Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/08/13


AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
250 PM MST TUE AUG 6 2013 .UPDATE... UPDATED AVIATION DISCUSSION... && .SYNOPSIS... SKIES WILL GRADUALLY CLEAR TONIGHT AS DRIER AIR MOVES INTO THE REGION FROM THE SOUTHWEST. DRY WEATHER WILL PREVAIL FOR MUCH OF THE UPCOMING WEEK WITH PRECIP CHANCES CONFINED MAINLY TO EASTERN ARIZONA. TEMPERATURES WILL REMAIN BELOW NORMAL WEDNESDAY...BUT COULD APPROACH THE 110 DEGREE MARK BY EARLY NEXT WEEK. && .DISCUSSION... REGIONAL RADAR MOSAIC INDICATES SHOWERS ARE TAPERING OFF ACROSS THE PHOENIX METRO...WHILE NEW SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS EASTERN/SOUTHERN ARIZONA. A BAND OF THUNDERSTORMS WERE ALSO LOCATED ACROSS YAVAPAI COUNTY AND WERE MOVING SOUTHWARD /IN THE DEFORMATION AREA OF THE UPPER LEVEL SHORTWAVE/. MEANWHILE TO THE WEST...JUST YOUR AVERAGE AUGUST DAY WITH TEMPS AROUND 100 WITH SUNNY SKIES AND NO PRECIP TO SPEAK OF. 17Z HRRR MODEL SEEMS TO HAVE CAUGHT ON TO THE PRESENT SITUATION AND ADVERTISES CONVECTION TO MOVE INTO SOUTHERN GILA COUNTY LATER THIS AFTERNOON...MEANWHILE THE YAVAPAI STORMS WILL TRY AND DRIFT SOUTHWARD INTO THE FAR NORTHEAST CORNER OF THE PHX METRO. SPC MESO PAGE INDICATES A FEW HUNDRED J/KG OF MLCAPE RESIDES IN THIS AREA WHICH HAS BEEN LARGELY FREE OF RAIN TODAY...SEEMS PLAUSIBLE A FEW STORMS COULD SURVIVE IN THAT ENVIRONMENT. THIS IS IN LINE WITH PREVIOUS UPDATES TO THE FORECAST...AND I WILL HANG ONTO 10-20 POPS ACROSS THE PHOENIX AREA THROUGH THE EVENING...WITH HIGHER POPS IN THE MOUNTAINS TO THE EAST. THE TROUGH WILL MOVE OUT OF THE AREA TONIGHT AND SUBSIDENCE BEHIND THE LOW SHOULD DRY THINGS OUT BEFORE MIDNIGHT. THE FORECAST FOR WEDNESDAY THROUGH NEXT WEEK IS LARGELY UNCHANGED AS THE UPPER FLOW BECOMES MORE SOUTHWESTERLY AND MOISTURE GETS DISPLACED INTO NEW MEXICO. COULD SEE SOME ISOLATED MOUNTAIN SHOWERS/THUNDERSTORMS WEDNESDAY/THURSDAY GIVEN LINGERING PWATS AROUND 1.1-1.3 INCHES...BUT CHANCES SHOULD REMAIN BELOW CLIMO GIVEN UNFAVORABLE FLOW ALOFT ALL THE WAY THROUGH EARLY NEXT WEEK. A GRADUAL INCREASE IN TEMPERATURES WILL TAKE PLACE THROUGH THE UPCOMING WEEKEND...BUT WITH THE UPPER LOW TO THE NORTHWEST...500MB HEIGHTS WILL REMAIN BELOW 590DM AND AFTERNOON HIGHS WILL STAY WITHIN A COUPLE DEGREES OF NORMAL THROUGH SATURDAY. MODELS ARE IN GOOD AGREEMENT LIFTING THE UPPER LOW NORTHEASTWARD LATE THIS WEEKEND ALLOWING FOR HEIGHTS TO INCREASE ACROSS THE DESERT SOUTHWEST AND SHIFTING THE SUBTROPICAL HIGH CLOSER TO THE FOUR CORNERS REGION. WARMING TEMPERATURES SUNDAY AND MONDAY ARE EXPECTED WITH SOME LOWER DESERT HIGHS AROUND 110 DEGREES. AN INCREASE IN BOUNDARY LAYER MOISTURE IS EXPECTED ACROSS FAR EASTERN ARIZONA EARLY NEXT WEEK ALLOWING FOR SLIGHTLY BETTER CHANCES FOR MONSOON STORMS MAINLY ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... SHOWERS AND CLOUDINESS WILL CONTINUE TO DECLINE OVER THE PHOENIX AREA THIS AFTERNOON. HOWEVER...STORMS OVER PINAL COUNTY AND FAR NORTHEAST MARICOPA COUNTY ARE STILL POSSIBLE THROUGH 03Z AND COULD BRUSH NORTH AND EAST PORTIONS OF THE METRO BUT PROBABILITY TOO LOW TO REFLECT IN THE TAFS. SURFACE WINDS WILL FAVOR EASTERLY DIRECTIONS THROUGH WEDNESDAY MORNING EXCEPT FOR A SHORT PERIOD LATE THIS AFTERNOON AND EVENING. ANTICIPATE CLEARING SKIES OVERNIGHT. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... CLEAR SKIES CAN BE EXPECTED THROUGH WEDNESDAY. WINDS WILL FAVOR SOUTHERLY DIRECTIONS OVER THE LOWER COLORADO RIVER VALLEY...WITH GUSTS OF 20-25 KTS IN THE AFTERNOONS. WINDS WILL BE LIGHTER OVER THE IMPERIAL VALLEY AND FAVOR EASTERLY DIRECTIONS IN THE AFTERNOONS...WESTERLY AT NIGHT. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... THURSDAY THROUGH MONDAY... AN AREA OF LOW PRESSURE WILL REMAIN SITUATED ALONG THE CALIFORNIA COAST THURSDAY THROUGH THE WEEKEND KEEPING A RATHER DRY SOUTHWEST FLOW ALOFT IN PLACE ACROSS THE AREA. THE ONLY THREAT FOR SHOWERS OR THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN AREAS EAST OF PHOENIX STARTING ON SATURDAY AND CONTINUING INTO MONDAY. A SLIGHT WARMING TREND IS EXPECTED WITH HIGH TEMPERATURES CLIMBING FROM NEAR OR SLIGHTLY BELOW NORMAL VALUES THURSDAY TO A FEW DEGREES ABOVE CLIMO BY THE WEEKEND. MINIMUM HUMIDITIES WILL RANGE FROM THE LOW TEENS TO SINGLE DIGITS OVER THE LOWER DESERTS THROUGH THE PERIOD...WITH FAIR RECOVERIES AT NIGHT. NO SIGNIFICANT WIND IS ANTICIPATED...JUST LOCAL AFTERNOON AND EARLY EVENING GUSTINESS FAVORING UPSLOPE OR THE SOUTHWEST. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS/KUHLMAN AVIATION...AJ FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
108 PM MST TUE AUG 6 2013 .SYNOPSIS... SKIES WILL GRADUALLY CLEAR TONIGHT AS DRIER AIR MOVES INTO THE REGION FROM THE SOUTHWEST. DRY WEATHER WILL PREVAIL FOR MUCH OF THE UPCOMING WEEK WITH PRECIP CHANCES CONFINED MAINLY TO EASTERN ARIZONA. TEMPERATURES WILL REMAIN BELOW NORMAL WEDNESDAY...BUT COULD APPROACH THE 110 DEGREE MARK BY EARLY NEXT WEEK. && .DISCUSSION... REGIONAL RADAR MOSAIC INDICATES SHOWERS ARE TAPERING OFF ACROSS THE PHOENIX METRO...WHILE NEW SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS EASTERN/SOUTHERN ARIZONA. A BAND OF THUNDERSTORMS WERE ALSO LOCATED ACROSS YAVAPAI COUNTY AND WERE MOVING SOUTHWARD /IN THE DEFORMATION AREA OF THE UPPER LEVEL SHORTWAVE/. MEANWHILE TO THE WEST...JUST YOUR AVERAGE AUGUST DAY WITH TEMPS AROUND 100 WITH SUNNY SKIES AND NO PRECIP TO SPEAK OF. 17Z HRRR MODEL SEEMS TO HAVE CAUGHT ON TO THE PRESENT SITUATION AND ADVERTISES CONVECTION TO MOVE INTO SOUTHERN GILA COUNTY LATER THIS AFTERNOON...MEANWHILE THE YAVAPAI STORMS WILL TRY AND DRIFT SOUTHWARD INTO THE FAR NORTHEAST CORNER OF THE PHX METRO. SPC MESO PAGE INDICATES A FEW HUNDRED J/KG OF MLCAPE RESIDES IN THIS AREA WHICH HAS BEEN LARGELY FREE OF RAIN TODAY...SEEMS PLAUSIBLE A FEW STORMS COULD SURVIVE IN THAT ENVIRONMENT. THIS IS IN LINE WITH PREVIOUS UPDATES TO THE FORECAST...AND I WILL HANG ONTO 10-20 POPS ACROSS THE PHOENIX AREA THROUGH THE EVENING...WITH HIGHER POPS IN THE MOUNTAINS TO THE EAST. THE TROUGH WILL MOVE OUT OF THE AREA TONIGHT AND SUBSIDENCE BEHIND THE LOW SHOULD DRY THINGS OUT BEFORE MIDNIGHT. THE FORECAST FOR WEDNESDAY THROUGH NEXT WEEK IS LARGELY UNCHANGED AS THE UPPER FLOW BECOMES MORE SOUTHWESTERLY AND MOISTURE GETS DISPLACED INTO NEW MEXICO. COULD SEE SOME ISOLATED MOUNTAIN SHOWERS/THUNDERSTORMS WEDNESDAY/THURSDAY GIVEN LINGERING PWATS AROUND 1.1-1.3 INCHES...BUT CHANCES SHOULD REMAIN BELOW CLIMO GIVEN UNFAVORABLE FLOW ALOFT ALL THE WAY THROUGH EARLY NEXT WEEK. A GRADUAL INCREASE IN TEMPERATURES WILL TAKE PLACE THROUGH THE UPCOMING WEEKEND...BUT WITH THE UPPER LOW TO THE NORTHWEST...500MB HEIGHTS WILL REMAIN BELOW 590DM AND AFTERNOON HIGHS WILL STAY WITHIN A COUPLE DEGREES OF NORMAL THROUGH SATURDAY. MODELS ARE IN GOOD AGREEMENT LIFTING THE UPPER LOW NORTHEASTWARD LATE THIS WEEKEND ALLOWING FOR HEIGHTS TO INCREASE ACROSS THE DESERT SOUTHWEST AND SHIFTING THE SUBTROPICAL HIGH CLOSER TO THE FOUR CORNERS REGION. WARMING TEMPERATURES SUNDAY AND MONDAY ARE EXPECTED WITH SOME LOWER DESERT HIGHS AROUND 110 DEGREES. AN INCREASE IN BOUNDARY LAYER MOISTURE IS EXPECTED ACROSS FAR EASTERN ARIZONA EARLY NEXT WEEK ALLOWING FOR SLIGHTLY BETTER CHANCES FOR MONSOON STORMS MAINLY ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... SCT TO NUMEROUS LIGHT -SHRA WILL AFFECT CNTRL ARIZONA TERMINALS THROUGH AT LEAST 18Z...WITH SOME LESSER CHANCE OF RAIN LINGERING INTO THE EARLY AFTERNOON. CIGS SHOULD REMAIN AOA 8K FT WITH VFR VSBYS...THOUGH ISOLD AREAS COULD VERY BRIEFLY DIP INTO MVFR CATEGORIES IN MORE MDT SHRA. COVERAGE AND PROBABILITIES OF LOWER FLIGHT CATEGORIES ARE FAR TOO REMOTE TO EVEN MENTION IN THIS TAF PACKAGE. PRIMARY IMPACTS WILL BE PERIODIC WET CONDITIONS FOR GROUNDS CREWS AND PARTIAL MTN OBSCURATION ON DEPARTURE/APPROACH. SFC WINDS WILL GENERALLY REMAIN ELY THROUGH THE MORNING BEFORE GRADUALLY VEERING TO SWLY DURING THE AFTERNOON. THERE MAY BE OCCASIONAL PERIODS OF MORE VARIABLE WINDS WITHIN SHRA THIS MORNING. OTHERWISE...CIGS SHOULD SLOWLY LIFT AND CLEAR BY WEDNESDAY MORNING. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... FAIRLY EXTENSIVE HIGH CLOUDS WILL AFFECT TERMINALS THROUGH TUESDAY EVENING...WITH SHOWERS REMAINING WELL TO THE EAST INTO CNTRL ARIZONA. WINDS WILL GENERALLY REMAIN FROM A SLY/SELY DIRECTION THROUGH THE EVENING WITH OCCASIONAL HIGHER GUSTS AT KBLH. WITH MODERATE CONFIDENCE...HAVE SFC WINDS SHIFTING TO WLY AT KIPL AFTER SUNSET. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... THURSDAY THROUGH MONDAY... AN AREA OF LOW PRESSURE WILL REMAIN SITUATED ALONG THE CALIFORNIA COAST THURSDAY THROUGH THE WEEKEND KEEPING A RATHER DRY SOUTHWEST FLOW ALOFT IN PLACE ACROSS THE AREA. THE ONLY THREAT FOR SHOWERS OR THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN AREAS EAST OF PHOENIX STARTING ON SATURDAY AND CONTINUING INTO MONDAY. A SLIGHT WARMING TREND IS EXPECTED WITH HIGH TEMPERATURES CLIMBING FROM NEAR OR SLIGHTLY BELOW NORMAL VALUES THURSDAY TO A FEW DEGREES ABOVE CLIMO BY THE WEEKEND. MINIMUM HUMIDITIES WILL RANGE FROM THE LOW TEENS TO SINGLE DIGITS OVER THE LOWER DESERTS THROUGH THE PERIOD...WITH FAIR RECOVERIES AT NIGHT. NO SIGNIFICANT WIND IS ANTICIPATED...JUST LOCAL AFTERNOON AND EARLY EVENING GUSTINESS FAVORING UPSLOPE OR THE SOUTHWEST. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS/KUHLMAN AVIATION...MO FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
916 AM MST TUE AUG 6 2013 .SYNOPSIS... A TEMPORARY INCREASE IN MONSOON MOISTURE ASSOCIATED WITH AN UPPER LEVEL LOW WILL BRING PERIODS OF LIGHT RAIN TODAY AND THE POSSIBILITY OF AN ISOLATED THUNDERSTORM. THE EXTENSIVE CLOUD COVER AND LIGHT RAIN WILL LEAD TO A MUCH COOLER DAY TODAY WITH HIGHS WELL BELOW NORMAL. A DRYING TREND WILL START ON WEDNESDAY AND WILL CONTINUE INTO THE WEEKEND...KEEPING PRECIPITATION CHANCES CONFINED MAINLY TO EASTERN ARIZONA. && .DISCUSSION... STILL LOOKING AT QUITE A BIT OF SHOWERS ACROSS THE REGION AS OF 16Z...AS A SHORTWAVE TROUGH SLOWLY MOVES THROUGH SONORA AND ARIZONA. RAINFALL TOTALS HAVE BEEN ON THE LOW SIDE SO FAR...GENERALLY A FEW HUNDREDTHS TO 0.15 INCHES VALLEY-WIDE. NOT SURPRISINGLY...THIS HAS ALSO PUT A SERIOUS DENT IN OUR TEMPERATURES. READINGS AS OF 16Z ARE ONLY IN THE LOW/MID 70S ACROSS THE METRO...EVEN SKY HARBOR IS STILL SITTING IN THE UPPER 70S. MEANWHILE TO THE WEST...DRY CONDITIONS REMAIN IN PLACE AND TEMPS HAVE BEEN WARMING ON SCHEDULE. THE SHORTWAVE TROUGH WILL MOVE THROUGH CENTRAL ARIZONA LATER THIS MORNING AND A GRADUAL DRYING TREND SHOULD COMMENCE AFTER NOON. RADAR MOSAIC ALREADY STARTING TO INDICATE THE WESTERN EDGE OF THE PRECIP IS BREAKING DOWN OVER WESTERN MARICOPA COUNTY...AND THIS TREND SHOULD CONTINUE THROUGH THE AFTERNOON HOURS. THAT BEING SAID...A SECONDARY TROUGH SOUTH OF PIMA COUNTY WILL MOVE INTO ARIZONA LATER TODAY. HI-RES WRF MODELS AND THE HRRR INDICATE CONVECTION SHOULD DEVELOP OVER THE MOUNTAINS EAST OF PHOENIX AFTER 21Z...AND I INCREASED POPS IN THESE AREAS BY ABOUT 10-20 PERCENT. RAP/HRRR MODEL ALSO INDICATING SCATTERED SHOWERS REMAINING IN PLACE ACROSS THE METRO THROUGH MID AFTERNOON. I INCREASED POPS ACROSS THE METRO A BIT AS WELL THROUGH 00Z ALTHOUGH THEY SHOULD BE SCATTERED IN NATURE. THE THREAT FOR SEVERE WEATHER EAST OF PHOENIX APPEARS SLIM GIVEN MOSTLY MOIST ADIABATIC PROFILES...BUT THUNDER CERTAINLY SEEMS PLAUSIBLE IN AREAS THAT HAVE REMAINED DRY THIS MORNING. TEMPERATURES ARE A HUGE CHALLENGE TODAY. IF CLOUDS HANG AROUND MUCH PAST 1-2PM...WE DONT STAND A CHANCE OF GETTING OUT OF THE UPPER 80S. WITH A LITTLE CLEARING...LOWER 90S SEEMS A MORE LIKELY SOLUTION. I LOWERED HIGHS A BIT AND AM NOW GOING WITH HIGHS AROUND 87-92 IN THE METRO. EITHER WAY...NOWHERE NEAR NORMAL FOR EARLY AUGUST. FORECAST A LITTLE MORE CLEAR-CUT FROM YUMA WESTWARD...HIGHS IN THE LOWER 100S SEEMS LIKE A SAFE BET GIVEN SUNNY SKIES. && .PREVIOUS DISCUSSION... THE SOUTHERN VORT CENTER WILL QUICKLY EXIT THE AREA BY EARLY EVENING...MOVING INTO NORTHERN ARIZONA BY MIDNIGHT TONIGHT. BEHIND THIS...MUCH DRIER WESTERLY FLOW WILL SLIDE INTO THE AREA ENDING ANY RAIN CHANCES AND BRINGING CLEARING SKIES TONIGHT. BOUNDARY LAYER MOISTURE WILL TAKE A BIT LONGER TO BE SCOURED OUT AND ONCE DAYTIME MIXING KICKS ON WEDNESDAY...SURFACE DEW POINTS WILL BE BACK IN THE 40/50S AND MORE LIKE 30/40S FOR THURSDAY THROUGH SATURDAY. AFTER WEDNESDAY...THE MUCH DRIER UPPER LEVEL PATTERN WILL DOMINATE ACROSS THE DESERT SOUTHWEST. A NEARLY STATIONARY CLOSED UPPER LOW SITUATED OFF THE CALIFORNIA COAST WILL FINALLY COME ASHORE SOMETIME WEDNESDAY LOWERING HEIGHTS ACROSS OUR REGION. PWATS FALL TO BELOW AN INCH BY THURSDAY AND 1000-700MB MIXING RATIOS FALL TO AROUND 5 G/KG. A GRADUAL INCREASE IN TEMPERATURES WILL TAKE PLACE THROUGH THE UPCOMING WEEKEND...BUT WITH THE UPPER LOW TO THE NORTHWEST...500MB HEIGHTS WILL REMAIN BELOW 590DM AND AFTERNOON HIGHS WILL STAY WITHIN A COUPLE DEGREES OF NORMAL THROUGH SATURDAY. MODELS ARE IN GOOD AGREEMENT LIFTING THE UPPER LOW NORTHEASTWARD LATE THIS WEEKEND ALLOWING FOR HEIGHTS TO INCREASE ACROSS THE DESERT SOUTHWEST AND SHIFTING THE SUBTROPICAL HIGH CLOSER TO THE FOUR CORNERS REGION. WARMING TEMPERATURES SUNDAY AND MONDAY ARE EXPECTED WITH SOME LOWER DESERT HIGHS AROUND 110 DEGREES. AN INCREASE IN BOUNDARY LAYER MOISTURE IS EXPECTED ACROSS FAR EASTERN ARIZONA EARLY NEXT WEEK ALLOWING FOR SLIGHTLY BETTER CHANCES FOR MONSOON STORMS MAINLY ACROSS THE HIGHER TERRAIN EAST OF PHOENIX. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... SCT TO NUMEROUS LIGHT -SHRA WILL AFFECT CNTRL ARIZONA TERMINALS THROUGH AT LEAST 18Z...WITH SOME LESSER CHANCE OF RAIN LINGERING INTO THE EARLY AFTERNOON. CIGS SHOULD REMAIN AOA 8K FT WITH VFR VSBYS...THOUGH ISOLD AREAS COULD VERY BRIEFLY DIP INTO MVFR CATEGORIES IN MORE MDT SHRA. COVERAGE AND PROBABILITIES OF LOWER FLIGHT CATEGORIES ARE FAR TOO REMOTE TO EVEN MENTION IN THIS TAF PACKAGE. PRIMARY IMPACTS WILL BE PERIODIC WET CONDITIONS FOR GROUNDS CREWS AND PARTIAL MTN OBSCURATION ON DEPARTURE/APPROACH. SFC WINDS WILL GENERALLY REMAIN ELY THROUGH THE MORNING BEFORE GRADUALLY VEERING TO SWLY DURING THE AFTERNOON. THERE MAY BE OCCASIONAL PERIODS OF MORE VARIABLE WINDS WITHIN SHRA THIS MORNING. OTHERWISE...CIGS SHOULD SLOWLY LIFT AND CLEAR BY WEDNESDAY MORNING. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... FAIRLY EXTENSIVE HIGH CLOUDS WILL AFFECT TERMINALS THROUGH TUESDAY EVENING...WITH SHOWERS REMAINING WELL TO THE EAST INTO CNTRL ARIZONA. WINDS WILL GENERALLY REMAIN FROM A SLY/SELY DIRECTION THROUGH THE EVENING WITH OCCASIONAL HIGHER GUSTS AT KBLH. WITH MODERATE CONFIDENCE...HAVE SFC WINDS SHIFTING TO WLY AT KIPL AFTER SUNSET. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... THURSDAY THROUGH MONDAY... AN AREA OF LOW PRESSURE WILL REMAIN SITUATED ALONG THE CALIFORNIA COAST THURSDAY THROUGH THE WEEKEND KEEPING A RATHER DRY SOUTHWEST FLOW ALOFT IN PLACE ACROSS THE AREA. THE ONLY THREAT FOR SHOWERS OR THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN AREAS EAST OF PHOENIX STARTING ON SATURDAY AND CONTINUING INTO MONDAY. A SLIGHT WARMING TREND IS EXPECTED WITH HIGH TEMPERATURES CLIMBING FROM NEAR OR SLIGHTLY BELOW NORMAL VALUES THURSDAY TO A FEW DEGREES ABOVE CLIMO BY THE WEEKEND. MINIMUM HUMIDITIES WILL RANGE FROM THE LOW TEENS TO SINGLE DIGITS OVER THE LOWER DESERTS THROUGH THE PERIOD...WITH FAIR RECOVERIES AT NIGHT. NO SIGNIFICANT WIND IS ANTICIPATED...JUST LOCAL AFTERNOON AND EARLY EVENING GUSTINESS FAVORING UPSLOPE OR THE SOUTHWEST. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS/KUHLMAN AVIATION...MO FIRE WEATHER...CB
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
816 PM MDT WED AUG 7 2013 .UPDATE... && .SHORT TERM...STRONG THUNDERSTORM ACTIVITY HAS SHIFTED EAST OF OUR AREA. THERE WAS A SHOWER BAND OVER THE CENTRAL MOUNTAINS LIFTING NORTH...BUT OVER THE LAST HOUR THIS AREA HAS SUDDENLY CLEARED. THE ZONE BETWEEN THE SOUTHERLIES OVER US AND NORTHERLY FLOW OVER WESTERN COLORADO LOOKS LIKE IT HAS BECOME A BIT MORE DYNAMIC...AND APPARENTLY THIS REGION BECAME SUBSIDENT QUICKLY. ALREADY UPDATED FOR LOWER POPS ACROSS MOST OF THE AREA...AND WHAT WE LEFT MAY STILL BE TOO MUCH FOR THE NORTHWEST HALF OF OUR AREA. SOUTH WINDS MAKE FOG FORMATION UNLIKELY...THOUGH IF THERE IS A LOT MORE CLEARING THAN WE EXPECTED THERE COULD BE SOME STRATUS AWAY FROM THE PALMER DIVIDE DOWNSLOPE. && .AVIATION...VFR CONDITIONS THROUGH THURSDAY. SOUTH WINDS BECOMING NORTH AT KDEN/KAPA THURSDAY MORNING. SCATTERED AFTERNOON THUNDERSTORMS EXPECTED WITH FAIRLY HIGH CEILINGS BUT A CHANCE OF GUSTY WINDS TO 30 KNOTS. && .HYDROLOGY...STRONG CONVECTION HAS SHIFTED EAST. FOR MOST OF THE AREA ONLY LIGHT SHOWERS EXPECTED IF ANYTHING. OVER LINCOLN COUNTY STILL A CHANCE OF STORMS BUT THEY SHOULD BE LESS INTENSE AND PRODUCE UNDER AN INCH OF RAIN...PROBABLY MUCH LESS. && .PREV DISCUSSION... /ISSUED 351 PM MDT WED AUG 7 2013/ SHORT TERM...A COMPLEX PICTURE TODAY WITH SEVERAL UPPER LEVEL SHORTWAVES EMBEDDED WITHIN AN OVERALL WEAK TROUGH CENTERED BACK TOWARDS THE FOUR CORNERS REGION. SATELLITE WATER VAPOR LOOP CAPTURES THINGS BEST. ONE FEATURE WENT BY THIS MORNING INTO EARLY AFTERNOON WITH SOME THUNDERSTORM ACTIVITY EAST OF DENVER THAT HAS SINCE MOVED OFF AND WEAKENED. THE PLATTEVILLE PROFILER SHOWS THIS I BELIEVE CENTERED AROUND 600 MB. WIDESPREAD CLOUDINESS BUT NOT MUCH RAIN FOR MOST OF THE REST OF THE FORECAST AREA WHICH HAS KEPT TEMPERATURES ON THE COOL SIDE AND THUNDER LIMITED SO FAR. MORE SUN AND WARMER CONDITIONS HAVE BEEN PRESENT SOUTH OF THE PALMER DIVIDE AND A SECOND WAVE SEEN IN THE WATER VAPOR IMAGERY AND CAPTURED BY THE RAP ANALYSES IS MOVING INTO THIS AREA WITH THUNDERSTORMS RAPIDLY DEVELOPING. THESE SHOULD MOVE INTO THE PALMER DIVIDE REGION OVER THE NEXT SEVERAL HOURS SO WILL CONTINUE THE FLASH FLOOD WATCH. ALTHOUGH SURFACE WARMING HAS BEEN LIMITED ACROSS THE PALMER DIVIDE COMPARED TO SOUTHEAST COLORADO DEW POINTS ARE QUITE HIGH WITH 61 NOW AT LIMON. ANOTHER WAVE IS FOUND FARTHER SOUTH MOVING NORTH INTO SOUTHWEST COLORADO AND THIS FEATURE IF IT HOLDS TOGETHER COULD HELP SUPPORT MORE ACTIVITY LATER TONIGHT AGAIN TO THE EAST OF DENVER. SEE THIS SECOND WAVE IN THE LATEST HRRR FORECAST RUN FROM 19Z BUT HRRR KEEPS IT RATHER FAR TO THE SOUTH AS IT APPROACHES NEAR 06Z. MAYBE TOO FAR SOUTH AS IT ALSO SEEMS TO BE WITH THE CURRENT WAVE OF STORMS MOVING EAST OF PUB AND COS. MEANWHILE AN UPPER LEVEL CIRCULATION REMAINS BEHIND NEAR THE FOUR CORNERS AND WHAT IS LEFT OF THIS COULD BE A FACTOR TOMORROW OR SHIFT MORE TO THE EAST. THE MAIN PRECIPITATION LOOKS LIKE IT WILL CONTINUE TO STAY EAST AND SOUTH OF DENVER. THERE IS ANOTHER AREA OF MORE SCATTERED THUNDERSTORMS OVER THE FOOTHILLS OVER LARIMER COUNTY AND SOME OF THESE COULD MOVE ONTO THE ADJACENT FRONT RANGE. MEANWHILE THERE CONTINUES TO BE A WIDE RANGE OF MODEL SOLUTIONS EVEN FOR THE PRECIPITATION IN THE NEXT 6 TO 12 HOURS. THE 12Z GFS HAD THE MOST ORGANIZED WIDESPREAD HEAVY RAIN AREA AS IT ORGANIZED ONE OF THE ABOVE NOTED FEATURES INTO A COMPACT CIRCULATION AT 700 MB. OTHER MODELS KEEP MOST OF THE PRECIP MUCH FARTHER TO THE SOUTH. LATEST HRRR HAS A WAVE OF PRECIP NEXT FEW HOURS THEN STAYS FARTHER SOUTH. SOMETHING IN BETWEEN THE EXTREMES LOOKS MOST LIKELY AND KEPT HIGHEST POPS OVER THE PALMER DIVIDE AND FAR EASTERN ZONES LINGERING INTO THURSDAY MORNING. LONG TERM...BACK EDGE OF MID LEVEL TROUGH TO BE EXITING EASTERN COLORADO DURING THE EVENING WITH WEAK SUBSIDENCE SPREADING ACROSS THE AREA. FLOW ALOFT APPEARS A BIT SPLIT WITH WESTERLY FLOW ACROSS SOUTHERN COLORADO AND NORTHWEST FLOW ALOFT OVER NORTHERN COLORADO...WITH THE MAIN BATCH OF SUBTROPICAL MOISTURE TO THE WEST AND SOUTH OF THE CFWA. STILL ENOUGH MOISTURE AND WEAK INSTABILITY DURING THE EVENING FOR SOME THUNDERSTORMS WHILE AIRMASS A BIT MORE STABLE OVER PLAINS. SHOULD SEE STORMS END ACROSS PLAINS AROUND MIDNIGHT AS AIRMASS CONTINUES TO STABILIZE WITH PERHAPS A FEW STORMS LINGERING OVERNIGHT ACROSS THE HIGH COUNTRY. ON FRIDAY...FLOW ALOFT BECOMES MORE WESTERLY BY THE AFTERNOON AS MODEL CONSENSUS SHOWS A WEAK UPPER TROUGH MOVES ACROSS NORTHERN WYOMING. HOWEVER...700 MB LOW IS STILL MORE SOUTHWEST...WHICH SHOULD ALLOW SOME INCREASE IN SUBTROPICAL MOISTURE OVER THE AREA. SURFACE HIGH TO PUSH ACROSS INTO CENTRAL PLAINS WITH LOW LEVEL FLOW BECOMING SOUTHEAST BY THE AFTERNOON. THIS WILL ALLOW SOME INCREASE IN LOW LEVEL MOISTURE ALONG WITH SLIGHTLY COOLER TEMPERATURES. FORECAST SOUNDINGS SHOW A BIT OF A CAP ACROSS THE PLAINS. SO BEST CHANCE FOR THUNDERSTORMS TO OCCUR ACROSS THE MOUNTAINS AND FOOTHILLS DURING THE AFTERNOON AND EVENING WITH MOST STORMS ENDING AROUND MIDNIGHT. ON SATURDAY...SOUTHWEST FLOW ALOFT TO PREVAIL WITH SOME INCREASE IN SUBTROPICAL MOISTURE...WHICH SHOULD LEAD TO A CHANCE OF THUNDERSTORMS OVER THE HIGH COUNTRY. ACROSS PLAINS...AIRMASS STILL FAIRLY CAPPED AS NOTED BY FORECAST SOUNDINGS WHICH SHOULD LIMIT THUNDERSTORM DEVELOPMENT. SOUTHEAST SURFACE WINDS OVER EASTERN COLORADO TO PREVAIL BY THE THE AFTERNOON WITH SOME HINTS OF A DENVER CYCLONE WHICH MAY INCREASE STORM CHANCES EAST AND SOUTH OF DENVER. TEMPERATURES TO WARM IN THE LOWER 80S ACROSS THE PLAINS. FOR SUNDAY...SOUTHWEST FLOW ALOFT TO CONTINUE WITH WEAK UPPER TROUGH MOVING ACROSS CENTRAL PLAINS. MODELS SHOW WEAK FRONT MOVING ACROSS THE PLAINS BY THE AFTERNOON WITH SOME INCREASE IN LOW LEVEL MOISTURE. HOWEVER THE BEST INSTABILITY LOOKS TO BE EAST OF COLORADO. BEST CHANCE FOR THUNDERSTORMS TO BE ACROSS MOUNTAINS WITH A SLIGHT CHANCE OVER THE PLAINS. HIGHS ACROSS PLAINS LOOK TO BE IN THE LOWER 80S. FOR THE LATER DAYS...MONDAY THROUGH WEDNESDAY: MODELS SHOW UPPER LEVEL RIDGE BUILDING ACROSS COLORADO WITH A GRADUAL DECREASE IN SUBTROPICAL MOISTURE. THIS TO LEAD TO A DECREASING CHANCE OF THUNDERSTORMS AND SLIGHTLY WARMER TEMPERATURES. AVIATION...WEAK WIND SHIFT WENT BY DIA EARLIER BUT OTHERWISE A GENERAL SOUTHEAST FLOW EXPECTED UNTIL LATER IN THE EVENING. MOST IF NOT ALL THUNDERSTORMS SHOULD REMAIN SOUTH AND EAST OF THE AIRPORT AS IT LOOKS NOW. HYDROLOGY...GIVEN THE DEVELOPMENT TO OUR SOUTH AS NOTED ABOVE WITH PUB GETTING ALMOST AN INCH OF RAIN IN A SHORT TIME THE THREAT OF FLASH FLOODING STILL IN PLACE SO CONTINUE THE WATCH FOR THE PALMER DIVIDE REGION. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SZOKE LONG TERM....D-L AVIATION/UPDATE...GIMMESTAD/BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1119 PM MDT MON AUG 5 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ACTIVE DAY FOR THE WESTERN SLOPES TODAY AS THUNDERSTORMS FIRED UP EARLIER THAN PAST COUPLE DAYS WITHIN THE MONSOON PLUME. THIS IS OUT AHEAD OF LEADING DISTURBANCE MOVING THROUGH SOUTHERN AZ. MEANWHILE...ANOTHER DISTURBANCE IS EXITING EASTERN CO TO THE EAST. DEW POINTS HAVE BEEN FALLING OFF ACROSS THE SE MTS/I-25 CORRIDOR AS PROGGED BY MODELS WITH 40 DEW POINTS AND EVEN SOME UPPER 30S. EVEN OUT TOWARDS LA JUNTA AND LAMAR...DEW POINTS HAVE BEEN FALLING INTO THE LOWER 50S AS WINDS HAVE SHIFTED OUT OF THE SOUTH AND EVEN SOUTHWEST AS THE SFC LOW HAS BEEN KICKING EASTWARD. FOR THE REMAINDER OF THIS EVENING...SCATTERED THUNDERSTORMS EXPECTED ACROSS THE MOUNTAINS...WITH HRRR SUGGESTING THUNDERSTORMS WILL SPREAD INTO THE ADJACENT PLAINS DURING THE LATE AFTERNOON/EARLY EVENING. NOT AS MUCH CAPE TODAY...SO NOT EXPECTING ANY STRONG STORMS ALONG THE I-25 CORRIDOR. WRF WAS HITTING WALDO BURN SCAR BETWEEN 3-5 PM...WHILE EACH SUCCESSIVE RUN OF THE HRRR HAS BEN DELAYING THIS POTENTIAL UNTIL A NORTHERLY SURGE AIDED BY CONVECTION ACROSS NE CO DROPS INTO THE PIKES PEAK REGION JUST AS WEAK FORCING ENHANCING WRN CO CONVECTION WORKS ITS WAY EASTWARD ACROSS THE SE MTS. THIS PUTS TIME FRAME FOR WALDO TO GET HIT BETWEEN 6PM-8PM WHICH MAY BE A LITTLE DELAYED FROM BEST SFC BASED HEATING TO REALIZE STRONG CONVECTION AND HIGH RAINFALL RATES. BUT THIS WILL HAVE TO BE MONITORED CLOSELY. OTHER AREA OF CONCERN BESIDES WILL BE OUT WEST ACROSS THE PAPOOSE AND WEST FORK BURN SCARS WHERE THEY WILL BE UNDER THE GUN FROM STORMS AND HEAVY RAINFALL/POTENTIAL FLASH FLOODING UNTIL 8 PM. MEANWHILE...FAR SOUTHEAST PLAINS WILL HAVE TO BE WATCHED CLOSELY AS CONVECTION ACROSS NW KS SENDS A BOUNDARY SOUTHWESTWARD INTO SE CO...INCREASING SFC DEW POINTS. COULD SEE SOME THUNDERSTORMS DEVELOP ALONG THE LEADING EDGE OF THIS OUTFLOW ACROSS KIOWA...PROWERS AND BACA COUNTIES WITH POTENTIAL FOR A STRONG STORM OR TWO. MAIN THREAT WINDOW WILL BE DURING THE EVENING...WITH POTENTIAL FOR NEAR SEVERE HAIL AND WIND. BEST SEVERE THREAT THOUGH APPEARS TO BE JUST NORTH AND EAST OF THE AREA. TONIGHT...LOTS OF MID/HIGH CLOUDINESS WILL KEEP TEMPERATURES ON THE WARM SIDE...WITH POPS DIMINISHING FOR MOST AREAS BY MIDNIGHT. CAN`T RULE OUT SOME ISOLATED SHOWERS AND THUNDERSTORMS OUT WEST WITHIN THE MONSOON PLUME. ON TUESDAY...PERHAPS A BIT MORE ACTIVE OUT WEST AS SHORTWAVES EMBEDDED IN MONSOON PLUME WORK THEIR WAY NORTHWARD THROUGH AZ INTO SRN UT/FOUR CORNERS REGION TOWARDS 00Z. CONTEMPLATED GOING WITH A FLASH FLOOD WATCH FOR THE WEST FORK AND PAPOOSE BURN SCARS TOMORROW...BUT SFC DEW POINTS DON`T APPEAR TO MOISTEN ALL THAT MUCH...AND MODEL QPFS OFF THE LARGER SCALE MODELS ARE NOT ALL THAT MUCH HIGHER. STILL THERE IS SOME INCREASE IN PRECIP WATERS OUT THAT WAY...SO WILL HAVE TO MONITOR THIS POTENTIAL. WILL LET LATER SHIFTS GET A LOOK AT THE HIGH RES SHORT RANGE MODELS AS THEY START TO RESOLVE THAT PERIOD. OTHERWISE...FOR THE EASTERN AREAS LOOKS LIKE MORE OF THE SAME. ANOTHER DAY OF LOWER SFC DEW POINTS ACROSS THE PLAINS WHICH KEEPS LCLS ON THE HIGH SIDE. STILL ENOUGH MOISTURE IN THE MONSOON PLUME FOR SOME LOCALLY HEAVY RAIN WITH THE STRONGER STORMS...BUT FOR NOW THIS THREAT LOOKS TOO LOCALIZED TO WARRANT ANY FLASH FLOOD WATCHES FOR THE WALDO OR BLACK FOREST. THIS COULD CHANGE INTO THE EVENING HOURS AS MODELS DROP A FRONT REINFORCED BY THUNDERSTORM OUTFLOWS INTO THE AREA FROM NE CO. -KT .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 244 PM MDT MON AUG 5 2013 ...HEAVY RAIN EXPECTED ON WEDNESDAY... HIGH PRESSURE OVER TEXAS AND AN AREA OF LOW PRESSURE OFF THE NORTHERN CALIFORNIA COAST WILL FORCE SOUTHERLY MONSOON ENERGY ACROSS COLORADO THROUGH THURSDAY. THIS WILL SET THE STAGE FOR WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TUESDAY NIGHT THROUGH THURSDAY AFTERNOON. EXPECT ACTIVE SHOWER AND THUNDERSTORM ACTIVITY TUESDAY EVENING OVER THE MOUNTAINS AND SPREADING INTO THE PLAINS. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE DURING THIS TIME PERIOD. MODELS INDICATING A SMALL LULL AROUND MIDNIGHT BEFORE ACTIVITY INCREASES AGAIN HEADING INTO WEDNESDAY MORNING. HOW QUICKLY THINGS PICK LATE TUESDAY NIGHT/WEDNESDAY MORNING WILL DEPEND ON HOW FAST A FRONT MOVES SOUTH ACROSS THE AREA...AND A STRONG SHORTWAVE EJECTS NORTHEAST OUT OF THE DESERT SOUTHWEST. FRONTAL TIMING LOOKS TO IMPACT THE AREA BY WEDNESDAY MORNING WITH A VERY MOIST AIR MASS MOVING INTO THE PLAINS BEHIND THE FRONT. IN ADDITION...LOW LEVEL FLOW IS FORECAST TO TURN EASTERLY WITH GOOD UPSLOPE FLOW ACROSS THE PLAINS. ALL OF THESE LOW LEVEL FEATURES WILL COMBINE WITH A VERY STRONG SHORTWAVE TROUGH ACROSS COLORADO TO PRODUCE WIDESPREAD MODERATE TO HEAVY RAINFALL ACROSS THE AREA. IN ADDITION...COLDER AIR ALOFT WILL MOVE INTO THE AREA WHICH WILL LIKELY INCREASE LAPSE RATES AND INSTABILITY ACROSS COLORADO. THE AREA OF GREATEST CONCERN WILL BE THE EASTERN MOUNTAINS AND I-25 CORRIDOR. MODELS ARE INDICATING WELL OVER AN INCH OF PRECIPITATION WILL BE POSSIBLE...ESPECIALLY IF WE CAN GET ENHANCEMENT FROM CONVECTIVE UPDRAFTS. THE ONE CAVEAT MAY BE CLOUD COVER ACROSS THE PLAINS WHICH WOULD LIMIT INSTABILITY AND CONVECTIVE ENHANCEMENT. THIS WILL NEED TO BE WATCHED. FLASH FLOODING WILL BE OF GREAT CONCERN...ESPECIALLY FOR AREA BURN SCARS. EXTREME CAUTION IS ADVISED AND FOLKS SHOULD REMAIN COGNIZANT OF THE WEATHER AROUND THEM. THE UPPER SYSTEM WILL BE SLOW TO MOVE OUT...WITH THE MODERATE TO HEAVY RAINFALL SLOWLY MOVING EAST ACROSS THE PLAINS WEDNESDAY NIGHT. THURSDAY...MOISTURE WILL BE IN PLACE AND DEPARTING UPPER LEVEL ENERGY WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE MOUNTAINS THURSDAY AFTERNOON. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE...AND FLASH FLOODING WILL BE POSSIBLE OVER AREA BURN SCARS. IF TRENDS HAVE ANYTHING TO SAY ABOUT IT...THE DAY AFTER EXPECTED WIDESPREAD HEAVY RAINFALL EVENTS SEEM TO BE PRIMED FOR HEAVIER RAINFALL OUT OF THUNDERSTORMS THAN MODELS SEEM TO INDICATE. THE PATTERN BEGINS TO SHIFT FRIDAY INTO EARLY NEXT WEEK. THE LOW OFF NORTHERN CALIFORNIA WILL DRIFT NORTHWARD HAS HIGH PRESSURE OVER TEXAS BUILDS NORTH ACROSS COLORADO. THE MAIN MONSOONAL TAP SHIFTS WESTWARD INTO THE GREAT BASIN. MODELS ARE INDICATING A DOWNWARD TREND IN CONVECTIVE ACTIVITY THROUGH THE WEEKEND WITH SHOWER AND THUNDERSTORM ACTIVITY REMAINING CONFINED TO MOUNTAIN AREAS. MOZLEY && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1117 PM MDT MON AUG 5 2013 VFR CONDITIONS ARE EXPECTED OVER THE KALS...KCOS AND KPUB TAF SITES FROM TONIGHT INTO TUESDAY AFTERNOON. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
928 PM EDT WED AUG 7 2013 .SYNOPSIS... A WEAK WARM FRONT WILL APPROACH AND LIFT NORTHWARD THROUGH THE REGION TONIGHT THROUGH THURSDAY. LOW PRESSURE MOVING ACROSS SOUTHEASTERN CANADA WILL ALLOW A COLD FRONT TO SLOWLY APPROACH OUR REGION FROM THE WEST FOR THE END OF THE WORK WEEK. THE FRONT IS EXPECTED TO CROSS OUR AREA DURING SATURDAY AND EVENTUALLY STALL TO OUR SOUTH FOR SUNDAY. EARLY NEXT WEEK, A FEW WAVES OF LOW PRESSURE ARE FORECAST TO MOVE ALONG THE STALLED BOUNDARY, FOLLOWED BY HIGH PRESSURE BUILDING TOWARD THE REGION FOR MID-WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... NOT MUCH CHANGE WITH THE 930PM UPDATE AS THE TEMPERATURES AND DEWPOINTS ARE ON TRACK AS ARE THE POPS. DID EDGE THE LIKELY POPS FURTHER SOUTH THAN PREVIOUSLY FORECASTED AS SOME OF THE HEAVIER RAIN HAS SPREAD INTO CENTRAL MARYLAND. OTHERWISE EVERYTHING ELSE APPEARS TO BE ON TRACK. THE TREND IS FOR SOME WEAKENING OF THE STORMS TO OUR WEST SO NOT EXPECTING ANYTHING SEVERE TO OCCUR. THE LATEST RUC SEEMS TO HAVE A DECENT HANDLE ON THE PLACEMENT AND MOVEMENT OF THE SHORTWAVE AND ITS SHOWERS CARRYING THEM INTO OUR WEST AND NORTH ZONES AFTER 3Z. DISCRETE CELLS ARE ALSO FIRING AHEAD OF THE LINE OF STORMS TO THE WEST OF SELINSGROVE DOWN TO ALTOONA, WHERE THE BEST ML- MUCAPES REMAINS. THESE ARE TAKING MORE OF A SOUTHWEST TO NORTHEAST MOVEMENT AND MAY CLIP OUR WESTERN ZONES OVER THE NEXT HOUR OR TWO. THOUGH WE ARE STARTING TO SEE SOME THINNING OF THE CLOUDS FROM THE SOUTHWEST, WHERE BETTER MIXING HAS OCCURRED FOR MOST OF THE DAY, THERE IS STILL PLENTY THAT WILL TRY TO PUSH IN FROM THE WEST- NORTHWEST WITH THE SHORTWAVE. WE KEEP THE OVERCAST CONDITIONS ACROSS A BETTER PART OF THE REGION TONIGHT AND CEILINGS SHOULD BEGIN TO LOWER A BIT MORE TOO. AS FOR OVERNIGHT LOWS WE CAN ONLY BE WRONG SO MUCH AS DEW POINTS HAVE RISEN AND WE CAN ONLY GO SO LOW. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... THE FOCUS ON THURSDAY FOR SHOWERS AND THUNDERSTORMS WITH HEAVIER RAIN SHIFTS TO THE NORTHWEST OF OUR CWA. AS ONE OF OUR COLLEGE VOLUNTEERS SHOWED IN THE BRIEFING THE GREATEST INSTABILITY IS FORECAST TO BE THERE CLOSER TO THE DEPARTING WARM FRONT AS WELL AS MORE ENTRENCHED IN THE 925MB/850MB DEEPER MOISTURE POOL COMING FROM THE OHIO VALLEY AND SLIGHTLY COLDER AIR AT THE MID LEVELS. ITS ALSO THE LOCATION CLOSEST TO THE FCST MID LEVEL QVEC CONVERGENCE (BETTER NORTH OF OUR AREA) THE FORECAST BULK SHEAR IS NOT AS VIGOROUS AS IT IS TODAY AND MID LEVEL LAPSE RATES ARE MODERATE AT BEST. SO THERE COULD BE SOME CLOSE TO SEVERE STORMS NORTHWEST DEPENDING UPON TIMING. FCST DCAPES AND DROP OF THETA E WITH HEIGHT DONT SUPPORT PULSE TYPE SEVERE, SO SOME ORGANIZATION POOLING WILL BE NEEDED FOR THE STORMS TO BECOME STRONGER. WITH PWATS CONTINUING TO RISE THE THREAT FOR HEAVY RAIN ALSO CONTINUES AND IN FACT INTENSIFIES. WE SHOULD BE STARTING CLOUDY DURING THE MORNING, BUT WE ARE EXPECTING ENOUGH SUNSHINE TO DEVELOP TO GET TO STAT GUIDANCE HIGHS (AS WELL AS TRIGGER CONVECTION). LOWEST CONFIDENCE ABOUT OUR MAX TEMPS IS NORTH BECAUSE OF THE WARM FRONTAL POSITION. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... UNSETTLED WEATHER IS EXPECTED THROUGH MUCH OF THE LONG TERM PERIOD, AS A SLOW-MOVING COLD FRONT APPROACHES FROM THE WEST AND EVENTUALLY STALLS TO OUR SOUTH. ALOFT, A MAINLY ZONAL FLOW WILL BE IN PLACE, WITH SOME SLIGHT TROUGHING LATE THIS WEEKEND INTO EARLY NEXT WEEK. BOTH THE GFS AND ECMWF SHOW MULTIPLE SHORTWAVES AND VORT MAXES MOVING THROUGH THIS MAINLY ZONAL FLOW ACROSS OUR REGION THROUGH EARLY NEXT WEEK. MEANWHILE, THE SURFACE COLD FRONT WILL GRADUALLY APPROACH OUR AREA FROM THE WEST DURING FRIDAY, EVENTUALLY PROGRESSING SOUTH AND EAST OF THE REGION BY THE END OF THE WEEKEND. THIS PATTERN AT THE SURFACE AND ALOFT WILL KEEP SCATTERED SHWRS/TSTORMS IN THE PICTURE, ESPECIALLY FOR OUR SOUTHERN ZONES. WITH THE STALLED FRONTAL BOUNDARY REMAINING TO OUR SOUTH INTO THE MONDAY AND TUESDAY TIMEFRAME, ISOLATED CONVECTION MAY STILL BE A POSSIBILITY FOR OUR DELMARVA ZONES AS MODEL GUIDANCE SHOWS A FEW WAVES OF LOW PRESSURE MOVING ALONG THE BOUNDARY. BOTH THE ECMWF AND GFS SHOW HIGH PRESSURE TRYING TO BUILD INTO THE REGION BY MID-WEEK AND EVENTUALLY PUSHING THE STALLED FRONTAL BOUNDARY FARTHER SOUTH, BUT CONFIDENCE IS ONLY AVERAGE REGARDING THE TIMING AND PROGRESSION OF THESE FEATURES AT THIS EXTENDED TIME RANGE. AHEAD OF THE APPROACHING COLD FRONT ON FRIDAY, PWATS ARE EXPECTED TO CLIMB INTO THE 1.5 TO 2 INCH RANGE ACROSS THE REGION, AND THIS AVAILABLE MOISTURE WILL PERSIST INTO THE WEEKEND. THIS COMBINED WITH ONLY A MODEST FLOW ALOFT WILL KEEP THE POTENTIAL FOR HEAVY RAIN IN THE PICTURE WITH FLOODING OF POOR DRAINAGE AND LOW LYING AREAS BEING A CONTINUED CONCERN. BY THE MIDDLE OF NEXT WEEK, WITH AN AREA OF HIGH PRESSURE PROGGED TO EDGE INTO OUR REGION FROM THE NORTHWEST, THE STALLED FRONTAL BOUNDARY WILL GRADUALLY BE PUSHED FARTHER SOUTH, ALLOWING FOR SOME DRIER AIR TO ADVANCE INTO THE REGION. OVERALL, NEAR TO SLIGHTLY ABOVE AVERAGE DAYTIME TEMPERATURES ARE EXPECTED FOR THE REGION THROUGH THE WEEKEND, WITH HIGHS REACHING FROM THE UPPER 70S ACROSS THE SOUTHERN POCONOS TO THE UPPER 80S FOR OUR SOUTHERN ZONES. BY THE MIDDLE OF NEXT WEEK, DAYTIME TEMPERATURES SHOULD RETURN CLOSER TO OR EVEN A BIT BELOW AVERAGE AS HIGH PRESSURE BUILDS DOWN FROM THE NORTHWEST, WITH HIGHS RANGING FROM THE LOW TO MID 70S NORTH TO THE LOWER 80S SOUTH. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS IS NOT A CONFIDENT FORECAST THROUGH THE NEXT 12 HOURS GIVEN POCKETS OF DRY AIR ALOFT TRYING TO SQUEEZE INTO THE REGION FROM THE SOUTHWEST MAKING THE CIGS JUMP AROUND A BIT. FOR TONIGHT, WE SHOULD REMAIN PRIMARILY MVFR OUTSIDE OF MIV/ACY, WITH AREAS OF SHOWERS AND POSSIBLE A COUPLE RUMBLES OF THUNDER MOVING THROUGH FOR THE NEXT COUPLE OF HOURS. TEMPO GROUPS HAVE BEEN PLACED IN THE TAFS FOR SUCH OCCURRENCES. TERMINALS THAT RECEIVE A BIT MORE RAIN TONIGHT HAVE A BETTER CHANCE AT SEEING IFR CIGS DEVELOP BY MID-MORNING, OR AT LEAST LOW-MVFR. AGAIN NOT TOO CONFIDENT ON HOW WIDESPREAD THE IFR CIGS WILL BE. ON THURSDAY WE ARE EXPECTING CONDITIONS TO IMPROVE TO VFR, WITH GREATER CONFIDENCE AS THE MORNING PROGRESSES AND LIKELY FASTER IMPROVEMENT SOUTHERN TERMINALS, AIRPORTS VS THE NORTHERN ONES. THERE WILL BE A GREATER CHANCE FOR THUNDERSTORMS VS TODAY, WHICH SHOULD BE MAINLY AFTER 18Z. PROB30S HAVE BEEN PLACED AT A MAJORITY OF OUR TAFS TO ACCOUNT FOR THE AFTERNOON STORMS THOUGH TIMING STILL NEEDS TO BE TWEAKED. OUTLOOK... THURSDAY NIGHT THROUGH EARLY MORNING SATURDAY...MAINLY MVFR CONDITIONS EXPECTED. POTENTIAL FOR LOWER CONDITIONS AT TIMES IN HEAVIER SHOWERS AND TSTORMS. REMAINDER OF SATURDAY THROUGH MONDAY...MOSTLY VFR CONDITIONS. ISOLATED SHWRS/TSTORMS REMAIN POSSIBLE. && .MARINE... SUB SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED THROUGH THURSDAY. THE STRONGEST WINDS HAVE BEEN NEAR THE IMMEDIATE COAST. WAVE WATCH MODEL IS ABOUT TO START RUNNING ABOUT A FOOT TOO HIGH. IN GENERAL A SOUTHERLY FLOW OF AIR IS EXPECTED TO PREVAIL THROUGH THURSDAY AS OUR FORECAST AREA GETS DEEPER INTO THE WARM SECTOR ON THE OTHER SIDE OF THE WARM FRONT. THUS GUIDANCE WINDS SHOULD BE A BIT ON THE HIGH SIDE AND WE CAPPED SEAS ABOUT A FOOT BELOW WAVE WATCH GUIDANCE. OUTLOOK... OVERALL, SUB-SCA CONDITIONS ARE EXPECTED FOR OUR AREA WATERS THROUGH THE BULK OF THE OUTLOOK PERIOD. GUIDANCE IS SHOWING AN INCREASE IN THE SOUTHERLY TO SOUTHWESTERLY FLOW DURING FRIDAY AHEAD OF AN APPROACHING COLD FRONT. SOME WIND GUSTS AROUND 20 KNOTS ARE EXPECTED FRIDAY INTO FRIDAY NIGHT. IN ADDITION, WAVEWATCH GUIDANCE ALSO INDICATES SEAS RISING TO AROUND 5 FEET FOR OUR COASTAL WATERS DURING THIS TIMEFRAME. HOWEVER, THIS GUIDANCE TENDS TO RUN A LITTLE HIGH IN SOUTHERLY FLOW, AND CONFIDENCE IS BELOW AVERAGE AT THIS TIME FOR SEAS REACHING 5 FEET BEFORE THE FRONTAL BOUNDARY MOVES THROUGH AND WINDS BECOME MORE WEST AND THEN NORTHWEST OVER THE WEEKEND. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...KLINE NEAR TERM...GIGI/HEAVENER SHORT TERM...GIGI LONG TERM...KLINE AVIATION...GIGI/HEAVENER/KLINE MARINE...GIGI/KLINE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
816 PM EDT WED AUG 7 2013 .SYNOPSIS... A WEAK WARM FRONT WILL APPROACH AND LIFT NORTHWARD THROUGH THE REGION TONIGHT THROUGH THURSDAY. LOW PRESSURE MOVING ACROSS SOUTHEASTERN CANADA WILL ALLOW A COLD FRONT TO SLOWLY APPROACH OUR REGION FROM THE WEST FOR THE END OF THE WORK WEEK. THE FRONT IS EXPECTED TO CROSS OUR AREA DURING SATURDAY AND EVENTUALLY STALL TO OUR SOUTH FOR SUNDAY. EARLY NEXT WEEK, A FEW WAVES OF LOW PRESSURE ARE FORECAST TO MOVE ALONG THE STALLED BOUNDARY, FOLLOWED BY HIGH PRESSURE BUILDING TOWARD THE REGION FOR MID-WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... WE MAINTAIN THE CURRENT POPS ACROSS OUR NORTHERN ZONES AS THE STRONGEST OF MID-LEVEL SHORTWAVES CONTINUES TO SPARK HEAVY SHOWERS AND THUNDERSTORMS ACROSS CENTRAL PENNSYLVANIA. THE TREND IS FOR SOME WEAKENING, SO NOT EXPECTING ANYTHING SEVERE TO OCCUR. THE LATEST RUC SEEMS TO HAVE A DECENT HANDLE ON THE PLACEMENT AND MOVEMENT OF THE SHORTWAVE AND ITS SHOWERS CARRYING THEM INTO OUR WEST AND NORTH ZONES AFTER 3Z. DISCRETE CELLS ARE ALSO FIRING AHEAD OF THE LINE OF STORMS TO THE WEST OF SELINSGROVE DOWN TO ALTOONA, WHERE THE BEST ML- MUCAPES REMAINS. THESE ARE TAKING MORE OF A SOUTHWEST TO NORTHEAST MOVEMENT AND MAY CLIP OUR WESTERN ZONES OVER THE NEXT HOUR OR TWO. THOUGH WE ARE STARTING TO SEE SOME THINNING OF THE CLOUDS FROM THE SOUTHWEST, WHERE BETTER MIXING HAS OCCURED FOR MOST OF THE DAY, THERE IS STILL PLENTY THAT WILL TRY TO PUSH IN FROM THE WEST- NORTHWEST WITH THE SHORTWAVE. WE KEEP THE OVERCAST CONDITIONS ACROSS A BETTER PART OF THE REGION TONIGHT AND CEILINGS SHOULD BEGIN TO LOWER A BIT MORE TOO. AS FOR OVERNIGHT LOWS WE CAN ONLY BE WRONG SO MUCH AS DEW POINTS HAVE RISEN AND WE CAN ONLY GO SO LOW. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... THE FOCUS ON THURSDAY FOR SHOWERS AND THUNDERSTORMS WITH HEAVIER RAIN SHIFTS TO THE NORTHWEST OF OUR CWA. AS ONE OF OUR COLLEGE VOLUNTEERS SHOWED IN THE BRIEFING THE GREATEST INSTABILITY IS FORECAST TO BE THERE CLOSER TO THE DEPARTING WARM FRONT AS WELL AS MORE ENTRENCHED IN THE 925MB/850MB DEEPER MOISTURE POOL COMING FROM THE OHIO VALLEY AND SLIGHTLY COLDER AIR AT THE MID LEVELS. ITS ALSO THE LOCATION CLOSEST TO THE FCST MID LEVEL QVEC CONVERGENCE (BETTER NORTH OF OUR AREA) THE FORECAST BULK SHEAR IS NOT AS VIGOROUS AS IT IS TODAY AND MID LEVEL LAPSE RATES ARE MODERATE AT BEST. SO THERE COULD BE SOME CLOSE TO SEVERE STORMS NORTHWEST DEPENDING UPON TIMING. FCST DCAPES AND DROP OF THETA E WITH HEIGHT DONT SUPPORT PULSE TYPE SEVERE, SO SOME ORGANIZATION POOLING WILL BE NEEDED FOR THE STORMS TO BECOME STRONGER. WITH PWATS CONTINUING TO RISE THE THREAT FOR HEAVY RAIN ALSO CONTINUES AND IN FACT INTENSIFIES. WE SHOULD BE STARTING CLOUDY DURING THE MORNING, BUT WE ARE EXPECTING ENOUGH SUNSHINE TO DEVELOP TO GET TO STAT GUIDANCE HIGHS (AS WELL AS TRIGGER CONVECTION). LOWEST CONFIDENCE ABOUT OUR MAX TEMPS IS NORTH BECAUSE OF THE WARM FRONTAL POSITION. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... UNSETTLED WEATHER IS EXPECTED THROUGH MUCH OF THE LONG TERM PERIOD, AS A SLOW-MOVING COLD FRONT APPROACHES FROM THE WEST AND EVENTUALLY STALLS TO OUR SOUTH. ALOFT, A MAINLY ZONAL FLOW WILL BE IN PLACE, WITH SOME SLIGHT TROUGHING LATE THIS WEEKEND INTO EARLY NEXT WEEK. BOTH THE GFS AND ECMWF SHOW MULTIPLE SHORTWAVES AND VORT MAXES MOVING THROUGH THIS MAINLY ZONAL FLOW ACROSS OUR REGION THROUGH EARLY NEXT WEEK. MEANWHILE, THE SURFACE COLD FRONT WILL GRADUALLY APPROACH OUR AREA FROM THE WEST DURING FRIDAY, EVENTUALLY PROGRESSING SOUTH AND EAST OF THE REGION BY THE END OF THE WEEKEND. THIS PATTERN AT THE SURFACE AND ALOFT WILL KEEP SCATTERED SHWRS/TSTORMS IN THE PICTURE, ESPECIALLY FOR OUR SOUTHERN ZONES. WITH THE STALLED FRONTAL BOUNDARY REMAINING TO OUR SOUTH INTO THE MONDAY AND TUESDAY TIMEFRAME, ISOLATED CONVECTION MAY STILL BE A POSSIBILITY FOR OUR DELMARVA ZONES AS MODEL GUIDANCE SHOWS A FEW WAVES OF LOW PRESSURE MOVING ALONG THE BOUNDARY. BOTH THE ECMWF AND GFS SHOW HIGH PRESSURE TRYING TO BUILD INTO THE REGION BY MID-WEEK AND EVENTUALLY PUSHING THE STALLED FRONTAL BOUNDARY FARTHER SOUTH, BUT CONFIDENCE IS ONLY AVERAGE REGARDING THE TIMING AND PROGRESSION OF THESE FEATURES AT THIS EXTENDED TIME RANGE. AHEAD OF THE APPROACHING COLD FRONT ON FRIDAY, PWATS ARE EXPECTED TO CLIMB INTO THE 1.5 TO 2 INCH RANGE ACROSS THE REGION, AND THIS AVAILABLE MOISTURE WILL PERSIST INTO THE WEEKEND. THIS COMBINED WITH ONLY A MODEST FLOW ALOFT WILL KEEP THE POTENTIAL FOR HEAVY RAIN IN THE PICTURE WITH FLOODING OF POOR DRAINAGE AND LOW LYING AREAS BEING A CONTINUED CONCERN. BY THE MIDDLE OF NEXT WEEK, WITH AN AREA OF HIGH PRESSURE PROGGED TO EDGE INTO OUR REGION FROM THE NORTHWEST, THE STALLED FRONTAL BOUNDARY WILL GRADUALLY BE PUSHED FARTHER SOUTH, ALLOWING FOR SOME DRIER AIR TO ADVANCE INTO THE REGION. OVERALL, NEAR TO SLIGHTLY ABOVE AVERAGE DAYTIME TEMPERATURES ARE EXPECTED FOR THE REGION THROUGH THE WEEKEND, WITH HIGHS REACHING FROM THE UPPER 70S ACROSS THE SOUTHERN POCONOS TO THE UPPER 80S FOR OUR SOUTHERN ZONES. BY THE MIDDLE OF NEXT WEEK, DAYTIME TEMPERATURES SHOULD RETURN CLOSER TO OR EVEN A BIT BELOW AVERAGE AS HIGH PRESSURE BUILDS DOWN FROM THE NORTHWEST, WITH HIGHS RANGING FROM THE LOW TO MID 70S NORTH TO THE LOWER 80S SOUTH. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS IS NOT A CONFIDENT FORECAST THROUGH THE NEXT 12 HOURS GIVEN POCKETS OF DRY AIR ALOFT TRYING TO SQUEEZE INTO THE REGION FROM THE SOUTHWEST MAKING THE CIGS JUMP AROUND A BIT. FOR TONIGHT, WE SHOULD REMAIN PRIMARILY MVFR OUTSIDE OF MIV/ACY, WITH AREAS OF SHOWERS AND POSSIBLE A COUPLE RUMBLES OF THUNDER MOVING THROUGH FOR THE NEXT COUPLE OF HOURS. TEMPO GROUPS HAVE BEEN PLACED IN THE TAFS FOR SUCH OCCURRENCES. TERMINALS THAT RECEIVE A BIT MORE RAIN TONIGHT HAVE A BETTER CHANCE AT SEEING IFR CIGS DEVELOP BY MID-MORNING, OR AT LEAST LOW-MVFR. AGAIN NOT TOO CONFIDENT ON HOW WIDESPREAD THE IFR CIGS WILL BE. ON THURSDAY WE ARE EXPECTING CONDITIONS TO IMPROVE TO VFR, WITH GREATER CONFIDENCE AS THE MORNING PROGRESSES AND LIKELY FASTER IMPROVEMENT SOUTHERN TERMINALS, AIRPORTS VS THE NORTHERN ONES. THERE WILL BE A GREATER CHANCE FOR THUNDERSTORMS VS TODAY, WHICH SHOULD BE MAINLY AFTER 18Z. PROB30S HAVE BEEN PLACED AT A MAJORITY OF OUR TAFS TO ACCOUNT FOR THE AFTERNOON STORMS THOUGH TIMING STILL NEEDS TO BE TWEAKED. OUTLOOK... THURSDAY NIGHT THROUGH EARLY MORNING SATURDAY...MAINLY MVFR CONDITIONS EXPECTED. POTENTIAL FOR LOWER CONDITIONS AT TIMES IN HEAVIER SHOWERS AND TSTORMS. REMAINDER OF SATURDAY THROUGH MONDAY...MOSTLY VFR CONDITIONS. ISOLATED SHWRS/TSTORMS REMAIN POSSIBLE. && .MARINE... SUB SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED THROUGH THURSDAY. THE STRONGEST WINDS HAVE BEEN NEAR THE IMMEDIATE COAST. WAVE WATCH MODEL IS ABOUT TO START RUNNING ABOUT A FOOT TOO HIGH. IN GENERAL A SOUTHERLY FLOW OF AIR IS EXPECTED TO PREVAIL THROUGH THURSDAY AS OUR FORECAST AREA GETS DEEPER INTO THE WARM SECTOR ON THE OTHER SIDE OF THE WARM FRONT. THUS GUIDANCE WINDS SHOULD BE A BIT ON THE HIGH SIDE AND WE CAPPED SEAS ABOUT A FOOT BELOW WAVE WATCH GUIDANCE. OUTLOOK... OVERALL, SUB-SCA CONDITIONS ARE EXPECTED FOR OUR AREA WATERS THROUGH THE BULK OF THE OUTLOOK PERIOD. GUIDANCE IS SHOWING AN INCREASE IN THE SOUTHERLY TO SOUTHWESTERLY FLOW DURING FRIDAY AHEAD OF AN APPROACHING COLD FRONT. SOME WIND GUSTS AROUND 20 KNOTS ARE EXPECTED FRIDAY INTO FRIDAY NIGHT. IN ADDITION, WAVEWATCH GUIDANCE ALSO INDICATES SEAS RISING TO AROUND 5 FEET FOR OUR COASTAL WATERS DURING THIS TIMEFRAME. HOWEVER, THIS GUIDANCE TENDS TO RUN A LITTLE HIGH IN SOUTHERLY FLOW, AND CONFIDENCE IS BELOW AVERAGE AT THIS TIME FOR SEAS REACHING 5 FEET BEFORE THE FRONTAL BOUNDARY MOVES THROUGH AND WINDS BECOME MORE WEST AND THEN NORTHWEST OVER THE WEEKEND. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...KLINE NEAR TERM...GIGI/HEAVENER SHORT TERM...GIGI LONG TERM...KLINE AVIATION...GIGI/HEAVENER/KLINE MARINE...GIGI/KLINE
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
825 PM EDT WED AUG 7 2013 .DISCUSSION... LATEST RUC ANALYSIS SHOWING THE ATLC RIDGE AXIS EXTENDING DOWN THE ERN SEABOARD WITH THE AXIS ROUGHLY PARALLEL AND JUST N OF THE I-4 CORRIDOR. PENINSULA WSR-88D WIND PROFILERS SHOWING A STEADY E/SE BREEZE THRU 4-5KFT...CONSISTENT WITH THE POSITION OF THE RIDGE. RUC ANALYSIS SHOWING LITTLE IN THE WAY OF MID LVL VORTICITY UPSTREAM COUPLED WITH FAIRLY STRONG SINKING OMEGA AIR. H100-H70 MEAN RH VALUES BTWN 75-80PCT OVER THE LCL ATLC...DECREASING BLO 70PCT OVER THE NRN/CENTRAL BAHAMAS. WEAK THERMODYNAMIC PROFILE OVERHEAD AS WELL WITH MID LVL LAPSE RATES AOB 5.5C/KM...H70 TEMPS ARND 9C...AND H50 TEMPS ARND -6C. DIURNAL CONVECTION HAS PUSHED W OF THE CWA...CONCENTRATING ALONG THE W FL COAST WITH SOME RATHER ACTIVE TSRA CELLS OVER THE TAMPA BAY AREA. UPSTREAM...ISOLD SHRAS DVLPG IN THE WAKE VORTICIES DOWNWIND OF THE NRN BAHAMAS AS SHOWN LITTLE SHOREWARD DRIFT. FARTHER N ISOLD SHRAS OFF THE FIRST COAST SHOWING MORE WRLY MOTION BUT NOT SURVIVING LONG AS THEY DRIFT OUT OF THE WARMER GULF STREAM WATERS. ANTICIPATE ONLY BRIEF ISOLD SHRA ACTIVITY OVER THE GULF STREAM OVERNIGHT AS THE DRIER AND MORE STABLE UPSTREAM AIRMASS BEGINS TO ADVECT W TOWARD THE FL PENINSULA. LCL NUMERICAL GUIDANCE INDICATING OVERNIGHT POPS BLO 15PCT AREAWIDE...BLO 10PCT S OF KMLB...MOST OF WHICH REFLECTS THE REMNANT OF TODAY`S CONVECTION. CAN SEE NO MEANINGFUL CHANCE FOR COASTAL SHRAS OVERNIGHT. EVEN IF ONE OR TWO WERE TO SURVIVE THE TREK ACRS THE COOLER SHELF WATERS...IMPACT WOULD BE NEGLIGIBLE AND LIMITED TO THE IMMEDIATE COAST. WILL REMOVE PRECIP FROM THE FCST WITH THE EVENING UPDATE. && .AVIATION... THRU 08/14Z...VFR ALL SITES...SE SFC WNDS DECREASING TO AOB 5KTS INTERIOR...5-10KTS ALONG THE COAST. BTWN 08/14Z-08/17Z...E/SE SFC WNDS INCREASING TO 12-15KTS WITH OCNL SFC G20KTS S OF KMLB. BTWN 08/17Z-08/23Z...SCT MVFR SHRAS/ISOLD IFR TSRAS NW OF KMLB-KOBE MVG W/NW ARND 15KTS. && .MARINE... DATA BUOYS/C-MAN STATIONS MEASURING SERLY WINDS AOB 12KTS...SEAS 1-2FT NEARSHORE AND 2-3FT OFFSHORE. LITTLE CHANGE ANTICIPATED OVERNIGHT WITH THE BROAD ATLC RIDGE AXIS REBUILDING ALONG THE I-4 CORRIDOR IN THE WAKE OF AN ERLY WAVE PUSHING INTO THE SE GOMEX. WILL ADJUST SEAS DOWN ABOUT A FOOT AREAWIDE WITH THE EVENING UPDATE. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...BRAGAW IMPACT WX...PENDERGRAST
AREA FORECAST DISCUSSION
NWS MIAMI FL
253 PM EDT TUE AUG 6 2013 .SHORT TERM (TONIGHT-THURSDAY NIGHT)... A MID/UPPER LEVEL RIDGE CURRENTLY STRETCHES ACROSS THE SOUTHERN STATES INTO THE ATLANTIC WITH AN INVERTED TROUGH MOVING WEST ACROSS THE EASTERN BAHAMAS BENEATH THE RIDGE AXIS. AT THE SURFACE, A WEAK SURFACE TROUGH EXTENDS FROM SOUTH FLORIDA INTO THE NORTHERN BAHAMAS AND INTO THE CENTRAL ATLANTIC. THE SURFACE TROUGH IS A VERY SHALLOW FEATURE AND THIS COMBINED WITH THE UPPER TROUGH TO THE EAST AND RIDGE TO THE NORTH IS RESULTING IN VERY WEAK SURFACE PRESSURE GRADIENT BECOMING NORTH TO NORTHEAST FLOW ABOVE 5K FT. THE 12Z MFL SOUNDING CAPTURED THIS WELL AND ALSO SHOWS PWAT REMAINING AT AROUND TWO INCHES. ALL OF THIS SPELLS CONVECTIVE DEVELOPMENT MOVING OFF TO THE SOUTH AND THE HRRR HAS BEEN INDICATING THIS ALSO WITH GOOD INITIAL TIMING AND LOCATION. THE SOUNDING ALSO SHOWED MID LEVEL LAPSE RATES QUITE WEAK AT 5.8 DEGREES CELSIUS/KM AND A 500 MB TEMPERATURE OF ONLY -5.9 WHICH IS NEARLY TWO DEGREES WARMER THAN AVERAGE FOR EARLY AUGUST SO ONLY ISOLATED STRONG STORMS ARE EXPECTED THIS AFTERNOON AT BEST. THE MID LEVEL TROUGH WILL CONTINUE MOVING TO THE WEST IN THE SHORT TERM WITH ALL GLOBAL MODELS IN VERY GOOD AGREEMENT SHIFTING IT INTO THE CENTRAL BAHAMAS ON WEDNESDAY AND THE WESTERN BAHAMAS BY LATE THURSDAY. AS THE TROUGH APPROACHES SOUTH FLORIDA, THE EASTERLY FLOW WILL DEEPEN AS THE UPPER RIDGE TO THE NORTH MOVES LITTLE THROUGH THIS PERIOD. THE ATMOSPHERIC MOISTURE PROFILE WILL CHANGE LITTLE THROUGH WEDNESDAY AND WITH THE EAST FLOW DEEPENING, THE PRIMARY THREAT FOR CONVECTIVE ACTIVITY WILL TEND TO BE MORNING SHOWERS ALONG THE EAST COAST AND THEN SCATTERED SHOWERS/THUNDERSTORMS DEVELOPING OVER THE INTERIOR DURING THE AFTERNOON AND MOVING TOWARDS THE SOUTHWEST COAST. THE STEERING WINDS ARE ONLY EXPECTED TO BE AROUND 5 MPH SO THE THREAT WILL EXIST FOR POSSIBLE LOCALLY HEAVY RAINS IN THE NAPLES AREA. THERE COULD ACTUALLY BE LESS ACTIVITY ON THURSDAY AS THE TROUGH APPROACHES WHICH PLACES SOUTH FLORIDA ON THE SUBSIDENCE SIDE. THIS TROUGH CURRENTLY SHOWS UP VERY WELL IN WATER VAPOR IMAGERY WITH STRONG SUBSIDENCE SHOWING UP TO ITS WEST. THE MODELS ALSO SHOW THE LOW MAINTAINING ITS CURRENT STRENGTH SO ANOTHER REASON THERE COULD BE LESS ACTIVITY. BY THURSDAY NIGHT, THE ATMOSPHERE WILL UNDERGO GOOD DESTABILIZATION AS THE TROUGH MOVES INTO THE STRAITS OF FLORIDA. THE GFS IS INDICATING 500 MB TEMPERATURES COOLING TO -11 SOUTHEAST OF KEY LARGO AND -10 OFF THE SOUTHEAST COAST. THE NAM IS A TAD BID SLOWER WITH THE MOVEMENT BUT STILL SHOWS THIS SAME COLD POOL ABOUT 50-100 MILES TO THE SOUTHEAST OF THE GFS POSITION. AT ANY RATE, THIS COULD SET OFF SOME IMPRESSIVE LIGHTNING DISPLAYS TO OUR SOUTHEAST THURSDAY EVENING AND NIGHT AS CONVECTIVE CELLS COULD EASILY DEVELOP OVER THE ATLANTIC WATERS WITH SUCH COLD TEMPERATURES ALOFT MOVING ACROSS THE GULF STREAM WATERS MAKING THE ENVIRONMENT VERY UNSTABLE. BUT AS ALWAYS AS WE GET OUT WITH TIME, CONFIDENCE IS LESS SO IT IS A WAIT AND SEE APPROACH. .LONG TERM (FRIDAY-TUESDAY)... LATE IN THE WEEK AND INTO THE WEEKEND AND EARLY NEXT WEEK, THE TROUGH WILL CONTINUE WESTWARD INTO THE GULF OF MEXICO ALLOWING THE ATLANTIC RIDGE TO ALSO BUILD WEST. THIS WILL STABILIZE THE ATMOSPHERE ONCE AGAIN AND THE GFS IS ALSO SHOWING SIGNIFICANT DRYING TAKING PLACE WITH PWAT DROPPING WELL UNDER TWO INCHES. SO WHILE FRIDAY COULD REMAIN QUITE ACTIVE, MUCH LESS ACTIVITY IS LIKELY AS WE GET INTO THE WEEKEND AND CROSS OVER INTO NEXT WEEK. && .AVIATION... ISOLATED HEAVY SHOWERS AND STORMS HAVE ALREADY DEVELOPED THIS AFTERNOON ACROSS PORTIONS OF THE AREA...MOSTLY SOUTH OF A LINE FROM FLL TO APF WITH THE MEAN LOW-LEVEL NORTHERLY FLOW IN PLACE. ALTHOUGH MOST OF THE AFTERNOON/EVENING ACTIVITY SHOULD REMAIN JUST INLAND OF THE TAF SITES...WE WILL CONTINUE TO INCLUDE VCTS AT MOST SITES FROM 21Z THROUGH THE EVENING HOURS AND UPDATE AS CONDITIONS EVOLVE. OVERNIGHT TONIGHT THROUGH WEDNESDAY...THE FLOW SHOULD BECOME MORE EASTERLY...WHICH WILL TRANSLATE TO THE BEST RAINFALL CHANCES SETTING UP ACROSS THE INTERIOR AND WESTERN LOCATIONS OF SOUTH FLORIDA THROUGH THE DAY WEDNESDAY. && .MARINE... LIGHT AND VARIABLE WIND TONIGHT WILL SLOWLY BECOME EAST BY WEDNESDAY AND THEN STRENGTHENING LATER IN THE WEEK AS THE GRADIENT TIGHTENS. THIS WILL BUILD SEAS OVER THE NEXT COUPLE OF DAYS BUT REMAIN WELL BELOW ADVISORY CRITERIA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 76 89 78 89 / 20 20 20 20 FORT LAUDERDALE 78 90 81 90 / 20 20 20 20 MIAMI 78 91 79 89 / 20 20 20 20 NAPLES 77 92 76 93 / 20 40 30 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...30/KOB AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS MIAMI FL
134 AM EDT TUE AUG 6 2013 .AVIATION... RIDGING CONTINUES TO CONTROL THE PATTERN THROUGH THIS TAF PERIOD. A HIGH PRESSURE RIDGE OVER MOST OF THE GULF OF MEXICO HAS TURNED TO MID LEVEL FLOW MORE NORTHERLY TONIGHT. THIS WILL KEEP UPPER LEVEL CLOUD COVER OVER SOUTH FLORIDA FOR A GOOD PART OF THE OVER NIGHT HOURS. TOMORROW, THE SEA BREEZE WILL DEVELOP AS CLOUDS BECOME MORE SCT IN NATURE AND ALLOW DAYTIME HEATING. THIS WILL ALLOW SHOWERS AND THUNDERSTORMS TO DEVELOP ONCE AGAIN, MAINLY IN THE INTERIOR OF SOUTH FLORIDA. BY VERY EARLY AFTERNOON, THUNDERSTORMS COULD BEGIN TO INFRINGE ON THE TAF SITES. HAVE TAKE VCTS OUT FOR THE MORNING HOURS, AS CHANCES ARE LOWER THAN 30 PERCENT, BUT KEPT THEM IN AFTER 17Z AT ALL ATLANTIC SITES. KAPF MAY SEE A SLIGHTLY EARLIER START. WINDS TOMORROW WILL TRY TO PICKUP OUT OF THE NNW, BUT SHOULD BECOME INFLUENCED BY THE SEA BREEZE AFTER 17Z. VFR CONDITIONS, OTHER THEN AREAS UNDER CONVECTION, WILL BE THE GENERAL RULE THROUGH THE TAF PERIOD. && .PREV DISCUSSION... /ISSUED 815 PM EDT MON AUG 5 2013/ UPDATE... CONVECTIVE ACTIVITY CONTINUES TO WANE ACROSS THE NORTHWEST INTERIOR THIS EVENING...DEVOLVING INTO MAINLY MODERATE STRATIFORM RAIN SHOWERS. LATEST HRRR CONTINUES TO SHOW THE REMAINDER OF THE LINGERING RAINFALL TO DISSIPATE OVER THE NEXT FEW HOURS AS IT SLOWLY HEADS TO THE SOUTH. INCREASED POPS THROUGH THE EVENING TO ACCOUNT FOR THE RATHER LARGE STRATIFORM RAIN SHIELD. THE REMAINDER OF THE FORECAST LOOKS GOOD AT THIS TIME. PREV DISCUSSION... /ISSUED 208 PM EDT MON AUG 5 2013/ SHORT TERM (TONIGHT-TUESDAY NIGHT)... CURRENT SYNOPTIC ANALYSIS SHOWS STRONG MID LEVEL RIDGE CENTERED OVER TEXAS WITH ITS RIDGE AXIS STRETCHING TO THE SOUTHEAST ACROSS THE STRAITS OF FLORIDA. AT THE SURFACE, A TROUGH EXTENDS ACROSS NORTH CENTRAL FLORIDA INTO THE ATLANTIC WITH A SURFACE RIDGE OVER THE FLORIDA KEYS. THIS IS CONTINUING THE WESTERLY STEERING FLOW FOR SOUTH FLORIDA WITH THE BEST CHANCES FOR THUNDERSTORMS OVER THE INTERIOR AND EAST COAST METRO REGION THROUGH EARLY THIS EVENING. THE OVERNIGHT HOURS TONIGHT WILL BE MOSTLY TRANQUIL ONCE THE DIURNAL HEATING CYCLE IS LOST AND THE LOW LEVEL FLOW BECOMES LIGHT AND VARIABLE. ON TUESDAY, SOUTH FLORIDA WILL UNDERGO A TRANSITIONAL PERIOD AS A MID LEVEL INVERTED TROUGH APPROACHES FROM THE EAST. THIS TROUGH IS CURRENTLY NEAR HISPANIOLA AND HAS BEEN WELL TRACKED BY THE GLOBAL MODELS. IT WILL MOVE INTO THE EASTERN BAHAMAS ON TUESDAY WHICH WILL GRADUALLY SHIFT THE MID/UPPER WIND FLOW TO A NORTHEAST DIRECTION. AT THE SAME TIME, A SURFACE RIDGE WILL BUILD FROM THE CENTRAL GULF OF MEXICO TO THE SOUTHEAST U.S. VEERING THE LOW LEVEL WIND TO AN EAST DIRECTION ACROSS OUR REGION. THE FORECAST SOUNDINGS ARE INDICATING PWAT REMAINING NEAR TWO INCHES SO STORMS WILL TEND TO DEVELOP NEAR THE EAST COAST AND THEN SLOWLY DRIFT TOWARDS THE WEST INTO THE EVERGLADES AND SOUTHWEST COAST. THE INVERTED TROUGH WILL MOVE INTO THE CENTRAL BAHAMAS ON WEDNESDAY WITH A SURFACE RIDGE ACROSS NORTH FLORIDA. THIS WILL RESULT IN A DEEP EASTERLY FLOW BECOMING ESTABLISHED ACROSS SOUTH FLORIDA. THIS COULD BRING AN INCREASING CHANCE OF NOCTURNAL SHOWERS ALONG THE EAST COAST TUESDAY NIGHT INTO WEDNESDAY MORNING AND A THREAT FOR AFTERNOON THUNDERSTORMS ACROSS THE INTERIOR AND SOUTHWEST COAST. AT THIS TIME, THE ATMOSPHERIC INSTABILITY PROFILE DOES NOT CHANGE MUCH WITH PWAT CONTINUING AROUND TWO INCHES AND WEAK MID LEVEL LAPSE RATES. LONG TERM (WEDNESDAY-MONDAY)... LOOKING AHEAD INTO THE EXTENDED PERIOD, THURSDAY APPEARS TO BE SOMEWHAT UNCERTAIN AS TO THE CHANCE FOR THUNDER. THE INVERTED TROUGH WILL MOVE ACROSS THE AREA WITH A STRONG DEEP LAYER RIDGE OVER NORTH FLORIDA. THIS TRANSLATES TO EASTERLY FLOW THROUGH THE ENTIRE ATMOSPHERE ACROSS SOUTH FLORIDA. IN FACT, THE LATEST 12Z RUN OF THE GFS IS INDICATING A STEERING FLOW OF 15 TO 20 MPH BY THURSDAY AFTERNOON AND IF THIS VERIFIES THE CHANCE FOR THUNDER WOULD BE MINIMAL WITH A MAJORITY OF THE ACTION BEING FAST MOVING SHOWERS. HOWEVER, THE TROUGH IN PLACE WILL ALSO DESTABILIZE THE MID LEVELS WITH MODELS ALSO SHOWING SIGNIFICANT COOLING ALOFT. FOR THIS REASON, DO NOT PLAN TO CHANGE FROM THE CURRENT FORECAST AND WILL WAIT FOR FUTURE GUIDANCE BEFORE MAKING A DECISION. THE TROUGH WILL CONTINUE MOVING WEST INTO THE GULF OF MEXICO ON FRIDAY AND INTO THE WEEKEND WITH THE ATLANTIC RIDGE BUILDING WEST ACROSS THE PENINSULA. THE GFS IS ALSO SHOWING SIGNIFICANT DRYING ALOFT WITH DEEP EASTERLY FLOW CONTINUING SO THIS WILL SET THE STAGE FOR SCATTERED SHOWERS/ISOLATED THUNDER MOSTLY OVER THE INTERIOR AND SOUTHWEST COAST. MARINE... THE SOUTHWEST TO WEST WIND WILL GRADUALLY SHIFT TO THE NORTHEAST AND EAST ON TUESDAY THEN BECOMING EAST ON WEDNESDAY WHILE INCREASING SPEED TO POSSIBLY 15 KNOTS OVER THE ATLANTIC. THIS WILL RESULT IN BUILDING SEAS BY MIDWEEK BUT REMAINING BELOW ADVISORY LEVELS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 91 77 90 78 / 50 20 30 20 FORT LAUDERDALE 89 80 89 79 / 50 20 30 30 MIAMI 91 78 89 80 / 50 20 30 30 NAPLES 92 76 92 76 / 40 20 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...10/CD AVIATION/RADAR...13/SI
FORECAST DISCUSSION BELOW.

