT NOT FAR FROM KCDS. MOST SOLUTIONS DIMINISH THIS ACTIVITY BEFORE REACHING KCDS WHILE THE LATEST HRRR DOES BRING LIGHTER SHOWERS TO THE AREA AFTER 14Z. WE REMAIN UNCONVINCED SO WILL RETAIN THE MID LEVEL CLOUD INCREASE AT KCDS AFTER 14Z. OTHERWISE...ARRIVAL OF THE COLD FRONT BY LATE SUNDAY EVENING OR POSSIBLY DELAYED UNTIL EARLY MONDAY MORNING SHOULD OFFER AT LEAST SOME OPPORTUNITY FOR THUNDER AT BOTH KLBB AND KCDS. LATEST SOLUTIONS ARE NOT TERRIBLY EAGER TO MOVE ACTIVITY IN BEFORE 06Z HOWEVER. WE WILL FOLLOW THIS LACKADAISICAL APPROACH AND AVOID ADDING IMPLICIT THUNDER TO THE END OF THE 06Z TAFS JUST YET. RMCQUEEN && .PREV DISCUSSION... /ISSUED 617 PM CDT SAT AUG 31 2013/ AVIATION... QUIET VFR CONDITIONS IN STORE THIS EVENING AND OVERNIGHT ALTHOUGH DEVELOPING ISOLATED THUNDERSTORMS OVER THE OKLAHOMA PANHANDLE WILL HAVE A TENDENCY TO DRIFT SOUTHEAST THROUGH THE EASTERN TEXAS PANHANDLE OVERNIGHT. ALL SOLUTIONS END ACTIVITY BEFORE REACHING CHILDRESS...ALTHOUGH A MID LEVEL CLOUD LAYER SEEMS LIKELY TO SURVIVE INTO KCDS EARLY SUNDAY ALONG WITH PERHAPS A SHIFT TO MORE VARIABLE SURFACE WINDS. WILL TRY TO ADDRESS THIS WITH MORE CONFIDENCE FOR THE 06Z TAF. OTHERWISE FOCUS WILL BE TOWARDS INCREASING THUNDER CHANCES FOR BOTH TAF SITES JUST BEYOND THE END OF THIS TAF PERIOD WITH APPROACHING WEAK COLD FRONT. RMCQUEEN PREV DISCUSSION... /ISSUED 245 PM CDT SAT AUG 31 2013/ SHORT TERM... THE PERSISTENT UPPER RIDGE CENTERED OVER NEW MEXICO WAS PROVIDING ANOTHER HOT DAY FOR THE SOUTH PLAINS REGION. 19Z TEMPERATURES WERE RUNNING 1-3 DEGREES ABOVE YESTERDAY AT THIS TIME...VARYING FROM THE MID-90S ON THE CAPROCK TO AT OR JUST ABOVE 100 ACROSS THE FAR EASTERN ZONES. THE HIGH SO FAR AT KLBB HAS REACHED 97 DEGREES AND WILL TOP OUT VERY CLOSE TO THE RECORD OF 100 DEGREES...SET BACK IN 1930. THE STRONG HEATING AND RESULTANT DEEP MIXING WAS NOW SUPPORTING A FEW HIGH-BASED CUMULUS...THOUGH LIMITED MOISTURE/INSTABILITY AND WARM MID-LEVELS SHOULD KEEP THESE CLOUDS LIMITED IN VERTICAL EXTENT. INSTEAD...THE CLOSEST CONVECTION WAS FIRING ACROSS THE HIGHER TERRAIN OF NEW MEXICO AND COLORADO...WITH ADDITIONAL DEVELOPMENT POSSIBLE INTO THE NORTHERN TEXAS PANHANDLE THROUGH WESTERN KANSAS. WEAK STEERING FLOW WILL DIRECT THIS ACTIVITY SLOWLY SOUTHEASTWARD AND THERE IS AN OUTSIDE CHANCE DECAYING CONVECTION COULD AFFECT THE NORTHEAST ZONES LATE TONIGHT/EARLY SUNDAY...THOUGH THE MORE LIKELY OUTCOME IS AN INCREASE IN MID/HIGH CLOUDINESS. THE WESTERN RIDGE WILL AMPLIFY OVER THE ROCKIES THROUGH SUNDAY IN ADVANCE OF AN UPPER LOW OFF THE WEST COAST WHILE A POTENT SHORTWAVE TROUGH TRANSLATES ACROSS THE UPPER MIDWEST AND INTO THE GREAT LAKES. THIS MODEST PATTERN ADJUSTMENT WILL ALLOW HEIGHTS TO DECREASE SLIGHTLY LOCALLY WHILE ALSO CAUSING THE MONSOONAL MOISTURE PLUME TO BEND SOUTHWARD AND OVER THE AREA LATER IN THE DAY. IN ADDITION...THE PASSING NORTHERN WAVE WILL PROPEL A COLD FRONT SOUTHWARD THROUGH THE PLAINS...WITH THE LATEST INDICATIONS THAT THE FRONT WILL BE NEAR OR INTO OUR NORTHERN ZONES BY LATE SUNDAY AFTERNOON. THE COMBINATION OF THE FRONT...IMPROVED MID-LEVEL MOISTURE AND PERHAPS WEAK UPPER SUPPORT WITHIN THE MOISTURE PLUME WILL RESULTING IN INCREASING SHOWER/STORM CHANCES SUNDAY AFTERNOON INTO SUNDAY NIGHT. BEFORE 00Z...EXPECT THE BEST CHANCE OF CONVECTION TO FAVOR THE NORTHERN HALF OF THE CWA WHERE SLIGHT CHANCE POPS WERE MAINTAINED. RELATIVELY HOT AND DRY LOW LEVELS WITH AN INVERTED-V PROFILE COUPLED WITH MOIST MID/UPPER LEVELS COULD SUPPORT A FEW STRONG WIND GUSTS WITH ANY MORE INTENSE RAIN CORES. ALSO THE BETTER MOISTURE ALOFT AND RESULTING INCREASING PWATS /FROM 1 TO 1.5 INCHES/ COUPLED WITH RELATIVELY SLOW STEERING FLOW COULD SUPPORT DECENT RAINFALL IN A FEW SPOTS...THOUGH COVERAGE OF CONVECTION MAY BE FAIRLY LIMITED. OTHERWISE...WE WILL SEE ANOTHER MILD NIGHT TONIGHT...SIMILAR TO THIS MORNING. IT WILL BE HOT AGAIN SUNDAY BUT INCREASED CLOUD COVER AND LOWERING THICKNESSES AND HEIGHTS SHOULD KNOCK TEMPERATURES DOWN A TOUCH FROM TODAY FOR MOST SPOTS. LONG TERM... COLD FRONT TO SAG SWD THROUGH THE FCST AREA SUNDAY EXPECTED TO CONTINUE TO FOCUS THUNDER DEVELOPMENT MAINLY ACROSS THE NRN ZONES THROUGH THE EVENING. FOCUS LIKELY TO SHIFT SLIGHTLY TO THE ROLLING PLAINS OVERNIGHT AS UPPER SUPPORT ROTATING AROUND THE SRN ROCKIES RIDGE STAYS JUST TO THE EAST OF THE FCST AREA. PRE-06Z POPS LOOK GOOD AS THEY ARE BUT WILL ADJUST 06Z-12Z POPS WITH 30S EAST AND 20S ELSEWHERE. STILL APPEARS TO BE SOME POTENTIAL FOR SHOWERS AND THUNDER MONDAY AFTN POSSIBLY LINGERING INTO THE EVENING IN UPSLOPE FLOW REGIME TO THE NORTH OF THE FRONT WHICH BY THAT TIME LIKELY TO BE DRAPED ACROSS THE PERMIAN BASIN. THIS SHOULD FOCUS POPS TOWARD THE SWRN THIRD OF THE FCST AREA...ALTHOUGH CONFIDENCE NOT QUITE HIGH ENOUGH TO BUMP INTO CHANCE CATEGORY. REMAINDER OF THE PERIOD LOOKS TO BE DRY WITH TEMPS AT OR JUST ABOVE SEASONAL NORMS. STILL SOME MODEL DIFFERENCES ON HOW THE RIDGE OVER THE SRN ROCKIES EXPANDS WITH RECENT TRENDS SUGGEST EXPANSION MORE NWD RATHER THAN EWD ONTO THE PLAINS. LAST SEVERAL ITERATIONS OF MEDIUM-RANGE MOS GUIDANCE KEEPS KLBB HIGHS IN A RANGE FROM 89-92 DEGREES. CURRENT FCST FOR MID TO LATE WEEK IN GREAT SHAPE WITH FEW CHANGES TO BE MADE. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 64 93 63 87 63 / 10 20 30 20 20 TULIA 67 93 65 87 64 / 0 20 30 20 20 PLAINVIEW 66 94 65 87 64 / 0 20 30 20 20 LEVELLAND 64 97 66 88 66 / 0 10 20 20 20 LUBBOCK 71 97 68 89 66 / 0 10 20 20 20 DENVER CITY 63 95 66 87 64 / 0 10 20 20 20 BROWNFIELD 65 98 68 89 66 / 0 10 20 20 20 CHILDRESS 70 99 69 92 67 / 10 20 30 20 10 SPUR 71 101 70 89 68 / 0 10 20 20 20 ASPERMONT 73 101 71 91 70 / 0 10 20 20 20 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99/05
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
431 AM MDT SUN SEP 1 2013 .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 431 AM MDT SUN SEP 1 2013 SUBTLE CHANGES IN THE RIDGE POSITIONING LEADS TO A WESTWARD SHIFT OF THE DEEP MONSOONAL MOISTURE PLUME...APPEARS FARTHER WEST THAN WHAT EARLIER MODELS MAY HAVE SHOWN. THE END RESULT IS FOR LESS CONVECTIVE POTENTIAL ACROSS THE DESERT VALLEYS (FROM SE UTAH INTO THE GRAND VALLEY) THIS AFTERNOON. OBJECTIVE ANALYSIS PLACES SUBTROPICAL WAVE WITH DEEP MOIST LAYER ACROSS SRN NEVADA/SWRN UTAH/NWRN ARIZONA WITH A VORTICITY LOBE THAT EXTENDS INTO ERN UTAH. RADAR INDICATING SOME SPOTTY SHOWERS ASSOCIATED WITH THIS ERN UTAH VORT LOBE. RAP AND HRRR MODEL SHOWS THIS FEATURE LIFTING NORTH OVER THE BOOKCLIFFS BY LATE MORNING... ENHANCING CONVECTION OVER THE BOOKCLIFFS THAT EXTENDS INTO WRN COLORADO AS FAR EAST AS INDEPENDENCE PASS. RAP/NAM/GFS MODELS SHOW RIDGE AXIS POSITIONED JUST WEST OF THE COLORADO SPINE AND AMPLIFIES AS THE DAY PROGRESSES. DRIER AIR THAT HAS ADVECTED INTO ERN ARIZONA WILL BE DRAWN NORTHWARD INTO SERN UTAH THIS MORNING...REACHING NW COLORADO LATE THIS AFTERNOON. THIS RIBBON OF MID LEVEL DRIER AIR LIMITS CONVECTIVE POTENTIAL ACROSS THE WRN HALF OF OUR FORECAST AREA. WITH WATER VAPOR LOOP CONFIRMING THIS TREND...CANNOT JUSTIFY THE CONTINUATION OF THE FLASH FLOOD WATCH FOR SOUTHEAST UTAH AS DEEP CONVECTIVE TOWERS WILL NOT SURVIVE THE PROMINENT DRY AIR INTRUSION. DIFFERENT ENVIRONMENT OVER THE COLORADO CENTRAL MOUNTAINS WITH MOISTURE IN PLACE WITH SOME SHEAR IN THE 15-20 KT RANGE...CONVECTION THAT FIRES OVER THE BOOKCLIFFS/ROAN PLATEAU AND FLAT TOP MOUNTAINS WILL TRACK ESE ACROSS EAGLE AND PITKIN COUNTY AND THIS AREA GETS THE HIGHEST POP VALUES FOR THIS AFTERNOON. MODELS REMAIN CONSISTENT LEAVING THE SUB TROPICAL HIGH CIRCULATION TO SPIN OVER CENTRAL NEW MEXICO THROUGH THE NEXT 24 TO 36 HOURS. THIS IS WHERE 00Z HAND ANALYSIS HAS IT LOCATED AS WELL...BUT THE ARIZONA WAVE IS NOT QUITE AS DISTINCT AS 24 HOURS AGO AND A BIT FARTHER WEST. PWAT LOOKS TO PEAK THROUGH THE DAY ACROSS THE WESTERN CWA THEN MODELS SHOW A DECLINING TREND THROUGH THE FIRST OF THE WEEK...BUT STILL ABOVE NORMAL. WITH THE ARIZONA WAVE LIFTING A BIT FARTHER WEST...MOISTURE LOOKS TO GET SPLIT APART BY THIS EVENING. SOME LIFTING WITH THE WAVE AND THE REST WRAPPING TOWARD THE CIRCULATION OVER NEW MEXICO...LEAVING A PSEUDO-DRY SLOT FROM THE 4 CORNERS TO THE NORTHERN MOUNTAINS GOING INTO LABOR DAY. WEAK ASCENT ASSOCIATED WITH THE WAVE TO THE WEST PUSHES ACROSS NORTHERN UTAH AND NORTHWEST COLORADO LATE TONIGHT INTO MONDAY MORNING AND MAY HELP FOCUS CONVECTION DURING THE TIME. MOISTURE ALSO POOLS NEAR THE SOUTHERN MOUNTAINS SO THESE TWO AREAS SHOULD HAVE THE BEST CHANCES FOR PRECIPITATION WHILE IN BETWEEN CONFIDENCE IS LOWER. UPPER FLOW NOT IMPRESSIVE BUT STORM MOTION TO THE NORTH SHOULD BE MORE APPARENT THAN THE PAST FEW DAYS AND MAY HELP ALLEVIATE SOME OF THE FLOODING POTENTIAL. LOCALLY HEAVY RAIN STILL POSSIBLE WITH WARM CLOUD RAIN PROCESSES STILL IN PLACE. EXPECT A BIT MORE SUNSHINE ON MONDAY SO PUSHED TEMPS UP A FEW DEGREES MANY AREAS CLOSER TO THE MAV GUIDANCE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 431 AM MDT SUN SEP 1 2013 SHOULD BE A BIT OF DOWNTURN TO THE CONVECTION OVER THE NORTHWEST 2/3 OF THE CWA AS THE UPPER HIGH WOBBLES TO THE NORTHWEST. THIS WILL LEAVE THE 4 CORNERS TO THE CENTRAL MOUNTAINS UNDER THE CIRCULATION WHERE RESIDUAL MOISTURE WILL BE POOLING. THEREFORE REFOCUSED THE HIGH POPS TO OUR SOUTHERN CWA TAPERING OFF TO THE NORTH. HIGH NOT CHANGING MUCH AND SHOULD REMAIN ABOVE NORMAL MOST AREAS. TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BE ANCHORED OVER THE COLORADO ROCKIES. MONSOONAL MOISTURE PLUME WILL BE WEST OF OUR FORECAST AREA. SOME MONSOONAL MOISTURE WILL BE TRAPPED BENEATH THE HIGH CORE TO ALLOW FOR DAILY SHOWERS AND THUNDERSTORMS. WITH SHEAR ESSENTIALLY NON EXISTENT...MOST STORMS WILL STAY PUT OVER THE MOUNTAINS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 431 AM MDT SUN SEP 1 2013 AFTER 18Z...SHOWERS AND THUNDERSTORMS WILL QUICKLY FORM OVER THE MOUNTAIN AREAS...ESPECIALLY TOWARD THE CONTINENTAL DIVIDE WHERE MOUNTAIN PEAKS AND RIDGE TOPS WILL BE OBSCURED FROM RAIN SHAFTS AND LOW CIGS. FARTHER WEST OVER THE LOWER DESERT VALLEYS...AREAL COVERAGE OF -SHRA/-TSRA WILL BE ISOLATED. SHOWERS AND STORMS DIMINISH AFTER 02Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...PF/15 LONG TERM...15/PF AVIATION...PF
AREA FORECAST DISCUSSION
NWS ALBANY NY
739 AM EDT SUN SEP 1 2013 .SYNOPSIS... A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 659 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG IT HAS SHIFTED DOWN STREAM NEAR CAPE COD. SOME DUAL POL QPE VALUES OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE SRN TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND. THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS REMAIN MUGGY FOR THE OPENING DAY OF SEPT. A FEW SHOWERS HAVE POPPED UP OVER SRN DUTCHESS AND LITCHFIELD COUNTIES NEAR THE DIFFUSE BOUNDARY. A MORE ROBUST THUNDERSTORM CLUSTER CONTINUES S/SE OF LITCHFIELD CTY. POPS WERE RETRENDED BASED ON THE RADAR TRENDS. THE MORNING WILL BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST 3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL /1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED CONVECTION. ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS. LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY. PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM 500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO 25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE MONITORED. OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND U60S TO M70S OVER THE HIGH PEAKS. MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES. TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH SOME U40S OVER THE MTNS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD. WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5 DEGREES BELOW NORMAL. TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP. HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW PASSES TO OUR NORTH. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION. MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU AND KALB. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY NIGHT. OUTLOOK... MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO TUESDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT. EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY. LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON SATURDAY AND THIS MORNING. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY. RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3 INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE TO MONITORED FOR ANY HYDRO ISSUES. COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .CLIMATE... THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND PITTSFIELD. THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949. THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS. PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013 AND THE SUMMER. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...IAA/FRUGIS FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
701 AM EDT SUN SEP 1 2013 .SYNOPSIS... A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 659 AM EDT...THE MINI MCS THAT FORMED ALONG THE FRONTAL BOUNDARY AND SOUTH OF THE WEAK WAVE OF LOW PRESSURE MOVING ALONG IT HAS SHIFTED DOWN STREAM NEAR CAPE COD. SOME DUAL POL QPE VALUES OF 1 TO 3 INCHES OCCURRED OVER NW CT...SRN BERKS...AND THE SRN TACONICS OF COLUMBIA AND EXTREME NE DUTCHES COUNTIES. THE KENX RADAR AREA HAS BECOME QUIET WITH SUBSIDENCE IN THE WAKE OF THE MCS. THE WATER VAPOR LOOP INDICATES LOTS OF MID AND UPPER LEVEL DRY AIR HAS MOVED OVER UPSTATE NY AND PORTIONS OF WRN NEW ENGLAND. THIS HAS ALLOWED PATCHY FOG AND SOME STRATUS TO FORM. CONDITIONS REMAIN MUGGY FOR THE OPENING DAY OF SEPT. A FEW SHOWERS HAVE POPPED UP OVER SRN DUTCHESS AND LITCHFIELD COUNTIES NEAR THE DIFFUSE BOUNDARY. A MORE ROBUST THUNDERSTORM CLUSTER CONTINUES S/SE OF LITCHFIELD CTY. POPS WERE RETRENDED BASED ON THE RADAR TRENDS. THE MORNING WILL BEGIN DRY WITH LOTS OF CLOUDS FOR MOST OF THE REGION. WEAK MID AND LOW LEVEL RIDGING WILL PROMOTE A QUIET START OF THE DAY. HOWEVER...THE DIFFUSE FRONTAL BOUNDARY WILL CREEP NORTHWARD FROM THE SRN TIER. POP-UP SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM...AND OTHER SHOWERS AND THUNDERSTORMS MAY INITIATE ALONG THE HIGHER TERRAIN DUE TO THE DIFFERENTIAL HEATING BTWN THE MTNS AND VALLEYS BY THE MID PM. THE COVERAGE AREA SHOULD BE A LITTLE LESS THAN YESTERDAY. THE GENERAL TREND FROM THE LATEST 3-KM HRRR BASE REF PRODUCT IS FOR THE SHOWERS/THUNDERSTORMS TO INCREASE FROM THE CAPITAL REGION SOUTHWARD BTWN 15Z-18Z. SOME OF THE SHOWERS AND THUNDERSTORMS COULD DUMP HVY AMOUNTS OF RAINFALL WITH PWATS STILL RUNNING 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL /1.25-1.75 INCH RANGE/ FOR THE START OF METEOROLOGICAL SUMMER. THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN THE 500-1000 J/KG WITH POCKETS GREATER THAN 1000 J/KG SOUTH OF THE CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED CONVECTION. ENHANCED WORDING WAS CONTINUED FOR HEAVY RAINFALL WITH ANY CONVECTION TODAY. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS. LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY. PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM 500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO 25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE MONITORED. OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND U60S TO M70S OVER THE HIGH PEAKS. MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES. TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH SOME U40S OVER THE MTNS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD. WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5 DEGREES BELOW NORMAL. TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP. HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW PASSES TO OUR NORTH. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION. MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU AND KALB. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY NIGHT. OUTLOOK... MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO TUESDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT. EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY. LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON SATURDAY AND THIS MORNING. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY. RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3 INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE TO MONITORED FOR ANY HYDRO ISSUES. COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .CLIMATE... THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND PITTSFIELD. THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949. THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS. PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013 AND THE SUMMER. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...IAA FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1108 AM EDT Sun Sep 1 2013 .NEAR TERM [Through Today]... Despite most of the Global Models indicating that today would be a Type 4 Sea Breeze Day (Light to Moderate SW winds (5 to 10 kts) between 1000 and 700 mb, this morning`s TAE sounding is more indicative of a Type 5. (same direction as a 4 but with stronger winds (10 to 15 kts). In fact, this is showing up quite well in this morning`s Radar imagery, as the sea breeze circulation has become convectively active and penetrated inland much earlier than at this time on Saturday. Therefore, raised the 12 UTC to 18 UTC PoPs across N FL into the 30-40 percent range, and for this afternoon, raised them to about 50 percent across the board except along the immediate coast and the SE Big Bend. This is also shown quite well in the Hi-Res HRRR model, which has been performing exceptionally well this morning. && .SHORT TERM [Tonight Through Tuesday]... Tonight, the large scale longwave pattern commences rather amplified highlighted by ridge over Wrn half of Conus, digging trough over Ern states and high in Atlc off Cntrl FL with ridge Wwd into Cntrl Gulf of Mex. This keeps local area in relative weakness between these systems. At surface, high well east of N FL with axis WSW across Cntrl FL. A cold front was noted from low Srn Ontario SSW thru OH Valley, Missouri the Nwwd thru KS. Throughout the short term period NAM and ECMWF slower bringing cold front into our area than GFS hence keeping more of our area in warm sector and with noticeably higher POPs and will lean in that direction. Will go 20-30% S-N mainly eve rain. Lows from around 70 SE counties to low 70s elsewhere. On Mon, the upper level trough will continue to dig down the ERN third of the CONUS reaching N FL with increasing storm motion from the WSW. By evening, trough also begin to shift Ewd. This will allow cold front to push into TN by 12z Mon then into N GA during the day and combined with position of Nrn gulf ridge yields light onshore flow over local area. These features combined with daytime heating and the Gulf sea breeze will help to generate SCT convection. Type 6 (SW near 10 mph) sea breeze favors FL but will be disturbed somewhat by approaching cold front which favor Nrn counties. GFS model PWATS increase at TLH from 1.8 inches at 12z Mon to 2inches at 00z Tues. Dothan increases from 1.7 to 1.9 inches same time. Will go 30-50% S-N POPs. Aftn CAPE impressive but shear negligible. Generally light steering flow so any cell mergers could yield locally heavy rain, gusty winds and frequent lightning. Inland highs in low 90s. By Tues, a series of shortwaves move thru trough further deepening and shifting it further Ewd with axis along Ern seaboard by sundown and into Wrn Atlc at night. By sundown, surface low ejects Newd to Canadian Maritimes with trailing front SSW down Wrn Atlc and across local region. Some model disagreement with ECMWF bringing front to Srn most GA/AL while GFS pushes it into N FL with more dry air filtering in behind over GA/AL. At 18Z Tues GFS PWATS remain around 2 inches along and south of front, but reflect modestly drier air building in behind front. For example Dothan PWATS drop to 1.78 at 18z Tues. Conversely, ECMWF PWATS remain around 2 inches at Dothan. Believe GFS too fast with front so will go 30-50% S-N POPS with POPs highest where NAM/ECMWF place front. Drier air seen between H8 and H4 may favor downdrafts and gusty winds altho with shear remaining weak, severe wx not expected. Inland highs 90 to 92 degrees. && .LONG TERM [Tuesday Night through Saturday]... The upper level ridge centered well to our west may briefly build into our region by mid week. Otherwise, upper level troughing will remain the dominate weather feature through the period. A cold front is expected to push into our CWA Wednesday and possibly stall on Thursday. Some drier air may filter into the northern zones by Thursday and Friday. Expect to see typical summertime diurnal convection largely driven by the sea breeze. Temperatures will stay near or just above seasonal normals. && .AVIATION...[Through 12z Monday]. While VFR conditions prevail at the 06z TAF issuance, this is anticipated to be short-lived. Expect LIFR conditions to develop by sunrise at DHN/ABY with the potential for at least MVFR conditions elsewhere. One complicating factor to this is remaining mid level cloudiness across North Florida and offshore convection. TLH/ECP does have a shot at some early morning storms, though confidence is too low to include in TAFs at this time. VSBY/CIG restrictions should end by 14z. Afternoon/evening convection is expected to be more scattered with VCTS groups indicated at all sites. Storm development would be later at ABY/DHN. && .MARINE... Outside of any thunderstorms, and with a weak pressure gradient in place, very light winds and minimal seas are expected over the coastal waters through most of the upcoming week. && .FIRE WEATHER... No concerns. && .HYDROLOGY... The Middle Suwannee River points from Ellaville through Luraville will crest over the next 24 hours below action stage as the Withlacoochee has already crested through the confluence with the Suwannee. The Alapaha has crested at Jennings and will soon be cresting near its confluence with the Suwannee near Nobles Ferry. Modest rises from Branford on through the lower portion of the Suwannee will continue throughout the weekend and through the latter part of this coming week from Wilcox on down to the Gulf of Mexico Entrance. These rises will bring the river points from Wilcox through Fowler`s Bluff to at least action stage this week. Wilcox at US19 has the best chance of reaching flood stage late in the week with a lesser chance further downriver at Fowler`s Bluff. Outside of the Suwannee River Basin, all remaining rivers in the forecast area remain in recession. The Aucilla River will continue to fall slowly and likely be below flood stage by mid week. Releases from Woodruff will continue to lead to a fall in river levels at Blountstown with the Apalachicola likely below action stage by the weekend if the current release schedule holds. For more information, check out the rivers and lakes tab on our homepage. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 92 73 92 72 91 / 50 20 40 30 40 Panama City 89 75 86 75 87 / 40 20 30 20 30 Dothan 92 73 91 72 91 / 50 20 50 30 50 Albany 93 73 91 73 91 / 50 30 50 40 50 Valdosta 95 71 92 73 92 / 50 20 40 30 50 Cross City 90 72 90 72 90 / 40 20 30 20 30 Apalachicola 88 75 87 76 87 / 40 20 30 20 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Gould SHORT TERM...Block LONG TERM...Barry AVIATION...Barry/Gould MARINE...Block/Gould FIRE WEATHER...Godsey HYDROLOGY...Godsey
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
950 AM EDT SUN SEP 1 2013 .UPDATE... NO CHANGES TO THE ONGOING FORECAST THIS MORNING. MORE UNIFORM SOUTHWEST FLOW IS IN PLACE AS SEEN IN AREA SOUNDINGS. SHOWER AND THUNDERSTORM COVERAGE IS LESS THAN THIS TIME YESTERDAY MORNING...BUT STILL SEEING SOME ACTIVITY NEAR BEACHES IN SARASOTA AND MANATEE COUNTIES. OUR LOCAL WRF DOES NOT SHOW MUCH ACTIVITY THIS AFTERNOON AND THE HRRR SHOWS SLIGHTLY MORE WITH THE BEST CHANCES INLAND DUE TO THE SOUTHWEST FLOW. SCATTERED POPS SEEM FINE AT THIS POINT SO WILL LEAVE THE FORECAST AS IS. STRONG WIND GUSTS WILL BE A POSSIBILITY WITH SOME OF THE THUNDERSTORMS TODAY...ESPECIALLY WITH A MID-LEVEL DRY LAYER IN PLACE AS SEEN VIA THE MORNING SOUNDING. && .AVIATION... MAINLY VFR CONDITIONS WITH ISOLD-SCT SHRA/TSRA EXPECTED TO CONTINUE AND DEV ON SEA BREEZE BOUNDARIES WITH BRIEF MVFR CIGS/VSBY AND GUSTY WINDS POSSIBLE NR TAF SITES UNTIL AROUND 00Z. && .PRELIMINARY POINT TEMPS/POPS... TPA 90 76 90 77 / 30 20 30 20 FMY 91 76 91 76 / 30 20 30 20 GIF 92 75 93 76 / 40 20 40 20 SRQ 89 76 89 75 / 30 20 30 20 BKV 92 69 92 70 / 30 20 30 20 SPG 90 79 90 78 / 30 20 30 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE...05/CARLISLE AVIATION...25/DAVIS
AREA FORECAST DISCUSSION
NWS MIAMI FL
905 AM EDT SUN SEP 1 2013 ...FEW STRONG TSTORMS POSSIBLE THIS AFTERNOON WITH FREQUENT LIGHTNING AND STRONG WIND GUSTS THE MAIN THREATS... .UPDATE...THE MIAMI SOUNDING THIS MORNING SHOWS SLIGHT DRYING IN THE LOWER LEVELS BUT STILL SUFFICIENTLY MOIST FOR CONVECTION. GPS MET PWAT DATA SHOWS HIGHER PWATS OF 1.8 TO 2.0 INCHES FROM NAPLES TO THE LAKE OKEECHOBEE REGION. SW LOW LEVEL FLOW CONTINUES. HRRR SHOWS INITIAL CONVECTIVE DEVELOPMENT ACROSS THE EAST COAST METRO AREAS JUST INLAND FROM THE COAST, THEN BECOMING CONCENTRATED OVER THE EVERGLADES WHICH SEEMS REASONABLE GIVEN THE FLOW SET UP TODAY. THEREFORE, HAVE SIDED WITH THIS OUTPUT. INCREASED POPS TO LIKELY TO INCLUDE ALL OF THE INTERIOR, EVEN THOUGH HRRR ISN`T AS BULLISH ACROSS THE LAKE REGION. HOWEVER, DID NOT SEE A REASON TO GO LOWER POPS THERE. EXPANDED CHANCE POPS TO THE GULF COAST AND INTO THE EAST COAST METRO AREAS WITH SLIGHT CHANCE ONLY ALONG THE IMMEDIATE ATLANTIC COAST. A FEW STRONG STORMS ARE POSSIBLE AGAIN THIS AFTERNOON. LAPSE RATES ARE STEEPER THAN YESTERDAY AND THERE IS SOME DRY AIR ALOFT, SO THE WIND GUST POTENTIAL IS THERE. WE HAD A FEW CELLS YESTERDAY PRODUCING DOWNBURST WINDS ESTIMATED AT 50 MPH. THIS AFTERNOON WE COULD HAVE A FEW CELLS APPROACHING SEVERE LIMITS AND WILL HIGHLIGHT STRONG GUSTS TO 55 MPH POSSIBLE. ISOLATED STREET FLOODING IS POSSIBLE AS WELL WHERE STORMS TRAIN. /GREGORIA && .PREV DISCUSSION... /ISSUED 647 AM EDT SUN SEP 1 2013/ AVIATION... HIGH PRESSURE IS BEGINNING TO BUILD IN FROM THE EAST. THIS HAS CAUSED THE UPPER LEVEL LOW THAT HAS BEEN OVER SOUTH FLORIDA TO DISSIPATE. THERE ARE SOME ISOLATED SHOWERS AND THUNDERSTORMS MOVING NORTHWARD, ACROSS CENTRAL FLORIDA. THIS IS LIKELY FROM OUTFLOW BOUNDARIES ASSOCIATED WITH YESTERDAYS CONVECTION OVER CUBA. THIS IS EXPECTED TO DIMINISH BY MID MORNING. FOR THE REST OF THE DAY, THERE IS STILL A SOUTHERLY FLOW OVER THE AREA. THIS WILL BE INFLUENCED BY THE SEA AND GULF BREEZES EARLY THIS AFTERNOON. WHEN THE BREEZES DO INITIATE, THEY WILL CAUSE CONVECTIVE SHOWERS AND SOME THUNDERSTORMS TO DEVELOP AND MOVE BOTH INLAND AND NORTH. THE FOCUS FOR DEVELOPMENT IS EXPECTED TO SHIFT TO THE LAKE OKEECHOBEE REGION LATER THIS AFTERNOON. IN THE MEANTIME, THERE IS UNCERTAINTY AS TO WHERE AND WHEN SHOWERS WILL CONVERT TO THUNDERSTORMS, SO ONLY VCSH IN THE TAFS AT THIS TIME. AS MODELS AND OBSERVATIONS MAKE THE PICTURE MORE CLEAR, VCTS MAY NEED TO BE ADDED TO ANY OR EVEN ALL THE TAF SITES LATER THIS MORNING. PREV DISCUSSION... /ISSUED 304 AM EDT SUN SEP 1 2013/ SHORT TERM... THE OUTFLOW BOUNDARY FROM YESTERDAYS AFTERNOON CONVECTION OVER CUBA HAS WORKED INTO FLORIDA BAY AND GULF WATERS OF SOUTH FLORIDA EARLY THIS MORNING. THIS OUTFLOW HAS ALLOWED FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP OVER THE GULF WATERS OF SOUTH FLORIDA EXTENDING EAST INTO THE FLORIDA BAY AND NORTHERN FLORIDA KEYS. THE SHOWERS AND THUNDERSTORMS WILL DISSIPATE TOWARDS SUNRISE AS THE OUTFLOW BOUNDARY DISSIPATES...BUT COULD WORK INTO THE WESTERN AND SOUTHERN COASTAL AREAS OF SOUTH FLORIDA. SO HAVE PUT IN A 20 PERCENT POPS FOR THESE AREAS THROUGH THE EARLY MORNING HOURS. THE UPPER LEVEL LOW THAT HAS BEEN HANGING AROUND SOUTH FLORIDA FOR THE LAST SEVERAL DAYS WILL SLOWLY MOVE WEST INTO THE GULF WATERS OF MEXICO TODAY. THIS WILL ALLOW FOR THE WESTERN ATLANTIC RIDGE TO BUILD INTO SOUTH FLORIDA...AND ALLOW FOR BOTH THE EAST AND WEST COAST SEA BREEZES TO DEVELOP AND PUSH INLAND ACROSS THE AREA. THE STEERING FLOW WILL ALSO BE LIGHT FROM THE SOUTH OVER SOUTH FLORIDA TODAY. SO ISOLATED TO SCATTERED POPS WILL ONCE AGAIN COVER SOUTH FLORIDA TODAY WITH THE HIGHEST POPS AROUND LAKE OKEECHOBEE. THE HIGH WILL REMAIN IN PLACE OVER SOUTH FLORIDA ON LABOR DAY WHICH WILL KEEP A LIGHT SOUTHERLY WIND FLOW OVER SOUTH FLORIDA...AND ALLOW FOR BOTH THE EAST AND WEST COAST SEA BREEZES TO DEVELOP AND PUSH INLAND. SO THE POPS FOR LABOR DAY WILL ONCE AGAIN BE IN THE ISOLATED TO SCATTERED RANGE WITH THE HIGHEST POPS OVER THE LAKE OKEECHOBEE REGION. THE HIGH WILL THEN MOVE NORTH INTO CENTRAL FLORIDA FOR THE MIDDLE OF THIS WEEK. THIS WILL ALLOW FOR THE STEERING FLOW TO BECOME MORE EASTERLY OVER SOUTH FLORIDA...AND FOCUS THE HIGHEST SCATTERED POPS OVER THE INTERIOR AND WEST COAST METRO AREAS. THE EAST COAST METRO AREAS WILL SEE ISOLATED TO LOW END SCATTERED POPS FOR THE MIDDLE OF THIS WEEK. THE HIGHS FOR LABOR DAY INTO MIDDLE OF THIS WEEK WILL BE IN THE LOWER TO MID 90S...EXCEPT AROUND 90 FOR THE EAST COAST METRO AREAS. THIS WILL ALLOW FOR THE HEAT INDEX READINGS TO BE IN THE 100 TO 105 RANGE OVER MOST OF SOUTH FLORIDA...EXCEPT FOR THE EAST COAST METRO AREAS WHERE THEY WILL BE AROUND 100. LONG TERM... THE HIGH WILL REMAIN OVER CENTRAL FLORIDA FOR END OF THIS WEEK INTO NEXT WEEKEND. THIS WILL KEEP A EASTERLY WIND FLOW OVER SOUTH FLORIDA WHICH IN TURN WILL KEEP THE HIGHEST SCATTERED POPS OVER THE INTERIOR AND WEST COAST METRO AREAS. THERE IS A TROPICAL WAVE LOCATED JUST EAST OF THE LESSER ANTILLES THAT WILL MOVE WEST NORTHWEST THROUGH THE WEEK...AND PASS SOUTH OF THE AREA BY LATE THIS WEEK INTO EARLY NEXT WEEKEND. THIS WAVE COULD BRING IN SOME DEEPER TROPICAL MOISTURE TO THE AREA DURING THIS TIME FRAME. SO WILL CONTINUE TO MONITOR THE LATEST MODEL RUNS ON HOW MUCH MOISTURE WORKS INTO THE AREA WITH THE PASSAGE OF THE TROPICAL WAVE TO THE SOUTH...AND TO SEE IF THE POPS NEED TO BE RAISED OVER SOUTH FLORIDA FOR LATE THIS WEEK INTO EARLY NEXT WEEK IN LATER FORECAST. MARINE... THE WINDS WILL BE AROUND 5 KNOTS TODAY INTO LABOR DAY FROM THE SOUTH TO SOUTHEAST DIRECTION. THE WINDS WILL THEN BECOME MORE EASTERLY AND SLOWLY INCREASE TO 10 TO 15 KNOTS BY END OF NEXT WEEK. THIS WILL KEEP THE SEAS AT 2 FEET OR LESS IN BOTH THE ATLANTIC AND GULF WATERS OF SOUTH FLORIDA THROUGH THE WEEK. SO BOATING CONDITIONS WILL REMAIN GOOD OVER ALL OF SOUTH FLORIDA WATERS THROUGH THE WEEK OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 76 90 77 / 30 20 30 20 FORT LAUDERDALE 89 78 90 79 / 20 20 20 20 MIAMI 90 77 91 79 / 40 20 30 20 NAPLES 89 75 90 76 / 50 20 30 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1041 AM EDT SUN SEP 1 2013 .SYNOPSIS... WEAK ATLANTIC HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH MONDAY. A COLD FRONT WILL PUSH THROUGH TUESDAY NIGHT AND WEDNESDAY WITH WEAK CANADIAN HIGH PRESSURE BUILDING IN FROM THE NORTH. THE HIGH WILL SHIFT OFF THE COAST LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATE THIS MORNING...THE LACK OF ANY FOG/STRATUS HAS RESULTED IN CLEAR SKIES ACROSS THE FORECAST AREA. THIS IS ALLOWING TEMPS TO WARM QUITE RAPIDLY AND SOME AREAS ALREADY IN THE MID 80S. A CU FIELD SHOULD START DEVELOPING VERY SOON AND WILL ENCOMPASS THE ENTIRE FORECAST AREA. THE MAIN FORECAST ISSUE FOR TODAY REVOLVES AROUND THE COVERAGE AND INTENSITY OF DIURNAL CONVECTION. THE MODELS ACROSS THE SPECTRUM ARE SENDING MIXED SIGNALS. SOME OF THE HI-RES RUNS SUCH AS THE HRRR SHOW LITTLE MORE THAN ISOLATED WEAK CONVECTION. ON THE OTHER HAND...THE 12Z NAM HAS COME IN WITH AN UPWARD TREND IN ITS COVERAGE AND INTENSITY. CURRENTLY...THERE IS A WELL DEFINED AREA OF NVA ALOFT NOTED ON WATER VAPOR IMAGERY IN ADVANCE OF THE POTENT SHORTWAVE DRIVING ONGOING CONVECTION OVER THE TENNESSEE VALLEY. THIS NVA WILL LIKELY HANG ON UNTIL LATE IN THE AFTERNOON BEFORE THE UPSTREAM ENERGY DISRUPTS IT. ANOTHER INTERESTING NOTE CONCERNS THE THERMODYNAMIC PARAMETERS FROM THE MODIFIED 12Z RAOB. USING A TEMP/DP OF SOMETHING AROUND 92/73 RESULTS IN CAPE VALUES AROUND 3000 J/KG...WITH DCAPES GREATER THAN 1000 J/KG THANKS TO A GOOD DEAL OF DRY MID LEVEL AIR. THE MAIN SOURCE OF LOW LEVEL CONVERGENCE WILL BE THE SEA BREEZE...THE BEST CONSENSUS SEEMS TO FAVOR ISOLATED TO SCATTERED COVERAGE IN THE MID/LATE AFTERNOON HOURS. GIVEN THE NEAR STORM ENVIRONMENT...THIS SEEMS TO BE A DAY WITH LIMITED COVERAGE BUT THE POTENTIAL FOR A COUPLE STRONG TO SEVERE STORMS DEPENDING ON HOW THE SEA BREEZE AND OUTFLOW BOUNDARIES INTERACT. AS I SAID EARLIER...TEMPS ARE RISING QUICKLY AND WITH INCREASED LOW LEVEL THICKNESSES...HIGHS WILL BE IN THE LOW 90S. SUCH VALUES WILL RUN ABOUT 4-5 DEGREES ABOVE CLIMO FOR EARLY SEPTEMBER. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... TONIGHT...MOST AREAS LIKELY TO SEE DRY WEATHER. THE AREA WHERE SOME ISOLATED NOCTURNAL CONVECTION MAY CROP UP OVERNIGHT COULD BE IN THE SAME AREAS BORDERING THE MIDLANDS AND PEE DEE WHERE A BIT MORE MID LEVEL TROFFINESS IS NOTED. COASTAL AREAS WILL KEEP A SLIGHT SW BREEZE GOING OVERNIGHT AS PATTERN IS FAVORABLE FOR NOCTURNAL JETTING ALONG THE SOUTH CAROLINA COAST. A BROAD UPPER TROUGH WILL SIT OVER THE AREA ON MONDAY WITH SUBSTANTIAL WESTERLY FLOW IN THE LOWER LEVELS. A WELL-DEFINED LEE TROUGH COMBINED WITH MODEST SURFACE BASED CAPE SHOULD ALLOW FOR SCATTERED SHOWERS/TSTMS ACROSS INLAND AREAS BY EARLY AFTERNOON. THE SEABREEZE WILL BE PINNED NEAR THE COAST MUCH OF THE DAY BUT COULD BECOME A PLAYER LATER IN THE AFTERNOON AS IT STARTS TO NUDGE INLAND. WESTERLY STEERING FLOW SHOULD BRING INLAND CONVECTION TOWARD THE COAST AS THE DAY PROGRESSES. OUR BEST COVERAGE LOOKS TO BE LATE AFTERNOON INTO THE EVENING THOUGH A FEW STORMS COULD CONTINUE OVERNIGHT GIVEN SUCH A RICH AIRMASS IN PLACE. THE UPPER TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES ON TUESDAY WITH A COLD FRONT SLOWLY DROPPING SOUTHEAST TOWARD THE AREA. DEWPOINTS RISING INTO THE MIDDLE 70S WITH TEMPS PUSHING INTO THE LOWER 90S WILL YIELD SUBSTANTIAL SURFACE BASED CAPES RANGING FROM 2000 TO 3000 J/KG. ADDITIONALLY SHORTWAVE ENERGY WILL PUSH IN FROM THE WEST DURING THE AFTERNOON. THUS FAIRLY GOOD COVERAGE OF SHOWERS AND TSTMS EXPECTED DURING THE DAY TUESDAY...ESPECIALLY LATER IN THE AFTERNOON ONCE THE CONVECTIVE BOUNDARIES BEGIN INTERACTING WITH THE SEABREEZE. SCATTERED CONVECTION MAY CONTINUE INTO TUESDAY NIGHT BEFORE TAPERING OFF FROM NORTH TO SOUTH. THE FRONT SHOULD PUSH SOUTH OF THE AREA ON WEDNESDAY WITH SLIGHTLY DRIER AND COOLER CONDITIONS IN ITS WAKE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... CANADIAN HIGH PRESSURE WILL PREVAIL FOR THE BEGINNING OF THE PERIOD BUT STEADILY SHIFT EAST WITH A RETURN FLOW SETTING UP ON THE SW PERIPHERY. MOST AREAS WILL BE DRY WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. DIURNAL CONVECTION RETURNS TO THE FORECAST FRIDAY THROUGH SUNDAY AS LOW-LEVEL MOISTURE INCREASES AND ANOTHER UPPER TROUGH SETS UP SHOP. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... STANDARD LATE SUMMER TAF FARE THIS MORNING. ATMOSPHERIC ENVIRONMENT FAVORS ISOLATED/SCATTERED SHOWERS AND TSTMS THIS AFTERNOON IN A MAINLY PULSE-TYPE CONVECTION MODE ANCHORED ON VARIOUS MESOSCALE BOUNDARIES ACROSS THE COASTAL CORRIDOR. BY EARLY EVENING...THE CONVECTION SHOULD DIMINISH WILL MAINLY VFR CONDITIONS CONTINUING TONIGHT. A SW LOW LEVEL JET SHOULD PRECLUDE ANY RISK FOR FOG. EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND TSTMS MONDAY THROUGH TUESDAY NIGHT WITH OCCASIONAL REDUCTIONS IN CEILING AND VISIBILITY. && .MARINE... SW FLOW SURGED A BIT OVERNIGHT...INTO THE 15 KT RANGE AT PLACES SUCH AS FOLLY BEACH AND GRAYS REEF. THIS NOCTURNAL SURGE SHOULD EBB NEARING DAYBREAK WITH FAIRLY LIGHT WINDS AND SEAS 2 TO 3 FT THROUGH MUCH OF THE MORNING AND EARLY AFTERNOON HOURS. A STRONGER NOCTURNAL SURGE IS ANTICIPATED TONIGHT AS THE BOUNDARY LAYER PRES GRADIENT TIGHTENS. THERE MAY BE A SHORT DURATION WHERE WINDS APPROACH SMALL CRAFT ADVISORY CONDITIONS IN FREQUENT GUSTS OVER 20 KT BUT WE HAVE CAPPED OFFSHORE FLOW AT 15 TO 20 KT FOR NOW. SEAS WILL BUILD TO NEAR 4 FT BEYOND 20 NM OFFSHORE. MONDAY THROUGH FRIDAY...WEATHER CONDITIONS WILL REMAIN BELOW ADVISORY CRITERIA. SOUTH TO SOUTHWEST WINDS WILL PERSIST UNTIL TUESDAY AHEAD OF THE COLD FRONT. ONCE THE FRONT PUSHES INTO THE AREA...WINDS WILL BECOME VARIABLE AND LIGHT...WITH SEAS NO HIGHER THAN 2-3 FEET. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...BSH SHORT TERM...JRL LONG TERM...JRL AVIATION... MARINE...JRL
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
954 AM EDT SUN SEP 1 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NVA COVERS THE REGION THIS MORNING WITH NO ACTIVITY IN THE FA SO FAR. AN UPSTREAM SHORT WAVE HAS KICKED OFF SOME SHOWER AND THUNDERSTORM ACTIVITY ACROSS NORTHERN GEORGIA. THE RUC MODEL MOVES THIS FEATURE INTO UPSTATE SOUTH CAROLINA LATER THIS AFTERNOON. EXPECT CONDITIONS TO REMAIN QUIET THROUGH THE MORNING HOURS. THEN AS AFTERNOON LAPSE RATES STEEPEN...MODEL LIS LOWER TO -6...CAPES GET OVER 2000 J/KG AND PWAT VALUES REMAIN HIGH AROUND 1.70 INCHES. SO WILL GO WITH A 30 PERCENT CHANCE NORTH CLOSER TO THE SHORT WAVE AND A 20 PERCENT CHANCE CENTRAL AND SOUTH PARTS. HIGH TEMPERATURES WITH SOME SUNSHINE SHOULD REACH 90 WITH MANY LOCATIONS GETTING TO ABOUT 91. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT VERIFICATION AND EXPECTED CLOUDINESS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY. DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING...BUT MAIN ACTIVITY IS ACROSS EASTERN TN/NRN GA INTO WRN NC. DIURNALLY DRIVEN SCATTERED SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON CONTINUE WELL INTO THE EVENING. EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE AREA. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
822 AM EDT SUN SEP 1 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A MID-LEVEL SHORTWAVE TROUGH WAS HELPING TO SUPPORT ISOLATED SHOWERS IN THE NORTH PART EARLY THIS MORNING. LIFT ASSOCIATED WITH THIS FEATURE WILL LIKELY BE EAST OF THE AREA BY AFTERNOON BUT ANOTHER SHORTWAVE TROUGH MAY MOVE INTO THE AREA LATE THIS AFTERNOON. THE LATEST RAP SHOWED THE LATER TROUGH REACHING THE AREA AROUND 21Z. THE HIGH-RESOLUTION MODELS SUGGESTED SCATTERED COVERAGE AND AN AVERAGE OF THE GFS AND NAM MOS SUPPORTED CHANCE POPS. THE LIMITED COVERAGE APPEARED REASONABLE BECAUSE OF SOMEWHAT SHALLOW MOISTURE AND WEAK LIFT. CLOUDINESS SHOULD HELP HOLD DOWN TEMPERATURES. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT VERIFICATION AND EXPECTED CLOUDINESS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY. DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY. && .AVIATION /12Z SUNDAY THROUGH FRIDAY/... HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING...BUT MAIN ACTIVITY IS ACROSS EASTERN TN/NRN GA INTO WRN NC. DIURNALLY DRIVEN SCATTERED SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON CONTINUE WELL INTO THE EVENING. EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE AREA. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
746 AM EDT SUN SEP 1 2013 .UPDATE... HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS. && .PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/ SHORT TERM /TODAY THROUGH MONDAY/... HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT SHOULD BEGIN TO BURN OFF AFTER SUNRISE. THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/ THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR OUTPUT. MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN. THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED DEVELOP...POPS MAY HAVE TO BE RAISED. FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION... LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS. NLISTEMAA LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO... TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE AREA ON SATURDAY. AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE COOLEST DAY OF THE PERIOD. TDP && .AVIATION... 12Z UPDATE... ENHANCED FOG CHANNEL SHOWS A STRIP OF 300 TO 500 FOOT CIGS FROM CANTON TO WEST OF ATL. THIS AREA IS MOVING EAST. DON`T THINK THE DECK WILL DISSIPATE BEFORE IT REACHES THE AIRPORT...SO WILL INCLUDE A BKN005 DECK FOR TWO HOURS. THE LOW DECK WILL SCT OUT TO A CU DECK AROUND 4500 FT LATE THIS MORNING. CONVECTION HAS BEEN INCREASING ACROSS N GA THIS MORNING. LATEST RUN OF THE HRRR HAS THIS ACTIVITY COMING THROUGH THE AIRPORT AROUND 18Z. MOVED UP THE PRECIP TIMING. //ATL CONFIDENCE...12Z UPDATE... LOW-MEDIUM CONFIDENCE ON LOW STRATUS CIGS THROUGH 15Z. MEDIUM CONFIDENCE ON CONVECTION TIMING TODAY. OTHERWISE...HIGH CONFIDENCE REMANING ELEMENTS. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 90 71 91 72 / 40 40 40 30 ATLANTA 89 72 89 74 / 40 40 40 40 BLAIRSVILLE 83 67 82 68 / 60 50 60 40 CARTERSVILLE 90 71 90 71 / 50 50 40 40 COLUMBUS 92 73 91 74 / 40 30 40 30 GAINESVILLE 88 71 88 73 / 40 50 40 40 MACON 91 72 91 72 / 40 30 40 30 ROME 91 71 92 72 / 60 50 60 40 PEACHTREE CITY 90 70 90 71 / 40 40 40 30 VIDALIA 91 74 91 74 / 40 30 40 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
623 AM EDT SUN SEP 1 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH FLOW INTO THE FORECAST AREA THROUGH MONDAY. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A MID-LEVEL SHORTWAVE TROUGH WAS HELPING TO SUPPORT ISOLATED SHOWERS IN THE NORTH PART EARLY THIS MORNING. LIFT ASSOCIATED WITH THIS FEATURE WILL LIKELY BE EAST OF THE AREA BY AFTERNOON BUT ANOTHER SHORTWAVE TROUGH MAY MOVE INTO THE AREA LATE THIS AFTERNOON. THE LATEST RAP SHOWED THE LATER TROUGH REACHING THE AREA AROUND 21Z. THE HIGH-RESOLUTION MODELS SUGGESTED SCATTERED COVERAGE AND AN AVERAGE OF THE GFS AND NAM MOS SUPPORTED CHANCE POPS. THE LIMITED COVERAGE APPEARED REASONABLE BECAUSE OF SOMEWHAT SHALLOW MOISTURE AND WEAK LIFT. CLOUDINESS SHOULD HELP HOLD DOWN TEMPERATURES. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... THE MODELS HINT AT A WEAK SURFACE TROUGH LINGERING IN THE FORECAST AREA THROUGH MONDAY. THE MODEL TIME SECTIONS INDICATE INCREASING MOISTURE THROUGH THE PERIOD AHEAD OF THE SLOW MOVING COLD FRONT. THERE WILL BE A SERIES OF MID-LEVEL SHORTWAVE TROUGHS THAT WILL DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THE MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS THROUGH TUESDAY. THE GREATEST CHANCE FOR SHOWERS AND THUNDERSTORMS APPEARS TO BE JUST AHEAD OF THE FRONT TUESDAY. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE BASED ON RECENT VERIFICATION AND EXPECTED CLOUDINESS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE GFS AND ECMWF SHOW THE COLD FRONT IN THE FORECAST AREA TUESDAY NIGHT WITH THE FRONT STALLING NEAR THE COAST WEDNESDAY. DEEPER MOISTURE APPEARS TO SHIFT EAST OF THE AREA BY TUESDAY NIGHT AS THE MAIN MID-LEVEL SHORTWAVE TROUGHS MOVES OFF THE COAST. THE MODELS INDICATE AN INVERTED TROUGH SHIFTING INLAND BEGINNING FRIDAY BUT MOISTURE APPEARS LIMITED. THE GFS AND ECMWF MOS INDICATE POPS MAINLY AROUND 20 PERCENT WHICH AGREES WITH THE GFS ENSEMBLE MEANS. EXPECT TEMPERATURES NEAR CLIMATOLOGY. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL CONTINUE TO PROVIDE A MOIST FLOW OVER THE FORECAST AREA TODAY. MVFR/IFR CONDITIONS ACROSS THE AREA THIS MORNING WILL IMPROVE TO VFR BY AROUND 15Z. ISOLATED SHOWERS PERSIST EARLY THIS MORNING BUT ARE NOT EXPECTED TO AFFECT ANY OF THE TAF SITES. DIURNALLY DRIVEN SCATTERED SHOWERS/TSTMS EXPECTED TO DEVELOP LATE THIS AFTERNOON CONTINUE WELL INTO THE EVENING. EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE AREA. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
640 AM CDT SUN SEP 1 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH CENTRAL/SOUTHEAST KS. THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD OF THE FRONT. COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS. JMC .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH. THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME. JMC && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 640 AM CDT SUN SEP 1 2013 SCATTERED SHOWERS/THUNDERSTORMS ARE WEAKENING AT 12Z TAF ISSUANCE. HAVE INCLUDED A BRIEF PERIOD OF -SHRA IN TEMPO GROUPS FOR KRSL AND KSLN...BUT THE OUTLOOK FOR WIDESPREAD RAIN IS NOT GOOD. THE HRRR CONTINUES TO DIMINISH THE PRECIPITATION EXPANSE AS THE FRONT MOVES SOUTHWARD. THUS...IF KHUT/KICT OR KCNU SEES PRECIPITATION AN AMENDMENT WILL BE NEEDED. THE FRONT IS JUST BEHIND THE MAIN CONVECTION/SHOWER LINE. WINDS WILL SWITCH AROUND TO THE NORTH THIS MORNING AND ARE EXPECTED TO STAY FROM THE NORTH SWITCHING FROM NORTHWEST TO NORTHEAST THROUGH THE DAY. MID-HIGH CLOUDS WILL PERSIST UNTIL EVENING AS THE FRONT EXITS TO THE SOUTH. VFR CONDITIONS ARE EXPECTED TO PREVAIL. BILLINGS && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 94 64 88 64 / 30 10 0 0 HUTCHINSON 92 63 87 63 / 40 10 0 0 NEWTON 92 63 86 62 / 40 10 0 0 ELDORADO 94 64 86 62 / 40 10 0 0 WINFIELD-KWLD 97 65 89 64 / 30 10 0 0 RUSSELL 89 59 87 62 / 40 0 0 0 GREAT BEND 90 62 88 62 / 40 0 0 0 SALINA 91 61 87 62 / 30 0 0 0 MCPHERSON 92 62 87 62 / 30 0 0 0 COFFEYVILLE 97 66 88 64 / 30 10 0 0 CHANUTE 94 64 86 63 / 30 10 0 0 IOLA 94 63 86 62 / 30 10 0 0 PARSONS-KPPF 96 65 87 63 / 30 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1107 AM EDT SUN SEP 1 2013 .UPDATE... ISSUED AT 1107 AM EDT SUN SEP 1 2013 PLENTIFUL CLOUD COVER OF VARYING HEIGHTS REMAINS IN THE WAKE OF THE OVERNIGHT AND EARLY MORNING CONVECTION. MOST OF THE SHORT RANGE MODEL DATA SUGGESTS THAT TODAY WILL BE MUCH LESS ACTIVE THIS AFTERNOON COMPARED TO YESTERDAY. AS SUCH...HAVE LOWERED POPS TO LOW CHANCE FOR MOST LOCATIONS AND HAVE ONLY MENTIONED ISOLATED THUNDERSTORM CHANCES FOR THIS AFTERNOON. CLOUDS WILL GRADUALLY THIN WITH TIME...HOWEVER DID NUDGE THE HIGH TEMPERATURES DOWN A TAD WITH THE SLOW START THIS MORNING. CONSEQUENTLY...WENT AHEAD AND TEMPERED THE DIURNAL RISE A BIT MORE AS WELL. UPDATE ISSUED AT 750 AM EDT SUN SEP 1 2013 UPDATED THE POP AND WX GRIDS TO REFLECT THE WANING OF THE SHOWERS AND THUNDERSTORMS ACROSS OUR SOUTH. ALSO FINE TUNED THE NEAR TERM T/TD GRIDS IN LINE WITH THE OBS AND TRENDS. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. A FRESHENED SET OF ZONES WILL FOLLOW. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 440 AM EDT SUN SEP 1 2013 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING INTO THE OHIO VALLEY FROM THE CENTRAL PLAINS. THIS...IN CONJUNCTION WITH AN MCV... CONTINUES TO DEVELOP CONVECTION OVER NORTHWESTERN/CENTRAL KENTUCKY AND DRIFT IT SOUTHEAST INTO THE CUMBERLAND VALLEY. THE RAINS FROM THIS COULD BE EXCESSIVE OVER PARTS OF WAYNE AND PULASKI COUNTIES PROMPTING A CONTINUATION OF THE URBAN AND SMALL STREAM FLOOD ADVISORIES FOR THESE LOCATIONS. IF THE RATES PICK UP IN THE NEXT ROUND OF CONVECTION WE WILL NEED TO CONSIDER FLOOD WARNINGS...BUT SO FAR THESE HAVE BEEN LIGHT ENOUGH TO JUST MAINTAIN THE ADVISORIES. OTHERWISE...MOSTLY CLOUDY SKIES COVER EAST KENTUCKY KEEPING THE FOG PATCHY AND LIGHT FOR MOST OF THE AREA. THIS IS DESPITE ANOTHER NIGHT OF MINIMAL DEW POINT DEPRESSIONS WITH TEMPS AND DEWS HOLDING IN THE UPPER 60S...MUCH OF THIS THE RESULT OF RAIN COOLING EARLIER IN THE NIGHT. THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH THE NORTHWEST FLOW REGIME OVER THE OHIO VALLEY AMPLIFYING IN RESPONSE TO A TROUGH PASSING THROUGH THE NORTHERN GREAT LAKES TODAY THROUGH MONDAY. THIS TROUGH WILL SEND PLENTY OF SHORTWAVE ENERGY INTO OUR AREA DURING THIS TIME WITH THE MESOSCALE DOMINANT FOR SENSIBLE WEATHER. ACCORDINGLY...HAVE USED THE NAM12 TO GUIDE THIS FORECAST IN COORDINATION WITH THE LATEST HRRR AND CURRENT LARGER SCALE RADAR TRENDS. SENSIBLE WEATHER WILL BE A CONTINUATION OF OUR WARM...HUMID...AND STORMY HOLIDAY WEEKEND. CONVECTION IS ANTICIPATED OVER OUR SOUTHERN AND WESTERN ZONES EARLY THIS MORNING GRADUALLY FADING OUT BEFORE ANOTHER ROUND DEVELOPS LATER TODAY. THE STRONGEST STORMS COULD CONTAIN GUSTY TO DAMAGING WINDS IF THEY GET TALL ENOUGH...BOW OR MERGE. A VEERING WIND PROFILE AND SOME MID LEVEL SPEED SHEAR ALSO SUPPORTS THIS CONCERN. OTHERWISE...THE MAIN ISSUE WILL BE EXCESSIVE RAINFALL AND FLOODING POTENTIAL GIVEN THE RAINS THAT HAVE FALLEN AND THE THREAT OF ADDITIONAL CONVECTION TRAINING OVER THE SAME AREAS. CANNOT RULE OUT THE SCATTERED CONVECTION CONTINUING INTO THE NIGHT WITH LOW PRESSURE IN PLACE OVER THE REGION AND THE APPROACH OF ITS COLD FRONT...THOUGH THE NAM12 WOULD SUGGEST A LULL UNTIL LATER MONDAY MORNING. HAVE RAMPED POPS DOWN DURING THIS TIME IN THE GRIDS...BUT NOT AS MUCH AS THE NAM12 INDICATES. FOR MONDAY...THE SYSTEM/S FRONT WILL MAKE A MORE DEFINITIVE PUSH INTO OUR AREA AND LIKELY ACTIVATE THE REMAINING DEEP MOISTURE FOR ONE LAST GOOD ROUND OF CONVECTION DURING THE DAY. TEMPERATURES WILL BE DEPENDENT ON CONVECTION... PARTICULARLY FOR HIGHS TODAY AND TOMORROW...BUT IN GENERAL SHOULD BE ABLE TO REACH THE MID AND UPPER 80S. AGAIN UPPER 60S WILL BE THE RULE FOR LOWS TONIGHT. USED THE CONSSHORT AND ITS BC VERSION FOR THE DEW POINT AND WIND GRIDS...RESPECTIVELY...THROUGH 00Z MONDAY AS A STARTING POINT AND THE CONSALL THEREAFTER. FOR TEMPS...ADJUSTED THE CONSALL FOR SOME MINOR TERRAIN ENHANCEMENTS IN THE LOWS TONIGHT AND PCPN CONSIDERATIONS TODAY AND MONDAY...WITH HOURLY DIURNAL CURVE DERIVED FROM THE NAM12. AS FOR POPS...ENDED UP CLOSER TO THE WETTER MAV GUIDANCE TODAY... SIMILAR TO BOTH TONIGHT...AND THEN NEARER THE MET MONDAY. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 AM EDT SUN SEP 1 2013 A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN. AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIR MASS...WITH WINDS AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY REACH NEAR 80 TUESDAY. THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIR MASS IN PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE 50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER GREAT LAKES SATURDAY. ACCORDING THE ECMWF...WARM AIR PULLING IN AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL SOMEWHAT UNKNOWN. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 800 AM EDT SUN SEP 1 2013 THE LATEST ROUND OF THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH THE CUMBERLAND VALLEY. DO STILL EXPECT SOME ADDITIONAL STORMS TO DEVELOP AND AFFECT THE AREA LATER IN THE DAY BUT HAVE BACKED THESE OFF TO JUST VCTS MENTIONS GIVEN THE LATEST HRRR AND NAM12 MODEL GUIDANCE SHOWING MORE OF A DRY PERIOD IN THE WAKE OF THE MORNING STORMS. THE REDEVELOPMENT WILL LIKEWISE FADE OUT LATER THIS EVENING AND PATCHY MVFR FOG CAN BE ANTICIPATED AFTER 06Z AT MOST SITES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY STORMS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...GREIF LONG TERM...JMW AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
800 AM EDT SUN SEP 1 2013 .UPDATE... ISSUED AT 750 AM EDT SUN SEP 1 2013 UPDATED THE POP AND WX GRIDS TO REFLECT THE WANING OF THE SHOWERS AND THUNDERSTORMS ACROSS OUR SOUTH. ALSO FINE TUNED THE NEAR TERM T/TD GRIDS IN LINE WITH THE OBS AND TRENDS. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. A FRESHENED SET OF ZONES WILL FOLLOW. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 440 AM EDT SUN SEP 1 2013 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING INTO THE OHIO VALLEY FROM THE CENTRAL PLAINS. THIS...IN CONJUNCTION WITH AN MCV... CONTINUES TO DEVELOP CONVECTION OVER NORTHWESTERN/CENTRAL KENTUCKY AND DRIFT IT SOUTHEAST INTO THE CUMBERLAND VALLEY. THE RAINS FROM THIS COULD BE EXCESSIVE OVER PARTS OF WAYNE AND PULASKI COUNTIES PROMPTING A CONTINUATION OF THE URBAN AND SMALL STREAM FLOOD ADVISORIES FOR THESE LOCATIONS. IF THE RATES PICK UP IN THE NEXT ROUND OF CONVECTION WE WILL NEED TO CONSIDER FLOOD WARNINGS...BUT SO FAR THESE HAVE BEEN LIGHT ENOUGH TO JUST MAINTAIN THE ADVISORIES. OTHERWISE...MOSTLY CLOUDY SKIES COVER EAST KENTUCKY KEEPING THE FOG PATCHY AND LIGHT FOR MOST OF THE AREA. THIS IS DESPITE ANOTHER NIGHT OF MINIMAL DEW POINT DEPRESSIONS WITH TEMPS AND DEWS HOLDING IN THE UPPER 60S...MUCH OF THIS THE RESULT OF RAIN COOLING EARLIER IN THE NIGHT. THE MODELS ARE IN GOOD AGREEMENT ALOFT WITH THE NORTHWEST FLOW REGIME OVER THE OHIO VALLEY AMPLIFYING IN RESPONSE TO A TROUGH PASSING THROUGH THE NORTHERN GREAT LAKES TODAY THROUGH MONDAY. THIS TROUGH WILL SEND PLENTY OF SHORTWAVE ENERGY INTO OUR AREA DURING THIS TIME WITH THE MESOSCALE DOMINANT FOR SENSIBLE WEATHER. ACCORDINGLY...HAVE USED THE NAM12 TO GUIDE THIS FORECAST IN COORDINATION WITH THE LATEST HRRR AND CURRENT LARGER SCALE RADAR TRENDS. SENSIBLE WEATHER WILL BE A CONTINUATION OF OUR WARM...HUMID...AND STORMY HOLIDAY WEEKEND. CONVECTION IS ANTICIPATED OVER OUR SOUTHERN AND WESTERN ZONES EARLY THIS MORNING GRADUALLY FADING OUT BEFORE ANOTHER ROUND DEVELOPS LATER TODAY. THE STRONGEST STORMS COULD CONTAIN GUSTY TO DAMAGING WINDS IF THEY GET TALL ENOUGH...BOW OR MERGE. A VEERING WIND PROFILE AND SOME MID LEVEL SPEED SHEAR ALSO SUPPORTS THIS CONCERN. OTHERWISE...THE MAIN ISSUE WILL BE EXCESSIVE RAINFALL AND FLOODING POTENTIAL GIVEN THE RAINS THAT HAVE FALLEN AND THE THREAT OF ADDITIONAL CONVECTION TRAINING OVER THE SAME AREAS. CANNOT RULE OUT THE SCATTERED CONVECTION CONTINUING INTO THE NIGHT WITH LOW PRESSURE IN PLACE OVER THE REGION AND THE APPROACH OF ITS COLD FRONT...THOUGH THE NAM12 WOULD SUGGEST A LULL UNTIL LATER MONDAY MORNING. HAVE RAMPED POPS DOWN DURING THIS TIME IN THE GRIDS...BUT NOT AS MUCH AS THE NAM12 INDICATES. FOR MONDAY...THE SYSTEM/S FRONT WILL MAKE A MORE DEFINITIVE PUSH INTO OUR AREA AND LIKELY ACTIVATE THE REMAINING DEEP MOISTURE FOR ONE LAST GOOD ROUND OF CONVECTION DURING THE DAY. TEMPERATURES WILL BE DEPENDENT ON CONVECTION... PARTICULARLY FOR HIGHS TODAY AND TOMORROW...BUT IN GENERAL SHOULD BE ABLE TO REACH THE MID AND UPPER 80S. AGAIN UPPER 60S WILL BE THE RULE FOR LOWS TONIGHT. USED THE CONSSHORT AND ITS BC VERSION FOR THE DEWPOINT AND WIND GRIDS...RESPECTIVELY...THROUGH 00Z MONDAY AS A STARTING POINT AND THE CONSALL THEREAFTER. FOR TEMPS...ADJUSTED THE CONSALL FOR SOME MINOR TERRAIN ENHANCEMENTS IN THE LOWS TONIGHT AND PCPN CONSIDERATIONS TODAY AND MONDAY...WITH HOURLY DIURNAL CURVE DERIVED FROM THE NAM12. AS FOR POPS...ENDED UP CLOSER TO THE WETTER MAV GUIDANCE TODAY... SIMILAR TO BOTH TONIGHT...AND THEN NEARER THE MET MONDAY. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 AM EDT SUN SEP 1 2013 A STRONG SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES AT THE START OF THE PERIOD WILL PUT THE OHIO RIVER VALLEY IN A TROUGHING PATTERN. AT THE SURFACE...AN ASSOCIATED LOW PRESSURE SYSTEM WILL GENERATE A COLD FRONT WHICH SHOULD JUST BE EXITING EASTERN KY AT THE BEGINNING OF THE PERIOD. THE FROPA WILL PRODUCE SHOWERS AND THUNDERSTORMS IN THE WARM SECTOR...WHICH SHOULD BE PUSHING OUT OF THE REGION BY TUESDAY MORNING. THE SHORTWAVE WILL CONTINUE EASTWARD THROUGHOUT THE DAY TUESDAY...WITH HIGH PRESSURE RIDGING TAKING HOLD ACROSS KY. THIS WILL MEAN THE RETURN OF A MUCH COOLER AND DRIER AIRMASS...WITH WINDS AT THE MID AND UPPER LEVELS OUT OF THE NE. HIGH TEMPS WILL ONLY REACH NEAR 80 TUESDAY. THIS UPPER AIR PATTERN AND SURFACE HIGH PRESSURE WILL PERSIST THROUGH THE REMAINDER OF THE WEEK...WITH ABUNDANT SUNSHINE ALLOWING TEMPS TO RISE SLIGHTLY INTO THE LOWS 80S. WITH A DRY AIRMASS IN PLACE...DIURNAL COOLING WILL ALLOW OVERNIGHT TEMPS TO FALL INTO THE 50S. WHILE MODELS START TO DIVERGE ON UPPER AIR SOLUTIONS BY THE END OF THE PERIOD...THERE IS STILL SOME CONSENSUS OF ANOTHER UPPER LEVEL SHORTWAVE DEVELOPING OVER NE CANADA FRIDAY NIGHT INTO SATURDAY. AT THIS SURFACE THIS WILL TRANSLATE TO A LOW PRESSURE SYSTEM OVER NE CANADA...WITH A COLD FRONT POISED TO DROP SOUTHWARD FROM THE UPPER GREAT LAKES SATURDAY. ACCORDING THE ECWMF...WARM AIR PULLING IN AHEAD OF THIS FRONT...COUPLED WITH DAYTIME HEATING...WILL LEAD TO THE DEVELOPMENT OF SCT CONVECTION. HOWEVER...WILL STICK WITH A MODEL CONSENSUS FOR SATURDAY AND SUNDAY...SINCE THIS FAR OUT THE EXACT COURSE OF THE TROUGHING AND ASSOCIATED COLD FRONT/PRECIP IS STILL SOMEWHAT UNKNOWN. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 800 AM EDT SUN SEP 1 2013 THE LATEST ROUND OF THUNDERSTORMS HAVE TAPERED TO SHOWERS THROUGH THE CUMBERLAND VALLEY. DO STILL EXPECT SOME ADDITIONAL STORMS TO DEVELOP AND AFFECT THE AREA LATER IN THE DAY BUT HAVE BACKED THESE OFF TO JUST VCTS MENTIONS GIVEN THE LATEST HRRR AND NAM12 MODEL GUIDANCE SHOWING MORE OF A DRY PERIOD IN THE WAKE OF THE MORNING STORMS. THE REDEVELOPMENT WILL LIKEWISE FADE OUT LATER THIS EVENING AND PATCHY MVFR FOG CAN BE ANTICIPATED AFTER 06Z AT MOST SITES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE...OUTSIDE OF ANY STORMS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...JMW AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
759 AM EDT SUN SEP 1 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM OVER LAKE SUPERIOR WILL CONTINUE TO DEVELOP AND MOVE EAST INTO NORTHERN QUEBEC THROUGH EARLY THIS WEEK. A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE THROUGH THE MID- ATLANTIC MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE BUILDS IN FROM THE NORTHWEST MID TO LATE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEBRIS CLOUDS LEFT OVER FROM YDA`S CONVECTION HAS LIMITED EXTENT OF FOG FORMATION ERY THIS MRNG. SOME PATCHY FOG WILL STILL DEVELOP THRU DAYBREAK PRIMARILY WITHIN THE SHELTERED VLYS IN CENTRAL VA...WHERE THE GROUND IS WET FROM YDA`S STORMS. HIPRES WILL REMAIN PARKED OVER THE WRN ATLANTIC TDA. WITH PERSISTENT SLY RETURN FLOW OVER THE ERN SEABOARD...THE AIRMASS WILL BE SIMILAR TO YDA...WARM AND HUMID /DESPITE THE CALENDAR CHANGING FROM METEOROLOGICAL SUMMER TO FALL/. MAX TEMPS ARE FCST IN MID TO UPPER 80S ALONG AND WEST OF THE BLUE RIDGE AND UPPER 80S TO LOWER 90S FARTHER EAST. ONE MID-LVL SHORTWAVE TROUGH EXITS THE MID-ATLANTIC REGION ERY THIS MRNG AS ANOTHER ONE APPROACHES FROM THE OH VLY. THE REMNANTS OF THIS UPSTREAM MCS WILL PROGRESS EWD THRU THE NRN MID-ATLANTIC STATES THIS AFTN/EVE. THE CWA WILL HAVE FILTERED SUNSHINE BEFOREHAND...PROVIDING AN OPPORTUNITY FOR THE ATMOSPHERE TO DESTABILIZE. SIMILAR TO YDA...SCT SHOWERS AND STORMS SHOULD DEVELOP OVER THE MTS THIS AFTN AS MODEST LIFT FROM THE SHORTWAVE TROUGH REACHES THE WRN CWA. WITH THE MID-LVL SUBSIDENCE INVERSION WEAKER THAN YDA...DEEPER CONVECTION WILL HAVE A BETTER CHANCE TO MAKE IT EAST OF THE MTS. THE BEST CHANCE FOR SHOWERS AND STORMS APPEAR TO BE LATE THIS AFTN AND EVE WHEN THE SHORTWAVE TROUGH MOVES THRU. LIMITED POPS TO CHANCE ACROSS THE ENTIRE CWA THOUGH AS CONVECTION MAY HAVE DIFFICULTY ORGANIZING DUE TO WEAK SHEAR PROFILES AND LIFT FROM THE TROUGH. FCST PARAMETERS FROM THE LATEST RAP INDICATE ABOUT 1500-2000 J/KG OF SBCAPE THIS AFTN. CANNOT RULE OUT A COUPLE OF PULSE SEVERE STORMS ESPECIALLY IN THE MTS GIVEN THE THERMODYNAMIC PROFILES. ONGOING CONVECTION WILL DIMINISH LATE THIS EVE WITH THE LOSS OF HEATING AND AS THE SHORTWAVE TROUGH LIFTS NEWD TNGT. DRY SLOT MOVES IN FROM THE WEST TNGT WHILE THE LLVL FLOW VEERS OUT OF THE WEST. THIS COULD ALLOW FOR BREAKS IN THE CLOUD COVER AND FOR FOG TO DEVELOP LATE TNGT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... LABOR DAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN APPROACHING COLD FRONT FROM THE WEST. A PREFRONTAL TROUGH WILL DEVELOP IN THE LEE OF THE APPALACHIANS WHICH SHOULD PROVIDE A FOCUS FOR ISOLATED/SCATTERED AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT. IT WILL BE A HOT DAY WITH MAX TEMPS IN THE LOW 90S. NAM AND GFS HAVE SBCAPE AROUND 2500 J/KG WITH BULK SHEAR UNDER 30 KT. MONDAY NIGHT...LINES OF CONVECTION SHOULD DEVELOP AHEAD OF THE FRONT AND PUSH EAST THROUGH THE AREA MONDAY EVENING/THROUGH MIDNIGHT. INCREASED LIKELY POP COVERAGE TO ACROSS THE BALT-WASH METRO FOR THE EVENING HOURS. THIS IS JUST ABOVE MOST GUIDANCE WHICH IS AROUND 50 POP. WITH AMPLE AVAILABLE ENERGY AND A STRAIGHT-LINE HODOGRAPH... EXPECT ORGANIZED ACTIVITY. SEVERE THREAT OF LARGE HAIL AND DAMAGING WIND. SPEAKING OF HAIL...THERE HAVE ONLY BEEN FOUR 1 INCH HAIL REPORTS SINCE JULY 4. WITH TALL AND FAT CAPE DEPICTED BY THE NAM/GFS SOUNDINGS...THIS HAIL DEARTH MAY END SOON. FRONT DRIFTS EAST THROUGH THE NIGHT...MIN TEMPS AROUND 60F IN THE ALLEGHENY HIGHLANDS...CLOSER TO 70F EAST OF THE BLUE RIDGE PER MAV/MET/SREF BLEND. TUESDAY...FRONT IS SLOW TO CLEAR THE AREA...MAY STALL OVER SRN MD CONTINUING A THUNDERSTORM THREAT DOWN THERE. OTW...NRN CONUS (NOT QUITE CANADIAN...AND THUS NOT AS COOL) HIGH PRESSURE BUILDS IN FROM THE NW...WITH SUNNY CONDITIONS ON TAP IN WRN PARTS OF THE CWA. MAX TEMPS GENERALLY 80S AT LOW ELEVATIONS...MID 80S I-95 AND EAST. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... DRY CONDITIONS AS HIGH PRESSURE DOMINATES THROUGH FRIDAY. WEAK SFC TROUGH DROPS SOUTH INTO THE CWA WEDNESDAY NIGHT...PUSHING SOUTH THURSDAY. PROBABLY JUST SOME MID LEVEL CLOUDS ASSOCIATED WITH THIS DISTURBANCE. MAX TEMPS CLOSE TO NORMAL...LOW 80S WED-FRI. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... LGT SLY WINDS AND MID TO HI CLOUDS HAVE LIMITED THE COVERAGE OF FOG ERY THIS MRNG. AS OF 0730Z...ALL TERMINALS ARE VFR. CHO HAS THE BEST OPPORTUNITY FOR A BRIEF PERIOD OF FOG TOWARD SUNRISE AS THE SOIL IS SATURATED FROM YDA`S STORMS. VFR CONDITIONS FOR MUCH OF TDA. SCT SHOWERS AND STORMS ARE EXPECTED TO INITIALLY DEVELOP OVER THE MTS THIS AFTN AND MOVE EWD TOWARD THE TERMINALS APPROX BETWEEN 20Z-01Z. TEMPORARY FLGT RESTRICTIONS POSSIBLE WITH THESE STORMS. PATCHY FOG POSSIBLE AGAIN LATE TNGT...ESPECIALLY AT THE FOG-PRONE LOCATIONS AT CHO AND MRB. THUNDERSTORMS INCREASE MONDAY AFTERNOON/CONTINUE THROUGH THE NIGHT AS A COLD FRONT DRIFTS EAST ACROSS THE TERMINALS. SLY FLOW AROUND 10 KT...THOUGH DAMAGING WINDS ARE POSSIBLE IN THUNDERSTORMS. HIGH PRESSURE THEN BUILDS TUESDAY AND DOMINATES REST OF THE WORK WEEK WITH VFR CONDS OUTSIDE OF MORNING FOG. && .MARINE... SLY WINDS BETWEEN 10-15 KT WILL CONTINUE TDA AND TNGT. SCT STORMS EXPECTED LATE IN THE DAY. LOCALLY STRONG WINDS WITH THESE STORMS COULD BECOME HAZARDOUS TO MARINERS AND HOLIDAY BOATERS. 10-15 KT SLY FLOW AHEAD OF A COLD FRONT ACROSS THE WATERS MONDAY. SPECIAL MARINE WARNINGS POSSIBLE FROM THUNDERSTORMS LATE MONDAY AFTERNOON THROUGH THE NIGHT. FLOW BECOMES NWLY BY TUESDAY EVENING...SOME CHANNELING GUSTS MAY APPROACH 18 KT. VARIABLE FLOW AND HIGH PRESSURE WEDNESDAY THROUGH FRIDAY. && .CLIMATE... FOR WASHINGTON DC (DCA)... ALTHOUGH THE AVG TEMP OF 78.3F FOR THE 2013 METEOROLOGICAL SUMMER WAS SLIGHTLY ABOVE THE 1981-2010 NORMAL...IT WAS CONSIDERABLY COOLER THAN THE PREVIOUS THREE SUMMERS (WHICH WERE THE THREE WARMEST SUMMERS ON RECORD FOR DC). BASED ON AVG TEMPS...THIS SUMMER RANKS AS THE 25TH WARMEST SUMMER ON RECORD (TIED WITH 1959). AUGUST 2013 WAS THE FIRST SUMMER MONTH THAT WAS BELOW NORMAL SINCE JULY 2009. MIN TEMPS WERE PARTICULARLY WARM. THE MIN TEMP FOR THE SUMMER AVERAGED 70.8F...WHICH WAS THE TIED WITH 1980 FOR THE 4TH WARMEST ON RECORD. THE ONLY THREE SUMMER THAT HAD A HIGHER MIN TEMP WAS 2010...2011 AND 2012. THE MIN TEMPERATURE WAS NEVER LOWER THAN 80F IN DC FOR FIVE STRAIGHT DAYS FROM 16-20 JULY...THE FIRST TIME THIS HAD HAPPENED ON RECORD. THE MOST NUMBER OF DAYS IN A ROW ABOVE 80F WAS PREVIOUSLY FOUR (21-24 JULY 2011). A MAX TEMP OF 90F OR WARMER WAS RECORDED 23 DAYS THIS SUMMER. LOOKING AT THE TEMP RECORDS SINCE 1871...THE AVERAGE NUMBER OF 90-DEGREE DAYS IN A SUMMER IS 26 FOR DC. THE NUMBER OF 90-DEGREE DAYS IN THE PREVIOUS THREE SUMMERS WAS 52 IN 2010...47 IN 2011 AND 48 IN 2012. THIS SUMMER FEATURED FIVE DAYS WITH A MAX TEMP OF 95F OR WARMER. THE AVG NUMBER OF 95-DEGREE DAYS IN A SUMMER IS 6 FOR DC. A RECORD 28 95-DEGREE DAYS OCCURRED IN THE SUMMER OF 2012 WHILE 22 SUCH DAYS WERE OBSERVED EACH IN 2010 AND 2011. RAINFALL THIS SUMMER MEASURED 15.74 INCHES...WHICH IS EQUIVALENT TO 50 PERCENT ABOVE THE NORMAL SUMMER RAINFALL FOR DC. IT WAS THE WETTEST SUMMER SINCE 2006 WHEN 18.61 INCHES WAS RECORDED. THE MAJORITY (TWO-THIRDS) OF THE RAINFALL THIS SUMMER OCCURRED IN JUNE. JUNE 2013 WAS THE 4TH WETTEST JUNE ON RECORD. FOR BALTIMORE (BWI)... THE AVG TEMP OF 75.8F FOR THE 2013 METEOROLOGICAL SUMMER WAS SLIGHTLY ABOVE THE 1981-2010 NORMAL BUT IT WAS CONSIDERABLY COOLER THAN THE PREVIOUS THREE SUMMERS (WHICH WERE ALL IN THE TOP TEN WARMEST SUMMERS ON RECORD). AUGUST 2013 WAS THE FIRST SUMMER MONTH THAT WAS BELOW NORMAL SINCE JULY 2009. A MAX TEMP OF 90F OR WARMER WAS RECORDED 19 DAYS THIS SUMMER. LOOKING AT THE TEMP RECORDS SINCE 1872...THE AVERAGE NUMBER OF 90-DEGREE DAYS IN A SUMMER IS 23 FOR BALTIMORE. THE NUMBER OF 90-DEGREE DAYS DURING THE PREVIOUS THREE SUMMERS WAS 47 IN 2010...37 IN 2011 AND 40 IN 2012. THIS SUMMER FEATURED ONLY FIVE DAYS WITH MAX TEMP OF 95F OR WARMER. THE AVG NUMBER OF 95-DEGREE DAYS IN A SUMMER IS 6 FOR BALTIMORE. THE NUMBER OF 90-DEGREE DAYS DURING THE PREVIOUS THREE SUMMERS WAS 19 IN 2010...16 IN 2011 AND 20 IN 2012. RAINFALL THIS SUMMER MEASURED 12.16 INCHES...WHICH IS SLIGHTLY WETTER THAN NORMAL. THE MAJORITY (TWO-THIRDS) OF THE RAINFALL THIS SUMMER OCCURRED IN JUNE. JUNE 2013 WAS THE 7TH WETTEST JUNE ON RECORD FOR BALTIMORE. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BAJ NEAR TERM...JRK SHORT TERM...BAJ LONG TERM...BAJ AVIATION...BAJ/JRK MARINE...BAJ/JRK CLIMATE...JRK
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1032 AM EDT SUN SEP 1 2013 .SYNOPSIS... ISSUED AT 352 AM EDT SUN SEP 1 2013 A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED FOR THE REMAINDER OF THE WEEK. && .UPDATE... ISSUED AT 1032 AM EDT SUN SEP 1 2013 OVERVIEW: COMPACT SHORT WAVE NOW ADVANCING THROUGH THE WESTERN U.P./WESTERN LAKE SUPERIOR. ATTENDING SFC LOW LOCATED OVER THE KEWEENAW PENINSULA AS OF 14Z WITH A COLD FRONT STRETCHING DOWN THROUGH CENTRAL WISCONSIN. AHEAD OF THE FRONT...12Z GRB/APX SOUNDINGS REVEAL A FAIRLY DRY LOWER LEVEL AIRMASS IN PLACE AND SFC BASED CAP UP THROUGH AROUND 800 MB OR SO. BUT...THERE IS A THIN RIBBON OF MODEST LOW LEVEL MOISTURE (850 THETA-E RIDGE) JUST ALONG THE FRONT IN CENTRAL WISCONSIN... WRAPPING INTO THE LOW OVER LAKE SUPERIOR. COUPLED WITH COOLING LOWER LEVELS WITH THE SFC FRONT AND UPPER WAVE...HAS PRODUCED A NARROW CORRIDOR OF INSTABILITY THAT IS ADVANCING EASTWARD... EVIDENCED BY THE BKN LINE OF CONVECTION THAT WRAPS ALONG THE LEADING EDGE OF THE SHORT WAVE. FORECAST FOR THIS AFTERNOON/EVENING IS COMPLICATED BY A NUMBER OF FACTORS...INCLUDING...BUT NOT LIMITED TO...MORNING STRATUS AND FOG THAT WILL MOST CERTAINLY INHIBIT HEATING AND INSTABILITY AT LEAST FOR AWHILE...AS WELL AS SMALLER SCALE AFFECTS ON THE LOW LEVEL WIND FIELD INDUCED BY THE LAKES THAT WILL IMPACT FRONTAL POSITION AND ULTIMATELY LOW LEVEL CONVERGENCE. THROUGH EARLY AFTERNOON...ONGOING CONVECTION UPSTREAM SHOULD BASICALLY HIT A "CINH" WALL AS IT TRIES TO ADVANCE INTO THIS CWA...ESSENTIALLY OUTRUNNING THE FORCING AND AFOREMENTIONED NARROW CORRIDOR OF INSTABILITY. SO...EXPECT MUCH OF THE CURRENT ACTIVITY TO FIZZLE. MAIN EXCEPTION...ACROSS UPPER MICHIGAN ALONG THE SHORT WAVE TRACK WHERE STRONGEST QG-FORCING WILL PROBABLY SUSTAIN SHOWERS INTO EASTERN UPPER MICHIGAN PAST LUNCH TIME. THEN...UPSTREAM SFC FRONT WILL TRY TO ADVANCE INTO THE CWA DURING THE COURSE OF THE AFTERNOON...ALTHOUGH DUE TO LAKE INDUCED CHANGES IN THE LOW LEVEL WIND FIELD...FRONT AND ASSOCIATED LOW LEVEL CONVERGENCE WILL LIKELY LOSE IT/S IDENTITY. FRONT MAY "JUMP" INTO NORTHEAST LOWER MICHIGAN THIS AFTERNOON AIDED BY SE FLOW OF LAKE HURON. PROVIDED WE CAN EVENTUALLY THIN OUT THE STRATUS AND FOG BY EARLY-MID AFTERNOON...WE MIGHT BE ABLE TO GENERATE SOME INSTABILITY AS THE AFOREMENTIONED LOWER LEVEL MOISTURE AXIS NOSES UP THROUGH NE LOWER MICHIGAN ALONG THE FRONT. WILL SEE HOW THIS GOES. BUT AT THIS POINT...THE BEST PRECIP CHANCES THROUGH THIS EVENING ARE SETTING UP FOR EASTER UPPER MICHIGAN (ALONG THE SHORT WAVE TRACK)...AS WELL AS NORTHEAST LOWER...THAT IS IF WE CAN MUSTER SOME HEATING AND DESTABILIZATION. CERTAINLY NOT A RAIN OUT EVENT BY ANY STRETCH. BUT FOLKS MAKING OUTDOOR HOLIDAY PLANS SHOULD AT LEAST PLAN FOR THE POTENTIAL FOR A PERIOD OF SHOWERS AND SOME THUNDER...ESPECIALLY IN EASTERN UPPER AND NORTHEAST LOWER. SEVERE THREAT...AGAIN INSTABILITY DEPENDENT. WIDESPREAD SEVERE WEATHER NOT ANTICIPATED. BUT...MID LEVEL FLOW DOES INCREASE TO 35 TO 4O KNOTS ALONG THE FRONT...LEADING TO SOME BULK SHEAR TO CAPITALIZE ON. COMBINED WITH BACKED FLOW OFF LAKE HURON...ANY STORMS THAT MANAGE TO DEVELOP IN NE LOWER MICHIGAN WILL BEAR SCRUTINY. UPDATE ISSUED AT 703 AM EDT SUN SEP 1 2013 STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8 WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID MORNING FOR EASTERN UPPER. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 352 AM EDT SUN SEP 1 2013 CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK. MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH THE FRONT. CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER 50S TO LOWER HALF OF THE 60S FOR MOST. TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS. PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG) FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT 30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT. THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY. LOW TEMPS TO FALL INTO THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 352 AM EDT SUN SEP 1 2013 INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH TEMPERATURES MONDAY THEN POPS TO END THE PERIOD. LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS. THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST. ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE LOWER 60S NORTH TO AROUND 70 SOUTHEAST. MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE 70S. WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S. FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR NORTH TO AROUND 80 SOUTH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 703 AM EDT SUN SEP 1 2013 IFR STRATUS HAS BECOME FAIRLY WIDESPREAD ACROSS NE LOWER...WHILE FOG HAS BEEN AN ISSUE AT PLN AND MBL. THE STRATUS WILL LIKELY LIFT INTO MVFR AND FINALLY INTO VFR BY LATE MORNING. THE FOG LIKELY TO LIFT SOONER. HIGH CLOUDS WILL STREAM IN FROM THE WEST...IN ADVANCE OF UPPER LEVEL SHORTWAVE AND CLUSTER OF SHOWERS AND STORMS FROM NE WISCONSIN/CENTRAL UPPER. THESE ARE NOT LIKELY TO AFFECT NW LOWER TAF SITES. RATHER...WILL BE AWAITING A COLD FRONT THAT WILL BE ASSOCIATED WITH A DIFFERENT DEVELOPING BAND OF SHOWERS AND STORMS WHICH WILL LIKELY BE A SCATTERED BAND OF ACTIVITY ROLLING THROUGH. WILL JUST TIME THIS WITH A VCTS FOR RIGHT NOW...AS THE BETTER ACTION WILL LIKELY BE ACROSS EASTERN UPPER. APN TO GET VCTS IN THE EVENING TONIGHT. ATMOSPHERE IS TOO CAPPED OFF FOR ANY DIURNAL LAKE BREEZE CONVERGENCE FORCING. WINDS WILL BECOME MORE VARIABLE/LIGHT AS THE FRONT/LOW PRESSURE SWINGS THROUGH...WITH AN ABRUPT SWITCH TO OUT OF THE NW LATE IN THE TAF PERIOD...AND INCREASE IN SPEED. THIS SPEED INCREASE WILL BE FELT MORE TOMORROW DURING THE DAY. && .MARINE... ISSUED AT 352 AM EDT SUN SEP 1 2013 A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS. THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...BA SYNOPSIS...AS SHORT TERM...SD LONG TERM...AS AVIATION...SD MARINE...SD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