20 PREVIOUS LONG TERM DISCUSSION/THURSDAY NIGHT THROUGH TUESDAY/ UPPER RIDGE WILL CONTINUE ANCHORED ACROSS THE SOUTHERN PLAINS WITH A SERIES OF UPPER SHORT WAVES MOVING ACROSS THE STATE. HAVE KEPT MAINLY CHANCE POPS DURING THE DAY AND CHANCE OR SLIGHT CHANCE OVERNIGHT. HOWEVER FOR SATURDAY LOOKS LIKE A FRONTAL BOUNDARY WILL DRIFT INTO NORTH GEORGIA AND STALL FOR A DAY OR TWO. SO HAVE INCLUDED LIKELY POPS FOR NORTH GEORGIA ON SATURDAY. UPPER FLOW TRANSITIONS TO A TROUGH OVER THE EASTERN STATES BY THE FIRST OF THE WEEK. SOME DRYING IS INDICATED FOR NORTH GEORGIA MONDAY AND TUESDAY...BUT NOT ENOUGH TO REMOVE POPS ALTOGETHER. TEMPERATURES LOOK SEASONAL WITH MID TO UPPER 80S NORTH TO LOW AND MID 90S SOUTH. 41 && .HYDROLOGY... FLOODING CONTINUES ACROSS PARTS OF NORTH GEORGIA. MORE RAIN IS POSSIBLE ACROSS THESE ALREADY FLOODED AREAS THROUGH THIS EVENING. WITH ANOTHER DISTURBANCE POSSIBLY AFFECTING THE STATE AGAIN BY THURSDAY MORNING...ADDITIONAL RAINFALL IS EXPECTED AGAIN ON THURSDAY. ALTHOUGH WIDESPREAD AMOUNTS OF A HALF INCH TO AN INCH ARE EXPECTED THROUGH THURSDAY AFTERNOON...ISOLATED HIGHER AMOUNTS ARE POSSIBLE. THE FLASH FLOOD WATCH CONTINUES TO BE IN EFFECT UNTIL 8AM THURSDAY. HAVE OPTED NOT EXTEND IT TEMPORALLY AT THIS POINT DUE TO UNCERTAINTY IN THE FORECAST...BUT IT IS A DISTINCT POSSIBILITY THAT THE FLOOD WATCH WILL NEED TO BE EXTENDED UNTIL THURSDAY AFTERNOON ACROSS PARTS OF NORTH GEORGIA. 11 && .AVIATION... 00Z UPDATE... CONVECTION MAINLY ON THE DECREASE NEAR MOST TAF SITES THIS EVENING AND LINGERING VCSH. IFR CIGS AND MVFR VSBYS ARE LIKELY AFTER ABOUT 09Z TONIGHT WITH POTENTIALLY SLIGHTLY LOWER HEIGHTS. WINDS SHOULD STAY MOSTLY CALM TO SE. CONDITIONS GRADUALLY IMPROVING THURSDAY NEAR MVFR/LOW END VFR CIGS AFTER 16Z. CHANCE FOR TSRA IN AFTERNOON WILL WARRANT PROB30 FOR NOW AS BEST CHANCE LOOKS TO BE NORTH OF SITES. //ATL CONFIDENCE...00Z UPDATE... MEDIUM ON OVERNIGHT CIGS/VSBYS. HIGH ALL ELSE. BAKER && .PRELIMINARY POINT TEMPS/POPS... ATHENS 70 88 72 90 / 40 50 30 30 ATLANTA 71 87 73 89 / 50 40 30 30 BLAIRSVILLE 69 81 68 86 / 60 70 40 40 CARTERSVILLE 71 87 72 90 / 60 60 30 40 COLUMBUS 74 92 74 93 / 70 40 30 30 GAINESVILLE 71 85 72 88 / 40 60 30 40 MACON 71 90 73 93 / 50 30 30 30 ROME 72 88 72 91 / 60 70 30 40 PEACHTREE CITY 70 87 72 90 / 60 40 30 30 VIDALIA 73 92 74 93 / 20 30 20 30 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 8 AM EDT THURSDAY FOR THE FOLLOWING ZONES: BANKS...BARROW...BARTOW...BUTTS...CARROLL...CATOOSA... CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...DADE... DAWSON...DEKALB...DOUGLAS...FANNIN...FAYETTE...FLOYD...FORSYTH... GILMER...GORDON...GREENE...GWINNETT...HALL...HARALSON...HEARD... HENRY...JACKSON...JASPER...LAMAR...LUMPKIN...MADISON... MERIWETHER...MORGAN...MURRAY...NEWTON...NORTH FULTON...OCONEE... OGLETHORPE...PAULDING...PICKENS...PIKE...POLK...PUTNAM... ROCKDALE...SOUTH FULTON...SPALDING...TALIAFERRO...TOWNS... TROUP...UNION...WALKER...WALTON...WHITE...WHITFIELD...WILKES. && $$ SHORT TERM...11/BAKER LONG TERM....20 AVIATION...BAKER
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
137 AM EDT TUE AUG 6 2013 .PREV DISCUSSION... /ISSUED 1041 PM EDT MON AUG 5 2013/ UPDATE... NO MAJOR CHANGES TO THE FORECAST THIS EVENING. WILL NEED TO WATCH TRENDS OVERNIGHT PER LATEST HRRR RUNS WHICH FIRE UP SOME STORMS OVER CENTRAL GA AROUND 07Z. HARD TO FIND ANY EVIDENCE IN OTHER SHORT TERM MODELS...BUT WORTH WATCHING NONETHELESS AS THE REMNANT SEA BREEZE BOUNDARY WORKS INTO THAT REGION. OF MORE INTEREST IS THE CONVECTION NOTED IN NE GA AFTER 07Z IN BOTH THE HRRR AND RUC. WILL AGAIN NEED TO WATCH TRENDS AS ONLY THE LATEST RUNS HAVE BEEN INDICATING THIS. PREV DISCUSSION... /ISSUED 827 PM EDT MON AUG 5 2013/ PREV DISCUSSION... /ISSUED 348 PM EDT MON AUG 5 2013/ SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... MODELS CONSISTENT THROUGH THE SHORT TERM WITH LARGE UPPER LEVEL RIDGE OVER THE SOUTH-CENTRAL U.S. AND LONG-WAVE TROUGH PUSHING EAST OF THE ATLANTIC COAST. MORE OF A ZONAL FLOW ANTICIPATED ACROSS THE REGION AS A RESULT...BUT NOT BEFORE SHORTWAVE DROPS INTO THE AREA TONIGHT AND INTO TUESDAY. ALREADY SEEING SOME VERY ISOLATED SHOWER DEVELOPMENT THIS AFTERNOON...MAINLY ALONG THE SOUTHEASTERN EDGE OF THE CWA WITH THE INFLUENCE OF THE STALLED WEAK SURFACE BOUNDARY. EXPECT THE LOCATION OF ACTIVITY TO TRANSITION TO THE NORTH AS SHORTWAVE APPROACHES. HAVE CONTINUED WITH SLIGHT CHANCE TO CHANCE POPS EVERYWHERE THROUGH THE AFTERNOON...WITH ONLY SLIGHT CHANCE POPS ACROSS THE NORTH AFTER 03-04Z. POPS INCREASE INTO TUESDAY MORNING AND CONTINUE WITH GOOD CHANCE POPS THROUGH TUESDAY AS SHORTWAVE...COMBINED WITH GOOD MOISTURE ACROSS THE AREA...RESULTS IN BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS. AS FOR TEMPERATURES...HAVE GONE WITH A BLEND OF THE MODEL GUIDANCE...WHICH HAS WORKED WELL THE LAST SEVERAL DAYS. TUESDAY HIGHS WILL BE CLOSELY TIED TO PRECIP AND CLOUD COVER...SO ALTHOUGH FORECAST IS SHOWING MID 80S TO NEAR 90...COULD SEE A FEW DEGREE ADJUSTMENT BASED ON FUTURE MODEL RUN GUIDANCE. 31 LONG TERM /WEDNESDAY THROUGH MONDAY/... NO MAJOR CHANGES WERE MADE TO THE EXTENDED PERIOD. LONG RANGE MODELS CONTINUE TO SHOW A DEEP SOUTHERLY WIND FLOW BECOMING ESTABLISHED ON WEDNESDAY AND AN OLD FRONTAL BOUNDARY BECOMING DIFFUSE. THE INCREASING MOISTURE AND INSTABILITY WILL RESULT IN A MORE SCATTERED TO NUMEROUS COVERAGE OF MAINLY DIURNALLY DRIVEN CONVECTION THROUGH FRIDAY. MODELS SHOW A FRONTAL BOUNDARY APPROACHING NORTH GA ON SATURDAY... PUSHING INTO NORTH GA ON SUNDAY... AND BECOMING NEARLY STATIONARY ACROSS CENTRAL GA ON MONDAY. THIS WOULD WARRANT SLIGHTLY HIGHER POPS ACROSS AT LEAST NORTH GA ON SATURDAY AND SUNDAY... THEN ACROSS CENTRAL GA BY MONDAY... AS A DRIER... MORE STABLE AIR MASS BEGINS TO SPREAD INTO NORTH GA ON MONDAY BEHIND THE FRONT. ALTHOUGH WIDESPREAD ORGANIZED SEVERE STORMS ARE NOT EXPECTED WITH THIS OVERALL SYNOPTIC WEATHER PATTERN... AN ISOLATED PULSE STRONG TO SEVERE STORM CANNOT BE RULED OUT EACH DAY... ESPECIALLY DURING MAX DAYTIME HEATING. && .AVIATION... 06Z UPDATE... MVFR CIGS ALREADY MOVING IN TOWARD AHN...AND THIS SHOULD SPREAD WEST OVER THE NEXT COUPLE OF HOURS. MAY SEE BRIEF IFR...BUT CONFIDENCE NOT HIGH. CSG MAY REMAIN VFR BUT CURRENT TAF DOES HAVE THEM GOING MVFR TOWARD SUNRISE. WINDS STILL SORT OF ALL OVER THE PLACE...LGT/VRB. EXPECT A MAINLY SE COMPONENT THOUGH SWITCHING TO SW AROUND 15Z...BACK TO SOLIDLY SE AFTER 00Z. HAVE CONTINUED PROB30 FOR AFTN TSRA BUT WILL REEVALUATE FOR 08Z AMD. INTRODUCED MVFR CIGS AT 06Z TUESDAY AS WELL. //ATL CONFIDENCE...06Z UPDATE... MEDIUM-HIGH ON CIGS. MEDIUM ON WINDS. MEDIUM-HIGH ON CONVECTION. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 84 71 86 71 / 40 30 50 40 ATLANTA 86 72 86 72 / 40 30 50 30 BLAIRSVILLE 83 69 80 67 / 40 40 60 50 CARTERSVILLE 87 72 87 72 / 30 30 50 40 COLUMBUS 92 74 90 74 / 30 20 40 20 GAINESVILLE 83 71 83 71 / 40 30 50 40 MACON 88 71 88 72 / 40 20 40 20 ROME 89 72 88 72 / 30 30 50 40 PEACHTREE CITY 87 71 87 72 / 40 20 50 20 VIDALIA 88 72 91 73 / 40 20 40 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ATWELL LONG TERM....ATWELL AVIATION...TDP
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
236 PM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * IMPROVING CIG TRENDS EARLY THIS AFTERNOON. * CHANCE OF TSRA TONIGHT. KREIN //DISCUSSION...UPDATED 18Z... THE RESIDUAL LOW CLOUD REMNANTS FOLLOWING EARLIER PCPN ARE QUICKLY DISSIPATING AND ALL SITES SHOULD GO VFR BTWN 18-19Z. THE REMAINDER OF THE AFTERNOON AND INTO THE EVENING HOURS SHOULD BE QUIET WITH VFR CIGS/VIS AND GENERALLY WESTERLY WINDS UNDER 10KT. THE NEXT CONCERN WILL BE THE CHANCES FOR THUNDERSTORMS TO AFFECT THE TERMINALS DURG THE EARLY MORNING HOURS. LATEST GUIDANCE STILL SUGGESTS THE POSSIBILITY OF A THUNDERSTORM COMPLEX TO DEVELOP TONIGHT FROM WISCONSIN TO IOWA IN ADVANCE OF AN APPROACHING COLD FRONT. EXPECT THAT THE BEST WINDOW OF OPPORTUNITY FOR TSRA TO IMPACT THE TERMINALS WILL BE GENERALLY BETWEEN 06Z-12Z. BASED ON THE LATEST LOCAL HIGH RES MODELS...HAVE PUSHED BACK THE TIMING A LITTLE FROM THE GOING FORECAST AND INTRODUCED A PROB30 GROUP OUTLINING THE MOST LIKELY TIMING BASED ON THE LATEST GUIDANCE...WHICH WOULD BRING TSRA TO THE RFD AREA BTWN 06-10Z AND THE CHICAGO AREA BTWN 08-12Z. THE TS POTENTIAL SHOULD QUICKLY SHUT OFF FOLLOWING THE FROPA...SO THE DURATION OF TS WILL BE HIGHLY DEPENDENT ON THE FRONTAL PROGRESSION SPEED. SO...WILL GO WITH THE PROB30 GROUP FOR NOW AND REFINE THE FORECAST TIMING...POSSIBLY UPGRADING TO A TEMPO OR PREVAILING GROUP AS ANTICIPATED CONDITIONS WARRANT. THE ONLY OTHER SIGNIFICANT CONCERN WILL BE WIND DIRECTION TRENDS. CURRENTLY...ANTICIPATE THAT WINDS SHOULD REMAIN GENERALLY WLY THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE EVENING. AS THE FRONT APPROACHES...EXPECT THAT WINDS SHOULD BACK TO MORE SLY BEFORE QUICKLY VEERING NWLY FOLLOWING THE FROPA. WITH THE EXPECTATION OF THE ENVIRONMENT AROUND ANY THUNDERSTORMS...WINDS SHOULD GENERALLY REMAIN AT OR BELOW 10KT GIVING A RELATIVELY PRESSURE GRADIENT OVER THE REGION AND THE LACK OF A STRONG COLD AIR PUSH FOLLOWING THE FROPA. KREIN //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TONIGHT...WITH LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. MONDAY...SLIGHT CHANCE OF TSRA. KJB && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
1251 PM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * IMPROVING CIG TRENDS EARLY THIS AFTERNOON. * CHANCE OF TSRA TONIGHT. KREIN //DISCUSSION...UPDATED 18Z... THE RESIDUAL LOW CLOUD REMNANTS FOLLOWING EARLIER PCPN ARE QUICKLY DISSIPATING AND ALL SITES SHOULD GO VFR BTWN 18-19Z. THE REMAINDER OF THE AFTERNOON AND INTO THE EVENING HOURS SHOULD BE QUIET WITH VFR CIGS/VIS AND GENERALLY WESTERLY WINDS UNDER 10KT. THE NEXT CONCERN WILL BE THE CHANCES FOR THUNDERSTORMS TO AFFECT THE TERMINALS DURG THE EARLY MORNING HOURS. LATEST GUIDANCE STILL SUGGESTS THE POSSIBILITY OF A THUNDERSTORM COMPLEX TO DEVELOP TONIGHT FROM WISCONSIN TO IOWA IN ADVANCE OF AN APPROACHING COLD FRONT. EXPECT THAT THE BEST WINDOW OF OPPORTUNITY FOR TSRA TO IMPACT THE TERMINALS WILL BE GENERALLY BETWEEN 06Z-12Z. BASED ON THE LATEST LOCAL HIGH RES MODELS...HAVE PUSHED BACK THE TIMING A LITTLE FROM THE GOING FORECAST AND INTRODUCED A PROB30 GROUP OUTLINING THE MOST LIKELY TIMING BASED ON THE LATEST GUIDANCE...WHICH WOULD BRING TSRA TO THE RFD AREA BTWN 06-10Z AND THE CHICAGO AREA BTWN 08-12Z. THE TS POTENTIAL SHOULD QUICKLY SHUT OFF FOLLOWING THE FROPA...SO THE DURATION OF TS WILL BE HIGHLY DEPENDENT ON THE FRONTAL PROGRESSION SPEED. SO...WILL GO WITH THE PROB30 GROUP FOR NOW AND REFINE THE FORECAST TIMING...POSSIBLY UPGRADING TO A TEMPO OR PREVAILING GROUP AS ANTICIPATED CONDITIONS WARRANT. THE ONLY OTHER SIGNIFICANT CONCERN WILL BE WIND DIRECTION TRENDS. CURRENTLY...ANTICIPATE THAT WINDS SHOULD REMAIN GENERALLY WLY THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE EVENING. AS THE FRONT APPROACHES...EXPECT THAT WINDS SHOULD BACK TO MORE SLY BEFORE QUICKLY VEERING NWLY FOLLOWING THE FROPA. WITH THE EXPECTATION OF THE ENVIRONMENT AROUND ANY THUNDERSTORMS...WINDS SHOULD GENERALLY REMAIN AT OR BELOW 10KT GIVING A RELATIVELY PRESSURE GRADIENT OVER THE REGION AND THE LACK OF A STRONG COLD AIR PUSH FOLLOWING THE FROPA. KREIN //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TONIGHT...WITH LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. MONDAY...SLIGHT CHANCE OF TSRA. KJB && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
1103 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * CIG TRENDS WITH LOW MVFR CIGS LEVEL THIS MORNING. * TIMING THE IMPROVEMENT OF CIGS DURING THE LATE MORNING HOURS. IMPROVEMENT MIGHT BE A LITTLE LATER THAN TAF INDICATES...BUT WHEN IMPROVEMENT COMES...SHOULD BE QUICK. * CHANCE OF TSRA TONIGHT. KREIN //DISCUSSION...UPDATED 12Z... THERE ARE A FEW LINGERING SHOWERS LEFT OVER FROM THE OVERNIGHT STORMS ACROSS NORTH CENTRAL ILLINOIS. HOWEVER...THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS TRENDS THIS MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A MESSY MORNING ACROSS THE AREA. CIGS AND VIS ARE TANKING IN THE WAKE OF THE HIGHER CLOUD COVER AND AREA OF SHOWERS. MOST AREAS WEST OF THE CHICAGO AREA ARE UNDER 800 FEET WITH VIS NOW DOWN TO 1/2 SM AT KRFD. I EXPECT THESE DETERIORATING CONDITIONS TO CONTINUE TO OVERSPREAD THE EASTERN TAF SITES EARLY THIS MORNING. I SUSPECT THAT THE VIS WILL DROP AT KORD AND KMDW AS WELL FOR A PERIOD EARLY THIS MORNING...BUT CONFIDENCE ON HOW LOW THEY WILL DROP IS LOW...BUT MVFR VIS AROUND 5 SM IS CERTAINLY POSSIBLE GIVEN THE TRENDS TO THE WEST. SO BY FAR THE BIGGEST DEAL WILL BE THE LOW CIGS. CIGS WILL PROB BE A BIT SLOW TO RECOVER THIS MORNING...WITH NO BIG IMPROVEMENTS UNTIL AFTER 14-15 UTC THIS MORNING. HOWEVER...ONCE THINGS IMPROVE LATER THIS MORNING...AVIATION WEATHER CONCERNS SHOULD BE AT A MINIMUM THROUGH THE REST OF THE DAY. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. IT MAY BE IN A WEAKENING STATE AS IT ARRIVES ACROSS NORTHEASTERN ILLINOIS...BUT I DID CONTINUE THE MENTION OF SHRA AND VCTS ALL THE TAFS AFTER 06 UTC TONIGHT. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIR MASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 16Z... * LOW CONFIDENCE IN TIMING OF IMPROVEMENT OF THE MVFR CIGS THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TONIGHT...WITH LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. MONDAY...SLIGHT CHANCE OF TSRA. KJB && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
913 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * CIG AND VIS TRENDS WITH LOW MVFR/IFR CIGS DOWN IN THE 800-1000 FEET LEVEL THIS MORNING. * TIMING THE IMPROVEMENT OF CIGS DURING THE MID TO LATE MORNING HOURS. IMPROVEMENT MIGHT BE A LITTLE LATER THAN TAF INDICATES...BUT WHEN IMPROVEMENT COMES...SHOULD BE QUICK. * CHANCE OF TSRA TONIGHT. KREIN //DISCUSSION...UPDATED 12Z... THERE ARE A FEW LINGERING SHOWERS LEFT OVER FROM THE OVERNIGHT STORMS ACROSS NORTH CENTRAL ILLINOIS. HOWEVER...THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS TRENDS THIS MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A MESSY MORNING ACROSS THE AREA. CIGS AND VIS ARE TANKING IN THE WAKE OF THE HIGHER CLOUD COVER AND AREA OF SHOWERS. MOST AREAS WEST OF THE CHICAGO AREA ARE UNDER 800 FEET WITH VIS NOW DOWN TO 1/2 SM AT KRFD. I EXPECT THESE DETERIORATING CONDITIONS TO CONTINUE TO OVERSPREAD THE EASTERN TAF SITES EARLY THIS MORNING. I SUSPECT THAT THE VIS WILL DROP AT KORD AND KMDW AS WELL FOR A PERIOD EARLY THIS MORNING...BUT CONFIDENCE ON HOW LOW THEY WILL DROP IS LOW...BUT MVFR VIS AROUND 5 SM IS CERTAINLY POSSIBLE GIVEN THE TRENDS TO THE WEST. SO BY FAR THE BIGGEST DEAL WILL BE THE LOW CIGS. CIGS WILL PROB BE A BIT SLOW TO RECOVER THIS MORNING...WITH NO BIG IMPROVEMENTS UNTIL AFTER 14-15 UTC THIS MORNING. HOWEVER...ONCE THINGS IMPROVE LATER THIS MORNING...AVIATION WEATHER CONCERNS SHOULD BE AT A MINIMUM THROUGH THE REST OF THE DAY. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. IT MAY BE IN A WEAKENING STATE AS IT ARRIVES ACROSS NORTHEASTERN ILLINOIS...BUT I DID CONTINUE THE MENTION OF SHRA AND VCTS ALL THE TAFS AFTER 06 UTC TONIGHT. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIR MASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 14Z... * LOW CONFIDENCE IN TIMING OF IMPROVEMENT OF THE LOW MVFR/IFR CIGS THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. MONDAY...SLIGHT CHANCE OF TSRA. KJB && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
648 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * CIG AND VIS TRENDS WITH LOW MVFR/IFR CIGS DOWN IN THE 700-1000 FEET LEVEL EARLY THIS MORNING. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MID TO LATE MORNING HOURS. BIG IMPROVEMENTS NOT LIKELY UNTIL AFTER 14-15 UTC. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 12Z... THERE ARE A FEW LINGERING SHOWERS LEFT OVER FROM THE OVERNIGHT STORMS ACROSS NORTH CENTRAL ILLINOIS. HOWEVER...THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS TRENDS THIS MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A MESSY MORNING ACROSS THE AREA. CIGS AND VIS ARE TANKING IN THE WAKE OF THE HIGHER CLOUD COVER AND AREA OF SHOWERS. MOST AREAS WEST OF THE CHICAGO AREA ARE UNDER 800 FEET WITH VIS NOW DOWN TO 1/2 SM AT KRFD. I EXPECT THESE DETERIORATING CONDITIONS TO CONTINUE TO OVERSPREAD THE EASTERN TAF SITES EARLY THIS MORNING. I SUSPECT THAT THE VIS WILL DROP AT KORD AND KMDW AS WELL FOR A PERIOD EARLY THIS MORNING...BUT CONFIDENCE ON HOW LOW THEY WILL DROP IS LOW...BUT MVFR VIS AROUND 5 SM IS CERTAINLY POSSIBLE GIVEN THE TRENDS TO THE WEST. SO BY FAR THE BIGGEST DEAL WILL BE THE LOW CIGS. CIGS WILL PROB BE A BIT SLOW TO RECOVER THIS MORNING...WITH NO BIG IMPROVEMENTS UNTIL AFTER 14-15 UTC THIS MORNING. HOWEVER...ONCE THINGS IMPROVE LATER THIS MORNING...AVIATION WEATHER CONCERNS SHOULD BE AT A MINIMUM THROUGH THE REST OF THE DAY. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. IT MAY BE IN A WEAKENING STATE AS IT ARRIVES ACROSS NORTHEASTERN ILLINOIS...BUT I DID CONTINUE THE MENTION OF SHRA AND VCTS ALL THE TAFS AFTER 06 UTC TONIGHT. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIR MASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM CONFIDENCE IN TIMING OF IMPROVEMENT OF THE LOW MVFR/IFR CIG/VIS THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... WEDNESDAY NIGHT THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. MONDAY...SLIGHT CHANCE OF TSRA. KJB && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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...UPDATED
NWS CHICAGO/ROMEOVILLE IL
421 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCED SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE SCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. WHILE THE CONVECTION IS LIKELY TO BE ON A WEAKENING TREND INTO WEDNESDAY MORNING...IF NOT ALREADY OVERNIGHT...GUIDANCE HAS AGREED ON A SLOWER MOVEMENT OF THE FRONT IN THE PAST 24 HOURS. SO HAVE INCREASED POPS IN EASTERN AREAS DURING EARLY WEDNESDAY. CONFIDENCE...MEDIUM. WEDNESDAY AFTERNOON THROUGH FRIDAY...AS THE FRONT EASES IN SPEED THERE IS CONCERN FOR CONVECTION IN THE SOUTHEAST PART OF THE FORECAST AREA WEDNESDAY AFTERNOON. HIGH MOISTURE WILL STILL OWE TO MODEST TO HIGH INSTABILITY ALONG THE BOUNDARY. EVEN A SLOWER FRONTAL MOVEMENT MAY MEAN WE COULD HAVE A SEVERE WEATHER THREAT IN THE FAR SOUTHERN FORECAST AREA. FOR THE TIME BEING MAINTAIN THE CHANCE POPS IN THE SOUTHERN AREA. LARGER INCREASES IN POPS WERE MADE FOR THU NIGHT AND INTO FRI ACROSS THE SOUTHEAST HALF OF THE FORECAST AS ONE AND POSSIBLY MULTIPLE WAVES TRAVERSE THE BOUNDARY...SPREADING SOUTHERLY 850MB FLOW NORTH OF THE FEATURE POTENTIALLY LEADING TO SOME SHOWERS AND STORMS ACROSS OUR AREA...DESPITE NORTHERLY SURFACE FLOW. THE MAIN FOCUS FOR ANYTHING OF HIGH IMPACT STILL LOOKS TO BE WELL SOUTH OF THE AREA. FOR TEMPERATURES ON WED-FRI HAVE GONE JUST A COUPLE DEGREES ABOVE AN OFFICIAL/MODEL BLEND. THIS WEEKEND...LITTLE CHANGES MADE TO THE GOING FORECAST AS HIGH PRESSURE IS STILL FAVORED IN THAT TIME YIELDING LIKELY PLEASANT WEATHER. GUIDANCE MAY BE A LITTLE QUICK ON BRINGING PRECIP CHANCES BACK SUNDAY NIGHT...BUT FOR THE TIME BEING HAVE GONE WITH A BLEND DUE TO ATTENTION ON THE SHORT TERM. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * ISOLATED SHOWERS/ VCTS EARLY THIS MORNING. * CIG TRENDS WITH LOW MVFR CIGS DOWN AROUND 1500 FEET EARLY THIS MORNING. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MID TO LATE MORNING HOURS. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS...ESPECIALLY THROUGH MID MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A RATHER COMPLICATED CIG AND VIS FORECAST OVERNIGHT...AS AREAS WHERE THE CLOUDS ARE DISSIPATING LOWER CLOUDS AND FOG ARE DEVELOPING. CURRENT THINKING IS THAT IT MAY TAKE A FEW MORE HOURS TO GET CIGS TO DROP BELOW 2000 FT AGL AT THE EASTERN TAF SITES...AND WITH MORE CLOUD COVER THE THREAT FOR FOG APPEARS LOW...ESPECIALLY AT ORD AND MDW. THE FOG THREAT IS A BIT UNCERTAIN AT DPA AND RFD AS LOW CIGS MAY BE THE RULE. HOWEVER...WITH VERY LOW DEW POINT DEPRESSIONS...IT WILL NOT TAKE MUCH TO GET THE VIS TO TANK. WITH THIS IN MIND...I DECIDED TO LEAVE THE TEMPO GROUPS FOR A PERIOD OF LOW VIS IN THE NEW TAF FORECAST AT RFD AND DPA. THERE HAVE AS BEEN A CONTINUED REDEVELOPMENT OF MAINLY SHOWERS ACROSS FAR NORTHERN ILLINOIS AS THE FLOW ALOFT REMAINS RATHER UNSETTLED. THIS WILL LIKELY CONTINUE TO BE THE CASE FOR THE NEXT FEW HOURS ACROSS THE AREA. I EXTENDED THE VCSH TO ACCOUNT FOR THESE SHOWERS. OVERALL THE THREAT FOR THUNDER WILL BE LOW...HOWEVER...THERE HAVE BEEN A FEW STRIKES IN THE CELL ACROSS STEPHENSON COUNTY. THIS CELL COULD APPROACH KRFD AFTER 07 UTC. CIGS LOOK TO BE SLOW TO INCREASE THIS MORNING...BUT ONCE THEY DO...THINGS SHOULD BE QUIET UNTIL TONIGHT. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. I DID ADD A MENTION OF SHRA AND VCTS TO THE ORD 30 HR TAF AFTER 08 UTC. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIRMASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN A BRIEF PERIOD OF SHOWERS THIS MORNING...WITH VCTS. * MEDIUM CONFIDENCE IN MVFR CIG/VIS CONDITIONS DEVELOPING FOR A PERIOD THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... WEDNESDAY...CHANCE TSRA MAINLY MORNING. OTHERWISE VFR. THURSDAY THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. RATZER && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
420 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURFACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTION ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCD SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVECTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPAGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE DCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. CONFIDENCE...MEDIUM. THE REST OF THE DISCUSSION WILL BE SENT SHORTLY. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * ISOLATED SHOWERS/ VCTS EARLY THIS MORNING. * CIG TRENDS WITH LOW MVFR CIGS DOWN AROUND 1500 FEET EARLY THIS MORNING. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MID TO LATE MORNING HOURS. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS...ESPECIALLY THROUGH MID MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A RATHER COMPLICATED CIG AND VIS FORECAST OVERNIGHT...AS AREAS WHERE THE CLOUDS ARE DISSIPATING LOWER CLOUDS AND FOG ARE DEVELOPING. CURRENT THINKING IS THAT IT MAY TAKE A FEW MORE HOURS TO GET CIGS TO DROP BELOW 2000 FT AGL AT THE EASTERN TAF SITES...AND WITH MORE CLOUD COVER THE THREAT FOR FOG APPEARS LOW...ESPECIALLY AT ORD AND MDW. THE FOG THREAT IS A BIT UNCERTAIN AT DPA AND RFD AS LOW CIGS MAY BE THE RULE. HOWEVER...WITH VERY LOW DEW POINT DEPRESSIONS...IT WILL NOT TAKE MUCH TO GET THE VIS TO TANK. WITH THIS IN MIND...I DECIDED TO LEAVE THE TEMPO GROUPS FOR A PERIOD OF LOW VIS IN THE NEW TAF FORECAST AT RFD AND DPA. THERE HAVE AS BEEN A CONTINUED REDEVELOPMENT OF MAINLY SHOWERS ACROSS FAR NORTHERN ILLINOIS AS THE FLOW ALOFT REMAINS RATHER UNSETTLED. THIS WILL LIKELY CONTINUE TO BE THE CASE FOR THE NEXT FEW HOURS ACROSS THE AREA. I EXTENDED THE VCSH TO ACCOUNT FOR THESE SHOWERS. OVERALL THE THREAT FOR THUNDER WILL BE LOW...HOWEVER...THERE HAVE BEEN A FEW STRIKES IN THE CELL ACROSS STEPHENSON COUNTY. THIS CELL COULD APPROACH KRFD AFTER 07 UTC. CIGS LOOK TO BE SLOW TO INCREASE THIS MORNING...BUT ONCE THEY DO...THINGS SHOULD BE QUIET UNTIL TONIGHT. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. I DID ADD A MENTION OF SHRA AND VCTS TO THE ORD 30 HR TAF AFTER 08 UTC. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIRMASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN A BRIEF PERIOD OF SHOWERS THIS MORNING...WITH VCTS. * MEDIUM CONFIDENCE IN MVFR CIG/VIS CONDITIONS DEVELOPING FOR A PERIOD THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... WEDNESDAY...CHANCE TSRA MAINLY MORNING. OTHERWISE VFR. THURSDAY THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. RATZER && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
343 AM CDT TUE AUG 6 2013 .DISCUSSION... 340 AM CDT THERE ARE MULTIPLE FORECAST CHALLENGES THIS MORNING...WITH SEVERAL OF THOSE TIED TO THUNDER CHANCES ASSOCIATED WITH A COOL FRONTAL ARRIVAL TONIGHT INTO WEDNESDAY MORNING AND THEN ITS SLOW DEPARTURE FROM THE REGION THURSDAY INTO FRIDAY...WITH CHANCES THEN MAINLY ACROSS THE SOUTH. OF COURSE IN AND AROUND FRONTAL SYSTEMS TEMPERATURES ALWAYS OFFER AN EXCITING CHALLENGE AS WELL. SYNOPSIS...THE PREVALENT UPPER RIDGE ACROSS THE SOUTHERN U.S. WILL CONTINUE ITS GRADUAL DAMPENING TREND IN RESPONSE TO AN UPPER TROUGH ADVANCING SOUTH ACROSS CENTRAL AND SOUTH CENTRAL CANADA. A PERSISTENT 90KT+ NORTHWESTERLY JET BETWEEN THESE UPPER FEATURES STRETCHES OVER THE FORECAST AREA WITH SMALL SCALE IMPULSES NOTED IN THIS FLOW AND RESPONSIBLE FOR SOME OF THE EARLY MORNING STORMS AS OF 330 AM. THE SURFACE MAP ACROSS THE MIDWEST THIS MORNING IS CHARACTERIZED BY ONLY A 2MB PRESSURE GRADIENT FROM HERE THROUGH THE CENTRAL PLAINS...WITH AN ELONGATED AND BAGGY SURACE TROUGH FROM MN THROUGH OK. THIS TROUGH WILL SHARPEN UP INTO A COOL FRONT BY LATE THIS AFTERNOON AS CYCLOGENESIS OCCURS ACROSS THE UPPER MIDWEST UNDER FORCING OF THE UPPER TROUGH. THE PARENT SURFACE LOW LOOKS TO REACH ITS DEEPEST PRESSURE /~1003MB/ THIS EVE AS IT NEARS LAKE SUPERIOR AND THEN MOVE NORTHEAST. INITIALLY THIS WILL BRING A COOL FRONT INTO THE AREA. AS THE FRONT STRETCHES OUT WITH THE LOW MOVING AWAY THE FORWARD MOMENTUM IS EXPECTED TO SLOW LATER WEDNESDAY WITH THE BOUNDARY STALLING NEAR OR NOT FAR NORTH OF THE OHIO VALLEY THU AND FRI. A SECONDARY COOL FRONT WILL USHER THIS BOUNDARY FURTHER SOUTH COME LATER FRI. THIS MORNING...SCATTERED CONVECTION HAS HELD ITS OWN NEAR ROCKFORD ASSOCIATED WITH A MID-LEVEL SPEED MAX AND SHEARED SHORT WAVE...ALONG WITH SUBTLE 850-925MB CONVERGENCE ON 20-25KT SW/WSW LLJ FLOW. ITS TOUGH TO SAY HOW LONG THIS ACTIVITY WILL LAST AS THE FORCING IS WEAK AND ITS ALREADY PERSISTED LONGER THAN INITIALLY THOUGHT. GIVEN THAT ITS TIED IN PART TO THE LLJ THIS SHOULD EASE IN COVERAGE AS IT NEARS OR MOVES INTO THE CHICAGO METRO AREA FROM 6-9 AM. SOME OF THIS HAS BEEN FAIRLY EFFICIENT AT RAIN PRODUCTION WITH SOME ESTIMATES ON RADAR OF OVER AN INCH IN WINNEBAGO COUNTY. AMDAR DATA INDICATES THE CLOUDS APART FROM THE CONVECTINO ARE OF AROUND 2000-4000 FT THICK...WITH FLIGHTS OUT OF CHICAGO NEAR THE DEEPER END. THIS WILL LIKELY TAKE SEVERAL HOURS TO PEEL AWAY INTO A CU LAYER...SO A SLOW TEMPERATURE CLIMB SHOULD INITIALLY BE SEEN. CONFIDENCE...LOW/MEDIUM. THIS AFTERNOON...SHORT WAVE RIDGING IS EXPECTED TO MOVE OVER THE AREA DURING THIS TIME OFFERING LIMITED FORCING FOR RAIN DESPITE BUILDING INSTABILITY IN THE SOUTHERLY FLOW SLOWLY MOVING IN. THERE SHOULD BE SOME SUNSHINE AND ABOVE NORMAL 850MB AND 925MB TEMPERATURES WOULD SUPPORT MEDIAN READINGS NEAR THE UPPER 80S IN OUR AREA BASED ON LOCAL RESEARCH. HAVE MID TO UPPER 80S FORECAST FOR MUCH OF THE AREA...WITH LOWER 80S IMMEDIATELY ALONG THE IL LAKE SHORE. THIS IS SUPPORTED BY THE RAP MODEL RUN...WHICH IS ONE OF THE WARMEST GUIDANCE YET HAS A VERY SLOW TEMPERATURE CLIMB THROUGH 9-10 AM...COINCIDENT WITH OUR FORECAST CLOUD COVER WHICH ADDS CREDIBIILITY TO ITS SOLUTION. CONFIDENCE...MEDIUM. TONIGHT INTO WEDNESDAY MORNING...THIS IS THE PERIOD THAT HAS THE BEST POTENTIAL FOR STORMS...ESPECIALLY LATE TONIGHT. THE SUITE OF MODEL GUIDANCE HAS BEEN IN SOLID AGREEMENT THE PAST 24 HOURS OF CONVECTION DEVELOPING UPSTREAM ACROSS IA AND SOUTHERN MN THIS EVE AS HEIGHT FALLS OVERSPREAD THE DEVELOPING COOL FRONT. A PRONOUNCD SHORT WAVE ACROSS MT EARLY THIS MORNING SEEMS TO CORRELATE WELL WITH MOVING OVER THAT REGION DURING EARLY EVE. AS CONVECTION LIKELY DEVELOPS IT IS ANTICIPATED TO MOVE EAST SOUTHEAST WITHIN THE FAST PACED WESTERLY FLOW...WITH SEVERAL CONVECTIVE ALLOWING MODELS PAINTING ORGANIZED/MCS CONVECTION. THIS SHOULD BE ABLE TO FEED ON MODESTLY UNSTABLE AND VERY MOIST AIR FEEDING NORTHWARD. PWATS HAVE BEEN 2 INCHES OR HIGHER FOR MULTIPLE DAYS UP TO SOUTHERN MO AND SOUTHEAST KS AND SOME OF THAT AIR MASS /PWATS ~1.75 IN./ WILL BE BROUGHT UP INTO OUR REGION ON 30KT OF 700-925MB MOISTURE TRANSPORT. ITS POSSIBLE FOR SCATTERED ELEVATED CONVECTION WITHIN THIS INCREASING MOIST FLOW AHEAD OF THE MAIN CONVERGENCE...BUT THE MAIN FOCUS STILL LOOKS TO BE OVERNIGHT. THE MAIN UNCERTAINTY IS IF THE CONVECTION CAN HOLD ITS OWN THROUGH THE OVERNIGHT OR WILL IT SHOW A WEAKENING TREND...ESPECIALLY IF MORE CONVECTION DEVELOPS SOUTH OF THE AREA IN MO AND SOUTHWEST IL ROBBING OUR MOIST RETURN. HAVE STILL GONE AHEAD AND BOOSTED QPF VALUES ACROSS THE WESTERN HALF OF THE AREA FROM WHAT WPC HAD AS LOCALIZED HIGHER AMOUNTS ARE FAVORED IN THE REGION...ESPECIALLY IF CONVCTION IS ORGANIZED. THE FLASH FLOOD THREAT WILL PROBABLY BE LIMITED WITH PROPOGATION OF THE HEAVIEST RAIN LIKELY TO BE QUICK ENOUGH AND ANTECEDENT CONDITIONS NOT TOO BAD OFF WITH RECENT DRYNESS. THIS WESTERN PART OF THE CWA IS ALSO THE PORTION WHERE IF ANY STORMS ARE ABLE TO REACH A SEVERE THRESHHOLD THE THREAT WOULD BE A LITTLE MORE FAVORED...NAMELY A WIND THREAT WITH APPRECIABLE DCAPE VALUES FORECAST BY THE NAM AND GFS /800-1200 J/KG/ AND POSSIBLE COLD POOL PROPAGATION. THE THREAT FOR SEVERE WEATHER THOUGH STILL APPEARS LOW. CONFIDENCE...MEDIUM. THE REST OF THE DISCUSSION WILL BE SENT SHORTLY. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * ISOLATED SHOWERS EARLY THIS MORNING. * CIG TRENDS WITH MVFR CIGS DOWN AROUND 1500 FEET BY DAYBREAK. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MORNING. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS...ESPECIALLY THROUGH MID MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A RATHER COMPLICATED CIG AND VIS FORECAST OVERNIGHT...AS AREAS WHERE THE CLOUDS ARE DISSIPATING LOWER CLOUDS AND FOG ARE DEVELOPING. CURRENT THINKING IS THAT IT MAY TAKE A FEW MORE HOURS TO GET CIGS TO DROP BELOW 2000 FT AGL AT THE EASTERN TAF SITES...AND WITH MORE CLOUD COVER THE THREAT FOR FOG APPEARS LOW...ESPECIALLY AT ORD AND MDW. THE FOG THREAT IS A BIT UNCERTAIN AT DPA AND RFD AS LOW CIGS MAY BE THE RULE. HOWEVER...WITH VERY LOW DEW POINT DEPRESSIONS...IT WILL NOT TAKE MUCH TO GET THE VIS TO TANK. WITH THIS IN MIND...I DECIDED TO LEAVE THE TEMPO GROUPS FOR A PERIOD OF LOW VIS IN THE NEW TAF FORECAST AT RFD AND DPA. THERE HAVE AS BEEN A CONTINUED REDEVELOPMENT OF MAINLY SHOWERS ACROSS FAR NORTHERN ILLINOIS AS THE FLOW ALOFT REMAINS RATHER UNSETTLED. THIS WILL LIKELY CONTINUE TO BE THE CASE FOR THE NEXT FEW HOURS ACROSS THE AREA. I EXTENDED THE VCSH TO ACCOUNT FOR THESE SHOWERS. OVERALL THE THREAT FOR THUNDER WILL BE LOW...HOWEVER...THERE HAVE BEEN A FEW STRIKES IN THE CELL ACROSS STEPHENSON COUNTY. THIS CELL COULD APPROACH KRFD AFTER 07 UTC. CIGS LOOK TO BE SLOW TO INCREASE THIS MORNING...BUT ONCE THEY DO...THINGS SHOULD BE QUIET UNTIL TONIGHT. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. I DID ADD A MENTION OF SHRA AND VCTS TO THE ORD 30 HR TAF AFTER 08 UTC. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIRMASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN MVFR CIG/VIS CONDITIONS DEVELOPING OVERNIGHT AND LINGERING THROUGH MID MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... WEDNESDAY...CHANCE TSRA MAINLY MORNING. OTHERWISE VFR. THURSDAY THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. RATZER && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
259 AM CDT TUE AUG 6 2013 .DISCUSSION... 755 PM CDT EVENING UPDATE: MADE TWEAKS TO EVENING GRIDS TO BACK OFF TO ISOLATED SHRA MENTION FOR APPROXIMATELY NORTHEASTERN HALF OF CWA. SHEARED OUT WAVE AND MID LEVEL SPEED MAX CONTINUES TO PUSH ACROSS REGION WITH SIGNIFICANT DRYING NOTED ON WATER VAPOR IN WAKE OF THIS WAVE. LATEST RAP MESOANALYSIS HAS SHOWN IN INCREASE IN ELEVATED CAPE BUT 00Z DVN RAOB INDICATES THAT THIS IS LIKELY OVERDONE WITH VERY MARGINAL INSTABILITY AND WEAK MID LEVEL LAPSE RATES ON THE SOUNDING. WITH THE FORCING FROM THE MIDLEVEL WAVE OVERHEAD...RETURNS OVER SOUTHWEST WISCONSIN HAVE INCREASED A BIT IN RECENT SCANS BUT GIVEN THAT INSTABILITY FURTHER DIMINISHES INTO OUR CWA...THIS ACTIVITY WILL LIKELY ONLY SURVIVE INTO CWA AS SPOTTY PRIMARILY LIGHT SHOWERS. AN OUTSIDE CHANCE EXISTS FOR AN ISOLATED T-STORM. THEN WENT WITH A DRY FORECAST AFTER MIDNIGHT FOR ENTIRE AREA AS FORCING FROM VORT MAX WILL TRANSLATE EAST OF US BY ABOUT MIDNIGHT. ATTENTION WILL THEN TURN TO FOG POTENTIAL OVERNIGHT AS AIR MASS REMAINS MOIST AND WINDS WILL CONTINUE TO DIMINISH. UNCERTAINTY AS TO WHETHER STRATUS OR FOG IS THE PRIMARY MODE BUT IF BETTER CLEARING CAN OCCUR...FOG WOULD BECOME MORE FAVORABLE AND EVEN POTENTIALLY BECOME LOCALLY DENSE. OBS OVER SW WISCONSIN SHOW VSBY BETWEEN 2 AND 4 MILES AND LATEST GUIDANCE STILL SUPPORTS BEST CHANCE FOR MORE WIDESPREAD FOG TO DEVELOP WELL WEST OF THE LAKEFRONT SO WILL CONTINUE TO MONITOR OBSERVATIONAL TRENDS THIS EVENING AND MAKE FURTHER UPDATES IF NEEDED. UPDATED ZONE PRODUCT HAS BEEN SENT. RC //PREV DISCUSSION... 312 PM CDT A PREDOMINANTLY NORTHWESTERLY UPPER FLOW PATTERN WILL BE IN PLACE THROUGH THE PERIOD WITH OCCASIONAL BUCKLING TO A MORE WESTERLY DIRECTION OVER THE NEXT FEW DAYS. AS A RESULT...TIMING MODEST PRECIP CHANCES WILL BE THE MAIN CHALLENGE THROUGH LATE WEEK. WATER VAPOR IMAGERY SHOWS AN UPPER LOW CENTERED OVER SOUTHWESTERN PORTIONS OF HUDSON BAY WHILE A LARGE UPPER ANTICYCLONE SPINS OVER TEXAS. BETWEEN THE TWO...IS A BELT OF NORTHWESTERLY UPPER FLOW STRETCHED FROM THE NORTHERN U.S. ROCKIES TO THE SOUTHEAST COAST. A CLOSER LOOK AT SATELLITE SHOWS SEVERAL EMBEDDED SHORTWAVES WITHIN THIS FLOW...WITH ONE HAVING PASSED OVER THE AREA EARLIER TODAY WITH ANOTHER APPROACHING LATE THIS AFTERNOON. A LARGER SCALE TROUGH AXIS EXTENDS FROM THE HUDSON BAY LOW WEST-SOUTHWEST WHERE A SMALLER SCALE CIRCULATION IS NOTED OVER SOUTHERN ALBERTA. THIS WILL BE KEY IN OUR WEATHER TUESDAY NIGHT AND WEDNESDAY. FURTHER WEST...ANOTHER UPPER LOW IS CUTOFF OFF THE NORTHERN CALIFORNIA COAST AND MOVING VERY LITTLE AS A RESULT. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER EASTERN OHIO AND WESTERN PENNSYLVANIA WHILE A LOW IS CENTERED OVER NORTHERN ONTARIO. A TROUGH AXIS EXTENDS SOUTHWARD FROM THE LOW INTO EASTERN MINNESOTA AND IOWA. THIS EVENING THROUGH TUESDAY...A WEAK SHORTWAVE CONTINUES TO CROSS THE LOCAL AREA WITH A SMALL CLUSTER OF SHRA/TSRA WORKING EAST-SOUTHEAST ACROSS THE FAR NORTHWEST ILLINOIS BORDER. THIS LOOKS TO MAINTAIN ITSELF OVER THE NEXT FEW HOURS BUT LITTLE IF ANY LOW LEVEL INSTABILITY HAS DEVELOPED THANKS TO AN EXTENSIVE...BUT THINNING...CLOUD SHIELD. WHAT HAS DEVELOPED THOUGH SUGGESTS THAT THIS CLUSTER WILL WORK SOUTHEAST TOWARD ROCKFORD...ROCHELLE...AND ON INTO THE WESTERN/SOUTHWESTERN CHICAGO METRO IF IT MAINTAINS. IN ADDITION...SOME SPOTTY ACTIVITY MAY DEVELOP AROUND THIS CLUSTER INTO THE EVENING. A FEW STRONGER CORES HAVE POPPED UP FROM TIME TO TIME IN THE LAST FEW RADAR SCANS WITH THE ACTIVITY BUT WITH SUCH LIMITED INSTABILITY...THOUGH THERE IS STRONG SHEAR...MORE THAN AN ISOLATED HAIL CORE OR WIND GUST LOOKS UNLIKELY. CHANCES WILL DIMINISH THROUGH THE EVENING. THE AFOREMENTIONED TROUGH AXIS/COOL FRONT MOVING ACROSS MINNESOTA WILL CONTINUE EASTWARD BUT FALL APART WITH TIME OVERNIGHT. MID LEVEL DRYING IS EXPECTED OVERNIGHT AND WITH NO COHERENT SOURCE OF FORCING DO NOT SEE MUCH CHANCE FOR PRECIP BY LATE TONIGHT...IF NOT BEFORE THAT. THE AREA WILL BE BETWEEN SYSTEMS TUESDAY WHICH SHOULD LEAD TO DRY CONDITIONS THROUGH AT LEAST THE FIRST PART OF THE DAY BEFORE SMALL CHANCES INCREASE LATER IN THE DAY AS THE NEXT TROUGH APPROACHES. MORNING CLOUD COVER WILL BE THE WILD CARD FOR TEMPS AS IT MAY BE EXTENSIVE ALONG WITH SOME MORNING FOG...BUT A DECREASE IS EXPECTED THROUGH LATE MORNING...WITH SOME DIURNAL CU AND SOME APPROACHING CIRRUS FOR THE AFTERNOON. H85 TEMPS WILL BE QUITE WARM RELATIVE TO RECENT DAYS...WITH READINGS AROUND +16C. THIS COMBINED WITH EXPECTED INCREASE IN SUNSHINE DURING THE AFTERNOON...AND A MODEST SOUTH-SOUTHWEST WIND SHOULD ALLOW FOR HIGHS TO WARM INTO THE LOW TO MID 80S...WITH A FEW UPPER 80S POSSIBLE IF CLOUD COVER IS LESS THAN FORECAST. TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW OVER HUDSON BAY WILL RE-POSITION ITSELF ACROSS EASTERN MANITOBA TUESDAY WITH ANOTHER TROUGH AXIS ROTATING AROUND IT. THIS WILL PUSH ANOTHER WEAK COOL FRONT SOUTHEASTWARD ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI RIVER VALLEY INTO TUESDAY EVENING WHICH WILL THEN CROSS THE LOCAL AREA EARLY WEDNESDAY. THIS FRONT LOOKS TO BE BETTER ORGANIZED THAN THE ONE APPROACHING TONIGHT GIVEN THAT THE PARENT SFC LOW WILL BE FURTHER SOUTH AND BETTER ORGANIZED AS IT CROSSES THE UPPER LAKES AND CENTRAL ONTARIO. A MOIST AIRMASS WILL BE IN PLACE ACROSS THE AREA WITH PRECIPITABLE WATER VALUES RUNNING BETWEEN 1.4 AND 1.7 INCHES. IT APPEARS THAT THERE MAY BE SEVERAL SHORTWAVES THAT CROSS THE AREA FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING WITH THE MAIN FRONT NOT PASSING UNTIL WEDNESDAY MORNING. WILL MAINTAIN THE LOW END LIKELY POPS FROM THE PREVIOUS FORECAST BUT REFINE THE TIMING...WITH THE BETTER CHANCES STARTING TUESDAY NIGHT. A DRYING TREND IS EXPECTED WEDNESDAY AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD INTO THE AREA SHIFTING WINDS TO THE NORTH AND EAST. HIGHS MAY STILL BE RATHER MILD WEDNESDAY WITH LOW TO MID 80S...THANKS TO THE UPPER FLOW BEING ZONAL KEEPING MID LEVEL COOL ADVECTION AT A MINIMUM THROUGH THE AFTERNOON. HOWEVER...TEMPS NEAR THE LAKESHORE WILL LIKELY COOL AS WINDS TURN ONSHORE. THURSDAY THROUGH THE WEEKEND...THE FRONT WILL STALL OUT SOUTH OF THE AREA INTO EARLY THURSDAY WHILE HIGH PRESSURE MOVES OVERHEAD AND THEN SHIFTS TO THE EAST. MID LEVEL COOL ADVECTION WILL BE UNDERWAY INTO THURSDAY LEADING TO HIGHS BACK INTO THE MID TO UPPER 70S...WITH A FEW 80S SOUTH. COOLEST READINGS WILL BE ALONG THE LAKESHORE AS ONSHORE FLOW CONTINUES. ONE LAST TROUGH AXIS IS EXPECTED TO ROTATE AROUND THE UPPER LOW OVER MANITOBA/ONTARIO. GUIDANCE IS LESS CLEAR IN HOW THIS EVOLVES...WITH SOME SUGGESTION OF A STRONGER WAVE THANKS TO PHASING OF ENERGY BETWEEN THE MAIN UPPER LOW AND ENERGY OVERTOPPING A RIDGE ACROSS THE PACIFIC NORTHWEST. THIS WILL HAVE A BIG IMPACT ON LOCAL POPS LATER THURSDAY AND FRIDAY AS A STRONGER SYSTEM WOULD FORCE BETTER ORGANIZED SURFACE LOW/INVERTED TROUGH DEVELOPMENT ACROSS THE MID MISSISSIPPI RIVER VALLEY ALONG THE OLD FRONTAL BOUNDARY. THE STRONGER THE SURFACE LOW THE FURTHER NORTH THE OLD BOUNDARY WILL MOVE AND THE GREATER THE CHANCES FOR PRECIP ACROSS THE CWA. CONFIDENCE IS LOW GIVEN THAT THE UPPER FLOW PATTERN IS ACTIVE BETWEEN NOW AND THEN AND ITS EVOLUTION MAY BE AFFECTED. AT THE MOMENT IT APPEARS THAT THE BEST PRECIP CHANCES WILL BE SOUTH OF THE AREA LATER THURSDAY/FRIDAY...WITH ANOTHER SURFACE HIGH BUILDING IN INTO SATURDAY. HAVE BETTER CONFIDENCE IN THE MAIN UPPER LOW MOVING EASTWARD WHICH WILL ALLOW RIDGING TO BUILD WEST AND A MORE PRONOUNCED NORTHWEST FLOW ALOFT OF THE LOCAL AREA FOR THE WEEKEND. THIS WILL LIKELY RESULT IN HIGHS THAT CONTINUE TO BE SEVERAL DEGREES BELOW NORMAL. EXPECT DRY CONDITIONS SATURDAY BEFORE A SLIGHT INFLUX IN MOISTURE ARRIVES SUNDAY/MONDAY WITH THE UPPER FLOW LOOKING TO BECOME MORE ACTIVE. WILL LEAVE SUNDAY DRY FOR NOW. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * ISOLATED SHOWERS EARLY THIS MORNING. * CIG TRENDS WITH MVFR CIGS DOWN AROUND 1500 FEET BY DAYBREAK. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MORNING. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS...ESPECIALLY THROUGH MID MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A RATHER COMPLICATED CIG AND VIS FORECAST OVERNIGHT...AS AREAS WHERE THE CLOUDS ARE DISSIPATING LOWER CLOUDS AND FOG ARE DEVELOPING. CURRENT THINKING IS THAT IT MAY TAKE A FEW MORE HOURS TO GET CIGS TO DROP BELOW 2000 FT AGL AT THE EASTERN TAF SITES...AND WITH MORE CLOUD COVER THE THREAT FOR FOG APPEARS LOW...ESPECIALLY AT ORD AND MDW. THE FOG THREAT IS A BIT UNCERTAIN AT DPA AND RFD AS LOW CIGS MAY BE THE RULE. HOWEVER...WITH VERY LOW DEW POINT DEPRESSIONS...IT WILL NOT TAKE MUCH TO GET THE VIS TO TANK. WITH THIS IN MIND...I DECIDED TO LEAVE THE TEMPO GROUPS FOR A PERIOD OF LOW VIS IN THE NEW TAF FORECAST AT RFD AND DPA. THERE HAVE AS BEEN A CONTINUED REDEVELOPMENT OF MAINLY SHOWERS ACROSS FAR NORTHERN ILLINOIS AS THE FLOW ALOFT REMAINS RATHER UNSETTLED. THIS WILL LIKELY CONTINUE TO BE THE CASE FOR THE NEXT FEW HOURS ACROSS THE AREA. I EXTENDED THE VCSH TO ACCOUNT FOR THESE SHOWERS. OVERALL THE THREAT FOR THUNDER WILL BE LOW...HOWEVER...THERE HAVE BEEN A FEW STRIKES IN THE CELL ACROSS STEPHENSON COUNTY. THIS CELL COULD APPROACH KRFD AFTER 07 UTC. CIGS LOOK TO BE SLOW TO INCREASE THIS MORNING...BUT ONCE THEY DO...THINGS SHOULD BE QUIET UNTIL TONIGHT. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. I DID ADD A MENTION OF SHRA AND VCTS TO THE ORD 30 HR TAF AFTER 08 UTC. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIRMASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN MVFR CIG/VIS CONDITIONS DEVELOPING OVERNIGHT AND LINGERING THROUGH MID MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... WEDNESDAY...CHANCE TSRA MAINLY MORNING. OTHERWISE VFR. THURSDAY THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. RATZER && .MARINE... 258 AM CDT SOUTHERLY FLOW IN THE 10 TO 20 KT RANGE WILL CONTINUE TODAY AND TONIGHT AS A TROUGH OF SURFACE LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA. IT APPEARS THAT THUNDERSTORMS WILL BECOME LIKELY TONIGHT AHEAD OF THE COLD FRONT...WHICH SHOULD MOVE ACROSS THE LAKE ON WEDNESDAY MORNING. ONCE THIS FRONT PASSES...THE WINDS WILL BECOME NORTHERLY BY LATE WEDNESDAY...AND COULD PICK UP TO 15 TO 20 KT FOR A PERIOD AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. THE SURFACE HIGH SHOULD SET UP OVER LAKE MICHIGAN FOR THURSDAY...AND THIS SHOULD RESULT IN ABATING WINDS INTO THURSDAY. KJB && .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
133 AM CDT TUE AUG 6 2013 .DISCUSSION... 755 PM CDT EVENING UPDATE: MADE TWEAKS TO EVENING GRIDS TO BACK OFF TO ISOLATED SHRA MENTION FOR APPROXIMATELY NORTHEASTERN HALF OF CWA. SHEARED OUT WAVE AND MID LEVEL SPEED MAX CONTINUES TO PUSH ACROSS REGION WITH SIGNIFICANT DRYING NOTED ON WATER VAPOR IN WAKE OF THIS WAVE. LATEST RAP MESOANALYSIS HAS SHOWN IN INCREASE IN ELEVATED CAPE BUT 00Z DVN RAOB INDICATES THAT THIS IS LIKELY OVERDONE WITH VERY MARGINAL INSTABILITY AND WEAK MID LEVEL LAPSE RATES ON THE SOUNDING. WITH THE FORCING FROM THE MIDLEVEL WAVE OVERHEAD...RETURNS OVER SOUTHWEST WISCONSIN HAVE INCREASED A BIT IN RECENT SCANS BUT GIVEN THAT INSTABILITY FURTHER DIMINISHES INTO OUR CWA...THIS ACTIVITY WILL LIKELY ONLY SURVIVE INTO CWA AS SPOTTY PRIMARILY LIGHT SHOWERS. AN OUTSIDE CHANCE EXISTS FOR AN ISOLATED T-STORM. THEN WENT WITH A DRY FORECAST AFTER MIDNIGHT FOR ENTIRE AREA AS FORCING FROM VORT MAX WILL TRANSLATE EAST OF US BY ABOUT MIDNIGHT. ATTENTION WILL THEN TURN TO FOG POTENTIAL OVERNIGHT AS AIR MASS REMAINS MOIST AND WINDS WILL CONTINUE TO DIMINISH. UNCERTAINTY AS TO WHETHER STRATUS OR FOG IS THE PRIMARY MODE BUT IF BETTER CLEARING CAN OCCUR...FOG WOULD BECOME MORE FAVORABLE AND EVEN POTENTIALLY BECOME LOCALLY DENSE. OBS OVER SW WISCONSIN SHOW VSBY BETWEEN 2 AND 4 MILES AND LATEST GUIDANCE STILL SUPPORTS BEST CHANCE FOR MORE WIDESPREAD FOG TO DEVELOP WELL WEST OF THE LAKEFRONT SO WILL CONTINUE TO MONITOR OBSERVATIONAL TRENDS THIS EVENING AND MAKE FURTHER UPDATES IF NEEDED. UPDATED ZONE PRODUCT HAS BEEN SENT. RC //PREV DISCUSSION... 312 PM CDT A PREDOMINANTLY NORTHWESTERLY UPPER FLOW PATTERN WILL BE IN PLACE THROUGH THE PERIOD WITH OCCASIONAL BUCKLING TO A MORE WESTERLY DIRECTION OVER THE NEXT FEW DAYS. AS A RESULT...TIMING MODEST PRECIP CHANCES WILL BE THE MAIN CHALLENGE THROUGH LATE WEEK. WATER VAPOR IMAGERY SHOWS AN UPPER LOW CENTERED OVER SOUTHWESTERN PORTIONS OF HUDSON BAY WHILE A LARGE UPPER ANTICYCLONE SPINS OVER TEXAS. BETWEEN THE TWO...IS A BELT OF NORTHWESTERLY UPPER FLOW STRETCHED FROM THE NORTHERN U.S. ROCKIES TO THE SOUTHEAST COAST. A CLOSER LOOK AT SATELLITE SHOWS SEVERAL EMBEDDED SHORTWAVES WITHIN THIS FLOW...WITH ONE HAVING PASSED OVER THE AREA EARLIER TODAY WITH ANOTHER APPROACHING LATE THIS AFTERNOON. A LARGER SCALE TROUGH AXIS EXTENDS FROM THE HUDSON BAY LOW WEST-SOUTHWEST WHERE A SMALLER SCALE CIRCULATION IS NOTED OVER SOUTHERN ALBERTA. THIS WILL BE KEY IN OUR WEATHER TUESDAY NIGHT AND WEDNESDAY. FURTHER WEST...ANOTHER UPPER LOW IS CUTOFF OFF THE NORTHERN CALIFORNIA COAST AND MOVING VERY LITTLE AS A RESULT. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER EASTERN OHIO AND WESTERN PENNSYLVANIA WHILE A LOW IS CENTERED OVER NORTHERN ONTARIO. A TROUGH AXIS EXTENDS SOUTHWARD FROM THE LOW INTO EASTERN MINNESOTA AND IOWA. THIS EVENING THROUGH TUESDAY...A WEAK SHORTWAVE CONTINUES TO CROSS THE LOCAL AREA WITH A SMALL CLUSTER OF SHRA/TSRA WORKING EAST-SOUTHEAST ACROSS THE FAR NORTHWEST ILLINOIS BORDER. THIS LOOKS TO MAINTAIN ITSELF OVER THE NEXT FEW HOURS BUT LITTLE IF ANY LOW LEVEL INSTABILITY HAS DEVELOPED THANKS TO AN EXTENSIVE...BUT THINNING...CLOUD SHIELD. WHAT HAS DEVELOPED THOUGH SUGGESTS THAT THIS CLUSTER WILL WORK SOUTHEAST TOWARD ROCKFORD...ROCHELLE...AND ON INTO THE WESTERN/SOUTHWESTERN CHICAGO METRO IF IT MAINTAINS. IN ADDITION...SOME SPOTTY ACTIVITY MAY DEVELOP AROUND THIS CLUSTER INTO THE EVENING. A FEW STRONGER CORES HAVE POPPED UP FROM TIME TO TIME IN THE LAST FEW RADAR SCANS WITH THE ACTIVITY BUT WITH SUCH LIMITED INSTABILITY...THOUGH THERE IS STRONG SHEAR...MORE THAN AN ISOLATED HAIL CORE OR WIND GUST LOOKS UNLIKELY. CHANCES WILL DIMINISH THROUGH THE EVENING. THE AFOREMENTIONED TROUGH AXIS/COOL FRONT MOVING ACROSS MINNESOTA WILL CONTINUE EASTWARD BUT FALL APART WITH TIME OVERNIGHT. MID LEVEL DRYING IS EXPECTED OVERNIGHT AND WITH NO COHERENT SOURCE OF FORCING DO NOT SEE MUCH CHANCE FOR PRECIP BY LATE TONIGHT...IF NOT BEFORE THAT. THE AREA WILL BE BETWEEN SYSTEMS TUESDAY WHICH SHOULD LEAD TO DRY CONDITIONS THROUGH AT LEAST THE FIRST PART OF THE DAY BEFORE SMALL CHANCES INCREASE LATER IN THE DAY AS THE NEXT TROUGH APPROACHES. MORNING CLOUD COVER WILL BE THE WILD CARD FOR TEMPS AS IT MAY BE EXTENSIVE ALONG WITH SOME MORNING FOG...BUT A DECREASE IS EXPECTED THROUGH LATE MORNING...WITH SOME DIURNAL CU AND SOME APPROACHING CIRRUS FOR THE AFTERNOON. H85 TEMPS WILL BE QUITE WARM RELATIVE TO RECENT DAYS...WITH READINGS AROUND +16C. THIS COMBINED WITH EXPECTED INCREASE IN SUNSHINE DURING THE AFTERNOON...AND A MODEST SOUTH-SOUTHWEST WIND SHOULD ALLOW FOR HIGHS TO WARM INTO THE LOW TO MID 80S...WITH A FEW UPPER 80S POSSIBLE IF CLOUD COVER IS LESS THAN FORECAST. TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW OVER HUDSON BAY WILL RE-POSITION ITSELF ACROSS EASTERN MANITOBA TUESDAY WITH ANOTHER TROUGH AXIS ROTATING AROUND IT. THIS WILL PUSH ANOTHER WEAK COOL FRONT SOUTHEASTWARD ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI RIVER VALLEY INTO TUESDAY EVENING WHICH WILL THEN CROSS THE LOCAL AREA EARLY WEDNESDAY. THIS FRONT LOOKS TO BE BETTER ORGANIZED THAN THE ONE APPROACHING TONIGHT GIVEN THAT THE PARENT SFC LOW WILL BE FURTHER SOUTH AND BETTER ORGANIZED AS IT CROSSES THE UPPER LAKES AND CENTRAL ONTARIO. A MOIST AIRMASS WILL BE IN PLACE ACROSS THE AREA WITH PRECIPITABLE WATER VALUES RUNNING BETWEEN 1.4 AND 1.7 INCHES. IT APPEARS THAT THERE MAY BE SEVERAL SHORTWAVES THAT CROSS THE AREA FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING WITH THE MAIN FRONT NOT PASSING UNTIL WEDNESDAY MORNING. WILL MAINTAIN THE LOW END LIKELY POPS FROM THE PREVIOUS FORECAST BUT REFINE THE TIMING...WITH THE BETTER CHANCES STARTING TUESDAY NIGHT. A DRYING TREND IS EXPECTED WEDNESDAY AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD INTO THE AREA SHIFTING WINDS TO THE NORTH AND EAST. HIGHS MAY STILL BE RATHER MILD WEDNESDAY WITH LOW TO MID 80S...THANKS TO THE UPPER FLOW BEING ZONAL KEEPING MID LEVEL COOL ADVECTION AT A MINIMUM THROUGH THE AFTERNOON. HOWEVER...TEMPS NEAR THE LAKESHORE WILL LIKELY COOL AS WINDS TURN ONSHORE. THURSDAY THROUGH THE WEEKEND...THE FRONT WILL STALL OUT SOUTH OF THE AREA INTO EARLY THURSDAY WHILE HIGH PRESSURE MOVES OVERHEAD AND THEN SHIFTS TO THE EAST. MID LEVEL COOL ADVECTION WILL BE UNDERWAY INTO THURSDAY LEADING TO HIGHS BACK INTO THE MID TO UPPER 70S...WITH A FEW 80S SOUTH. COOLEST READINGS WILL BE ALONG THE LAKESHORE AS ONSHORE FLOW CONTINUES. ONE LAST TROUGH AXIS IS EXPECTED TO ROTATE AROUND THE UPPER LOW OVER MANITOBA/ONTARIO. GUIDANCE IS LESS CLEAR IN HOW THIS EVOLVES...WITH SOME SUGGESTION OF A STRONGER WAVE THANKS TO PHASING OF ENERGY BETWEEN THE MAIN UPPER LOW AND ENERGY OVERTOPPING A RIDGE ACROSS THE PACIFIC NORTHWEST. THIS WILL HAVE A BIG IMPACT ON LOCAL POPS LATER THURSDAY AND FRIDAY AS A STRONGER SYSTEM WOULD FORCE BETTER ORGANIZED SURFACE LOW/INVERTED TROUGH DEVELOPMENT ACROSS THE MID MISSISSIPPI RIVER VALLEY ALONG THE OLD FRONTAL BOUNDARY. THE STRONGER THE SURFACE LOW THE FURTHER NORTH THE OLD BOUNDARY WILL MOVE AND THE GREATER THE CHANCES FOR PRECIP ACROSS THE CWA. CONFIDENCE IS LOW GIVEN THAT THE UPPER FLOW PATTERN IS ACTIVE BETWEEN NOW AND THEN AND ITS EVOLUTION MAY BE AFFECTED. AT THE MOMENT IT APPEARS THAT THE BEST PRECIP CHANCES WILL BE SOUTH OF THE AREA LATER THURSDAY/FRIDAY...WITH ANOTHER SURFACE HIGH BUILDING IN INTO SATURDAY. HAVE BETTER CONFIDENCE IN THE MAIN UPPER LOW MOVING EASTWARD WHICH WILL ALLOW RIDGING TO BUILD WEST AND A MORE PRONOUNCED NORTHWEST FLOW ALOFT OF THE LOCAL AREA FOR THE WEEKEND. THIS WILL LIKELY RESULT IN HIGHS THAT CONTINUE TO BE SEVERAL DEGREES BELOW NORMAL. EXPECT DRY CONDITIONS SATURDAY BEFORE A SLIGHT INFLUX IN MOISTURE ARRIVES SUNDAY/MONDAY WITH THE UPPER FLOW LOOKING TO BECOME MORE ACTIVE. WILL LEAVE SUNDAY DRY FOR NOW. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * ISOLATED SHOWERS EARLY THIS MORNING. * CIG TRENDS WITH MVFR CIGS DOWN AROUND 1500 FEET BY DAYBREAK. * TIMING THE IMPROVEMENT OF THESE LOWER CIGS DURING THE MORNING. * GOOD CHANCE OF TSRA TUESDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE PRIMARY FORECAST CONCERNS IN THE NEAR TERM WILL BE CIGS AND VIS...ESPECIALLY THROUGH MID MORNING. ATTENTION THEN TURNS TO LATER TONIGHT INTO WEDNESDAY MORNING WITH OUR NEXT CHANCE FOR TSRA. ABUNDANT LOW LEVEL MOISTURE ACROSS THE AREA IS CREATING A RATHER COMPLICATED CIG AND VIS FORECAST OVERNIGHT...AS AREAS WHERE THE CLOUDS ARE DISSIPATING LOWER CLOUDS AND FOG ARE DEVELOPING. CURRENT THINKING IS THAT IT MAY TAKE A FEW MORE HOURS TO GET CIGS TO DROP BELOW 2000 FT AGL AT THE EASTERN TAF SITES...AND WITH MORE CLOUD COVER THE THREAT FOR FOG APPEARS LOW...ESPECIALLY AT ORD AND MDW. THE FOG THREAT IS A BIT UNCERTAIN AT DPA AND RFD AS LOW CIGS MAY BE THE RULE. HOWEVER...WITH VERY LOW DEW POINT DEPRESSIONS...IT WILL NOT TAKE MUCH TO GET THE VIS TO TANK. WITH THIS IN MIND...I DECIDED TO LEAVE THE TEMPO GROUPS FOR A PERIOD OF LOW VIS IN THE NEW TAF FORECAST AT RFD AND DPA. THERE HAVE AS BEEN A CONTINUED REDEVELOPMENT OF MAINLY SHOWERS ACROSS FAR NORTHERN ILLINOIS AS THE FLOW ALOFT REMAINS RATHER UNSETTLED. THIS WILL LIKELY CONTINUE TO BE THE CASE FOR THE NEXT FEW HOURS ACROSS THE AREA. I EXTENDED THE VCSH TO ACCOUNT FOR THESE SHOWERS. OVERALL THE THREAT FOR THUNDER WILL BE LOW...HOWEVER...THERE HAVE BEEN A FEW STRIKES IN THE CELL ACROSS STEPHENSON COUNTY. THIS CELL COULD APPROACH KRFD AFTER 07 UTC. CIGS LOOK TO BE SLOW TO INCREASE THIS MORNING...BUT ONCE THEY DO...THINGS SHOULD BE QUIET UNTIL TONIGHT. IT APPEARS LIKELY THAT A COMPLEX OF THUNDERSTORMS WILL DEVELOP WEST OF THE AREA ACROSS IOWA AND SOUTHWESTERN WISCONSIN DURING THE EVENING TODAY. THIS ACTIVITY APPEARS THAT IT WILL MOVE OVER NORTHERN ILLINOIS LATER TONIGHT...LIKELY AFTER 06 UTC...ESPECIALLY AT THE EASTERN TAF SITS. I DID ADD A MENTION OF SHRA AND VCTS TO THE ORD 30 HR TAF AFTER 08 UTC. IT IS POSSIBLE THAT ACTIVITY COULD IMPACT THE TERMINAL A FEW HOURS PRIOR TO 08 UTC...HOWEVER...THE BEST TIMING APPEARS TO BE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A SURFACE FRONTAL ZONE APPROACHES THE AREA. DUE TO THE HIGH MOISTURE CONTENT EXPECTED IN THE AIRMASS AHEAD OF THIS FRONT...A PERIOD OF HEAVY RAINFALL IS PROBABLE...WHICH COULD REDUCE THE VIS DOWN UNDER 2 MILES FOR BRIEF PERIODS. THERE IS ALSO A SMALL RISK OF SOME STRONG WINDS WITH SOME OF THE STORMS...ESPECIALLY OUT BY RFD. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN MVFR CIG/VIS CONDITIONS DEVELOPING OVERNIGHT AND LINGERING THROUGH MID MORNING. * MEDIUM TO HIGH CONFIDENCE IN THUNDERSTORMS LATER TUESDAY NIGHT...WITH ONLY LOW TO MEDIUM CONFIDENCE ON THE EXACT TIMING. KJB //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... WEDNESDAY...CHANCE TSRA MAINLY MORNING. OTHERWISE VFR. THURSDAY THROUGH SUNDAY...VFR. SLIGHT CHANCE TSRA MAINLY SOUTH OF CHICAGO THURSDAY NIGHT. RATZER && .MARINE... 240 PM...A BROAD WEAK TROUGH EXTENDING ACROSS THE PLAINS FROM A SLIGHTLY STRONGER LOW OVER ONTARIO WILL SLOWLY MOVE EAST ACROSS THE WESTERN LAKES WEDNESDAY...WITH THE LOW OVER ONTARIO SLOWLY MOVING EAST THROUGH MID WEEK. AHEAD OF THIS TROUGH...SOUTHERLY WINDS HAVE INCREASED TO 10-20 KT AND FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR SOME WINDS INTO THE 15-25 KT RANGE THIS EVENING BEFORE SLOWLY DIMINISHING OVERNIGHT. ONCE THE TROUGH/COLD FRONT MOVES ACROSS THE LAKE MIDDAY WEDNESDAY...WINDS WILL SHIFT NORTHERLY WITH A PERIOD OF 10-20 KTS POSSIBLE BUT APPEARS THAT WOULD BE SHORT LIVED AS HIGH PRESSURE SPREADS ACROSS THE LAKES REGION WEDNESDAY NIGHT INTO THURSDAY. THE LOW OVER ONTARIO FINALLY SHIFTS EAST INTO QUEBEC ON FRIDAY...WITH A WEAK COLD FRONT MOVING ACROSS THE WESTERN LAKES FRIDAY NIGHT SHIFTING WINDS BACK NORTHERLY INTO SATURDAY WITH ANOTHER HIGH MOVING ACROSS THE LAKES SATURDAY NIGHT INTO SUNDAY. CMS && .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 INDIANAPOLIS IN
224 PM EDT TUE AUG 6 2013 .UPDATE... THE LONG TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 243 AM EDT TUE AUG 6 2013 WARMER AIR IS SET TO ARRIVE IN INDIANA TODAY AS HIGH PRESSURE OVER THE EAST COAST PROVIDES A WARMER AND MORE HUMID SOUTHERLY FLOW ALONG WITH DRY WEATHER. A MORE ACTIVE WEATHER PATTERN WILL TAKE SHAPE THROUGH THE MIDDLE OF THE WEEK AS A COLD FRONT IS EXPECTED TO PUSH TOWARD INDIANA LATE TONIGHT AND STALL ACROSS SOUTHERN INDIANA THROUGH THURSDAY THE FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS FROM LATE TONIGHT THROUGH FRIDAY. HIGH PRESSURE IS EXPECTED TO ARRIVE LATE FRIDAY AND BRING A RETURN TO DRY WEATHER FOR THE WEEKEND. && .NEAR TERM /REST OF TODAY/... ISSUED AT 944 AM EDT TUE AUG 6 2013 BUMPED UP CLOUD COVER THIS MORNING DUE TO SATELLITE TRENDS AS LOW DECK HAS BEEN OVERSPREADING THE AREA. LOOKS LIKE IT WILL TAKE A BIT LONGER TO SCATTER OUT AND THUS TRENDED MOSTLY CLOUDY TO LAST THROUGH MID AFTERNOON FOR MOST OF THE AREA. WITH THIS INCREASE IN CLOUD COVER HAVE ALSO LOWER HIGH TEMPERATURES FOR THE DAY...ONLY BY A DEGREE OR SO IN THE NORTH AND CENTRAL BUT BY A FEW DEGREES IN THE SOUTHWEST SINCE DEBRIS CLOUDS WILL LIKELY KEEP THAT AREA MOSTLY CLOUDY THROUGH MUCH OF THE DAY. RAP SHOWS SOME ISOLATED TO SCATTERED CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON BUT OTHER MODELS STILL LOOK DRY. WITH SOME SUBSIDENCE AND DRY AIR ALOFT AND THE RAP ALSO SHOWING SOME THINGS NOW THAT ARE NOT OCCURRING WILL CONTINUE WITH DRY FORECAST THROUGH THE DAY. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 243 AM EDT TUE AUG 6 2013 MAIN FOCUS DURING THIS PERIOD WILL BE POPS. MODELS ARE IN PRETTY GOOD AGREEMENT OF THE OVERALL TREND OF A WET...ACTIVE PATTERN. GFS AND NAM BOTH SUGGEST THE FIRST SHORT WAVE ARRIVING IN THE AREA LATE TONIGHT AMID THE NW FLOW ALOFT. FORECAST SOUNDINGS HINT AT A SLOW TOP DOWN STYLE SATURATION BY 12Z. THUS WILL KEEP THE EVENING DRY...BUT TREND TOWARD HIGHER CHANCES FOR RAIN DURING THE OVERNIGHT HOURS. 310K GFS ISENTROPIC SURFACE ALSO SHOWS A GOOD SURGE OF ISENTROPIC LIFT WITH SPECIFIC HUMIDITIES RISING TO NEAR 8 G/KG. WILL TREND LOWS AT OR ABOVE MAVMOS VALUES DUE TO EXPECTED WARM AIR ADVECTION...CLOUDS...AND PRECIP. ON WEDNESDAY MORNING...THE GFS AND NAM SUGGEST A COLD FRONT TROUGH LINGERING ACROSS THE STATE AS THE UPPER SUPPORT FROM THE OVERNIGHT PERIOD DEPARTS. FORECAST SOUNDINGS SUGGEST DRYING OUT...HOWEVER PLENTY OF CAPE...IN EXCESS OF 2000 J/KG REMAINS AVAILABLE. PWATS ARE ALSO NEAR 1.75 INCHES...VERY MOIST. CONVECTIVE TEMPS ON WEDNESDAY AFTERNOON ARE VERY ATTAINABLE...IN THE LOWER 80S...AND THE GFS 310K ISENTROPIC SURFACE SHOWS STRONG LIFT WITH AGAIN A VERY MOIST AIR MASS WITH SPECIFIC HUMIDITIES OVER 9 G/KG. MEANWHILE AT THE SURFACE A WARM FRONT STALLS ACROSS SOUTHERN INDIANA...FURTHER ACTING AS A FOCUS FOR LOWER LEVEL CONVERGENCE. THUS ANY HEATING ON WEDNESDAY SHOULD LEAD TO DEVELOPMENT. WILL TREND POPS AT OR ABOVE MAVMOS...PARTICULARLY DURING THE AFTERNOON. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND HIGHS AT OR BELOW MAVMOS. GFS DEPICTS A SHORT WAVE RIDING ACROSS THE WARM FRONT ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA ON WEDNESDAY NIGHT...AGAIN A VERY WARM AND MOIST AIR MASS WILL REMAIN IN PLACE. FORECAST SOUNDINGS ACROSS THE AREA ALSO INDICATE DEEP SATURATION BY THURSDAY...AND NOW WITH PWATS IN EXCESS OF 2 INCHES. FAVORABLE CAPE IS ALSO AVAILABLE. ALOFT IT APPEARS AS IF THE TROPICAL PLUME THAT IS CURRENTLY FLOWING ACROSS THE PLAINS INTO THE DEEP SOUTH WILL SHIFT EAST BY WEDNESDAY AND THURSDAY...ALLOWING THIS DEEPER MOISTURE TO SURGE INTO INDIANA AND THE OHIO VALLEY...PARTICULARLY ACROSS THE SOUTHERN PARTS OF OUR STATE. THUS WILL CONTINUE TO RAISE POPS THROUGH THURSDAY NIGHT...TRENDING HIGHS COOLER THAN MAVMOS AND LOWS WARMER...GIVEN THE EXPECTED CLOUDS AND RAIN. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 224 PM EDT TUE AUG 6 2013 EXTENDED MODELS IN FAIR AGREEMENT ON A COLD FRONT DROPPING TO NEAR THE OHIO RIVER 12Z SATURDAY WITH NORTHWEST FLOW LOFT. THE FRONT SHOULD SETTLE GRADUALLY FURTHER SOUTH THROUGH THE WEEKEND WITH HIGH PRESSURE BUILDING IN BEHIND THE FRONT. THIS SCENARIO SUGGESTS THUNDERSTORM CHANCES FRIDAY NIGHT...WITH MOSTLY SMALL POPS AND MAINLY ACROSS THE SOUTH...THEREAFTER. HAD TO TINKER ABOUT WITH REGIONAL ALLBLEND TO REFLECT THAT. THIS FAMILIAR RECENT PATTERN ALSO STRONGLY SUGGESTS BELOW NORMAL TEMPERATURES ONCE AGAIN. REGIONAL INITIALIZATION HAD A GOOD HANDLE ON THAT. && .AVIATION /DISCUSSION FOR 141800Z TAF ISSUANCE/... ISSUED AT 100 PM EDT SUN JUL 14 2013 MVFR CEILINGS LOOK LIKE THEY PERSIST ALL DAY PER MODEL SOUNDINGS...CONVECTIVE CONDENSATION LEVELS AND CU DEVELOPMENT PROGS. HOWEVER...WOULD NOT RULE OUT CEILINGS TO 3500 FEET AFTER 20Z IF ANY BREAKS OCCUR IN THE OVERCAST. OTHERWISE...SHOULD BE DRY UNTIL AFTER 00Z. THEN...ILL-DEFINED WARM FRONT IS EXPECTED TO MOVE THROUGH AFTER 04Z. WOULD NOT RULE OUT STORMS ALONG AND AHEAD OF THE WARM FRONT...HOWEVER WITH CONVERGENCE WEAK...AND LITTLE GOING ON NOW AHEAD OF THE FRONT...WILL LEAVE OUT MENTION OF THUNDER OVERNIGHT AND JUST GO WITH VCTS AFTER 20Z WEDNESDAY AT IND ASSOCIATED WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. SOUTH AND SOUTHWEST WINDS WILL BE 10 KNOTS OR LESS THROUGH THE PERIOD. FINALLY...WILL THROW IN MVFR FOG AFTER 09Z AS DEW POINTS INCREASE TO AROUND 70 BEHIND THE WARM FRONT. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...CP SHORT TERM...PUMA LONG TERM....MK AVIATION...MK VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
100 PM EDT TUE AUG 6 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 243 AM EDT TUE AUG 6 2013 WARMER AIR IS SET TO ARRIVE IN INDIANA TODAY AS HIGH PRESSURE OVER THE EAST COAST PROVIDES A WARMER AND MORE HUMID SOUTHERLY FLOW ALONG WITH DRY WEATHER. A MORE ACTIVE WEATHER PATTERN WILL TAKE SHAPE THROUGH THE MIDDLE OF THE WEEK AS A COLD FRONT IS EXPECTED TO PUSH TOWARD INDIANA LATE TONIGHT AND STALL ACROSS SOUTHERN INDIANA THROUGH THURSDAY THE FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS FROM LATE TONIGHT THROUGH FRIDAY. HIGH PRESSURE IS EXPECTED TO ARRIVE LATE FRIDAY AND BRING A RETURN TO DRY WEATHER FOR THE WEEKEND. && .NEAR TERM /REST OF TODAY/... ISSUED AT 944 AM EDT TUE AUG 6 2013 BUMPED UP CLOUD COVER THIS MORNING DUE TO SATELLITE TRENDS AS LOW DECK HAS BEEN OVERSPREADING THE AREA. LOOKS LIKE IT WILL TAKE A BIT LONGER TO SCATTER OUT AND THUS TRENDED MOSTLY CLOUDY TO LAST THROUGH MID AFTERNOON FOR MOST OF THE AREA. WITH THIS INCREASE IN CLOUD COVER HAVE ALSO LOWER HIGH TEMPERATURES FOR THE DAY...ONLY BY A DEGREE OR SO IN THE NORTH AND CENTRAL BUT BY A FEW DEGREES IN THE SOUTHWEST SINCE DEBRIS CLOUDS WILL LIKELY KEEP THAT AREA MOSTLY CLOUDY THROUGH MUCH OF THE DAY. RAP SHOWS SOME ISOLATED TO SCATTERED CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON BUT OTHER MODELS STILL LOOK DRY. WITH SOME SUBSIDENCE AND DRY AIR ALOFT AND THE RAP ALSO SHOWING SOME THINGS NOW THAT ARE NOT OCCURRING WILL CONTINUE WITH DRY FORECAST THROUGH THE DAY. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 243 AM EDT TUE AUG 6 2013 MAIN FOCUS DURING THIS PERIOD WILL BE POPS. MODELS ARE IN PRETTY GOOD AGREEMENT OF THE OVERALL TREND OF A WET...ACTIVE PATTERN. GFS AND NAM BOTH SUGGEST THE FIRST SHORT WAVE ARRIVING IN THE AREA LATE TONIGHT AMID THE NW FLOW ALOFT. FORECAST SOUNDINGS HINT AT A SLOW TOP DOWN STYLE SATURATION BY 12Z. THUS WILL KEEP THE EVENING DRY...BUT TREND TOWARD HIGHER CHANCES FOR RAIN DURING THE OVERNIGHT HOURS. 310K GFS ISENTROPIC SURFACE ALSO SHOWS A GOOD SURGE OF ISENTROPIC LIFT WITH SPECIFIC HUMIDITIES RISING TO NEAR 8 G/KG. WILL TREND LOWS AT OR ABOVE MAVMOS VALUES DUE TO EXPECTED WARM AIR ADVECTION...CLOUDS...AND PRECIP. ON WEDNESDAY MORNING...THE GFS AND NAM SUGGEST A COLD FRONT TROUGH LINGERING ACROSS THE STATE AS THE UPPER SUPPORT FROM THE OVERNIGHT PERIOD DEPARTS. FORECAST SOUNDINGS SUGGEST DRYING OUT...HOWEVER PLENTY OF CAPE...IN EXCESS OF 2000 J/KG REMAINS AVAILABLE. PWATS ARE ALSO NEAR 1.75 INCHES...VERY MOIST. CONVECTIVE TEMPS ON WEDNESDAY AFTERNOON ARE VERY ATTAINABLE...IN THE LOWER 80S...AND THE GFS 310K ISENTROPIC SURFACE SHOWS STRONG LIFT WITH AGAIN A VERY MOIST AIR MASS WITH SPECIFIC HUMIDITIES OVER 9 G/KG. MEANWHILE AT THE SURFACE A WARM FRONT STALLS ACROSS SOUTHERN INDIANA...FURTHER ACTING AS A FOCUS FOR LOWER LEVEL CONVERGENCE. THUS ANY HEATING ON WEDNESDAY SHOULD LEAD TO DEVELOPMENT. WILL TREND POPS AT OR ABOVE MAVMOS...PARTICULARLY DURING THE AFTERNOON. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND HIGHS AT OR BELOW MAVMOS. GFS DEPICTS A SHORT WAVE RIDING ACROSS THE WARM FRONT ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA ON WEDNESDAY NIGHT...AGAIN A VERY WARM AND MOIST AIR MASS WILL REMAIN IN PLACE. FORECAST SOUNDINGS ACROSS THE AREA ALSO INDICATE DEEP SATURATION BY THURSDAY...AND NOW WITH PWATS IN EXCESS OF 2 INCHES. FAVORABLE CAPE IS ALSO AVAILABLE. ALOFT IT APPEARS AS IF THE TROPICAL PLUME THAT IS CURRENTLY FLOWING ACROSS THE PLAINS INTO THE DEEP SOUTH WILL SHIFT EAST BY WEDNESDAY AND THURSDAY...ALLOWING THIS DEEPER MOISTURE TO SURGE INTO INDIANA AND THE OHIO VALLEY...PARTICULARLY ACROSS THE SOUTHERN PARTS OF OUR STATE. THUS WILL CONTINUE TO RAISE POPS THROUGH THURSDAY NIGHT...TRENDING HIGHS COOLER THAN MAVMOS AND LOWS WARMER...GIVEN THE EXPECTED CLOUDS AND RAIN. && .LONG TERM /FRIDAY THROUGH TUESDAY/... ISSUED AT 223 AM EDT TUE AUG 6 2013 LONG TERM PERIOD WILL BE CHARACTERIZED BY ZONAL OR WEAKLY CYCLONIC FLOW...WITH SURFACE HIGH PRESSURE LIKELY TO BE IN CONTROL ACROSS THE AREA FROM THE WEEKEND ONWARD. FRONTAL BOUNDARY WILL BE GRADUALLY EXITING THE REGION EARLY IN THE PERIOD...AND WILL CONTINUE TO CARRY POPS FRIDAY AND FRIDAY NIGHT BEFORE GOING DRY THE REST OF THE PERIOD. ALLBLEND WANTS TO INSERT POPS LATE IN THE WEEKEND BUT AT THIS POINT MODELS LOOK OVERAGGRESSIVE FOR THE WEAK FEATURES NOTED WELL UPSTREAM. ZONAL TO WEAKLY CYCLONIC FLOW SUGGESTS TEMPS NEAR TO A BIT BELOW NORMAL...AND ALLBLEND HANDLED THIS WELL WITH FEW TWEAKS REQUIRED. && .AVIATION /DISCUSSION FOR 141800Z TAF ISSUANCE/... ISSUED AT 100 PM EDT SUN JUL 14 2013 MVFR CEILINGS LOOK LIKE THEY PERSIST ALL DAY PER MODEL SOUNDINGS...CONVECTIVE CONDENSATION LEVELS AND CU DEVELOPMENT PROGS. HOWEVER...WOULD NOT RULE OUT CEILINGS TO 3500 FEET AFTER 20Z IF ANY BREAKS OCCUR IN THE OVERCAST. OTHERWISE...SHOULD BE DRY UNTIL AFTER 00Z. THEN...ILL-DEFINED WARM FRONT IS EXPECTED TO MOVE THROUGH AFTER 04Z. WOULD NOT RULE OUT STORMS ALONG AND AHEAD OF THE WARM FRONT...HOWEVER WITH CONVERGENCE WEAK...AND LITTLE GOING ON NOW AHEAD OF THE FRONT...WILL LEAVE OUT MENTION OF THUNDER OVERNIGHT AND JUST GO WITH VCTS AFTER 20Z WEDNESDAY AT IND ASSOCIATED WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. SOUTH AND SOUTHWEST WINDS WILL BE 10 KNOTS OR LESS THROUGH THE PERIOD. FINALLY...WILL THROW IN MVFR FOG AFTER 09Z AS DEW POINTS INCREASE TO AROUND 70 BEHIND THE WARM FRONT. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...CP SHORT TERM...PUMA LONG TERM....NIELD AVIATION...MK VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1014 AM EDT TUE AUG 6 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 243 AM EDT TUE AUG 6 2013 WARMER AIR IS SET TO ARRIVE IN INDIANA TODAY AS HIGH PRESSURE OVER THE EAST COAST PROVIDES A WARMER AND MORE HUMID SOUTHERLY FLOW ALONG WITH DRY WEATHER. A MORE ACTIVE WEATHER PATTERN WILL TAKE SHAPE THROUGH THE MIDDLE OF THE WEEK AS A COLD FRONT IS EXPECTED TO PUSH TOWARD INDIANA LATE TONIGHT AND STALL ACROSS SOUTHERN INDIANA THROUGH THURSDAY THE FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS FROM LATE TONIGHT THROUGH FRIDAY. HIGH PRESSURE IS EXPECTED TO ARRIVE LATE FRIDAY AND BRING A RETURN TO DRY WEATHER FOR THE WEEKEND. && .NEAR TERM /REST OF TODAY/... ISSUED AT 944 AM EDT TUE AUG 6 2013 BUMPED UP CLOUD COVER THIS MORNING DUE TO SATELLITE TRENDS AS LOW DECK HAS BEEN OVERSPREADING THE AREA. LOOKS LIKE IT WILL TAKE A BIT LONGER TO SCATTER OUT AND THUS TRENDED MOSTLY CLOUDY TO LAST THROUGH MID AFTERNOON FOR MOST OF THE AREA. WITH THIS INCREASE IN CLOUD COVER HAVE ALSO LOWER HIGH TEMPERATURES FOR THE DAY...ONLY BY A DEGREE OR SO IN THE NORTH AND CENTRAL BUT BY A FEW DEGREES IN THE SOUTHWEST SINCE DEBRIS CLOUDS WILL LIKELY KEEP THAT AREA MOSTLY CLOUDY THROUGH MUCH OF THE DAY. RAP SHOWS SOME ISOLATED TO SCATTERED CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON BUT OTHER MODELS STILL LOOK DRY. WITH SOME SUBSIDENCE AND DRY AIR ALOFT AND THE RAP ALSO SHOWING SOME THINGS NOW THAT ARE NOT OCCURRING WILL CONTINUE WITH DRY FORECAST THROUGH THE DAY. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 243 AM EDT TUE AUG 6 2013 MAIN FOCUS DURING THIS PERIOD WILL BE POPS. MODELS ARE IN PRETTY GOOD AGREEMENT OF THE OVERALL TREND OF A WET...ACTIVE PATTERN. GFS AND NAM BOTH SUGGEST THE FIRST SHORT WAVE ARRIVING IN THE AREA LATE TONIGHT AMID THE NW FLOW ALOFT. FORECAST SOUNDINGS HINT AT A SLOW TOP DOWN STYLE SATURATION BY 12Z. THUS WILL KEEP THE EVENING DRY...BUT TREND TOWARD HIGHER CHANCES FOR RAIN DURING THE OVERNIGHT HOURS. 310K GFS ISENTROPIC SURFACE ALSO SHOWS A GOOD SURGE OF ISENTROPIC LIFT WITH SPECIFIC HUMIDITIES RISING TO NEAR 8 G/KG. WILL TREND LOWS AT OR ABOVE MAVMOS VALUES DUE TO EXPECTED WARM AIR ADVECTION...CLOUDS...AND PRECIP. ON WEDNESDAY MORNING...THE GFS AND NAM SUGGEST A COLD FRONT TROUGH LINGERING ACROSS THE STATE AS THE UPPER SUPPORT FROM THE OVERNIGHT PERIOD DEPARTS. FORECAST SOUNDINGS SUGGEST DRYING OUT...HOWEVER PLENTY OF CAPE...IN EXCESS OF 2000 J/KG REMAINS AVAILABLE. PWATS ARE ALSO NEAR 1.75 INCHES...VERY MOIST. CONVECTIVE TEMPS ON WEDNESDAY AFTERNOON ARE VERY ATTAINABLE...IN THE LOWER 80S...AND THE GFS 310K ISENTROPIC SURFACE SHOWS STRONG LIFT WITH AGAIN A VERY MOIST AIR MASS WITH SPECIFIC HUMIDITIES OVER 9 G/KG. MEANWHILE AT THE SURFACE A WARM FRONT STALLS ACROSS SOUTHERN INDIANA...FURTHER ACTING AS A FOCUS FOR LOWER LEVEL CONVERGENCE. THUS ANY HEATING ON WEDNESDAY SHOULD LEAD TO DEVELOPMENT. WILL TREND POPS AT OR ABOVE MAVMOS...PARTICULARLY DURING THE AFTERNOON. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND HIGHS AT OR BELOW MAVMOS. GFS DEPICTS A SHORT WAVE RIDING ACROSS THE WARM FRONT ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA ON WEDNESDAY NIGHT...AGAIN A VERY WARM AND MOIST AIR MASS WILL REMAIN IN PLACE. FORECAST SOUNDINGS ACROSS THE AREA ALSO INDICATE DEEP SATURATION BY THURSDAY...AND NOW WITH PWATS IN EXCESS OF 2 INCHES. FAVORABLE CAPE IS ALSO AVAILABLE. ALOFT IT APPEARS AS IF THE TROPICAL PLUME THAT IS CURRENTLY FLOWING ACROSS THE PLAINS INTO THE DEEP SOUTH WILL SHIFT EAST BY WEDNESDAY AND THURSDAY...ALLOWING THIS DEEPER MOISTURE TO SURGE INTO INDIANA AND THE OHIO VALLEY...PARTICULARLY ACROSS THE SOUTHERN PARTS OF OUR STATE. THUS WILL CONTINUE TO RAISE POPS THROUGH THURSDAY NIGHT...TRENDING HIGHS COOLER THAN MAVMOS AND LOWS WARMER...GIVEN THE EXPECTED CLOUDS AND RAIN. && .LONG TERM /FRIDAY THROUGH TUESDAY/... ISSUED AT 223 AM EDT TUE AUG 6 2013 LONG TERM PERIOD WILL BE CHARACTERIZED BY ZONAL OR WEAKLY CYCLONIC FLOW...WITH SURFACE HIGH PRESSURE LIKELY TO BE IN CONTROL ACROSS THE AREA FROM THE WEEKEND ONWARD. FRONTAL BOUNDARY WILL BE GRADUALLY EXITING THE REGION EARLY IN THE PERIOD...AND WILL CONTINUE TO CARRY POPS FRIDAY AND FRIDAY NIGHT BEFORE GOING DRY THE REST OF THE PERIOD. ALLBLEND WANTS TO INSERT POPS LATE IN THE WEEKEND BUT AT THIS POINT MODELS LOOK OVERAGGRESSIVE FOR THE WEAK FEATURES NOTED WELL UPSTREAM. ZONAL TO WEAKLY CYCLONIC FLOW SUGGESTS TEMPS NEAR TO A BIT BELOW NORMAL...AND ALLBLEND HANDLED THIS WELL WITH FEW TWEAKS REQUIRED. && .AVIATION /UPDATED DISCUSSION FOR TAFS/... ISSUED AT 958 AM EDT TUE AUG 6 2013 WILL EXTEND DURATION OF MVFR CLOUD DECKS AT ALL TAF SITES A LITTLE LONGER INTO THE AFTERNOON BASED ON OBSERVED DECKS REMAINING FAIRLY SOLID. ALSO SOUNDING FORECASTS KEEPING VERY SHALLOW BUT NEARLY SATURATED LAYER THAT SLOWLY LIFTS TO NEAR 3000 FEET WITH HEATING. KHUF ALSO FLIRTING WITH IFR CLOUD DECKS THAT ARE OVER ILLINOIS AND TRYING TO SPREAD EAST. KLAF SHOULD REMAIN ABOVE 1000 FT DECKS GIVEN ADJACENT ILLINOIS OBSERVATIONS. KIND AND KBMG SHOULD ALSO REMAIN ABOVE 1000 FT AND THREAT TIME...IF ANY WOULD BE THROUGH 061500Z. PREVIOUS DISCUSSION ISSUED AT 638 AM EDT TUE AUG 6 2013... MVFR CEILINGS LIKELY TO PERSIST AT TIMES THROUGH MIDDAY TODAY. VFR BEYOND THEN. MVFR CEILINGS HAVE MOVED EASTWARD ACROSS THE AREA AND GUIDANCE HANGS ONTO THEM THROUGH AT LEAST MIDDAY. THIS APPEARS REASONABLE AND SREF PROBABILITIES AGREE. WILL INSERT TEMPO SCATTERED GROUPS LATER IN THE MORNING AS THE CEILINGS WILL LIKELY BEGIN TO FLUCTUATE AS THEY LIFT. MAINLY MID CLOUD BEYOND THIS MORNING. SOME SHOWERS/STORMS POSSIBLE TONIGHT BUT FAIRLY UNCERTAIN AT THIS POINT...SO WILL LEAVE FOR LATER PACKAGES. WINDS WILL BE BELOW 10KT THROUGHOUT THE PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...CP SHORT TERM...PUMA LONG TERM....NIELD AVIATION...TUCEK VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
951 AM EDT TUE AUG 6 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 243 AM EDT TUE AUG 6 2013 WARMER AIR IS SET TO ARRIVE IN INDIANA TODAY AS HIGH PRESSURE OVER THE EAST COAST PROVIDES A WARMER AND MORE HUMID SOUTHERLY FLOW ALONG WITH DRY WEATHER. A MORE ACTIVE WEATHER PATTERN WILL TAKE SHAPE THROUGH THE MIDDLE OF THE WEEK AS A COLD FRONT IS EXPECTED TO PUSH TOWARD INDIANA LATE TONIGHT AND STALL ACROSS SOUTHERN INDIANA THROUGH THURSDAY THE FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS FROM LATE TONIGHT THROUGH FRIDAY. HIGH PRESSURE IS EXPECTED TO ARRIVE LATE FRIDAY AND BRING A RETURN TO DRY WEATHER FOR THE WEEKEND. && .NEAR TERM /REST OF TODAY/... ISSUED AT 944 AM EDT TUE AUG 6 2013 BUMPED UP CLOUD COVER THIS MORNING DUE TO SATELLITE TRENDS AS LOW DECK HAS BEEN OVERSPREADING THE AREA. LOOKS LIKE IT WILL TAKE A BIT LONGER TO SCATTER OUT AND THUS TRENDED MOSTLY CLOUDY TO LAST THROUGH MID AFTERNOON FOR MOST OF THE AREA. WITH THIS INCREASE IN CLOUD COVER HAVE ALSO LOWER HIGH TEMPERATURES FOR THE DAY...ONLY BY A DEGREE OR SO IN THE NORTH AND CENTRAL BUT BY A FEW DEGREES IN THE SOUTHWEST SINCE DEBRIS CLOUDS WILL LIKELY KEEP THAT AREA MOSTLY CLOUDY THROUGH MUCH OF THE DAY. RAP SHOWS SOME ISOLATED TO SCATTERED CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON BUT OTHER MODELS STILL LOOK DRY. WITH SOME SUBSIDENCE AND DRY AIR ALOFT AND THE RAP ALSO SHOWING SOME THINGS NOW THAT ARE NOT OCCURRING WILL CONTINUE WITH DRY FORECAST THROUGH THE DAY. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 243 AM EDT TUE AUG 6 2013 MAIN FOCUS DURING THIS PERIOD WILL BE POPS. MODELS ARE IN PRETTY GOOD AGREEMENT OF THE OVERALL TREND OF A WET...ACTIVE PATTERN. GFS AND NAM BOTH SUGGEST THE FIRST SHORT WAVE ARRIVING IN THE AREA LATE TONIGHT AMID THE NW FLOW ALOFT. FORECAST SOUNDINGS HINT AT A SLOW TOP DOWN STYLE SATURATION BY 12Z. THUS WILL KEEP THE EVENING DRY...BUT TREND TOWARD HIGHER CHANCES FOR RAIN DURING THE OVERNIGHT HOURS. 310K GFS ISENTROPIC SURFACE ALSO SHOWS A GOOD SURGE OF ISENTROPIC LIFT WITH SPECIFIC HUMIDITIES RISING TO NEAR 8 G/KG. WILL TREND LOWS AT OR ABOVE MAVMOS VALUES DUE TO EXPECTED WARM AIR ADVECTION...CLOUDS...AND PRECIP. ON WEDNESDAY MORNING...THE GFS AND NAM SUGGEST A COLD FRONT TROUGH LINGERING ACROSS THE STATE AS THE UPPER SUPPORT FROM THE OVERNIGHT PERIOD DEPARTS. FORECAST SOUNDINGS SUGGEST DRYING OUT...HOWEVER PLENTY OF CAPE...IN EXCESS OF 2000 J/KG REMAINS AVAILABLE. PWATS ARE ALSO NEAR 1.75 INCHES...VERY MOIST. CONVECTIVE TEMPS ON WEDNESDAY AFTERNOON ARE VERY ATTAINABLE...IN THE LOWER 80S...AND THE GFS 310K ISENTROPIC SURFACE SHOWS STRONG LIFT WITH AGAIN A VERY MOIST AIR MASS WITH SPECIFIC HUMIDITIES OVER 9 G/KG. MEANWHILE AT THE SURFACE A WARM FRONT STALLS ACROSS SOUTHERN INDIANA...FURTHER ACTING AS A FOCUS FOR LOWER LEVEL CONVERGENCE. THUS ANY HEATING ON WEDNESDAY SHOULD LEAD TO DEVELOPMENT. WILL TREND POPS AT OR ABOVE MAVMOS...PARTICULARLY DURING THE AFTERNOON. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND HIGHS AT OR BELOW MAVMOS. GFS DEPICTS A SHORT WAVE RIDING ACROSS THE WARM FRONT ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA ON WEDNESDAY NIGHT...AGAIN A VERY WARM AND MOIST AIR MASS WILL REMAIN IN PLACE. FORECAST SOUNDINGS ACROSS THE AREA ALSO INDICATE DEEP SATURATION BY THURSDAY...AND NOW WITH PWATS IN EXCESS OF 2 INCHES. FAVORABLE CAPE IS ALSO AVAILABLE. ALOFT IT APPEARS AS IF THE TROPICAL PLUME THAT IS CURRENTLY FLOWING ACROSS THE PLAINS INTO THE DEEP SOUTH WILL SHIFT EAST BY WEDNESDAY AND THURSDAY...ALLOWING THIS DEEPER MOISTURE TO SURGE INTO INDIANA AND THE OHIO VALLEY...PARTICULARLY ACROSS THE SOUTHERN PARTS OF OUR STATE. THUS WILL CONTINUE TO RAISE POPS THROUGH THURSDAY NIGHT...TRENDING HIGHS COOLER THAN MAVMOS AND LOWS WARMER...GIVEN THE EXPECTED CLOUDS AND RAIN. && .LONG TERM /FRIDAY THROUGH TUESDAY/... ISSUED AT 223 AM EDT TUE AUG 6 2013 LONG TERM PERIOD WILL BE CHARACTERIZED BY ZONAL OR WEAKLY CYCLONIC FLOW...WITH SURFACE HIGH PRESSURE LIKELY TO BE IN CONTROL ACROSS THE AREA FROM THE WEEKEND ONWARD. FRONTAL BOUNDARY WILL BE GRADUALLY EXITING THE REGION EARLY IN THE PERIOD...AND WILL CONTINUE TO CARRY POPS FRIDAY AND FRIDAY NIGHT BEFORE GOING DRY THE REST OF THE PERIOD. ALLBLEND WANTS TO INSERT POPS LATE IN THE WEEKEND BUT AT THIS POINT MODELS LOOK OVERAGGRESSIVE FOR THE WEAK FEATURES NOTED WELL UPSTREAM. ZONAL TO WEAKLY CYCLONIC FLOW SUGGESTS TEMPS NEAR TO A BIT BELOW NORMAL...AND ALLBLEND HANDLED THIS WELL WITH FEW TWEAKS REQUIRED. && .AVIATION /DISCUSSION FOR THE 06/12Z TAFS/... ISSUED AT 638 AM EDT TUE AUG 6 2013 MVFR CEILINGS LIKELY TO PERSIST AT TIMES THROUGH MIDDAY TODAY. VFR BEYOND THEN. MVFR CEILINGS HAVE MOVED EASTWARD ACROSS THE AREA AND GUIDANCE HANGS ONTO THEM THROUGH AT LEAST MIDDAY. THIS APPEARS REASONABLE AND SREF PROBABILITIES AGREE. WILL INSERT TEMPO SCATTERED GROUPS LATER IN THE MORNING AS THE CEILINGS WILL LIKELY BEGIN TO FLUCTUATE AS THEY LIFT. MAINLY MID CLOUD BEYOND THIS MORNING. SOME SHOWERS/STORMS POSSIBLE TONIGHT BUT FAIRLY UNCERTAIN AT THIS POINT...SO WILL LEAVE FOR LATER PACKAGES. WINDS WILL BE BELOW 10KT THROUGHOUT THE PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...CP SHORT TERM...PUMA LONG TERM....NIELD AVIATION...NIELD VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
951 PM CDT Wed Aug 7 2013 .UPDATE... Issued at 940 PM CDT WED AUG 7 2013 Increase pops based on the new runs the HRRR model. The HRRR did a good job last night forecasting the outflow boundary propagating northeast off the MCS and causing numerous showers and thunderstorms to develop farther north along and and south of the boundary, from the southern counties to north of I-70. The greatest potential for likely to categorical pops will remain across the southern counties with a sharp gradient in pops from east central KS, along I-70 into north central KS along the NE border. Northeast KS may not see any rainfall until Thursday afternoon. Also increased pops for the southern CWA into Thursday morning as the brunt of MCS will move across southeast KS and the northern fringe may cause heavy rainfall across the extreme southeast counties. && .SHORT TERM...(THIS EVENING THROUGH Thursday) ISSUED AT 331 PM CDT WED AUG 7 2013 Extensive cloud cover has kept high temperatures today mainly in upper 70s to lower to middle 80s across the area. Diffuse boundary has been draped E to W across the area but is difficult to find because of very weak surface wind fields. Isolated brief showers have popped up and quickly died where greater instability exists, near and south of boundary. Wouldn`t expect this activity to be more than isolated late this afternoon and evening with weak convergence and no organized upper support. Nearly all short range (and medium range) models now consistent in keeping weak upper disturbance south of area, so most of northeast quarter of KS dry overnight. Only outlier is now the 09Z SREF, and have disregarded that in coming up with POP and QPF forecast. Thus, have considerably decreased previous forecast POPs for tonight with highest values across far south and west forecast area and least in far northeast KS. Latest model runs also increase influence of surface high pressure nosing into area from the upper midwest/western Great Lakes. This will also inhibit chances for thunderstorms on Thursday as well, with best chances still south and west and lowest chances northeast. With this guidance, would not expect any significantly heavy precipitation and very low chances for any new flooding, or increase on current river flooding through Thursday. .LONG TERM...(Thursday NIGHT THROUGH Wednesday) ISSUED AT 331 PM CDT WED AUG 7 2013 Thursday evening through Saturday... On Thursday evening, widespread moderate to at times heavy rainfall is expected to spread northeast through the cwa. Weak mid level flow will allow a slow northeast progression of the main shortwave trof and therefore prolonged duration of scattered showers and thunderstorms in the area. Strong southerly fetch of moisture combined with warm air overriding the h85 front is expected to center heaviest rainfall along and just north of the axis. Latest model runs of the GFS and NAM are beginning to focus higher qpf values just south and east of the cwa. This will need to be monitored for consistency in consideration of flood potential. Areas especially south of Interstate 70 who have persistently seen rainfall each evening and/or have had flooding issues need to be most aware to flash flooding potential from Thursday evening into Friday. Based on the uncertainty mentioned will defer issuing flood watch until next issuance. Where heavy precip does develop forecast soundings depict completely saturated columns during this period with pwat values extending above 2 inches. Showers and thunderstorms should gradually exit the area through the day on Friday before surface high builds southward Friday evening. Cloud cover gradually clearing out with exiting showers should hold temps to the upper 70s and low 80s on Friday. Light northeast winds hover around 10 mph. Ridge flattens out Saturday with mid level zonal flow keeping most of the rain showers out of the area. Cool air advection filtering southward on the backside of the cool front will keep highs quite pleasant for August in the low 80s. Slightly drier air accompanying the wave should alleviate dewpoints a bit into the low 60s. The 12Z NAM and ECMWF try to redevelop scattered convection over east central areas during the late aftn in vcnty of the frontal boundary. With this being the only run will keep forecast dry for now and monitor model trends in upcoming forecasts. Saturday evening through Wednesday... On Sunday an upper trof begins to deepen across the Ontario region. A series of embedded waves will continue to bring off and on showers and thunderstorm chances. GFS has pretty consistent between each run by carrying southward a sfc trough and complex of showers and thunderstorms southeast Sunday evening into Monday. Frontal boundary accompanying the trough becomes nearly stationary over central Kansas with a similar pattern for precip chances through Wednesday. Confidence is not high after Monday as the 12Z ECMWF has been inconsistent with the frontal boundary positioning well south of the cwa and therefore keeping much of the period dry. Temperatures while progged to be slightly warmer will largely depend on rainfall and cloud cover. For now will keep highs in the low to mid 80s with lows in the 60s. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z Thursday EVENING) ISSUED AT 620 PM CDT WED AUG 7 2013 Most numerical models are showing thunderstorms remaining west and south of the TAF sites through most of the TAF period. At this time I do not have confidence to insert VCTS into TAFS. Kept TAFS VFR through next 24 hours. CU may develop once again Thursday afternoon with bases of 6 to 8 thousand feet. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Gargan SHORT TERM...PHILLIPS LONG TERM...BOWEN AVIATION...GARGAN
AREA FORECAST DISCUSSION
NWS GOODLAND KS
523 PM MDT WED AUG 7 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 221 PM MDT WED AUG 7 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES ZONAL FLOW STILL IN PLACE ACROSS THE CONUS WITH STRONG CLOSED LOW OVER CENTRAL CANADA. AN EMBEDDED H5/H7 LOW IN IN PLACE UPSTREAM OF THE CWA OVER THE FOUR CORNER REGION. LARGE SCALE FORCING AND MID LEVEL MOISTURE CONTINUE TO ADVECT INTO THE CWA FROM THE SOUTHWEST AHEAD OF THE FOUR CORNERS TROUGH. RAP ANALYSIS STILL SHOWS 500-1500 J/KG OF MUCAPE IN PLACE...SO THUNDERSTORMS ARE CERTAINLY POSSIBLE. AT THIS POINT OVERALL THREAT FOR SEVERE THUNDERSTORMS SEEMS LOW. MODELS CONTINUE TO PAIN BULLS EYE OF 0.50+ QPF...FAVORING SOUTHERN LOCATIONS. AT THE SAME TIME...NAM/SREF HAVE TRENDED FURTHER NORTH WHICH DOES SEEM TO HAVE SUPPORT LOOKING AT LATEST RADAR TRENDS. I ADJUSTED POPS ACCORDINGLY. RAP INDICATES PWATS IN EXCESS OF 1.3"...AND WHILE LOWER THAN THE LAST FEW DAYS IS STILL CLIMATOLOGICALLY HIGH. BASED ON RADAR/SATELLITE TRENDS...AND THE NATURE OF THIS PATTERN...I AM CURRENTLY EXPECTING SEVERAL PERIODS OF SHOWERS/THUNDERSTORMS ROTATING ACROSS OUR CWA THROUGH TONIGHT...BEFORE THE MAIN TROUGH MOVES ACROSS THE REGION. AS THIS OCCURS WE MIGHT SEE OUR BEST CHANCE FOR HEAVY PRECIP ACROSS MOST OF THE CWA. THERE IS STILL SOME INDICATION THIS COULD OCCUR LATER IN THE DAY THURSDAY...HOWEVER CONSENSUS SUPPORTS A MORNING TROUGH PASSAGE AND DECREASING CHANCES THROUGH MIDDAY THURSDAY. REGARDING WATCH...CONSIDERING THE LIKELIHOOD THAT PRECIPITATION WILL REMAIN LIGHT TO MODERATE ACROSS MOST OF THE AREA WITH HIGHEST TOTALS SPREAD OUT OVER 6-12HR PERIOD...I AM STARTING TO QUESTION THE POTENTIAL FOR FLASH FLOODING. LATEST 6HR FLASH FLOOD GUIDANCE IS GENERALLY IN THE 2-3 INCH RANGE OVER THE WATCH AREA AND UNLESS WE CAN GET A STRONG THUNDERSTORM EMBEDDED WITHIN THE LARGER AREA OF LIGHT-MODERATE RAIN IM NOT SURE WE WILL SEE THESE RATES. WE MAY BE ABLE TO CANCEL THE WATCH LATER THIS EVENING...BUT I WOULD RATHER WAIT AND SEE HOW CONVECTION EVOLVES. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 221 PM MDT WED AUG 7 2013 THURSDAY EVENING THE UPPER LEVEL SHORT WAVE TROUGH WILL MOVE EAST OF THE AREA. WITH THE NOSE OF THE LOW LEVEL JET OVER THE EASTERN PART OF THE AREA AS WELL...AND A WEAK RIGHT ENTRANCE REGION OF THE 300MB JET OVER THE AREA...THERE MAY BE SOME LINGERING PRECIP. ACTIVITY AHEAD OF THE EXITING TROUGH. MEANWHILE BEHIND THE TROUGH DRIER AIR WILL BE MOVING IN WHICH WILL CAUSE PRECIP. CHANCES TO DECLINE FROM WEST TO EAST. HOWEVER WITH COOLER AIR MOVING IN THERE WILL BE SOME INSTABILITY LINGERING BEHIND THE TROUGH. WITH SOME MUCH SMALLER UPPER LEVEL DISTURBANCES MOVING THROUGH BEHIND THE MAIN FEATURE...ISOLATED STORMS CANNOT BE RULED OUT DURING THE EVENING AND INTO THE OVERNIGHT HOURS. FRIDAY ANOTHER UPPER LEVEL SHORT WAVE TROUGH WILL DEVELOP OVER FAR EASTERN COLORADO IN THE LATE AFTERNOON. AT THE SURFACE A TROUGH WILL BE OVER THE WESTERN BORDER OF THE TRI-STATE AREA BENEATH THE SHORT WAVE. WITH SURFACE CONVERGENCE AND UPPER LEVEL LIFT...ANTICIPATE SOME STORMS DEVELOPING ALONG THE SURFACE TROUGH DURING THE MID AFTERNOON INTO THE EARLY EVENING. MEAN STORM MOTIONS WILL BE VERY SLOW...WITH MOTIONS TURNING FROM THE WEST TO THE NORTH. THESE MOTIONS WILL KEEP THE STORMS CONFINED TO THE SURFACE TROUGH. BY THE LATE EVENING ANY STORMS THAT DEVELOPED WILL DISSIPATE AS THE ENVIRONMENT STABILIZES. THE MAIN THREAT WITH ANY STORMS THAT DEVELOP WILL BE HEAVY RAINFALL. SATURDAY THROUGH WEDNESDAY THE UPPER LEVEL RIDGE OVER THE SOUTHWEST CONUS WILL SLOWLY BUILD NORTHWARD...WITH THE TRI-STATE AREA REMAINING UNDER THE PERIPHERY OF THE RIDGE. AS A RESULT MULTIPLE UPPER LEVEL SHORT WAVE TROUGHS WILL MOVE OVER THE AREA THROUGH THE PERIOD. THE STRONGER TROUGHS WILL MOVE OVER THE AREA AFTER THE WEEKEND. MEANWHILE A FRONT WILL WAFFLE BACK AND FORTH OVER THE AREA DURING THIS PERIOD WHICH WILL CAUSE TEMPERATURES TO VARY SOMEWHAT. AT THIS TIME RANGE DIFFICULT TO KNOW WHERE THE FRONT WILL BE SO WILL KEEP THE CONSENSUS TEMP. FORECAST OF NEAR NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 520 PM MDT WED AUG 7 2013 A LARGE AREA OF PRECIPITATION CURRENTLY MOVING ACROSS NORTHEAST COLORADO ASSOCIATED WITH AN UPPER DISTURBANCE WILL OVERSPREAD B0TH KGLD AND KMCK THIS EVENING AND CONTINUE THROUGH THURSDAY MORNING. FLIGHT CATEGORIES WILL GO DOWN WITH THE LOWERING CIGS AND VISIBILITY RESTRICTIONS DUE TO RAIN AND/OR FOG...SLOW TO IMPROVE THURSDAY MORNING THROUGH EARLY AFTERNOON. A FEW RUMBLES OF THUNDER WILL ALSO BE POSSIBLE BUT SEVERE POTENTIAL LOOKS LIMITED AT THIS TIME DUE TO COOL/STABLE AIR MASS IN THE AREA. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...FLASH FLOOD WATCH UNTIL 11 PM MDT /MIDNIGHT CDT/ THIS EVENING FOR KSZ027>029-041-042. CO...FLASH FLOOD WATCH UNTIL 11 PM MDT THIS EVENING FOR COZ092. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JTL AVIATION...024
AREA FORECAST DISCUSSION
NWS GOODLAND KS
247 PM MDT TUE AUG 6 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 222 PM MDT TUE AUG 6 2013 LATEST WV IMAGERY AND RAP ANALYSIS SHOWS NW FLOW STILL IN PLACE ACROSS THE NORTHERN AND CENTRAL CONUS...WITH A RIDGE CENTERED OVER TEXAS AND A WEAKENED CLOSED LOW OVER SOUTHERN ARIZONA. A VERY MOIST/UNSTABLE AIRMASS REMAINS IN PLACE OVER OUR CWA WITH TD VALUES ACROSS NW KANSAS IN THE MID 60S TO LOW 70S...AND SB CAPE VALUES IN THE 2000-4000 J/KG RANGE FROM THE WEST TO THE EAST. A SURFACE TROUGH IS CURRENTLY CENTERED ALONG THE KS/CO BORDER...WITH LOWER TD VALUES AND MUCH MORE STABLE AIRMASS TO THE WEST OF THIS FEATURE. THUNDERSTORMS HAVE ALREADY DEVELOPED ALONG THIS TROUGH AXIS IN OUR FAR SW CWA. I WOULD EXPECT ADDITIONAL THUNDERSTORM ACTIVITY TO INITIATE ALONG AND EAST OF THIS FEATURE THROUGH THIS AFTERNOON AND EVENING. LATEST HRRR INDICATED ACTIVITY FORMING AHEAD OF THIS AXIS AND FORMING INTO A CLUSTER/LINE AND SHIFTING TO THE SOUTH AND EAST. BASED ON NAM/GFS SUPPORTING BETTER COVERAGE IN THE SOUTH...WHICH IS IN LINE WITH SHORT RANGE GUIDANCE I KEPT THIS TREND. A COLD FRONT WILL APPROACH THE CWA TONIGHT...WITH ELEVATED INSTABILITY/GOOD MOISTURE LINGERING I DECIDED TO KEEP THUNDERSTORM MENTION THROUGH THE NIGHT. CONSIDERING STORM MOTION WITH INDIVIDUAL CELLS AND MOISTURE AVAILABILITY I AM CONCERNED WE COULD SEE LOCALIZED FLASH FLOODING THIS AFTERNOON/EVENING IN ADDITION TO SEVERE HAIL/WIND THREAT. COVERAGE IS A QUESTION THOUGH...WITH ANY CLUSTER/LINE LIKELY BEGINNING TO PROPAGATE QUICKER AS IT FORMS A COLD POOL IN OUR SOUTH. AS A RESULT WE MAY NOT ACTUALLY SEE AS WIDESPREAD OF A THREAT OF FLASH FLOODING TODAY/TONIGHT. WEDNESDAY...COLD FRONT WILL DROP SOUTH OF OUR CWA AND BE NEAR THE KS/OK BORDER BY LATE WED AFTERNOON. DEEP MOIST EASTERLY FLOW ALONG/NORTH OF THIS FEATURE COMBINED WITH INCREASING LARGE SCALE ASCENT WILL SUPPORT NUMEROUS TO WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS OUR SOUTHERN CWA. I AM CONCERNED THAT THE BEST COVERAGE MAY BE TIED TO THE FRONT...WHICH WOULD PUT BETTER COVERAGE SOUTH OF OUR CWA. HOWEVER THERE IS ENOUGH MOISTURE/FORCING ALOFT TO SUPPORT HIGHER POPS ACROSS OUR SOUTHERN CWA IN THE AFTERNOON. A RESULT OF THICK CLOUD COVER AND CAA THROUGH THE DAY WILL BE HIGH TEMPERATURES WELL BELOW NORMAL (UPPER 60S TO MID 70S). PREVIOUS FORECAST HAD THIS COOLER TREND...SO ONLY MINOR ADJUSTMENTS MADE. WHILE WE MAY NEED A FLASH FLOOD WATCH FOR WED AFTERNOON DUE TO POSSIBLE TRAINING AND WIDESPREAD HEAVY RAIN COVERAGE IN THE SOUTH...I FELT IT WAS BEST TO CONCENTRATE PUBLIC ATTENTION ON ONGOING THUNDERSTORMS THIS AFTERNOON/EVENING TO AVOID CONFUSION. WE MAY NEED TO ISSUE A WATCH ON OVERNIGHT SHIFTS IF IT LOOKS LIKE OUR SOUTHERN CWA WILL REMAIN FAVORABLE FOR A LARGE SCALE FLASH FLOOD THREAT. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 246 PM MDT TUE AUG 6 2013 FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT THE UPPER LEVEL WEATHER PATTERN WILL REMAIN LARGELY UNCHANGED. AN UPPER LEVEL SHORT WAVE TROUGH WILL MOVE OVER THE AREA WEDNESDAY NIGHT AND SLOWLY GLIDE EASTWARD ACROSS THE AREA WITH ANOTHER ONE FOLLOWING IT OVER THE AREA THURSDAY. WITH THE MID THROUGH UPPER LEVELS NEARLY TO TOTALLY SATURATED AND THE RIGHT ENTRANCE OF THE 300MB JET OVER THE AREA AS THESE TROUGHS MOVE THROUGH...AM THINKING THERE SHOULD BE A GOOD CHANCE FOR SCATTERED TO WIDESPREAD RAINFALL DEVELOPMENT. THE BEST AREA FOR PRECIP. CHANCES LOOKS TO BE OVER THE SOUTH HALF WHERE THE BETTER FORCING AND LIFT WILL BE. PRECIP. CHANCES TAPER OFF THURSDAY NIGHT FROM WEST TO EAST AS THE UPPER LEVEL TROUGH MOVES OUT OF THE AREA AND DRIER AIR MOVES IN BEHIND IT. WEDNESDAY EVENING LOOKS TO BE THE BEST CHANCE FOR SEVERE STORM DEVELOPMENT DUE TO 0-6KM SHEAR OF 30-50KTS. HOWEVER ANY SEVERE STORMS THAT DEVELOP SHOULD REMAIN CONFINED TO THE WESTERN AND SOUTHERN FRINGES OF THE AREA WHERE THE BEST INSTABILITY WILL BE LOCATED. HEAVY RAINFALL WILL BE THE PREDOMINANT THREAT DURING THIS TIMEFRAME DUE TO STORM MOTIONS OF 5-10KTS. A FLASH FLOOD WATCH WILL LIKELY BE NEEDED FROM WEDNESDAY THROUGH THURSDAY MORNING FOR THE SOUTHERN TWO ROWS OF COUNTIES WHERE STORM COVERAGE WILL BE MOST WIDESPREAD. AFTER SOME DISCUSSION WILL HOLD OFF ISSUING THE WATCH FOR NOW TO PREVENT CONFUSION WITH ANY POTENTIAL FLOODING THREAT FROM TODAY/S STORM ACTIVITY. FOR FRIDAY THROUGH TUESDAY THE UPPER LEVEL RIDGE OVER THE SOUTHWEST CONUS WILL BUILD A BIT FURTHER NORTH...WITH THE NORTHERN PERIPHARY OF THE RIDGE OVER THE AREA. MULTIPLE UPPER LEVEL SHORT WAVE TROUGHS WILL MOVE ACROSS THE AREA DURING THIS TIME CAUSING THERE TO BE PRECIP. CHANCES FOR NEARLY EVERY DAY. MEANWHILE THE WEAK FRONT THAT HAS BEEN WEST OF THE AREA WILL MOVE EAST ACROSS THE AREA DURING THE WEEKEND INTO EARLY NEXT WEEK. AS A RESULT TEMPERATURES WILL RETURN TO NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1144 AM MDT TUE AUG 6 2013 SCATTERED THUNDERSTORMS WILL DEVELOP ALONG TROUGH AXIS OVER NW KS/SW NE THIS AFTERNOON AND INCREASE IN COVERAGE THROUGH THIS EVENING AS THE ACTIVITY TRANSITIONS EAST. CURRENTLY COVERAGE IS STILL TOO MUCH OF A QUESTION AT EITHER TERMINAL WITH BETTER CHANCES FURTHER SOUTH AND EAST...SO I LIMITED MENTION TO VCTS. LATE TONIGHT FOG/STRATUS IS EXPECTED TO REDEVELOP...WITH LOWER CIGS/VIS AT BOTH TERMINALS BY SUNRISE. GUIDANCE CURRENTLY SUPPORTS MVFR CONDITIONS...HOWEVER CONSIDERING THE MOIST NATURE OF THE AIRMASS IF WINDS GO COMPLETELY CALM WE COULD SEE LOWER CONDITIONS DEVELOP. FOR NOW I CHOSE TO STAY IN LINE WITH CURRENT GUIDANCE...HOWEVER WE WILL NEED TO MONITOR THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JTL AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
222 PM MDT TUE AUG 6 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 222 PM MDT TUE AUG 6 2013 LATEST WV IMAGERY AND RAP ANALYSIS SHOWS NW FLOW STILL IN PLACE ACROSS THE NORTHERN AND CENTRAL CONUS...WITH A RIDGE CENTERED OVER TEXAS AND A WEAKENED CLOSED LOW OVER SOUTHERN ARIZONA. A VERY MOIST/UNSTABLE AIRMASS REMAINS IN PLACE OVER OUR CWA WITH TD VALUES ACROSS NW KANSAS IN THE MID 60S TO LOW 70S...AND SB CAPE VALUES IN THE 2000-4000 J/KG RANGE FROM THE WEST TO THE EAST. A SURFACE TROUGH IS CURRENTLY CENTERED ALONG THE KS/CO BORDER...WITH LOWER TD VALUES AND MUCH MORE STABLE AIRMASS TO THE WEST OF THIS FEATURE. THUNDERSTORMS HAVE ALREADY DEVELOPED ALONG THIS TROUGH AXIS IN OUR FAR SW CWA. I WOULD EXPECT ADDITIONAL THUNDERSTORM ACTIVITY TO INITIATE ALONG AND EAST OF THIS FEATURE THROUGH THIS AFTERNOON AND EVENING. LATEST HRRR INDICATED ACTIVITY FORMING AHEAD OF THIS AXIS AND FORMING INTO A CLUSTER/LINE AND SHIFTING TO THE SOUTH AND EAST. BASED ON NAM/GFS SUPPORTING BETTER COVERAGE IN THE SOUTH...WHICH IS IN LINE WITH SHORT RANGE GUIDANCE I KEPT THIS TREND. A COLD FRONT WILL APPROACH THE CWA TONIGHT...WITH ELEVATED INSTABILITY/GOOD MOISTURE LINGERING I DECIDED TO KEEP THUNDERSTORM MENTION THROUGH THE NIGHT. CONSIDERING STORM MOTION WITH INDIVIDUAL CELLS AND MOISTURE AVAILABILITY I AM CONCERNED WE COULD SEE LOCALIZED FLASH FLOODING THIS AFTERNOON/EVENING IN ADDITION TO SEVERE HAIL/WIND THREAT. COVERAGE IS A QUESTION THOUGH...WITH ANY CLUSTER/LINE LIKELY BEGINNING TO PROPAGATE QUICKER AS IT FORMS A COLD POOL IN OUR SOUTH. AS A RESULT WE MAY NOT ACTUALLY SEE AS WIDESPREAD OF A THREAT OF FLASH FLOODING TODAY/TONIGHT. WEDNESDAY...COLD FRONT WILL DROP SOUTH OF OUR CWA AND BE NEAR THE KS/OK BORDER BY LATE WED AFTERNOON. DEEP MOIST EASTERLY FLOW ALONG/NORTH OF THIS FEATURE COMBINED WITH INCREASING LARGE SCALE ASCENT WILL SUPPORT NUMEROUS TO WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS OUR SOUTHERN CWA. I AM CONCERNED THAT THE BEST COVERAGE MAY BE TIED TO THE FRONT...WHICH WOULD PUT BETTER COVERAGE SOUTH OF OUR CWA. HOWEVER THERE IS ENOUGH MOISTURE/FORCING ALOFT TO SUPPORT HIGHER POPS ACROSS OUR SOUTHERN CWA IN THE AFTERNOON. A RESULT OF THICK CLOUD COVER AND CAA THROUGH THE DAY WILL BE HIGH TEMPERATURES WELL BELOW NORMAL (UPPER 60S TO MID 70S). PREVIOUS FORECAST HAD THIS COOLER TREND...SO ONLY MINOR ADJUSTMENTS MADE. WHILE WE MAY NEED A FLASH FLOOD WATCH FOR WED AFTERNOON DUE TO POSSIBLE TRAINING AND WIDESPREAD HEAVY RAIN COVERAGE IN THE SOUTH...I FELT IT WAS BEST TO CONCENTRATE PUBLIC ATTENTION ON ONGOING THUNDERSTORMS THIS AFTERNOON/EVENING TO AVOID CONFUSION. WE MAY NEED TO ISSUE A WATCH ON OVERNIGHT SHIFTS IF IT LOOKS LIKE OUR SOUTHERN CWA WILL REMAIN FAVORABLE FOR A LARGE SCALE FLASH FLOOD THREAT. .LONG TERM...(FRIDAY THROUGH MONDAY) ISSUED AT 220 AM MDT TUE AUG 6 2013 MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE SYNOPTIC SCALE PATTERN DURING THE EXTENDED PERIOD. MINOR DIFFERENCES EMERGE BY THE WEEKEND WHEN ECMWF IS STRONGER AND MORE AMPLIFIED THAN THE GFS WITH UPPER RIDGE THAT BUILDS OVER OUR AREA. OTHERWISE...TYPICAL DIFFERENCES EXIST WITH TIMING AND PLACEMENT OF SUBTLE SHORTWAVES IN THE MID/UPPER FLOW LEADING TO UNCERTAINTY AS TO WHEN THE MOST WIDESPREAD CONVECTION WILL OCCUR. BY EARLY FRIDAY...DEEP MOISTURE WILL HAVE SHIFTED EAST OF THE AREA AS RELATIVELY STRONG SHORTWAVE DEPARTS. COOL NORTHEASTERLY SURFACE FLOW EARLY SHOULD SHIFT TO SOUTHEASTERLY LATE FRIDAY CAUSING A RETURN OF LOW LEVEL MOISTURE AND HIGHER THETA-E VALUES. SOME CONVECTION MAY DEVELOP FRIDAY AND FRIDAY EVENING IN THE VICINITY OF LEE TROUGH / SURFACE CONVERGENCE OVER THE WESTERN PORTION OF THE AREA. SIGNIFICANT FORCING IS ABSENT AND A RELATIVELY DRY COLUMN WITH DEEP MIXED LAYER WILL LIKELY LIMIT COVERAGE OF CONVECTION. ON SATURDAY...MOISTURE INCREASES FURTHER AND MID/UPPER FLOW STRENGTHENS. LEE TROUGH SHARPENS AND MODELS INDICATE ONE OR TWO SMALL PERTURBATIONS IN THE WESTERLY FLOW ALOFT...ALL OF WHICH SUPPORTS A BETTER CHANCE OF CONVECTION ACROSS THE AREA. GFS IS MORE PROGRESSIVE FOR SUNDAY AND MONDAY SHOWING DEEP MIXING ACROSS THE WESTERN HALF OF THE AREA SUNDAY WITH CONVECTION CONFINED TO THE EASTERN PORTION OF THE AREA WHERE BETTER MOISTURE RESIDES. ECMWF HAS THE UPPER RIDGE AXIS FURTHER WEST AND THE GFS ENSEMBLE MEAN IS IN BETWEEN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1144 AM MDT TUE AUG 6 2013 SCATTERED THUNDERSTORMS WILL DEVELOP ALONG TROUGH AXIS OVER NW KS/SW NE THIS AFTERNOON AND INCREASE IN COVERAGE THROUGH THIS EVENING AS THE ACTIVITY TRANSITIONS EAST. CURRENTLY COVERAGE IS STILL TOO MUCH OF A QUESTION AT EITHER TERMINAL WITH BETTER CHANCES FURTHER SOUTH AND EAST...SO I LIMITED MENTION TO VCTS. LATE TONIGHT FOG/STRATUS IS EXPECTED TO REDEVELOP...WITH LOWER CIGS/VIS AT BOTH TERMINALS BY SUNRISE. GUIDANCE CURRENTLY SUPPORTS MVFR CONDITIONS...HOWEVER CONSIDERING THE MOIST NATURE OF THE AIRMASS IF WINDS GO COMPLETELY CALM WE COULD SEE LOWER CONDITIONS DEVELOP. FOR NOW I CHOSE TO STAY IN LINE WITH CURRENT GUIDANCE...HOWEVER WE WILL NEED TO MONITOR THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...BRB AVIATION...DR