714 AM EDT SUN SEP 1 2013 .SYNOPSIS... ISSUED AT 352 AM EDT SUN SEP 1 2013 A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED FOR THE REMAINDER OF THE WEEK. && .UPDATE... ISSUED AT 703 AM EDT SUN SEP 1 2013 STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8 WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID MORNING FOR EASTERN UPPER. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 352 AM EDT SUN SEP 1 2013 CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK. MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH THE FRONT. CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER 50S TO LOWER HALF OF THE 60S FOR MOST. TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS. PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG) FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT 30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT. THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY. LOW TEMPS TO FALL INTO THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 352 AM EDT SUN SEP 1 2013 INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH TEMPERATURES MONDAY THEN POPS TO END THE PERIOD. LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS. THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST. ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE LOWER 60S NORTH TO AROUND 70 SOUTHEAST. MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE 70S. WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S. FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR NORTH TO AROUND 80 SOUTH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 703 AM EDT SUN SEP 1 2013 IFR STRATUS HAS BECOME FAIRLY WIDESPREAD ACROSS NE LOWER...WHILE FOG HAS BEEN AN ISSUE AT PLN AND MBL. THE STRATUS WILL LIKELY LIFT INTO MVFR AND FINALLY INTO VFR BY LATE MORNING. THE FOG LIKELY TO LIFT SOONER. HIGH CLOUDS WILL STREAM IN FROM THE WEST...IN ADVANCE OF UPPER LEVEL SHORTWAVE AND CLUSTER OF SHOWERS AND STORMS FROM NE WISCONSIN/CENTRAL UPPER. THESE ARE NOT LIKELY TO AFFECT NW LOWER TAF SITES. RATHER...WILL BE AWAITING A COLD FRONT THAT WILL BE ASSOCIATED WITH A DIFFERENT DEVELOPING BAND OF SHOWERS AND STORMS WHICH WILL LIKELY BE A SCATTERED BAND OF ACTIVITY ROLLING THROUGH. WILL JUST TIME THIS WITH A VCTS FOR RIGHT NOW...AS THE BETTER ACTION WILL LIKELY BE ACROSS EASTERN UPPER. APN TO GET VCTS IN THE EVENING TONIGHT. ATMOSPHERE IS TOO CAPPED OFF FOR ANY DIURNAL LAKE BREEZE CONVERGENCE FORCING. WINDS WILL BECOME MORE VARIABLE/LIGHT AS THE FRONT/LOW PRESSURE SWINGS THROUGH...WITH AN ABRUPT SWITCH TO OUT OF THE NW LATE IN THE TAF PERIOD...AND INCREASE IN SPEED. THIS SPEED INCREASE WILL BE FELT MORE TOMORROW DURING THE DAY. && .MARINE... ISSUED AT 352 AM EDT SUN SEP 1 2013 A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS. THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...SD SYNOPSIS...AS SHORT TERM...SD LONG TERM...AS AVIATION...SD MARINE...SD
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
414 AM PDT SUN SEP 1 2013 .SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL LEVELS BY THE MIDDLE OF THE WEEK. && .UPDATE...IT JUST KEEPS ON GOING. CONVECTION ACROSS MOHAVE COUNTY IS STILL GOING. EVEN THOUGH CLOUD TOPS HAVE WARMED QUITE A BIT IN THE LAST HOUR, THE AREAL EXTENT OF ACTIVITY HAS SPREAD OUT MORE THAN EXPECTED AND WILL LIKELY LAST PAST 12Z. THEREFORE, I WENT AHEAD AND ADJUSTED POPS TO MATCH THE LATEST RADAR TRENDS, ESPECIALLY ACROSS EASTERN SAN BERNARDINO COUNTY WHERE LIGHT RAIN WAS COVERING A LARGE AREA. THE REST OF THE FORECAST STILL LOOKS GOOD. && .PREVIOUS DISCUSSION... ISSUED AT 304 AM PDT SUN SEP 1 2013 .SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH OF THE NORTHWEST CWFA. FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS. ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN. TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER. FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER, IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER. ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA. GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR MOST OF THE LONG TERM. && .AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS. THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING MOUNTAINS TOWARD THE AIRPORT COMPLEX. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH TONIGHT. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022. FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ014. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519>521. && $$ STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
304 AM PDT SUN SEP 1 2013 .SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL LEVELS BY THE MIDDLE OF THE WEEK. && .SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH OF THE NORTHWEST CWFA. FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS. ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN. TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER. FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER, IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER. ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA. GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR MOST OF THE LONG TERM. && .AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS. THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING MOUNTAINS TOWARD THE AIRPORT COMPLEX. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH TONIGHT. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022. FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ014. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519>521. && $$ STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
303 AM PDT SUN SEP 1 2013 .SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL LEVELS BY THE MIDDLE OF THE WEEK. && .SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH OF THE NORTHWEST CWFA. FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW THINGS NOT GET GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS. ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN. TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER. FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER, IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER. ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA. GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR MOST OF THE LONG TERM. && .AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS. THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING MOUNTAINS TOWARD THE AIRPORT COMPLEX. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH TONIGHT. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022. FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ014. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519>521. && $$ STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
301 AM PDT SUN SEP 1 2013 .SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL LEVELS BY THE MIDDLE OF THE WEEK. && .SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SO HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH OF THE NORTHWEST CWFA. FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW THINGS NOT GET GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS. ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN. TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER. FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER, IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER. ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA. GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR MOST OF THE LONG TERM. && .AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS. THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING MOUNTAINS TOWARD THE AIRPORT COMPLEX. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH TONIGHT. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022. FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ014. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519>521. && $$ STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
534 AM MDT SUN SEP 1 2013 .AVIATION... 12Z TAF CYCLE ISOLD -SHRA AND POSSIBLY -TSRA LINGERING OVER ERN NM BEFORE 18Z WILL BECOME MORE NUMEROUS AS WELL AS DEVELOP OVER THE WRN HIGH TERRAIN THEREAFTER AS SURFACE FRONT PUSHES INTO NE NM AND THEN SOUTH AND WWD...REACHING THE CENTRAL MT CHAIN BY 23Z. ISOLD TO WDLY SCT MVFR CIGS/VSBY IN SHRA/TSRA TO OCCASIONALLY OBSCURE HIGHER TERRAIN. CELL MOVEMENT TO BE SLOW AND OCCASIONALLY ERRATIC DUE TO UPPER HIGH PRESSURE CENTER OVERHEAD. && .PREV DISCUSSION...324 AM MDT SUN SEP 1 2013... ...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR DAY... COLD FRONT APPEARS TO BE IN NORTHEASTERN CO STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED. LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40. WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF 400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST TOWARD TX. TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP SUBTROPICAL MOISTURE INTRUSIONS. 52 && .FIRE WEATHER... UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY. WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM. NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON. NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH RECOVERIES ANTICIPATED. CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO POOR VENTILATION LIKELY OVER THE WEST AND NORTH. A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES. AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY. WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST. HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND CENTRAL NM. && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1013 AM CDT SUN SEP 1 2013 .UPDATE... ISSUED AT 1013 AM CDT SUN SEP 1 2013 GIVEN VISIBLE SATELLITE TRENDS THROUGH 15 UTC...INCREASED CLOUD COVER THROUGH 18 UTC AS THE BREAK UP AND LIFTING OF THE STRATUS FIELD IS TAKING LONGER THAN PREVIOUSLY FORECAST. THIS IS CONFIRMED BY THE 12 UTC HRRR LOW LEVEL CLOUD COVER FORECASTS. OTHERWISE...THE REMAINDER OF THE FORECAST IS ON TRACK. UPDATE ISSUED AT 655 AM CDT SUN SEP 1 2013 NO SIGNIFICANT CHANGES MADE TO THE FORECAST. TEMPERATURES ARE RUNNING A LITTLE WARMER THAN FORECAST AT LOCATIONS UNDER CLOUD COVER. OTHERWISE...THE FORECAST IS ON TRACK. SATELLITE CONTINUES TO SHOW CLOUDS PUSHING SOUTHWARD...ALMOST TO BISMARCK AT THIS TIME. OBS INDICATING CEILINGS WITH THESE CLOUDS AROUND 1000-1500 FEET. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 301 AM CDT SUN SEP 1 2013 DRIER AND COOLER WEATHER WILL HIGHLIGHT THE SHORT TERM FORECAST. CLOUD COVER EXTENT AND TIMING IS THE MAIN FORECAST CONCERN...AS THIS WILL IMPACT MAXIMUM TEMPERATURES. CURRENTLY...HIGH PRESSURE WAS CENTERED OVER SOUTHERN SASKATCHEWAN WITH THE HIGH AXIS EXTENDING INTO EASTERN MONTANA. AN AREA OF VFR/MVFR CLOUDS OVER SOUTHERN SASKATCHEWAN AND MANITOBA HAD EDGED INTO NORTHERN NORTH DAKOTA. MODELS WERE SUGGESTING THESE CLOUDS WILL MOVE SOUTH ACROSS THE STATE THIS MORNING. THE HIGH CENTER IS FORECAST TO MOVE SOUTHEAST AND BY EARLY AFTERNOON BE CENTERED OVER LAKE WINNIPEG INTO THE JAMES/RED RIVER VALLEYS. NORTHWEST WINDS SHOULD BECOME NORTH...THEN NORTHEAST INTO THE LATER MORNING HOURS. AS THE HIGH MOVES SOUTHEAST...MODELS ARE SUGGESTING CLEARING SKIES NEAR THE HIGH CENTER AND ASSOCIATED CLOUDS REMAINING ON THE WESTERN/SOUTHERN PERIPHERY OF THE HIGH LATER THIS MORNING AND EARLY AFTERNOON TODAY BEFORE FINALLY DISSIPATING DURING THE MID-LATE AFTERNOON HOURS. THIS WOULD RESULT IN CLEARING SKIES OVER THE TURTLE MOUNTAINS...WITH PARTLY TO MOSTLY CLOUDY SKIES OVER MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THROUGH EARLY AFTERNOON...THEN SCATTERING OUT DURING THE MID-LATE AFTERNOON. THIS RESULTS IN AFTERNOON HIGH TEMPERATURES A TAD LOWER THAN THE PREVIOUS FORECAST. SO...HIGHS FROM THE UPPER 60S IN THE TURTLE MOUNTAINS TO THE UPPER 70S IN THE SOUTHWEST. TONIGHT CLEAR SKIES ARE EXPECTED. THE HIGH CENTER IS FORECAST TO SETTLE OVER MINNESOTA AND THE FAR EASTERN DAKOTAS...WITH RETURN SOUTHEASTERLY FLOW DEVELOPING OVER THE WESTERN DAKOTAS. THUS LOWER MINIMUM TEMPERATURES OVER THE JAMES RIVER BASIN - CLEAR SKIES AND LIGHT WINDS CLOSER TO THE HIGH CENTER - EXPECTING LOWS IN THE MID 40S. LOW TO MID 50S FOR LOWS IN THE WEST FARTHER FROM THE HIGH CENTER AND WHERE SOUTHEASTERLY WINDS SHOULD KEEP THE LOWER ATMOSPHERE MIXED SOMEWHAT AND KEEP THE TEMPERATURES FROM LOWERING INTO THE 40S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 301 AM CDT SUN SEP 1 2013 MAJORITY OF THE EXTENDED PERIOD WILL BE DOMINATED BY STRONG RIDGE THAT EXTENDS FROM AROUND NEW MEXICO THROUGH ALBERTA/SASKATCHEWAN. LITTLE CHANGE IN THE PATTERN EXPECTED THROUGH MUCH OF THE WEEK WITH THE RIDGE LOCATED BETWEEN DEEP UPPER LOW JUST OFF PAC NW COAST AND TROUGH OVER EASTERN NORTH AMERICA. THIS WILL RESULT IN MOSTLY DRY CONDITIONS AND TEMPERATURES RUNNING WELL ABOVE NORMAL WITH HIGHS IN THE 80S TO LOW 90S. TOWARD THE END OF THE WEEK THE PAC NW LOW BEGINS MOVING INLAND REACHING MONTANA BY SAT NIGHT PER 00Z GFS/ECMWF. ONE WAVE DEPICTED BY GFS/ECMWF RIDES RIDGE AND APPROACHES ND BY TUESDAY RESULTING IN SOME LOW POPS FOR MAINLY WESTERN ND TUE AND TUE NIGHT. BETTER LIKELIHOOD OF PRECIPITATION BY SATURDAY AS THE UPPER LOW APPROACHES THE REGION. GFS/ECMWF INDICATE SURFACE LOW IN VICINITY OF EASTERN MONTANA SATURDAY AFTERNOON LEAVING NORTH DAKOTA IN WARM SECTOR WITH GFS INDICATING AXIS OF INSTABILITY && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 1013 AM CDT SUN SEP 1 2013 MVFR STRATUS IMPACTING KMOT/KISN/KBIS WILL SLOWLY LIFT AND BREAK UP THROUGH THE 16-18 UTC TIME FRAME. OTHERWISE...VFR CONDITIONS ARE FORECAST WITH HIGH PRESSURE IN PLACE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...JV LONG TERM...JNS AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
633 AM CDT SUN SEP 1 2013 .UPDATE... ISSUED AT 630 AM CDT SUN SEP 1 2013 WE WILL INCREASE CLOUD COVER A BIT THIS MORNING BEFORE CLEARING MOVES IN FROM THE NW. THE LATEST HRRR ACTUALLY HOLDS ONTO CLOUDS LONGER TODAY...AND IT COULD BE CLOUDY A BIT LONGER THAN EXPECTED. FOR NOW WILL BE MORE OPTIMISTIC WITH CLEARING PER THE NAM...BUT MAY HAVE TO INCREASE CLOUDS TODAY IF THIS TREND CONTINUES. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 310 AM CDT SUN SEP 1 2013 THE MAIN CHALLENGE WILL BE TEMPS WITH DRY WEATHER THROUGH AT LEAST FRIDAY NIGHT. MODELS ARE IN VERY GOOD OVERALL AGREEMENT AND NO REAL PREFERENCE THIS MORNING...SO A MODEL BLEND WILL BE UTILIZED THIS MORNING. FOR TODAY...A STRONG COLD FRONT HAS USHERED IN UNSEASONABLY COOL AIR FOR THE FIRST DAY OF SEPTEMBER. IT WILL BE BREEZY THROUGH MID AFTERNOON WITH ABOUT 25KT TO MIX...AND TEMPS WILL STRUGGLE TO REACH 70 IN MOST AREAS. THERE WILL BE CLOUDS FOR THE MORNING HOURS NEAR THE STRONGEST COLD ADVECTION...WITH PLENTIFUL SUNSHINE AND HIGH CONVECTIVE TEMPS THIS AFTERNOON FOR ALL BUT THE FAR EAST. FOR TONIGHT...COLD HIGH PRESSURE WILL SETTLE OVER THE REGION...AND EXPECT LOWS TO FALL INTO THE LOW/MID 40S FOR ALL AREAS. THERE COULD BE SOME AREAS AROUND 40 WHERE WINDS DECOUPLE QUICKLY THIS EVENING...MOST LIKELY IN THE NORTHERN RED RIVER VALLEY. ON MONDAY...TEMPS WILL WARM TO AROUND NORMAL WITH PLENTY OF SUNSHINE EXPECTED. SFC HIGH PRESSURE WILL MOVE INTO WESTERN MN...AS RETURN FLOW DEVELOPS OVER THE CENTRAL DAKOTAS. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 1 2013 FOR MONDAY NIGHT...IT WILL BE WARMER THAN SUNDAY NIGHT...WITH SOUTHERLY WINDS INCREASING A BIT LATE IN THE WEST. FOR TUE...IT WILL WARM ABOVE NORMAL WITH UPPER RIDGING AND 850MB TEMPS WARMING TO AROUND +20C IN THE WEST. WEDNESDAY THROUGH SATURDAY NIGHT...TRANQUIL CONDITIONS WILL CONTINUE. 500 TO 300 HPA RIDGE AXIS REMAINS ACROSS EASTERN MT/ WESTERN DAKOTAS...BUT MID-LEVEL THERMAL AXIS PUSHES EAST A BIT EACH DAY...SO THAT DAYTIME HIGHS CLIMB BACK INTO THE MID TO UPPER 80S BY FRIDAY. A DEGREE OR TWO OF COOLING IS POSSIBLE BY SATURDAY AS THE RIDGE BEGINS TO BREAK-DOWN A BIT IN ADVANCE OF THE NEXT PACIFIC SHORT-WAVE. DRY CONDITIONS WILL CONTINUE THROUGH SATURDAY GIVEN PERSISTENT SURFACE HIGH PRESSURE WITH THE NEXT BEST CHANCE FOR SHOWERS AND THUNDERSTORMS SATURDAY NIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 630 AM CDT SUN SEP 1 2013 THE BIGGEST CHALLENGE WILL BE WHEN CLEARING WILL MOVE INTO THE AREA. EXPECT THE WEST AND NORTH TO CLEAR FIRST...WITH MFVR AND LOCAL IFR CONDITIONS THIS MORNING PERSISTING IN THE EAST. NORTHERLY WINDS WILL GUST OVER 20KT IN ALL AREAS THROUGH MID AFTERNOON BEFORE QUICKLY SUBSIDING AROUND SUNSET. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...DK SHORT TERM...DK LONG TERM...DK/ROGERS AVIATION...DK
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1020 AM EDT SUN SEP 1 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... 10 AM UPDATE. ADJUSTED POPS WITH SHORT WAVE CROSSING AREA TODAY PER RADAR...SATELLITE...SURFACE ANALYSIS TREND AND THE HRRR MODEL. LOOKS LIKE THE HRRR MODEL HAS A VERY GOOD GRASP ON WHAT IS CURRENTLY GOING ON MESOSCALE WISE PER THE CURRENT TRENDS...WHEREAS OTHER MODELS ARE ACCOUNTING MORE FOR GENERAL SYNOPTIC SCALE FORCING AND JUST PAINTING THE ARE WITH QPF. CONVECTION TO OUR SOUTH AND SOUTHWEST...WHICH HAS KEPT THINGS QUIET AROUND HERE...HAS WEAKENED TO THE POINT WHERE NEW CONVECTION DEVELOPING OVER SOUTHERN KENTUCKY IS STARTING TO LIFT NORTHEAST. THIS WILL BRING THE HIGHEST POPS...PER HRRR...INTO THE MOUNTAINS THROUGH THIS AFTERNOON. ELSEWHERE...LACK OF FOCUSING AND UNIMPRESSIVE INSTABILITY SUGGESTS THAT EVEN WITH SUNSHINE...CONVECTION OF A MORE SCATTERED NATURE CAN BE EXPECTED. THUS...UPDATED TO LIKELY MOUNTAINS AND SCATTERED ELSEWHERE...WITH A BIT LESS CLOUDS OUTSIDE OF MOUNTAINS. TEMPS STILL LOOK GOOD. PREVIOUS DISCUSSION... THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7 TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT. SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION. WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET. INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN. ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION. THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH. TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH PRESSURE MOVES INTO THE AREA FROM THE NW. RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR DAY WEEKEND. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK. TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED PRECIPITATION. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... 14Z SUNDAY THROUGH 12Z MONDAY... SHORT WAVE CROSSES AREA TODAY...WITH MOST OF THE CONVECTION IN THE MOUNTAINS THIS AFTERNOON...SCATTERED AFTERNOON DIURNAL CONVECTION ELSEWHERE. EXPECT VFR OUTSIDE OF CONVECTION...EXCEPT WILL INCLUDE PREVAILING MVFR IN CENTRAL AND SOUTHERN MOUNTAINS...ESPECIALLY AT BKW GIVEN THE SUSTAINED HIGH POPS. BULK OF CONVECTION WILL DIE DOWN AFTER 03Z...BUT STILL CANNOT TOTALLY PULL POPS GIVEN THE MAIN SHORT WAVE AND FRONT ARE STILL TO THE WEST. WILL KEEP ISOLATED. FOG DEVELOPMENT TONIGHT WILL DEPEND ON THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE DAY...BUT THINK MOST SITES WILL SEE ENOUGH STARS TO BRING IN MVFR TO IFR FOG AFTER 05Z...ESPECIALLY ALONG RIVERS AND IN VALLEYS WHERE IT RAINS TODAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND RESTRICTIONS IN CONVECTION DEPENDS ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG DEVELOPMENT AND DENSITY MAY VARY FROM CURRENT FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 CRW CONSISTENCY H H H H M M H H H H H H HTS CONSISTENCY H H H M M M H H H H H H BKW CONSISTENCY H H H H M M M M M H H H EKN CONSISTENCY H H H H M M M M H H H H PKB CONSISTENCY H H H M M M M H H H H H CKB CONSISTENCY H H H H M M M M M H H H AFTER 12Z MONDAY... IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE TUESDAY AND WEDNESDAY MORNINGS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...JMV/SL SHORT TERM...TRM LONG TERM...26 AVIATION...JMV/SL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
624 AM EDT SUN SEP 1 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE TODAY...AND A COLD FRONT APPROACHING MONDAY...CONTINUE THE CHANCE FOR THUNDERSTORMS. THE PASSAGE OF THE FRONT BRINGS AN END TO THE THUNDERSTORMS FOR THE SHORT WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE UNSETTLED WEATHER PATTERN CONTINUES...WITH THE MODELS IN DECENT AGREEMENT IN THE NEAR TERM PERIOD. UPPER LEVEL DISTURBANCE AT 06Z MOVING INTO WESTERN OHIO...WILL CONTINUE TO PUSH EAST TODAY...WITH SHOWERS AND THUNDERSTORMS BECOMING LIKELY...PARTICULARLY DURING PEAK HEATING HOURS. PW VALUES ABOVE NORMAL ACROSS THE CWA...GENERALLY 1.7 TO 1.9 INCHES FOR THE PERIOD...WITH ANY STORMS PRODUCING HEAVY DOWNPOURS. COLD FRONT JUST TO THE NORTH OF THE CWA AT 06Z WILL SLOWLY CONTINUE TO SAG SOUTH INTO SOUTHEAST OHIO ZONES BY THE END OF THE NEAR TERM AND WEAKEN AS IT DOES SO. THIS WILL THEN BE OVERTAKEN BY ANOTHER SE MOVING COLD FRONT ON MONDAY AS LOW PRESSURE CONTINUES TO PUSH TO THE EAST. THERE COULD BE SOME STORMS ON THE STRONGER SIDE TO THE WEST OF THE CWA OUT AHEAD OF THIS COLD FRONT...AND THE POTENTIAL EXISTS FOR A STRONGER STORM TO SURVIVE INTO OUR WESTERN ZONES TODAY...WITH STRONG WIND GUSTS THE PRIMARY THREAT. SOME PARTIAL CLEARING IS POSSIBLE TONIGHT...MAINLY ACROSS SOUTHEAST OHIO ZONES...AS THE UPPER DISTURBANCE PUSHES EAST OF THE AREA. FOG DEVELOPMENT TONIGHT WILL BE TRICKY AND WILL DEPEND LARGELY ON LOCATIONS OF CONVECTION ACROSS THE CWA...AS WELL AS LOCATION/EXTENT OF CLEARING. POPS WILL RAPIDLY INCREASE TOWARDS THE END OF THE PERIOD...AS THE COLD FRONT STARTS TO MOVE SOUTHEAST INTO THE REGION. WILL CONTINUE TO HOLD OFF ON A FFA ACROSS NORTHERN WV ZONES AND KEEP A MENTION IN THE HWO...AS AREA HAS SEEN RATHER DRY WEATHER THE PAST FEW DAYS. 3 HOUR FFG VALUES HAVE RECOVERED NICELY...CLIMBING TO AROUND 2 INCHES FOR MUCH OF NORTHERN/CENTRAL WV. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... UPPER LEVEL S/W TROUGH PUSHES SFC COLD FRONT THROUGH THE AREA MON NT INTO TUE. LEAD S/W TROUGH AHEAD OF THE MAIN TROUGH AXIS IS EXODUS BY THE START OF THE SHORT TERM. WHAT REMAINS IS A BROAD BASED TROUGH WITH UPPER LEVEL SUPPORT NOT VERY FOCUSED...OTHER THAN UPPER LEVEL DIVERGENCE ASSOCIATED WITH RR ENTRANCE REGION OF JET. INTEGRATED MOISTURE CONTENT ALSO DECREASES FROM THE N...WITH PW VALUES PEAKING AROUND 1.7 INCHES. THIS IS STILL ENOUGH TO SUPPORT DOWNPOURS WITH LOCALLY EXCESSIVE RAINFALL...ESPECIALLY OVER AREAS THAT GET HIT HARD IN THE NEAR TERM. FFG VALUES OVER NORTHERN WV HAVE INCREASED A BIT...BUT POCKETS AS LOW AS 1.2 IN PER HR REMAIN. ON THE OTHER HAND...THE TIMING OF WHATEVER UPPER LEVEL FORCING THERE IS ASSOCIATED WITH THE APPROACHING SFC FRONT HAS SLOWED...AND IS NOW CONDUCIVE TO THE DIURNAL HEATING CONTRIBUTION. THE SFC FRONT MOVES THROUGH THE AREA MON NT INTO TUE. THE NAM IS SLOWER COMPARED WITH GLOBAL MODELS...APPLY REFLECTION THE LOCAL EFFECTS THE MOUNTAINS HAVE ON SLOWING FRONTS...ESPECIALLY THOSE OF THE WEAKER SUMMER VARIETY. THIS LEAVES UNSTABLE AIR IN PLACE AT LEAST E OF THE OHIO RIVER TUE. HOWEVER...LITTLE FORCING REMAINS...SO JUST HAVE SLIGHT CHANCE FOR SHOWERS ENDING TUE MORNING. THERE WILL LIKELY BE A LOT OF CU AROUND THROUGH. TUE NT TURNS OUT CLEAR WITH DENSE VALLEY FOG FORMING...AS HIGH PRESSURE MOVES INTO THE AREA FROM THE NW. RAISED TEMPERATURES SLIGHTLY MON AND TUE...MOSTLY VIA THE MET...STILL AT THE LOW END OF GUIDANCE FOR HIGHS TUE. FRONT TUE WILL NOT BE FAST ENOUGH FOR STRATUS TO SET UP IN THE MORNING...BUT THERE WILL LIKELY BE AN EXPANSIVE CU FIELD COME MIDDAY. FOR THE START OF THE SHORT WORK WEEK...SIGNIFICANTLY LOWER TEMPERATURES AND DEW POINTS REPLACE THE MID SUMMER-LIKE AIR MASS IN PLACE THIS LABOR DAY WEEKEND. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED FORECAST LEANS HEAVILY TOWARDS THE DRY SIDE WITH HIGH PRESSURE SETTLING INTO THE AREA THROUGH THE END OF THE WEEK. TEMPERATURES BEGIN SLIGHTLY BELOW NORMAL WEDNESDAY...AND WILL SLOWLY MODIFY IN DECENT INSOLATION EACH DAY THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. WILL NEED TO WATCH THE 500MB FLOW TRANSITION TO A MORE ZONAL REGIME FOR THE END OF THE WEEKEND...WHICH WILL BRING THE NEXT CHANCE FOR ORGANIZED PRECIPITATION. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... 12Z SUNDAY THROUGH 12Z MONDAY... PATCHY MVFR/IFR FOG AT A FEW LOCATIONS...BUT FOR THE MOST PART...VFR CONDITIONS WITH LIGHT SURFACE WINDS. CONVECTION WILL INCREASE IN COVERAGE AGAIN AFTER 15Z...AS AN UPPER DISTURBANCE MOVES EAST THROUGH THE AREA. EXPECT BRIEF MVFR/IFR CONDITIONS AND GUSTY WINDS IN VICINITY OF STORMS. BULK OF CONVECTION WILL DIE DOWN AFTER 03Z. FOG DEVELOPMENT TONIGHT WILL DEPEND ON THE AMOUNT OF CLEARING AND LOCATION OF PRECIPITATION DURING THE DAY. BEST LOCATION FOR POTENTIAL FOG DEVELOPMENT WILL BE EASTERN KENTUCKY AND SOUTHEAST OHIO WHERE BETTER CLEARING IS EXPECTED...BUT THINKING MOST LOCATIONS WILL REMAIN VFR UNDER EXTENSIVE CLOUD COVER. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND RESTRICTIONS IN CONVECTION DEPENDS ON HARD TO DISCERN MESOSCALE INFLUENCES. FOG DEVELOPMENT AND DENSITY MAY VARY FROM CURRENT FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18 CRW CONSISTENCY H H H H H H H M M H H H HTS CONSISTENCY H H H H H H M M M H H H BKW CONSISTENCY M H H H H H H M M M M M EKN CONSISTENCY M H H H H H H M M M M H PKB CONSISTENCY H H H H H H M M M M H H CKB CONSISTENCY H H H H H H H M M M M M AFTER 12Z MONDAY... IFR POSSIBLE IN CONVECTION THROUGH AT LEAST MONDAY. IFR FOG POSSIBLE TUESDAY AND WEDNESDAY MORNINGS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL SHORT TERM...TRM LONG TERM...26 AVIATION...SL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
743 AM EDT SUN SEP 1 2013 .SYNOPSIS... MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... 5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG. AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA. ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE NEEDED. STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL. THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE HIGHEST CHANCES BY MID AFTN. TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES. SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE HEAVY RAIN AND FLASH FLOODING STILL A THREAT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY. CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING. WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED. LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE NITE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW NORMAL AND RISE TO NEAR NORMAL. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AT KCLT...SMALL POSSIBILITY OF A LOW CIG SETTLING IN AROUND DAYBREAK AND KEEPING A RESTRICTION AFTER 12Z...BUT PRETTY CONFIDENT IN VFR TO START THE TAF. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND HAVE THEM IN A TEMPO IN THE EARLY TO MID AFTN...AND A VCSH SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD. FOLLOWING THE END OF THE DIURNAL CONVECTION VFR WILL PREVAIL...BUT GUIDANCE SUGGESTS SOME FOG POSSIBLE LATE TONIGHT ONCE AGAIN. THIS IS ESPECIALLY LIKELY IF THE FIELD IS HIT BY A SHOWER OR TSTM TODAY. ELSEWHERE...EARLY MORNING DENSE FOG AND LIFR TO VLIFR CLOUD BASES EXPECTED ACROSS THE MTNS TO THE WESTERN PIEDMONT EARLY THIS MORNING. CLIMO INDICATES THAT CONDITIONS MAY NOT IMPROVE TO VFR UNTIL 14Z. SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST EARLY TODAY THOUGH CURRENT TRENDS SUGGEST LITTLE DIRECT THREAT TO KAVL OR ANY OTHER TAF SITE. HOWEVER DIURNAL INSTABILITY WILL GROW QUICKLY ONCE THE LOW CIGS BURN OFF. KAVL AND THE MTNS WILL LIKELY SEE SHRA/TSRA THIS AFTN. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL KEEP TEMPOS DURING THE AFTERNOON AS WELL AS A VCSH/VCTS AS NECESSARY TO INDICATE LESSER PROBABILITY IN THE SURROUNDING TIMEFRAME. FLOW REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH RESTRICTIONS WILL MAINLY COME FROM FOG. SITES AFFECTED BY TSRA/SHRA TODAY ARE MOST LIKELY TO GO DOWN TONIGHT...BUT IN GENERAL MOST SITES HAVE A GOOD SHOT AT SEEING AT LEAST MVFR VSBY BEFORE DAYBREAK. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER AIR WILL FOLLOW THE FRONT. CONFIDENCE TABLE... 11-17Z 17-23Z 23-05Z 05-11Z KCLT HIGH 94% HIGH 100% HIGH 100% HIGH 94% KGSP HIGH 83% HIGH 100% HIGH 100% HIGH 94% KAVL LOW 59% HIGH 100% HIGH 97% MED 77% KHKY MED 78% HIGH 100% HIGH 88% HIGH 94% KGMU MED 79% HIGH 100% HIGH 100% HIGH 91% KAND MED 75% HIGH 100% HIGH 100% HIGH 86% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...NED/WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
741 AM EDT SUN SEP 1 2013 .SYNOPSIS... MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE AREA AS WEAK HIGH PRESSURE SLOWLY SLIDES OFFSHORE TODAY. THIS MOIST FLOW WILL HELP TO KICK OFF SHOWERS AND THUNDERSTORMS THROUGH LABOR DAY. A COLD FRONT CROSSES THE AREA TUESDAY WITH DRY HIGH PRESSURE RETURNING ON WEDNESDAY. MOISTURE AND SCATTERED THUNDERSTORMS RETURN BY NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... 5 AM UPDATE...SHRA/TSRA MOVING INTO THE SW MTNS ARE HAVING TROUBLE PUSHING FURTHER EAST...BUT WEAK UPSLOPE FLOW AND CONTINUING ELEVATED INSTBY MAY ALLOW SOME MORE DEVELOPMENT THERE. HRRR AND RAP BRING SOME ACTIVITY FROM DECAYING TENN VALLEY MCS ACRS THE NC BORDER JUST AFTER DAYBREAK. IT IS LOOKING LESS AND LESS ORGANIZED...SO DON/T HAVE A LOT OF CONFIDENCE THAT WILL HAPPEN...BUT FELT IT WAS A GOOD IDEA TO RAISE POPS SLIGHTLY NEAR THE BORDER EARLY THIS MRNG. AS OF EARLY SUNDAY MORNING...WESTERLY FLOW INTO THE MTNS IS MAKING THE MOST OF THE FEW HUNDRED JOULES OF MUCAPE STILL PRESENT OVER EAST TN...ALLOWING A FEW CELLS TO FIRE UP THERE AS OF 315 AM. THOUGH THE INSTABILITY WILL LIKELY WANE SOMEWHAT THRU DAYBREAK...GIVEN THE CONTINUED WLY LLVL WINDS HAVE KEPT ISOLD PRECIP MENTION NEAR THE TENN BORDER INTO THE MORNING. THE REMAINING PRECIP SHIELD FROM AN MCS WHICH MOVED THRU THE CUMBERLAND PLATEAU EARLIER IS MOVING TOWARD THE NC BORDER...BUT THIS MAY DISSOLVE BEFORE IT GETS TO OUR CWFA. ALSO NOTING A SECOND MCS OVER KY ON RADAR. STORM MOTION /FWD-PROP CORFIDI VECTOR/ FROM 00Z NASHVILLE SOUNDING SUGGESTS THIS WILL MOVE WEST OF OUR AREA...AND THIS IS BACKED UP BY 00Z SPC WRF. ON ANOTHER NOTE...LOW CLOUDS AND FOG NOW WIDESPREAD IN THE MTNS AND SPOTTY IN THE FOOTHILLS MAY WORSEN A BIT TOWARD DAYBREAK THOUGH WITH TEMPS NEARLY STEADY I THINK VSBY NOT GET TOO MUCH WORSE. IF DENSE FOG SETTLES INTO A LARGE CONTIGUOUS AREA A DENSE FOG ADVY MAY BE NEEDED. STILL EXPECTING A RELATIVELY SIMILAR SITUATION TODAY COMPARED TO YESTERDAY. THE CWFA REMAINS UNDER CYCLONIC UPPER FLOW WITH A FEW EMBEDDED EDDIES POTENTIALLY HELPING TO DRIVE CONVECTION. REGARDING THAT CONVECTION...NAM/GFS REMARKABLY DIFFERENT IN CAPE PROGS FOR TODAY...WITH THE GFS FEATURING SUSPICIOUSLY HIGH VALUES IN THE MTNS...ABOVE 4000 J/KG AT MIDDAY. NAM SEEMS TO REFLECT THE DELAYED WARMING DUE TO THE LOW CLOUDS IN THE MTNS...RAMPING UP INSTABILITY FIRST IN THE PIEDMONT AND KEEPING THE HIGHEST VALUES THERE OVERALL. THIS ALSO INDICATED BY SREF PROBS. THIS IS PLAUSIBLE SO I BROUGHT POPS UP THERE FIRST...BUT THE MTNS WILL LIKELY EVENTUALLY DESTABILIZE AND WITH SWLY UPSLOPE FLOW THEY WILL STILL SEE THE HIGHEST CHANCES BY MID AFTN. TONIGHT SOME ISENTROPIC LIFT IS NOTED ON 305K SURFACE FROM NAM/GFS...PERHAPS DUE TO WEAK WAA AS THE UPPER TROUGH SHIFTS SLOWLY EASTWARD. OTHERWISE THE PATTERN REMAINS ABOUT THE SAME...STILL SUPPORTIVE OF SOME NOCTURNAL CONVECTION...SO I HAVE KEPT SCT SHOWERS OVERNIGHT IN THE MTNS/FOOTHILLS AND ISOLD IN THE PIEDMONT. LOWS TONIGHT MAY BE A TAD WARMER WITH SLIGHTLY HIGHER THICKNESSES. SHEAR WILL BE WEAK ENOUGH TO PRECLUDE MOST SEVERE WEATHER...BUT GIVEN THE INSTABILITY WOULD NOT BE SURPRISED TO SEE A COUPLE STORMS PRODUCE STRONG TO SEVERE WINDS. VERY SLOW CORFIDI VECTORS INDICATE HEAVY RAIN AND FLASH FLOODING STILL A THREAT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... AS OF 220 AM SUN...A WEAK UPPER TROF REMAINS OVER THE AREA MONDAY WITH THE TROF AXIS SHIFTING OFF SHORE TUE WITH NWLY FLOW DEVELOPING WED. AT THE SFC...A LEE TROF REMAINS OVER THE AREA MONDAY KEEPING A MOIST S TO SWLY LOW LEVEL FLOW IN PLACE. A WEAK COLD FRONT JUMPS INTO THE TROF TUE AND SLIDES OFF SHORE TUE NITE AND WED. WITH DEEP MOISTURE IN PLACE MON...MODERATE INSTABILITY DEVELOPS LEADING TO ANOTHER DAY OF CONVECTION FAVORING THE MTNS WITH ONLY SLIGHTLY LOWER CHC ELSEWHERE. LOW LEVEL FLOW BECOMES WLY TUE AS THE FRONT JUMPS INTO THE LEE TROF. HOWEVER...ENUF LOW LEVEL MOISTURE REMAINS TO PRODUCE SCT CONVECTION WITH THE DEVELOPING MODERATE INSTABILITY. CONVECTION SHUD QUICKLY DIMINISH TUE NITE WITH LOSS OF HEATING. WITH DRIER HIGH PRESSURE MOVING IN WED...EXPECT ONLY CLOUDS WITH THE LINGERING LOW LEVEL MOISTURE. HIGHS WILL BE STEADY NEAR OR A LITTLE ABOVE NORMAL MON AND TUE...THEN DROP TO SLIGHTLY BELOW NORMAL WED. LOWS ABOUT 5 DEGREES ABOVE NORMAL MON NITE DROP TO NEAR NORMAL TUE NITE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 315 AM SUN...THE MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THRU THE PERIOD. A SERIES OF SHORT WAVES DROP THRU THE NWLY FLOW OVER THE AREA. THIS CAUSES A KINK IN THE FLOW CREATING A WEAK TROF OVER THE SERN US BY FRI WHICH STRENGTHENS ON SAT. DRY HIGH PRESSURE STARTS OVER THE AREA THU. THERE IS SOME LINGERING LOW LEVEL MOISTURE AND WEAK ELY LOW LEVEL FLOW. HOWEVER...EXPECT ONLY CLOUDS TO DEVELOP DURING THE DAY. A WEAK BACK DOOR COLD FRONT DROPS INTO THE AREA FRI WHICH COULD HELP PRODUCE ISOLATED DIURNAL CONVECTION. SCT DIURNAL CONVECTION EXPECTED SAT AS LOW LEVEL FLOW BECOMES SLY BRINGING BETTER MOISTURE AND INSTABILITY BACK INTO THE AREA. HIGHS START NEAR NORMAL AND FALL A LITTLE BELOW BY SAT. LOWS START OUT A LITTLE BELOW NORMAL AND RISE TO NEAR NORMAL. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AT KCLT...SMALL POSSIBILITY OF A LOW CIG SETTLING IN AROUND DAYBREAK AND KEEPING A RESTRICTION AFTER 12Z...BUT PRETTY CONFIDENT IN VFR TO START THE TAF. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND HAVE THEM IN A TEMPO IN THE EARLY TO MID AFTN...AND A VCSH SURROUNDING TO REFLECT A LOWER PROBABILITY SURROUNDING THIS PERIOD. FOLLOWING THE END OF THE DIURNAL CONVECTION VFR WILL PREVAIL...BUT GUIDANCE SUGGESTS SOME FOG POSSIBLE LATE TONIGHT ONCE AGAIN. THIS IS ESPECIALLY LIKELY IF THE FIELD IS HIT BY A SHOWER OR TSTM TODAY. ELSEWHERE...SOME CONVECTION MAY MOVE INTO THE MTNS FROM THE WEST EARLY TODAY THOUGH CURRENT TRENDS SUGGEST LITTLE DIRECT THREAT TO KAVL OR ANY OTHER TAF SITE. HOWEVER DIURNAL INSTABILITY WILL GROW QUICKLY ONCE THE LOW CIGS BURN OFF. KAVL AND THE MTNS WILL LIKELY SEE SHRA/TSRA THIS AFTN. THUNDER CHANCES A BIT HIGHER TODAY VS YESTERDAY AND WILL KEEP TEMPOS DURING THE AFTERNOON AS WELL AS A VCSH/VCTS AS NECESSARY TO INDICATE LESSER PROBABILITY IN THE SURROUNDING TIMEFRAME. FLOW REMAINS GENERALLY SOUTHWESTERLY /EXCEPT NW IN UP-VALLEY FLOW AT KAVL/ INTO TONIGHT. WITH LITTLE CHANGE IN THE PATTERN...A SIMILAR NIGHT IS LIKELY TO UNFOLD TONIGHT...THOUGH RESTRICTIONS WILL MAINLY COME FROM FOG. SITES AFFECTED BY TSRA/SHRA TODAY ARE MOST LIKELY TO GO DOWN TONIGHT...BUT IN GENERAL MOST SITES HAVE A GOOD SHOT AT SEEING AT LEAST MVFR VSBY BEFORE DAYBREAK. OUTLOOK...DIURNALLY DRIVEN ISOLD TO SCT CONVECTION EXPECTED AGAIN MONDAY. DAYBREAK FOG WILL BE MOST LIKELY IN MOUNTAIN VALLEYS AND WHERE RAIN FELL THE DAY BEFORE. A COLD FRONT WILL CROSS THE AREA ON TUESDAY...BUT CONVECTIVE CHANCES ARE UNCERTAIN AT THIS TIME. DRIER AIR WILL FOLLOW THE FRONT. CONFIDENCE TABLE... 11-17Z 17-23Z 23-05Z 05-11Z KCLT HIGH 94% HIGH 100% HIGH 100% HIGH 94% KGSP HIGH 83% HIGH 100% HIGH 100% HIGH 94% KAVL LOW 59% HIGH 100% HIGH 97% MED 77% KHKY MED 78% HIGH 100% HIGH 88% HIGH 94% KGMU MED 79% HIGH 100% HIGH 100% HIGH 91% KAND MED 75% HIGH 100% HIGH 100% HIGH 86% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...RWH NEAR TERM...WIMBERLEY SHORT TERM...RWH LONG TERM...RWH AVIATION...NED/WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1028 AM CDT SUN SEP 1 2013 .UPDATE... FORT WORTH SOUNDING SHOWS SLIGHT COOLING DURING THE LAST 24 HOURS IN THE LOWEST 50MB...SO TEMPS SHOULD BE A DEGREE OR SO COOLER THAN YESTERDAY. HOWEVER HIGHS WILL ONCE AGAIN REACH THE CENTURY MARK ACROSS MOST OF NORTH TEXAS TODAY AND DID RAISE THEM A BIT FROM THE PREVIOUS FORECAST IN A FEW LOCATIONS. THE MORNING SOUNDING ALSO INDICATED HIGHER PRECIPITABLE WATER WITH NOTABLE COOLING/MOISTENING OCCURRING IN THE MID LEVELS...SUGGESTING WEAK UPPER LEVEL LIFT IS NOW SPREADING ACROSS NORTH TEXAS. AS HEATING OCCURS TODAY WOULD EXPECT ISOLATED CONVECTION TO DEVELOP. HI-RES AND SHORT-TERM GUIDANCE DOES NOT FAVOR ANY PARTICULAR AREA FOR THIS POP-UP ACTIVITY...AND THUS WILL MENTION ISOLATED SHOWERS/STORMS EVERYWHERE THIS AFTERNOON WITH A 10 POP SINCE COVERAGE WILL BE LOW WITHOUT A SURFACE FOCUSING MECHANISM. A COLD FRONT WILL ARRIVE INTO THE NORTHERN ZONES AFTER 00Z...AND NORTHERN AND WESTERN ZONES WILL BE THE FAVORED AREA FOR MORE SIGNIFICANT RAINFALL COVERAGE TONIGHT. TR.92 && .AVIATION... CONCERNS...ISOLATED TO SCATTERED CONVECTION TONIGHT. FOR THIS FORECAST CYCLE...HAVE DECIDED TO KEEP ALL TAFS VFR. HOWEVER...A CONVECTIVE OUTFLOW BOUNDARY...CURRENTLY MOVING THROUGH CENTRAL OKLAHOMA...IS A CONCERN FOR THE METROPLEX TERMINALS AS IT IS EXPECTED TO MOVE SOUTH OF THE RED RIVER LATER THIS AFTERNOON. THIS BOUNDARY SHOULD BE ABLE TO FIRE ISOLATED TO WIDELY SCATTERED CONVECTION BETWEEN THE RED RIVER AND I-20 MID-LATE AFTERNOON AND OVERNIGHT PER LAST SEVERAL HI- RES RUNS AS WELL AS THE GFS AND NAM SERIES. ERGO...HAVE DECIDED TO ADD A PROB30 0205/0209 FOR THIS POTENTIAL. ALSO...A WIND SHIFT IS INDICATED FOR THE KDFW EXTENDED FORECAST AFTER 02/15Z. 75 && .PREV DISCUSSION... /ISSUED 319 AM CDT SUN SEP 1 2013/ NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST TOWARD THE UPPER TEXAS COAST. ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109 AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON. IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM. SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS. MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS. THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS. THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON WHERE THIS FEATURE TRACKS. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 103 79 98 77 98 / 10 30 20 20 10 WACO, TX 102 77 100 75 98 / 10 20 20 20 20 PARIS, TX 101 74 96 71 96 / 10 30 20 10 10 DENTON, TX 103 77 97 72 97 / 10 40 20 10 10 MCKINNEY, TX 102 76 97 73 98 / 10 30 20 10 10 DALLAS, TX 104 80 98 78 99 / 10 30 20 20 10 TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10 CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10 TEMPLE, TX 100 74 98 74 97 / 10 10 20 20 20 MINERAL WELLS, TX 103 74 95 73 96 / 10 40 30 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
616 AM CDT SUN SEP 1 2013 .AVIATION... CONCERNS...ISOLATED TO SCATTERED CONVECTION TONIGHT. FOR THIS FORECAST CYCLE...HAVE DECIDED TO KEEP ALL TAFS VFR. HOWEVER...A CONVECTIVE OUTFLOW BOUNDARY...CURRENTLY MOVING THROUGH CENTRAL OKLAHOMA...IS A CONCERN FOR THE METROPLEX TERMINALS AS IT IS EXPECTED TO MOVE SOUTH OF THE RED RIVER LATER THIS AFTERNOON. THIS BOUNDARY SHOULD BE ABLE TO FIRE ISOLATED TO WIDELY SCATTERED CONVECTION BETWEEN THE RED RIVER AND I-20 MID-LATE AFTERNOON AND OVERNIGHT PER LAST SEVERAL HI- RES RUNS AS WELL AS THE GFS AND NAM SERIES. ERGO...HAVE DECIDED TO ADD A PROB30 0205/0209 FOR THIS POTENTIAL. ALSO...A WIND SHIFT IS INDICATED FOR THE KDFW EXTENDED FORECAST AFTER 02/15Z. 75 && .PREV DISCUSSION... /ISSUED 319 AM CDT SUN SEP 1 2013/ NORTH TEXAS WILL BE UNDERNEATH NORTH-NORTHWEST FLOW THE NEXT FEW DAYS...AS THE UPPER HIGH WILL BE ANCHORED TO THE WEST WITH AN ACTIVE LONGWAVE TROUGH FROM THE MID MISSISSIPPI VALLEY TO THE MID ATLANTIC STATES. THE SHORTWAVE THAT PRODUCED ISOLATED STRONG STORMS ACROSS THE FAR EASTERN COUNTIES SATURDAY WAS MOVING SOUTHWEST TOWARD THE UPPER TEXAS COAST. ONE MORE VERY HOT DAY TODAY WITH HIGHS 100-105 DEGREES ACROSS MUCH OF NORTH TEXAS. CHECK OF RECORDS AT BOTH WACO AND DFW INDICATE RECORD WILL REMAIN INTACT. CURRENT RECORDS ARE 106 AT WACO AND 109 AT DFW. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM THIS EVENING. HOWEVER...SOME CHANGES ARE IN STORE FOR THE AREA. A SHORTWAVE DISTURBANCE ASSOCIATED WITH WEAKENING CONVECTION OVER SOUTHWEST KANSAS WILL DROP SOUTH ACROSS OKLAHOMA THIS AFTERNOON. IN ADDITION...OUTFLOW FROM THE DYING KANSAS COMPLEX WILL HELP SPEED UP THE SOUTHWARD PUSH OF THE COLD FRONT THROUGH OKLAHOMA AND TOWARD THE RED RIVER VALLEY LATE THIS AFTERNOON AND INTO THIS EVENING. THE HRRR IS THE FASTEST WITH THE FRONT/OUTFLOW PER LATEST INDICATIONS... WITH THE NAM NEXT IN LINE AND THE GFS AND TECH WRF MODELS SLIGHTLY SLOWER. SINCE THIS BOUNDARY IS MESOSCALE DRIVEN...WILL LEAN MORE TOWARD A FASTER SOLUTION OF THE HRRR/NAM. SPEED DISCREPANCIES ASIDE...THE FRONT WILL BE ENTERING THE RED RIVER VALLEY RIGHT AT PEAK HEATING. ISOLATED THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTHERN TIER COUNTIES JUST BEFORE 00Z LABOR DAY...THEN MORE SCATTERED ACROSS THE NORTHERN COUNTIES IN THE VICINITY OF THE FRONT IN THE EVENING HOURS. THE 750-500MB RH INCREASES WITH STEEP LOW LEVEL LAPSE RATES IN THE LOWER LEVELS. MID LEVEL INSTABILITY IS NOT EXPECTED TO BE EXTREME DUE TO THE INFLUENCE OF THE EASTERN PERIPHERY OF THE UPPER HIGH. PWAT VALUES WILL BE NEAR 2 STANDARD DEVIATIONS FOR THIS TIME OF YEAR. LOCALIZED MICROBURSTS WITH HEAVY DOWNPOURS WILL BE LIKELY WITH STRONGER ACTIVITY THROUGH NIGHTFALL WITH A WEAKENING TREND AFTER DARK DUE TO THE LOSS OF DAYTIME HEATING. WE HAVE INTRODUCED A SLIGHT CHANCE ACROSS THE NORTHERN COUNTIES FOR LATE AFTERNOON AS THE FRONT ARRIVES INTO THE RED RIVER VALLEY. WITH LIFT FROM THE SHORTWAVE AND THE FRONT ENTERING AREAS NORTH OF I-20...WE HAVE RAISED POPS NORTH OF I-20 THIS EVENING WHILE GENERALLY MAINTAINING BEST CHANCES ACROSS THE WESTERN COUNTIES OVERNIGHT AS A STORM CLUSTER SHIFTS SOUTH THROUGH A HIGHER INSTABILITY AXIS. THE WEAK COLD FRONT SHOULD SHIFT SOUTH OF I-20 BY TUESDAY MORNING WITH INFLUENCE OF STORM-DRIVEN COLD POOL INDICATED BY THE MODELS. THIS IS WHERE CONFIDENCE WANES WITH UNCERTAINTY ON SUCH MESOSCALE DRIVEN FEATURES AND WHERE THEY END UP. FOR NOW HAVE MAINTAIN LOW CONVECTIVE CHANCES FROM THE PREVIOUS FORECAST CONTINGENT ON THE SOUTH-SOUTHWEST PROGRESSION OF THE SHORTWAVE TOWARD THE HILL COUNTRY. A COUPLE OF MODELS INDICATE ANOTHER SUBTLE SHORTWAVE ROTATING AROUND THE UPPER HIGH AND ACROSS CENTRAL AND SOUTHEAST TEXAS LATER ON TUESDAY. HAVE INTRODUCED LOW POPS ACROSS THE CENTRAL TEXAS COUNTIES TO ACCOUNT FOR THIS FEATURE. FOR THE LATTER HALF OF NEXT WEEK...THE UPPER HIGH LOOKS TO EXPAND EAST ACROSS THE SOUTHERN PLAINS ONCE AGAIN AND WILL KEEP BETTER FORCING OFF TO SOUTHEAST. BY NEXT WEEKEND... THERE ARE SIGNS OF THE UPPER HIGH POSSIBLY RETROGRADING WEST AGAIN WITH A WEAK PIECE OF ENERGY DROPPING SOUTHWEST ACROSS THE SABINE RIVER VALLEY. THIS COULD LEAD TO LOW RAIN CHANCES ACROSS THE EASTERN HALF OF NORTH TEXAS ONCE AGAIN BUT WILL LEAVE THE FORECAST DRY WITH LACK OF CONFIDENCE ON WHERE THIS FEATURE TRACKS. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 102 79 98 77 98 / 10 40 20 20 10 WACO, TX 101 77 100 75 98 / 5 20 20 20 20 PARIS, TX 101 74 96 71 96 / 20 30 20 10 10 DENTON, TX 103 77 97 72 97 / 20 40 20 10 10 MCKINNEY, TX 102 76 97 73 98 / 20 40 20 10 10 DALLAS, TX 103 80 98 78 99 / 10 40 20 20 10 TERRELL, TX 102 78 98 75 98 / 10 30 20 20 10 CORSICANA, TX 101 77 100 75 98 / 10 20 20 20 10 TEMPLE, TX 99 74 98 74 97 / 5 10 20 20 20 MINERAL WELLS, TX 102 74 95 73 96 / 10 40 30 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR TXZ103-104-118-119. && $$ 75/
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1004 AM EDT SUN SEP 1 2013 .SYNOPSIS... UPPER AIR DISTURBANCES WILL MOVE EAST ACROSS THE AREA THROUGH MONDAY WITH A COLD FRONT MOVING THROUGH BY TUESDAY. THIS FRONT WILL BRING A DRIER AIRMASS TO THE REGION FOR THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 935 AM EDT SUNDAY... BAND OF SHRA/TSRA APPROACHING FROM THE SW WILL BE PUSHING NE INTO THE FAR WESTERN AREAS AROUND 11 AM...AND THEN LIKELY AID NEW DEVELOPMENT FARTHER EAST AS INSTABILITY INCREASES PER EARLY HEATING. EARLY ARRIVAL OF CONVECTION MAY TEND TO LIMIT THE WESTERN SEVERE THREAT TO SOME DEGREE ESPCLY GIVEN WEAKER WINDS ALOFT OFF MORNING RAOBS AND DEEP MOISTURE TO 6H. HOWEVER LATEST SHORT RANGE GUIDANCE REMAINS VARIED ON LATER TRENDS WITH SOME TAKING BETTER LIFT TO THE SW OF THE AREA WITH THE OLD OUTFLOW UNFOLDING INTO THE TN VALLEY...WHILE THE HRRR BRINGS A SWATH OF SHRA/TSRA EAST ALONG THE RESIDUAL VORT AXIS. THIS LOOKS BEST IN LINE WITH THE CURRENT SCENARIO ESPCLY GIVEN DECENT INSTABILITY OFF MODIFIED RAOBS WEST AND BETTER HEATING EAST WHERE INITIAL LIFT MAY GET WEAKENED SOME VIA DOWNSLOPE. THUS HAVE UPPED POPS TO LIKELYS A BIT SOONER FAR WEST AND EXTENDED EAST TO THE BLUE RIDGE FOR NOW. LEFT CHANCE POPS IN THE EAST FOR LATER DEVELOPMENT ALTHOUGH MAY NEED TO RAISE LATER PENDING TRENDS. KEPT HIGHS A LITTLE COOLER...75-80 OVER THE SW GIVEN EARLIER ARRIVAL OF SHRA...WITH THE EAST PUSHING 90 UNDER WEAK WESTERLY FLOW AND 85H TEMPS OF +18C. PREVIOUS VALID DISCUSSION... HAVE ADJUSTED POPS DOWNWARD EARLY THEN BLEND INTO THE HIGHER POPS BY MIDDAY OVER THE WEST. THINK ANY OUTFLOW AND HIGHER THETA-E ACROSS THE MTNS WILL BE ENOUGH TO GET SHRA/TSRA GOING BEFORE NOON ACROSS SE WV/FAR SW VA. THE 06Z NAM/00Z ECMWF CONTINUE TO ADVERTISE MORE ORGANZIED CONVECTION MOVING FROM NRN KY INTO ERN WV/SHENANDOAH VALLEY OF VA THIS AFTERNOON WITH 6Z GFS SINGLING OUT THE MOUNTAINS OF NC/FAR SW VA. OVERALL KEPT THE LIKELY POPS OVER THE WEST BY EARLY AFTERNOON TAPERING TO SCATTERED EAST OF THE BLUE RIDGE. ANY FOG EARLY WILL BURN OFF BY 10 AM. PREVIOUS DISCUSSION AT 330 AM... EARLY THIS MORNING...SEEING SOME DENSE FOG ACROSS THE AREA RESULTING FROM LACK OF LOWER OR MID CLOUDS AND WET GROUND FROM SATURDAYS RAINS. WILL MAINTAIN SPECIAL WX STATEMENTS FOR THIS...GIVEN THAT WILL SEE UPSTREAM CLOUDINESS ARRIVING THAT MAY CAUSE VSBYS TO FLUCTUATE ENOUGH TO KEEP THE COVERAGE OF DENSE FOG TO A LOCALIZED/PATCHY STATE. HAVE STAYED CLOSER TO THE 00Z GFS SOLUTION THIS PERIOD AS IT WAS HANDLING THE UPPER SHORTWAVE ACROSS OHIO AND STORMS OVER KY THIS MORNING BETTER THAN THE OTHER MODELS. THE LOCAL WRF/HRRR NOT ALL THAT BAD EITHER BUT APPEAR TO BE OVERDOING PRECIP IN THE EAST AS RADAR IS CLEAR. SO FOR TODAY...STILL LOOKS LIKELY THAT SHOWERS AND STORMS WILL IMPACT THE MOUNTAINS BY MIDDAY...THEN SHIFT ENE ACROSS THE REST OF THE AREA THRU THE AFTERNOON. THE FLOW WILL BE SW TO WEST WHICH MAY LIMIT COVERAGE AS WE HEAD DOWNSTREAM OF THE BLUE RIDGE SO LEFT POPS IN THE FOOTHILLS PIEDMONT AREAS TO 30/4O WHILE GOING LIKELY OR HIGH CHANCE WEST. PWATS REMAINING HIGH WILL FAVOR HEAVY RAINERS AS STORM MOTION WILL BE IN THE 10-20 MPH RANGE. SEVERE THREAT WILL BE ISOLATED TO WIND DAMAGE FROM OUTFLOW/DOWNBURSTS. WILL CONTINUE TO MENTION THE RAIN/SVR THREAT IN THE HWO. AS THE WAVE PASSES THIS EVENING...THE CENTRAL/ERN CWA SHOULD SEE DRYING TREND. NEXT UPSTREAM WAVE WILL BE WEAKENING AS IT MOVES FROM KY INTO WV OVERNIGHT...BUT ENOUGH THETA-E/HIGH MOISTURE AHEAD OF THE FRONT TO KEEP HIGHER POPS ACROSS THE SE WV/FAR SW VA AFTER MIDNIGHT BUT ONLY ABOUT 30/40 POPS. WITH MAINLY A MIX OF CLOUDS/SUN TODAY WILL STILL SEE WARM TEMPS IN THE MAV/MET BLEND RANGE FROM UPPER 70S/LOWER 80S MOUNTAINS...TO NEAR 90 PIEDMONT. TONIGHT...MUGGY CONDITIONS REMAIN WITH TEMPS FALLING INTO THE 60S. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 400 AM EDT SATURDAY... LOOKING AHEAD TO MONDAY...THE APPALACHIAN CHAIN WILL BE SITUATED AT THE BASE OF A BROAD UPPER LEVEL TROUGH EXTENDING SOUTHWARD FROM THE GREAT LAKES...RESULTING IN WESTERLY WINDFLOW ACROSS OUR AREA. ASIDE FROM A FEW SHOWERS SPILLING OVER OUR FAR WESTERN RIDGELINES...THIS WEST WIND WILL KEEP A LID ON CONVECTION DURING THE MORNING AND MUCH OF THE AFTERNOON...BEFORE AN UPPER LEVEL DISTURBANCE APPROACHES DURING THE EVENING. CLOUD COVER WILL BE SCATTERED EAST OF THE BLUE RIDGE...MAINLY CONFINED TO MID AND HIGH CLOUDS...AND BELIEVE THE COMBINATION OF THE DOWNSLOPE WIND AND FILTERED SUNSHINE REACHING THE SURFACE WILL BE SUFFICIENT TO ALLOW TEMPERATURES TO REACH INTO THE LOWER 90S IN A FEW AREA OF THE PIEDMONTS. AS MENTIONED...AN UPPER LEVEL DISTURBANCE IS EXPECTED TO MOVE IN FROM THE WEST DURING THE EVENING...INCREASING THE COVERAGE OF SHOWERS AND THUNDERSTORMS ACROSS OUR AREA. INSTABILITY ASSOCIATED WITH THE DISTURBANCE WILL BE SUFFICIENT TO ALLOW A FEW THUNDERSTORMS TO BECOME SEVERE...AND EXPECT THE BIGGER THREAT TO COME IN THE FORM OF DAMAGING WINDS. ATMOSPHERIC MOISTURE WILL REMAIN ABUNDANT...AND EXPECT WE WILL ALSO SEE A FEW STORMS PRODUCE HEAVY RAIN...AND POSSIBLY LOCALIZED FLASH FLOODING. THUNDERSTORM ACTIVITY WILL DECREASE LATE MONDAY NIGHT/EARLY TUESDAY AS THIS DISTURBANCE MOVES EAST. MODELS ARE IN DECENT AGREEMENT THAT AN ASSOCIATED COLD FRONT WILL ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES TUESDAY MORNING...AND CONTINUE SOUTHEAST...EXITING OUR AREA DURING THE AFTERNOON. THE TRULY DRIER AIR IN THE LOW LEVELS WILL LAG A FEW HOURS BEHIND THE FRONT...SO EXPECT WE WILL STILL SEE A COUPLE SHOWERS AND THUNDERSTORMS SOUTH OF INTERSTATE 81 THROUGH SUNSET...AT WHICH POINT INSTABILITY WILL DISAPPEAR. CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BRINGING WITH IT A HINT OF AUTUMN AS TEMPERATURES FOR MID WEEK ARE EXPECTED TO BE SLIGHTLY BELOW NORMAL FOR EARLY SEPTEMBER. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 400 PM EDT SATURDAY... A STRONG RIDGE CONTINUES IN THE WEST...WHILE AMPLIFYING TROUGH ANTICIPATED IN THE EAST. HIGH PRESSURE WILL CONTROL OUR WEATHER PATTERN FOR THURSDAY...RESULTING IN DRY CONDITIONS WITH MOSTLY CLEAR SKIES...OUTSIDE OF EARLY MORNING FOG. ANOTHER COLD FRONT WILL DROP SOUTHEAST ACROSS THE REGION FRIDAY WITH SOME MOISTURE AND INSTABILITY...KEPT THE MENTION OF ISOLATED TO SCATTERED SHOWERS WITH FRONTAL BOUNDARY. ISOLATED AFTERNOON CONVECTION IS POSSIBLE SATURDAY AFTERNOON WITH BEST CHANCES ACROSS THE HIGHER TERRAIN. TEMPERATURES INITIALLY START BELOW NORMAL THEN SLOWLY MODERATE INTO THE WEEKEND. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... AS OF 735 AM EDT SUNDAY... LIFR/VLIFR AT LWB/BCB/LYH AND DAN AT 12Z WILL LIFT TO VFR BY 15Z. WILL SEE SHOWERS/TSRA ARRIVING IN THE BLF/LWB CORRIDOR AROUND MIDDAY THEN NEXT AT BCB AND ROA BY 19Z. KEPT VCTS AT THESE SITES BUT NO MENTION OF IT AT DAN/LYH. ANTICIPATING AT LEAST SOME TIME THIS AFTERNOON THAT THE TAF SITES FROM ROA/BCB TO LWB/BLF WILL SEE A STORM IMPACT THE TERMINAL BUT NOT ENOUGH CONFIDENCE YET TO PIN DOWN THE TIMING. OVERALL VFR EXPECTED TODAY WHILE STORMS COULD DROP HEAVY RAIN/GUSTY WINDS SENDING VSBYS/CIGS TO UNDER VFR. WEAKENING IN THE CONVECTION THIS EVENING WITH FOG AGAIN FORMING OVERNIGHT AT MOST SITES...WITH FOG BECOMING DENSE AT LWB/BCB...AND MAYBE LYH IF IT RAINS NEARBY. TRUE FRONT EXPECTED TO NOT MOVE INTO AND THRU THE CWA UNTIL TUESDAY MORNING...SO MONDAY WILL BE ANOTHER DAY OF SCATTERED CONVECTION WITH THE LAST IN THE UPPER LEVEL SHORTWAVES MOVING ACROSS INTERACTING WITH HUMID SFC CONDITIONS AND LOW LVL CONVERGENCE. ANTICIPATE MORE FOG TUESDAY MORNING WITH DRIER AIR NOSING IN DURING THE DAY TUESDAY. MOSTLY VFR WX EXPECTED THROUGH LATE WEEK OUTSIDE OF ANY OVERNIGHT FOG. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS/WP NEAR TERM...JH/WP SHORT TERM...NF LONG TERM...KK AVIATION...DS/RCS/WP
AREA FORECAST DISCUSSION...CORRECTED
NWS PHOENIX AZ
310 PM MST SUN SEP 1 2013 CORRECTED TYPO .SYNOPSIS... A DECLINE IN MONSOON MOISTURE WILL LEAD TO LOWER HUMIDITY AND SLIGHTLY WARMER TEMPERATURES THAN WHAT HAS BEEN EXPERIENCED IN RECENT DAYS. THERE WILL BE ENOUGH LINGERING MOISTURE AND WEATHER DISTURBANCES TO KEEP AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE REGION THROUGH WEDNESDAY. ANTICIPATE A SLOW EASTWARD RETREAT OF STORM CHANCES THE REST OF THE WEEK. && .DISCUSSION... REST OF TODAY THROUGH MONDAY... WITH LESS MORNING CLOUDINESS AND SOMEWHAT LOWER SURFACE DEW POINTS...24 HOUR TEMP TRENDS EARLY THIS AFTERNOON ARE RUNNING AT LEAST A FEW DEGREES WARMER OVER SOUTH CENTRAL ARIZONA...LITTLE CHANGE FURTHER WEST WHERE THERE WAS MORE STORM ACTIVITY LAST NIGHT. SATELLITE AND RADAR IMAGERY AS OF 21Z SHOWS MEAGER STORM DEVELOPMENT OVER EASTERN ARIZONA WITH ONLY ACTIVITY IN SANTA CRUZ COUNTY. THE NORTHWEST QUARTER OF ARIZONA HAS HAD MOST OF THE STORMS SO FAR. IN OUR FORECAST AREA...LA PAZ COUNTY HAS HAD A STRAY THUNDERSTORM SO FAR. CUMULUS DEVELOPMENT OVER ZONE 24 INDICATES THAT THERE IS STILL SOME MOISTURE TO WORK WITH. GPS IPW DATA TRENDS ARE A MIXED BAG WITH SOME STATIONS SHOWING SOME ADDITIONAL DRYING SINCE THIS MORNING AND SOME OTHERS WITH SOME REVERSAL OF THE DRYING TREND. BUT OVERALL...NOT A LOT OF CHANGE FROM THE MORNING. HRRR MODEL CONTINUES TO SHOW ONLY ISOLATED STORMS OVER SOUTH-CENTRAL ARIZONA THROUGH THIS EVENING...MAINLY OVER ZONE 24...WITH BETTER COVERAGE FURTHER WEST...MAINLY LA PAZ AND EASTERN RIVERSIDE COUNTIES. LATEST RUC/RAP SHOWS A SIMILAR PATTERN BUT IS NOT AS GENEROUS OVER LA PAZ AND EASTERN RIVERSIDE. THE NMM6KM AND LOCAL WRF ARE EVEN LESS GENEROUS WITH STORM ACTIVITY. HOWEVER...THE AFTERNOON IS STILL YOUNG AND THE INFLUENCE OF STORMS OVER NORTHERN SONORA REMAINS TO BE SEEN. NAM APPEARS TO HAVE HAD A BETTER HANDLE ON THE MOISTURE TRENDS FOR TODAY THAN THE GFS AS DEW POINTS HAVENT DROPPED AS MUCH. GFS HAD ALSO UNDERINITIALIZED THE LOWER LEVEL MOISTURE OVER PORTIONS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. MADE SOME MINOR UPWARD TWEAKS TO THE POPS FOR THIS EVENING DUE TO LINGERING MOISTURE AVAILABILITY AND MORE UNSTABLE BOUNDARY LAYERS. ANTICIPATE SOME ADDITIONAL MOISTURE DECLINE TOMORROW AND THUS SOMEWHAT LOWER POPS...BUT NOT ENOUGH TO DROP THEM ALTOGETHER. TUESDAY... TROPICAL STORM KIKO OFF THE SOUTHERN BAJA COAST WILL NOT BE SENDING A BIG SLUG OF TROPICAL MOISTURE INTO OUR FORECAST AREA LIKE JULIETTE DID. HOWEVER...THERE IS AN INVERTED TROUGH/SHORT WAVE ADVERTISED TO MOVE ACROSS NORTHERN MEXICO AND INTO SOUTHEAST ARIZONA TUESDAY NIGHT. THIS WILL LEAD TO SOME UPPER LEVEL DIVERGENCE WHICH WILL BE MORE CONDUCIVE TO STORM DEVELOPMENT. HOWEVER...THE GFS DOESNT DEPICT A SUBSTANTIAL INCREASE IN MOISTURE WITH IT. IT ALSO IS UNCHARACTERISTICALLY MODEST WITH THE DIVERGENCE FIELDS. ECMWF AND NAM ARE A BIT MORE GENEROUS WITH MOISTURE AVAILABILITY. MEANWHILE...THE REMNANT ATMOSPHERIC WAVE ASSOCIATED WITH KIKO MAY ALSO BE A PLAYER...MORE SO FOR SOUTHEAST CALIFORNIA. GFS SHOWS IT MOVING NORTHWARD ACROSS SOUTHERN CALIFORNIA ON TUESDAY GETTING ABSORBED INTO THE MUCH LARGER WEST COAST TROUGH. THERE IS ALSO A JETLET ASSOCIATED WITH THE WAVE WHICH LEADS TO SOME SPEED DIVERGENCE WHICH MIGHT BE A SUBTLE DIFFERENCE MAKER. MADE SOME MODEST UPWARD ADJUSTMENTS BUT INHERENT UNCERTAINTY ABOUT THESE FEATURES AND MOISTURE AVAILABILITY MAKES HIGH POPS UNWARRANTED. WEDNESDAY THROUGH SUNDAY... MODELS ARE FORECASTING A NUMBER OF HARD TO TIME UPPER LEVEL PERTURBATIONS MOVING INTO AZ FROM NORTHWEST MEXICO. THEREFORE A SLIGHT CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ARE WARRANTED. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... 12Z MODELS SUGGESTING CONVECTION SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN SURROUNDING THE PHOENIX METRO AS SLIGHTLY DRIER AIR MOVES INTO THE REGION. STORMS WILL BE ISOLATED IN NATURE BUT I DO NOT ANTICIPATE ANYTHING DIRECTLY AFFECTING THE TERMINALS ASIDE FROM DEBRIS CLOUDS. WINDS SHOULD FAVOR TYPICAL DIURNAL PATTERNS. SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH... CLOUDS ARE CLEARING OUT AND HUMIDITIES REMAIN HIGH AT BOTH TAF SITES...BUT MODELS SUGGESTING CONVECTION SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN AND STAY MOSTLY OUT OF THE LOWER DESERTS. I WILL INCLUDE SOME DEBRIS CLOUDS IN THE TAFS LATER THIS AFTERNOON AND EVENING BUT OTHERWISE NEITHER SITES SHOULD BE DIRECTLY IMPACTED TODAY. WINDS WILL FAVOR THE USUAL DIURNAL TRENDS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... DRIER AIR WILL MOVE INTO THE REGION AS THE WEEK PROGRESSES. WHILE AFTERNOON SHOWERS AND THUNDERSTORMS WILL REMAIN A POSSIBILITY EACH AFTERNOON...STORMS SHOULD BECOME INCREASINGLY CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX...WITH LITTLE TO NO ACTIVITY ACROSS THE DESERTS. HUMIDITIES EACH AFTERNOON WILL DROP INTO THE 15 TO 20 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY ANTICIPATED. WINDS WILL FAVOR THE TYPICAL UPSLOPE/DOWNVALLEY PATTERNS WITH NO MAJOR WIND EVENTS ANTICIPATED. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...AJ/VASQUEZ AVIATION...LEINS FIRE WEATHER...LEINS
AREA FORECAST DISCUSSION
NWS PUEBLO CO
230 PM MDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 226 PM MDT SUN SEP 1 2013 ABUNDANT MOISTURE IS OVER THE AREA TODAY. THE MONSOON PLUME LIES OVERHEAD AND SFC DEW POINTS RANGE FROM THE UPR 40S TO LOWER 60S ACRS MOST OF THE AREA...AND LCL/S ARE LOWER TODAY...ALL LEADING TO A BETTER POTENTIAL FOR HEAVY RAINFALL TODAY. LOW LEVEL UPSLOPE FLOW COULD HELP ENHANCE CONVECTION ALONG AND NR THE MTS AND COULD LEAD TO A TRAINING EFFECT. THE UPR LEVEL FLOW IS NORTHWESTERLY AROUND 15 KTS SO IN GENERAL THE STORMS SHOULD MOVE TOWARD THE SOUTHEAST THIS EVENING. SHOWERS AND TSTMS OVER THE MOUNTAINS EARLY THIS AFTERNOON SHOULD INCREASE IN COVERAGE AND SPREAD TO THE LOWER ELEVATIONS. HOWEVER THE NAM12 AND RAP13 SHOW LITTLE CONVECTION OUT OVR THE SERN PLAINS THIS EVENING AND QUICKLY END PCPN BY MIDNIGHT OVR ALL AREAS EXCEPT ALONG THE CONTDVD. THE HRRR SHOWS A LINE OF CONVECTION MOVING OUT OVR THE SERN PLAINS EARLY IN THE EVENING BUT DOESN/T REALLY MOVE IT PAST LA JUNTA. OVERNIGHT THE MODELS SHOW THE MONSOON MSTR PLUME SHIFTING SOUTH OF THE AREA...AND THEN ON MON THAT PLUME IS EXPECTED TO BE OVR THE MOUNTAIN AREAS...WITH DRIER UPR LEVELS FROM THE I-25 CORRIDOR AND WESTWARD. AT THE LOWER LEVELS DEW POINTS ARE STILL EXPECTED TO REMAIN FAIRLY HIGH...IN THE UPPER 40S AND 50S. LCL/S ARE EXPECTED TO BE A LITTLE HIGHER ON MON. BEST CHANCES FOR PCPN ON MON WL BE OVR THE NR THE MTS...WITH SOME STORMS LIKELY MOVING OUT OVR THE I-25 CORRIDOR...BUT MUCH OF THE REST OF THE PLAINS COULD BE DRY. WE COULD AGAIN SEE SOME LOCALLY HEAVY RAIN ON MON AND IF ANY OF THESE STRONGER STORMS MOVE OVER THE BURN SCARS...THERE WL AGAIN BE THE THREAT OF FLASH FLOODING. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 226 PM MDT SUN SEP 1 2013 UPPER LEVEL HIGH PRESSURE WILL REMAIN CENTERED OVER COLORADO THROUGH AT LEAST FRIDAY. UPPER LOW SLOWLY MOVES ONSHORE IN THE PACIFIC NORTHWEST FRIDAY/SATURDAY TIMEFRAME. MODELS A BIT SLOWER WITH THIS FEATURE THAN RUNS FROM 24 HOURS AGO...LIKELY DUE TO THE BLOCKINESS OF THE PATTERN. THIS DOMINANT RIDGE MEANS A RETURN TO UNSEASONABLY WARM CONDITIONS. THUNDERSTORM CHANCES THROUGH THE WORK WEEK WILL BE PRIMARILY CONFINED TO THE MOUNTAINS AND WEST...ALTHOUGH MODELS HINT AT A SUBTLE UPPER DISTURBANCE MOVING THROUGH THE HIGH PLAINS AND SENDING A WEAK FRONTAL BOUNDARY THROUGH THE EAST CENTRAL PLAINS WEDNESDAY AFTERNOON WHICH COULD TRIGGER SOME CONVECTION ON THE PALMER DIVIDE. LITTLE IN THE WAY OF MID AND UPPER LEVEL MOISTURE THOUGH...SO FLASH FLOOD THREAT WILL BE LOWER. RIDGE GETS FLATTENED AND AXIS SHUNTED OFF TO THE EAST SATURDAY NIGHT AND SUNDAY AS LOW PRESSURE MOVES EAST ALONG THE US/CANADIAN BORDER. COULD SEE A DECENT COLD FRONT MOVE THROUGH THE PLAINS NEXT WEEKEND IF THE MODELS REMAIN CONSISTENT WITH THE TIMING OF THIS SYSTEM. IF SO, COOLER TEMPERATURES AND A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS ARE POSSIBLE SOMETIME NEXT WEEKEND. IN THE MEANTIME, DESPITE TEMPERATURES WARMING TO ABOVE NORMAL LEVELS THIS WEEK...GUIDANCE NUMBERS REMAIN TOO WARM. WILL CONTINUE TREND OF SHAVING A FEW DEGREES OFF GUIDANCE HIGHS. STARK && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 226 PM MDT SUN SEP 1 2013 IN GENERAL...VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS. HOWEVER...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE IN THE EVENING HOURS AT THE TERMINAL SITES AND COULD BRIEFLY BRING REDUCED VSBYS/CIGS. THERE IS ALSO THE POTENTIAL FOR STRATUS DEVELOPMENT NR KCOS LATE TONIGHT. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN MONDAY AFTERNOON...WITH KCOS AND KALS HAVING A BETTER CHANCE THAN KPUB. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...STARK AVIATION...28
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1112 AM MDT SUN SEP 1 2013 .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 431 AM MDT SUN SEP 1 2013 SUBTLE CHANGES IN THE RIDGE POSITIONING LEADS TO A WESTWARD SHIFT OF THE DEEP MONSOONAL MOISTURE PLUME...APPEARS FARTHER WEST THAN WHAT EARLIER MODELS MAY HAVE SHOWN. THE END RESULT IS FOR LESS CONVECTIVE POTENTIAL ACROSS THE DESERT VALLEYS (FROM SE UTAH INTO THE GRAND VALLEY) THIS AFTERNOON. OBJECTIVE ANALYSIS PLACES SUBTROPICAL WAVE WITH DEEP MOIST LAYER ACROSS SRN NEVADA/SWRN UTAH/NWRN ARIZONA WITH A VORTICITY LOBE THAT EXTENDS INTO ERN UTAH. RADAR INDICATING SOME SPOTTY SHOWERS ASSOCIATED WITH THIS ERN UTAH VORT LOBE. RAP AND HRRR MODEL SHOWS THIS FEATURE LIFTING NORTH OVER THE BOOKCLIFFS BY LATE MORNING... ENHANCING CONVECTION OVER THE BOOKCLIFFS THAT EXTENDS INTO WRN COLORADO AS FAR EAST AS INDEPENDENCE PASS. RAP/NAM/GFS MODELS SHOW RIDGE AXIS POSITIONED JUST WEST OF THE COLORADO SPINE AND AMPLIFIES AS THE DAY PROGRESSES. DRIER AIR THAT HAS ADVECTED INTO ERN ARIZONA WILL BE DRAWN NORTHWARD INTO SERN UTAH THIS MORNING...REACHING NW COLORADO LATE THIS AFTERNOON. THIS RIBBON OF MID LEVEL DRIER AIR LIMITS CONVECTIVE POTENTIAL ACROSS THE WRN HALF OF OUR FORECAST AREA. WITH WATER VAPOR LOOP CONFIRMING THIS TREND...CANNOT JUSTIFY THE CONTINUATION OF THE FLASH FLOOD WATCH FOR SOUTHEAST UTAH AS DEEP CONVECTIVE TOWERS WILL NOT SURVIVE THE PROMINENT DRY AIR INTRUSION. DIFFERENT ENVIRONMENT OVER THE COLORADO CENTRAL MOUNTAINS WITH MOISTURE IN PLACE WITH SOME SHEAR IN THE 15-20 KT RANGE...CONVECTION THAT FIRES OVER THE BOOKCLIFFS/ROAN PLATEAU AND FLAT TOP MOUNTAINS WILL TRACK ESE ACROSS EAGLE AND PITKIN COUNTY AND THIS AREA GETS THE HIGHEST POP VALUES FOR THIS AFTERNOON. MODELS REMAIN CONSISTENT LEAVING THE SUB TROPICAL HIGH CIRCULATION TO SPIN OVER CENTRAL NEW MEXICO THROUGH THE NEXT 24 TO 36 HOURS. THIS IS WHERE 00Z HAND ANALYSIS HAS IT LOCATED AS WELL...BUT THE ARIZONA WAVE IS NOT QUITE AS DISTINCT AS 24 HOURS AGO AND A BIT FARTHER WEST. PWAT LOOKS TO PEAK THROUGH THE DAY ACROSS THE WESTERN CWA THEN MODELS SHOW A DECLINING TREND THROUGH THE FIRST OF THE WEEK...BUT STILL ABOVE NORMAL. WITH THE ARIZONA WAVE LIFTING A BIT FARTHER WEST...MOISTURE LOOKS TO GET SPLIT APART BY THIS EVENING. SOME LIFTING WITH THE WAVE AND THE REST WRAPPING TOWARD THE CIRCULATION OVER NEW MEXICO...LEAVING A PSEUDO-DRY SLOT FROM THE 4 CORNERS TO THE NORTHERN MOUNTAINS GOING INTO LABOR DAY. WEAK ASCENT ASSOCIATED WITH THE WAVE TO THE WEST PUSHES ACROSS NORTHERN UTAH AND NORTHWEST COLORADO LATE TONIGHT INTO MONDAY MORNING AND MAY HELP FOCUS CONVECTION DURING THE TIME. MOISTURE ALSO POOLS NEAR THE SOUTHERN MOUNTAINS SO THESE TWO AREAS SHOULD HAVE THE BEST CHANCES FOR PRECIPITATION WHILE IN BETWEEN CONFIDENCE IS LOWER. UPPER FLOW NOT IMPRESSIVE BUT STORM MOTION TO THE NORTH SHOULD BE MORE APPARENT THAN THE PAST FEW DAYS AND MAY HELP ALLEVIATE SOME OF THE FLOODING POTENTIAL. LOCALLY HEAVY RAIN STILL POSSIBLE WITH WARM CLOUD RAIN PROCESSES STILL IN PLACE. EXPECT A BIT MORE SUNSHINE ON MONDAY SO PUSHED TEMPS UP A FEW DEGREES MANY AREAS CLOSER TO THE MAV GUIDANCE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 431 AM MDT SUN SEP 1 2013 SHOULD BE A BIT OF DOWNTURN TO THE CONVECTION OVER THE NORTHWEST 2/3 OF THE CWA AS THE UPPER HIGH WOBBLES TO THE NORTHWEST. THIS WILL LEAVE THE 4 CORNERS TO THE CENTRAL MOUNTAINS UNDER THE CIRCULATION WHERE RESIDUAL MOISTURE WILL BE POOLING. THEREFORE REFOCUSED THE HIGH POPS TO OUR SOUTHERN CWA TAPERING OFF TO THE NORTH. HIGH NOT CHANGING MUCH AND SHOULD REMAIN ABOVE NORMAL MOST AREAS. TUESDAY THROUGH SATURDAY...HIGH PRESSURE WILL BE ANCHORED OVER THE COLORADO ROCKIES. MONSOONAL MOISTURE PLUME WILL BE WEST OF OUR FORECAST AREA. SOME MONSOONAL MOISTURE WILL BE TRAPPED BENEATH THE HIGH CORE TO ALLOW FOR DAILY SHOWERS AND THUNDERSTORMS. WITH SHEAR ESSENTIALLY NON EXISTENT...MOST STORMS WILL STAY PUT OVER THE MOUNTAINS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1110 AM MDT SUN SEP 1 2013 SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS THIS AFTERNOON...ESPECIALLY TOWARD THE CONTINENTAL DIVIDE WHERE MOUNTAIN PEAKS AND RIDGE TOPS WILL BE OBSCURED FROM RAIN SHAFTS AND LOW CIGS. FARTHER WEST OVER THE LOWER DESERT VALLEYS...AREAL COVERAGE OF -SHRA/-TSRA WILL BE ISOLATED. SHOWERS AND STORMS DIMINISH AFTER 02Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...PF/15 LONG TERM...15/PF AVIATION...JDC
AREA FORECAST DISCUSSION
NWS ALBANY NY
155 PM EDT SUN SEP 1 2013 .SYNOPSIS... A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 110 PM EDT...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW A GOOD DEAL OF CLOUDINESS AROUND THE REGION EARLY THIS AFTERNOON. A DIFFUSE SFC FRONTAL BOUNDARY REMAINS SITUATED NEAR THE FAR SOUTHEASTERN CORNER OF THE CWA. SHOWER AND THUNDERSTORM ACTIVITY HAS INCREASED ACROSS MAINLY ULSTER...DUTCHESS AND LITCHFIELD COUNTIES SO RAISED POPS TO LIKELY IN THESE AREA. SPC RAP ANALYSIS SHOW A DECENT INSTABILITY GRADIENT ACROSS THE AREA WITH ONLY AROUND 500 J/KG OF CAPE ACROSS THE ADIRONDACKS...WITH AROUND 2000 J/KG SOUTH AND EAST OF ALBANY. THE MOST UNSTABLE AREA COINCIDES WITH WHERE THE SURFACE BOUNDARY IS...THUS THE HIGHER POPS. LOWERED TO SLIGHT CHANCE FOR MUCH OF THE WESTERN/SOUTHERN ADIRONDACKS DUE TO LACK OF FORCING. THE DIFFUSE FRONTAL BOUNDARY WILL CREEP BACK NORTHWARD DURING THE THE REST OF THE DAYLIGHT HOURS...WITH POP-UP SHOWERS AND THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE ESPECIALLY SOUTH AND EAST OF ALBANY. THE COVERAGE AREA SHOULD BE A LITTLE LESS THAN YESTERDAY...WITH THE MOST ACTIVITY FOR SOUTHERN AREAS CLOSER TO THE BOUNDARY. THE PWAT VALUE ON THE 12Z KALY SOUNDING WAS 1.52 INCHES...WHICH IS SLIGHTLY ABOVE NORMAL...SO ANY THUNDERSTORM WILL BE CAPABLE OF PRODUCING HEAVY DOWNPOURS IN A SHORT PERIOD OF TIME. ENHANCED WORDING IN THE GRIDS AND HWO PRODUCT WAS CONTINUED FOR HEAVY RAINFALL WITH ANY CONVECTION TODAY FOR SOUTHEASTERN PARTS OF THE AREA...WHICH WILL HAVE BETTER COVERAGE DUE TO BEING MORE CLOSELY LOCATED TO THE SFC FRONTAL BOUNDARY. THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN THE 500-1000 J/KG WITH POCKETS OF 1500-2000 J/KG SOUTH OF THE CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S. THE PROJECTED VALUE FOR THIS AFTN BASED ON THE 12Z KALY SOUNDING WAS AROUND 1085 J/KG. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED CONVECTION. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS. LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY. PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM 500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO 25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE MONITORED. OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND U60S TO M70S OVER THE HIGH PEAKS. MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES. TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH SOME U40S OVER THE MTNS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD. WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5 DEGREES BELOW NORMAL. TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP. HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW PASSES TO OUR NORTH. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... A FRONTAL BOUNDARY IS SITUATED JUST TO THE SOUTH OF THE REGION...ALLOWING FOR SOME SCT SHOWERS AND THUNDERSTORMS NEAR KPOU. WITHIN ANY SHOWER OR TSTM...A BRIEF PERIOD OF IFR CONDITIONS IS POSSIBLE. FURTHER NORTH...KALB/KPSF/KGFL LOOK QUIET FOR THE NEXT FEW HOURS WITH VFR OR HIGH END MVFR CIGS...BUT THE THREAT FOR SHOWERS/STORMS WILL RETURN TO THESE SITES FOR THE EVENING AS THE FRONTAL BOUNDARY BEGINS TO LIFT BACK NORTHWARD. SFC WINDS LOOK VERY LIGHT...GENERALLY 5 KTS OR LESS THROUGH THE EVENING. TONIGHT INTO MONDAY MORNING...ADDITIONAL SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE REGION AS A SLOW MOVING COLD FRONT AND ASSOCIATED UPPER TROUGH APPROACH THE AREA. THIS WILL ALLOW FOR MVFR CONDITIONS AND POSSIBLE PERIODS OF IFR AS WELL WITHIN SHOWERS...POSSIBLE THUNDERSTORMS AND LOW CLOUDS. WINDS WILL BE NEARLY CALM OVERNIGHT...BECOMING SOUTHERLY ON MONDAY AT 5-10 KTS. SOME IMPROVEMENT IN FLYING CONDITIONS MAY OCCUR TOWARDS MIDDAY MONDAY...ESP FOR THE VALLEY TERMINALS. OUTLOOK... MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO TUESDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT. EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY. LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON SATURDAY AND THIS MORNING. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY. RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3 INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE TO MONITORED FOR ANY HYDRO ISSUES. COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .CLIMATE... THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND PITTSFIELD. THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949. THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS. PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013 AND THE SUMMER. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...FRUGIS/JPV/WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...FRUGIS FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