AREA FORECAST DISCUSSION
NWS JACKSON KY
1102 PM EDT WED AUG 7 2013 .UPDATE... ISSUED AT 1102 PM EDT WED AUG 7 2013 RAIN IS STARTING TO PUSH INTO AREAS FROM MOUNT STERLING TO MOUNT VERNON...BUT IS BEGINNING TO FALL APART. HRRR SEEMS TO HAVE A GOOD HANDLE ON THIS TREND WITH THE CURRENT COMPLEX COLLAPSING WITH VERY LITTLE FOR THE REST OF THE NIGHT. UPDATE HAS BEEN SENT. UPDATE ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED ACROSS EASTERN KENTUCKY. HAVE SEEN SOME NEW DEVELOPMENT OUT WEST OF LEXINGTON. THIS ACTIVITY COULD MAKE IT INTO THE I-75 CORRIDOR OVER THE NEXT FEW HOURS...BUT STILL SOME QUESTION IF THIS WILL MAKE IT INTO AREAS FURTHER EAST. FOR NOW...GOING TO DOWNPLAY POPS FOR THE REST OF THE NIGHT GIVEN THE CURRENT LACK OF ORGANIZED ACTIVITY. LATEST HRRR HAS ALMOST NO SHOWER OR THUNDERSTORM ACTIVITY ACROSS THE AREA UNTIL 11Z. THUS...THE DOWNWARD TREND IN POPS SEEMS REASONABLE. CAN`T IGNORE THOSE HIGH PW`S NEAR 2 LATER TONIGHT...SO IT WON`T TAKE MUCH TO GET SOME LOCALLY HEAVY RAIN...BUT STILL PLANNING TO PUSH ANY MENTION UNTIL AFTER 12Z. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 315 PM EDT WED AUG 7 2013 AFTER INITIAL ROUND OF SHOWERS AND A FEW THUNDERSTORMS THIS MORNING CONVECTION HAS REMAINED LIMITED THIS AFTERNOON...WITH MOSTLY SCATTERED SHOWERS...AND VERY LITTLE THUNDER. CLOUD COVER HAS INHIBITED DESTABILIZATION AND WITH LOSS OF DAYTIME HEATING EXPECT CONVECTION TO DIMINISH EVEN FURTHER THIS EVENING. HOWEVER THIS WILL BE TEMPORARY...WITH A MID LEVEL SHORT WAVE TROUGH MOVING EAST TONIGHT...AND A LOW LEVEL JET AT 8H IMPINGING ON EASTERN KY AFTER 06Z. AT THE SAME TIME EXPECT A SURFACE WAVE OF LOW PRESSURE TO TREK ALONG THE SURFACE FRONT TO THE NORTHWEST OF THE FORECAST AREA THURSDAY MORNING. THERE IS GOOD MODEL AGREEMENT WITH INCREASING THREAT OF SHOWERS AND THUNDERSTORMS LATE TONIGHT INTO THE DAY ON THURSDAY. DETERMINISTIC MODELS ALONG WITH THE SERF ARE POINTING TOWARDS PRECIPITABLE WATER IN EXCESS OF 2 INCHES BY THURSDAY MORNING. PRECIPITABLE WATER SHOULD APPROACH OR EXCEED THE 99TH PERCENTILE. BASED ON THIS WILL ADD THE THREAT OF HEAVY RAIN TO THE THURSDAY FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. WITH ALL THIS IN MIND WILL INCREASE RAIN PROBABILITIES LATE TONIGHT TO LIKELY IN THE WEST...THEN LIKELY ACROSS THE ENTIRE AREA ON THURSDAY...BEFORE DECREASING CHANCES AGAIN LATE IN THE DAY THURSDAY. WITH THE FRONT STALLING SOMEWHERE IN THE OH VALLEY...THE TREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THURSDAY NIGHT. THERE IS LESS MODEL AGREEMENT ON THE TIMING OF THE NEXT SHORT WAVE WHICH WOULD TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS BUT FOR FOR NOW WILL CONTINUE THE PREVIOUS FORECAST IDEA OF INCREASING CHANCES AGAIN LATE THURSDAY NIGHT. HIGH DEWPOINTS WILL KEEP MINIMUM TEMPERATURES AROUND 70 TONIGHT AND AGAIN THURSDAY NIGHT. WITH RAIN AND CLOUD IN THE FORECAST ON THURSDAY...WILL GO WITH HIGHS IN THE LOWER 80S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 358 PM EDT WED AUG 7 2013 UNSETTLED WEATHER WILL CONTINUE INTO THE LONG TERM PERIOD. THE PERIOD SHOULD BEGIN WITH A NEARLY STATIONARY BOUNDARY ACROSS THE OH VALLEY EXTENDING SOUTHWEST INTO THE OH VALLEY FROM LOW PRESSURE OVER QUEBEC. THERE MAY BE A WAVE OR SERIES OF SFC WAVES ALONG THE BOUNDARY TO OUR WEST AT THAT POINT AS DISTURBANCES MOVING INTO THE REGION. AT THE START OF THE PERIOD UPPER LEVEL RIDGING IS EXPECTED TO EXTEND ACROSS THE SOUTHERN STATES AND NORTH INTO THE ROCKIES. AN UPPER LEVEL LOW SHOULD BE ROTATING TO THE NORTH OF THE GREAT LAKES FROM ONTARIO. THERE WILL PROBABLY BE SOME SHORTWAVES ROTATING TOWARD THE LOWER OH VALLEY FROM THE PLAINS...BUT THERE ARE MODEL DIFFERENCES IN TIMING. THE MODELS GRADUALLY SAG THE BOUNDARY SOUTH OF THE OH RIVER AND EVENTUALLY INTO THE JKL CWA AND STRING IT OUT MORE WEST TO EAST AS THE UPPER LOW WORKS TOWARD THE MARITIMES OVER THE WEEKEND. FROM EARLY TO THE MIDDLE PART OF NEXT WEEK...THE TROUGH SHOULD DEEPEN AGAIN OVER EASTERN CANADA AND THE NORTHEAST AS ANOTHER UPPER LEVEL LOW ROTATES FROM THE HUDSON BAY REGION NORTH OF THE GREAT LAKES AND TOWARD THE MARITIMES. THE MODEL CONSENSUS FROM EARLY TO THE MIDDLE PART OF NEXT WEEK IS FOR MORE AMPLIFIED PATTERN WITH THE BOUNDARY PUSHING SOUTH OF THE AREA...BUT WEST NORTHWEST UPPER FLOW SHOULD REMAIN. DISTURBANCES IN THIS FLOW WILL STILL KEEP A THREAT OF CONVECTION IN THE PICTURE FOR AT LEAST MON AND TUE...ESPECIALLY EACH AFTERNOON AND EVENING. ENOUGH DRIER AIR MAY WORK INTO THE REGION LATE IN THE PERIOD IF THE 12Z ECMWF VERIFIES FOR DRY WEATHER ON WEDNESDAY OR TUESDAY AND WEDNESDAY. HOWEVER...MODEL TO MODEL DIFFERENCES AND RUN TO RUN DIFFERENCE REMAIN AND THE EXTENDED GRID LOAD OF ISOLATED TO SCATTERED POPS WAS REASONABLE. PW WILL REMAIN VERY HIGH ABOVE THE 90TH TO 95TH PERCENTILE RANGE INTO EARLY IN THE PERIOD AHEAD OF THE BOUNDARY. THERE IS THE POTENTIAL FOR ANY CONVECTION TO HAVE DEEP WARM CLOUD DEPTH AND THEY COULD PRODUCE AT LEAST LOCALLY HEAVY RAIN. TIMING AND STRENGTH OF PASSING UPPER LEVEL SHORTWAVES WILL BE A KEY INGREDIENT AND CONFIDENCE IN THIS IS NOT HIGH AT THIS POINT. HOWEVER...WE WILL HIGHLIGHT THIS IN THE HWO. TEMPERATURES THROUGH THE PERIOD SHOULD REMAIN NEAR IF NOT A BIT BELOW NORMAL FOR DAYTIME HIGHS WITH OVERNIGHT LOWS EARLY IN THE PERIOD A BIT ABOVE NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWERS HAVE DIMINISHED ACROSS EASTERN KENTUCKY AND TAFS WILL ALL START OFF VFR. WITH LOTS OF LOW LEVEL MOISTURE PRESENT...SOME STRATUS SHOULD DEVELOP OVERNIGHT...MUCH LIKE LAST NIGHT. IN ADDITION SOME RAIN COULD START TO INVADE THE AREA TOWARDS DAYBREAK. WITH CLOUD COVER FAIRLY HIGH TONIGHT...NO FOG EXPECTED AT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...SBH LONG TERM...JP AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
746 PM EDT WED AUG 7 2013 .UPDATE... ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED ACROSS EASTERN KENTUCKY. HAVE SEEN SOME NEW DEVELOPMENT OUT WEST OF LEXINGTON. THIS ACTIVITY COULD MAKE IT INTO THE I-75 CORRIDOR OVER THE NEXT FEW HOURS...BUT STILL SOME QUESTION IF THIS WILL MAKE IT INTO AREAS FURTHER EAST. FOR NOW...GOING TO DOWNPLAY POPS FOR THE REST OF THE NIGHT GIVEN THE CURRENT LACK OF ORGANIZED ACTIVITY. LATEST HRRR HAS ALMOST NO SHOWER OR THUNDERSTORM ACTIVITY ACROSS THE AREA UNTIL 11Z. THUS...THE DOWNWARD TREND IN POPS SEEMS REASONABLE. CAN`T IGNORE THOSE HIGH PW`S NEAR 2 LATER TONIGHT...SO IT WON`T TAKE MUCH TO GET SOME LOCALLY HEAVY RAIN...BUT STILL PLANNING TO PUSH ANY MENTION UNTIL AFTER 12Z. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 315 PM EDT WED AUG 7 2013 AFTER INITIAL ROUND OF SHOWERS AND A FEW THUNDERSTORMS THIS MORNING CONVECTION HAS REMAINED LIMITED THIS AFTERNOON...WITH MOSTLY SCATTERED SHOWERS...AND VERY LITTLE THUNDER. CLOUD COVER HAS INHIBITED DESTABILIZATION AND WITH LOSS OF DAYTIME HEATING EXPECT CONVECTION TO DIMINISH EVEN FURTHER THIS EVENING. HOWEVER THIS WILL BE TEMPORARY...WITH A MID LEVEL SHORT WAVE TROUGH MOVING EAST TONIGHT...AND A LOW LEVEL JET AT 8H IMPINGING ON EASTERN KY AFTER 06Z. AT THE SAME TIME EXPECT A SURFACE WAVE OF LOW PRESSURE TO TREK ALONG THE SURFACE FRONT TO THE NORTHWEST OF THE FORECAST AREA THURSDAY MORNING. THERE IS GOOD MODEL AGREEMENT WITH INCREASING THREAT OF SHOWERS AND THUNDERSTORMS LATE TONIGHT INTO THE DAY ON THURSDAY. DETERMINISTIC MODELS ALONG WITH THE SERF ARE POINTING TOWARDS PRECIPITABLE WATER IN EXCESS OF 2 INCHES BY THURSDAY MORNING. PRECIPITABLE WATER SHOULD APPROACH OR EXCEED THE 99TH PERCENTILE. BASED ON THIS WILL ADD THE THREAT OF HEAVY RAIN TO THE THURSDAY FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. WITH ALL THIS IN MIND WILL INCREASE RAIN PROBABILITIES LATE TONIGHT TO LIKELY IN THE WEST...THEN LIKELY ACROSS THE ENTIRE AREA ON THURSDAY...BEFORE DECREASING CHANCES AGAIN LATE IN THE DAY THURSDAY. WITH THE FRONT STALLING SOMEWHERE IN THE OH VALLEY...THE TREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THURSDAY NIGHT. THERE IS LESS MODEL AGREEMENT ON THE TIMING OF THE NEXT SHORT WAVE WHICH WOULD TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS BUT FOR FOR NOW WILL CONTINUE THE PREVIOUS FORECAST IDEA OF INCREASING CHANCES AGAIN LATE THURSDAY NIGHT. HIGH DEWPOINTS WILL KEEP MINIMUM TEMPERATURES AROUND 70 TONIGHT AND AGAIN THURSDAY NIGHT. WITH RAIN AND CLOUD IN THE FORECAST ON THURSDAY...WILL GO WITH HIGHS IN THE LOWER 80S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 358 PM EDT WED AUG 7 2013 UNSETTLED WEATHER WILL CONTINUE INTO THE LONG TERM PERIOD. THE PERIOD SHOULD BEGIN WITH A NEARLY STATIONARY BOUNDARY ACROSS THE OH VALLEY EXTENDING SOUTHWEST INTO THE OH VALLEY FROM LOW PRESSURE OVER QUEBEC. THERE MAY BE A WAVE OR SERIES OF SFC WAVES ALONG THE BOUNDARY TO OUR WEST AT THAT POINT AS DISTURBANCES MOVING INTO THE REGION. AT THE START OF THE PERIOD UPPER LEVEL RIDGING IS EXPECTED TO EXTEND ACROSS THE SOUTHERN STATES AND NORTH INTO THE ROCKIES. AN UPPER LEVEL LOW SHOULD BE ROTATING TO THE NORTH OF THE GREAT LAKES FROM ONTARIO. THERE WILL PROBABLY BE SOME SHORTWAVES ROTATING TOWARD THE LOWER OH VALLEY FROM THE PLAINS...BUT THERE ARE MODEL DIFFERENCES IN TIMING. THE MODELS GRADUALLY SAG THE BOUNDARY SOUTH OF THE OH RIVER AND EVENTUALLY INTO THE JKL CWA AND STRING IT OUT MORE WEST TO EAST AS THE UPPER LOW WORKS TOWARD THE MARITIMES OVER THE WEEKEND. FROM EARLY TO THE MIDDLE PART OF NEXT WEEK...THE TROUGH SHOULD DEEPEN AGAIN OVER EASTERN CANADA AND THE NORTHEAST AS ANOTHER UPPER LEVEL LOW ROTATES FROM THE HUDSON BAY REGION NORTH OF THE GREAT LAKES AND TOWARD THE MARITIMES. THE MODEL CONSENSUS FROM EARLY TO THE MIDDLE PART OF NEXT WEEK IS FOR MORE AMPLIFIED PATTERN WITH THE BOUNDARY PUSHING SOUTH OF THE AREA...BUT WEST NORTHWEST UPPER FLOW SHOULD REMAIN. DISTURBANCES IN THIS FLOW WILL STILL KEEP A THREAT OF CONVECTION IN THE PICTURE FOR AT LEAST MON AND TUE...ESPECIALLY EACH AFTERNOON AND EVENING. ENOUGH DRIER AIR MAY WORK INTO THE REGION LATE IN THE PERIOD IF THE 12Z ECMWF VERIFIES FOR DRY WEATHER ON WEDNESDAY OR TUESDAY AND WEDNESDAY. HOWEVER...MODEL TO MODEL DIFFERENCES AND RUN TO RUN DIFFERENCE REMAIN AND THE EXTENDED GRID LOAD OF ISOLATED TO SCATTERED POPS WAS REASONABLE. PW WILL REMAIN VERY HIGH ABOVE THE 90TH TO 95TH PERCENTILE RANGE INTO EARLY IN THE PERIOD AHEAD OF THE BOUNDARY. THERE IS THE POTENTIAL FOR ANY CONVECTION TO HAVE DEEP WARM CLOUD DEPTH AND THEY COULD PRODUCE AT LEAST LOCALLY HEAVY RAIN. TIMING AND STRENGTH OF PASSING UPPER LEVEL SHORTWAVES WILL BE A KEY INGREDIENT AND CONFIDENCE IN THIS IS NOT HIGH AT THIS POINT. HOWEVER...WE WILL HIGHLIGHT THIS IN THE HWO. TEMPERATURES THROUGH THE PERIOD SHOULD REMAIN NEAR IF NOT A BIT BELOW NORMAL FOR DAYTIME HIGHS WITH OVERNIGHT LOWS EARLY IN THE PERIOD A BIT ABOVE NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWERS HAVE DIMINISHED ACROSS EASTERN KENTUCKY AND TAFS WILL ALL START OFF VFR. WITH LOTS OF LOW LEVEL MOISTURE PRESENT...SOME STRATUS SHOULD DEVELOP OVERNIGHT...MUCH LIKE LAST NIGHT. IN ADDITION SOME RAIN COULD START TO INVADE THE AREA TOWARDS DAYBREAK. WITH CLOUD COVER FAIRLY HIGH TONIGHT...NO FOG EXPECTED AT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...SBH LONG TERM...JP AVIATION...KAS
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1213 PM EDT TUE AUG 6 2013 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE COULD TRIGGER A SHOWER OR THUNDERSTORM THIS AFTERNOON. OTHERWISE, HIGH PRESSURE WILL BUILD ACROSS THE AREA TODAY AND MOVE EAST OF THE REGION ON WEDNESDAY AS ANOTHER FRONT APPROACHES FROM THE SOUTHWEST. && .NEAR TERM /THROUGH TONIGHT/... NOON UPDATE...CUMULUS HAVE FORMED ACROSS MANY AREAS. MODIFIED CLOUDS COVER TO GO PARTLY CLOUDY IN NORTH CENTRAL AND WESTERN AREAS WITH CUMULUS CLOUDS. REST OF THE FORECAST REMAINS ON TRACK. PREVIOUS DISCUSSION... DRIER AND MILDER TODAY. A WEAK RIDGE OF HIGH PRES AT THE SFC IS SET TO MOVE OVER THE REGION TODAY INTO TONIGHT. DRIER WEATHER W/MORE SUNSHINE WILL BE SEEN TODAY W/TEMPERATURES RESPONDING INTO THE MID AND UPPER 70S. THE CAVEAT TO THIS HOWEVER WILL BE A WEAK S/WV IN THE UPPER LEVELS THAT WILL MOVE ACROSS THE STATE THIS AFTERNOON. THIS FEATURE IS PICKED UP WELL BY THE 00Z NAM AND CANADIAN GEM PER 06Z ANALYSIS OVER ONTARIO. IR SATL IMAGERY SHOWED SOME MID/HIGH CLOUDS ASSOCIATED W/THIS FEATURE MOVING INTO WESTERN AND NORTHERN NYS. GFS/NAM SOUNDINGS AS WELL AS THE GEM SHOW SOME MOISTURE AT THE 850MB LEVEL W/THE MAJORITY OF THE RH ABOVE 700MBS. LATEST TRAJECTORIES BRING SOME CLOUDINESS`S ACROSS PORTIONS OF WESTERN AND NORTHERN AREAS TODAY. SOUNDINGS DO INDICATE SOME INSTABILITY AS LIS DROP TO -1 TO -3 AND SBCAPES HIT CLOSE TO 500 JOULES. THERE IS SOME WEAK SHEAR AT 0-6KM OF 15 KTS OR SO. 850-700MB LAPSE RATES FROM THE NAM ARE CLOSE TO 7.0 C/KM AND SOME LLVL CONVERGENCE NOTED. ALL THIS COULD BE ENOUGH TO TRIGGER SOME ISOLD SHOWERS OR PERHAPS A TSTM MAINLY FOR THE WESTERN AND NWRN AREAS. THE NAM AND GFS HINT AT THIS TO SET UP. EVEN THE 06Z HRRR SHOWS WIDELY SCATTERED TO ISOLD PRECIP. THEREFORE, DECIDED TO ADD THE MENTION OF A SHOWER OR POSSIBLE TSTM INTO LATE AFTERNOON(20%). ACTIVITY WILL WIND DOWN IN THE EVENING AS THE S/WV MOVES TO THE E AND LOSS OF HEATING. HIGH PRES IN THE GULF OF MAINE WILL RIDGE OVER THE REGION TONIGHT. CLEARING SKIES AND COOLER TEMPERATURES WILL ALLOW FOR SOME FOG TO DEVELOP. OVERNIGHT LOWS ARE EXPECTED TO DROP BACK INTO THE UPPER 40S ACROSS THE N AND NW WHILE LOWER 50S SHOULD DO IT FOR CENTRAL AND DOWNEAST AREAS.SATURATED GROUND AND DAYTIME HEATING WILL AID IN THE FOG DEVELOPMENT. ATTM, WENT W/PATCHY FOG. DAYCREW CAN ASSESS THIS FURTHER TODAY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE EAST OF THE REGION DURING WEDNESDAY. AFTER A MAINLY SUNNY START TO THE DAY EXPECT INCREASING HIGH CLOUDS IN ADVANCE OF THE NEXT TROF APPROACHING FROM THE WEST. THE MAIN CHANGE TO THE WEDNESDAY FORECAST WAS TO DELAY THE ONSET OF ANY SHOWERS GETTING INTO THE WESTERN AREAS UNTIL WEDNESDAY EVENING. HIGH TEMPERATURES ON WEDNESDAY WILL BE CLOSE TO NORMAL FOR THIS TIME OF YEAR WITH MID 70S TO NEAR 80 DEGREES ACROSS THE REGION. CLOUDS WILL CONTINUE TO INCREASE WEDNESDAY NIGHT WITH SHOWERS DEVELOPING FROM WEST TO EAST AFTER MIDNIGHT IN ADVANCE OF AN APPROACHING WARM FRONT. LOWS WEDNESDAY NIGHT ARE EXPECTED TO RANGE FROM THE MID TO UPPER 50S ACROSS THE REGION. SHOWERS WILL CONTINUE TO BE LIKELY ON THURSDAY IN ADVANCE OF THE APPROACHING COLD FRONT. HIGH TEMPERATURES ON THURSDAY WILL BE A BIT BELOW NORMAL FOR THIS TIME OF YEAR DUE TO THE COMBINATION OF CLOUDS AND SHOWERS. HIGHS WILL RANGE FROM THE UPPER 60S TO NEAR 70 DEGREES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THE WEAK SURFACE COLD FRONT WILL SLOWLY CROSS THE REGION THURSDAY NIGHT WITH SHOWERS TAPERING OFF FROM WEST TO EAST AFTER MIDNIGHT. THE WEAKENING FRONT WILL STALL NEAR OR ALONG THE COAST LATER THURSDAY NIGHT AND FRIDAY. LATEST MODEL GUIDANCE SUGGESTS FRIDAY MAY BE A MAINLY DRY ALTHOUGH MOSTLY CLOUDY DAY. A VIGOROUS 500MB LOW WILL MOVE EAST INTO QUEBEC LATER FRIDAY AND SATURDAY. MODELS DIVERGE ON THE OVERALL SENSIBLE WEATHER FOR LATER FRIDAY NIGHT AND INTO SATURDAY. THE 00Z OP RUN OF THE GFS DEVELOPS A COMPACT SURFACE LOW ACROSS NYS FRIDAY NIGHT AND THEN TRACKS IT ACROSS NEW ENGLAND AND ACROSS DOWNEAST MAINE FRIDAY NIGHT. 00Z EC IS FURTHER SOUTH AND WEAKER WITH THE LOW KEEPING THE REGION MAINLY DRY. FOR NOW HAVE KEPT CONTINUITY WITH GOING FORECAST AND WENT WITH LOW CHANCE POPS FRIDAY NIGHT AND INTO SATURDAY. COOLER AND DRIER AIR WILL WILL FOLLOW FOR LATE WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPERATURES AVERAGING BELOW SEASONAL FOR THIS TIME OF YEAR. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR THROUGH TONIGHT FOR ALL TERMINALS. THERE IS POTENTIAL FOR SOME FOG TO DEVELOP LATE TONIGHT MAINLY ACROSS THE NORTHERN TERMINALS DUE TO THE WET GROUND AND CLEARING. CONDITIONS COULD BRIEFLY DROP TO MVFR OR PERHAPS IFR BY EARLY WEDNESDAY MORNING. SHORT TERM: VFR WEDNESDAY. MVFR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT IN SHOWERS. VFR FRIDAY AND SATURDAY. && .MARINE... NEAR TERM: NO HEADLINES THIS TERM. WINDS WILL TURN TO THE SW LATER TODAY AND AVERAGE 10 KT OR SO. WAVE HEIGHTS WILL STAY AT 2-3 FT MAINLY AWAY FROM THE INTRA-COASTAL ZONE. SHORT TERM: WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS FOR THIS TERM. && .MARINE... NEAR TERM: SHORT TERM: && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...BLOOMER
AREA FORECAST DISCUSSION
NWS CARIBOU ME
921 AM EDT TUE AUG 6 2013 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE COULD TRIGGER A SHOWER OR THUNDERSTORM THIS AFTERNOON. OTHERWISE, HIGH PRESSURE WILL BUILD ACROSS THE AREA TODAY AND MOVE EAST OF THE REGION ON WEDNESDAY AS ANOTHER FRONT APPROACHES FROM THE SOUTHWEST. && .NEAR TERM /THROUGH TONIGHT/... 9:00 AM UPDATE...BROUGHT TEMPS UP A DEGREE AND MADE SKIES MOSTLY CLEAR ACROSS THE AREA WITH PLENTY OF SUNSHINE AROUND. EXPECT A FEW CUMULUS TO DEVELOP THROUGH MIDDAY. AN ISOLATED THUNDERSHOWER IS POSSIBLE IN SOME SPOTS. PREVIOUS DISCUSSION... DRIER AND MILDER TODAY. A WEAK RIDGE OF HIGH PRES AT THE SFC IS SET TO MOVE OVER THE REGION TODAY INTO TONIGHT. DRIER WEATHER W/MORE SUNSHINE WILL BE SEEN TODAY W/TEMPERATURES RESPONDING INTO THE MID AND UPPER 70S. THE CAVEAT TO THIS HOWEVER WILL BE A WEAK S/WV IN THE UPPER LEVELS THAT WILL MOVE ACROSS THE STATE THIS AFTERNOON. THIS FEATURE IS PICKED UP WELL BY THE 00Z NAM AND CANADIAN GEM PER 06Z ANALYSIS OVER ONTARIO. IR SATL IMAGERY SHOWED SOME MID/HIGH CLOUDS ASSOCIATED W/THIS FEATURE MOVING INTO WESTERN AND NORTHERN NYS. GFS/NAM SOUNDINGS AS WELL AS THE GEM SHOW SOME MOISTURE AT THE 850MB LEVEL W/THE MAJORITY OF THE RH ABOVE 700MBS. LATEST TRAJECTORIES BRING SOME CLOUDINESS`S ACROSS PORTIONS OF WESTERN AND NORTHERN AREAS TODAY. SOUNDINGS DO INDICATE SOME INSTABILITY AS LIS DROP TO -1 TO -3 AND SBCAPES HIT CLOSE TO 500 JOULES. THERE IS SOME WEAK SHEAR AT 0-6KM OF 15 KTS OR SO. 850-700MB LAPSE RATES FROM THE NAM ARE CLOSE TO 7.0 C/KM AND SOME LLVL CONVERGENCE NOTED. ALL THIS COULD BE ENOUGH TO TRIGGER SOME ISOLD SHOWERS OR PERHAPS A TSTM MAINLY FOR THE WESTERN AND NWRN AREAS. THE NAM AND GFS HINT AT THIS TO SET UP. EVEN THE 06Z HRRR SHOWS WIDELY SCATTERED TO ISOLD PRECIP. THEREFORE, DECIDED TO ADD THE MENTION OF A SHOWER OR POSSIBLE TSTM INTO LATE AFTERNOON(20%). ACTIVITY WILL WIND DOWN IN THE EVENING AS THE S/WV MOVES TO THE E AND LOSS OF HEATING. HIGH PRES IN THE GULF OF MAINE WILL RIDGE OVER THE REGION TONIGHT. CLEARING SKIES AND COOLER TEMPERATURES WILL ALLOW FOR SOME FOG TO DEVELOP. OVERNIGHT LOWS ARE EXPECTED TO DROP BACK INTO THE UPPER 40S ACROSS THE N AND NW WHILE LOWER 50S SHOULD DO IT FOR CENTRAL AND DOWNEAST AREAS.SATURATED GROUND AND DAYTIME HEATING WILL AID IN THE FOG DEVELOPMENT. ATTM, WENT W/PATCHY FOG. DAYCREW CAN ASSESS THIS FURTHER TODAY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE EAST OF THE REGION DURING WEDNESDAY. AFTER A MAINLY SUNNY START TO THE DAY EXPECT INCREASING HIGH CLOUDS IN ADVANCE OF THE NEXT TROF APPROACHING FROM THE WEST. THE MAIN CHANGE TO THE WEDNESDAY FORECAST WAS TO DELAY THE ONSET OF ANY SHOWERS GETTING INTO THE WESTERN AREAS UNTIL WEDNESDAY EVENING. HIGH TEMPERATURES ON WEDNESDAY WILL BE CLOSE TO NORMAL FOR THIS TIME OF YEAR WITH MID 70S TO NEAR 80 DEGREES ACROSS THE REGION. CLOUDS WILL CONTINUE TO INCREASE WEDNESDAY NIGHT WITH SHOWERS DEVELOPING FROM WEST TO EAST AFTER MIDNIGHT IN ADVANCE OF AN APPROACHING WARM FRONT. LOWS WEDNESDAY NIGHT ARE EXPECTED TO RANGE FROM THE MID TO UPPER 50S ACROSS THE REGION. SHOWERS WILL CONTINUE TO BE LIKELY ON THURSDAY IN ADVANCE OF THE APPROACHING COLD FRONT. HIGH TEMPERATURES ON THURSDAY WILL BE A BIT BELOW NORMAL FOR THIS TIME OF YEAR DUE TO THE COMBINATION OF CLOUDS AND SHOWERS. HIGHS WILL RANGE FROM THE UPPER 60S TO NEAR 70 DEGREES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THE WEAK SURFACE COLD FRONT WILL SLOWLY CROSS THE REGION THURSDAY NIGHT WITH SHOWERS TAPERING OFF FROM WEST TO EAST AFTER MIDNIGHT. THE WEAKENING FRONT WILL STALL NEAR OR ALONG THE COAST LATER THURSDAY NIGHT AND FRIDAY. LATEST MODEL GUIDANCE SUGGESTS FRIDAY MAY BE A MAINLY DRY ALTHOUGH MOSTLY CLOUDY DAY. A VIGOROUS 500MB LOW WILL MOVE EAST INTO QUEBEC LATER FRIDAY AND SATURDAY. MODELS DIVERGE ON THE OVERALL SENSIBLE WEATHER FOR LATER FRIDAY NIGHT AND INTO SATURDAY. THE 00Z OP RUN OF THE GFS DEVELOPS A COMPACT SURFACE LOW ACROSS NYS FRIDAY NIGHT AND THEN TRACKS IT ACROSS NEW ENGLAND AND ACROSS DOWNEAST MAINE FRIDAY NIGHT. 00Z EC IS FURTHER SOUTH AND WEAKER WITH THE LOW KEEPING THE REGION MAINLY DRY. FOR NOW HAVE KEPT CONTINUITY WITH GOING FORECAST AND WENT WITH LOW CHANCE POPS FRIDAY NIGHT AND INTO SATURDAY. COOLER AND DRIER AIR WILL WILL FOLLOW FOR LATE WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPERATURES AVERAGING BELOW SEASONAL FOR THIS TIME OF YEAR. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR THROUGH TONIGHT FOR ALL TERMINALS. THERE IS POTENTIAL FOR SOME FOG TO DEVELOP LATE TONIGHT MAINLY ACROSS THE NORTHERN TERMINALS DUE TO THE WET GROUND AND CLEARING. CONDITIONS COULD BRIEFLY DROP TO MVFR OR PERHAPS IFR BY EARLY WEDNESDAY MORNING. SHORT TERM: VFR WEDNESDAY. MVFR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT IN SHOWERS. VFR FRIDAY AND SATURDAY. && .MARINE... NEAR TERM: NO HEADLINES THIS TERM. WINDS WILL TURN TO THE SW LATER TODAY AND AVERAGE 10 KT OR SO. WAVE HEIGHTS WILL STAY AT 2-3 FT MAINLY AWAY FROM THE INTRA-COASTAL ZONE. SHORT TERM: WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS FOR THIS TERM. && .MARINE... NEAR TERM: SHORT TERM: && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...BLOOMER
AREA FORECAST DISCUSSION
NWS CARIBOU ME
643 AM EDT TUE AUG 6 2013 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE COULD TRIGGER A SHOWER OR THUNDERSTORM THIS AFTERNOON. OTHERWISE, HIGH PRESSURE WILL BUILD ACROSS THE AREA TODAY AND MOVE EAST OF THE REGION ON WEDNESDAY AS ANOTHER FRONT APPROACHES FROM THE SOUTHWEST. && .NEAR TERM /THROUGH TONIGHT/... 645 AM UPDATE: MODIFIED THE SKY AND TEMPERATURES TO BRING THEM TO THE CURRENT CONDITIONS SHOWING MAINLY CLEAR AND COOL CONDITIONS. SOME AREAS BACK ACROSS WEST AND NORTHWEST MAINE DROPPED BACK INTO THE MID AND UPPER 30S W/LOWER 40S AT ALLAGASH AND DICKEY. ELSEWHERE, READINGS WERE IN THE UPPER 40S AND LOWER 50S. EXPECTING THOSE TEMPERATURES TO REBOUND AFTER 8 AM W/THE AID OF THE SUN. PREVIOUS DISCUSSION... DRIER AND MILDER TODAY. A WEAK RIDGE OF HIGH PRES AT THE SFC IS SET TO MOVE OVER THE REGION TODAY INTO TONIGHT. DRIER WEATHER W/MORE SUNSHINE WILL BE SEEN TODAY W/TEMPERATURES RESPONDING INTO THE MID AND UPPER 70S. THE CAVEAT TO THIS HOWEVER WILL BE A WEAK S/WV IN THE UPPER LEVELS THAT WILL MOVE ACROSS THE STATE THIS AFTERNOON. THIS FEATURE IS PICKED UP WELL BY THE 00Z NAM AND CANADIAN GEM PER 06Z ANALYSIS OVER ONTARIO. IR SATL IMAGERY SHOWED SOME MID/HIGH CLOUDS ASSOCIATED W/THIS FEATURE MOVING INTO WESTERN AND NORTHERN NYS. GFS/NAM SOUNDINGS AS WELL AS THE GEM SHOW SOME MOISTURE AT THE 850MB LEVEL W/THE MAJORITY OF THE RH ABOVE 700MBS. LATEST TRAJECTORIES BRING SOME CLOUDINESS`S ACROSS PORTIONS OF WESTERN AND NORTHERN AREAS TODAY. SOUNDINGS DO INDICATE SOME INSTABILITY AS LIS DROP TO -1 TO -3 AND SBCAPES HIT CLOSE TO 500 JOULES. THERE IS SOME WEAK SHEAR AT 0-6KM OF 15 KTS OR SO. 850-700MB LAPSE RATES FROM THE NAM ARE CLOSE TO 7.0 C/KM AND SOME LLVL CONVERGENCE NOTED. ALL THIS COULD BE ENOUGH TO TRIGGER SOME ISOLD SHOWERS OR PERHAPS A TSTM MAINLY FOR THE WESTERN AND NWRN AREAS. THE NAM AND GFS HINT AT THIS TO SET UP. EVEN THE 06Z HRRR SHOWS WIDELY SCATTERED TO ISOLD PRECIP. THEREFORE, DECIDED TO ADD THE MENTION OF A SHOWER OR POSSIBLE TSTM INTO LATE AFTERNOON(20%). ACTIVITY WILL WIND DOWN IN THE EVENING AS THE S/WV MOVES TO THE E AND LOSS OF HEATING. HIGH PRES IN THE GULF OF MAINE WILL RIDGE OVER THE REGION TONIGHT. CLEARING SKIES AND COOLER TEMPERATURES WILL ALLOW FOR SOME FOG TO DEVELOP. OVERNIGHT LOWS ARE EXPECTED TO DROP BACK INTO THE UPPER 40S ACROSS THE N AND NW WHILE LOWER 50S SHOULD DO IT FOR CENTRAL AND DOWNEAST AREAS.SATURATED GROUND AND DAYTIME HEATING WILL AID IN THE FOG DEVELOPMENT. ATTM, WENT W/PATCHY FOG. DAYCREW CAN ASSESS THIS FURTHER TODAY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE EAST OF THE REGION DURING WEDNESDAY. AFTER A MAINLY SUNNY START TO THE DAY EXPECT INCREASING HIGH CLOUDS IN ADVANCE OF THE NEXT TROF APPROACHING FROM THE WEST. THE MAIN CHANGE TO THE WEDNESDAY FORECAST WAS TO DELAY THE ONSET OF ANY SHOWERS GETTING INTO THE WESTERN AREAS UNTIL WEDNESDAY EVENING. HIGH TEMPERATURES ON WEDNESDAY WILL BE CLOSE TO NORMAL FOR THIS TIME OF YEAR WITH MID 70S TO NEAR 80 DEGREES ACROSS THE REGION. CLOUDS WILL CONTINUE TO INCREASE WEDNESDAY NIGHT WITH SHOWERS DEVELOPING FROM WEST TO EAST AFTER MIDNIGHT IN ADVANCE OF AN APPROACHING WARM FRONT. LOWS WEDNESDAY NIGHT ARE EXPECTED TO RANGE FROM THE MID TO UPPER 50S ACROSS THE REGION. SHOWERS WILL CONTINUE TO BE LIKELY ON THURSDAY IN ADVANCE OF THE APPROACHING COLD FRONT. HIGH TEMPERATURES ON THURSDAY WILL BE A BIT BELOW NORMAL FOR THIS TIME OF YEAR DUE TO THE COMBINATION OF CLOUDS AND SHOWERS. HIGHS WILL RANGE FROM THE UPPER 60S TO NEAR 70 DEGREES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THE WEAK SURFACE COLD FRONT WILL SLOWLY CROSS THE REGION THURSDAY NIGHT WITH SHOWERS TAPERING OFF FROM WEST TO EAST AFTER MIDNIGHT. THE WEAKENING FRONT WILL STALL NEAR OR ALONG THE COAST LATER THURSDAY NIGHT AND FRIDAY. LATEST MODEL GUIDANCE SUGGESTS FRIDAY MAY BE A MAINLY DRY ALTHOUGH MOSTLY CLOUDY DAY. A VIGOROUS 500MB LOW WILL MOVE EAST INTO QUEBEC LATER FRIDAY AND SATURDAY. MODELS DIVERGE ON THE OVERALL SENSIBLE WEATHER FOR LATER FRIDAY NIGHT AND INTO SATURDAY. THE 00Z OP RUN OF THE GFS DEVELOPS A COMPACT SURFACE LOW ACROSS NYS FRIDAY NIGHT AND THEN TRACKS IT ACROSS NEW ENGLAND AND ACROSS DOWNEAST MAINE FRIDAY NIGHT. 00Z EC IS FURTHER SOUTH AND WEAKER WITH THE LOW KEEPING THE REGION MAINLY DRY. FOR NOW HAVE KEPT CONTINUITY WITH GOING FORECAST AND WENT WITH LOW CHANCE POPS FRIDAY NIGHT AND INTO SATURDAY. COOLER AND DRIER AIR WILL WILL FOLLOW FOR LATE WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPERATURES AVERAGING BELOW SEASONAL FOR THIS TIME OF YEAR. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR THROUGH TONIGHT FOR ALL TERMINALS. THERE IS POTENTIAL FOR SOME FOG TO DEVELOP LATE TONIGHT MAINLY ACROSS THE NORTHERN TERMINALS DUE TO THE WET GROUND AND CLEARING. CONDITIONS COULD BRIEFLY DROP TO MVFR OR PERHAPS IFR BY EARLY WEDNESDAY MORNING. SHORT TERM: VFR WEDNESDAY. MVFR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT IN SHOWERS. VFR FRIDAY AND SATURDAY. && .MARINE... NEAR TERM: NO HEADLINES THIS TERM. WINDS WILL TURN TO THE SW LATER TODAY AND AVERAGE 10 KT OR SO. WAVE HEIGHTS WILL STAY AT 2-3 FT MAINLY AWAY FROM THE INTRA-COASTAL ZONE. SHORT TERM: WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS FOR THIS TERM. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HEWITT SHORT TERM...DUDA LONG TERM...DUDA AVIATION...HEWITT/DUDA MARINE...HEWITT/DUDA
AREA FORECAST DISCUSSION
NWS CARIBOU ME
443 AM EDT TUE AUG 6 2013 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE COULD TRIGGER A SHOWER OR THUNDERSTORM THIS AFTERNOON. OTHERWISE, HIGH PRESSURE WILL BUILD ACROSS THE AREA TODAY AND MOVE EAST OF THE REGION ON WEDNESDAY AS ANOTHER FRONT APPROACHES FROM THE SOUTHWEST. && .NEAR TERM /THROUGH TONIGHT/... DRIER AND MILDER TODAY. A WEAK RIDGE OF HIGH PRES AT THE SFC IS SET TO MOVE OVER THE REGION TODAY INTO TONIGHT. DRIER WEATHER W/MORE SUNSHINE WILL BE SEEN TODAY W/TEMPERATURES RESPONDING INTO THE MID AND UPPER 70S. THE CAVEAT TO THIS HOWEVER WILL BE A WEAK S/WV IN THE UPPER LEVELS THAT WILL MOVE ACROSS THE STATE THIS AFTERNOON. THIS FEATURE IS PICKED UP WELL BY THE 00Z NAM AND CANADIAN GEM PER 06Z ANALYSIS OVER ONTARIO. IR SATL IMAGERY SHOWED SOME MID/HIGH CLOUDS ASSOCIATED W/THIS FEATURE MOVING INTO WESTERN AND NORTHERN NYS. GFS/NAM SOUNDINGS AS WELL AS THE GEM SHOW SOME MOISTURE AT THE 850MB LEVEL W/THE MAJORITY OF THE RH ABOVE 700MBS. LATEST TRAJECTORIES BRING SOME CLOUDINESS`S ACROSS PORTIONS OF WESTERN AND NORTHERN AREAS TODAY. SOUNDINGS DO INDICATE SOME INSTABILITY AS LIS DROP TO -1 TO -3 AND SBCAPES HIT CLOSE TO 500 JOULES. THERE IS SOME WEAK SHEAR AT 0-6KM OF 15 KTS OR SO. 850-700MB LAPSE RATES FROM THE NAM ARE CLOSE TO 7.0 C/KM AND SOME LLVL CONVERGENCE NOTED. ALL THIS COULD BE ENOUGH TO TRIGGER SOME ISOLD SHOWERS OR PERHAPS A TSTM MAINLY FOR THE WESTERN AND NWRN AREAS. THE NAM AND GFS HINT AT THIS TO SET UP. EVEN THE 06Z HRRR SHOWS WIDELY SCATTERED TO ISOLD PRECIP. THEREFORE, DECIDED TO ADD THE MENTION OF A SHOWER OR POSSIBLE TSTM INTO LATE AFTERNOON(20%). ACTIVITY WILL WIND DOWN IN THE EVENING AS THE S/WV MOVES TO THE E AND LOSS OF HEATING. HIGH PRES IN THE GULF OF MAINE WILL RIDGE OVER THE REGION TONIGHT. CLEARING SKIES AND COOLER TEMPERATURES WILL ALLOW FOR SOME FOG TO DEVELOP. OVERNIGHT LOWS ARE EXPECTED TO DROP BACK INTO THE UPPER 40S ACROSS THE N AND NW WHILE LOWER 50S SHOULD DO IT FOR CENTRAL AND DOWNEAST AREAS.SATURATED GROUND AND DAYTIME HEATING WILL AID IN THE FOG DEVELOPMENT. ATTM, WENT W/PATCHY FOG. DAYCREW CAN ASSESS THIS FURTHER TODAY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE EAST OF THE REGION DURING WEDNESDAY. AFTER A MAINLY SUNNY START TO THE DAY EXPECT INCREASING HIGH CLOUDS IN ADVANCE OF THE NEXT TROF APPROACHING FROM THE WEST. THE MAIN CHANGE TO THE WEDNESDAY FORECAST WAS TO DELAY THE ONSET OF ANY SHOWERS GETTING INTO THE WESTERN AREAS UNTIL WEDNESDAY EVENING. HIGH TEMPERATURES ON WEDNESDAY WILL BE CLOSE TO NORMAL FOR THIS TIME OF YEAR WITH MID 70S TO NEAR 80 DEGREES ACROSS THE REGION. CLOUDS WILL CONTINUE TO INCREASE WEDNESDAY NIGHT WITH SHOWERS DEVELOPING FROM WEST TO EAST AFTER MIDNIGHT IN ADVANCE OF AN APPROACHING WARM FRONT. LOWS WEDNESDAY NIGHT ARE EXPECTED TO RANGE FROM THE MID TO UPPER 50S ACROSS THE REGION. SHOWERS WILL CONTINUE TO BE LIKELY ON THURSDAY IN ADVANCE OF THE APPROACHING COLD FRONT. HIGH TEMPERATURES ON THURSDAY WILL BE A BIT BELOW NORMAL FOR THIS TIME OF YEAR DUE TO THE COMBINATION OF CLOUDS AND SHOWERS. HIGHS WILL RANGE FROM THE UPPER 60S TO NEAR 70 DEGREES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THE WEAK SURFACE COLD FRONT WILL SLOWLY CROSS THE REGION THURSDAY NIGHT WITH SHOWERS TAPERING OFF FROM WEST TO EAST AFTER MIDNIGHT. THE WEAKENING FRONT WILL STALL NEAR OR ALONG THE COAST LATER THURSDAY NIGHT AND FRIDAY. LATEST MODEL GUIDANCE SUGGESTS FRIDAY MAY BE A MAINLY DRY ALTHOUGH MOSTLY CLOUDY DAY. A VIGOROUS 500MB LOW WILL MOVE EAST INTO QUEBEC LATER FRIDAY AND SATURDAY. MODELS DIVERGE ON THE OVERALL SENSIBLE WEATHER FOR LATER FRIDAY NIGHT AND INTO SATURDAY. THE 00Z OP RUN OF THE GFS DEVELOPS A COMPACT SURFACE LOW ACROSS NYS FRIDAY NIGHT AND THEN TRACKS IT ACROSS NEW ENGLAND AND ACROSS DOWNEAST MAINE FRIDAY NIGHT. 00Z EC IS FURTHER SOUTH AND WEAKER WITH THE LOW KEEPING THE REGION MAINLY DRY. FOR NOW HAVE KEPT CONTINUITY WITH GOING FORECAST AND WENT WITH LOW CHANCE POPS FRIDAY NIGHT AND INTO SATURDAY. COOLER AND DRIER AIR WILL WILL FOLLOW FOR LATE WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPERATURES AVERAGING BELOW SEASONAL FOR THIS TIME OF YEAR. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR THROUGH TONIGHT FOR ALL TERMINALS. THERE IS POTENTIAL FOR SOME FOG TO DEVELOP LATE TONIGHT MAINLY ACROSS THE NORTHERN TERMINALS DUE TO THE WET GROUND AND CLEARING. CONDITIONS COULD BRIEFLY DROP TO MVFR OR PERHAPS IFR BY EARLY WEDNESDAY MORNING. SHORT TERM: VFR WEDNESDAY. MVFR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT IN SHOWERS. VFR FRIDAY AND SATURDAY. && .MARINE... NEAR TERM: NO HEADLINES THIS TERM. WINDS WILL TURN TO THE SW LATER TODAY AND AVERAGE 10 KT OR SO. WAVE HEIGHTS WILL STAY AT 2-3 FT MAINLY AWAY FROM THE INTRA-COASTAL ZONE. SHORT TERM: WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS FOR THIS TIME OF YEAR. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HEWITT SHORT TERM...DUDA LONG TERM...DUDA AVIATION...HEWITT/DUDA MARINE...HEWITT/DUDA
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
822 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL REMAIN PARKED OFFSHORE THROUGH THE END OF THE WEEK. SOUTHERLY RETURN FLOW AROUND THE HIGH WILL DRAW TROPICAL MOISTURE UP THE EASTERN SEABOARD. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE MID-ATLANTIC STATES FRIDAY NIGHT AND SATURDAY. HIGH PRESSURE BRIEFLY BUILDS IN LATE THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... UPDATE...CANCELLED COASTAL FLOOD ADZY FOR ANNE ARUNDEL CO. WIDESPREAD SHOWERS W/ EMBEDDED POCKETS OF HEAVIER RAIN WILL CONTINUE TO SPREAD ACROSS THE I-95 CORRIDOR. HRRR SEEMS TO HAVE THE BEST HANDLE ON THIS EVOLVING SITUATION BASED ON EARLY MORNING RADAR TRENDS. THIS ACTIVITY WILL COLLECT ALONG THE I-95 CORRIDOR AND THE CHESAPEAKE BAY REGION LATER THIS MRNG...MORE SCATTERED SHOWERS AND A FEW ISOLATED TSTMS POSSIBLE THIS AFTN/EVE. AFTER THAT WAVE SLIDES EAST OF US BY MID TO LATE MORNING. MOST MESOMODELS SHOW SCATTERED CONVECTION DEVELOPING IN THE WARM ADVECTION ENVIRONMENT FOR THE AFTERNOON AND TUE NIGHT FAIRLY EVENLY ACROSS THE FORECAST AREA. GIVEN THE WEAK AND DIFFUSE FORCING WITH THIS...AM NOT CURRENTLY ABLE TO PUT MUCH DETAIL INTO WHERE THE BEST CHANCES ARE IN TIME AND AREA. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A CLOSED LOW WILL MEANDER OVER MANITOBA WHILE AN UPPER RIDGE IS PARKED OVER THE GULF COAST STATES THRU THE SHORT-TERM PERIOD. UPPER FLOW PATTERN BETWEEN THESE TWO SYSTEMS WILL BE FAIRLY ZONAL DURING THIS TIME WITH THE MID-ATLANTIC REGION SITUATED ON SRN PERIPHERY OF STRONGER WESTERLIES. A SERIES OF SHORTWAVE DISTURBANCES WILL ROTATE AROUND THE BASE OF THE UPPER TROUGH WITHIN THIS BELT OF ENHANCED WESTERLIES DURING THE SECOND HALF OF THE WEEK. IN THE LLVLS AND AT THE SFC...SLY RETURN FLOW AROUND HIPRES OVER THE WRN ATLANTIC WILL TRANSPORT MOISTURE FROM THE CARIBBEAN UP THE ERN SEABOARD. PWATS INCREASE FROM AROUND 1.5 INCHES WED MRNG TO 2 INCHES BY THU. IT WILL NOT REQUIRE A WHOLE LOT OF FORCING FROM EACH SHORTWAVE TROUGH TO PRODUCE SHOWERS AND TSTMS IN THIS TROPICAL AIRMASS. LOWERED POPS A BIT FROM PREV FCST WITH THE BEST FORCING EXPECTED TO REMAIN NORTH AND WEST OF THE AREA DURING THE SHORT TERM. POPS CLOSELY FOLLOW DIURNAL CYCLE AND ARE HIGHEST EACH DAY DURING THE AFTN/EVE HRS. WITH EXTENSIVE CLOUD COVER OVER THE AREA...THERE IS SOME FCST UNCERTAINTY REGARDING TSTM COVERAGE...WHICH WILL DEPEND ON AMT OF DAYTIME HEATING. ANY STORMS WILL HAVE THE POTENTIAL TO PRODUCE LOCALLY HVY RAINFALL...ESPECIALLY ON THU. HUMID AIRMASS AND CLOUDS COVER WILL YIELD BELOW NORMAL HIGHS AND ABOVE NORMAL LOWS. && .LONG TERM /FRIDAY THROUGH MONDAY/... THE VERTICALLY-STACKED LOW WILL PROGRESS SLOWLY EWD ACROSS CENTRAL ONTARIO FRI. A LEADING SHORTWAVE DISTURBANCE ROTATING AROUND THE BASE OF THE LARGE-SCALE TROUGH IS FCST TO MOVE FROM THE GREAT LAKES/OH VLY TO THE NRN MID-ATLANTIC AND NORTHEAST STATES DURING THIS TIME. THIS DISTURBANCE WILL PROVIDE SOME WEAK LIFT FOR SHOWERS AND STORMS ESPECIALLY DURING THE PEAK HEATING HRS. YDA`S MODELS SHOWED A COLD FRONT BECOMING STALLED OVER THE AREA ON FRI. NOW...THE LATEST 00Z ECMWF...GFS AND ITS ENSEMBLE MEMBERS INDICATE THE BOUNDARY REMAINING NORTH OF THE AREA. GIVEN THE SLOWING TREND...POPS WERE LOWERED AND THE POTENTIAL FOR MORE WIDESPREAD HEAVY RAIN NOT AS HIGH AS IT APPEARED TO BE YDA. NONETHELESS...PWATS WILL BE ABOVE 2 INCHES...SO ANY STORMS THAT DEVELOPS WILL BE EFFICIENT RAINFALL PRODUCERS. CONVECTION FRI AFTN MAY FOCUS ALONG A LEE TROUGH THAT FORMS AHEAD OF THE MAIN COLD FRONT. THE AFOREMENTIONED SHORTWAVE TROUGH WILL MOVE ACROSS NRN NEW ENGLAND FRI NGT. NW FLOW BEHIND THE TROUGH WILL HELP PUSH THE COLD FRONT TOWARD THE MASON-DIXON LINE LATE FRI NGT. DIURNALLY-DRIVEN CONVECTION EXPECTED TO WANE AFTER SUNSET. WITH A LATER TIMING IN THE FROPA AND COOLER...DRIER AND MORE STABLE AIR LAGGING BEHIND THE FRONT...FCST HAS TRENDED WETTER FOR THE SRN HALF OF THE CWA ON SAT. EXPECT SHOWERS AND STORMS TO DEVELOP DURING THE PEAK HEATING HRS. THE HIGHEST POPS RESIDE OVER THE CENTRAL VA AND LWR SRN MD...WHICH WILL BE LOCATED CLOSEST TO LLVL CONVERGENCE NEAR THE FRONT. THE FRONTAL BOUNDARY IS EXPECTED TO STALL SOUTH OF THE AREA ON SUN BEFORE LIFTING BACK NORTHWARD AS A WARM FRONT ON MON. DRY WEATHER TO CLOSED OUT THE WEEKEND WILL BE SHORT LIVED AS SHOWERS AND STORMS RETURN ERY NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... EXPECTING MVFR CONDITIONS TO MOVE IN THIS MORNING AND LAST INTO WED. SHOWER THREAT WILL BE THERE..ESP FOR CHO THIS MORNING. ALSO AN ISOLATED CHANCE FOR A TSTM. MOIST SLY RETURN FLOW WILL BE ACCOMPANIED BY DAILY CHANCES FOR SHRA AND TSRA DURING THE SECOND HALF OF THE WEEK. CONVECTION WILL BE PREDOMINANTLY DIURNALLY-DRIVEN AND SCT IN NATURE. THE POTENTIAL IS THERE FOR PERIODS OF LOW CLOUDS AND FOG EACH NGT/ERY MRNG GIVEN THE MOIST BOUNDARY LAYER IN PLACE. A COLD FRONT MOVES THRU THE TERMINALS FRI NGT AND SAT. && .MARINE... SCA HAS BEEN ISSUED FOR LATER TODAY INTO WED FOR THE BAY CHANNEL S OF ANNAP AND THE LOWER TIDAL POTOMAC. SCA HAS BEEN EXTENDED INTO WED FOR MOST OF THE MD CHSPK BAY AND THE MOUTH OF THE TIDAL POTOMAC. SLY FETCH WILL PROMOTE CHANNELING IN THESE ZONES. HIPRES MOVES FARTHER OFFSHORE THU AND FRI. CHANNELING WILL STILL ENHANCE WIND SPEEDS TO AROUND 15 KT IN THE BAY. && .TIDES/COASTAL FLOODING... SLY FLOW WILL CONTINUE THROUGH THE END OF THE WEEK AS HIGH PRESSURE REMAINS OFF THE EAST COAST. THE HIGHER OF THE HIGH TIDE WILL BE THE ONE TO WATCH FOR POTENTIAL MINOR TIDAL FLOODING WITH THE NEW MOON EXPECTED MID WEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EDT WEDNESDAY FOR ANZ531-539. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM EDT WEDNESDAY FOR ANZ532>534-537-540>543. && $$ UPDATE...GMS PREV DISCUSSION...CAS/JRK
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
401 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL REMAIN PARKED OFFSHORE THROUGH THE END OF THE WEEK. SOUTHERLY RETURN FLOW AROUND THE HIGH WILL DRAW TROPICAL MOISTURE UP THE EASTERN SEABOARD. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE MID-ATLANTIC STATES FRIDAY NIGHT AND SATURDAY. HIGH PRESSURE BRIEFLY BUILDS IN LATE THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... WAVE WILL COME THRU BRINGING RAIN SHOWERS MAINLY TO CENTRAL VA AND SOUTHERN MD OVERNIGHT INTO THE MORNING...MAINTAINING THE CHANCE IT COULD EDGE FURTHER NORTH AS IT MOVES EAST SOUTHEAST ACROSS THE REGION. HRRR SEEMS TO HAVE THE BEST HANDLE ON THIS EVOLVING SITUATION BASED ON EARLY MORNING RADAR TRENDS. AFTER THAT WAVE SLIDES EAST OF US BY MID TO LATE MORNING. MOST MESOMODELS SHOW SCATTERED CONVECTION DEVELOPING IN THE WARM ADVECTION ENVIRONMENT FOR THE AFTERNOON AND TUE NIGHT FAIRLY EVENLY ACROSS THE FORECAST AREA. GIVEN THE WEAK AND DIFFUSE FORCING WITH THIS...AM NOT CURRENTLY ABLE TO PUT MUCH DETAIL INTO WHERE THE BEST CHANCES ARE IN TIME AND AREA. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A CLOSED LOW WILL MEANDER OVER MANITOBA WHILE AN UPPER RIDGE IS PARKED OVER THE GULF COAST STATES THRU THE SHORT-TERM PERIOD. UPPER FLOW PATTERN BETWEEN THESE TWO SYSTEMS WILL BE FAIRLY ZONAL DURING THIS TIME WITH THE MID-ATLANTIC REGION SITUATED ON SRN PERIPHERY OF STRONGER WESTERLIES. A SERIES OF SHORTWAVE DISTURBANCES WILL ROTATE AROUND THE BASE OF THE UPPER TROUGH WITHIN THIS BELT OF ENHANCED WESTERLIES DURING THE SECOND HALF OF THE WEEK. IN THE LLVLS AND AT THE SFC...SLY RETURN FLOW AROUND HIPRES OVER THE WRN ATLANTIC WILL TRANSPORT MOISTURE FROM THE CARIBBEAN UP THE ERN SEABOARD. PWATS INCREASE FROM AROUND 1.5 INCHES WED MRNG TO 2 INCHES BY THU. IT WILL NOT REQUIRE A WHOLE LOT OF FORCING FROM EACH SHORTWAVE TROUGH TO PRODUCE SHOWERS AND TSTMS IN THIS TROPICAL AIRMASS. LOWERED POPS A BIT FROM PREV FCST WITH THE BEST FORCING EXPECTED TO REMAIN NORTH AND WEST OF THE AREA DURING THE SHORT TERM. POPS CLOSELY FOLLOW DIURNAL CYCLE AND ARE HIGHEST EACH DAY DURING THE AFTN/EVE HRS. WITH EXTENSIVE CLOUD COVER OVER THE AREA...THERE IS SOME FCST UNCERTAINTY REGARDING TSTM COVERAGE...WHICH WILL DEPEND ON AMT OF DAYTIME HEATING. ANY STORMS WILL HAVE THE POTENTIAL TO PRODUCE LOCALLY HVY RAINFALL...ESPECIALLY ON THU. HUMID AIRMASS AND CLOUDS COVER WILL YIELD BELOW NORMAL HIGHS AND ABOVE NORMAL LOWS. && .LONG TERM /FRIDAY THROUGH MONDAY/... THE VERTICALLY-STACKED LOW WILL PROGRESS SLOWLY EWD ACROSS CENTRAL ONTARIO FRI. A LEADING SHORTWAVE DISTURBANCE ROTATING AROUND THE BASE OF THE LARGE-SCALE TROUGH IS FCST TO MOVE FROM THE GREAT LAKES/OH VLY TO THE NRN MID-ATLANTIC AND NORTHEAST STATES DURING THIS TIME. THIS DISTURBANCE WILL PROVIDE SOME WEAK LIFT FOR SHOWERS AND STORMS ESPECIALLY DURING THE PEAK HEATING HRS. YDA`S MODELS SHOWED A COLD FRONT BECOMING STALLED OVER THE AREA ON FRI. NOW...THE LATEST 00Z ECMWF...GFS AND ITS ENSEMBLE MEMBERS INDICATE THE BOUNDARY REMAINING NORTH OF THE AREA. GIVEN THE SLOWING TREND...POPS WERE LOWERED AND THE POTENTIAL FOR MORE WIDESPREAD HEAVY RAIN NOT AS HIGH AS IT APPEARED TO BE YDA. NONETHELESS...PWATS WILL BE ABOVE 2 INCHES...SO ANY STORMS THAT DEVELOPS WILL BE EFFICIENT RAINFALL PRODUCERS. CONVECTION FRI AFTN MAY FOCUS ALONG A LEE TROUGH THAT FORMS AHEAD OF THE MAIN COLD FRONT. THE AFOREMENTIONED SHORTWAVE TROUGH WILL MOVE ACROSS NRN NEW ENGLAND FRI NGT. NW FLOW BEHIND THE TROUGH WILL HELP PUSH THE COLD FRONT TOWARD THE MASON-DIXON LINE LATE FRI NGT. DIURNALLY-DRIVEN CONVECTION EXPECTED TO WANE AFTER SUNSET. WITH A LATER TIMING IN THE FROPA AND COOLER...DRIER AND MORE STABLE AIR LAGGING BEHIND THE FRONT...FCST HAS TRENDED WETTER FOR THE SRN HALF OF THE CWA ON SAT. EXPECT SHOWERS AND STORMS TO DEVELOP DURING THE PEAK HEATING HRS. THE HIGHEST POPS RESIDE OVER THE CENTRAL VA AND LWR SRN MD...WHICH WILL BE LOCATED CLOSEST TO LLVL CONVERGENCE NEAR THE FRONT. THE FRONTAL BOUNDARY IS EXPECTED TO STALL SOUTH OF THE AREA ON SUN BEFORE LIFTING BACK NORTHWARD AS A WARM FRONT ON MON. DRY WEATHER TO CLOSED OUT THE WEEKEND WILL BE SHORT LIVED AS SHOWERS AND STORMS RETURN ERY NEXT WEEK. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... EXPECTING MVFR CONDITIONS TO MOVE IN THIS MORNING AND LAST INTO WED. SHOWER THREAT WILL BE THERE..ESP FOR CHO THIS MORNING. ALSO AN ISOLATED CHANCE FOR A TSTM. MOIST SLY RETURN FLOW WILL BE ACCOMPANIED BY DAILY CHANCES FOR SHRA AND TSRA DURING THE SECOND HALF OF THE WEEK. CONVECTION WILL BE PREDOMINANTLY DIURNALLY-DRIVEN AND SCT IN NATURE. THE POTENTIAL IS THERE FOR PERIODS OF LOW CLOUDS AND FOG EACH NGT/ERY MRNG GIVEN THE MOIST BOUNDARY LAYER IN PLACE. A COLD FRONT MOVES THRU THE TERMINALS FRI NGT AND SAT. && .MARINE... SCA HAS BEEN ISSUED FOR LATER TODAY INTO WED FOR THE BAY CHANNEL S OF ANNAP AND THE LOWER TIDAL POTOMAC. SCA HAS BEEN EXTENDED INTO WED FOR MOST OF THE MD CHSPK BAY AND THE MOUTH OF THE TIDAL POTOMAC. SLY FETCH WILL PROMOTE CHANNELING IN THESE ZONES. HIPRES MOVES FARTHER OFFSHORE THU AND FRI. CHANNELING WILL STILL ENHANCE WIND SPEEDS TO AROUND 15 KT IN THE BAY. && .TIDES/COASTAL FLOODING... SLY FLOW WILL CONTINUE THROUGH THE END OF THE WEEK AS HIGH PRESSURE REMAINS OFF THE EAST COAST. THE HIGHER OF THE HIGH TIDE WILL BE THE ONE TO WATCH FOR POTENTIAL MINOR TIDAL FLOODING WITH THE NEW MOON EXPECTED MID WEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...COASTAL FLOOD ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MDZ014. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM EDT WEDNESDAY FOR ANZ532>534-537-540>543. && $$ SYNOPSIS...JRK NEAR TERM...CAS SHORT TERM...JRK LONG TERM...JRK AVIATION...JRK/CAS MARINE...JRK/CAS TIDES/COASTAL FLOODING...JRK/CAS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
247 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE OVER THE MID ATLANTIC STATES MOVES OFF THE COAST TONIGHT AND TUESDAY. A WARM FRONT WILL LIFT BACK NORTH INTO THE REGION LATE TONIGHT THROUGH TUESDAY. A MOIST AIR MASS WILL PREVAIL THE REST OF THE WEEK...RESULTING IN DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TODAY/... THE LATEST WATER VAPOR IMAGERY ALONG WITH 00Z UPPER AIR OBSERVATIONS INDICATE NW MID/UPPER FLOW FROM THE UPPER MIDWEST THROUGH THE MID ATLANTIC BETWEEN TWO PRIMARY TROUGHS OVER CENTRAL AND ATLANTIC CANADA...AND AN UPPER RIDGE CENTERED OVER TX. WV IMAGERY INDICATES A SHORTWAVE TROUGH DIVING ESE ACROSS THE LOWER GREAT LAKES. WAA RETURNS AHEAD OF THIS FEATURE LATE TONIGHT ALONG WITH ISENTROPIC LIFT AROUND THE 305-310K RANGE. IN EFFECT...THE 80H WARM FRONT WILL PASS THROUGH THE AREA TUESDAY MORNING. THIS WILL BEGIN OVER THE MOUNTAINS OF SOUTHWEST VIRGINIA AND DEVELOP TO THE E AND NE. THE LAST FEW RUNS OF THE RUC ALONG WITH SUPPORT FROM THE 18Z NAM/GFS INDICATE RATHER STRONG LIFT OVER THE NW QUADRANT OF THE CWA LATE TONIGHT INTO EARLY TUESDAY MORNING (08-12Z). GIVEN THIS...POPS WERE RAISED TO LIKELY FOR THE NW CORNER OF THE AREA DURING THIS TIMEFRAME. OTHERWISE...POPS REMAIN AS IS FOR REST OF THE AREA. LOW TEMPERATURES WILL RANGE FROM THE LOWER 60S ON THE LOWER EASTERN SHORE TO THE MID AND UPR 60S ELSEWHERE. ON TUESDAY...FOLLOWED CLOSE TO NAM FORECAST. BOTH THE NAM AND MOS GUIDE HAVE THE HIGHEST POPS OVER THE FAR NORTH PART OF OUR AREA (DORCHESTER COUNTY MD AND PART OF THE NORTHERN NECK). HAVE LIKELY POPS IN THIS AREA THROUGH EARLY TUESDAY AFTN. A CHANCE FOR SHOWERS AND THUNDERSTORMS WILL EXTEND ACROSS THE CWA TUESDAY AFTN WITH LOWEST POPS (20 PERCENT) JUST ALONG THE ALBEMARLE SOUND. KEPT THUNDERSTORM MENTION TO SLIGHT CHANCE UNTIL 18Z TUESDAY. TEMPERATURES WILL BE HELD DOWN SOME BY CLOUD COVER AND PCPN WITH READINGS AROUND 80 IN THE NORTH TO THE MID 80S NEAR THE VA/NC BORDER. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... CONTINUED WITH THE CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH MOST OF THE SHORT TERM PERIOD. MOST POPS ARE IN THE 30 TO 40 PERCENT RANGE. DEEPEST MOISTURE APPEARS TO BE OVER THE NORTHWEST HALF OF THE AREA. SOME LOCALLY HEAVY RAINFALL IS POSSIBLE...MAINLY WEST OF I95 AND ACROSS THE NORTHERN COUNTIES...BUT DO NOT SEE A NEED TO HIGHLIGHT IN THE HWO AT THIS POINT. HIGHEST CHANCES APPEAR TO BE WEDNESDAY NIGHT WHEN MOST MODELS INDICATE A SHORT WAVE MOVING THROUGH. WITH THIS BEING IN THE FIFTH PERIOD...HIGHEST CHANCES ARE ACROSS OUR NORTHERN AREAS...SIMILAR TO TUESDAY MORNING. WAS NOT CONFIDENT ENOUGH WITH THE TIMING TO GO LIKELY AT THIS POINT. HIGH TEMPERATURES WEDNESDAY ARE FORECAST TO BE IN THE LOW TO MID 80S WEDNESDAY AND MID 80S TO NEAR 90 ON THURSDAY. LOWS SHOULD RANGE FROM 65 TO 70. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MEDIUM RANGE MODELS CONTINUE TO HANDLE THE OVERALL UPPER PATTERN WELL. STRONG UPPER LEVEL CLOSED LOW WILL BEGIN TO EJECT EWD FRI AS A SPEED MAX ROUNDS THE BASE OF THE LOW...AMPLIFYING A MID LEVEL TROUGH OVER THE NE STATES. THE EJECTING LOW WILL PUSH A SFC LOW THRU SE CANADA WITH AN ATTENDANT COLD FRONT STRETCHING SWWD INTO THE OH VALLEY. MEANWHILE...MID LEVEL HIGH PRESSURE WILL LOCATE JUST OFF THE SOUTHEAST COAST FRI WITH RIDGING OVER THE WRN ATLANTIC. THE RESULT WILL BE INCREASING SW FLOW OVER THE LOCAL AREA. PRECIP WATER VALUES PROGGED TO INCREASE AOA 2 INCHES FRI AFTERNOON WITH STRONG H85 MOISTURE TRANSPORT. SHORTWAVE ENERGY EMBEDDED IN THE WSW FLOW ALOFT WILL PROVIDE SUBTLE FORCING FOR ASCENT FRI AFTERNOON. LEE SIDE TROUGH AND THE APPROACHING COLD FRONT...AS WELL AS LOCAL CONVERGENCE BOUNDARIES...WILL COMBINE WITH MID LEVEL FORCING AND ABUNDANT MOISTURE FOR SCATTERED SHOWERS AND THUNDERSTORMS FRI AFTERNOON. THE BEST COVERAGE WILL BE OVER THE PIEDMONT...CLOSEST TO THE FRONT AND BEST MOISTURE. HIGH PRESSURE AND LESS MOISTURE ALONG THE COAST WILL LIMIT PRECIP CHANCES ACROSS THE SE. AS THE UPPER LEVEL FORCING WANES FRI NIGHT IN ADVANCE OF THE FRONT...EXPECT PRECIP CHANCES TO DIMINISH LATE FRI NIGHT/EARLY SAT MORNING. THE FRONT WILL SAG SWD THROUGH THE LOCAL AREA SAT. ADDITIONAL SHORTWAVE ENERGY AS WELL AS RRQ OF 70 KT UPPER LEVEL JET WILL PROVIDE BETTER FORCING FOR ASCENT SAT ALONG THE COLD FRONT...RESULTING IN BETTER COVERAGE (ALBEIT CHANCE) OF SHOWERS AND THUNDERSTORMS OVER THE LOCAL AREA. REGARDLESS OF ABUNDANT MOISTURE (+1 TO +2 STD DEV PRECIP WATER) AND LIMITED FORCING FOR ASCENT...THE BEST DYNAMICS WILL REMAIN WELL NORTH OF THE LOCAL AREA. THIS WILL LIKELY LIMIT THE COVERAGE OF SHOWERS/THUNDERSTORMS...BUT LOCALLY HEAVY RAINFALL WILL STILL BE POSSIBLE DUE TO THE VERY MOIST AIRMASS. FLOW PARALLEL TO THE FRONT AND HIGH PRESSURE ALONG THE SE COAST WILL RESULT IN THE FRONT SLOWING AS IT REACHES THE COAST. WILL HOLD ONTO SLIGHT CHANCE-CHANCE POPS ACROSS THE SE SUN TO ACCOUNT FOR THE SLOWING FRONT. HIGH PRESSURE WILL THEN BUILD IN BEHIND THE DEPARTING COLD FRONT. HOWEVER...COLDEST AIR EXPECTED TO REMAIN NORTH OF THE LOCAL AREA. MAIN CHANGES POST FRONTAL WILL BE DRIER AIR AND NLY WINDS. TEMPS DURING THE EXTENDED WILL REMAIN AROUND SEASONABLE NORMS (MID/UPPER 80S) UNDER PARTLY CLOUDY TO MOSTLY CLOUDY SKIES. MILD OVERNIGHT TEMPS WITH LOWS GENERALLY IN THE UPPER 60S/LOW 70S. HUMID FRI-SAT BEFORE DRYING OUT POST FRONTAL SAT NIGHT-MON. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS CONTINUE TO PREVAIL EARLY THIS MORNING ACROSS AREA TERMINALS. HAVE NOTED SOME LOWERING CEILINGS OVER THE PAST 2 HOURS AHEAD OF AN APPROACHING WARM FRONT. EXPECT BKN/OVC CONDITIONS BETWEEN 4-6KFT BETWEEN 08-12Z. AFTER A BRIEF PERIOD OF VICINITY SHRAS, HV CONTINUED PREDOMINATE -RA MENTION AT KRIC/KPHF/KSBY THROUGH 12Z. DUE TO DRY AIR IN LLVLS, WILL KEEP VSBYS P6SM AND CIGS AOA 3KFT. WINDS SHIFT FROM SE TO S/SW THIS AFTN WITH THE POTENTIAL FOR AT LEAST SCATTERED SHRA OR TSRA BUT GIVEN UNCERTAINTY WENT WITH ANOTHER PERIOD OF "VCSH" IN TAFS FOR NOW. OTHERWISE...MODESTLY WARMER AND MORE HUMID AIRMASS WILL PREVAIL FOR THE MID TO LATTER PORTION OF THE WORK WEEK. SCT (MAINLY DIURNALLY DRIVEN) SHOWERS AND TSTMS ARE EXPECTED. COLD FRONT SLOWLY PUSHES THROUGH ON SAT...BRINGING WITH IT CONTINUED CHANCES FOR SHRA/TSRA. && .MARINE... LIGHT N-NE WINDS AOB 10 KT OVER THE WATERS TODAY AS HIGH PRESSURE ORIENTS ALONG THE MID ATLANTIC COAST. HIGH PRESSURE WILL CONTINUE TO SLIDE OFFSHORE TONIGHT AS WINDS TURN TO THE S-SE. A WARM FRONT WILL LIFT THROUGH THE MID ATLANTIC REGION LATE TUE-WED. WINDS WILL INCREASE BEHIND THE FRONT AS THE GRADIENT TIGHTENS BTWN HIGH PRESSURE OFFSHORE AND LOW PRESSURE OVER THE GREAT LAKES REGION...BUT ARE EXPECTED TO REMAIN BELOW SCA SPEEDS. SOME SLY CHANNELING MAY LEAD TO ENHANCED WINDS OVER THE MIDDLE BAY TUES NIGHT-WED. GRADIENT WILL REMAIN THROUGH THURS WITH SLY WINDS AOB 15 KT. S-SE WINDS OVER THE COASTAL WATERS WILL BUILD SEAS 3-5 FT WED NIGHT-THURS OVER THE NRN COASTAL ZONES BEFORE DIMINISHING THURS EVENING. UNSETTLED CONDITIONS WILL REMAIN OVER THE WATERS THROUGH EARLY THIS WEEKEND AS A COLD FRONT APPROACHES FROM THE NORTHWEST. THE FRONT IS EXPECTED TO REACH...AND STALL OVER THE WATERS SAT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LSA NEAR TERM...AJZ/LSA SHORT TERM...LSA LONG TERM...SAM AVIATION...LKB/MAM MARINE...SAM
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
655 PM EDT TUE AUG 6 2013 .AVIATION... //DISCUSSION... DIURNALLY DRIVEN SHOWERS WILL FADE AT THE BEGINNING OF THE FORECAST LEAVING DRY CONDITIONS OVERNIGHT AS NEXT AREA OF SHOWERS/STORMS WELL TO THE WEST OVER MN/WI MOST LIKELY DROP SOUTHEAST AND BYPASS MUCH OF LOWER MICHIGAN OVERNIGHT. RESIDUAL LOW LEVEL MOISTURE WILL BRING PATCHY FOG BY DAYBREAK WEDNESDAY...BUT VSBYS SHOULD HOLD IN THE 4 TO 6SM RANGE. THE NEXT CHANCE OF SHRAS/TSRAS WILL COME WITH THE PASSAGE OF A SURFACE TROUGH BETWEEN 16Z-21Z WEDNESDAY...PROGRESSING FROM KMBS TO THE I-94 TERMINALS DURING THE COURSE OF THE AFTERNOON. FOR DTW...WITH CURRENT CONVECTION LIFTING NORTHEAST...THE NEXT CHANCE OF SHRAS/TSRAS WILL HOLD OFF UNTIL 20Z-22Z WEDNESDAY AS ACTIVITY DEVELOPS ALONG AN APPROACHING SURFACE TROUGH. OTHER THAN THIS...THE ONLY MINOR CONCERN WILL BE THE POTENTIAL OF FOG LATE TONIGHT...BUT EVEN WITH THIS...VSBYS SHOULD REMAIN GENERALLY 5SM. //DTW THRESHOLD THREATS... * LOW CONFIDENCE IN CEILINGS AOB 5000 FEET WEDNESDAY AFTERNOON. * LOW CONFIDENCE IN TIMING/COVERAGE OF THUNDERSTORMS WEDNESDAY AFTERNOON. && .PREV DISCUSSION...ISSUED 402 PM EDT TUE AUG 6 2013 SHORT TERM...THROUGH TONIGHT CURRENT OBSERVATIONS AND SATELLITE TRENDS SHOW CLOUDS OVER SOUTHEAST MICHIGAN...ALONG WITH RAIN SHOWERS CONTINUING TO MOVE OFF TO THE NORTHEAST. AREAS OF RAIN SHOWERS WERE ABLE TO DEVELOP OVER THE WESTERN CWA AND MAINTAIN MOMENTUM AS AN AREA OF 500 MB VORTICITY MOVED THROUGH AND LOW LEVEL LAPSE RATES INCREASED TO AROUND 6.5 C/KM. A BREAK IN THE RAIN WILL BE SEEN BEFORE ANOTHER ROUND MOVES THROUGH ROUGHLY THE SAME AREA LATE THIS AFTERNOON AND EVENING. LATEST RUN OF THE HRRR IS ADVERTISING MORE SHOWERS BETWEEN 20Z-03Z. HAVE SLIGHTLY INCREASED POPS IN AREAS MAINLY NORTH OF METRO DETROIT DURING THIS TIMEFRAME. EXPECTING MODERATE RAIN SHOWERS AS WAS SEEN THIS MORNING...WITH A SLIGHT CHANCE FOR ISOLATED THUNDERSTORMS. EXPECTING ANY THUNDERSTORMS THAT DO DEVELOP TO REMAIN BELOW SEVERE CRITERIA. HAVE BEEN MONITORING A SMALL BREAK IN CLOUDS OVER THE PAST FEW HOURS WHICH HAS ALLOWED INSTABILITY TO INCREASE. LOOKING AT THE SPC MESOANALYSIS...LOW LEVEL LAPSE RATES HAVE INCREASED TO AROUND 7-7.5 WITH SBCAPE ONLY AROUND 500 J/KG. SHOWERS HAVE STARTED TO DEVELOP JUST SOUTH OF THE LANSING AND WILL CONTINUE TO MOVE OFF TO THE NORTHEAST. CHANCES FOR PRECIPITATION WILL DIMINISH WITH THE LOSS OF DIURNAL HEATING. OVERNIGHT...SOUTHEAST MICHIGAN WILL START FEELING THE INFLUENCE FROM THE UPPER LEVEL JET STREAK AS THE LOW PRESSURE CURRENTLY OVER THE UPPER MIDWEST SAGS EAST. HIGHER CLOUDS FROM CONVECTION CURRENTLY OVER WISCONSIN WILL STREAM IN OVER SE MICHIGAN AND WITH WINDS OUT OF THE SOUTH..WILL KEEP LOWS WARMER THAN THE PREVIOUS MORNING. ANOTHER AREA OF VORTICITY ASSOCIATED AHEAD OF THE COLD FRONT IS SET TO ROTATE DOWN ACROSS THE UPPER GREAT LAKES WEDNESDAY MORNING...INCREASING THE CHANCES FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS. LONG TERM...WEDNESDAY THROUGH MONDAY NOT MUCH CHANGE IN THE LONG TERM THROUGH THE PERIOD AS THE DOMINATE CUTOFF UPPER LOW CONTINUES TO WOBBLE ABOUT EASTERN CANADA. MODELS HAVE HAD AMPLE TIME TO LATCH ONTO THIS FEATURE WHICH HAS LED TO GOOD AGREEMENT WITH THE OVERALL PATTERN. A SECOND UPPER LOW OVER THE WEST COAST IS STEERING THE SOUTHERN STREAM OF THE JET UP FROM SOUTHERN CALIFORNIA THROUGH THE CENTRAL PORTION OF THE CONUS TO THE GREAT LAKES. THIS WILL BRING ABOUT SOME PHASING OF THE TWO STREAMS OVER THE GREAT LAKES THROUGH THE WEEKEND. GENERAL NW PROGRESSIVE FLOW WILL SEND A SERIES OF SHORTWAVES THROUGH THE REGION PRODUCING A FEW SHOTS AT PRECIP BUT DRY AIR AND HIGH IN THE WAKE OF THE BEST FRONT ON WEDNESDAY WILL PREVENT ANY SIGNIFICANT EVENTS. FOR WEDNESDAY...WE MAY HAVE A COUPLE ROUNDS OF PRECIP IN THE HOPPER AS MODELS INDICATE A MORNING COMPLEX WITH A LEAD SHORTWAVE FOLLOWED BY A SECOND ROUND ALONG THE COLD FRONT ITSELF LATER IN THE AFTERNOON/EVENING. BOTH THE NAM AND HRRR SUGGEST THE MORNING STORM COMPLEX WILL TRACK GENERALLY THROUGH CHI AND IND KEEPING THE BULK OF PRECIP TO OUR SOUTH WITH SOME MORE SCATTERED SHOWERS UP AROUND SE MI. THIS WILL COME MORE IN LINE THROUGH THE EVENING AS WE SEE IF/HOW THE COMPLEX ACTUALLY COMES TOGETHER. REGARDLESS THERE WILL BE A FAIR AMOUNT OF CLOUD COVER TO CONTEND WITH EARLY IN THE DAY. AS IS USUALLY THE CASE FOR THE AREA...THE AMOUNT OF CLOUDS AND HOW LONG THEY STICK AROUND WILL HELP DICTATE WHERE WE STAND WITH CONVECTION LATER IN THE DAY ALONG THE FRONT. EVEN WITH THE NAM KEEPING A FAIR AMOUNT OF CLOUDS AROUND THROUGH THE DAY IT STILL GENERATES UP TO 1500 K/KG OF CAPE WITH 30-40 KNOTS OF BULK SHEAR. GFS IS A LITTLE MORE BULLISH WITH CLEARING WHICH THEN ALLOWS MORE INSTABILITY TO BUILD ADVERTISING JUST OVER 2000 J/KG OF CAPE. ANOTHER PROBLEM WITH THE SETUP IS THAT THE PARENT SFC LOW WILL BE LIFTING TO THE NORTH THROUGH THE DAY WHICH SLOWLY ORIENTATES THE FRONT PARALLEL TO THE FLOW REDUCING SFC CONVERGENCE ALONG THE FRONT. LI/S ARE ON THE LOW SIDE AS WELL ONLY REACHING AROUND -3C. FRONTAL TIMING WILL BE FAVORABLE GIVING SE MI THE FULL DAY TO CLEAR OUT AND HEAT UP BEFORE THE FRONT ROLLS THROUGH SO CHANCES FOR STRONG ORGANIZED STORMS WILL GET LARGER AS YOU TRACK FROM MBS TO DTW. SPC IS ON TRACK WITH THIS THINKING KEEPING ONLY FAR SE MI...SE OF A LINE FROM PORT HURON TO COLDWATER...WITHIN THE SLIGHT RISK AREA. TEMPS SHOULD REACH 80+ FOR MOST LOCATIONS AS A DECENT THETA E RIDGE BUILDS IN AHEAD OF THE FRONT. 850 MB TEMPS ARE STILL PROGGED TO REACH 16C BY THE AFTERNOON HOURS. IN THE WAKE OF THE FRONT A HIGH PRESSURE SYSTEM WILL SLIDE INTO THE REGION BRINGING COOLER DRIER AIR IN FROM CANADA THROUGH SATURDAY. A WEAK FRONT WILL DROP THROUGH FRIDAY NIGHT WITH LITTLE CHANCE OF PRODUCING MORE THAN A CHANCE FOR MOST LOCATIONS. A SHORTWAVE ON SUNDAY WILL WORK OVER THE AREA BUT WILL LIKELY STRUGGLE TO PRODUCE ANY PRECIP WITH DRY AIR PRESENT. NORTHERLY FLOW WITH THE MAIN BAROCLINIC ZONE TO OUR SOUTH WILL KEEP TEMPERATURES ON THE COOL SIDE THROUGH MUCH OF THE EXTENDED. THE PATTERN HAS YIELDED AN EXTENSIVE PERIOD OF 70S AND DO NOT SEE THIS CHANGING. MARINE... LOW PRESSURE WILL SAG OVER THE UPPER GREAT LAKES PULLING A COLD FRONT THROUGH THE AREA LATER WEDNESDAY EVENING. SOUTHERLY WINDS AHEAD OF THE FRONT WILL CONTINUE OVERNIGHT AND THROUGH WEDNESDAY. WARMER AIR ASSOCIATED WITH THE SOUTHERLY WINDS WILL KEEP CONDITIONS STABLE OVER THE WATERS. CHANCE FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS WILL INCREASE STARTING WEDNESDAY MORNING. WINDS WILL DIMINISH THURSDAY INTO FRIDAY AS HIGH PRESSURE OVERSPREADS THE REGION. ANOTHER COLD FRONT IS FORECAST TO TRAVERSE THE LAKES FRIDAY NIGHT. A PUSH OF MUCH COLDER AIR BEHIND THIS FRONT IS LIKELY TO CAUSE STRENGTHENING OF THE POST FRONTAL NORTHWEST WINDS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....DG SHORT TERM...SS LONG TERM....DRK MARINE.......SS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
402 PM EDT TUE AUG 6 2013 .SHORT TERM...THROUGH TONIGHT CURRENT OBSERVATIONS AND SATELLITE TRENDS SHOW CLOUDS OVER SOUTHEAST MICHIGAN...ALONG WITH RAIN SHOWERS CONTINUING TO MOVE OFF TO THE NORTHEAST. AREAS OF RAIN SHOWERS WERE ABLE TO DEVELOP OVER THE WESTERN CWA AND MAINTAIN MOMENTUM AS AN AREA OF 500 MB VORTICITY MOVED THROUGH AND LOW LEVEL LAPSE RATES INCREASED TO AROUND 6.5 C/KM. A BREAK IN THE RAIN WILL BE SEEN BEFORE ANOTHER ROUND MOVES THROUGH ROUGHLY THE SAME AREA LATE THIS AFTERNOON AND EVENING. LATEST RUN OF THE HRRR IS ADVERTISING MORE SHOWERS BETWEEN 20Z-03Z. HAVE SLIGHTLY INCREASED POPS IN AREAS MAINLY NORTH OF METRO DETROIT DURING THIS TIMEFRAME. EXPECTING MODERATE RAIN SHOWERS AS WAS SEEN THIS MORNING...WITH A SLIGHT CHANCE FOR ISOLATED THUNDERSTORMS. EXPECTING ANY THUNDERSTORMS THAT DO DEVELOP TO REMAIN BELOW SEVERE CRITERIA. HAVE BEEN MONITORING A SMALL BREAK IN CLOUDS OVER THE PAST FEW HOURS WHICH HAS ALLOWED INSTABILITY TO INCREASE. LOOKING AT THE SPC MESOANALYSIS...LOW LEVEL LAPSE RATES HAVE INCREASED TO AROUND 7-7.5 WITH SBCAPE ONLY AROUND 500 J/KG. SHOWERS HAVE STARTED TO DEVELOP JUST SOUTH OF THE LANSING AND WILL CONTINUE TO MOVE OFF TO THE NORTHEAST. CHANCES FOR PRECIPITATION WILL DIMINISH WITH THE LOSS OF DIURNAL HEATING. OVERNIGHT...SOUTHEAST MICHIGAN WILL START FEELING THE INFLUENCE FROM THE UPPER LEVEL JET STREAK AS THE LOW PRESSURE CURRENTLY OVER THE UPPER MIDWEST SAGS EAST. HIGHER CLOUDS FROM CONVECTION CURRENTLY OVER WISCONSIN WILL STREAM IN OVER SE MICHIGAN AND WITH WINDS OUT OF THE SOUTH..WILL KEEP LOWS WARMER THAN THE PREVIOUS MORNING. ANOTHER AREA OF VORTICITY ASSOCIATED AHEAD OF THE COLD FRONT IS SET TO ROTATE DOWN ACROSS THE UPPER GREAT LAKES WEDNESDAY MORNING...INCREASING THE CHANCES FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS. && .LONG TERM...WEDNESDAY THROUGH MONDAY NOT MUCH CHANGE IN THE LONG TERM THROUGH THE PERIOD AS THE DOMINATE CUTOFF UPPER LOW CONTINUES TO WOBBLE ABOUT EASTERN CANADA. MODELS HAVE HAD AMPLE TIME TO LATCH ONTO THIS FEATURE WHICH HAS LED TO GOOD AGREEMENT WITH THE OVERALL PATTERN. A SECOND UPPER LOW OVER THE WEST COAST IS STEERING THE SOUTHERN STREAM OF THE JET UP FROM SOUTHERN CALIFORNIA THROUGH THE CENTRAL PORTION OF THE CONUS TO THE GREAT LAKES. THIS WILL BRING ABOUT SOME PHASING OF THE TWO STREAMS OVER THE GREAT LAKES THROUGH THE WEEKEND. GENERAL NW PROGRESSIVE FLOW WILL SEND A SERIES OF SHORTWAVES THROUGH THE REGION PRODUCING A FEW SHOTS AT PRECIP BUT DRY AIR AND HIGH IN THE WAKE OF THE BEST FRONT ON WEDNESDAY WILL PREVENT ANY SIGNIFICANT EVENTS. FOR WEDNESDAY...WE MAY HAVE A COUPLE ROUNDS OF PRECIP IN THE HOPPER AS MODELS INDICATE A MORNING COMPLEX WITH A LEAD SHORTWAVE FOLLOWED BY A SECOND ROUND ALONG THE COLD FRONT ITSELF LATER IN THE AFTERNOON/EVENING. BOTH THE NAM AND HRRR SUGGEST THE MORNING STORM COMPLEX WILL TRACK GENERALLY THROUGH CHI AND IND KEEPING THE BULK OF PRECIP TO OUR SOUTH WITH SOME MORE SCATTERED SHOWERS UP AROUND SE MI. THIS WILL COME MORE IN LINE THROUGH THE EVENING AS WE SEE IF/HOW THE COMPLEX ACTUALLY COMES TOGETHER. REGARDLESS THERE WILL BE A FAIR AMOUNT OF CLOUD COVER TO CONTEND WITH EARLY IN THE DAY. AS IS USUALLY THE CASE FOR THE AREA...THE AMOUNT OF CLOUDS AND HOW LONG THEY STICK AROUND WILL HELP DICTATE WHERE WE STAND WITH CONVECTION LATER IN THE DAY ALONG THE FRONT. EVEN WITH THE NAM KEEPING A FAIR AMOUNT OF CLOUDS AROUND THROUGH THE DAY IT STILL GENERATES UP TO 1500 K/KG OF CAPE WITH 30-40 KNOTS OF BULK SHEAR. GFS IS A LITTLE MORE BULLISH WITH CLEARING WHICH THEN ALLOWS MORE INSTABILITY TO BUILD ADVERTISING JUST OVER 2000 J/KG OF CAPE. ANOTHER PROBLEM WITH THE SETUP IS THAT THE PARENT SFC LOW WILL BE LIFTING TO THE NORTH THROUGH THE DAY WHICH SLOWLY ORIENTATES THE FRONT PARALLEL TO THE FLOW REDUCING SFC CONVERGENCE ALONG THE FRONT. LI/S ARE ON THE LOW SIDE AS WELL ONLY REACHING AROUND -3C. FRONTAL TIMING WILL BE FAVORABLE GIVING SE MI THE FULL DAY TO CLEAR OUT AND HEAT UP BEFORE THE FRONT ROLLS THROUGH SO CHANCES FOR STRONG ORGANIZED STORMS WILL GET LARGER AS YOU TRACK FROM MBS TO DTW. SPC IS ON TRACK WITH THIS THINKING KEEPING ONLY FAR SE MI...SE OF A LINE FROM PORT HURON TO COLDWATER...WITHIN THE SLIGHT RISK AREA. TEMPS SHOULD REACH 80+ FOR MOST LOCATIONS AS A DECENT THETA E RIDGE BUILDS IN AHEAD OF THE FRONT. 850 MB TEMPS ARE STILL PROGGED TO REACH 16C BY THE AFTERNOON HOURS. IN THE WAKE OF THE FRONT A HIGH PRESSURE SYSTEM WILL SLIDE INTO THE REGION BRINGING COOLER DRIER AIR IN FROM CANADA THROUGH SATURDAY. A WEAK FRONT WILL DROP THROUGH FRIDAY NIGHT WITH LITTLE CHANCE OF PRODUCING MORE THAN A CHANCE FOR MOST LOCATIONS. A SHORTWAVE ON SUNDAY WILL WORK OVER THE AREA BUT WILL LIKELY STRUGGLE TO PRODUCE ANY PRECIP WITH DRY AIR PRESENT. NORTHERLY FLOW WITH THE MAIN BAROCLINIC ZONE TO OUR SOUTH WILL KEEP TEMPERATURES ON THE COOL SIDE THROUGH MUCH OF THE EXTENDED. THE PATTERN HAS YIELDED AN EXTENSIVE PERIOD OF 70S AND DO NOT SEE THIS CHANGING. && .MARINE... LOW PRESSURE WILL SAG OVER THE UPPER GREAT LAKES PULLING A COLD FRONT THROUGH THE AREA LATER WEDNESDAY EVENING. SOUTHERLY WINDS AHEAD OF THE FRONT WILL CONTINUE OVERNIGHT AND THROUGH WEDNESDAY. WARMER AIR ASSOCIATED WITH THE SOUTHERLY WINDS WILL KEEP CONDITIONS STABLE OVER THE WATERS. CHANCE FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS WILL INCREASE STARTING WEDNESDAY MORNING. WINDS WILL DIMINISH THURSDAY INTO FRIDAY AS HIGH PRESSURE OVERSPREADS THE REGION. ANOTHER COLD FRONT IS FORECAST TO TRAVERSE THE LAKES FRIDAY NIGHT. A PUSH OF MUCH COLDER AIR BEHIND THIS FRONT IS LIKELY TO CAUSE STRENGTHENING OF THE POST FRONTAL NORTHWEST WINDS. && .AVIATION...ISSUED 117 PM EDT TUE AUG 6 2013 //DISCUSSION... CLOUDS AND LOW LEVEL MOISTURE WILL CONTINUE TO STREAM INTO THE AREA THROUGH WEDNESDAY MORNING AS A COLD FRONT APPROACHES. THERE IS ANOTHER CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS EARLY THIS EVENING. CHANCES ARE SLIGHTLY BETTER AT PNT/FNT TAF SITES AND SO HAVE INCLUDED THAT IN THE TAFS. HOWEVER...WITH ANY PRECIPITATION THAT DOES DEVELOP...AM EXPECTING SHOWERS LIKE WHAT WAS SEEN EARLIER THIS AFTERNOON DUE TO THE WARMER AIR IN THE MID LEVELS KEEPING THINGS FROM DEVELOPING TOO MUCH. THERE IS STILL A SLIGHT CHANCE OF AN ISOLATED THUNDERSTORM...ESPECIALLY IF BREAKS IN THE CLOUDS DEVELOP FOR ANY LENGTH OF TIME. A BREAK IN THE PRECIPITATION WILL BE SEEN OVERNIGHT AND WITH THE AMOUNT OF LOW LEVEL MOISTURE DO HAVE THE POTENTIAL TO SEE AREAS OF DECREASED VISIBILITY. RAIN AND THUNDERSTORMS WILL ONCE AGAIN AFFECT THE AREA WEDNESDAY AS THE COLD FRONT WORKS CLOSER AND IS EXPECTED TO PUSH THROUGH AFTER 00Z THURSDAY. FOR DTW...CONFIDENCE IS TO LOW TO MENTION ANY THUNDERSTORMS IN THE TAFS LATER THIS AFTERNOON...HOWEVER WILL KEEP MONITORING FOR CHANGES. WITH THE AMOUNT OF LOW LEVEL MOISTURE STILL PRESENT OVERNIGHT...THERE WILL BE AN INCREASED CHANCE FOR VISIBILITIES TO DROP UNDER 6SM. //DTW THRESHOLD THREATS... * MODERATE CONFIDENCE IN CEILING BELOW 5000 FT OVERNIGHT. * LOW CONFIDENCE IN TIMING/COVERAGE OF SHOWERS THIS EVENING. * LOW CONFIDENCE IN THUNDERSTORMS LATER THIS AFTERNOON INTO EARLY EVENING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...SS LONG TERM....DRK MARINE.......SS AVIATION.....SS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
352 PM EDT TUE AUG 6 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 347 PM EDT TUE AUG 6 2013 A COLD FRONT WILL MOVE THROUGH THE NORTHERN PLAINS TONIGHT AND APPROACH LAKE MICHIGAN TOWARDS DAYBREAK. THE FRONT WILL SWEEP THROUGH LOWER MICHIGAN ON WEDNESDAY BRINGING COOLER AND DRIER AIR INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. SHOWER AND STORMS WILL ACCOMPANY THE FRONT BOTH TONIGHT AND WEDNESDAY. SOME OF THE STORMS MAY BE ON THE STRONG SIDE WEDNESDAY AFTERNOON SOUTH AND EAST OF GRAND RAPIDS. HIGHS ON WEDNESDAY WILL PUSH INTO THE UPPER 70S AND LOWER 80S. THE UPCOMING WEEKEND LOOKS DRY WITH HIGHS IN THE 70S. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 347 PM EDT TUE AUG 6 2013 MAIN CONCERNS IN THE SHORT TERM ARE RELATED TO CONVECTION TONIGHT AND WEDNESDAY. CURRENT THINKING IS WE WILL SEE SOME SCATTERED SHOWERS AND STORMS BETWEEN NOW AND MIDNIGHT...WITH BETTER CHANCES OCCURRING LATE. THE LATEST HRRR GUIDANCE WOULD SUGGEST WE WILL SEE A THUNDERSTORM COMPLEX ROLL EAST OUT OF WISCONSIN AND MOVE INTO CENTRAL LOWER MICHIGAN OVERNIGHT. THIS SEEMS PLAUSIBLE GIVEN THE CONFIGURATION OF THE 850MB LLJ. NOT EXPECTING SEVERE WEATHER AT THIS TIME...BUT THE SIMULATED REFLECTIVITY IS IN THE FORM OF A SQUALL LINE. EXPECT SCATTERED SHOWERS AND STORMS TO BE OVER A DECENT AMOUNT OF THE FORECAST AREA BETWEEN 09Z AND 15Z AS UPSTREAM RESIDUAL CONVECTION SLIDES INTO LOWER MICHIGAN OR DEVELOPS OVERHEAD ON THE LLJ. SHOWERS AND STORMS SHOULD REFOCUS MIDDAY ALONG THE COLD FRONT THAT SHOULD BISECT THE CWA. STRONG STORMS ARE POSSIBLE IN THE EASTERN CWA TOMORROW AFTERNOON WITH 40 KNOTS OF DEEP LAYER SHEAR AND THE POTENTIAL FOR SOME BREAKS IN THE OVERCAST AHEAD OF THE MORNING STORMS. CLOUD COVER TOMORROW MORNING WILL DETERMINE THE STRENGTH OF THE AFTERNOON CONVECTION AS DEEP MOISTURE WILL BE IN PLACE. THE SHOWERS AND STORMS SHOULD EXIT TO THE EAST EARLY IN THE EVENING AS THE FRONT SWEEPS THROUGH. MAINLY DRY WEATHER IS THEN FORECAST FROM WEDNESDAY EVENING THROUGH THURSDAY NIGHT. THERE IS SOME SMALL POTENTIAL FOR SHOWERS AND STORMS IN THE SOUTH THURSDAY NIGHT...BUT THIS ACTIVITY MAY JUST MISS THE AREA TO THE SOUTH PER RECENT MODEL TRENDS. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 347 PM EDT TUE AUG 6 2013 THE POLAR VORTEX OVER EASTERN CANADA WILL CONTINUE TO PLAY A ROLE IN OUR WEATHER THROUGH THE EXTENDED PERIOD. A STRONG SHORT WAVE MOVING ACROSS ONTARIO WILL PUSH A COLD FRONT THROUGH THE CWA FRIDAY SENDING ANOTHER PUSH OF COOLER AIR SOUTH ACROSS THE CWA FOR THE WEEKEND. THE LACK OF DEEP MOISTURE AND INSTABILITY WILL RESULT IN LIGHT SHOWERS AT BEST FRIDAY. MUCH OF THE WEEKEND LOOKS DRY WITH HIGHS IN THE MID 70S AND DEWPOINTS IN THE 50S AS SFC HIGH PRESSURE SETTLES OVER THE GREAT LAKES. ANOTHER SHORT WAVE WILL DROP SOUTH FROM NORTHERN ONTARIO DURING THE MONDAY/TUESDAY TIME FRAME. SIMILAR TO THE LAST FRONT...THERE WON/T BE MUCH MOISTURE WITH THIS FRONT EITHER. LOW CHANCES OF SHOWERS WILL COVER THIS TROUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 352 PM EDT TUE AUG 6 2013 LATEST NEPH ANALYSIS SHOWS MVFR CONDITONS ACROSS MUCH OF THE MIDWEST. ERN LWR MI WAS MAINLY VFR AND KJXN WAS JUST ON THE EDGE...EXPLAINING WHY THEY KEEP OSCILLATING BETWEEN IFR/MVFR. GIVEN THE SW WINDS I KEPT KJXN MVFR BUT THEY COULD CONTINUE TO OSCILLATE THROUGH THE AFTERNOON. LIGHT SHOWERS ARE POSSIBLE ACROSS THE SRN TAF SITES THIS AFTERNOON. OVERALL...LOOK FOR VFR TO DEVELOP BY THIS EVENING WITH TSRA POSSIBLE OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT. && .MARINE... ISSUED AT 347 PM EDT TUE AUG 6 2013 HAVE HELD OFF ON ANY SMALL CRAFT ADVISORIES OR BEACH HAZARDS STATEMENTS AS THE WINDS AND WAVES IN TODAY/S MODEL RUNS ARE NOT AS SIGNIFICANT AS LAST NIGHT OR YESTERDAY. IT APPEARS AT THIS POINT IN BOTH THE SOUTHERLY FLOW TONIGHT AND THE NORTH FLOW BEHIND THE FRONT TOMORROW THAT WE REMAIN BELOW CRITERIA. AM A BIT CONCERNED THOUGH BASED ON THE WINDS SEEN IN BUFKIT THAT WE WON/T INDEED BE HIGHER BOTH TONIGHT...WEDNESDAY AND WEDNESDAY NIGHT. WE WILL SEE AS WE PROGRESS THROUGH THE EVENING AS BUFKIT WOULD SUGGEST INCREASING WINDS IN THE 04Z-08Z TIME FRAME. WE PLAY THINGS LOWER AT THIS POINT BUT WATCH CAUTIOUSLY AND CLOSELY. && .HYDROLOGY... ISSUED AT 347 PM EDT TUE AUG 6 2013 NO SIGNIFICANT HYDRO ISSUES EXPECTED THROUGH THE NEXT COUPLE DAYS WITH NEAR NORMAL FLOWS IN PLACE NOW AND FORECAST RAINFALL IS NOT EXPECTED TO BE WIDESPREAD OR OVERLY HEAVY. RAINFALL LAST NIGHT WAS QUITE LIMITED AS WELL SO WE ARE STARTING OFF WITH FAIRLY DRY GROUND OVER MUCH OF THE AREA. RAINFALL IS EXPECTED TONIGHT THROUGH WEDNESDAY...BUT IT WILL BE ASSOCIATED WITH THUNDERSTORM COMPLEXES THAT WILL BE TRAVERSING THE AREA AT A DECENT CLIP. THE FIRST COMES LATE TONIGHT AS STORMS THAT FIRE IN MINNESOTA THIS EVENING TRY TO MOVE ACROSS LAKE MICHIGAN AFTER MIDNIGHT. THESE STORMS WILL LIKELY AFFECT CENTRAL LOWER MICHIGAN. SCATTERED SHOWERS AND STORMS WILL THEN TRAVERSE MUCH OF THE AREA LATE TONIGHT AND WEDNESDAY MORNING. A MORE CONCENTRATED AREA OF SHOWERS AND STORMS WILL AFFECT THE EASTERN TO SOUTHEASTERN HALF OF THE AREA WEDNESDAY AFTERNOON. WE COULD SEE GENERAL RAINFALL AMOUNTS ON THE ORDER OF A QUARTER TO HALF INCH WITH ISOLATED AMOUNTS AROUND AN INCH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...DUKE SHORT TERM...DUKE LONG TERM...93 AVIATION...93 HYDROLOGY...DUKE MARINE...DUKE
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
347 PM EDT TUE AUG 6 2013 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE .SYNOPSIS... ISSUED AT 347 PM EDT TUE AUG 6 2013 A COLD FRONT WILL MOVE THROUGH THE NORTHERN PLAINS TONIGHT AND APPROACH LAKE MICHIGAN TOWARDS DAYBREAK. THE FRONT WILL SWEEP THROUGH LOWER MICHIGAN ON WEDNESDAY BRINGING COOLER AND DRIER AIR INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. SHOWER AND STORMS WILL ACCOMPANY THE FRONT BOTH TONIGHT AND WEDNESDAY. SOME OF THE STORMS MAY BE ON THE STRONG SIDE WEDNESDAY AFTERNOON SOUTH AND EAST OF GRAND RAPIDS. HIGHS ON WEDNESDAY WILL PUSH INTO THE UPPER 70S AND LOWER 80S. THE UPCOMING WEEKEND LOOKS DRY WITH HIGHS IN THE 70S. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 347 PM EDT TUE AUG 6 2013 MAIN CONCERNS IN THE SHORT TERM ARE RELATED TO CONVECTION TONIGHT AND WEDNESDAY. CURRENT THINKING IS WE WILL SEE SOME SCATTERED SHOWERS AND STORMS BETWEEN NOW AND MIDNIGHT...WITH BETTER CHANCES OCCURRING LATE. THE LATEST HRRR GUIDANCE WOULD SUGGEST WE WILL SEE A THUNDERSTORM COMPLEX ROLL EAST OUT OF WISCONSIN AND MOVE INTO CENTRAL LOWER MICHIGAN OVERNIGHT. THIS SEEMS PLAUSIBLE GIVEN THE CONFIGURATION OF THE 850MB LLJ. NOT EXPECTING SEVERE WEATHER AT THIS TIME...BUT THE SIMULATED REFLECTIVITY IS IN THE FORM OF A SQUALL LINE. EXPECT SCATTERED SHOWERS AND STORMS TO BE OVER A DECENT AMOUNT OF THE FORECAST AREA BETWEEN 09Z AND 15Z AS UPSTREAM RESIDUAL CONVECTION SLIDES INTO LOWER MICHIGAN OR DEVELOPS OVERHEAD ON THE LLJ. SHOWERS AND STORMS SHOULD REFOCUS MIDDAY ALONG THE COLD FRONT THAT SHOULD BISECT THE CWA. STRONG STORMS ARE POSSIBLE IN THE EASTERN CWA TOMORROW AFTERNOON WITH 40 KNOTS OF DEEP LAYER SHEAR AND THE POTENTIAL FOR SOME BREAKS IN THE OVERCAST AHEAD OF THE MORNING STORMS. CLOUD COVER TOMORROW MORNING WILL DETERMINE THE STRENGTH OF THE AFTERNOON CONVECTION AS DEEP MOISTURE WILL BE IN PLACE. THE SHOWERS AND STORMS SHOULD EXIT TO THE EAST EARLY IN THE EVENING AS THE FRONT SWEEPS THROUGH. MAINLY DRY WEATHER IS THEN FORECAST FROM WEDNESDAY EVENING THROUGH THURSDAY NIGHT. THERE IS SOME SMALL POTENTIAL FOR SHOWERS AND STORMS IN THE SOUTH THURSDAY NIGHT...BUT THIS ACTIVITY MAY JUST MISS THE AREA TO THE SOUTH PER RECENT MODEL TRENDS. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 347 PM EDT TUE AUG 6 2013 THE POLAR VORTEX OVER EASTERN CANADA WILL CONTINUE TO PLAY A ROLE IN OUR WEATHER THROUGH THE EXTENDED PERIOD. A STRONG SHORT WAVE MOVING ACROSS ONTARIO WILL PUSH A COLD FRONT THROUGH THE CWA FRIDAY SENDING ANOTHER PUSH OF COOLER AIR SOUTH ACROSS THE CWA FOR THE WEEKEND. THE LACK OF DEEP MOISTURE AND INSTABILITY WILL RESULT IN LIGHT SHOWERS AT BEST FRIDAY. MUCH OF THE WEEKEND LOOKS DRY WITH HIGHS IN THE MID 70S AND DEWPOINTS IN THE 50S AS SFC HIGH PRESSURE SETTLES OVER THE GREAT LAKES. ANOTHER SHORT WAVE WILL DROP SOUTH FROM NORTHERN ONTARIO DURING THE MONDAY/TUESDAY TIME FRAME. SIMILAR TO THE LAST FRONT...THERE WON/T BE MUCH MOISTURE WITH THIS FRONT EITHER. LOW CHANCES OF SHOWERS WILL COVER THIS TROUGH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 752 AM EDT TUE AUG 6 2013 NUMEROUS MVFR CIGS AND SCATTERED RAIN SHOWERS THIS MORNING SHOULD TRANSITION TO PRIMARILY VFR CONDITIONS FOR THIS AFTERNOON INTO THIS EVENING. MORNING STRATUS DECK WITH BASES OF 1500-2500 FT IS EXPECTED TO LIFT TO A DIURNAL CUMULUS DECK WITH BASES AROUND 3500 FT THIS AFTERNOON. SOME IFR CIGS ARE POSSIBLE THROUGH MID MORNING WEST OF HWY 131 INCLUDING MKG. WHILE THE THUNDER THREAT IS NOT ZERO THIS AFTERNOON AND EVENING... PROBABLY THE BEST CHANCE OF TSTMS WILL COME LATE TONIGHT AFTER 06Z ESPECIALLY ALONG AND WEST OF HWY 131. && .MARINE... ISSUED AT 347 PM EDT TUE AUG 6 2013 HAVE HELD OFF ON ANY SMALL CRAFT ADVISORIES OR BEACH HAZARDS STATEMENTS AS THE WINDS AND WAVES IN TODAY/S MODEL RUNS ARE NOT AS SIGNIFICANT AS LAST NIGHT OR YESTERDAY. IT APPEARS AT THIS POINT IN BOTH THE SOUTHERLY FLOW TONIGHT AND THE NORTH FLOW BEHIND THE FRONT TOMORROW THAT WE REMAIN BELOW CRITERIA. AM A BIT CONCERNED THOUGH BASED ON THE WINDS SEEN IN BUFKIT THAT WE WON/T INDEED BE HIGHER BOTH TONIGHT...WEDNESDAY AND WEDNESDAY NIGHT. WE WILL SEE AS WE PROGRESS THROUGH THE EVENING AS BUFKIT WOULD SUGGEST INCREASING WINDS IN THE 04Z-08Z TIME FRAME. WE PLAY THINGS LOWER AT THIS POINT BUT WATCH CAUTIOUSLY AND CLOSELY. && .HYDROLOGY... ISSUED AT 347 PM EDT TUE AUG 6 2013 NO SIGNIFICANT HYDRO ISSUES EXPECTED THROUGH THE NEXT COUPLE DAYS WITH NEAR NORMAL FLOWS IN PLACE NOW AND FORECAST RAINFALL IS NOT EXPECTED TO BE WIDESPREAD OR OVERLY HEAVY. RAINFALL LAST NIGHT WAS QUITE LIMITED AS WELL SO WE ARE STARTING OFF WITH FAIRLY DRY GROUND OVER MUCH OF THE AREA. RAINFALL IS EXPECTED TONIGHT THROUGH WEDNESDAY...BUT IT WILL BE ASSOCIATED WITH THUNDERSTORM COMPLEXES THAT WILL BE TRAVERSING THE AREA AT A DECENT CLIP. THE FIRST COMES LATE TONIGHT AS STORMS THAT FIRE IN MINNESOTA THIS EVENING TRY TO MOVE ACROSS LAKE MICHIGAN AFTER MIDNIGHT. THESE STORMS WILL LIKELY AFFECT CENTRAL LOWER MICHIGAN. SCATTERED SHOWERS AND STORMS WILL THEN TRAVERSE MUCH OF THE AREA LATE TONIGHT AND WEDNESDAY MORNING. A MORE CONCENTRATED AREA OF SHOWERS AND STORMS WILL AFFECT THE EASTERN TO SOUTHEASTERN HALF OF THE AREA WEDNESDAY AFTERNOON. WE COULD SEE GENERAL RAINFALL AMOUNTS ON THE ORDER OF A QUARTER TO HALF INCH WITH ISOLATED AMOUNTS AROUND AN INCH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...DUKE SHORT TERM...DUKE LONG TERM...93 AVIATION...MEADE HYDROLOGY...DUKE MARINE...DUKE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
324 PM EDT TUE AUG 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 548 AM EDT TUE AUG 6 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNUSUALLY DEEP VORTEX FOR EARLY AUG CENTERED JUST S OF HUDSON BAY ALONG THE MANITOBA/ONTARIO BORDER. ACROSS THE UPPER LAKES...FLOW HAS BECOME MORE WESTERLY OVER THE LAST DAY OR TWO IN RESPONSE TO THE DEEPENING/EXPANDING VORTEX THAT HAS BEEN DRIFTING S. SEVERAL SHORTWAVES ARE EVIDENT UPSTREAM WITH 2 MORE NOTABLE WAVES OVER ERN MT/SRN SASKATCHEWAN AND OVER ERN ALBERTA. THESE 2 WAVES WILL POWER A COLD FRONT ACROSS UPPER MI TONIGHT AND WEDNESDAY MORNING. CLOSER TO HOME...ISOLD/SCT SHRA (EVEN ISOLD TSRA AT TIMES) HAVE BEEN OCCURRING OVER THE LAST SEVERAL HRS OVER WRN UPPER MI/ADJACENT LAKE SUPERIOR. THESE SHRA ARE JUST AHEAD OF A 700MB TROF AND SURGE OF MIDLEVEL DRYING PER BY LATEST RUC. FOCUS EARLY THIS MORNING WILL BE ON THE ISOLD/SCT SHRA OVER THE W. AS AFOREMENTIONED 700MB TROF CONTINUES TO PUSH E...WILL PROBABLY CONTINUE TO SEE SOME SHRA SPREAD E INTO CNTRL UPPER MI OVER THE NEXT SEVERAL HRS. LATEST SPC MESOANALYSIS SHOWS MUCAPE AROUND 250J/KG... SO THERE MIGHT BE AN OCNL LIGHTNING STRIKE THOUGH THERE HAS NOT BEEN ANY CG STRIKES FOR THE LAST COUPLE OF HRS. AS THE TROF CONTINUES EASTWARD...IT WILL COINCIDE WITH THE HEATING CYCLE AND SHOULD AID SHRA/TSRA DEVELOPMENT OVER THE ERN PART OF THE FCST AREA LATE THIS MORNING/EARLY THIS AFTN...ESPECIALLY INLAND FROM LAKE MICHIGAN. SOME HIGH RES GUIDANCE (NAM NEST AND RUC13) INDICATE LAKE BREEZE WILL DEVELOP OFF LAKE SUPERIOR OVER THE E...BUT WILL MAKE LIMITED INLAND PROGRESS. IF SO...CONVERGENCE ZONE WILL BE A GOOD FOCAL POINT FOR CONVECTION. TO THE W ACROSS THE W HALF OF UPPER MI...THE SAME HIGH RES GUIDANCE POINTS TO A MORE ACTIVE INLAND PUSH OF LAKE SUPERIOR LAKE BREEZE. IN THE FLOW UPSTREAM...THERE ARE PROBABLY SOME SUBTLE SHORTWAVES PRESENT GIVEN THE SCT CLUSTERS OF SHRA/TSRA THAT WERE PRESENT EARLIER IN THE NIGHT ACROSS THE NRN PLAINS. WITH EXPECTATION OF LOW CLOUDS CLEARING OUT/TRANSITIONING TO CU FIELD...DAYTIME HEATING WILL LIKELY BE SUFFICIENT TO RAISE MLCAPE TO 500J/KG OR SO PER NAM/GFS. LAKE BREEZE AND ANY SUBTLE SHORTWAVES SHOULD THEN SUPPORT SCT SHRA/TSRA DEVELOPMENT. WITH DEEP LAYER SHEAR AROUND 35KT...SOME ORGANIZED/STRONGER STORMS ARE POSSIBLE. IF CAPE ENDS UP HIGHER THAN CURRENTLY EXPECTED...THERE MIGHT BE AN ISOLD SVR STORM OR TWO. TONIGHT...THE STRONGER SHORTWAVES WELL UPSTREAM WILL PUSH A COLD FRONT INTO UPPER MI. AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...MODELS CONTINUE TO POINT TOWARD A GOOD POTENTIAL OF SHRA/TSRA SPREADING ACROSS THE FCST AREA. WITH RATHER VIGOROUS DEEP LAYER FORCING...STRONG MOISTURE TRANSPORT AND SHARP LOW LEVEL TROF SHIFTING E...WILL RETAIN LIKELY POPS SPREADING E ACROSS THE AREA TONIGHT. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 548 AM EDT TUE AUG 6 2013 AMPLIFIED UPPER AIR PATTERN PERSISTS THROUGH THE UPCOMING WEEKEND AND LIKELY INTO NEXT WEEK AS WELL. MEAN TROUGHING DOMINATES MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES. PRIMARY RESULT OF THIS PATTERN WILL BE CONTINUATION OF COOLER THAN NORMAL TEMPERATURES THROUGH AT LEAST MID AUGUST ACROSS UPPER GREAT LAKES REGION. TO START OUT ON WEDNESDAY...MAIN FEATURES ALOFT ARE CLOSED OFF UPPER LOW CENTERED ALONG MANITOBA AND NORTHERN ONTARIO BORDER...SHARP WEST TO EAST RIDGE OVER FAR NORTHERN CANADA AND A DOUBLE BARRELED TROUGH EXTENDING FROM THE NORTH POLE SOUTHWEST ACROSS ALASKA AND TO THE NORTHERN PORTIONS OF PACIFIC OCEAN. NOT A WHOLE LOT OF CHANGE WRT LOCATIONS OF SAID FEATURES THROUGH THE LONG TERM. ONLY THING THAT DOES CHANGE IS UPPER LOW OVER ONTARIO SLIDES ACROSS QUEBEC THIS WEEKEND AS STRONGER JET ENERGY BECOMES PLACED OUT AHEAD OF THE TROUGH...KEEPING IT MORE PROGRESSIVE. MAIN CHANCE OF RAIN IN THIS PATTERN WILL BE RIGHT OFF THE BAT ON WEDNESDAY MORNING OVER EAST HALF OF CWA AS COLD FRONT MOVES THROUGH REGION. ADDITIONAL CHANCES OF RAIN POSSIBLE THURSDAY NIGHT INTO FRIDAY AS SECONDARY LOW PRESSURE SYSTEM AND COLD FRONT CROSS THE AREA. GENERALLY LOOKS QUIET THROUGH THE WEEKEND...BUT COOL. NEXT CHANCE OF RAIN PROBABLY ARRIVES LATER SUNDAY NIGHT INTO MONDAY AS SHORTWAVES DROP ACROSS AREA IN NW FLOW ALOFT. COLD FRONT SHOULD BE OVER CNTRL UPR MICHIGAN TO START THE DAY ON WEDNESDAY...QUICKLY HEADING EAST TO AROUND ERY BTWN 15Z-18Z. NAM STILL ON THE FAST SIDE...WHILE ECMWF IS SLOWEST. COMPROMISE SOLN WITH FRONT IS THE GFS/GEM-REGIONAL AS WELL AS NCEP WRF-ARW/NMM. MAJORITY OF WIDESPREAD SHRA/TSRA WILL BE ALONG AND AHEAD OF FRONT IN WARM AIR ADVECTION REGIME. GOING FCST LOOKS PRETTY GOOD. CHANGES TO POPS ON WEDNESDAY WITH FROPA PRETTY MINIMAL. KEPT LIKELY POPS OVR FAR EAST THROUGH 15Z...THEN TRIMMED BACK QUICKLY WITH ARRIVAL OF STRONG MID-LEVEL DRYING AND AS PRIMARY H85 MOISTURE ADVECTION IS EAST OF CWA. SOUNDINGS INDICATE LINGERING LOW-LEVEL MOISTURE BEHIND COLD FRONT THAT COULD LEAD TO BRIEF PERIOD OF LGT RAIN/DRIZZLE IN THE MORNING FOR AREAS NEAR LK SUPERIOR. EVENTUALLY...BLYR BECOMING MIXED ALONG WITH NEGATIVE SFC-H85 THETA-E ADVECTION WILL SHUT DOWN ANY LINGERING PRECIP BY MIDDAY. HAVE NO POPS AFTER 18Z WHICH WAS A BIT OF A CHANGE COMPARED TO PREVIOUS FCST. BKN CU/SC DECK MAY REMAIN LONGER THAN THIS...BUT EVEN THAT SHOULD TEND TO MIX OUT TO PARTLY CLOUDY SKIES BY MID-LATE AFTN. TEMPS TRICKY WITH FROPA AS 925-850MB TEMPS JUST AHEAD OF FRONT ARE PRETTY WARM. FIGURING OUT HOW THE WARM AIR BALANCES BTWN COOLING FROM CLOUDS/PRECIP IS MAIN HURDLE. WILL GO FOR MAX TEMPS TOPPING OUT IN THE LOW 70S...WARMEST SOUTH CENTRAL. TEMPS ALONG LK SUPERIOR COULD RISE EARLY ON...BUT THEN FALL BACK IN THE AFTN WITH INCREASING ONSHORE FLOW. SHOULD BE ESPECIALLY NOTABLE NEAR MQT-P53. FOG THAT IS DEVELOPING ACROSS LK SUPERIOR CURRENTLY MAY GET SHOVED ONSHORE TOO FOR A WHILE. SFC HIGH RIDGES IN FROM CANADIAN PRAIRIE PROVINCES WEDNESDAY NIGHT INTO THURSDAY AHEAD OF NEXT COLD FRONT. H85 WINDS STAY ONSHORE ALL NIGHT...BUT LOWEST LEVEL WINDS THROUGH 900MB BECOME LESS SO...ALLOWING POTENTIAL FOR TYPICAL COOL SPOTS INLAND FROM THE GREAT LAKES TO SEE TEMPS FALL INTO THE LOWER 40S. LIGHT GRADIENT WINDS ON THURSDAY ALLOWS IN LIGHT LAKE BREEZES ALONG BOTH SUPERIOR AND MICHIGAN. AWAY FM LOCAL COOLING THOUGH...TEMPS SHOULD BOUNCE BACK INTO AT LEAST THE LOWER 70S MOST AREAS GIVEN H85 TEMPS WARMER THAN +10C. THICKENING MID CLOUDS /H6-H5/ FOR WEST HALF BY AFTN AS WARM AIR ADVECTION DEVELOPS AHEAD OF THE COLD FRONT. GFS HAS SHOWED STEADY TREND IN BACKING OFF QPF INTO WESTERN TIER. USED A BLEND OF MORE CONSISTENT ECMWF AND THE DRIER TRENDING GFS. RESULT WAS SOME LOWER CHANCE POPS FOR WESTERN LK SUPERIOR/ISLE ROYALE ON NOSE OF H85-H7 MOISTURE ADVECTION. AS SFC LOW SPINS OVER NORTHERN ONTARIO THE COLD FRONT WILL SLOWLY SINK NORTH TO SOUTH ACROSS LK SUPERIOR ON THURSDAY NIGHT. BEST CHANCE FOR SHRA/ISOLD TSRA WILL BE OVR LK SUPERIOR DUE TO H85 TEMP ADVECTION/WEAK LOW-LEVEL JET AND SOME LOW-LEVEL FRONTAL CONVERGENCE. TEMPS WILL BE ON THE MILD SIDE AGAIN WITH SOUTH WINDS/WARM AIR ADVECTION AHEAD OF FRONT. COLD FRONT WORKS ACROSS UPR MICHIGAN ON FRIDAY...SO WILL KEEP WITH SOME LOWER CHANCE POPS. COOLING BEGINS ON FRIDAY...ESPECIALLY NEAR LK SUPERIOR. INLAND...TEMPS MAY END UP ONLY A COUPLE DEGREES COOLER THAN THURSDAY. STRONG DRYING BEHIND FRONT FOR FRIDAY NIGHT AND SATURDAY. JUST SOME SCT CU SHOULD DEVELOP DURING PEAK HEATING ON SATURDAY. H85 TEMPS ONLY UP TO +6C WITH STRONGER ONSHORE FLOW WILL LEAD TO A COOL DAY BY AUGUST STANDARDS WITH READINGS IN THE UPPER 50S/NEAR 60 ALONG LK SUPERIOR AND MAYBE REACHING 70 DEGREES IN THE FAR SOUTH CENTRAL NEAR MNM. 60S ELSEWHERE...WHICH IS AT LEAST 10 DEGREES BLO NORMAL. NOT MUCH IN WAY OF CHANGES TO REST OF CONSENSUS GRIDS FOR EXTENDED. SLIGHT CHANCE POPS FOR SUNDAY...THOUGH THESE ARE BIASED BY A LATEST GFS WHICH TRENDED MUCH WETTER FOR PARTS OF CWA COMPARED TO PREVIOUS RUNS. ECMWF INDICATES SMALL CHANCES OF INSTABILITY SHRA/TSRA AS ANOTHER STRONGER WAVE OR TWO /CURRENTLY WITHIN THE LARGER TROUGH FM ALASKA TO THE NORTH POLE/ DROPS ACROSS UPPER LAKES. POCKET OF STEEPER MID-LEVEL LAPSE RATES WOULD JUSTIFY AT LEAST A MENTION OF TSRA DURING PEAK HEATING OF SUNDAY AFTN LINGERING INTO SUN EVENING. SIMILAR SETUP FOR MONDAY THOUGH BY THAT TIME BETTER FORCING IS SLIDING EAST AND SOUTH OF LK SUPERIOR REGION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1151 AM EDT TUE AUG 6 2013 SLIGHTLY DRIER AIR ACROSS NE MN THIS MORNING HAS HAD A DIFFICULT TIME MOVING INTO UPPER MI. EVEN WITH ABUNDANT LOW LEVEL MOISTURE...AND AN ADDITIONAL PUSH OUT OF WI ON S-SW WINDS...CEILINGS HAVE BEEN ABLE TO SLOWLY RISE INTO MVFR CATEGORY THANKS IN PART TO BETTER MIXING /DAYTIME HEATING/. VFR CONDITIONS WILL BE POSSIBLE THIS AFTERNOON AHEAD OF A COLD FRONT NEARING FROM MN...WITH DETERIORATING CONDITIONS AGAIN BY THE MID-LATE EVENING HOURS. THERE IS A POTENTIAL FOR A BROKEN LINE OF POP UP SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI THIS AFTERNOON. WILL KEEP MENTION OF VCSH AT SAW...WITH THE POTENTIAL OF ADDING TS/CB IF ANYTHING LOOKS MORE CERTAIN. COLD FRONT WILL MOVE INTO UPPER MI TONIGHT...BRINGING A PERIOD OF SHRA/TS AND A RETURN TO MVFR AND POSSIBLY IFR CONDITIONS. ONCE FRONT PASSES...UPSLOPE FLOW AT KIWD/KCMX AND TO A LESSER EXTENT SAW WILL RESULT IN LIFR CONDITIONS WHICH WILL LINGER THROUGH THE MID MORNING HOURS BEFORE QUICKLY CLEARING DURING THE MID-LATE MORNING HOURS W TO E. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 323 PM EDT TUE AUG 6 2013 WIND GUSTS SHOULD REMAIN AT OR BELOW 25KTS...WITH THE STRONGEST GUSTS OUT OF THE W TO NW EXPECTED LATE TONIGHT THROUGH WEDNESDAY CENTRAL AND EAST...AND AGAIN FRIDAY AFTERNOON AND EVENING BEHIND A COUPLE OF COLD FRONT SWINGING ACROSS LAKE SUPERIOR. LOW PRESSURE ACROSS WESTERN LAKE SUPERIOR WILL CONTINUE ACROSS LAKE SUPERIOR THROUGH WEDNESDAY MORNING. PATCHY TO AREAS OF FOG SHOULD DIMINISH IN COVERAGE DURING THE DAY WEDNESDAY AS DRIER AIR SLIDES OVERHEAD. EXPECT HIGH PRESSURE TO BUILD EAST INTO THE UPPER GREAT LAKES BY THURSDAY MORNING. AS THE HIGH SHIFTS EAST...A TROUGH WILL MOVE ACROSS LAKE SUPERIOR THURSDAY NIGHT THROUGH FRIDAY MORNING. HIGH PRESSURE WILL THEN BUILD SOUTHEAST INTO THE UPPER MISSISSIPPI VALLEY SATURDAY...AND LINGER ACROSS THE REGION THROUGH SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...KF MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1152 AM EDT TUE AUG 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 548 AM EDT TUE AUG 6 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNUSUALLY DEEP VORTEX FOR EARLY AUG CENTERED JUST S OF HUDSON BAY ALONG THE MANITOBA/ONTARIO BORDER. ACROSS THE UPPER LAKES...FLOW HAS BECOME MORE WESTERLY OVER THE LAST DAY OR TWO IN RESPONSE TO THE DEEPENING/EXPANDING VORTEX THAT HAS BEEN DRIFTING S. SEVERAL SHORTWAVES ARE EVIDENT UPSTREAM WITH 2 MORE NOTABLE WAVES OVER ERN MT/SRN SASKATCHEWAN AND OVER ERN ALBERTA. THESE 2 WAVES WILL POWER A COLD FRONT ACROSS UPPER MI TONIGHT AND WEDNESDAY MORNING. CLOSER TO HOME...ISOLD/SCT SHRA (EVEN ISOLD TSRA AT TIMES) HAVE BEEN OCCURRING OVER THE LAST SEVERAL HRS OVER WRN UPPER MI/ADJACENT LAKE SUPERIOR. THESE SHRA ARE JUST AHEAD OF A 700MB TROF AND SURGE OF MIDLEVEL DRYING PER BY LATEST RUC. FOCUS EARLY THIS MORNING WILL BE ON THE ISOLD/SCT SHRA OVER THE W. AS AFOREMENTIONED 700MB TROF CONTINUES TO PUSH E...WILL PROBABLY CONTINUE TO SEE SOME SHRA SPREAD E INTO CNTRL UPPER MI OVER THE NEXT SEVERAL HRS. LATEST SPC MESOANALYSIS SHOWS MUCAPE AROUND 250J/KG... SO THERE MIGHT BE AN OCNL LIGHTNING STRIKE THOUGH THERE HAS NOT BEEN ANY CG STRIKES FOR THE LAST COUPLE OF HRS. AS THE TROF CONTINUES EASTWARD...IT WILL COINCIDE WITH THE HEATING CYCLE AND SHOULD AID SHRA/TSRA DEVELOPMENT OVER THE ERN PART OF THE FCST AREA LATE THIS MORNING/EARLY THIS AFTN...ESPECIALLY INLAND FROM LAKE MICHIGAN. SOME HIGH RES GUIDANCE (NAM NEST AND RUC13) INDICATE LAKE BREEZE WILL DEVELOP OFF LAKE SUPERIOR OVER THE E...BUT WILL MAKE LIMITED INLAND PROGRESS. IF SO...CONVERGENCE ZONE WILL BE A GOOD FOCAL POINT FOR CONVECTION. TO THE W ACROSS THE W HALF OF UPPER MI...THE SAME HIGH RES GUIDANCE POINTS TO A MORE ACTIVE INLAND PUSH OF LAKE SUPERIOR LAKE BREEZE. IN THE FLOW UPSTREAM...THERE ARE PROBABLY SOME SUBTLE SHORTWAVES PRESENT GIVEN THE SCT CLUSTERS OF SHRA/TSRA THAT WERE PRESENT EARLIER IN THE NIGHT ACROSS THE NRN PLAINS. WITH EXPECTATION OF LOW CLOUDS CLEARING OUT/TRANSITIONING TO CU FIELD...DAYTIME HEATING WILL LIKELY BE SUFFICIENT TO RAISE MLCAPE TO 500J/KG OR SO PER NAM/GFS. LAKE BREEZE AND ANY SUBTLE SHORTWAVES SHOULD THEN SUPPORT SCT SHRA/TSRA DEVELOPMENT. WITH DEEP LAYER SHEAR AROUND 35KT...SOME ORGANIZED/STRONGER STORMS ARE POSSIBLE. IF CAPE ENDS UP HIGHER THAN CURRENTLY EXPECTED...THERE MIGHT BE AN ISOLD SVR STORM OR TWO. TONIGHT...THE STRONGER SHORTWAVES WELL UPSTREAM WILL PUSH A COLD FRONT INTO UPPER MI. AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...MODELS CONTINUE TO POINT TOWARD A GOOD POTENTIAL OF SHRA/TSRA SPREADING ACROSS THE FCST AREA. WITH RATHER VIGOROUS DEEP LAYER FORCING...STRONG MOISTURE TRANSPORT AND SHARP LOW LEVEL TROF SHIFTING E...WILL RETAIN LIKELY POPS SPREADING E ACROSS THE AREA TONIGHT. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 548 AM EDT TUE AUG 6 2013 AMPLIFIED UPPER AIR PATTERN PERSISTS THROUGH THE UPCOMING WEEKEND AND LIKELY INTO NEXT WEEK AS WELL. MEAN TROUGHING DOMINATES MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES. PRIMARY RESULT OF THIS PATTERN WILL BE CONTINUATION OF COOLER THAN NORMAL TEMPERATURES THROUGH AT LEAST MID AUGUST ACROSS UPPER GREAT LAKES REGION. TO START OUT ON WEDNESDAY...MAIN FEATURES ALOFT ARE CLOSED OFF UPPER LOW CENTERED ALONG MANITOBA AND NORTHERN ONTARIO BORDER...SHARP WEST TO EAST RIDGE OVER FAR NORTHERN CANADA AND A DOUBLE BARRELED TROUGH EXTENDING FROM THE NORTH POLE SOUTHWEST ACROSS ALASKA AND TO THE NORTHERN PORTIONS OF PACIFIC OCEAN. NOT A WHOLE LOT OF CHANGE WRT LOCATIONS OF SAID FEATURES THROUGH THE LONG TERM. ONLY THING THAT DOES CHANGE IS UPPER LOW OVER ONTARIO SLIDES ACROSS QUEBEC THIS WEEKEND AS STRONGER JET ENERGY BECOMES PLACED OUT AHEAD OF THE TROUGH...KEEPING IT MORE PROGRESSIVE. MAIN CHANCE OF RAIN IN THIS PATTERN WILL BE RIGHT OFF THE BAT ON WEDNESDAY MORNING OVER EAST HALF OF CWA AS COLD FRONT MOVES THROUGH REGION. ADDITIONAL CHANCES OF RAIN POSSIBLE THURSDAY NIGHT INTO FRIDAY AS SECONDARY LOW PRESSURE SYSTEM AND COLD FRONT CROSS THE AREA. GENERALLY LOOKS QUIET THROUGH THE WEEKEND...BUT COOL. NEXT CHANCE OF RAIN PROBABLY ARRIVES LATER SUNDAY NIGHT INTO MONDAY AS SHORTWAVES DROP ACROSS AREA IN NW FLOW ALOFT. COLD FRONT SHOULD BE OVER CNTRL UPR MICHIGAN TO START THE DAY ON WEDNESDAY...QUICKLY HEADING EAST TO AROUND ERY BTWN 15Z-18Z. NAM STILL ON THE FAST SIDE...WHILE ECMWF IS SLOWEST. COMPROMISE SOLN WITH FRONT IS THE GFS/GEM-REGIONAL AS WELL AS NCEP WRF-ARW/NMM. MAJORITY OF WIDESPREAD SHRA/TSRA WILL BE ALONG AND AHEAD OF FRONT IN WARM AIR ADVECTION REGIME. GOING FCST LOOKS PRETTY GOOD. CHANGES TO POPS ON WEDNESDAY WITH FROPA PRETTY MINIMAL. KEPT LIKELY POPS OVR FAR EAST THROUGH 15Z...THEN TRIMMED BACK QUICKLY WITH ARRIVAL OF STRONG MID-LEVEL DRYING AND AS PRIMARY H85 MOISTURE ADVECTION IS EAST OF CWA. SOUNDINGS INDICATE LINGERING LOW-LEVEL MOISTURE BEHIND COLD FRONT THAT COULD LEAD TO BRIEF PERIOD OF LGT RAIN/DRIZZLE IN THE MORNING FOR AREAS NEAR LK SUPERIOR. EVENTUALLY...BLYR BECOMING MIXED ALONG WITH NEGATIVE SFC-H85 THETA-E ADVECTION WILL SHUT DOWN ANY LINGERING PRECIP BY MIDDAY. HAVE NO POPS AFTER 18Z WHICH WAS A BIT OF A CHANGE COMPARED TO PREVIOUS FCST. BKN CU/SC DECK MAY REMAIN LONGER THAN THIS...BUT EVEN THAT SHOULD TEND TO MIX OUT TO PARTLY CLOUDY SKIES BY MID-LATE AFTN. TEMPS TRICKY WITH FROPA AS 925-850MB TEMPS JUST AHEAD OF FRONT ARE PRETTY WARM. FIGURING OUT HOW THE WARM AIR BALANCES BTWN COOLING FROM CLOUDS/PRECIP IS MAIN HURDLE. WILL GO FOR MAX TEMPS TOPPING OUT IN THE LOW 70S...WARMEST SOUTH CENTRAL. TEMPS ALONG LK SUPERIOR COULD RISE EARLY ON...BUT THEN FALL BACK IN THE AFTN WITH INCREASING ONSHORE FLOW. SHOULD BE ESPECIALLY NOTABLE NEAR MQT-P53. FOG THAT IS DEVELOPING ACROSS LK SUPERIOR CURRENTLY MAY GET SHOVED ONSHORE TOO FOR A WHILE. SFC HIGH RIDGES IN FROM CANADIAN PRAIRIE PROVINCES WEDNESDAY NIGHT INTO THURSDAY AHEAD OF NEXT COLD FRONT. H85 WINDS STAY ONSHORE ALL NIGHT...BUT LOWEST LEVEL WINDS THROUGH 900MB BECOME LESS SO...ALLOWING POTENTIAL FOR TYPICAL COOL SPOTS INLAND FROM THE GREAT LAKES TO SEE TEMPS FALL INTO THE LOWER 40S. LIGHT GRADIENT WINDS ON THURSDAY ALLOWS IN LIGHT LAKE BREEZES ALONG BOTH SUPERIOR AND MICHIGAN. AWAY FM LOCAL COOLING THOUGH...TEMPS SHOULD BOUNCE BACK INTO AT LEAST THE LOWER 70S MOST AREAS GIVEN H85 TEMPS WARMER THAN +10C. THICKENING MID CLOUDS /H6-H5/ FOR WEST HALF BY AFTN AS WARM AIR ADVECTION DEVELOPS AHEAD OF THE COLD FRONT. GFS HAS SHOWED STEADY TREND IN BACKING OFF QPF INTO WESTERN TIER. USED A BLEND OF MORE CONSISTENT ECMWF AND THE DRIER TRENDING GFS. RESULT WAS SOME LOWER CHANCE POPS FOR WESTERN LK SUPERIOR/ISLE ROYALE ON NOSE OF H85-H7 MOISTURE ADVECTION. AS SFC LOW SPINS OVER NORTHERN ONTARIO THE COLD FRONT WILL SLOWLY SINK NORTH TO SOUTH ACROSS LK SUPERIOR ON THURSDAY NIGHT. BEST CHANCE FOR SHRA/ISOLD TSRA WILL BE OVR LK SUPERIOR DUE TO H85 TEMP ADVECTION/WEAK LOW-LEVEL JET AND SOME LOW-LEVEL FRONTAL CONVERGENCE. TEMPS WILL BE ON THE MILD SIDE AGAIN WITH SOUTH WINDS/WARM AIR ADVECTION AHEAD OF FRONT. COLD FRONT WORKS ACROSS UPR MICHIGAN ON FRIDAY...SO WILL KEEP WITH SOME LOWER CHANCE POPS. COOLING BEGINS ON FRIDAY...ESPECIALLY NEAR LK SUPERIOR. INLAND...TEMPS MAY END UP ONLY A COUPLE DEGREES COOLER THAN THURSDAY. STRONG DRYING BEHIND FRONT FOR FRIDAY NIGHT AND SATURDAY. JUST SOME SCT CU SHOULD DEVELOP DURING PEAK HEATING ON SATURDAY. H85 TEMPS ONLY UP TO +6C WITH STRONGER ONSHORE FLOW WILL LEAD TO A COOL DAY BY AUGUST STANDARDS WITH READINGS IN THE UPPER 50S/NEAR 60 ALONG LK SUPERIOR AND MAYBE REACHING 70 DEGREES IN THE FAR SOUTH CENTRAL NEAR MNM. 60S ELSEWHERE...WHICH IS AT LEAST 10 DEGREES BLO NORMAL. NOT MUCH IN WAY OF CHANGES TO REST OF CONSENSUS GRIDS FOR EXTENDED. SLIGHT CHANCE POPS FOR SUNDAY...THOUGH THESE ARE BIASED BY A LATEST GFS WHICH TRENDED MUCH WETTER FOR PARTS OF CWA COMPARED TO PREVIOUS RUNS. ECMWF INDICATES SMALL CHANCES OF INSTABILITY SHRA/TSRA AS ANOTHER STRONGER WAVE OR TWO /CURRENTLY WITHIN THE LARGER TROUGH FM ALASKA TO THE NORTH POLE/ DROPS ACROSS UPPER LAKES. POCKET OF STEEPER MID-LEVEL LAPSE RATES WOULD JUSTIFY AT LEAST A MENTION OF TSRA DURING PEAK HEATING OF SUNDAY AFTN LINGERING INTO SUN EVENING. SIMILAR SETUP FOR MONDAY THOUGH BY THAT TIME BETTER FORCING IS SLIDING EAST AND SOUTH OF LK SUPERIOR REGION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1151 AM EDT TUE AUG 6 2013 SLIGHTLY DRIER AIR ACROSS NE MN THIS MORNING HAS HAD A DIFFICULT TIME MOVING INTO UPPER MI. EVEN WITH ABUNDANT LOW LEVEL MOISTURE...AND AN ADDITIONAL PUSH OUT OF WI ON S-SW WINDS...CEILINGS HAVE BEEN ABLE TO SLOWLY RISE INTO MVFR CATEGORY THANKS IN PART TO BETTER MIXING /DAYTIME HEATING/. VFR CONDITIONS WILL BE POSSIBLE THIS AFTERNOON AHEAD OF A COLD FRONT NEARING FROM MN...WITH DETERIORATING CONDITIONS AGAIN BY THE MID-LATE EVENING HOURS. THERE IS A POTENTIAL FOR A BROKEN LINE OF POP UP SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI THIS AFTERNOON. WILL KEEP MENTION OF VCSH AT SAW...WITH THE POTENTIAL OF ADDING TS/CB IF ANYTHING LOOKS MORE CERTAIN. COLD FRONT WILL MOVE INTO UPPER MI TONIGHT...BRINGING A PERIOD OF SHRA/TS AND A RETURN TO MVFR AND POSSIBLY IFR CONDITIONS. ONCE FRONT PASSES...UPSLOPE FLOW AT KIWD/KCMX AND TO A LESSER EXTENT SAW WILL RESULT IN LIFR CONDITIONS WHICH WILL LINGER THROUGH THE MID MORNING HOURS BEFORE QUICKLY CLEARING DURING THE MID-LATE MORNING HOURS W TO E. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 548 AM EDT TUE AUG 6 2013 LIGHT WINDS THROUGH MUCH OF TONIGHT THEN WINDS WILL KICK UP AS COLD FRONT CROSSES LK SUPERIOR LATE TONIGHT THROUGH WEDNESDAY MORNING. NW WINDS BEHIND COLD FRONT MAY REACH 20-25 KTS IN GUSTS. SHOWERS AND STORMS LIKELY WITH THE FRONTAL PASSAGE. SHIP REPORTS INDICATE FOG HAS FORMED OVERNIGHT WITH ARRIVAL OF MOIST AIRMASS. EXPECT THE FOG TO CONTINUE UNTIL WEDNESDAY AFTERNOON WHEN DRIER AIR SCOURS OUT THE FOG. WINDS DIMINISH TO LESS THAN 20 KTS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH HIGH PRESSURE OVERHEAD. STRONGER W-NW WINDS POSSIBLE FRIDAY AND FRIDAY NIGHT AS ANOTHER COLD FRONT CROSSES LAKE SUPERIOR FROM NORTH TO SOUTH. GUSTS COULD REACH OVER 25 KTS. WINDS DIMINISH TO LESS THAN 20 KTS FOR REST OF WEEKEND WITH WEAKER PRESSURE GRADIENT BY THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...KF MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