110 PM EDT SUN SEP 1 2013 .SYNOPSIS... A PERSISTENT WARM AND HUMID AIR MASS FOR THE FIRST DAY OF SEPTEMBER WILL REMAIN OVER THE REGION THROUGH LABOR DAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 110 PM EDT...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW A GOOD DEAL OF CLOUDINESS AROUND THE REGION EARLY THIS AFTERNOON. A DIFFUSE SFC FRONTAL BOUNDARY REMAINS SITUATED NEAR THE FAR SOUTHEASTERN CORNER OF THE CWA. SHOWER AND THUNDERSTORM ACTIVITY HAS INCREASED ACROSS MAINLY ULSTER...DUTCHESS AND LITCHFIELD COUNTIES SO RAISED POPS TO LIKELY IN THESE AREA. SPC RAP ANALYSIS SHOW A DECENT INSTABILITY GRADIENT ACROSS THE AREA WITH ONLY AROUND 500 J/KG OF CAPE ACROSS THE ADIRONDACKS...WITH AROUND 2000 J/KG SOUTH AND EAST OF ALBANY. THE MOST UNSTABLE AREA COINCIDES WITH WHERE THE SURFACE BOUNDARY IS...THUS THE HIGHER POPS. LOWERED TO SLIGHT CHANCE FOR MUCH OF THE WESTERN/SOUTHERN ADIRONDACKS DUE TO LACK OF FORCING. THE DIFFUSE FRONTAL BOUNDARY WILL CREEP BACK NORTHWARD DURING THE THE REST OF THE DAYLIGHT HOURS...WITH POP-UP SHOWERS AND THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE ESPECIALLY SOUTH AND EAST OF ALBANY. THE COVERAGE AREA SHOULD BE A LITTLE LESS THAN YESTERDAY...WITH THE MOST ACTIVITY FOR SOUTHERN AREAS CLOSER TO THE BOUNDARY. THE PWAT VALUE ON THE 12Z KALY SOUNDING WAS 1.52 INCHES...WHICH IS SLIGHTLY ABOVE NORMAL...SO ANY THUNDERSTORM WILL BE CAPABLE OF PRODUCING HEAVY DOWNPOURS IN A SHORT PERIOD OF TIME. ENHANCED WORDING IN THE GRIDS AND HWO PRODUCT WAS CONTINUED FOR HEAVY RAINFALL WITH ANY CONVECTION TODAY FOR SOUTHEASTERN PARTS OF THE AREA...WHICH WILL HAVE BETTER COVERAGE DUE TO BEING MORE CLOSELY LOCATED TO THE SFC FRONTAL BOUNDARY. THE SBCAPE VALUES FROM BOTH THE GFS AND NAM ARE A BIT LOWER TODAY IN THE 500-1000 J/KG WITH POCKETS OF 1500-2000 J/KG SOUTH OF THE CAPITAL DISTRICT WHERE THE SFC DEWPTS WILL BE IN THE U60S TO L70S. THE PROJECTED VALUE FOR THIS AFTN BASED ON THE 12Z KALY SOUNDING WAS AROUND 1085 J/KG. NOT ANTICIPATING ANY SEVERE WEATHER AGAIN WITH WEAK MID LEVEL LAPSE RATES AND WEAK DEEP SHEAR PREVENTING ANY DEEP WELL ORGANIZED CONVECTION. H850 TEMPS IN THE +15C TO +17C RANGE WITH SOME SUNSHINE FOR A FEW HOURS WILL ALLOW TEMPS TO GET IN THE M70S TO M80S ACROSS THE FCST AREA. THE NRN ZONES MAY ACTUALLY HAVE MORE SUNSHINE TODAY...SINCE THE WEAK BOUNDARY WILL BE ACROSS THE SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT...A STRONG UPPER LEVEL LOW WILL BE CHURNING EASTWARD FROM THE UPPER GREAT LAKES REGION AND ONTARIO. THE LARGE SFC TROUGH OF LOW PRESSURE WILL BE MOVING TOWARDS THE NORTHEAST. ONE SHORT-WAVE ASSOCIATED WITH THE SYSTEM IN THE SOUTHWEST FLOW ALOFT WILL IMPACT THE REGION SHORTLY BEFORE OR JUST AFTER MIDNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS...OR EVEN A DEVELOPING STRATIFORM RAIN SHIELD. THE QG LIFT STRENGTHENS BTWN 06Z-12Z DUE TO THE DIFFERENTIAL CYCLONIC VORTICITY ADVECTION AND WEAK THERMAL ADVECTION. THE RAIN INTENSIFIES DUE TO A PLUME OF UPPER LEVEL DIVERGENCE MOVING OVER ERN NY. POPS WERE KEPT IN THE LIKELY OR LOW-CATEGORICAL RANGE. MIN TEMPS WILL BE OF THE WET BULB VARIETY IN THE M60S TO NEAR 70F WITH SOME L60S OVER THE MTNS. LABOR DAY...THE LEAD SHORT-WAVE CROSSES THE REGION IN THE MORNING/EARLY PM. THE RAINFALL COULD INCREASE IN INTENSITY AGAIN IN THE EARLY TO MID PM...AS PORTIONS OF ERN NY WILL BE NEAR THE RIGHT ENTRANCE REGION OF A 60-70 KT H250 JET STREAK. ALSO...SOME BREAKS IN THE CLOUDS COULD ALLOW FOR ENOUGH DESTABILIZATION FOR SOME STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. THIS SET-UP IS STILL A BIT NEBULOUS...BUT A STRONG COLD FRONT WILL BE APPROACHING IN THE MID TO LATE PM. STRONG CONVERGENCE IS EXPECTED WITH THE BOUNDARY. PLENTY OF LOW-LEVEL MOISTURE WILL BE IN PLACE WITH PWATS STILL A COUPLE OF STD DEVS ABOVE NORMAL. SBCAPES VALUES MAY RANGE FROM 500-1500 J/KG WITH THE 0-6 KM BULK SHEAR VALUES RAMPING UP TO 25-35 KTS. THE SEE TEXT FROM SPC LOOKS FINE...BECAUSE THE SEVERE POTENTIAL WILL BE CONDITIONAL TO THE AMOUNT OF SFC HEATING THAT OCCURS...AND THE TIMING OF THESE IMPULSES ROTATING AROUND THE UPPER LEVEL LOW. THE MID LEVEL LAPSE RATES STILL DON/T FALL TO 6.5 C/KM OR LOWER UNTIL AFTER DARK. HEAVY RAINFALL LOOKS LIKE A GOOD BET WITH A WIDESPREAD HALF AN INCH TO AN INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS TO 2 INCHES. WIDESPREAD FLASH FLOODING DOES NOT LOOK LIKELY AT THIS TIME...BUT THE POSSIBILITY WILL CONTINUE TO BE MONITORED. OUR FORECAST REFLECTS MAX TEMPS CLOSER TO THE COOLER NAM MOS VALUES FOR THE HOLIDAY WITH U70S TO L80S IN THE VALLEYS...AND U60S TO M70S OVER THE HIGH PEAKS. MON NIGHT...THE SHOWERS AND THUNDERSTORMS WILL END WITH THE PASSAGE OF THE FIRST COLD FRONT. THE BETTER COLD ADVECTION DOES NOT ARRIVE UNTIL AFTER DAY BREAK. LOWS WILL RANGE FROM THE MID AND U50S OVER THE NW ZONES TO LOWER TO M60S OVER THE SE ZONES. TUE-TUE NIGHT...MUCH COOLER AIR INVADES THE FCST AREA...AS THE HUMIDITY BREAKS. THE UPPER LEVEL TROUGH AXIS...AND A SECONDARY COLD FRONT MOVE THROUGH DURING THE DAY WITH ISOLD-SCT SHOWERS POSSIBLE BASED ON THE NAM/GFS/ECMWF/CANADIAN GUIDANCE. H850 TEMPS FALL TO AROUND +10C NEAR THE CAPITAL REGION. THE COLD POOL WILL HELP FOCUS INSTABILITY SHOWERS. MAX TEMPS WILL BE IN THE MID 70S TO L80S IN THE VALLEYS...WITH M60S TO M70S OVER THE MTNS. LOWS WILL COOL OFF INTO THE 50S FOR MOST OF THE REGION TUE NIGHT...WITH SOME U40S OVER THE MTNS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE NORTHEAST WILL REMAIN UNDER A LONGWAVE TROUGH FOR THE PERIOD. WE ARE LOOKING FOR PLEASANT DAY WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLY WARM TEMPERATURES. A COLD FRONT IS FORECAST TO MOVE ACROSS THE REGION WEDNESDAY NIGHT INTO THURSDAY USHERING IN A MORE AUTUMN-LIKE AIRMASS AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE. AN INCREASE CLOUDS ALONG WITH ISOLATED SHOWERS SHOULD ACCOMPANY THE BOUNDARY. TEMPERATURES THURSDAY AND FRIDAY SHOULD RUN ABOUT 5 DEGREES BELOW NORMAL. TEMPERATURES ARE ANTICIPATED TO MODERATE BACK TO SEASONABLE LEVELS FOR THE START OF THE WEEKEND AS THE SURFACE HIGH SHIFTS TO OUR SOUTHEAST ALLOWING A SOUTH-SOUTHWEST FLOW TO DEVELOP. HOWEVER...THERE ARE MODEL DIFFERENCES DEALING WITH THE TIMING AND STRENGTH OF INDIVIDUALS SHORT WAVE ROTATING ABOUT AN UPPER LOW OVER EASTERN CANADA. THIS WILL IMPACT THE TIMING OF FRONTAL BOUNDARIES ACROSS THE REGION NEXT WEEKEND. AT THIS TIME...IT APPEARS A WARM FRONT SHOULD MOVE INTO/THROUGH THE REGION ON SATURDAY AS A LOW PASSES TO OUR NORTH. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... A MUGGY AIRMASS IS IN PLACE WITH A STALLED BOUNDARY ACROSS THE REGION. GUIDANCE INDICATES THE FRONTAL BOUNDARY WILL WEAKEN AND DISSIPATE TODAY. ISOLATED SHOWERS/THUNDERSTORMS HAVE RECENTLY DEVELOPED TO THE EAST OF KPOU IN MORE UNSTABLE AIR TO THE SOUTH AND EAST OF THE BOUNDARY. OVERALL THE LULL IN THE CONVECTION IS EXPECTED TO CONTINUE ACROSS THE LOCAL AREA INTO THIS AFTERNOON AS SOME WEAK WEAK RIDGING OCCUR EARLY TODAY. CHANCES FOR STORMS WILL INCREASE BY MID TO LATE AFTERNOON AND WITH NUMEROUS STORMS TONIGHT AS A STRONGER SHORT WAVE APPROACHES AND HEIGHT FALLS ACROSS THE REGION. MVFR TO LIFR CONDITIONS WILL IMPROVE TO VFR BY MID/LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED THROUGH MUCH OF THE DAY WITH CONDITIONS LOWERING AS WE HEAD THROUGH THE EVENING AND CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE. IFR CONDITIONS ARE EXPECTED TO DEVELOP AT KGFL AND KPSF LATE TONIGHT WITH MVFR CONDITIONS PERSISTING AT KPOU AND KALB. A LIGHT SOUTH-SOUTHWEST FLOW IS EXPECTED TO DEVELOP DURING THE DAY SUNDAY WITH LIGHT AND VARIABLE TO CALM WINDS EXPECTED AGAIN SUNDAY NIGHT. OUTLOOK... MON NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. TUE-WED: NO OPERATIONAL IMPACT. NO SIG WX. WED NIGHT-THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER ISSUES ARE EXPECTED THE NEXT SEVERAL DAYS. A HUMID AIR MASS WITH SEVERAL CHANCES OF RAINFALL WILL BE POSSIBLE INTO TUESDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM ALONG A WEAK BOUNDARY TODAY. THE UNSETTLED WEATHER CONTINUES TONIGHT INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO EASTERN NEW YORK AND WESTERN NEW ENGLAND WITH SOME LOCALLY HEAVY RAINFALL. HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR THIS AFTERNOON. THE RH VALUES WILL RECOVER CLOSE TO 100 PERCENT MONDAY MORNING...AND REMAIN HIGH IN THE AFTERNOON AT 65 TO 85 PERCENT. EXPECT WINDS FROM THE SOUTHEAST OR SOUTH AT 5 TO 15 MPH TODAY. LIGHT AND VARIABLE WINDS WILL OCCUR TONIGHT. SOUTH OR SOUTHWEST WINDS OF 5 TO 15 MPH ARE FORECAST FOR LABOR DAY. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS WITH LOCALIZED OR ISOLATED FLASH FLOODING POSSIBLE. THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TONIGHT AND ON LABOR DAY. HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE EXPECTED WITH THUNDERSTORMS. SOME LOCATIONS COULD GET A QUICK FEW INCHES OF RAINFALL IN 3 HOURS OR LESS...AS WHAT OCCURRED ON SATURDAY AND THIS MORNING. ISOLATED URBAN...SMALL STREAM...AND POOR DRAINAGE FLOODING WILL BE POSSIBLE THE REMAINDER OF THE HOLIDAY WEEKEND. SOME SUBSTANTIAL WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE ISOLATED FLASH FLOODING TODAY INTO LABOR DAY. IF THE POTENTIAL FOR WIDESPREAD FLASH FLOODING INCREASES...THEN A FLASH FLOOD WATCH MAY BE NEEDED FOR PARTS OF THE HYDRO SERVICE AREA TONIGHT INTO LABOR DAY. RAINFALL AMOUNTS WILL CONTINUE TO BE QUITE VARIABLE DUE TO WHERE THE CONVECTION DEVELOPS AND MOVES. SOME LOCATIONS RECEIVED 1 TO 3 INCHES OF RAINFALL YESTERDAY INTO THIS MORNING /SRN TACONICS...NW CT...SRN BERKSHIRES...HELDERBERGS AND PORTIONS OF ALY CTY/. THE SOILS ARE BIT MORE SATURATED IN THESE AREAS...AND THEY WILL HAVE TO MONITORED FOR ANY HYDRO ISSUES. COOLER AND DRIER WEATHER WILL MOVE BACK INTO THE HSA FOR THE MID WEEK ALLOWING STREAMS AND RIVERS TO RECEDE FROM THE RAINFALL. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .CLIMATE... THE AVERAGE MONTHLY TEMPERATURES FOR AUGUST 2013 CAME IN BELOW NORMAL FOR ALBANY...GLENS FALLS...POUGHKEEPSIE...BENNINGTON AND PITTSFIELD. THE METEOROLOGICAL SUMMER FOR 2013 COMES IN AT THE 7TH WETTEST FOR ALBANY SINCE 1826 AND THE 4TH WETTEST FOR POUGHKEEPSIE SINCE 1949. THE AVERAGE TEMPERATURES FOR THE SUMMER WERE AROUND 1.5 DEGREES ABOVE NORMAL FOR ALL 5 CLIMATE LOCATIONS. PLEASE REFER TO OUR FACEBOOK POSTS OR TWEETS SUMMARIZING AUGUST 2013 AND THE SUMMER. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...FRUGIS/JPV/WASULA SHORT TERM...WASULA LONG TERM...IAA AVIATION...IAA/FRUGIS FIRE WEATHER...WASULA HYDROLOGY...SND/WASULA CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
207 PM EDT SUN SEP 1 2013 .SHORT TERM... ISOLATED SHOWERS ARE DEVELOPING ACROSS NE FL AND BECOMING MORE SCATTERED NEAR THE I-75 CORRIDOR IN THE MOIST SWLY FLOW OFF THE GULF OF MEXICO. AS TEMPS CLIMB TO NEAR 90...STORMS ARE BEGINNING TO PRODUCE LIGHTNING. THE ACTIVITY WILL PUSH TOWARD THE EAST COAST AND COLLIDE WITH THE SEA BREEZE THAT IS CURRENTLY PINNED TO THE COAST. HI-RES MODELS INDICATE AN INCREASE IN COVERAGE AFTER 3 PM THEN FADE AFTER SUNSET. THESE MODELS AND HRRR INDICATE STORMS WILL DRIFT BACK INLAND BETWEEN I-95 AND HWY 301 INTO THE EVENING HOURS. SHOWERS WILL DEVELOP OVER THE OUTER WATERS AFTER MIDNIGHT AND A FEW MAY MOVE ONSHORE FROM THE GULF IN THE PRE-DAWN HOURS. FAIR SKIES WITH LOW TEMPS IN THE 70-75 RANGE INLAND AND UPPER 70S COAST ARE EXPECTED. .MONDAY THROUGH WEDNESDAY...EASTERN U.S. UPPER TROUGHING WILL AMPLIFY AGAIN AND BRING A COLD FRONT INTO SE GA BY WEDNESDAY BEFORE WASHING OUT. SCATTERED AFTERNOON/EVENING THUNDERSTORMS AND HOT HUMID CONDITIONS WILL CONTINUE. CONVECTION WILL INCREASE AND REACH THE EAST COAST LATE IN THE DAY DUE TO W TO SW STEERING FLOW. .LONG TERM...THURSDAY THROUGH SUNDAY...FAIRLY WEAK FLOW AND MOIST UNSTABLE AIRMASS WILL RESULT IN DIURNAL SEABREEZE THUNDERSTORMS EACH DAY. TEMPERATURES WILL REMAIN A FEW DEGREES ABOVE AVERAGE WITH NEAR CLIMO POPS. .AVIATION... PREVAILING VFR IS EXPECTED. HAVE VCSH OR VCTS FOR REMAINDER OF AFTN. MVFR CONDITIONS ARE EXPECTED BETWEEN 08Z AND 14Z AT GNV AND VQQ. && .MARINE... SOUTHWEST FLOW TO CONTINUE THE NEXT FEW DAYS. NOCTURNAL WIND SURGE OFFSHORE MAY APPROACH SCEC CONDITIONS. SEAS WILL REMAIN 2 TO 3 FEET. OFFSHORE STEERING FLOW WILL PUSH STORMS INTO THE COASTAL WATERS DURING THE LATE AFTERNOON AND EARLY EVENING. RIP CURRENTS: LOW RISK THROUGH MONDAY DUE TO OFFSHORE WINDS. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 94 72 94 / 20 40 40 40 SSI 76 92 75 92 / 20 50 50 30 JAX 72 94 72 94 / 30 40 40 40 SGJ 74 91 73 92 / 30 30 30 30 GNV 71 93 71 93 / 20 40 20 30 OCF 71 93 71 94 / 20 30 10 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ TRABERT/ZIBURA/MCALLISTER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
203 PM EDT SUN SEP 1 2013 .PREV DISCUSSION... /ISSUED 1221 PM EDT SUN SEP 1 2013/ UPDATE... HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION OVER NORTH GA. WHILE IT IS SHOWING A LULL AS THE OUTFLOW FROM MCS INTERACTS WITH INSTABILITY...CAPES 1500-2000 ACROSS PORTIONS OF WEST AND CENTRAL GA. CURRENT THINKING AS AREA OVER NORTH GA WILL TRANSITION SOUTHWARD WITHOUT THE LULL AND HAVE ADJUSTED POP/WEATHER TRENDS ACCORDINGLY. OTHERWISE CURRENT FORECAST TRENDS PRETTY MUCH ON TRACK EXCEPT FOR MAX TEMPERATURES IN PORTIONS OF NORTH GA WHICH WERE ALSO TWEAKED. UPDATED FORECAST PRODUCTS WILL BE ISSUED SHORTLY. PREV DISCUSSION... /ISSUED 746 AM EDT SUN SEP 1 2013/ UPDATE... HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS. PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/ SHORT TERM /TODAY THROUGH MONDAY/... HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT SHOULD BEGIN TO BURN OFF AFTER SUNRISE. THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/ THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR OUTPUT. MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN. THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED DEVELOP...POPS MAY HAVE TO BE RAISED. FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION... LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS. NLISTEMAA LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO... TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE AREA ON SATURDAY. AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE COOLEST DAY OF THE PERIOD. TDP && .AVIATION... 18Z UPDATE... LINE OF CONVECTION DEVELOPING OVER THE ATL TO AHN TAF SITES WILL SLOWLY SINK TO THE SOUTH THROUGH THIS EVENING. ANTICIPATE STORMS WILL BE SOUTH OF ATL AFTER 20Z AND IMPACT CSG/MCN 20-24Z. VFR CONDITIONS EXPECTED OUTSIDE OF CONVECTION WITH MVFR AND WIND GUSTS TO NEAR 30KTS EXPECTED. LOW CLOUDS WILL DEVELOP TOWARD MORNING AIDED BY THE SATURATED GROUND WITH IFR/LOW MVFR CIGS EXPECTED AT THIS TIME. WEST WINDS WILL PREVAIL THROUGH THE PERIOD. //ATL CONFIDENCE...18Z UPDATE... HIGH CONFIDENCE IN WINDS...VISIBILITY. MEDIUM CONFIDENCE IN CIGS OVERNIGHT...CONVECTIVE TIMING. ATWELL && .PRELIMINARY POINT TEMPS/POPS... ATHENS 90 70 90 72 / 60 40 40 30 ATLANTA 89 73 90 74 / 60 40 40 40 BLAIRSVILLE 83 66 84 68 / 60 30 60 40 CARTERSVILLE 89 71 89 71 / 60 40 40 40 COLUMBUS 92 75 93 74 / 60 50 40 30 GAINESVILLE 88 69 88 73 / 60 40 40 40 MACON 91 71 91 72 / 60 50 40 30 ROME 88 70 90 72 / 60 30 60 40 PEACHTREE CITY 90 69 90 71 / 60 40 40 30 VIDALIA 91 74 93 74 / 50 40 40 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ATWELL LONG TERM....30 AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
154 PM EDT SUN SEP 1 2013 .SYNOPSIS... WEAK ATLANTIC HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH MONDAY. A COLD FRONT WILL PUSH THROUGH TUESDAY NIGHT AND WEDNESDAY WITH WEAK CANADIAN HIGH PRESSURE BUILDING IN FROM THE NORTH. THE HIGH WILL SHIFT OFF THE COAST LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... EARLY THIS AFTERNOON...ISOLATED SHOWERS ARE STARTING TO DEVELOP MAINLY UPSTREAM ACROSS THE MIDLANDS WITHIN THE SURFACE TROUGH. A COUPLE OF SHOWERS HAVE ALSO STARTED TO BUBBLE OVER SOUTHEAST GEORGIA. THERE IS NO CHANGE IN THE FORECAST THINKING FOR CONVECTIVE ACTIVITY THIS AFTERNOON/EVENING. PREVIOUS DISCUSSION FOLLOWS BELOW. LATE THIS MORNING...THE LACK OF ANY FOG/STRATUS HAS RESULTED IN CLEAR SKIES ACROSS THE FORECAST AREA. THIS IS ALLOWING TEMPS TO WARM QUITE RAPIDLY AND SOME AREAS ALREADY IN THE MID 80S. A CU FIELD SHOULD START DEVELOPING VERY SOON AND WILL ENCOMPASS THE ENTIRE FORECAST AREA. THE MAIN FORECAST ISSUE FOR TODAY REVOLVES AROUND THE COVERAGE AND INTENSITY OF DIURNAL CONVECTION. THE MODELS ACROSS THE SPECTRUM ARE SENDING MIXED SIGNALS. SOME OF THE HI-RES RUNS SUCH AS THE HRRR SHOW LITTLE MORE THAN ISOLATED WEAK CONVECTION. ON THE OTHER HAND...THE 12Z NAM HAS COME IN WITH AN UPWARD TREND IN ITS COVERAGE AND INTENSITY. CURRENTLY...THERE IS A WELL DEFINED AREA OF NVA ALOFT NOTED ON WATER VAPOR IMAGERY IN ADVANCE OF THE POTENT SHORTWAVE DRIVING ONGOING CONVECTION OVER THE TENNESSEE VALLEY. THIS NVA WILL LIKELY HANG ON UNTIL LATE IN THE AFTERNOON BEFORE THE UPSTREAM ENERGY DISRUPTS IT. ANOTHER INTERESTING NOTE CONCERNS THE THERMODYNAMIC PARAMETERS FROM THE MODIFIED 12Z RAOB. USING A TEMP/DP OF SOMETHING AROUND 92/73 RESULTS IN CAPE VALUES AROUND 3000 J/KG...WITH DCAPES GREATER THAN 1000 J/KG THANKS TO A GOOD DEAL OF DRY MID LEVEL AIR. THE MAIN SOURCE OF LOW LEVEL CONVERGENCE WILL BE THE SEA BREEZE...THE BEST CONSENSUS SEEMS TO FAVOR ISOLATED TO SCATTERED COVERAGE IN THE MID/LATE AFTERNOON HOURS. GIVEN THE NEAR STORM ENVIRONMENT...THIS SEEMS TO BE A DAY WITH LIMITED COVERAGE BUT THE POTENTIAL FOR A COUPLE STRONG TO SEVERE STORMS DEPENDING ON HOW THE SEA BREEZE AND OUTFLOW BOUNDARIES INTERACT. AS I SAID EARLIER...TEMPS ARE RISING QUICKLY AND WITH INCREASED LOW LEVEL THICKNESSES...HIGHS WILL BE IN THE LOW 90S. SUCH VALUES WILL RUN ABOUT 4-5 DEGREES ABOVE CLIMO FOR EARLY SEPTEMBER. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... TONIGHT...MOST AREAS LIKELY TO SEE DRY WEATHER. THE AREA WHERE SOME ISOLATED NOCTURNAL CONVECTION MAY CROP UP OVERNIGHT COULD BE IN THE SAME AREAS BORDERING THE MIDLANDS AND PEE DEE WHERE A BIT MORE MID LEVEL TROFFINESS IS NOTED. COASTAL AREAS WILL KEEP A SLIGHT SW BREEZE GOING OVERNIGHT AS PATTERN IS FAVORABLE FOR NOCTURNAL JETTING ALONG THE SOUTH CAROLINA COAST. A BROAD UPPER TROUGH WILL SIT OVER THE AREA ON MONDAY WITH SUBSTANTIAL WESTERLY FLOW IN THE LOWER LEVELS. A WELL-DEFINED LEE TROUGH COMBINED WITH MODEST SURFACE BASED CAPE SHOULD ALLOW FOR SCATTERED SHOWERS/TSTMS ACROSS INLAND AREAS BY EARLY AFTERNOON. THE SEABREEZE WILL BE PINNED NEAR THE COAST MUCH OF THE DAY BUT COULD BECOME A PLAYER LATER IN THE AFTERNOON AS IT STARTS TO NUDGE INLAND. WESTERLY STEERING FLOW SHOULD BRING INLAND CONVECTION TOWARD THE COAST AS THE DAY PROGRESSES. OUR BEST COVERAGE LOOKS TO BE LATE AFTERNOON INTO THE EVENING THOUGH A FEW STORMS COULD CONTINUE OVERNIGHT GIVEN SUCH A RICH AIRMASS IN PLACE. THE UPPER TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES ON TUESDAY WITH A COLD FRONT SLOWLY DROPPING SOUTHEAST TOWARD THE AREA. DEWPOINTS RISING INTO THE MIDDLE 70S WITH TEMPS PUSHING INTO THE LOWER 90S WILL YIELD SUBSTANTIAL SURFACE BASED CAPES RANGING FROM 2000 TO 3000 J/KG. ADDITIONALLY SHORTWAVE ENERGY WILL PUSH IN FROM THE WEST DURING THE AFTERNOON. THUS FAIRLY GOOD COVERAGE OF SHOWERS AND TSTMS EXPECTED DURING THE DAY TUESDAY...ESPECIALLY LATER IN THE AFTERNOON ONCE THE CONVECTIVE BOUNDARIES BEGIN INTERACTING WITH THE SEABREEZE. SCATTERED CONVECTION MAY CONTINUE INTO TUESDAY NIGHT BEFORE TAPERING OFF FROM NORTH TO SOUTH. THE FRONT SHOULD PUSH SOUTH OF THE AREA ON WEDNESDAY WITH SLIGHTLY DRIER AND COOLER CONDITIONS IN ITS WAKE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... CANADIAN HIGH PRESSURE WILL PREVAIL FOR THE BEGINNING OF THE PERIOD BUT STEADILY SHIFT EAST WITH A RETURN FLOW SETTING UP ON THE SW PERIPHERY. MOST AREAS WILL BE DRY WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. DIURNAL CONVECTION RETURNS TO THE FORECAST FRIDAY THROUGH SUNDAY AS LOW-LEVEL MOISTURE INCREASES AND ANOTHER UPPER TROUGH SETS UP SHOP. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... THE BIGGEST TAF CONCERN FOR THE UPCOMING FORECAST PERIOD IS THE POTENTIAL FOR IMPACTS FROM SHOWERS/THUNDERSTORMS THIS AFTERNOON AND EVENING. SO FAR...DEVELOPMENT HAS BEEN SLOW AND EVEN THE CU FIELD HAS BEEN QUITE MUTED THANKS TO SOME SUPPRESSION ALOFT. MODELS DO SHOW MOST OF THE DEVELOPMENT IN THE LATE AFTERNOON HOURS AND THAT IS WHAT IS PRESENTED IN THE TAF/S. THE MODELS TEND TO PLACE THE BEST COVERAGE CLOSEST TO KCHS SO I HAVE ADDED THE MOST DETAIL THERE WITH PREVAILING VCTS STARTING AT 20Z AND THEN A TEMPO FOR MVFR TSRA CONDITIONS BETWEEN 21-23Z. I HAVE LEFT KSAV WITH JUST A VCTS FOR NOW...BUT WILL CONTINUE TO MONITOR RADAR TRENDS FOR AMENDMENTS AT BOTH SITES. MOST OF THE COVERAGE WILL THEN DRIFT INLAND LATE THIS EVENING AND THE FORECAST IS VFR THEREAFTER. SOME GUIDANCE HINTS AT THE POSSIBILITY FOR MVFR CEILINGS OVERNIGHT...BUT CHANCES ARE TOO LOW TO WARRANT A MENTION AT THIS POINT. EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND TSTMS MONDAY THROUGH TUESDAY NIGHT WITH OCCASIONAL REDUCTIONS IN CEILING AND VISIBILITY. && .MARINE... FAIRLY LIGHT WINDS AND SEAS 2 TO 3 FT EXPECTED THROUGH THE AFTERNOON HOURS. A STRONGER NOCTURNAL SURGE IS ANTICIPATED TONIGHT AS THE BOUNDARY LAYER PRES GRADIENT TIGHTENS. THERE MAY BE A SHORT DURATION WHERE WINDS APPROACH SMALL CRAFT ADVISORY CONDITIONS IN FREQUENT GUSTS OVER 20 KT BUT WE HAVE CAPPED OFFSHORE FLOW AT 15 TO 20 KT FOR NOW. SEAS WILL BUILD TO NEAR 4 FT BEYOND 20 NM OFFSHORE. MONDAY THROUGH FRIDAY...WEATHER CONDITIONS WILL REMAIN BELOW ADVISORY CRITERIA. SOUTH TO SOUTHWEST WINDS WILL PERSIST UNTIL TUESDAY AHEAD OF THE COLD FRONT. ONCE THE FRONT PUSHES INTO THE AREA...WINDS WILL BECOME VARIABLE AND LIGHT...WITH SEAS NO HIGHER THAN 2-3 FEET. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...BSH SHORT TERM...JRL LONG TERM...JRL AVIATION...BSH MARINE...JRL
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1221 PM EDT SUN SEP 1 2013 .UPDATE... HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION OVER NORTH GA. WHILE IT IS SHOWING A LULL AS THE OUTFLOW FROM MCS INTERACTS WITH INSTABILITY...CAPES 1500-2000 ACROSS PORTIONS OF WEST AND CENTRAL GA. CURRENT THINKING AS AREA OVER NORTH GA WILL TRANSITION SOUTHWARD WITHOUT THE LULL AND HAVE ADJUSTED POP/WEATHER TRENDS ACCORDINGLY. OTHERWISE CURRENT FORECAST TRENDS PRETTY MUCH ON TRACK EXCEPT FOR MAX TEMPERATURES IN PORTIONS OF NORTH GA WHICH WERE ALSO TWEAKED. UPDATED FORECAST PRODUCTS WILL BE ISSUED SHORTLY. && .PREV DISCUSSION... /ISSUED 746 AM EDT SUN SEP 1 2013/ UPDATE... HAVE UPPED THE POPS ACROSS NORTHERN GA THIS MORNING. HAVE SEEN A STEADY INCREASE IN COVERAGE AHEAD OF WEAKENING MCS. PREV DISCUSSION... /ISSUED 324 AM EDT SUN SEP 1 2013/ SHORT TERM /TODAY THROUGH MONDAY/... HIGH PRESSURE HAS MOVED OFFSHORE...WHILE A STALLED BOUNDARY REMAINS SITUATED ACROSS THE OHIO VALLEY. REGIONAL RADAR AND SATELLITE SHOWS A WEAKENING MCS DROPPING SOUTH ACROSS SOUTHERN IN AND W KY. ANOTHER AREA OF WEAKENING STORMS IS ACROSS THE TN/NC BORDER. JUST A FEW CLOUDS ACROSS THE CWFA THIS MORNING...BLOW OFF FROM THE STORMS TO THE NORTH. PATCHY FOG HAS ALSO DEVELOPED BUT SHOULD BEGIN TO BURN OFF AFTER SUNRISE. THE LATEST RUN OF THE HRRR BRINGS THE REMNANT SHOWERS/ THUNDERSTORMS FROM THE COMPLEXES UP NORTH ACROSS NORTHERN GA DURING THE FIRST PART OF THE MORNING. THIS SEEMS REASONABLE...AS THE ACTIVITY SHOULD CONTINUE TO WEAKEN AS IT APPROACHES THE NORTHERN METRO. DO THINK THAT STORMS LATER IN THE DAY COULD FOCUS UPON THE LEFTOVER OUTFLOW/DIFFERENTIAL HEATING BOUNDARY. HAVE TRIED TO ORIENT POPS ACCORDING TO THE EARLY HOURS OF THE HRRR OUTPUT. MODELS DO HAVE A WEAK SHORTWAVE DROPPING SOUTH IN THE FLOW ACROSS NORTHERN GA LATER IN THE AFTERNOON. THIS FEATURE SHOULD SERVE TO FOCUS/INITIATE SCT/NMRS STORMS INTO THE EARLY EVENING. MODELS KEEP THE ATMOS UNSTABLE OVERNIGHT...AND WITH ABUNDANT LOW LEVEL MOISTURE...SCT/ISO STORMS WILL BE POSSIBLE THROUGH THE OVERNIGHT HOURS. TOWARDS 12Z MONDAY...THE GFS LOOKS AS IF IT IS TRYING TO BRING AN MCS ACROSS NORTHERN GA. THE NAM DOESN`T REALLY HAVE THIS FEATURE IN THE MID LEVELS OR THE 800MB - 300MB THICKNESS PATTERN. THE GFS MAY BE SUFFERING FROM CONVECTIVE FEEDBACK...BUT WILL KEEP SCT POPS IN ACROSS THE NORTH OVERNIGHT. IF THE COMPLEX DOES INDEED DEVELOP...POPS MAY HAVE TO BE RAISED. FRONT OVER THE MID ATLANTIC WILL SHIFT SOUTHWARD THROUGH MONDAY AND CONTINUE TO APPROACH THE CWFA FROM THE NORTH. GOOD SOUTHERLY FLOW AHEAD OF THE BOUNDARY AND INSTABILITY WILL LEAD TO ANOTHER DAY OF SCT THUNDERSTORMS. SEVERE WEATHER IS NOT ANTICIPATED TODAY OR MONDAY...BUT A FEW OF THE STORMS COULD BE STRONG. IN ADDITION... LOCALLY HEAVY RAINFALL ACROSS NORTHERN GA WILL BE POSSIBLE ESPECIALLY ON MONDAY. STORMS WILL ALSO BE CAPABLE OF PRODUCING OCCASIONAL LIGHTNING STRIKES AND GUSTY WINDS. NLISTEMAA LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... THE EXTENDED BEGINS WITH AN UPPER LOW OVER SOUTHERN ONTARIO... TROUGHING DOWN THE EASTERN THIRD OF THE U.S...WITH THE ASSOCIATED COLD FRONT PUSHING THROUGH THE SOUTHEAST. PRECIP CHANCES CONTINUE ACROSS THE STATE MONDAY NIGHT BUT AS THE FRONT PUSHES TOWARD THE COAST TUESDAY AND TUESDAY NIGHT...DRIER AIR FILTERS IN BEHIND IT AND PUSHES PRECIP CHANCES INTO CENTRAL AND SOUTH GEORGIA. DRIEST DAY LOOKS TO BE WEDNESDAY AS THE TROUGH AXIS SHIFTS EAST OFF THE COAST AND HIGH PRESSURE DOMINATES MOST OF THE STATE. HOWEVER...ON THURSDAY ANOTHER SHORTWAVE ROUNDS THE BASE OF THE TROUGH AND LOOKS TO PROVIDE ENOUGH LIFT THAT WHEN COMBINED WITH OROGRAPHIC LIFTING IS ENOUGH TO WARRANT SLIGHT TO LOW CHANCE POPS IN THE NORTHEAST MOUNTAINS. ECMWF IS A LITTLE STRONGER WITH THIS SHORTWAVE INITIALLY BUT BOTH MODELS IN REASONABLE AGREEMENT WITH THIS FEATURE ON FRIDAY. AS WE PUSH INTO THE WEEKEND...THE GFS IS DEFINITELY THE WETTER OF THE TWO MODELS SO COMPROMISED ON THIS UNCERTAINTY BY PAINTING GENERALLY SLIGHT CHANCE POPS ACROSS THE AREA ON SATURDAY. AS FOR TEMPS...TUESDAY WILL CONTINUE THE TREND OF ABOVE-NORMAL TEMPS...AND EVEN WITH THE FRONTAL PASSAGE TEMPS WILL ONLY DROP A COUPLE OF DEGREES BUT SHOULD BE NEAR SEASONAL NORMALS. THE MORE NOTICEABLE CHANGE WILL BE IN OVERNIGHT LOWS...LIKELY DROPPING AT LEAST 5 DEGREES BETWEEN MONDAY NIGHT AND WEDNESDAY NIGHT. SATURDAY IS A BIT FAR OUT THERE BUT WITH THE INFLUENCE OF THE STRONG SHORTWAVE /INCREASED CLOUDINESS/...RIGHT NOW THAT LOOKS TO BE THE COOLEST DAY OF THE PERIOD. TDP AVIATION... 12Z UPDATE... ENHANCED FOG CHANNEL SHOWS A STRIP OF 300 TO 500 FOOT CIGS FROM CANTON TO WEST OF ATL. THIS AREA IS MOVING EAST. DON`T THINK THE DECK WILL DISSIPATE BEFORE IT REACHES THE AIRPORT...SO WILL INCLUDE A BKN005 DECK FOR TWO HOURS. THE LOW DECK WILL SCT OUT TO A CU DECK AROUND 4500 FT LATE THIS MORNING. CONVECTION HAS BEEN INCREASING ACROSS N GA THIS MORNING. LATEST RUN OF THE HRRR HAS THIS ACTIVITY COMING THROUGH THE AIRPORT AROUND 18Z. MOVED UP THE PRECIP TIMING. //ATL CONFIDENCE...12Z UPDATE... LOW-MEDIUM CONFIDENCE ON LOW STRATUS CIGS THROUGH 15Z. MEDIUM CONFIDENCE ON CONVECTION TIMING TODAY. OTHERWISE...HIGH CONFIDENCE REMANING ELEMENTS. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 90 71 91 72 / 50 40 40 30 ATLANTA 89 72 89 74 / 50 40 40 40 BLAIRSVILLE 83 67 82 68 / 60 30 60 40 CARTERSVILLE 89 71 90 71 / 60 40 40 40 COLUMBUS 92 73 91 74 / 60 50 40 30 GAINESVILLE 88 71 88 73 / 60 40 40 40 MACON 91 72 91 72 / 60 50 40 30 ROME 88 71 92 72 / 60 30 60 40 PEACHTREE CITY 90 70 90 71 / 50 40 40 30 VIDALIA 91 74 91 74 / 60 40 40 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ATWELL LONG TERM....30 AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
252 PM CDT SUN SEP 1 2013 .DISCUSSION... 1045 AM CDT NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER. HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS DURING THE AFTERNOON. CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS. BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS. OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST CWA. WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL CONVERGENCE ELSEWHERE. FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT. IZZI //PREV DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GENERALLY WESTERLY WINDS TO ARND 10KT UNTIL FROPA EARLY THIS EVENING...THEN SHIFT NORTHWEST/NORTH AND STRENGTHENING OVERNIGHT FOLLOWING FRONTAL PASSAGE. * NORTH WINDS GUSTING TO 18 KT BY THE EARLY MORNING HOURS. * ISOLD SHRA/TSRA DEVELOPING ALONG OR JUST AHEAD OF THE FRONTAL BOUNDARY. KREIN //DISCUSSION...UPDATED 18Z... PRIMARY CONCERN FOR THE PERIOD WILL BE THE CHANCES FOR SHRA/TSRA LATE THIS AFTERNOON INTO EARLY THIS EVENING. A COLD FRONT IS DROPPING SEWD INTO THE MIDDLE MISSISSIPPI VALLEY WHICH SHOULD BE THE FOCUS FOR THE CONVECTIVE ACTIVITY. LATEST SFC ANALYSIS SHOWS A FAIRLY DIFFUSE BOUNDARY WITH LITTLE WIND SHIFT OR TEMPERATURE CONTRAST INVOF THE BOUNDARY WITH WINDS ONLY GRADUALLY VEERING FROM WLY TO NWLY. EARLY MORNING STRATUS AND FOG HAS FINALLY CLEARED AND INCREASED INSOLATION IS ALLOWING SFC TEMPS TO INCREASE INTO THE 80S WITH DEWPOINTS IN THE UPPER 60S TO LOWER 70S. LATEST VISIBLY SATELLITE IMAGERY IS ALSO INDICATING ENHANCED CU DEVELOPMENT INVOF THE FRONTAL BOUNDARY. STILL EXPECTING SCT SHOWERS AND THUNDERSTORMS AS THE FRONT MOVES THROUGH THE AREA...BUT SINCE CONVECTIVE ACTIVITY IS EXPECTED TO REMAIN SCATTERED...CONFIDENCE IN EXACT TIMING AND DURATION IS LOW. FOLLOWING THE FROPA...COOLER...DRIER AIR WILL GRADUALLY FILTER INTO THE REGION WITH THE STRONGEST COLD ADVECTION DEVELOPING DURING THE EARLY MORNING HOURS. EXPECT THAT WINDS SHOULD VEER TO NORTHERLY AND GUST TO ARND 18KT IN TIME FOR THE MORNING RUSH HOURS. WINDS SHOULD GRADUALLY TAPER OFF THROUGH THE AFTERNOON TOMORROW AS HIGH PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES. KREIN //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED. * LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 252 PM...LOW PRESSURE OVER LAKE SUPERIOR WILL SLOWLY MOVE EAST INTO QUEBEC MONDAY AFTERNOON. A TRAILING COLD FRONT WILL MOVE SOUTH ACROSS LAKE MICHIGAN THIS EVENING SHIFTING WINDS BRIEFLY NORTHWEST AND THEN NORTHERLY OVERNIGHT. PREVAILING SPEEDS IN THE 20-25KT RANGE STILL LOOK ON TRACK THOUGH ITS STILL POSSIBLE FOR SOME GUSTS TO 30 KT ESPECIALLY MONDAY MORNING. HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT INTO MONDAY AND THEN SLIDE SOUTHEAST ACROSS THE SOUTHERN LAKES AND OHIO VALLEY MONDAY NIGHT THROUGH WEDNESDAY. THIS WILL ALLOW THE WINDS TO DIMINISH FIRST ACROSS THE SOUTHERN END OF THE LAKE BUT AS ANOTHER FRONT SAGS INTO THE NORTHERN LAKES TUESDAY NIGHT INTO WEDNESDAY...THE GRADIENT MAY STAY SOMEWHAT TIGHT ACROSS THE NORTHERN HALF OR THIRD OF THE LAKE TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE SPREADING ACROSS SOUTHERN CANADA TUESDAY NIGHT WILL WEAKEN AND MERGE WITH THE HIGH OVER THE OHIO VALLEY WEDNESDAY AND WEDNESDAY NIGHT. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
102 PM CDT SUN SEP 1 2013 .DISCUSSION... 1045 AM CDT NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER. HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS DURING THE AFTERNOON. CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS. BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS. OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST CWA. WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL CONVERGENCE ELSEWHERE. FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT. IZZI //PREV DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * WEST TO WEST-NORTHWEST WINDS TO ARND 10KT UNTIL FROPA LATE THIS AFTERNOON...THEN SHIFT NORTHWEST/NORTH AND STRENGTHENING FOLLOWING FRONTAL PASSAGE. * NORTH WINDS GUSTING TO 18KT BY THE EARLY MORNING HOURS. * ISOLD SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY. KREIN //DISCUSSION...UPDATED 18Z... PRIMARY CONCERN FOR THE PERIOD WILL BE THE CHANCES FOR SHRA/TSRA LATE THIS AFTERNOON INTO EARLY THIS EVENING. A COLD FRONT IS DROPPING SEWD INTO THE MIDDLE MISSISSIPPI VALLEY WHICH SHOULD BE THE FOCUS FOR THE CONVECTIVE ACTIVITY. LATEST SFC ANALYSIS SHOWS A FAIRLY DIFFUSE BOUNDARY WITH LITTLE WIND SHIFT OR TEMPERATURE CONTRAST INVOF THE BOUNDARY WITH WINDS ONLY GRADUALLY VEERING FROM WLY TO NWLY. EARLY MORNING STRATUS AND FOG HAS FINALLY CLEARED AND INCREASED INSOLATION IS ALLOWING SFC TEMPS TO INCREASE INTO THE 80S WITH DEWPOINTS IN THE UPPER 60S TO LOWER 70S. LATEST VISIBLY SATELLITE IMAGERY IS ALSO INDICATING ENHANCED CU DEVELOPMENT INVOF THE FRONTAL BOUNDARY. STILL EXPECTING SCT SHOWERS AND THUNDERSTORMS AS THE FRONT MOVES THROUGH THE AREA...BUT SINCE CONVECTIVE ACTIVITY IS EXPECTED TO REMAIN SCATTERED...CONFIDENCE IN EXACT TIMING AND DURATION IS LOW. FOLLOWING THE FROPA...COOLER...DRIER AIR WILL GRADUALLY FILTER INTO THE REGION WITH THE STRONGEST COLD ADVECTION DEVELOPING DURING THE EARLY MORNING HOURS. EXPECT THAT WINDS SHOULD VEER TO NORTHERLY AND GUST TO ARND 18KT IN TIME FOR THE MORNING RUSH HOURS. WINDS SHOULD GRADUALLY TAPER OFF THROUGH THE AFTERNOON TOMORROW AS HIGH PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES. KREIN //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED. * LOW/MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1143 AM CDT SUN SEP 1 2013 .DISCUSSION... 1045 AM CDT NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER. HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS DURING THE AFTERNOON. CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS. BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS. OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST CWA. WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL CONVERGENCE ELSEWHERE. FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT. IZZI //PREV DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * WEST TO WEST-NORTHWEST WINDS TO ARND 10KT. FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AND STRENGTHENING FOLLOWING FRONTAL PASSAGE. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 19-22Z. KREIN //DISCUSSION...UPDATED 12Z... SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO 10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY 00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS INTO THE MID TEENS DEVELOPING OVERNIGHT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM/HIGH CONFIDENCE IN WIND DIR/SPEED. * LOW/MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1046 AM CDT SUN SEP 1 2013 .DISCUSSION... 1045 AM CDT NO BIG CHANGES MADE TO GOING FORECAST OTHER THAN TO SLOW THE WARM UP TREND IN HOURLY TEMPS THIS MORNING DUE TO CONSIDERABLE CLOUD COVER. HAVE LEFT FORECAST HIGHS TEMPS LARGELY AS IS BANKING ON THE FACT THAT THE FAIRLY HIGH SUN ANGLE SHOULD BE ENOUGH TO ERODE STRATUS AND ALLOW FOR AT LEAST PARTIAL SUNSHINE AND A QUICK REBOUND IN TEMPS DURING THE AFTERNOON. CONVECTIVE CHANCES AND SEVERE POTENTIAL ARE A BIT MORE MURKY. FRONT THAT PASSED SOUTH OF THE AREA EARLIER THIS WEEKEND TOOK SOME OF THE MOISTURE WITH IT...THOUGH SURFACE OBS DO SHOW A SMALL RIBBON OF HIGHER DEWPOINTS BEGINNING TO POOL IN ADVANCE OF THE SECOND AND STRONGER FRONT THAT WILL MOVE THROUGH LATER TODAY. FRONTAL CONVERGENCE LOOKS TO BE FAIRLY WEAK WITH SFC WINDS ALL VEERED TO THE WEST ALREADY AHEAD OF THE FRONT WITH LOW LEVEL MASS CONVERGENCE BASICALLY JUST SPEED CONVERGENCE WITH STRONGER NORTHWEST WINDS BEHIND THE FRONT. WATER VAPOR IMAGERY DOES SHOW A SHORTWAVE ASSOCIATED WITH A SPEED MAX MOVING INTO SOUTHERN MN AND JUST NOW INTO FAR NORTHERN IOWA THIS MORNING. LARGE SCALE ASCENT IN ADVANCE THIS FEATURE WILL BE KEY IN THE CONVECTIVE POTENTIAL THIS AFTERNOON GIVEN THE PALTRY LOW LEVEL CONVERGENCE AND STOUT CAPPING INVERSION NOTED ON THE 1200 UTC KDVN/KILX SOUNDINGS. BOTH SOUNDINGS DID SHOW A FAIRLY CLASSIC LOAD GUN TYPE SET UP WITH STEEP LAPSE RATES LOCATED ABOVE A MOIST BOUNDARY LAYER. ASSUMING THAT WE ARE ABLE TO HEAT UP AS EXPECTED THIS AFTERNOON THEN MLCAPES WOULD LIKELY CLIMB ABOVE 2000 J/KG WITH FORECAST RAP SOUNDINGS SUGGESTING THAT THE CAP WILL BE EFFECTIVELY LIFTED THROUGH WITH MINIMAL INHIBITION. FAIRLY STOUT 6KM WEST-NORTHWEST WINDS OF 30-35KT HAVE BEEN SAMPLED UPSTREAM AND ARE PROGGED TO BE OVER THE AREA THIS AFTERNOON. HOWEVER...LIGHT WESTERLY WINDS AT THE SFC WILL RESULT IN BULK SHEAR VALUES OF ONLY 25-30KT...WHICH GIVEN MODERATE INSTABILITY WOULD BE ENOUGH TO ALLOW FOR SOME DEGREE OF STORM ORGANIZATION AND RESULTANT SEVERE THREAT...PRIMARILY IN THE FORM OF DAMAGING WINDS. OF COURSE THIS IS ALL CONTINGENT ON SUFFICIENT INSTABILITY ACTUALLY BEING REALIZED AND THEN STORMS FORMING DESPITE THE MEAGER LOW LEVEL CONVERGENCE. GIVEN ALL THE UNCERTAINTIES HAVE OPTED TO MAINTAIN POPS IN THE 40-50% RANGE THIS AFTERNOON INTO EARLY THIS EVENING SOUTHEAST CWA. WILL NEED TO WATCH FOR POTENTIAL LAKE BREEZE FORMATION RIGHT ALONG THE SHORE THIS AFTERNOON GIVEN LIGHT SYNOPTIC WINDS. SHOULD LAKE BREEZE FORM THE ENHANCED CONVERGENCE COULD BE A FOCAL POINT CONVECTIVE INITIATION GIVEN THE RELATIVE ABSENCE OF LOW LEVEL CONVERGENCE ELSEWHERE. FORECAST GRIDS AND DERIVED PRODUCTS HAVE ALREADY BEEN SENT. IZZI && .PREV DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 10KT LATE MORNING. FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT 00Z. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z. KREIN //DISCUSSION...UPDATED 12Z... SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO 10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY 00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS INTO THE MID TEENS DEVELOPING OVERNIGHT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
901 AM CDT SUN SEP 1 2013 .DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 10KT LATE MORNING. FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT 00Z. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z. KREIN //DISCUSSION...UPDATED 12Z... SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO 10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY 00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS INTO THE MID TEENS DEVELOPING OVERNIGHT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023-ILZ032- ILZ033-ILZ039 UNTIL 10 AM SUNDAY. BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10 AM SUNDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