740 AM EDT TUE AUG 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 548 AM EDT TUE AUG 6 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNUSUALLY DEEP VORTEX FOR EARLY AUG CENTERED JUST S OF HUDSON BAY ALONG THE MANITOBA/ONTARIO BORDER. ACROSS THE UPPER LAKES...FLOW HAS BECOME MORE WESTERLY OVER THE LAST DAY OR TWO IN RESPONSE TO THE DEEPENING/EXPANDING VORTEX THAT HAS BEEN DRIFTING S. SEVERAL SHORTWAVES ARE EVIDENT UPSTREAM WITH 2 MORE NOTABLE WAVES OVER ERN MT/SRN SASKATCHEWAN AND OVER ERN ALBERTA. THESE 2 WAVES WILL POWER A COLD FRONT ACROSS UPPER MI TONIGHT AND WEDNESDAY MORNING. CLOSER TO HOME...ISOLD/SCT SHRA (EVEN ISOLD TSRA AT TIMES) HAVE BEEN OCCURRING OVER THE LAST SEVERAL HRS OVER WRN UPPER MI/ADJACENT LAKE SUPERIOR. THESE SHRA ARE JUST AHEAD OF A 700MB TROF AND SURGE OF MIDLEVEL DRYING PER BY LATEST RUC. FOCUS EARLY THIS MORNING WILL BE ON THE ISOLD/SCT SHRA OVER THE W. AS AFOREMENTIONED 700MB TROF CONTINUES TO PUSH E...WILL PROBABLY CONTINUE TO SEE SOME SHRA SPREAD E INTO CNTRL UPPER MI OVER THE NEXT SEVERAL HRS. LATEST SPC MESOANALYSIS SHOWS MUCAPE AROUND 250J/KG... SO THERE MIGHT BE AN OCNL LIGHTNING STRIKE THOUGH THERE HAS NOT BEEN ANY CG STRIKES FOR THE LAST COUPLE OF HRS. AS THE TROF CONTINUES EASTWARD...IT WILL COINCIDE WITH THE HEATING CYCLE AND SHOULD AID SHRA/TSRA DEVELOPMENT OVER THE ERN PART OF THE FCST AREA LATE THIS MORNING/EARLY THIS AFTN...ESPECIALLY INLAND FROM LAKE MICHIGAN. SOME HIGH RES GUIDANCE (NAM NEST AND RUC13) INDICATE LAKE BREEZE WILL DEVELOP OFF LAKE SUPERIOR OVER THE E...BUT WILL MAKE LIMITED INLAND PROGRESS. IF SO...CONVERGENCE ZONE WILL BE A GOOD FOCAL POINT FOR CONVECTION. TO THE W ACROSS THE W HALF OF UPPER MI...THE SAME HIGH RES GUIDANCE POINTS TO A MORE ACTIVE INLAND PUSH OF LAKE SUPERIOR LAKE BREEZE. IN THE FLOW UPSTREAM...THERE ARE PROBABLY SOME SUBTLE SHORTWAVES PRESENT GIVEN THE SCT CLUSTERS OF SHRA/TSRA THAT WERE PRESENT EARLIER IN THE NIGHT ACROSS THE NRN PLAINS. WITH EXPECTATION OF LOW CLOUDS CLEARING OUT/TRANSITIONING TO CU FIELD...DAYTIME HEATING WILL LIKELY BE SUFFICIENT TO RAISE MLCAPE TO 500J/KG OR SO PER NAM/GFS. LAKE BREEZE AND ANY SUBTLE SHORTWAVES SHOULD THEN SUPPORT SCT SHRA/TSRA DEVELOPMENT. WITH DEEP LAYER SHEAR AROUND 35KT...SOME ORGANIZED/STRONGER STORMS ARE POSSIBLE. IF CAPE ENDS UP HIGHER THAN CURRENTLY EXPECTED...THERE MIGHT BE AN ISOLD SVR STORM OR TWO. TONIGHT...THE STRONGER SHORTWAVES WELL UPSTREAM WILL PUSH A COLD FRONT INTO UPPER MI. AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...MODELS CONTINUE TO POINT TOWARD A GOOD POTENTIAL OF SHRA/TSRA SPREADING ACROSS THE FCST AREA. WITH RATHER VIGOROUS DEEP LAYER FORCING...STRONG MOISTURE TRANSPORT AND SHARP LOW LEVEL TROF SHIFTING E...WILL RETAIN LIKELY POPS SPREADING E ACROSS THE AREA TONIGHT. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 548 AM EDT TUE AUG 6 2013 AMPLIFIED UPPER AIR PATTERN PERSISTS THROUGH THE UPCOMING WEEKEND AND LIKELY INTO NEXT WEEK AS WELL. MEAN TROUGHING DOMINATES MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES. PRIMARY RESULT OF THIS PATTERN WILL BE CONTINUATION OF COOLER THAN NORMAL TEMPERATURES THROUGH AT LEAST MID AUGUST ACROSS UPPER GREAT LAKES REGION. TO START OUT ON WEDNESDAY...MAIN FEATURES ALOFT ARE CLOSED OFF UPPER LOW CENTERED ALONG MANITOBA AND NORTHERN ONTARIO BORDER...SHARP WEST TO EAST RIDGE OVER FAR NORTHERN CANADA AND A DOUBLE BARRELED TROUGH EXTENDING FROM THE NORTH POLE SOUTHWEST ACROSS ALASKA AND TO THE NORTHERN PORTIONS OF PACIFIC OCEAN. NOT A WHOLE LOT OF CHANGE WRT LOCATIONS OF SAID FEATURES THROUGH THE LONG TERM. ONLY THING THAT DOES CHANGE IS UPPER LOW OVER ONTARIO SLIDES ACROSS QUEBEC THIS WEEKEND AS STRONGER JET ENERGY BECOMES PLACED OUT AHEAD OF THE TROUGH...KEEPING IT MORE PROGRESSIVE. MAIN CHANCE OF RAIN IN THIS PATTERN WILL BE RIGHT OFF THE BAT ON WEDNESDAY MORNING OVER EAST HALF OF CWA AS COLD FRONT MOVES THROUGH REGION. ADDITIONAL CHANCES OF RAIN POSSIBLE THURSDAY NIGHT INTO FRIDAY AS SECONDARY LOW PRESSURE SYSTEM AND COLD FRONT CROSS THE AREA. GENERALLY LOOKS QUIET THROUGH THE WEEKEND...BUT COOL. NEXT CHANCE OF RAIN PROBABLY ARRIVES LATER SUNDAY NIGHT INTO MONDAY AS SHORTWAVES DROP ACROSS AREA IN NW FLOW ALOFT. COLD FRONT SHOULD BE OVER CNTRL UPR MICHIGAN TO START THE DAY ON WEDNESDAY...QUICKLY HEADING EAST TO AROUND ERY BTWN 15Z-18Z. NAM STILL ON THE FAST SIDE...WHILE ECMWF IS SLOWEST. COMPROMISE SOLN WITH FRONT IS THE GFS/GEM-REGIONAL AS WELL AS NCEP WRF-ARW/NMM. MAJORITY OF WIDESPREAD SHRA/TSRA WILL BE ALONG AND AHEAD OF FRONT IN WARM AIR ADVECTION REGIME. GOING FCST LOOKS PRETTY GOOD. CHANGES TO POPS ON WEDNESDAY WITH FROPA PRETTY MINIMAL. KEPT LIKELY POPS OVR FAR EAST THROUGH 15Z...THEN TRIMMED BACK QUICKLY WITH ARRIVAL OF STRONG MID-LEVEL DRYING AND AS PRIMARY H85 MOISTURE ADVECTION IS EAST OF CWA. SOUNDINGS INDICATE LINGERING LOW-LEVEL MOISTURE BEHIND COLD FRONT THAT COULD LEAD TO BRIEF PERIOD OF LGT RAIN/DRIZZLE IN THE MORNING FOR AREAS NEAR LK SUPERIOR. EVENTUALLY...BLYR BECOMING MIXED ALONG WITH NEGATIVE SFC-H85 THETA-E ADVECTION WILL SHUT DOWN ANY LINGERING PRECIP BY MIDDAY. HAVE NO POPS AFTER 18Z WHICH WAS A BIT OF A CHANGE COMPARED TO PREVIOUS FCST. BKN CU/SC DECK MAY REMAIN LONGER THAN THIS...BUT EVEN THAT SHOULD TEND TO MIX OUT TO PARTLY CLOUDY SKIES BY MID-LATE AFTN. TEMPS TRICKY WITH FROPA AS 925-850MB TEMPS JUST AHEAD OF FRONT ARE PRETTY WARM. FIGURING OUT HOW THE WARM AIR BALANCES BTWN COOLING FROM CLOUDS/PRECIP IS MAIN HURDLE. WILL GO FOR MAX TEMPS TOPPING OUT IN THE LOW 70S...WARMEST SOUTH CENTRAL. TEMPS ALONG LK SUPERIOR COULD RISE EARLY ON...BUT THEN FALL BACK IN THE AFTN WITH INCREASING ONSHORE FLOW. SHOULD BE ESPECIALLY NOTABLE NEAR MQT-P53. FOG THAT IS DEVELOPING ACROSS LK SUPERIOR CURRENTLY MAY GET SHOVED ONSHORE TOO FOR A WHILE. SFC HIGH RIDGES IN FROM CANADIAN PRAIRIE PROVINCES WEDNESDAY NIGHT INTO THURSDAY AHEAD OF NEXT COLD FRONT. H85 WINDS STAY ONSHORE ALL NIGHT...BUT LOWEST LEVEL WINDS THROUGH 900MB BECOME LESS SO...ALLOWING POTENTIAL FOR TYPICAL COOL SPOTS INLAND FROM THE GREAT LAKES TO SEE TEMPS FALL INTO THE LOWER 40S. LIGHT GRADIENT WINDS ON THURSDAY ALLOWS IN LIGHT LAKE BREEZES ALONG BOTH SUPERIOR AND MICHIGAN. AWAY FM LOCAL COOLING THOUGH...TEMPS SHOULD BOUNCE BACK INTO AT LEAST THE LOWER 70S MOST AREAS GIVEN H85 TEMPS WARMER THAN +10C. THICKENING MID CLOUDS /H6-H5/ FOR WEST HALF BY AFTN AS WARM AIR ADVECTION DEVELOPS AHEAD OF THE COLD FRONT. GFS HAS SHOWED STEADY TREND IN BACKING OFF QPF INTO WESTERN TIER. USED A BLEND OF MORE CONSISTENT ECMWF AND THE DRIER TRENDING GFS. RESULT WAS SOME LOWER CHANCE POPS FOR WESTERN LK SUPERIOR/ISLE ROYALE ON NOSE OF H85-H7 MOISTURE ADVECTION. AS SFC LOW SPINS OVER NORTHERN ONTARIO THE COLD FRONT WILL SLOWLY SINK NORTH TO SOUTH ACROSS LK SUPERIOR ON THURSDAY NIGHT. BEST CHANCE FOR SHRA/ISOLD TSRA WILL BE OVR LK SUPERIOR DUE TO H85 TEMP ADVECTION/WEAK LOW-LEVEL JET AND SOME LOW-LEVEL FRONTAL CONVERGENCE. TEMPS WILL BE ON THE MILD SIDE AGAIN WITH SOUTH WINDS/WARM AIR ADVECTION AHEAD OF FRONT. COLD FRONT WORKS ACROSS UPR MICHIGAN ON FRIDAY...SO WILL KEEP WITH SOME LOWER CHANCE POPS. COOLING BEGINS ON FRIDAY...ESPECIALLY NEAR LK SUPERIOR. INLAND...TEMPS MAY END UP ONLY A COUPLE DEGREES COOLER THAN THURSDAY. STRONG DRYING BEHIND FRONT FOR FRIDAY NIGHT AND SATURDAY. JUST SOME SCT CU SHOULD DEVELOP DURING PEAK HEATING ON SATURDAY. H85 TEMPS ONLY UP TO +6C WITH STRONGER ONSHORE FLOW WILL LEAD TO A COOL DAY BY AUGUST STANDARDS WITH READINGS IN THE UPPER 50S/NEAR 60 ALONG LK SUPERIOR AND MAYBE REACHING 70 DEGREES IN THE FAR SOUTH CENTRAL NEAR MNM. 60S ELSEWHERE...WHICH IS AT LEAST 10 DEGREES BLO NORMAL. NOT MUCH IN WAY OF CHANGES TO REST OF CONSENSUS GRIDS FOR EXTENDED. SLIGHT CHANCE POPS FOR SUNDAY...THOUGH THESE ARE BIASED BY A LATEST GFS WHICH TRENDED MUCH WETTER FOR PARTS OF CWA COMPARED TO PREVIOUS RUNS. ECMWF INDICATES SMALL CHANCES OF INSTABILITY SHRA/TSRA AS ANOTHER STRONGER WAVE OR TWO /CURRENTLY WITHIN THE LARGER TROUGH FM ALASKA TO THE NORTH POLE/ DROPS ACROSS UPPER LAKES. POCKET OF STEEPER MID-LEVEL LAPSE RATES WOULD JUSTIFY AT LEAST A MENTION OF TSRA DURING PEAK HEATING OF SUNDAY AFTN LINGERING INTO SUN EVENING. SIMILAR SETUP FOR MONDAY THOUGH BY THAT TIME BETTER FORCING IS SLIDING EAST AND SOUTH OF LK SUPERIOR REGION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 739 AM EDT TUE AUG 6 2013 ABUNDANT LOW-LEVEL MOISTURE HAS RESULTED IN LIFR CONDITIONS AT KIWD/KCMX/KSAW EARLY THIS MORNING. DAYTIME HEATING WILL WORK TO RAISE/SCATTER OUT THE STRATUS AND DISSIPATE FOG. EXPECT ALL TERMINALS TO BE VFR EARLY THIS AFTN...IF NOT SOONER. AS INSTABILITY BUILDS THIS AFTN...ISOLD/SCT SHRA/TSRA SHOULD DEVELOP OVER PARTS OF UPPER MI. KSAW PROBABLY HAS THE BEST CHC OF SEEING SOME PCPN AS LAKE BREEZE WILL HELP FOCUS SHRA ACTIVITY IN CNTRL UPPER MI. FOR NOW... INCLUDED VCSH IN THE AFTN. COLD FRONT WILL MOVE INTO UPPER MI TONIGHT...BRINGING A PERIOD OF SHRA/TSRA AND A RETURN TO MVFR AND POSSIBLY IFR CONDITIONS. ONCE FRONT PASSES...UPSLOPE FLOW AT KIWD/KCMX WILL RESULT IN LIFR CONDITIONS REDEVELOPING AT THOSE TERMINALS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 548 AM EDT TUE AUG 6 2013 LIGHT WINDS THROUGH MUCH OF TONIGHT THEN WINDS WILL KICK UP AS COLD FRONT CROSSES LK SUPERIOR LATE TONIGHT THROUGH WEDNESDAY MORNING. NW WINDS BEHIND COLD FRONT MAY REACH 20-25 KTS IN GUSTS. SHOWERS AND STORMS LIKELY WITH THE FRONTAL PASSAGE. SHIP REPORTS INDICATE FOG HAS FORMED OVERNIGHT WITH ARRIVAL OF MOIST AIRMASS. EXPECT THE FOG TO CONTINUE UNTIL WEDNESDAY AFTERNOON WHEN DRIER AIR SCOURS OUT THE FOG. WINDS DIMINISH TO LESS THAN 20 KTS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH HIGH PRESSURE OVERHEAD. STRONGER W-NW WINDS POSSIBLE FRIDAY AND FRIDAY NIGHT AS ANOTHER COLD FRONT CROSSES LAKE SUPERIOR FROM NORTH TO SOUTH. GUSTS COULD REACH OVER 25 KTS. WINDS DIMINISH TO LESS THAN 20 KTS FOR REST OF WEEKEND WITH WEAKER PRESSURE GRADIENT BY THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...ROLFSON MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
548 AM EDT TUE AUG 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 548 AM EDT TUE AUG 6 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNUSUALLY DEEP VORTEX FOR EARLY AUG CENTERED JUST S OF HUDSON BAY ALONG THE MANITOBA/ONTARIO BORDER. ACROSS THE UPPER LAKES...FLOW HAS BECOME MORE WESTERLY OVER THE LAST DAY OR TWO IN RESPONSE TO THE DEEPENING/EXPANDING VORTEX THAT HAS BEEN DRIFTING S. SEVERAL SHORTWAVES ARE EVIDENT UPSTREAM WITH 2 MORE NOTABLE WAVES OVER ERN MT/SRN SASKATCHEWAN AND OVER ERN ALBERTA. THESE 2 WAVES WILL POWER A COLD FRONT ACROSS UPPER MI TONIGHT AND WEDNESDAY MORNING. CLOSER TO HOME...ISOLD/SCT SHRA (EVEN ISOLD TSRA AT TIMES) HAVE BEEN OCCURRING OVER THE LAST SEVERAL HRS OVER WRN UPPER MI/ADJACENT LAKE SUPERIOR. THESE SHRA ARE JUST AHEAD OF A 700MB TROF AND SURGE OF MIDLEVEL DRYING PER BY LATEST RUC. FOCUS EARLY THIS MORNING WILL BE ON THE ISOLD/SCT SHRA OVER THE W. AS AFOREMENTIONED 700MB TROF CONTINUES TO PUSH E...WILL PROBABLY CONTINUE TO SEE SOME SHRA SPREAD E INTO CNTRL UPPER MI OVER THE NEXT SEVERAL HRS. LATEST SPC MESOANALYSIS SHOWS MUCAPE AROUND 250J/KG... SO THERE MIGHT BE AN OCNL LIGHTNING STRIKE THOUGH THERE HAS NOT BEEN ANY CG STRIKES FOR THE LAST COUPLE OF HRS. AS THE TROF CONTINUES EASTWARD...IT WILL COINCIDE WITH THE HEATING CYCLE AND SHOULD AID SHRA/TSRA DEVELOPMENT OVER THE ERN PART OF THE FCST AREA LATE THIS MORNING/EARLY THIS AFTN...ESPECIALLY INLAND FROM LAKE MICHIGAN. SOME HIGH RES GUIDANCE (NAM NEST AND RUC13) INDICATE LAKE BREEZE WILL DEVELOP OFF LAKE SUPERIOR OVER THE E...BUT WILL MAKE LIMITED INLAND PROGRESS. IF SO...CONVERGENCE ZONE WILL BE A GOOD FOCAL POINT FOR CONVECTION. TO THE W ACROSS THE W HALF OF UPPER MI...THE SAME HIGH RES GUIDANCE POINTS TO A MORE ACTIVE INLAND PUSH OF LAKE SUPERIOR LAKE BREEZE. IN THE FLOW UPSTREAM...THERE ARE PROBABLY SOME SUBTLE SHORTWAVES PRESENT GIVEN THE SCT CLUSTERS OF SHRA/TSRA THAT WERE PRESENT EARLIER IN THE NIGHT ACROSS THE NRN PLAINS. WITH EXPECTATION OF LOW CLOUDS CLEARING OUT/TRANSITIONING TO CU FIELD...DAYTIME HEATING WILL LIKELY BE SUFFICIENT TO RAISE MLCAPE TO 500J/KG OR SO PER NAM/GFS. LAKE BREEZE AND ANY SUBTLE SHORTWAVES SHOULD THEN SUPPORT SCT SHRA/TSRA DEVELOPMENT. WITH DEEP LAYER SHEAR AROUND 35KT...SOME ORGANIZED/STRONGER STORMS ARE POSSIBLE. IF CAPE ENDS UP HIGHER THAN CURRENTLY EXPECTED...THERE MIGHT BE AN ISOLD SVR STORM OR TWO. TONIGHT...THE STRONGER SHORTWAVES WELL UPSTREAM WILL PUSH A COLD FRONT INTO UPPER MI. AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...MODELS CONTINUE TO POINT TOWARD A GOOD POTENTIAL OF SHRA/TSRA SPREADING ACROSS THE FCST AREA. WITH RATHER VIGOROUS DEEP LAYER FORCING...STRONG MOISTURE TRANSPORT AND SHARP LOW LEVEL TROF SHIFTING E...WILL RETAIN LIKELY POPS SPREADING E ACROSS THE AREA TONIGHT. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 548 AM EDT TUE AUG 6 2013 AMPLIFIED UPPER AIR PATTERN PERSISTS THROUGH THE UPCOMING WEEKEND AND LIKELY INTO NEXT WEEK AS WELL. MEAN TROUGHING DOMINATES MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES. PRIMARY RESULT OF THIS PATTERN WILL BE CONTINUATION OF COOLER THAN NORMAL TEMPERATURES THROUGH AT LEAST MID AUGUST ACROSS UPPER GREAT LAKES REGION. TO START OUT ON WEDNESDAY...MAIN FEATURES ALOFT ARE CLOSED OFF UPPER LOW CENTERED ALONG MANITOBA AND NORTHERN ONTARIO BORDER...SHARP WEST TO EAST RIDGE OVER FAR NORTHERN CANADA AND A DOUBLE BARRELED TROUGH EXTENDING FROM THE NORTH POLE SOUTHWEST ACROSS ALASKA AND TO THE NORTHERN PORTIONS OF PACIFIC OCEAN. NOT A WHOLE LOT OF CHANGE WRT LOCATIONS OF SAID FEATURES THROUGH THE LONG TERM. ONLY THING THAT DOES CHANGE IS UPPER LOW OVER ONTARIO SLIDES ACROSS QUEBEC THIS WEEKEND AS STRONGER JET ENERGY BECOMES PLACED OUT AHEAD OF THE TROUGH...KEEPING IT MORE PROGRESSIVE. MAIN CHANCE OF RAIN IN THIS PATTERN WILL BE RIGHT OFF THE BAT ON WEDNESDAY MORNING OVER EAST HALF OF CWA AS COLD FRONT MOVES THROUGH REGION. ADDITIONAL CHANCES OF RAIN POSSIBLE THURSDAY NIGHT INTO FRIDAY AS SECONDARY LOW PRESSURE SYSTEM AND COLD FRONT CROSS THE AREA. GENERALLY LOOKS QUIET THROUGH THE WEEKEND...BUT COOL. NEXT CHANCE OF RAIN PROBABLY ARRIVES LATER SUNDAY NIGHT INTO MONDAY AS SHORTWAVES DROP ACROSS AREA IN NW FLOW ALOFT. COLD FRONT SHOULD BE OVER CNTRL UPR MICHIGAN TO START THE DAY ON WEDNESDAY...QUICKLY HEADING EAST TO AROUND ERY BTWN 15Z-18Z. NAM STILL ON THE FAST SIDE...WHILE ECMWF IS SLOWEST. COMPROMISE SOLN WITH FRONT IS THE GFS/GEM-REGIONAL AS WELL AS NCEP WRF-ARW/NMM. MAJORITY OF WIDESPREAD SHRA/TSRA WILL BE ALONG AND AHEAD OF FRONT IN WARM AIR ADVECTION REGIME. GOING FCST LOOKS PRETTY GOOD. CHANGES TO POPS ON WEDNESDAY WITH FROPA PRETTY MINIMAL. KEPT LIKELY POPS OVR FAR EAST THROUGH 15Z...THEN TRIMMED BACK QUICKLY WITH ARRIVAL OF STRONG MID-LEVEL DRYING AND AS PRIMARY H85 MOISTURE ADVECTION IS EAST OF CWA. SOUNDINGS INDICATE LINGERING LOW-LEVEL MOISTURE BEHIND COLD FRONT THAT COULD LEAD TO BRIEF PERIOD OF LGT RAIN/DRIZZLE IN THE MORNING FOR AREAS NEAR LK SUPERIOR. EVENTUALLY...BLYR BECOMING MIXED ALONG WITH NEGATIVE SFC-H85 THETA-E ADVECTION WILL SHUT DOWN ANY LINGERING PRECIP BY MIDDAY. HAVE NO POPS AFTER 18Z WHICH WAS A BIT OF A CHANGE COMPARED TO PREVIOUS FCST. BKN CU/SC DECK MAY REMAIN LONGER THAN THIS...BUT EVEN THAT SHOULD TEND TO MIX OUT TO PARTLY CLOUDY SKIES BY MID-LATE AFTN. TEMPS TRICKY WITH FROPA AS 925-850MB TEMPS JUST AHEAD OF FRONT ARE PRETTY WARM. FIGURING OUT HOW THE WARM AIR BALANCES BTWN COOLING FROM CLOUDS/PRECIP IS MAIN HURDLE. WILL GO FOR MAX TEMPS TOPPING OUT IN THE LOW 70S...WARMEST SOUTH CENTRAL. TEMPS ALONG LK SUPERIOR COULD RISE EARLY ON...BUT THEN FALL BACK IN THE AFTN WITH INCREASING ONSHORE FLOW. SHOULD BE ESPECIALLY NOTABLE NEAR MQT-P53. FOG THAT IS DEVELOPING ACROSS LK SUPERIOR CURRENTLY MAY GET SHOVED ONSHORE TOO FOR A WHILE. SFC HIGH RIDGES IN FROM CANADIAN PRAIRIE PROVINCES WEDNESDAY NIGHT INTO THURSDAY AHEAD OF NEXT COLD FRONT. H85 WINDS STAY ONSHORE ALL NIGHT...BUT LOWEST LEVEL WINDS THROUGH 900MB BECOME LESS SO...ALLOWING POTENTIAL FOR TYPICAL COOL SPOTS INLAND FROM THE GREAT LAKES TO SEE TEMPS FALL INTO THE LOWER 40S. LIGHT GRADIENT WINDS ON THURSDAY ALLOWS IN LIGHT LAKE BREEZES ALONG BOTH SUPERIOR AND MICHIGAN. AWAY FM LOCAL COOLING THOUGH...TEMPS SHOULD BOUNCE BACK INTO AT LEAST THE LOWER 70S MOST AREAS GIVEN H85 TEMPS WARMER THAN +10C. THICKENING MID CLOUDS /H6-H5/ FOR WEST HALF BY AFTN AS WARM AIR ADVECTION DEVELOPS AHEAD OF THE COLD FRONT. GFS HAS SHOWED STEADY TREND IN BACKING OFF QPF INTO WESTERN TIER. USED A BLEND OF MORE CONSISTENT ECMWF AND THE DRIER TRENDING GFS. RESULT WAS SOME LOWER CHANCE POPS FOR WESTERN LK SUPERIOR/ISLE ROYALE ON NOSE OF H85-H7 MOISTURE ADVECTION. AS SFC LOW SPINS OVER NORTHERN ONTARIO THE COLD FRONT WILL SLOWLY SINK NORTH TO SOUTH ACROSS LK SUPERIOR ON THURSDAY NIGHT. BEST CHANCE FOR SHRA/ISOLD TSRA WILL BE OVR LK SUPERIOR DUE TO H85 TEMP ADVECTION/WEAK LOW-LEVEL JET AND SOME LOW-LEVEL FRONTAL CONVERGENCE. TEMPS WILL BE ON THE MILD SIDE AGAIN WITH SOUTH WINDS/WARM AIR ADVECTION AHEAD OF FRONT. COLD FRONT WORKS ACROSS UPR MICHIGAN ON FRIDAY...SO WILL KEEP WITH SOME LOWER CHANCE POPS. COOLING BEGINS ON FRIDAY...ESPECIALLY NEAR LK SUPERIOR. INLAND...TEMPS MAY END UP ONLY A COUPLE DEGREES COOLER THAN THURSDAY. STRONG DRYING BEHIND FRONT FOR FRIDAY NIGHT AND SATURDAY. JUST SOME SCT CU SHOULD DEVELOP DURING PEAK HEATING ON SATURDAY. H85 TEMPS ONLY UP TO +6C WITH STRONGER ONSHORE FLOW WILL LEAD TO A COOL DAY BY AUGUST STANDARDS WITH READINGS IN THE UPPER 50S/NEAR 60 ALONG LK SUPERIOR AND MAYBE REACHING 70 DEGREES IN THE FAR SOUTH CENTRAL NEAR MNM. 60S ELSEWHERE...WHICH IS AT LEAST 10 DEGREES BLO NORMAL. NOT MUCH IN WAY OF CHANGES TO REST OF CONSENSUS GRIDS FOR EXTENDED. SLIGHT CHANCE POPS FOR SUNDAY...THOUGH THESE ARE BIASED BY A LATEST GFS WHICH TRENDED MUCH WETTER FOR PARTS OF CWA COMPARED TO PREVIOUS RUNS. ECMWF INDICATES SMALL CHANCES OF INSTABILITY SHRA/TSRA AS ANOTHER STRONGER WAVE OR TWO /CURRENTLY WITHIN THE LARGER TROUGH FM ALASKA TO THE NORTH POLE/ DROPS ACROSS UPPER LAKES. POCKET OF STEEPER MID-LEVEL LAPSE RATES WOULD JUSTIFY AT LEAST A MENTION OF TSRA DURING PEAK HEATING OF SUNDAY AFTN LINGERING INTO SUN EVENING. SIMILAR SETUP FOR MONDAY THOUGH BY THAT TIME BETTER FORCING IS SLIDING EAST AND SOUTH OF LK SUPERIOR REGION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 131 AM EDT TUE AUG 6 2013 ABUNDANT LOW LEVEL MOISTURE WILL REMAIN IN PLACE OVERNIGHT AS WEAK SRLY FLOW CONTINUES. EXPECT IFR/LIFR CIGS AT SAW/CMX TO PERSIST AND ONLY GRADUALLY IMPROVE TODAY AS WRLY FLOW BEHIND A SFC TROUGH BRINGS IN DRIER AIR. CIGS ARE EXPECTED TO ALSO DROP INTO THE IFR RANGE AT IWD PER GUIDANCE AND MDL LOW LEVEL MOISTURE FCST...ALTHOUGH CONFIDENCE IS LOWER GIVEN MAINLY VFR/MVFR UPSTREAM CONDITIONS OVER NW WI. ANY LEFTOVER LOWER CIGS SHOULD LIFT TO MVFR BY MID/LATE MORNING AND TO VFR IN THE AFTERNOON. CIGS/VIS IS EXPECTED TO DROP AGAIN BY EVENING AS SHOWERS MOVE IN AHEAD OF THE NEXT TROUGH. SOME THUNDER MAY ALSO BE POSSIBLE BUT PROB/CONFIDENCE WAS LOW ENOUGH TO LEAVE OUT MENTION. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 548 AM EDT TUE AUG 6 2013 LIGHT WINDS THROUGH MUCH OF TONIGHT THEN WINDS WILL KICK UP AS COLD FRONT CROSSES LK SUPERIOR LATE TONIGHT THROUGH WEDNESDAY MORNING. NW WINDS BEHIND COLD FRONT MAY REACH 20-25 KTS IN GUSTS. SHOWERS AND STORMS LIKELY WITH THE FRONTAL PASSAGE. SHIP REPORTS INDICATE FOG HAS FORMED OVERNIGHT WITH ARRIVAL OF MOIST AIRMASS. EXPECT THE FOG TO CONTINUE UNTIL WEDNESDAY AFTERNOON WHEN DRIER AIR SCOURS OUT THE FOG. WINDS DIMINISH TO LESS THAN 20 KTS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH HIGH PRESSURE OVERHEAD. STRONGER W-NW WINDS POSSIBLE FRIDAY AND FRIDAY NIGHT AS ANOTHER COLD FRONT CROSSES LAKE SUPERIOR FROM NORTH TO SOUTH. GUSTS COULD REACH OVER 25 KTS. WINDS DIMINISH TO LESS THAN 20 KTS FOR REST OF WEEKEND WITH WEAKER PRESSURE GRADIENT BY THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...JLB MARINE...JLA
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
330 AM EDT TUE AUG 6 2013 .SYNOPSIS... ISSUED AT 330 AM EDT TUE AUG 6 2013 IT WILL BE WARMER AND MORE HUMID TODAY WITH A FEW SHOWERS AND THUNDERSTORMS. A COLD FRONT WILL BRING A BETTER CHANCE FOR SHOWERS AND STORMS VERY LATE TONIGHT THROUGH WEDNESDAY. FAIR WEATHER WITH SEASONABLE TEMPERATURES WILL RETURN LATE THIS WEEK. && .SHORT TERM...(TODAY THROUGH THURSDAY AFTERNOON) ISSUED AT 330 AM EDT TUE AUG 6 2013 SOUTHERLY FLOW WILL RESULT IN WARMER AND MORE HUMID WEATHER TODAY WITH SUFFICIENT INSTABILITY FOR SCATTERED SHOWERS AND PERHAPS A FEW STORMS TO DEVELOP THROUGH THE DAY. MAINTAINED ONLY LOW POPS SINCE THERE IS A LACK OF A FOCUSING MECHANISM FOR CONVECTIVE INITIATION TO OCCUR. THE COLD FRONT WILL BRING A MUCH BETTER CHANCE FOR RAIN AND STORMS VERY LATE TONIGHT THROUGH WEDNESDAY. THE BEST CHANCE FOR STRONGER STORMS SHOULD COME WEDNESDAY AFTERNOON BUT THIS WILL BE LARGELY CONTINGENT ON EXTENT OF CLOUD COVER AND INSTABILITY. MOISTURE IS SUFFICIENT BUT SEVERE WX SEEMS UNLIKELY GIVEN LACK OF STRONGER INSTABILITY. DRY WX WITH SEASONABLE TEMPS WILL RETURN BEHIND THAT FRONT WEDNESDAY NIGHT THROUGH THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH MONDAY) ISSUED AT 330 AM EDT TUE AUG 6 2013 IN GENERAL THE LONG TERM PERIOD LOOKS RELATIVELY QUIET WITH TEMPERATURES CONTINUING TO AVERAGE A FEW DEGREES BELOW NORMAL. PERSISTENT TROUGHING OVER EASTERN CANADA LOOKS TO STAY PUT WHICH KEEPS A PREDOMINATELY NORTHWEST FLOW ALOFT IN TACT OVER THE GREAT LAKES REGION. AS THE CLOSED UPPER LOW CURRENTLY NEAR WESTERN HUDSON BAY DROPS SSW... OUR FLOW ALOFT ACTUALLY GOES TEMPORARILY SOUTHWESTERLY ON THURSDAY NIGHT INTO FRIDAY. AN UPPER LEVEL JET STREAK OF 100-120 KTS PROGGED ON THE SOUTHEAST SIDE OF THE UPPER LOW ACROSS LAKE SUPERIOR CREATES RIGHT ENTRANCE REGION DYNAMICS OVER SRN LWR MI. THIS MAY HELP CREATE A RAIN SHOWER POTENTIAL ON THE NORTH SIDE OF THE STALLED FRONTAL BOUNDARY TO OUR SOUTH. FOR THIS REASON WILL CARRY A SLIGHT CHANCE OF RAIN SHOWERS THURSDAY NIGHT AND FRIDAY. THE ONTARIO UPPER LOW LIFTS NORTHEAST INTO QUEBEC OVER THE WEEKEND... SO WOULD NOT EXPECT MUCH OF A COLD AIR INTRUSION FROM THE NORTH. RATHER... THE ZONAL FLOW ALOFT AND RIDGING AT THE SURFACE SHOULD LEAD TO PLEASANT TEMPERATURES/HUMIDITIES OVER THE COMING WEEKEND ALONG WITH DRY WEATHER. WILL REMAIN OPTIMISTIC WITH THE SKY COVER FORECAST... BUT SUSPECT THAT INTERVALS OF THICKER MID/HIGH CLOUDINESS WITHIN THE FAST ZONAL FLOW ALOFT MAY IMPACT THE AREA FROM TIME TO TIME. A SHORTWAVE DROPPING DOWN FROM THE NORTHWEST ON SUNDAY NIGHT AND MONDAY COULD PRODUCE A FEW SHOWERS... BUT TIMING OF THIS FEATURE IS TOUGH THAT FAR OUT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1152 PM EDT MON AUG 5 2013 AS I WAS THINKING AT 6 PM... THE LOW CLOUDS WILL COME IN FROM WISCONSIN OVERNIGHT BRINGING IFR CIGS ACROSS THE AREA THAT WILL NOT LIFT UNTIL LATE MORNING OR EARLY AFTERNOON TO TUESDAY. THE REAL QUESTION IS WILL THERE BE SHOWERS OVERNIGHT... ENOUGH TO LOWER THE VISIBILITIES THAT IS? GIVEN THE WATER VAPOR IMAGE LOOPS SHOWING SO MUCH MID-LEVEL DRY AIR.... AND SEEING RAP AND NAM 00Z MODEL RUN SOUNDINGS SHOWING SO MUCH DRY AIR ABOVE 700 MB THROUGH THE NIGHT... EVEN SOUTH OF INTERSTATE 94... IT IS HARD TO IMAGE ANYTHING TO SIGNIFICANT DEVELOPING. WHAT EVER DOES HAPPEN.. ARE MORE LIKELY SOUTH OF INTERSTATE 96... SINCE THAT AREA IS CLOSER THE TO BETTER MOISTURE AND BETTER LOW LEVEL INFLOW. I FEATURES SHOWERS OVER THE SOUTHERN TAF SITES ONLY ON THE 06Z TAF SET. && .MARINE... ISSUED AT 330 AM EDT TUE AUG 6 2013 WAVE HEIGHTS MAINLY IN THE 1 TO 3 FOOT RANGE ARE EXPECTED TODAY IN WARM AIR ADVECTION SOUTHERLY FLOW. WINDS WILL STRENGTHEN A BIT IN ADVANCE OF THE COLD FRONT TONIGHT THAT SHOULD BUILD WAVES UP TO AROUND 2 TO 4 FEET NORTH OF MUSKEGON. AFTER FROPA WEDNESDAY WAVES WILL INCREASE IN NORTHERLY FLOW COOL AIR ADVECTION AND SMALL CRAFT ADVISORIES AND BEACH HAZARDS STATEMENTS MAY BE NEEDED. && .HYDROLOGY... ISSUED AT 330 AM EDT TUE AUG 6 2013 ANY RAINFALL TODAY WILL BE RATHER LIGHT BUT SOME STEADIER RAIN AND STORMS SHOULD ARRIVE LATE TONIGHT THROUGH WEDNESDAY WITH BASIN AVG QPF AMOUNTS OF AT LEAST A QUARTER TO HALF INCH POSSIBLE WITH LOCALLY HIGHER AMOUNTS. HOWEVER GIVEN ANTECEDENT LOW RIVER FLOWS WE DO NOT EXPECT TO HAVE ANY MAJOR HYDRO ISSUES. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...LAURENS SHORT TERM...LAURENS LONG TERM...MEADE AVIATION...WDM HYDROLOGY...LAURENS MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
204 PM CDT Tue Aug 6 2013 .SHORT TERM...(Today and Tonight) ISSUED AT 349 AM CDT TUE AUG 6 2013 Very serious flooding situation unfolding across the area this morning. A band of thunderstorms producing heavy rainfall has set of up from roughly the Lake of the Ozark area southeastward through portions of Laclede/Pulaski counties and into the northern half of Texas county. Radar estimates vary a bit, but given rainfall rate observations from the past several nights, as much as 8" of rain has fallen in spots. This band of rainfall will be the primary concern this morning. A decaying line of storms entering from the west has produced a large swath of moderate rain. Rainfall amounts are more modest with a general half inch to one inch of rainfall over a longer duration, with embedded pockets of up to two inches of rainfall. The biggest concern for this morning is that band of torrential rainfall from central Missouri into the eastern Ozarks and the extreme flooding risk. Looking at the HRRR and other short range models, this band of rainfall will not move much through day break. With hourly rainfall rates between one and two inches, a bad situation will only get worse. Rain will gradually end from west to east during the mid to late morning hours. Like yesterday some clearing is expected and a warm and humid afternoon is in store. Instability will quickly increase during the afternoon and additional isolated to widely scattered thunderstorms will be possible across the entire area. There will be a limited risk for severe with this activity, with hail to the size of quarters and localized damaging wind gusts. This activity will likely persist into the evening in a widely scattered fashion. Then attention will turn to a complex of thunderstorms develop to our north/northwest. This will approach the area from the northwest overnight tonight. In addition, much like the past few nights, will need to watch for low level jet interaction with any lingering boundaries. This activity will be possible just about anywhere across the outlook area. The air mass remains extremely moist, and flash flooding will once again be a major concern. .LONG TERM...(Wednesday through Monday) ISSUED AT 349 AM CDT TUE AUG 6 2013 The forecast for midweek into early next week remains complex and concerning. Northwest flow aloft will keep our region in the atmospheric battleground, and multiple rounds of showers and thunderstorms remain possible. There is moderate confidence in another round of heavy rainfall Wednesday night into Thursday. As a result, the Flash Flood Watch will be extended into Thursday morning. The medium range models do offer a glimmer of hope for the weekend and the pattern briefly deamplifies and the atmospheric battleground shifts just to the west. Tough to get to confident in this solution given the persistent upper level pattern that has been in place. One can certainly hope, though. The bottom line is that more rounds of rain will be possible. Temperatures will be at or below average (depending on cloud coverage and rain). && .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) ISSUED AT 156 PM CDT TUE AUG 6 2013 For the KSGF/KJLN/KBBG tafs...a front over IA/NEB will drop south into the region tonight. Scattered showers are ongoing near KJLN and KSGF and will watch trends, but better chances for showers and thunderstorms would appear to be tonight toward 06Z. Will keep tafs mainly in the vfr cat but no doubt there will be mvfr or ifr possibilities in heavier rain showers. There is potential for a more prolonged period of lower clouds late in the taf period near and just north of the sfc boundary, but there is not a lot of confidence in the boundary position by that time. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH through Thursday morning FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH through Thursday morning FOR KSZ073-097-101. && $$ SHORT TERM...Gagan LONG TERM...Gagan AVIATION...DSA
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1221 PM CDT Tue Aug 6 2013 .SHORT TERM...(Today through Wednesday) Issued at 307 AM CDT TUE AUG 6 2013 Large MCS continues to interact with synoptic boundary arcing from west central Missouri southeast through the Ozarks. Based on 00Z soundings, convective outflow boundary should be more than sufficient forcing to easily overturn the entire warm sector air mass as well as the region through about 50 miles north. This sharp delineation has been well handled by the HRRR and NSSL WRF runs, and takes the northern extent of the thunderstorms to roughly the MO river from Kansas City metro eastward. Thunderstorm cloud tops have continued to be in the -75 to -80C range with prolific lightning counts. This would suggest that despite the rich boundary layer moisture, rainfall efficiency is not as high as it could be. Nonetheless, 1-2"/hr rates are almost certain in the heavier cells, and there may be some tendency for slower storm movement/propagation where the outflow boundary becomes W-E oriented along the nrn edge of the convection. 80-100% POPs generally carried along and south of the MO river (slightly more NW- SE oriented) with a rapid decrease further north. Given the short term setup, while we definitely need the rain around Kansas City, mesoscale influences suggest this is also the most likely region for flooding through the next 3-4 hours if conceptual evolution materializes. Elsewhere, areas of light fog are expected along the periphery of the MCS cloud shield where subsidence will work in concert with more efficient boundary layer cooling and high antecedent moisture content. MCS (if not MCC designated) should gradually exit the CWA to the southeast this morning as the low level jet veers, with convective debris cirrus lingering through the morning. Like yesterday, most aggressive warming will occur during the afternoon hours. Given the very stagnant air mass in place, will introduce haze into the forecast, coupling with otherwise very sultry conditions expected as dewpoints climb into the middle 70s. Other than a rogue pulse thunderstorm or two during the afternoon along a residual boundary, expect the region to be fairly quiet between 15-00Z. By evening, a disturbance currently producing active deep convection over SW South Dakota will reach far NW MO. Despite model variances, there appears to be an overall suggestion that at least scattered thunderstorms will develop and/or move into NW MO early this evening, possibly growing upscale overnight as this activity moves southeast. SPC highlights the area with a broad slight risk overnight for wind damage potential. Given some modest increase/linearity to the 700-500mb flow, certainly cannot rule out some storm organization. This system should also clear the region by late morning, leaving a hazy, warm and very humid day again on Wednesday. .LONG TERM...(Thursday through Monday) Issued at 307 AM CDT TUE AUG 6 2013 Remnant energy lifting northward out of the Baja California Peninsula and into the Central Plains on Thursday will provide a reasonable chance for fairly widespread rains across the lower Missouri river valley. By Thursday morning ECMWF/GFS both suggest increased troughing over the central Rockies, allowing for southwest flow to move into the Plains. Strong warm advection ahead of this wave of energy may be strong enough to force baroclinic zone which has been stuck to the south of the CWA northward during the day. As this upper wave ejects eastward Thursday night into Friday, fairly pronounced mid-level lift provided by PVA and an enhanced upper jet streak should keep PoPs high overnight as several rounds of showers and thunderstorms will be possible. High pressure is expected to sink southward into the central US on Friday, leading to dry conditions for the first half of the weekend. Increased troughing off the West Coast combined with fairly progressive zonal flow over the Nation`s midsection will lead to lower forecast confidence by early next week. Several waves of energy may again eject eastward out of this trough, but timing of these features remains too problematic to target any one time period for higher PoPs. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1216 PM CDT TUE AUG 6 2013 Challenging precipitation forecast for the next 24 hours. Cannot rule out a brief shower this afternoon at terminals, but with no expected reduction in flight category have left out of TAF at this time. Otherwise anticipate overnight showers/thunderstorms in the vicinity or over terminals during the 05-13Z window, but specific impacts and timing still highly uncertain. Wind shift expected Wednesday morning following a cold frontal passage to prevailing northeasterly winds. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Bookbinder LONG TERM...Dux AVIATION...Blair
AREA FORECAST DISCUSSION...UPDATED
NWS SPRINGFIELD MO
640 AM CDT Tue Aug 6 2013 ...SERIOUS FLASH FLOODING SITUATION CONTINUES ACROSS PORTIONS OF TEXAS AND PULASKI COUNTIES... .MESOSCALE DISCUSSION... Issued AT 639 AM CDT TUE AUG 6 2013 Low level jet continues to veer and moisture transport remains focused from central Missouri through the eastern Ozarks and into south central Missouri. Some good news is that there has been a weakening trend to this activity, especially in the areas hardest hit in Pulaski and Texas counties. Could still see an additional half inch of rain or so, but the heaviest rain rates have come to an end. Latest radar trends suggest an orderly west to east end to the precipitation and will update timing shortly. Forecast for the afternoon looks good at this point. Should see at least partial clearing with a warm/humid afternoon on tap. Isolated to widely scattered pulse thunderstorm redevelopment remains plausible this afternoon. && .SHORT TERM...(Today and Tonight) ISSUED AT 349 AM CDT TUE AUG 6 2013 Very serious flooding situation unfolding across the area this morning. A band of thunderstorms producing heavy rainfall has set of up from roughly the Lake of the Ozark area southeastward through portions of Laclede/Pulaski counties and into the northern half of Texas county. Radar estimates vary a bit, but given rainfall rate observations from the past several nights, as much as 8" of rain has fallen in spots. This band of rainfall will be the primary concern this morning. A decaying line of storms entering from the west has produced a large swath of moderate rain. Rainfall amounts are more modest with a general half inch to one inch of rainfall over a longer duration, with embedded pockets of up to two inches of rainfall. The biggest concern for this morning is that band of torrential rainfall from central Missouri into the eastern Ozarks and the extreme flooding risk. Looking at the HRRR and other short range models, this band of rainfall will not move much through day break. With hourly rainfall rates between one and two inches, a bad situation will only get worse. Rain will gradually end from west to east during the mid to late morning hours. Like yesterday some clearing is expected and a warm and humid afternoon is in store. Instability will quickly increase during the afternoon and additional isolated to widely scattered thunderstorms will be possible across the entire area. There will be a limited risk for severe with this activity, with hail to the size of quarters and localized damaging wind gusts. This activity will likely persist into the evening in a widely scattered fashion. Then attention will turn to a complex of thunderstorms develop to our north/northwest. This will approach the area from the northwest overnight tonight. In addition, much like the past few nights, will need to watch for low level jet interaction with any lingering boundaries. This activity will be possible just about anywhere across the outlook area. The airmass remains extremely moist, and flash flooding will once again be a major concern. .LONG TERM...(Wednesday through Monday) ISSUED AT 349 AM CDT TUE AUG 6 2013 The forecast for midweek into early next week remains complex and concerning. Northwest flow aloft will keep our region in the atmospheric battleground, and multiple rounds of showers and thunderstorms remain possible. There is moderate confidence in another round of heavy rainfall Wednesday night into Thursday. As a result, the Flash Flood Watch will be extended into Thursday morning. The medium range models do offer a glimmer of hope for the weekend and the pattern briefly deamplifies and the atmospheric battleground shifts just to the west. Tough to get to confident in this solution given the persistent upper level pattern that has been in place. One can certainly hope, though. The bottom line is that more rounds of rain will be possible. Temperatures will be at or below average (depending on cloud coverage and rain). && .AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning) ISSUED AT 639 AM CDT TUE AUG 6 2013 Rainfall is exiting from west to east out of the JLN/SGF/BBG aerodromes. VFR conditions are expected today with gradual clearing of mid/high deck expected. Will need to monitor for isolated to widely scattered thunderstorm development during the mid/late afternoon hours. Confidence is not high enough to include at this point. Will also be monitoring for another round of thunderstorms tonight. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH through Thursday morning FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH through Thursday morning FOR KSZ073-097-101. && $$ MESOSCALE...Gagan SHORT TERM...Gagan LONG TERM...Gagan AVIATION...Gagan
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
631 AM CDT TUE AUG 6 2013 .SHORT TERM...(Today through Wednesday) Issued at 307 AM CDT TUE AUG 6 2013 Large MCS continues to interact with synoptic boundary arcing from west central Missouri southeast through the Ozarks. Based on 00Z soundings, convective outflow boundary should be more than sufficient forcing to easily overturn the entire warm sector air mass as well as the region through about 50 miles north. This sharp delineation has been well handled by the HRRR and NSSL WRF runs, and takes the northern extent of the thunderstorms to roughly the MO river from Kansas City metro eastward. Thunderstorm cloud tops have continued to be in the -75 to -80C range with prolific lightning counts. This would suggest that despite the rich boundary layer moisture, rainfall efficiency is not as high as it could be. Nonetheless, 1-2"/hr rates are almost certain in the heavier cells, and there may be some tendency for slower storm movement/propagation where the outflow boundary becomes W-E oriented along the nrn edge of the convection. 80-100% POPs generally carried along and south of the MO river (slightly more NW- SE oriented) with a rapid decrease further north. Given the short term setup, while we definitely need the rain around Kansas City, mesoscale influences suggest this is also the most likely region for flooding through the next 3-4 hours if conceptual evolution materializes. Elsewhere, areas of light fog are expected along the periphery of the MCS cloud shield where subsidence will work in concert with more efficient boundary layer cooling and high antecedent moisture content. MCS (if not MCC designated) should gradually exit the CWA to the southeast this morning as the low level jet veers, with convective debris cirrus lingering through the morning. Like yesterday, most aggressive warming will occur during the afternoon hours. Given the very stagnant air mass in place, will introduce haze into the forecast, coupling with otherwise very sultry conditions expected as dewpoints climb into the middle 70s. Other than a rogue pulse thunderstorm or two during the afternoon along a residual boundary, expect the region to be fairly quiet between 15-00Z. By evening, a disturbance currently producing active deep convection over SW South Dakota will reach far NW MO. Despite model variances, there appears to be an overall suggestion that at least scattered thunderstorms will develop and/or move into NW MO early this evening, possibly growing upscale overnight as this activity moves southeast. SPC highlights the area with a broad slight risk overnight for wind damage potential. Given some modest increase/linearity to the 700-500mb flow, certainly cannot rule out some storm organization. This system should also clear the region by late morning, leaving a hazy, warm and very humid day again on Wednesday. .LONG TERM...(Thursday through Monday) Issued at 307 AM CDT TUE AUG 6 2013 Remnant energy lifting northward out of the Baja California Peninsula and into the Central Plains on Thursday will provide a reasonable chance for fairly widespread rains across the lower Missouri river valley. By Thursday morning ECMWF/GFS both suggest increased troughing over the central Rockies, allowing for southwest flow to move into the Plains. Strong warm advection ahead of this wave of energy may be strong enough to force baroclinic zone which has been stuck to the south of the CWA northward during the day. As this upper wave ejects eastward Thursday night into Friday, fairly pronounced mid-level lift provided by PVA and an enhanced upper jet streak should keep PoPs high overnight as several rounds of showers and thunderstorms will be possible. High pressure is expected to sink southward into the central US on Friday, leading to dry conditions for the first half of the weekend. Increased troughing off the West Coast combined with fairly progressive zonal flow over the Nation`s midsection will lead to lower forecast confidence by early next week. Several waves of energy may again eject eastward out of this trough, but timing of these features remains too problematic to target any one time period for higher PoPs. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning) Issued at 628 AM CDT TUE AUG 6 2013 Convective complex has exited east of the STJ-MCI-MKC terminals early this morning, however foggy conditions persist to the north and east with IFR/local LIFR expected to improve aft 13Z. For today, high clouds should burn off by mid morning. However, with stagnant airmass in place, haze aloft will continue to become an increase concern. VFR conditions to continue otherwise with lgt/vrb winds becoming southeast at 8-10 knots. Models very consistent with developing a complex of strong to severe thunderstorms across IA/NE later this afternoon (possibly an extension of ongoing activity near Omaha), and pushing it quickly southward this evening. Best guess is 03-05Z across the terminals, with strong wind gusts and torrential rainfall potentially impacting late evening arrival rates. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Bookbinder LONG TERM...Dux AVIATION...Bookbinder
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
349 AM CDT Tue Aug 6 2013 ...SERIOUS FLASH FLOODING SITUATION UNFOLDING ACROSS PORTIONS OF TEXAS AND PULASKI COUNTIES... .SHORT TERM...(Today and Tonight) ISSUED AT 349 AM CDT TUE AUG 6 2013 Very serious flooding situation unfolding across the area this morning. A band of thunderstorms producing heavy rainfall has set of up from roughly the Lake of the Ozark area southeastward through portions of Laclede/Pulaski counties and into the northern half of Texas county. Radar estimates vary a bit, but given rainfall rate observations from the past several nights, as much as 8" of rain has fallen in spots. This band of rainfall will be the primary concern this morning. A decaying line of storms entering from the west has produced a large swath of moderate rain. Rainfall amounts are more modest with a general half inch to one inch of rainfall over a longer duration, with embedded pockets of up to two inches of rainfall. The biggest concern for this morning is that band of torrential rainfall from central Missouri into the eastern Ozarks and the extreme flooding risk. Looking at the HRRR and other short range models, this band of rainfall will not move much through day break. With hourly rainfall rates between one and two inches, a bad situation will only get worse. Rain will gradually end from west to east during the mid to late morning hours. Like yesterday some clearing is expected and a warm and humid afternoon is in store. Instability will quickly increase during the afternoon and additional isolated to widely scattered thunderstorms will be possible across the entire area. There will be a limited risk for severe with this activity, with hail to the size of quarters and localized damaging wind gusts. This activity will likely persist into the evening in a widely scattered fashion. Then attention will turn to a complex of thunderstorms develop to our north/northwest. This will approach the area from the northwest overnight tonight. In addition, much like the past few nights, will need to watch for low level jet interaction with any lingering boundaries. This activity will be possible just about anywhere across the outlook area. The airmass remains extremely moist, and flash flooding will once again be a major concern. .LONG TERM...(Wednesday through Monday) ISSUED AT 349 AM CDT TUE AUG 6 2013 The forecast for midweek into early next week remains complex and concerning. Northwest flow aloft will keep our region in the atmospheric battleground, and multiple rounds of showers and thunderstorms remain possible. There is moderate confidence in another round of heavy rainfall Wednesday night into Thursday. As a result, the Flash Flood Watch will be extended into Thursday morning. The medium range models do offer a glimmer of hope for the weekend and the pattern briefly deamplifies and the atmospheric battleground shifts just to the west. Tough to get to confident in this solution given the persistent upper level pattern that has been in place. One can certainly hope, though. The bottom line is that more rounds of rain will be possible. Temperatures will be at or below average (depending on cloud coverage and rain). && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) ISSUED AT 815 PM CDT MON AUG 5 2013 Pilots can expect additional storms to move into the region overnight bringing areas of MVFR conditions and the potential of strong thunderstorm winds. IFR conditions will be possible in the heavier rainfall. Improving flight conditions will return by Tuesday afternoon. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH through Thursday morning FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH through Thursday morning FOR KSZ073-097-101. && $$ SHORT TERM...Gagan LONG TERM...Gagan AVIATION...Foster
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
311 AM CDT Tue Aug 6 2013 .SHORT TERM...(Today through Wednesday) Issued at 307 AM CDT TUE AUG 6 2013 Large MCS continues to interact with synoptic boundary arcing from west central Missouri southeast through the Ozarks. Based on 00Z soundings, convective outflow boundary should be more than sufficient forcing to easily overturn the entire warm sector air mass as well as the region through about 50 miles north. This sharp delineation has been well handled by the HRRR and NSSL WRF runs, and takes the northern extent of the thunderstorms to roughly the MO river from Kansas City metro eastward. Thunderstorm cloud tops have continued to be in the -75 to -80C range with prolific lightning counts. This would suggest that despite the rich boundary layer moisture, rainfall efficiency is not as high as it could be. Nonetheless, 1-2"/hr rates are almost certain in the heavier cells, and there may be some tendency for slower storm movement/propagation where the outflow boundary becomes W-E oriented along the nrn edge of the convection. 80-100% POPs generally carried along and south of the MO river (slightly more NW- SE oriented) with a rapid decrease further north. Given the short term setup, while we definitely need the rain around Kansas City, mesoscale influences suggest this is also the most likely region for flooding through the next 3-4 hours if conceptual evolution materializes. Elsewhere, areas of light fog are expected along the periphery of the MCS cloud shield where subsidence will work in concert with more efficient boundary layer cooling and high antecedent moisture content. MCS (if not MCC designated) should gradually exit the CWA to the southeast this morning as the low level jet veers, with convective debris cirrus lingering through the morning. Like yesterday, most aggressive warming will occur during the afternoon hours. Given the very stagnant air mass in place, will introduce haze into the forecast, coupling with otherwise very sultry conditions expected as dewpoints climb into the middle 70s. Other than a rogue pulse thunderstorm or two during the afternoon along a residual boundary, expect the region to be fairly quiet between 15-00Z. By evening, a disturbance currently producing active deep convection over SW South Dakota will reach far NW MO. Despite model variances, there appears to be an overall suggestion that at least scattered thunderstorms will develop and/or move into NW MO early this evening, possibly growing upscale overnight as this activity moves southeast. SPC highlights the area with a broad slight risk overnight for wind damage potential. Given some modest increase/linearity to the 700-500mb flow, certainly cannot rule out some storm organization. This system should also clear the region by late morning, leaving a hazy, warm and very humid day again on Wednesday. .LONG TERM...(Thursday through Monday) Issued at 307 AM CDT TUE AUG 6 2013 Remnant energy lifting northward out of the Baja California Peninsula and into the Central Plains on Thursday will provide a reasonable chance for fairly widespread rains across the lower Missouri river valley. By Thursday morning ECMWF/GFS both suggest increased troughing over the central Rockies, allowing for southwest flow to move into the Plains. Strong warm advection ahead of this wave of energy may be strong enough to force baroclinic zone which has been stuck to the south of the CWA northward during the day. As this upper wave ejects eastward Thursday night into Friday, fairly pronounced mid-level lift provided by PVA and an enhanced upper jet streak should keep PoPs high overnight as several rounds of showers and thunderstorms will be possible. High pressure is expected to sink southward into the central US on Friday, leading to dry conditions for the first half of the weekend. Increased troughing off the West Coast combined with fairly progressive zonal flow over the Nation`s midsection will lead to lower forecast confidence by early next week. Several waves of energy may again eject eastward out of this trough, but timing of these features remains too problematic to target any one time period for higher PoPs. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1045 PM CDT MON AUG 5 2013 Cluster of storms across southeast Kansas will continue to move east southeast through the overnight hours. Bulk of the activity should pass south of Kansas City, so only include VCTS in the KC terminals for the early morning hours. Otherwise, thoughts are that ceilings will stay in the VFR range unless a thunderstorm directly effects a terminal, which will have to be handled with an amendment. Otherwise, expect winds to back around to the south by the early afternoon hours. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Bookbinder LONG TERM...Dux AVIATION...Cutter
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1132 PM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 844 PM CDT MON AUG 5 2013 THUNDERSTORMS HAVE STAYED SOUTHWEST OF THE CWA THIS EVENING... THOUGH DO EXPECT ADDITIONAL STORMS TO DEVELOP FROM EASTERN KANSAS INTO SOUTHEAST MISSOURI OVERNIGHT. THESE STORMS WILL DEVELOP IN A BAND OF LOW LEVEL MOISTURE CONVERGENCE ON THE BROAD NOSE OF A LOW LEVEL JET. LATEST RUNS OF THE HRRR SUGGESTS THAT NORTHERN AND EASTERN EDGE OF THUNDERSTORMS WILL MOVE INTO CENTRAL AND SOUTHEAST MISSOURI TOWARD SUNRISE...WITH BEST COVERAGE ACROSS SOUTHEAST MISSOURI INTO SOUTHERN ILLINOIS BETWEEN 10-15Z. HAVE ADJUSTED RAIN CHANCES TO GO ALONG WITH THIS IDEA. OTHERWISE...GOING FORECAST LOOKS GOOD AND ONLY MADE MINOR TWEAKS TO TEMPERATURE AND CLOUD COVER TO MATCH WITH GOING TRENDS. BRITT && .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 333 PM CDT MON AUG 5 2013 FRONTAL BOUNDARY TO THE SOUTH WILL SLOWLY RETREAT AND MOVE NORTHWARD OVERNIGHT TONIGHT. ISOLATED TO SCATERRED CONVECTION HAS DEVELOPED ALONG IT OVER THE PAST COUPLE OF HOURS ACROSS PORTIONS OF SW MISSOURI. THINKING THAT THIS CONVECTION SHOULD WEAKEN AND DIE OUT THIS EVENING WITH LOSS OF DAYLIGHT HEATING. TIED HIGHEST POPS TONIGHT TO PORTIONS OF SOUTH CENTRAL AND SOUTHEAST MISSOURI WHICH WILL BE IN CLOSER PROXIMITY TO AFOREMENTIONED FRONT. DID LOWER POPS A BIT FROM PREVIOUS FORECAST AS CONVERGENCE ALONG FRONT IS RATHER WEAK AND LOW LEVEL FORCING IS PROGGED TO BE NOT NEARLY AS STRONG OR FOCUSED TONIGHT AS PREVIOUS FEW NIGHTS. ALONG AND NORTH OF BOUNDARY LOW STRATUS...AND POSSIBLY FOG...TO AFFECT MUCH OF THE REGION WHICH WILL HELP KEEP LOW TEMPERATURES UP IN THE UPPER 60S TO LOW 70S. BOOSTED LOWS A DEGREE OR TWO ABOVE WARMER MAV GUIDANCE DUE TO EXPECTED LOW CLOUD COVER OVERNIGHT TONIGHT. GOSSELIN .LONG TERM...(TUESDAY THROUGH NEXT MONDAY) ISSUED AT 333 PM CDT MON AUG 5 2013 WITH WAA/ISENTROPIC ASCENT STILL OVER OUR AREA TUESDAY MORNING COUPLED WITH A FEW VORTICITY MAXIMA RIDING OVER A RIDGE TO OUR SW... THE SHOWERS AND THUNDERSTORMS THAT DEVELOPS OVERNIGHT SHOULD CONTINUE TO PROPAGATE INTO OUR S COUNTIES DURING THE MORNING...WITH LIKELY POPS AS FAR N AS A COLUMBIA TO SPARTA LINE. ELSEWHERE...WILL MAINTAIN CHANCE OF POPS THROUGHOUT THE DAY...AS TONGUE OF WAA PERSISTS OVER OUR AREA COUPLED WITH A FEW WEAK SHORTWAVES WITHIN THE GENERAL FLOW. BY TUESDAY NIGHT...EXPECTING AN UPTICK IN CONVECTIVE ACTIVITY OVER THE N 2/3 OF THE CWA AS WAA INTENSIFIES EVEN MORE AHEAD OF APPRROACHING SHORTWAVE AND ASSOCIATED COLD FRONT. ON WEDNESDAY THE COLD FRONT IS EXPECTED TO SWEEP ACROSS THE AREA. SOME MODELS SUGGEST THAT THE IMPACTS OF THE OVERNIGHT CONVECTION MAY INHIBIT ADDITIONAL DEVELOPMENT OF CONVECTION ALONG THE FRONT DURING THE DAY. HOWEVER...HAVE NOT MADE ANY MAJOR CHANGES TO CURRENT POPS ATTM. 12Z GFS REBOUNDS THE FRONTAL BOUNDARY AS A WARM FRONT ACROSS OUR AREA LATE WEDNESDAY INTO THURSDAY MORNING IN RESPONSE TO A DEEPENING SHORTWAVE TO THE WEST...WHILE MANY OF THE OTHER 12Z SOLUTIONS ALLOW THE FRONTAL BOUNDARY TO SETTLE INTO N ARKANSAS. WHILE THIS WILL IMPACT TEMPS...ALL SOLUTIONS POINT TO ACTIVE BAROCLINIC ZONE REMAINING OVER S MISSOURI AND S ILLINOIS. THEREFORE HAVE MAINTAINED LIKELY POPS OVER SOUTHERN SECTIONS OF THE CWA THROUGH THURSDAY NIGHT WITH A CHANCE OF POPS ACROSS THE NORTH. WITH TIME...MEDIUM RANGE SOLUTIONS DO INIDICATE THAT THE BAROCLINIC ZONE WILL SAG SOUTH...WHICH IN TURN SHOULD ALLOW A SLOW DECREASE IN POPS IN THE FRIDAY-SATURDAY TIME FRAME. HOWEVER...IT APPEARS THAT TSRA THREAT WILL BE RETURNING BY THE START OF NEXT WEEK AS LOW LEVEL WARM ADVECTION REDEVELOPS ACROSS THE REGION. HUSTEDDE/TRUETT && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1105 PM CDT MON AUG 5 2013 RATHER COMPLEX WX SITUATION WITH ONE AREA OF MVFR CIGS MOVING SWD OVER PORTIONS OF CENTRAL IL AND NERN MO...ANOTHER AREA OF IFR CIGS MOVING NWD AND NEWD CURRENTLY ACROSS SRN AND SWRN IL AS WELL AS SERN AND E CENTRAL MO. COMPLICATING MATTERS IS AREA OF TSRA CURRENTLY OVER KS MOVING EWD WITH CI SHIELD OVER THE REGION. UIN MAY COOL ENUF THRU THE NIGHT FOR AT LEAST MVFR FG TO DEVELOP ALONG WITH AREA OF MVFR CIGS MOVING BACK NWD AS THE WRMFNT LIFTS NWD TONIGHT. COU SHUD REMAIN VFR THRU MUCH OF THE NIGHT AS THICKER CI CONTINUES TO MOVE OVER THE AREA AS TSRA COMPLEX APPROACHES. BELIEVE THESE TSRA WILL REMAIN JUST S OF COU TERMINAL...BUT MAY STILL SEE SPRINKLES OR A BRIEF PERIOD OF -RA. THESE TSRA ARE ALSO EXPECTED TO REMAIN JUST S OF SUS/CPS TUES MORNING...BUT CAN NOT RULE OUT DEVELOPMENT ALONG THE NRN FRINGES OF THE COMPLEX. UNTIL THESE TSRA ARRIVE...BELIEVE IFR CIGS WILL REMAIN IN PLACE AS THE WRMFNT SHUD REMAIN JUST S OF THE TERMINALS. THESE CIGS SHUD BE SLOW TO RISE TUES. KEPT MENTION OF VCSH TUES AFTERNOON WITH REDEVELOPMENT EXPECTED ALONG THE FNT. BETTER CHANCES EXIST AT UIN TUES NIGHT NEAR THE END OF THE TAF PERIOD AS A CDFNT MOVES S INTO THE REGION. WILL LEAVE OUT FOR NOW. SPECIFICS FOR KSTL...TSRA OVER KS WILL MOVE ESE TOWARD ERN MO OVERNIGHT. EXPECT TSRA TO REMAIN S OF TERMINAL...BUT CAN NOT RULE OUT DEVELOPMENT ALONG THE NRN FRINGES OF THIS COMPLEX. UNTIL THEN...BELIEVE IFR CIGS WILL REMAIN IN PLACE AS THE WRMFNT APPROACHES THE AREA. LOW CIGS SHUD BE SLOW TO LIFT TUES MORNING. KEPT MENTION OF VCSH TUES AFTERNOON WHERE REDEVELOPMENT OF TSRA ALONG THE FNT IS EXPECTED. && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
215 PM MDT TUE AUG 6 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY... NORTHWESTERLY FLOW ALOFT CONTINUES THROUGH THURSDAY. WEATHER FOR THE NORTHERN CONUS IS DOMINATED BY A LARGE UPPER LOW OVER NORTH CENTRAL CANADA. AS THIS LOW SPINS AND MAKES SLOW PROGRESS EASTWARD OVER THE NEXT FEW DAYS...PERIODIC SHORTWAVE DISTURBANCES IN THE FLOW AROUND THE LOW PASS OVER THE MONTANA AREA. THESE DISTURBANCES BRING SUPPORT FOR SHOWERS AND THUNDERSTORMS. SHOWER ACTIVITY MOSTLY OCCURS IN THE AFTERNOONS AS DAYTIME HEATING OF THE RELATIVELY MOIST BOUNDARY LAYER CREATES CONVECTIVE INSTABILITY WHICH COMBINES WITH MODEST UPPER LEVEL FORCING FROM SHORTWAVE ACTIVITY. CURRENTLY..SOME NON-SEVERE SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED WITH THE PASSAGE OF A SHORTWAVE TONIGHT WITH A WEAKER ONE DUE LATE WEDNESDAY. THURSDAY AFTERNOON HAS A LOWER CHANCE OF CONVECTIVE ACTIVITY AS THE GFS AND NAM HAVE THE CANADA LOW BY THAT TIME FAR ENOUGH EASTWARD TO ALLOW SOME BUILDING OF HIGH PRESSURE OVER THE ROCKIES. FOR TONIGHT...THE HRRR MODEL SEEMS TO HAVE A REASONABLE HANDLE ON DEVELOPMENT FOLLOWING THE LOWER RESOLUTION MODELS IN PRODUCING AN AREA OF SHOWERS OVER THE NORTHEAST 2/3RDS OF THE CWA...WHICH DIES OUT AROUND 9PM. STRENGTH OF CONVECTION IS EXPECTED TO BE MODEST...THOUGH SOME THUNDERSTORMS WILL OCCUR...AS BOUNDARY LAYER INSTABILITY IS WEAK WITH LESS THAN 1000 J/KG OF MLCAPE AT MOST...WHICH RAPIDLY DECLINES AFTER 6PM AS THE SURFACE COOLS DIURNALLY. TEMPERATURES ARE EXPECTED TO BE MILD THROUGH THURSDAY DUE TO CLOUD COVER AND LIMITED THICKNESSES IN THE SOUTHWEST QUADRANT OF THE CANADA LOW. THERE IS ALSO A LACK OF WELL-DEFINED SURFACE FEATURES THAT WOULD LEAD TO STRONG WINDS. CURRENT SURFACE LOW EXITING THE DAKOTAS HAS KEPT NORTHWESTERLY SURFACE WINDS IN PLACE. THESE WINDS WILL BECOME LIGHTER TONIGHT AND WEDNESDAY...AND THEN MORE EASTERLY ON THURSDAY AS A THERMAL SURFACE LOW DEVELOPS OVER THE ROCKIES. MARTIN .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... THE EXTENDED PERIOD BEGINS THURSDAY NIGHT WITH HIGH PRESSURE AND A HEAT DOME OVER THE SOUTHWESTERN DESERT...WITH AN UPPER RIDGE EXTENDING NORTH ALL THE WAY UP INTO THE PACIFIC NORTHWEST. THE CLOSED UPPER LEVEL CANADIAN LOW WILL BE RETREATING EAST INTO ONTARIO...LEAVING BEHIND IN ITS WAKE ANOTHER...BUT WEAKER...TROUGH OVER THE PRAIRIE PROVINCES. THIS PATTERN WILL MAINTAIN OUR NORTHWEST FLOW ALOFT AND THE STATIONARY BOUNDARY ACROSS NORTHEAST MONTANA THROUGH MOST OF THE WEEKEND. THIS FLOW WILL NOT BE CLEAN...RESULTING IN OCCASIONAL SHORT PERIODS OF RAIN SHOWERS OR THUNDERSTORMS. THEN AS THE RIDGE ATTEMPTS TO MOVE EAST A COUPLE OF LOWS IN THE PAC-NW AND WESTERN CANADA SEND MOISTURE OVER THE DIVIDE. THIS MOISTURE AND MORE DISTURBANCES WILL TEND TO KNOCK DOWN THE RIDGE AND CONTINUE TO PRODUCE RAIN SHOWERS AND THUNDERSTORMS INTO NEXT WEEK. GUIDANCE SUGGEST WARMING TO ABOVE NORMAL...BUT THE PATTERN MIGHT RESIST THAT GUIDANCE TREND. FEW SIGNIFICANT CHANGES WERE NEEDED. SCT PREVIOUS DISCUSSION... FORECAST THROUGH THE END OF THE WEEK WILL BE INFLUENCED BY THE LINGERING EFFECTS OF THE STRONG HUDSON BAY LOW. UPPER RIDGE BUILDING NORTH ALONG THE ROCKIES WILL BE THE MAIN PLAYER FOR EARLY NEXT WEEK. MODELS SLIPPING OUT OF AGREEMENT REGARDING THE HUDSON BAY LOW AFTER IT DROPS INTO CENTRAL MANITOBA. ECMWF MOVES IT EAST FASTER THEN THE GFS BUT LEAVES A PORTION BEHIND IN SASKATCHEWAN THURSDAY NIGHT. EC CURRENTLY NOT INDICATING MUCH INFLUENCE ON THE SENSIBLE WEATHER WITH THIS FEATURE BUT THAT COULD CHANGE. NORTHWEST FLOW INTO EASTERN MONTANA ALONG WITH CANADIAN HIGH PUSHING INTO THE NORTHERN PLAINS SUGGEST A SHORT PERIOD OF DRIER WEATHER BUT AS SHORTWAVES BEGIN EJECTING OUT OF THE TROF ALONG THE WEST COAST AND THROUGH THE NORTHERN ROCKIES RIDGE...WILL SEE A RETURN OF THUNDERSTORM CHANCES. AFTER A COOL START TO THE EXTENDED PERIOD WITH THE PROXIMITY OF THE HUDSON BAY LOW...TEMPERATURES WILL WARM THROUGH THE WEEKEND AS UPPER RIDGE PUSHES OUT INTO THE NORTHERN PLAINS. EBERT && .AVIATION... VFR. AN UPPER LEVEL RIDGE WEST OF THE DIVIDE AND A STRONG LOW PRESSURE SYSTEM OVER HUDSON BAY WILL MAINTAIN NORTHWEST FLOW ALOFT FOR NORTHEAST MONTANA. THESE WEATHER SYSTEMS HAVE PLACED A STATIONARY COLD FRONT ACROSS THE LOCAL AREA THAT WILL BE THE FOCUS OF INTERMITTENT RAIN SHOWERS AND GENERAL THUNDERSTORMS THIS AFTERNOON THROUGH WEDNESDAY. BRIEF PERIODS OF LESS THAN VFR CONDITIONS ARE POSSIBLE WITH ANY THUNDERSTORM THAT DEVELOPS. A SURFACE TROUGH ACROSS THE DAKOTAS WILL MAINTAIN NORTHERLY SURFACE WIND THIS AFTERNOON. EXPECT WIND SPEED OF AROUND 10KT TO 20KT. WIND WILL BECOME LIGHT AND VARIABLE TONIGHT AND INTO WEDNESDAY AFTERNOON. SCT && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
924 AM MDT TUE AUG 6 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH THURSDAY... AREAS IN THE SOUTHWEST PART OF THE CWA ARE MOSTLY CLEAR...SO REDUCED CLOUD COVER AND POPS IN THAT AREA FOR THIS MORNING FOR THIS UPDATE. THE HRRR AND OTHER MODELS HAVE PRECIPITATION DEVELOPING AFTER 18Z OVER THE NORTHEAST 2/3RDS OF THE CWA...AND THIS APPEARS TO BE WELL-REPRESENTED IN THE CURRENT FORECAST. VERY MARGINAL INSTABILITY SHOULD KEEP ANY THUNDERSHOWER ACTIVITY ON THE WEAK SIDE. MARTIN PREVIOUS DISCUSSION... SYNOPTIC SET UP... A LARGE CLOSED COLD CORE LOW IS CENTERED OVER NORTHERN MANITOBA AND ITS INFLUENCE SPREADS FAR BACK ACROSS THE CANADIAN PRAIRIES AND NORTHERN US HIGH PLAINS. TO THE SOUTH A LARGE HIGH PRESSURE HEAT DOME STRETCHES FROM THE SOUTHERN PLAINS TO THE FOUR CORNERS INTO THE LOWER INTERMOUNTAIN WEST. NORTHEAST MONTANA LIES IN ZONAL FLOW BETWEEN THESE TWO LARGE FEATURES. TO THE WEST A RIDGE RUNS UP BRITISH COLUMBIA WITH A BROAD WEAK TROUGH OFF THE COAST OF CANADA AND THE US. TODAY THROUGH TONIGHT... THE COLD AIR ACROSS THE REGION IS ANTICIPATED TO MOVE OFF TO THE WEST DURING THE MORNING HOURS. WHILE THE RIDGE ACROSS THE INTERMOUNTAIN WEST IS EXPECTED TO SURGE UP INTO THE BRITISH COLUMBIA RIDGE... RE-ROUTING SLOWLY TO NORTHWEST FLOW AND WARMING THE AREA SLIGHTLY. A WEAK SHORTWAVE IS ANTICIPATED TO RIDE AROUND THE MANITOBA LOW AND WILL BRIEFLY BRUSH THE NORTHEAST CORNER OF THE CWA DURING THE AFTERNOON HOURS. CAPE WITH THIS SYSTEM/SHORTWAVE COULD REACH UP TO 1000 J/KG DURING THE AFTERNOON WITH WEAK SHEAR. CAPE ALSO LOOKS VERY THIN ALLOWING FOR WEAKENING DRY AIR ENTRAINMENT EFFECTS. THIS COULD PRODUCE SOME SMALL HAIL BUT WILL HAVE A HARD TIME BECOMING SEVERE. IN ADDITION... CAPE LOOKS VERY MUCH SURFACE BASED. SO... AS THE SUN GOES DOWN THUNDERSTORMS WILL RAPIDLY DIE OFF LEADING TO A FAIRLY DRY OVERNIGHT PERIOD. WEDNESDAY THROUGH THURSDAY... TEMPERATURES WILL BRIEFLY RISE AGAIN WEDNESDAY. AFTER THAT... A CONFIDENCE PROBLEM ARISES WITH TWO SOLUTIONS.,. ONE BEING THE GFS/NAM AND THE OTHER BEING THE GEM/EC. GFS/NAM SOLUTION BRINGS A SHORTWAVE THROUGH WITH A VERY SHARPENED COLD FRONT AROUND MIDNIGHT. THE EC/GEM SOLUTION BRINGS THE SHORTWAVE THROUGH... BUT DELAYS THE FRONT ABOUT 12 TO 24 HOURS LATER BY LEAVING IT VERY DIFFUSE. BOUNDARY OR NOT... CHANCES FOR POPS SHOULD SHOOT UP A BIT THROUGH THESE PERIODS WITH THE SHORTWAVE. THE QUESTION IS THE EXTENT TO WHICH IT SHOOTS UP BEING DEPENDENT UPON THE FRONT. GAH .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... FORECAST THROUGH THE END OF THE WEEK WILL BE INFLUENCED BY THE LINGERING EFFECTS OF THE STRONG HUDSON BAY LOW. UPPER RIDGE BUILDING NORTH ALONG THE ROCKIES WILL BE THE MAIN PLAYER FOR EARLY NEXT WEEK. MODELS SLIPPING OUT OF AGREEMENT REGARDING THE HUDSON BAY LOW AFTER IT DROPS INTO CENTRAL MANITOBA. ECMWF MOVES IT EAST FASTER THEN THE GFS BUT LEAVES A PORTION BEHIND IN SASKATCHEWAN THURSDAY NIGHT. EC CURRENTLY NOT INDICATING MUCH INFLUENCE ON THE SENSIBLE WEATHER WITH THIS FEATURE BUT THAT COULD CHANGE. NORTHWEST FLOW INTO EASTERN MONTANA ALONG WITH CANADIAN HIGH PUSHING INTO THE NORTHERN PLAINS SUGGEST A SHORT PERIOD OF DRIER WEATHER BUT AS SHORTWAVES BEGIN EJECTING OUT OF THE TROF ALONG THE WEST COAST AND THROUGH THE NORTHERN ROCKIES RIDGE...WILL SEE A RETURN OF THUNDERSTORM CHANCES. AFTER A COOL START TO THE EXTENDED PERIOD WITH THE PROXIMITY OF THE HUDSON BAY LOW...TEMPERATURES WILL WARM THROUGH THE WEEKEND AS UPPER RIDGE PUSHES OUT INTO THE NORTHERN PLAINS. EBERT && .AVIATION... MOSTLY VFR TODAY...EXCEPT FOR MORNING LOW STRATUS IN THE MISSOURI AND YELLOWSTONE RIVER VALLEYS AFFECTING KOLF AND KSDY WITH MVFR CEILINGS. AN UPPER LEVEL RIDGE WEST OF THE DIVIDE AND A STRONG LOW PRESSURE SYSTEM OVER HUDSON BAY WILL MAINTAIN NORTHWEST FLOW ALOFT FOR NORTHEAST MONTANA. THESE WEATHER SYSTEMS HAVE PLACED A STATIONARY COLD FRONT ACROSS THE LOCAL AREA THAT WILL BE THE FOCUS OF INTERMITTENT RAIN SHOWERS AND GENERAL THUNDERSTORMS THIS AFTERNOON THROUGH WEDNESDAY. BRIEF PERIODS OF LESS THAN VFR CONDITIONS ARE POSSIBLE WITH ANY THUNDERSTORM THAT DEVELOPS. A SURFACE TROUGH ACROSS THE DAKOTAS WILL MAINTAIN NORTHWEST SURFACE WIND THIS MORNING THAT WILL VEER TO THE NORTH BY AFTERNOON. EXPECT WIND SPEED OF AROUND 10KT TO 20KT. WIND WILL BECOME LIGHT AND VARIABLE TONIGHT AND WEDNESDAY MORNING. SCT && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1132 PM MDT MON AUG 5 2013 .AVIATION... 06Z TAF CYCLE AN ACTIVE EVENING WINDING DOWN. HOWEVER...ISOLATED SHOWERS AND STORMS STILL ONGOING OVER WESTERN AND NORTHERN NM. WILL CARRY AN HOUR OR TWO TEMPO -SHRA AT KGUP...KFMN...KABQ AND KSAF. ALSO VCTS AT KGUP AND KFMN. SHOULD BE VFR CONDITIONS THOUGH THROUGH AT LEAST 18Z TUE. NEXT CROP OF CONVECTION TUESDAY PM AND EVE MAY BE EVEN MORE WIDESPREAD THAN TODAY AS AN UPPER LEVEL DISTURBANCE MOVES NORTH ACROSS ERN AZ...DRAWING ADDITIONAL MOISTURE NORTH. WILL CARRY VCTS ALL TERMINALS TUE PM EXCEPT KROW WHERE CHANCES WILL BE LOWEST. && .PREV DISCUSSION...244 PM MDT MON AUG 5 2013... LESS ACTIVE TODAY THAN AT THIS TIME YESTERDAY. SHOWERS AND STORMS WITH LOCALLY HVY RAIN ARE STILL DEVELOPING OVER THE NORTHERN AND WESTERN HIGH TERRAIN AND EASTERN HIGH PLAINS. STORM MOTIONS ARE FASTER AND MORE TO THE NORTHEAST. LAPS PARAMETERS STILL INDICATE POTENTIAL FOR A FEW STRONG STORMS ARE FLASH FLOODING IS NOT OUT OF THE QUESTION FOR ANY AREA. RUC GUIDANCE AGAIN SHOWS ACTIVITY MERGING INTO THE RGV THIS VALLEY HOWEVER CONFIDENCE NOT AS HIGH SINCE OTHER GUIDANCE MEMBERS KEEP ALL ACTIVITY FARTHER SOUTH AND THERE IS A LESS THAN IMPRESSIVE CU FIELD OVER THE AREA ATTM. THE INTERESTINGLY THERE IS A WELL DEFINED WAVE THAT HAS DEVELOPED IN THE MONSOONAL PLUME HEADING NORTH INTO THE NM BOOTHEEL. FOR THIS REASON HAVE KEPT A LARGER THAN TYPICAL AREA OF CHANCE POPS FOR THE OVERNIGHT. THE NEXT VERY WELL DEFINED WAVE IS POISED OVER THE BAJA REGION AND THIS WILL MOVE NORTH THROUGH THE MONSOON PLUME TUESDAY. TOTAL BLENDED PWAT VALUES PER CIRA IMAGERY WITH THIS WAVE ARE IN THE 2.25-2.50 RANGE. 12Z GFS INDICATES THE MAX THETA-E WAVE ASSOCIATED WITH THIS SYSTEM WILL SLIDE OVER CENTRAL AND WESTERN NM NOW... WHICH IS A LITTLE FARTHER EAST THAN PREVIOUS RUNS. STORM MOTIONS WILL BE FASTER TO THE NE BUT FLASH FLOODING IS STILL A CONCERN. THIS UPPER WAVE WILL GET CAUGHT UP IN INCREASING WESTERLY FLOW OVER THE CENTRAL ROCKIES THEN NW FLOW OVER THE GREAT PLAINS. A BACK DOOR FRONTAL BOUNDARY WILL BE FORCED SOUTHWARD INTO THE NE PLAINS BEHIND THESE UPPER DYNAMICS. VERY MOIST UPSLOPE FLOW WILL IMPACT THE SANGRES EASTWARD ACROSS THE PLAINS AND GIVEN LATEST ROUNDS OF HEAVY RAINFALL IN THIS AREA...THE FLASH FLOOD THREAT WILL BE QUITE HIGH. WEDNESDAY NIGHT EXPECTING TO SEE A LARGE RAIN SHIELD SHIFTING SOUTHEAST OVER THE EAST...FOLLOWED BY A DRIER DAY FOR THURSDAY. TEMPS WILL BE BELOW NORMAL THROUGH THE WHOLE PERIOD. THE FRIDAY THROUGH MONDAY PERIOD LOOKS INTERESTING WITH ANOTHER MONSOON BURST POSSIBLE DURING THIS TIME OVER CENTRAL AND WESTERN NM. MODEL CONSISTENCY ON TIMING AND PLACEMENT IS NOT THE BEST SO WILL KEEP VALUES JUST AT CLIMO OR BELOW FOR NOW. GUYER .FIRE WEATHER... UPPER HIGH WILL REMAIN CENTERED OVER PORTIONS OF TEXAS AND THE LOWER MISSISSIPPI VALLEY THROUGH TUESDAY. THE MONSOONAL MOISTURE PLUME WILL REMAIN CENTERED OVER WESTERN AND CENTRAL NEW MEXICO DURING THIS PERIOD. WETTING THUNDERSTORMS WILL BE EMBEDDED WITHIN THIS PLUME WITH HIGHER HUMIDITY. MODELS SHOWS A GRADUAL CHANGE IN THE MONSOON FLOW WEDNESDAY AND THURSDAY AS A WEAK TROUGH SWINGS ACROSS THE SOUTHERN AND CENTRAL ROCKIES. WEDNESDAY COULD BE QUITE DYNAMIC AS FAR AS AN EXPECTED DRIER TREND ACROSS THE WEST AND WETTING THUNDERSTORMS CENTRAL AND EASTERN AREAS. MODELS SHOW AN UPTICK IN THE UPPER FLOW SO THIS SHOULD TRANSLATE INTO A LITTLE STRONGER SURFACE WIND VERSUS WHAT WE HAVE HAD THE PAST SEVERAL DAYS. MIGHT BE A LITTLE LOW IN THE GRIDDED WIND FORECAST SO WILL WATCH THE TREND IN THE MODELS. A BACK DOOR COLD FRONT TIED TO A VIGOROUS LOW PRESSURE AREA SHOULD ADD TO THE THUNDERSTORM FOCUS ACROSS THE NORTHEAST. IT APPEARS THAT HUMIDITY VALUES LOWER THE MOST ACROSS THE SOUTHWEST HALF. THURSDAY LOOKS TO BE DRIER BOTH HUMIDITY AND WETTING THUNDERSTORM WISE. WINDS ALSO LOOK TO BE LIGHTER ON THURSDAY VERSUS WEDNESDAY. BOTH THE ECMWF AND GFS WEATHER MODELS SHOW THE UPPER HIGH REDEVELOPING OVER CENTRAL TEXAS ON FRIDAY. MONSOONAL MOISTURE WOULD TRY TO FLOW BACK OVER THE AREA. AS OF RIGHT NOW...RESIDUAL OR LEFTOVER MOISTURE SHOULD FOCUS WETTING THUNDERSTORM DEVELOPMENT OVER THE NORTH CENTRAL MOUNTAINS AND PORTIONS OF THE NORTHEAST PLAINS. THE PLUME OF MOISTURE SHOULD REINVIGORATE OVER WESTERN AND CENTRAL NEW MEXICO DURING THE WEEKEND. HUMIDITY VALUES WOULD TREND UP. A MONSOON BURST CONCENTRATING SIGNIFICANT MOISTURE AND STORMS WOULD BE POSSIBLE DURING THIS PERIOD. WEATHER MODELS TRY TO ELONGATE THE UPPER HIGH OVER PORTIONS OF NEW MEXICO EARLY NEXT WEEK. RESIDUAL MOISTURE WOULD BE AROUND AND CAUGHT WITHIN THIS UPPER HIGH ALTHOUGH STORMS WOULD BE MORE IN THE RECYCLE MODE VERSUS A TRUE MONSOON BURST MODE. THUS THE WETTING RAIN COVERAGE WOULD GRADUALLY DECLINE. WILL CONTINUE TO MONITOR THIS TREND. 50 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1030 PM EDT WED AUG 7 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 1030 PM EDT WEDNESDAY...BASED ON CURRENT RADAR AND RECENT NAM/RAP/HRRR GUIDANCE TRENDS HAVE MADE FAIRLY SIGNIFICANT DOWNWARD TWEAKS TO POPS TONIGHT INTO THURSDAY MORNING. ASIDE FOR SOME SHOWERS THAT HAD MOVED ACROSS THE NORTHERN CHAMPLAIN VALLEY INTO NORTHERN VERMONT...STEADIER/HEAVIER SHOWERS AND THUNDERSTORMS REMAIN ACROSS EASTERN ONTARIO AND THE NORTHERN SHORE OF LAKE ONTARIO. THE RADAR RETURNS ACROSS THE SAINT LAWRENCE VALLEY ARE MERELY ANVIL SHADOWS...AND RECENT TRENDS SHOW BETTER CONVECTIVE DEVELOPMENT TRAILING BACK ALONG THE NORTHERN SHORE OF LAKE ONTARIO IN THE VICINITY OF THE TORONTO AREA. AS MENTIONED...FEEL THAT THE NAM...RAP AND HRRR MODELS ARE CURRENTLY HANDLING PRESENT CONDITIONS THE BEST AND HAVE THEREFORE ALIGNED THE FORECAST CLOSER TO THAT SUITE OF GUIDANCE. SPECULATING THAT OTHER WETTER GUIDANCE...E.G. THE GFS...MAY HAVE BEEN KEYING ON DEEPER MOISTURE FEED WHICH THE EARLIER MCS OVER PA MAY HAVE TAPPED INTO. NEVERTHELESS...STILL EXPECT SFC COLD FRONT ACROSS ONTARIO TO APPROACH THE NORTH COUNTRY THROUGH OVERNIGHT BUT WILL ONLY BE GOING WITH CHANCE TO HIGH CHANCE POPS THROUGH SUNRISE...AND THEN SLIGHT CHANCE TO CHANCE THROUGH THE THURSDAY MORNING PERIOD. CURRENT TEMPS/DEWPOINTS STILL LOOK ON TRACK AND IT SHOULD OTHERWISE BE A CLOUDY...MILDER AND SLIGHTLY MORE HUMID NIGHT THAN RECENTLY WITH LOWS IN THE UPPER 50S TO THE 60S. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 341 PM EDT WEDNESDAY...THE EXTENDED PORTION OF THE FORECAST WILL FEATURE PRETTY QUIET AND COOL WEATHER...NO SIGNIFICANT CHANCES FOR PRECIPITATION. UPPER LEVEL LOW LIFTS NORTHEAST AND AWAY FROM THE NORTH COUNTRY SATURDAY AND A RIDGE OF SURFACE HIGH PRESSURE BUILDS INTO THE AREA. MAINLY DRY WEATHER IS EXPECTED FROM SATURDAY THROUGH MONDAY. A LOW PRESSURE SYSTEM PASSING NORTH OF OUR REGION ON MONDAY NIGHT WILL BRING A CHANCE FOR SOME SHOWERS...THOUGH BEST DYNAMICS REMAIN WELL NORTH OF OUR FORECAST AREA. TUESDAY THROUGH WEDNESDAY WILL ALSO BE QUIET WITH ANOTHER RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... THROUGH 00Z FRIDAY...DIFFICULT AVIATION FORECAST OVER THE NEXT 24 HOURS AS MOST MODELS NOT HANDLING THE CURRENT CONDITIONS VERY WELL. BROKEN LINE OF SHOWERS/STORMS ENTERING THE OTTAWA RIVER VALLEY ASSOCIATED WITH A PRE-FRONTAL SURFACE TROUGH WILL SHIFT EAST INTO THE NORTH COUNTRY OVERNIGHT WHILE DISSIPATING. HAVE PUT IN SOME VCTS FOR KMSS/KSLK BUT ONLY VCSH EASTWARD AS INSTABILITY WEAKENS BY THE TIME PRECIP GETS THERE. SCATTERED SHOWERS PERSIST THROUGH 09-12Z ALONG WITH SOME MVFR CIGS...THEN DISSIPATE FOR THE MORNING HOURS AS THE REAL COLD FRONT BEGINS TO MOVE INTO THE SAINT LAWRENCE VALLEY. MAINLY VFR CONDITIONS ARE THEN EXPECTED THURSDAY WITH SCATTERED SHOWERS AND POSSIBLY STORMS ARE LIKELY AGAIN FROM THE CHAMPLAIN VALLEY EAST DURING THE AFTERNOON...THOUGH DIFFICULT TO FORECAST TIMING AND LOCATION SO HAVE JUST GONE WITH SOME MORE VCSH. WINDS REMAIN MODERATE AT 5-10 KNOTS THROUGH THE PERIOD... GUSTING A BIT THIS EVENING AND AGAIN TOMORROW AFTERNOON. OUTLOOK 00Z FRIDAY THROUGH MONDAY... 00Z FRIDAY THROUGH 00Z SATURDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 00Z SATURDAY THROUGH MONDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH/LOCONTO SHORT TERM...WGH LONG TERM...NEILES AVIATION...LAHIFF MARINE... EQUIPMENT...
AREA FORECAST DISCUSSION
NWS BUFFALO NY
846 PM EDT WED AUG 7 2013 .SYNOPSIS... SOUTHERLY WINDS BETWEEN HIGH PRESSURE OFF THE EAST COAST AND A COLD FRONT APPROACHING FROM THE MIDWEST WILL KEEP WARM AND MORE HUMID CONDITIONS TO OUR AREA TONIGHT...ALONG WITH A CHANCE FOR A FEW SHOWERS AND THUNDERSTORMS. SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD LATER TONIGHT AND THURSDAY MORNING AS THE FRONT MOVES ACROSS WESTERN AND CENTRAL NEW YORK. SOMEWHAT UNSETTLED WEATHER WILL LAST INTO FRIDAY. && .NEAR TERM /THROUGH THURSDAY/... WESTERN NEW YORK IS IN A DRY SLOT LATE THIS EVENING IN THE WAKE OF AN EXITING SHORTWAVE WHICH SPARKED AN MCS TO OUR SOUTH. MEANWHILE...THERE IS FAIRLY UNSTABLE AIR IN PLACE (500 TO 1000 J/KG) BUT NO FOCUS TO TAP THIS ENERGY. THAT MIGHT CHANGE LATER THIS EVENING...AS THE FRONTAL BOUNDARY ITSELF DROPS ACROSS THE REGION. MODEL GUIDANCE HAS STRUGGLED IN HANDLING THIS CONVECTION...BUT IT SEEMS THAT THE 18Z NAM AND HOURLY RUNS OF THE HRRR HAVE HAD THE BEST HANDLE ON THIS. FOLLOWING THIS...EXPECT SHOWERS AND THUNDERSTORMS ACROSS ONTARIO TO DROP SOUTHWARD DURING THE EVENING HOURS...WITH WHATEVER REMAINS OF THIS ACTIVITY DROPPING SOUTH OF LAKE ONTARIO AROUND OR SHORTLY AFTER MIDNIGHT. THE BEST CHANCE FOR THUNDERSTORMS WILL BE EAST OF LAKE ONTARIO...WHERE UPSTREAM CONVECTION IS MOST VIGOROUS. ELSEWHERE IT REMAINS A BIT UNCERTAIN HOW SOLID THE LINE WILL BE...WITH ONLY SCATTERED UPSTREAM ACTIVITY WEST OF TORONTO AND LONDON. FOR NOW WILL MAINTAIN LIKELY POPS FROM BUF-ROC...THEN TAPER DOWN AS THE NIGHT GOES ON FIGURING CONVECTION WILL TAPER OFF WITH THE LOSS OF HEATING AND THE STALLING FRONTAL BOUNDARY. THE SEVERE WEATHER POTENTIAL FOR OUR REGION REMAINS QUITE LIMITED...WITH THE MOST ORGANIZED CONVECTION UPSTREAM OF THE NORTH COUNTRY. IT STILL APPEARS THAT THE STEADIEST SHOWERS AND THUNDERSTORMS WILL OCCUR IN THE 11 PM TO 4 AM TIME FRAME. FOR THURSDAY...THE FRONTAL BOUNDARY WILL BE STALLED ACROSS OUR REGION. THERE WILL BE A MARGINAL CHANCE FOR SHOWERS IN THE MORNING...WITH INCREASING CHANCES DURING THE AFTERNOON HOURS WILL ANY MODEST DAYTIME HEATING...AND DEVELOPING LAKE BREEZE CONVERGENCE BOUNDARIES. FOR TEMPERATURES...THE CONTINUED INFLUX OF WARM AND HUMID AIR THROUGH THE NIGHT...THE OVERNIGHT LOWS WILL BE IN THE MIDDLE TO UPPER 60S AND EVEN NEAR 70 IN DOWNSLOPING AREAS ACROSS THE LAKE PLAINS AND IN URBAN AREAS. WITH THE SLOW PASSAGE OF THE COL FRONT ON THURSDAY...EXPECT HIGH TEMPS TO REACH THE UPPER 70S TO LOWER 80S. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... MATURE SURFACE LOW PRESSURE AND PARENT UPPER LEVEL LOW WILL BE CENTERED OVER NORTHERN ONTARIO PROVINCE NEAR THE HUDSON BAY THURSDAY EVENING. A COLD FRONT ORIENTED FROM A TRIPLE POINT LOW OVER THE CANADIAN MARITIMES SOUTHWEST ACROSS THE ADIRONDACKS TO THE OHIO VALLEY WILL BE STALLING/SLOWING AS IT BECOMES PARALLEL WITH THE UPPER LEVEL FLOW. A SURFACE WAVE WILL LIFT NORTHEAST ALONG THE FRONT THURSDAY EVENING. A SWATH OF SHOWERS ASSOCIATED WITH THIS WAVE AND POSSIBLY SOME EMBEDDED LIGHTING LOOKS TO SHIFT ACROSS THE SOUTHERN TIER INTO THE FINGER LAKES AND ACROSS CENTRAL NEW YORK IN THE EVENING. ITS NORTHERN EDGE MAY EVEN BRING SOME LIGHT RAIN TO THE NIAGARA FRONTIER. THE SHOWERS WILL SHIFT EAST INTO CENTRAL AND EASTERN NEW YORK OVERNIGHT. THE SURFACE WAVE WILL SHIFT NORTH ACROSS NEW ENGLAND THROUGH FRIDAY WHILE ACTING TO SHOVE THE COLD FRONT WELL SOUTH AND EAST OF THE FORECAST AREA. A CHANCE OF RAIN WILL LINGER ACROSS THE FINGER LAKES AND NORTH COUNTY FRIDAY MORNING OTHERWISE EXPECT WESTERN AND NORTH CENTRAL NEW YORK TO BE RAIN FREE BY MID-AFTERNOON BEHIND THE FRONT. THE 12Z NAM IS THE ONLY OUTLIER IN THIS SCENARIO AS IT FORECASTS A SECOND SURFACE WAVE TO LIFT ALONG THE FRONT EARLY FRIDAY WITH ANOTHER ROUND OF RAIN ACROSS WNY THROUGH THE AFTERNOON. THIS IDEA HAS BEEN DISCOUNTED WITH THE MAJORITY OF FORECAST MODELS SHOWING DRY CONDITIONS ON FRIDAY. CANADIAN PRAIRIE SOURCED HIGH PRESSURE WILL BUILD ACROSS THE GREAT LAKES REGION THROUGH FRIDAY AND INTO SATURDAY WITH SEASONABLY COOL TEMPERATURES AND DRY SUNNY CONDITIONS TO START OFF THE WEEKEND. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AN AMPLIFIED WESTERN RIDGE AND EASTERN TROUGH 500MB PATTERN WILL BE IN PLACE ACROSS SOUTHERN CANADA OVER THE WEEKEND. ZONAL FLOW IN THE BASE OF THE EASTERN CANADIAN TROUGH WILL EXTENDING FROM THE NORTHERN PLAINS EAST ACROSS THE GREAT LAKES TO THE NORTHEAST STATES. THIS SHOULD KEEP SEASONABLY COOL AND DRY WEATHER IN PLACE FOR AT LEAST SUNDAY AND MONDAY. MEDIUM RANGE MODELS THEN SHOW THE NEXT STRONG VORTICITY MAX/DISTURBANCE TO DROP INTO THE BASE OF THIS TROUGH ACROSS THE GREAT LAKES MONDAY NIGHT AND LIFTING INTO ATLANTIC CANADA ON TUESDAY. THE 00Z ECMWF IS MUCH DRIER AHEAD OF THE TROUGH AXIS THAN THE 12Z GFS SHOWING JUST A LIMITED SHOWER THREAT. THE GFS SHOWS MORE OF A FRONTAL ORIENTATION. HAVE ONLY INCLUDED A SLIGHT CHANCE OF SHOWERS FOR NOW MONDAY NIGHT IN TO TUESDAY UNTIL MORE MODEL AGREEMENT CAN BE MADE. BY WEDNESDAY HIGH PRESSURE EITHER LINGERS OR BUILDS BACK ACROSS NEW YORK DEPEND ON WHICH MODEL YOU LOOK AT BUT WILL KEEP WEDNESDAY DRY. THE LINGERING TROUGH OVER EASTERN CANADA WILL KEEP SEASONABLY COOL TEMPERATURES IN PLACE ACROSS THE FORECAST AREA THROUGH MID NEXT WEEK WITH NO STRONG CONNECTION TO THE GULF OR ATLANTIC. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... FOR THE 00Z TAF CYCLE...EXPECT MOSTLY VFR CONDITIONS THIS EVENING...AS THE REGION IS IN A DRY SLOT. SHOWERS AND THUNDERSTORMS ALONG A FRONTAL BOUNDARY WILL DROP FROM N-S ACROSS THE REGION LATE TONIGHT...GRADUALLY WEAKENING AS THEY DO. THUNDERSTORMS MAY BRING BRIEF PERIODS OF HEAVY RAIN...LOWERING VSBY TO 2SM OR LESS. OUTSIDE OF THUNDERSTORMS...EXPECT MAINLY VFR CONDITIONS. LINGERING LOW MOISTURE MAY RESULT IN SOME LOW CLOUDS OR FOG AT JHW...OR BRIEF PERIODS OF MVFR CIGS ELSEWHERE. ON THURSDAY...EXPECT ONLY SCATTERED LIGHT SHOWERS IN THE MORNING...WITH SHOWERS AND THUNDERSTORMS A BIT MORE WIDESPREAD DURING THE AFTERNOON HOURS. OUTLOOK... THURSDAY NIGHT AND FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS. SATURDAY AND SUNDAY...VFR. MONDAY...VFR WITH CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS. && .MARINE... AS A COLD FRONT CROSSES THE CENTRAL LAKES LATE TONIGHT AND EASTERN LAKES ON THURSDAY...THE WINDS WILL SWITCH TO THE WEST SOUTHWEST AND DIMINISH. HIGH PRESSURE IS FORECAST TO SETTLE ACROSS THE EASTERN LAKES ON FRIDAY. SMALL CRAFT ADVISORY CONDITIONS ARE NOT EXPECTED. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...WCH NEAR TERM...APFFEL/WCH SHORT TERM...SMITH LONG TERM...SMITH AVIATION...APFFEL MARINE...APFFEL/WCH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
743 PM EDT WED AUG 7 2013 .SYNOPSIS... RAIN AND THUNDER CHANCES INCREASE THIS EVENING, AS A COLD FRONT MOVES SOUTHEAST TOWARDS THE AREA. THIS FEATURE WILL THEN STALL WEST OF THE AREA BY MORNING, KEEPING THE THREAT FOR CONTINUED SHOWERS AND STORMS IN THE FORECAST THROUGH THE REMAINDER OF THE WORK WEEK. THIS FRONTAL PASSAGE LOOKS TO FINALLY OCCUR FRIDAY EVENING. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 545 PM UPDATE... WITH CLOUDY SKIES AND MARINE LAYER SHOWERS ARE NOT MATERIALIZING. LOWERED POPS. A FEW SHOWERS AND TSTORMS FORMED IN WRN NY AND WRN PA BUT THEY ARE DYING AS THEY MOVE EAST. BULK OF PA PRECIP WILL MISS TO THE SOUTH AND VERY LITTLE IN NY. SEE NO REASON WHY THE MARINE LAYER WITH COOL TEMPS WILL NOT REMAIN THROUGH THE NIGHT. 245 PM UPDATE... SFC LOPRES JUST SOUTH OF HUDSON BAY HAS DRAPED A CDFNT DOWN ACRS LK HURON AND SWWRD INTO NRN MO. AT THE SAME TIME CONVECTION THAT DVLPD OVRNGT HAS THROWN OUT A GUST FRONT AND HAS ALLOWED STORMS TO DVLP ACRS NRN OH. MAIN AREA OF STORMS ACRS SRN ONTARIO HAS LIFTED NORTH AS EXPECTED WITH MAIN S/WV ROTATING ARND BASE OF HUDSON BAY TROF. TIMING ON THIS AFOREMENTIONED LINE OF STORMS PLACES IT INTO EXTRM WRN ZONES BY 21Z THIS AFTN AND WL WORK TWD CNTRL PART OF CWA BY 00Z. THIS LOOKS TO BE KICKED OFF BY S/WV WORKING ITS WAY EAST ACRS NRN OH AND IT APPEARS TO BE HEADING A LITTLE SOUTH OF EAST. THUS, WL MAINTAIN LKLY POPS THRU TONIGHT WITH CONTINUAL MOISTURE BEING PUMPED INTO REGION ON LLJ AND PW VALUES INCRSG TO NEAR 1.50 INCHES AND ANY SUBTLE S/WVS THAT ENCROACH UPON THE AREA. BULLSEYE OF QPF ALONG THE I-81 CORRIDOR ADVERTISED BY 12Z GFS AND LATEST RAP APPEARS TO BE A RESULT OF CONVECTIVE FEEDBACK AND HV DISCOUNTED THIS SOLN. THINK THAT AREAL AVGS WL LKLY BE BETWEEN 0.25 AND 0.50 INCHES. AS FOR OVRNGT MINS DO NOT THINK TEMPS WL MV MUCH AS CLDS RMN ENTRENCHED OVR AREA. FCST LOWS WL BOTTOM OUT IN THE L/M 60S. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... 245 PM UPDATE... FRONTAL BNDRY WL STALL OUT THUR MRNG JUST TO THE WEST OF THE AREA AND RMN THERE INTO FRIDAY. VRY LITTLE MIXING WL OCCUR DRG THE DAY AS AREA WL LKLY BE SOCKED IN WITH CLDS ONCE AGAIN. MAX TEMPS WL JUST BARELY TOP OUT IN THE 80S. CAPES WL BE SIMILAR TO WED WITH VALUES APPCHG 1000 J/KG BUT WIND SHEAR IS EXPECTED TO DROP OFF DRG THE DAY. PW VALUES PROGGED TO APPCH 2.00 INCHES DRG THE DAY THUS ANY STORM THAT DVLPS MAY PRODUCE MODERATE TO HVY RAIN. LKLY POPS WL CONTINUE TOMORROW NGT AS BNDRY RMNS STALLED OUT TO THE WEST. MED RANGE MODELS HINTING AT SFC LOPRES RIDING UP ALONG THE FRONT THU NGT AND HELPING GIVE THE FRONT A LITTLE SHOVE TO THE SOUTH. FROPA NOW LOOKS TO OCCUR DRG THE DAY FRIDAY. THUS, HV TAKEN OUT PCPN AFT 12Z SATURDAY. NO OTHER CHGS NEEDED TO THE END OF THE SHORT TERM WITH PERHAPS SOME LINGERING SHOWERS ON FRIDAY WITH RMNG UL WV MVG THRU BHND FRONT. ELONGATED VORT MAX PROGGED TO MV THRU ON SATURDAY BUT WITH DRY AIRMASS IN PLACE NOT EXPECTING MUCH MORE THAN CLDS AT THIS POINT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... 200 PM UPDATE... AREA REMAINS UNDER A BROAD LONG WAVE UPPER LEVEL TROUGH THROUGH THE PERIOD AND SLIGHTLY COOLER THAN NORMAL TEMPERATURES WITH HIGHS IN LOWER TO MIDDLE 70S AND NIGHTTIME LOWS IN THE 50S. A FRONT THAT MOVED THROUGH THE AREA EARLY SATURDAY IS FORECAST TO STALL IN A EAST-WEST MANNER ACROSS VIRGINA SATURDAY NIGHT INTO SUNDAY. FROM THIS POINT MODELS HAVE DIFFERENCES OF TIMING AND POSITIONING OF WAVES MOVING EASTWARD ALONG THIS FRONT THROUGH MIDWEEK CAUSING SOME UNCERTAINTY IN THE FORECAST. FORECASTED CLOUDS TO SPREAD NORTH WITH A WAVE ON SUNDAY BUT JUST PLACED A SLIGHT CHANCE THUNDERSTORMS IN THE POCONOS FOR SUNDAY AFTERNOON. HIGH PRESSURE BUILDS ACROSS SUNDAY NIGHT BEHIND THIS WAVE. A SHORT-WAVE MOVING AROUND THE UPR LEVEL LOW TO OUR NORTH MAY BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE AFTERNOON MONDAY. UNCERTAINTY INCREASES TUESDAY AS GFS LINKS A SHORT-WAVE MOVING AROUND THE UPR LOW TO THE NORTH WITH A SURFACE LOW AND WAVE MOVING NORTHEAST ALONG THAT FRONTAL ZONE AND SPREADS CLOUDS AND PRECIPITATION NORTHEAST ACROSS THE AREA TUESDAY. ON THE OTHER HAND THE ECMWF DOES NOT LINK A WAVE UP FROM THE SOUTH WITH JUST AN ISOLATED CHANCE. PUT A 30 POP IN TUESDAY AFTERNOON. SURFACE HIGH PRESSURE BUILDS IN FOR WEDNESDAY WITH A SHORTWAVE RIDGE ALOFT. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... UPR WV AND WRM FNT FEATURE PUSHING THRU ATTM. HWVR...STUBBORN SELY FLOW WILL KEEP A MARINE LYR IN THE AREA FOR MUCH OF THE NGT KEEPING CIGS IN THE MVFR RANGE...WITH BRIEF MVFR VSBYS PSBL. DRIER AIR BEGINS TO WORK INTO THE AREA ON THU AHD OF A SFC COLD FNT SO XPCT CIGS AND VSBYS TO CLIMB INTO THE VFR RANGE. BEST CHANCE OF TSRA TMRW WILLBE OVER NEPA AND AVP WHERE BETTER INSTABILITY WILL DVLP. BRIEF MVFR CIGS AND VSBY PSBL THERE. OUTLOOK... THU NGT...MVFR IN SHRA AND TSRA. FRI...VFR BUT MVFR IN SCATTERED SHRA/TSRA MAINLY SOUTH. SAT THRU MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...PVN/TAC NEAR TERM...PVN/TAC SHORT TERM...PVN LONG TERM...BMW AVIATION...BMW/DGM
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
740 PM EDT WED AUG 7 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 714 PM EDT WEDNESDAY...REGIONAL COMPOSITE RADAR SHOWS ONLY VERY LIGHT SHOWERS ACROSS THE ADIRONDACKS...IN FACT MUCH OF IT ISN`T EVEN REACHING THE GROUND WITH ONLY POTSDAM AND MASSENA NY NOTING LIGHT RAIN. FURTHER WEST...A BROKEN LINE OF CONVECTION HAS DEVELOPED ACROSS LAKE ONTARIO AND BACK INTO CENTRAL ONTARIO. RAP ANALYSIS DO SHOW CAPES IN EXCESS OF 1000 J/KG AND SHOWALTERS BETWEEN -1 TO -2 IN THE SAINT LAWRENCE VALLEY AREA. THE STORMS MAY ALSO BE TAPPING INTO SOME DYNAMIC SUPPORT ON THE SOUTHERN EDGE OF A VORTICITY MAXIMA EXITING INTO CENTRAL QC. SO ONE CHANGE WAS TO INCLUDE SLIGHT CHANCE MENTION OF THUNDERSTORMS IN FOR THE SAINT LAWRENCE VALLEY INTO THE NORTHERN ADIRONDACKS WITH THE THUNDER THREAT TO DIMINISH THRU LATE EVENING. STILL THINK GENERAL START OF SHOWERS IN VERMONT UNTIL LATE EVENING/AFTER MIDNIGHT LOOKS GOOD...BUT THERE`S SOME QUESTION FROM RECENT NEAR-TERM GUIDANCE AS TO HOW LONG THE RAIN SHOWERS LAST. HRRR REFLECTIVITY PROGS DON`T SHOW MUCH ACTIVITY AT ALL WHILE LOCAL BTV4/BTV12 GUIDANCE SUGGEST THAT SHOWERS PUSH THROUGH VERMONT BUT BEGIN TO WEAKEN. MOST OF THE GUIDANCE KEEP RAIN GOING...BUT THE EVIDENT DRY SLOT ON WV IMAGERY AND FAST WEST FLOW ALOFT ALSO SUGGEST THE HRRR IDEA CAN`T BE TOTALLY DISCOUNTED EITHER. WILL AWAIT UPCOMING GUIDANCE COMING IN LATER THIS EVENING BEFORE MAKING ANY SIGNIFICANT CHANCES TO POPS AFTER MIDNIGHT. OTHERWISE...REST OF FORECAST REMAINS ON TRACK. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 341 PM EDT WEDNESDAY...THE EXTENDED PORTION OF THE FORECAST WILL FEATURE PRETTY QUIET AND COOL WEATHER...NO SIGNIFICANT CHANCES FOR PRECIPITATION. UPPER LEVEL LOW LIFTS NORTHEAST AND AWAY FROM THE NORTH COUNTRY SATURDAY AND A RIDGE OF SURFACE HIGH PRESSURE BUILDS INTO THE AREA. MAINLY DRY WEATHER IS EXPECTED FROM SATURDAY THROUGH MONDAY. A LOW PRESSURE SYSTEM PASSING NORTH OF OUR REGION ON MONDAY NIGHT WILL BRING A CHANCE FOR SOME SHOWERS...THOUGH BEST DYNAMICS REMAIN WELL NORTH OF OUR FORECAST AREA. TUESDAY THROUGH WEDNESDAY WILL ALSO BE QUIET WITH ANOTHER RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THROUGH 00Z FRIDAY...DIFFICULT AVIATION FORECAST OVER THE NEXT 24 HOURS AS MOST MODELS NOT HANDLING THE CURRENT CONDITIONS VERY WELL. BROKEN LINE OF SHOWERS/STORMS ENTERING THE OTTAWA RIVER VALLEY ASSOCIATED WITH A PRE-FRONTAL SURFACE TROUGH WILL SHIFT EAST INTO THE NORTH COUNTRY OVERNIGHT WHILE DISSIPATING. HAVE PUT IN SOME VCTS FOR KMSS/KSLK BUT ONLY VCSH EASTWARD AS INSTABILITY WEAKENS BY THE TIME PRECIP GETS THERE. SCATTERED SHOWERS PERSIST THROUGH 09-12Z ALONG WITH SOME MVFR CIGS...THEN DISSIPATE FOR THE MORNING HOURS AS THE REAL COLD FRONT BEGINS TO MOVE INTO THE SAINT LAWRENCE VALLEY. MAINLY VFR CONDITIONS ARE THEN EXPECTED THURSDAY WITH SCATTERED SHOWERS AND POSSIBLY STORMS ARE LIKELY AGAIN FROM THE CHAMPLAIN VALLEY EAST DURING THE AFTERNOON...THOUGH DIFFICULT TO FORECAST TIMING AND LOCATION SO HAVE JUST GONE WITH SOME MORE VCSH. WINDS REMAIN MODERATE AT 5-10 KNOTS THROUGH THE PERIOD... GUSTING A BIT THIS EVENING AND AGAIN TOMORROW AFTERNOON. OUTLOOK 00Z FRIDAY THROUGH MONDAY... 00Z FRIDAY THROUGH 00Z SATURDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 00Z SATURDAY THROUGH MONDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH/LOCONTO SHORT TERM...WGH LONG TERM...NEILES AVIATION...LAHIFF MARINE...MUCCILLI EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
714 PM EDT WED AUG 7 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 714 PM EDT WEDNESDAY...REGIONAL COMPOSITE RADAR SHOWS ONLY VERY LIGHT SHOWERS ACROSS THE ADIRONDACKS...IN FACT MUCH OF IT ISN`T EVEN REACHING THE GROUND WITH ONLY POTSDAM AND MASSENA NY NOTING LIGHT RAIN. FURTHER WEST...A BROKEN LINE OF CONVECTION HAS DEVELOPED ACROSS LAKE ONTARIO AND BACK INTO CENTRAL ONTARIO. RAP ANALYSES DO SHOW CAPES IN EXCESS OF 1000 J/KG AND SHOWALTERS BETWEEN -1 TO -2 IN THE SAINT LAWRENCE VALLEY AREA. THE STORMS MAY ALSO BE TAPPING INTO SOME DYNAMIC SUPPORT ON THE SOUTHERN EDGE OF A VORTICITY MAXIMA EXITING INTO CENTRAL QC. SO ONE CHANGE WAS TO INCLUDE SLIGHT CHANCE MENTION OF THUNDERSTORMS IN FOR THE SAINT LAWRENCE VALLEY INTO THE NORTHERN ADIRONDACKS WITH THE THUNDER THREAT TO DIMINISH THRU LATE EVENING. STILL THINK GENERAL START OF SHOWERS IN VERMONT UNTIL LATE EVENING/AFTER MIDNIGHT LOOKS GOOD...BUT THERE`S SOME QUESTION FROM RECENT NEAR-TERM GUIDANCE AS TO HOW LONG THE RAIN SHOWERS LAST. HRRR REFLECTIVITY PROGS DON`T SHOW MUCH ACTIVITY AT ALL WHILE LOCAL BTV4/BTV12 GUIDANCE SUGGEST THAT SHOWERS PUSH THROUGH VERMONT BUT BEGIN TO WEAKEN. MOST OF THE GUIDANCE KEEP RAIN GOING...BUT THE EVIDENT DRYSLOT ON WV IMAGERY AND FAST WEST FLOW ALOFT ALSO SUGGEST THE HRRR IDEA CAN`T BE TOTALLY DISCOUNTED EITHER. WILL AWAIT UPCOMING GUIDANCE COMING IN LATER THIS EVENING BEFORE MAKING ANY SIGNIFICANT CHANCES TO POPS AFTER MIDNIGHT. OTHERWISE...REST OF FORECAST REMAINS ON TRACK. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 341 PM EDT WEDNESDAY...THE EXTENDED PORTION OF THE FORECAST WILL FEATURE PRETTY QUIET AND COOL WEATHER...NO SIGNIFICANT CHANCES FOR PRECIPITATION. UPPER LEVEL LOW LIFTS NORTHEAST AND AWAY FROM THE NORTH COUNTRY SATURDAY AND A RIDGE OF SURFACE HIGH PRESSURE BUILDS INTO THE AREA. MAINLY DRY WEATHER IS EXPECTED FROM SATURDAY THROUGH MONDAY. A LOW PRESSURE SYSTEM PASSING NORTH OF OUR REGION ON MONDAY NIGHT WILL BRING A CHANCE FOR SOME SHOWERS...THOUGH BEST DYNAMICS REMAIN WELL NORTH OF OUR FORECAST AREA. TUESDAY THROUGH WEDNESDAY WILL ALSO BE QUIET WITH ANOTHER RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THROUGH 18Z THURSDAY...-RW DEVELOPS IN N NY...W/ CONDITIONS DROPPING THRU REST OF FORECAST PERIOD AS FRNT PUSH THRU AREA...MAINLY OVERNIGHT. LOOKING FOR VFR TO DROP DOWN TO IFR/MVFR MIX BY 03Z THURS...WITH VSBY 2-6SM AND CEILINGS BKN020-040. WINDS SSE TO SSW 5-15KTS W/ GUSTS NEAR 20KTS IN THE CVLY. TRW ALSO POSSIBLE BY 00Z. CONDITIONS WILL IMPROVE AT ALL TAF SITES BY ABOUT 12Z THURSDAY...THOUGH SOME MVFR CIGS STILL POSSIBLE. OUTLOOK 18Z THURSDAY THROUGH SUNDAY... 18Z THURSDAY THROUGH 06Z FRIDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 06Z FRIDAY THROUGH SUNDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE WITH ISOLATED SHOWERS ACROSS THE HIGHER TERRAIN POSSIBLE SATURDAY AFTERNOON. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH/LOCONTO SHORT TERM...WGH LONG TERM...NEILES AVIATION...NEILES MARINE... EQUIPMENT...
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
920 PM EDT WED AUG 7 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS FROM THE NORTHEAST THEN MOVE OFFSHORE OVER THE NEXT SEVERAL DAYS. AS THE RIDGE LOSES ITS GRIP ACROSS THE REGION THE WINDS WILL BECOME SOUTHERLY ALLOWING THE RETURN OF WARMER AND MORE HUMID AIR INTO THE CAROLINAS. A COLD FRONT WILL STALL NEAR OR JUST NORTH OF THE AREA MONDAY THROUGH WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 745 PM WEDNESDAY...LATEST IR SAT IMAGERY IE. THE 11-3.9 MICRON CHANNEL A FAVORITE AMONGST US FOR NIGHT-TIME SURVEILLANCE...INDICATES CLOUDINESS HAS THINNED OUT...ESPECIALLY ALONG AND EAST OF THE I-95 CORRIDOR. MODELS ARE ONCE AGAIN BEHIND THE 8-BALL IN TERMS OF SKY CONDITIONS THIS EVENING...AND LIKELY FOR THE OVERNIGHT PERIOD. THE W TO NW...DOWNSLOPE.. FLOW IN THE MID-UPPER LEVELS HAS BEEN A STRONGER PLAYER IN THE SCOURING OF THE CLOUDINESS ACROSS THE ILM CWA THEN POSSIBLY WHAT THE MODELS TAKE INTO ACCOUNT. WILL THEREFORE LEAN TOWARD A MORE OPTIMISTIC SKY CONDITION FOR THE OVERNITE. THE FLY IN THE OINTMENT WILL BE ALONG THE IMMEDIATE COAST...WHERE RENEGADE LOW CLOUDS COULD BRIEFLY MOVE ONSHORE. HAVE CONTINUED WITH CURRENT THINKING WITH REGARDS TO KEEPING POPS OVER THE ADJACENT ATL WATERS...WITH NO ONSHORE MOVEMENT. MIN TEMP FORECAST ALREADY ON THE LOW SIDE OF GUIDANCE. GIVEN THE DECREASE IN THE AMOUNT OF CLOUDS AND NEARLY CALM WINDS...SEE NO REASON TO DETOUR FROM THIS LOW TEMP FCST. PREVIOUS DISCUSSION............................................. AS OF 2 PM WEDNESDAY...HIGH PRESSURE CONTINUES TO WEDGE IN FROM THE NORTHEAST AND MID-LEVEL CLOUD COVER CONTINUES MAINLY WEST OF INTERSTATE 95. THE HIGH RESOLUTION NUMERICAL MODELS ARE HAVING A DIFFICULT TIME OF PRODUCING ANY CONVECTION AND THE 15 UTC HRRR IS SHOWING ISOLATED CONVECTION AT 17 UTC BUT IT IS SHORT LIVED AND MAINLY WEST OF A ELIZABETHTOWN TO ANDREWS LINE. CURRENT RADAR IS SHOWING ONE POSSIBLE CONVECTIVE ELEMENT OVER CHESTERFIELD COUNTY. VISIBLE SATELLITE IS SOME ENHANCED CUMULUS FIELDS OVER FLORENCE AND WESTERN WILLIAMSBURG COUNTY. A INTERESTING CYCLONIC FEATURE HAS BEEN OBSERVED IN THE RADAR THE PAST HOUR OR SHOW. A FEW SHOWERS ARE WORKING THEIR WAY TOWARD THE COAST BUT ARE SLOWLY DISSIPATING AS THEY APPROACH COAST. TODAY WOULD BE A GOOD DAY FOR A LESS THAN 20% CHANCE. WILL CONTINUE TO MONITOR AND MAY UP IT TO A 20% CHANCE ALONG INTERSTATE 95 AND THE HORRY AND GEORGETOWN COAST ON THE NEXT UPDATE IF MORE SHOWERS CONTINUE. MOSTLY CLEAR SKIES ARE EXPECTED OVERNIGHT WITH TEMPERATURES RANGING FROM NEAR 70 INLAND TO MID 70S ALONG THE BEACH. AS MENTIONED IN LAST NIGHTS DISCUSSION WILL CONTINUE A MENTION OS SHOWERS/ISOLATED THUNDERSTORMS OVER THE COASTAL WATERS WITH THE SOUTHEAST FLOW. THEREFORE WILL STILL INCLUDE A 20 PERCENT POP FOR THE BEACHES AROUND SUNRISE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...THE ATMOSPHERE WILL BE TRANSITIONING BACK TO A MORE TYPICAL SUMMERTIME PATTERN WITH HIGH PRESSURE SETTING UP OFF THE COAST ALLOWING FOR THE RETURN OF MORE HUMID CONDITIONS. AN H5 SUBTROPICAL RIDGE WILL BECOME PINCHED FROM THE SOUTHEAST U.S. WESTWARD TO THE LOWER MS VALLEY AND TX...WITH A STRONG SHORTWAVE PUSHING ACROSS SOUTHEAST CANADA AND WESTWARD MOVING H5 TROFS OVER THE GULF OF MEXICO. DON/T THINK THE AIR-MASS WILL BECOME STRONGLY CAPPED ACROSS THE FORECAST AREA AND WITH SUFFICIENT INSTABILITY EXPECT WIDELY SCATTERED SHOWERS/TSTMS EACH DAY. THE SEA BREEZE FRONT WILL BE THE PRIMARY LIFTING MECHANISM...MORE-SO IN THE AFTERNOON AND EARLY EVENING. MAX/MIN TEMPS WILL BE AT OR ABOVE CLIMO EACH PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 2 PM WEDNESDAY...ELONGATED MID LEVEL RIDGE WILL START TO BREAK DOWN EARLY NEXT WEEK WITH LONGWAVE 5H TROUGH SETTING UP OVER THE EAST COAST BY THE END OF THE PERIOD. THE PERIOD WILL START OFF WARM AND RELATIVELY DRY...HIGHS IN THE LOW TO MID 90S AND LOWS IN THE LOW TO MID 70S WITH SLIGHT CHC TO LOW CHC POP. CONVECTION IS LIKELY TO BE DIURNAL IN NATURE AND ASSOCIATED WITH THE SEA BREEZE AND PIEDMONT TROUGH. BREAK DOWN OF THE RIDGE AND RETREATING BERMUDA HIGH ALLOWS A COLD FRONT TO DROP IN FROM THE NORTHWEST ON MON. MID LEVEL TROUGH AXIS NEVER MOVES OFF THE COAST AND THE FRONT ENDS UP LAYING PARALLEL TO THE STEERING FLOW. THIS WILL KEEP THE FRONT STALLED IN THE AREA THROUGH WED. ABUNDANT DEEP MOISTURE IN THE PRESENCE OF THE BOUNDARY...ALONG WITH OCCASIONAL SHORTWAVES PASSING OVERHEAD IN SOUTHEAST FLOW WILL ELEVATE POP CHANCES FOR SECOND HALF OF THE PERIOD. WILL KEEP POP IN CHC CAT BUT INCREASE TO 40-50 ALONG WITH LOWERING HIGHS. LOWS WILL LIKELY REMAIN IN THE LOW TO MID 70S AS COOLER AIR REMAINS TRAPPED NORTHWEST OF THE REGION AND CLOUD COVER WILL LINGER. THINK COVERAGE OF PRECIP WILL DECREASE OVERNIGHT BUT SHOWERS ARE LIKELY TO LINGER OVERNIGHT SO WILL MAINTAIN LOW CHC POP. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD WITH THE EXCEPTION OF MVFR/POSSIBLE IFR DUE TO FOG/LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS ON THURSDAY. LIGHT WINDS AND FEW/SCT CLOUDS WILL CONTINUE INTO THE OVERNIGHT HOURS. GIVEN LATEST TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS...ANTICIPATE MVFR ALONG THE COAST AND POSSIBLE IFR/LIFR INLAND DUE TO FOG DEVELOPMENT AND LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS. AFTER DAYBREAK ON THURSDAY...CONDITIONS WILL IMPROVE TO VFR WITH LIGHT WINDS. AS HIGH PRESSURE SHIFTS ABOUT THE AREA...WINDS WILL BECOME SOUTHWEST BY THE AFTERNOON HOURS WITH SUSTAINED WINDS AOB 12 KTS...BECOMING LIGHT INTO THE EVENING HOURS...WITH MID AND HIGH CLOUDS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 815 PM WEDNESDAY...RIDGE AXIS EXTENDING SW FROM THE HIGHS CENTER WELL OFFSHORE FROM THE NE STATES...WILL REMAIN NORTH OF THE ILM COASTAL WATERS AS IT RIDGES INLAND. THIS WILL RESULT WITH ONSHORE SE WINDS CONTINUING ACROSS THE COASTAL WATERS OVERNIGHT. THE SFC PG WILL REMAIN RATHER LOOSE...PRODUCING AROUND 10 KT WIND SPEEDS. MODELS REMAIN SOMEWHAT DIFFERENT WITH REGARD TO THE HANDLING OF THE COASTAL TROF...MEANING ITS STRENGTH AND EVENTUAL MOVEMENT ACROSS THE WATERS DURING LATE TONIGHT AND INTO THE BEGINNING OF THE SHORT TERM PERIOD. FOR NOW...WILL CONTINUE TO MENTION ISOLATED PCPN ASSOCIATED WITH IT LATER TONIGHT. SIGNIFICANT SEAS WILL BE AROUND 2 FT...WITH 3 FOOTERS POSSIBLE FROM OFF CAPE FEAR NORTHWARD IN ASSOCIATION WITH THE COASTAL TROF. WIND DRIVEN WAVES WILL AGAIN DOMINATE SIGNIFICANT SEAS...WITH 2 SETS OF WIND WAVES AT 3 AND 5-6 SECOND PERIODS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...HIGH PRESSURE WILL PRESIDE OFFSHORE RESULTING IN SOUTHERLY FLOW ACROSS THE COASTAL WATERS DURING THE SHORT TERM PERIOD. THE PRESSURE GRADIENT WILL LIKELY SUPPORT WINDS IN THE 10-15 KT RANGE...WITH SOME ENHANCEMENT EACH DAY FROM THE SEA BREEZE CIRCULATION. SEAS WILL LIKELY AVERAGE 3 FT AWAY FROM THE COAST THURSDAY AND 3-4 FT BY FRIDAY AFTERNOON...WITH HIGHER FREQUENCY WAVES DOMINATING THE WAVE SPECTRUM. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 2 PM WEDNESDAY...BERMUDA HIGH AND PIEDMONT TROUGH WILL MAINTAIN SOUTH TO SOUTHWEST FLOW OVER THE WATERS THROUGH THE PERIOD. RELATIVELY WEAK GRADIENT WILL KEEP SPEEDS IN THE 10 TO 15 KT RANGE WITH HIGHEST VALUES IN THE AFTERNOON/EVENING. SPEEDS MAY INCREASE A LITTLE LATE IN THE PERIOD AS COLD FRONT DROPS IN FROM THE NORTHWEST AND PINCHES GRADIENT. SEAS OF 2 TO 4 FT WILL BE A COMBINATION OF DOMINANT SOUTHERLY WIND WAVE AND EAST TO SOUTHEAST SWELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SRP NEAR TERM...DCH/DRH SHORT TERM...SRP LONG TERM...III AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
857 PM EDT WED AUG 7 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS FROM THE NORTHEAST THEN MOVE OFFSHORE OVER THE NEXT SEVERAL DAYS. AS THE RIDGE LOSES ITS GRIP ACROSS THE REGION THE WINDS WILL BECOME SOUTHERLY ALLOWING THE RETURN OF WARMER AND MORE HUMID AIR INTO THE CAROLINAS. A COLD FRONT WILL STALL NEAR OR JUST NORTH OF THE AREA MONDAY THROUGH WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 745 PM WEDNESDAY...LATEST IR SAT IMAGERY IE. THE 11-3.9 MICRON CHANNEL A FAVORITE AMONGST US FOR NIGHT-TIME SURVEILLANCE...INDICATES CLOUDINESS HAS THINNED OUT...ESPECIALLY ALONG AND EAST OF THE I-95 CORRIDOR. MODELS ARE ONCE AGAIN BEHIND THE 8-BALL IN TERMS OF SKY CONDITIONS THIS EVENING...AND LIKELY FOR THE OVERNIGHT PERIOD. THE W TO NW...DOWNSLOPE.. FLOW IN THE MID-UPPER LEVELS HAS BEEN A STRONGER PLAYER IN THE SCOURING OF THE CLOUDINESS ACROSS THE ILM CWA THEN POSSIBLY WHAT THE MODELS TAKE INTO ACCOUNT. WILL THEREFORE LEAN TOWARD A MORE OPTIMISTIC SKY CONDITION FOR THE OVERNITE. THE FLY IN THE OINTMENT WILL BE ALONG THE IMMEDIATE COAST...WHERE RENEGADE LOW CLOUDS COULD BRIEFLY MOVE ONSHORE. HAVE CONTINUED WITH CURRENT THINKING WITH REGARDS TO KEEPING POPS OVER THE ADJACENT ATL WATERS...WITH NO ONSHORE MOVEMENT. MIN TEMP FORECAST ALREADY ON THE LOW SIDE OF GUIDANCE. GIVEN THE DECREASE IN THE AMOUNT OF CLOUDS AND NEARLY CALM WINDS...SEE NO REASON TO DETOUR FROM THIS LOW TEMP FCST. PREVIOUS DISCUSSION............................................... AS OF 2 PM WEDNESDAY...HIGH PRESSURE CONTINUES TO WEDGE IN FROM THE NORTHEAST AND MID-LEVEL CLOUD COVER CONTINUES MAINLY WEST OF INTERSTATE 95. THE HIGH RESOLUTION NUMERICAL MODELS ARE HAVING A DIFFICULT TIME OF PRODUCING ANY CONVECTION AND THE 15 UTC HRRR IS SHOWING ISOLATED CONVECTION AT 17 UTC BUT IT IS SHORT LIVED AND MAINLY WEST OF A ELIZABETHTOWN TO ANDREWS LINE. CURRENT RADAR IS SHOWING ONE POSSIBLE CONVECTIVE ELEMENT OVER CHESTERFIELD COUNTY. VISIBLE SATELLITE IS SOME ENHANCED CUMULUS FIELDS OVER FLORENCE AND WESTERN WILLIAMSBURG COUNTY. A INTERESTING CYCLONIC FEATURE HAS BEEN OBSERVED IN THE RADAR THE PAST HOUR OR SHOW. A FEW SHOWERS ARE WORKING THEIR WAY TOWARD THE COAST BUT ARE SLOWLY DISSIPATING AS THEY APPROACH COAST. TODAY WOULD BE A GOOD DAY FOR A LESS THAN 20% CHANCE. WILL CONTINUE TO MONITOR AND MAY UP IT TO A 20% CHANCE ALONG INTERSTATE 95 AND THE HORRY AND GEORGETOWN COAST ON THE NEXT UPDATE IF MORE SHOWERS CONTINUE. MOSTLY CLEAR SKIES ARE EXPECTED OVERNIGHT WITH TEMPERATURES RANGING FROM NEAR 70 INLAND TO MID 70S ALONG THE BEACH. AS MENTIONED IN LAST NIGHTS DISCUSSION WILL CONTINUE A MENTION OS SHOWERS/ISOLATED THUNDERSTORMS OVER THE COASTAL WATERS WITH THE SOUTHEAST FLOW. THEREFORE WILL STILL INCLUDE A 20 PERCENT POP FOR THE BEACHES AROUND SUNRISE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...THE ATMOSPHERE WILL BE TRANSITIONING BACK TO A MORE TYPICAL SUMMERTIME PATTERN WITH HIGH PRESSURE SETTING UP OFF THE COAST ALLOWING FOR THE RETURN OF MORE HUMID CONDITIONS. AN H5 SUBTROPICAL RIDGE WILL BECOME PINCHED FROM THE SOUTHEAST U.S. WESTWARD TO THE LOWER MS VALLEY AND TX...WITH A STRONG SHORTWAVE PUSHING ACROSS SOUTHEAST CANADA AND WESTWARD MOVING H5 TROFS OVER THE GULF OF MEXICO. DON/T THINK THE AIR-MASS WILL BECOME STRONGLY CAPPED ACROSS THE FORECAST AREA AND WITH SUFFICIENT INSTABILITY EXPECT WIDELY SCATTERED SHOWERS/TSTMS EACH DAY. THE SEA BREEZE FRONT WILL BE THE PRIMARY LIFTING MECHANISM...MORE-SO IN THE AFTERNOON AND EARLY EVENING. MAX/MIN TEMPS WILL BE AT OR ABOVE CLIMO EACH PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 2 PM WEDNESDAY...ELONGATED MID LEVEL RIDGE WILL START TO BREAK DOWN EARLY NEXT WEEK WITH LONGWAVE 5H TROUGH SETTING UP OVER THE EAST COAST BY THE END OF THE PERIOD. THE PERIOD WILL START OFF WARM AND RELATIVELY DRY...HIGHS IN THE LOW TO MID 90S AND LOWS IN THE LOW TO MID 70S WITH SLIGHT CHC TO LOW CHC POP. CONVECTION IS LIKELY TO BE DIURNAL IN NATURE AND ASSOCIATED WITH THE SEA BREEZE AND PIEDMONT TROUGH. BREAK DOWN OF THE RIDGE AND RETREATING BERMUDA HIGH ALLOWS A COLD FRONT TO DROP IN FROM THE NORTHWEST ON MON. MID LEVEL TROUGH AXIS NEVER MOVES OFF THE COAST AND THE FRONT ENDS UP LAYING PARALLEL TO THE STEERING FLOW. THIS WILL KEEP THE FRONT STALLED IN THE AREA THROUGH WED. ABUNDANT DEEP MOISTURE IN THE PRESENCE OF THE BOUNDARY...ALONG WITH OCCASIONAL SHORTWAVES PASSING OVERHEAD IN SOUTHEAST FLOW WILL ELEVATE POP CHANCES FOR SECOND HALF OF THE PERIOD. WILL KEEP POP IN CHC CAT BUT INCREASE TO 40-50 ALONG WITH LOWERING HIGHS. LOWS WILL LIKELY REMAIN IN THE LOW TO MID 70S AS COOLER AIR REMAINS TRAPPED NORTHWEST OF THE REGION AND CLOUD COVER WILL LINGER. THINK COVERAGE OF PRECIP WILL DECREASE OVERNIGHT BUT SHOWERS ARE LIKELY TO LINGER OVERNIGHT SO WILL MAINTAIN LOW CHC POP. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD WITH THE EXCEPTION OF MVFR/POSSIBLE IFR DUE TO FOG/LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS ON THURSDAY. LIGHT WINDS AND FEW/SCT CLOUDS WILL CONTINUE INTO THE OVERNIGHT HOURS. GIVEN LATEST TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS...ANTICIPATE MVFR ALONG THE COAST AND POSSIBLE IFR/LIFR INLAND DUE TO FOG DEVELOPMENT AND LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS. AFTER DAYBREAK ON THURSDAY...CONDITIONS WILL IMPROVE TO VFR WITH LIGHT WINDS. AS HIGH PRESSURE SHIFTS ABOUT THE AREA...WINDS WILL BECOME SOUTHWEST BY THE AFTERNOON HOURS WITH SUSTAINED WINDS AOB 12 KTS...BECOMING LIGHT INTO THE EVENING HOURS...WITH MID AND HIGH CLOUDS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM WEDNESDAY...WINDS ARE NOW LIGHT FROM THE EAST AT 10 KNOTS WITH SEAS RUNNING AROUND 2 FEET. WITH THE SOUTHEASTERLY FLOW THERE HAS BEEN A SLIGHT INCREASE IN SHOWERS OVER THE WATER AS A SMALL CYCLONIC FEATURE HAS BEEN OBSERVED ON RADAR THE PAST COUPLE OF HOURS. WILL INCLUDE A SLIGHT CHANCE OF SHOWERS AS THEY PUSH TOWARDS THE COAST. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...HIGH PRESSURE WILL PRESIDE OFFSHORE RESULTING IN SOUTHERLY FLOW ACROSS THE COASTAL WATERS DURING THE SHORT TERM PERIOD. THE PRESSURE GRADIENT WILL LIKELY SUPPORT WINDS IN THE 10-15 KT RANGE...WITH SOME ENHANCEMENT EACH DAY FROM THE SEA BREEZE CIRCULATION. SEAS WILL LIKELY AVERAGE 3 FT AWAY FROM THE COAST THURSDAY AND 3-4 FT BY FRIDAY AFTERNOON...WITH HIGHER FREQUENCY WAVES DOMINATING THE WAVE SPECTRUM. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 2 PM WEDNESDAY...BERMUDA HIGH AND PIEDMONT TROUGH WILL MAINTAIN SOUTH TO SOUTHWEST FLOW OVER THE WATERS THROUGH THE PERIOD. RELATIVELY WEAK GRADIENT WILL KEEP SPEEDS IN THE 10 TO 15 KT RANGE WITH HIGHEST VALUES IN THE AFTERNOON/EVENING. SPEEDS MAY INCREASE A LITTLE LATE IN THE PERIOD AS COLD FRONT DROPS IN FROM THE NORTHWEST AND PINCHES GRADIENT. SEAS OF 2 TO 4 FT WILL BE A COMBINATION OF DOMINANT SOUTHERLY WIND WAVE AND EAST TO SOUTHEAST SWELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...DCH/DRH SHORT TERM...SRP LONG TERM...III AVIATION...SGL MARINE...
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
753 PM EDT WED AUG 7 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS FROM THE NORTHEAST THEN MOVE OFFSHORE OVER THE NEXT SEVERAL DAYS. AS THE RIDGE LOSES ITS GRIP ACROSS THE REGION THE WINDS WILL BECOME SOUTHERLY ALLOWING THE RETURN OF WARMER AND MORE HUMID AIR INTO THE CAROLINAS. A COLD FRONT WILL STALL NEAR OR JUST NORTH OF THE AREA MONDAY THROUGH WEDNESDAY. && .NEAR TERM /THROUGH THURSDAY/... AS OF 2 PM WEDNESDAY...HIGH PRESSURE CONTINUES TO WEDGE IN FROM THE NORTHEAST AND MID-LEVEL CLOUD COVER CONTINUES MAINLY WEST OF INTERSTATE 95. THE HIGH RESOLUTION NUMERICAL MODELS ARE HAVING A DIFFICULT TIME OF PRODUCING ANY CONVECTION AND THE 15 UTC HRRR IS SHOWING ISOLATED CONVECTION AT 17 UTC BUT IT IS SHORT LIVED AND MAINLY WEST OF A ELIZABETHTOWN TO ANDREWS LINE. CURRENT RADAR IS SHOWING ONE POSSIBLE CONVECTIVE ELEMENT OVER CHESTERFIELD COUNTY. VISIBLE SATELLITE IS SOME ENHANCED CUMULUS FIELDS OVER FLORENCE AND WESTERN WILLIAMSBURG COUNTY. A INTERESTING CYCLONIC FEATURE HAS BEEN OBSERVED IN THE RADAR THE PAST HOUR OR SHOW. A FEW SHOWERS ARE WORKING THEIR WAY TOWARD THE COAST BUT ARE SLOWLY DISSIPATING AS THEY APPROACH COAST. TODAY WOULD BE A GOOD DAY FOR A LESS THAN 20% CHANCE. WILL CONTINUE TO MONITOR AND MAY UP IT TO A 20% CHANCE ALONG INTERSTATE 95 AND THE HORRY AND GEORGETOWN COAST ON THE NEXT UPDATE IF MORE SHOWERS CONTINUE. MOSTLY CLEAR SKIES ARE EXPECTED OVERNIGHT WITH TEMPERATURES RANGING FROM NEAR 70 INLAND TO MID 70S ALONG THE BEACH. AS MENTIONED IN LAST NIGHTS DISCUSSION WILL CONTINUE A MENTION OS SHOWERS/ISOLATED THUNDERSTORMS OVER THE COASTAL WATERS WITH THE SOUTHEAST FLOW. THEREFORE WILL STILL INCLUDE A 20 PERCENT POP FOR THE BEACHES AROUND SUNRISE. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...THE ATMOSPHERE WILL BE TRANSITIONING BACK TO A MORE TYPICAL SUMMERTIME PATTERN WITH HIGH PRESSURE SETTING UP OFF THE COAST ALLOWING FOR THE RETURN OF MORE HUMID CONDITIONS. AN H5 SUBTROPICAL RIDGE WILL BECOME PINCHED FROM THE SOUTHEAST U.S. WESTWARD TO THE LOWER MS VALLEY AND TX...WITH A STRONG SHORTWAVE PUSHING ACROSS SOUTHEAST CANADA AND WESTWARD MOVING H5 TROFS OVER THE GULF OF MEXICO. DON/T THINK THE AIR-MASS WILL BECOME STRONGLY CAPPED ACROSS THE FORECAST AREA AND WITH SUFFICIENT INSTABILITY EXPECT WIDELY SCATTERED SHOWERS/TSTMS EACH DAY. THE SEA BREEZE FRONT WILL BE THE PRIMARY LIFTING MECHANISM...MORE-SO IN THE AFTERNOON AND EARLY EVENING. MAX/MIN TEMPS WILL BE AT OR ABOVE CLIMO EACH PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 2 PM WEDNESDAY...ELONGATED MID LEVEL RIDGE WILL START TO BREAK DOWN EARLY NEXT WEEK WITH LONGWAVE 5H TROUGH SETTING UP OVER THE EAST COAST BY THE END OF THE PERIOD. THE PERIOD WILL START OFF WARM AND RELATIVELY DRY...HIGHS IN THE LOW TO MID 90S AND LOWS IN THE LOW TO MID 70S WITH SLIGHT CHC TO LOW CHC POP. CONVECTION IS LIKELY TO BE DIURNAL IN NATURE AND ASSOCIATED WITH THE SEA BREEZE AND PIEDMONT TROUGH. BREAK DOWN OF THE RIDGE AND RETREATING BERMUDA HIGH ALLOWS A COLD FRONT TO DROP IN FROM THE NORTHWEST ON MON. MID LEVEL TROUGH AXIS NEVER MOVES OFF THE COAST AND THE FRONT ENDS UP LAYING PARALLEL TO THE STEERING FLOW. THIS WILL KEEP THE FRONT STALLED IN THE AREA THROUGH WED. ABUNDANT DEEP MOISTURE IN THE PRESENCE OF THE BOUNDARY...ALONG WITH OCCASIONAL SHORTWAVES PASSING OVERHEAD IN SOUTHEAST FLOW WILL ELEVATE POP CHANCES FOR SECOND HALF OF THE PERIOD. WILL KEEP POP IN CHC CAT BUT INCREASE TO 40-50 ALONG WITH LOWERING HIGHS. LOWS WILL LIKELY REMAIN IN THE LOW TO MID 70S AS COOLER AIR REMAINS TRAPPED NORTHWEST OF THE REGION AND CLOUD COVER WILL LINGER. THINK COVERAGE OF PRECIP WILL DECREASE OVERNIGHT BUT SHOWERS ARE LIKELY TO LINGER OVERNIGHT SO WILL MAINTAIN LOW CHC POP. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD WITH THE EXCEPTION OF MVFR/POSSIBLE IFR DUE TO FOG/LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS ON THURSDAY. LIGHT WINDS AND FEW/SCT CLOUDS WILL CONTINUE INTO THE OVERNIGHT HOURS. GIVEN LATEST TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS...ANTICIPATE MVFR ALONG THE COAST AND POSSIBLE IFR/LIFR INLAND DUE TO FOG DEVELOPMENT AND LOW CIGS LATE OVERNIGHT INTO THE EARLY MORNING HOURS. AFTER DAYBREAK ON THURSDAY...CONDITIONS WILL IMPROVE TO VFR WITH LIGHT WINDS. AS HIGH PRESSURE SHIFTS ABOUT THE AREA...WINDS WILL BECOME SOUTHWEST BY THE AFTERNOON HOURS WITH SUSTAINED WINDS AOB 12 KTS...BECOMING LIGHT INTO THE EVENING HOURS...WITH MID AND HIGH CLOUDS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM WEDNESDAY...WINDS ARE NOW LIGHT FROM THE EAST AT 10 KNOTS WITH SEAS RUNNING AROUND 2 FEET. WITH THE SOUTHEASTERLY FLOW THERE HAS BEEN A SLIGHT INCREASE IN SHOWERS OVER THE WATER AS A SMALL CYCLONIC FEATURE HAS BEEN OBSERVED ON RADAR THE PAST COUPLE OF HOURS. WILL INCLUDE A SLIGHT CHANCE OF SHOWERS AS THEY PUSH TOWARDS THE COAST. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 2 PM WEDNESDAY...HIGH PRESSURE WILL PRESIDE OFFSHORE RESULTING IN SOUTHERLY FLOW ACROSS THE COASTAL WATERS DURING THE SHORT TERM PERIOD. THE PRESSURE GRADIENT WILL LIKELY SUPPORT WINDS IN THE 10-15 KT RANGE...WITH SOME ENHANCEMENT EACH DAY FROM THE SEA BREEZE CIRCULATION. SEAS WILL LIKELY AVERAGE 3 FT AWAY FROM THE COAST THURSDAY AND 3-4 FT BY FRIDAY AFTERNOON...WITH HIGHER FREQUENCY WAVES DOMINATING THE WAVE SPECTRUM. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 2 PM WEDNESDAY...BERMUDA HIGH AND PIEDMONT TROUGH WILL MAINTAIN SOUTH TO SOUTHWEST FLOW OVER THE WATERS THROUGH THE PERIOD. RELATIVELY WEAK GRADIENT WILL KEEP SPEEDS IN THE 10 TO 15 KT RANGE WITH HIGHEST VALUES IN THE AFTERNOON/EVENING. SPEEDS MAY INCREASE A LITTLE LATE IN THE PERIOD AS COLD FRONT DROPS IN FROM THE NORTHWEST AND PINCHES GRADIENT. SEAS OF 2 TO 4 FT WILL BE A COMBINATION OF DOMINANT SOUTHERLY WIND WAVE AND EAST TO SOUTHEAST SWELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DRH SHORT TERM...SRP LONG TERM...III AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
122 PM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL MOVE FARTHER OUT TO SEA THIS WEEK...BUT A RIDGE AXIS WILL REMAIN ACROSS NORTH CAROLINA THROUGH WEDNESDAY. AS WINDS GRADUALLY TURN MORE SOUTHERLY HEAT AND HUMIDITY WILL RETURN LATE IN THE WEEK. A PIEDMONT TROUGH WILL DEVELOP INLAND FRIDAY AND SATURDAY AHEAD OF A COLD FRONT THAT MAY APPROACH FROM THE NORTH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM TUESDAY...ANOTHER COOL DAY ON TAP ACROSS THE EASTERN CAROLINAS AS CANADIAN HIGH PRESSURE DRIFTING OFFSHORE THE MID-ATLANTIC CONTINUES ITS INFLUENCE OVER THE REGION. AN UPPER LEVEL IMPULSE MOVING THROUGH THE EASTERN CONUS LONGWAVE TROUGH MAY BRING SOME LIGHT RAIN SHOWERS TO THE AREA LATER THIS MORNING INTO THE AFTN. WEAKENING COLD FRONT HAS CRUISED TO JUST SOUTH OF THE FLORIDA-GEORGIA LINE...WITH CANADIAN HIGH PRESSURE KEEPING THE HEAT OF THE SUMMER AT BAY. TEMPS TODAY WILL STRUGGLE AGAIN TO SEVERAL DEGREES BELOW NORMAL FOR EARLY AUGUST...REACHING ONLY THE LOW 80S ACROSS THE NORTHERN TIER...MID/UPR 80S FAR SOUTH. WHILE WINDS WILL SLOWLY BECOME MORE S/SE TODAY AS HIGH PRESSURE RETREATS FURTHER OFFSHORE...THIS CONTINUES TO ADVECT VERY DRY AIR INTO THE CWA SINCE STREAMLINES SUGGEST CANADIAN AIR-MASS ORIGIN, AS NOTED BY PREVIOUS FORECASTER. THIS CONTINUED DRY AIR IS IMPORTANT TO NOTE...SINCE IT WILL HAVE CONSIDERABLE IMPACT ON PRECIP CHANCES THROUGH THIS EVE. AN UPPER IMPULSE NOTED ON WV IMAGERY IS PRODUCING AN AREA OF LIGHT TO MDT RAIN SHOWERS...CURRENTLY JUST WEST OF THE ILM CWA. THIS SHORTWAVE WILL MOVE NEARLY OVERHEAD THIS AFTN...EXITING OFFSHORE BY 4PM THIS EVE. FORECAST PROFILES SUGGEST INCREASING MID-LEVEL SATURATION FROM ELIZABETHTOWN...TO FLORENCE...AND POINTS WEST THIS AFTN...WHILE THE COASTAL REGION REMAINS QUITE DRY. THIS POINTS TO THE POTENTIAL FOR A PERIOD OF SHOWERS...FOCUSED MAINLY ACROSS THE WESTERN HALF OF THE CWA...WITH PRECIP ERODING SLOWLY AS THE SHORTWAVE TRAVERSES EASTWARD. THIS IS ALREADY EVIDENT ON REFLECTIVITY...SO INHERITED LOW-CHC ACROSS THE NW TIER REMAINS UNCHANGED...BUT DID EXPAND SCHC POP SE SLIGHTLY TO ACCOUNT FOR LATEST HRRR WHICH HAS PERFORMED WELL THIS MORNING. EVEN PLACES THAT DO NOT RECEIVE RAINFALL TODAY WILL SEE INCREASING MID LEVEL CLOUDINESS. TONIGHT...RENEWED DRYING WILL OCCUR WITHIN THE COLUMN...BRINGING AN END TO ANY PRECIP CHANCES FOR THE PERIOD. LIGHT SOUTHERLY WINDS WILL PERSIST HOWEVER...SO EVEN AS SKY CONDITIONS IMPROVE...RADIATIONAL COOLING WILL BE SOMEWHAT INHIBITED. MINS WILL BE A DEGREE OR TWO WARMER THAN LAST NIGHT...FALLING TO 70-73 AT THE COAST...67-70 INLAND. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF THE EAST COAST THROUGH THE PERIOD. COASTAL CAROLINAS WILL BASICALLY BE IN A DEEPER WARMER AND MOISTER RETURN FLOW ON THE WESTERN PERIPHERY OF THE ATLANTIC RIDGE BY THE END OF THE PERIOD. THE FLOW WILL SHIFT FROM SE ON WED TO S-SW BY FRI MORNING. ALTHOUGH DEWPOINT TEMPS WILL BE CREEPING BACK UP TOWARD 70 ON WED...THE ATMOSPHERIC COLUMN WILL REMAIN RELATIVELY DRY WITH PCP WATER VALUES AROUND 1.5 INCHES. LOOKS LIKE A MINOR PERTURBATION FROM THE WEST IN THE MID LEVEL FLOW WILL REACH THE COAST OVERNIGHT WED AND MAY SEE SOME CLOUDS AND AN ISOLATED SHOWER OR TWO MOVING ACROSS THE COASTAL WATERS AND POSSIBLY JUST ALONG THE COAST. OTHERWISE...EXPECT PLENTY OF SUNSHINE FOR WED. BY THURS A DEEPER SOUTHERLY FLOW WILL CONTINUE TO FEED MOISTURE INTO THE AREA BRINGING PCP WATER VALUES UP TO 1.75 INCHES...BUT MID TO UPPER RIDGE WILL NUDGE INTO THE AREA FROM THE EAST. OVERALL EXPECT CU BUILDUP IN THE AFTERNOON AND ONLY LOCALIZED CONVECTION MAINLY ALONG THE SEA BREEZE BOUNDARY WITH DRY AIR AND SUBSIDENCE ALOFT TO PREVENT MORE WIDESPREAD ACTIVITY. TEMPS WILL RUN SLIGHTLY BELOW NORMAL ON WED WITH MID 80S MOST PLACES AND WILL HEAD BACK TO NORMAL ON THURS WITH READINGS NEAR 70 FOR LOWS AND CLOSER TO 90 FOR HIGHS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...SOUTHERLY RETURN FLOW WILL PERSIST AROUND ATLANTIC HIGH PRESSURE AS MID TO UPPER RIDGE BUILDS OVER THE AREA FROM THE SOUTHEAST FRI INTO SAT. THE SOUTHERN EXTENT OF A COLD FRONT WILL REACH THE CAROLINAS BY SATURDAY BUT WILL END UP STALLING WITH PIEDMONT TROUGH INLAND AND SEA BREEZE BOUNDARY BEING THE MAIN FEATURES TO FOCUS ANY CONVECTION ON BOTH FRI AND SATURDAY. THE H5 RIDGE UP TO 595 DEM JUST OFF THE COAST FRI INTO EARLY SAT SHOULD PROVIDE ENOUGH SUBSIDENCE TO KEEP SHOWER ACTIVITY LIMITED TO MAINLY INLAND AREAS. BY SATURDAY THE RIDGE GETS SUPPRESSED FARTHER SOUTH AS MID TO UPPER TROUGH BEGINS TO DIG DOWN THE EAST COAST WITH SFC TROUGH/FRONT SHIFTING SOUTHEAST AND CLOSER TO THE COAST. BY LATE SUNDAY THROUGH TUESDAY...A MUCH DEEPER COLUMN OF MOISTURE WILL BE PRESENT WITH PCP WATER VALUES UP ABOVE 2 INCHES. OVERALL EXPECT INCREASING CHC OF MORE WIDESPREAD CONVECTION INTO EARLY NEXT WEEK WITH GREATER INSTABILITY AND MOISTURE IN THE ATMOSPHERE AS DECENT UPPER LEVEL SUPPORT. DEWPOINT TEMPS WILL BE BACK UP IN THE 70S WITH OVERNIGHT LOWS IN THE MID 70S AND DAY TIME HIGHS REACHING INTO THE 90S. CLOUDS AND PCP MAY KEEP VALUES SLIGHTLY LOWER EACH AFTERNOON INTO EARLY NEXT WEEK. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 18Z...STRATIFORM PRECIP LOOKS TO HANG IN THERE THROUGH MUCH OF THE AFTERNOON...AFFECTING MAINLY FLO AND LBT. VISIBILITIES WILL REMAIN VFR AS WELL AS CEILINGS IN THE PRECIP. MAINLY A MID CLOUD CEILING THROUGHOUT THE REGION THROUGH THE AFTERNOON HOURS WITH A VARIABLE WIND...STRONGEST...AND FROM THE SOUTHEAST...NEAR THE COAST. MUCH OF THE CLOUDS DISSIPATE THROUGH THE OVERNIGHT HOURS. SOME MVFR FOG IS POSSIBLE AT THE INLAND TERMINALS AS THE PRECIP THIS AFTERNOON SHOULD MOISTEN UP THE LOWER LAYERS JUST ENOUGH. WEDNESDAY...BECOMING VFR WITH MAINLY SCATTERED SKIES AND A CONTINUED SOUTHEAST WIND...MAINLY LESS THAN 10 KTS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SUNDAY. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 1015 AM TUESDAY...CANADIAN HIGH PRESSURE JUST OFF THE MID-ATLANTIC COAST WILL CONTINUE TO PUSH SLOWLY AWAY FROM SHORE THROUGH TONIGHT. WHILE THIS OCCURS...A RIDGE AXIS WILL CONTINUE TO EXTEND BACK TOWARDS THE EASTERN CAROLINAS...KEEPING THE PRESSURE GRADIENT LIGHT AND WINDS E/SE AT AROUND 10 KTS. SEAS AT THE LOCAL BUOYS ARE CURRENTLY ALL 2 FT OR LESS...AND THIS WILL PERSIST THROUGH THE PERIOD WITH LITTLE CHANGE. WAVES WILL BE FORMED BY A CONTINUED 4-SEC E/SE WIND CHOP AND 10 SEC SE GROUND SWELL. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...RETURN FLOW AROUND ATLANTIC RIDGE OF HIGH PRESSURE WILL PERSIST THROUGH THE PERIOD. THE FLOW WILL VEER AROUND FROM SOUTHEAST ON WED BECOMING MORE S-SW ON THURS. THE WINDS WILL REMAIN AROUND 10 KTS SPIKING UP A BIT EACH AFTERNOON IN THE SEA BREEZE. THE PERSISTENT ON SHORE PUSH WILL KEEP SEAS AROUND 2 TO 3 FT WITH SHORTER PERIOD WIND WAVES MIXING WITH A LONGER PERIOD 9 SECOND SE SWELL. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...EXPECT A SOUTH TO SOUTHWEST FLOW TO CONTINUE THROUGH THE PERIOD AROUND ATLANTIC HIGH. THE WINDS WILL VEER SLIGHTLY MORE INTO THE WEEKEND AS PIEDMONT TROUGH BECOMES MORE PRONOUNCED AND COLD FRONT MOVES INTO THE CAROLINAS FROM THE NORTHWEST OVER THE WEEKEND. THE GRADIENT WILL TIGHTEN BETWEEN INLAND TROUGH/FRONT AND HIGH PRESSURE OFF SHORE TO PRODUCE WIND 10 TO 15 KTS THROUGH THE PERIOD. THE INCREASED SOUTHERLY PUSH WILL PRODUCE A RISE IN SEAS UP CLOSER TO 3 FT THROUGH THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...JDW SHORT TERM...RGZ LONG TERM...RGZ AVIATION...43/17
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1017 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL MOVE FARTHER OUT TO SEA THIS WEEK...BUT A RIDGE AXIS WILL REMAIN ACROSS NORTH CAROLINA THROUGH WEDNESDAY. AS WINDS GRADUALLY TURN MORE SOUTHERLY HEAT AND HUMIDITY WILL RETURN LATE IN THE WEEK. A PIEDMONT TROUGH WILL DEVELOP INLAND FRIDAY AND SATURDAY AHEAD OF A COLD FRONT THAT MAY APPROACH FROM THE NORTH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM TUESDAY...ANOTHER COOL DAY ON TAP ACROSS THE EASTERN CAROLINAS AS CANADIAN HIGH PRESSURE DRIFTING OFFSHORE THE MID-ATLANTIC CONTINUES ITS INFLUENCE OVER THE REGION. AN UPPER LEVEL IMPULSE MOVING THROUGH THE EASTERN CONUS LONGWAVE TROUGH MAY BRING SOME LIGHT RAIN SHOWERS TO THE AREA LATER THIS MORNING INTO THE AFTN. WEAKENING COLD FRONT HAS CRUISED TO JUST SOUTH OF THE FLORIDA-GEORGIA LINE...WITH CANADIAN HIGH PRESSURE KEEPING THE HEAT OF THE SUMMER AT BAY. TEMPS TODAY WILL STRUGGLE AGAIN TO SEVERAL DEGREES BELOW NORMAL FOR EARLY AUGUST...REACHING ONLY THE LOW 80S ACROSS THE NORTHERN TIER...MID/UPR 80S FAR SOUTH. WHILE WINDS WILL SLOWLY BECOME MORE S/SE TODAY AS HIGH PRESSURE RETREATS FURTHER OFFSHORE...THIS CONTINUES TO ADVECT VERY DRY AIR INTO THE CWA SINCE STREAMLINES SUGGEST CANADIAN AIR-MASS ORIGIN, AS NOTED BY PREVIOUS FORECASTER. THIS CONTINUED DRY AIR IS IMPORTANT TO NOTE...SINCE IT WILL HAVE CONSIDERABLE IMPACT ON PRECIP CHANCES THROUGH THIS EVE. AN UPPER IMPULSE NOTED ON WV IMAGERY IS PRODUCING AN AREA OF LIGHT TO MDT RAIN SHOWERS...CURRENTLY JUST WEST OF THE ILM CWA. THIS SHORTWAVE WILL MOVE NEARLY OVERHEAD THIS AFTN...EXITING OFFSHORE BY 4PM THIS EVE. FORECAST PROFILES SUGGEST INCREASING MID-LEVEL SATURATION FROM ELIZABETHTOWN...TO FLORENCE...AND POINTS WEST THIS AFTN...WHILE THE COASTAL REGION REMAINS QUITE DRY. THIS POINTS TO THE POTENTIAL FOR A PERIOD OF SHOWERS...FOCUSED MAINLY ACROSS THE WESTERN HALF OF THE CWA...WITH PRECIP ERODING SLOWLY AS THE SHORTWAVE TRAVERSES EASTWARD. THIS IS ALREADY EVIDENT ON REFLECTIVITY...SO INHERITED LOW-CHC ACROSS THE NW TIER REMAINS UNCHANGED...BUT DID EXPAND SCHC POP SE SLIGHTLY TO ACCOUNT FOR LATEST HRRR WHICH HAS PERFORMED WELL THIS MORNING. EVEN PLACES THAT DO NOT RECEIVE RAINFALL TODAY WILL SEE INCREASING MID LEVEL CLOUDINESS. TONIGHT...RENEWED DRYING WILL OCCUR WITHIN THE COLUMN...BRINGING AN END TO ANY PRECIP CHANCES FOR THE PERIOD. LIGHT SOUTHERLY WINDS WILL PERSIST HOWEVER...SO EVEN AS SKY CONDITIONS IMPROVE...RADIATIONAL COOLING WILL BE SOMEWHAT INHIBITED. MINS WILL BE A DEGREE OR TWO WARMER THAN LAST NIGHT...FALLING TO 70-73 AT THE COAST...67-70 INLAND. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF THE EAST COAST THROUGH THE PERIOD. COASTAL CAROLINAS WILL BASICALLY BE IN A DEEPER WARMER AND MOISTER RETURN FLOW ON THE WESTERN PERIPHERY OF THE ATLANTIC RIDGE BY THE END OF THE PERIOD. THE FLOW WILL SHIFT FROM SE ON WED TO S-SW BY FRI MORNING. ALTHOUGH DEWPOINT TEMPS WILL BE CREEPING BACK UP TOWARD 70 ON WED...THE ATMOSPHERIC COLUMN WILL REMAIN RELATIVELY DRY WITH PCP WATER VALUES AROUND 1.5 INCHES. LOOKS LIKE A MINOR PERTURBATION FROM THE WEST IN THE MID LEVEL FLOW WILL REACH THE COAST OVERNIGHT WED AND MAY SEE SOME CLOUDS AND AN ISOLATED SHOWER OR TWO MOVING ACROSS THE COASTAL WATERS AND POSSIBLY JUST ALONG THE COAST. OTHERWISE...EXPECT PLENTY OF SUNSHINE FOR WED. BY THURS A DEEPER SOUTHERLY FLOW WILL CONTINUE TO FEED MOISTURE INTO THE AREA BRINGING PCP WATER VALUES UP TO 1.75 INCHES...BUT MID TO UPPER RIDGE WILL NUDGE INTO THE AREA FROM THE EAST. OVERALL EXPECT CU BUILDUP IN THE AFTERNOON AND ONLY LOCALIZED CONVECTION MAINLY ALONG THE SEA BREEZE BOUNDARY WITH DRY AIR AND SUBSIDENCE ALOFT TO PREVENT MORE WIDESPREAD ACTIVITY. TEMPS WILL RUN SLIGHTLY BELOW NORMAL ON WED WITH MID 80S MOST PLACES AND WILL HEAD BACK TO NORMAL ON THURS WITH READINGS NEAR 70 FOR LOWS AND CLOSER TO 90 FOR HIGHS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...SOUTHERLY RETURN FLOW WILL PERSIST AROUND ATLANTIC HIGH PRESSURE AS MID TO UPPER RIDGE BUILDS OVER THE AREA FROM THE SOUTHEAST FRI INTO SAT. THE SOUTHERN EXTENT OF A COLD FRONT WILL REACH THE CAROLINAS BY SATURDAY BUT WILL END UP STALLING WITH PIEDMONT TROUGH INLAND AND SEA BREEZE BOUNDARY BEING THE MAIN FEATURES TO FOCUS ANY CONVECTION ON BOTH FRI AND SATURDAY. THE H5 RIDGE UP TO 595 DEM JUST OFF THE COAST FRI INTO EARLY SAT SHOULD PROVIDE ENOUGH SUBSIDENCE TO KEEP SHOWER ACTIVITY LIMITED TO MAINLY INLAND AREAS. BY SATURDAY THE RIDGE GETS SUPPRESSED FARTHER SOUTH AS MID TO UPPER TROUGH BEGINS TO DIG DOWN THE EAST COAST WITH SFC TROUGH/FRONT SHIFTING SOUTHEAST AND CLOSER TO THE COAST. BY LATE SUNDAY THROUGH TUESDAY...A MUCH DEEPER COLUMN OF MOISTURE WILL BE PRESENT WITH PCP WATER VALUES UP ABOVE 2 INCHES. OVERALL EXPECT INCREASING CHC OF MORE WIDESPREAD CONVECTION INTO EARLY NEXT WEEK WITH GREATER INSTABILITY AND MOISTURE IN THE ATMOSPHERE AS DECENT UPPER LEVEL SUPPORT. DEWPOINT TEMPS WILL BE BACK UP IN THE 70S WITH OVERNIGHT LOWS IN THE MID 70S AND DAY TIME HIGHS REACHING INTO THE 90S. CLOUDS AND PCP MAY KEEP VALUES SLIGHTLY LOWER EACH AFTERNOON INTO EARLY NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...A COUPLE OF WEAK DISTURBANCES COMING OVER THE MOUNTAINS WILL GIVE THE NORTHWESTERN PORTION OF THE CWA A CHANCE FOR SHOWERS THROUGH THE MORNING HOURS. MUCH OF THE PRECIPITATION WILL COME OUT OF MID CLOUD AND WILL LIKELY STAY VIRGA. WILL KEEP VCSH IN THE LBT TAF...OTHERWISE PRECIP FREE FOR THE REMAINDER OF THE REGION. MAINLY A MID CLOUD CEILING THROUGHOUT THE REGION THROUGH THE AFTERNOON HOURS WITH A SOUTHEAST WIND...STRONGEST NEAR THE COAST. MUCH OF THE CLOUDS DISSIPATE THROUGH THE OVERNIGHT HOURS...BUT PROBABLY TOO DRY AT THE SURFACE TO ADD FOG. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 1015 AM TUESDAY...CANADIAN HIGH PRESSURE JUST OFF THE MID-ATLANTIC COAST WILL CONTINUE TO PUSH SLOWLY AWAY FROM SHORE THROUGH TONIGHT. WHILE THIS OCCURS...A RIDGE AXIS WILL CONTINUE TO EXTEND BACK TOWARDS THE EASTERN CAROLINAS...KEEPING THE PRESSURE GRADIENT LIGHT AND WINDS E/SE AT AROUND 10 KTS. SEAS AT THE LOCAL BUOYS ARE CURRENTLY ALL 2 FT OR LESS...AND THIS WILL PERSIST THROUGH THE PERIOD WITH LITTLE CHANGE. WAVES WILL BE FORMED BY A CONTINUED 4-SEC E/SE WIND CHOP AND 10 SEC SE GROUND SWELL. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...RETURN FLOW AROUND ATLANTIC RIDGE OF HIGH PRESSURE WILL PERSIST THROUGH THE PERIOD. THE FLOW WILL VEER AROUND FROM SOUTHEAST ON WED BECOMING MORE S-SW ON THURS. THE WINDS WILL REMAIN AROUND 10 KTS SPIKING UP A BIT EACH AFTERNOON IN THE SEA BREEZE. THE PERSISTENT ON SHORE PUSH WILL KEEP SEAS AROUND 2 TO 3 FT WITH SHORTER PERIOD WIND WAVES MIXING WITH A LONGER PERIOD 9 SECOND SE SWELL. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...EXPECT A SOUTH TO SOUTHWEST FLOW TO CONTINUE THROUGH THE PERIOD AROUND ATLANTIC HIGH. THE WINDS WILL VEER SLIGHTLY MORE INTO THE WEEKEND AS PIEDMONT TROUGH BECOMES MORE PRONOUNCED AND COLD FRONT MOVES INTO THE CAROLINAS FROM THE NORTHWEST OVER THE WEEKEND. THE GRADIENT WILL TIGHTEN BETWEEN INLAND TROUGH/FRONT AND HIGH PRESSURE OFF SHORE TO PRODUCE WIND 10 TO 15 KTS THROUGH THE PERIOD. THE INCREASED SOUTHERLY PUSH WILL PRODUCE A RISE IN SEAS UP CLOSER TO 3 FT THROUGH THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...JDW SHORT TERM...RGZ LONG TERM...RGZ AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
650 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL MOVE FARTHER OUT TO SEA THIS WEEK...BUT A RIDGE AXIS WILL REMAIN ACROSS NORTH CAROLINA THROUGH WEDNESDAY. AS WINDS GRADUALLY TURN MORE SOUTHERLY HEAT AND HUMIDITY WILL RETURN LATE IN THE WEEK. A PIEDMONT TROUGH WILL DEVELOP INLAND FRIDAY AND SATURDAY AHEAD OF A COLD FRONT THAT MAY APPROACH FROM THE NORTH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 645 AM TUESDAY...TWEAKS TO CLOUDS AND POPS ARE THE MAIN FOCUS OF THIS EARLY MORNING UPDATE...INCORPORATING THE LATEST HRRR MODEL WHICH SEEMS TO HAVE INITIALIZED FAIRLY WELL. MEASURABLE RAIN CHANCES ARE HIGHEST TODAY IN THE AREA FROM BENNETTSVILLE THROUGH LUMBERTON AND ELIZABETHTOWN. THE 00Z ECMWF MOS TEMPERATURES CAME IN VERY CLOSE TO MY FORECAST HIGHS SO NO SIGNIFICANT CHANGES ARE PLANNED THERE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... UNSEASONABLY DRY AIR AT THE SURFACE IS BEING PROVIDED BY EASTERLY FLOW AROUND HIGH PRESSURE CENTERED OFF THE MID-ATLANTIC COAST. ALTHOUGH AN EAST WIND IS NORMALLY QUITE HUMID... LOOKING BACK ALONG THE STREAMLINES REVEALS THIS AIR HAS CANADIAN ORIGINS JUST A FEW DAYS AGO. THE COLD FRONT THAT PUSHED ACROSS THE CAROLINAS TWO DAYS AGO IS STALLED NEAR THE GEORGIA/FLORIDA STATE LINE AND SHOULD WEAKEN TODAY. IN THE UPPER LEVELS A LONGWAVE TROUGH REMAINS ACROSS EASTERN NORTH AMERICA. THERE ARE MULTIPLE SHORTWAVES EMBEDDED WITHIN THE REGION OF CYCLONIC FLOW ALOFT. THE ONE EXPECTED TO HAVE THE MOST IMPACT ON OUR WEATHER TODAY IS CURRENTLY OVER THE SOUTHERN APPALACHIANS AND IS HELPING SUSTAIN SHOWERS AND T-STORMS EARLY THIS MORNING ACROSS THE WESTERN AND CENTRAL CAROLINAS. THERE ARE COMPETING FACTORS AT WORK REGARDING HOW HIGH PRECIPITATION CHANCES WILL BECOME HERE IN THE EASTERN CAROLINAS LATER TODAY. THE UPPER LEVEL DISTURBANCE WILL MOVE EAST OUT OF THE MOUNTAINS AND OVERHEAD BETWEEN 11AM AND 2 PM. THERE IS INCREASING MID LEVEL MOISTURE AND SOME COOLING ALOFT THAT WILL HELP ERODE THE MID-LEVEL CAPPING OBSERVED ON BOTH THE 00Z MHX AND CHS SOUNDINGS. NEGATIVE FACTORS WORKING AGAINST PRECIPITATION INCLUDE RESIDUAL DRY AIR BELOW 850 MB THAT WILL KEEP SURFACE-BASED INSTABILITY VERY LOW...AND A JET STREAK AT 200 MB CENTERED OVER OHIO AND WEST VIRGINIA WHICH PLACES THE CAROLINAS IN THE RIGHT-EXIT REGION...TYPICALLY ASSOCIATED WITH UPPER LEVEL CONVERGENCE AND LOWER-TROPOSPHERIC SINKING MOTION. THE COAST CERTAINLY WILL HAVE THE SMALLEST PRECIPITATION POTENTIAL TODAY GIVEN OVERWHELMING DRY AIR. I AM FORECASTING ONLY PERIODS OF CLOUDINESS TO PASS OVERHEAD HERE TODAY. ALONG THE INTERSTATE 95 CORRIDOR (BUT PARTICULARLY AROUND LUMBERTON) THERE ARE INCREASING CHANCES FOR SHOWERS FORECAST...MAINLY FROM MID MORNING THROUGH EARLY AFTERNOON AS THE UPPER DISTURBANCE CROSSES THE AREA. DESPITE WARMING TEMPERATURES IN THE AFTERNOON WITH SOME SUNSHINE...NVA AND INCREASED SUBSIDENT MOTION BEHIND THE SHORTWAVE SHOULD LEAD TO DIMINISHING RAIN CHANCES. THE 00Z GFS IS MUCH MORE BULLISH WITH RAIN CHANCES THAN THE 00Z NAM...AND WITH ITS ADDITIONAL RAINFALL THE GFS HAS MUCH COOLER TEMPERATURES FORECAST TODAY COMPARED TO THE NAM. GIVEN CURRENT RADAR RETURNS ALONG I-85 FROM CHARLOTTE THROUGH GREENSBORO THE GFS IS PROBABLY CORRECT WITH COVERAGE BUT MAY HAVE PLACED ITS QPF MAXIMUM TOO FAR SOUTH. MY FORECAST IS FOR 20-30 PERCENT COVERAGE OF SHOWERS ACROSS DARLINGTON-FLORENCE-DILLON-LUMBERTON-ELIZABETHTOWN...WITH ONLY A 5-10 PERCENT CHANCE AT THE COAST. HIGHS SHOULD RANGE FROM THE UPPER 80S FROM FLORENCE AND MARION INTO KINGSTREE...WITH MID 80S ELSEWHERE. ALTHOUGH AREAS OF MID LEVEL CLOUDINESS WILL HANG AROUND THROUGH TONIGHT PRECIPITATION CHANCES SHOULD BE TOO LOW FOR MENTION IN THE FORECAST. TEMPERATURES WILL MODERATE A LITTLE WITH THE CONTINUING ONSHORE FLOW...WITH LOWS IN THE UPPER 60S FORECAST INLAND AND LOWER 70S AT THE BEACHES. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF THE EAST COAST THROUGH THE PERIOD. COASTAL CAROLINAS WILL BASICALLY BE IN A DEEPER WARMER AND MOISTER RETURN FLOW ON THE WESTERN PERIPHERY OF THE ATLANTIC RIDGE BY THE END OF THE PERIOD. THE FLOW WILL SHIFT FROM SE ON WED TO S-SW BY FRI MORNING. ALTHOUGH DEWPOINT TEMPS WILL BE CREEPING BACK UP TOWARD 70 ON WED...THE ATMOSPHERIC COLUMN WILL REMAIN RELATIVELY DRY WITH PCP WATER VALUES AROUND 1.5 INCHES. LOOKS LIKE A MINOR PERTURBATION FROM THE WEST IN THE MID LEVEL FLOW WILL REACH THE COAST OVERNIGHT WED AND MAY SEE SOME CLOUDS AND AN ISOLATED SHOWER OR TWO MOVING ACROSS THE COASTAL WATERS AND POSSIBLY JUST ALONG THE COAST. OTHERWISE...EXPECT PLENTY OF SUNSHINE FOR WED. BY THURS A DEEPER SOUTHERLY FLOW WILL CONTINUE TO FEED MOISTURE INTO THE AREA BRINGING PCP WATER VALUES UP TO 1.75 INCHES...BUT MID TO UPPER RIDGE WILL NUDGE INTO THE AREA FROM THE EAST. OVERALL EXPECT CU BUILDUP IN THE AFTERNOON AND ONLY LOCALIZED CONVECTION MAINLY ALONG THE SEA BREEZE BOUNDARY WITH DRY AIR AND SUBSIDENCE ALOFT TO PREVENT MORE WIDESPREAD ACTIVITY. TEMPS WILL RUN SLIGHTLY BELOW NORMAL ON WED WITH MID 80S MOST PLACES AND WILL HEAD BACK TO NORMAL ON THURS WITH READINGS NEAR 70 FOR LOWS AND CLOSER TO 90 FOR HIGHS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...SOUTHERLY RETURN FLOW WILL PERSIST AROUND ATLANTIC HIGH PRESSURE AS MID TO UPPER RIDGE BUILDS OVER THE AREA FROM THE SOUTHEAST FRI INTO SAT. THE SOUTHERN EXTENT OF A COLD FRONT WILL REACH THE CAROLINAS BY SATURDAY BUT WILL END UP STALLING WITH PIEDMONT TROUGH INLAND AND SEA BREEZE BOUNDARY BEING THE MAIN FEATURES TO FOCUS ANY CONVECTION ON BOTH FRI AND SATURDAY. THE H5 RIDGE UP TO 595 DEM JUST OFF THE COAST FRI INTO EARLY SAT SHOULD PROVIDE ENOUGH SUBSIDENCE TO KEEP SHOWER ACTIVITY LIMITED TO MAINLY INLAND AREAS. BY SATURDAY THE RIDGE GETS SUPPRESSED FARTHER SOUTH AS MID TO UPPER TROUGH BEGINS TO DIG DOWN THE EAST COAST WITH SFC TROUGH/FRONT SHIFTING SOUTHEAST AND CLOSER TO THE COAST. BY LATE SUNDAY THROUGH TUESDAY...A MUCH DEEPER COLUMN OF MOISTURE WILL BE PRESENT WITH PCP WATER VALUES UP ABOVE 2 INCHES. OVERALL EXPECT INCREASING CHC OF MORE WIDESPREAD CONVECTION INTO EARLY NEXT WEEK WITH GREATER INSTABILITY AND MOISTURE IN THE ATMOSPHERE AS DECENT UPPER LEVEL SUPPORT. DEWPOINT TEMPS WILL BE BACK UP IN THE 70S WITH OVERNIGHT LOWS IN THE MID 70S AND DAY TIME HIGHS REACHING INTO THE 90S. CLOUDS AND PCP MAY KEEP VALUES SLIGHTLY LOWER EACH AFTERNOON INTO EARLY NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...A COUPLE OF WEAK DISTURBANCES COMING OVER THE MOUNTAINS WILL GIVE THE NORTHWESTERN PORTION OF THE CWA A CHANCE FOR SHOWERS THROUGH THE MORNING HOURS. MUCH OF THE PRECIPITATION WILL COME OUT OF MID CLOUD AND WILL LIKELY STAY VIRGA. WILL KEEP VCSH IN THE LBT TAF...OTHERWISE PRECIP FREE FOR THE REMAINDER OF THE REGION. MAINLY A MID CLOUD CEILING THROUGHOUT THE REGION THROUGH THE AFTERNOON HOURS WITH A SOUTHEAST WIND...STRONGEST NEAR THE COAST. MUCH OF THE CLOUDS DISSIPATE THROUGH THE OVERNIGHT HOURS...BUT PROBABLY TOO DRY AT THE SURFACE TO ADD FOG. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 630 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... CANADIAN HIGH PRESSURE CENTERED OFF THE NEW JERSEY COAST IS EXTENDING A SURFACE RIDGE AXIS SOUTHWESTWARD INTO EASTERN NORTH CAROLINA AND CENTRAL SOUTH CAROLINA. ALTHOUGH THE MAIN AREA OF HIGH PRESSURE WILL MOVE FARTHER OFFSHORE TONIGHT THE RIDGE AXIS WILL REMAIN IN PLACE. THIS SHOULD KEEP OUR WINDS FROM VEERING AROUND TO THE SOUTH AS NORMALLY OCCURS WITH A DEPARTING EAST COAST HIGH. EAST TO SOUTHEAST WINDS 10-15 KNOTS THIS MORNING WILL DIMINISH TO AROUND 10 KNOTS FOR THIS AFTERNOON AND TONIGHT. ALTHOUGH THERE WILL BE AN INCREASE IN CLOUD COVER THIS MORNING...IT APPEARS SHOWER CHANCES WILL REMAIN CONFINED TO INTERIOR SECTIONS OF THE CAROLINAS. SEAS CURRENTLY AVERAGE 2-3 FT AT THE BUOYS WITH SHORT WIND-DRIVEN PERIODS. LITTLE CHANGE IS FORECAST INTO TONIGHT. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...RETURN FLOW AROUND ATLANTIC RIDGE OF HIGH PRESSURE WILL PERSIST THROUGH THE PERIOD. THE FLOW WILL VEER AROUND FROM SOUTHEAST ON WED BECOMING MORE S-SW ON THURS. THE WINDS WILL REMAIN AROUND 10 KTS SPIKING UP A BIT EACH AFTERNOON IN THE SEA BREEZE. THE PERSISTENT ON SHORE PUSH WILL KEEP SEAS AROUND 2 TO 3 FT WITH SHORTER PERIOD WIND WAVES MIXING WITH A LONGER PERIOD 9 SECOND SE SWELL. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...EXPECT A SOUTH TO SOUTHWEST FLOW TO CONTINUE THROUGH THE PERIOD AROUND ATLANTIC HIGH. THE WINDS WILL VEER SLIGHTLY MORE INTO THE WEEKEND AS PIEDMONT TROUGH BECOMES MORE PRONOUNCED AND COLD FRONT MOVES INTO THE CAROLINAS FROM THE NORTHWEST OVER THE WEEKEND. THE GRADIENT WILL TIGHTEN BETWEEN INLAND TROUGH/FRONT AND HIGH PRESSURE OFF SHORE TO PRODUCE WIND 10 TO 15 KTS THROUGH THE PERIOD. THE INCREASED SOUTHERLY PUSH WILL PRODUCE A RISE IN SEAS UP CLOSER TO 3 FT THROUGH THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
641 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL MOVE FARTHER OUT TO SEA THIS WEEK...BUT A RIDGE AXIS WILL REMAIN ACROSS NORTH CAROLINA THROUGH WEDNESDAY. AS WINDS GRADUALLY TURN MORE SOUTHERLY HEAT AND HUMIDITY WILL RETURN LATE IN THE WEEK. A PIEDMONT TROUGH WILL DEVELOP INLAND FRIDAY AND SATURDAY AHEAD OF A COLD FRONT THAT MAY APPROACH FROM THE NORTH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 645 AM TUESDAY...TWEAKS TO CLOUDS AND POPS ARE THE MAIN FOCUS OF THIS EARLY MORNING UPDATE...INCORPORATING THE LATEST HRRR MODEL WHICH SEEMS TO HAVE INITIALIZED FAIRLY WELL. MEASURABLE RAIN CHANCES ARE HIGHEST TODAY IN THE AREA FROM BENNETTSVILLE THROUGH LUMBERTON AND ELIZABETHTOWN. THE 00Z ECMWF MOS TEMPERATURES CAME IN VERY CLOSE TO MY FORECAST HIGHS SO NO SIGNIFICANT CHANGES ARE PLANNED THERE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... UNSEASONABLY DRY AIR AT THE SURFACE IS BEING PROVIDED BY EASTERLY FLOW AROUND HIGH PRESSURE CENTERED OFF THE MID-ATLANTIC COAST. ALTHOUGH AN EAST WIND IS NORMALLY QUITE HUMID... LOOKING BACK ALONG THE STREAMLINES REVEALS THIS AIR HAS CANADIAN ORIGINS JUST A FEW DAYS AGO. THE COLD FRONT THAT PUSHED ACROSS THE CAROLINAS TWO DAYS AGO IS STALLED NEAR THE GEORGIA/FLORIDA STATE LINE AND SHOULD WEAKEN TODAY. IN THE UPPER LEVELS A LONGWAVE TROUGH REMAINS ACROSS EASTERN NORTH AMERICA. THERE ARE MULTIPLE SHORTWAVES EMBEDDED WITHIN THE REGION OF CYCLONIC FLOW ALOFT. THE ONE EXPECTED TO HAVE THE MOST IMPACT ON OUR WEATHER TODAY IS CURRENTLY OVER THE SOUTHERN APPALACHIANS AND IS HELPING SUSTAIN SHOWERS AND T-STORMS EARLY THIS MORNING ACROSS THE WESTERN AND CENTRAL CAROLINAS. THERE ARE COMPETING FACTORS AT WORK REGARDING HOW HIGH PRECIPITATION CHANCES WILL BECOME HERE IN THE EASTERN CAROLINAS LATER TODAY. THE UPPER LEVEL DISTURBANCE WILL MOVE EAST OUT OF THE MOUNTAINS AND OVERHEAD BETWEEN 11AM AND 2 PM. THERE IS INCREASING MID LEVEL MOISTURE AND SOME COOLING ALOFT THAT WILL HELP ERODE THE MID-LEVEL CAPPING OBSERVED ON BOTH THE 00Z MHX AND CHS SOUNDINGS. NEGATIVE FACTORS WORKING AGAINST PRECIPITATION INCLUDE RESIDUAL DRY AIR BELOW 850 MB THAT WILL KEEP SURFACE-BASED INSTABILITY VERY LOW...AND A JET STREAK AT 200 MB CENTERED OVER OHIO AND WEST VIRGINIA WHICH PLACES THE CAROLINAS IN THE RIGHT-EXIT REGION...TYPICALLY ASSOCIATED WITH UPPER LEVEL CONVERGENCE AND LOWER-TROPOSPHERIC SINKING MOTION. THE COAST CERTAINLY WILL HAVE THE SMALLEST PRECIPITATION POTENTIAL TODAY GIVEN OVERWHELMING DRY AIR. I AM FORECASTING ONLY PERIODS OF CLOUDINESS TO PASS OVERHEAD HERE TODAY. ALONG THE INTERSTATE 95 CORRIDOR (BUT PARTICULARLY AROUND LUMBERTON) THERE ARE INCREASING CHANCES FOR SHOWERS FORECAST...MAINLY FROM MID MORNING THROUGH EARLY AFTERNOON AS THE UPPER DISTURBANCE CROSSES THE AREA. DESPITE WARMING TEMPERATURES IN THE AFTERNOON WITH SOME SUNSHINE...NVA AND INCREASED SUBSIDENT MOTION BEHIND THE SHORTWAVE SHOULD LEAD TO DIMINISHING RAIN CHANCES. THE 00Z GFS IS MUCH MORE BULLISH WITH RAIN CHANCES THAN THE 00Z NAM...AND WITH ITS ADDITIONAL RAINFALL THE GFS HAS MUCH COOLER TEMPERATURES FORECAST TODAY COMPARED TO THE NAM. GIVEN CURRENT RADAR RETURNS ALONG I-85 FROM CHARLOTTE THROUGH GREENSBORO THE GFS IS PROBABLY CORRECT WITH COVERAGE BUT MAY HAVE PLACED ITS QPF MAXIMUM TOO FAR SOUTH. MY FORECAST IS FOR 20-30 PERCENT COVERAGE OF SHOWERS ACROSS DARLINGTON-FLORENCE-DILLON-LUMBERTON-ELIZABETHTOWN...WITH ONLY A 5-10 PERCENT CHANCE AT THE COAST. HIGHS SHOULD RANGE FROM THE UPPER 80S FROM FLORENCE AND MARION INTO KINGSTREE...WITH MID 80S ELSEWHERE. ALTHOUGH AREAS OF MID LEVEL CLOUDINESS WILL HANG AROUND THROUGH TONIGHT PRECIPITATION CHANCES SHOULD BE TOO LOW FOR MENTION IN THE FORECAST. TEMPERATURES WILL MODERATE A LITTLE WITH THE CONTINUING ONSHORE FLOW...WITH LOWS IN THE UPPER 60S FORECAST INLAND AND LOWER 70S AT THE BEACHES. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF THE EAST COAST THROUGH THE PERIOD. COASTAL CAROLINAS WILL BASICALLY BE IN A DEEPER WARMER AND MOISTER RETURN FLOW ON THE WESTERN PERIPHERY OF THE ATLANTIC RIDGE BY THE END OF THE PERIOD. THE FLOW WILL SHIFT FROM SE ON WED TO S-SW BY FRI MORNING. ALTHOUGH DEWPOINT TEMPS WILL BE CREEPING BACK UP TOWARD 70 ON WED...THE ATMOSPHERIC COLUMN WILL REMAIN RELATIVELY DRY WITH PCP WATER VALUES AROUND 1.5 INCHES. LOOKS LIKE A MINOR PERTURBATION FROM THE WEST IN THE MID LEVEL FLOW WILL REACH THE COAST OVERNIGHT WED AND MAY SEE SOME CLOUDS AND AN ISOLATED SHOWER OR TWO MOVING ACROSS THE COASTAL WATERS AND POSSIBLY JUST ALONG THE COAST. OTHERWISE...EXPECT PLENTY OF SUNSHINE FOR WED. BY THURS A DEEPER SOUTHERLY FLOW WILL CONTINUE TO FEED MOISTURE INTO THE AREA BRINGING PCP WATER VALUES UP TO 1.75 INCHES...BUT MID TO UPPER RIDGE WILL NUDGE INTO THE AREA FROM THE EAST. OVERALL EXPECT CU BUILDUP IN THE AFTERNOON AND ONLY LOCALIZED CONVECTION MAINLY ALONG THE SEA BREEZE BOUNDARY WITH DRY AIR AND SUBSIDENCE ALOFT TO PREVENT MORE WIDESPREAD ACTIVITY. TEMPS WILL RUN SLIGHTLY BELOW NORMAL ON WED WITH MID 80S MOST PLACES AND WILL HEAD BACK TO NORMAL ON THURS WITH READINGS NEAR 70 FOR LOWS AND CLOSER TO 90 FOR HIGHS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...SOUTHERLY RETURN FLOW WILL PERSIST AROUND ATLANTIC HIGH PRESSURE AS MID TO UPPER RIDGE BUILDS OVER THE AREA FROM THE SOUTHEAST FRI INTO SAT. THE SOUTHERN EXTENT OF A COLD FRONT WILL REACH THE CAROLINAS BY SATURDAY BUT WILL END UP STALLING WITH PIEDMONT TROUGH INLAND AND SEA BREEZE BOUNDARY BEING THE MAIN FEATURES TO FOCUS ANY CONVECTION ON BOTH FRI AND SATURDAY. THE H5 RIDGE UP TO 595 DEM JUST OFF THE COAST FRI INTO EARLY SAT SHOULD PROVIDE ENOUGH SUBSIDENCE TO KEEP SHOWER ACTIVITY LIMITED TO MAINLY INLAND AREAS. BY SATURDAY THE RIDGE GETS SUPPRESSED FARTHER SOUTH AS MID TO UPPER TROUGH BEGINS TO DIG DOWN THE EAST COAST WITH SFC TROUGH/FRONT SHIFTING SOUTHEAST AND CLOSER TO THE COAST. BY LATE SUNDAY THROUGH TUESDAY...A MUCH DEEPER COLUMN OF MOISTURE WILL BE PRESENT WITH PCP WATER VALUES UP ABOVE 2 INCHES. OVERALL EXPECT INCREASING CHC OF MORE WIDESPREAD CONVECTION INTO EARLY NEXT WEEK WITH GREATER INSTABILITY AND MOISTURE IN THE ATMOSPHERE AS DECENT UPPER LEVEL SUPPORT. DEWPOINT TEMPS WILL BE BACK UP IN THE 70S WITH OVERNIGHT LOWS IN THE MID 70S AND DAY TIME HIGHS REACHING INTO THE 90S. CLOUDS AND PCP MAY KEEP VALUES SLIGHTLY LOWER EACH AFTERNOON INTO EARLY NEXT WEEK. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 06Z...EXPECT VFR TO CONTINUE THROUGH THE VALID PERIOD. FEW/SCT MID TO HIGH CLOUDS WILL CONTINUE TO LINGER ACROSS THE AREA WITH LIGHT AND VARIABLE WINDS THROUGH THE MORNING HOURS. LATEST COMPUTER MODELS ARE NOT SUPPORTING FOG DEVELOPMENT...BUT COULD NOT ENTIRELY RULE OUT ISOLATED AREAS OF GROUND FOG...ESPECIALLY INLAND. AFTER DAYBREAK...VFR WILL PREVAIL WITH COVERAGE IN MID TO HIGH CLOUDS INCREASING. LIGHT SOUTH-SOUTHEAST WINDS IN THE MORNING WILL INCREASE TO 10 KTS THROUGH THE AFTERNOON HOURS. ISOLATED SHOWERS AND TSTMS COULD DEVELOP ACROSS THE CENTRAL CAROLINAS...POTENTIALLY MOVING AS FAR EAST AS THE FLO/LBT AIRPORTS IN THE 20-23Z TIMEFRAME BUT CONFIDENCE IS TOO LOW FOR INCLUSION IN THE FORECAST AT THIS TIME. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE WEDNESDAY THROUGH SATURDAY. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 630 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... CANADIAN HIGH PRESSURE CENTERED OFF THE NEW JERSEY COAST IS EXTENDING A SURFACE RIDGE AXIS SOUTHWESTWARD INTO EASTERN NORTH CAROLINA AND CENTRAL SOUTH CAROLINA. ALTHOUGH THE MAIN AREA OF HIGH PRESSURE WILL MOVE FARTHER OFFSHORE TONIGHT THE RIDGE AXIS WILL REMAIN IN PLACE. THIS SHOULD KEEP OUR WINDS FROM VEERING AROUND TO THE SOUTH AS NORMALLY OCCURS WITH A DEPARTING EAST COAST HIGH. EAST TO SOUTHEAST WINDS 10-15 KNOTS THIS MORNING WILL DIMINISH TO AROUND 10 KNOTS FOR THIS AFTERNOON AND TONIGHT. ALTHOUGH THERE WILL BE AN INCREASE IN CLOUD COVER THIS MORNING...IT APPEARS SHOWER CHANCES WILL REMAIN CONFINED TO INTERIOR SECTIONS OF THE CAROLINAS. SEAS CURRENTLY AVERAGE 2-3 FT AT THE BUOYS WITH SHORT WIND-DRIVEN PERIODS. LITTLE CHANGE IS FORECAST INTO TONIGHT. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...RETURN FLOW AROUND ATLANTIC RIDGE OF HIGH PRESSURE WILL PERSIST THROUGH THE PERIOD. THE FLOW WILL VEER AROUND FROM SOUTHEAST ON WED BECOMING MORE S-SW ON THURS. THE WINDS WILL REMAIN AROUND 10 KTS SPIKING UP A BIT EACH AFTERNOON IN THE SEA BREEZE. THE PERSISTENT ON SHORE PUSH WILL KEEP SEAS AROUND 2 TO 3 FT WITH SHORTER PERIOD WIND WAVES MIXING WITH A LONGER PERIOD 9 SECOND SE SWELL. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...EXPECT A SOUTH TO SOUTHWEST FLOW TO CONTINUE THROUGH THE PERIOD AROUND ATLANTIC HIGH. THE WINDS WILL VEER SLIGHTLY MORE INTO THE WEEKEND AS PIEDMONT TROUGH BECOMES MORE PRONOUNCED AND COLD FRONT MOVES INTO THE CAROLINAS FROM THE NORTHWEST OVER THE WEEKEND. THE GRADIENT WILL TIGHTEN BETWEEN INLAND TROUGH/FRONT AND HIGH PRESSURE OFF SHORE TO PRODUCE WIND 10 TO 15 KTS THROUGH THE PERIOD. THE INCREASED SOUTHERLY PUSH WILL PRODUCE A RISE IN SEAS UP CLOSER TO 3 FT THROUGH THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...TRA/SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT FURTHER OFFSHORE THIS MORNING...GIVING WAY TO A MOIST...SOUTHERLY LOW LEVEL RETURN FLOW THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 240 AM TUESDAY... HIGH PRESSURE CENTERED OFF THE MID-ATLANTIC COAST THIS MORNING EXTENDS SOUTHWEST OVER EASTERN NC/SC...WHILE A A RELATIVELY FAST NORTHWESTERLY FLOW CONTINUES ALOFT. SOUTHEASTERLY RETURN FLOW AROUND THE HIGH PRESSURE HAS BEEN CREATING SOME WEAK WARM ADVECTION AND UPSLOPE FLOW...SUPPORTING THE DEVELOPMENT OF SCATTERED SHOWERS OVER THE FOOTHILLS AND WESTERN PIEDMONT. HOWEVER... THE PRECIP HAS STRUGGLED TO MOVE EAST ACROSS THE PIEDMONT ONCE IT MOVES OUT OF THE BETTER LOW-LEVEL MOIST AXIS OVER WESTERN NC. RAP AND WATER VAPOR IMAGERY SUGGEST A FEW WEAK DISTURBANCES ALOFT WILL DRIFT OVERHEAD TODAY...WHICH MAY AID PRECIP IN MOVING FURTHER EAST ACROSS THE PIEDMONT...BUT INSTABILITY WILL BE WEAK AND POPS WILL STILL BE GRADUATED FROM CHANCE IN THE WEST TO SLIGHT CHANCE IN THE EAST. SKIES WILL ALSO BE MORE CLOUDY OVER THE WESTERN CWA...WHERE FORECAST SOUNDINGS SHOW A SOLID LAYER OF MOISTURE BETWEEN 850-700MB. LOW-LEVEL THICKNESSES ARE ONLY SLIGHTLY HIGHER THAN THOSE OBSERVED ON MONDAY OF AROUND 1400M. WITH PERIODS OF CLOUD COVER...HIGHS SHOULD AGAIN BE IN THE LOW TO MID 80S. TONIGHT... SIMILAR TO THIS MORNING...SCATTERED SHOWER WILL BE POSSIBLE OVER THE WESTERN CWA...WITH THE SHOWERS LIKELY TO WEAKEN AS THEY DRIFT EAST INTO A MORE HOSTILE ENVIRONMENT AND SURFACE HIGH PRESSURE RIDGE. LOWS IN THE UPPER 60S. && .SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 245 AM TUESDAY... WEDNESDAY AND WEDNESDAY NIGHT... HIGH PRESSURE RIDGING ALONG THE CAROLINA COAST WILL WEAKEN WEDNESDAY AS THE PARENT HIGH MOVES FURTHER OFF THE MID-ATLANTIC COAST AND COLD FRONT MOVES THROUGH THE MIDWEST STATES. INSTABILITY...WHILE SLIGHTLY GREATER THAN FORECAST FOR TODAY... WILL CONTINUE TO BE WEAK OVER CENTRAL NC DESPITE RISING PRECIP WATER. WEAK WARM ADVECTION AND UPSLOPE SHOULD STILL FAVOR SCATTERED SHOWERS AND ISOLATED STORMS OVER THE WESTERN PIEDMONT. WHILE HIGHS WILL STILL BE BELOW NORMAL...FORECAST SOUNDINGS SHOW A LITTLE LESS CLOUD COVER AND BETTER MIXING...WHICH SHOULD SUPPORT HIGHS A COUPLE DEGREES WARMER THAN TODAY...85-88. LOWS AROUND 70. -SMITH FOR THURSDAY/THURSDAY NIGHT: THE CANADIAN VORTEX DRIFTS SLOWLY EASTWARD TO CENTRAL ONTARIO THU/THU NIGHT AS WEAK MID LEVEL RIDGING PASSES OVER NC... INSTIGATING SUBTLE WARMING ALOFT (500-300 MB) WITH A VERY LIGHT WESTERLY MID LEVEL FLOW AND THE JET STREAM DISPLACED WELL TO OUR NORTH ACROSS THE NRN GREAT LAKES... LARGE SCALE FORCED ASCENT WILL BE LIMITED TO LOWER LEVEL MASS CONVERGENCE OVER THE NC MOUNTAINS/FOOTHILLS INTO VA... IN THE LOW LEVEL MOIST CONVEYOR ZONE WHERE PW VALUES WILL BE GREATEST (NEAR 2.0 INCHES). SREF PROBABILITIES OF MEASURABLE RAIN REACH 50-70% OVER THE NW HALF OF THE FORECAST AREA LATE THU MORNING THROUGH THE AFTERNOON... CORRESPONDING TO MODEL-INDICATED AREAS OF ENHANCED LOW LEVEL MOISTURE TRANSPORT ON THE PERIPHERY OF THE OFFSHORE SURFACE HIGH... WITH PROBABILITIES OF 10% OR LOWER IN THE EAST WHERE FORECAST SOUNDINGS SHOW SEVERAL LAYERS OF DRY AIR THROUGH THE COLUMN WITH MINIMAL INSTABILITY. WILL KEEP CHANCE POPS ACROSS THE WRN AND FAR NRN CWA... ON THE PERIPHERY OF THE RIDGE CORE... WITH ISOLATED POPS OVER MUCH OF THE EAST. THE NAM HINTS AT POTENTIAL SEA-BREEZE CONVECTION WORKING INTO THE EXTREME SE FORECAST AREA... SO WILL PUT A SECONDARY POP MAX (BUT STILL JUST SMALL COVERAGE) HERE. HIGHS 86-90. MODELS AGREE ON ANY PRECIP SHUTTING OFF NEAR SUNSET... AND EXPECT LARGELY DRY WEATHER OVERNIGHT BUT WITH MID CLOUDS MOVING IN (BLOWOFF CLOUDS FROM MORE ORGANIZED/WIDESPREAD CONVECTION OVER WV/KY/TN)... AND WE SHOULD SEE STRATUS/FOG FORMATION OVERNIGHT GIVEN THE LIGHT SOUTH/SW FLOW AND RISING LOW LEVEL MOISTURE. LOWS 69-73. FOR FRIDAY/FRIDAY NIGHT: THE CANADIAN VORTEX IS EXPECTED TO CONTINUE ITS EASTWARD WOBBLE ACROSS ONTARIO TO THE TIP OF JAMES BAY DURING THIS TIME FRAME. THE GFS HAS BEEN TRENDING SLOWER WITH THIS IN RECENT RUNS... AND AS A RESULT IT NOW DELAYS THE ARRIVAL OF THE GREATER COVERAGE OF CONVECTION WITHIN THE STREAM OF PREFRONTAL WARM AIR ADVECTION... AND KEEPS THE FAR ERN CWA MAINLY DRY THROUGH FRI NIGHT. THE GFS KEEPS THE UPPER LEVEL ANTICYCLONE CENTER OVER THE CAROLINAS... AND WITH THE SWRLY UPPER JET CORE CROSSING THE GREAT LAKES... THE BULK OF THE UPPER DIVERGENCE SKIRTS BY TO OUR NW AND NORTH. THE SLIGHTLY FASTER ECMWF IS A BIT MORE EMPHATIC WITH CONVECTION ACROSS CENTRAL NC ALONG THE LEE SURFACE TROUGH AS THE MID LEVEL TROUGH AXIS APPROACHES... A SOLUTION THAT CANNOT BE DISCOUNTED GIVEN THE EXPECTED MODERATE INSTABILITY (MLCAPE NEAR 1500 J/KG)... SO WILL BRING IN CHANCE POPS AREAWIDE FRIDAY (MAINLY AFTERNOON INTO EARLY EVENING)... DECREASING AFTER MID EVENING AS SUBSTANTIAL FORCING FOR ASCENT CONTINUES TO BE LACKING... WHILE 850 MB FLOW BECOMES MORE WESTERLY. FORECAST SOUNDINGS SUGGEST THAT THERE WILL BE ENOUGH THIN SPOTS IN THE MID CLOUD COVERAGE TO FOSTER RADIATIONAL COOLING AND ANOTHER ROUND OF STRATUS/FOG OVERNIGHT. HIGHS 87-91 WITH THICKNESSES CLOSE TO NORMAL. LOWS 69-74. -GIH && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 305 AM TUESDAY... STILL APPEARS LIKELY THAT WE`LL SEE THE BEST CHANCE OF SHOWERS/STORMS DURING THIS FORECAST CYCLE ON SATURDAY... WITH LOWER CHANCES LARGELY CONFINED TO SRN SECTIONS ON SUNDAY/MONDAY. THE VORTEX WILL CROSS QUEBEC TO THE MARITIMES WHILE ADDITIONAL ENERGY TO ITS NORTH DROPS INTO ITS WEST SIDE... ALLOWING THE LONGWAVE TROUGH TO DEEPEN DOWN THROUGH THE GREAT LAKES/NORTHEAST/MIDATLANTIC... EVENTUALLY LEADING TO STRENGTHENING WNW MID LEVEL FLOW OVER NC. EXPECT A GOOD CHANCE OF SHOWERS/STORMS AREAWIDE SATURDAY AS THE SURFACE FRONT APPROACHES... WITH A SOUTHWARD SUPPRESSION OF THESE RAIN CHANCES SUNDAY/MONDAY AS THE FRONT DROPS SLOWLY THROUGH THE AREA... PROPELLED BY THE STRENGTHENING WNW STEERING FLOW. GFS/ECMWF THICKNESSES SUPPORT HIGHS NEAR TO JUST BELOW NORMAL... WITH LOWS A BIT ABOVE NORMAL SAT NIGHT TRENDING TO JUST BELOW NORMAL SUNDAY NIGHT. -GIH && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 145 AM TUESDAY... SHOWERS CONTINUE TO DEVELOP WEST OVER THE WESTERN PIEDMONT AND FOOTHILLS WHERE WEAK WARM ADVECTION AND UPSLOPE FLOW IS MORE PROMINENT...BUT THE TREND HAS BEEN FOR THE SHOWERS TO DISSIPATE AS THEY DRIFT EAST NEAR KINT/KGSO. HIGH PRESSURE OFF THE MID-ATLANTIC COAST IS FORECAST TO REMAIN RELATIVELY STATIONARY TODAY...WITH LITTLE CHANGE IN THE FLOW OVER CENTRAL NC. THUS...MOISTURE WILL CONTINUE TO BE BEST OVER WESTERN NC AND SHOWERS OR STORMS WILL STRUGGLE TO MOVE ACROSS THE PIEDMONT. FORECAST SOUNDINGS SHOW CEILINGS IN THE 3000-5000 FT RANGE TODAY...ALTHOUGH MVFR CEILINGS CERTAINLY WILL BE POSSIBLE AT KGSO AND KINT. OUTLOOK... EARLY MORNING STRATUS WILL BE A PROBLEM EACH MORNING THIS WEEK AS A MOIST SOUTHERLY FLOW PERSISTS. THE CHANCE OF SHOWERS AND STORMS WILL EXIST EACH DAY...PARTICULARLY OVER WESTERN NC. THE WEATHER WILL BECOME MORE UNSETTLED BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM..SMITH/HARTFIELD LONG TERM...HARTFIELD AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
240 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT FURTHER OFFSHORE THIS MORNING...GIVING WAY TO A MOIST...SOUTHERLY LOW LEVEL RETURN FLOW THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 240 AM TUESDAY... HIGH PRESSURE CENTERED OFF THE MID-ATLANTIC COAST THIS MORNING EXTENDS SOUTHWEST OVER EASTERN NC/SC...WHILE A A RELATIVELY FAST NORTHWESTERLY FLOW CONTINUES ALOFT. SOUTHEASTERLY RETURN FLOW AROUND THE HIGH PRESSURE HAS BEEN CREATING SOME WEAK WARM ADVECTION AND UPSLOPE FLOW...SUPPORTING THE DEVELOPMENT OF SCATTERED SHOWERS OVER THE FOOTHILLS AND WESTERN PIEDMONT. HOWEVER... THE PRECIP HAS STRUGGLED TO MOVE EAST ACROSS THE PIEDMONT ONCE IT MOVES OUT OF THE BETTER LOW-LEVEL MOIST AXIS OVER WESTERN NC. RAP AND WATER VAPOR IMAGERY SUGGEST A FEW WEAK DISTURBANCES ALOFT WILL DRIFT OVERHEAD TODAY...WHICH MAY AID PRECIP IN MOVING FURTHER EAST ACROSS THE PIEDMONT...BUT INSTABILITY WILL BE WEAK AND POPS WILL STILL BE GRADUATED FROM CHANCE IN THE WEST TO SLIGHT CHANCE IN THE EAST. SKIES WILL ALSO BE MORE CLOUDY OVER THE WESTERN CWA...WHERE FORECAST SOUNDINGS SHOW A SOLID LAYER OF MOISTURE BETWEEN 850-700MB. LOW-LEVEL THICKNESSES ARE ONLY SLIGHTLY HIGHER THAN THOSE OBSERVED ON MONDAY OF AROUND 1400M. WITH PERIODS OF CLOUD COVER...HIGHS SHOULD AGAIN BE IN THE LOW TO MID 80S. TONIGHT... SIMILAR TO THIS MORNING...SCATTERED SHOWER WILL BE POSSIBLE OVER THE WESTERN CWA...WITH THE SHOWERS LIKELY TO WEAKEN AS THEY DRIFT EAST INTO A MORE HOSTILE ENVIRONMENT AND SURFACE HIGH PRESSURE RIDGE. LOWS IN THE UPPER 60S. && .SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 245 AM TUESDAY... WEDNESDAY AND WEDNESDAY NIGHT... HIGH PRESSURE RIDGING ALONG THE CAROLINA COAST WILL WEAKEN WEDNESDAY AS THE PARENT HIGH MOVES FURTHER OFF THE MID-ATLANTIC COAST AND COLD FRONT MOVES THROUGH THE MIDWEST STATES. INSTABILITY...WHILE SLIGHTLY GREATER THAN FORECAST FOR TODAY... WILL CONTINUE TO BE WEAK OVER CENTRAL NC DESPITE RISING PRECIP WATER. WEAK WARM ADVECTION AND UPSLOPE SHOULD STILL FAVOR SCATTERED SHOWERS AND ISOLATED STORMS OVER THE WESTERN PIEDMONT. WHILE HIGHS WILL STILL BE BELOW NORMAL...FORECAST SOUNDINGS SHOW A LITTLE LESS CLOUD COVER AND BETTER MIXING...WHICH SHOULD SUPPORT HIGHS A COUPLE DEGREES WARMER THAN TODAY...85-88. LOWS AROUND 70. -SMITH FOR THURSDAY/THURSDAY NIGHT: THE CANADIAN VORTEX DRIFTS SLOWLY EASTWARD TO CENTRAL ONTARIO THU/THU NIGHT AS WEAK MID LEVEL RIDGING PASSES OVER NC... INSTIGATING SUBTLE WARMING ALOFT (500-300 MB) WITH A VERY LIGHT WESTERLY MID LEVEL FLOW AND THE JET STREAM DISPLACED WELL TO OUR NORTH ACROSS THE NRN GREAT LAKES... LARGE SCALE FORCED ASCENT WILL BE LIMITED TO LOWER LEVEL MASS CONVERGENCE OVER THE NC MOUNTAINS/FOOTHILLS INTO VA... IN THE LOW LEVEL MOIST CONVEYOR ZONE WHERE PW VALUES WILL BE GREATEST (NEAR 2.0 INCHES). SREF PROBABILITIES OF MEASURABLE RAIN REACH 50-70% OVER THE NW HALF OF THE FORECAST AREA LATE THU MORNING THROUGH THE AFTERNOON... CORRESPONDING TO MODEL-INDICATED AREAS OF ENHANCED LOW LEVEL MOISTURE TRANSPORT ON THE PERIPHERY OF THE OFFSHORE SURFACE HIGH... WITH PROBABILITIES OF 10% OR LOWER IN THE EAST WHERE FORECAST SOUNDINGS SHOW SEVERAL LAYERS OF DRY AIR THROUGH THE COLUMN WITH MINIMAL INSTABILITY. WILL KEEP CHANCE POPS ACROSS THE WRN AND FAR NRN CWA... ON THE PERIPHERY OF THE RIDGE CORE... WITH ISOLATED POPS OVER MUCH OF THE EAST. THE NAM HINTS AT POTENTIAL SEA-BREEZE CONVECTION WORKING INTO THE EXTREME SE FORECAST AREA... SO WILL PUT A SECONDARY POP MAX (BUT STILL JUST SMALL COVERAGE) HERE. HIGHS 86-90. MODELS AGREE ON ANY PRECIP SHUTTING OFF NEAR SUNSET... AND EXPECT LARGELY DRY WEATHER OVERNIGHT BUT WITH MID CLOUDS MOVING IN (BLOWOFF CLOUDS FROM MORE ORGANIZED/WIDESPREAD CONVECTION OVER WV/KY/TN)... AND WE SHOULD SEE STRATUS/FOG FORMATION OVERNIGHT GIVEN THE LIGHT SOUTH/SW FLOW AND RISING LOW LEVEL MOISTURE. LOWS 69-73. FOR FRIDAY/FRIDAY NIGHT: THE CANADIAN VORTEX IS EXPECTED TO CONTINUE ITS EASTWARD WOBBLE ACROSS ONTARIO TO THE TIP OF JAMES BAY DURING THIS TIME FRAME. THE GFS HAS BEEN TRENDING SLOWER WITH THIS IN RECENT RUNS... AND AS A RESULT IT NOW DELAYS THE ARRIVAL OF THE GREATER COVERAGE OF CONVECTION WITHIN THE STREAM OF PREFRONTAL WARM AIR ADVECTION... AND KEEPS THE FAR ERN CWA MAINLY DRY THROUGH FRI NIGHT. THE GFS KEEPS THE UPPER LEVEL ANTICYCLONE CENTER OVER THE CAROLINAS... AND WITH THE SWRLY UPPER JET CORE CROSSING THE GREAT LAKES... THE BULK OF THE UPPER DIVERGENCE SKIRTS BY TO OUR NW AND NORTH. THE SLIGHTLY FASTER ECMWF IS A BIT MORE EMPHATIC WITH CONVECTION ACROSS CENTRAL NC ALONG THE LEE SURFACE TROUGH AS THE MID LEVEL TROUGH AXIS APPROACHES... A SOLUTION THAT CANNOT BE DISCOUNTED GIVEN THE EXPECTED MODERATE INSTABILITY (MLCAPE NEAR 1500 J/KG)... SO WILL BRING IN CHANCE POPS AREAWIDE FRIDAY (MAINLY AFTERNOON INTO EARLY EVENING)... DECREASING AFTER MID EVENING AS SUBSTANTIAL FORCING FOR ASCENT CONTINUES TO BE LACKING... WHILE 850 MB FLOW BECOMES MORE WESTERLY. FORECAST SOUNDINGS SUGGEST THAT THERE WILL BE ENOUGH THIN SPOTS IN THE MID CLOUD COVERAGE TO FOSTER RADIATIONAL COOLING AND ANOTHER ROUND OF STRATUS/FOG OVERNIGHT. HIGHS 87-91 WITH THICKNESSES CLOSE TO NORMAL. LOWS 69-74. -GIH && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 318 PM MONDAY... SATURDAY....SUB TROPICAL RIDGE PROJECTED TO EXPAND/STRENGTHEN WEST-TO-EAST ACROSS THE LOWER MS VALLEY AND SE U.S. THIS WILL PLACE CENTRAL NC ON THE PERIPHERY OF THIS WEATHER SYSTEM. WEAK PERTURBATIONS TRAVERSING EWD COUPLED WITH AVAILABLE MOISTURE AND INSTABILITY SUGGEST A THREAT FOR SCATTERED SHOWERS AND STORMS EACH DAY...MORE SO ON SATURDAY AFTERNOON AS A S/W IN THE NORTHERN STREAM PROPELS A SFC FRONT SWD TOWARD CENTRAL NC. PLAN TO HAVE HIGH CHANCE POPS MOST LOCATIONS LATE SATURDAY-SATURDAY NIGHT. SUNDAY INTO MONDAY....LATEST GFS HAS TRENDED TOWARD THE MORE PROGRESSIVE ECMWF WHICH PUSHES THE SFC COLD FRONT SWD ACROSS CENTRAL NC SUNDAY...AND POSITIONED SOUTH OF THE REGION MONDAY. THIS SUGGEST A DECREASING THREAT FOR SCATTERED SHOWERS AND STORMS. PLAN TO MAINTAIN MENTION OF A SMALL CHANCE BOTH DAYS...SUNDAY TO ACCOUNT FOR POSSIBLE MODEL TIMING ISSUES WITH THE FRONTAL PASSAGE...AND ON MONDAY AS DEVELOPING NW FLOW ALOFT MAY PROVIDE AN AVENUE FOR DISTURBANCES ROTATING AROUND A DEEP CLOSED UPPER LOW OVER THE NORTHERN LAKES TO TRANSLATE INTO OUR REGION. TEMPS THURSDAY THROUGH MONDAY DEPENDENT UPON EXTENT OF CLOUD COVER AND AREAL COVERAGE OF CONVECTION. EXPECT AFTERNOON TEMPS TO AVERAGE A COUPLE OF DEGREES BELOW NORMAL WHILE OVERNIGHT TEMPS WILL BE 3-5 DEGREES ABOVE NORMAL. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 145 AM TUESDAY... SHOWERS CONTINUE TO DEVELOP WEST OVER THE WESTERN PIEDMONT AND FOOTHILLS WHERE WEAK WARM ADVECTION AND UPSLOPE FLOW IS MORE PROMINENT...BUT THE TREND HAS BEEN FOR THE SHOWERS TO DISSIPATE AS THEY DRIFT EAST NEAR KINT/KGSO. HIGH PRESSURE OFF THE MID-ATLANTIC COAST IS FORECAST TO REMAIN RELATIVELY STATIONARY TODAY...WITH LITTLE CHANGE IN THE FLOW OVER CENTRAL NC. THUS...MOISTURE WILL CONTINUE TO BE BEST OVER WESTERN NC AND SHOWERS OR STORMS WILL STRUGGLE TO MOVE ACROSS THE PIEDMONT. FORECAST SOUNDINGS SHOW CEILINGS IN THE 3000-5000 FT RANGE TODAY...ALTHOUGH MVFR CEILINGS CERTAINLY WILL BE POSSIBLE AT KGSO AND KINT. OUTLOOK... EARLY MORNING STRATUS WILL BE A PROBLEM EACH MORNING THIS WEEK AS A MOIST SOUTHERLY FLOW PERSISTS. THE CHANCE OF SHOWERS AND STORMS WILL EXIST EACH DAY...PARTICULARLY OVER WESTERN NC. THE WEATHER WILL BECOME MORE UNSETTLED BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM..SMITH/HARTFIELD LONG TERM...WSS AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
222 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT FURTHER OFFSHORE TONIGHT. A MOIST SOUTHERLY LOW LEVEL RETURN FLOW WILL PREVAIL THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 915 PM MONDAY... TONIGHT: SURFACE HIGH PRESSURE HAS SHIFTED JUST OFF THE SOUTHERN MID-ATLANTIC COAST THIS EVENING... WHILE THE MID/UPPER LEVEL FLOW ALOFT CONTINUES TO BE OUT OF THE NORTHWEST. THIS HAS RESULTED IN A LIGHT SOUTH/SOUTHEASTERLY SURFACE/LOW LEVEL RETURN FLOW UP AND INTO THE HIGHER TERRAIN ALONG WITH WEAK PERTURBATION MOVING THROUGH THE NORTHWEST FLOW ALOFT... WHICH HAS ALLOWED SOME SHOWERS TO DEVELOP IN THE HIGHER TERRAIN. THESE SHOWERS (AND PERHAPS A THUNDERSTORM OR TWO) HAVE HAD A HARD TIME COMING OFF THE HIGHER TERRAIN AND INTO THE PIEDMONT. HOWEVER... THE LATEST HRRR AND SOME OF THE OTHER HI-RES GUIDANCE IS NOW SHOWING THIS ACTIVITY SLOWLY SHIFTING EASTWARD AND INTO THE PIEDMONT LATER THIS EVENING INTO THE OVERNIGHT HOURS. GIVEN THE RATHER WEAK INSTABILITY EXPECTED OVER OUR AREA... WE DO NOT ANTICIPATE ANY SVR WEATHER FROM THIS ACTIVITY. HOWEVER... WE COULD SEE A BRIEF HEAVY DOWNPOUR AND REDUCED VISIBILITY AS A SHOWER AND/OR STORM MOVES ACROSS A GIVEN LOCATION. THE HIGHEST PROBABILITIES WILL REMAIN ACROSS THE NORTH/NORTHWESTERN PIEDMONT THIS EVENING/TONIGHT. THUS... WILL CONTINUE TO SHOW THE FAR NORTHWEST PIEDMONT WITH THE HIGHEST POPS AFTER MIDNIGHT (CHANCE... 25-40 PERCENT) TO SLIGHT CHANCE JUST WEST OF RALEIGH. GIVEN THIS EXPECT SKIES WILL GENERALLY BE PARTLY TO MOSTLY CLOUDY/CLOUDY OVERNIGHT... WHICH WILL HELP TO KEEP TEMPS UP A BIT TONIGHT... ALONG WITH THE INCREASE IN LOW LEVEL MOISTURE. THUS... EXPECT LOWS TO RANGE FROM THE MID 60S EAST TO UPPER 60S WEST. -BSD TUESDAY: EXPECT AN INCREASING POTENTIAL FOR SHOWER (THUNDERSTORM) ACTIVITY TUESDAY MORNING (AFTERNOON) AS A SEASONABLY MOIST SOUTHERLY LOW-LEVEL RETURN FLOW AIDS IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION IN THE PRESENCE OF WEAK LOW-LEVEL CONVERGENCE AND AN INCREASED POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN NW FLOW ALOFT. WILL INDICATE PRECIP CHANCES RANGING FROM 20-50%...HIGHEST IN THE WESTERN PIEDMONT AND LOWEST IN THE COASTAL PLAIN WHERE LOW-LEVEL MOISTURE /DIURNAL DESTABILIZATION/ IS EXPECTED TO BE MARGINAL. HIGHS WILL BE SIMILAR TO TODAY AND PRIMARILY DEPEND ON CLOUD COVER... RANGING FROM NEAR 80F IN THE N/NW PIEDMONT TO MID/UPPER 80S IN THE SANDHILLS AND COASTAL PLAIN. -VINCENT && .SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 318 PM MONDAY / 220 AM TUESDAY... TUESDAY NIGHT...APPROACH OF A WEAK MID-UPPER LEVEL DISTURBANCE COUPLED WITH AN INCREASINGLY MOIST AIR MASS WILL SUPPORT THE POTENTIAL FOR A FEW SHOWERS/ISOLATED THUNDER WELL INTO THE NIGHT...MAINLY OVER THE NW PIEDMONT. INCREASING/THICKENING CLOUD COVER AND A LIGHT SLY WIND WILL RESULT IN A FAIRLY UNIFORM TEMP FIELD OVERNIGHT. MIN TEMPS UPPER 60S TO AROUND 70. WEDNESDAY AND WEDNESDAY NIGHT...THE MID-UPPER LEVEL TROUGH TRANSLATE SLOWLY EWD TOWARD AND ACROSS THE MID ATLANTIC AND CAROLINAS WED AFTERNOON-EVENING. 12Z GFS NOT TOO IMPRESSIVE WITH ITS CONVECTIVE PARAMETERS WED AFTERNOON-EVENING ...DEPICTING MARGINAL/SLIGHT INSTABILITY AT BEST. STILL...FAVORED LOW LEVEL CONFLUENCE OVER THE WESTERN PIEDMONT DURING PRIME HEATING SUPPORT HIGH CHANCE POP IN THIS REGION....WITH POPS TAPERING TO SLIGHT CHANCE OVER THE SOUTHERN COASTAL PLAINS AND SANDHILLS. MORE CLOUDS THAN SUN WILL LIMIT NORMAL DIURNAL TEMP RISE IN THE WEST-NW WHERE MAX TEMPS EXPECTED TO BE LOWER 80S. PARTIAL SUN OVER THE SE HALF SHOULD WARM TEMPS WELL INTO THE 80S. CONSIDERABLE CLOUDINESS WEDNESDAY NIGHT WILL MAINTAIN HUMID CONDITIONS. MIN TEMPS AROUND 70/LOWER 70S. -WSS FOR THURSDAY/THURSDAY NIGHT: THE CANADIAN VORTEX DRIFTS SLOWLY EASTWARD TO CENTRAL ONTARIO THU/THU NIGHT AS WEAK MID LEVEL RIDGING PASSES OVER NC... INSTIGATING SUBTLE WARMING ALOFT (500-300 MB) WITH A VERY LIGHT WESTERLY MID LEVEL FLOW AND THE JET STREAM DISPLACED WELL TO OUR NORTH ACROSS THE NRN GREAT LAKES... LARGE SCALE FORCED ASCENT WILL BE LIMITED TO LOWER LEVEL MASS CONVERGENCE OVER THE NC MOUNTAINS/FOOTHILLS INTO VA... IN THE LOW LEVEL MOIST CONVEYOR ZONE WHERE PW VALUES WILL BE GREATEST (NEAR 2.0 INCHES). SREF PROBABILITIES OF MEASURABLE RAIN REACH 50-70% OVER THE NW HALF OF THE FORECAST AREA LATE THU MORNING THROUGH THE AFTERNOON... CORRESPONDING TO MODEL-INDICATED AREAS OF ENHANCED LOW LEVEL MOISTURE TRANSPORT ON THE PERIPHERY OF THE OFFSHORE SURFACE HIGH... WITH PROBABILITIES OF 10% OR LOWER IN THE EAST WHERE FORECAST SOUNDINGS SHOW SEVERAL LAYERS OF DRY AIR THROUGH THE COLUMN WITH MINIMAL INSTABILITY. WILL KEEP CHANCE POPS ACROSS THE WRN AND FAR NRN CWA... ON THE PERIPHERY OF THE RIDGE CORE... WITH ISOLATED POPS OVER MUCH OF THE EAST. THE NAM HINTS AT POTENTIAL SEA-BREEZE CONVECTION WORKING INTO THE EXTREME SE FORECAST AREA... SO WILL PUT A SECONDARY POP MAX (BUT STILL JUST SMALL COVERAGE) HERE. HIGHS 86-90. MODELS AGREE ON ANY PRECIP SHUTTING OFF NEAR SUNSET... AND EXPECT LARGELY DRY WEATHER OVERNIGHT BUT WITH MID CLOUDS MOVING IN (BLOWOFF CLOUDS FROM MORE ORGANIZED/WIDESPREAD CONVECTION OVER WV/KY/TN)... AND WE SHOULD SEE STRATUS/FOG FORMATION OVERNIGHT GIVEN THE LIGHT SOUTH/SW FLOW AND RISING LOW LEVEL MOISTURE. LOWS 69-73. FOR FRIDAY/FRIDAY NIGHT: THE CANADIAN VORTEX IS EXPECTED TO CONTINUE ITS EASTWARD WOBBLE ACROSS ONTARIO TO THE TIP OF JAMES BAY DURING THIS TIME FRAME. THE GFS HAS BEEN TRENDING SLOWER WITH THIS IN RECENT RUNS... AND AS A RESULT IT NOW DELAYS THE ARRIVAL OF THE GREATER COVERAGE OF CONVECTION WITHIN THE STREAM OF PREFRONTAL WARM AIR ADVECTION... AND KEEPS THE FAR ERN CWA MAINLY DRY THROUGH FRI NIGHT. THE GFS KEEPS THE UPPER LEVEL ANTICYCLONE CENTER OVER THE CAROLINAS... AND WITH THE SWRLY UPPER JET CORE CROSSING THE GREAT LAKES... THE BULK OF THE UPPER DIVERGENCE SKIRTS BY TO OUR NW AND NORTH. THE SLIGHTLY FASTER ECMWF IS A BIT MORE EMPHATIC WITH CONVECTION ACROSS CENTRAL NC ALONG THE LEE SURFACE TROUGH AS THE MID LEVEL TROUGH AXIS APPROACHES... A SOLUTION THAT CANNOT BE DISCOUNTED GIVEN THE EXPECTED MODERATE INSTABILITY (MLCAPE NEAR 1500 J/KG)... SO WILL BRING IN CHANCE POPS AREAWIDE FRIDAY (MAINLY AFTERNOON INTO EARLY EVENING)... DECREASING AFTER MID EVENING AS SUBSTANTIAL FORCING FOR ASCENT CONTINUES TO BE LACKING... WHILE 850 MB FLOW BECOMES MORE WESTERLY. FORECAST SOUNDINGS SUGGEST THAT THERE WILL BE ENOUGH THIN SPOTS IN THE MID CLOUD COVERAGE TO FOSTER RADIATIONAL COOLING AND ANOTHER ROUND OF STRATUS/FOG OVERNIGHT. HIGHS 87-91 WITH THICKNESSES CLOSE TO NORMAL. LOWS 69-74. -GIH && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 318 PM MONDAY... SATURDAY....SUB TROPICAL RIDGE PROJECTED TO EXPAND/STRENGTHEN WEST-TO-EAST ACROSS THE LOWER MS VALLEY AND SE U.S. THIS WILL PLACE CENTRAL NC ON THE PERIPHERY OF THIS WEATHER SYSTEM. WEAK PERTURBATIONS TRAVERSING EWD COUPLED WITH AVAILABLE MOISTURE AND INSTABILITY SUGGEST A THREAT FOR SCATTERED SHOWERS AND STORMS EACH DAY...MORE SO ON SATURDAY AFTERNOON AS A S/W IN THE NORTHERN STREAM PROPELS A SFC FRONT SWD TOWARD CENTRAL NC. PLAN TO HAVE HIGH CHANCE POPS MOST LOCATIONS LATE SATURDAY-SATURDAY NIGHT. SUNDAY INTO MONDAY....LATEST GFS HAS TRENDED TOWARD THE MORE PROGRESSIVE ECMWF WHICH PUSHES THE SFC COLD FRONT SWD ACROSS CENTRAL NC SUNDAY...AND POSITIONED SOUTH OF THE REGION MONDAY. THIS SUGGEST A DECREASING THREAT FOR SCATTERED SHOWERS AND STORMS. PLAN TO MAINTAIN MENTION OF A SMALL CHANCE BOTH DAYS...SUNDAY TO ACCOUNT FOR POSSIBLE MODEL TIMING ISSUES WITH THE FRONTAL PASSAGE...AND ON MONDAY AS DEVELOPING NW FLOW ALOFT MAY PROVIDE AN AVENUE FOR DISTURBANCES ROTATING AROUND A DEEP CLOSED UPPER LOW OVER THE NORTHERN LAKES TO TRANSLATE INTO OUR REGION. TEMPS THURSDAY THROUGH MONDAY DEPENDENT UPON EXTENT OF CLOUD COVER AND AREAL COVERAGE OF CONVECTION. EXPECT AFTERNOON TEMPS TO AVERAGE A COUPLE OF DEGREES BELOW NORMAL WHILE OVERNIGHT TEMPS WILL BE 3-5 DEGREES ABOVE NORMAL. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 145 AM TUESDAY... SHOWERS CONTINUE TO DEVELOP WEST OVER THE WESTERN PIEDMONT AND FOOTHILLS WHERE WEAK WARM ADVECTION AND UPSLOPE FLOW IS MORE PROMINENT...BUT THE TREND HAS BEEN FOR THE SHOWERS TO DISSIPATE AS THEY DRIFT EAST NEAR KINT/KGSO. HIGH PRESSURE OFF THE MID-ATLANTIC COAST IS FORECAST TO REMAIN RELATIVELY STATIONARY TODAY...WITH LITTLE CHANGE IN THE FLOW OVER CENTRAL NC. THUS...MOISTURE WILL CONTINUE TO BE BEST OVER WESTERN NC AND SHOWERS OR STORMS WILL STRUGGLE TO MOVE ACROSS THE PIEDMONT. FORECAST SOUNDINGS SHOW CEILINGS IN THE 3000-5000 FT RANGE TODAY...ALTHOUGH MVFR CEILINGS CERTAINLY WILL BE POSSIBLE AT KGSO AND KINT. OUTLOOK... EARLY MORNING STRATUS WILL BE A PROBLEM EACH MORNING THIS WEEK AS A MOIST SOUTHERLY FLOW PERSISTS. THE CHANCE OF SHOWERS AND STORMS WILL EXIST EACH DAY...PARTICULARLY OVER WESTERN NC. THE WEATHER WILL BECOME MORE UNSETTLED BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD NEAR TERM...BSD/VINCENT SHORT TERM..WSS/HARTFIELD LONG TERM...WSS AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
145 AM EDT TUE AUG 6 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT FURTHER OFFSHORE TONIGHT. A MOIST SOUTHERLY LOW LEVEL RETURN FLOW WILL PREVAIL THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 915 PM MONDAY... TONIGHT: SURFACE HIGH PRESSURE HAS SHIFTED JUST OFF THE SOUTHERN MID-ATLANTIC COAST THIS EVENING... WHILE THE MID/UPPER LEVEL FLOW ALOFT CONTINUES TO BE OUT OF THE NORTHWEST. THIS HAS RESULTED IN A LIGHT SOUTH/SOUTHEASTERLY SURFACE/LOW LEVEL RETURN FLOW UP AND INTO THE HIGHER TERRAIN ALONG WITH WEAK PERTURBATION MOVING THROUGH THE NORTHWEST FLOW ALOFT... WHICH HAS ALLOWED SOME SHOWERS TO DEVELOP IN THE HIGHER TERRAIN. THESE SHOWERS (AND PERHAPS A THUNDERSTORM OR TWO) HAVE HAD A HARD TIME COMING OFF THE HIGHER TERRAIN AND INTO THE PIEDMONT. HOWEVER... THE LATEST HRRR AND SOME OF THE OTHER HI-RES GUIDANCE IS NOW SHOWING THIS ACTIVITY SLOWLY SHIFTING EASTWARD AND INTO THE PIEDMONT LATER THIS EVENING INTO THE OVERNIGHT HOURS. GIVEN THE RATHER WEAK INSTABILITY EXPECTED OVER OUR AREA... WE DO NOT ANTICIPATE ANY SVR WEATHER FROM THIS ACTIVITY. HOWEVER... WE COULD SEE A BRIEF HEAVY DOWNPOUR AND REDUCED VISIBILITY AS A SHOWER AND/OR STORM MOVES ACROSS A GIVEN LOCATION. THE HIGHEST PROBABILITIES WILL REMAIN ACROSS THE NORTH/NORTHWESTERN PIEDMONT THIS EVENING/TONIGHT. THUS... WILL CONTINUE TO SHOW THE FAR NORTHWEST PIEDMONT WITH THE HIGHEST POPS AFTER MIDNIGHT (CHANCE... 25-40 PERCENT) TO SLIGHT CHANCE JUST WEST OF RALEIGH. GIVEN THIS EXPECT SKIES WILL GENERALLY BE PARTLY TO MOSTLY CLOUDY/CLOUDY OVERNIGHT... WHICH WILL HELP TO KEEP TEMPS UP A BIT TONIGHT... ALONG WITH THE INCREASE IN LOW LEVEL MOISTURE. THUS... EXPECT LOWS TO RANGE FROM THE MID 60S EAST TO UPPER 60S WEST. -BSD TUESDAY: EXPECT AN INCREASING POTENTIAL FOR SHOWER (THUNDERSTORM) ACTIVITY TUESDAY MORNING (AFTERNOON) AS A SEASONABLY MOIST SOUTHERLY LOW-LEVEL RETURN FLOW AIDS IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION IN THE PRESENCE OF WEAK LOW-LEVEL CONVERGENCE AND AN INCREASED POTENTIAL FOR SMALL AMPLITUDE DISTURBANCES IN NW FLOW ALOFT. WILL INDICATE PRECIP CHANCES RANGING FROM 20-50%...HIGHEST IN THE WESTERN PIEDMONT AND LOWEST IN THE COASTAL PLAIN WHERE LOW-LEVEL MOISTURE /DIURNAL DESTABILIZATION/ IS EXPECTED TO BE MARGINAL. HIGHS WILL BE SIMILAR TO TODAY AND PRIMARILY DEPEND ON CLOUD COVER... RANGING FROM NEAR 80F IN THE N/NW PIEDMONT TO MID/UPPER 80S IN THE SANDHILLS AND COASTAL PLAIN. -VINCENT && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 318 PM MONDAY... TUESDAY NIGHT...APPROACH OF A WEAK MID-UPPER LEVEL DISTURBANCE COUPLED WITH AN INCREASINGLY MOIST AIR MASS WILL SUPPORT THE POTENTIAL FOR A FEW SHOWERS/ISOLATED THUNDER WELL INTO THE NIGHT...MAINLY OVER THE NW PIEDMONT. INCREASING/THICKENING CLOUD COVER AND A LIGHT SLY WIND WILL RESULT IN A FAIRLY UNIFORM TEMP FIELD OVERNIGHT. MIN TEMPS UPPER 60S TO AROUND 70. WEDNESDAY AND WEDNESDAY NIGHT...THE MID-UPPER LEVEL TROUGH TRANSLATE SLOWLY EWD TOWARD AND ACROSS THE MID ATLANTIC AND CAROLINAS WED AFTERNOON-EVENING. 12Z GFS NOT TOO IMPRESSIVE WITH ITS CONVECTIVE PARAMETERS WED AFTERNOON-EVENING ...DEPICTING MARGINAL/SLIGHT INSTABILITY AT BEST. STILL...FAVORED LOW LEVEL CONFLUENCE OVER THE WESTERN PIEDMONT DURING PRIME HEATING SUPPORT HIGH CHANCE POP IN THIS REGION....WITH POPS TAPERING TO SLIGHT CHANCE OVER THE SOUTHERN COASTAL PLAINS AND SANDHILLS. MORE CLOUDS THAN SUN WILL LIMIT NORMAL DIURNAL TEMP RISE IN THE WEST-NW WHERE MAX TEMPS EXPECTED TO BE LOWER 80S. PARTIAL SUN OVER THE SE HALF SHOULD WARM TEMPS WELL INTO THE 80S. CONSIDERABLE CLOUDINESS WEDNESDAY NIGHT WILL MAINTAIN HUMID CONDITIONS. MIN TEMPS AROUND 70/LOWER 70S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 318 PM MONDAY... THURSDAY... LINGERING MID-UPPER LEVEL TROUGH WILL MAINTAIN A DECENT THREAT FOR SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY AS LOW LEVEL CONVERGENCE PROJECTED TO BE MAXIMIZED OVER OUR REGION. ONLY CAVEAT IS THAT BUILDING MID-UPPER LEVEL HEIGHTS MAY RESULT IN THE DEVELOPMENT OF A LAYER OF WARM AIR ALOFT...POSSIBLY CAPPING AIR MASS AND LIMITING CONVECTIVE DEVELOPMENT. HOWEVER CONSIDERING THE AMOUNT OF LOW LEVEL CONVERGENCE AND AVAILABLE MOISTURE SUPPORT CHANCE POPS THURSDAY. FRIDAY-SATURDAY....SUB TROPICAL RIDGE PROJECTED TO EXPAND/STRENGTHEN WEST-TO-EAST ACROSS THE LOWER MS VALLEY AND SE U.S. THIS WILL PLACE CENTRAL NC ON THE PERIPHERY OF THIS WEATHER SYSTEM. WEAK PERTURBATIONS TRAVERSING EWD COUPLED WITH AVAILABLE MOISTURE AND INSTABILITY SUGGEST A THREAT FOR SCATTERED SHOWERS AND STORMS EACH DAY...MORE SO ON SATURDAY AFTERNOON AS A S/W IN THE NORTHERN STREAM PROPELS A SFC FRONT SWD TOWARD CENTRAL NC. PLAN TO HAVE CHANCE-SLIGHT CHANCE POPS NW-SE ACROSS THE REGION FRIDAY WITH HIGH CHANCE POPS MOST LOCATIONS LATE SATURDAY-SATURDAY NIGHT. SUNDAY INTO MONDAY....LATEST GFS HAS TRENDED TOWARD THE MORE PROGRESSIVE ECMWF WHICH PUSHES THE SFC COLD FRONT SWD ACROSS CENTRAL NC SUNDAY...AND POSITIONED SOUTH OF THE REGION MONDAY. THIS SUGGEST A DECREASING THREAT FOR SCATTERED SHOWERS AND STORMS. PLAN TO MAINTAIN MENTION OF A SMALL CHANCE BOTH DAYS...SUNDAY TO ACCOUNT FOR POSSIBLE MODEL TIMING ISSUES WITH THE FRONTAL PASSAGE...AND ON MONDAY AS DEVELOPING NW FLOW ALOFT MAY PROVIDE AN AVENUE FOR DISTURBANCES ROTATING AROUND A DEEP CLOSED UPPER LOW OVER THE NORTHERN LAKES TO TRANSLATE INTO OUR REGION. TEMPS THURSDAY THROUGH MONDAY DEPENDENT UPON EXTENT OF CLOUD COVER AND AREAL COVERAGE OF CONVECTION. EXPECT AFTERNOON TEMPS TO AVERAGE A COUPLE OF DEGREES BELOW NORMAL WHILE OVERNIGHT TEMPS WILL BE 3-5 DEGREES ABOVE NORMAL. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 145 AM TUESDAY... SHOWERS CONTINUE TO DEVELOP WEST OVER THE WESTERN PIEDMONT AND FOOTHILLS WHERE WEAK WARM ADVECTION AND UPSLOPE FLOW IS MORE PROMINENT...BUT THE TREND HAS BEEN FOR THE SHOWERS TO DISSIPATE AS THEY DRIFT EAST NEAR KINT/KGSO. HIGH PRESSURE OFF THE MID-ATLANTIC COAST IS FORECAST TO REMAIN RELATIVELY STATIONARY TODAY...WITH LITTLE CHANGE IN THE FLOW OVER CENTRAL NC. THUS...MOISTURE WILL CONTINUE TO BE BEST OVER WESTERN NC AND SHOWERS OR STORMS WILL STRUGGLE TO MOVE ACROSS THE PIEDMONT. FORECAST SOUNDINGS SHOW CEILINGS IN THE 3000-5000 FT RANGE TODAY...ALTHOUGH MVFR CEILINGS CERTAINLY WILL BE POSSIBLE AT KGSO AND KINT. OUTLOOK... EARLY MORNING STRATUS WILL BE A PROBLEM EACH MORNING THIS WEEK AS A MOIST SOUTHERLY FLOW PERSISTS. THE CHANCE OF SHOWERS AND STORMS WILL EXIST EACH DAY...PARTICULARLY OVER WESTERN NC. THE WEATHER WILL BECOME MORE UNSETTLED BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD NEAR TERM...BSD/VINCENT SHORT TERM..WSS LONG TERM...WSS AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