649 AM CDT SUN SEP 1 2013 .DISCUSSION... 352 AM CDT MAIN CONCERNS THIS FORECAST PERIOD ARE WITH FOG EARLY THIS MORNING ACROSS THE ENTIRE AREA...THUNDERSTORMS SOME OF WHICH COULD BE STRONG AND MAYBE EVEN AN ISOLATED SEVERE THREAT...AS WELL AS MUCH COOLER TEMPS WITH BEACH HAZARDS EXPECTED MONDAY. CONTINUE TO MONITOR FOG POTENTIAL EARLY THIS MORNING WITH SEVERAL SITES CURRENTLY REPORTING VIS BELOW ONE MILE...WITH SOME ISOLATED LOCATIONS BOUNCING AROUND ONE QUARTER MILE AT TIMES. ALTHOUGH FOG IS CURRENTLY BEING OBSERVED ACROSS THE ENTIRE CWA...MAIN CONCERN RIGHT NOW IS THE FAR NORTHWEST AND FAR NORTHERN CWA. LOWEST VIS IS IN THIS LOCATION AT THIS TIME...WITH LATEST SATELLITE IMAGERY DEPICTING THE POTENTIAL FOR THE MORE DENSE FOG WHICH HAS BEEN RESIDING JUST OUTSIDE OF THE CWA BEGINNING TO SPREAD INTO THE CWA. HAD ISSUED AN SPS EARLIER FOR THIS FOG/LOW VIS...BUT WILL MAKE A LAST MINUTE DECISION HERE IN THE NEAR TERM WITH THE POTENTIAL FOR A FOG ADVISORY. ALTHOUGH...DO EXPECT ANY FOG THIS MORNING TO QUICKLY DISSIPATE WITH THE APPROACH OF SUNRISE. LOW LEVEL STRATUS ALSO REMAINS ACROSS PORTIONS OF THE CWA...IN PARTICULAR THE SOUTHEAST CWA. IT HAS SHOWN A DISSIPATING TREND AS IT SLOWLY MOVES EAST THIS MORNING...AND EXPECT THIS TREND TO CONTINUE THIS MORNING. ALTHOUGH AS THIS STRATUS DEPARTS TO THE EAST...MID/HIGH LEVEL CLOUD COVER SHOULD CONTINUE TO SPREAD EASTWARD ACROSS THE CWA THROUGH MID MORNING. MOST LOCATIONS SHOULD OBSERVE A PERIOD OF SUNSHINE THIS MORNING...BUT WITH THE ARRIVAL OF THIS MID/HIGH LEVEL CLOUD COVER MOST LOCATIONS SHOULD GO MORE PARTLY CLOUDY TO PARTLY SUNNY. DESPITE A FAIRLY WARM AIR MASS STILL IN PLACE...DID SLIGHTLY LOWER HIGH TEMPS TODAY. NONETHELESS...MID TO UPPER 80S WILL STILL BE REACHABLE WITH SOME AREAS ACROSS THE SOUTHERN CWA POSSIBLY APPROACHING THE 90 DEGREE MARK. IF YOU STEP OUTSIDE THIS MORNING...YOU WILL NOTICE THAT MUGGY CONDITIONS ARE IN STILL IN PLACE. THIS IS A RESULT OF MID TO UPPER 60 DEGREE DEWPOINTS...THAT SHOULD ACTUALLY SLIGHTLY INCREASE AND APPROACH 70 DEGREES. THIS WILL RESULT IN SOME LOCATIONS...MAINLY THE SOUTHWEST CWA OBSERVING MID 90 DEGREE HEAT INDICES WITH UPPER 90 DEGREE HEAT INDICES NOT OUT OF THE QUESTION IN THOSE LOCATIONS. PRECIP TRENDS LATER THIS MORNING AND ESPECIALLY INTO THE AFTERNOON REMAIN SOMEWHAT UNCERTAIN AT THIS TIME...WITH GUIDANCE VARYING AS TO THE EXTENT OF THE COVERAGE OF THUNDERSTORMS. MADE ONLY MINOR ADJUSTED TO POPS FOR TODAY...MAINLY ADJUSTING THE TIMING AND TRENDS INTO THE AFTERNOON. AS LARGE SCALE VORT MAX ACROSS THE UPPER MIDWEST SHIFTS TO THE EAST TODAY...SOUTHERN EDGE OF THIS WAVE AS WELL AS SMALLER SCALE IMPULSES SHOULD DROP SOUTHEAST TOWARDS THE AREA LATER THIS MORNING AND AFTERNOON. THIS WILL HELP AN ATTENDANT SURFACE TROUGH AND ASSOCIATED COLD FRONT DROP SOUTHEAST TOWARDS THE CWA BY MID DAY. DESPITE THIS FRONT AND SOME SUPPORT ALOFT APPROACHING...THERE WILL BE SOME LIMITING FACTORS IN PLACE THAT COULD LIMIT THE OVERALL COVERAGE OF THUNDERSTORM DEVELOPMENT TODAY. FIRST...LOW-MID LEVEL FLOW ARE FORECAST TO ALREADY BE WEST IF NOT NORTHWEST OUT AHEAD OF THIS FRONT...WITH LATEST RAP ANALYSIS ALREADY SHOWING THIS TREND. THIS WILL LIMIT THE COVERAGE AND STRENGTH OF ANY LOW/MID LEVEL CONVERGENCE. SECOND...CLOUD COVER SPREADING SOUTHEAST ACROSS THE CWA COULD PLAY INTO THE AMOUNT OF HEATING/DESTABILIZATION. WITHOUT ANY CLOUD COVER...MLCAPE VALUES COULD REACH OR EXCEED 2000 J/KG ONCE AGAIN TODAY. WITH THIS AMOUNT OF INSTABILITY AND WITH THE PRESENCE OF SUFFICIENT MOISTURE AND A BOUNDARY...I AM A LITTLE CONCERNED FOR THUNDERSTORM POTENTIAL TODAY. ALTHOUGH ONCE AGAIN...THIS CLOUD COVER COULD LIMIT THE AMOUNT OF INSTABILITY. DESPITE THESE LIMITING FACTORS...DO FEEL THAT HIGH CHANCE POPS MAKING MENTION OF SCATTERED THUNDERSTORMS IS WARRANTED FOR MOST LOCATIONS TODAY INTO THE EARLY EVENING. ALTHOUGH ITS CONCEIVABLE MOST LOCATIONS WILL NOT OBSERVE PRECIP TODAY...ISOLATED TO SCATTERED DEVELOPMENT IS AT LEAST A POSSIBILITY. IF THIS CLOUD COVER CAN EXIT AND HEATING/SUFFICIENT DESTABILIZATION OCCURS...STRONG THUNDERSTORMS WITH EVEN AN ISOLATED SEVERE STORM WILL BE POSSIBLE DESPITE THE LACK OF BULK SHEAR...AND THIS WILL OCCUR WHERE EVER BEST CONVERGENCE CAN OCCUR. COOLER TEMPS FILTERING IN ON THE BACKSIDE OF THIS SYSTEM WILL PROVIDE MUCH COOLER TEMPS ON MONDAY...WITH FORECAST HIGHS IN THE 70S EXPECTED. DID ADD CLOUD COVER FOR MONDAY AS I DO THINK STRATOCU DEVELOPMENT WILL OCCUR...WITH CYCLONIC FLOW STILL IN PLACE. ALSO...ITS POSSIBLE THAT WITH THIS COOLER AIR MOVING DOWN THE LAKE...CLOUD COVER COULD SPILL INTO AREAS IMMEDIATE TO THE LAKE MONDAY NIGHT. STRONGER NORTHERLY WINDS RESULTING IN HIGHER WAVES...WILL MAKE FOR DANGEROUS SWIMMING CONDITIONS LATE TONIGHT INTO MONDAY AND TUESDAY WITH A BEACH HAZARDS STATEMENT ISSUED AT THIS TIME. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * PATCHY GROUND FOG DEVELOPED EARLY THIS MORNING...CURRENTLY IS HOLDING WEST OF ORD/MDW WHERE VSBYS HAVE REDUCED TO LESS THAN 1/2SM IN SPOTS. * SOUTHWEST/WEST WINDS WILL INCREASE TO ARND 6-8KT AFT 13Z...THEN FRONT WILL APPROACH WITH WINDS TURNING NORTHWEST/NORTH AFT 00Z. * ISO SHRA/TSRA DEVELOPING ALONG FRONTAL BOUNDARY ARND 22-24Z. BEACHLER //DISCUSSION...UPDATED 12Z... SHALLOW GROUND FOG HAS DEVELOPED EARLY THIS MORNING FOR MANY AIRFIELDS IN NORTHERN IL/NORTHWEST IN...WITH SOME THICKER OR PATCHY DENSE FOG WEST OF KUGN AIRFIELD. EXPECT FOG TO LIFT/ERODE BY 13-14Z WITH VSBYS RETURNING TO VFR. WINDS WILL SLOWLY INCREASE FROM THE SOUTHWEST TO WEST ARND 6-8KT...THEN INCREASE SLIGHTLY TO 10KT BY MIDDAY. A FRONTAL BOUNDARY WILL STEADILY APPROACH THE REGION FROM THE NORTHWEST AND EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP ALONG THIS BOUNDARY. GUIDANCE HAS MAINTAINED A CONSISTENT THEME OF ARRIVAL AROUND 19-20Z ACROSS FAR NORTHWEST IL...ARRIVING AT RFD ARND 21-23Z. THEN THIS BOUNDARY AND THUNDERSTORMS WILL SLIDE SOUTHEAST...REACHING ORD/MDW CLOSER TO 22-24Z. HAVE MAINTAINED THIS IN THE TAF AS A TEMPO GROUP. EXPECT THE BOUNDARY TO CONTINUE TO PRESS SOUTHEAST AND SHOULD CLEAR THE TAF SITES BY 00-02Z MON WITH CIGS SLOWLY IMPROVING. WINDS BEHIND THE BOUNDARY WILL STEADILY TURN NORTHWEST/NORTH AND INCREASE...WITH GUSTS INTO THE MID TEENS DEVELOPING OVERNIGHT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM/HIGH CONFIDENCE IN PATCHY FOG DISSIPATING AROUND 13-14Z. * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM/HIGH CONFIDENCE IN SHRA/TSRA DEVELOPING AFT 20Z. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...VFR. NORTH/NORTHEAST WINDS. TUESDAY THROUGH WEDNESDAY...VFR. AFTERNOON LAKE BREEZE. THURSDAY THROUGH SATURDAY...VFR. BEACHLER && .MARINE... 358 AM CDT WEAK AREA OF HIGH PRESSURE HAS ARRIVED OVER THE GREAT LAKES...HOWEVER THIS FEATURE CONTINUES TO PUSH EAST TOWARDS EASTERN CANADA. THE GRADIENT WILL REMAIN VERY MINIMAL OVER LAKE MICHIGAN THIS MORNING AND ALLOW FOR WINDS TO BE LIGHT. MEANWHILE A STRONGER AREA OF LOW PRESSURE WILL PUSH EAST ACROSS LAKE SUPERIOR TODAY...WITH A TRAILING FRONTAL BOUNDARY. THIS BOUNDARY SHOULD PUSH ACROSS LAKE MICHIGAN FROM NORTH TO SOUTH...BRINGING STRONGER WINDS AND LIKELY SMALL CRAFT CONDITIONS TO THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA BY EARLY MONDAY MORNING. THEN WITH MUCH COOLER AIR ARRIVING BEHIND THE FRONTAL PASSAGE...WAVES WILL REMAIN ELEVATED ESPECIALLY FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL CONTINUE TO DIMINISH AS ANOTHER RIDGE OF HIGH PRESSURE SLIDES INTO THE REGION MONDAY NIGHT INTO TUESDAY. DESPITE THE DIMINISHING WINDS...WAVES WILL LIKELY REMAIN A HAZARD FOR SMALL CRAFT ALONG THE ILLINOIS AND INDIANA NEARSHORE WATERS THROUGH MIDDAY TUESDAY. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010- ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022- ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 AM SUNDAY. BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM MONDAY TO 7 PM TUESDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002...4 AM MONDAY TO 7 PM TUESDAY. DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 AM SUNDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...4 AM MONDAY TO 4 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS GOODLAND KS
244 PM MDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 207 PM MDT SUN SEP 1 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW RIDGE BEGINNING TO RETREAT TOWARD THE FOUR CORNERS REGION WITH POSITIVELY TILTED TROUGH MIGRATING INTO THE NORTHERN GREAT LAKES REGION. STRONG SUBSIDENCE IS EVIDENT ACROSS THE NORTHERN PLAINS...AND IS BEGINNING TO OVERSPREAD OUR CWA FROM THE NORTH-NORTHEAST. AT THE SURFACE HIGH PRESSURE HAS SETTLED OVER OUR CWA WITH COLD FRONT NOW ALONG FRONT RANGE EXTENDING SOUTH ACROSS TEXAS PANHANDLE. THERE HAVE BEEN A FEW LIGHT SHOWERS SLOWLY MOVING ACROSS THE PLAINS OF EASTERN COLORADO AND LATEST RAP/HRRR SHOW THIS ACTIVITY FALLING APART THROUGH SUNRISE. AT THIS POINT I AM NOT CONFIDENT WE WILL SEE ANY MEASURABLE PRECIP OUT OF THIS WITH STABLE/DRY AIR SPREADING WEST...SO I WILL KEEP MENTION OUT THROUGH THE REMAINDER OF THE AFTERNOON. WITH STABLE AIR MASS IN PLACE AND SUBSIDENCE BUILDING IN ALOFT...I AM ANTICIPATING DRY CONDITIONS THROUGH MONDAY. REGARDING TEMPS...COOLER AIR MASS REMAINS IN PLACE OVERNIGHT...AND WITH LOW TD VALUES (45-50F) ADVECTING SOUTH THROUGH THIS EVENING AND CLEAR/CALM CONDITIONS WE SHOULD SEE VERY GOOD RADIATIONAL COOLING. I TRIMMED TEMPS A LITTLE WITH LOWS AT SOME LOCATIONS IN THE LOW 50S. H5 RIDGE WILL BEGIN TO BUILD BACK TO THE EAST MONDAY AND LEE TROUGH WILL BEGIN TO STRENGTHEN. WE SHOULD SEE WAA ALOFT WITH UNIDIRECTIONAL SOUTHERLY FLOW...AND HIGHS ABOUT 3-4F WARMER THAN TODAY (UPPER 80S/NEAR 90F). .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 221 PM MDT SUN SEP 1 2013 FROM MONDAY NIGHT THROUGH SATURDAY...THE UPPER HIGH PRESSURE CENTER REMAINS OVER THE CENTRAL ROCKIES AND CENTRAL HIGH PLAINS REGIONS. BY NEXT SUNDAY...THE UPPER LOW CENTER THAT HAS BEEN SLOWLY MOVING INTO THE PACIFIC NORTHWEST MOVES ACROSS THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS...PUSHING THE UPPER TROUGH AXIS FURTHER EAST OVER THE PLAINS AND WESTERN GREAT LAKES REGIONS AND TURNING THE FLOW ALOFT TO THE SOUTHWEST ACROSS THE FORECAST AREA. THE SURFACE HIGH PRESSURE AREA IN PLACE OVER THE PLAINS STATES MOVES FURTHER TO THE EAST AS THE SURFACE TROUGH MOVES INTO POSITION NEAR THE EASTERN COLORADO BORDER BY WEDNESDAY MORNING. A WEAK SURFACE TROUGH REMAINS NEARLY STATIONARY OVER THE EASTERN COLORADO BORDER THROUGH SUNDAY WITH MAINLY WESTERLY FLOW ALOFT OVER THE ROCKIES. DURING THIS TIME...ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN TO THE WEST EACH AFTERNOON WITH A STRAY STORM OR TWO MOVING INTO THE WESTERN PORTION OF THE FORECAST AREA LATE EACH DAY. OTHERWISE...HAVE KEPT THE EXTENDED FORECAST PERIOD DRY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1118 AM MDT SUN SEP 1 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH KGLD AND KMCK TERMINALS. NORTHEAST WINDS GUSTING TO 20KT WILL BE POSSIBLE EARLY IN THE TAF BEFORE THE SURFACE GRADIENT BEGINS TO RELAX BEHIND A COLD FRONT CURRENTLY SOUTH OF BOTH TERMINALS. BY MID AFTERNOON WINDS SHOULD BE BELOW 12KT AT BOTH TERMINALS WITH LIGHT AND VARIABLE WINDS OVERNIGHT. WINDS WILL SHIFT TO THE SOUTH AND INCREASE ONCE AGAIN AROUND SUNRISE MONDAY MORNING IN RESPONSE TO DEEPENING SURFACE TROUGH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
207 PM MDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 207 PM MDT SUN SEP 1 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW RIDGE BEGINNING TO RETREAT TOWARD THE FOUR CORNERS REGION WITH POSITIVELY TILTED TROUGH MIGRATING INTO THE NORTHERN GREAT LAKES REGION. STRONG SUBSIDENCE IS EVIDENT ACROSS THE NORTHERN PLAINS...AND IS BEGINNING TO OVERSPREAD OUR CWA FROM THE NORTH-NORTHEAST. AT THE SURFACE HIGH PRESSURE HAS SETTLED OVER OUR CWA WITH COLD FRONT NOW ALONG FRONT RANGE EXTENDING SOUTH ACROSS TEXAS PANHANDLE. THERE HAVE BEEN A FEW LIGHT SHOWERS SLOWLY MOVING ACROSS THE PLAINS OF EASTERN COLORADO AND LATEST RAP/HRRR SHOW THIS ACTIVITY FALLING APART THROUGH SUNRISE. AT THIS POINT I AM NOT CONFIDENT WE WILL SEE ANY MEASURABLE PRECIP OUT OF THIS WITH STABLE/DRY AIR SPREADING WEST...SO I WILL KEEP MENTION OUT THROUGH THE REMAINDER OF THE AFTERNOON. WITH STABLE AIR MASS IN PLACE AND SUBSIDENCE BUILDING IN ALOFT...I AM ANTICIPATING DRY CONDITIONS THROUGH MONDAY. REGARDING TEMPS...COOLER AIR MASS REMAINS IN PLACE OVERNIGHT...AND WITH LOW TD VALUES (45-50F) ADVECTING SOUTH THROUGH THIS EVENING AND CLEAR/CALM CONDITIONS WE SHOULD SEE VERY GOOD RADIATIONAL COOLING. I TRIMMED TEMPS A LITTLE WITH LOWS AT SOME LOCATIONS IN THE LOW 50S. H5 RIDGE WILL BEGIN TO BUILD BACK TO THE EAST MONDAY AND LEE TROUGH WILL BEGIN TO STRENGTHEN. WE SHOULD SEE WAA ALOFT WITH UNIDIRECTIONAL SOUTHERLY FLOW...AND HIGHS ABOUT 3-4F WARMER THAN TODAY (UPPER 80S/NEAR 90F). .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 214 AM MDT SUN SEP 1 2013 UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM TEMPERATURES AND DRY CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA WILL BE CENTERED OVER COLORADO FOR WEDNESDAY AS RIDGE BECOMES MORE AMPLIFIED INTO THE NORTHERN HIGH PLAINS FOR THURSDAY AND FRIDAY. THE RIDGE WILL DEAMPLIFY AND RETROGRADE WESTWARD INTO THE DESERT SOUTHWEST REGION NEXT WEEKEND AS AN UPPER LEVEL LOW MOVES OUT OF ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE TROUGHS LOOK TO DEVELOP LATE INTO NEXT WEEKEND AND MOVE INTO THE HIGH PLAINS WITH THE MAIN ASSOCIATED UPPER LEVEL TROUGH...WHICH COULD PROVIDE ENOUGH LIFT FOR THUNDERSTORM DEVELOPMENT FOR SUNDAY. STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE LOWER 90S. LOW TEMPERATURES FOR THE EXTENDED PERIOD WILL BE IN THE UPPER 60S FOR MOST LOCATIONS. MODEL SOUNDINGS SHOW STABLE UPPER AIR PROFILE THROUGH THE PERIOD...WITH MARGINAL INSTABILITY PARAMETERS AT BEST AND A GENERAL LACK OF MOISTURE IN THE UPPER AIR PROFILES. MODEL FORECASTS DIFFER ON PRECIPITATION CHANCES FOR NEXT SUNDAY...BUT ENCROACHING FRONTAL CLIPPER SYSTEM WILL LIKELY PROVIDE SOME CHANCES FOR STORM DEVELOPMENT. BESIDES SLIGHT PRECIPITATION CHANCES NEXT WEEKEND...THE MAIN WEATHER PATTERN FOR THE EXTENDED FORECAST PERIOD CONTINUES TO BE WARM TEMPERATURES AND MAINLY DRY CONDITIONS FOR THE TRI STATE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1118 AM MDT SUN SEP 1 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH KGLD AND KMCK TERMINALS. NORTHEAST WINDS GUSTING TO 20KT WILL BE POSSIBLE EARLY IN THE TAF BEFORE THE SURFACE GRADIENT BEGINS TO RELAX BEHIND A COLD FRONT CURRENTLY SOUTH OF BOTH TERMINALS. BY MID AFTERNOON WINDS SHOULD BE BELOW 12KT AT BOTH TERMINALS WITH LIGHT AND VARIABLE WINDS OVERNIGHT. WINDS WILL SHIFT TO THE SOUTH AND INCREASE ONCE AGAIN AROUND SUNRISE MONDAY MORNING IN RESPONSE TO DEEPENING SURFACE TROUGH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...MK AVIATION...DR
AREA FORECAST DISCUSSION
NWS WICHITA KS
1245 PM CDT SUN SEP 1 2013 .UPDATE... ISSUED AT 1108 AM CDT SUN SEP 1 2013 COOL FRONTAL BOUNDARY CONTINUES TO SLOWLY PUSH INTO SRN KS AT THIS TIME. CURRENTLY LOCATED FROM KDDC-KPTT TO JUST SOUTH OF KICT TO NEAR KCNU. SOME WIDELY SCT SHOWERS OR SPRINKLES ARE LOCATED ALONG THE FRONT...WITH MORE WIDESPREAD SHOWERS OVER ERN KS. EXPECT THIS FRONTAL BOUNDARY TO CONTINUE TO PUSH SOUTH INTO EXTREME SRN KS EARLY THIS AFTERNOON...AND EVENTUALLY PUSH INTO OK BY LATE THIS AFTERNOON/EARLY THIS EVENING. THE DRIER AIR ASSOCIATED WITH THIS BOUNDARY IS LAGGING BEHIND SOMEWHAT...WITH SFC DEWPOINTS IN CEN KS FALLING INTO THE LOW 60S. STILL SEEING SOME HIGHER SFC DWPTS OVER SOUTHEAST KS...CLOSER TO THE MAIN BOUNDARY. EXPECT THE MAIN SHORTWAVE OVER NE NEB TO DROP SOUTHEAST INTO ERN KS AS THE AFTERNOON PROGRESSES. AS THIS INCREASED LIFT MOVES INTO SERN KS...THINK SOME REINVIGORATED SHOWERS/STORMS WILL DEVELOP WHERE THIS HIGHER SFC DWPT AIR AND UNSTABLE AIRMASS WILL BE LOCATED. SO WILL KEEP THE HIGHEST POPS ALONG THE KS/OK BORDER AND ESPECIALLY FOR SERN KS FOR THE LATE AFTERNOON HOURS. THINK THERE IS A SMALL WINDOW OF OPPORTUNITY FOR STORMS TO DEVELOP...AS THE DRIER AIR PUSHES INTO SRN KS...AND EVENTUALLY WITH THE FRONT DROPPING SOUTH INTO OK. SO THINK BY THE LATE AFTERNOON/EARLY EVENING HOURS...MOST OF THE CONVECTIVE CHANCES WILL DROP SOUTH OF THE AREA INTO OK. CURRENT POPS/GRIDS HAVE THIS TREND WILL IN HAND...WITH ONLY SOME MINOR TWEAKS FOR TIMING. KETCHAM && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH CENTRAL/SOUTHEAST KS. THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD OF THE FRONT. COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS. JMC .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH. THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME. JMC && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1244 PM CDT SUN SEP 1 2013 A WEAK COOL FRONT OVER SRN KS WILL CONTINUE TO PUSH SOUTH INTO OK LATE THIS AFTERNOON. EXPECTING VFR CONDITIONS EVEN WITH THE CLOUD COVER ACROSS THE AREA ASSOCIATED WITH THE BOUNDARY...WITH MOST LOCATIONS ALREADY SEEING A WIND SHIFT TO THE NORTH OR NORTHEAST. COULD ALSO SEE SOME SCATTERED SHRA FOR AREAS MAINLY EAST OF THE KS TURNPIKE...WITH A FEW RUMBLES OF THUNDER POSSIBLE GIVEN SOME LINGERING INSTABILITY IN THIS AREA. SO WILL GO WITH A VCTS FOR THE KCNU TAF FOR THE AFTN HOURS. WILL SEE VFR CONDITIONS EVEN WITH THE TSRA CHANCES. THINK CHANCES OF TSRA WILL END QUICKLY AFTER 02Z/MON AS THE BOUNDARY CONTINUES TO PUSH SOUTH INTO OK...WITH DRIER AIR PUSHING INTO MOST LOCATIONS. THIS DRIER AIR WILL ALSO LEAD TO A DIMINISHING CLOUD TREND FOR MOST OF CEN KS LATE AFTN INTO THIS EVE. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 90 64 88 64 / 100 10 0 0 HUTCHINSON 89 63 87 63 / 100 10 0 0 NEWTON 89 63 86 62 / 100 10 0 0 ELDORADO 90 64 86 62 / 90 10 0 0 WINFIELD-KWLD 95 65 89 64 / 30 10 0 0 RUSSELL 87 59 87 62 / 40 0 0 0 GREAT BEND 88 62 88 62 / 40 0 0 0 SALINA 89 61 87 62 / 30 0 0 0 MCPHERSON 89 62 87 62 / 30 0 0 0 COFFEYVILLE 95 66 88 64 / 30 10 0 0 CHANUTE 92 64 86 63 / 30 10 0 0 IOLA 91 63 86 62 / 30 10 0 0 PARSONS-KPPF 94 65 87 63 / 30 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1109 AM CDT SUN SEP 1 2013 .UPDATE... ISSUED AT 1108 AM CDT SUN SEP 1 2013 COOL FRONTAL BOUNDARY CONTINUES TO SLOWLY PUSH INTO SRN KS AT THIS TIME. CURRENTLY LOCATED FROM KDDC-KPTT TO JUST SOUTH OF KICT TO NEAR KCNU. SOME WIDELY SCT SHOWERS OR SPRINKLES ARE LOCATED ALONG THE FRONT...WITH MORE WIDESPREAD SHOWERS OVER ERN KS. EXPECT THIS FRONTAL BOUNDARY TO CONTINUE TO PUSH SOUTH INTO EXTREME SRN KS EARLY THIS AFTERNOON...AND EVENTUALLY PUSH INTO OK BY LATE THIS AFTERNOON/EARLY THIS EVENING. THE DRIER AIR ASSOCIATED WITH THIS BOUNDARY IS LAGGING BEHIND SOMEWHAT...WITH SFC DEWPOINTS IN CEN KS FALLING INTO THE LOW 60S. STILL SEEING SOME HIGHER SFC DWPTS OVER SOUTHEAST KS...CLOSER TO THE MAIN BOUNDARY. EXPECT THE MAIN SHORTWAVE OVER NE NEB TO DROP SOUTHEAST INTO ERN KS AS THE AFTERNOON PROGRESSES. AS THIS INCREASED LIFT MOVES INTO SERN KS...THINK SOME REINVIGORATED SHOWERS/STORMS WILL DEVELOP WHERE THIS HIGHER SFC DWPT AIR AND UNSTABLE AIRMASS WILL BE LOCATED. SO WILL KEEP THE HIGHEST POPS ALONG THE KS/OK BORDER AND ESPECIALLY FOR SERN KS FOR THE LATE AFTERNOON HOURS. THINK THERE IS A SMALL WINDOW OF OPPORTUNITY FOR STORMS TO DEVELOP...AS THE DRIER AIR PUSHES INTO SRN KS...AND EVENTUALLY WITH THE FRONT DROPPING SOUTH INTO OK. SO THINK BY THE LATE AFTERNOON/EARLY EVENING HOURS...MOST OF THE CONVECTIVE CHANCES WILL DROP SOUTH OF THE AREA INTO OK. CURRENT POPS/GRIDS HAVE THIS TREND WILL IN HAND...WITH ONLY SOME MINOR TWEAKS FOR TIMING. KETCHAM && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 APPARENT MCV OVER WEST-CENTRAL KS WAS DRIVING A BATCH OF CONVECTION OVER SOUTHWEST KS EARLY THIS MORNING WHICH THE HRRR TRACKS EAST-SOUTHEASTWARD WITH SOME WEAKENING TREND. OTHER STORM CLUSTERS EXTENDED ALONG THE COLD FRONT FROM NORTH CENTRAL KANSAS TO EASTERN NEBRASKA AND WERE MOVING SOUTHEAST. HAVE INCREASED STORM PROBABILITIES IN CENTRAL KS THIS MORNING BASED ON LATEST RADAR TRENDS. ISOLATED-WIDELY SCATTERED STORMS ARE POSSIBLE IN SOUTH CENTRAL/SOUTHEAST KS. THE COLD FRONT IS PROGGED TO BE PUSHING THROUGH CENTRAL KS AT MIDDAY...THEN CLEARING FAR SOUTHEAST KS EARLY THIS EVE. WILL MAINTAIN A 20-30% CHANCE OF STORMS THIS AFTERNOON IN THE SOUTH AS A RESULT. SOME COOLER AIR WILL PUSH INTO CENTRAL KS TODAY BEHIND THE FRONT...WITH HOT CONDITIONS IN THE FAR SOUTHERN COUNTIES JUST AHEAD OF THE FRONT. COOLER AND DRIER AIR WILL MOVE IN BEHIND THE FRONT TONIGHT INTO TUESDAY WITH MORE SEASONABLE TEMPERATURES. THIS WILL MAKE FOR VERY NICE WEATHER FOR LABOR DAY FOR THOSE WITH OUTDOOR PLANS. JMC .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 239 AM CDT SUN SEP 1 2013 THE UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE CENTRAL ROCKIES/HIGH PLAINS WEDNESDAY INTO THURSDAY...THEN PERSISTING INTO THE WEEKEND. THIS WILL LIKELY RESULT IN SLOWLY WARMING TEMPERATURES TO ABOUT 5-10 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. THE MAIN RAIN CHANCES LOOK TO REMAIN NORTH AND EAST OF OUR FORECAST AREA...AS VARIOUS SHORTWAVES RIDE OVERTOP OF AND AROUND THE UPPER HIGH. THEREFORE...EXTENDED FORECAST CONTINUITY LOOKS ON TRACK AT THIS TIME. JMC && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 640 AM CDT SUN SEP 1 2013 SCATTERED SHOWERS/THUNDERSTORMS ARE WEAKENING AT 12Z TAF ISSUANCE. HAVE INCLUDED A BRIEF PERIOD OF -SHRA IN TEMPO GROUPS FOR KRSL AND KSLN...BUT THE OUTLOOK FOR WIDESPREAD RAIN IS NOT GOOD. THE HRRR CONTINUES TO DIMINISH THE PRECIPITATION EXPANSE AS THE FRONT MOVES SOUTHWARD. THUS...IF KHUT/KICT OR KCNU SEES PRECIPITATION AN AMENDMENT WILL BE NEEDED. THE FRONT IS JUST BEHIND THE MAIN CONVECTION/SHOWER LINE. WINDS WILL SWITCH AROUND TO THE NORTH THIS MORNING AND ARE EXPECTED TO STAY FROM THE NORTH SWITCHING FROM NORTHWEST TO NORTHEAST THROUGH THE DAY. MID-HIGH CLOUDS WILL PERSIST UNTIL EVENING AS THE FRONT EXITS TO THE SOUTH. VFR CONDITIONS ARE EXPECTED TO PREVAIL. BILLINGS && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 90 64 88 64 / 100 10 0 0 HUTCHINSON 89 63 87 63 / 100 10 0 0 NEWTON 89 63 86 62 / 100 10 0 0 ELDORADO 90 64 86 62 / 90 10 0 0 WINFIELD-KWLD 95 65 89 64 / 30 10 0 0 RUSSELL 87 59 87 62 / 40 0 0 0 GREAT BEND 88 62 88 62 / 40 0 0 0 SALINA 89 61 87 62 / 30 0 0 0 MCPHERSON 89 62 87 62 / 30 0 0 0 COFFEYVILLE 95 66 88 64 / 30 10 0 0 CHANUTE 92 64 86 63 / 30 10 0 0 IOLA 91 63 86 62 / 30 10 0 0 PARSONS-KPPF 94 65 87 63 / 30 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1236 PM CDT Sun Sep 1 2013 .UPDATE... ISSUED AT 1235 PM CDT SUN SEP 1 2013 Beginning to be concerned for severe weather potential across southern Illinois this afternoon. Although the original convection moving through central Missouri has dissipated, the convective mesoscale vort center is now very obviously moving east southeast toward our region, and a few strong cells have developed just ahead it just southwest St Louis. Lots of sunshine and warming over the northern half of the southern Illinois should provide plenty of instability for the convectively generate disturbance to work with this afternoon. Increased pops to around 40 percent for scattered storms over much of southern Illinois. Also backed off temperatures a few degrees over much of southern Illinois and the Evansville Tri State area. UPDATE ISSUED AT 1212 PM CDT SUN SEP 1 2013 Update for 18z aviation. UPDATE ISSUED AT 1208 PM CDT SUN SEP 1 2013 Major update to all public products has just been sent. Looks like southeast Missouri may see scattered showers and thunderstorms through much of the day, as west southwesterly low-level flow continues to bang into the old outflow boundary. The severe storm complex over central Missouri is finally weakening, and would expect that trend to continue per the latest HRRR forecast. May see some anvil debris spread into our northwest counties through early afternoon, but do not expect this area to bodily move into our region this afternoon. The other concern is the Heat Advisory. Used a combination of the HRRR, which has a decent handle on the hot temperatures in the sunny northern portions of the area, and the 00Z ARW WRF which has the best handle I could find on the clouds, convection and temperatures over the south/southwest. Tried to indicate some decrease in cloud cover over the southwest, but kept temperatures in the middle 80s. Of course if the convection continues to stream over that area, the associated cloud cover may hold them down even more. Feel that the chance of a massive outbreak of sunshine over in that area is not likely, so have removed much of that area from the Heat Advisory. Over the north, not sure how much of an impact last night`s convection will have on high temperature potential with plentiful sunshine this afternoon. Decided to use the HRRR as a guide and go with mid 90s over this area, which leads to heat indices in the 100 to 105 range. Further adjustments will likely be needed this afternoon, so stay tuned. Also, not sure what impact the persistent Missouri convection will have on the thunderstorm potential across the area tonight. && .SHORT TERM...(Today through Tuesday Night) ISSUED AT 306 AM CDT SUN SEP 1 2013 A slight challenge with forecast package through 7 am CDT, as decent southwesterly flow aiding in decent surface thet-a convergence along western edge of complex. This should support renewed convective cell development westward along the upshear component over the expanding cold pool. The NAM-WRF and SREF guidance hint at this feature and continue to extend precipitation chances to the south and west through the morning hours. As CAPE increases duri9ng the afternoon, the focus of convection should shift to just south of the frontal boundary by late afternoon, aided by differential heating. For tonight, was a little more generous with the coverage and PoPs during the evening and early overnight hours. Once the forcing and instability shift southward before daybreak on Monday, rain chances should drop off quite rapidly along with significant clearing. The remainder of the short term forecast period should be dry and slightly cooler as northerly flow builds into the region. The last day of the heat advisory still looks good. Heat index values should spike into the low 100`s between 1 pm and 6 pm CDT ahead of the frontal boundary. See no reason to adjust the current advisory in effect. Anticipate the greatest severe threat will be late this afternoon and into the early evening over Southern IL/Southeast MO. Main concern for the remainder of the pre-dawn hours will be locally heavy rain and isolated strong winds gusts. .LONG TERM...(Wednesday through Saturday) ISSUED AT 306 AM CDT SUN SEP 1 2013 The mid level flow pattern will be more typical of what we have seen much of the summer, with the mean trof position over the east CONUS and the ridge over the west U.S. Generally dry weather is expected with temperatures slowly moderating each day back toward normal for this time of year. A front is forecast to backdoor the area Thur/Fri. But moisture profiles in both the GFS and ECMWF are not too impressive at this time. && .AVIATION... ISSUED AT 1209 PM CDT SUN SEP 1 2013 Placed thunder mention in kevv and kowb for this afternoon with clearing skies and mcv headed that way could see storms pre frontal. Kept mention of thunder tonight for fropa all sites. Low confidence in timing and coverage of precip. Also have wind shift this evening for fropa and some fog mention mainly at kevv and kowb due to the heavy rain that had already fallen there. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091. MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076. IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088. KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016- 018>020. && $$ UPDATE...DRS SHORT TERM...Smith LONG TERM...CN AVIATION...KH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1212 PM CDT Sun Sep 1 2013 .UPDATE... ISSUED AT 1208 AM CDT SUN SEP 1 2013 Update for 18z aviation. Major update to all public products has just been sent. Looks like southeast Missouri may see scattered showers and thunderstorms through much of the day, as west southwesterly low-level flow continues to bang into the old outflow boundary. The severe storm complex over central Missouri is finally weakening, and would expect that trend to continue per the latest HRRR forecast. May see some anvil debris spread into our northwest counties through early afternoon, but do not expect this area to bodily move into our region this afternoon. The other concern is the Heat Advisory. Used a combination of the HRRR, which has a decent handle on the hot temperatures in the sunny northern portions of the area, and the 00Z ARW WRF which has the best handle I could find on the clouds, convection and temperatures over the south/southwest. Tried to indicate some decrease in cloud cover over the southwest, but kept temperatures in the middle 80s. Of course if the convection continues to stream over that area, the associated cloud cover may hold them down even more. Feel that the chance of a massive outbreak of sunshine over in that area is not likely, so have removed much of that area from the Heat Advisory. Over the north, not sure how much of an impact last night`s convection will have on high temperature potential with plentiful sunshine this afternoon. Decided to use the HRRR as a guide and go with mid 90s over this area, which leads to heat indices in the 100 to 105 range. Further adjustments will likely be needed this afternoon, so stay tuned. Also, not sure what impact the persistent Missouri convection will have on the thunderstorm potential across the area tonight. && .SHORT TERM...(Today through Tuesday Night) ISSUED AT 306 AM CDT SUN SEP 1 2013 A slight challenge with forecast package through 7 am CDT, as decent southwesterly flow aiding in decent surface thet-a convergence along western edge of complex. This should support renewed convective cell development westward along the upshear component over the expanding cold pool. The NAM-WRF and SREF guidance hint at this feature and continue to extend precipitation chances to the south and west through the morning hours. As CAPE increases duri9ng the afternoon, the focus of convection should shift to just south of the frontal boundary by late afternoon, aided by differential heating. For tonight, was a little more generous with the coverage and PoPs during the evening and early overnight hours. Once the forcing and instability shift southward before daybreak on Monday, rain chances should drop off quite rapidly along with significant clearing. The remainder of the short term forecast period should be dry and slightly cooler as northerly flow builds into the region. The last day of the heat advisory still looks good. Heat index values should spike into the low 100`s between 1 pm and 6 pm CDT ahead of the frontal boundary. See no reason to adjust the current advisory in effect. Anticipate the greatest severe threat will be late this afternoon and into the early evening over Southern IL/Southeast MO. Main concern for the remainder of the pre-dawn hours will be locally heavy rain and isolated strong winds gusts. .LONG TERM...(Wednesday through Saturday) ISSUED AT 306 AM CDT SUN SEP 1 2013 The mid level flow pattern will be more typical of what we have seen much of the summer, with the mean trof position over the east CONUS and the ridge over the west U.S. Generally dry weather is expected with temperatures slowly moderating each day back toward normal for this time of year. A front is forecast to backdoor the area Thur/Fri. But moisture profiles in both the GFS and ECMWF are not too impressive at this time. && .AVIATION... ISSUED AT 1209 PM CDT SUN SEP 1 2013 Placed thunder mention in kevv and kowb for this afternoon with clearing skies and mcv headed that way could see storms pre frontal. Kept mention of thunder tonight for fropa all sites. Low confidence in timing and coverage of precip. Also have wind shift this evening for fropa and some fog mention mainly at kevv and kowb due to the heavy rain that had already fallen there. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091. MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076. IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088. KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016- 018>020. && $$ UPDATE...DRS SHORT TERM...Smith LONG TERM...CN AVIATION...KH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1108 AM CDT Sun Sep 1 2013 .UPDATE... ISSUED AT 1108 AM CDT SUN SEP 1 2013 Major update to all public products has just been sent. Looks like southeast Missouri may see scattered showers and thunderstorms through much of the day, as west southwesterly low-level flow continues to bang into the old outflow boundary. The severe storm complex over central Missouri is finally weakening, and would expect that trend to continue per the latest HRRR forecast. May see some anvil debris spread into our northwest counties through early afternoon, but do not expect this area to bodily move into our region this afternoon. The other concern is the Heat Advisory. Used a combination of the HRRR, which has a decent handle on the hot temperatures in the sunny northern portions of the area, and the 00Z ARW WRF which has the best handle I could find on the clouds, convection and temperatures over the south/southwest. Tried to indicate some decrease in cloud cover over the southwest, but kept temperatures in the middle 80s. Of course if the convection continues to stream over that area, the associated cloud cover may hold them down even more. Feel that the chance of a massive outbreak of sunshine over in that area is not likely, so have removed much of that area from the Heat Advisory. Over the north, not sure how much of an impact last night`s convection will have on high temperature potential with plentiful sunshine this afternoon. Decided to use the HRRR as a guide and go with mid 90s over this area, which leads to heat indices in the 100 to 105 range. Further adjustments will likely be needed this afternoon, so stay tuned. Also, not sure what impact the persistent Missouri convection will have on the thunderstorm potential across the area tonight. && .SHORT TERM...(Today through Tuesday Night) ISSUED AT 306 AM CDT SUN SEP 1 2013 A slight challenge with forecast package through 7 am CDT, as decent southwesterly flow aiding in decent surface thet-a convergence along western edge of complex. This should support renewed convective cell development westward along the upshear component over the expanding cold pool. The NAM-WRF and SREF guidance hint at this feature and continue to extend precipitation chances to the south and west through the morning hours. As CAPE increases duri9ng the afternoon, the focus of convection should shift to just south of the frontal boundary by late afternoon, aided by differential heating. For tonight, was a little more generous with the coverage and PoPs during the evening and early overnight hours. Once the forcing and instability shift southward before daybreak on Monday, rain chances should drop off quite rapidly along with significant clearing. The remainder of the short term forecast period should be dry and slightly cooler as northerly flow builds into the region. The last day of the heat advisory still looks good. Heat index values should spike into the low 100`s between 1 pm and 6 pm CDT ahead of the frontal boundary. See no reason to adjust the current advisory in effect. Anticipate the greatest severe threat will be late this afternoon and into the early evening over Southern IL/Southeast MO. Main concern for the remainder of the pre-dawn hours will be locally heavy rain and isolated strong winds gusts. .LONG TERM...(Wednesday through Saturday) ISSUED AT 306 AM CDT SUN SEP 1 2013 The mid level flow pattern will be more typical of what we have seen much of the summer, with the mean trof position over the east CONUS and the ridge over the west U.S. Generally dry weather is expected with temperatures slowly moderating each day back toward normal for this time of year. A front is forecast to backdoor the area Thur/Fri. But moisture profiles in both the GFS and ECMWF are not too impressive at this time. && .AVIATION... ISSUED AT 709 AM CDT SUN SEP 1 2013 With the 12z Sunday TAF issuance, kept all of the WFO PAH TAF sites in VFR category at this time. Until convective activity appears later on this afternoon and this evening, it is difficult to pinpoint at this time for lowered visibilities and ceilings. Utilized vicinity thunderstorm to approximate the time for convective activity near the sites. Slightly lower cloud decks or MVFR visibilities were added the KEVV/KOWB TAF`s to account for the approach of the frontal boundary. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY until 6 PM CDT this evening FOR ILZ075>078-080>091. MO...HEAT ADVISORY until 6 PM CDT this evening FOR MOZ076. IN...HEAT ADVISORY until 6 PM CDT this evening FOR INZ081-082-085>088. KY...HEAT ADVISORY until 6 PM CDT this evening FOR KYZ007-010-013>016- 018>020. && $$ UPDATE...DRS SHORT TERM...Smith LONG TERM...CN AVIATION...Smith