903 PM CDT WED AUG 7 2013 .UPDATE... ISSUED AT 903 PM CDT WED AUG 7 2013 MAIN UPDATE WAS TO REMOVE MENTION OF THUNDER FOR ALL BUT THE SOUTHWEST UNTIL MIDNIGHT...THEN REMOVE THUNDER ALTOGETHER. LATEST WATER VAPOR IMAGERY SHOWED A SHORTWAVE NOW OVER WESTERN NORTH DAKOTA...WITH A NARROW BAND OF LIFT/RAIN SHOWERS SOUTH OF HIGHWAY 2...FROM NEAR NEW TOWN EAST TO HARVEY. THIS AREA WAS CONTINUING TO SAG SOUTH WHILE CONTINUING TO ADVANCE EAST. LOCAL RADAR WAS ALSO SHOWING A WEAK LINE OF SHOWERS EXTENDING FROM GARRISON SOUTH TO BISMARCK. SPC MESO-ANALYSIS SHOWS MID LEVEL LAPSE RATES INCREASING IN RESPONSE TO THE SHORTWAVE IN WESTERN NORTH DAKOTA. WITH 50KT 0-6KM SHEAR IN THE SOUTHWEST...WILL CONTINUE TO MENTION ISOLATED THUNDERSTORMS. A LACK OF INSTABILITY ELSEWHERE WILL INHIBIT ANY THREAT OF THUNDERSTORMS. THE RAP AND 00Z NAM MAINTAIN THE IDEA THAT ISOLATED SHOWERS WILL CONTINUE TO PUSH SOUTH TO THE BORDER THROUGH 12Z THURSDAY. CONCUR WITH THIS IDEA BASED ON THE POSITION AND MOVEMENT OF THE AFOREMENTIONED SHORTWAVE. MINOR UPDATES TO POPS/SKY/WX AND HOURLY TEMPERATURES. UPDATE ISSUED AT 542 PM CDT WED AUG 7 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE NOW WORKING ITS WAY INTO NORTHEAST MONTANA FROM SOUTHERN SASKATCHEWAN. AN AREA OF RAIN SHOWERS CONTINUE TO MOVE INTO NORTHWEST NORTH DAKOTA. THE LATEST RAP HAS A GOOD READ ON THE ACTIVITY AS SCOOTS IT ACROSS THE NORTH CENTRAL THIS EVENING. IN ADDITION...WILL WATCH FOR SHOWERS TO DEVELOP IN THE WEST AND SOUTH CENTRAL EARLY TONIGHT PER RAP MODEL. RADAR SHOWING A WEAK LINE TRYING TO GENERATE FROM NEAR WILLISTON SOUTH TO TROTTERS AT THIS MOMENT. BEST FORCING REMAINS NORTH. THUS WILL CONTINUE WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NORTH THIS EVENING AND ISOLATED SHOWERS/THUNDERSTORMS WEST AND CENTRAL OVERNIGHT. GIVEN THE WEAK INSTABILITY...THUNDER SHOULD REMAIN ISOLATED. MINOR UPDATES TO HOURLY TEMPS/DEWPOINTS AND CHANGED UNCERTAINTY WORDING TO AREAL COVERAGE IN THE WEATHER GROUP BASED ON RADAR. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 338 PM CDT WED AUG 7 2013 CURRENTLY...A STRONG UPPER LEVEL JET AND A SHORTWAVE IMPULSE TRACKING ACROSS SOUTHERN SASKATCHEWAN IS RESPONSIBLE FOR PRODUCING SCATTERED SHOWERS FROM NORTHEAST MONTANA INTO NORTHWEST NORTH DAKOTA. THE SHOWERS ARE EXPECTED TO TRACK EAST AND SOUTH ACROSS THE AREA LATE THIS AFTERNOON AND THIS EVENING. SIMILAR TO THE TRACK OF A SHORTWAVE YESTERDAY. THE MAIN DIFFERENCE IS THE ATMOSPHERE IS MORE STABLE TODAY. HOWEVER...WITH A STRONG UPPER LEVEL JET AND SHORTWAVE...WE CANNOT RULE OUT A FEW THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING...WITH SMALL HAIL AND GUSTY WINDS. HOWEVER IN THE FORECAST WE LIMITED THE BEST CHANCES TO THE NORTH LATE THIS AFTERNOON...AND WITH LIMITED INSTABILITY AND CAPPING ALOFT...WE KEPT A MENTION OF SHOWERS WITH ONLY ISOLATED THUNDERSTORMS. EXPECT PRECIPITATION CHANCES TO DIMINISH AS THE SYSTEM TRACKS SOUTHEAST. BUT THE LATEST RAP AND HRRR HOLD REFLECTIVITIES TOGETHER AS THEY TRACK INTO THE SOUTHEAST CWA AROUND MIDNIGHT. MODELS HAVE TRENDED FARTHER SOUTH WITH THE NEXT WAVE COMING INTO THE AREA AFTER MIDNIGHT. HAVE THEREFORE CONTINUED THE TREND OF LOWERING POPS ACROSS THE AREA. CURRENTLY HAVE CHANCE POPS ACROSS THE FAR SOUTHWEST AND SOUTH CENTRAL LATE TONIGHT...AND HAVE DROPPED POPS ACROSS THE SOUTH ON THURSDAY MORNING. ANOTHER SHORTWAVE MOVING ACROSS ALBERTA TONIGHT WILL DROP SOUTHEAST INTO THE LOCAL AREA THURSDAY AFTERNOON. THIS COULD DEVELOP AN ISOLATED SHOWERS ACROSS THE NORTH DURING THE AFTERNOON. TEMPERATURES WILL REMAIN ON THE COOL SIDE WITH HIGHS RANGING FROM THE 60S NORTH TO THE 70S SOUTH. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 PM CDT WED AUG 7 2013 CONTINUED BELOW NORMAL TEMPERATURES WILL HIGHLIGHT THE EXTENDED FORECAST. AS HAS BEEN THE PATTERN OVER THE LAST COUPLE WEEKS...NORTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE NORTHERN PLAINS THROUGH THE EXTENDED. THIS FAVORS BELOW NORMAL TEMPERATURES WITH HIGHS GENERALLY IN THE 70S...PERHAPS RECOVERING INTO THE LOWER 80S BY MID NEXT WEEK. OVERALL...THE COOLER EDGE OF GUIDANCE HAS BEEN HANDLING THIS PATTERN BETTER...AND THUS UTILIZED A BLEND OF THE BIAS CORRECTED 12 UTC SUITE. IN REGARDS TO PRECIPITATION...WHILE ISOLATED DIURNAL CONVECTION IS HARD TO RULE OUT ANY DAY UNDER NORTHWEST FLOW...THE FAVORED PERIODS FOR PRECIPITATION ARE SATURDAY WITH LEE SURFACE LOW PRESSURE AND AGAIN TUESDAY INTO WEDNESDAY AS PACIFIC ENERGY CRESTS THE UPPER LEVEL INTERMOUNTAIN WEST RIDGE AND PROPAGATES INTO THE NORTHERN PLAINS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 542 PM CDT WED AUG 7 2013 SCT/BKN LOW VFR CIGS WILL CONTINUE THROUGH THE TAF PERIOD UNDER A NORTHWEST UPPER FLOW AND A COUPLE OF UPPER AIR DISTURBANCES RESULTING IN A VCSH MENTION AT KISN/KMOT/KJMS. COULD BE PATCHY FOG DEVELOPING FOR A SHORT PERIOD TOWARD 12Z THURSDAY AT KMOT. WILL MONITOR SATELLITE AND SURFACE OBSERVATIONS BEFORE MENTIONING A PREDOMINATE GROUP IN THE FORECAST. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...TWH LONG TERM...AYD AVIATION...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1131 PM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 1125 PM CDT MON AUG 5 2013 MAIN QUESTION IS HOW MUCH PRECIP WILL MAKE IT THIS FAR EAST LATER TONIGHT INTO TUESDAY. BIG MCS NOW IN SOUTHERN KANSAS AND LACK OF ANY STRONG LOW LEVEL MOISTURE ADVECTION AND WEAK 850 MB JET IS CAUSING A LOT OF THE ACTIVITY FROM SASK INTO WRN ND TO WEAKEN. CANADAIAN RADARS SHOW THIS TOO. BUT VORT IS PRETTY STRONG SO DO FORSEE SOME ACTIVITY TO MAKE IT IN AS FCST OVERNIGHT. 00Z MODELS AND LATEST HRRR COMING AROUND TO THE IDEA OF A WEAK SFC LOW NR WILLISTON MOVING SOUTHEAST TO NEAR FARGO AREA BY 16Z TUE WITH WINDS TURNING NORTHWEST AND NORTH BEHIND IT. 00Z GFS ACTUALLY NOT BAD WITH QPF THIS RUN....OTHER MODELS TOO MUCH. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 321 PM CDT MON AUG 5 2013 WITH THE CLOUDS CONTINUING TO PUSH EAST SLOWLY ANY CLEARING WILL BE RELATIVELY SHORT LIVED. CONVECTION STARTING UP OVER EASTERN MT WILL BEGIN SPREADING IN SOME HIGHER LEVEL CLOUDS TONIGHT. THE MAIN FORECAST CONCERN WILL SHIFT BACK TO TIMING THE NEXT CHANCE OF PCPN FOR LATER TONIGHT INTO TUE/TUE NIGHT. TRIED TO FOLLOW THE HIGH RES MODELS FOR THE ARRIVAL TIME OF PCPN TONIGHT AND THEN KIND OF A BLEND FOR TIMING THE BEST CHANCES FROM WEST TO EAST THRU TUE. SPC HAS SOUTHWEST ND AND WESTERN SD IN A SLIGHT RISK FOR DAY1. THIS IS THE AREA ONCE AGAIN WHICH HAS HEATED OUT WITH SLIGHTLY HIGHER DEW POINTS. RESULTANT MLCAPE VALUES ARE PUSHING TO AROUND 1500J/KG WITH DECENT SHEAR ALSO PRESENT. SO ONCE AGAIN THE CONVECTION IS FIRING WEST OF THE FA. THE NEXT DECENT UPSTREAM SHORT WAVE IS DROPPING INTO NORTHWEST MT. THIS WAVE WILL BEGIN AN EASTWARD SHIFT TAKING IT INTO EASTERN MT/WESTERN ND BY 06Z THEN CENTRAL ND BY 12Z. THEREFORE IT SEEMS REASONABLE THAT SOME LINGERING CONVECTION THAT FIRES OUT WEST MAY HOLD TOGETHER AS IT TRACKS INTO THE FA LATE. ANOTHER AREA THAT WILL BEAR WATCHING IS A COLD FRONT UP IN THE MANITOBA LAKES REGION NORTH OF WINNIPEG. AS THE WESTERN WAVE APPROACHES CENTRAL ND BY 12Z TUE IT WILL HELP ORGANIZE A WEAK SFC LOW IN THIS SAME GENERAL VICINITY. THE COLD FRONT SHOULD GET DRAWN DOWN INTO THE NORTHERN FA BY 12Z. THE HIGH RES MODELS SHOW THE POTENTIAL FOR SOME PCPN ALONG THIS BOUNDARY TOO. SOME WEAK WARM ADVECTION AND LOW LEVEL JET ENERGY MAY ALSO COME INTO PLAY AFTER DARK TOO...FEEDING INTO CENTRAL ND IN THE LATE EVENING. ALL OF THE ABOVE MENTIONED FEATURES KIND OF MELD OVER THE FA ON TUE WITH THE COLD FRONT SLOWLY SLIDING FROM NORTH TO SOUTH AND THE SHORT WAVE FROM WEST TO EAST. KEPT LIKELY CHANCES FOR PCPN AND TRIED TO BREAK THEM OUT TO SHOW THE WEST TO EAST PROGRESS THRU THE DAY. SPC DAY2 HAS A SLIGHT RISK JUST TO THE SOUTH OF THE FA SO HOW FAST THE FRONT DROPS SOUTH WILL LIKELY DETERMINE IF ANY TSTMS CAN BECOME STRONG TO SEVERE ACROSS THE FAR SOUTH TUE AFTERNOON. STILL EXPECT ANY LINGERING PCPN TO EXIT THE EAST TUE EVENING. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 321 PM CDT MON AUG 5 2013 KEPT WED PCPN FREE WITH THE NEXT PCPN CHANCES COMING WED NIGHT INTO THU. PRETTY MUCH LEFT THE PCPN CHANCES FOR THIS NEXT EVENT AS IS FOR NOW. FRIDAY TO MONDAY...MODEL AGREEMENT CONTINUES WITH THE SAME OLD PATTERN OF CONFLUENT NW FLOW AT 500MB...WHICH MEANS DRY AND SLIGHTLY COOLER THAN NORMAL FOR THE NORTHERN PLAINS. THERE REMAINS A CHANCE FOR SOME SHOWER ACTIVITY AT SOME POINT OVER THE NEXT WEEKEND BUT WITH UNCERTAINTY IN TIMING AND SMALL AREAL COVERAGE THAT A WEAK WAVE MAY INDUCED PRECIP...HAVE KEPT THE MAJORITY OF THE CWFA COMPLETELY DRY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1125 PM CDT MON AUG 5 2013 HIGH CLOUDS SPREADING ACROSS THE AREA ATTM...AND QUESTION WILL BE TIMING ANY SHOWERS. THUNDER THREAT IS WEAKENING AND SHOULD BE ISOLD OVERNIGHT INTO TUESDAY MORNING. EXPECT SHOWERS TO COME FROM BASES AOA 6000 FT AGL AS SYSTEM MOVES THROUGH. WINDS TURN NORTH- NORTHWEST TUESDAY MORNING IN DVL REGION THEN REACHING SE ND/WCNTRL MN TUES EARLY-MID AFTN. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...RIDDLE SHORT TERM...GODON LONG TERM...GODON/JK AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
911 PM EDT WED AUG 7 2013 .SYNOPSIS... A COLD FRONT WILL SLOWLY PUSH INTO THE REGION TONIGHT AND THURSDAY. THE FRONT WILL EVENTUALLY STALL CLOSE TO THE OHIO RIVER BY FRIDAY MORNING. THIS FRONTAL BOUNDARY WILL THEN OSCILLATE NEAR THE OHIO RIVER THROUGH THE WEEKEND. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE PERIOD...ESPECIALLY FOR THOSE LOCATIONS CLOSER TO THE FRONTAL BOUNDARY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... HAVE UPDATED PRIMARILY TO ACCOUNT FOR SHOWERS AND THUNDERSTORMS OVER PORTIONS OF NORTHERN KENTUCKY SOUTH OF METRO CINCINNATI. A WEAK INFLECTION RUNNING ALONG BUT JUST SOUTHEAST OF THE I-71 CORRIDOR MAY HAVE AN ENHANCED POTENTIAL FOR SHOWERS THIS EVENING BUT ONLY FOR THE NEXT HOUR OR TWO. UPSTREAM STORMS OVER INDIANA DO NOT POSE A THREAT TO US IN THE NEXT 3-5 HOURS AND THE STORMS OVER KY WILL BE DYING OUT AS THEY SLOWLY MOVE ENE. BLENDED INTO THE 30ISH POPS TOWARDS DAYBREAK THAT WERE IN EARLIER FORECAST AND TRIED TO PLAY DOWN THE THREAT ELSEWHERE...AT LEAST FOR THE EARLY PART OF THE OVERNIGHT. HAVE USED A BLEND OF THE HRRR AND NAM FOR THE NEAR TERM FORECAST. A COLD FRONT WAS POISED TO OUR NORTHWEST THIS EVENING. THIS FRONT IS FORECAST TO SLOWLY SINK SOUTHEAST TOWARD THE AREA OVERNIGHT. CURRENT THINKING IS THAT CONVECTIVE ACTIVITY NEAR THE FRONT WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING AND FORCING. LATEST MODEL RUNS NOW SUGGEST THAT SUBTLE LOW LEVEL JET AND ASSOCIATED UPR LVL DISTURBANCE WILL LIKELY STAY TO OUR SOUTH AND SOUTHWEST OVERNIGHT. AS A RESULT...WITH VERY WEAK FORCING...CAN NOT SEE GOING MUCH HIGHER THAN 30 POPS FOR ALL LOCATIONS. WILL UPDATE THE ZONES TO REFLECT THIS. WILL ALSO REMOVE HEAVY RAIN THREAT GIVEN SPARSE COVERAGE. AMPLE LOW LEVEL MOISTURE AND DIMINISHING WINDS WILL MAKE FOG AND/OR STRATUS A CONCERN AFTER MIDNIGHT...ESPECIALLY IF HOLES CAN DEVELOP IN THE MID AND UPPER LEVEL CLOUDS. WILL CONTINUE TO MENTION AREAS OF FOG IN THE ZONES AFTER MIDNIGHT AS WELL AS IN THE HWO. LOWS WILL RANGE FROM THE UPPER 60S NW TO THE LOWER 70S ELSEWHERE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THE LOWER GREAT LAKES AND OHIO VALLEY REGION WILL BE BETWEEN A LARGE ANOMALOUS UPR LVL LOW OVER ONTARIO AND A MID LVL SUBTROPICAL RIDGE OVER THE SRN STATES THROUGH THE SHORT TERM PERIOD. THIS SETUP WILL ONLY ALLOW AFOREMENTIONED FRONTAL SYSTEM TO MOVE EVER SO SLOWLY TO SOUTHEAST...EVENTUALLY STALLING NEAR THE OHIO RIVER BY FRIDAY MORNING AS MID LEVEL FLOW BECOMES ZONAL. THE FRONT WILL PROVIDE THE FOCUS FOR SHOWERS AND STORMS THROUGH THE PERIOD...BUT THE TIMING AND AREAL COVERAGE WILL BE PROBLEMATIC AS MODELS ARE ESSENTIALLY OFFERING DIFFERENT SOLUTIONS. HAVE GONE WITH A NAM/ECMWF BLEND WHICH IS FORECASTING A SLOWER FRONTAL MOVEMENT. AS SUCH...THERE IS A HINT OF A FRONTAL WAVE RIPPLING ALONG THE FRONT ON THURSDAY THROUGH THE HEART OF THE FORECAST AREA. THIS WAVE AND ANY UPR LVL SUPPORT FROM AN ASSOCIATED DISTURBANCE OR MCV SHOULD PROVIDE THE BEST CHANCE FOR SHOWERS AND STORMS ALONG AND SOUTHEAST OF THE LOW. HAVE HIGHEST POPS MAINLY FOR POINTS ALONG AND SOUTHEAST OF INTERSTATE 71 WITH THE DIURNAL CYCLE PLAYING A ROLE IN TERMS OF BEST COVERAGE. LOOKS LIKE WAVE MOVES OFF TO THE NORTHEAST THURSDAY NIGHT...WHICH SHOULD RESULT IN A DOWN TICK IN SHOWER/THUNDERSTORMS COVERAGE IN ITS WAKE. THE AIRMASS WILL BE QUITE MOIST ALONG AND AHEAD OF THE FRONT WITH PWATS OF 2 INCHES PLUS EXPECTED. IN ADDITION...WARM CLOUD DEPTHS WILL BE CLOSE TO 4 KM WHICH WOULD FAVOR COLLISION/COALESCENCE PROCESSES AND THE POTENTIAL FOR HEAVY RAIN. GIVEN THE UNCERTAINTY IN PLACEMENT OF HEAVIEST RAIN WITH UPCOMING ROUNDS OF SHOWERS AND STORMS...WILL CONTINUE TO HIGHLIGHT THE HEAVY RAIN THREAT/LOCAL FLOODING ISSUES IN THE HWO WITH AN EMPHASIS PLACED ACRS THE SRN CWFA CLOSER TO THE FRONTAL BOUNDARY. HIGHS ON THURSDAY SHOULD BE HELD DOWN BY CLOUDS AND PCPN...WITH LOWER TO MID 80S EXPECTED. LOWS THURSDAY NIGHT WILL RANGE FROM THE MID 60S NW TO THE LOWER 70S SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... MAIN FOCUS FOR THE FIRST PART OF THE EXTENDED PERIOD WILL BE A SURFACE FRONTAL BOUNDARY THAT WILL ORIENT ITSELF ALONG THE OHIO RIVER FRIDAY MORNING. WITH ZONAL FLOW ALOFT...THIS BOUNDARY WILL VERY SLOWLY SAG SOUTHWARD THROUGH THE WEEKEND. ONE WAVE OF LOW PRESSURE RIDING ALONG THE FRONT WILL BE EXITING TO THE NORTHEAST AT THE START OF THE PERIOD...ONLY TO BE FOLLOWED BY ANOTHER RIPPLE FRIDAY NIGHT INTO SATURDAY. SOUTHERN PORTIONS OF THE FA WILL SEE THE GREATEST CHANCE FOR RAIN THROUGH THE WEEKEND AND LATEST DETERMINISTIC RUNS CONTINUE TO INDICATE PW VALUES IN THE 150 TO 175 PERCENT OF NORMAL RANGE THERE THROUGH FRIDAY NIGHT. WITH SEVERAL ROUNDS OF SHOWERS AND STORMS IN THE FORECAST...WILL CONTINUE TO MONITOR THE POSSIBILITY OF SOME LOCALIZED FLOODING ACROSS THE SOUTH. THE 12Z GFS AND ECMWF HAVE BOTH NUDGED QPF A TAD FURTHER SOUTH FOR SATURDAY AND SUNDAY THAN THEY HAD IN EARLIER RUNS...SO OPTED TO LOWER OR TAKE OUT POPS ACROSS THE NORTHERN HALF OF THE FA THROUGH THE WEEKEND. KEPT CHANCE POPS IN ACROSS THE SOUTH WHILE THE FRONT LINGERS NEAR THE OHIO RIVER. BY MONDAY A MID LEVEL TROUGH OVER EASTERN CANADA WILL BEGIN TO AMPLIFY...RESULTING IN NW FLOW OVER THE OHIO VALLEY BY THE MIDDLE OF NEXT WEEK. MEANWHILE SURFACE HIGH PRESSURE WILL BUILD OVER THE GREAT LAKES WHICH SHOULD PROVIDE A PERIOD OF DRIER WEATHER FOR TUESDAY AND WEDNESDAY. TEMPERATURES THROUGH THE PERIOD WILL REMAIN A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE UPPER 70S TO LOWER 80S. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... COLD FRONT IS APPROACHING CWA THIS EVENING AND SHOULD BE IN THE DAYTON VICINITY SHORTLY AFTER MIDNIGHT AND ALONG THE I-71 CORRIDOR BY DAYBREAK. CU FIELD DID NOT HAVE ENOUGH DAYLIGHT AS IT TOOK TOO LONG FOR THE STRATUS TO BREAK UP AND ONLY EASTERN AREAS OF CWA OUTSIDE OF TAFS SAW ANY SHOWER/THUNDERSTORM ACTIVITY THIS AFTERNOON. SOME STORMS ARE TRYING TO GET GOING SOUTH OF CINCINNATI BUT WILL NOT RECEIVE THE BENEFIT OF DAYLIGHT TO HELP THEM CONTINUE THIS EVENING AND ARE EXPECTED TO DIE OUT. AS THE FRONT APPROACHES...SOME STORMS MAY OCCUR WITH THEM BUT THEY SHOULD BE FEW AND FAR BETWEEN SO I LEFT THEM OUT OF THE TERMINAL FORECASTS IN FAVOR OF UPDATING WHEN IT IS APPARENT THE TAF SITES WILL BE AFFECTED. THIS HOLDS TRUE FOR EARLY TOMORROW AS WELL. STRATUS IS EXPECTED AGAIN TONIGHT ESPECIALLY AS THERE IS NOT MUCH IN THE LINES OF MID/HIGH CLOUDS AND THE LOWER ATMOSPHERE SHOULD RADIATE NICELY. THINK THAT LIFR CIGS/VSBYS ARE POSSIBLE OVERNIGHT IN ANY LOCATION BUT MORE LIKELY TOWARDS CINCINNATI METRO. MODELS ARE NOT HANDLING THE AIRMASS WELL AND A LOT OF UNCERTAINTY EXISTS IN TONIGHTS FORECAST AND WILL LIKELY EXTEND INTO THE NEXT 24-48 HOURS AS THE FRONT STALLS OVER THE REGION. TIMING...PLACEMENT...AND EVEN OCCURRENCE ISSUES WILL ABOUND WITH ANY STORMS THE NEXT FEW DAYS. OUTLOOK...THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE AT TIMES THROUGH FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...FRANKS/HICKMAN SHORT TERM...HICKMAN LONG TERM...KURZ AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
713 PM EDT WED AUG 7 2013 .SYNOPSIS... A COLD FRONT WILL SLOWLY PUSH INTO THE REGION TONIGHT AND THURSDAY. THE FRONT WILL EVENTUALLY STALL CLOSE TO THE OHIO RIVER BY FRIDAY MORNING. THIS FRONTAL BOUNDARY WILL THEN OSCILLATE NEAR THE OHIO RIVER THROUGH THE WEEKEND. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE PERIOD...ESPECIALLY FOR THOSE LOCATIONS CLOSER TO THE FRONTAL BOUNDARY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... HAVE USED A BLEND OF THE HRRR AND NAM FOR THE NEAR TERM FORECAST. A COLD FRONT WAS POISED TO OUR NORTHWEST THIS EVENING. THIS FRONT IS FORECAST TO SLOWLY SINK SOUTHEAST TOWARD THE AREA OVERNIGHT. CURRENT THINKING IS THAT CONVECTIVE ACTIVITY NEAR THE FRONT WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING AND FORCING. LATEST MODEL RUNS NOW SUGGEST THAT SUBTLE LOW LEVEL JET AND ASSOCIATED UPR LVL DISTURBANCE WILL LIKELY STAY TO OUR SOUTH AND SOUTHWEST OVERNIGHT. AS A RESULT...WITH VERY WEAK FORCING...CAN NOT SEE GOING MUCH HIGHER THAN 30 POPS FOR ALL LOCATIONS. WILL UPDATE THE ZONES TO REFLECT THIS. WILL ALSO REMOVE HEAVY RAIN THREAT GIVEN SPARSE COVERAGE. AMPLE LOW LEVEL MOISTURE AND DIMINISHING WINDS WILL MAKE FOG AND/OR STRATUS A CONCERN AFTER MIDNIGHT...ESPECIALLY IF HOLES CAN DEVELOP IN THE MID AND UPPER LEVEL CLOUDS. WILL CONTINUE TO MENTION AREAS OF FOG IN THE ZONES AFTER MIDNIGHT AS WELL AS IN THE HWO. LOWS WILL RANGE FROM THE UPPER 60S NW TO THE LOWER 70S ELSEWHERE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THE LOWER GREAT LAKES AND OHIO VALLEY REGION WILL BE BETWEEN A LARGE ANOMALOUS UPR LVL LOW OVER ONTARIO AND A MID LVL SUBTROPICAL RIDGE OVER THE SRN STATES THROUGH THE SHORT TERM PERIOD. THIS SETUP WILL ONLY ALLOW AFOREMENTIONED FRONTAL SYSTEM TO MOVE EVER SO SLOWLY TO SOUTHEAST...EVENTUALLY STALLING NEAR THE OHIO RIVER BY FRIDAY MORNING AS MID LEVEL FLOW BECOMES ZONAL. THE FRONT WILL PROVIDE THE FOCUS FOR SHOWERS AND STORMS THROUGH THE PERIOD...BUT THE TIMING AND AREAL COVERAGE WILL BE PROBLEMATIC AS MODELS ARE ESSENTIALLY OFFERING DIFFERENT SOLUTIONS. HAVE GONE WITH A NAM/ECMWF BLEND WHICH IS FORECASTING A SLOWER FRONTAL MOVEMENT. AS SUCH...THERE IS A HINT OF A FRONTAL WAVE RIPPLING ALONG THE FRONT ON THURSDAY THROUGH THE HEART OF THE FORECAST AREA. THIS WAVE AND ANY UPR LVL SUPPORT FROM AN ASSOCIATED DISTURBANCE OR MCV SHOULD PROVIDE THE BEST CHANCE FOR SHOWERS AND STORMS ALONG AND SOUTHEAST OF THE LOW. HAVE HIGHEST POPS MAINLY FOR POINTS ALONG AND SOUTHEAST OF INTERSTATE 71 WITH THE DIURNAL CYCLE PLAYING A ROLE IN TERMS OF BEST COVERAGE. LOOKS LIKE WAVE MOVES OFF TO THE NORTHEAST THURSDAY NIGHT...WHICH SHOULD RESULT IN A DOWN TICK IN SHOWER/THUNDERSTORMS COVERAGE IN ITS WAKE. THE AIRMASS WILL BE QUITE MOIST ALONG AND AHEAD OF THE FRONT WITH PWATS OF 2 INCHES PLUS EXPECTED. IN ADDITION...WARM CLOUD DEPTHS WILL BE CLOSE TO 4 KM WHICH WOULD FAVOR COLLISION/COALESCENCE PROCESSES AND THE POTENTIAL FOR HEAVY RAIN. GIVEN THE UNCERTAINTY IN PLACEMENT OF HEAVIEST RAIN WITH UPCOMING ROUNDS OF SHOWERS AND STORMS...WILL CONTINUE TO HIGHLIGHT THE HEAVY RAIN THREAT/LOCAL FLOODING ISSUES IN THE HWO WITH AN EMPHASIS PLACED ACRS THE SRN CWFA CLOSER TO THE FRONTAL BOUNDARY. HIGHS ON THURSDAY SHOULD BE HELD DOWN BY CLOUDS AND PCPN...WITH LOWER TO MID 80S EXPECTED. LOWS THURSDAY NIGHT WILL RANGE FROM THE MID 60S NW TO THE LOWER 70S SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... MAIN FOCUS FOR THE FIRST PART OF THE EXTENDED PERIOD WILL BE A SURFACE FRONTAL BOUNDARY THAT WILL ORIENT ITSELF ALONG THE OHIO RIVER FRIDAY MORNING. WITH ZONAL FLOW ALOFT...THIS BOUNDARY WILL VERY SLOWLY SAG SOUTHWARD THROUGH THE WEEKEND. ONE WAVE OF LOW PRESSURE RIDING ALONG THE FRONT WILL BE EXITING TO THE NORTHEAST AT THE START OF THE PERIOD...ONLY TO BE FOLLOWED BY ANOTHER RIPPLE FRIDAY NIGHT INTO SATURDAY. SOUTHERN PORTIONS OF THE FA WILL SEE THE GREATEST CHANCE FOR RAIN THROUGH THE WEEKEND AND LATEST DETERMINISTIC RUNS CONTINUE TO INDICATE PW VALUES IN THE 150 TO 175 PERCENT OF NORMAL RANGE THERE THROUGH FRIDAY NIGHT. WITH SEVERAL ROUNDS OF SHOWERS AND STORMS IN THE FORECAST...WILL CONTINUE TO MONITOR THE POSSIBILITY OF SOME LOCALIZED FLOODING ACROSS THE SOUTH. THE 12Z GFS AND ECMWF HAVE BOTH NUDGED QPF A TAD FURTHER SOUTH FOR SATURDAY AND SUNDAY THAN THEY HAD IN EARLIER RUNS...SO OPTED TO LOWER OR TAKE OUT POPS ACROSS THE NORTHERN HALF OF THE FA THROUGH THE WEEKEND. KEPT CHANCE POPS IN ACROSS THE SOUTH WHILE THE FRONT LINGERS NEAR THE OHIO RIVER. BY MONDAY A MID LEVEL TROUGH OVER EASTERN CANADA WILL BEGIN TO AMPLIFY...RESULTING IN NW FLOW OVER THE OHIO VALLEY BY THE MIDDLE OF NEXT WEEK. MEANWHILE SURFACE HIGH PRESSURE WILL BUILD OVER THE GREAT LAKES WHICH SHOULD PROVIDE A PERIOD OF DRIER WEATHER FOR TUESDAY AND WEDNESDAY. TEMPERATURES THROUGH THE PERIOD WILL REMAIN A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE UPPER 70S TO LOWER 80S. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... STUBBORN STRATUS AND FOG THAT AFFECTED THE MAJORITY OF THE TAFS THIS MORNING HAS FINALLY LIFTED TO VFR. IT HAS LIMITED THE INSTABILITY SO FAR...BUT LATEST RADAR LOOP IS SHOWING SOME DEVELOPMENT ACROSS THE WRN TAFS...WITH SLIGHTLY BETTER INSTABILITY JUST TO THEIR E. POP UP CONVECTION WILL BE POSSIBLE THOUGH THE AFTN HOURS DUE TO THE HEATING OF THE DAY. EXPECT A LULL BETWEEN 00-06Z...BEFORE ANOTHER CHANCE OF CONVECTION AFT 06Z...ASSOCIATED WITH A CDFNT THAT IS SCHEDULED TO PUSH IN AFT 06Z. WENT WITH JUST A VCTS DUE TO THE UNCERTAINTY OVERNIGHT. AM CONCERNED ABOUT THE REDEVELOPMENT OF MVFR/IFR ST AND FOG LATE AFT 09Z. WENT WITH MVFR CONDITIONS IN THE TAFS...BUT SOME LOWER CONDITIONS ARE POSSIBLE. EXPECT THE ST TO LINGER INTO LATE MORNING LIKE IT DID THIS MORNING. OUTLOOK...THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE AT TIMES THROUGH FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...KURZ AVIATION...SITES
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
101 PM EDT TUE AUG 6 2013 .SYNOPSIS... INSTABILITY INCREASES LATE TODAY AND OVERNIGHT. STRONGER MID LEVEL DISTURBANCE PASSES WEDNESDAY. MORE ROUNDS OF CONVECTION INTO THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... ONCE YOU GET SPOILED BY THOSE RARE LOWER DEW POINTS IN THE DOG DAYS OF SUMMER...YOU HATE TO SEE THEM LEAVE. THE INITIAL MID LEVEL DISTURBANCE WAS CROSSING THE CENTRAL WV MOUNTAINS THIS EARLY HOUR OF 08Z. A SECONDARY 500 MB VORT IS INDICATED ON THE 07Z RAP MODEL PASSING N OF BKW AROUND 09-10Z. MEANWHILE...WHILE THE MID LEVEL MOISTURE INCREASED FROM THE WEST LAST NIGHT...THE LOWER LEVEL MOISTURE MADE ITS FASTEST INITIAL CHARGE NORTH...ON THE EASTERN SLOPES OF THE APPALACHIANS. YET...THE 925 TO 850 MB FLOW REMAINS WEAK AND STARTS VEERING MORE TOWARD SOUTH AND SOUTHWEST. SO TOUGH CLOUD FORECAST TODAY FOR AREAS FROM BKW EAST INTO THE UPPER GREENBRIER VALLEY. MEANWHILE...IN THE WAKE OF THE MID LEVEL DISTURBANCE...BREAKS IN THE CLOUDS COULD YIELD SOME BRIEF FOG IN THE MID OHIO VALLEY FOR DAWN. NO MAJOR CHANGES TODAY...KEPT A 20/30 POPS OVER THE MOUNTAINS FOR THE AFTERNOON HEATING IN THE WEAK FLOW. ALSO KEPT THE POSSIBILITY OF CONVECTION FORMING FOR OUR NE KENTUCKY AND THE TRI STATE AROUND HTS AFTER 18Z. MOST MODELS LIKE THE ECMWF...GFS HOLD US DRY OVERNIGHT. BUT NAM SHOWS MINOR FEATURES WITH INCREASING LOW LEVEL WINDS/FORCING AT 925 MB TO 850 MBS. IT IS TOO PREMATURE TO REMOVE POPS IN OUR SOUTHERN AND WESTERN COUNTIES FOR TONIGHT. I DID TRY TO HOLD THE ROUTE 50 CORRIDOR INCLUDING PKB TO CKB DRY MOST OF THE NIGHT. HAVE POPS INCREASING INTO THE 30 TO 40 PERCENT RANGE ACROSS THE SOUTH OVERNIGHT. CERTAINLY THE LONGER WE CAN HOLD OFF AREAS OF HEAVIER CONVECTION THE BETTER...CONSIDERING THE ACTIVE PATTERN INTO THIS WEEKEND. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... NEW 00Z MODELS LEAVE SOME QUESTION TO HOW THINGS WILL PLAY OUT THROUGH THE SHORT TERM...AS ECMWF HAS MOVED BEST UPPER LEVEL SUPPORT FARTHER NORTH WHILE NAM/GFS HAVE BEEN FAIRLY CONSISTENT WITH PREVIOUS RUNS LOCATION WISE. ALL MODELS HAVE SLOWED DOWN A BIT WITH THE PRECIP FOR WEDNESDAY...SO TRENDED THAT WAY. DESPITE THE MODEL DIFFERENCES...THUNDERSTORMS LIKELY WEDNESDAY INTO WEDNESDAY NIGHT AND WITH PW VALUES CLIMBING ABOVE 2 INCHES HEAVY RAIN IS ALSO LIKELY. TRAIN OF VORT MAXES CONTINUES AS COLD FRONT APPROACHES THURSDAY THROUGH FRIDAY. GFS STILL SHOWS THE COLD FRONT TRYING TO PUSH THROUGH FRIDAY NIGHT...HOWEVER NEW ECMWF STALLS THE SURFACE FRONT NEAR TO JUST NORTH OF CWA. THINK THE ECMWF MAY BE ON TO SOMETHING...BUT WITH THIS BEING THE FIRST INDICATION...WON/T JUMP FULLY ON IT YET. DID INCREASE LOWS FRIDAY NIGHT QUITE A BIT...WITH ONLY MINIMAL CHANGES MADE TO OTHER TEMPS. WILL CONTINUE WATER CONCERN MENTION IN HWO. THINK MOST LOCATIONS SHOULD BE ABLE TO HANDLE WEDNESDAYS BATCH OF HEAVY RAIN SINCE WE HAVE HAD SOME TIME TO DRY OUT SINCE LAST SIGNIFICANT RAIN...SO AM MORE CONCERNED WITH REPETITIVE STORMS ADDING UP THROUGH THE END OF THE WEEK. WITH THAT SAID...CAN NOT RULE OUT LOCALIZED ISSUES WEDNESDAY DUE TO DOWNPOURS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... GENERALLY USED WPC THINKING FOR THIS PORTION OF THE FORECAST. HOWEVER...HAVE MADE SOME CHANGES TO REFLECT DIFFERENCES IN LATEST MODEL GUIDANCE. WPC INDICATES A COLD FRONT SHOULD BE LOCATED JUST TO OUR NORTHWEST EARLY IN THE PERIOD. THE COLD FRONT WILL PUSH SOUTHEAST SATURDAY AND SATURDAY NIGHT. SEVERAL MID-LEVEL SHORTWAVES AND A WEAK AREA OF LOW PRESSURE WILL THEN PUSH EAST MONDAY INTO TUESDAY. LATEST GFS IS SLOWER WITH THE SOUTHEAST PROGRESS OF THE COLD FRONT. WITH THIS IN MIND...HAVE HELD ONTO LOW POPS A LITTLE LONGER FOR SATURDAY NIGHT INTO SUNDAY. LOWERED HPC TEMP NUMBERS A FEW DEGREES AS THEY APPEAR TOO WARM FOR THE EXPECTED CONDITIONS. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... THE MID LEVEL DISTURBANCE CROSSING THE WV MOUNTAINS BETWEEN EKN AND BKW AT 10Z. WITH BREAKS IN THE CLOUDS IN ITS WAKE...AREAS OF IFR/LIFR IN FOG FORMING LATE...IN WAKE OF THE RAIN SHOWERS...FROM EASTERN OHIO ACROSS NORTHERN WEST VIRGINIA INCLUDING PKB TO CKB...AND EVEN TOWARD W22 AND EKN...FOR A BRIEF TIME AROUND 10Z TO 12Z. MAINLY MVFR IN FOG FURTHER SOUTH TOWARD CRW AND THE SOUTHERN WV COAL FIELDS. THE UPSLOPE FLOW ALONG THE EASTERN SLOPES OF THE APPALACHIANS IS WEAK AND BECOMES MORE SOUTHERLY BY MIDDAY TODAY. THIS LOWERS MY CONFIDENCE IN THE CEILINGS ALONG THE SPINE OF THE APPALACHIANS ON EAST INTO THE GREENBRIER VALLEY. BECKLEY IN THE SOUTHERN MOUNTAINS MAY BE ON THE WESTERN FRINGE OF THIS MAXIMUM IN LOW LEVEL MOISTURE THIS MORNING...SO HAVE A SCATTERED TO BROKEN DECK THERE AROUND 2 THSD FT AGL. IN DAYTIME HEATING HAVE SCATTERED TO BROKEN CLOUDS MOSTLY 2 TO 4 THSD FT AGL EXCEPT 4 TO 6 THSD FT ACROSS NORTHERN WV LOWLANDS. A FEW SHOWERS OR THUNDERSTORMS COULD FORM IN THE AFTERNOON HEATING OVER THE MOUNTAINOUS COUNTIES. INSTABILITY INCREASES IN THE TRI STATE VCNTY OF HTS BY 21Z INCLUDING EASTERN KENTUCKY...SO SOME THUNDERSTORMS COULD DEVELOP THERE LATE TODAY AND LINGER TONIGHT. WITH MOISTURE INCREASING AT 850 MB AND BELOW WEST OF THE MOUNTAINS TONIGHT...HAVE MORE WIDESPREAD CEILINGS A 3 TO 4 THSD FT DEVELOPING 00Z TO 06Z WEDNESDAY IN THE WESTERN LOWLANDS. VSBY COULD BE 5 TO 6 MILES IN HAZE WITH INCREASING SURFACE DEW POINTS. INSTABILITY LINGERS OVERNIGHT...SO HAVE CHANCE POPS FOR CONVECTION CREEPING NE INTO CENTRAL WV AND CRW VCNTY. EXPECTING DRY CONDITIONS TO HOLD PKB TO CKB VCNTY OVERNIGHT THRU 12Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: EARLY MORNING FOG IN WAKE OF THE RAIN COULD LINGER AN HOUR LONGER. COVERAGE AND TIMING OF ANY OVERNIGHT CONVECTION COULD VARY. 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 M M H H H H H H H H H H HTS CONSISTENCY M M H H H H H H H H H H BKW CONSISTENCY M M M M M M H H H H M M EKN CONSISTENCY L M M H H H H H H H H H PKB CONSISTENCY L L H H H H H H H H H H CKB CONSISTENCY L L H H H H H H H H H H AFTER 18Z WEDNESDAY... IFR POSSIBLE IN ROUNDS OF CONVECTION WEDNESDAY INTO SATURDAY. IN HUMID AIR IFR CEILINGS COULD EVEN DEVELOP OUTSIDE THE CONVECTION... ESPECIALLY AT NIGHT AND INTO THE MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...JSH AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
556 AM EDT TUE AUG 6 2013 .SYNOPSIS... WEAK DISTURBANCE EXITS THE MOUNTAIN COUNTIES THIS MORNING. INSTABILITY INCREASES LATE TODAY AND OVERNIGHT. STRONGER MID LEVEL DISTURBANCE PASSES WEDNESDAY. MORE ROUNDS OF CONVECTION INTO THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... ONCE YOU GET SPOILED BY THOSE RARE LOWER DEW POINTS IN THE DOG DAYS OF SUMMER...YOU HATE TO SEE THEM LEAVE. THE INITIAL MID LEVEL DISTURBANCE WAS CROSSING THE CENTRAL WV MOUNTAINS THIS EARLY HOUR OF 08Z. A SECONDARY 500 MB VORT IS INDICATED ON THE 07Z RAP MODEL PASSING N OF BKW AROUND 09-10Z. MEANWHILE...WHILE THE MID LEVEL MOISTURE INCREASED FROM THE WEST LAST NIGHT...THE LOWER LEVEL MOISTURE MADE ITS FASTEST INITIAL CHARGE NORTH...ON THE EASTERN SLOPES OF THE APPALACHIANS. YET...THE 925 TO 850 MB FLOW REMAINS WEAK AND STARTS VEERING MORE TOWARD SOUTH AND SOUTHWEST. SO TOUGH CLOUD FORECAST TODAY FOR AREAS FROM BKW EAST INTO THE UPPER GREENBRIER VALLEY. MEANWHILE...IN THE WAKE OF THE MID LEVEL DISTURBANCE...BREAKS IN THE CLOUDS COULD YIELD SOME BRIEF FOG IN THE MID OHIO VALLEY FOR DAWN. NO MAJOR CHANGES TODAY...KEPT A 20/30 POPS OVER THE MOUNTAINS FOR THE AFTERNOON HEATING IN THE WEAK FLOW. ALSO KEPT THE POSSIBILITY OF CONVECTION FORMING FOR OUR NE KENTUCKY AND THE TRI STATE AROUND HTS AFTER 18Z. MOST MODELS LIKE THE ECMWF...GFS HOLD US DRY OVERNIGHT. BUT NAM SHOWS MINOR FEATURES WITH INCREASING LOW LEVEL WINDS/FORCING AT 925 MB TO 850 MBS. IT IS TOO PREMATURE TO REMOVE POPS IN OUR SOUTHERN AND WESTERN COUNTIES FOR TONIGHT. I DID TRY TO HOLD THE ROUTE 50 CORRIDOR INCLUDING PKB TO CKB DRY MOST OF THE NIGHT. HAVE POPS INCREASING INTO THE 30 TO 40 PERCENT RANGE ACROSS THE SOUTH OVERNIGHT. CERTAINLY THE LONGER WE CAN HOLD OFF AREAS OF HEAVIER CONVECTION THE BETTER...CONSIDERING THE ACTIVE PATTERN INTO THIS WEEKEND. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... NEW 00Z MODELS LEAVE SOME QUESTION TO HOW THINGS WILL PLAY OUT THROUGH THE SHORT TERM...AS ECMWF HAS MOVED BEST UPPER LEVEL SUPPORT FARTHER NORTH WHILE NAM/GFS HAVE BEEN FAIRLY CONSISTENT WITH PREVIOUS RUNS LOCATION WISE. ALL MODELS HAVE SLOWED DOWN A BIT WITH THE PRECIP FOR WEDNESDAY...SO TRENDED THAT WAY. DESPITE THE MODEL DIFFERENCES...THUNDERSTORMS LIKELY WEDNESDAY INTO WEDNESDAY NIGHT AND WITH PW VALUES CLIMBING ABOVE 2 INCHES HEAVY RAIN IS ALSO LIKELY. TRAIN OF VORT MAXES CONTINUES AS COLD FRONT APPROACHES THURSDAY THROUGH FRIDAY. GFS STILL SHOWS THE COLD FRONT TRYING TO PUSH THROUGH FRIDAY NIGHT...HOWEVER NEW ECMWF STALLS THE SURFACE FRONT NEAR TO JUST NORTH OF CWA. THINK THE ECMWF MAY BE ON TO SOMETHING...BUT WITH THIS BEING THE FIRST INDICATION...WON/T JUMP FULLY ON IT YET. DID INCREASE LOWS FRIDAY NIGHT QUITE A BIT...WITH ONLY MINIMAL CHANGES MADE TO OTHER TEMPS. WILL CONTINUE WATER CONCERN MENTION IN HWO. THINK MOST LOCATIONS SHOULD BE ABLE TO HANDLE WEDNESDAYS BATCH OF HEAVY RAIN SINCE WE HAVE HAD SOME TIME TO DRY OUT SINCE LAST SIGNIFICANT RAIN...SO AM MORE CONCERNED WITH REPETITIVE STORMS ADDING UP THROUGH THE END OF THE WEEK. WITH THAT SAID...CAN NOT RULE OUT LOCALIZED ISSUES WEDNESDAY DUE TO DOWNPOURS. && .LONG TERM /SATURDAY THROUGH MONDAY/... USED WPC THINKING FOR THIS PORTION OF THE FORECAST...WITH SOME MINOR TWEAKS. A COLD FRONT SHOULD BE LOCATED JUST TO OUR SOUTHEAST SATURDAY. A REINFORCING COLD FRONT SHOULD THEN PUSH SOUTHEAST SATURDAY/SATURDAY NIGHT...BEFORE WEAK HIGH PRESSURE TAKES CONTROL BY MONDAY. BELOW NORMAL TEMPERATURES SHOULD PREVAIL THROUGH THE PERIOD. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... THE MID LEVEL DISTURBANCE CROSSING THE WV MOUNTAINS BETWEEN EKN AND BKW AT 10Z. WITH BREAKS IN THE CLOUDS IN ITS WAKE...AREAS OF IFR/LIFR IN FOG FORMING LATE...IN WAKE OF THE RAIN SHOWERS...FROM EASTERN OHIO ACROSS NORTHERN WEST VIRGINIA INCLUDING PKB TO CKB...AND EVEN TOWARD W22 AND EKN...FOR A BRIEF TIME AROUND 10Z TO 12Z. MAINLY MVFR IN FOG FURTHER SOUTH TOWARD CRW AND THE SOUTHERN WV COAL FIELDS. THE UPSLOPE FLOW ALONG THE EASTERN SLOPES OF THE APPALACHIANS IS WEAK AND BECOMES MORE SOUTHERLY BY MIDDAY TODAY. THIS LOWERS MY CONFIDENCE IN THE CEILINGS ALONG THE SPINE OF THE APPALACHIANS ON EAST INTO THE GREENBRIER VALLEY. BECKLEY IN THE SOUTHERN MOUNTAINS MAY BE ON THE WESTERN FRINGE OF THIS MAXIMUM IN LOW LEVEL MOISTURE THIS MORNING...SO HAVE A SCATTERED TO BROKEN DECK THERE AROUND 2 THSD FT AGL. IN DAYTIME HEATING HAVE SCATTERED TO BROKEN CLOUDS MOSTLY 2 TO 4 THSD FT AGL EXCEPT 4 TO 6 THSD FT ACROSS NORTHERN WV LOWLANDS. A FEW SHOWERS OR THUNDERSTORMS COULD FORM IN THE AFTERNOON HEATING OVER THE MOUNTAINOUS COUNTIES. INSTABILITY INCREASES IN THE TRI STATE VCNTY OF HTS BY 21Z INCLUDING EASTERN KENTUCKY...SO SOME THUNDERSTORMS COULD DEVELOP THERE LATE TODAY AND LINGER TONIGHT. WITH MOISTURE INCREASING AT 850 MB AND BELOW WEST OF THE MOUNTAINS TONIGHT...HAVE MORE WIDESPREAD CEILINGS A 3 TO 4 THSD FT DEVELOPING 00Z TO 06Z WEDNESDAY IN THE WESTERN LOWLANDS. VSBY COULD BE 5 TO 6 MILES IN HAZE WITH INCREASING SURFACE DEW POINTS. INSTABILITY LINGERS OVERNIGHT...SO HAVE CHANCE POPS FOR CONVECTION CREEPING NE INTO CENTRAL WV AND CRW VCNTY. EXPECTING DRY CONDITIONS TO HOLD PKB TO CKB VCNTY OVERNIGHT THRU 12Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: EARLY MORNING FOG IN WAKE OF THE RAIN COULD LINGER AN HOUR LONGER. COVERAGE AND TIMING OF ANY OVERNIGHT CONVECTION COULD VARY. 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 TUE 08/06/13 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY H M M H M H H H H H H H HTS CONSISTENCY H M M M M H H H H H H H BKW CONSISTENCY M M M M M M M M M H H H EKN CONSISTENCY H M M H H M H H H H H H PKB CONSISTENCY L L L L H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z WEDNESDAY... IFR POSSIBLE IN ROUNDS OF CONVECTION WEDNESDAY INTO SATURDAY. IN HUMID AIR IFR CEILINGS COULD EVEN DEVELOP OUTSIDE THE CONVECTION... ESPECIALLY AT NIGHT AND INTO THE MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...JSH AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
430 AM EDT TUE AUG 6 2013 .SYNOPSIS... WEAK DISTURBANCE EXITS THE MOUNTAIN COUNTIES THIS MORNING. INSTABILITY INCREASES LATE TODAY AND OVERNIGHT. STRONGER MID LEVEL DISTURBANCE PASSES WEDNESDAY. MORE ROUNDS OF CONVECTION INTO THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... ONCE YOU GET SPOILED BY THOSE RARE LOWER DEW POINTS IN THE DOG DAYS OF SUMMER...YOU HATE TO SEE THEM LEAVE. THE INITIAL MID LEVEL DISTURBANCE WAS CROSSING THE CENTRAL WV MOUNTAINS THIS EARLY HOUR OF 08Z. A SECONDARY 500 MB VORT IS INDICATED ON THE 07Z RAP MODEL PASSING N OF BKW AROUND 09-10Z. MEANWHILE...WHILE THE MID LEVEL MOISTURE INCREASED FROM THE WEST LAST NIGHT...THE LOWER LEVEL MOISTURE MADE ITS FASTEST INITIAL CHARGE NORTH...ON THE EASTERN SLOPES OF THE APPALACHIANS. YET...THE 925 TO 850 MB FLOW REMAINS WEAK AND STARTS VEERING MORE TOWARD SOUTH AND SOUTHWEST. SO TOUGH CLOUD FORECAST TODAY FOR AREAS FROM BKW EAST INTO THE UPPER GREENBRIER VALLEY. MEANWHILE...IN THE WAKE OF THE MID LEVEL DISTURBANCE...BREAKS IN THE CLOUDS COULD YIELD SOME BRIEF FOG IN THE MID OHIO VALLEY FOR DAWN. NO MAJOR CHANGES TODAY...KEPT A 20/30 POPS OVER THE MOUNTAINS FOR THE AFTERNOON HEATING IN THE WEAK FLOW. ALSO KEPT THE POSSIBILITY OF CONVECTION FORMING FOR OUR NE KENTUCKY AND THE TRI STATE AROUND HTS AFTER 18Z. MOST MODELS LIKE THE ECMWF...GFS HOLD US DRY OVERNIGHT. BUT NAM SHOWS MINOR FEATURES WITH INCREASING LOW LEVEL WINDS/FORCING AT 925 MB TO 850 MBS. IT IS TOO PREMATURE TO REMOVE POPS IN OUR SOUTHERN AND WESTERN COUNTIES FOR TONIGHT. I DID TRY TO HOLD THE ROUTE 50 CORRIDOR INCLUDING PKB TO CKB DRY MOST OF THE NIGHT. HAVE POPS INCREASING INTO THE 30 TO 40 PERCENT RANGE ACROSS THE SOUTH OVERNIGHT. CERTAINLY THE LONGER WE CAN HOLD OFF AREAS OF HEAVIER CONVECTION THE BETTER...CONSIDERING THE ACTIVE PATTERN INTO THIS WEEKEND. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... NEW 00Z MODELS LEAVE SOME QUESTION TO HOW THINGS WILL PLAY OUT THROUGH THE SHORT TERM...AS ECMWF HAS MOVED BEST UPPER LEVEL SUPPORT FARTHER NORTH WHILE NAM/GFS HAVE BEEN FAIRLY CONSISTENT WITH PREVIOUS RUNS LOCATION WISE. ALL MODELS HAVE SLOWED DOWN A BIT WITH THE PRECIP FOR WEDNESDAY...SO TRENDED THAT WAY. DESPITE THE MODEL DIFFERENCES...THUNDERSTORMS LIKELY WEDNESDAY INTO WEDNESDAY NIGHT AND WITH PW VALUES CLIMBING ABOVE 2 INCHES HEAVY RAIN IS ALSO LIKELY. TRAIN OF VORT MAXES CONTINUES AS COLD FRONT APPROACHES THURSDAY THROUGH FRIDAY. GFS STILL SHOWS THE COLD FRONT TRYING TO PUSH THROUGH FRIDAY NIGHT...HOWEVER NEW ECMWF STALLS THE SURFACE FRONT NEAR TO JUST NORTH OF CWA. THINK THE ECMWF MAY BE ON TO SOMETHING...BUT WITH THIS BEING THE FIRST INDICATION...WON/T JUMP FULLY ON IT YET. DID INCREASE LOWS FRIDAY NIGHT QUITE A BIT...WITH ONLY MINIMAL CHANGES MADE TO OTHER TEMPS. WILL CONTINUE WATER CONCERN MENTION IN HWO. THINK MOST LOCATIONS SHOULD BE ABLE TO HANDLE WEDNESDAYS BATCH OF HEAVY RAIN SINCE WE HAVE HAD SOME TIME TO DRY OUT SINCE LAST SIGNIFICANT RAIN...SO AM MORE CONCERNED WITH REPETITIVE STORMS ADDING UP THROUGH THE END OF THE WEEK. WITH THAT SAID...CAN NOT RULE OUT LOCALIZED ISSUES WEDNESDAY DUE TO DOWNPOURS. && .LONG TERM /SATURDAY THROUGH MONDAY/... USED WPC THINKING FOR THIS PORTION OF THE FORECAST...WITH SOME MINOR TWEAKS. A COLD FRONT SHOULD BE LOCATED JUST TO OUR SOUTHEAST SATURDAY. A REINFORCING COLD FRONT SHOULD THEN PUSH SOUTHEAST SATURDAY/SATURDAY NIGHT...BEFORE WEAK HIGH PRESSURE TAKES CONTROL BY MONDAY. BELOW NORMAL TEMPERATURES SHOULD PREVAIL THROUGH THE PERIOD. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... THE OLD SQUEEZE PLAY...WITH THE LAST OF THE DRIER AIR EXITING. MID LEVEL DISTURBANCES IN THE WNW FLOW AT 700 MB CROSSING 06Z TO 12Z WILL CAUSE SOME SPOTTY LIGHT RAIN SHOWERS MAINLY CKB TO EKN VCNTY. MEANWHILE...FLOW AROUND 925 MB FROM THE EAST AND SOUTHEAST...WITH LOW LEVEL MOISTURE INCREASING NORTH...UP THE EASTERN SLOPES OF THE APPALACHIANS. THAT FLOW IN VERY WEAK AND BECOMES MORE SOUTHERLY BY MIDDAY TODAY. THIS LOWERS MY CONFIDENCE IN THE CEILINGS ALONG THE SPINE OF THE APPALACHIANS ON EAST INTO THE GREENBRIER VALLEY. BECKLEY IN THE SOUTHERN MOUNTAINS MAY BE ON THE WESTERN FRINGE OF THIS MAXIMUM IN LOW LEVEL MOISTURE THIS MORNING...SO HAVE A SCATTERED TO BROKEN DECK THERE AROUND 2 THSD FT AGL. THERE MAY BE SOME BREAKS IN THE MID CLOUDS OVER THE WESTERN LOWLANDS DURING THE PREDAWN...SO COULD STILL SEE SOME BRIEF 1 TO 3 MILES IN FOG TOWARD DAWN. A FEW SHOWERS OR THUNDERSTORMS COULD FORM IN THE AFTERNOON HEATING OVER THE MOUNTAINOUS COUNTIES. INSTABILITY INCREASES IN THE TRI STATE VCNTY OF HTS BY 21Z INCLUDING EASTERN KENTUCKY...SO SOME THUNDERSTORMS COULD DEVELOP THERE LATE TODAY AND LINGER INTO THIS EVENING. WITH MOISTURE INCREASING AT 850 MB AND BELOW WEST OF THE MOUNTAINS TONIGHT...HAVE MORE WIDESPREAD CEILINGS A 3 TO 4 THSD FT DEVELOPING 00Z TO 06Z WEDNESDAY IN THE WESTERN LOWLANDS. VSBY COULD BE 5 TO 6 MILES IN HAZE WITH INCREASING SURFACE DEW POINTS. INSTABILITY LINGERS OVERNIGHT...SO HAVE CHANCE POPS FOR CONVECTION CREEPING NE CENTRAL WV AND CRW VCNTY. SHOULD REMAIN DRY PKB TO CKB VCNTY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: IF MORE BREAKS DEVELOP SOONER...THICKER FOG COULD DEVELOP THAN FORECAST DURING THE 09Z TO 12Z TIME FRAME IN THE WESTERN LOWLANDS INCLUDING THE MID OHIO VALLEY. 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 TUE 08/06/13 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY H M M H M H H H H H H H HTS CONSISTENCY H M M M M H H H H H H H BKW CONSISTENCY M M M M M M M M M H H H EKN CONSISTENCY H M M H H M H H H H H H PKB CONSISTENCY L L L L H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 06Z WEDNESDAY... IFR POSSIBLE IN ROUNDS OF CONVECTION WEDNESDAY INTO SATURDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...JSH AVIATION...KTB
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
214 AM EDT TUE AUG 6 2013 .SYNOPSIS... WEAK DISTURBANCES WILL MOVE ACROSS THE AREA TONIGHT AND TUESDAY. A MORE PRONOUNCED SYSTEM WILL MOVE ACROSS THE AREA LATE TUESDAY NIGHT INTO WEDNESDAY. A COLD FRONT WILL MOVE THROUGH THE REGION WEDNESDAY NIGHT. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... ABUNDANT MOISTURE ALOFT IN NORTHWESTERLY FLOW IS HELPING TO BRING PATCHES OF SPRINKLES AND LIGHT RAIN ACROSS CENTRAL INDIANA AND CENTRAL OHIO THIS EVENING. THE TREND OVER THE PAST FEW HOURS HAS BEEN TO WEAKEN THE AREAS OF PRECIPITATION. HAVE FORECAST THESE SHOWERS TO GRADUALLY DISSIPATE AS THEY SHIFT EAST TO SOUTHEAST THROUGH THE LATE EVENING. OF NOTEWORTHINESS...LATEST RUC IS TRYING TO REDEVELOP SHOWERS ACROSS NORTHERN INDIANA EARLY IN THE MORNING AND THESE SHOWERS COULD MAKE IT TO OUR NORTHWESTERN ZONES AROUND SUNRISE. THIS MORNING ACTIVITY IS ALSO COARSELY DEPICTED IN THE 12Z ECMWF AND THEREFORE MAY NEED TO INTRODUCE POPS ACROSS THOSE ZONES AFTER 11Z IF THESE ADDITIONAL SHOWERS BEGIN TO FILL IN UPSTREAM OVER THE NEXT FEW HOURS. OTHERWISE...EXPECT MOSTLY CLOUDY SKIES WITH TEMPERATURES FALLING INTO THE UPPER 60S ACROSS THE WEST...TO THE UPPER 50S ACROSS OUR EASTERN ZONES. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/... A WEAK DISTURBANCE WILL BRING A CHANCE FOR SOME SHOWERS AND THUNDERSTORMS ACROSS THE FA ON TUESDAY. A MORE WELL DEFINED SHORT WAVE WILL APPROACH THE AREA TUESDAY NIGHT INTO WEDNESDAY. THIS FEATURE WILL BRING WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO THE AREA. MODELS HAVE BEEN INCONSISTENT WITH WHERE THE HEAVIEST RAIN WILL BE WITH THIS FEATURE. THE BEST CHANCE FOR HEAVIER RAINFALL WILL BE ACROSS SOUTHERN PORTIONS OF THE FA AND THEREFORE ADDED FLOODING POTENTIAL IN TO THE HWO ACROSS THIS AREA. DECIDED AGAINST A FLASH FLOOD WATCH DUE TO RELATIVELY HIGH FFG VALUES AND MODEL INCONSISTENCIES WITH WHERE THE HEAVIEST RAINFALL WILL OCCUR. ADDITIONAL PRECIPITATION WILL BE POSSIBLE ACROSS THE FA WEDNESDAY NIGHT AS A COLD FRONT MOVES THROUGH. SOUTHERLY FLOW ACROSS THE FA ON TUESDAY WILL ALLOW FOR TEMPERATURES TO RISE INTO THE 80S. TEMPERATURES ON WEDNESDAY WILL BE COOLER WITH HIGHS IN THE UPPER 70S TO LOWER 80S DUE TO MORE WIDESPREAD PRECIPITATION AND CLOUD COVER ACROSS THE FA. && .LONG TERM /THURSDAY THROUGH MONDAY/... MOST GUIDANCE HAS TRENDED TOWARDS A DRIER SOLUTION FOR THURSDAY. A WEAK FRONTAL BOUNDARY WILL REMAIN ACROSS THE SOUTH BUT FORCING DOES NOT LOOK PARTICULARLY STRONG AT THIS TIME. SO HAVE ONLY KEPT LOW CHANCE POPS IN FOR THAT PERIOD. CHANCE OF RAIN WILL INCREASE AGAIN LATE THURSDAY NIGHT AND PARTICULARLY INTO FRIDAY AS A WAVE MOVES ALONG THE STALLED FRONT. HAVE INCREASED POPS TO LIKELY ACROSS THE SOUTHERN COUNTIES. THIS WILL PUSH OFF TO THE EAST DURING FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND. THERE IS THE POTENTIAL FOR A WEAK SYSTEM TO SWING INTO THE REGION BY MONDAY. BUT SIGNAL IS NOT VERY STRONG AND AT DAY 7 HAVE KEPT ANY CHANCE OF RAIN RATHER LOW. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... NORTHWEST FLOW WITH MID TO HIGH LEVEL CLOUDS MOVING ACROSS THE AREA THROUGH THE EARLY MORNING HOURS. UPSTREAM OF THIS DECK...A LARGE AREA OF VFR LOW CLOUDS AROUND 5000 FEET APPEARS WILL SPREAD ACROSS OUR AREA. THE VFR LOW CLOUD DECK WILL LIKELY REMAIN ACROSS THE TAFS THROUGH THE DAY...BECOMING SCATTERED AT TIMES. SHOWERS WILL BECOME POSSIBLE LATE IN THE AFTERNOON WEST OF INTERSTATE 75...WITH THE BEST CHANCE FOR A SHOWER BEING AT KDAY. SINCE LIKELIHOOD IS LOW HAVE KEPT THE TAFS DRY THRU THE DAY. HAVE A MENTION OF VCSH AT 30 HOUR KCVG TAF SITE TOWARD SUNRISE WEDNESDAY WITH PRECIP APPROACHING FROM THE SW. OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY INTO THURSDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...NOVAK NEAR TERM...LATTO SHORT TERM...NOVAK LONG TERM... AVIATION...AR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
728 AM EDT TUE AUG 6 2013 .SYNOPSIS... AN INCREASINGLY MOIST AND UNSETTLED WEATHER PATTERN WILL PERSIST INTO THE FIRST PART OF THE WEEKEND...AS MULTIPLE FRONTS APPROACH AND EVENTUALLY MOVE ACROSS THE REGION. A GRADUAL WARMING TREND TO NEAR NORMAL TEMPERATURES IS EXPECTED THROUGH THE END OF THE WEEK...BEFORE ANOTHER SHOT OF SEASONABLY COOL AIR ARRIVES ON SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... IR SATL TRENDS SINCE MIDNIGHT HAVE DEPICTED A NOTABLE INCREASE IN LOW-MID LEVEL CLOUDS ACRS A GOOD PORTION OF THE CWA. THE IR SATL IMAGERY ALSO SHOWS FOG IN THE NRN RIVER/STREAM VALLEYS...WHERE AIR/WATER TEMP SPREADS ARE AGAIN RUNNING 25-30 DEGREES. VWP/S FROM IAD/BWI INDICATE THE 925-850MB FLOW HAS VEERED TO THE S-SW...AND LATEST RUC MESO ANALYSIS SHOW A MSTR AXIS /+13-15C 850MB DEWPTS/ EXTENDING NWD ALONG THE ERN SLOPES OF THE APPLCHNS ON THE WRN PERIPHERY OF DEPARTING SFC HIGH. THIS ENHANCED MSTR FLUX APPEARS TO BE OVERRUNNING A WARM FRONT OVER NRN VA WITH DEVELOPING SHOWERS STARTING TO PEEL NWD FROM THE MAIN W-E RAIN BAND TWD SRN MD. THEREFORE CANT RULE OUT AN ISOLD SHOWER OVER THE FAR S-CNTRL OR SERN ZONES PRIOR TO 12Z. WEAK BUT PERSISTENT LLVL WARM AIR/MSTR ADVECTION AND BROAD ISENT LIFT OVERRUNNING THE WARM FRONT OVER NRN VA WILL LKLY SUPPORT THE DEVELOPMENT OF SCT SHOWERS...SPREADING FROM SOUTH TO NORTH DURING THE MID-LATE MORNING THRU THE AFTN HOURS. SHORTWAVES EMBEDDED WITHIN THE SEASONABLY STRONG WNW FLOW ALOFT ON THE SRN PERIPHERY OF CLOSED/SLOW-MOVING UPPER LOW CENTERED OVER NRN MANITOBA/ONTARIO WILL PROVIDE ENOUGH LARGE SCALE LIFT TO AID IN SHOWER DEVELOPMENT. A FEW ISOLD THUNDERSTORMS WITH LOCALIZED HEAVY DOWNPOURS MAY ALSO DEVELOP IN THE AFTN...BUT FOR THE MOST PART INSTABILITY WILL BE WEAK WITH MEAN CAPES GENERALLY AOB 500 J/KG. MODEL QPFS ARE IN REASONABLY GOOD AGREEMENT IN KEEPING THE BETTER RAINFALL AXIS TO THE SOUTH OF THE MASON-DIXON LINE FROM SRN VA NEWD INTO DE...WITH JUST LGT AMTS /0.1-0.25 INCHES/ OVER CNTRL AND SERN PA. THE STEADILY INCREASING MSTR AND CLOUDS WILL KEEP MAX TEMPS IN THE LOW TO MID 70S...AVERAGING A FEW TO SEVERAL DEGREES BELOW NORMAL DEPENDING ON LOCATION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... THE AFOREMENTIONED WARM FRONT WILL LIFT NWD INTO CNTRL PA TONIGHT WITH BROAD LLVL SWLY FLOW CONTINUING TO ADVECT HIGHER PWS/60+ DEWPOINTS INTO THE AREA. MDL CONSENSUS STILL FAVORS THE ERN 1/2 TO 1/3 OF THE CWA WITH THE BEST CHC FOR LGT SHOWERS OVERNIGHT INTO EARLY WEDNESDAY MORNING. IN CONTRAST TO DAYTIME HIGHS...THICKENING CLOUDS PLUS INCREASING MSTR/DEWPOINTS WILL RESULT IN WARMER THAN AVG MIN TEMPS WITH READINGS IN THE LOW-MID 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... A ZONAL FLOW ACROSS THE NORTHERN CONUS WILL PREVAIL ACROSS THE REGION FROM WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. NUMEROUS EMBEDDED DISTURBANCES WILL ACT ON MONSOONAL MOISTURE FROM THE SOUTHWESTERN UNITED STATES AND NEARLY STATIONARY BOUNDARY LAYER FORCING TO PRODUCE A LOCALLY HEAVY RAIN/FLASH FLOOD THREAT ON THU- FRI BEFORE DRIER AND COOLER CONDS RETURN BY LATE SAT AND SUN. CLOUDS/PCPN SHOULD OFFSET WARMING ALOFT AND KEEP TEMPS NEAR TO SLIGHTLY BELOW AVG. MDL DATA INDICATES THE COLD FRONT WILL BECOME MUCH LESS PROGRESSIVE OR STALL OUT OVER THE UPPER OH VLY WED NGT INTO THUR. MODELS AND ENS MEANS CENTER AROUND THE GENERAL IDEA OF A MODERATELY SLOW PROGRESSION OF THE CLOSED LOW TRACKING EWD BTWN THE GRT LKS AND HUDSON BAY FROM THU THRU SAT. AT THE SFC...THE COLD FRONT TURN Q-STNRY BNDRY IN THE OH VLY...WHICH WAS ASSOCIATED WITH THE LEAD SHORTWAVE TROUGH...SHOULD PUSH SLOWLY EWD ACRS CNTRL PA ON DAY4/THU. THE SFC PATTERN GETS QUITE COMPLICATED FRI-SAT AS WPC PROGS SHOW THE FIRST BOUNDARY STALLING OUT OVER THE SRN MID- ATLC STATES AND SECONDARY COLD FRONT APPROACHING FROM THE GREAT LAKES. WAVES OF LOW PRESSURE RIDING NEWD ALONG THESE ENCROACHING FRONTS COULD KEEP UNSETTLED CONDS IN THE FCST THRU THE FIRST PART OF THE WEEKEND. ANOTHER PUSH OF WESTERLIES SHOULD OVERSPREAD THE AREA BY SUNDAY AND NUDGE THE SECOND FRONT EWD TO OR OFF THE COAST. A LARGE AREA OF CANADIAN HIGH PRESSURE SHOULD SUPPLY ANOTHER REFRESHINGLY COOL/DRY AIRMASS INTO THE GREAT LAKES AND NORTHEAST BY NEXT SUNDAY. DON`T EXPECT TEMPS TO FLUCTUATE VERY MUCH THRU THE MEDIUM RANGE...CONTINUING TO AVG NEAR TO SLIGHTLY BELOW NORMAL FOR EARLY AUGUST. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... S-SWLY RETURN FLOW ON THE WRN PERIPHERY OF DEPARTING HIGH PRES SLIDING OFF THE EAST COAST WILL BRING INCREASING MSTR AND THICKENING LOW-MID CLOUDS INTO CNTRL PA THRU TONIGHT. THE INCREASINGLY MOIST LLVL FLOW WILL OVERRUN A WARM FRONT LIFTING SLOWLY NWD FROM VA AND SUPPORT SCT SHOWERS /WITH ISOLD TSRA AND LOCALLY HVY DOWNPOURS/ INTO THE AFTN. THE S-CNTRL AND SERN AIRFIELDS STAND THE GREATEST CHC TO BE IMPACTED BY THE SHOWER ACTIVITY...AND ADDED VCSH TO MDT/LNS BASED ON THE LATEST COSPA DATA. EXPECT CIG/VIS RESTRICTIONS TO BECOME WIDESPREAD TONIGHT INTO EARLY WEDNESDAY AS SLY FLOW AND LLVL MSTR CONTINUES TO INCREASE AHEAD OF THE AFOREMENTIONED WARM FRONT. OUTLOOK... WED-FRI...MVFR/VFR. TWO FRONTAL SYSTEMS WILL BRING PERIODS OF SHOWERS AND OCNL TSTMS. SAT...BCMG VFR AS HIGH PRES BUILDS SEWD FROM THE UPPER MIDWEST. && .EQUIPMENT... KCCX HAS SUFFERED MULTIPLE PEDESTAL DYNAMIC FAULTS EARLY THIS MORNING...CAUSING IT TO GO INTO STAND-BY MODE. THE RADAR WILL REMAIN IN STAND-BY MODE UNTIL OUR TECHNICIANS CAN DIAGNOSE THE PROBLEM LATER THIS MORNING. WE APOLOGIZE FOR THE INCONVENIENCE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...DEVOIR/GARTNER AVIATION...STEINBUGL EQUIPMENT...STEINBUGL/DEVOIR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 AM EDT TUE AUG 6 2013 .SYNOPSIS... AN INCREASINGLY MOIST AND UNSETTLED WEATHER PATTERN WILL PERSIST INTO THE FIRST PART OF THE WEEKEND...AS MULTIPLE FRONTS APPROACH AND EVENTUALLY MOVE ACROSS THE REGION. A GRADUAL WARMING TREND TO NEAR NORMAL TEMPERATURES IS EXPECTED THROUGH THE END OF THE WEEK...BEFORE ANOTHER SHOT OF SEASONABLY COOL AIR ARRIVES ON SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... IR SATL TRENDS SINCE MIDNIGHT HAVE DEPICTED A NOTABLE INCREASE IN LOW-MID LEVEL CLOUDS ACRS A GOOD PORTION OF THE CWA. THE IR SATL IMAGERY ALSO SHOWS FOG IN THE NRN RIVER/STREAM VALLEYS...WHERE AIR/WATER TEMP SPREADS ARE AGAIN RUNNING 25-30 DEGREES. VWP/S FROM IAD/BWI INDICATE THE 925-850MB FLOW HAS VEERED TO THE S-SW...AND LATEST RUC MESO ANALYSIS SHOW A MSTR AXIS /+13-15C 850MB DEWPTS/ EXTENDING NWD ALONG THE ERN SLOPES OF THE APPLCHNS ON THE WRN PERIPHERY OF DEPARTING SFC HIGH. THIS ENHANCED MSTR FLUX APPEARS TO BE OVERRUNNING A WARM FRONT OVER NRN VA WITH DEVELOPING SHOWERS STARTING TO PEEL NWD FROM THE MAIN W-E RAIN BAND TWD SRN MD. THEREFORE CANT RULE OUT AN ISOLD SHOWER OVER THE FAR S-CNTRL OR SERN ZONES PRIOR TO 12Z. WEAK BUT PERSISTENT LLVL WARM AIR/MSTR ADVECTION AND BROAD ISENT LIFT OVERRUNNING THE WARM FRONT OVER NRN VA WILL LKLY SUPPORT THE DEVELOPMENT OF SCT SHOWERS...SPREADING FROM SOUTH TO NORTH DURING THE MID-LATE MORNING THRU THE AFTN HOURS. SHORTWAVES EMBEDDED WITHIN THE SEASONABLY STRONG WNW FLOW ALOFT ON THE SRN PERIPHERY OF CLOSED/SLOW-MOVING UPPER LOW CENTERED OVER NRN MANITOBA/ONTARIO WILL PROVIDE ENOUGH LARGE SCALE LIFT TO AID IN SHOWER DEVELOPMENT. A FEW ISOLD THUNDERSTORMS WITH LOCALIZED HEAVY DOWNPOURS MAY ALSO DEVELOP IN THE AFTN...BUT FOR THE MOST PART INSTABILITY WILL BE WEAK WITH MEAN CAPES GENERALLY AOB 500 J/KG. MODEL QPFS ARE IN REASONABLY GOOD AGREEMENT IN KEEPING THE BETTER RAINFALL AXIS TO THE SOUTH OF THE MASON-DIXON LINE FROM SRN VA NEWD INTO DE...WITH JUST LGT AMTS /0.1-0.25 INCHES/ OVER CNTRL AND SERN PA. THE STEADILY INCREASING MSTR AND CLOUDS WILL KEEP MAX TEMPS IN THE LOW TO MID 70S...AVERAGING A FEW TO SEVERAL DEGREES BELOW NORMAL DEPENDING ON LOCATION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... THE AFOREMENTIONED WARM FRONT WILL LIFT NWD INTO CNTRL PA TONIGHT WITH BROAD LLVL SWLY FLOW CONTINUING TO ADVECT HIGHER PWS/60+ DEWPOINTS INTO THE AREA. MDL CONSENSUS STILL FAVORS THE ERN 1/2 TO 1/3 OF THE CWA WITH THE BEST CHC FOR LGT SHOWERS OVERNIGHT INTO EARLY WEDNESDAY MORNING. IN CONTRAST TO DAYTIME HIGHS...THICKENING CLOUDS PLUS INCREASING MSTR/DEWPOINTS WILL RESULT IN WARMER THAN AVG MIN TEMPS WITH READINGS IN THE LOW-MID 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... A ZONAL FLOW ACROSS THE NORTHERN CONUS WILL PREVAIL ACROSS THE REGION FROM WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. NUMEROUS EMBEDDED DISTURBANCES WILL ACT ON MONSOONAL MOISTURE FROM THE SOUTHWESTERN UNITED STATES AND NEARLY STATIONARY BOUNDARY LAYER FORCING TO PRODUCE A LOCALLY HEAVY RAIN/FLASH FLOOD THREAT ON THU- FRI BEFORE DRIER AND COOLER CONDS RETURN BY LATE SAT AND SUN. CLOUDS/PCPN SHOULD OFFSET WARMING ALOFT AND KEEP TEMPS NEAR TO SLIGHTLY BELOW AVG. MDL DATA INDICATES THE COLD FRONT WILL BECOME MUCH LESS PROGRESSIVE OR STALL OUT OVER THE UPPER OH VLY WED NGT INTO THUR. MODELS AND ENS MEANS CENTER AROUND THE GENERAL IDEA OF A MODERATELY SLOW PROGRESSION OF THE CLOSED LOW TRACKING EWD BTWN THE GRT LKS AND HUDSON BAY FROM THU THRU SAT. AT THE SFC...THE COLD FRONT TURN Q-STNRY BNDRY IN THE OH VLY...WHICH WAS ASSOCIATED WITH THE LEAD SHORTWAVE TROUGH...SHOULD PUSH SLOWLY EWD ACRS CNTRL PA ON DAY4/THU. THE SFC PATTERN GETS QUITE COMPLICATED FRI-SAT AS WPC PROGS SHOW THE FIRST BOUNDARY STALLING OUT OVER THE SRN MID- ATLC STATES AND SECONDARY COLD FRONT APPROACHING FROM THE GREAT LAKES. WAVES OF LOW PRESSURE RIDING NEWD ALONG THESE ENCROACHING FRONTS COULD KEEP UNSETTLED CONDS IN THE FCST THRU THE FIRST PART OF THE WEEKEND. ANOTHER PUSH OF WESTERLIES SHOULD OVERSPREAD THE AREA BY SUNDAY AND NUDGE THE SECOND FRONT EWD TO OR OFF THE COAST. A LARGE AREA OF CANADIAN HIGH PRESSURE SHOULD SUPPLY ANOTHER REFRESHINGLY COOL/DRY AIRMASS INTO THE GREAT LAKES AND NORTHEAST BY NEXT SUNDAY. DON`T EXPECT TEMPS TO FLUCTUATE VERY MUCH THRU THE MEDIUM RANGE...CONTINUING TO AVG NEAR TO SLIGHTLY BELOW NORMAL FOR EARLY AUGUST. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... SLY RETURN FLOW DEVELOPING ON THE WRN PERIPHERY OF HIGH PRES SLIDING OFF THE EAST COAST WILL BRING INCREASING MSTR AND THICKENING LOW-MID CLOUDS INTO CNTRL PA THRU TONIGHT. A LLVL MSTR CONVERGENCE AXIS EXTENDING NWD FM THE SE STATES ALONG THE ERN SLOPES OF THE APPLCHNS IS LKLY RESPONSIBLE FOR THE AREA OF 6-8KFT CIGS OVER THE S-CNTRL AND SERN TAFS. EXPECT THESE CIGS TO THICKEN AND LOWER 1-2KFT INTO THE MID MORNING AS BLYR COOLS AND LLVL FLOW CONTINUES VEERING TO THE SOUTH-SOUTHEAST. THE INCREASINGLY MOIST LLVL FLOW WILL OVERRUN A WARM FRONT LIFTING SLOWLY NEWD FROM THE TN VLY AND CNTRL APPLCHNS AND SUPPORT SCT SHOWERS /WITH ISOLD TSRA/ INTO THE AFTN. THE S-CNTRL AND SERN AIRFIELDS STAND THE GREATEST CHC TO BE IMPACTED BY THE SHOWER ACTIVITY. EXPECT CIG RESTRICTIONS TO BECOME MORE WIDESPREAD FROM TONIGHT INTO EARLY WEDNESDAY AS SLY FLOW AND LLVL MSTR CONTINUES TO INCREASE AS WARM FRONT LIFTS NEWD ACRS THE AIRSPACE. OUTLOOK... WED-FRI...MVFR/VFR. TWO FRONTAL SYSTEMS WILL BRING PERIODS OF SHOWERS AND OCNL TSTMS. SAT...BCMG VFR AS HIGH PRES BUILDS SEWD FROM THE UPPER MIDWEST. && .EQUIPMENT... KCCX HAS SUFFERED MULTIPLE PEDESTAL DYNAMIC FAULTS EARLY THIS MORNING...CAUSING IT TO GO INTO STAND-BY MODE. THE RADAR WILL REMAIN IN STAND-BY MODE UNTIL OUR TECHNICIANS CAN DIAGNOSE THE PROBLEM LATER THIS MORNING. WE APOLOGIZE FOR THE INCONVENIENCE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...DEVOIR/GARTNER AVIATION...STEINBUGL EQUIPMENT...STEINBUGL/DEVOIR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
433 AM EDT TUE AUG 6 2013 .SYNOPSIS... AN INCREASINGLY MOIST AND UNSETTLED WEATHER PATTERN WILL PERSIST INTO THE FIRST PART OF THE WEEKEND...AS MULTIPLE FRONTS APPROACH AND EVENTUALLY MOVE ACROSS THE REGION. A GRADUAL WARMING TREND TO NEAR NORMAL TEMPERATURES IS EXPECTED THROUGH THE END OF THE WEEK...BEFORE ANOTHER SHOT OF SEASONABLY COOL AIR ARRIVES ON SUNDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... IR SATL TRENDS SINCE MIDNIGHT HAVE DEPICTED A NOTABLE INCREASE IN LOW-MID LEVEL CLOUDS ACRS A GOOD PORTION OF THE CWA. THE IR SATL IMAGERY ALSO SHOWS FOG IN THE NRN RIVER/STREAM VALLEYS...WHERE AIR/WATER TEMP SPREADS ARE AGAIN RUNNING 25-30 DEGREES. VWP/S FROM IAD/BWI INDICATE THE 925-850MB FLOW HAS VEERED TO THE S-SW...AND LATEST RUC MESO ANALYSIS SHOW A MSTR AXIS /+13-15C 850MB DEWPTS/ EXTENDING NWD ALONG THE ERN SLOPES OF THE APPLCHNS ON THE WRN PERIPHERY OF DEPARTING SFC HIGH. THIS ENHANCED MSTR FLUX APPEARS TO BE OVERRUNNING A WARM FRONT OVER NRN VA WITH DEVELOPING SHOWERS STARTING TO PEEL NWD FROM THE MAIN W-E RAIN BAND TWD SRN MD. THEREFORE CANT RULE OUT AN ISOLD SHOWER OVER THE FAR S-CNTRL OR SERN ZONES PRIOR TO 12Z. WEAK BUT PERSISTENT LLVL WARM AIR/MSTR ADVECTION AND BROAD ISENT LIFT OVERRUNNING THE WARM FRONT OVER NRN VA WILL LKLY SUPPORT THE DEVELOPMENT OF SCT SHOWERS...SPREADING FROM SOUTH TO NORTH DURING THE MID-LATE MORNING THRU THE AFTN HOURS. SHORTWAVES EMBEDDED WITHIN THE SEASONABLY STRONG WNW FLOW ALOFT ON THE SRN PERIPHERY OF CLOSED/SLOW-MOVING UPPER LOW CENTERED OVER NRN MANITOBA/ONTARIO WILL PROVIDE ENOUGH LARGE SCALE LIFT TO AID IN SHOWER DEVELOPMENT. A FEW ISOLD THUNDERSTORMS WITH LOCALIZED HEAVY DOWNPOURS MAY ALSO DEVELOP IN THE AFTN...BUT FOR THE MOST PART INSTABILITY WILL BE WEAK WITH MEAN CAPES GENERALLY AOB 500 J/KG. MODEL QPFS ARE IN REASONABLY GOOD AGREEMENT IN KEEPING THE BETTER RAINFALL AXIS TO THE SOUTH OF THE MASON-DIXON LINE FROM SRN VA NEWD INTO DE...WITH JUST LGT AMTS /0.1-0.25 INCHES/ OVER CNTRL AND SERN PA. THE STEADILY INCREASING MSTR AND CLOUDS WILL KEEP MAX TEMPS IN THE LOW TO MID 70S...AVERAGING A FEW TO SEVERAL DEGREES BELOW NORMAL DEPENDING ON LOCATION. && .SHORT TERM /TONIGHT/... THE AFOREMENTIONED WARM FRONT WILL LIFT NWD INTO CNTRL PA TONIGHT WITH BROAD LLVL SWLY FLOW CONTINUING TO ADVECT HIGHER PWS/60+ DEWPOINTS INTO THE AREA. MDL CONSENSUS STILL FAVORS THE ERN 1/2 TO 1/3 OF THE CWA WITH THE BEST CHC FOR LGT SHOWERS OVERNIGHT INTO EARLY WEDNESDAY MORNING. IN CONTRAST TO DAYTIME HIGHS...THICKENING CLOUDS PLUS INCREASING MSTR/DEWPOINTS WILL RESULT IN WARMER THAN AVG MIN TEMPS WITH READINGS IN THE LOW-MID 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... A ZONAL FLOW ACROSS THE NORTHERN CONUS WILL PREVAIL ACROSS THE REGION FROM WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. NUMEROUS EMBEDDED DISTURBANCES WILL ACT ON MONSOONAL MOISTURE FROM THE SOUTHWESTERN UNITED STATES AND NEARLY STATIONARY BOUNDARY LAYER FORCING TO PRODUCE A LOCALLY HEAVY RAIN/FLASH FLOOD THREAT ON THU- FRI BEFORE DRIER AND COOLER CONDS RETURN BY LATE SAT AND SUN. CLOUDS/PCPN SHOULD OFFSET WARMING ALOFT AND KEEP TEMPS NEAR TO SLIGHTLY BELOW AVG. MDL DATA INDICATES THE COLD FRONT WILL BECOME MUCH LESS PROGRESSIVE OR STALL OUT OVER THE UPPER OH VLY WED NGT INTO THUR. MODELS AND ENS MEANS CENTER AROUND THE GENERAL IDEA OF A MODERATELY SLOW PROGRESSION OF THE CLOSED LOW TRACKING EWD BTWN THE GRT LKS AND HUDSON BAY FROM THU THRU SAT. AT THE SFC...THE COLD FRONT TURN Q-STNRY BNDRY IN THE OH VLY...WHICH WAS ASSOCIATED WITH THE LEAD SHORTWAVE TROUGH...SHOULD PUSH SLOWLY EWD ACRS CNTRL PA ON DAY4/THU. THE SFC PATTERN GETS QUITE COMPLICATED FRI-SAT AS WPC PROGS SHOW THE FIRST BOUNDARY STALLING OUT OVER THE SRN MID- ATLC STATES AND SECONDARY COLD FRONT APPROACHING FROM THE GREAT LAKES. WAVES OF LOW PRESSURE RIDING NEWD ALONG THESE ENCROACHING FRONTS COULD KEEP UNSETTLED CONDS IN THE FCST THRU THE FIRST PART OF THE WEEKEND. ANOTHER PUSH OF WESTERLIES SHOULD OVERSPREAD THE AREA BY SUNDAY AND NUDGE THE SECOND FRONT EWD TO OR OFF THE COAST. A LARGE AREA OF CANADIAN HIGH PRESSURE SHOULD SUPPLY ANOTHER REFRESHINGLY COOL/DRY AIRMASS INTO THE GREAT LAKES AND NORTHEAST BY NEXT SUNDAY. DON`T EXPECT TEMPS TO FLUCTUATE VERY MUCH THRU THE MEDIUM RANGE...CONTINUING TO AVG NEAR TO SLIGHTLY BELOW NORMAL FOR EARLY AUGUST. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... SLY RETURN FLOW DEVELOPING ON THE WRN PERIPHERY OF HIGH PRES SLIDING OFF THE EAST COAST WILL BRING INCREASING MSTR AND THICKENING LOW-MID CLOUDS INTO CNTRL PA THRU TONIGHT. A LLVL MSTR CONVERGENCE AXIS EXTENDING NWD FM THE SE STATES ALONG THE ERN SLOPES OF THE APPLCHNS IS LKLY RESPONSIBLE FOR THE AREA OF 6-8KFT CIGS OVER THE S-CNTRL AND SERN TAFS. EXPECT THESE CIGS TO THICKEN AND LOWER 1-2KFT INTO THE MID MORNING AS BLYR COOLS AND LLVL FLOW CONTINUES VEERING TO THE SOUTH-SOUTHEAST. THE INCREASINGLY MOIST LLVL FLOW WILL OVERRUN A WARM FRONT LIFTING SLOWLY NEWD FROM THE TN VLY AND CNTRL APPLCHNS AND SUPPORT SCT SHOWERS /WITH ISOLD TSRA/ INTO THE AFTN. THE S-CNTRL AND SERN AIRFIELDS STAND THE GREATEST CHC TO BE IMPACTED BY THE SHOWER ACTIVITY. EXPECT CIG RESTRICTIONS TO BECOME MORE WIDESPREAD FROM TONIGHT INTO EARLY WEDNESDAY AS SLY FLOW AND LLVL MSTR CONTINUES TO INCREASE AS WARM FRONT LIFTS NEWD ACRS THE AIRSPACE. OUTLOOK... WED-FRI...MVFR/VFR. TWO FRONTAL SYSTEMS WILL BRING PERIODS OF SHOWERS AND OCNL TSTMS. SAT...BCMG VFR AS HIGH PRES BUILDS SEWD FROM THE UPPER MIDWEST. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...DEVOIR/GARTNER AVIATION...STEINBUGL
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1238 PM CDT TUE AUG 6 2013 .UPDATE... UPDATED AVIATION DISCUSSION BELOW FOR 18Z TAFS. WEAK SURFACE LOW PRESSURE AREA IN SOUTHEAST ND MOVING EAST LATE THIS MORNING WITH A WEAK COOL FRONT DROPPING IN BEHIND IT. MOST OF THE CONVECTION WAS OVER THIS MORNING. THE HRRR MODEL WAS SHOWING SOME REDEVELOPMENT OVER FAR NE SD/WC MN THIS AFTERNOON AND EVENING AND ALSO ALONG THE WEAK COOL FRONT DROPPING IN FROM THE NORTH. THUS...ADJUSTED POPS DOWNWARD ACROSS MOST OF THE REGION THROUGH THE AFTERNOON. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH THURSDAY PRECIPITATION CHANCES TODAY WILL BE THE MAIN FORECAST CHALLENGE. THUNDERSTORMS CURRENTLY ONGOING ALONG AND SOUTH OF I-90 SHOULD CONTINUE TO DRIFT ESE...CLIPPING ONLY THE SOUTHWEST PORTION OF THE CWA THROUGH THE MID MORNING HOURS. ADDITIONAL CONVECTION IS MOVING DUE EAST ALONG I-94 IN NORTH DAKOTA. THESE STORMS SHOULD REMAIN NORTH OF THIS CWA THROUGH THE MORNING HOURS. MODELS SORT OF AGREE WITH TWO POSSIBLE CLUSTERS OF STORMS DEVELOPING LATER THIS AFTERNOON. ONE CLUSTER WOULD BE ACROSS SOUTHEAST SOUTH DAKOTA WHERE BETTER INSTABILITY IS LOCATED ALONG WITH A WEAK MID LEVEL SHORT WAVE. IF THIS ACTIVITY DEVELOPS...IT SHOULD REMAIN SOUTH OF THIS CWA. THE SECONDARY CLUSTER WILL BE ALONG A SLOWLY SOUTHWARD SINKING COLD FRONT. LESS INSTABILITY ALONG THE FRONT...BUT SLIGHTLY BETTER 0-6 KM BULK SHEAR MAY RESULT IN A FEW STRONGER STORMS IN NORTHEAST SOUTH DAKOTA AND WESTERN MINNESOTA LATER THIS AFTERNOON. A COOL CANADIAN HIGH PRESSURE SETTLING ACROSS THE REGION WILL BRING DRY AND TRANQUIL CONDITIONS FOR WEDNESDAY AND FOR MOST OF WEDNESDAY NIGHT. THEN ANOTHER SURFACE LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION DURING THE EARLY MORNING HOURS ON THURSDAY. THERE SEEMS TO BE A GENERAL CONSENSUS WITH MOST OF THE CONVECTION OCCURRING ACROSS SOUTHERN NORTH DAKOTA. THERE IS STILL A CHANCE FOR THUNDERSTORMS ACROSS MOST OF THE CWA AS A TRAILING COLD FRONT MOVES SOUTHWARD ACROSS THE CWA ON THURSDAY. SIGNIFICANTLY LESS INSTABILITY SHOULD RESULT IN GENERAL THUNDERSTORMS. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY NIGHT NO CHANGES FROM 24 HOURS AGO. NORTHWEST FLOW WILL STEER ONE OR MORE MID-LEVEL SHORTWAVES THROUGH THE REGION ATOP A DECENT LOW TO MID-LEVEL BAROCLINIC ZONE...RESULTING IN A COUPLE HALFWAY DECENT CHANCES FOR MEASURABLE PRECIP OVER A GOODLY AMOUNT OF AREAL COVERAGE OF THE CWA. SEEMS THE BEST CHANCES FOR PRECIPITATION...RIGHT NOW...ARE ANCHORED ON FRIDAY NIGHT THROUGH SUNDAY MORNING. 925HPA AND 850HPA THERMAL PROGS IN THE GFS AND ECMWF SUGGEST TEMPERATURES WILL REMAIN GENERALLY NEAR TO BELOW NORMAL THROUGH THE PERIOD. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD. AS OF 18Z A BAND OF -SHRA STRETCHES FROM WESTERN THROUGH CENTRAL SD. HAVE INCLUDED VCSH AT KPIR FOR THE AFTERNOON HOURS TO ACCOUNT FOR THIS. OTHERWISE...AS A FRONTAL BOUNDARY MOVES ACROSS THE REGION TODAY...A FEW SHRA/TSRA ARE POSSIBLE...MAINLY OVER EASTERN PORTIONS OF THE AREA. HAVE INCLUDED A VCTS MENTION AT KATY LATER THIS AFTERNOON. W/NW WINDS WILL BECOME MORE N/NE OVERNIGHT AS THE MAIN PUSH OF COOLER AIR WORKS ITS WAY SOUTH OVER THE AREA. LIGHT WINDS AND VFR CONDITIONS CAN BE EXPECTED ON WEDNESDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR/TMT SHORT TERM...CONNELLY LONG TERM...DORN AVIATION...TMT WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1029 AM CDT TUE AUG 6 2013 .UPDATE... WEAK SURFACE LOW PRESSURE AREA IN SOUTHEAST ND MOVING EAST LATE THIS MORNING WITH A WEAK COOL FRONT DROPPING IN BEHIND IT. MOST OF THE CONVECTION WAS OVER THIS MORNING. THE HRRR MODEL WAS SHOWING SOME REDEVELOPMENT OVER FAR NE SD/WC MN THIS AFTERNOON AND EVENING AND ALSO ALONG THE WEAK COOL FRONT DROPPING IN FROM THE NORTH. THUS...ADJUSTED POPS DOWNWARD ACROSS MOST OF THE REGION THROUGH THE AFTERNOON. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH THURSDAY PRECIPITATION CHANCES TODAY WILL BE THE MAIN FORECAST CHALLENGE. THUNDERSTORMS CURRENTLY ONGOING ALONG AND SOUTH OF I-90 SHOULD CONTINUE TO DRIFT ESE...CLIPPING ONLY THE SOUTHWEST PORTION OF THE CWA THROUGH THE MID MORNING HOURS. ADDITIONAL CONVECTION IS MOVING DUE EAST ALONG I-94 IN NORTH DAKOTA. THESE STORMS SHOULD REMAIN NORTH OF THIS CWA THROUGH THE MORNING HOURS. MODELS SORT OF AGREE WITH TWO POSSIBLE CLUSTERS OF STORMS DEVELOPING LATER THIS AFTERNOON. ONE CLUSTER WOULD BE ACROSS SOUTHEAST SOUTH DAKOTA WHERE BETTER INSTABILITY IS LOCATED ALONG WITH A WEAK MID LEVEL SHORT WAVE. IF THIS ACTIVITY DEVELOPS...IT SHOULD REMAIN SOUTH OF THIS CWA. THE SECONDARY CLUSTER WILL BE ALONG A SLOWLY SOUTHWARD SINKING COLD FRONT. LESS INSTABILITY ALONG THE FRONT...BUT SLIGHTLY BETTER 0-6 KM BULK SHEAR MAY RESULT IN A FEW STRONGER STORMS IN NORTHEAST SOUTH DAKOTA AND WESTERN MINNESOTA LATER THIS AFTERNOON. A COOL CANADIAN HIGH PRESSURE SETTLING ACROSS THE REGION WILL BRING DRY AND TRANQUIL CONDITIONS FOR WEDNESDAY AND FOR MOST OF WEDNESDAY NIGHT. THEN ANOTHER SURFACE LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION DURING THE EARLY MORNING HOURS ON THURSDAY. THERE SEEMS TO BE A GENERAL CONSENSUS WITH MOST OF THE CONVECTION OCCURRING ACROSS SOUTHERN NORTH DAKOTA. THERE IS STILL A CHANCE FOR THUNDERSTORMS ACROSS MOST OF THE CWA AS A TRAILING COLD FRONT MOVES SOUTHWARD ACROSS THE CWA ON THURSDAY. SIGNIFICANTLY LESS INSTABILITY SHOULD RESULT IN GENERAL THUNDERSTORMS. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY NIGHT NO CHANGES FROM 24 HOURS AGO. NORTHWEST FLOW WILL STEER ONE OR MORE MID-LEVEL SHORTWAVES THROUGH THE REGION ATOP A DECENT LOW TO MID-LEVEL BAROCLINIC ZONE...RESULTING IN A COUPLE HALFWAY DECENT CHANCES FOR MEASURABLE PRECIP OVER A GOODLY AMOUNT OF AREAL COVERAGE OF THE CWA. SEEMS THE BEST CHANCES FOR PRECIPITATION...RIGHT NOW...ARE ANCHORED ON FRIDAY NIGHT THROUGH SUNDAY MORNING. 925HPA AND 850HPA THERMAL PROGS IN THE GFS AND ECMWF SUGGEST TEMPERATURES WILL REMAIN GENERALLY NEAR TO BELOW NORMAL THROUGH THE PERIOD. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS GOOD VFR AND DRY CONDITIONS ARE EXPECTED AT ALL FOUR TERMINALS THROUGH THIS AFTERNOON. THEN...A COLD FRONT MOVING THROUGH THE REGION COULD TOUCH OFF A FEW SHOWERS OR STORMS AT OR NEAR THE KABR/KATY TERMINALS. THE COLD FRONT WILL ALSO BE SWITCHING WINDS AROUND TO THE NORTHWEST. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...SD LONG TERM...DORN AVIATION...DORN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1024 PM CDT WED AUG 7 2013 .UPDATE...SCATTERED CONVECTION STILL GOING ON, MAINLY WEST OF I-65. SO FAR, HRRR DOING A FAIRLY GOOD JOB HANDLING THE EVENING ACTIVITY. MODEL DOES SHOW A SLIGHT INCREASE IN ACTIVITY OVERNIGHT, BUT DON`T KNOW THAT IT JUSTIFIES LIKELY POP`S. WILL TREND BACK TO SCATTERED FOR THE 06Z TO 12Z PERIOD AND UPDATE THE FORECAST ACCORDINGLY. && .PREV DISCUSSION... /ISSUED 631 PM CDT WED AUG 7 2013/ UPDATE...FOR 00Z AVIATION. AVIATION...00Z TAF DISCUSSION. MIXED BAG TONIGHT. ALL TERMINALS HAVE GONE VFR AT ISSUANCE AS THE ATMOSPHERE SEEMS TO BE FAIRLY STABLE DUE TO EARLIER RAINS AND TS. HIGH CLOUDS OVER THE EASTERN HALF OF MIDDLE TENNESSEE SHOULD CONTINUE MOVING OUT OF THE AREA AND SET THE STAGE FOR SOME FOG AND STRATUS DEVELOPMENT AROUND MIDNIGHT TONIGHT. WILL DROP CSV/CKV THE LOWEST AND GO IFR BY 09Z-10Z AT BOTH. THE QUESTION STILL REMAINS AS TO WHETHER WE WILL SEE ANY REDEVELOPMENT TONIGHT IN THE WAY OF RAINS. SOME SHORT TERM GUIDANCE STILL SUGGESTS THIS...BUT IS TRENDING AWAY FROM ANYTHING TOO WIDESPREAD. FOR THIS REASON... WILL REMOVE ANY OVERNIGHT VC WORDING AND WORK FROM AMDS TONIGHT. WILL NEED TO MONITOR UPSTREAM ACTIVITY AS WELL AS WE REMAIN IN A QUASI-NW FLOW. LOOK FOR AFTERNOON TS DEVELOPMENT THURSDAY AROUND ALL OF MIDDLE TENNESSEE. UNGER PREV DISCUSSION... /ISSUED 323 PM CDT WED AUG 7 2013/ DISCUSSION...STATUS QUO FOR THIS FORECAST CYCLE...WITH A MOIST AND UNSETTLED PATTERN CONTINUING TO BRING GOOD CHANCES FOR SHOWERS AND THUNDERSTORMS. PRECIPITABLE WATER VALUES WILL REMAIN WELL ABOVE NORMAL THE NEXT COUPLE OF DAYS...A LITTLE OVER 2 INCHES. THIS WILL MEAN THE POSSIBILITY FOR SOME LOCALLY HEAVY RAINFALL. THANKS TO THE ON AND OFF NATURE OF THE RAIN...AND THE VARIABILITY IN LOCATION...WE STILL DO NOT SEE THE NEED FOR A FLASH FLOOD WATCH AT THIS TIME. AVERAGE QPF THROUGH FRIDAY LOOKS LIKE 1-2 INCHES...BUT A FEW LOCATIONS IMPACTED BY STRONGER STORMS WILL CERTAINLY HAVE GREATER AMOUNTS. THE BIG QUESTION IS EXACTLY WHEN THE RAIN WILL OCCUR. SHORT RANGE MODELS SEEM USELESS IN DETERMINING TRENDS INTO TONIGHT WITH SOLUTIONS ALL OVER THE PLACE. RIGHT NOW IT APPEARS THAT EARLIER STORMS HAVE "WORKED OVER" THE ATMOSPHERE...AND WE WILL HAVE AT LEAST A FEW QUIET HOURS EARLY THIS EVENING. SOME REDEVELOPMENT IS EXPECTED LATER...PERHAPS ANOTHER MCS SCENARIO WHERE STORMS DEVELOP OVER MO AND COME IN FROM THE NORTHWEST LATE NIGHT. TIMING IS ALSO HIGHLY UNCERTAIN THURSDAY AND FRIDAY WITH A SERIES OF WEAK WAVES AND VARIOUS MESOSCALE BOUNDARIES TRAVERSING THE REGION. STILL...WE WILL GO WITH HIGH POPS GIVEN GUIDANCE NUMBERS...RECENT HISTORY...AND THE FAVORABLE STATE OF THE ATMOSPHERE. THE MAIN CONCERN WITH STORMS THROUGH FRIDAY WILL BE HEAVY RAINFALL. A FEW STRONG OR BRIEFLY SEVERE STORMS WITH GUSTY WINDS CANNOT BE RULED OUT IN THE HEAT OF THE AFTERNOON THROUGH THE NEXT COUPLE OF DAYS. INSTABILITY WILL BE GREATLY DEPENDENT ON AMOUNT OF SURFACE HEATING. MOS GUIDANCE CONTINUES TO OVERSHOOT ON THE HIGHS...SO CHOPPING OFF A FEW DEGREES OVER THE NEXT COUPLE OF DAYS. HOWEVER...HIGH TEMPS ARE HIGHLY DEPENDENT ON CLOUD COVER AND THUNDERSTORMS COVERAGE...SO IF WE MANAGE TO SEE A LITTLE MORE SUN...TEMPERATURES COULD JUMP QUICKLY TO 90+. INTO THE WEEKEND...A FRONT WILL BE DROPPING ACROSS THE OHIO VALLEY AND INTO TN. THIS BOUNDARY MAY SINK FAR ENOUGH FOR SLIGHTLY DRIER TO COME IN BY LATE SUNDAY...BUT THAT SEEMS OPTIMISTIC. EVEN IF THIS OCCURS...THE BOUNDARY WILL STILL BE CLOSE ENOUGH TO MAINTAIN A CHANCE FOR SHOWERS AND STORMS. INTO NEXT WEEK...NORTHWEST FLOW ALOFT MAY BRING A LITTLE MORE COOLING AND DRYING...BUT NORTHWEST FLOW IS NOTORIOUSLY UNSETTLED...SO A CHANCE FOR THUNDERSTORMS WILL REMAIN IN THE FORECAST EVERY DAY. 13 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ROSE
AREA FORECAST DISCUSSION...UPDATED
NWS MEMPHIS TN
740 PM CDT WED AUG 7 2013 .UPDATE... DIFFICULT TO GET A HANDLE ON EXACTLY WHERE ANY SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS EVENING WITH MANY OF THE MODELS BEING POOR IN HANDLING THE CURRENT SITUATION. A WEAK WARM EXTENDS FROM NORTHEAST AR INTO SOUTHWEST TN AT EARLY EVENING. A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG THE TN RIVER IN WEST TN JUST NORTH OF THIS FRONT. THE HIGH RESOLUTION RAPID REFRESH MODEL SEEMS TO BE DOING THE BEST JOB...AND THIS MODEL INDICATE FURTHER DEVELOPMENT THIS EVENING NORTH OF THE FRONT ACROSS PORTIONS OF NORTHEAST AR...THE MO BOOTHEEL...AND PORTIONS OF WEST TN. UPDATED TO REMOVE MENTION OF RAIN THIS EVENING SOUTH OF THIS AREA. ALSO ADJUSTED THE SKY COVER A LITTLE FOR THIS EVENING...OTHERWISE LITTLE CHANGE MADE TO THE EARLIER FORECAST. JCL && .PREV DISCUSSION... /ISSUED 312 PM CDT WED AUG 7 2013/ THE OUTFLOW BOUNDARY GENERATED FROM THIS MORNINGS MCS CONTINUES TO PUSH ACROSS NORTHERN MISSISSIPPI. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG AND IN ADVANCE OF THE BOUNDARY AND WILL CONTINUE TO PUSH ACROSS THE REMAINDER OF NORTH MISSISSIPPI OVER THE NEXT COUPLE OF HOURS. THESE STORMS COULD BE STRONG WITH GUSTY WINDS AND HEAVY RAIN. THE BOUNDARY HAS LIMITED HIGH TEMPS ACROSS THE DELTA THOUGH THE SOUTHERN MOST COUNTIES...FROM TALLAHATCHIE TO MONROE...HAVE WARMED INTO THE MID 90S WITH HEAT INDEX VALUES FLIRTING WITH 105 DEGREES. THE REMNANTS OF THE COLD POOL HAVE RESULTED IN A RELATIVELY NICE DAY ACROSS MUCH OF EASTERN AR...THE MO BOOTHEEL AND WEST TENNESSEE WHERE TEMPS ARE MOSTLY IN THE 80S TO AROUND 90. THE AIRMASS STILL QUITE STABLE AND PRECIP FREE. TONIGHT...LOOKING AT A FAIRLY QUIET EVENING GIVEN THE WORKED OVER AIRMASS IN PLACE. WENT WITH A 20 POP OVER MOST OF THE AREA AND A 30 POP OVER NE ARKANSAS WHERE THE HRRR IS HINTING AT SOME DEVELOPMENT BEFORE MIDNIGHT. LOOKING AT ANOTHER POTENTIAL MCS SCENARIO LATER TONIGHT AS THE LOW LEVEL JET REDEVELOPS OVER EASTERN OK AND WESTERN AR AND IMPINGES UPON THE WEAK STATIONARY FRONT ACROSS THE AREA. THIS FRONT HAS BEEN HAVING TROUBLE LIFTING NORTH OVER THE LAST COUPLE OF DAYS THANKS TO THE RECENT MCS ACTIVITY AND ASSOCD COLD POOLS. AN AREA OF SHOWERS AND THUNDERSTORMS SHOULD BLOSSOM OVER SRN MISSOURI AFTER MIDNIGHT AND THEN HEAD ESE AND SKIRT THE NORTHERN TIER OF THE MIDSOUTH BY MORNING. POPS WILL DECREASE SHARPLY TOWARD SOUTHERN AREAS OF THE MIDSOUTH. ANOTHER MILD NIGHT ON TAP WITH LOWS IN THE MID 70S. THURSDAY...EXPECT THE MCS TO SKIRT THE NORTHERN TIER AND WEAKEN AS IT SPREADS EAST. BEST CHANCE WILL BE ACROSS NORTHERN AND EASTERN SECTION WITH LESSER CHANCES TOWARD THE SOUTHWEST. MEX GUIDANCE CONTINUES TO BE VERY WARM AND WENT CLOSER TO THE COOLER MET GUIDANCE. EXPECT THAT ANOTHER OUTFLOW BOUNDARY MAY PUSH SOUTH WHICH WILL HELP KEEP A LID ON TEMPS. AREAS SOUTHWEST OF MEMPHIS ARE LIKELY TO GET THE WARMEST AND COULD FLIRT WITH HEAT ADVISORY CRITERIA. THURSDAY NIGHT THROUGH FRIDAY NIGHT...PATTERN REMAINS SIMILAR WITH A BROAD UPPER RIDGE ACROSS THE SOUTHERN U.S AND A WEAK STATIONARY FRONT ACROSS SOUTHERN MISSOURI. EXPECT MCS DEVELOPMENT ALONG THIS FRONT EACH NIGHT WITH THE BEST CHANCES OF PRECIP ALONG THE NORTHERN TIER OF THE MIDSOUTH. CONTINUED TO PREFER THE COOLER MET GUIDANCE THOUGH PARTS OF NORTH MISSISSIPPI AND EAST CENTRAL ARKANSAS WILL FLIRT WITH HEAT ADVISORY CRITERIA ON FRIDAY. SATURDAY THROUGH SUNDAY...CONFIDENCE STARTING TO WANE AT THIS POINT. UPPER RIDGE REMAINS ACROSS THE SOUTHERN U.S. WHILE THE WEAK BOUNDARY TRIES TO SLIP SOUTH INTO THE MIDSOUTH BUT REALLY DOES NOT MOVE MUCH. CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE REGION. MEX STILL TOO WARM. MONDAY THROUGH WEDNESDAY...MEDIUM RANGE MODELS INDICATE THAT AN UPPER TROF WILL DEVELOP OVER THE EASTERN U.S. EARLY NEXT WEEK. THE GFS IS NOT AS DEEP WITH THE TROF WHICH REESTABLISHES NORTHWEST FLOW ACROSS THE REGION AND KEEPS THE SURFACE BOUNDARY IN THE AREA RESULTING IN A RENEWED MCS PATTERN. THE ECMWF HAS A DEEPER TROF AND ACTUALLY PUSHES THE FRONT SOUTH...SHUTTING OFF PRECIP CHANCES. FOR NOW JUST WENT WITH A COMPROMISE OF 20 POPS AND SLIGHTLY COOLER THAN NORMAL TEMPS. SJM && .AVIATION... 00Z TAF CYCLE VFR CONDITIONS EXPECTED AT ALL THE TAF SITES OUTSIDE OF TEMPO LIGHT FOG/MVFR VISIBILITIES NEAR SUNRISE AT MKL...JBR AND TUP. BIGGER CHALLENGE WILL BE THE EXTENT OF THE NEXT FUTURE ROUND OF CONVECTION CROSSING SOUTHERN MISSOURI. FOR NOW THE GREATEST IMPACT WILL BE AT JBR AND MKL...WHILE MEM AND TUP SHOULD STAY JUST FAR ENOUGH SOUTH. CONFIDENCE THOUGH...IS NOT HIGH ENOUGH TO PLACE THUNDERSTORMS ON STATION AT JBR AND MKL...SO WENT WITH TEMPO MIDDAY SHOWERS...BECOMING VCTS LATE. WINDS WILL EITHER REMAIN LIGHT AND VARIABLE OR FROM THE SOUTH AND SOUTHEAST TONIGHT...INCREASING SLIGHTLY FROM THE SOUTH THURSDAY. JAB && .PRELIMINARY POINT TEMPS/POPS... MEM 77 93 78 94 / 30 30 10 30 MKL 73 88 74 91 / 50 60 30 40 JBR 75 90 75 92 / 50 40 30 40 TUP 75 93 75 93 / 20 40 10 40 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
623 PM CDT WED AUG 7 2013 .UPDATE... UPDATED FOR 00Z AVIATION DISCUSSION. && .PREV DISCUSSION... /ISSUED 312 PM CDT WED AUG 7 2013/ DISCUSSION... THE OUTFLOW BOUNDARY GENERATED FROM THIS MORNINGS MCS CONTINUES TO PUSH ACROSS NORTHERN MISSISSIPPI. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG AND IN ADVANCE OF THE BOUNDARY AND WILL CONTINUE TO PUSH ACROSS THE REMAINDER OF NORTH MISSISSIPPI OVER THE NEXT COUPLE OF HOURS. THESE STORMS COULD BE STRONG WITH GUSTY WINDS AND HEAVY RAIN. THE BOUNDARY HAS LIMITED HIGH TEMPS ACROSS THE DELTA THOUGH THE SOUTHERN MOST COUNTIES...FROM TALLAHATCHIE TO MONROE...HAVE WARMED INTO THE MID 90S WITH HEAT INDEX VALUES FLIRTING WITH 105 DEGREES. THE REMNANTS OF THE COLD POOL HAVE RESULTED IN A RELATIVELY NICE DAY ACROSS MUCH OF EASTERN AR...THE MO BOOTHEEL AND WEST TENNESSEE WHERE TEMPS ARE MOSTLY IN THE 80S TO AROUND 90. THE AIRMASS STILL QUITE STABLE AND PRECIP FREE. TONIGHT...LOOKING AT A FAIRLY QUIET EVENING GIVEN THE WORKED OVER AIRMASS IN PLACE. WENT WITH A 20 POP OVER MOST OF THE AREA AND A 30 POP OVER NE ARKANSAS WHERE THE HRRR IS HINTING AT SOME DEVELOPMENT BEFORE MIDNIGHT. LOOKING AT ANOTHER POTENTIAL MCS SCENARIO LATER TONIGHT AS THE LOW LEVEL JET REDEVELOPS OVER EASTERN OK AND WESTERN AR AND IMPINGES UPON THE WEAK STATIONARY FRONT ACROSS THE AREA. THIS FRONT HAS BEEN HAVING TROUBLE LIFTING NORTH OVER THE LAST COUPLE OF DAYS THANKS TO THE RECENT MCS ACTIVITY AND ASSOCD COLD POOLS. AN AREA OF SHOWERS AND THUNDERSTORMS SHOULD BLOSSOM OVER SRN MISSOURI AFTER MIDNIGHT AND THEN HEAD ESE AND SKIRT THE NORTHERN TIER OF THE MIDSOUTH BY MORNING. POPS WILL DECREASE SHARPLY TOWARD SOUTHERN AREAS OF THE MIDSOUTH. ANOTHER MILD NIGHT ON TAP WITH LOWS IN THE MID 70S. THURSDAY...EXPECT THE MCS TO SKIRT THE NORTHERN TIER AND WEAKEN AS IT SPREADS EAST. BEST CHANCE WILL BE ACROSS NORTHERN AND EASTERN SECTION WITH LESSER CHANCES TOWARD THE SOUTHWEST. MEX GUIDANCE CONTINUES TO BE VERY WARM AND WENT CLOSER TO THE COOLER MET GUIDANCE. EXPECT THAT ANOTHER OUTFLOW BOUNDARY MAY PUSH SOUTH WHICH WILL HELP KEEP A LID ON TEMPS. AREAS SOUTHWEST OF MEMPHIS ARE LIKELY TO GET THE WARMEST AND COULD FLIRT WITH HEAT ADVISORY CRITERIA. THURSDAY NIGHT THROUGH FRIDAY NIGHT...PATTERN REMAINS SIMILAR WITH A BROAD UPPER RIDGE ACROSS THE SOUTHERN U.S AND A WEAK STATIONARY FRONT ACROSS SOUTHERN MISSOURI. EXPECT MCS DEVELOPMENT ALONG THIS FRONT EACH NIGHT WITH THE BEST CHANCES OF PRECIP ALONG THE NORTHERN TIER OF THE MIDSOUTH. CONTINUED TO PREFER THE COOLER MET GUIDANCE THOUGH PARTS OF NORTH MISSISSIPPI AND EAST CENTRAL ARKANSAS WILL FLIRT WITH HEAT ADVISORY CRITERIA ON FRIDAY. SATURDAY THROUGH SUNDAY...CONFIDENCE STARTING TO WANE AT THIS POINT. UPPER RIDGE REMAINS ACROSS THE SOUTHERN U.S. WHILE THE WEAK BOUNDARY TRIES TO SLIP SOUTH INTO THE MIDSOUTH BUT REALLY DOES NOT MOVE MUCH. CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE REGION. MEX STILL TOO WARM. MONDAY THROUGH WEDNESDAY...MEDIUM RANGE MODELS INDICATE THAT AN UPPER TROF WILL DEVELOP OVER THE EASTERN U.S. EARLY NEXT WEEK. THE GFS IS NOT AS DEEP WITH THE TROF WHICH REESTABLISHES NORTHWEST FLOW ACROSS THE REGION AND KEEPS THE SURFACE BOUNDARY IN THE AREA RESULTING IN A RENEWED MCS PATTERN. THE ECMWF HAS A DEEPER TROF AND ACTUALLY PUSHES THE FRONT SOUTH...SHUTTING OFF PRECIP CHANCES. FOR NOW JUST WENT WITH A COMPROMISE OF 20 POPS AND SLIGHTLY COOLER THAN NORMAL TEMPS. SJM && .AVIATION... 00Z TAF CYCLE VFR CONDITIONS EXPECTED AT ALL THE TAF SITES OUTSIDE OF TEMPO LIGHT FOG/MVFR VISIBILITIES NEAR SUNRISE AT MKL...JBR AND TUP. BIGGER CHALLENGE WILL BE THE EXTENT OF THE NEXT FUTURE ROUND OF CONVECTION CROSSING SOUTHERN MISSOURI. FOR NOW THE GREATEST IMPACT WILL BE AT JBR AND MKL...WHILE MEM AND TUP SHOULD STAY JUST FAR ENOUGH SOUTH. CONFIDENCE THOUGH...IS NOT HIGH ENOUGH TO PLACE THUNDERSTORMS ON STATION AT JBR AND MKL...SO WENT WITH TEMPO MIDDAY SHOWERS...BECOMING VCTS LATE. WINDS WILL EITHER REMAIN LIGHT AND VARIABLE OR FROM THE SOUTH AND SOUTHEAST TONIGHT...INCREASING SLIGHTLY FROM THE SOUTH THURSDAY. JAB && .PRELIMINARY POINT TEMPS/POPS... MEM 77 93 78 94 / 30 30 10 30 MKL 73 88 74 91 / 50 60 30 40 JBR 75 90 75 92 / 50 40 30 40 TUP 75 93 75 93 / 20 40 10 40 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS EL PASO TX/SANTA TERESA NM
131 PM MDT TUE AUG 6 2013 .SYNOPSIS... AFTER ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS EVENING AND OVERNIGHT...WE`LL SEE A DECREASE IN STORM ACTIVITY THROUGH EARLY FRIDAY AFTERNOON AS HIGH PRESSURE ALOFT SERVES TO CAP MOST STORM ACTIVITY EXCEPT IN AREA MOUNTAINS. THE RISK OF RAIN WILL INCREASE FRIDAY NIGHT AND SATURDAY AS A BACKDOOR COLD FRONT MOVES NEAR THE REGION BY EARLY FRIDAY AND SOUTHEAST SURFACE WINDS BRING ADDITIONAL MOISTURE. LATER IN THE WEEKEND AND EARLY NEXT WEEK WE SHOULD RETURN TO A WEAK MONSOON PATTERN WITH THE BEST CHANCES OF STORMS OVER FAR WESTERN PORTIONS OF THE AREA. && .DISCUSSION... NOT MUCH CHANGE FROM PREVIOUS THINKING. HRRR BRINGS A CLUSTER OF STORMS NORTH OVER MEXICO THIS EVENING BUT DIMINISHES ACTIVITY AS IT APPROACHES EL PASO/HUDSPETH COUNTIES. MAY REGRET IT BUT I PUSHED POPS ABOVE MOS OVER THAT AREA FOR 1ST PERIOD. OTHERWISE UPPER HIGH BUILDS BACK INTO REGION FOR TOMORROW THROUGH MOST OF FRIDAY BEFORE BACKDOOR COLD FRONT MOVES INTO EASTERN PLAINS OF NM FRIDAY. OVERALL LOWER POPS EXPECTED. GIVEN THE USUAL POOR PERFORMANCE OF MODELS IN HANDLING THESE BACKDOORS...I WOULDN`T BE SURPRISED TO HAVE A FRONTAL PASSAGE LATER FRIDAY INTO EARLY SATURDAY. IN THIS CASE IT WON`T MAKE AS MUCH DIFFERENCE AS IT USUALLY WOULD SINCE WINDS AHEAD OF THE FRONT WILL SWING TO THE SE AND RETURN TROPICAL MOISTURE INTO THE REGION. THIS WILL GIVE THE BEST CHANCE OF SHOWERS AND STORMS AFTER THIS EVENING. IF THE FRONT ARRIVES RAINFALL WOULD BE HEAVIER AND POSSIBLE SEVERE STORMS WOULD COME INTO PLAY. AFTER THAT THE UPPER HIGH AND BUILDS BACK OVER THE AREA GRADUALLY DIMINISHING STORMS ONCE AGAIN INTO EARLY NEXT WEEK. && .AVIATION...VALID 07/00Z-08/00Z. MOSTLY VFR THRU THE PERIOD. 00Z-09Z SCATTERED TSRAGS 3SM BKN060CB TOPS 420. ISOLD AREAS MVFR TO VFR IN/NR TSTMS. SURFACE WINDS SOUTHWEST 12-22KTS...EXCEPT FOR WIND GUSTS TO 45 KTS NEAR STORMS. AFT 09Z SCT080 SCT-BKN 100-200. ISOLD -SHRA UNTIL 18Z THEN VERY ISOLD TS ALL AREAS ESPLY MTNS AND WINDS WSW 15G25KTS. && .FIRE WEATHER... HIGH PRESSURE ALOFT OVER NORTHEAST TEXAS WILL AGAIN CHANNEL THE DEEPER MOISTURE MAINLY OVER SOUTHWESTERN NEW MEXICO WITH SCATTERED AFTERNOON THUNDERSTORMS. AN UPPER TROUGH OVER ARIZONA WILL ALSO PROVIDE SOME ADDITIONAL DYNAMICS FOR THUNDERSTORM DEVELOPMENT MAINLY WEST OF THE RIO GRANDE. EAST OF THE RIO GRANDE THUNDERSTORM DEVELOPMENT WILL BE MORE ISOLATED. THE UPPER TROUGH OVER ARIZONA IS FORECAST TO MOVE ACROSS NEW MEXICO WEDNESDAY BRINGING WIDELY SCATTERED THUNDERSTORMS BUT THEN USHER IN DRIER AIR LATER IN THE DAY. WITH DRIER AIR...THERE WILL BE ONLY A FEW MOUNTAIN THUNDERSTORMS ON THURSDAY. A POSSIBLE WEAK BACK DOOR FRONT WILL MOVE IN TO THE AREA EARLY FRIDAY SHIFTING THE WINDS TO THE SOUTHEAST THEREBY INCREASING THE MOISTURE AT LOWER LEVELS FRIDAY INTO THE WEEKEND. THIS WILL INCREASE THUNDERSTORMS ACROSS THE AREA WITH TEMPERATURES STILL REMAINING MAINLY ABOVE NORMAL. MIN RH VALUES WILL GENERALLY RUN IN THE 25% TO 35% RANGE ALL AREAS TUESDAY AND WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... EL PASO 74 92 75 94 74 / 30 10 10 10 10 SIERRA BLANCA 68 94 69 95 71 / 30 10 20 20 20 LAS CRUCES 68 91 67 91 69 / 10 10 10 10 10 ALAMOGORDO 71 93 68 94 68 / 20 10 20 10 10 CLOUDCROFT 51 67 51 69 49 / 20 20 20 20 20 TRUTH OR CONSEQUENCES 67 90 67 90 67 / 20 30 10 10 10 SILVER CITY 60 79 58 83 60 / 30 30 10 10 10 DEMING 67 89 64 91 65 / 20 20 10 10 10 LORDSBURG 63 87 63 90 65 / 30 20 10 10 10 WEST EL PASO METRO 74 92 73 94 74 / 30 10 10 10 10 DELL CITY 70 95 69 97 67 / 10 10 10 10 10 FORT HANCOCK 73 95 72 97 72 / 30 10 10 10 20 LOMA LINDA 65 86 66 88 67 / 30 10 10 10 10 FABENS 73 93 71 95 71 / 30 10 10 10 10 SANTA TERESA 70 92 71 93 71 / 30 10 10 10 10 WHITE SANDS HQ 70 92 70 92 69 / 10 10 10 10 10 JORNADA RANGE 67 92 67 92 67 / 10 20 10 10 10 HATCH 66 88 67 89 67 / 20 20 10 10 10 COLUMBUS 66 89 67 91 67 / 20 10 10 10 10 OROGRANDE 72 93 71 94 69 / 20 10 10 10 10 MAYHILL 59 78 58 78 55 / 20 20 20 20 20 MESCALERO 57 79 56 80 56 / 20 20 20 20 20 TIMBERON 57 76 58 77 56 / 20 10 10 20 20 WINSTON 57 78 58 80 57 / 20 40 20 20 10 HILLSBORO 63 84 62 86 63 / 20 30 10 20 10 SPACEPORT 67 90 67 91 67 / 20 20 10 10 10 LAKE ROBERTS 58 78 55 82 58 / 30 40 20 20 10 HURLEY 62 81 61 86 62 / 30 30 10 10 10 CLIFF 61 84 60 88 61 / 40 40 10 20 10 MULE CREEK 56 80 56 85 58 / 40 40 10 10 10 FAYWOOD 63 82 61 85 63 / 20 30 10 10 10 ANIMAS 63 87 65 89 65 / 30 30 20 10 10 HACHITA 64 88 64 90 66 / 30 20 10 10 10 ANTELOPE WELLS 63 86 63 89 65 / 30 30 20 20 10 CLOVERDALE 61 80 61 84 63 / 30 30 20 10 10 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 02/20
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1206 AM CDT TUE AUG 6 2013 .DISCUSSION... SEE AVIATION FOR 06Z TAF ISSUANCE. && .AVIATION... MAINLY VFR CONDITIONS EXPECTED THROUGH THE ISSUANCE PERIOD. NAM AND GFS DEWPOINT DEPRESSION FIELDS STILL HINTING AT LOWER VISIBILITIES THIS MORNING MAINLY IN THE SOUTHWESTERN ZONES. MOST LIKELY WILL BE LIMITED TO KLBX AND POSSIBLY KSGR. THIS AFTERNOON SURFACE LOW PRESSURE WILL FORM IN THE TEXAS PANHANDLE CAUSING THE PRESSURE GRADIENT TO SLIGHTLY STRENGTHEN KEEPING MODERATE WINDS IN PLACE. RAP IS SHOWING A SEA AND BAY BREEZE MAKING ITS WAY INLAND LATER THIS AFTERNOON. GIVEN CONTINUED MODERATE ONSHORE FLOW NOT SOLD ON RAP SOLUTION. WIND SHIFT FROM SEA BREEZE WILL MOST LIKELY BE TRANSIENT AS WAS THE CASE TODAY. 23 && .PREV DISCUSSION... /ISSUED 852 PM CDT MON AUG 5 2013/ UPDATE... NO CHANGE TO THE ONGOING HEAT ADVISORY THAT WILL MOST LIKELY BE IN EFFECT FOR ANOTHER FEW DAYS. THE CURRENT CONFIGURATION OF COUNTIES IS ON POINT AS THESE WILL BE THE COUNTIES THAT EXPERIENCE HEAT INDICES AT (OR GREATER THAN) 108 F...OR WHERE HIGHEST AMBIENT TEMPERATURES WILL OCCUR IN TANDEM WITH HIGHER DEW POINT AIR. ELSEWHERE...LOWER DEW POINT MIX-DOWN DURING PEAK HEATING WILL KEEP HEAT INDICES BELOW DEFINED CRITERIA. THE MESSAGE OF HEAT SAFETY REMAINS THE SAME IF YOU ARE OUTSIDE (NON-SHADED ENVIRONMENT) DURING THE MID MORNING THROUGH EARLY EVENING HOURS...CORE BEING THAT OF REMAINING HYDRATED WHILE KEEPING STRENUOUS ACTIVITY TO A MINIMUM. 31 PREV DISCUSSION... /ISSUED 604 PM CDT MON AUG 5 2013/ DISCUSSION... SEE AVIATION FOR 00Z TAF ISSUANCE. AVIATION... MOSTLY VFR CONDITIONS EXPECTED THROUGH THE ISSUANCE PERIOD. THERE IS ANOTHER CHANCE OF BRIEF MVFR CIGS TUESDAY MORNING AS SOUNDINGS STILL SHOW AN INVERSION IN PLACE AROUND 900MB. THE GREATEST CHANCE OF THIS WILL BE KCXO NORTHWARDS. IN THE SOUTHWESTERN ZONES THERE IS ALSO A CHANCE OF SOME BRIEF MORNING LOW VISIBILITIES. BOTH NAM AND GFS DEW POINT DEPRESSION FIELDS SHOW THIS ALBEIT A TAD OVERDONE PROBABLY. 23 PREV DISCUSSION... /ISSUED 325 PM CDT MON AUG 5 2013/ DISCUSSION... A VERY WARM AFTERNOON ACROSS SOUTHEAST TEXAS AS SOUTHWESTERLY LOW LEVEL WINDS HAVE ALLOWED INLAND TEMPERATURES TO CLIMB INTO THE UPPER 90S AND LOW 100S. TEMPERATURES ALONG THE COAST ARE ONLY IN THE LOW TO MID 90S BUT RISING DEW POINTS BEHIND THE SEA BREEZE HAVE PUSHED APPARENT TEMPERATURES ABOVE 105 DEGREES ALONG THE COAST. THE HEAT ADVISORY HAS BEEN EXTENDED THROUGH TUESDAY AFTERNOON FOR THE CURRENTLY AFFECTED AREA. AREAS FURTHER INLAND HAVE MIXED OUT ENOUGH TO KEEP VALUES BELOW THE 108 DEGREE APPARENT TEMPERATURE REQUIRED FOR ISSUANCE OF A HEAT ADVISORY. NO RELIEF EXPECTED IN THE NEXT FEW DAYS AS TEMPERATURES WILL REMAIN UNSEASONABLY WARM. STRONG SOUTHWESTERLY FLOW BELOW 700MB WILL CONTINUE THROUGH MID WEEK WHICH WILL DRIVE TEMPERATURES INTO THE TRIPLE DIGITS FOR MANY AREAS EACH AFTERNOON. PRECIPITATION CHANCES REMAIN AT OR NEAR ZERO THROUGH THE MIDDLE OF THE WEEK AS THE UPPER LEVEL RIDGE REMAINS FIRMLY PLANTED ACROSS THE STATE. TEMPERATURES WILL BEGIN TO BACK DOWN JUST A BIT ON FRIDAY AS LOW LEVEL MOISTURE BEGINS TO INCREASE IN ASSOCIATION WITH AN INVERTED UPPER TROUGH WHICH WILL TREK WESTWARD ACROSS THE GULF OF MEXICO. MODELS ARE NOW IN BETTER AGREEMENT WITH THIS FEATURE UNDERCUTTING THE UPPER RIDGE ACROSS OUR AREA AND BRINGING INCREASED RAIN CHANCES TO SOUTHEAST TEXAS FOR THIS WEEKEND. GIVEN THE INCREASE IN MODEL AGREEMENT HAVE BUMPED POPS UP SLIGHTLY ON SATURDAY AND SUNDAY OVER THE SOUTHERN HALF OF THE AREA. A RETURN TO DRIER AND WARMER TEMPERATURES IS EXPECTED EARLY NEXT WEEK AS THE TROUGH MOVES INTO MEXICO AND UPPER LEVEL RIDGING BECOMES REESTABLISHED OVER THE REGION. 38 MARINE... LIGHT TO MODERATE ONSHORE WINDS WILL PERSIST FOR MUCH OF THE WEEK AND CONTINUE ON INTO THE WEEKEND. SPEEDS MIGHT REACH CAUTION LEVELS TUESDAY AND TUESDAY NIGHT. AT THE VERY END OF THE WEEK AND OVER THE WEEKEND...A WESTWARD MOVING TROPICAL WAVE IS EXPECTED TO BRING INCREASING SHOWER AND THUNDERSTORM CHANCES TO THE AREA. 42 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 101 78 102 79 102 / 10 10 10 0 0 HOUSTON (IAH) 98 77 100 79 100 / 10 10 10 0 0 GALVESTON (GLS) 93 81 94 82 94 / 10 10 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...HEAT ADVISORY UNTIL 9 PM CDT TUESDAY FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...GALVESTON...HARRIS...JACKSON... LIBERTY...MATAGORDA. GM...NONE. && $$ DISCUSSION...31 AVIATION/MARINE...23
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
946 PM EDT WED AUG 7 2013 .SYNOPSIS... HIGH PRESSURE REMAINS OFF THE COAST THROUGH THURSDAY. SOUTHERLY RETURN FLOW AROUND THE HIGH WILL DRAW TROPICAL MOISTURE UP THE EASTERN SEABOARD. A FRONT MOVES INTO THE MOUNTAINS BY THURSDAY NIGHT INTO FRIDAY AND SLOWLY SHIFTS TO THE SOUTH OF US AFTER THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... AS OF 940 PM EDT WEDNESDAY... PRECIPITATION HAS ENDED ACROSS MOST OF THE REGION. SOME LINGERING LIGHT RAIN WAS WITHIN THE JAMES RIVER BASIN AND PARTS OF THE LOWER DAN RIVER BASIN. BY MIDNIGHT...WE EXPECT MOST...IF NOT ALL...OF THE REAMINING PRECIPITATION TO HAVE DISSIPATED OR EXITED THE REGION. SHOWERS RETURN TO THE FORECAST LATER TONIGHT IN THE WEST IN ADVANCE OF THE NEXT APPROACHING SHORTWAVE TROUGH. HAVE MADE LITTLE IF ANY ADJUSTMENTS TO THE OVERNIGHT TEMPERATURES AND ADDED A FEW MORE AREAS OF FOG THAN PREVIOUSLY FORECAST. AS OF 635 PM EDT WEDNESDAY... NOT A LOT OF BIG CHANGES EARLY THIS EVENING. OUR FOCUS FOR THE BEST COVERAGE OF SHOWERS AND STORMS HEADING INTO THE EVENING REMAINS ACROSS THE MOUNTAINS...AND PERHAPS ONE OR TWO TIERS OF COUNTIES EAST OF THE CREST OF THE BLUE RIDGE. LATEST LOCAL AND REGIONAL RADAR TRENDS SHOW THE FORECAST DECREASE IN COVERAGE AND INTENSITY. THIS TREND IS EXPECTED TO CONTINUE THROUGH THE EVENING. HAVE TWEAKED TRENDS IN HOURLY TEMPERATURES AND DEW POINTS TO REFLECT THE LATEST OBSERVATIONS AND EXPECTED TRENDS THROUGH THE EVENING. AS OF 340 PM EDT WEDNESDAY... SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING WILL DIMINISH WITH THE LOSS OF SOLAR HEATING TONIGHT. CONTINUED THE MENTION OF HEAVY RAIN WITH THUNDERSTORMS BECAUSE SOME OF THE THUNDERSTORMS COULD BE EFFICIENT RAIN PRODUCERS. HOWEVER...NOT EXPECTING WIDESPREAD FLASH FLOODING WITH 1 FFG RELATIVELY HIGH RANGING FROM 1.6 TO 3 INCHES. LOCAL WATER PROBLEMS ARE POSSIBLE DEPENDING ON EVOLUTION AND TRACK OF THUNDERSTORMS. PLACED THE HIGHEST POPS IN THE WEST AND TAPER OFF AS ONE HEAD SOUTHEAST TONIGHT. THERE IS THE POTENTIAL FOR SOME STORMS MOVE INTO THE WESTERN CWA LATE TONIGHT INTO THURSDAY MORNING AS DEPICTED ON HRRR AND ECMWF. WENT WITH WARMER MOS LOW TEMPERATURES FROM THE LOWER 60S IN THE MOUNTAINS TO AROUND 70 DEGREES IN THE SOUTHEAST. ISOLATED SHOWERS THURSDAY MORNING WILL BECOME SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE MOUNTAINS THURSDAY AFTERNOON AND EVENING AS WEAK DISTURBANCES PASS FROM WEST TO EAST IN THE ZONAL UPPER LEVEL WIND FLOW. WITH PRECIPITABLE WATER FORECAST AROUND 2 INCHES AND SOME CAPE...THERE COULD BE SOME THUNDERSTORMS WITH LOCALLY HEAVY RAINS. A FEW OF THE STORMS COULD BE STRONG TO SEVERE ACROSS THE NORTH AS SPC HAS A 5 PERCENT CHANCE FOR A SEVERE STORMS ON THURSDAY. PLAYED HIGH TEMPERATURES ON THURSDAY FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONTS. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 400 PM EDT WEDNESDAY... WITH A CLOSED LOW OVER THE UPPER GREAT LAKES AND A BROAD UPPER RIDGE FROM THE WESTERN ATLANTIC THROUGH THE ARKLATEX...A STATIONARY BOUNDARY WILL REMAIN NEAR OUR REGION THROUGH THE PERIOD. EVERY DAY WILL FEATURE SHOWERS AND STORMS...WITH PERHAPS FRIDAY BEING THE WETTEST DAY. THE BOUNDARY PERHAPS SINKS A LITTLE FURTHER SOUTH AND WITH A WESTERLY/DOWNSLOPING WIND DEVELOPING...THERE MAY BE LESS COVERAGE AND MORE FOCUS ACROSS SOUTHSIDE VIRGINIA AND THE NC PIEDMONT. WITH LITTLE OR NO FLOW...BACKBUILDING AND/OR COLLIDING STORMS...AND HIGH PWATS...THE OPPORTUNITY FOR FLASH FLOODING WILL CONTINUE WITH A FLASH FLOOD WATCH PERHAPS NEEDED AT SOME POINT BASED ON ANTECEDENT CONDITIONS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 400 PM EDT WEDNESDAY... WITH THE UPPER RIDGE CONSOLIDATING AND MOVING TO THE FOUR CORNERS REGION...TROUGHING WILL DEEPEN AND STRENGTHEN ACROSS THE EAST AND MIDDLE ATLANTIC. WITH THE COOLER TEMPS AND LESS MOISTURE...SHOWERS AND STORMS WILL BECOME LESS LIKELY AND SUPPRESSED SOUTH AS THE WEEK WEARS ON. HOWEVER...CAN`T TOTALLY RULE OUT A FEW POP UP SHOWERS REGIONWIDE WITH SUCH CHILLY TEMPS ALOFT FOR THIS TIME OF YEAR. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... AS OF 640 PM EDT WEDNESDAY... CONFIDENCE IS HIGH THAT CURRENT SHRA/TSRA ACTITIVY ACROSS THE REGION WILL CONTINUE TO WANE AS WE PROGRESS THROUGH THE EVENING HOURS. ALSO AT HIGH CONFIDENCE IS THE TREND FOR CIGS/VSBYS TO TREND FROM MAINLY A MIX OF MVFR/VFR CONDITIONS TO LIFR/IFR CONDITIONS BY 10Z/6AM THURSDAY. PRECIPTIATION WILL BE ON THE INCREASE TOWARD THURSDAY MORNING...EPSECIALLY OVER THE MOUNTAIN WITH THE APPROACH OF THE NEXT SHORWAVE TROUGH. COVERAGE WILL INCREASE THROUGH THE DAY THURSDAY WITH CONFIDENCE HIGH THAT THE BEST COVERAGE WILL BE OVER THE MOUNTAINS. FLIGHT CATEGORIES WILL GRADUALLY IMPROVE THROUGH THE MORNING HOURS WITH MOST AREAS MVFR/VFR BY 16Z/NOON. AS OF 130 PM EDT WEDNESDAY... BY FRIDAY-SUNDAY A FRONTAL BOUNDARY WILL BE IN THE VICINITY TO SEE MORE COVERAGE AREA WIDE. THIS WILL KEEP TERMINALS DEALING WITH DELAYS DUE TO STORMS...BUT OVER HALF THE TIME...IT SHOULD BE VFR. DRIER AIR PUSHES INTO NORTH ON MONDAY WITH SCATTERED CONVECTION STILL POSSIBLE ESPECIALLY IN THE SOUTH. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...DS/KK SHORT TERM...KM LONG TERM...KM AVIATION...DS/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
742 PM EDT WED AUG 7 2013 .SYNOPSIS... HIGH PRESSURE REMAINS OFF THE COAST THROUGH THURSDAY. SOUTHERLY RETURN FLOW AROUND THE HIGH WILL DRAW TROPICAL MOISTURE UP THE EASTERN SEABOARD. A FRONT MOVES INTO THE MOUNTAINS BY THURSDAY NIGHT INTO FRIDAY AND SLOWLY SHIFTS TO THE SOUTH OF US AFTER THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... AS OF 635 PM EDT WEDNESDAY... NOT A LOT OF BIG CHANGES EARLY THIS EVENING. OUR FOCUS FOR THE BEST COVERAGE OF SHOWERS AND STORMS HEADING INTO THE EVENING REMAINS ACROSS THE MOUNTAINS...AND PERHAPS ONE OR TWO TIERS OF COUNTIES EAST OF THE CREST OF THE BLUE RIDGE. LATEST LOCAL AND REGIONAL RADAR TRENDS SHOW THE FORECAST DECREASE IN COVERAGE AND INTENSITY. THIS TREND IS EXPECTED TO CONTINUE THROUGH THE EVENING. HAVE TWEAKED TRENDS IN HOURLY TEMPERATURES AND DEW POINTS TO REFLECT THE LATEST OBSERVATIONS AND EXPECTED TRENDS THROUGH THE EVENING. AS OF 340 PM EDT WEDNESDAY... SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING WILL DIMINISH WITH THE LOSS OF SOLAR HEATING TONIGHT. CONTINUED THE MENTION OF HEAVY RAIN WITH THUNDERSTORMS BECAUSE SOME OF THE THUNDERSTORMS COULD BE EFFICIENT RAIN PRODUCERS. HOWEVER...NOT EXPECTING WIDESPREAD FLASH FLOODING WITH 1 FFG RELATIVELY HIGH RANGING FROM 1.6 TO 3 INCHES. LOCAL WATER PROBLEMS ARE POSSIBLE DEPENDING ON EVOLUTION AND TRACK OF THUNDERSTORMS. PLACED THE HIGHEST POPS IN THE WEST AND TAPER OFF AS ONE HEAD SOUTHEAST TONIGHT. THERE IS THE POTENTIAL FOR SOME STORMS MOVE INTO THE WESTERN CWA LATE TONIGHT INTO THURSDAY MORNING AS DEPICTED ON HRRR AND ECMWF. WENT WITH WARMER MOS LOW TEMPERATURES FROM THE LOWER 60S IN THE MOUNTAINS TO AROUND 70 DEGREES IN THE SOUTHEAST. ISOLATED SHOWERS THURSDAY MORNING WILL BECOME SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE MOUNTAINS THURSDAY AFTERNOON AND EVENING AS WEAK DISTURBANCES PASS FROM WEST TO EAST IN THE ZONAL UPPER LEVEL WIND FLOW. WITH PRECIPITABLE WATER FORECAST AROUND 2 INCHES AND SOME CAPE...THERE COULD BE SOME THUNDERSTORMS WITH LOCALLY HEAVY RAINS. A FEW OF THE STORMS COULD BE STRONG TO SEVERE ACROSS THE NORTH AS SPC HAS A 5 PERCENT CHANCE FOR A SEVERE STORMS ON THURSDAY. PLAYED HIGH TEMPERATURES ON THURSDAY FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONTS. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 400 PM EDT WEDNESDAY... WITH A CLOSED LOW OVER THE UPPER GREAT LAKES AND A BROAD UPPER RIDGE FROM THE WESTERN ATLANTIC THROUGH THE ARKLATEX...A STATIONARY BOUNDARY WILL REMAIN NEAR OUR REGION THROUGH THE PERIOD. EVERY DAY WILL FEATURE SHOWERS AND STORMS...WITH PERHAPS FRIDAY BEING THE WETTEST DAY. THE BOUNDARY PERHAPS SINKS A LITTLE FURTHER SOUTH AND WITH A WESTERLY/DOWNSLOPING WIND DEVELOPING...THERE MAY BE LESS COVERAGE AND MORE FOCUS ACROSS SOUTHSIDE VIRGINIA AND THE NC PIEDMONT. WITH LITTLE OR NO FLOW...BACKBUILDING AND/OR COLLIDING STORMS...AND HIGH PWATS...THE OPPORTUNITY FOR FLASH FLOODING WILL CONTINUE WITH A FLASH FLOOD WATCH PERHAPS NEEDED AT SOME POINT BASED ON ANTECEDENT CONDITIONS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 400 PM EDT WEDNESDAY... WITH THE UPPER RIDGE CONSOLIDATING AND MOVING TO THE FOUR CORNERS REGION...TROUGHING WILL DEEPEN AND STRENGTHEN ACROSS THE EAST AND MIDDLE ATLANTIC. WITH THE COOLER TEMPS AND LESS MOISTURE...SHOWERS AND STORMS WILL BECOME LESS LIKELY AND SUPPRESSED SOUTH AS THE WEEK WEARS ON. HOWEVER...CAN`T TOTALLY RULE OUT A FEW POP UP SHOWERS REGIONWIDE WITH SUCH CHILLY TEMPS ALOFT FOR THIS TIME OF YEAR. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 640 PM EDT WEDNESDAY... CONFIDENCE IS HIGH THAT CURRENT SHRA/TSRA ACTITIVY ACROSS THE REGION WILL CONTINUE TO WANE AS WE PROGRESS THROUGH THE EVENING HOURS. ALSO AT HIGH CONFIDENCE IS THE TREND FOR CIGS/VSBYS TO TREND FROM MAINLY A MIX OF MVFR/VFR CONDITIONS TO LIFR/IFR CONDITIONS BY 10Z/6AM THURSDAY. PRECIPTIATION WILL BE ON THE INCREASE TOWARD THURSDAY MORNING...EPSECIALLY OVER THE MOUNTAIN WITH THE APPROACH OF THE NEXT SHORWAVE TROUGH. COVERAGE WILL INCREASE THROUGH THE DAY THURSDAY WITH CONFIDENCE HIGH THAT THE BEST COVERAGE WILL BE OVER THE MOUNTAINS. FLIGHT CATEGORIES WILL GRADUALLY IMPROVE THROUGH THE MORNING HOURS WITH MOST AREAS MVFR/VFR BY 16Z/NOON. AS OF 130 PM EDT WEDNESDAY... BY FRIDAY-SUNDAY A FRONTAL BOUNDARY WILL BE IN THE VICINITY TO SEE MORE COVERAGE AREA WIDE. THIS WILL KEEP TERMINALS DEALING WITH DELAYS DUE TO STORMS...BUT OVER HALF THE TIME...IT SHOULD BE VFR. DRIER AIR PUSHES INTO NORTH ON MONDAY WITH SCATTERED CONVECTION STILL POSSIBLE ESPECIALLY IN THE SOUTH. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...DS/KK SHORT TERM...KM LONG TERM...KM AVIATION...DS/WP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
620 AM CDT TUE AUG 6 2013 .UPDATE... ISSUED AT 620 AM CDT TUE AUG 6 2013 FOG HAS THICKEN UP OVER SOUTHWEST WI...AND PER OBS AND CALLS TO DISPATCH...1/4 MILE VSBYS WERE FAIRLY COMMON. EXPANDED THE DENSE FOG ADV AS A RESULT. BUFKIT SOUNDINGS CONTINUE TO SUGGEST THAT WINDS WILL START TO MIX OUT THE FOG BY 9-10 AM. .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 357 AM CDT TUE AUG 6 2013 AT 3 AM...DENSE FOG WAS REPORTED ACROSS MUCH OF SOUTHEAST MINNESOTA...NORTHEAST IOWA...IN THE WISCONSIN RIVER VALLEY... AND ON THE RIDGE TOPS SURROUNDING THE MISSISSIPPI RIVER. THE VISIBILITIES AT OUR OFFICE IS LESS THAN A QUARTER MILE. AS A TROUGH MOVES THROUGH NORTHEAST IOWA AND WESTERN WISCONSIN EARLY THIS MORNING...THE WINDS WILL INCREASE ALOFT AND SOME DRIER AIR WILL HELP DISSIPATE THE FOG BETWEEN 06.10Z AND 06.14Z. FOR THIS AFTERNOON AND TONIGHT...WE WILL HAVE TO WATCH 2 AREAS OF CONVECTION WHICH IS LOCATED CURRENTLY OVER THE DAKOTAS. THE LATEST RAP SHOWS THAT 850 MB MOISTURE TRANSPORT INTO THESE AREAS WILL KEEP THIS CONVECTION GOING THROUGH THE MORNING. THESE AREAS ARE CAUSING HAVOC ON THE MESO MODELS. BOTH THE 06.00Z NMM AND ARW ARE SHOWING THAT THE CONVECTION OVER NORTH DAKOTA IS THE MOST DOMINANT AND THEY BRING A ROBUST AREA OF SHOWERS AND THUNDERSTORMS INTO SOUTHEAST MINNESOTA AND NORTHEAST IOWA. MEANWHILE THE HRRR SHOW THAT THE CONVECTION ACROSS NORTH DAKOTA WILL MOVE EAST SOUTHEAST ACROSS NORTHERN MINNESOTA. MEANWHILE THE CONVECTION ACROSS WESTERN SOUTH DAKOTA WILL DEVELOP A MESOSCALE VORTICITY WILL DEVELOP OUT OF THIS THUNDERSTORM COMPLEX. LOOKING AT THE LATEST WATER VAPOR AND RADAR IMAGERY THIS ACTUALLY MAKES A LOT OF SENSE. AS THIS VORTICITY ENCOUNTERS INCREASING CAPES ACROSS EASTERN SOUTH DAKOTA...NORTHWEST IOWA...AND SOUTHWEST MINNESOTA...THERE WILL BE THE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS LATE THIS MORNING AND AFTERNOON. ADDITIONAL LINES OF THUNDERSTORMS WILL LIKELY DEVELOP AHEAD OF AN APPROACHING COLD FRONT ACROSS WEST CENTRAL AND NORTHWEST MINNESOTA. THERE IS MORE THAN ADEQUATE SHEAR FOR THESE THUNDERSTORMS TO BECOME ORGANIZED. THIS WILL INCLUDE SPLITTING SUPERCELLS AND BOWING LINE SEGMENTS. THE MAIN SEVERE WEATHER THREAT ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND WEST CENTRAL AND SOUTHWEST WISCONSIN WILL BE LIKELY LARGE HAIL...DAMAGING WINDS...AND POSSIBLY ISOLATED TORNADOES FROM 6 PM THROUGH MIDNIGHT. AS THE COLD FRONT SWEEPS THROUGH THE AREA OVERNIGHT...THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL QUICKLY COME TO AN END ACROSS THE AREA FROM NORTHWEST TO SOUTHEAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 357 AM CDT TUE AUG 6 2013 ON THURSDAY NIGHT AND FRIDAY...THE 06.00Z MODELS ARE IN GOOD AGREEMENT THAT A VIGOROUS SHORT WAVE TROUGH WILL MOVE EAST ACROSS NORTHERN MINNESOTA AND UPPER MICHIGAN. AS THIS OCCURS...A COLD FRONT WILL MOVE SOUTH THROUGH THE NORTHERN HALVES OF MINNESOTA AND WISCONSIN. THERE LOOKS TO BE ENOUGH INSTABILITY AND SYNOPTIC FORCING FOR THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THIS FRONT. WITH THE BEST 0-6 KM SHEAR IN THE WAKE OF THIS SYSTEM...NOT EXPECTING TO SEE ANY SEVERE WEATHER FROM THIS SYSTEM. FROM LATE SATURDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO STRUGGLE WITH THE LOCATION AND TIMING OF SHORT WAVES MOVING OUT OF THE NORTHERN PLAINS. AS A RESULT CONFIDENCE IN THE TIMING AND LOCATION OF PRECIPITATION DURING THIS TIME PERIOD IS LOWER THAN NORMAL. AS A RESULT...JUST WENT WITH THE ALL BLEND FOR THIS TIME PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 620 AM CDT MON AUG 5 2013 SFC TROUGH HELPED CLEAR DENSE FOG FROM KRST EARLY THIS MORNING...BUT MORE FG THEN FORMED A FEW MILES BEHIND THE TROUGH - WHERE THE SKIES WERE CLEAR. THIS COULD STILL IMPACT KRST FOR A COUPLE HOURS EARLY THIS MORNING...MOSTLY IFR/MVFR. KLSE WILL ALSO DEAL WITH SOME BR FOR A FEW HOURS. COLD FRONT WILL SWEEP IN FROM THE WEST TONIGHT...WITH A BAND OF SHRA/TS ALONG AND AHEAD OF IT. THERE WILL BE SOME LOWER VSBYS WITH THE STORMS...AND SOME CLOUD BASE LOWERING. WILL KEEP VFR VCTS/TSRA FOR THE MOMENT...ALLOWING FOR LATER UPDATES WHEN TIMING CAN BE BETTER REFINED. COULD BE SOME ENHANCED GUSTINESS AROUND THE STORMS TOO. THE FRONT LOOKS TO TRACK ACROSS KRST/KLSE IN THE 06-09Z TIME FRAME. MODEL RH FIELDS SUGGESTING THAT LOW STRATUS COULD FOLLOW/DEVELOP IN THE WAKE OF THE FRONT...ESPECIALLY THE NAM. FORECAST CONFIDENCE SHAKY ON JUST HOW LOW CIGS COULD GO...BUT WILL TREND THEM DOWNWARD. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ053>055- 061. MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ094-095. DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ096. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>010- 018-019-029. DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ011-030. && $$ UPDATE.......RIECK SHORT TERM...BOYNE LONG TERM....BOYNE AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
358 AM CDT TUE AUG 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 357 AM CDT TUE AUG 6 2013 AT 3 AM...DENSE FOG WAS REPORTED ACROSS MUCH OF SOUTHEAST MINNESOTA...NORTHEAST IOWA...IN THE WISCONSIN RIVER VALLEY... AND ON THE RIDGE TOPS SURROUNDING THE MISSISSIPPI RIVER. THE VISIBILITIES AT OUR OFFICE IS LESS THAN A QUARTER MILE. AS A TROUGH MOVES THROUGH NORTHEAST IOWA AND WESTERN WISCONSIN EARLY THIS MORNING...THE WINDS WILL INCREASE ALOFT AND SOME DRIER AIR WILL HELP DISSIPATE THE FOG BETWEEN 06.10Z AND 06.14Z. FOR THIS AFTERNOON AND TONIGHT...WE WILL HAVE TO WATCH 2 AREAS OF CONVECTION WHICH IS LOCATED CURRENTLY OVER THE DAKOTAS. THE LATEST RAP SHOWS THAT 850 MB MOISTURE TRANSPORT INTO THESE AREAS WILL KEEP THIS CONVECTION GOING THROUGH THE MORNING. THESE AREAS ARE CAUSING HAVOC ON THE MESO MODELS. BOTH THE 06.00Z NMM AND ARW ARE SHOWING THAT THE CONVECTION OVER NORTH DAKOTA IS THE MOST DOMINANT AND THEY BRING A ROBUST AREA OF SHOWERS AND THUNDERSTORMS INTO SOUTHEAST MINNESOTA AND NORTHEAST IOWA. MEANWHILE THE HRRR SHOW THAT THE CONVECTION ACROSS NORTH DAKOTA WILL MOVE EAST SOUTHEAST ACROSS NORTHERN MINNESOTA. MEANWHILE THE CONVECTION ACROSS WESTERN SOUTH DAKOTA WILL DEVELOP A MESOSCALE VORTICITY WILL DEVELOP OUT OF THIS THUNDERSTORM COMPLEX. LOOKING AT THE LATEST WATER VAPOR AND RADAR IMAGERY THIS ACTUALLY MAKES A LOT OF SENSE. AS THIS VORTICITY ENCOUNTERS INCREASING CAPES ACROSS EASTERN SOUTH DAKOTA...NORTHWEST IOWA...AND SOUTHWEST MINNESOTA...THERE WILL BE THE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS LATE THIS MORNING AND AFTERNOON. ADDITIONAL LINES OF THUNDERSTORMS WILL LIKELY DEVELOP AHEAD OF AN APPROACHING COLD FRONT ACROSS WEST CENTRAL AND NORTHWEST MINNESOTA. THERE IS MORE THAN ADEQUATE SHEAR FOR THESE THUNDERSTORMS TO BECOME ORGANIZED. THIS WILL INCLUDE SPLITTING SUPERCELLS AND BOWING LINE SEGMENTS. THE MAIN SEVERE WEATHER THREAT ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND WEST CENTRAL AND SOUTHWEST WISCONSIN WILL BE LIKELY LARGE HAIL...DAMAGING WINDS...AND POSSIBLY ISOLATED TORNADOES FROM 6 PM THROUGH MIDNIGHT. AS THE COLD FRONT SWEEPS THROUGH THE AREA OVERNIGHT...THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL QUICKLY COME TO AN END ACROSS THE AREA FROM NORTHWEST TO SOUTHEAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 357 AM CDT TUE AUG 6 2013 ON THURSDAY NIGHT AND FRIDAY...THE 06.00Z MODELS ARE IN GOOD AGREEMENT THAT A VIGOROUS SHORT WAVE TROUGH WILL MOVE EAST ACROSS NORTHERN MINNESOTA AND UPPER MICHIGAN. AS THIS OCCURS...A COLD FRONT WILL MOVE SOUTH THROUGH THE NORTHERN HALVES OF MINNESOTA AND WISCONSIN. THERE LOOKS TO BE ENOUGH INSTABILITY AND SYNOPTIC FORCING FOR THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THIS FRONT. WITH THE BEST 0-6 KM SHEAR IN THE WAKE OF THIS SYSTEM...NOT EXPECTING TO SEE ANY SEVERE WEATHER FROM THIS SYSTEM. FROM LATE SATURDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO STRUGGLE WITH THE LOCATION AND TIMING OF SHORT WAVES MOVING OUT OF THE NORTHERN PLAINS. AS A RESULT CONFIDENCE IN THE TIMING AND LOCATION OF PRECIPITATION DURING THIS TIME PERIOD IS LOWER THAN NORMAL. AS A RESULT...JUST WENT WITH THE ALL BLEND FOR THIS TIME PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1124 PM CDT MON AUG 5 2013 CONDITIONS CONTINUE TO DETERIORATE ACROSS THE REGION AS A LOW END MVFR TO IFR STRATUS DECK STALLED ALONG AND EAST OF THE MISSISSIPPI RIVER. FURTHER WEST OF THIS STRATUS IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA...SKIES HAVE CLEARED WITH FOG FORMING DUE TO THE LIGHT WINDS AND RECENT RAINS. EXPECT THAT CONDITIONS WILL CONTINUE TO DROP THROUGH THE NIGHT WITH VISIBILITY DROPPING TO A QUARTER OF A MILE AT TIMES...THOUGH LSE HAS BEEN AT 10SM ALL EVENING DESPITE HAVING A 1KFT DECK OVERHEAD. WARMER AIR WILL MOVE IN TOMORROW MORNING AND WILL HELP TO IMPROVE CONDITIONS RATHER QUICKLY. SHOWERS AND THUNDERSTORMS ARE THEN EXPECTED TO DEVELOP AHEAD OF A COLD FRONT TUESDAY AFTERNOON/EVENING ACROSS MINNESOTA. SOME BRIEF DROPS TO IFR WILL BE POSSIBLE AS THESE STORMS ROLL THROUGH SOMETIME IN THE LATE AFTERNOON AND EARLY EVENING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ086-087- 094-095. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>010- 018-019-029. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
120 AM CDT TUE AUG 6 2013 .UPDATE... ISSUED AT 120 AM CDT TUE AUG 6 2013 FOG CONTINUED TO THICKEN ACROSS AREAS WEST OF THE MISSISSIPPI RIVER EARLY THIS MORNING...PER SFC OBS WITH SUPPORT FROM CALLS TO LOCAL DISPATCHES...SO HAVE ISSUED A DENSE FOG ADV THROUGH 14Z. THE FOG MAY CLEAR A FEW HOURS BEFORE THAT THOUGH AS A WEAK SFC TROUGH MOVES IN. WILL KEEP AN EYE ON TRENDS AND CLEAR THE ADV EARLY IF NEEDED. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 310 PM CDT MON AUG 5 2013 THE NEXT 24 TO 36 HOURS WILL FEATURE A MORE ACTIVE PERIOD WITH A FEW WEATHER SYSTEMS TO CONTEND WITH INCLUDING PRECIPITATION CHANCES THIS EVENING...FOG OVERNIGHT...AND THEN SEVERE THREAT TUESDAY AFTERNOON/EVENING. LATEST WATER VAPOR COMBINED WITH RAP 500MB HEIGHTS SHOW BROAD NORTHWEST FLOW EAST OF THE ROCKIES...WITH NUMEROUS EMBEDDED SHORTWAVE TROUGHS. ONE CURRENTLY MOVING THROUGH MINNESOTA/IOWA...WHILE UPSTREAM ACROSS ALBERTA SITS A MORE VIGOROUS WAVE. FINALLY...A CLOSED POLAR VORTEX RESIDES NEAR HUDSON BAY. FOR THIS EVENING INTO TONIGHT...WILL CARRY A SLIGHT CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS UNTIL UPPER LEVEL SHORTWAVE COMPLETELY EXITS THE AREA. DESPITE SURFACE TROUGH LAGGING BEHIND...AND BUILDING INSTABILITY WITH CLEARING SKIES...SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL SHORTWAVE AND SOME LOW TO MID LEVEL DRYING SHOULD PRECLUDE THE DEVELOPMENT OF ADDITIONAL SHOWERS/STORMS. HAVE ADDED PATCHY TO AREAS OF FOG FOR PARTS OF WISCONSIN...INCLUDING THE MS AND WISCONSIN RIVER VALLEYS OVERNIGHT AS A WEAK SURFACE HIGH BUILDS IN THE WAKE OF THE DEPARTING SYSTEM AND AHEAD OF THE APPROACHING COLD FRONT. NICE SETUP WITH TODAY/S COOL...CLOUDY CONDITIONS AND RECENT RAINFALL...THEN CLEARING SKIES LATE THIS EVENING. SURFACE WIND FIELD DROPS TO 5 KTS OR LESS...AND SOUNDINGS SHOW DECENT BOUNDARY LAYER SATURATION THOUGH TRY TO SHOW A STIFF BREEZE AT ABOUT 500 FT. COULD BE A MORE WIDESPREAD FOG SCENARIO INSTEAD OF JUST THE RIVER VALLEYS...SOMETHING TO WATCH THIS EVENING. THE ALBERTA SHORTWAVE TROUGH THEN TAKES AIM ON THE AREA...AND WILL BE THE FOCUS FOR PUSHING THROUGH A SURFACE COLD FRONT TUESDAY EVENING. BUILDING INSTABILITY DURING THE DAY IS SOMEWHAT CONDITIONAL ON AN EARLY MORNING MCS EXPECTED WELL TO OUR WEST...BUT BY MID AFTERNOON...MUCAPE BETWEEN 1500 AND 2000 J/KG COULD BE REALIZED. THE SHEAR ENVIRONMENT IS MORE THAN SUFFICIENT FOR SEVERE STORMS AS 250 MB JET MAX OVERHEAD PUTS 40 TO 50 KTS OF EFFECTIVE SHEAR ACROSS MUCH OF THE AREA...AND THE LOW-LEVELS HAVE FAVORABLE LAPSE RATES. HODOGRAPHS SHOW MODEST LOOPING. OVERALL...IF INSTABILITY CONDITIONS ARE MET...ENVISION STORM MODE TO FAVOR RIGHT MOVING CLUSTER OF CELLS EVOLVING INTO BOWING SEGMENTS WITH THE MAIN THREAT LARGE HAIL AND DAMAGING WINDS. 0-1 KM SHEAR ENVIRONMENT IS UNIDIRECTIONAL SO NOT EXPECTING A FAVORABLE TORNADO ENVIRONMENT HOWEVER WITH THAT SAID...ANY LINGERING SURFACE BOUNDARIES COULD COMPLICATE THAT. MODEL AGREEMENT ON FRONTAL TIMING IS HIGHER WITH THE 05.12Z GUIDANCE...WHICH ADDS CONFIDENCE TO THE LATE AFTERNOON AND EVENING PRECIPITATION CHANCES. THE NAM REMAINS A FASTER OUTLIER WHILE THE GEM/GFS/ECMWF ARE CONSISTENT WITH A 00 TO 06Z PASSAGE. EARLIER FORECAST TIMING FOR POPS LOOK GOOD SO HAVE CARRIED SIMILAR THINKING. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 310 PM CDT MON AUG 5 2013 THE BIG STORY IN THE LONG TERM WILL BE A CONTINUATION OF THE UNSEASONABLY COOL WEATHER PATTERN AS THE MAIN POLAR VORTEX / CLOSED UPPER LOW WOBBLES ACROSS SOUTHERN CANADA. OUTSIDE OF SCATTERED DAYTIME CUMULUS FIELD ACROSS WISCONSIN WEDNESDAY...HIGH PRESSURE DOMINATES WITH PLEASANT CONDITIONS. HIGHS LOWER TO MIDDLE 70S. ANOTHER SIMILAR DAY THURSDAY...THOUGH BY EVENING INTO THE NIGHT THE CLOSED UPPER LOW WOBBLES FURTHER TO THE SOUTH AS ANOTHER PIECE OF ENERGY ROUNDS THE BASE. THIS TRIES TO DRIVE A SURFACE COLD FRONT WITH SHOWERS AND THUNDERSTORMS ACROSS CENTRAL MINNESOTA INTO WISCONSIN. HOWEVER...BETTER DYNAMICS AND MOISTURE TRANSPORT REMAIN IN THE WEST AND NORTH FORECAST...AND THE FRONT WASHES OUT BEFORE MAKING IT VERY FAR INTO THE FORECAST AREA. WILL CONTINUE SLIGHT CHANCES IN THE NORTHWEST WHILE THE REST OF THE AREA WILL LIKELY ONLY SEE INCREASED CLOUD COVER. IN THE WAKE OF THIS SHORTWAVE TROUGH...A REINFORCING SHOT OF COOLER AIR SURGES IN AS SEEN BY 850 MB TEMPERATURES FRIDAY AND SATURDAY DROPPING TO THE 8 TO 10C RANGE. HIGHS IN THE 70S AND OVERNIGHT LOWS COULD DIP INTO THE UPPER 40S TO LOWER 50S...ESPECIALLY FOR THE TYPICAL COOLER SPOTS OF CENTRAL WISCONSIN. DEPENDING ON THE HIGH PRESSURE AXIS...COULD SEE A FEW MORNINGS OF RIVER VALLEY FOG AS WELL. OVERALL...VERY NICE CONDITIONS FOR EARLY/MID AUGUST POSSIBLE ACROSS THE ENTIRE UPPER MIDWEST FROM FRIDAY INTO EARLY NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1124 PM CDT MON AUG 5 2013 CONDITIONS CONTINUE TO DETERIORATE ACROSS THE REGION AS A LOW END MVFR TO IFR STRATUS DECK STALLED ALONG AND EAST OF THE MISSISSIPPI RIVER. FURTHER WEST OF THIS STRATUS IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA...SKIES HAVE CLEARED WITH FOG FORMING DUE TO THE LIGHT WINDS AND RECENT RAINS. EXPECT THAT CONDITIONS WILL CONTINUE TO DROP THROUGH THE NIGHT WITH VISIBILITY DROPPING TO A QUARTER OF A MILE AT TIMES...THOUGH LSE HAS BEEN AT 10SM ALL EVENING DESPITE HAVING A 1KFT DECK OVERHEAD. WARMER AIR WILL MOVE IN TOMORROW MORNING AND WILL HELP TO IMPROVE CONDITIONS RATHER QUICKLY. SHOWERS AND THUNDERSTORMS ARE THEN EXPECTED TO DEVELOP AHEAD OF A COLD FRONT TUESDAY AFTERNOON/EVENING ACROSS MINNESOTA. SOME BRIEF DROPS TO IFR WILL BE POSSIBLE AS THESE STORMS ROLL THROUGH SOMETIME IN THE LATE AFTERNOON AND EARLY EVENING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ086-087- 094-095. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>010- 018-019-029. && $$ UPDATE.......RIECK SHORT TERM...ZT LONG TERM....ZT AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1124 PM CDT MON AUG 5 2013 .UPDATE... ISSUED AT 912 PM CDT MON AUG 5 2013 DIURNAL CONVECTION HAS GENERALLY COME TO AN END ACROSS THE REGION WITH SOME TRAILING SHOWERS LINGERING IN SOUTHWEST WISCONSIN ALONG A WEAK SURFACE TROUGH/COLD FRONT. MID LEVEL SUBSIDENCE NOTED ON WATER VAPOR HAS ALLOWED FOR SKIES TO CLEAR OUT ACROSS MUCH OF MINNESOTA AND IOWA. IT WAS LOOKING LIKE WISCONSIN WOULD GET IN ON THE CLEARING AS WELL...BUT A LOW LEVEL STRATUS DECK GOT STUCK UNDER A SHALLOW INVERSION AROUND 1500FT AND HAS STALLED OUT FROM FAR EASTERN MINNESOTA/IOWA ON INTO WESTERN WISCONSIN. WITH THE LOW LEVEL SURGE OF DRIER AIR APPEARING TO HAVE STALLED OUT TO THE WEST...AM BECOMING MORE CONCERNED FOR THE POTENTIAL OF DENSE FOG TONIGHT. THE MAIN UNCERTAINTY IS WITH WHETHER THIS WILL JUST STAY AS A LOW LEVEL STRATUS DECK BECAUSE OF SOME STRONGER...10KT...WINDS AT THE INVERSION LEVEL OR IF THE SATURATION WILL JUST CONTINUE ON DOWN TO THE GROUND OVERNIGHT. SOME REPORTS FROM NORTHEAST IOWA HAVE BEEN THAT VISIBILITY HAS DROPPED DOWN TO AN EIGHTH OF A MILE IN SPOTS IN EASTERN FILLMORE COUNTY AND NORTHERN WINNESHIEK COUNTIES. WITH SUCH HIGH MOISTURE ALREADY IN PLACE...AM LEANING MORE ALONG THE FOG SOLUTION RATHER THAN JUST STRATUS. IF QUARTER MILE VISIBILITIES BECOME MORE WIDESPREAD...MAY HAVE TO DO A DENSE FOG ADVISORY OVERNIGHT. ALSO...DESPITE LOW LEVEL FORCING LOOKING WEAK...ALSO CAN NOT RULE OUT SOME DRIZZLE WITH THESE LOW CEILINGS. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 310 PM CDT MON AUG 5 2013 THE NEXT 24 TO 36 HOURS WILL FEATURE A MORE ACTIVE PERIOD WITH A FEW WEATHER SYSTEMS TO CONTEND WITH INCLUDING PRECIPITATION CHANCES THIS EVENING...FOG OVERNIGHT...AND THEN SEVERE THREAT TUESDAY AFTERNOON/EVENING. LATEST WATER VAPOR COMBINED WITH RAP 500MB HEIGHTS SHOW BROAD NORTHWEST FLOW EAST OF THE ROCKIES...WITH NUMEROUS EMBEDDED SHORTWAVE TROUGHS. ONE CURRENTLY MOVING THROUGH MINNESOTA/IOWA...WHILE UPSTREAM ACROSS ALBERTA SITS A MORE VIGOROUS WAVE. FINALLY...A CLOSED POLAR VORTEX RESIDES NEAR HUDSON BAY. FOR THIS EVENING INTO TONIGHT...WILL CARRY A SLIGHT CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS UNTIL UPPER LEVEL SHORTWAVE COMPLETELY EXITS THE AREA. DESPITE SURFACE TROUGH LAGGING BEHIND...AND BUILDING INSTABILITY WITH CLEARING SKIES...SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL SHORTWAVE AND SOME LOW TO MID LEVEL DRYING SHOULD PRECLUDE THE DEVELOPMENT OF ADDITIONAL SHOWERS/STORMS. HAVE ADDED PATCHY TO AREAS OF FOG FOR PARTS OF WISCONSIN...INCLUDING THE MS AND WISCONSIN RIVER VALLEYS OVERNIGHT AS A WEAK SURFACE HIGH BUILDS IN THE WAKE OF THE DEPARTING SYSTEM AND AHEAD OF THE APPROACHING COLD FRONT. NICE SETUP WITH TODAY/S COOL...CLOUDY CONDITIONS AND RECENT RAINFALL...THEN CLEARING SKIES LATE THIS EVENING. SURFACE WIND FIELD DROPS TO 5 KTS OR LESS...AND SOUNDINGS SHOW DECENT BOUNDARY LAYER SATURATION THOUGH TRY TO SHOW A STIFF BREEZE AT ABOUT 500 FT. COULD BE A MORE WIDESPREAD FOG SCENARIO INSTEAD OF JUST THE RIVER VALLEYS...SOMETHING TO WATCH THIS EVENING. THE ALBERTA SHORTWAVE TROUGH THEN TAKES AIM ON THE AREA...AND WILL BE THE FOCUS FOR PUSHING THROUGH A SURFACE COLD FRONT TUESDAY EVENING. BUILDING INSTABILITY DURING THE DAY IS SOMEWHAT CONDITIONAL ON AN EARLY MORNING MCS EXPECTED WELL TO OUR WEST...BUT BY MID AFTERNOON...MUCAPE BETWEEN 1500 AND 2000 J/KG COULD BE REALIZED. THE SHEAR ENVIRONMENT IS MORE THAN SUFFICIENT FOR SEVERE STORMS AS 250 MB JET MAX OVERHEAD PUTS 40 TO 50 KTS OF EFFECTIVE SHEAR ACROSS MUCH OF THE AREA...AND THE LOW-LEVELS HAVE FAVORABLE LAPSE RATES. HODOGRAPHS SHOW MODEST LOOPING. OVERALL...IF INSTABILITY CONDITIONS ARE MET...ENVISION STORM MODE TO FAVOR RIGHT MOVING CLUSTER OF CELLS EVOLVING INTO BOWING SEGMENTS WITH THE MAIN THREAT LARGE HAIL AND DAMAGING WINDS. 0-1 KM SHEAR ENVIRONMENT IS UNIDIRECTIONAL SO NOT EXPECTING A FAVORABLE TORNADO ENVIRONMENT HOWEVER WITH THAT SAID...ANY LINGERING SURFACE BOUNDARIES COULD COMPLICATE THAT. MODEL AGREEMENT ON FRONTAL TIMING IS HIGHER WITH THE 05.12Z GUIDANCE...WHICH ADDS CONFIDENCE TO THE LATE AFTERNOON AND EVENING PRECIPITATION CHANCES. THE NAM REMAINS A FASTER OUTLIER WHILE THE GEM/GFS/ECMWF ARE CONSISTENT WITH A 00 TO 06Z PASSAGE. EARLIER FORECAST TIMING FOR POPS LOOK GOOD SO HAVE CARRIED SIMILAR THINKING. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 310 PM CDT MON AUG 5 2013 THE BIG STORY IN THE LONG TERM WILL BE A CONTINUATION OF THE UNSEASONABLY COOL WEATHER PATTERN AS THE MAIN POLAR VORTEX / CLOSED UPPER LOW WOBBLES ACROSS SOUTHERN CANADA. OUTSIDE OF SCATTERED DAYTIME CUMULUS FIELD ACROSS WISCONSIN WEDNESDAY...HIGH PRESSURE DOMINATES WITH PLEASANT CONDITIONS. HIGHS LOWER TO MIDDLE 70S. ANOTHER SIMILAR DAY THURSDAY...THOUGH BY EVENING INTO THE NIGHT THE CLOSED UPPER LOW WOBBLES FURTHER TO THE SOUTH AS ANOTHER PIECE OF ENERGY ROUNDS THE BASE. THIS TRIES TO DRIVE A SURFACE COLD FRONT WITH SHOWERS AND THUNDERSTORMS ACROSS CENTRAL MINNESOTA INTO WISCONSIN. HOWEVER...BETTER DYNAMICS AND MOISTURE TRANSPORT REMAIN IN THE WEST AND NORTH FORECAST...AND THE FRONT WASHES OUT BEFORE MAKING IT VERY FAR INTO THE FORECAST AREA. WILL CONTINUE SLIGHT CHANCES IN THE NORTHWEST WHILE THE REST OF THE AREA WILL LIKELY ONLY SEE INCREASED CLOUD COVER. IN THE WAKE OF THIS SHORTWAVE TROUGH...A REINFORCING SHOT OF COOLER AIR SURGES IN AS SEEN BY 850 MB TEMPERATURES FRIDAY AND SATURDAY DROPPING TO THE 8 TO 10C RANGE. HIGHS IN THE 70S AND OVERNIGHT LOWS COULD DIP INTO THE UPPER 40S TO LOWER 50S...ESPECIALLY FOR THE TYPICAL COOLER SPOTS OF CENTRAL WISCONSIN. DEPENDING ON THE HIGH PRESSURE AXIS...COULD SEE A FEW MORNINGS OF RIVER VALLEY FOG AS WELL. OVERALL...VERY NICE CONDITIONS FOR EARLY/MID AUGUST POSSIBLE ACROSS THE ENTIRE UPPER MIDWEST FROM FRIDAY INTO EARLY NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1124 PM CDT MON AUG 5 2013 CONDITIONS CONTINUE TO DETERIORATE ACROSS THE REGION AS A LOW END MVFR TO IFR STRATUS DECK STALLED ALONG AND EAST OF THE MISSISSIPPI RIVER. FURTHER WEST OF THIS STRATUS IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA...SKIES HAVE CLEARED WITH FOG FORMING DUE TO THE LIGHT WINDS AND RECENT RAINS. EXPECT THAT CONDITIONS WILL CONTINUE TO DROP THROUGH THE NIGHT WITH VISIBILITY DROPPING TO A QUARTER OF A MILE AT TIMES...THOUGH LSE HAS BEEN AT 10SM ALL EVENING DESPITE HAVING A 1KFT DECK OVERHEAD. WARMER AIR WILL MOVE IN TOMORROW MORNING AND WILL HELP TO IMPROVE CONDITIONS RATHER QUICKLY. SHOWERS AND THUNDERSTORMS ARE THEN EXPECTED TO DEVELOP AHEAD OF A COLD FRONT TUESDAY AFTERNOON/EVENING ACROSS MINNESOTA. SOME BRIEF DROPS TO IFR WILL BE POSSIBLE AS THESE STORMS ROLL THROUGH SOMETIME IN THE LATE AFTERNOON AND EARLY EVENING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...ZT LONG TERM....ZT AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
521 PM MDT WED AUG 7 2013 .UPDATE... ISSUED AT 518 PM MDT WED AUG 7 2013 UPDATED FORECAST FOR THIS EVENING TO INCLUDE THE SEVERE THUNDERSTORM WATCH FOR CONVERSE...NIOBRARA COUNTIES IN ADDITION TO THE NORTHERN NEBRASKA PANHANDLE. THIS WATCH IS IN EFFECT UNTIL 11 PM TONIGHT FOR THE THREAT OF LARGE HAIL AND DAMAGING WINDS. SEVERE THUNDERSTORMS SHOULD BE RATHER ISOLATED IN NATURE THROUGH THIS EVENING. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 300 PM MDT WED AUG 7 2013 SHOWERS AND THUNDERSTORMS WERE DEVELOPING EARLY THIS AFTERNOON OVER VARIOUS PARTS OF THE CWA. THE ACTIVITY IS SLOWLY BECOMING MORE INTENSE...BUT SO FAR HAS BEEN HINDERED SOME BY THE CIRRUS CURRENTLY OVER THE AREA. AT LEAST A SCATTERED COVERAGE OF STORMS SHOULD CONTINUE THROUGH EARLY THURSDAY MORNING. THE ATMOSPHERE IS MOIST AND UNSTABLE WITH SURFACE FORCING NEAR THE MOUNTAINS. IN ADDITION...A SHORTWAVE TROUGH NEAR THE FOUR CORNERS REGION EARLY THIS AFTERNOON WILL MOVE NORTHEAST AND NEAR THE CWA THROUGH EARLY THURSDAY MORNING. THE MAIN THREAT STILL APPEARS TO BE A PERIOD OF HEAVY RAIN...SMALL HAIL AND GUSTY WINDS THROUGH THE EVENING. THE BEST POTENTIAL FOR SEVERE STORMS WILL BE IN THE NORTH PART OF THE CWA IN THE AREA OF BETTER 0-6 KM SHEAR THROUGH THIS EVENING. AREAS OF LOW CLOUDS AND FOG WILL BE POSSIBLE LATER TONIGHT AND INTO MID MORNING THURSDAY FROM KSNY TO THE SOUTHERN LARAMIE RANGE. BY MIDDAY THURSDAY...HEIGHTS ALOFT BUILD OVER THE ROCKIES WITH A SHORTWAVE RIDGE OVER THE AREA THROUGH FRIDAY. THE PLUME OF MID AND UPPER LEVEL MOISTURE WILL BE MAINLY OVER THE SOUTH PART OF THE CWA THURSDAY AND THEN OVER THE ENTIRE CWA FRIDAY. MOIST BOUNDARY LAYER UPSLOPE WINDS WILL CONTINUE THROUGH FRIDAY WITH SURFACE DEW POINTS IN THE 50S TO THE EAST OF THE LARAMIE RANGE. PRECIPITABLE WATER VALUES THROUGH THAT TIME WILL CONTINUE TO RANGE FROM NEAR ONE HALF INCH OVER SOUTH CENTRAL WYOMING TO AN INCH OVER THE PANHANDLE. A SCATTERED COVERAGE OF AFTERNOON AND EVENING THUNDERSTORMS WILL AGAIN TAKE PLACE OVER THE CWA ON THURSDAY. THEN ON FRIDAY...MODELS MOVE A MORE SIGNIFICANT SHORTWAVE NEAR THE CWA. THAT SHOULD RESULT IN MORE COVERAGE AND PERHAPS HEAVIER RAINFALL. TEMPERATURES WILL BE SIMILAR OVER THE CWA THROUGH FRIDAY WITH READINGS NEAR OR JUST BELOW NORMAL. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 300 PM MDT WED AUG 7 2013 NEW ECMWF 12Z RUN CONTINUES TO BE MORE BULLISH ON QPF...PARTICULARLY WEST OF THE LARAMIE RANGE FRIDAY NIGHT. NAM/WRF BACKS THE ECMWF SOLUTIONS...SO KEPT PRETTY HIGH POPS GOING OUT WEST FRIDAY NIGHT. THIS IS DUE TO A PRETTY POTENT VORT MAX TRACKING NORTHEAST THROUGH THE RIDGE. ITS REALLY SLOW MOVING TO THE NORTHEAST AND BY SATURDAY MORNING...IT FINALLY CLEARS TO CWFA. SO CURRENTLY THINKING IS FOR SHOWERS AND THUNDERSTORMS TO CONTINUE ALL NIGHT...PARTICULARLY OUT WEST AND INTO CONVERSE COUNTY. RESIDUAL MOISTURE AND UPSLOPING WINDS EAST OF THE LARAMIE RANGE WILL AID IN ANOTHER ROUND OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS SATURDAY AND SATURDAY EVENING. WE ARE LOOKING AT THE BROKEN RECORD CONTINUING THROUGH MID WEEK AS MONSOONAL MOISTURE REMAINS OVER THE AREA. ITS A GOOD PROBLEM TO HAVE AS WE ARE STILL WAY BELOW ON RAINFALL...AND THE RAIN KEEPS FIRE WEATHER CONCERNS AT BAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 1046 AM MDT WED AUG 7 2013 LOOKS LIKE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS FOR THIS AFTERNOON. LATEST HRRR FORECAST SHOWING THUNDERSTORMS FORMING ALONG A LINE JUST NORTH OF CHADRON OVER TO LUSK AROUND 19Z...SWEEPING SOUTH THROUGH THE SOUTHERN PANHANDLE BY 00Z. BASED TIMING ON ITS FORECAST. THEN BEHIND THE LINE...WE SEE A NORTHEAST WIND DEVELOPING BEHIND THIS LINE. HRRR AND SREF SHOWING A FAIRLY WIDESPREAD AND PROLONGED LOW CEILING EVENT WITH THESE NORTHEAST UPSLOPING WINDS. BELIEVE THE MOST PROBABLE AREA WILL BE HERE AT KCYS AND KSNY IN THE SOUTHERN PANHANDLE. BUT KAIA AND KBFF COULD ALSO BE IMPACTED. SHOULD THESE AIRPORTS AND THE PANHANDLE RECEIVE GOOD RAINFALL TODAY...THEN CONFIDENCE WILL CERTAINLY GROW THAT IT WILL HAPPEN. && .FIRE WEATHER... ISSUED AT 300 PM MDT WED AUG 7 2013 MONSOONAL MOISTURE WILL REMAIN OVER THE CWA THROUGH AT LEAST FRIDAY. THE RESULT WILL BE AT LEAST A SCATTERED COVERAGE OF MAINLY LATE DAY SHOWERS AND THUNDERSTORMS EACH DAY AND TEMPERATURES AT OR JUST BELOW NORMAL. THE ATMOSPHERE DRIES SOME FOR THE WEEKEND AND EARLY NEXT WEEK AND MAY RESULT IN MARGINAL FIRE WEATHER CONDITIONS FOR THE LOWER ELEVATIONS OF THE WEST PART OF THE CWA. HOWEVER...WINDS IN MOST AREAS WILL BE FAIRLY LIGHT THROUGH EARLY NEXT WEEK. IN GENERAL THAT LEADS TO A REDUCED FIRE WEATHER CONCERN OVER THE CWA DURING THAT TIME. DRY THUNDERSTORMS WILL BE A POSSIBILITY ON SOME DAYS OVER THE LOWER ELEVATIONS OF CARBON COUNTY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...TJT SHORT TERM...WEILAND LONG TERM...CLAYCOMB AVIATION...CLAYCOMB FIRE WEATHER...WEILAND
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1039 PM MDT WED AUG 7 2013 .UPDATE... ISSUED AT 1039 PM MDT WED AUG 7 2013 UPDATED TO CANCEL THE FLASH FLOOD WATCH. MUCH OF THE PRECIPITATION OVER SOUTHERN COLORADO AND SOUTHEAST UT HAS DIMINISHED AND THE THREAT OF FLOODING HAS ENDED. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 320 PM MDT WED AUG 7 2013 COMPLEX WEATHER PATTERN AFFECTING THE REGION THIS AFTERNOON. AT THE SURFACE THERE IS A WEAK QUASI STATIONARY FRONTAL BOUNDARY DRAPED NEAR THE WY BORDER. ALOFT AND STUCK IN AN UPPER LEVEL RIDGE AXIS IS A SHORTWAVE TROUGH CENTERED IN SOUTH CENTRAL UT. WHILE THE CENTER OF ROTATION WILL STRUGGLE TO MOVE EAST TONIGHT AS EVIDENCED BY THE RAP MODEL...ITS TROUGH WILL ROTATE NORTHEAST INTO SOUTHERN CO. AXIS OF GREATEST INSTABILITY...MUCAPES 1000 TO 2000 J/KG... EXTENDS ALONG THE CO/NM BORDER AT THIS TIME AND THIS INDEED IS WHERE THE MOST VIGOROUS CONVECTION HAS DEVELOPED. THESE STORMS WILL MOVE NORTHEAST INTO SOUTHWEST CO AND INTO THE SAN JUAN MTNS THROUGH EARLY EVENING. MEANWHILE...RAINFALL ASSOCIATED WITH THE CENTER OF ROTATION ACROSS SRN UT WILL ALSO MOVE EAST. OBSERVED RAINFALL RATES SO FAR THIS AFTERNOON HAVE BEEN 0.2 TO 0.3/HOUR IN PARTS OF THE SAN JUANS AND IN THE CENTRAL MTNS. EXPECT EVEN HIGHER RATES TO OCCUR WITH THE STRONG CONVECTION. SO FLASH FLOOD WATCH LOOKS GOOD AND WILL REMAIN IN EFFECT THROUGH MIDNIGHT. THERE IS A MID LEVEL SHEAR AXIS BASICALLY ALONG I-70 WITH DRIER AIR TO THE NORTH. CONSEQUENTLY CONVECTION NORTH OF I-70 WILL BE LESS ROBUST. EXPECT SHOWERS TO DIMINISH OVERNIGHT BUT LINGER OVER THE CENTRAL AND SOUTHERN AREAS TO SOME EXTENT. ON THURSDAY...THE SHORTWAVE SHOULD BE EAST OF THE AREA WITH THE RIDGE AXIS AGAIN DOMINATING. HOWEVER...THERE WILL STILL BE MID TO HIGH LEVEL MOISTURE TRAPPED UNDER THE RIDGE...SO EXPECT ISOLATED TO SCATTERED CONVECTION DIURNAL CONVECTION WEST TO NUMEROUS STORMS EAST...FOCUSED ON THE USUAL HIGHER TERRAIN LOCATIONS. SLIGHTLY LESS CLOUD COVER INITIALLY ON THURSDAY WILL HELP TEMPS RISE A LITTLE QUICKER AND HIGHER THAN TODAY...THOUGH STILL REMAIN BELOW NORMAL. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 320 PM MDT WED AUG 7 2013 THE LARGE SCALE PATTERN CHANGES LITTLE AS A LOW PRESSURE TROUGH CONTINUES TO SIT ALONG THE WEST COAST...AND HIGH PRESSURE REMAINS PARKED OVER TEXAS. AFTER A BRIEF PERIOD OF NORTH/NORTHWEST FLOW BEHIND TODAY`S DISTURBANCE...SOUTHERLY FLOW WILL QUICKLY BECOME REESTABLISHED ON FRIDAY. HOWEVER MODELS CONTINUE TO ADVERTISE A MODEST DROP IN MOISTURE ACROSS THE AREA. THESE SOMEWHAT DRIER CONDITIONS WILL THEN PERSIST THROUGH THE EARLY PART OF NEXT WEEK. PRECIPITABLE WATER WILL DROP FROM TODAY`S VALUES OF 0.6-1.0 INCH ...NORTH-SOUTH/CENTRAL TO MORE LIKE 0.4-0.6 INCH ACROSS MOST OF THE AREA. THE LATEST MODEL RUNS HAVE DELAYED FURTHER DRYING UNTIL AROUND MIDWEEK. BETTER SUNSHINE AND THIS MODEST AMOUNT OF MOISTURE WILL STILL RESULT IN ISOLATED TO SCATTERED AFTERNOON SHOWER AND THUNDERSTORM DEVELOPMENT...BUT THIS WILL GENERALLY BE TIED TO THE HIGHER TERRAIN IN THIS DRIER ENVIRONMENT. ONE WEAK DISTURBANCE WILL PASS ACROSS ID/WY AROUND THE TOP OF THE RIDGE ON FRIDAY FOR A LITTLE ENHANCEMENT ACROSS THE NORTH...OTHERWISE THE SOUTH WILL BE FAVORED. THE 12Z GFS AND ECMWF RUNS SHOW GOOD AGREEMENT WITH THIS PERSISTENT PATTERN...AND AS THE HIGH EVENTUALLY SHIFTS WEST INTO SOUTHERN NM/AZ BY THE MIDDLE OF NEXT WEEK. AS THE HIGH REACHES SOUTHERN NM...IT WILL TEND TO BLOCK THE SUBTROPICAL MOISTURE STREAM. THEREFORE LOOK FOR ANOTHER NOTCH OF DRYING. IN SPITE OF GOOD MODEL AGREEMENT...SUBSEQUENT MODEL RUNS HAVE SLOWED THE DRYING TREND. THEREFORE CONFIDENCE IS NOT OVERLY HIGH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1039 PM MDT WED AUG 7 2013 VFR CONDITIONS WILL PREVAIL AT THE TAFS SITES TONIGHT. AREAS OF PRECIPITATION OVER SW CO AND SE UT WILL PRODUCE LOCAL MOUNTAIN OBSCURATIONS. SCATTERED THUNDERSTORMS SHOULD FORM THURSDAY AFTERNOON AND EVENING...MAINLY OVER THE MOUNTAINS. KASE...KRIL... AND KEGE HAVE ABOUT AT 15 PERCENT CHANCE OF MVFR VSBYS IN STRONGER RAIN SHOWERS. THE STORMS WILL CAUSE LOCAL MOUNTAINS OBSCURATIONS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...CC SHORT TERM...BWM LONG TERM...EH AVIATION...CC
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
403 AM CDT Thu Aug 8 2013 ...UPDATED LONG TERM SECTION... .SYNOPSIS... ISSUED AT 1010 PM CDT WED AUG 7 2013 The 08.00Z 250 hPa showed 50 KT flow extending from KDDC increasing to around 100 KT at KAPX. @ 500 hPa, a 577-580 decameter cyclone was spinning off northwest California. Downstream, an open wave was moving across the central Rockies. A huge 550 decameter cyclone was noted across west central Ontario. @ 700 hPa, easterly upslope flow was observed at KDDC. This upslope flow also continued at 850 hPa and down to the sfc. The precipitable water for KDDC was 1.41" (above the 75th percentile for a Gaussian distribution). At the sfc, a stationary front was located across the KS/OK state border. KDDC WSR-88D was busy indicating an MCS to the west. && .SHORT TERM...(Today and tonight) ISSUED AT 254 AM CDT THU AUG 8 2013 ...Pretty busy shift this morning. Most of the attention was paid to overnight convection and then some to this afternoon... This morning: A fairly significant rain event occurred through the overnight period. Rainfall reports have been pretty sparse given the fact that it is O`Dark Thirty. We should get more reports by dawn. A few reports have trickled in with 3.00" in Hugoton, 1.50" by Richfield, and a few flash flooding reports. Here at the KDDC airport as of 07:24Z, we have had a measly half of an inch. Southern Ford county and other areas probably saw 2" to 4" via estimation from radar. Anyway, given the initial event, canceled the Flood Watch and issued a Flash Flood Watch instead. So, why all the precip? Well, an upper level wave, 850 hPa theta-e advection, pwats around the 75th percentile, sfc-700 hPa upslope flow, and isentropic lift was the impetus for MCS formation. For the rest of the early morning, will taper precipitation probability percentage points west to east via radar trends and HRRR guidance. FWIW, the 00Z NAM performed poorly for the event. Will carry the FF.A (Flash Flood Watch) until 18Z. Today/tonight: We should see some break in the precipitation from the morning activity to possible additional activity later this afternoon as temporary subsidence builds in the wake of the departing MCS. Forecast skew-t/log-p`s show pwats still in the 1.50-1.70" range this afternoon. A moist upslope flow will also continue from the sfc up through 800 hPa. The main synoptic wave mentioned in the synopsis will have translated over western Kansas by afternoon, and this will provide some upper level support for additional lift. The atmosphere will become unstable again with 1000-2000 J/kg of SBCAPE. Low to mid level lapse rates are fairly moist adiabatic, so the CAPE profile is fairly skinny. Bulk shear vectors are SW/40 KT. All and all, tomorrow does not look that impressive for severe weather (supercells etc). What does look more promising is another MCS. There is significant questions in regarding convective initiation/placement. The ECMWF and both cores of the WRF look reasonable. The atmosphere could be "worked over" from the morning convection, so a lack of additional activity is also possible. Anywho, will carry chance precipitation probabilities this afternoon and ramp them up to likely region wide by tonight. Maximums will be in the 70sF and minimums in the 60sF. .LONG TERM...(Friday through Wednesday) ISSUED AT 353 AM CDT THU AUG 8 2013 A shortwave trough will move across the central plains reaching the lower Missouri River Valley by late Friday with shortwave ridging moving into the western plains. This will provide a break in precipitation chances from late Friday into Saturday night with surface ridging across Kansas. Low level moisture will still be around, however, given all the saturated ground providing ample evapotranspiration...so dewpoint temperatures will remain int he 60s for the most part despite there being some mid level subsidence. Some subtropical jet energy will begin to move into the desert Southwest region impinging on the southern Rockies by Sunday night into early next week...and this is when precipitation chances will once again be on the increase. As far as the grids go...no changes were made to the forecast and the latest all-blend guidance was used for the Sunday-Thursday time frame. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) ISSUED AT 1212 AM CDT THU AUG 8 2013 MVFR cigs expected through the overnight with VFR cigs after 15Z or so. NE-E 8-11 KT. && .PRELIMINARY POINT TEMPS/POPS... DDC 75 63 78 61 / 60 70 20 10 GCK 74 61 77 57 / 60 70 20 10 EHA 77 62 80 60 / 60 70 10 10 LBL 79 63 80 61 / 60 70 20 10 HYS 74 62 76 61 / 100 70 30 10 P28 80 67 81 65 / 100 80 30 10 && .DDC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH until 1 PM CDT /Noon MDT/ this afternoon FOR KSZ030-031-043>046-061>066-074>081-084>090. && $$ SYNOPSIS...Sugden SHORT TERM...Sugden LONG TERM...UMSCHEID AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS WICHITA KS
328 AM CDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 TODAY & TONIGHT: AS ALL OBVIOUSLY KNOW...FLOODING TO CONTINUE BEINGING THE HIGHLIGHT OF FOR PERIODS AS FLOOD WATCH REMAINS IN EFFECT TIL 7 AM FRIDAY. DURING THE NIGHT A POORLY-DEFINED STATIONARY FRONT WAS DRAPED IN AN E-W MANNER GENERALLY THROUGH CNTRL OK WITH A WEAK 700-MB TROF SITUATED FROM THE UT/CO BORDER TO ~CA/AZ BORDER. WITH THE TROF SLOWLY EVOLVING INTO A WEAK LOW AS IT VENTURES E TO WRN KS RICH & DEEP MOISTURE WILL CONTINUE TO SPREAD NE ACROSS KS. WITH THE MID-LVL "KICKER" LACKING THE SFC-850MB FRONTS WILL MOVE VERY LITTLE...IF AT ALL...THEREBY PROMOTING BROAD ECHO TRAINING OVER KICT COUNTRY WHICH IN TURN WOULD EXACERBATE THE FLOODING SITUATION ACROSS THE CWA. ONLY CHANGES TO INHERITED FORECAST WERE TO SHIFT THE POP GRADIENT TO GENERALLY A N/S ORIENTATION TO BETTER ALIGN WITH THE BROAD LWR-MID DECK MOISTURE CHANNEL. ASSIGNED 80-100% TO CNTRL & SC KS THIS MORNING WITH HIGHEST POPS & ASSOCIATED TSRA SHIFTED E OVER SE KS THIS AFTERNOON AS HRRR DEPICTS. PW`S REMAIN IN 175-200% RANGE SO CONTINUED TO HIT QPFS HARD. FRI & FRI NIGHT: A FAIRLY BROAD UPR-DECK RIDGE IS FORECAST MOVE SLOWLY MOVG E TOWARD THE CNTRL ROCKIES...THE WEAK MID-LVL LOW WILL GET FORCED E TOWARD...THEN ACROSS...ERN KS. THIS WOULD THEREFORE SHIFT BULK OF +TSRA E ACROSS THE KS/MO BORDER ON FRI WITH -TSRA CONFINED FROM GENERALLY THE FLINT HILLS E FRI NGT. AS SUCH WILL CONTINUE TO SCHEDULE THE FLOOD WATCH TO END AT 7AM FRI. SAT & SAT NGT: MOST AREAS WILL EXPERIENCE AN INTERMISSION FROM TSRA. A FEW TSRA SHOULD VENTURE TOWARD THE WRN CORRIDOR SAT NGT AS WEAK LWR-DECK TROFFING BEGINS ALONG THE FRONT RANGE. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 ALL AREAS TO BE UNDER A WEAK NW FLOW REGIME FOR MOST OF THESE PERIODS. A WEAK COLD FRONT WILL VENTURE SE TOWARD & PERHAPS ACROSS KICGT COUNTRY EARLY NEXT WEEK WHICH WOULD INCREASE TSRA CHANCES FOR MUCH OF THESE PERIODS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1137 PM CDT WED AUG 7 2013 MAIN MCS STRETCHING FROM WESTERN KS INTO WESTERN OK WILL TRACK EASTWARD ACROSS CENTRAL/SOUTH CENTRAL/SOUTHEAST KS LATE TONIGHT INTO THE EARLY MORNING HOURS THURSDAY. STRONGEST ACTIVITY COULD PRODUCE SOME GUSTY WINDS/HEAVY RAIN AT HUT AND ICT FROM 08-12Z. SHOWERS/STORMS COULD REDEVELOP AND BECOME FAIRLY WIDESPREAD LATER THURSDAY AFTERNOON INTO THURSDAY NIGHT WITH SOME VSBY/CIG REDUCTIONS INTO AT LEAST THE MVFR RANGE AT TIMES. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 80 68 79 65 / 100 90 40 10 HUTCHINSON 78 65 76 63 / 100 90 40 10 NEWTON 78 66 76 63 / 100 90 50 10 ELDORADO 79 67 79 64 / 100 90 50 20 WINFIELD-KWLD 82 70 82 66 / 100 70 30 10 RUSSELL 77 63 76 62 / 100 70 40 10 GREAT BEND 77 63 75 61 / 100 80 40 10 SALINA 78 65 77 63 / 100 80 50 10 MCPHERSON 78 65 76 63 / 100 80 50 10 COFFEYVILLE 85 71 86 68 / 80 80 40 20 CHANUTE 81 69 81 66 / 80 80 60 20 IOLA 80 68 80 66 / 80 80 70 20 PARSONS-KPPF 83 70 84 67 / 80 80 50 20 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ032-033-047>053- 067>072-082-083-091>096-098>100. && $$ ES
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
254 AM CDT Thu Aug 8 2013 ...Update to short term discussion... .SYNOPSIS... ISSUED AT 1010 PM CDT WED AUG 7 2013 The 08.00Z 250 hPa showed 50 KT flow extending from KDDC increasing to around 100 KT at KAPX. @ 500 hPa, a 577-580 decameter cyclone was spinning off northwest California. Downstream, an open wave was moving across the central Rockies. A huge 550 decameter cyclone was noted across west central Ontario. @ 700 hPa, easterly upslope flow was observed at KDDC. This upslope flow also continued at 850 hPa and down to the sfc. The precipitable water for KDDC was 1.41" (above the 75th percentile for a Gaussian distribution). At the sfc, a stationary front was located across the KS/OK state border. KDDC WSR-88D was busy indicating an MCS to the west. && .SHORT TERM...(Today and tonight) ISSUED AT 254 AM CDT THU AUG 8 2013 ...Pretty busy shift this morning. Most of the attention was paid to overnight convection and then some to this afternoon... This morning: A fairly significant rain event occurred through the overnight period. Rainfall reports have been pretty sparse given the fact that it is O`Dark Thirty. We should get more reports by dawn. A few reports have trickled in with 3.00" in Hugoton, 1.50" by Richfield, and a few flash flooding reports. Here at the KDDC airport as of 07:24Z, we have had a measly half of an inch. Southern Ford county and other areas probably saw 2" to 4" via estimation from radar. Anyway, given the initial event, canceled the Flood Watch and issued a Flash Flood Watch instead. So, why all the precip? Well, an upper level wave, 850 hPa theta-e advection, pwats around the 75th percentile, sfc-700 hPa upslope flow, and isentropic lift was the impetus for MCS formation. For the rest of the early morning, will taper precipitation probability percentage points west to east via radar trends and HRRR guidance. FWIW, the 00Z NAM performed poorly for the event. Will carry the FF.A (Flash Flood Watch) until 18Z. Today/tonight: We should see some break in the precipitation from the morning activity to possible additional activity later this afternoon as temporary subsidence builds in the wake of the departing MCS. Forecast skew-t/log-p`s show pwats still in the 1.50-1.70" range this afternoon. A moist upslope flow will also continue from the sfc up through 800 hPa. The main synoptic wave mentioned in the synopsis will have translated over western Kansas by afternoon, and this will provide some upper level support for additional lift. The atmosphere will become unstable again with 1000-2000 J/kg of SBCAPE. Low to mid level lapse rates are fairly moist adiabatic, so the CAPE profile is fairly skinny. Bulk shear vectors are SW/40 KT. All and all, tomorrow does not look that impressive for severe weather (supercells etc). What does look more promising is another MCS. There is significant questions in regarding convective initiation/placement. The ECMWF and both cores of the WRF look reasonable. The atmosphere could be "worked over" from the morning convection, so a lack of additional activity is also possible. Anywho, will carry chance precipitation probabilities this afternoon and ramp them up to likely region wide by tonight. Maximums will be in the 70sF and minimums in the 60sF. .LONG TERM...(Thursday night through Wednesday) ISSUED AT 228 PM CDT WED AUG 7 2013 Medium range models indicate little change to the overall large scale pattern through early next week with a low amplitude upper level ridge remaining in place across the central and southern Rockies. Early in the period, a significant upper level shortwave is expected to eject out of the southern Rockies east-northeast into the western high plains bringing the possibility for more showers and thunderstorms to portions of western Kansas Thursday night into early Friday. As the shortwave approaches, a prevailing surface low across the Texas panhandle and an attendant frontal boundary extending generally east across northern Oklahoma, will provide increased lift within a low level convergence zone generally along and just north of the Kansas border. Although the flow aloft will remain fairly weak, a few showers and isolated thunderstorms will be possible across much of southwest and central Kansas with enough instability present as surface dewpoints remain well up into the 60s(F). A brief break in precip chances is expected generally Friday night into Saturday as surface high pressure migrates southward into western Kansas pushing a frontal boundary just to our south further down into west Texas and southern Oklahoma. Chances for thunderstorms will return to portions of western Kansas Sunday as the weak upper level ridge begins to build across the Rockies returning a westerly flow aloft to the western high plains. In response, the frontal boundary well to our south is expected to return northward providing the focus for thunderstorm development across the region into early next week. Below normal temperatures are likely Friday as the aforementioned surface low in the Texas panhandle pushes off to the east setting up a more north to northeasterly low level flow across western Kansas. Slightly cooler air will filter down into western Kansas with H85 temperatures ranging from the mid teens(C) across central Kansas to near 20C in far southwest Kansas. Along with increased clouds, look for highs only up into the 70s(F) to possibly near 80F across much of central and southwest Kansas Friday afternoon. A gradual warming trend is then expected through the weekend as the upper level ridging in the intermountain west begins to amplify. Highs back up into the 80s(F) to near 90F are likely over the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) ISSUED AT 1212 AM CDT THU AUG 8 2013 MVFR cigs expected through the overnight with VFR cigs after 15Z or so. NE-E 8-11 KT. && .PRELIMINARY POINT TEMPS/POPS... DDC 75 63 78 61 / 60 70 20 10 GCK 74 61 77 57 / 60 70 20 10 EHA 77 62 80 60 / 60 70 10 10 LBL 79 63 80 61 / 60 70 20 10 HYS 74 62 76 61 / 100 70 30 10 P28 80 67 81 65 / 100 80 30 10 && .DDC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH until 1 PM CDT /Noon MDT/ this afternoon FOR KSZ030-031-043>046-061>066-074>081-084>090. && $$ SYNOPSIS...Sugden SHORT TERM...Sugden LONG TERM...JJOHNSON AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1114 PM MDT WED AUG 7 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 221 PM MDT WED AUG 7 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES ZONAL FLOW STILL IN PLACE ACROSS THE CONUS WITH STRONG CLOSED LOW OVER CENTRAL CANADA. AN EMBEDDED H5/H7 LOW IN IN PLACE UPSTREAM OF THE CWA OVER THE FOUR CORNER REGION. LARGE SCALE FORCING AND MID LEVEL MOISTURE CONTINUE TO ADVECT INTO THE CWA FROM THE SOUTHWEST AHEAD OF THE FOUR CORNERS TROUGH. RAP ANALYSIS STILL SHOWS 500-1500 J/KG OF MUCAPE IN PLACE...SO THUNDERSTORMS ARE CERTAINLY POSSIBLE. AT THIS POINT OVERALL THREAT FOR SEVERE THUNDERSTORMS SEEMS LOW. MODELS CONTINUE TO PAIN BULLS EYE OF 0.50+ QPF...FAVORING SOUTHERN LOCATIONS. AT THE SAME TIME...NAM/SREF HAVE TRENDED FURTHER NORTH WHICH DOES SEEM TO HAVE SUPPORT LOOKING AT LATEST RADAR TRENDS. I ADJUSTED POPS ACCORDINGLY. RAP INDICATES PWATS IN EXCESS OF 1.3"...AND WHILE LOWER THAN THE LAST FEW DAYS IS STILL CLIMATOLOGICALLY HIGH. BASED ON RADAR/SATELLITE TRENDS...AND THE NATURE OF THIS PATTERN...I AM CURRENTLY EXPECTING SEVERAL PERIODS OF SHOWERS/THUNDERSTORMS ROTATING ACROSS OUR CWA THROUGH TONIGHT...BEFORE THE MAIN TROUGH MOVES ACROSS THE REGION. AS THIS OCCURS WE MIGHT SEE OUR BEST CHANCE FOR HEAVY PRECIP ACROSS MOST OF THE CWA. THERE IS STILL SOME INDICATION THIS COULD OCCUR LATER IN THE DAY THURSDAY...HOWEVER CONSENSUS SUPPORTS A MORNING TROUGH PASSAGE AND DECREASING CHANCES THROUGH MIDDAY THURSDAY. REGARDING WATCH...CONSIDERING THE LIKELIHOOD THAT PRECIPITATION WILL REMAIN LIGHT TO MODERATE ACROSS MOST OF THE AREA WITH HIGHEST TOTALS SPREAD OUT OVER 6-12HR PERIOD...I AM STARTING TO QUESTION THE POTENTIAL FOR FLASH FLOODING. LATEST 6HR FLASH FLOOD GUIDANCE IS GENERALLY IN THE 2-3 INCH RANGE OVER THE WATCH AREA AND UNLESS WE CAN GET A STRONG THUNDERSTORM EMBEDDED WITHIN THE LARGER AREA OF LIGHT-MODERATE RAIN IM NOT SURE WE WILL SEE THESE RATES. WE MAY BE ABLE TO CANCEL THE WATCH LATER THIS EVENING...BUT I WOULD RATHER WAIT AND SEE HOW CONVECTION EVOLVES. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 221 PM MDT WED AUG 7 2013 THURSDAY EVENING THE UPPER LEVEL SHORT WAVE TROUGH WILL MOVE EAST OF THE AREA. WITH THE NOSE OF THE LOW LEVEL JET OVER THE EASTERN PART OF THE AREA AS WELL...AND A WEAK RIGHT ENTRANCE REGION OF THE 300MB JET OVER THE AREA...THERE MAY BE SOME LINGERING PRECIP. ACTIVITY AHEAD OF THE EXITING TROUGH. MEANWHILE BEHIND THE TROUGH DRIER AIR WILL BE MOVING IN WHICH WILL CAUSE PRECIP. CHANCES TO DECLINE FROM WEST TO EAST. HOWEVER WITH COOLER AIR MOVING IN THERE WILL BE SOME INSTABILITY LINGERING BEHIND THE TROUGH. WITH SOME MUCH SMALLER UPPER LEVEL DISTURBANCES MOVING THROUGH BEHIND THE MAIN FEATURE...ISOLATED STORMS CANNOT BE RULED OUT DURING THE EVENING AND INTO THE OVERNIGHT HOURS. FRIDAY ANOTHER UPPER LEVEL SHORT WAVE TROUGH WILL DEVELOP OVER FAR EASTERN COLORADO IN THE LATE AFTERNOON. AT THE SURFACE A TROUGH WILL BE OVER THE WESTERN BORDER OF THE TRI-STATE AREA BENEATH THE SHORT WAVE. WITH SURFACE CONVERGENCE AND UPPER LEVEL LIFT...ANTICIPATE SOME STORMS DEVELOPING ALONG THE SURFACE TROUGH DURING THE MID AFTERNOON INTO THE EARLY EVENING. MEAN STORM MOTIONS WILL BE VERY SLOW...WITH MOTIONS TURNING FROM THE WEST TO THE NORTH. THESE MOTIONS WILL KEEP THE STORMS CONFINED TO THE SURFACE TROUGH. BY THE LATE EVENING ANY STORMS THAT DEVELOPED WILL DISSIPATE AS THE ENVIRONMENT STABILIZES. THE MAIN THREAT WITH ANY STORMS THAT DEVELOP WILL BE HEAVY RAINFALL. SATURDAY THROUGH WEDNESDAY THE UPPER LEVEL RIDGE OVER THE SOUTHWEST CONUS WILL SLOWLY BUILD NORTHWARD...WITH THE TRI-STATE AREA REMAINING UNDER THE PERIPHERY OF THE RIDGE. AS A RESULT MULTIPLE UPPER LEVEL SHORT WAVE TROUGHS WILL MOVE OVER THE AREA THROUGH THE PERIOD. THE STRONGER TROUGHS WILL MOVE OVER THE AREA AFTER THE WEEKEND. MEANWHILE A FRONT WILL WAFFLE BACK AND FORTH OVER THE AREA DURING THIS PERIOD WHICH WILL CAUSE TEMPERATURES TO VARY SOMEWHAT. AT THIS TIME RANGE DIFFICULT TO KNOW WHERE THE FRONT WILL BE SO WILL KEEP THE CONSENSUS TEMP. FORECAST OF NEAR NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1110 PM MDT WED AUG 7 2013 AS TEMPERATURES COOL TO SATURATION...LOW CEILINGS SHOULD BECOME PREDOMINANT BY SUNRISE...WITH OCCASIONAL REDUCTIONS IN VISIBILITY IN LIGHT RAIN AND/OR FOG. FLIGHT CATEGORIES WILL BE SLOW TO IMPROVE THURSDAY WITH MOIST CONDITIONS AND LIGHT SOUTHERLY WINDS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR KSZ027>029-041- 042. CO...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR COZ092. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JTL AVIATION...024
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1133 PM CDT Wed Aug 7 2013 .UPDATE... Issued at 940 PM CDT WED AUG 7 2013 Increase pops based on the new runs the HRRR model. The HRRR did a good job last night forecasting the outflow boundary propagating northeast off the MCS and causing numerous showers and thunderstorms to develop farther north along and and south of the boundary, from the southern counties to north of I-70. The greatest potential for likely to categorical pops will remain across the southern counties with a sharp gradient in pops from east central KS, along I-70 into north central KS along the NE border. Northeast KS may not see any rainfall until Thursday afternoon. Also increased pops for the southern CWA into Thursday morning as the brunt of MCS will move across southeast KS and the northern fringe may cause heavy rainfall across the extreme southeast counties. && .SHORT TERM...(THIS EVENING THROUGH Thursday) ISSUED AT 331 PM CDT WED AUG 7 2013 Extensive cloud cover has kept high temperatures today mainly in upper 70s to lower to middle 80s across the area. Diffuse boundary has been draped E to W across the area but is difficult to find because of very weak surface wind fields. Isolated brief showers have popped up and quickly died where greater instability exists, near and south of boundary. Wouldn`t expect this activity to be more than isolated late this afternoon and evening with weak convergence and no organized upper support. Nearly all short range (and medium range) models now consistent in keeping weak upper disturbance south of area, so most of northeast quarter of KS dry overnight. Only outlier is now the 09Z SREF, and have disregarded that in coming up with POP and QPF forecast. Thus, have considerably decreased previous forecast POPs for tonight with highest values across far south and west forecast area and least in far northeast KS. Latest model runs also increase influence of surface high pressure nosing into area from the upper midwest/western Great Lakes. This will also inhibit chances for thunderstorms on Thursday as well, with best chances still south and west and lowest chances northeast. With this guidance, would not expect any significantly heavy precipitation and very low chances for any new flooding, or increase on current river flooding through Thursday. .LONG TERM...(Thursday NIGHT THROUGH Wednesday) ISSUED AT 331 PM CDT WED AUG 7 2013 Thursday evening through Saturday... On Thursday evening, widespread moderate to at times heavy rainfall is expected to spread northeast through the cwa. Weak mid level flow will allow a slow northeast progression of the main shortwave trof and therefore prolonged duration of scattered showers and thunderstorms in the area. Strong southerly fetch of moisture combined with warm air overriding the h85 front is expected to center heaviest rainfall along and just north of the axis. Latest model runs of the GFS and NAM are beginning to focus higher qpf values just south and east of the cwa. This will need to be monitored for consistency in consideration of flood potential. Areas especially south of Interstate 70 who have persistently seen rainfall each evening and/or have had flooding issues need to be most aware to flash flooding potential from Thursday evening into Friday. Based on the uncertainty mentioned will defer issuing flood watch until next issuance. Where heavy precip does develop forecast soundings depict completely saturated columns during this period with pwat values extending above 2 inches. Showers and thunderstorms should gradually exit the area through the day on Friday before surface high builds southward Friday evening. Cloud cover gradually clearing out with exiting showers should hold temps to the upper 70s and low 80s on Friday. Light northeast winds hover around 10 mph. Ridge flattens out Saturday with mid level zonal flow keeping most of the rain showers out of the area. Cool air advection filtering southward on the backside of the cool front will keep highs quite pleasant for August in the low 80s. Slightly drier air accompanying the wave should alleviate dewpoints a bit into the low 60s. The 12Z NAM and ECMWF try to redevelop scattered convection over east central areas during the late aftn in vcnty of the frontal boundary. With this being the only run will keep forecast dry for now and monitor model trends in upcoming forecasts. Saturday evening through Wednesday... On Sunday an upper trof begins to deepen across the Ontario region. A series of embedded waves will continue to bring off and on showers and thunderstorm chances. GFS has pretty consistent between each run by carrying southward a sfc trough and complex of showers and thunderstorms southeast Sunday evening into Monday. Frontal boundary accompanying the trough becomes nearly stationary over central Kansas with a similar pattern for precip chances through Wednesday. Confidence is not high after Monday as the 12Z ECMWF has been inconsistent with the frontal boundary positioning well south of the cwa and therefore keeping much of the period dry. Temperatures while progged to be slightly warmer will largely depend on rainfall and cloud cover. For now will keep highs in the low to mid 80s with lows in the 60s. && .AVIATION...(For the 06Z TAFs through 06Z Thursday Night) Issued at 1129 PM CDT WED AUG 7 2013 The complex of storms across southwest KS may reach the TAF sites late this morning according to some models. I may place VCTS from 16Z through 19Z. A much stronger upper disturbance will bring a better chance for thunderstorms at the TAF sites after 3Z Friday and I may insert a VCTS group in the TAFS for later Tonight. Expect VFR conditions outside of possible Thunderstorms. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Gargan SHORT TERM...PHILLIPS LONG TERM...BOWEN AVIATION...Gargan
AREA FORECAST DISCUSSION
NWS JACKSON KY
413 AM EDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE COLD FRONT THAT HAS REMAINED NEARLY STATIONARY JUST NORTH OF THE OHIO RIVER VALLEY YESTERDAY WILL FINALLY BEGIN ITS PUSH SEWARD ACROSS KY DURING THE DAY TODAY...REACHING THE SE PORTION OF THE STATE BY EVENING. AS WAS THE CASE WITH THIS SYSTEM YESTERDAY...HIGH HUMIDITY VALUES IN ADDITION TO THE ISENTROPIC LIFT PROVIDED BY THIS FRONT WILL WORK TO SPAWN CONVECTION...ESPECIALLY WITH THE ADDITION OF DAYTIME HEATING AND GREATER INSTABILITY. EXPECT A LARGE AREA OF SHOWERS AND POTENTIAL THUNDERSTORMS TO DEVELOP JUST AHEAD OF THE FRONT AND ENCOMPASS MUCH OF THE CWA...THEN SHIFT SLIGHTLY EASTWARD AS THE FRONT NEARS INTO THE REGION. CURRENT RADAR TRENDS ARE ALREADY SUPPORTING THIS IDEA...WITH SCATTERED SHOWERS CONTINUING TO DEVELOP ACROSS THE WESTERN HALF OF THE CWA. WHILE MODELS REMAIN FAIRLY CONSISTENT THAT PRECIP WILL OVERSPREAD THE AREA...THERE IS STILL SOME SUBTLE DIFFERENCES IN RESOLUTION AS TO WHERE THE HEAVIEST PRECIP WILL OCCUR. BASED ON THE LATEST HRRR AND NAM12...EXPECT BEST PRECIP DEVELOPMENT ACROSS THE SOUTHERN EXTENT OF THE CWA IN THE MORNING...SPREADING TO THE NORTH BY THE AFTERNOON. BY 0Z FRIDAY...FRONT WILL ONCE AGAIN BECOME STATIONARY...THIS TIME PARKING ITSELF ACROSS EASTERN KY. WITH SUCH HUMID AND UNSTABLE CONDITIONS IN PLACE...WILL CONTINUE WITH ONGOING FORECAST OF SOME SCT CONVECTIVE POSSIBILITY THROUGHOUT THE NIGHT...SINCE ANY STORM ONGOING IN THE AFTERNOON WILL TAKE SOME TIME TO DIE OFF...AND THERE IS ALWAYS THE POSSIBILITY THAT ANY LITTLE AREA OF LIFT COULD INITIATE SOME MORE SHOWERS. LUCKILY...WITH LOSS OF DAYTIME HEATING...BEST INSTABILITY AND THUNDERSTORM POTENTIAL WILL LESSON. HIGH DEWPOINTS WILL ALSO LEAD TO LITTLE VARIATION FOR TEMPERATURES...WITH LOWS ONLY DROPPING TO AROUND 70. FRIDAY WILL BRING ABOUT SIMILAR CONDITIONS TO TODAY...WITH THE STATIONARY FRONT LIFTING SLIGHTLY JUST TO THE NORTH OF THE CWA. AN UPPER LEVEL SHORTWAVE MOVING THROUGH EASTERN KY BY FRIDAY MORNING WILL BE ENOUGH TO KICK START SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE REGION. WHILE PRECIPITABLE WATER VALUES WERE NEARING 2 INCHES FOR TODAY/S FORECAST...ACCORDING TO LATEST NAM12 SOUNDINGS...FRIDAY/S SOUNDINGS ARE POINTING AT WELL OVER 2.10 INCHES IN MANY LOCATIONS WITHIN A 6 HOUR PERIOD. IF A STRONG SHOWER OR THUNDERSTORM DEVELOPS AND MOVES OVER A PARTICULAR SITE...FLASH FLOODING IS A DEFINITE THREAT...ESPECIALLY IF THEY ARE IMPACTED BY TODAY/S CONVECTIVE ACTIVITY. MOST OF THIS MOISTURE IS EXPECTED TO FALL DURING THE MORNING AND EARLY AFTERNOON HOURS...WITH PWAT VALUES SLIGHTLY LESS...IN THE 1.5-2.0 RANGE IN THE AFTERNOON HOURS. TEMPERATURES SHOULD REMAIN FAIRLY SIMILAR TO TODAY WITH LITTLE CHANGE IN THE OVERALL PATTERN. SINCE A LOT OF THE EXPECTED PRECIP IS BASED ON MESOSCALE DEVELOPMENT...DISCUSSED THE IDEA OF ISSUING A FFA FOR THE AREA...BUT ULTIMATELY DECIDED TO HOLD OFF FOR RIGHT NOW. FUTURE SHIFTS MAY DECIDE TO PULL THE TRIGGER BASED ON HOW WIDESPREAD AND HEAVY THE DAY/S CONVECTIVE DEVELOPMENT PROVES TO BE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT ON THE GENERAL UPPER AIR PATTERN THAT WILL GUIDE OUR WEATHER THROUGH THE EXTENDED PORTION OF THE FORECAST. THIS CONSISTS PRIMARILY OF A DEEP AND PERSISTENT TROUGH OVER SOUTHEAST CANADA AND A FLAT RIDGE OVER THE SOUTHERN TIER OF THIS NATION. BETWEEN THESE...FAIRLY FAST MID LEVEL FLOW WILL CARRY SHORT WAVE ENERGY FROM THE WEST COAST THROUGH THE OHIO VALLEY BEFORE EXITING OFF THE EASTERN SEABOARD. THIS FLOW WILL BE FAIRLY ZONAL OVER KENTUCKY THROUGH THE WEEKEND BEFORE A WESTERN RESURGENCE IN THE CANADIAN TROUGH INDUCES A DIP SOUTH THROUGH THE GREAT LAKES AND INTO THE NORTHERN OHIO VALLEY. THIS WILL RESULT IN MORE OF A NORTHWEST FLOW PATTERN FOLLOWING THE WEEKEND INTO THE MIDDLE OF NEXT WEEK. THE GFS AND ECMWF DIFFER MOST DURING THE LATTER PORTION OF THE FORECAST AS THE ECMWF RUNS A BIT FASTER AND FURTHER EAST WITH THE CANADIAN LOW/S REDEVELOPMENT INTO THE DAY MONDAY. THE GFS TAKES THE CORE OF THIS LOW FURTHER SOUTH ON TUESDAY...DIPPING INTO THE STATES...BEFORE LIFTING IT JUST NORTH OF EAST. DURING THIS TIME OF LARGER GFS/ECMWF DISCREPANCY THE GEM SEEMS TO BE SIDING WITH THE ECMWF SO THE MORE EXTREME GFS SOLUTION FOR MONDAY TO WEDNESDAY WILL BE DISCOUNTED. ALSO...ITS RUN TO RUN CONSISTENCY HAS BEEN POOR...NOT THAT THE ECMWF HAS BEEN ALL THAT MUCH BETTER/JUST NOT SO OUT THERE AT TIMES...FOR THE LATTER PART OF THE EXTENDED. ACCORDINGLY...WILL FAVOR THE BLENDED RESULTS THROUGH THE WEEKEND BEFORE LEANING MORE TOWARD THE ECMWF INTO THE MIDDLE OF NEXT WEEK. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF OUR WET PATTERN THAT IS PRIMED FOR BOUTS OF HEAVY RAIN. THE SFC BOUNDARY WILL REMAIN STALLED THROUGH THE REGION INTO THE WEEKEND WITH EACH SFC WAVE RIPPLING PAST...POTENTIALLY SENDING THE BOUNDARY AND ITS HEAVIEST RAIN OUR WAY. HIGH PW AIR AND DAYTIME INSTABILITY WILL PROVIDE THE FUEL FOR THIS MCS ACTIVITY. THEREFORE...POPS WILL REMAIN HIGH INTO THE WEEKEND WITH MAX TEMPERATURES CAPPED BELOW NORMAL DUE TO CLOUDS AND CONVECTION. FOR THE START OF NEXT WEEK...IT LOOKS LIKE THE AMPLIFYING TROUGH ALOFT WILL BE ENOUGH TO EVENTUALLY PUSH THE FRONT SOUTH OF THE AREA AND ALLOW DRIER AIR TO FLOW INTO THE STATE. THE FAVORED 12Z ECMWF DOES TAKE THE DEEPER MOISTURE SOUTH LATER MONDAY WHILE THE GFS WAITS UNTIL A SECONDARY FRONT PUSHES THROUGH ON TUESDAY NIGHT. WILL CONTINUE SMALL POPS INTO TUESDAY FOR THIS TRANSITION...BUT NOT AS HIGH AS THE GFS WOULD IMPLY. HOPEFULLY WEDNESDAY WILL TURN OUT AS PLEASANT AS THE MODEL CONSENSUS SUGGESTS WITH A RETURN OF DECENT SUNSHINE AND MUCH DRIER AIR. WE WILL SEE... BUT AT LEAST THIS SEEMS TO BE A BUILDING AND STABILIZING ASPECT OF THE FORECAST FROM THE LATEST MEDIUM RANGE MODELS. THE CR GRID LOAD CAME IN NICELY FOR THIS UNSETTLED FORECAST THROUGH THE WEEKEND. DID TWEAK POPS TO ADD MORE OF A DIURNAL CYCLE AND ALSO TOWARD THE LATEST SPECIFICS FROM THE 12Z ECMWF FOR MONDAY ON INTO WEDNESDAY. ONLY MADE MINOR TERRAIN BASED ADJUSTMENTS FOR TEMPS THROUGHOUT THE BULK OF THIS EXTENDED PERIOD GIVEN THE HIGH MOISTURE CONTENT...AT LEAST THROUGH TUESDAY MORNING. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 137 AM EDT THU AUG 8 2013 SIMILAR SITUATION TO LAST NIGHT...WITH SCT PRECIP ACROSS THE AREA AND CLOUD HEIGHTS VARYING FROM POCKETS OF MVFR TO MID LEVEL VFR ACROSS THE AREA. WHERE THE TAF SITES WILL CONTINUE TO FALL WITHIN THIS PATTERN WILL BE THE MAIN CONCERN OVERNIGHT. FOR THE MOST PART...EXPECT VFR CONDITIONS AT TAF SITES UNLESS INFLUENCED BY THE PASSAGE OF A RAIN SHOWER. BEST CONVECTIVE CHANCES WILL DEVELOP IN THE MORNING...WITH POSSIBLE MVFR CIGS EXPECTED WITH ONSET. THE EXACT SET UP OF THESE STORMS IN RELATION TO HOW THEY WILL AFFECT THE TAF SITES IS STILL SOMEWHAT UNCERTAIN. IF A HEAVY SHOWER OR THUNDERSTORM DOES IMPACT A SITE DURING THE DAY...VIS COULD TEMPORARILY BE REDUCED BELOW MVFR. SHOWERS AND THUNDERSTORMS WILL DIE DOWN TOMORROW EVENING WITH LOSS OF DAYTIME HEATING...THOUGH SOME SCT CONVECTION IS STILL POSSIBLE THROUGH THE REMAINDER OF THE TAF PERIOD. MUCH LIKE TONIGHT...EXPECT OVERALL CONDITIONS TO IMPROVE TO VFR WITH SOME POSSIBLE ADJUSTMENTS IF A SHOWER OR LINGERING THUNDERSTORM PASSES OVER TAF SITE. AS FAR AS FOG OVERNIGHT...SOME TEMPORARY BR IS BEING REPORTED AT KJKL IN CONJUNCTION WITH THE RAIN THAT JUST PASSED OVER INTERACTING WITH THE WARM HUMID CONDITIONS. OTHERWISE...WITH CLOUD COVER ACROSS MUCH OF THE REGION...ANY WIDESPREAD FOG DEVELOPMENT IS UNLIKELY...ESPECIALLY TO A DEGREE THAT IT WILL AFFECT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
137 AM EDT THU AUG 8 2013 .UPDATE... ISSUED AT 1214 AM EDT THU AUG 8 2013 UPDATED POPS TO ACCOUNT FOR POSSIBILITY OF DEVELOPMENT OUTSIDE OF MAIN SHIELD OF PRECIP CURRENTLY OVER THE NW AND CENTRAL CWA. CONVECTION IN THE CWA SEEMS TO BE FAIRLY LIGHT WITH A DIMINISHING TREND OVER THE LAST HOUR...BUT EXPECT SOME LIGHT RAIN AND A POSSIBLE RUMBLE OF THUNDER TO CONTINUE OVER THE NEXT FEW HOURS FOR THE ABOVE MENTIONED AREAS. MEANWHILE...ISOLATED CONVECTION TO OUR SW WILL MOVE EASTWARD INTO THE AREA...THEN INCREASE IN COVERAGE AS WE WORK INTO TOMORROW MORNING. ALSO UPDATED ONGOING TEMPS/DEW POINTS/AND WIND FORECASTS WITH LATEST OBSERVATIONS TO MAKE SURE THEY REFLECTED THE MOST CURRENT CONDITIONS. UPDATE ISSUED AT 1102 PM EDT WED AUG 7 2013 RAIN IS STARTING TO PUSH INTO AREAS FROM MOUNT STERLING TO MOUNT VERNON...BUT IS BEGINNING TO FALL APART. HRRR SEEMS TO HAVE A GOOD HANDLE ON THIS TREND WITH THE CURRENT COMPLEX COLLAPSING WITH VERY LITTLE FOR THE REST OF THE NIGHT. UPDATE HAS BEEN SENT. UPDATE ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED ACROSS EASTERN KENTUCKY. HAVE SEEN SOME NEW DEVELOPMENT OUT WEST OF LEXINGTON. THIS ACTIVITY COULD MAKE IT INTO THE I-75 CORRIDOR OVER THE NEXT FEW HOURS...BUT STILL SOME QUESTION IF THIS WILL MAKE IT INTO AREAS FURTHER EAST. FOR NOW...GOING TO DOWNPLAY POPS FOR THE REST OF THE NIGHT GIVEN THE CURRENT LACK OF ORGANIZED ACTIVITY. LATEST HRRR HAS ALMOST NO SHOWER OR THUNDERSTORM ACTIVITY ACROSS THE AREA UNTIL 11Z. THUS...THE DOWNWARD TREND IN POPS SEEMS REASONABLE. CAN`T IGNORE THOSE HIGH PW`S NEAR 2 LATER TONIGHT...SO IT WON`T TAKE MUCH TO GET SOME LOCALLY HEAVY RAIN...BUT STILL PLANNING TO PUSH ANY MENTION UNTIL AFTER 12Z. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 315 PM EDT WED AUG 7 2013 AFTER INITIAL ROUND OF SHOWERS AND A FEW THUNDERSTORMS THIS MORNING CONVECTION HAS REMAINED LIMITED THIS AFTERNOON...WITH MOSTLY SCATTERED SHOWERS...AND VERY LITTLE THUNDER. CLOUD COVER HAS INHIBITED DESTABILIZATION AND WITH LOSS OF DAYTIME HEATING EXPECT CONVECTION TO DIMINISH EVEN FURTHER THIS EVENING. HOWEVER THIS WILL BE TEMPORARY...WITH A MID LEVEL SHORT WAVE TROUGH MOVING EAST TONIGHT...AND A LOW LEVEL JET AT 8H IMPINGING ON EASTERN KY AFTER 06Z. AT THE SAME TIME EXPECT A SURFACE WAVE OF LOW PRESSURE TO TREK ALONG THE SURFACE FRONT TO THE NORTHWEST OF THE FORECAST AREA THURSDAY MORNING. THERE IS GOOD MODEL AGREEMENT WITH INCREASING THREAT OF SHOWERS AND THUNDERSTORMS LATE TONIGHT INTO THE DAY ON THURSDAY. DETERMINISTIC MODELS ALONG WITH THE SERF ARE POINTING TOWARDS PRECIPITABLE WATER IN EXCESS OF 2 INCHES BY THURSDAY MORNING. PRECIPITABLE WATER SHOULD APPROACH OR EXCEED THE 99TH PERCENTILE. BASED ON THIS WILL ADD THE THREAT OF HEAVY RAIN TO THE THURSDAY FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. WITH ALL THIS IN MIND WILL INCREASE RAIN PROBABILITIES LATE TONIGHT TO LIKELY IN THE WEST...THEN LIKELY ACROSS THE ENTIRE AREA ON THURSDAY...BEFORE DECREASING CHANCES AGAIN LATE IN THE DAY THURSDAY. WITH THE FRONT STALLING SOMEWHERE IN THE OH VALLEY...THE TREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THURSDAY NIGHT. THERE IS LESS MODEL AGREEMENT ON THE TIMING OF THE NEXT SHORT WAVE WHICH WOULD TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS BUT FOR FOR NOW WILL CONTINUE THE PREVIOUS FORECAST IDEA OF INCREASING CHANCES AGAIN LATE THURSDAY NIGHT. HIGH DEWPOINTS WILL KEEP MINIMUM TEMPERATURES AROUND 70 TONIGHT AND AGAIN THURSDAY NIGHT. WITH RAIN AND CLOUD IN THE FORECAST ON THURSDAY...WILL GO WITH HIGHS IN THE LOWER 80S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 358 PM EDT WED AUG 7 2013 UNSETTLED WEATHER WILL CONTINUE INTO THE LONG TERM PERIOD. THE PERIOD SHOULD BEGIN WITH A NEARLY STATIONARY BOUNDARY ACROSS THE OH VALLEY EXTENDING SOUTHWEST INTO THE OH VALLEY FROM LOW PRESSURE OVER QUEBEC. THERE MAY BE A WAVE OR SERIES OF SFC WAVES ALONG THE BOUNDARY TO OUR WEST AT THAT POINT AS DISTURBANCES MOVING INTO THE REGION. AT THE START OF THE PERIOD UPPER LEVEL RIDGING IS EXPECTED TO EXTEND ACROSS THE SOUTHERN STATES AND NORTH INTO THE ROCKIES. AN UPPER LEVEL LOW SHOULD BE ROTATING TO THE NORTH OF THE GREAT LAKES FROM ONTARIO. THERE WILL PROBABLY BE SOME SHORTWAVES ROTATING TOWARD THE LOWER OH VALLEY FROM THE PLAINS...BUT THERE ARE MODEL DIFFERENCES IN TIMING. THE MODELS GRADUALLY SAG THE BOUNDARY SOUTH OF THE OH RIVER AND EVENTUALLY INTO THE JKL CWA AND STRING IT OUT MORE WEST TO EAST AS THE UPPER LOW WORKS TOWARD THE MARITIMES OVER THE WEEKEND. FROM EARLY TO THE MIDDLE PART OF NEXT WEEK...THE TROUGH SHOULD DEEPEN AGAIN OVER EASTERN CANADA AND THE NORTHEAST AS ANOTHER UPPER LEVEL LOW ROTATES FROM THE HUDSON BAY REGION NORTH OF THE GREAT LAKES AND TOWARD THE MARITIMES. THE MODEL CONSENSUS FROM EARLY TO THE MIDDLE PART OF NEXT WEEK IS FOR MORE AMPLIFIED PATTERN WITH THE BOUNDARY PUSHING SOUTH OF THE AREA...BUT WEST NORTHWEST UPPER FLOW SHOULD REMAIN. DISTURBANCES IN THIS FLOW WILL STILL KEEP A THREAT OF CONVECTION IN THE PICTURE FOR AT LEAST MON AND TUE...ESPECIALLY EACH AFTERNOON AND EVENING. ENOUGH DRIER AIR MAY WORK INTO THE REGION LATE IN THE PERIOD IF THE 12Z ECMWF VERIFIES FOR DRY WEATHER ON WEDNESDAY OR TUESDAY AND WEDNESDAY. HOWEVER...MODEL TO MODEL DIFFERENCES AND RUN TO RUN DIFFERENCE REMAIN AND THE EXTENDED GRID LOAD OF ISOLATED TO SCATTERED POPS WAS REASONABLE. PW WILL REMAIN VERY HIGH ABOVE THE 90TH TO 95TH PERCENTILE RANGE INTO EARLY IN THE PERIOD AHEAD OF THE BOUNDARY. THERE IS THE POTENTIAL FOR ANY CONVECTION TO HAVE DEEP WARM CLOUD DEPTH AND THEY COULD PRODUCE AT LEAST LOCALLY HEAVY RAIN. TIMING AND STRENGTH OF PASSING UPPER LEVEL SHORTWAVES WILL BE A KEY INGREDIENT AND CONFIDENCE IN THIS IS NOT HIGH AT THIS POINT. HOWEVER...WE WILL HIGHLIGHT THIS IN THE HWO. TEMPERATURES THROUGH THE PERIOD SHOULD REMAIN NEAR IF NOT A BIT BELOW NORMAL FOR DAYTIME HIGHS WITH OVERNIGHT LOWS EARLY IN THE PERIOD A BIT ABOVE NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 137 AM EDT THU AUG 8 2013 SIMILAR SITUATION TO LAST NIGHT...WITH SCT PRECIP ACROSS THE AREA AND CLOUD HEIGHTS VARYING FROM POCKETS OF MVFR TO MID LEVEL VFR ACROSS THE AREA. WHERE THE TAF SITES WILL CONTINUE TO FALL WITHIN THIS PATTERN WILL BE THE MAIN CONCERN OVERNIGHT. FOR THE MOST PART...EXPECT VFR CONDITIONS AT TAF SITES UNLESS INFLUENCED BY THE PASSAGE OF A RAIN SHOWER. BEST CONVECTIVE CHANCES WILL DEVELOP IN THE MORNING...WITH POSSIBLE MVFR CIGS EXPECTED WITH ONSET. THE EXACT SET UP OF THESE STORMS IN RELATION TO HOW THEY WILL AFFECT THE TAF SITES IS STILL SOMEWHAT UNCERTAIN. IF A HEAVY SHOWER OR THUNDERSTORM DOES IMPACT A SITE DURING THE DAY...VIS COULD TEMPORARILY BE REDUCED BELOW MVFR. SHOWERS AND THUNDERSTORMS WILL DIE DOWN TOMORROW EVENING WITH LOSS OF DAYTIME HEATING...THOUGH SOME SCT CONVECTION IS STILL POSSIBLE THROUGH THE REMAINDER OF THE TAF PERIOD. MUCH LIKE TONIGHT...EXPECT OVERALL CONDITIONS TO IMPROVE TO VFR WITH SOME POSSIBLE ADJUSTMENTS IF A SHOWER OR LINGERING THUNDERSTORM PASSES OVER TAF SITE. AS FAR AS FOG OVERNIGHT...SOME TEMPORARY BR IS BEING REPORTED AT KJKL IN CONJUNCTION WITH THE RAIN THAT JUST PASSED OVER INTERACTING WITH THE WARM HUMID CONDITIONS. OTHERWISE...WITH CLOUD COVER ACROSS MUCH OF THE REGION...ANY WIDESPREAD FOG DEVELOPMENT IS UNLIKELY...ESPECIALLY TO A DEGREE THAT IT WILL AFFECT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...SBH LONG TERM...JP AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
1216 AM EDT THU AUG 8 2013 .UPDATE... ISSUED AT 1214 AM EDT THU AUG 8 2013 UPDATED POPS TO ACCOUNT FOR POSSIBILITY OF DEVELOPMENT OUTSIDE OF MAIN SHIELD OF PRECIP CURRENTLY OVER THE NW AND CENTRAL CWA. CONVECTION IN THE CWA SEEMS TO BE FAIRLY LIGHT WITH A DIMINISHING TREND OVER THE LAST HOUR...BUT EXPECT SOME LIGHT RAIN AND A POSSIBLE RUMBLE OF THUNDER TO CONTINUE OVER THE NEXT FEW HOURS FOR THE ABOVE MENTIONED AREAS. MEANWHILE...ISOLATED CONVECTION TO OUR SW WILL MOVE EASTWARD INTO THE AREA...THEN INCREASE IN COVERAGE AS WE WORK INTO TOMORROW MORNING. ALSO UPDATED ONGOING TEMPS/DEW POINTS/AND WIND FORECASTS WITH LATEST OBSERVATIONS TO MAKE SURE THEY REFLECTED THE MOST CURRENT CONDITIONS. UPDATE ISSUED AT 1102 PM EDT WED AUG 7 2013 RAIN IS STARTING TO PUSH INTO AREAS FROM MOUNT STERLING TO MOUNT VERNON...BUT IS BEGINNING TO FALL APART. HRRR SEEMS TO HAVE A GOOD HANDLE ON THIS TREND WITH THE CURRENT COMPLEX COLLAPSING WITH VERY LITTLE FOR THE REST OF THE NIGHT. UPDATE HAS BEEN SENT. UPDATE ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWER AND THUNDERSTORM ACTIVITY HAS DIMINISHED ACROSS EASTERN KENTUCKY. HAVE SEEN SOME NEW DEVELOPMENT OUT WEST OF LEXINGTON. THIS ACTIVITY COULD MAKE IT INTO THE I-75 CORRIDOR OVER THE NEXT FEW HOURS...BUT STILL SOME QUESTION IF THIS WILL MAKE IT INTO AREAS FURTHER EAST. FOR NOW...GOING TO DOWNPLAY POPS FOR THE REST OF THE NIGHT GIVEN THE CURRENT LACK OF ORGANIZED ACTIVITY. LATEST HRRR HAS ALMOST NO SHOWER OR THUNDERSTORM ACTIVITY ACROSS THE AREA UNTIL 11Z. THUS...THE DOWNWARD TREND IN POPS SEEMS REASONABLE. CAN`T IGNORE THOSE HIGH PW`S NEAR 2 LATER TONIGHT...SO IT WON`T TAKE MUCH TO GET SOME LOCALLY HEAVY RAIN...BUT STILL PLANNING TO PUSH ANY MENTION UNTIL AFTER 12Z. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 315 PM EDT WED AUG 7 2013 AFTER INITIAL ROUND OF SHOWERS AND A FEW THUNDERSTORMS THIS MORNING CONVECTION HAS REMAINED LIMITED THIS AFTERNOON...WITH MOSTLY SCATTERED SHOWERS...AND VERY LITTLE THUNDER. CLOUD COVER HAS INHIBITED DESTABILIZATION AND WITH LOSS OF DAYTIME HEATING EXPECT CONVECTION TO DIMINISH EVEN FURTHER THIS EVENING. HOWEVER THIS WILL BE TEMPORARY...WITH A MID LEVEL SHORT WAVE TROUGH MOVING EAST TONIGHT...AND A LOW LEVEL JET AT 8H IMPINGING ON EASTERN KY AFTER 06Z. AT THE SAME TIME EXPECT A SURFACE WAVE OF LOW PRESSURE TO TREK ALONG THE SURFACE FRONT TO THE NORTHWEST OF THE FORECAST AREA THURSDAY MORNING. THERE IS GOOD MODEL AGREEMENT WITH INCREASING THREAT OF SHOWERS AND THUNDERSTORMS LATE TONIGHT INTO THE DAY ON THURSDAY. DETERMINISTIC MODELS ALONG WITH THE SERF ARE POINTING TOWARDS PRECIPITABLE WATER IN EXCESS OF 2 INCHES BY THURSDAY MORNING. PRECIPITABLE WATER SHOULD APPROACH OR EXCEED THE 99TH PERCENTILE. BASED ON THIS WILL ADD THE THREAT OF HEAVY RAIN TO THE THURSDAY FORECAST AND THE HAZARDOUS WEATHER OUTLOOK. WITH ALL THIS IN MIND WILL INCREASE RAIN PROBABILITIES LATE TONIGHT TO LIKELY IN THE WEST...THEN LIKELY ACROSS THE ENTIRE AREA ON THURSDAY...BEFORE DECREASING CHANCES AGAIN LATE IN THE DAY THURSDAY. WITH THE FRONT STALLING SOMEWHERE IN THE OH VALLEY...THE TREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THURSDAY NIGHT. THERE IS LESS MODEL AGREEMENT ON THE TIMING OF THE NEXT SHORT WAVE WHICH WOULD TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS BUT FOR FOR NOW WILL CONTINUE THE PREVIOUS FORECAST IDEA OF INCREASING CHANCES AGAIN LATE THURSDAY NIGHT. HIGH DEWPOINTS WILL KEEP MINIMUM TEMPERATURES AROUND 70 TONIGHT AND AGAIN THURSDAY NIGHT. WITH RAIN AND CLOUD IN THE FORECAST ON THURSDAY...WILL GO WITH HIGHS IN THE LOWER 80S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 358 PM EDT WED AUG 7 2013 UNSETTLED WEATHER WILL CONTINUE INTO THE LONG TERM PERIOD. THE PERIOD SHOULD BEGIN WITH A NEARLY STATIONARY BOUNDARY ACROSS THE OH VALLEY EXTENDING SOUTHWEST INTO THE OH VALLEY FROM LOW PRESSURE OVER QUEBEC. THERE MAY BE A WAVE OR SERIES OF SFC WAVES ALONG THE BOUNDARY TO OUR WEST AT THAT POINT AS DISTURBANCES MOVING INTO THE REGION. AT THE START OF THE PERIOD UPPER LEVEL RIDGING IS EXPECTED TO EXTEND ACROSS THE SOUTHERN STATES AND NORTH INTO THE ROCKIES. AN UPPER LEVEL LOW SHOULD BE ROTATING TO THE NORTH OF THE GREAT LAKES FROM ONTARIO. THERE WILL PROBABLY BE SOME SHORTWAVES ROTATING TOWARD THE LOWER OH VALLEY FROM THE PLAINS...BUT THERE ARE MODEL DIFFERENCES IN TIMING. THE MODELS GRADUALLY SAG THE BOUNDARY SOUTH OF THE OH RIVER AND EVENTUALLY INTO THE JKL CWA AND STRING IT OUT MORE WEST TO EAST AS THE UPPER LOW WORKS TOWARD THE MARITIMES OVER THE WEEKEND. FROM EARLY TO THE MIDDLE PART OF NEXT WEEK...THE TROUGH SHOULD DEEPEN AGAIN OVER EASTERN CANADA AND THE NORTHEAST AS ANOTHER UPPER LEVEL LOW ROTATES FROM THE HUDSON BAY REGION NORTH OF THE GREAT LAKES AND TOWARD THE MARITIMES. THE MODEL CONSENSUS FROM EARLY TO THE MIDDLE PART OF NEXT WEEK IS FOR MORE AMPLIFIED PATTERN WITH THE BOUNDARY PUSHING SOUTH OF THE AREA...BUT WEST NORTHWEST UPPER FLOW SHOULD REMAIN. DISTURBANCES IN THIS FLOW WILL STILL KEEP A THREAT OF CONVECTION IN THE PICTURE FOR AT LEAST MON AND TUE...ESPECIALLY EACH AFTERNOON AND EVENING. ENOUGH DRIER AIR MAY WORK INTO THE REGION LATE IN THE PERIOD IF THE 12Z ECMWF VERIFIES FOR DRY WEATHER ON WEDNESDAY OR TUESDAY AND WEDNESDAY. HOWEVER...MODEL TO MODEL DIFFERENCES AND RUN TO RUN DIFFERENCE REMAIN AND THE EXTENDED GRID LOAD OF ISOLATED TO SCATTERED POPS WAS REASONABLE. PW WILL REMAIN VERY HIGH ABOVE THE 90TH TO 95TH PERCENTILE RANGE INTO EARLY IN THE PERIOD AHEAD OF THE BOUNDARY. THERE IS THE POTENTIAL FOR ANY CONVECTION TO HAVE DEEP WARM CLOUD DEPTH AND THEY COULD PRODUCE AT LEAST LOCALLY HEAVY RAIN. TIMING AND STRENGTH OF PASSING UPPER LEVEL SHORTWAVES WILL BE A KEY INGREDIENT AND CONFIDENCE IN THIS IS NOT HIGH AT THIS POINT. HOWEVER...WE WILL HIGHLIGHT THIS IN THE HWO. TEMPERATURES THROUGH THE PERIOD SHOULD REMAIN NEAR IF NOT A BIT BELOW NORMAL FOR DAYTIME HIGHS WITH OVERNIGHT LOWS EARLY IN THE PERIOD A BIT ABOVE NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 746 PM EDT WED AUG 7 2013 SHOWERS HAVE DIMINISHED ACROSS EASTERN KENTUCKY AND TAFS WILL ALL START OFF VFR. WITH LOTS OF LOW LEVEL MOISTURE PRESENT...SOME STRATUS SHOULD DEVELOP OVERNIGHT...MUCH LIKE LAST NIGHT. IN ADDITION SOME RAIN COULD START TO INVADE THE AREA TOWARDS DAYBREAK. WITH CLOUD COVER FAIRLY HIGH TONIGHT...NO FOG EXPECTED AT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...SBH LONG TERM...JP AVIATION...KAS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