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
146 PM EDT SUN SEP 1 2013 .SYNOPSIS... A WEAK TROUGH OF LOW PRESSURE WILL PERSIST OVER THE AREA THROUGH TONIGHT...AS HIGH PRESSURE REMAINS WELL OFF THE COAST. A COLD FRONT WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL PUSH ACROSS THE AREA TUESDAY MORNING. HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC STATES LATE TUESDAY AND WEDNESDAY...BRINGING COOLER AND LESS HUMID CONDITIONS TO THE AREA BY MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/... 1 PM UPDATE...A SMALL CONVECTIVE VORT MAX APPEARS ON STLT TO BE MOVING ACROSS THE LOWER EASTERN SHORE. THIS MAY TRIGGER A FEW SHOWERS OR TSTMS THROUGH 18Z NEAR THE MD COAST WITH 30 POP THROUGH 18Z THEN 20 POP REST THE AFTN. A SIGNIFICANT CU FIELD HAS DEVELOPED ACRS NE NORTH CAROLINA AND EXTREME SOUTHEAST VIRGINIA IN THE SAME AREA THAT HRRR AND ARW HAVE TSTMS DEVELOP EARLY THIS AFTN, HAVE PLACED 30 PERCENT POPS FOR THE AFTN ACROSS A LARGE PART OF SOUTHEAST VIRGINIA AND OUR NORTHEAST NORTH CAROLINA COUNTIES. TEMPERATURES ARE RUNNING A BIT COOLER THAN EXPECTED OVER THE PIEDMONT AREA AND CU FIELD HAD NOT BEGUN TO FORM AS OF 16Z. . LOWERED MAX TEMPERATURES 1 TO 2 DEGREES AND LOWERED POPS TO 20 PERCENT THROUGH 20Z. PREVIOUS DISCUSSION... THE MAIN SHORT WAVE THAT WILL IMPACT THE AREA TOWARD EVENING WAS PUSHING INTO EXTREME SOUTHWEST VIRGINIA AS OF 16Z. SIMILAR TO SATURDAY...LEESIDE TROUGH WILL DEVELOP AS THE SHORT WAVE MOVES IN FROM THE WEST, EXPECT TSTMS TO DEVELOP NEAR THE BLUE RIDGE WITH CONVECTION SPREADING TO THE EAST TOWARD EVENING. CONTINUED WITH POPS 30-40 PERCENT W OF INTERSTATE 95 DECREASING TOWARD THE COAST. HIGH TEMPERATURES RANGE FROM THE UPR 80S TO AROUND 90 ACROSS MOST AREAS, PRECIPITIBLE WATER OF AROUND AN INCH AND THREE QUARTERS AND WEAK STEERING CURRENTS MAY RESULT IN LOCALLY HEAVY RAINFALL AND MINOR FLOODING. SOME TSTMS MAY PRODUCE GUSTY WINDS IN THE RANGE OF 30 TO 40 MPH. DUE TO RELATIVELY WEAK SHEAR...TSTMS SHOULD REMAIN SCATTERED. AFT 00Z...SHOWERS AND SCATTERED TSTMS WILL LINGER INTO THE EVENING AS THE SHORT WAVE MOVES ACRS NRN PORTIONS OF THE AREA. KEPT POPS OF 30 TO 40 PERCENT N OF INTERSTATE 64 AND ACROSS THE LOWER EASTERN SHORE THROUGH MIDNIGHT, BY MORNING...LOW TEMPERATURES RANGE FROM 70 TO 75. && .SHORT TERM /MONDAY THROUGH TUESDAY/... INCREMENTAL INCREASE IN POPS CONTINUES ON MONDAY, AS UPPER TROUGH PERSISTS AND SFC FRONT SLOWLY APPROACHES FROM THE W-NW. ONCE AGAIN EXPECT SHOWERS TO FIRE UPSTREAM AND FILL IN ALONG PRE-FRONTAL TROUGH, THOUGH DEVELOPING DOWNSLOPE FLOW AND CONTINUED ANEMIC DEEP LAYER SHEAR VALUES WOULD ARGUE FOR WEAKER/LESS ORGANIZED CELLS. EITHER WAY, DEEPER MOISTURE AND STRONGER DYNAMICS SUPPORT INCREASED CHC FOR SHOWERS AND TSTMS BY LABOR DAY AFTN/EVENING...AND WILL CARRY 50% POPS DURING THIS PERIOD. TEMPERATURES ARE A BIT OF A CHALLENGE CONSIDERING INCREASING AFTN CLOUDS AND RATHER STARK DIFFERENCE IN NUMERICAL GUIDANCE. ATTM, THINKING IS THAT MAV (GFS) GUIDANCE IS TOO HIGH...AS IT HAS BEEN NUMEROUS TIMES IN SIMILAR PRE-FRONTAL SITUATIONS. INCREASING CLOUDS/AFTN PCPN SHOULD KEEP MAXIMA BELOW THESE VALUES, AND CLOSER TO COOLER MET NUMBERS. DID ADJUST TEMPS UPWARD SLIGHTLY GIVEN SLOWER FRONTAL TIMING...WITH HIGHS MONDAY GENERALLY IN THE LOWER 90S (MID-UPPER 80S ALONG IMMEDIATE COASTAL AREAS). WARM AND MUGGY ONCE AGAIN MONDAY NIGHT, WITH EARLY MORNING LOWS IN THE LOWER TO MIDDLE 70S. TUESDAY... HAVE GONE CLOSEST TO THE ECMWF SOLUTION FOR FRONTAL TIMING, WHICH IS A GENERAL CONSENSUS OF THE MORE PROGRESSIVE 00Z GFS AND SLOWER NAM SOLUTION. EXPECT THE FRONT TO BE ORIENTED FROM THE MD ERN SHORE SW THROUGH SOUTH CENTRAL VA AT 12Z/8A TUE, WITH THE FRONT SLOWLY SLIDING SE OFF THE COAST BY TUE EVENING (00Z WED/8PM TUES NGT). UPPER JET LINGERS ALONG THE COAST HOWEVER, AND WITH UPPER TROUGH AXIS PIVOTING OFFSHORE DURING THIS PERIOD, EXPECT THAT AT LEAST SCATTERED SHRAS/TSTMS WL CONTINUE ACRS SE HALF OF THE AREA THROUGH TUE AFTN...WITH LESS COVERAGE FARTHER N/W AS COOLER/DRIER AIRMASS OF CANADIAN ORIGIN FILTERS IN FROM THE NW. HIGHS TUE WILL AVG IN THE MID-UPPER 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY STRONG MID LVL RIDGE OVER THE ROCKIES AND A MID LEVEL TROUGH OVER THE EASTERN CONUS. HIGH PRESSURE BUILDS IN FROM THE NW TUE NIGHT-WED IN THE WAKE OF SFC FROPA...AND PERSISTS OVER THE REGION INTO THU AS THE DEEP UPPER TROUGH BECOMES ANCHORED OVER EASTERN CANADA. EXPECT COOLER AND DRIER/MORE COMFORTABLE CONDITIONS WED WITH HIGHS MAINLY 80-85. FLOW BRIEFLY TURNS BACK TO THE SW ON THU ALLOWING FOR SOMEWHAT WARMER TEMPS INTO THE MIDDLE 80S AHEAD OF THE NEXT FRONT. THIS FRONT LOOKS TO COME THROUGH THU NIGHT/EARLY FRI WITH MINIMAL DYNAMICS SO WILL KEEP FORECAST DRY WITH JUST SOME INCREASE IN CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/ HIGHS 80-84. MOISTURE MAY START TO INCREASE AGAIN NEXT WEEKEND FOR SLIGHT CHC POPS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... NUMEROUS SHOWERS WITH EMBEDDED TSTRMS QUICKLY DVLPNG AS WEAK S/W MOVES CROSS THE DELMARVA ALONG WITH A SFC TROF EXTENDING SW ACROSS SERN VA / NC. THUS...HAVE INCLUDED VCSH ACROSS COASTAL TAF SITES NEXT SEVRAL HRS. ADDITIONAL CONVECTION EXPECTED TO DVLP ACROSS THE MTS THEN MOVE SE LATER THIS AFTRN. TIMING OF ANY CONVECTION AT RIC PROBLEMATIC ATTM SO KEPT THEM DRY FOR NOW. CONVECTION EXPECTED TO DISSIPATE AFTER SUNSET WITH VFR CONDITIONS THROUGH THE NIGHT. HOWEVER...MODELS HINTING THAT SOME LATE NIGHT FOG DEVELOPING...ESPECIALLY WHERE IT DOES RAIN. SO ADDED SOME MVFR VSBYS FOR BR OVER INLAND TAF SITES. ANOTHER ROUND OF SHOWERS / TSTRMS EXPECTED MONDAY AHEAD OF A COLD FRONT THAT WILL BRING IN A LESS HUID AIRMASS INTO THE REGION BY MID WEEK. && .MARINE... SURFACE AND MID LEVEL TROUGHING WILL RESIDE OVER THE REGION TODAY. AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE INLAND TROUGH AND ARE EXPECTED TO MOVE OVER THE WATERS MAINLY THIS EVENING...AND AFTER MIDNIGHT BECOMING MORE FOCUSED OVER NRN CHES BAY/NRN COASTAL WATERS. S-SW WINDS OVER ALL WATERS WILL AVERAGE 10-15 KT TODAY AND TONIGHT...AND WAVES/SEAS WILL AVERAGE 1-3 FT (POSSIBLY UP TO 4 FT OUT NEAR 20 NM EARLY MONDAY MORNING). A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON MONDAY. THIS WILL RESULT IN INCREASING SHOWER/THUNDERSTORM ACTIVITY BY MONDAY EVENING AS THE FRONT BEGINS TO PUSH OVER THE WATERS. THE FRONT SLOWLY PUSHES ACROSS THE WATERS ON TUESDAY AND STALLS ALONG THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL ALSO BE POSSIBLE ON TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW WINDS MONDAY AND TUESDAY WILL AVERAGE 10-15 KT (UP TO 20 KT AT TIMES FOR COASTAL WATERS)...THEN FINALLY VEER TO THE W-NW BEHIND THE FRONT TUESDAY NIGHT. A COOL NW-N SURGE TUESDAY NIGHT INTO WEDNESDAY MORNING MAY RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON THIS REMAINS UNCERTAIN. HIGH PRESSURE RE-ESTABLISHES ITSELF OVER THE MID ATLANTIC STATES FROM WEDNESDAY THROUGH AT LEAST SATURDAY. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...LSA SHORT TERM...LKB/MAM LONG TERM...JDM AVIATION...MPR MARINE...BMD
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1256 PM EDT SUN SEP 1 2013 .SYNOPSIS... A WEAK TROUGH OF LOW PRESSURE WILL PERSIST OVER THE AREA THROUGH TONIGHT...AS HIGH PRESSURE REMAINS WELL OFF THE COAST. A COLD FRONT WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL PUSH ACROSS THE AREA TUESDAY MORNING. HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC STATES LATE TUESDAY AND WEDNESDAY...BRINGING COOLER AND LESS HUMID CONDITIONS TO THE AREA BY MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/... 1 PM UPDATE...A SMALL CONVECTIVE VORT MAX APPEARS ON STLT TO BE MOVING ACROSS THE LOWER EASTERN SHORE. THIS MAY TRIGGER A FEW SHOWERS OR TSTMS THROUGH 18Z NEAR THE MD COAST WITH 30 POP THROUGH 18Z THEN 20 POP REST THE AFTN. A SIGNIFICANT CU FIELD HAS DEVELOPED ACRS NE NORTH CAROLINA AND EXTREME SOUTHEAST VIRGINIA IN THE SAME AREA THAT HRRR AND ARW HAVE TSTMS DEVELOP EARLY THIS AFTN, HAVE PLACED 30 PERCENT POPS FOR THE AFTN ACROSS A LARGE PART OF SOUTHEAST VIRGINIA AND OUR NORTHEAST NORTH CAROLINA COUNTIES. TEMPERATURES ARE RUNNING A BIT COOLER THAN EXPECTED OVER THE PIEDMONT AREA AND CU FIELD HAD NOT BEGUN TO FORM AS OF 16Z. . LOWERED MAX TEMPERATURES 1 TO 2 DEGREES AND LOWERED POPS TO 20 PERCENT THROUGH 20Z. PREVIOUS DISCUSSION... THE MAIN SHORT WAVE THAT WILL IMPACT THE AREA TOWARD EVENING WAS PUSHING INTO EXTREME SOUTHWEST VIRGINIA AS OF 16Z. SIMILAR TO SATURDAY...LEESIDE TROUGH WILL DEVELOP AS THE SHORT WAVE MOVES IN FROM THE WEST, EXPECT TSTMS TO DEVELOP NEAR THE BLUE RIDGE WITH CONVECTION SPREADING TO THE EAST TOWARD EVENING. CONTINUED WITH POPS 30-40 PERCENT W OF INTERSTATE 95 DECREASING TOWARD THE COAST. HIGH TEMPERATURES RANGE FROM THE UPR 80S TO AROUND 90 ACROSS MOST AREAS, PRECIPITIBLE WATER OF AROUND AN INCH AND THREE QUARTERS AND WEAK STEERING CURRENTS MAY RESULT IN LOCALLY HEAVY RAINFALL AND MINOR FLOODING. SOME TSTMS MAY PRODUCE GUSTY WINDS IN THE RANGE OF 30 TO 40 MPH. DUE TO RELATIVELY WEAK SHEAR...TSTMS SHOULD REMAIN SCATTERED. AFT 00Z...SHOWERS AND SCATTERED TSTMS WILL LINGER INTO THE EVENING AS THE SHORT WAVE MOVES ACRS NRN PORTIONS OF THE AREA. KEPT POPS OF 30 TO 40 PERCENT N OF INTERSTATE 64 AND ACROSS THE LOWER EASTERN SHORE THROUGH MIDNIGHT, BY MORNING...LOW TEMPERATURES RANGE FROM 70 TO 75. && .SHORT TERM /MONDAY THROUGH TUESDAY/... INCREMENTAL INCREASE IN POPS CONTINUES ON MONDAY, AS UPPER TROUGH PERSISTS AND SFC FRONT SLOWLY APPROACHES FROM THE W-NW. ONCE AGAIN EXPECT SHOWERS TO FIRE UPSTREAM AND FILL IN ALONG PRE-FRONTAL TROUGH, THOUGH DEVELOPING DOWNSLOPE FLOW AND CONTINUED ANEMIC DEEP LAYER SHEAR VALUES WOULD ARGUE FOR WEAKER/LESS ORGANIZED CELLS. EITHER WAY, DEEPER MOISTURE AND STRONGER DYNAMICS SUPPORT INCREASED CHC FOR SHOWERS AND TSTMS BY LABOR DAY AFTN/EVENING...AND WILL CARRY 50% POPS DURING THIS PERIOD. TEMPERATURES ARE A BIT OF A CHALLENGE CONSIDERING INCREASING AFTN CLOUDS AND RATHER STARK DIFFERENCE IN NUMERICAL GUIDANCE. ATTM, THINKING IS THAT MAV (GFS) GUIDANCE IS TOO HIGH...AS IT HAS BEEN NUMEROUS TIMES IN SIMILAR PRE-FRONTAL SITUATIONS. INCREASING CLOUDS/AFTN PCPN SHOULD KEEP MAXIMA BELOW THESE VALUES, AND CLOSER TO COOLER MET NUMBERS. DID ADJUST TEMPS UPWARD SLIGHTLY GIVEN SLOWER FRONTAL TIMING...WITH HIGHS MONDAY GENERALLY IN THE LOWER 90S (MID-UPPER 80S ALONG IMMEDIATE COASTAL AREAS). WARM AND MUGGY ONCE AGAIN MONDAY NIGHT, WITH EARLY MORNING LOWS IN THE LOWER TO MIDDLE 70S. TUESDAY... HAVE GONE CLOSEST TO THE ECMWF SOLUTION FOR FRONTAL TIMING, WHICH IS A GENERAL CONSENSUS OF THE MORE PROGRESSIVE 00Z GFS AND SLOWER NAM SOLUTION. EXPECT THE FRONT TO BE ORIENTED FROM THE MD ERN SHORE SW THROUGH SOUTH CENTRAL VA AT 12Z/8A TUE, WITH THE FRONT SLOWLY SLIDING SE OFF THE COAST BY TUE EVENING (00Z WED/8PM TUES NGT). UPPER JET LINGERS ALONG THE COAST HOWEVER, AND WITH UPPER TROUGH AXIS PIVOTING OFFSHORE DURING THIS PERIOD, EXPECT THAT AT LEAST SCATTERED SHRAS/TSTMS WL CONTINUE ACRS SE HALF OF THE AREA THROUGH TUE AFTN...WITH LESS COVERAGE FARTHER N/W AS COOLER/DRIER AIRMASS OF CANADIAN ORIGIN FILTERS IN FROM THE NW. HIGHS TUE WILL AVG IN THE MID-UPPER 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY STRONG MID LVL RIDGE OVER THE ROCKIES AND A MID LEVEL TROUGH OVER THE EASTERN CONUS. HIGH PRESSURE BUILDS IN FROM THE NW TUE NIGHT-WED IN THE WAKE OF SFC FROPA...AND PERSISTS OVER THE REGION INTO THU AS THE DEEP UPPER TROUGH BECOMES ANCHORED OVER EASTERN CANADA. EXPECT COOLER AND DRIER/MORE COMFORTABLE CONDITIONS WED WITH HIGHS MAINLY 80-85. FLOW BRIEFLY TURNS BACK TO THE SW ON THU ALLOWING FOR SOMEWHAT WARMER TEMPS INTO THE MIDDLE 80S AHEAD OF THE NEXT FRONT. THIS FRONT LOOKS TO COME THROUGH THU NIGHT/EARLY FRI WITH MINIMAL DYNAMICS SO WILL KEEP FORECAST DRY WITH JUST SOME INCREASE IN CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/ HIGHS 80-84. MOISTURE MAY START TO INCREASE AGAIN NEXT WEEKEND FOR SLIGHT CHC POPS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... SURFACE TO MID LEVEL TROUGHING RESIDES OVER THE MID ATLANTIC REGION EARLY THIS MORNING AND IS EXPECTED TO REMAIN STEADFAST THROUGH TODAY. THERE ARE PLENTY OF HIGH DEBRIS CLOUDS AND FEW-SCT MID LEVEL CU LEFT FROM SHOWERS ON SATURDAY EVENING. VERY DIFFUSE DRY SLOTTING CAN BE SEEN IN WATER VAPOR IMAGERY AND MAY LEAD TO SOME THINNING OF THE BKN-OVC CIRRUS THROUGH THE MORNING. HOWEVER ONCE DAYTIME HEATING BEGINS...EXPECT MORE CU DEVELOPMENT TO OCCUR FROM LATE MORNING INTO THE AFTERNOON. MEANWHILE...SHORTWAVE ENERGY FROM THE OHIO VALLEY WILL SLIDE CLOSER TO THE APPALACHIANS AND INTERACT WITH THE TROUGHING CURRENTLY IN PLACE. THIS WILL PROMOTE SHOWER/THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON INTO THE EVENING...AND SHOULD RESULT IN PRECIPITATION SHIFTING FARTHER EAST THAN THE DAY BEFORE. SHOWERS/STORMS MAY HAVE A TOUGH TIME REACHING ALL THE WAY TO THE COAST DUE TO THE LOSS OF DAYTIME HEATING BY THE TIME THE MOISTURE ARRIVES AND ALSO DUE TO POSSIBLE DRY SLOTTING. KRIC AND KSBY HAVE THE BEST CHANCE OF EXPERIENCING THUNDERSTORMS TODAY INTO TONIGHT...WHILE KPHF/KORF/KECG MAY SEE A SHOWER OR TWO BUT THAT SHOULD BE IT. SHOWERS AND STORMS SHOULD TAPER OFF QUICKLY AFTER MIDNIGHT...WITH LINGERING SHOWERS POSSIBLE OVERNIGHT IN AREAS NE OF INTERSTATE 64 (INCLUDING THE MD/VA EASTERN SHORE). SOUTH WINDS WILL BECOME BREEZY BY MID TO LATE MORNING AS THE PRESSURE GRADIENT TIGHTENS UP AGAIN THROUGH THE AFTERNOON. A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON MONDAY. THIS WILL RESULT IN INCREASED SHOWER/THUNDERSTORM CHANCES AND COVERAGE BY MONDAY EVENING AS THE FRONT STARTS TO PUSH INTO THE REGION. THE FRONT SLOWLY PUSHES ACROSS THE AREA ON TUESDAY AND STALLS ALONG THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL BE POSSIBLE ON TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW WINDS FINALLY VEER TO THE W-NW BEHIND THE FRONT LATE TUESDAY. HIGH PRESSURE RE-ESTABLISHES ITSELF OVER THE MID ATLANTIC STATES FROM WEDNESDAY THROUGH AT LEAST SATURDAY. && .MARINE... SURFACE AND MID LEVEL TROUGHING WILL RESIDE OVER THE REGION TODAY. AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE INLAND TROUGH AND ARE EXPECTED TO MOVE OVER THE WATERS MAINLY THIS EVENING...AND AFTER MIDNIGHT BECOMING MORE FOCUSED OVER NRN CHES BAY/NRN COASTAL WATERS. S-SW WINDS OVER ALL WATERS WILL AVERAGE 10-15 KT TODAY AND TONIGHT...AND WAVES/SEAS WILL AVERAGE 1-3 FT (POSSIBLY UP TO 4 FT OUT NEAR 20 NM EARLY MONDAY MORNING). A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON MONDAY. THIS WILL RESULT IN INCREASING SHOWER/THUNDERSTORM ACTIVITY BY MONDAY EVENING AS THE FRONT BEGINS TO PUSH OVER THE WATERS. THE FRONT SLOWLY PUSHES ACROSS THE WATERS ON TUESDAY AND STALLS ALONG THE COAST TUESDAY NIGHT. SHOWER/STORMS WILL ALSO BE POSSIBLE ON TUESDAY...ESPECIALLY ALONG THE FRONTAL BOUNDARY. BREEZY S-SW WINDS MONDAY AND TUESDAY WILL AVERAGE 10-15 KT (UP TO 20 KT AT TIMES FOR COASTAL WATERS)...THEN FINALLY VEER TO THE W-NW BEHIND THE FRONT TUESDAY NIGHT. A COOL NW-N SURGE TUESDAY NIGHT INTO WEDNESDAY MORNING MAY RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON THIS REMAINS UNCERTAIN. HIGH PRESSURE RE-ESTABLISHES ITSELF OVER THE MID ATLANTIC STATES FROM WEDNESDAY THROUGH AT LEAST SATURDAY. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...LSA SHORT TERM...LKB/MAM LONG TERM...JDM AVIATION...BMD MARINE...BMD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
402 PM EDT SUN SEP 1 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 401 PM EDT SUN SEP 1 2013 12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PAIR OF VIGOROUS SHRTWVS DIGGING THRU ONTARIO/LK SUP IN THE NW FLOW ALF BTWN RDG OVER THE ROCKIES AND A TROF OVER ERN NAMERICA. WHILE DRYING ALF UNDER DNVA/UPR CONFLUENCE/DEEP LYR QVECTOR DVGC IN THE WAKE OF THE MOST IMPRESSIVE SHRTWV MOVING ACRS NRN LK SUP HAS ENDED THE SHRA OVER THE SW CWA...MORE NMRS SHRA/TS IN THE COMMA TAIL IN ADVANCE OF RATHER WEAK ATTENDANT COLD FNT...WHERE RUC ANALYSIS SHOWS KINX NOT FAR FM 40/STEEPER MID LVL LAPSE RATES/MUCAPE IN THE 500-1000J/KG RANGE... ARE MOVING THRU THE ERN ZNS. MORE NMRS SHRA/TS ALSO IMPACTED THE KEWEENAW EARLIER IN THE DAY CLOSER TO THE COMMA HEAD ASSOCIATED WITH THIS SHRTWV. THE MAIN HAZARD FM ALL THE SHRA/TS HAVE BEEN HEAVY DOWNPOURS...WHICH PROMPTED THE ISSUANCE OF AN URBAN/SMALL STREAM FLOOD ADVY FOR THE KEWEENAW EARLIER IN THE AFTN FOLLOWING A REPORT OF 2 INCHES OF RA IN AN HOUR NEAR CALUMET. EVEN THOUGH THERE HAS BEEN DRYING ALF OVER THE W IN THE WAKE OF THE WEAK SFC COLD FROPA...A FEW -SHRA HAVE DVLPD IN THIS AREA ALONG WITH SOME LO CLDS AS LLVL MSTR SHOWN ON THE 12Z INL RAOB HAS OVERSPREAD THE AREA IN THE NW LLVL FLOW IN THE WAKE OF THE SHRTWV. LARGE SCALE QVECTOR DVGC/SUBSIDENCE IN THE WAKE OF THE DEPARTING SHRTWV HAVE TENDED TO LIMIT THE INTENSITY OF THESE -SHRA. THERE IS A SHARPER SURGE OF COOL AIR ASSOCIATED WITH THE SECOND SHRTWV DROPPING SSEWD IN NW ONTARIO. LO CLDS ARE WIDESRPEAD TO THE NW OF LK SUP WITH SOME -RA/-DZ REPORTED IN THE CYC FLOW ON THE NW FLANK OF SFC LO PRES MOVING THRU LK SUP THAT ASSOCIATED WITH THE FIRST SHRTWV. REST OF THIS AFTN/TNGT...EXPECT LINGERING SHRA/TS OVER THE ERN ZNS LATE THIS AFTN TO SHIFT TO THE E FOLLOWING DEPARTURE OF AXIS OF HIER RH/DEEP LYR QVECTOR CNVGC AND UNDER DEEP LYR QVECTOR DVGC BEHIND DEPARTING FIRST SHRTWV. FOLLOWING THE PASSAGE OF REINFORCING COLD FNT EARLY THIS EVNG ASSOCIATED WITH THE SECOND SHRTWV DIGGING THRU ONTARIO...EXPECT WIDESPREAD LO CLD/SOME -DZ TO DVLP ESPECIALLY IN THE UPSLOPE AREAS NEAR LK SUP AS LLVL NNW FLOW DRIVES NEAR SFC COOL AIR INTO THE AREA AND SHARPENS INVRN BASE NEAR H9 AS SHOWN ON 12Z LOCAL WRF ARW FCST SDNGS. THE COMBINATION OF GUSTY WINDS WITH H925 WINDS FCST UP TO 25-30 KTS AND THE ARRIVAL OF THE COOLER AIR WL MAKE THE NGT FEEL QUITE CHILLY AS COMPARED TO THE WARM WX IN RECENT WEEKS. LABOR DAY...MON WL FEATURE A CONFLUENT NW FLOW OVER THE UPR LKS/DEEP LYR QVECTOR DVGC. MAIN FCST CONCERN IS HOW QUICKLY LO CLDS/-DZ WITH SHALLOW MOIST LYR BLO SHARP LLVL INVRN WL DEPART. GIVEN THE INTENSITY OF THE DISTURBANCES IN PLAY TODAY...PREFERRED TO FOLLOW THE 12Z LOCAL WRF-ARW FCST SCENARIO...WHICH SHOWS MORE PERSISTENT LLVL MSTR MAINTAINED BY STRONGER N WIND. BUT EVEN THIS MODEL INDICATES SOME IMPROVEMENT IN THE AFTN ESPECIALLY OVER THE W HALF WITH CLOSER APRCH OF SFC HI PRES/WEAKER AND MORE ACYC FLOW. EXPECT THE RETURN OF AT LEAST SOME SUNSHINE IN THAT AREA AFT 18Z. TEMPS WL RUN BLO NORMAL FOR THE FIRST TIME IN QUITE AWHILE. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 401 PM EDT SUN SEP 1 2013 QUITE A TRANQUIL PERIOD OF WEATHER EXPECTED OVER THE NEXT WEEK AS LARGE SCALE FEATURES TREND BACK TO THE EARLY SUMMER SET-UP OF A WESTERN RIDGE AND EASTERN TROUGH. TEMPERATURES SHOULD BE AT TO SLIGHTLY ABOVE NORMAL THROUGH THE WEEK. MONDAY NIGHT THROUGH TUESDAY NIGHT...A STRONG MID-LEVEL SHORTWAVE TROUGH AND AN ACCOMPANYING SFC LOW WILL BE OVER THE SOUTHEAST ONTARIO AND QUEBEC BORDER AT THE START OF THE PERIOD...AND WILL BE CONTINUING TO MOVE EAST MONDAY NIGHT. MEANWHILE...MID-LEVEL RIDGING WILL BE BUILDING INTO THE UPPER MS VALLEY AS A SFC HIGH PRESSURE SETTLES OVER OVER NW TO CENTRAL WI. MAIN QUESTIONS IN THIS TIME FRAME REVOLVE AROUND DEPARTING LOW CLOUD COVER IN THE EAST...AND MIN TEMPS FOR THE WEST. INCREASINGLY DRIER AIR WILL CONTINUE ADVECTING INTO THE REGION FROM THE NW AHEAD OF THE SFC HIGH. ATTM...IT APPEARS THAT LOW-CLOUDS UNDER AN H8 INVERSION SHOULD DISSIPATE ENOUGH FROM INSOLATION AND INCOMING DRY AIR TO RESULT IN MOSTLY CLEAR SKIES FOR THE WEST HALF. THE EAST HALF IS A BIT MORE TRICKY...WITH THE NAM NON-SURPRISINGLY KEEPING LOW STRATUS ACROSS THE AREA WELL INTO THE OVERNIGHT HOURS. OVERALL...FEELING IS THAT CLOUDS WILL CLEAR OUT BY MIDNIGHT FOR THE EAST. WITH THE GRADIENT FLOW WEAKENING ACROSS THE WEST...AND PWAT VALUES AROUND 0.5 INCHES...GOOD RADIATIONAL COOLING IS EXPECTED. HAVE FORECAST TEMPS IN THE LOW 40S INTERIOR WEST...WITH EVEN A COUPLE POCKETS OF UPPER 30S. LOWS SHOULD REMAIN AROUND 50 ALONG THE GREAT LAKES...AND ACROSS THE EAST HALF WHERE GRADIENT FLOW REMAINS STRONGER THROUGHOUT THE NIGHT. BROAD RIDGING MOVES ACROSS THE UPPER GREAT LAKES ON TUESDAY...AND WILL BRING SUNNY SKIES WITH TEMPS WARMING TO THE MID 70S. RETURN FLOW ON THE BACKSIDE OF THE SFC HIGH ALONG WITH INCREASING MID-LEVEL CLOUDS SHOULD KEEP TEMPS FROM FALLING OFF TOO MUCH TUESDAY...WITH COLDEST LOWS ONLY IN THE UPPER 40S. PLENTY OF DRY AIR ABOVE THE INVERSION SHOULD ALLOW RH VALUES TO FALL INTO THE MID 30S TO AROUND 40 FOR INTERIOR LOCATIONS...THOUGH WINDS WILL BE QUITE LIGHT. WEDNESDAY...A STRENGTHENING SHORTWAVE ACROSS NORTHERN CANADA WILL QUICKLY TRACK SOUTHEAST ACROSS NORTHERN MANITOBA ON TUESDAY...AND SOUTHERN HUDSON BAY TUESDAY NIGHT INTO WEDNESDAY MORNING. AN ASSOCIATED STRENGTHENING SFC LOW WILL SEND A COLD FRONT FROM NORTH TO SOUTH ACROSS THE CWA LATE TUESDAY NIGHT INTO WEDNESDAY. NEARLY ALL FORCING BY WAY OF MID-LEVEL Q-VECTOR CONVERGENCE WILL STAY WELL NORTH AND EAST OF THE AREA. GIVEN LIMITED MOISTURE WITH THIS SYSTEM...DO NOT EXPECT ANYTHING MORE THAN SOME SCATTERED TO BROKEN MID-LEVEL CLOUDINESS. ONE EXCEPTION COULD BE A BRIEF BOUT OF POST-FRONTAL UPSLOPE DRIZZLE ACROSS THE NORTH-CENTRAL CWA...BUT WITH DRY AIR MOVING IN QUICKLY BEHIND THE FRONT...LEFT OUT OF THE FCST FOR NOW. THE ECMWF HAS BEEN ON THE FASTER END OF GUIDANCE WITH THE PASSAGE OF THE FRONT...CLEARING MUCH OF THE CWA BY NOON. THE GFS HAD BEEN SEVERAL HOURS SLOWER...NOT CLEARING THE CWA UNTIL MID TO LATE AFTERNOON. HOWEVER...IT HAS TRENDED 3 TO 5 HOURS QUICKER OVER THE LAST SEVERAL RUNS...AND NOW LINES UP MUCH BETTER WITH THE ECMWF. WILL FOLLOW THE IDEA OF A QUICKER FRONTAL PASSAGE. STRENGTHENING HIGH PRESSURE TRACKING SOUTHEASTWARD INTO THE UPPER MS VALLEY BEHIND THE FRONT WILL INDUCE A MODEST ISALLOBARIC WIND COMPONENT AND BRING A WINDOW OF BREEZY CONDITIONS WEDNESDAY MORNING...PRODUCING AN ELEVATED SWIM RISK FOR WEDNESDAY. WEDNESDAY NIGHT THROUGH SUNDAY...HIGH PRESSURE WILL SETTLE OVER THE AREA WEDNESDAY NIGHT AND ALLOW TEMPS TO ONCE AGAIN FALL WELL INTO THE 40S FOR INTERIOR LOCATIONS. DEEP TROUGHING IN THE WEST WILL DEVELOP BY LATE IN THE WEEK AND DOMINATE THE PATTERN ACROSS THE NE CONUS. A COUPLE OF WEAK SHORTWAVES WILL TRACK ALONG THE BACKSIDE OF THIS TROUGH AND AFFECT THE CWA. TIMING AND STRENGTH ARE TYPICALLY DIFFICULT TO PIN DOWN IN THIS TYPE OF FLOW REGIME...SO WILL USE CONSENSUS FORECAST THROUGH THE WEEKEND. WITH THAT SAID...BEST CHANCE TO SEE SOME ISOLATED SHOWERS AND A FEW THUNDERSTORMS WILL BE FRIDAY AND FRIDAY NIGHT AS A COLD FRONT DROPS SOUTH THROUGH THE REGION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 123 PM EDT SUN SEP 1 2013 OVERALL MVFR/VFR CONDITIONS THIS AFTN WL FALL TO IFR AT ALL 3 SITES BY THIS EVNG FOLLOWING THE PASSAGE OF A COLD FNT AND THE DVLPMNT OF A GUSTY UPSLOPE NNW WIND UNDER A SHARPENING PRES GRADIENT. SOME -DZ/SPRINKLES ARE LIKELY AS WELL. AS THE GRADIENT/ UPSLOPE WIND COMPONENT DIMINISH LATE TNGT/MON MRNG...CONDITIONS WL GRDLY IMPROVE TO MVFR AND ANY LGT PCPN WL END. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 401 PM EDT SUN SEP 1 2013 FOLLOWING A COLD FRONTAL PASSAGE LATE THIS AFTERNOON/EARLY EVENING...EXPECT NNW WINDS UP TO 30 KTS TO DEVELOP OVER THE LAKE AND CONTINUE INTO MON...WHEN A HI PRES APPROACHING THE UPPER LAKES WILL CAUSE THE WINDS TO DIMINISH WEST-TO-EAST THRU MON NIGHT. LOOK FOR LIGHTER WINDS ON TUE AS THE HI PRES MOVES OVER THE UPPER LAKES. STRONGER NNW WINDS UP TO 25 KTS WILL DEVELOP OVER THE E HALF ON WED FOLLOWING ANOTHER COLD FRONTAL PASSAGE. THEN WINDS SHOULD DIMINISH QUICKLY THE REST OF THE WEEK AS ANOTHER HI PRES/WEAK PRES GRADIENT MOVE OVER THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... BEACH HAZARDS STATEMENT FROM 8 PM EDT THIS EVENING THROUGH LATE MONDAY NIGHT FOR MIZ005-006. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KLUBER AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS GAYLORD MI
158 PM EDT SUN SEP 1 2013 .SYNOPSIS... ISSUED AT 352 AM EDT SUN SEP 1 2013 A COLD FRONT WILL MOVE IN FROM THE WEST TODAY...BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS...THOUGH TEMPERATURES WILL REMAIN RATHER WARM. BEHIND THE FRONT...ON LABOR DAY...IT WILL FEEL MUCH MORE LIKE AUTUMN. MAINLY DRY AND SOMEWHAT WARMER WEATHER IS EXPECTED FOR THE REMAINDER OF THE WEEK. && .UPDATE... ISSUED AT 158 PM EDT SUN SEP 1 2013 POTENT SHORT WAVE AND ATTENDING SFC LOW CONTINUES TO ADVANCE THROUGH UPPER MICHIGAN/LAKE SUPERIOR THIS AFTERNOON...ASSOCIATED COLD FRONT TRAILS DOWN THROUGH EAST-CENTRAL WISCONSIN. NICE BATCH OF SHOWERS/THUNDER ADVANCING INTO ROUGHLY THE NRN HALF OF THE CWA RIGHT ALONG THE EASTERN FRINGE OF THE SHORT WAVE...AND WITHIN A NARROW CORRIDOR OF INSTABILITY ABOUT TO PUSH THROUGH THE REGION. CONVECTION IS WEAKENING...RUNNING OUT AHEAD OF THE STRONGEST FORCING AND INTO DECREASED INSTABILITY DOWNSTREAM. BUT HAVE LONG AGO UPDATED POPS TO HAVE A PERIOD OF CATEGORICAL PRECIP ACROSS THE NRN PART OF THE CWA...TRAILING OFF TO NOTHING SOUTH OF M-72. REST OF THE AFTERNOON...INITIAL BATCH OF PRECIP WILL WORK THROUGH THE NORTH OVER THE NEXT FEW HOURS. COLD FRONT STILL HAS TO COME THROUGH THE REGION. STRATUS IS STARTING TO THIN ACROSS NRN LOWER MICHIGAN WITH TEMPS STARTING TO WARM NICELY. STILL THINK THERE WILL BE A WINDOW OF OPPORTUNITY FOR CONVECTION LATER THIS AFTERNOON AS THE FRONT/COOLING ALOFT PRESSES THROUGH THE REGION... PARTICULARLY OVER NE LOWER MICHIGAN WHERE CONVERGENCE WILL BE MAXIMIZED. UPDATE ISSUED AT 1032 AM EDT SUN SEP 1 2013 OVERVIEW: COMPACT SHORT WAVE NOW ADVANCING THROUGH THE WESTERN U.P./WESTERN LAKE SUPERIOR. ATTENDING SFC LOW LOCATED OVER THE KEWEENAW PENINSULA AS OF 14Z WITH A COLD FRONT STRETCHING DOWN THROUGH CENTRAL WISCONSIN. AHEAD OF THE FRONT...12Z GRB/APX SOUNDINGS REVEAL A FAIRLY DRY LOWER LEVEL AIRMASS IN PLACE AND SFC BASED CAP UP THROUGH AROUND 800 MB OR SO. BUT...THERE IS A THIN RIBBON OF MODEST LOW LEVEL MOISTURE (850 THETA-E RIDGE) JUST ALONG THE FRONT IN CENTRAL WISCONSIN... WRAPPING INTO THE LOW OVER LAKE SUPERIOR. COUPLED WITH COOLING LOWER LEVELS WITH THE SFC FRONT AND UPPER WAVE...HAS PRODUCED A NARROW CORRIDOR OF INSTABILITY THAT IS ADVANCING EASTWARD... EVIDENCED BY THE BKN LINE OF CONVECTION THAT WRAPS ALONG THE LEADING EDGE OF THE SHORT WAVE. FORECAST FOR THIS AFTERNOON/EVENING IS COMPLICATED BY A NUMBER OF FACTORS...INCLUDING...BUT NOT LIMITED TO...MORNING STRATUS AND FOG THAT WILL MOST CERTAINLY INHIBIT HEATING AND INSTABILITY AT LEAST FOR AWHILE...AS WELL AS SMALLER SCALE AFFECTS ON THE LOW LEVEL WIND FIELD INDUCED BY THE LAKES THAT WILL IMPACT FRONTAL POSITION AND ULTIMATELY LOW LEVEL CONVERGENCE. THROUGH EARLY AFTERNOON...ONGOING CONVECTION UPSTREAM SHOULD BASICALLY HIT A "CINH" WALL AS IT TRIES TO ADVANCE INTO THIS CWA...ESSENTIALLY OUTRUNNING THE FORCING AND AFOREMENTIONED NARROW CORRIDOR OF INSTABILITY. SO...EXPECT MUCH OF THE CURRENT ACTIVITY TO FIZZLE. MAIN EXCEPTION...ACROSS UPPER MICHIGAN ALONG THE SHORT WAVE TRACK WHERE STRONGEST QG-FORCING WILL PROBABLY SUSTAIN SHOWERS INTO EASTERN UPPER MICHIGAN PAST LUNCH TIME. THEN...UPSTREAM SFC FRONT WILL TRY TO ADVANCE INTO THE CWA DURING THE COURSE OF THE AFTERNOON...ALTHOUGH DUE TO LAKE INDUCED CHANGES IN THE LOW LEVEL WIND FIELD...FRONT AND ASSOCIATED LOW LEVEL CONVERGENCE WILL LIKELY LOSE IT/S IDENTITY. FRONT MAY "JUMP" INTO NORTHEAST LOWER MICHIGAN THIS AFTERNOON AIDED BY SE FLOW OF LAKE HURON. PROVIDED WE CAN EVENTUALLY THIN OUT THE STRATUS AND FOG BY EARLY-MID AFTERNOON...WE MIGHT BE ABLE TO GENERATE SOME INSTABILITY AS THE AFOREMENTIONED LOWER LEVEL MOISTURE AXIS NOSES UP THROUGH NE LOWER MICHIGAN ALONG THE FRONT. WILL SEE HOW THIS GOES. BUT AT THIS POINT...THE BEST PRECIP CHANCES THROUGH THIS EVENING ARE SETTING UP FOR EASTER UPPER MICHIGAN (ALONG THE SHORT WAVE TRACK)...AS WELL AS NORTHEAST LOWER...THAT IS IF WE CAN MUSTER SOME HEATING AND DESTABILIZATION. CERTAINLY NOT A RAIN OUT EVENT BY ANY STRETCH. BUT FOLKS MAKING OUTDOOR HOLIDAY PLANS SHOULD AT LEAST PLAN FOR THE POTENTIAL FOR A PERIOD OF SHOWERS AND SOME THUNDER...ESPECIALLY IN EASTERN UPPER AND NORTHEAST LOWER. SEVERE THREAT...AGAIN INSTABILITY DEPENDENT. WIDESPREAD SEVERE WEATHER NOT ANTICIPATED. BUT...MID LEVEL FLOW DOES INCREASE TO 35 TO 4O KNOTS ALONG THE FRONT...LEADING TO SOME BULK SHEAR TO CAPITALIZE ON. COMBINED WITH BACKED FLOW OFF LAKE HURON...ANY STORMS THAT MANAGE TO DEVELOP IN NE LOWER MICHIGAN WILL BEAR SCRUTINY. UPDATE ISSUED AT 703 AM EDT SUN SEP 1 2013 STRATUS HAS BECOME FAIRLY WIDESPREAD COMING IN OFF LAKE HURON...AND AIDED BY EXCELLENT COOLING OF THE BL. FOG ALSO WAS COMMON...BUT NOT WIDESPREAD...YET DENSE IN SPOTS. STRATUS WILL LIKELY LINGER FOR A BIT...WHILE HIGHER LEVEL CLOUDS STREAM IN FROM THE WEST. ALSO...A CLUSTER OF SHOWERS AND STORMS WILL ROLL IN FROM NE WISCONSIN/CENTRAL UPPER...AND LIKELY SCRAPE WESTERN SECTIONS OF CHIP/MACK...MAYBE FAR NRN LAKE MICHIGAN. NOT TOTALLY SURE OF THE EVOLUTION OF THIS PRECIP...AS IT SHOULD BE MORE DRIVEN BY THE H8 WESTERLY LLJ OUT TO OUR WEST. THAT SAID...UPPER LEVEL SHORTWAVE WILL ALREADY BE THROWING SOME ENERGY IN ACROSS THESE AREAS AS WELL. WILL START CHANCES FOR RAIN A COUPLE HOURS EARLIER...MID MORNING FOR EASTERN UPPER. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 352 AM EDT SUN SEP 1 2013 CONDITIONS ARE SET TO CHANGE OVER THE NEXT 24-30 HRS...AS A COLD FRONT WILL BLOW THROUGH THE REGION WITH WARM/MUGGY SUMMER WEATHER WILL TURN MUCH COOLER AND BREEZY FOR THE START OF NEXT WORK WEEK. MAIN ISSUE IS THE STRENGTH AND COVERAGE OF SHOWERS AND STORMS WITH THE FRONT. CURRENTLY...CLEARLY EVIDENT SHORTWAVE SEEN DROPPING SE ACROSS FAR NRN MN WITH ASSOCIATED SFC LOW PRESSURE OVER THE ARROWHEAD. A COLD FRONT EXTENDED FROM THIS LOW PRESSURE BACK ACROSS MN AND FAR FAR NW IOWA. SHOWERS AND STORMS HAVE REALLY FALLEN APART ACROSS THE ENTIRE FRONT...WITH LOSS OF DIURNAL HEATING. LATEST RUC ANALYSIS SHOWING PRESENCE OF AN ELEVATED WARM FRONT WITH 30-35KTS OF A WESTERLY JET...WARM/MOIST CONVERGENCE PIN-POINTED ON EASTERN UPPER. SKIES WERE CLEAR HOWEVER...WITH ONLY SOME THIN HIGH LEVEL CLOUDS IN EASTERN UPPER FROM EARLIER SHOWERS AND STORMS ACROSS WISCONSIN. THESE CLOUDS AND EVEN PRECIP HAD PROBLEMS HOLDING TOGETHER AS THEY WORKED THEIR WAY WEST INTO RELATIVELY DRIER AIR MASS CENTERED RIGHT OVER NRN MICHIGAN. DID SEE A FEW LIGHT RAIN SHOWERS/SPRINKLES DOTTING EASTERN UPPER...OTHERWISE...THERE WAS ABSOLUTELY NO PRECIP NEAR NRN MICHIGAN. THE MAIN ACTION WAS STUCK ACROSS IOWA IN BETTER LOW LEVEL CONVERGENCE AND INSTABILITY. A MUGGY SFC AIR MASS AND THE CLEAR SKIES HAS RESULTED IN PATCHY AREAS OF FOG THAT HAS BEEN LOCALLY DENSE. TEMPERATURES IN UPPER 50S TO LOWER HALF OF THE 60S FOR MOST. TODAY AND TONIGHT...SOME ADDITIONAL UPSTREAM HIGH LEVEL CLOUDS WILL SWEEP IN OVER THE AREA 09-12Z...ESPECIALLY EASTERN UPPER...BUT WILL LIKELY STILL HAVE A HARD TIME NOT THINNING EVEN MORE. THUS...BELIEVE THE SKY COVER WILL BE RATHER CLEAR FOR ALL TO START THE DAY. CHANCES FOR PRECIPITATION WERE REMOVED THROUGH 15Z BASED ON THE AFOREMENTIONED. A DECENT WARMING PERIOD WILL GET TEMPERATURES IN THE UPPER 70S NORTH...TO THE LOWER HALF OF THE 80S IN NRN LOWER TODAY. WINDS WILL BE LIGHT OUT OF THE S/SE...THUS LIGHT WINDS. THESE WINDS WILL TRY AND TURN ONSHORE AS WE HEAD THROUGH THE AFTERNOON...CREATING A POCKET OF BETTER LOW LEVEL CONVERGENCE ACROSS PORTIONS OF NE LOWER. AS THE FRONT NEARS THE WESTERN CWA LATE THIS AFTERNOON...AND CROSSES NE LOWER AFTER THE EVENING...WEAK H8-H7 WAA...DPVA AND H4-H2 UPPER DIVERGENCE IN LEFT EXIT REGION OF AN UPPER JETLET...WILL COMBINE WITH DIURNAL HEATING/DESTABILIZATION FOR A CHANCE AT SHOWERS AND STORMS. PROBLEMS...UPPER WAVE STARTS TO LIFT NE AND SHEAR OF THE MEAGER CORRIDOR OF DEEPER MOISTURE. PLUS...CAPPING AROUND 800MB AND LACK OF ANY APPRECIABLE LL MOISTURE SHOWS QUITE A BIT OF CINH (40J/KG) FOR MUCH OF THE DAY. THIS CAPPING DOES GET ERODED...BUT NOT UNTIL THE FRONT ARRIVES. THIS WILL LEAVE A PERIOD OF POSSIBLE SHOWERS AND STORMS...WHICH WILL MORE LIKELY LAST FOR 3-5 HRS ON/NEAR THE FRONT. WIND FIELDS NOT OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR AT 30KTS...AND WET BULBS AT 11KFT ARE KIND OF HIGH. HOWEVER...DECENT HEATING TO START THE DAY...MLCAPE OF 1500 J/KG POSSIBLE...THEN A LOW END THREAT FOR DAMAGING WINDS AND ISOLATED LARGE HAIL WITH EH STRONGER CELLS ARE POSSIBLE. WE ARE NOT IN A SLIGHT RISK RIGHT NOW...AND THIS WOULD CERTAINLY NOT BE A WIDESPREAD SEVERE THREAT. THE FRONT CROSSES NE LOWER BY MIDNIGHT...WITH A GRADUALLY INCREASING/STRENGTHENING PRESSURE GRADIENT RESULTING IN A GROWING COLD ADVECTION REGIME WITH BREEZIER WINDS TOWARD DAYBREAK...ESPECIALLY DOWNWIND OF LAKE MICHIGAN AND WHITEFISH BAY. LOW TEMPS TO FALL INTO THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 352 AM EDT SUN SEP 1 2013 INCREASING RIDGING TO START THE PERIOD TUESDAY WHICH HOLDS THROUGH MUCH OF WEDNESDAY. THE RIDGE THEN GETS TEMPORARILY KNOCKED DOWN LATER WEDNESDAY INTO WEDNESDAY NIGHT AS A MOISTURE STARVED SHORT WAVE MOVES THROUGH THE FLOW. RIDGING THEN TAKES OVER ONCE AGAIN LATE IN THE WEEK INTO THE FIRST HALF OF NEXT WEEKEND AHEAD OF THE NEXT TROUGH. OVERALL DRY WEATHER IS EXPECTED...THOUGH THERE MAY END UP BEING SLIGHT CHANCES FOR SHOWERS LATE IN THE WEEK. THE MAIN LONG TERM FORECAST CONCERNS CENTER AROUND CLOUD COVER AND HIGH TEMPERATURES MONDAY THEN POPS TO END THE PERIOD. LABOR DAY...SHARPLY COOLER CONDITIONS ARE EXPECTED. MODEL SOUNDINGS AND CROSS SECTIONS SHOW A DECENT AMOUNT OF MOISTURE AT LOWER LEVELS. THIS SHOULD RESULT IN LOTS OF CLOUDS AND POSSIBLE DRIZZLE ACROSS NORTHERN AREAS AS AN UPPER LEVEL TROUGH MOVES BY TO OUR NORTHEAST. ACROSS SOUTHERN ZONES...THERE COULD END UP BEING A BIT LESS CLOUD COVER WHICH MAY TEMPER TEMPERATURES. HIGHS ONLY RANGING FROM THE LOWER 60S NORTH TO AROUND 70 SOUTHEAST. MONDAY NIGHT THROUGH TUESDAY NIGHT...SEASONABLE WEATHER IS EXPECTED AS SURFACE HIGH PRESSURE TEMPORARILY SEIZES CONTROL. LOWS IN THE 40S TO LOWER 50S. HIGHS TUESDAY REBOUNDING INTO THE LOWER AND MIDDLE 70S. WEDNESDAY INTO THURSDAY...A MOISTURE STARVED UPPER LEVEL SHORT WAVE AND SURFACE COLD FRONT MOVE ACROSS THE REGION. AT THIS POINT NO PRECIPITATION IS EXPECTED. WARMER WEDNESDAY WITH HIGHS RANGING FROM AROUND 70 NORTH TO THE UPPER 70S SOUTHEAST. COOLER THURSDAY WITH HIGHS RANGING FROM THE MIDDLE 60S TO LOWER 70S. FRIDAY INTO SATURDAY...THE UPPER LEVEL RIDGE LOOKS TO NOSE EASTWARD INTO OUR NECK OF THE WOODS...WHICH BODES WELL FOR ANOTHER WARMING TREND SETTING IN TO ROUND OUT THE WEEK. THERE COULD BE SOME INSTABILITY DRIVEN SHOWERS...BUT EXTENDED MODELS DISAGREE ON THE AMOUNT OF AVAILABLE MOISTURE AS WELL AS THE STRENGTH OF A POSSIBLE CAPPING INVERSION ALOFT SO WILL CONTINUE TO LEAVE OUT POPS AT THIS TIME. HIGHS BOTH DAYS RANGING FROM THE LOWER AND MIDDLE 70S FAR NORTH TO AROUND 80 SOUTH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 158 PM EDT SUN SEP 1 2013 LINE OF SHOWERS/THUNDER WILL IMPACT PLN OVER THE NEXT 1 TO 2 HOURS. OTHERWISE...VFR CIGS SLOWLY EMERGING ACROSS NRN LOWER MICHIGAN. COLD FRONT EXPECTED TO SWING THROUGH THE REGION LATE THIS AFTERNOON/EARLY EVENING AND MAY YET SPARK ADDITIONAL SHOWERS AND STORMS ACROSS NRN LOWER MICHIGAN...ESPECIALLY NE LOWER MICHIGAN. BEHIND THE FRONT...MUCH COOLER AIR WILL SPREAD INTO THE REGION TONIGHT. THIS WILL LEAD TO ABUNDANT STATUS EXPANDING DOWN INTO THE REGION DURING THE OVERNIGHT PERIOD THAT WILL PERSIST THROUGH MUCH OF LABOR DAY. WINDS TURN NORTHWEST TONIGHT WITH SOME GUSTINESS THROUGH THE DAY MONDAY. && .MARINE... ISSUED AT 352 AM EDT SUN SEP 1 2013 A WEAK S/SE WIND TODAY AHEAD OF AN APPROACHING COLD FRONT...WILL TRY AND TURN MORE ONSHORE THIS AFTERNOON DUE TO ANTICIPATED LAKE BREEZES. THIS WILL CHANGE THROUGH THE NIGHT...AS A PERIOD OF SCATTERED SHOWERS AND STORMS WILL BLOW THROUGH ALONG WITH THE COLD FRONT. BEHIND THIS FRONT...WINDS WILL SHIFT ABRUPTLY OUT OF THE NW....WHILE OVERLAKE INSTABILITY DEVELOPS AND A TIGHTER PRESSURE GRADIENT SETTLES IN OVER THE GREAT LAKES. ADVISORY LEVEL WINDS ARE LIKELY MONDAY AND MONDAY NIGHT IN MANY OF THE NEARSHORE WATERS. THIS IS ESPECIALLY TRUE FOR PRESQUE ISLE LIGHT/NE LOWER MICHIGAN NEARSHORES. HIGHER PRESSURE THEN BUILDS IN FOR QUIETER/CALMER BOATING CONDITIONS FOR THE REMAINDER OF THE WORK WEEK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EDT MONDAY FOR LMZ323-342-344>346. LS...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EDT MONDAY FOR LSZ321. && $$ UPDATE...BA SYNOPSIS...AS SHORT TERM...SD LONG TERM...AS AVIATION...BA MARINE...SD