544 AM EDT THU AUG 8 2013 .SYNOPSIS... A WARM FRONT WILL LIFT INTO THE AREA TODAY AND STALL ACROSS THE HIGHER TERRAIN THROUGH FRIDAY. A COLD FRONT MOVES THROUGH ON FRIDAY AND FRIDAY EVENING. HIGH PRESSURE BUILDS IN FOR THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK. LOW PRESSURE WILL APPROACH FROM THE WEST IN THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...SCT WAA SHRA ARE PUSHING ACROSS THE AREA ATTM...ROUGHLY ALIGNED WITH NH/ME BORDER. A FEW OF THE STRONGER CELLS HAVE HAD SOME IN CLOUD LIGHTNING WITH THEM...BUT MOSTLY JUST SOME BRIEF -SHRA. THIS WAVE OF PCPN WILL CONTINUE EWD THRU THE MORNING HOURS. FARTHER W...BROKEN LINE OF SHRA/TSTMS FROM THE ST. LAWRENCE VALLEY SWWD TOWARDS KBUF CONTINUES TO TRACK EWD. COMPLEX OF TSTMS NEAR THE EASTERN TOWNSHIPS WILL LIKELY EFFECT NRN COOS AND THE WRN ME MTNS. SATELLITE TRENDS SUGGEST WEAKENING IS OCCURRING...WITH CLOUD TOPS WARMING AND LIGHTNING DECREASING. ACROSS WRN NY...COMPLEX OF TSTMS THERE IS MAINTAINING STRENGTH WITH CLOUD TOPS COOLING AND LIGHTNING INCREASING. THIS GROWING COMPLEX MAY BE THE REASON FOR THE RELATIVE LACK OF CONVECTIVE ACTIVITY ACROSS THE ADIRONDACKS AND VT. HAVE TRENDED POP BASED ON THE LATEST HRRR AND RADAR. PREVIOUS DISCUSSION...FNT WILL APPROACH THE AREA TODAY AND BRING AT LEAST A COUPLE ROUNDS OF SHRA/TSTMS. EARLY TODAY AN INCREASINGLY MOISTENING ATMOSPHERE WILL RESULT IN CLOUDS SPREADING EWD AND THICKENING. ADDITIONALLY...WAA WILL SUPPORT WIDELY SCT SHRA ACROSS THE AREA THRU SUNRISE. A LINE OF SHRA AND TSTMS ALONG THE FNT WILL ALSO PUSH EWD INTO WRN ZONES IN THE NEXT SEVERAL HOURS. SO IN THE NEAR TERM HAVE TRIED TO TIME POP WITH THIS TREND...WHICH THE HRRR SEEM TO HAVE A DECENT HANDLE ON. A BLEND OF THAT AND THE LOCAL WRF WAS USED AS THE BASE FOR THE FIRST HALF OF THE DAY. AS THIS EARLY CONVECTION WEAKENS AND MOVES E...EXPECT THAT A FEW PARTIAL BREAKS IN THE OVERCAST WILL DEVELOP THIS AFTERNOON. IT IS THESE POCKETS OF SFC HEATING THAT WILL BECOME THE FOCUS FOR THE AFTERNOON FORECAST. LAPSE RATES ARE MARGINAL AT BEST...BUT DEW POINTS INCREASING TO THE UPR 60S TO NEAR 70 WILL SUPPORT MODERATE INSTABILITY FOR LOCATIONS THAT CAN GLIMPSE SOME SUNSHINE. AMPLE MID LVL WLY FLOW WILL SUPPORT ENOUGH EFFECTIVE SHEAR FOR SOME STORM ORGANIZATION. AT LEAST TRANSIENT SUPERCELL STRUCTURE WILL LEAD TO STRONGER CONVECTION CONTAINING GUSTY WINDS AND SMALL HAIL. GREATER THREAT IS PROBABLY WIND...AS DEEP...MOIST AIR MASS WILL BE MORE SUPPORTIVE OF MELTING HAIL. PCPN LOADING IN THE COLUMN AND STEEP LLVL LAPSE RATES WHERE SUN PEEKS OUT IS MORE THAN ENOUGH FOR SOME GUSTY DOWNDRAFTS. THIS HAS BEEN ADDED TO THE GRIDS...MAINLY ACROSS NH AND EXTREME WRN ME. NOT EXPECTING ANYTHING WIDESPREAD...BUT AN ISOLD SEVERE WX REPORT IS ENTIRELY PSBL TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... ATTENTION THEN TURNS TO FNT STALLING ALONG OR S OF THE SRN CWFA BORDER. TO THE S WILL BE AN EXTREMELY MOIST AIR MASS...WITH PWAT VALUES INCREASING TO NEAR 2 INCHES. FOR THE GYX AREA THIS REPRESENTATION AOA +2 SD ABOVE NORMAL. HEAVY RNFL IS LIKELY WITH ANY CONVECTION...WITH EXTREME RNFL RATES AT TIMES. IN ADDITION...BOUNDARY WILL PROVIDE A FOCUS FOR TRAINING CELLS. ATTM UNCERTAINTY STILL EXISTS ON LOCATION FNT STALLS...BUT AS CONFIDENCE GROWS SOME SORT OF FLOOD/FLASH FLOOD HEADLINE MAY BE NECESSARY FOR A PORTION OF THE AREA. MUCH OF THAT MAY ALSO DEPEND ON WHERE HEAVY RAIN FALLS TODAY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A COLD FRONT WILL SLOWLY PUSH THROUGH THE REGION FRIDAY EVENING...SWEEPING THE HIGHER SURFACE DEW POINTS AND PRECIPITABLE WATER VALUES OFF THE COAST. MODELS STILL HAVE SOME ISSUES WITH THE TIMING OF THE PASSAGE OF THE FRONT. HAVE USED A BLEND BETWEEN THE VERY PROGRESSIVE...FAST MOVING FRONTAL PASSAGE WITH THE GFS/EURO SOLUTION...AND THE SLOWER FROPA WITH THE NAM/GGEM SOLUTION. SURFACE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SATURDAY. HOWEVER...STILL PLENTY OF COLD AIR AND CYCLONIC FLOW ALOFT ALLOWING FOR A FEW DIURNALLY DRIVEN SPRINKLES OR SCATTERED SHOWERS...MAINLY ACROSS THE HIGHER TERRAIN OF THE MOUNTAINS. THIS AIR MASS WILL BE NOTICEABLY COOLER AND DRIER. EXPECT CHILLY NIGHTS WITH PATCHY FOG AS THIS SYSTEM BUILDS OVERHEAD. MODELS IN GOOD AGREEMENT ADVANCING THE AREA OF HIGH PRESSURE OVER OUR REGION SUNDAY INTO MONDAY. BY TUESDAY...LOW PRESSURE WILL BEGIN TO EXIT THE GREAT LAKES REGION...BRINGING MORE SCATTERED SHOWERS TO OUR REGION DURING THE MIDWEEK PERIOD. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... SHORT TERM...CONDS EXPECTED TO DETERIORATE INTO GENERALLY MVFR CIGS AND VSBYS AS FNT APPROACHES TODAY. SOME LOCAL IFR IS PSBL IN NEAR COAST STRATUS OR SHRA/TSTM. IFR CONDS COULD BECOME MORE WIDESPREAD NEAR THE COAST AS FNT STALL TONIGHT AND FRI AND DEEPER MOISTURE WORKS NWD. LONG TERM...SHOWERS AND A FEW EMBEDDED THUNDERSTORMS EARLY FRIDAY EVENING MAY BRING MVFR TO IFR CONDITIONS. EXPECT IMPROVING CONDITIONS BEHIND A COLD FRONT FRIDAY NIGHT WITH VFR CONDITIONS CONTINUING INTO EARLY NEXT WEEK. && .MARINE... SHORT TERM...SUSTAINED ONSHORE FLOW WILL DEVELOP TODAY AHEAD OF AN APPROACHING FNT. THIS WILL GRADUALLY BUILD SEAS TO NEAR 5 FT BY LATE THIS EVENING...DESPITE WINDS REMAINING BLO 25 KTS. USED A BLEND OF THE NAM BASED SWAN WITH THE WNA4 IN THE FIRST PERIOD...AS GFS IS USUALLY TOO AGGRESSIVE WITH WINDS AND SEAS IN SLY FLOW. LONG TERM...SOUTHERLY FLOW WILL END FRIDAY EVENING. HOWEVER SEAS STILL EXPECTED TO BE RELATIVELY HIGH IN THE 4 TO 6 FOOT RANGE. THEREFORE....SMALL CRAFT ADVISORIES MAY STILL BE NEEDED THROUGH MUCH OF FRIDAY NIGHT AND POSSIBLY INTO EARLY SATURDAY MORNING. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ LEGRO/JC
AREA FORECAST DISCUSSION
NWS GRAY ME
318 AM EDT THU AUG 8 2013 .SYNOPSIS... A WARM FRONT WILL LIFT INTO THE AREA TODAY AND STALL ACROSS THE HIGHER TERRAIN THROUGH FRIDAY. A COLD FRONT MOVES THROUGH ON FRIDAY AND FRIDAY EVENING. HIGH PRESSURE BUILDS IN FOR THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK. LOW PRESSURE WILL APPROACH FROM THE WEST IN THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... FNT WILL APPROACH THE AREA TODAY AND BRING AT LEAST A COUPLE ROUNDS OF SHRA/TSTMS. EARLY TODAY AN INCREASINGLY MOISTENING ATMOSPHERE WILL RESULT IN CLOUDS SPREADING EWD AND THICKENING. ADDITIONALLY...WAA WILL SUPPORT WIDELY SCT SHRA ACROSS THE AREA THRU SUNRISE. A LINE OF SHRA AND TSTMS ALONG THE FNT WILL ALSO PUSH EWD INTO WRN ZONES IN THE NEXT SEVERAL HOURS. SO IN THE NEAR TERM HAVE TRIED TO TIME POP WITH THIS TREND...WHICH THE HRRR SEEM TO HAVE A DECENT HANDLE ON. A BLEND OF THAT AND THE LOCAL WRF WAS USED AS THE BASE FOR THE FIRST HALF OF THE DAY. AS THIS EARLY CONVECTION WEAKENS AND MOVES E...EXPECT THAT A FEW PARTIAL BREAKS IN THE OVERCAST WILL DEVELOP THIS AFTERNOON. IT IS THESE POCKETS OF SFC HEATING THAT WILL BECOME THE FOCUS FOR THE AFTERNOON FORECAST. LAPSE RATES ARE MARGINAL AT BEST...BUT DEW POINTS INCREASING TO THE UPR 60S TO NEAR 70 WILL SUPPORT MODERATE INSTABILITY FOR LOCATIONS THAT CAN GLIMPSE SOME SUNSHINE. AMPLE MID LVL WLY FLOW WILL SUPPORT ENOUGH EFFECTIVE SHEAR FOR SOME STORM ORGANIZATION. AT LEAST TRANSIENT SUPERCELL STRUCTURE WILL LEAD TO STRONGER CONVECTION CONTAINING GUSTY WINDS AND SMALL HAIL. GREATER THREAT IS PROBABLY WIND...AS DEEP...MOIST AIR MASS WILL BE MORE SUPPORTIVE OF MELTING HAIL. PCPN LOADING IN THE COLUMN AND STEEP LLVL LAPSE RATES WHERE SUN PEEKS OUT IS MORE THAN ENOUGH FOR SOME GUSTY DOWNDRAFTS. THIS HAS BEEN ADDED TO THE GRIDS...MAINLY ACROSS NH AND EXTREME WRN ME. NOT EXPECTING ANYTHING WIDESPREAD...BUT AN ISOLD SEVERE WX REPORT IS ENTIRELY PSBL TODAY. && .SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/... ATTENTION THEN TURNS TO FNT STALLING ALONG OR S OF THE SRN CWFA BORDER. TO THE S WILL BE AN EXTREMELY MOIST AIR MASS...WITH PWAT VALUES INCREASING TO NEAR 2 INCHES. FOR THE GYX AREA THIS REPRESENTATION AOA +2 SD ABOVE NORMAL. HEAVY RNFL IS LIKELY WITH ANY CONVECTION...WITH EXTREME RNFL RATES AT TIMES. IN ADDITION...BOUNDARY WILL PROVIDE A FOCUS FOR TRAINING CELLS. ATTM UNCERTAINTY STILL EXISTS ON LOCATION FNT STALLS...BUT AS CONFIDENCE GROWS SOME SORT OF FLOOD/FLASH FLOOD HEADLINE MAY BE NECESSARY FOR A PORTION OF THE AREA. MUCH OF THAT MAY ALSO DEPEND ON WHERE HEAVY RAIN FALLS TODAY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A COLD FRONT WILL SLOWLY PUSH THROUGH THE REGION FRIDAY EVENING...SWEEPING THE HIGHER SURFACE DEW POINTS AND PRECIPITABLE WATER VALUES OFF THE COAST. MODELS STILL HAVE SOME ISSUES WITH THE TIMING OF THE PASSAGE OF THE FRONT. HAVE USED A BLEND BETWEEN THE VERY PROGRESSIVE...FAST MOVING FRONTAL PASSAGE WITH THE GFS/EURO SOLUTION...AND THE SLOWER FROPA WITH THE NAM/GGEM SOLUTION. SURFACE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SATURDAY. HOWEVER...STILL PLENTY OF COLD AIR AND CYCLONIC FLOW ALOFT ALLOWING FOR A FEW DIURNALLY DRIVEN SPRINKLES OR SCATTERED SHOWERS...MAINLY ACROSS THE HIGHER TERRAIN OF THE MOUNTAINS. THIS AIR MASS WILL BE NOTICEABLY COOLER AND DRIER. EXPECT CHILLY NIGHTS WITH PATCHY FOG AS THIS SYSTEM BUILDS OVERHEAD. MODELS IN GOOD AGREEMENT ADVANCING THE AREA OF HIGH PRESSURE OVER OUR REGION SUNDAY INTO MONDAY. BY TUESDAY...LOW PRESSURE WILL BEGIN TO EXIT THE GREAT LAKES REGION...BRINGING MORE SCATTERED SHOWERS TO OUR REGION DURING THE MIDWEEK PERIOD. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SHORT TERM...CONDS EXPECTED TO DETERIORATE INTO GENERALLY MVFR CIGS AND VSBYS AS FNT APPROACHES TODAY. SOME LOCAL IFR IS PSBL IN NEAR COAST STRATUS OR SHRA/TSTM. IFR CONDS COULD BECOME MORE WIDESPREAD NEAR THE COAST AS FNT STALL TONIGHT AND FRI AND DEEPER MOISTURE WORKS NWD. LONG TERM...SHOWERS AND A FEW EMBEDDED THUNDERSTORMS EARLY FRIDAY EVENING MAY BRING MVFR TO IFR CONDITIONS. EXPECT IMPROVING CONDITIONS BEHIND A COLD FRONT FRIDAY NIGHT WITH VFR CONDITIONS CONTINUING INTO EARLY NEXT WEEK. && .MARINE... SHORT TERM...SUSTAINED ONSHORE FLOW WILL DEVELOP TODAY AHEAD OF AN APPROACHING FNT. THIS WILL GRADUALLY BUILD SEAS TO NEAR 5 FT BY LATE THIS EVENING...DESPITE WINDS REMAINING BLO 25 KTS. USED A BLEND OF THE NAM BASED SWAN WITH THE WNA4 IN THE FIRST PERIOD...AS GFS IS USUALLY TOO AGGRESSIVE WITH WINDS AND SEAS IN SLY FLOW. LONG TERM...SOUTHERLY FLOW WILL END FRIDAY EVENING. HOWEVER SEAS STILL EXPECTED TO BE RELATIVELY HIGH IN THE 4 TO 6 FOOT RANGE. THEREFORE....SMALL CRAFT ADVISORIES MAY STILL BE NEEDED THROUGH MUCH OF FRIDAY NIGHT AND POSSIBLY INTO EARLY SATURDAY MORNING. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ LEGRO/JC
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1257 AM EDT THU AUG 8 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE SOUTHEAST OF THE AREA OVERNIGHT. A COLD FRONT WILL APPROACH FROM QUEBEC THURSDAY NIGHT...THEN CROSS THE REGION FRIDAY WHILE LOW PRESSURE MOVES NORTH ALONG THE FRONT. && .NEAR TERM /THROUGH TODAY/... 1250 AM UPDATE...CLOUDS WILL CONTINUE TO INCREASE OVERNIGHT AND THE CLOUD COVER WILL KEEP TEMPERATURES FROM FALLING ALL THAT MUCH. THEREFORE...HAVE RAISED OVERNIGHT LOWS A FEW DEGREES. OTHERWISE THE FORECAST STILL LOOKS ON TRACK. THE LATEST HRRR AND RUC INDICATE THAT SHOWERS WILL START TO MAKE IT INTO THE WESTERN ZONES AFTER 06Z AND THE CURRENT GRIDDED DATABASE SEEMS TO HAVE A GOOD HANDLE ON THIS. PREVIOUS DISCUSSION HIGH PRESSURE WILL MOVE EAST OVERNIGHT. CLEAR SKIES AND LIGHT WINDS WILL ALLOW TEMPERATURES TO FALL INTO THE LOW 50S WITH A FEW READINGS IN THE UPPER 40S POSSIBLE TOWARDS THE EASTERN BORDER OF THE STATE. CLOUDS INCREASE THURSDAY AS AN OCCLUDED FRONT APPROACHES. THIS FRONT IS ASSOCIATED WITH A CUT OFF UPPER LOW IN WESTERN ONTARIO. A SHORTWAVE ROTATING AROUND THE LOW WILL WEAKEN AS IT MOVES INTO QUEBEC. AS A RESULT...THE FRONT WILL ALSO WEAKEN AS IT MOVES INTO THE FORECAST AREA THURSDAY MORNING. BESIDES INCREASING CLOUDS...SOME SHOWER ACTIVITY IS EXPECTED WITH A TENTH OR TWO OF AN INCH OF RAIN POSSIBLE. THE SURFACE FRONT IS NOT EXPECTED TO CROSS THE STATE THURSDAY...BUT MORE HUMID AIR WILL BE INTRODUCED IN WESTERN PORTIONS OF THE FORECAST AREA THURSDAY AFTERNOON. THIS HUMID AIR AND SOME PERIODS OF AFTERNOON SUNSHINE IS EXPECTED TO DESTABILIZE THE ATMOSPHERE AND ALLOW SOME THUNDERSTORMS TO DEVELOP...MOSTLY FOR PISCATAQUIS COUNTY AND FAR SOUTHWESTERN PENOBSCOT COUNTY. ELSEWHERE...A COMBINATION OF CLOUD COVER AND MARINE INFLUENCES SHOULD PREVENT MUCH DAYTIME HEATING AND INSTABILITY. HIGHS WILL ONLY REACH THE UPPER 60S TO LOW 70S. && .SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/... A COLD FRONT WILL APPROACH THURSDAY NIGHT WITH A CHANCE OF SHOWERS ACROSS THE FORECAST AREA IN ADVANCE OF THE FRONT. THE COLD FRONT THEN CROSSES THE REGION FRIDAY THROUGH FRIDAY NIGHT WHILE AN AREA OF LOW PRESSURE MOVES NORTH ALONG THE FRONT. AN AREA OF RAIN WILL CROSS THE REGION FRIDAY THROUGH EARLY FRIDAY NIGHT...WITH THE SLIGHT CHANCE OF A THUNDERSTORM FRIDAY AFTERNOON. THE PRECIPITATION WILL THEN TAPER TO SHOWERS IN THE WAKE OF THE FRONT LATER FRIDAY NIGHT. THE COLD FRONT WILL MOVE EAST OF THE REGION EARLY SATURDAY...WHILE AN UPPER LOW TRACKS NORTH OF MAINE SATURDAY AFTERNOON. COULD HAVE AN ISOLATED SHOWER DOWNEAST EARLY SATURDAY. OTHERWISE...EXPECT PARTLY/MOSTLY SUNNY SKIES DOWNEAST SATURDAY. A CHANCE OF SHOWERS COULD EXIST ACROSS NORTHERN AREAS INTO THE EARLY AFTERNOON SATURDAY WITH THE UPPER LOW. OTHERWISE...EXPECT PARTLY/MOSTLY CLOUDY SKIES ACROSS NORTHERN AREAS DURING THE MORNING WITH DECREASING CLOUDS DURING THE AFTERNOON. HIGH PRESSURE THEN BUILDS ACROSS THE REGION SATURDAY NIGHT. TEMPERATURES WILL BE AT BELOW NORMAL LEVELS FRIDAY...WITH SLIGHTLY BELOW NORMAL LEVEL TEMPERATURES SATURDAY. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... SUNDAY WILL FEATURE MAINLY SUNNY SKIES WITH SEASONAL TEMPERATURES TO ROUND OUT THE WEEKEND ALONG WITH COMFORTABLY LOW LEVELS OF HUMIDITY. EXPECT MAINLY CLEAR AND COOL CONDITIONS SUNDAY NIGHT UNDER HIGH PRESSURE. CLOUDS BEGIN TO INCREASE MONDAY WITH THE APPROACH OF THE NEXT SYSTEM. THIS SYSTEM WILL BRING A CHANCE OF SHOWERS ARRIVING BY LATE DAY MONDAY AND LASTING INTO TUESDAY. CONDITIONS WILL CLEAR OUT ONCE AGAIN FOR THE MIDDLE OF NEXT WEEK. AT THIS POINT NO MAJOR HOT SPELLS ARE ON THE HORIZON WITH THE OVERALL PATTERN FAVORING AVERAGE TO BELOW AVERAGE TEMPERATURES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR THROUGH TONIGHT. MVFR CEILINGS ARE EXPECTED TO DEVELOP THURSDAY MORNING IN SHOWERS. SHORT TERM: MVFR/IFR...WITH OCCASIONAL LIFR...CONDITIONS ARE EXPECTED THURSDAY NIGHT INTO EARLY FRIDAY NIGHT. VFR/MVFR CONDITIONS ARE EXPECTED LATER FRIDAY NIGHT. OCCASIONAL MVFR CONDITIONS ARE POSSIBLE ACROSS NORTHERN AREAS EARLY SATURDAY. OTHERWISE...VFR CONDITIONS ARE EXPECTED ACROSS THE REGION SATURDAY THROUGH SATURDAY NIGHT. EXPECT VFR SUNDAY INTO MONDAY WITH MVFR/IFR POSSIBLE BY TUESDAY. && .MARINE... NEAR TERM: WINDS WILL INCREASE THURSDAY WITH GUSTS UP TO 15 KTS FROM THE SOUTH. SEAS WILL ALSO INCREASE TOWARDS 3 TO 4 FEET BY LATER THURSDAY. SHORT TERM: SMALL CRAFT ADVISORY LEVEL SEAS ARE POSSIBLE THURSDAY NIGHT INTO EARLY SATURDAY. VISIBILITIES COULD BE REDUCED IN RAIN AND FOG THURSDAY NIGHT INTO FRIDAY NIGHT...WITH A LINGERING SHOWER POSSIBLE EARLY SATURDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...DUDA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
525 AM EDT THU AUG 8 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 518 AM EDT THU AUG 8 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP MID LEVEL LOW OVER NRN ONTARIO JUST E OF THE MANITOBA/ONTARIO BORDER. FOR THIS TIME OF YEAR...THE LOW IS UNUSUALLY DEEP WITH 500MB HEIGHTS 2.5 STANDARD DEVIATIONS BELOW THE LONG TERM AVG. THE UPPER LAKES ARE UNDER THE SRN PORTION OF ITS RATHER EXPANSIVE CIRCULATION. IN THE WAKE OF THE SHORTWAVES THAT PASSED ACROSS THE UPPER LAKES YESTERDAY...A DRY AIR MASS HAS PUSHED INTO UPPER MI. COMBINED WITH CLEAR SKIES AND LIGHT/CALM WIND...TEMPS HAVE ONCE AGAIN DIPPED AS LOW AS THE UPPER 30S IN SOME OF THE TRADITIONAL COLD SPOTS IN THE INTERIOR (DOE LAKE AND SPINCICH LAKE IN PARTICULAR). JUST TO THE W...A SHORTWAVE THAT WAS MUCH MORE WELL DEFINED YESTERDAY AFTN HAS WEAKENED/SHEARED E INTO MN...AND IT IS SPREADING A BAND OF MID CLOUDS ACROSS NRN MN AND WRN LAKE SUPERIOR. AFTER DIMINISHING...A BAND OF SHRA HAS REDEVELOPED ACROSS NRN MN IN ASSOCIATION WITH THE SHORTWAVE. TO THE NW OVER MANITOBA...A SHORTWAVE SPOKE IS EVIDENT ROTATING AROUND THE DEEP MIDLEVEL LOW OVER NRN ONTARIO. BOTH OF THESE SHORTWAVES WILL HAVE SOME IMPACT ON THE WEATHER HERE TODAY/TONIGHT. FIRST UP...THE WEAKENING SHORTWAVE OVER MN WILL PASS ACROSS THE AREA THIS MORNING. SEVERAL OF THE HIGH RES MODELS INCLUDING NAM AND HIGH RES WRF-ARW/WRF-NMM HAVE DONE A NICE JOB PICKING UP ON THE LOCATION OF SHRA TO THE W AND SUGGEST SHRA WILL TEND TO DISSIPATE AS THEY SHIFT E INTO WRN UPPER MI THIS MORNING. WILL GENERALLY FOLLOW THIS IDEA AND SPREAD ISOLD -SHRA INTO PORTIONS OF WRN UPPER MI THIS MORNING. DURING THE AFTN...NEXT SHORTWAVE CURRENTLY ROTATING THRU SRN MANITOBA SHOULD PROVIDE FORCING FOR ISOLD TO PERHAPS SCT AFTN CONVECTION WITH LAKE BREEZES PROVIDING A LOW LEVEL FOCUS AS WELL. WITH MLCAPES ONLY UP TO A COUPLE HUNDRED J/KG...THUNDER POTENTIAL IS MINIMAL...BUT PROBABLY STILL WORTHY OF INCLUDING MENTION IN FCST. ISOLD/SCT SHRA SHOULD SLOWLY SHIFT E AND SE TONIGHT AS PRONOUNCED MID LEVEL DRYING PUSHES IN FROM THE W. THIS SHOULD ALSO LEAD TO CLEARING OVER AT LEAST THE W HALF OR SO OF THE FCST AREA. LEANED SOMEWHAT TOWARD THE LOWER SIDE OF AVBL GUIDANCE FOR MINS OVER THE W WITH EXPECATION OF CLEARING AND A DRYING COLUMN. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 518 AM EDT THU AUG 8 2013 OMEGA BLOCKING FROM ALASKA TO EASTERN CANADA WILL FINALLY BEGIN TO BREAKDOWN...ALBEIT SLOWLY...BY THIS WEEKEND. BESIDE A CHANCE FOR SHOWERS AND STORMS SUNDAY AFTERNOON INTO MONDAY NIGHT...THE LONG TERM TREND WILL BE DRY AND SLIGHTLY COOLER THAN NORMAL. FRIDAY THROUGH SATURDAY NIGHT...A DEEP CLOSED MID-LEVEL LOW OVER NORTHERN ONTARIO WILL BE SENDING A SHORTWAVE TROUGH ACROSS THE CWA THURSDAY NIGHT. THE ASSOCIATED COLD FRONT IS PROGGED TO CLEAR THE CWA BY 12Z FRIDAY...WITH MUCH DRIER AIR USHERING IN BEHIND IT. SOME LOW-LEVEL MOISTURE COULD LINGER ACROSS THE EAST HALF AFTER 12Z UNDER INCREASING SUBSIDENCE BEHIND THE FRONT...SO KEPT SLIGHT CHANCE POPS FOR A FEW HOURS BEYOND 12Z FOR THE FAR EAST. THE MAIN TROUGH AXIS WILL THEN PUSH SOUTHEASTWARD ACROSS THE CWA FRIDAY AFTERNOON INTO LATE FRIDAY NIGHT. WHILE MOISTURE IS LACKING IN THE MID-LEVELS...H8 TO H7 FGEN UNDER MODEST MID-LEVEL Q-VECTOR CONVERGENCE WILL LEAD TO INCREASED CLOUDINESS BELOW H5. THE NAM IS THE ONLY MODEL TO INDICATE A SHOT AT ISOLATED SHOWERS ACROSS THE NORTH CLOSER TO THE MAIN FORCING. HAVE OPTED TO KEEP ANY PRECIP OUT OF THE FORECAST FOR NOW GIVEN VERY DRY LOW LEVELS AND THAT MOST MODELS HAVE BEEN CONSISTENT WITH ALL PRECIP REMAINING OUT OF THE CWA. MODEL TRENDS HAVE ALSO SHOWED A STRONGER PRESSURE GRADIENT...ESPECIALLY NORTH....WITH THE TROUGH PASSAGE. WEAK STABILITY SUGGESTS THAT MIXING COULD BRING GUSTY WNW OF UP TO 25 MPH TO MUCH OF THE NORTH HALF BY THE AFTERNOON. SFC HIGH PRESSURE WILL THEN BUILD INTO THE UPPER GREAT LAKES WITH MID-LEVEL SHORTWAVE RIDGING FRIDAY NIGHT THROUGH SATURDAY. GENERALLY CLEAR SKIES AND LOW PWATS OF AROUND 0.5 INCHES WILL BE CONDUCIVE FOR GOOD RADIATIONAL COOLING ACROSS MUCH OF THE CWA...PARTICULARLY THE INTERIOR WEST HALF. HAVE FOLLOWED THE PREVIOUS SHIFTS TREND OF LOWERING TEMPS. WIDESPREAD 40S ARE LIKELY FOR ALL BUT THE IMMEDIATE GREAT LAKES SHORELINES. WEAK LOW-LEVEL MOISTURE RETURN WILL BEGIN ACROSS THE WEST SATURDAY AFTERNOON AS THE SFC HIGH MOVES EAST. WITH THIS MOISTURE INCREASE...AFTERNOON CUMULUS DEVELOPMENT WILL BE COMMON. A FEW ISOLATED DIURNAL SHOWERS COULD EVEN BE POSSIBLE...BUT ONCE AGAIN...CONFIDENCE IS TOO LOW TO INTRODUCE ANY PRECIP ATTM. LOW TO MID-LEVEL CLOUDINESS WILL CONTINUE TO INCREASE WITH THE MOISTURE RETURN SATURDAY NIGHT...KEEPING TEMPS SEVERAL DEGREES WARMER THAN FRIDAY NIGHT. SUNDAY THROUGH MONDAY...ANOTHER SHORTWAVE TROUGH ON THE BACKSIDE OF THE DEEP EASTERN CANADIAN MID-LEVEL TROUGH WILL BE DIGGING SOUTHWARD ACROSS FAR WESTERN ONTARIO LATE SATURDAY NIGHT. THE ECMWF HAS SLOWED THIS TROUGH PASSAGE OVER THE LAST FEW RUNS...AND NOW LINES UP WELL WITH THE GFS IN BRINGING THE MAIN TROUGH AXIS THROUGH MONDAY EVENING. BOTH MODELS HAVE ALSO RECENTLY PICKED UP ON A WEAK LEAD SHORTWAVE TROUGH FROM PHASING BETWEEN A PORTION OF THE MAIN TROUGH AND A WEAK WAVE MOVING EASTWARD FROM WESTERN CANADA. THE TIMING OF THIS WEAK WAVE IS A LITTLE DIFFERENT BETWEEN THE TWO MODELS...WITH THE CONSENSUS BEING EARLY SUNDAY EVENING. INSTABILITY WILL BE QUITE POOR NORTH OF THE WI BORDER AND SHOULD PRECLUDE ANY STRONG THUNDERSTORM THREAT ATTM. THE TROUGH WILL CONTINUE TO SLOWLY WORK EASTWARD ACROSS THE CWA AND BRING ISOLATED TO SCATTERED SHOWERS THROUGH MONDAY AFTERNOON. MONDAY NIGHT THROUGH WEDNESDAY...BY THIS POINT...THE ECMWF AND GFS HAVE SOME DISAGREEMENT ON THE STRENGTH OF THE SHORTWAVE...AND HOW QUICK IT WILL DEPART. THE ECMWF IS MUCH QUICKER AND BRINGS GENERALLY DRY CONDITIONS THROUGH WEDNESDAY. THE GFS SWINGS A STRONG SECONDARY TROUGH ACROSS THE EASTERN CWA ON TUESDAY...BUT LIMITS SHOWERS TO ONLY THE EAST HALF. STUCK WITH OVERALL MODEL CONSENSUS FOR NOW...THROUGH MUCH OF THE PERIOD SHOULD REMAIN DRY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 144 AM EDT THU AUG 8 2013 VFR CONDITIONS WILL PERSIST THRU THE END OF THIS FCST PERIOD AT KIWD/KCMX/KSAW. LAKE BREEZES WILL MOVE INTO KSAW LATER IN THE AFTERNOON. PCPN CHANCE IS TOO LOW AT THIS POINT TO PUT INTO THE TAFS AS NEXT UPPER LEVEL DISTURBANCE PASSES THROUGH TODAY. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 518 AM EDT THU AUG 8 2013 EXPECT WINDS UNDER 20KT ACROSS LAKE SUPERIOR TODAY/TONIGHT UNDER A GENERALLY WEAK PRES GRADIENT. HOWEVER...WINDS WILL BEGIN TO INCREASE OVERNIGHT TONIGHT AHEAD OF THE NEXT COLD FRONT DROPPING SE. AN INCREASING PRESSURE GRADIENT BETWEEN HIGH PRESSURE BUILDING IN FROM SOUTH CENTRAL CANADA AND LOW PRESSURE EXITING TO THE EAST ACROSS EASTERN ONTARIO WILL CREATE W TO WNW WINDS OF 15 TO 25 KNOTS ACROSS WESTERN LAKE SUPERIOR FRIDAY MORNING...AND CENTRAL AND EASTERN LAKE SUPERIOR FRIDAY AFTERNOON. WEST WINDS UNDER 15 KNOTS WILL THEN BE THE RULE THROUGH THE WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE UPPER GREAT LAKES. ANOTHER TROUGH WILL CROSS LAKE SUPERIOR ON MONDAY AND BRING NW WINDS UNDER 15 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...KLUBER AVIATION...07 MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
330 AM CDT Thu Aug 8 2013 .SHORT TERM...(Today through Friday) Issued at 322 AM CDT THU AUG 8 2013 Another night of conceptual forecasting as none of the 00Z solutions have initialized the anticipated MCS riding along the KS/OK border, and continue to poorly handle the subtle but key features emanating out of the western trough each afternoon. The HRRR continues to perform exceptionally well (albiet slow on timing), but its short- term guidance only goes so far. In any case, 07Z surface analysis depicts a strongly convergent frontal zone across nrn OK/AR with the greatest lift once again focused about 50 miles north of this boundary. A secondary elevated boundary, roughly juxtaposed with the southern extent of dry surface air, extends NE from Wichita to Clinton to Jefferson City. Developing MCV along over SW KS will likely begin to make the turn ENE along this northern boundary. Its also possible that additional showers/storms develop along this elevated boundary over the next several hours, remaining /just/ south of the CWA border. With that said, dry northeasterly flow should keep most of the CWA quiet through daybreak. Much like the past several nights, a sub- synoptic occlusion should occur as the eastward advancing MCS overtakes the W-E stationary front. This would place the southwestern zones under the best chances for thunder by 12Z, with more stratiform rain/embedded rumbles further north. The MCV should lift slowly NE across the CWA during the day, with QPF diminishing. However, the MCV passage will mark the return of deeper warm/air moisture advection that will place us back in a preferred zone for deep moist convection tonight and Friday. As for highs today, generally went around 80 across the board. Despite better chances for sunshine over the NE CWA (at least early), CAA should yield similar readings as points further south. Convective debris/showers should limit insolation over the srn CWA through the morning, but expect some PM sun to boost them back up. For tonight, the large scale mid-level trough will begin to finally eject out of the central Rockies, establishing a surface low across OK. Deepening southwesterly flow aloft will lift the surface warm front back to near I-44. This will place the southern CWA in a precarious region of strong deep layer ascent/convergence amidst increasing moisture advection. Based only on persistence from the past 4-5 days, greatest QPF should fall in the 06-15Z time frame Friday. Given the frontogenetic forcing, upper support and boundary- relative shear profiles, have significantly bumped POPs and QPF from 06Z-18Z Friday. A flash flood watch will likely be required south of the MO river given antecedent rainfall and prospects for very heavy rainfall tonight/Friday morning. Highs Friday honestly a hedge toward some afternoon clearing, but could conceivably end up in the low-mid 70s if this doesn`t occur. Friday Night remains the biggest question mark given the large model spread in timing of the upper trough passage. Areas along/ahead of this mid level wind shift certainly remain under the gun for additional precipitation and have retained moderate POPs across all but far NW MO for that reason. .LONG TERM...(Saturday through Wednesday) Issued at 322 AM CDT THU AUG 8 2013 The upcoming weekend should remain dry as the region will fall under the influence of high pressure moving southeast through the Great Lakes. With little change in the synoptic pattern and a continuance of progressive zonal to northwesterly flow heading into into next week, it appears there will only be a short break to the rainfall in the region. By Monday, upper troughing will temporarily deepen over Manitoba and Ontario, pushing a weak shortwave into the Central Plains. Increasing warm advection ahead of this wave will induce showers and thunderstorms over a large area of the central CONUS Monday into Monday night. Have increased PoPs from late Sunday night into Tuesday morning. Latest guidance suggests a cold front will sweep southward through the region by Tuesday morning, with high pressure once again moving into the western Great Lakes providing dry conditions to the local area. As far as temperatures are concerned, warm advection and southwesterly surface flow on Sunday will push temperatures back towards seasonal normals. However, past the frontal passage on Tuesday, temperatures will likely remain below normal into the middle of next week. && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1153 PM CDT WED AUG 7 2013 VFR conditions are expected through the entire forecast. There may be a brief period around sunrise of minor fog or haze reducing visibilities to around 4 miles or so. Have kept this out of the forecast for now as winds around 5 knots from the north to northeast should keep the lowest levels mixed enough to prevent much fog formation. Otherwise, only mid to high level clouds are expected with winds becoming more easterly tomorrow but still remaining light. any chances for storms should remain to the south for the rest of the overnight. A dying area of showers or storms is possible by late morning but the dry air in the lowest levels may kill things off before getting to the terminals. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Bookbinder LONG TERM...Dux AVIATION...CDB
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
330 AM MDT THU AUG 8 2013 .DISCUSSION... SURFACE BOUNDARY ATTM IN APPROXIMATELY THE SAME LOCATION AS ONE 24 HOURS. STILL CONSIDERABLE MOISTURE LINGERING OVER THE STATE WITH SIGNIFICANTLY DRIER DEWPOINTS AS WELL AS A MUCH DRIER AIR MASS OVERALL ACROSS CENTRAL/WRN AZ. SOMEWHAT MORE ORGANIZED CLOUD COVER ROTG SE OVER THE FOUR CORNERS REGION...AND RUC13 CONTINUES TO ANALYZE A WEAK CLOSED CIRCULATION AT H5 OVER NW NM/SW CO THROUGH EARLY THIS AFTERNOON. AS THE DAY PROGRESSES...A SURFACE BOUNDARY IS FORECAST TO BECOME MORE DEFINED OVER NE NM. THEREFORE HAVE TRENDED TOWARDS THE HIGHER GUIDANCE POPS TODAY FOR THE NORTHEAST THIRD TO HALF OF THE FORECAST AREA. LATEST SPC OUTLOOK HAS SLIGHT RISK FOR SVR STORMS IN AN AREA SIMILAR TO WHAT WAS PREDICTED 24 HOURS AGO. HAVE NOT HIGHLIGHTED THAT POSSIBILITY IN THE WX GRIDS...SO LATER SHIFTS WILL NEED TO MONITOR. FRONT TO PLUNGE INTO THE EASTERN PLAINS TONIGHT BUT NOT MUCH INDICATION MODEL WISE IT WILL REACH THE RGV. FRIDAY NIGHT APPEARS AS IF THIS POSSIBILITY IS MORE LIKELY...TRENDING SHOWER AND STORM CHANCES UPWARD AND WESTWARD. HIGHS TODAY WILL BE A FEW DEGREES BELOW AVERAGE MAINLY NORTH OF INTERSTATE 40...AND MAINLY OVER THE NORTHEAST QUARTER FRIDAY. WITH POTENTIAL FORECAST FOR A MONSOON BURST...HIGHS SATURDAY ACROSS THE NORTHWEST HALF WILL BE SEVERAL DEGREES BELOW AVERAGE. ANOTHER TRANSITION FORECAST IN THE WEATHER PATTERN FOR NEXT WEEK...WITH A TREND TOWARDS WARMER AND DRIER. THE UPPER HIGH CENTER DRIFTS BACK OVER NEW MEXICO...AND FAR ENOUGH WESTWARD TO PUT THE NORTHEAST UNDER NORTHWEST FLOW AS LEAST FOR A DAY OR TWO. && .FIRE WEATHER... BACK DOOR COLD FRONT HAS MOVED INTO THE EASTERN PLAINS WITH A REINFORCEMENT OF THIS BOUNDARY EXPECTED FRIDAY NIGHT. CURRENTLY THE REMNANTS OF THE UPPER LOW FROM AZ CONTINUE TO BECOME LESS ORGANIZED OVER SOUTHERN CO. MOISTURE AND LINGERING ENERGY FROM THE LEFTOVER DISTURBANCE WILL KEEP THE BEST WETTING RAIN CHANCES OVER NORTH CENTRAL TO NORTHEASTERN NM TODAY. MODELS CONTINUE TO ADVERTISE DRIER AIR WORKING IN FROM THE WEST TODAY...AND WATER VAPOR SATELLITE IMAGERY SUPPORTS THIS. THEREFORE...EXPECT MINIMAL SHOWER/STORM COVERAGE IN THE CENTRAL TO WEST CENTRAL AND NORTHWESTERN ZONES TODAY. MINIMUM RH WILL STILL STAY AOA 20 PERCENT WITH MODERATE SURFACE BREEZES EXHIBITING A NORTHWESTERLY COMPONENT OVER MUCH OF THE FORECAST AREA. EXCELLENT RH RECOVERY IS EXPECTED OVER THE NORTHEASTERN HALF OF THE FORECAST AREA TONIGHT WITH STILL GOOD RECOVERY OF 60-80 PERCENT FARTHER WEST. CONVECTION FROM THE LATE EVENING MAY ATTEMPT TO SHOVE AN EAST WIND BEYOND THE CENTRAL MOUNTAIN CHAIN TONIGHT...BUT MODELS ARE NOT ENTHUSIASTIC ABOUT IT. AT THIS TIME NO STRONG GAP/CANYON WINDS HAVE BEEN BUILT INTO THE FORECAST THROUGH FRIDAY MORNING. MOISTURE WILL HAVE AT LEAST WORKED TOWARD THE CENTRAL MOUNTAIN CHAIN EARLY ON FRIDAY WITH THE AFOREMENTIONED EASTERLY WINDS...AND THIS MOISTURE PUSH WILL CONTINUE WESTWARD INTO THE AFTERNOON. STORMS WILL BECOME A BIT MORE WIDESPREAD ALONG THE CENTRAL MOUNTAIN CHAIN AND TOWARD THE CONTINENTAL DIVIDE AS TEMPERATURES WARM CLOSE TO AVERAGE IN MOST ZONES. LOWEST MINIMUM RH VALUES WILL BE IN THE SAN JUAN BASIN FRIDAY WHERE VALUES WILL SLIP TO 20 PERCENT OR JUST SLIGHTLY BELOW. ANY CONVECTION LATE FRIDAY EAST OF THE CENTRAL MOUNTAINS WILL AID THE PUSH OF A REINFORCING BACK DOOR FRONT. THIS WILL CONTINUE TO CARRY MOISTURE WESTWARD WHILE ALSO PRODUCING MODERATE TO STRONG GAP/CANYON WINDS NEAR CENTRAL VALLEY LOCATIONS THROUGH SATURDAY MORNING. BETTER LOW LAYER MOISTURE TRANSPORTED FROM THE EAST WILL COUPLE WITH A MID LEVEL MONSOON PLUME SQUEEZING INTO NM...AND THIS WILL SET THE STAGE FOR AN ACTIVE THUNDERSTORM DAY SATURDAY. NAM MODEL IS MOST BULLISH WITH WETTING PRECIP CHANCES AND CONSEQUENTLY BOASTS MUCH COOLER TEMPERATURES WHICH WOULD CERTAINLY MITIGATE ANY FIRE WX CONCERNS. PLENTY OF LEFTOVER MOISTURE TO RECYCLE ON SUNDAY WILL ALSO YIELD A GOOD CROP OF STORMS. INTO NEXT WEEK THE UPPER HIGH IS STILL DEPICTED AS MOVING WESTWARD OVER OR CLOSE TO NM WHILE ELONGATING SOME ON A WEST-EAST AXIS. ANOTHER BACK DOOR FRONT IN THE NORTHEAST COULD KEEP CONVECTIVE ACTIVITY GOING IN THE NORTHEAST LATE TUESDAY. 52 && .AVIATION... 06Z TAF CYCLE SH/TS ACTIVITY ASSOCIATED WITH THE UPPER LOW HAS BEEN WINDING DOWN THE PAST FEW HOURS. BACK DOOR COLD FRONT HAS SPILLED INTO THE NORTHEAST AND EAST CENTRAL PLAINS. A FEW SHOWERS WILL LINGER WITH THIS FRONT AS BEING THE FOCUS. THE FRONT SHOULD PUSH FURTHER SOUTH. HAVE IT NOW IMPACTING ROW LATER TONIGHT. SHALL SEE ON THAT. OTHERWISE...THE NORTHEAST WIND SHIFT HAS ALREADY OCCURRED AT LVS AND TCC. ANOTHER ROUND OF SH/TS WITH MTN TOP OBSCD EXPECTED ACROSS THE NORTHERN THIRD OR SO OF THE FORECAST AREA THURSDAY AFTERNOON. USING VCSH FOR A PLACEHOLDER AT FMN/SAF AND LVS. THESE SITES ARE THE MOST LIKELY TO RECEIVE SOME SORT OF EFFECT FROM A PASSING SH OR TS BASED ON STEERING FLOW CONSIDERATIONS. 50 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 85 56 89 59 / 20 10 20 40 DULCE........................... 77 47 84 50 / 40 20 30 40 CUBA............................ 79 51 82 52 / 30 10 20 40 GALLUP.......................... 82 47 85 54 / 10 10 20 20 EL MORRO........................ 79 46 82 51 / 10 10 30 30 GRANTS.......................... 82 49 85 54 / 10 10 30 30 QUEMADO......................... 82 51 85 55 / 10 10 20 30 GLENWOOD........................ 86 57 90 58 / 10 10 20 20 CHAMA........................... 73 43 78 47 / 50 20 30 50 LOS ALAMOS...................... 78 53 81 56 / 40 10 30 40 PECOS........................... 79 52 78 53 / 50 20 30 50 CERRO/QUESTA.................... 76 46 78 49 / 60 30 30 40 RED RIVER....................... 67 43 71 43 / 60 40 50 50 ANGEL FIRE...................... 71 44 75 47 / 60 30 50 50 TAOS............................ 77 47 80 51 / 50 20 20 40 MORA............................ 73 48 75 49 / 50 30 40 50 ESPANOLA........................ 85 53 86 55 / 30 20 20 40 SANTA FE........................ 81 53 82 54 / 40 20 30 40 SANTA FE AIRPORT................ 84 55 85 56 / 30 20 20 40 ALBUQUERQUE FOOTHILLS........... 85 61 87 64 / 10 10 20 40 ALBUQUERQUE HEIGHTS............. 87 64 89 66 / 10 10 20 30 ALBUQUERQUE VALLEY.............. 88 59 90 62 / 10 10 20 20 ALBUQUERQUE WEST MESA........... 87 61 90 62 / 10 10 20 40 LOS LUNAS....................... 89 62 92 63 / 10 10 20 20 RIO RANCHO...................... 87 64 89 64 / 10 10 20 40 SOCORRO......................... 92 66 93 65 / 10 10 20 20 SANDIA PARK/CEDAR CREST......... 84 57 85 59 / 20 10 30 40 TIJERAS......................... 85 60 86 62 / 20 10 30 40 MORIARTY/ESTANCIA............... 85 54 83 57 / 30 20 30 40 CLINES CORNERS.................. 82 55 80 56 / 40 20 30 40 GRAN QUIVIRA.................... 85 56 85 57 / 20 10 20 40 CARRIZOZO....................... 87 61 88 62 / 10 10 20 30 RUIDOSO......................... 79 59 79 57 / 10 20 30 40 CAPULIN......................... 74 50 76 51 / 60 30 30 30 RATON........................... 77 52 79 53 / 50 30 30 30 SPRINGER........................ 78 51 78 52 / 50 30 30 30 LAS VEGAS....................... 80 50 78 52 / 50 20 30 40 CLAYTON......................... 79 57 82 57 / 50 30 20 20 ROY............................. 80 54 81 56 / 50 30 20 30 CONCHAS......................... 85 60 86 61 / 40 20 20 40 SANTA ROSA...................... 86 62 87 63 / 30 20 20 40 TUCUMCARI....................... 90 63 89 64 / 30 20 20 40 CLOVIS.......................... 91 62 87 62 / 30 20 20 40 PORTALES........................ 92 63 88 63 / 30 20 20 40 FORT SUMNER..................... 95 64 90 65 / 20 20 20 40 ROSWELL......................... 97 69 95 69 / 10 20 20 50 PICACHO......................... 88 63 89 62 / 10 20 30 40 ELK............................. 81 61 84 59 / 10 20 40 50 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
405 AM EDT THU AUG 8 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL EVENTUALLY MOVE PAST THE REGION ON FRIDAY NIGHT. IN THE MEANTIME...CHANCES FOR PERIODIC SHOWERS AND A THUNDERSTORM OR TWO WILL CONTINUE FOR TODAY AND FRIDAY. A DRIER WEEKEND IS IN STORE WITH TEMPERATURES REMAINING ON THE COOLER SIDE OF NORMAL FOR AUGUST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TODAY WILL BE A CRAZY...CONVOLUTED AND LOW CONFIDENCE FORECAST GIVEN THE NATURE OF ZONAL FLOW PATTERNS IN THE SUMMER MONTHS. THE FIRST ORDER OF BUSINESS WITH THIS MORNING`S UPDATE IS TO TRACK AND TIME THE CONVECTION MOVING THROUGH WESTERN NEW YORK AND IT`S IMPACT HERE IN CENTRAL DURING THE EARLY HOURS. CONVECTION LOOKS TO BE MAINLY DRIVEN NOW BY COLD POOL INTERACTION WITHIN A BROAD UNSTABLE ENVIRONMENT...AS WV LOOP SHOWS INITIATING SHORT WAVE IS RUNNING OUT AHEAD OF THE CONVECTION ACROSS LOWER ONTARIO. LINEAR TRACKING TAKES THE RAIN AND EMBEDDED TSRA ACROSS MAINLY THE FINGER LAKES REGION AND NORTHERN PORTIONS OF THE SOUTHERN TIER DURING THE EARLY DAYLIGHT HOURS AND HAVE ACCOUNTED FOR THIS WITH ABOUT 4-6 HOURS OF CATEGORICAL-LIKELY POPS OVER NORTHERN COUNTIES WITH SOME SLACK ON THE SOUTHERN END OF THE POP FIELD FOR NEW DEVELOPMENT. THINK THERE WILL ALSO CONTINUE TO BE WEAKENING OF THIS FEATURE AS THE MORNING WEARS ON. THEN...ATTENTION TURNS TO SLOWLY APPROACHING FRONTAL BOUNDARY FOR LATER THIS AFTERNOON. AFTER SCOURING MANY MODEL SOLUTIONS...AND PICKING THROUGH THE NOISE OF CONVECTIVE FEEDBACK...WE ARE HARD PRESSED TO FIND MUCH IN THE WAY OF FORCING FOR NEW CONVECTION THIS AFTERNOON ASIDE FROM MINOR HEIGHT AND PRESSURE FALLS ASSOCIATED WITH THE FRONTAL BOUNDARY...FORMING IN TANDEM WITH DECREASING DIURNAL STABILITY. THE MESOSCALE MODELS LIKE THE HRRR AND WRF-ARW CONVECT MAINLY ALONG THE FRONTAL BOUNDARY MOVING INTO WRN NY THIS AFTENROON WITH SPOTTY ACTIVITY IN OUR ARAE. WE THEREFORE FEEL MUCH OF THE DAY WILL FEATURE...AT BEST... SCATTERED NEW CONVECTIVE DEVELOPMENT ONCE THIS LINGERING RAIN FEATURE MAKES ITS WAY THROUGH OR DISSIPATES IN THE PROCESS. HAVE THUS SCALED BACK ON ANY LIKELY POPS WE HAD GOING THIS AFTERNOON. OTHER PARAMETERS ARE FAIRLY ROUTINE. TEMPERATURES AS A BLEND OF PREV FORECAST/00Z MOS AND 2M MODEL TEMPS AND LOOK TO BE MAINLY IN THE UPPER 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE FORECAST GETS NO EASIER TONIGHT WITH FRONT ONLY SAGGING INTO THE REGION. 00Z NAM AND GFS ARE SIMILAR IN FRONTAL PLACEMENT AND UPPER AIR MASS FIELDS...BUT THE RESULTANT QPF FIELDS ARE VERY DIFFERENT TONIGHT AND FRIDAY AND SEEM OVERDONE WITH RESPECT TO VERY SUBTLE FORCING MECHANISMS. AGAIN...WEEDING THROUGH THE CONVECTIVE FEEDBACK PROBLEMS AS BOTH MODELS TRY TO LIFT SOUTHERN PLAINS CONVECTIVE VORTS THROUGH OUR REGION OVERNIGHT...WE ARE AGAIN HARD PRESSED TO FIND SIGNIFICANT SYNOPTIC SUPPORT FOR AS MUCH RAIN AS THESE MODELS ARE CRANKING OUT ON US. THAT SAID...THE SFC FRONT WILL BE MOVING INTO THE REGION AND THERE IS A POSSIBILITY THAT SOME MINOR UPPER LEVEL FEATURE COULD RUN FAST THROUGH THE REGION. BOTH MODELS ALSO HINT AT AN INCRG SOUTHERLY LOW LEVEL JET IMPINGING ON THE FRONTAL ZONE AND OUR HIGHER TERRAIN AREAS IN NEPA/SENY LATE TONIGHT. WITHOUT MAKING TOO DRAMATIC A SWING IN THE FORECAST...HAVE LOWERED SOME OF THE PREVIOUS FORECAST POPS FOR TONIGHT AND FRIDAY...BUT HAVE MAINTAINED THE LIKELY TERMINOLOGY AS THERE JUST DOESN`T SEEM TO BE MUCH THERE TO WARRANT WIDESPREAD AREAS OF SHOWERS/TSRA. ALSO SHIFTED THE AXIS OF HIGHER POPS A BIT WESTWARD TO LINE UP BETTER WITH THE FRONTAL MOVEMENT. THE FOCUS ON THE SOUTHEAST ZONES JUST SEEMS UNREALISTIC AND THE GFS SEEMED TO HAVE TRENDED A BIT WEST THIS RUN WITH NAM MORE IN OUR EASTERN ZONES. THE TRENDS THEN SUPPORT THE FRONT TO MOVE EAST OF THE REGION FRIDAY NIGHT WITH DECREASING PRECIP PROBABILITY FROM WEST TO EAST THROUGH THE DAY FRIDAY AND EVENTUALLY A DRY OVERNIGHT INTO SATURDAY. HIGH PRESSURE AND COOL NORTHWESTERLY FLOW OVERSPREADS THE REGION THIS WEEKEND. BEST CHANCE FOR SUNSHINE LOOKS TO BE SUNDAY AS COLD ADVECTION CLOUDS ON THE FIRST DAY (SATURDAY) BEHIND A COLD FROPA HERE SPELLS STRATOCU FIELDS GALORE AND PARTLY TO MOSTLY CLOUDY CONDITIONS. FOLLOWED MOS AND 2M MODEL BLENDED TEMPS ALONG WITH PREVIOUS FORECAST WHICH HELPED TO COOL THINGS SLIGHTLY ON FRIDAY AND SATURDAY FROM PREV FORECAST. THE TREND ON SATURDAY WILL CERTAINLY FIT THE CLOUD IDEA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... 4 AM UPDATE... VERY FEW CHANGES MADE TO INHERITED GRIDS AS GOOD AGREEMENT BETWEEN THE GFS AND ECMWF SUPPORTS BETTER THAN AVERAGE CONFIDENCE THROUGH THE PERIOD. UPPER PATTERN THROUGH THE TIME FRAME WILL BE DOMINATED BY BROAD CYCLONIC FLOW ALOFT AS A BLOCKY MID-LATITUDE PATTERN PERSISTS THANKS TO STRONG HIGH PRESSURE ACROSS THE NORTHERN ATLANTIC AND CANADIAN PRAIRIE PROVINCES. BOTH THE GFS AND ECMWF AGREE THAT A SECOND UPPER LOW WILL SWING SOUTH FROM HUDSON BAY BY LATE MON/EARLY TUESDAY WHICH WILL SEND A COLD FRONT EAST ACROSS OUR REGION AS LOW PRESSURE TRACKS JUST OFF TO OUR NORTH. THUS EXPECT RENEWED SHWR AND THUNDERSTORM CHANCES BY TUESDAY BEFORE DRY WX RETURNS TO CONCLUDE THE PERIOD. BELOW NORMAL TEMPS EXPECTED WITH NO HINTS OF ANY MAJOR WARMING SEEN FOR THE FORESEEABLE FUTURE. 200 PM UPDATE... AREA REMAINS UNDER A BROAD LONG WAVE UPPER LEVEL TROUGH THROUGH THE PERIOD AND SLIGHTLY COOLER THAN NORMAL TEMPERATURES WITH HIGHS IN LOWER TO MIDDLE 70S AND NIGHTTIME LOWS IN THE 50S. A FRONT THAT MOVED THROUGH THE AREA EARLY SATURDAY IS FORECAST TO STALL IN A EAST-WEST MANNER ACROSS VIRGINA SATURDAY NIGHT INTO SUNDAY. FROM THIS POINT MODELS HAVE DIFFERENCES OF TIMING AND POSITIONING OF WAVES MOVING EASTWARD ALONG THIS FRONT THROUGH MIDWEEK CAUSING SOME UNCERTAINTY IN THE FORECAST. FORECASTED CLOUDS TO SPREAD NORTH WITH A WAVE ON SUNDAY BUT JUST PLACED A SLIGHT CHANCE THUNDERSTORMS IN THE POCONOS FOR SUNDAY AFTERNOON. HIGH PRESSURE BUILDS ACROSS SUNDAY NIGHT BEHIND THIS WAVE. A SHORT-WAVE MOVING AROUND THE UPR LEVEL LOW TO OUR NORTH MAY BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE AFTERNOON MONDAY. UNCERTAINTY INCREASES TUESDAY AS GFS LINKS A SHORT-WAVE MOVING AROUND THE UPR LOW TO THE NORTH WITH A SURFACE LOW AND WAVE MOVING NORTHEAST ALONG THAT FRONTAL ZONE AND SPREADS CLOUDS AND PRECIPITATION NORTHEAST ACROSS THE AREA TUESDAY. ON THE OTHER HAND THE ECMWF DOES NOT LINK A WAVE UP FROM THE SOUTH WITH JUST AN ISOLATED CHANCE. PUT A 30 POP IN TUESDAY AFTERNOON. SURFACE HIGH PRESSURE BUILDS IN FOR WEDNESDAY WITH A SHORTWAVE RIDGE ALOFT. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... VERY DIFFICULT FCST THIS MORNING AS LATEST SATELLITE AND OBSERVATION TRENDS HAVE SHOWN A NOTABLE DECREASE IN LOW STRATUS ACROSS THE REGION OVER THE PAST FEW HRS. ADDITIONALLY...CONVECTION NOW ENTERING THE GREATER BUFFALO METRO WILL CONTINUE WORKING EAST OVERNIGHT WITH POSSIBLE IMPACTS AT BOTH ELM AND ITH BY 10Z OR SO. THAT SAID...HAVE DELAYED IFR MENTION AT BGM FOR A FEW HRS BASED ON LATEST TRENDS...HOWEVER CONCERNS ARE THAT LOW CLOUDS WILL FILL BACK IN AS WE PROGRESS THROUGH THE EARLY MORNING. IF THIS DOES OCCUR...WE MAINLY EXPECT MVFR CONDITIONS AT REMAINING FCST LOCATIONS. AFTER 12Z...FCST BECOMES MORE CLOUDED AS WEAK TO MODERATE INSTABILITY DEVELOPS OVER THE REGION. ITS NEARLY IMPOSSIBLE TO DISCERN ANY SPECIFIC TIMING AS THERE REMAINS VERY LITTLE IN THE WAY OF ANY APPRECIABLE FORCING MECHANISMS. FOR NOW...WILL CONTINUE WITH EARLIER LINE OF THINKING WITH POSSIBLE SHWRS/STORMS DEVELOPING ALONG AND EAST OF THE I-81 CORRIDOR LATER THIS AFTERNOON. RAIN TO LIKELY CONTINUE INTO THE EVENING HRS...ESPECIALLY AT AVP AS NEXT SFC WAVE WORKS NORTH WITH TIME. OUTLOOK... FRI...VFR BUT MVFR IN SCATTERED SHRA/TSRA MAINLY SOUTH. SAT THRU MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...JAB NEAR TERM... SHORT TERM...JAB LONG TERM...BMW/CMG AVIATION...CMG
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
341 AM EDT THU AUG 8 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1223 AM EDT THURSDAY...CURRENT FORECAST IN GREAT SHAPE AND ONLY MINOR ADJUSTMENTS TO T/TD/MIN TEMP DATASETS AS OF THE MIDNIGHT HOUR. SCT CONVECTION ALONG PRE-FRONTAL TROUGH HAVING A HARD TIME MAKING IT INTO OUR REGION AND TRUDGING SLOWLY EAST FROM ONTARIO/OTTAWA VALLEY ATTM. INDEED...LATEST CAM MODEL RUNS ACTUALLY SHOWING MUCH OF THIS ACTIVITY EITHER WANING OR SPLITTING NORTH AND/OR SOUTH OF OUR AREA OVERNIGHT LEAVING MANY AREAS DRY. THUS PRIOR IDEA OF LOWERING POPS TO CHANCE (30/40 PCT) LOOKS RIGHT ON TRACK. TEMPERATURES WILL REMAIN MILD AND HOLD GENERALLY IN THE 60S TO LOCALLY NEAR 70 IN THE CHAMPLAIN VALLEY AS LIGHT TO MODERATE SOUTH FLOW CONTINUES. HAVE A GREAT NIGHT. PRIOR DISCUSSION FOLLOWS... BASED ON CURRENT RADAR AND RECENT NAM/RAP/HRRR GUIDANCE TRENDS HAVE MADE FAIRLY SIGNIFICANT DOWNWARD TWEAKS TO POPS TONIGHT INTO THURSDAY MORNING. ASIDE FOR SOME SHOWERS THAT HAD MOVED ACROSS THE NORTHERN CHAMPLAIN VALLEY INTO NORTHERN VERMONT...STEADIER/HEAVIER SHOWERS AND THUNDERSTORMS REMAIN ACROSS EASTERN ONTARIO AND THE NORTHERN SHORE OF LAKE ONTARIO. THE RADAR RETURNS ACROSS THE SAINT LAWRENCE VALLEY ARE MERELY ANVIL SHADOWS...AND RECENT TRENDS SHOW BETTER CONVECTIVE DEVELOPMENT TRAILING BACK ALONG THE NORTHERN SHORE OF LAKE ONTARIO IN THE VICINITY OF THE TORONTO AREA. AS MENTIONED...FEEL THAT THE NAM...RAP AND HRRR MODELS ARE CURRENTLY HANDLING PRESENT CONDITIONS THE BEST AND HAVE THEREFORE ALIGNED THE FORECAST CLOSER TO THAT SUITE OF GUIDANCE. SPECULATING THAT OTHER WETTER GUIDANCE...E.G. THE GFS...MAY HAVE BEEN KEYING ON DEEPER MOISTURE FEED WHICH THE EARLIER MCS OVER PA MAY HAVE TAPPED INTO. NEVERTHELESS...STILL EXPECT SFC COLD FRONT ACROSS ONTARIO TO APPROACH THE NORTH COUNTRY THROUGH OVERNIGHT BUT WILL ONLY BE GOING WITH CHANCE TO HIGH CHANCE POPS THROUGH SUNRISE...AND THEN SLIGHT CHANCE TO CHANCE THROUGH THE THURSDAY MORNING PERIOD. CURRENT TEMPS/DEWPOINTS STILL LOOK ON TRACK AND IT SHOULD OTHERWISE BE A CLOUDY...MILDER AND SLIGHTLY MORE HUMID NIGHT THAN RECENTLY WITH LOWS IN THE UPPER 50S TO THE 60S. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 341 AM EDT THURSDAY...ELONGATED AREA OF SFC HIGH PRESSURE STRETCHING FROM THE GREAT LKS REGION TO THE EAST COAST FOR THE SAT NGT-MONDAY MORNING PERIOD W/ END RESULT OF RIDGE SHIFTING OFFSHORE THRU THE DAY MONDAY. EXPECTING NICE STRETCH OF WX OVER THE UPCOMING WEEKEND AS A RESULT. THE NORTH COUNTRY WILL FEEL THE EFFECTS OF BROAD UPPER LOW OVER EASTERN CANADA. ANOTHER LOW PINWHEELING AROUND THIS SYSTEM WILL DIVE SE THRU THE GREAT LKS MONDAY AND ACROSS THE NORTHEAST REGION INTO MIDWEEK. ZONAL MIDLEVEL FLOW COMBINED WITH SOUTHERLY WINDS AT THE SFC...WILL ALLOW FOR SLOW MVMNT THRU AREA AND WILL BRING AMPLE POTENTIAL QPF AS A RESULT OF SSW FLOW. WILL BE CARRYING -RW FOR THE LATTER PORTION OF EXTENDED INTO EARLY TUESDAY EVENING BFR SFC RIDGE RETURNS FROM THE WEST DRYING REGION OUT AGAIN WED INTO THURS. TEMPS NEAR NORMAL THRU PERIOD WITH HIGHS RANGING IN THE MID TO UPPER 70S AND LOWS IN THE 40S TO L50S. PRECIP/CLD COVER MONDAY NGT INTO TUESDAY COULD HAMPER TEMPS. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... THROUGH 06Z FRIDAY...SCT -RW WITH SOME POSSIBLE FG THRU 12Z THURSDAY WILL BRING MVFR COND WITH VSBY DOWN TO 3-6SM AT TIMES AND CEILINGS DOWN TO BKN025-030 AT TIMES. FROM 12Z THURSDAY VFR CONDITIONS WITH CEILINGS BKN040-060 AND VCSH. CHANCE FOR TRW TO DEVELOP LATE IN AFTNOON INTO EVENING HRS. AFT 00Z FRI...SOME MVFR FG FOR SLK/MPV ALONG WITH CHANCE FOR RW/TRW AS BOUNDARY PUSHES THRU REGION. WINDS SSW 10-20KTS WITH GUSTS NEAR 30KTS FOR BTV. LGT/VAR FOR MPV/SLK AFT 00Z FRI. OUTLOOK 06Z FRIDAY THROUGH MONDAY... 06Z FRIDAY THROUGH 00Z SATURDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 00Z SATURDAY THROUGH MONDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...JMG/LOCONTO SHORT TERM...WGH LONG TERM...JN AVIATION...LAHIFF/JN MARINE...BTV EQUIPMENT...BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
139 AM EDT THU AUG 8 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1223 AM EDT THURSDAY...CURRENT FORECAST IN GREAT SHAPE AND ONLY MINOR ADJUSTMENTS TO T/TD/MIN TEMP DATASETS AS OF THE MIDNIGHT HOUR. SCT CONVECTION ALONG PRE-FRONTAL TROUGH HAVING A HARD TIME MAKING IT INTO OUR REGION AND TRUDGING SLOWLY EAST FROM ONTARIO/OTTAWA VALLEY ATTM. INDEED...LATEST CAM MODEL RUNS ACTUALLY SHOWING MUCH OF THIS ACTIVITY EITHER WANING OR SPLITTING NORTH AND/OR SOUTH OF OUR AREA OVERNIGHT LEAVING MANY AREAS DRY. THUS PRIOR IDEA OF LOWERING POPS TO CHANCE (30/40 PCT) LOOKS RIGHT ON TRACK. TEMPERATURES WILL REMAIN MILD AND HOLD GENERALLY IN THE 60S TO LOCALLY NEAR 70 IN THE CHAMPLAIN VALLEY AS LIGHT TO MODERATE SOUTH FLOW CONTINUES. HAVE A GREAT NIGHT. PRIOR DISCUSSION FOLLOWS... BASED ON CURRENT RADAR AND RECENT NAM/RAP/HRRR GUIDANCE TRENDS HAVE MADE FAIRLY SIGNIFICANT DOWNWARD TWEAKS TO POPS TONIGHT INTO THURSDAY MORNING. ASIDE FOR SOME SHOWERS THAT HAD MOVED ACROSS THE NORTHERN CHAMPLAIN VALLEY INTO NORTHERN VERMONT...STEADIER/HEAVIER SHOWERS AND THUNDERSTORMS REMAIN ACROSS EASTERN ONTARIO AND THE NORTHERN SHORE OF LAKE ONTARIO. THE RADAR RETURNS ACROSS THE SAINT LAWRENCE VALLEY ARE MERELY ANVIL SHADOWS...AND RECENT TRENDS SHOW BETTER CONVECTIVE DEVELOPMENT TRAILING BACK ALONG THE NORTHERN SHORE OF LAKE ONTARIO IN THE VICINITY OF THE TORONTO AREA. AS MENTIONED...FEEL THAT THE NAM...RAP AND HRRR MODELS ARE CURRENTLY HANDLING PRESENT CONDITIONS THE BEST AND HAVE THEREFORE ALIGNED THE FORECAST CLOSER TO THAT SUITE OF GUIDANCE. SPECULATING THAT OTHER WETTER GUIDANCE...E.G. THE GFS...MAY HAVE BEEN KEYING ON DEEPER MOISTURE FEED WHICH THE EARLIER MCS OVER PA MAY HAVE TAPPED INTO. NEVERTHELESS...STILL EXPECT SFC COLD FRONT ACROSS ONTARIO TO APPROACH THE NORTH COUNTRY THROUGH OVERNIGHT BUT WILL ONLY BE GOING WITH CHANCE TO HIGH CHANCE POPS THROUGH SUNRISE...AND THEN SLIGHT CHANCE TO CHANCE THROUGH THE THURSDAY MORNING PERIOD. CURRENT TEMPS/DEWPOINTS STILL LOOK ON TRACK AND IT SHOULD OTHERWISE BE A CLOUDY...MILDER AND SLIGHTLY MORE HUMID NIGHT THAN RECENTLY WITH LOWS IN THE UPPER 50S TO THE 60S. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 341 PM EDT WEDNESDAY...THE EXTENDED PORTION OF THE FORECAST WILL FEATURE PRETTY QUIET AND COOL WEATHER...NO SIGNIFICANT CHANCES FOR PRECIPITATION. UPPER LEVEL LOW LIFTS NORTHEAST AND AWAY FROM THE NORTH COUNTRY SATURDAY AND A RIDGE OF SURFACE HIGH PRESSURE BUILDS INTO THE AREA. MAINLY DRY WEATHER IS EXPECTED FROM SATURDAY THROUGH MONDAY. A LOW PRESSURE SYSTEM PASSING NORTH OF OUR REGION ON MONDAY NIGHT WILL BRING A CHANCE FOR SOME SHOWERS...THOUGH BEST DYNAMICS REMAIN WELL NORTH OF OUR FORECAST AREA. TUESDAY THROUGH WEDNESDAY WILL ALSO BE QUIET WITH ANOTHER RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... THROUGH 06Z FRIDAY...SCT -RW WITH SOME POSSIBLE FG THRU 12Z THURSDAY WILL BRING MVFR COND WITH VSBY DOWN TO 3-6SM AT TIMES AND CEILINGS DOWN TO BKN025-030 AT TIMES. FROM 12Z THURSDAY VFR CONDITIONS WITH CEILINGS BKN040-060 AND VCSH. CHANCE FOR TRW TO DEVELOP LATE IN AFTNOON INTO EVENING HRS. AFT 00Z FRI...SOME MVFR FG FOR SLK/MPV ALONG WITH CHANCE FOR RW/TRW AS BOUNDARY PUSHES THRU REGION. WINDS SSW 10-20KTS WITH GUSTS NEAR 30KTS FOR BTV. LGT/VAR FOR MPV/SLK AFT 00Z FRI. OUTLOOK 06Z FRIDAY THROUGH MONDAY... 06Z FRIDAY THROUGH 00Z SATURDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 00Z SATURDAY THROUGH MONDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...JMG/LOCONTO SHORT TERM...WGH LONG TERM...NEILES AVIATION...LAHIFF/JN MARINE...BTV EQUIPMENT...BTV
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1223 AM EDT THU AUG 8 2013 .SYNOPSIS... SOUTHERLY FLOW WILL PERSIST ACROSS THE NORTH COUNTRY OVERNIGHT THROUGH THURSDAY WITH A CHANCE OF RAIN SHOWERS OVERNIGHT AND A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY. A COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY BRINGING MORE SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY. SOME THUNDERSTORMS ON FRIDAY COULD PRODUCE LOCALLY HEAVY RAINFALL. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTH COUNTRY ON FRIDAY NIGHT AND WILL BRING FAIR AND DRY WEATHER TO THE REGION THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1223 AM EDT THURSDAY...CURRENT FORECAST IN GREAT SHAPE AND ONLY MINOR ADJUSTMENTS TO T/TD/MIN TEMP DATASETS AS OF THE MIDNIGHT HOUR. SCT CONVECTION ALONG PRE-FRONTAL TROUGH HAVING A HARD TIME MAKING IT INTO OUR REGION AND TRUDGING SLOWLY EAST FROM ONTARIO/OTTAWA VALLEY ATTM. INDEED...LATEST CAM MODEL RUNS ACTUALLY SHOWING MUCH OF THIS ACTIVITY EITHER WANING OR SPLITTING NORTH AND/OR SOUTH OF OUR AREA OVERNIGHT LEAVING MANY AREAS DRY. THUS PRIOR IDEA OF LOWERING POPS TO CHANCE (30/40 PCT) LOOKS RIGHT ON TRACK. TEMPERATURES WILL REMAIN MILD AND HOLD GENERALLY IN THE 60S TO LOCALLY NEAR 70 IN THE CHAMPLAIN VALLEY AS LIGHT TO MODERATE SOUTH FLOW CONTINUES. HAVE A GREAT NIGHT. PRIOR DISCUSSION FOLLOWS... BASED ON CURRENT RADAR AND RECENT NAM/RAP/HRRR GUIDANCE TRENDS HAVE MADE FAIRLY SIGNIFICANT DOWNWARD TWEAKS TO POPS TONIGHT INTO THURSDAY MORNING. ASIDE FOR SOME SHOWERS THAT HAD MOVED ACROSS THE NORTHERN CHAMPLAIN VALLEY INTO NORTHERN VERMONT...STEADIER/HEAVIER SHOWERS AND THUNDERSTORMS REMAIN ACROSS EASTERN ONTARIO AND THE NORTHERN SHORE OF LAKE ONTARIO. THE RADAR RETURNS ACROSS THE SAINT LAWRENCE VALLEY ARE MERELY ANVIL SHADOWS...AND RECENT TRENDS SHOW BETTER CONVECTIVE DEVELOPMENT TRAILING BACK ALONG THE NORTHERN SHORE OF LAKE ONTARIO IN THE VICINITY OF THE TORONTO AREA. AS MENTIONED...FEEL THAT THE NAM...RAP AND HRRR MODELS ARE CURRENTLY HANDLING PRESENT CONDITIONS THE BEST AND HAVE THEREFORE ALIGNED THE FORECAST CLOSER TO THAT SUITE OF GUIDANCE. SPECULATING THAT OTHER WETTER GUIDANCE...E.G. THE GFS...MAY HAVE BEEN KEYING ON DEEPER MOISTURE FEED WHICH THE EARLIER MCS OVER PA MAY HAVE TAPPED INTO. NEVERTHELESS...STILL EXPECT SFC COLD FRONT ACROSS ONTARIO TO APPROACH THE NORTH COUNTRY THROUGH OVERNIGHT BUT WILL ONLY BE GOING WITH CHANCE TO HIGH CHANCE POPS THROUGH SUNRISE...AND THEN SLIGHT CHANCE TO CHANCE THROUGH THE THURSDAY MORNING PERIOD. CURRENT TEMPS/DEWPOINTS STILL LOOK ON TRACK AND IT SHOULD OTHERWISE BE A CLOUDY...MILDER AND SLIGHTLY MORE HUMID NIGHT THAN RECENTLY WITH LOWS IN THE UPPER 50S TO THE 60S. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... AS OF 428 PM EDT WEDNESDAY...ON THURSDAY MODELS SHOW MOISTURE STREAMING NORTHEASTWARD INTO THE REGION FROM THE OHIO VALLEY. CONDITIONS DESTABILIZE DURING THE DAY ON THURSDAY...SO HAVE GONE WITH LIKELY POPS FOR SHOWERS AND THUNDERSTORMS. EXPECTING THIS ACTIVITY TO CONTINUE INTO THURSDAY NIGHT. MOISTURE WILL CONTINUE TO STREAM INTO THE REGION ON FRIDAY WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. HAVE ADDED ENHANCED WORDING TO THE FORECAST TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION DURING THE DAY ON FRIDAY. DRIER AIR WORKING INTO THE REGION FRIDAY NIGHT AFTER THE COLD FRONTAL PASSAGE. EXPECTING SHOWER AND THUNDERSTORM ACTIVITY TO DIMINISH EARLY FRIDAY EVENING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 341 PM EDT WEDNESDAY...THE EXTENDED PORTION OF THE FORECAST WILL FEATURE PRETTY QUIET AND COOL WEATHER...NO SIGNIFICANT CHANCES FOR PRECIPITATION. UPPER LEVEL LOW LIFTS NORTHEAST AND AWAY FROM THE NORTH COUNTRY SATURDAY AND A RIDGE OF SURFACE HIGH PRESSURE BUILDS INTO THE AREA. MAINLY DRY WEATHER IS EXPECTED FROM SATURDAY THROUGH MONDAY. A LOW PRESSURE SYSTEM PASSING NORTH OF OUR REGION ON MONDAY NIGHT WILL BRING A CHANCE FOR SOME SHOWERS...THOUGH BEST DYNAMICS REMAIN WELL NORTH OF OUR FORECAST AREA. TUESDAY THROUGH WEDNESDAY WILL ALSO BE QUIET WITH ANOTHER RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... THROUGH 00Z FRIDAY...DIFFICULT AVIATION FORECAST OVER THE NEXT 24 HOURS AS MOST MODELS NOT HANDLING THE CURRENT CONDITIONS VERY WELL. BROKEN LINE OF SHOWERS/STORMS ENTERING THE OTTAWA RIVER VALLEY ASSOCIATED WITH A PRE-FRONTAL SURFACE TROUGH WILL SHIFT EAST INTO THE NORTH COUNTRY OVERNIGHT WHILE DISSIPATING. HAVE PUT IN SOME VCTS FOR KMSS/KSLK BUT ONLY VCSH EASTWARD AS INSTABILITY WEAKENS BY THE TIME PRECIP GETS THERE. SCATTERED SHOWERS PERSIST THROUGH 09-12Z ALONG WITH SOME MVFR CIGS...THEN DISSIPATE FOR THE MORNING HOURS AS THE REAL COLD FRONT BEGINS TO MOVE INTO THE SAINT LAWRENCE VALLEY. MAINLY VFR CONDITIONS ARE THEN EXPECTED THURSDAY WITH SCATTERED SHOWERS AND POSSIBLY STORMS ARE LIKELY AGAIN FROM THE CHAMPLAIN VALLEY EAST DURING THE AFTERNOON...THOUGH DIFFICULT TO FORECAST TIMING AND LOCATION SO HAVE JUST GONE WITH SOME MORE VCSH. WINDS REMAIN MODERATE AT 5-10 KNOTS THROUGH THE PERIOD... GUSTING A BIT THIS EVENING AND AGAIN TOMORROW AFTERNOON. OUTLOOK 00Z FRIDAY THROUGH MONDAY... 00Z FRIDAY THROUGH 00Z SATURDAY...VFR WITH OCCASIONAL MVFR/IFR IN SHOWERS/THUNDERSTORMS AS A WARM/OCCLUDED FRONT LIFTS ACROSS THE AREA. 00Z SATURDAY THROUGH MONDAY...MAINLY VFR UNDER SURFACE HIGH PRESSURE. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT THROUGH EARLY THURSDAY MORNING. SOUTH WINDS WILL INCREASE THIS EVENING TO 15 TO 25 KNOTS...PEAKING AROUND MIDNIGHT WITH SOME GUSTS UP TO 30 KNOTS..ESPECIALLY ACROSS THE OPEN WATERS OF CENTRAL AND NORTHERN LAKE CHAMPLAIN. WINDS WILL GRADUALLY DECREASE TOWARDS THURSDAY MORNING WITH SOUTH WINDS FROM 10 TO 20 KNOTS EXPECTED ON THURSDAY. THESE WINDS WILL CREATE WAVES OF 2 TO 4 FEET ON THE BROAD LAKE...ESPECIALLY ACROSS THE CENTRAL AND NORTHERN PORTIONS. WAVE HEIGHTS WILL DECREASE TO 1 TO 3 FEET FOR THURSDAY. IN ADDITION...SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MAY AFFECT THE AREA TONIGHT THROUGH THURSDAY...WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY LATE THURSDAY NIGHT AND INTO FRIDAY. && .EQUIPMENT... AS OF 456 PM EDT WEDNESDAY...THE KTYX 88D DOPPLER RADAR IN NORTHERN NEW YORK HAS BEEN RESTORED TO SERVICE. SOME ADDITIONAL WORK ON THIS RADAR WILL NEED TO BE DONE ON THURSDAY. AS OF 350 AM EDT WEDNESDAY...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. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...JMG/LOCONTO SHORT TERM...WGH LONG TERM...NEILES AVIATION...LAHIFF MARINE...MUCCILLI EQUIPMENT...BTV
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
320 AM EDT THU AUG 8 2013 .SYNOPSIS... A GRADUAL TRANSITION TO WARMER TEMPERATURES AND INCREASED CHANCES FOR RAIN WILL OCCUR THROUGH THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM THURSDAY...AFTER ENJOYING SEVERAL DAYS OF BELOW-NORMAL TEMPERATURES AND HUMIDITY...THE REALITY OF AUGUST RETURNS TO THE CAROLINAS TODAY. THE SURFACE RIDGE AXIS THAT HELD OUR SURFACE WINDS EASTERLY OVER THE PAST SEVERAL DAYS IS GONE. BERMUDA HIGH PRESSURE WILL ESTABLISH A SOUTH FLOW ACROSS THE AREA TODAY WITH TEMPERATURES RISING TO AROUND 90 INLAND AND UPPER 80S NEAR THE COAST. WITH NO SUBSIDENCE INVERSIONS TO DEAL WITH TODAY AND SURFACE-BASED CAPE BUILDING TO AROUND 1000 J/KG...LOOK FOR SCATTERED SHOWERS AND A FEW T-STORMS TODAY AS WELL. ACTIVITY COULD GET A VERY EARLY START ALONG THE COAST AND PARTICULARLY IN THE CAPE FEAR REGION WHERE THE LAST SEVERAL RUNS OF THE HRRR INDICATE SHOWERS MAY DEVELOP AS EARLY AS SUNRISE NEAR SOUTHPORT AND WILMINGTON. BY LATE MORNING SCATTERED CONVECTION SHOULD BE LINING UP ALONG THE DEVELOPING SEABREEZE BOUNDARY...LIFTING SLOWLY INLAND THROUGH THE AFTERNOON HOURS. FORECAST POPS RANGE FROM 20-40 PERCENT...HIGHEST ACROSS SE NORTH CAROLINA. FOR TONIGHT...INLAND CONVECTIVE ACTIVITY SHOULD GRADUALLY DIMINISH DURING THE EVENING HOURS WITH SKIES BECOMING MOSTLY CLEAR TO PARTLY CLOUDY. SOME LOW STRATUS MAY DEVELOP VERY LATE TONIGHT INLAND AS SATURATION OCCURS WITHIN THE BOUNDARY LAYER BUT 1000-FOOT WINDS REMAIN A LITTLE TOO STRONG FOR FOG. LOWS WILL FALL TO 72-74 INLAND AND 73-78 NEAR THE COAST. SOME SOUTH-FACING BEACHES COULD SEE LOW TEMPERATURES STRUGGLE TO DROP BELOW 80 IF THE ONSHORE WIND CONTINUES THROUGH THE NIGHT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...MID LEVEL RIDGE WILL REMAIN ACROSS THE AREA AS A WESTERLY PATTERN DEVELOPS AT THE MID LEVELS. HOWEVER THERE WILL BE INTERVALS OF RICHER THETA-E AIR TRAVERSING THE ZONAL FLOW WHICH WARRANTS AT LEAST LOW CHANCE POPS THROUGH THE PERIOD. THE NUMEROUS CLUSTERS OF THUNDERSTORMS WE HAVE SEEN MOVING ACROSS THE TENNESSEE VALLEY WILL NOW TAKE AIM ON THE CAROLINAS. THE PIEDMONT TROUGH WILL BE ENHANCED WITH THE WESTERLY FLOW WHICH WILL ASSIST IN THE FORCING AS WELL. I HAVE MAINTAINED THE CHANCE POPS...MAINLY ON A DIURNAL BASIS THROUGH THE PERIOD. AS WE GET CLOSER TO THE WEEKEND...THERE WILL BE TIMES WHEN LIKELY POPS WILL BE WARRANTED BUT THIS WILL BE BETTER ADDRESSED WITH THE NEAR TERM FORECAST. TEMPERATURE TRENDS REMAIN RELATIVELY UNCHANGED WITH THE STRONG RIDGE AND DOWNSLOPE COMPONENT LEADING TO READINGS SLIGHTLY ABOVE CLIMATOLOGY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY...MEDIUM RANGE GUIDANCE IS TRENDING TOWARD A RATHER WET SCENARIO FOR THE EXTENDED PERIOD. ELONGATED MID LEVEL RIDGE SHIFTS WEST AND TROUGHING DEVELOPS ACROSS THE OHIO VALLEY. THE TROUGH REMAINS IN PLACE AS DOES THE FRONT ASSOCIATED WITH IT...WHICH IS POSITIONED RIGHT ACROSS OUR AREA. THIS WILL PROVIDE A GOOF FOCUSING MECHANISM FOR INTERVALS OF SHOWERS AND THUNDERSTORMS. HAVE INCREMENTALLY INCREASED POPS TO REPRESENT THIS TREND. TEMPERATURES FORECAST IS ALREADY SHOWING LOWER THAN USUAL DIURNAL RANGE WITH THE MOISTURE AND NEEDED NO CHANGES WITH THE MORNING UPDATE. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... AS OF 06Z...ISOLATED SHRA OVER THE ATLANTIC SHOULD REMAIN JUST EAST OF THE ILM AIRPORT THROUGH DAYBREAK. ANTICIPATE DEVELOPMENT OF MVFR CIGS ALONG THE COAST...WITH POSSIBLE IFR/LIFR INLAND DUE TO FOG & LOW CIGS AN HOUR OR TWO BEFORE DAYBREAK. FLIGHT CATEGORY SHOULD IMPROVE TO VFR NO LATER THAN 13-14Z. CANNOT RULE OUT ISOLATED SHOWERS...THUS HAVE OPTED TO INTRODUCE VCSH AT ALL SITES...BEGINNING ALONG THE COAST FIRST. SHOWERS WILL TAPER OFF IN THE EVENING HOURS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM THURSDAY...THE SURFACE RIDGE AXIS THAT HAS HELD OUR WIND DIRECTIONS EASTERLY FOR THE PAST SEVERAL DAYS HAS FINALLY BROKEN DOWN. RATHER THAN CANADIAN HIGH PRESSURE POKING DOWN FROM THE NORTHEAST...OUR WEATHER TODAY AND TONIGHT WILL COME UNDER THE INFLUENCE OF BERMUDA HIGH PRESSURE FROM THE EAST. THIS MEANS WINDS WILL BECOME SOUTHERLY TODAY AND SOUTH-SOUTHWESTERLY TONIGHT...WITH SPEEDS AVERAGING 10-12 KNOTS. SEAS ARE CURRENTLY 2-3 FT WITH PERIODS SPLIT BETWEEN A 6 SECOND WIND WAVE AND A WEAK 9-10 SECOND SOUTHEAST SWELL. SEAS MAY BUILD HALF A FOOT THROUGH TONIGHT AS SOUTH WINDS FURTHER DEVELOP THE WIND WAVE COMPONENT. RADAR CURRENTLY SHOWS ONLY ISOLATED SHOWERS OUT BEYOND 30 MILES FROM SHORE...BUT MODELS ARE SHOWING WE SHOULD HAVE SCATTERED SHOWERS DEVELOPING NEARSHORE NEAR AND NORTH OF CAPE FEAR THIS MORNING. CONVECTIVE ACTIVITY SHOULD LARGELY SHIFT INLAND THIS AFTERNOON AS THE SEABREEZE CIRCULATION BECOMES BETTER DEVELOPED. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...ELEMENTS REMAIN THE SAME FOR THE COASTAL WATERS THROUGH THE PERIOD AS BERMUDA HIGH PRESSURE AND THE PIEDMONT TROUGH KEEP A SOUTHWESTERLY FLOW IN PLACE. SPEEDS REMAIN STABLE IN A RANGE OF 10-15 KNOTS...WHICH IF ANYTHING MAY BE ON THE HIGHER END SATURDAY AFTERNOON AS THE TROUGH STRENGTHENS. THE TEPID INCREASE IN WINDS ISN/T ENOUGH TO IMPACT SIGNIFICANT SEAS...WHICH REMAIN IN A 2-3 FOOT RANGE. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM THURSDAY...DIFFUSE FRONT WILL REMAIN JUST INLAND...AT LEAST LOOKING AT THE LATEST WPC FORECAST AND THIS WILL KEEP A RATHER WEAK SOUTHWESTERLY FLOW IN PLACE. SPEEDS CONTINUE TO HOVER AROUND TEN KNOTS OR BELOW. CAN/T RULE OUT BRIEF DISRUPTIONS IN THE SYNOPTIC FLOW WITH INTERVALS OF CONVECTION EXPECTED BUT THIS OF COURSE IS ALL BUT IMPOSSIBLE TO FORECAST THIS FAR OUT IN TIME. SIGNIFICANT SEAS SHOW LITTLE CHANGE AS WELL WITH 2-3 FEET AND LITTLE IN THE WAY OF A SWELL COMPONENT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...TRA SHORT TERM...SHK LONG TERM...SHK AVIATION...SGL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1242 AM CDT THU AUG 8 2013 .UPDATE... ISSUED AT 1242 AM CDT THU AUG 8 2013 LINGERING ISOLATED LIGHT RAIN SHOWERS OVER SOUTH CENTRAL NORTH DAKOTA WERE ASSOCIATED WITH WEAK UPPER LEVEL IMPULSES MOVING SOUTHEASTWARD ACROSS THE STATE. CURRENT FORECAST ON TRACK REGARDING THIS...AS WELL AS WINDS AND TEMPERATURES FOR THE OVERNIGHT HOURS. UPDATE ISSUED AT 903 PM CDT WED AUG 7 2013 MAIN UPDATE WAS TO REMOVE MENTION OF THUNDER FOR ALL BUT THE SOUTHWEST UNTIL MIDNIGHT...THEN REMOVE THUNDER ALTOGETHER. LATEST WATER VAPOR IMAGERY SHOWED A SHORTWAVE NOW OVER WESTERN NORTH DAKOTA...WITH A NARROW BAND OF LIFT/RAIN SHOWERS SOUTH OF HIGHWAY 2...FROM NEAR NEW TOWN EAST TO HARVEY. THIS AREA WAS CONTINUING TO SAG SOUTH WHILE CONTINUING TO ADVANCE EAST. LOCAL RADAR WAS ALSO SHOWING A WEAK LINE OF SHOWERS EXTENDING FROM GARRISON SOUTH TO BISMARCK. SPC MESO-ANALYSIS SHOWS MID LEVEL LAPSE RATES INCREASING IN RESPONSE TO THE SHORTWAVE IN WESTERN NORTH DAKOTA. WITH 50KT 0-6KM SHEAR IN THE SOUTHWEST...WILL CONTINUE TO MENTION ISOLATED THUNDERSTORMS. A LACK OF INSTABILITY ELSEWHERE WILL INHIBIT ANY THREAT OF THUNDERSTORMS. THE RAP AND 00Z NAM MAINTAIN THE IDEA THAT ISOLATED SHOWERS WILL CONTINUE TO PUSH SOUTH TO THE BORDER THROUGH 12Z THURSDAY. CONCUR WITH THIS IDEA BASED ON THE POSITION AND MOVEMENT OF THE AFOREMENTIONED SHORTWAVE. MINOR UPDATES TO POPS/SKY/WX AND HOURLY TEMPERATURES. UPDATE ISSUED AT 542 PM CDT WED AUG 7 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE NOW WORKING ITS WAY INTO NORTHEAST MONTANA FROM SOUTHERN SASKATCHEWAN. AN AREA OF RAIN SHOWERS CONTINUE TO MOVE INTO NORTHWEST NORTH DAKOTA. THE LATEST RAP HAS A GOOD READ ON THE ACTIVITY AS SCOOTS IT ACROSS THE NORTH CENTRAL THIS EVENING. IN ADDITION...WILL WATCH FOR SHOWERS TO DEVELOP IN THE WEST AND SOUTH CENTRAL EARLY TONIGHT PER RAP MODEL. RADAR SHOWING A WEAK LINE TRYING TO GENERATE FROM NEAR WILLISTON SOUTH TO TROTTERS AT THIS MOMENT. BEST FORCING REMAINS NORTH. THUS WILL CONTINUE WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NORTH THIS EVENING AND ISOLATED SHOWERS/THUNDERSTORMS WEST AND CENTRAL OVERNIGHT. GIVEN THE WEAK INSTABILITY...THUNDER SHOULD REMAIN ISOLATED. MINOR UPDATES TO HOURLY TEMPS/DEWPOINTS AND CHANGED UNCERTAINTY WORDING TO AREAL COVERAGE IN THE WEATHER GROUP BASED ON RADAR. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 338 PM CDT WED AUG 7 2013 CURRENTLY...A STRONG UPPER LEVEL JET AND A SHORTWAVE IMPULSE TRACKING ACROSS SOUTHERN SASKATCHEWAN IS RESPONSIBLE FOR PRODUCING SCATTERED SHOWERS FROM NORTHEAST MONTANA INTO NORTHWEST NORTH DAKOTA. THE SHOWERS ARE EXPECTED TO TRACK EAST AND SOUTH ACROSS THE AREA LATE THIS AFTERNOON AND THIS EVENING. SIMILAR TO THE TRACK OF A SHORTWAVE YESTERDAY. THE MAIN DIFFERENCE IS THE ATMOSPHERE IS MORE STABLE TODAY. HOWEVER...WITH A STRONG UPPER LEVEL JET AND SHORTWAVE...WE CANNOT RULE OUT A FEW THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING...WITH SMALL HAIL AND GUSTY WINDS. HOWEVER IN THE FORECAST WE LIMITED THE BEST CHANCES TO THE NORTH LATE THIS AFTERNOON...AND WITH LIMITED INSTABILITY AND CAPPING ALOFT...WE KEPT A MENTION OF SHOWERS WITH ONLY ISOLATED THUNDERSTORMS. EXPECT PRECIPITATION CHANCES TO DIMINISH AS THE SYSTEM TRACKS SOUTHEAST. BUT THE LATEST RAP AND HRRR HOLD REFLECTIVITIES TOGETHER AS THEY TRACK INTO THE SOUTHEAST CWA AROUND MIDNIGHT. MODELS HAVE TRENDED FARTHER SOUTH WITH THE NEXT WAVE COMING INTO THE AREA AFTER MIDNIGHT. HAVE THEREFORE CONTINUED THE TREND OF LOWERING POPS ACROSS THE AREA. CURRENTLY HAVE CHANCE POPS ACROSS THE FAR SOUTHWEST AND SOUTH CENTRAL LATE TONIGHT...AND HAVE DROPPED POPS ACROSS THE SOUTH ON THURSDAY MORNING. ANOTHER SHORTWAVE MOVING ACROSS ALBERTA TONIGHT WILL DROP SOUTHEAST INTO THE LOCAL AREA THURSDAY AFTERNOON. THIS COULD DEVELOP AN ISOLATED SHOWERS ACROSS THE NORTH DURING THE AFTERNOON. TEMPERATURES WILL REMAIN ON THE COOL SIDE WITH HIGHS RANGING FROM THE 60S NORTH TO THE 70S SOUTH. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 PM CDT WED AUG 7 2013 CONTINUED BELOW NORMAL TEMPERATURES WILL HIGHLIGHT THE EXTENDED FORECAST. AS HAS BEEN THE PATTERN OVER THE LAST COUPLE WEEKS...NORTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE NORTHERN PLAINS THROUGH THE EXTENDED. THIS FAVORS BELOW NORMAL TEMPERATURES WITH HIGHS GENERALLY IN THE 70S...PERHAPS RECOVERING INTO THE LOWER 80S BY MID NEXT WEEK. OVERALL...THE COOLER EDGE OF GUIDANCE HAS BEEN HANDLING THIS PATTERN BETTER...AND THUS UTILIZED A BLEND OF THE BIAS CORRECTED 12 UTC SUITE. IN REGARDS TO PRECIPITATION...WHILE ISOLATED DIURNAL CONVECTION IS HARD TO RULE OUT ANY DAY UNDER NORTHWEST FLOW...THE FAVORED PERIODS FOR PRECIPITATION ARE SATURDAY WITH LEE SURFACE LOW PRESSURE AND AGAIN TUESDAY INTO WEDNESDAY AS PACIFIC ENERGY CRESTS THE UPPER LEVEL INTERMOUNTAIN WEST RIDGE AND PROPAGATES INTO THE NORTHERN PLAINS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1242 AM CDT THU AUG 8 2013 SCT TO BKN VFR CIGS EXPECTED THROUGH THE TAF PERIOD. NOT MUCH CHANGE IN SYNOPTIC PATTERN THIS 24 HOUR TIME PERIOD WITH SURFACE HIGH PRESSURE IN CANADA PUSHING SOUTHWARD FARTHER INTO NORTH DAKOTA...AND UPPER LEVEL DISTURBANCES IN THE NORTHWEST FLOW ALOFT. LIGHT EAST TO NORTHERLY WINDS WITH NO MENTION OF PRECIPITATION EXCEPT FOR AT KJMS EARLY IN THE TAF PERIOD WITH LINGERING LIGHT SHOWERS OVER SOUTH CENTRAL NORTH DAKOTA UNTIL AROUND 12Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...TWH LONG TERM...AYD AVIATION...JV
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
208 AM EDT THU AUG 8 2013 .SYNOPSIS... A COLD FRONT WILL SLOWLY PUSH INTO THE REGION TONIGHT AND THURSDAY. THE FRONT WILL EVENTUALLY STALL CLOSE TO THE OHIO RIVER BY FRIDAY MORNING. THIS FRONTAL BOUNDARY WILL THEN OSCILLATE NEAR THE OHIO RIVER THROUGH THE WEEKEND. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE PERIOD...ESPECIALLY FOR THOSE LOCATIONS CLOSER TO THE FRONTAL BOUNDARY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... HAVE UPDATED PRIMARILY TO ACCOUNT FOR SHOWERS AND THUNDERSTORMS OVER PORTIONS OF NORTHERN KENTUCKY SOUTH OF METRO CINCINNATI. A WEAK INFLECTION RUNNING ALONG BUT JUST SOUTHEAST OF THE I-71 CORRIDOR MAY HAVE AN ENHANCED POTENTIAL FOR SHOWERS THIS EVENING BUT ONLY FOR THE NEXT HOUR OR TWO. UPSTREAM STORMS OVER INDIANA DO NOT POSE A THREAT TO US IN THE NEXT 3-5 HOURS AND THE STORMS OVER KY WILL BE DYING OUT AS THEY SLOWLY MOVE ENE. BLENDED INTO THE 30ISH POPS TOWARDS DAYBREAK THAT WERE IN EARLIER FORECAST AND TRIED TO PLAY DOWN THE THREAT ELSEWHERE...AT LEAST FOR THE EARLY PART OF THE OVERNIGHT. HAVE USED A BLEND OF THE HRRR AND NAM FOR THE NEAR TERM FORECAST. A COLD FRONT WAS POISED TO OUR NORTHWEST THIS EVENING. THIS FRONT IS FORECAST TO SLOWLY SINK SOUTHEAST TOWARD THE AREA OVERNIGHT. CURRENT THINKING IS THAT CONVECTIVE ACTIVITY NEAR THE FRONT WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING AND FORCING. LATEST MODEL RUNS NOW SUGGEST THAT SUBTLE LOW LEVEL JET AND ASSOCIATED UPR LVL DISTURBANCE WILL LIKELY STAY TO OUR SOUTH AND SOUTHWEST OVERNIGHT. AS A RESULT...WITH VERY WEAK FORCING...CAN NOT SEE GOING MUCH HIGHER THAN 30 POPS FOR ALL LOCATIONS. WILL UPDATE THE ZONES TO REFLECT THIS. WILL ALSO REMOVE HEAVY RAIN THREAT GIVEN SPARSE COVERAGE. AMPLE LOW LEVEL MOISTURE AND DIMINISHING WINDS WILL MAKE FOG AND/OR STRATUS A CONCERN AFTER MIDNIGHT...ESPECIALLY IF HOLES CAN DEVELOP IN THE MID AND UPPER LEVEL CLOUDS. WILL CONTINUE TO MENTION AREAS OF FOG IN THE ZONES AFTER MIDNIGHT AS WELL AS IN THE HWO. LOWS WILL RANGE FROM THE UPPER 60S NW TO THE LOWER 70S ELSEWHERE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... THE LOWER GREAT LAKES AND OHIO VALLEY REGION WILL BE BETWEEN A LARGE ANOMALOUS UPR LVL LOW OVER ONTARIO AND A MID LVL SUBTROPICAL RIDGE OVER THE SRN STATES THROUGH THE SHORT TERM PERIOD. THIS SETUP WILL ONLY ALLOW AFOREMENTIONED FRONTAL SYSTEM TO MOVE EVER SO SLOWLY TO SOUTHEAST...EVENTUALLY STALLING NEAR THE OHIO RIVER BY FRIDAY MORNING AS MID LEVEL FLOW BECOMES ZONAL. THE FRONT WILL PROVIDE THE FOCUS FOR SHOWERS AND STORMS THROUGH THE PERIOD...BUT THE TIMING AND AREAL COVERAGE WILL BE PROBLEMATIC AS MODELS ARE ESSENTIALLY OFFERING DIFFERENT SOLUTIONS. HAVE GONE WITH A NAM/ECMWF BLEND WHICH IS FORECASTING A SLOWER FRONTAL MOVEMENT. AS SUCH...THERE IS A HINT OF A FRONTAL WAVE RIPPLING ALONG THE FRONT ON THURSDAY THROUGH THE HEART OF THE FORECAST AREA. THIS WAVE AND ANY UPR LVL SUPPORT FROM AN ASSOCIATED DISTURBANCE OR MCV SHOULD PROVIDE THE BEST CHANCE FOR SHOWERS AND STORMS ALONG AND SOUTHEAST OF THE LOW. HAVE HIGHEST POPS MAINLY FOR POINTS ALONG AND SOUTHEAST OF INTERSTATE 71 WITH THE DIURNAL CYCLE PLAYING A ROLE IN TERMS OF BEST COVERAGE. LOOKS LIKE WAVE MOVES OFF TO THE NORTHEAST THURSDAY NIGHT...WHICH SHOULD RESULT IN A DOWN TICK IN SHOWER/THUNDERSTORMS COVERAGE IN ITS WAKE. THE AIRMASS WILL BE QUITE MOIST ALONG AND AHEAD OF THE FRONT WITH PWATS OF 2 INCHES PLUS EXPECTED. IN ADDITION...WARM CLOUD DEPTHS WILL BE CLOSE TO 4 KM WHICH WOULD FAVOR COLLISION/COALESCENCE PROCESSES AND THE POTENTIAL FOR HEAVY RAIN. GIVEN THE UNCERTAINTY IN PLACEMENT OF HEAVIEST RAIN WITH UPCOMING ROUNDS OF SHOWERS AND STORMS...WILL CONTINUE TO HIGHLIGHT THE HEAVY RAIN THREAT/LOCAL FLOODING ISSUES IN THE HWO WITH AN EMPHASIS PLACED ACRS THE SRN CWFA CLOSER TO THE FRONTAL BOUNDARY. HIGHS ON THURSDAY SHOULD BE HELD DOWN BY CLOUDS AND PCPN...WITH LOWER TO MID 80S EXPECTED. LOWS THURSDAY NIGHT WILL RANGE FROM THE MID 60S NW TO THE LOWER 70S SOUTH. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... MAIN FOCUS FOR THE FIRST PART OF THE EXTENDED PERIOD WILL BE A SURFACE FRONTAL BOUNDARY THAT WILL ORIENT ITSELF ALONG THE OHIO RIVER FRIDAY MORNING. WITH ZONAL FLOW ALOFT...THIS BOUNDARY WILL VERY SLOWLY SAG SOUTHWARD THROUGH THE WEEKEND. ONE WAVE OF LOW PRESSURE RIDING ALONG THE FRONT WILL BE EXITING TO THE NORTHEAST AT THE START OF THE PERIOD...ONLY TO BE FOLLOWED BY ANOTHER RIPPLE FRIDAY NIGHT INTO SATURDAY. SOUTHERN PORTIONS OF THE FA WILL SEE THE GREATEST CHANCE FOR RAIN THROUGH THE WEEKEND AND LATEST DETERMINISTIC RUNS CONTINUE TO INDICATE PW VALUES IN THE 150 TO 175 PERCENT OF NORMAL RANGE THERE THROUGH FRIDAY NIGHT. WITH SEVERAL ROUNDS OF SHOWERS AND STORMS IN THE FORECAST...WILL CONTINUE TO MONITOR THE POSSIBILITY OF SOME LOCALIZED FLOODING ACROSS THE SOUTH. THE 12Z GFS AND ECMWF HAVE BOTH NUDGED QPF A TAD FURTHER SOUTH FOR SATURDAY AND SUNDAY THAN THEY HAD IN EARLIER RUNS...SO OPTED TO LOWER OR TAKE OUT POPS ACROSS THE NORTHERN HALF OF THE FA THROUGH THE WEEKEND. KEPT CHANCE POPS IN ACROSS THE SOUTH WHILE THE FRONT LINGERS NEAR THE OHIO RIVER. BY MONDAY A MID LEVEL TROUGH OVER EASTERN CANADA WILL BEGIN TO AMPLIFY...RESULTING IN NW FLOW OVER THE OHIO VALLEY BY THE MIDDLE OF NEXT WEEK. MEANWHILE SURFACE HIGH PRESSURE WILL BUILD OVER THE GREAT LAKES WHICH SHOULD PROVIDE A PERIOD OF DRIER WEATHER FOR TUESDAY AND WEDNESDAY. TEMPERATURES THROUGH THE PERIOD WILL REMAIN A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE UPPER 70S TO LOWER 80S. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SLOW MOVING COLD FRONT MOVING INTO NW OHIO WILL SLIP INTO CENTRAL OHIO THIS AFTERNOON AND STALL OUT NEAR THE OHIO RIVER TONIGHT. SCATTERED STORMS WERE DEVELOPING AHD OF THIS FRONT ACRS PORTIONS OF CENTRAL AND SRN OHIO WHERE BLYR CAPE WERE APPROACHING 1000 J/KG. HAVE TEMPO MENTION OF STORMS WITH MVFR CONDITIONS AT KDAY/KCMH AND KLCK WHERE COVERAGE LOOKS BEST. FOG AND STRATUS IS EXPECTED AGAIN EARLY THIS MORNING IN MOIST ENVIRONMENT. IFR CIGS/VSBYS ARE POSSIBLE IN ANY LOCATION BUT MORE LIKELY AT KCVG/KLUK AND KILN. GENERALLY EXPECT CONDITIONS LIFTING TO MVFR AFTER SUNRISE. THUNDERSTORM CHANCES CONTINUE TO INCREASE WITH THE FRONT SLIPPING A LTL FURTHER SOUTH AND BLYR LAYER CAPES OF 1200-1800 J/KG DURG THE AFTN. HAVE MENTION OF VCTS AND THEN PLACED PREVAILING PRECIP IN THE TIME FRAME WHEN THREAT APPEARS BEST. HOWEVER...UNCERTAINTY EXISTS REGARDING TIMING AND PLACEMENT DUE TO MODEL SOLN DIFFERENCES REGARDING FRONTAL MOVEMENT. GIVEN WESTERLY UPPER LEVEL FLOW WHICH BACKS SLIGHTLY TONIGHT...PREFER SLOWER MOVEMENT MORE LIKE THE GFS/ECMWF SOLNS WITH THE NAM APPEARING TO BE TOO FAST. OUTLOOK...THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE AT TIMES THROUGH FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...FRANKS/HICKMAN SHORT TERM...HICKMAN LONG TERM...KURZ AVIATION...AR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
315 AM EDT THU AUG 8 2013 .SYNOPSIS... MOIST HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH SATURDAY. A WEAK COLD FRONT ARRIVE FROM THE NORTH SUNDAY. THIS FRONT WILL SLOWLY CROSS THE AREA THROUGH TUESDAY...BEFORE MOVING SOUTH OF THE AREA ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... THE LATEST GSP-WSR88D WIND PROFILER DATA SHOW NORTHERLY FLOW BETWEEN 9-13 KFT. WHILE AT THE TCLT TDWR THE FLOW AT THIS LEVEL IS OUT OF THE WSW. THE TROUGH IS ALSO EVIDENT IN THE REFLECTIVITIES AS PATCHY LIGHT SHOWERS ARE MOVING OUT OF THE NORTH OVER THE CENTRAL PART OF THE UPSTATE...BUT THEY ARE MOVING FROM THE SOUTH OVER TOWARD UNION AND GAFFNEY. WHILE THIS IS A WEAK FEATURE IT MAY BE ENOUGH TO FINALLY KEEP IT DRY THROUGH SUNRISE ON THE BACK SIDE OF THE TROUGH ACROSS THE BLUE RIDGE. A COUPLE CONVECTION ALLOWING MODELS FIRE UP HEAVIER SHOWERS AND STORMS EAST OF THE TROUGH AXIS PRIOR TO SUNRISE HOWEVER. I/M NOT CERTAIN THAT THIS WON/T HAPPEN...BUT I DOUBT IT AT THIS POINT. LATER IN THE MORNING THE NAM AND RUC DEVELOP CONVECTION BACK ACROSS THE BLUE RIDGE AS A STRONGER MID-TROPOSPHERIC TROUGH APPROACHES. THIS FEATURE IS CURRENTLY EVIDENT ON THE RUC...AND MODESTLY EVIDENT ON WATER VAPOR IMAGERY...OVER MIDDLE TN AND SW KY. THE SHORT WAVE IS EXPECTED TO TRIGGER NUMEROUS SHOWERS AND TSTMS OVER MOUNTAINS AND FOOTHILLS TODAY. EVEN THE PIEDMONT MIGHT GET INTO THE ACT AS THE LLVL FLOW IS A LITTLE MORE SOUTHWESTERLY TODAY. AS SEVERAL INCHES OF RAIN HAS FALLEN OVER PARTS OF NE GA...UPSTATE SC AND THE SRN MTNS OF NC OVER THE PAST 3 DAYS...I/VE ISSUED A FLASH FLOOD WATCH FOR THIS AREA. I DID NOT TAKE IT ACROSS NRN MTNS...NRN FOOTHILLS OR THE WRN NC/SC PIEDMONT AS ANTECEDENT CONDITIONS ARE DRIER. I HOPE I DON/T REGRET THIS...BUT THE NEIGHBORING OFFICES ARE IN AGREEMENT ON THIS APPROACH AS WELL. OVERNIGHT THE AREA OF MID-LEVEL TROUGHING STRENGTHENS JUST A LITTLE WITH SOUTHWESTERLY H5 WINDS INCREASING TO 25 KTS OVER THE WRN ZONES ALONG WITH A COMMISERATE RESPONSE AND BACKING IN THE LLVL WIND FIELD. THIS MAY SET THE STAGE FOR CONVECTION TO LAST A WAYS INTO THE OVERNIGHT HOURS...OR EVEN REDEVELOP AT SOME POINT DURING THE THE NIGHT. THE FLASH FLOOD WATCH WILL BE RUN THROUGH 6 AM FRIDAY TO ACCOUNT FOR THIS. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AT 230 AM EDT THURSDAY...AN UPPER RIDGE WILL EXTEND ACROSS THE SOUTHEAST STATES ON FRIDAY...WHILE A CLOSED UPPER LOW CROSSES SOUTH CENTRAL CANADA AND AN EASTERLY WAVE MOVES INTO THE SOUTHEAST GULF OF MEXICO. THE RIDGE PERSISTS INTO SATURDAY...WHILE THE UPPER LOW REACHES EASTERN CANADA...AND THE EASTERLY WAVE REACHES THE WESTERN GULF. AN ATLANTIC SURFACE RIDGE WILL MAINTAIN A HOLD ON THE CAROLINAS AND GA ON FRIDAY...WHILE A RIVER OF GULF MOISTURE WILL EXTEND TO THE SOUTHERN APPALACHIANS. ISENTROPIC UPGLIDE OVER THE RIDGE WILL BE RATHER WEAK...AND UPSLOPE FLOW LIMITED BY THE SOUTHWESTERLY NATURE OF THE WINDS. THE RIVER OF GULF MOISTURE BECOMES REORIENTED ON SATURDAY AS THE EASTERLY WAVE AFFECTS THE GULF INFLOW...AND LOW LEVEL WINDS VEER TO THE WEST...FAVORING THE TN BORDER FOR PRECIPITATION. MEANWHILE...A SLOW MOVING COLD FRONT WILL OUT OF THE OH RIVER VALLEY...APPROACHING OUR AREA FROM THE NORTH ON SUNDAY NIGHT. WITH DEEP MOISTURE REMAINING OVER OUR AREA...POPS WILL BE ABOVE CLIMATOLOGY...AND WILL CONTINUE OVERNIGHT...DESPITE THE LACK OF WELL DEFINED FORCING. ALTHOUGH QPF WILL BE LIMITED...ESPECIALLY AS FLOW VEERS SATURDAY...THE LONG DURATION OF THE EVENT COULD PRODUCE RUNOFF PROBLEMS IN AREAS THAT HAD GREATER RAINFALL EARLIER ON. A LIMITED DIURNAL TEMPERATURE RANGE IS EXPECTED TO CONTINUE...WITH CLOUDS KEEPING MAXIMUMS SLIGHTLY BELOW NORMAL...AND MINIMUMS SLIGHTLY ABOVE NORMAL. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AT 230 AM EDT THURSDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST COAST FROM SUNDAY THROUGH WEDNESDAY. A COLD FRONT WILL DROP VERY SLOWLY SOUTH INTO THE NORTHERN PORTION OF THE AREA ON SUNDAY... CROSSING MUCH OF WESTERN NC ON MONDAY...THE INTERSTATE 85 CORRIDOR TUESDAY...AND FINALLY MOVING SOUTH OF THE AREA ON WEDNESDAY. ALTHOUGH THIS BOUNDARY WILL SERVE AS A FOCUSING MECHANISM FOR PRECIPITATION...SOUTHERLY INFLOW AHEAD OF THE FRONT IS EXPECTED TO DECREASE BASED ON A REORIENTATION OF THE SURFACE RIDGE TO THE SOUTH. UPSLOPE WILL BE LIMITED TO THE TN BORDER AREA TO BEGIN WITH AS LOW LEVEL WINDS WILL BE WESTERLY...AND WILL DIMINISH IN THE LEE OF THE MOUNTAINS AS THE FRONT SETTLES SOUTH AND WINDS VEER MORE TO THE NORTHWEST. POPS WILL REMAIN ABOVE CLIMATOLOGY...AND WITH SOME UNCERTAINTY AS TO THE TIMING OF THE FRONT...POPS WILL BE ALLOWED TO REMAIN INTO WEDNESDAY. TEMPERATURES WILL DECREASE AS HEIGHTS FALL ALOFT...BUT THE DIURNAL RANGE WILL REMAIN LIMITED DUE TO CLOUDS AND MOISTURE. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... AT KCLT...A SOLID DECK OF MID LEVEL CLOUDS HAS DEVELOPED UP AROUND 140KFT. THERE ARE A COUPLE OTHER LOWER DECKS AS WELL. SOME LIGHT RAIN IS FALLING OUT OF SOME OF THESE CLOUDS. EXPECT IFR STRATUS TO DEVELOP...BUT IT SHOULD TAKE A WHILE WITH ALL THE HIGHER LEVEL CLOUDS. ALSO...A COUPLE COMPUTER MODELS DEVELOP THUNDERSTORMS AND HEAVY RAIN STARTING IN A COUPLE HOURS. THERE HAS BEEN PLENTY OF OVERNIGHT THUNDERSTORM ACTIVITY LATELY SO I/M NOT COMPLETELY DISREGARDING THIS...BUT I HAVEN/T INCLUDED THAT IN THE TAFS. STRATUS WILL SLOWLY BURN OFF DURING THE MORNING HOURS. SCT SHRA AND TSTMS ARE EXPECTED IN THE AFTN...THOUGH CHANCES WILL CONTINUE TO BE HIGHER A LITTLE CLOSER TO THE MOUNTAINS. ELSEWHERE...SEVERAL DIFFERENT CLOUD LAYERS COVER THE REGION EARLY THIS MORNING. THERE IS A DECK UP AROUND 140KFT AND SEVERAL LOWER ONES AS WELL. HOWEVER...MOST OF THESE CLOUDS ARE IN THE VFR RANGE. WITH A VERY MOIST ATMOSPHERE AND LIGHT SW WINDS WE SHOULD SEE IFR STRATUS DEVELOP...THOUGH IT MAY BE PATCHY CONSIDERING THE HIGH CLOUD COVER. I HAVE ACCOUNTED FOR THIS WITH A LONG PERIOD OF TEMPO GROUPS. THE EXCEPTION MAY BE KAVL WHERE LIFR CIGS HAVE ALREADY DEVELOPED. CLOUDS ARE NOT AS THICK OVER HKY WHICH WILL GIVE THEM A BETTER CHANCE OF A SOLID IFR STRATUS DECK AND SOME FOG. SHRA AND EVEN A FEW TSMTS MAY DEVELOP OVER THE REGION IN A FEW HOURS. BETTER CHANCES WILL BE FOUND THIS AFTERNOON...UNLESS THE CONVECTION SIMPLY KEEPS GOING TROUGH THE MORNING HOURS LIKE IT DID YDAY. OUTLOOK...MOISTURE AND INSTABILITY CONTINUE THROUGH THE WEEKEND... LEADING TO CONTINUED CHANCES FOR MAINLY DIURNAL CONVECTION. EARLY MORNING PATCHY FOG AND LOW CLOUDS MAY OCCUR OVER AREAS OF RECENT RAINFALL AND IN MTN VALLEYS. CONFIDENCE TABLE... 07-13Z 13-19Z 19-01Z 01-07Z KCLT HIGH 81% MED 74% HIGH 91% HIGH 100% KGSP MED 76% MED 79% HIGH 85% HIGH 83% KAVL HIGH 86% HIGH 83% HIGH 85% HIGH 80% KHKY LOW 46% MED 79% MED 77% MED 78% KGMU MED 71% MED 76% HIGH 87% HIGH 83% KAND LOW 58% MED 69% HIGH 90% 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...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR GAZ010-017-018-026- 028-029. NC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ062>065-509-510. SC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR SCZ001>007-010>012- 019. && $$ SYNOPSIS...JAT NEAR TERM...MCAVOY SHORT TERM...JAT LONG TERM...JAT AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1145 PM CDT WED AUG 7 2013 .UPDATE... UPDATED FOR 06Z AVIATION DISCUSSION. && .PREV DISCUSSION... /ISSUED 740 PM CDT WED AUG 7 2013/ UPDATE... DIFFICULT TO GET A HANDLE ON EXACTLY WHERE ANY SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS EVENING WITH MANY OF THE MODELS BEING POOR IN HANDLING THE CURRENT SITUATION. A WEAK WARM EXTENDS FROM NORTHEAST AR INTO SOUTHWEST TN AT EARLY EVENING. A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG THE TN RIVER IN WEST TN JUST NORTH OF THIS FRONT. THE HIGH RESOLUTION RAPID REFRESH MODEL SEEMS TO BE DOING THE BEST JOB...AND THIS MODEL INDICATE FURTHER DEVELOPMENT THIS EVENING NORTH OF THE FRONT ACROSS PORTIONS OF NORTHEAST AR...THE MO BOOTHEEL...AND PORTIONS OF WEST TN. UPDATED TO REMOVE MENTION OF RAIN THIS EVENING SOUTH OF THIS AREA. ALSO ADJUSTED THE SKY COVER A LITTLE FOR THIS EVENING...OTHERWISE LITTLE CHANGE MADE TO THE EARLIER FORECAST. JCL && .PREV DISCUSSION... /ISSUED 312 PM CDT WED AUG 7 2013/ THE OUTFLOW BOUNDARY GENERATED FROM THIS MORNINGS MCS CONTINUES TO PUSH ACROSS NORTHERN MISSISSIPPI. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG AND IN ADVANCE OF THE BOUNDARY AND WILL CONTINUE TO PUSH ACROSS THE REMAINDER OF NORTH MISSISSIPPI OVER THE NEXT COUPLE OF HOURS. THESE STORMS COULD BE STRONG WITH GUSTY WINDS AND HEAVY RAIN. THE BOUNDARY HAS LIMITED HIGH TEMPS ACROSS THE DELTA THOUGH THE SOUTHERN MOST COUNTIES...FROM TALLAHATCHIE TO MONROE...HAVE WARMED INTO THE MID 90S WITH HEAT INDEX VALUES FLIRTING WITH 105 DEGREES. THE REMNANTS OF THE COLD POOL HAVE RESULTED IN A RELATIVELY NICE DAY ACROSS MUCH OF EASTERN AR...THE MO BOOTHEEL AND WEST TENNESSEE WHERE TEMPS ARE MOSTLY IN THE 80S TO AROUND 90. THE AIRMASS STILL QUITE STABLE AND PRECIP FREE. TONIGHT...LOOKING AT A FAIRLY QUIET EVENING GIVEN THE WORKED OVER AIRMASS IN PLACE. WENT WITH A 20 POP OVER MOST OF THE AREA AND A 30 POP OVER NE ARKANSAS WHERE THE HRRR IS HINTING AT SOME DEVELOPMENT BEFORE MIDNIGHT. LOOKING AT ANOTHER POTENTIAL MCS SCENARIO LATER TONIGHT AS THE LOW LEVEL JET REDEVELOPS OVER EASTERN OK AND WESTERN AR AND IMPINGES UPON THE WEAK STATIONARY FRONT ACROSS THE AREA. THIS FRONT HAS BEEN HAVING TROUBLE LIFTING NORTH OVER THE LAST COUPLE OF DAYS THANKS TO THE RECENT MCS ACTIVITY AND ASSOCD COLD POOLS. AN AREA OF SHOWERS AND THUNDERSTORMS SHOULD BLOSSOM OVER SRN MISSOURI AFTER MIDNIGHT AND THEN HEAD ESE AND SKIRT THE NORTHERN TIER OF THE MIDSOUTH BY MORNING. POPS WILL DECREASE SHARPLY TOWARD SOUTHERN AREAS OF THE MIDSOUTH. ANOTHER MILD NIGHT ON TAP WITH LOWS IN THE MID 70S. THURSDAY...EXPECT THE MCS TO SKIRT THE NORTHERN TIER AND WEAKEN AS IT SPREADS EAST. BEST CHANCE WILL BE ACROSS NORTHERN AND EASTERN SECTION WITH LESSER CHANCES TOWARD THE SOUTHWEST. MEX GUIDANCE CONTINUES TO BE VERY WARM AND WENT CLOSER TO THE COOLER MET GUIDANCE. EXPECT THAT ANOTHER OUTFLOW BOUNDARY MAY PUSH SOUTH WHICH WILL HELP KEEP A LID ON TEMPS. AREAS SOUTHWEST OF MEMPHIS ARE LIKELY TO GET THE WARMEST AND COULD FLIRT WITH HEAT ADVISORY CRITERIA. THURSDAY NIGHT THROUGH FRIDAY NIGHT...PATTERN