AREA FORECAST DISCUSSION
NWS ELKO NV
200 PM PDT SUN SEP 1 2013 .SYNOPSIS...MONSOON MOISTURE WILL INCREASE ACROSS NEVADA TONIGHT THROUGH MONDAY...WITH SHOWERS AND THUNDERSTORMS BECOMING INCREASINGLY LIKELY. SOME STORMS WILL PRODUCE HEAVY RAIN AND LOCALIZED FLOODING. MONSOON MOISTURE IS EXPECTED TO LINGER FOR MUCH OF THIS WEEK. && .SHORT TERM...TONIGHT THROUGH TUESDAY. AN IMPRESSIVE SURGE OF MONSOON MOISTURE IS ORGANIZING ACROSS CENTRAL AND SOUTHERN NEVADA THIS AFTERNOON, WHERE YET ANOTHER CROP OF SCATTERED THUNDERSTORMS IS GETTING UNDERWAY. 12Z NAM AND THE 3KM-HRRR BOTH SPREAD NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHERN HALF OF THE CWA /WHITE PINE, NYE, SOUTHERN LANDER/EUREKA COUNTIES/ THROUGH THIS EVENING. VISIBLE SATELLITE REVEALS PERCOLATING CUMULUS ON THE HIGHER TERRAIN OF CENTRAL NEVADA, WITH SPC MESOANALYSIS REVEALING LIFTED INDEX TO -5 AND CAPE TO 1500 J/KG, AND THAT`S ONLY AS OF NOON. EXTRA MOISTURE IN THE AIR SEEMS TO BE SLOWING HEATING SOMEWHAT, AND SOME WARMER AIR ALOFT IS NOT HELPING EITHER. BUT THUNDERSTORMS ARE EXPECTED THROUGH THIS EVENING NONETHELESS. WILL MAINTAIN FLASH FLOOD WATCH FOR CENTRAL NEVADA THROUGH 11 PM, WHERE THE GREATEST CONCENTRATION OF STORMS WILL BE LOCATED. 3KM HRRR FORECASTS A COMPLEX OF THUNDERSTORMS ENTERING SOUTHERN ELKO COUNTY WITH THE MAIN MOISTURE SURGE AROUND MIDNIGHT TONIGHT. KEPT SHOWER AND THUNDERSTORM COVERAGE MUCH HIGHER TONIGHT THAN IS TYPICAL, WITH LOCALLY HEAVY RAIN LIKELY. WILL LET THE FLASH FLOOD WATCH EXPIRE AT 11 PM FOR NOW, BUT CONFIDENT THE CONVECTION WILL NOT END THEN, SO THE EVENING SHIFT WILL NEED TO DETERMINE WHETHER TO EXTEND THE WATCH THROUGH TONIGHT. MOISTURE QUALITY WILL BE INCREASING DRAMATICALLY TONIGHT THROUGH MONDAY MORNING, AND WITH GFS/NAM BOTH FORECASTING SIGNIFICANT INSTABILITY OVERNIGHT INTO MONDAY MORNING, NOCTURNAL CONVECTION IS LIKELY. FURTHER AIDING THE THUNDERSTORMS WILL BE THE ADVERTISED WEAK SHORTWAVE, ROTATING NORTH THROUGH EASTERN NEVADA IN THE MOIST MONSOON FLOW, AND APPROACHING ELKO COUNTY AROUND 5 AM MONDAY. THIS IS THE MOST STABLE TIME OF DAY /THE CONVECTIVE MINIMUM/ BUT DESPITE THIS, EXPECT SOME THUNDERSTORMS WILL SURVIVE THE NIGHT. WITH THE CLOUDS, RAIN, AND RAPIDLY INCREASING HUMIDITY LOW TEMPERATURES LABOR DAY MORNING WILL BE VERY MILD AND WAY ABOVE NORMAL, IN THE UPPER 50S AND LOWER 60S. SOME RECORD WARM OVERNIGHT LOWS ARE LIKELY, ELKO`S RECORD FOR SEP 2ND IS 59 SET IN 1960. MY FORECASTED LOW IS 61 DEGREES. LABOR DAY...CLOUDY AND MOIST WITH SHOWERS AND THUNDERSTORMS LIKELY. MOISTURE WILL BE PLENTIFUL WITH PRECIPITABLE WATER VALUES NEAR RECORD LEVELS FOR EARLY SEPTEMBER, RANGING FROM 1-1.2 INCHES. ANY STORMS THAT DEVELOP MONDAY WILL PRODUCE EXCESSIVE RAINFALL. THE QUESTION IS, WILL THERE BE ENOUGH INSTABILITY FOR THUNDERSTORMS TO REDEVELOP MONDAY? THE ANSWER FROM MANY MODELS, THE 12/18Z NAM, 12Z GFS AND ECMWF IS A UNANIMOUS YES. ALL GUIDANCE ALLOWS SCATTERED TO NUMEROUS THUNDERSTORMS TO REDEVELOP ACROSS NEVADA MONDAY AFTERNOON AND EVENING, EVEN ALL THE WAY INTO HUMBOLDT COUNTY. SOME FORECASTER CONCERNS REGARDING THIS SCENARIO: 1) THE SHORTWAVE THAT WILL HELP TRIGGER STORMS TONIGHT IS COMING THROUGH NE NEVADA LATE TONIGHT AND EARLY MONDAY, NOT A GREAT TIME TO GET STORMS GOING. IN FACT, SUBSIDENCE BEHIND THE DEPARTING WAVE AND THE SINKING AIR ASSOCIATED WITH IT MAY HINDER THUNDERSTORM GROWTH MONDAY AFTERNOON, AND 2) WE ARE GOING TO BE VERY MOIST. SKIES WILL BE MOSTLY CLOUDY TO CLOUDY ALL DAY, AND IT MAY PROVE DIFFICULT TO GET THE SUNSHINE NEEDED FOR NEW STORM INITIATION. DESPITE THESE CONCERNS, FORECASTED SCATTERED TO NUMEROUS THUNDERSTORMS FOR ALL ZONES MONDAY. BECAUSE OF THE UNCERTAINTIES, WILL NOT ISSUE ANOTHER FLASH FLOOD WATCH FOR MONDAY, BUT THIS WILL REQUIRE CAREFUL WATCHING, ESPECIALLY GIVEN THE OUTDOOR HOLIDAY ACTIVITIES. FOR NOW, SORT OF TOOK A MIDDLE GROUND AND MENTIONED HEAVY RAIN IN THE GRIDS FOR NE NEVADA. AGAIN, WITH NEAR RECORD PW IN THE ATMOSPHERE, ANY STORM WILL PRODUCE VERY HEAVY RAIN. NOT THE BEST FORECAST FOR LABOR DAY PLANS, BUT DOUBT MANY WILL COMPLAIN AS THE NEVADA DROUGHT CONTINUES. TUESDAY...CONTINUED MOIST AND UNSTABLE. PW REMAINS VERY HEALTHY, RANGING FROM 0.80-1.2 INCH. 12Z GFS FORECASTS WIDESPREAD NEGATIVE LIFTED INDICES AT 5 PM TUESDAY, SO INCREASED THUNDERSTORM COVERAGE IN THE GRIDS ACCORDINGLY. TURNER .LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY. MODELS AGREE FAIRLY WELL WITH THE OVERALL PATTERN THROUGH THE PERIOD. THE CWA IS UNDER THE INFLUENCE OF THE "MONSOON" MOISTURE TUESDAY NIGHT THROUGH THURSDAY...HOWEVER UPPER TROF PUSHES INLAND SHOVING THE TSTM ACTIVITY TO EASTERN NV ON THURSDAY. BY FRIDAY TROF WEAKENS OVER THE CWA AS IT MOVES NORTH INTO THE PACIFIC NORTHWEST. AGAIN THE TSTM ACTIVITY IS EXPECTED TO BE CONFINED TO EASTERN NV. BY SATURDAY INSTABILITY IS PUSHED INTO WHITE PINE COUNTY AS TROF MOVES TO THE NORTH OF NEVADA. THEN EXPECT DRY CONDITIONS NEXT SUNDAY AS FOUR CORNER HIGH GETS SUPPRESSED. JH && .AVIATION...VFR ALL TERMINALS. KWMC AND KEKO WILL SEE PERIODIC SMOKY CONDITIONS...BUT IS NOT EXPECTED TO REDUCE SURFACE VSBY. KEKO WILL ALSO HAVE VCTS THIS EVENING AND MONDAY AFTERNOON. KTPH AND KELY MAY HAVE -TSRA THROUGH EARLY EVENING. KELY MAY SEE HEAVY RAIN AT TIMES. JH && .FIRE WEATHER...SCATTERED TO NUMEROUS THUNDERSTORMS THIS AFTERNOON THROUGH MONDAY. WHILE LIGHTNING WILL BE PLENTIFUL, WETTING RAINS AND MUCH HIGHER RH WILL MINIMIZE THE RISK FOR NEW LIGHTNING IGNITIONS. RETURNING MONSOON MOISTURE WILL ALLOW FOR MUCH HIGHER MAX/MIN RH AND GREAT OVERNIGHT RECOVERIES. TURNER && .LKN WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 11 PM PDT THIS EVENING FOR NORTHEASTERN NYE COUNTY...NORTHWESTERN NYE COUNTY...SOUTHERN LANDER COUNTY AND SOUTHERN EUREKA COUNTY...WHITE PINE COUNTY. && $$ 99/87/87/99
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
957 AM PDT SUN SEP 1 2013 .SYNOPSIS...MOIST AND UNSTABLE AIR WILL ONCE AGAIN RESULT ON SHOWERS AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS EVENING ESPECIALLY ACROSS SOUTHERN NEVADA...NORTHWEST ARIZONA AND THE HIGHER ELEVATIONS OF INYO COUNTY. THE PRIMARY THREAT WITH STORMS TODAY WILL ONCE AGAIN BE LOCALLY HEAVY RAIN THAT COULD RESULT IN FLASH FLOODING. ALTHOUGH SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA THROUGH THE END OF THE WEEK...THE BEST CHANCES SHOULD BE NORTH AND EAST OF LAS VEGAS. HIGH TEMPERATURES SHOULD GRADUALLY RETURN TO NEAR NORMAL LEVELS BY THE MIDDLE OF THE WEEK. && .UPDATE...MAIN CONCERN FOR TODAY IS WHETHER TO EXPAND THE FLASH FLOOD WATCH INTO DEATH VALLEY NATIONAL PARK. WATER VAPOR LOOP SHOWED MID LEVEL MOISTURE GRADIENT SURGING NORTH...POSSIBLY FOCUSING STORMS FARTHER NORTH THAN DVNP LATER IN THE DAY. CONFIDENCE IS NOT HIGH ENOUGH TO JUSTIFY EXPANSION...SO WILL STAND PAT FOR NOW. NO CHANGES AT THIS TIME. && .PREVIOUS DISCUSSION... ISSUED AT 304 AM PDT SUN SEP 1 2013 .SHORT TERM...CONVECTION HAS REFUSED TO GO AWAY TONIGHT ACROSS MOHAVE, SOUTHERN CLARK AND NORTHEAST SAN BERNARDINO COUNTIES AS ACTIVITY THAT DEVELOPED EARLIER BEHIND AN OUTFLOW BOUNDARY THAT PUSHED SOUTH ACROSS THE AREA BLOSSOMED AND HAS MANAGED TO DUMP SOME HEFTY AMOUNTS OF RAIN. ONE AUTOMATED RAIN GAUGE NEAR SEARCHLIGHT HAS MEASURED 2.60 INCHES OF RAIN IN ABOUT 2 HOURS AND VERY HEAVY RAIN WAS FALLING AROUND YUCCA AND OTHER AREAS IN SOUTH-CENTRAL MOHAVE COUNTY. CLOUD TOPS HAVE ACTUALLY COOLED IN THE LAST HOUR OR SO WITH THIS CONVECTIVE COMPLEX WITH VALUES PUSHING -72C WHICH IS IMPRESSIVE FOR ANYTIME OF DAY BUT ESPECIALLY AT THIS HOUR OF THE NIGHT. THIS CONVECTIVE COMPLEX OVER MOHAVE COUNTY WILL BE THE MAIN ISSUE WITH THE INITIAL PORTIONS OF THE FORECAST AS IT MAY WORK OVER ENOUGH OF THE SOUTHEAST PORTIONS OF THE AREA TO INHIBIT CONVECTION UNTIL LATER TODAY OR EVEN POSSIBLY ALTOGETHER. ELSEWHERE THINGS HAVE RELATIVELY CALMED DOWN AND CLOUD COVER HAS CLEARED OUT ESPECIALLY ACROSS MUCH OF THE NORTHWEST CWFA. FOR TODAY, THE FLOW ALOFT WILL START TO TAKE ON MORE OF A SOUTHWEST COMPONENT ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE CWFA. WHILE THIS WILL TRY TO BRING IN SOME DRIER AIR, THERE IS SO MUCH MOISTURE IN PLACE, ALONG WITH SUFFICIENT INSTABILITY, THAT IT IS HARD TO DISCOUNT THUNDERSTORMS DEVELOPING ANYWHERE FROM LATE THIS MORNING INTO THIS AFTERNOON AND EVENING. HOWEVER, LOOKING AT 700-300 MB THETA E VALUES THERE IS A NOTICEABLE INCREASE IN VALUES ABOVE 340K ACROSS LINCOLN, CLARK AND NORTHERN MOHAVE COUNTIES WHICH ALSO MATCHES WHERE THE BEST COMPUTED CAPE VALUES ARE SHOWN. SO, WE HAVE CONTINUED WITH THE HIGHEST POPS ACROSS THESE AREAS. IN ADDITION, A WEAK RIPPLE IN THE MID-LEVELS (A WEAK INVERTED TROUGH) AND A POTENTIAL ASSOCIATED PIECE OF ENERGY ARE SHOWN TO LIFT NORTHEAST ACROSS SOUTHERN NEVADA LATE THIS AFTERNOON INTO THIS EVENING WHICH MAY FURTHER HELP TO ENHANCE CONVECTION IN THESE AREAS AND COULD EVEN KEEP IT GOING LATER THIS EVENING AND INTO LATE TONIGHT THAN WHAT WE SEE GO ON ELSEWHERE. WITH THAT, I WENT AHEAD AND ADJUSTED UP POPS FOR LINCOLN AND NORTHERN MOHAVE COUNTIES INTO THE LATER PORTIONS OF TONIGHT. THE FLASH FLOOD WATCH WAS EXTENDED FOR THESE AREAS LAST EVENING FOR THE ONGOING CONVECTION, SO EVEN THOUGH MODELS SHOW THINGS NOT GETTING GOING UNTIL BETWEEN 10 AM AND NOON, IT WILL REMAIN OUT. THE STEERING FLOW TODAY WILL BE STRONGER AND MORE WELL DEFINED FROM THE SOUTHWEST THAN THE ZIG-ZAG NATURE WE HAD YESTERDAY, AND THUS WE WILL NEED TO WATCH IN THE LAS VEGAS VALLEY FOR ACTIVITY TO MOVE IN FROM THE SPRING MOUNTAINS BY LATE THIS MORNING AND INTO THIS AFTERNOON. THIS COULD PRESENT PROBLEMS WITH THE CARPENTER 1 FIRE BURN AREA AND WE WILL NEED TO WATCH OUT AGAIN FOR DEBRIS FLOWS. ELSEWHERE, BOTH THE GFS AND ECMWF AS WELL AS THE HRRR MODEL SUGGEST THAT ACTIVITY SHOULD GET GOING ACROSS THE SOUTHERN SIERRA, WHITE MOUNTAINS AS WELL AS MOUNTAINS OF ESMERALDA AND CENTRAL NYE COUNTIES. ENOUGH INSTABILITY AND CAPE ARE SHOWN THERE AS IS MOISTURE TO JUSTIFY ADDING THESE AREAS TO THE FLASH FLOOD WATCH, HOWEVER SINCE ACTIVITY WILL LIKELY TAKE UNTIL LATER THIS MORNING, THE WATCH WILL START HERE AT 11 AM. AGAIN, THE STEERING FLOW WILL BE FROM THE SOUTHWEST WHICH COULD DRIVE STORMS THAT DEVELOP ALONG THE SOUTHERN SIERRA CREST INTO THE OWENS VALLEY LATER THIS AFTERNOON AND THIS EVENING. WE MAY GET A LITTLE MORE ISSUES WITH WIND HERE AS THERE WILL BE A LITTLE MORE LOWER LEVEL DRYING THAT TAKES PLACE AND STORMS MAY GET SOME MOMENTUM AS THEY DROP OFF THE MOUNTAINS AND INTO THE VALLEYS AND THE AIR ACCELERATES DOWN THE TERRAIN. TEMPS TODAY SHOULD BE A FEW DEGREES WARMER THAN SATURDAY, EXCEPT WHERE CLOUDS ARE THICKER AND CONVECTION DEVELOPS EARLIER. FOR LABOR DAY, THE TROUGH APPROACHING NORCAL WILL KEEP THE FLOW ALOFT SOUTHWEST TO SOUTH. EVEN THOUGH A LITTLE DRYING TAKES PLACE ACROSS SOUTHEAST CALIFORNIA, THERE IS STILL ENOUGH MOISTURE AND INSTABILITY TO KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS AROUND EVERYWHERE. HOWEVER, THE BEST MOISTURE REMAINS NORTH AND EAST OF LAS VEGAS, WHICH IS WHERE THE HIGHEST POPS WERE PLACED. HOWEVER, IT DOES APPEAR THAT THE COVERAGE OF STORMS WILL BE AS GREAT AS WHAT WE COULD SEE TODAY. WITH A LESS IN THE WAY OF STORMS, THERE COULD BE MORE SUN AND THUS TEMPS SHOULD BE A LITTLE WARMER. ONE THING TO WATCH TODAY AND MONDAY WILL BE HOW MUCH ACTIVITY GETS GOING ON THE MOIST-DRY INTERFACE AS THIS AREA MAY BE MORE ACTIVE THAN WHAT THE MODELS SHOW. TODAY MAY HELP PROVIDE SOME CLUES AS TO WHAT WE COULD SEE ALONG THAT INTERFACE TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY...HIGH PRESSURE WILL PERSIST ROUGHLY NEAR THE FOUR CORNERS AREA MONDAY NIGHT THROUGH FRIDAY WITH GENERALLY A SOUTHERLY FLOW OVER THE FORECAST AREA. THIS WILL KEEP MONSOON MOISTURE IN PLACE WITH ISOLATED TO SCATTERED THUNDERSTORMS EACH DAY. THE GFS AND ECMWF ARE IN FAIR AGREEMENT FOR A BIT OF A PATTERN CHANGE BY SATURDAY WITH A LOW PRESSURE SYSTEM FINALLY MOVING EAST THROUGH THE PACIFIC NORTHWEST. THE RESULT IS A WEST TO MAYBE EVEN NORTHWEST FLOW OVER THE NORTHERN PART OF THE FORECAST AREA BRINGING IN DRIER AIR. THIS MAY BRING AN END TO THE THUNDERSTORM CHANCES FOR THE FAR NORTH AND PARTS OF THE WESTERN CWA. GUIDANCE CONTINUES TO INDICATE TEMPERATURES A TOUCH ABOVE NORMAL FOR MOST OF THE LONG TERM. .AVIATION...FOR MCCARRAN...WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AWAY FROM ANY SHRA/TSRA THROUGH TONIGHT. SCT-BKN CLOUDS AOA 10-15K FEET ARE EXPECTED THROUGH TONIGHT. SHRA/TSRA ARE EXPECTED TO DEVELOP IN AND AROUND THE LAS VEGAS VALLEY AND IN THE APPROACH CORRIDORS ON TODAY AFTER 18Z AND DIMINISH BETWEEN 04Z AND 07Z MONDAY. GUSTY AND ERRATIC WINDS...REDUCED CIGS AND VSBY ARE POSSIBLE IN AND NEAR ANY SHRA/TSRA AND OUTFLOW BOUNDARIES WHICH MAY IMPACT CONFIGURATIONS. THE FLOW IN THE ATMOSPHERE IS FROM THE SOUTHWEST TO WEST THROUGH TONIGHT WHICH WOULD FAVOR PUSHING SHRA/TSRA IN FROM THE SPRING MOUNTAINS TOWARD THE AIRPORT COMPLEX. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...EXPECT SCT-BKN CLOUDS AOA 10-15K FEET WITH WINDS FAVORING TYPICAL DIURNAL TRENDS THROUGH TONIGHT AWAY FROM ANY SHRA/TSRA. REDUCED CIGS AND VSBY AND GUSTY AND ERRATIC WINDS IN AND NEAR SHRA/TSRA WILL BE THE MAIN THREATS. SHRA AND TSRA ARE EXPECTED AFTER 18Z SUNDAY BEFORE DECREASING AROUND 06Z MONDAY WITH ACTIVITY MOST LIKELY IN LINCOLN, CLARK, ESMERALDA, MOHAVE, CENTRAL NYE AND WESTERN INYO COUNTIES. SHRA/TSRA SHOULD MAINLY FROM EAST THROUGH TONIGHT. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ015-016-018>022. FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR NVZ014. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ001>003-036. CA...FLASH FLOOD WATCH FROM 11 AM PDT THIS MORNING THROUGH THIS EVENING FOR CAZ519>521. && $$ MORGAN/STACHELSKI/HARRISON FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1140 AM MDT SUN SEP 1 2013 .AVIATION... 18Z TAF CYCLE MORE CONVECTIVE ACTIVITY EXPECTED TODAY AS BACKDOOR SFC FRONT GETS STORMS GOING ERN PLAINS AND CENTRAL MTNS EARLY THIS AFTERNOON AND STORMS AND SFC FRONT DEVELOP WWD INTO RG VALLEY LATE THIS AFTN AND INTO WRN NM THIS EVENING/TONIGHT. ISOLD TO WDLY SCT MVFR CIGS/VSBY IN SHRA/TSRA TO OCCASIONALLY OBSCURE HIGHER TERRAIN. CELL MOVEMENT WILL BE SLOW AND SOMEWHAT ERRATIC DUE TO UPPER LEVEL HIGH PRESSURE CENTER OVERHEAD. STORMS IN WRN NM WILL CONTINUE UNTIL BTWN 6Z-9Z MONDAY AS A SOMEWHAT ORGANIZED LINE DEVELOPS AND PROPAGATES SLOWLY WWD. 33 && .PREV DISCUSSION...324 AM MDT SUN SEP 1 2013... ...SIGNIFICANT UPTICK IN THUNDERSTORMS EXPECTED TODAY AND LABOR DAY... COLD FRONT APPEARS TO BE IN NORTHEASTERN CO STRETCHING OVER THE KS/NE BORDER JUST AFTER 3 AM. THIS BOUNDARY WILL PLAY A PIVOTAL ROLE IN THE WEATHER OVER NM TODAY AND THE LABOR DAY HOLIDAY. THE UPPER LEVEL DOME OF HIGH PRESSURE WILL KEEP A SYMMETRICAL AND STEADY PRESENCE OVER NM TODAY. MODEST...YET SUFFICIENT MOISTURE IS CURRENTLY IN PLACE OVER THE NORTHERN HALF OF THE STATE...AND A NOTABLE INCREASE IS EXPECTED OVER THE NORTH CENTRAL TO NORTHEASTERN ZONES TODAY AS BETTER BOUNDARY LAYER MOISTURE IS TRANSPORTED IN WITH THE ARRIVAL OF THE FRONTAL BOUNDARY. DECENT CAPE VALUES OF 800-1500 J/KG WILL SUPPORT HEALTHY STORM GROWTH AS UPSLOPE FLOW IS EXPLOITED. THERE WILL LIKELY BE SOME LOCALLY HEAVY RAINFALL AT TIMES...BUT CONFIDENCE IS NOT HIGH ENOUGH TO SUPPORT A WIDESPREAD FLASH FLOOD WATCH. STEERING FLOW WILL BE SLUGGISH DUE TO THE LIGHT WINDS ALOFT...BUT A PROGRESSIVE ADVANCEMENT OF THE FRONT FARTHER SOUTH AND WEST SHOULD KEEP THE BEST AREA OF FORCING ON THE MOVE. TEMPERATURES WILL TAKE A SUBSTANTIAL DROP IN THE NORTHEAST WHILE SOME PARTS OF DE BACA...ROOSEVELT...AND CHAVES COUNTIES FLIRT WITH NEAR RECORD HIGHS WHERE THE FRONT WILL NOT YET HAVE ARRIVED. LATE THIS AFTERNOON AND INTO TONIGHT A MODERATE GAP/CANYON WIND IS EXPECTED TO DEVELOP...PRIMARILY DOWNWIND OF THE TAOS CANYON...GLORIETA PASS...AND TIJERAS CANYON. WINDS APPEAR TO STAY MORE SOUTHEASTERLY FARTHER TO THE SOUTH. GUSTS OF 25 TO 35 MPH SEEM TO FIT THE BILL WITH CONVECTIVE BURSTS POTENTIALLY ENHANCING THESE SPEEDS BRIEFLY. THE FRONT IS DEPICTED AS ADVANCING AS FAR WEST AS THE SAN JUAN BASIN OF NORTHWEST NM BEFORE DAWN ON LABOR DAY...BUT IT DOES NOT APPEAR TO ADVANCE VERY FAR TO THE SOUTH...SOMEWHERE NEAR OR JUST SLIGHTLY SOUTH OF I-40. WHERE THE FRONT GETS HUNG UP IN THE NORTHWESTERN TO WEST CENTRAL ZONES WILL DICTATE THE THUNDERSTORM CROP FOR LABOR DAY. HAVE CONTINUED WITH LIKELY POPS THERE...ASSUMING THE FLUX OF BETTER BOUNDARY LAYER MOISTURE WILL SURVIVE THE TREK THERE. FOR THE SECOND DAY IN A ROW THE MODELS CONTINUE TO HAMMER THE CENTRAL MOUNTAIN CHAIN AND ADJACENT HIGHLANDS/HIGH PLAINS TO THE EAST WITH SYNOPTIC SOUTHEASTERLY SURFACE FLOW AND SUFFICIENT CAPE VALUES OF 400-1000 J/KG. HAVE PAINTED LIKELY POPS ACROSS THE CENTRAL MOUNTAIN CHAIN BASED ON THIS...TAPERING OFF AS ONE PROGRESSES EAST TOWARD TX. TUESDAY`S STORMS WILL BE BASED ON A PROCESS OF RECYCLING REMNANT MOISTURE FROM MONDAY. WOULD EXPECT A LOWER COVERAGE OVERALL WITH THE WESTERN TWO THIRDS FAVORED AS THE UPPER HIGH STRENGTHENS INTO CO. THIS TREND CARRIES ON INTO WEDNESDAY WITH H5 HEIGHTS CLIMBING TO 596 DAM IN CO. THE HIGH EVENTUALLY DRIFTS BACK INTO NM BY NEXT WEEKEND WITH A DIURNAL RECYCLING OF MOISTURE PERSISTING. THE HIGH WILL THUS FIGHT OFF THE WESTERLIES ALOFT...KEEPING AVAILABLE MOISTURE FROM ESCAPING PREMATURELY...HOWEVER THE ADVERTISED ORIENTATION OF THE HIGH ALSO WOULD NOT BE SUSCEPTIBLE TO ANY DEEP SUBTROPICAL MOISTURE INTRUSIONS. 52 .FIRE WEATHER... UPPER HIGH CENTER LOCATED OVER CENTRAL NM EARLY THIS MORNING AND FORECAST TO WANDER SLIGHTLY TO THE WEST AND NORTH...BUT STILL REMAINING SQUARELY OVER THE STATE THIS AFTERNOON AND THROUGH LABOR DAY. WIND SHIFT APPARENTLY ASSOCIATED WITH EARLIER CONVECTION OVER SW KS STILL CHUGGING SOUTH INTO PORTIONS OF THE EAST CENTRAL PLAINS ATTM. NOT CONFIDENT THIS IS THE FRONT FORECAST TO IMPACT THE NORTHEAST LATER THIS MORNING...AS THE RUC13 SHOWS OTHERWISE...DEPICTING ANOTHER PUSH AROUND MIDDAY. STILL IT HAS SHOVED SOME 50S DEWPOINTS BACK INTO THE REGION AFTER THEY DRIED/MIXED OUT SATURDAY AFTERNOON. NORTHEAST QUARTER OF NM STILL FAVORED FOR BEST WETTING RAIN CHANCES TODAY...SPREADING WESTWARD TONIGHT AS AN EASTERLY WIND BREAKS INTO THE UPPER/MIDDLE RGV AND REACHES THE JEMEZ. STORM MOTION TO BE RATHER SLOW SO POTENTIAL FOR LOCALLY HEAVY RAIN EXISTS. HIGHS TODAY TO REMAIN ABOVE AVERAGE...WITH NEAR RECORD HIGHS POSSIBLE IN PORTIONS OF THE EAST CENTRAL PLAINS. GENLY GOOD OR BETTER OVERNIGHT RH RECOVERIES ANTICIPATED. CHANCES FOR WETTING RAIN ON LABOR DAY WILL BE FOCUSED OVER THE CENTRAL MT CHAIN AND ALONG AND EAST OF THE CONTDVD. HIGHS WILL BE A BIT COOLER BUT STILL ABOVE AVERAGE. STORM MOTION TO BE SLOW...SO SOME CELLS COULD PRODUCE LOCALLY HEAVY RAIN. SOME POCKETS OF FAIR TO POOR VENTILATION LIKELY OVER THE WEST AND NORTH. A DRYING TREND IS STILL FORECAST FOR THE TUESDAY THROUGH FRIDAY PERIOD. MAINLY DIURNAL SHOWERS AND STORMS ARE FEATURED STARTING WEDNESDAY OVER THE NORTHERN AND WESTERN HIGH TERRAIN AS THE UPPER HIGH CENTER WANDERS INTO COLORADO. DESPITE THE DRYING TREND...OVERNIGHT RECOVERIES SHOULD REMAIN GOOD FOR MOST LOCALES. AREAS OF FAIR TO POOR VENTILATION RATES ARE FORECAST FOR THE CENTRAL AND WEST TUESDAY...WITH SOME IMPROVEMENT WEDNESDAY AND THURSDAY. WIDESPREAD POOR RATES ARE INDICATED FRIDAY FOR THE CENTRAL AND WEST. HIGH TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE ACROSS NRN AND CENTRAL NM. && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHY
AREA FORECAST DISCUSSION
NWS RALEIGH NC
246 PM EDT SUN SEP 1 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT... THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY AND LINGER THROUGH THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SUNDAY... UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE (IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 245 PM SUNDAY... OVERVIEW: CYCLONIC FLOW ALOFT WILL FURTHER STRENGTHEN ACROSS THE MID- ATLANTIC AND CAROLINAS ON MON/MON NIGHT AS AN UPPER LEVEL LOW AMPLIFIES ACROSS THE NORTHERN GREAT LAKES. AN ATTENDANT SFC LOW WILL BE PRESENT ACROSS THE LOWER GREAT LAKES AND NORTHERN MID- ATLANTIC...WITH A COLD FRONT EXTENDING SOUTHWEST FROM THE OH VALLEY INTO THE LOWER MS RIVER VALLEY. THE COLD FRONT WILL APPROACH THE SOUTHERN APPALACHIANS FROM THE NORTHWEST BY 12Z TUE. PRECIP CHANCES: EXPECT A THERMODYNAMIC ENVIRONMENT LARGELY SIMILAR TO TODAY ON MON AFT/EVE...WITH THE POSSIBLE EXCEPTION OF SLIGHTLY STEEPER MID- LEVEL LAPSE RATES ON THE ORDER OF 6.0-6.5 C/KM IN ADDITION TO A DRIER MID-LEVEL AIRMASS...WHICH SHOULD CONTRIBUTE TO MLCAPE VALUES OF 1500-2500 J/KG AND DCAPE OF 1000-1250 J/KG AT PEAK HEATING. FORCING FOR ASCENT MON AFT/EVE WILL CONSIST OF WEAK/SHALLOW LOW- LEVEL CONVERGENCE ASSOCIATED WITH A SHARPENING LEE TROUGH...AND DPVA ASSOC/W SMALL AMPLITUDE DISTURBANCES IN CYCLONIC FLOW ALOFT...WHICH SHOULD BE MORE THAN ENOUGH TO RESULT IN SCATTERED TO WIDESPREAD CONVECTION GIVEN MODERATE DIURNAL DESTABILIZATION AND DEEP MOISTURE WITH PWAT VALUES OF ~1.75". THE EXACT TIMING AND COVERAGE OF CONVECTION REMAINS DIFFICULT TO ASCERTAIN GIVEN THAT IT WILL HIGHLY DEPEND ON THE PRECISE TIMING OF SMALL AMPLITUDE DISTURBANCES ALOFT...AND PERHAPS FURTHER COMPLICATED BY THE REMNANTS OF ANY UPSTREAM MCS ACTIVITY (IF SUCH ACTIVITY DEVELOPS OVER THE TN VALLEY) LATE TONIGHT AND MONDAY MORNING...SIMILAR TO THE PAST FEW DAYS. AT THIS TIME WILL MAKE LITTLE CHANGE TO THE PREVIOUS FCST WITH PRECIP CHANCES ~50%. CHANCES SHOULD DECREASE WITHIN SEVERAL HOURS AFTER SUNSET...THOUGH A SLIGHT TO LOW CHANCE OF SHOWERS (PERHAPS AN ISOLD STORM) WILL PERSIST AFTER MIDNIGHT GIVEN DEEP MOISTURE...MARGINAL NOCTURNAL INSTABILITY AND CYCLONIC FLOW ALOFT. TEMPERATURES: HIGHS ON MON WILL BE SIMILAR TO BUT PERHAPS SLIGHTLY WARMER THAN TODAY DEPENDING ON CLOUD COVER AND CONVECTION...IN THE UPPER 80S TO LOWER 90S...OR 88-93F...WARMEST IN THE EAST. LOWS MON NIGHT ABOVE NORMAL IN THE LOWER TO MID 70S GIVEN CLOUD COVER AND LIGHT SOUTHERLY FLOW IN ADVANCE OF THE COLD FRONT APPROACHING THE SOUTHERN APPALACHIANS. SEVERE THREAT: THE OVERALL ENVIRONMENT ON MON AFT/EVE WILL BE SIMILAR TO TODAY... WITH SLIGHTLY STRONGER DEEP LAYER SHEAR (~20 KT) AND...PERHAPS MORE IMPORTANTLY...SLIGHTLY STEEPER MID-LEVEL LAPSE RATES AND A DRIER MID-LEVEL AIRMASS THAT WILL CONTRIBUTE TO STRONGER DCAPE DURING PEAK HEATING. WITH THE ABOVE IN MIND...WILL INCLUDE MENTION IN THE HAZARDOUS WEATHER OUTLOOK OF A POTENTIAL FOR ISOLD SEVERE STORMS CAPABLE OF PRODUCING DAMAGING WINDS DURING THE AFT/EVE. IF FORCING FOR ASCENT IS JUXTAPOSED WELL WITH PEAK HEATING AND DEVELOPMENT IS LARGELY DELAYED UNTIL MID/LATE AFTERNOON...A BETTER SEVERE WIND THREAT COULD EMERGE VIA ORGANIZATION ASSOC/W OUTFLOW GIVEN AN ENVIRONMENT THAT WOULD FAVOR ROBUST COLD POOLS. -VINCENT && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 200 PM SUNDAY... MORE AND MORE THE LONG TERM IS SHAPING UP TO BE AN EXTENDED PERIOD OF DRY WEATHER CHARACTERIZED BY NEAR NORMAL TEMPERATURES FOR EARLY SEPTEMBER. THE BEST CHANCE FOR RAIN COULD BE VERY EARLY ON IN THE PERIOD AS AN UPPER TROUGH SITS OVER THE EAST COAST WITH A SURFACE LOW MOVING THROUGH SOUTHERN QUEBEC. ON TUESDAY AFTERNOON THE MAIN FRONTAL SYSTEM ASSOCIATED WITH THIS LOW SHOULD BE JUST EAST OF THE CWA WITH REINFORCING BOUNDARY OVER THE APPALACHIANS. GFS FORECAST SOUNDINGS IN BUFKIT INDICATE THAT AN ELEVATED MIXED LAYER WILL STILL EXIST BUT WILL BECOME INCREASING CAPPED AS THE DAY GOES ON. THE BEST CONDITIONS FOR ANY KIND OF SUSTAINED CONVECTION SHOULD BE FROM FAYETTEVILLE SOUTH AND EAST. BACK TO THE WEST A LARGE SURFACE HIGH WILL SLOWLY BUILD EASTWARD...ENFORCING MORE STABLE CONDITIONS WITH TIME. WILL KEEP CHANCE POPS IN THE SOUTHEAST WITH SLIGHT CHANCE BACK TO THE WEST. THIS SHOULD BE THE HOTTEST DAY OF THE LONG TERM AS THE FULL EFFECTS OF THE FRONT WILL NOT BE REALIZED UNTIL WEDNESDAY. HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES. LOWS IN THE LOWER 60S NW TO UPPER 60S SOUTH. WEDNESDAY THROUGH FRIDAY CENTRAL NC WILL BE UNDER A DOMINANT SURFACE HIGH PRESSURE AND A VERY WEAK UPPER LEVEL FLOW REGIME BETWEEN THE UPPER TROUGH TO THE NORTH AND THE VERY STRONG UPPER HIGH OVER THE SOUTHWESTERN CONUS. WEATHER SHOULD REMAIN DRY AND HIGHS WILL BE IN THE MID 80S WITH LOWS IN THE LOW TO MID 60S. THE STRONG HIGH OVER THE SOUTHWESTERN CONUS WILL BEGIN TO BREAK DOWN OVER THE WEEKEND AND A WEAK UPPER LEVEL LOW OVER THE DEEP SOUTH WILL SLOWLY BEGIN TO ADVECT MOISTURE TOWARDS THE SOUTHWESTERN PORTIONS OF OUR CWA. IT IS VERY POSSIBLE AT THIS POINT THAT THE WEEKEND COULD REMAIN DRY BUT THE CHANCES FOR PRECIPITATION WILL CERTAINLY BE GREATER THAN MIDWEEK. WILL CARRY SLIGHT CHANCE POPS SATURDAY AND SUNDAY AFTERNOON WITH HIGHEST VALUES IN THE SOUTHWEST BUT STILL FEEL LIKE SURFACE HIGH WILL KEEP WEATHER LARGELY DRY THROUGH THE END OF THE LONG TERM. MAY SEE A VERY GRADUAL WARMING TOWARDS THE UPPER 80S BY THE WEEKEND WITH LOWS TRENDING TOWARDS THE UPPER 60S. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 1200 PM SUNDAY... 24-HR TAF PERIOD: MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY MORNING. LOOKING AHEAD: THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...RTE AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 PM EDT SUN SEP 01 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT... THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY AND LINGER THROUGH THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SUNDAY... UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE (IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SUNDAY... SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE... THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT 1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS... WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS... ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15 KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN CONVECTION DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430 M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR 90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 200 PM SUNDAY... MORE AND MORE THE LONG TERM IS SHAPING UP TO BE AN EXTENDED PERIOD OF DRY WEATHER CHARACTERIZED BY NEAR NORMAL TEMPERATURES FOR EARLY SEPTEMBER. THE BEST CHANCE FOR RAIN COULD BE VERY EARLY ON IN THE PERIOD AS AN UPPER TROUGH SITS OVER THE EAST COAST WITH A SURFACE LOW MOVING THROUGH SOUTHERN QUEBEC. ON TUESDAY AFTERNOON THE MAIN FRONTAL SYSTEM ASSOCIATED WITH THIS LOW SHOULD BE JUST EAST OF THE CWA WITH REINFORCING BOUNDARY OVER THE APPALACHIANS. GFS FORECAST SOUNDINGS IN BUFKIT INDICATE THAT AN ELEVATED MIXED LAYER WILL STILL EXIST BUT WILL BECOME INCREASING CAPPED AS THE DAY GOES ON. THE BEST CONDITIONS FOR ANY KIND OF SUSTAINED CONVECTION SHOULD BE FROM FAYETTEVILLE SOUTH AND EAST. BACK TO THE WEST A LARGE SURFACE HIGH WILL SLOWLY BUILD EASTWARD...ENFORCING MORE STABLE CONDITIONS WITH TIME. WILL KEEP CHANCE POPS IN THE SOUTHEAST WITH SLIGHT CHANCE BACK TO THE WEST. THIS SHOULD BE THE HOTTEST DAY OF THE LONG TERM AS THE FULL EFFECTS OF THE FRONT WILL NOT BE REALIZED UNTIL WEDNESDAY. HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES. LOWS IN THE LOWER 60S NW TO UPPER 60S SOUTH. WEDNESDAY THROUGH FRIDAY CENTRAL NC WILL BE UNDER A DOMINANT SURFACE HIGH PRESSURE AND A VERY WEAK UPPER LEVEL FLOW REGIME BETWEEN THE UPPER TROUGH TO THE NORTH AND THE VERY STRONG UPPER HIGH OVER THE SOUTHWESTERN CONUS. WEATHER SHOULD REMAIN DRY AND HIGHS WILL BE IN THE MID 80S WITH LOWS IN THE LOW TO MID 60S. THE STRONG HIGH OVER THE SOUTHWESTERN CONUS WILL BEGIN TO BREAK DOWN OVER THE WEEKEND AND A WEAK UPPER LEVEL LOW OVER THE DEEP SOUTH WILL SLOWLY BEGIN TO ADVECT MOISTURE TOWARDS THE SOUTHWESTERN PORTIONS OF OUR CWA. IT IS VERY POSSIBLE AT THIS POINT THAT THE WEEKEND COULD REMAIN DRY BUT THE CHANCES FOR PRECIPITATION WILL CERTAINLY BE GREATER THAN MIDWEEK. WILL CARRY SLIGHT CHANCE POPS SATURDAY AND SUNDAY AFTERNOON WITH HIGHEST VALUES IN THE SOUTHWEST BUT STILL FEEL LIKE SURFACE HIGH WILL KEEP WEATHER LARGELY DRY THROUGH THE END OF THE LONG TERM. MAY SEE A VERY GRADUAL WARMING TOWARDS THE UPPER 80S BY THE WEEKEND WITH LOWS TRENDING TOWARDS THE UPPER 60S. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 1200 PM SUNDAY... 24-HR TAF PERIOD: MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY MORNING. LOOKING AHEAD: THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...HARTFIELD LONG TERM...ELLIS AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1234 PM EDT SUN SEP 01 2013 .SYNOPSIS... A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH MONDAY. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY NIGHT... THEN PUSH SLOWLY SOUTHEAST THROUGH THE CAROLINAS ON TUESDAY. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY AND LINGER THROUGH THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SUNDAY... UPPER LEVEL DISTURBANCES WILL TRAVERSE THE REGION IN STRENGTHENING CYCLONIC FLOW ALOFT THIS AFT/EVE...IN THE PRESENCE OF MODERATE INSTABILITY (MLCAPE 1500-2000 J/KG) ASSOC/W STRONG INSOLATION AND A VERY MOIST LOW-LEVEL AIRMASS. AS OF 16Z...ISOLATED TO SCATTERED CONVECTION HAS DEVELOPED ALONG THE HIGHWAY 1 IN ASSOCIATION WITH STRONG INSOLATION /RAPID EROSION OF CINH/ AND A SMALL AMPLITUDE DISTURBANCE ALOFT PER WV IMAGERY AND RAP DATA. EXPECT THE BEST CHANCE FOR CONVECTION THIS AFTERNOON EAST OF THE HIGHWAY 1 CORRIDOR AS THE AFOREMENTIONED DISTURBANCE TRACKS SLOWLY EAST TOWARD THE COAST...FOLLOWED BY INCREASING CHANCES IN THE WESTERN PIEDMONT BY LATE THIS AFTERNOON THROUGH THIS EVENING AS A SMALL AMPLITUDE WAVE (IN EASTERN KY AT 16Z) TRACKS SLOWLY EAST IN VICINITY OF THE NORTHWEST NC AND SOUTHWEST VA BORDER. DESPITE MODERATE INSTABILITY...GIVEN WEAK DEEP LAYER SHEAR (<= 20 KT)...WEAK TO MARGINAL DCAPE (500-1000 J/KG) AND WEAK MID-LEVEL LAPSE RATES...FEEL THAT THE POTENTIAL FOR AN ISOLD SVR STORM IS TOO LOW TO WARRANT MENTION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. A SLIGHT CHANCE OF SHOWERS WILL LIKELY PERSIST OVERNIGHT GIVEN EXCELLENT DEEP LAYER MOISTURE AND MARGINAL NOCTURNAL INSTABILITY IN THE PRESENCE OF CYCLONIC FLOW ALOFT...WITH THE RELATIVE BEST CHANCE NEAR THE VA BORDER WHERE DPVA APPEARS MORE LIKELY. EXPECT HIGHS IN THE UPPER 80S TO LOWER 90S...OR 87-92F...HIGHEST IN THE COASTAL PLAIN. LOWS TONIGHT IN THE LOWER TO MID 70S...OR 70-74F. -VINCENT && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SUNDAY... SHOULD BE ANOTHER FAIRLY ACTIVE DAY. LONGWAVE TROUGHING WILL DIG DOWN OVER ERN NOAM AS A SHORTWAVE TROUGH FROM SRN ONTARIO THROUGH MI SWINGS ESE... YIELDING HEIGHT FALLS OF AROUND 20-30 M OVER NC MON/MON NIGHT. THE COLD FRONT NOW STRETCHING FROM THE UPPER MIDWEST LOW SSW THROUGH THE CENTRAL PLAINS WILL CONTINUE TO PUSH ESE... THROUGH THE OH VALLEY MONDAY THEN TO THE APPALACHIANS BY MONDAY NIGHT... AS THE PRECEDING PIEDMONT TROUGH SHARPENS. THE LOW-MID LEVEL FLOW FROM THE SW AND WSW WILL ENSURE CONTINUED ABOVE-NORMAL MOISTURE CONTENT THROUGH THE COLUMN WITH PW VALUES HOLDING AT 1.7-1.8 INCHES FROM THE TRIANGLE EAST/SE... ALTHOUGH THE MORE WNW DOWNSLOPE FLOW OVER THE NW PIEDMONT IS EXPECTED TO CAUSE PW VALUES TO DROP BELOW 1.5 IN. MODELS DIFFER CONSIDERABLY WITH THEIR INSTABILITY... WITH THE NAM DEPICTING LOWER MLCAPE UNDER 2000 J/KG FROM THE TRIANGLE SOUTH AND EAST WITH 2000-2500 J/KG OVER THE NW CWA... WHILE THE GFS IS NEARLY OPPOSITE WITH MLCAPE LOW OVER THE NW AND PEAKING AT 1500-2500 J/KG OVER THE SOUTH AND EAST MONDAY AFTERNOON. THIS IS LARGELY A REFLECTION OF SURFACE DEW POINTS... WHICH ARE DIFFICULT TO RESOLVE IN THE MODELS AT THIS RANGE. AS SUCH... IT IS TOUGH TO DETERMINE THE THREAT OF STRONG STORMS... ALTHOUGH THE DEEP LAYER BULK SHEAR REMAINS MARGINAL AT JUST 10-15 KTS... WHICH WILL LIMIT STORM ORGANIZATION AND STRENGTH. IN ANY CASE... WE SHOULD STILL SEE AT LEAST SCATTERED STORMS DEVELOPING BY AFTERNOON... MOST LIKELY STARTING OUT AS ISOLATED MOUNTAIN CONVECTION DROPPING TO THE ESE AND CONGEALING INTO A BROKEN LINE OF COLD POOL DOMINATED STORMS. GFS STATISTICAL GUIDANCE HIGHS APPEAR TOO WARM GIVEN THAT WE SHOULD SEE QUITE A BIT OF CONVECTIVE DEBRIS MID/HIGH CLOUDS... AND ITS JUMP IN AFTERNOON THICKNESS (BEYOND 1430 M) IS A VAST DEPARTURE FROM OTHER GUIDANCE. WILL RETAIN HIGHS NEAR 90 TO THE LOWER 90S. LOWS 69-73 WITH PARTLY CLOUDY SKIES AND A LINGERING ISOLATED SHOWER/STORM CHANCE. -GIH && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 215 AM SUNDAY... THE LONG TERM PATTERN WILL FEATURES A PERSISTENT HIGH-AMPLITUDE SOUTHERN ROCKY MOUNTAIN/WESTERN PLAINS RIDGE AND AN EASTERN U.S. TROUGH THAT GRADUALLY DEAMPLIFIES AT THE END OF THE PERIOD. WHILE THE MAIN TROUGH LIFTS NORTH LATE IN THE WORK WEEK...A MID-LEVEL WEAKNESS AND TROUGH LINGERS WEST OF OUR REGION ON FRIDAY AND SATURDAY. THE UPPER LEVEL TROUGH AXIS SWINGS THROUGH CENTRAL NC ON TUESDAY AND TUESDAY NIGHT. THE GFS IS THE FASTEST SET OF GUIDANCE WHILE THE NAM IS THE SLOWEST WITH THE EC IN BETWEEN. THE TIMING OF THE UPPER LEVEL TROUGH IS CONSISTENT WITH THE PASSAGE OF THE SURFACE COLD FRONT. GIVEN THE MEAGER FLOW ALOFT AND THE WEAK SURFACE HIGH BEHIND THE FRONT AS WELL AS GUIDANCE TRENDS WHICH SUGGEST A SLOWER FRONTAL PASSAGE...PREFER TO USE THE SLOWER TIMING. MUCH DRIER AIR WILL BE WORKING INTO THE WESTERN PIEDMONT BY EARLY TUESDAY AFTERNOON WHILE THE DEEPEST MOISTURE AND INSTABILITY WILL BE LOCATED ACROSS THE COASTAL PLAIN. HIGHS TUESDAY WILL RANGE IN THE UPPER 80S.. BUT WITH A COOLER AIR MASS ARRIVING FROM THE WEST...LOWS TUESDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE TRIAD TO THE UPPER 60S IN THE SOUTHERN COASTAL PLAIN. THE FRONT WILL CONTINUE TO PUSH SOUTH ON WEDNESDAY AND MUCH DRIER AIR WILL WORK INTO THE REGION FROM THE NORTH. A MORNING SHOWER IS STILL POSSIBLE IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS AS THE LOW LEVEL MOISTURE IN THAT AREA IS A BIT MORE STUBBORN. AFTERNOON PRECIPITABLE WATER VALUES WILL RANGE FROM AROUND 0.75 INCHES NEAR THE VA BORDER TO 1.5 INCHES TOWARD FAR SOUTHERN PORTIONS OF THE COASTAL PLAIN. HIGHS WILL RANGE IN THE LOWER TO MID 80S AND LOWS WEDNESDAY NIGHT WILL RANGE IN THE LOWER TO MID 60S. FAIRLY QUIET WEATHER IS EXPECTED ON THURSDAY AND FRIDAY AS HIGH PRESSURE LINGERS ACROSS THE OHIO VALLEY AND ANOTHER COLD FRONT PUSHES SOUTH ACROSS THE NORTHEAST BUT STALLS IN THE MID-ATLANTIC. THE NORTHEAST LOW LEVEL FLOW ON THURSDAY VEERS AROUND TO SOUTH AND SOUTHEAST ON FRIDAY AND CONTINUES INTO SATURDAY. THE RESULT WILL BE A GRADUAL INCREASE IN MOISTURE AND SOME ENHANCED UPSLOPE FLOW ACROSS WESTERN NC. THIS PATTERN WILL LIKELY RESULT IN SOME ISOLATED AFTERNOON AND EVENING CONVECTION...MAINLY DRIVEN BY LOCAL PROCESSES SUCH AS DIFFERENTIAL HEATING IN THE MOUNTAINS AND ALONG THE SEA BREEZE. OTHERWISE EXPECT PARTLY CLOUDY SKIES WITH SOME MORNING FOG/STRATUS POSSIBLE ON FRIDAY AND SATURDAY MORNINGS. HIGHS DURING THE PERIOD WILL GENERALLY RANGE IN THE LOWER TO MID 80S WITH MORNING LOWS MAINLY IN THE LOWER TO MID 60S. -BLAES && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 1200 PM SUNDAY... 24-HR TAF PERIOD: MVFR/VFR CEILINGS RANGING FROM 1500-4500 FT AGL ARE EXPECTED ACROSS CENTRAL NC THIS AFTERNOON...WITH THE BEST CHANCE OF MVFR CEILINGS AT THE INT/GSO TERMINALS THROUGH EARLY/MID AFTERNOON...THEN EQUAL CHANCES AT ALL TERMINALS MID AFTERNOON THROUGH MIDNIGHT IN ASSOC/W SCATTERED SHOWERS AND THUNDERSTORMS. SUB-VFR CEILINGS OR FOG WILL BE POSSIBLE ONCE AGAIN OVERNIGHT...PRIMARILY BETWEEN 06-14Z MONDAY MORNING. LOOKING AHEAD: THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE MON AFT/EVE INTO MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND T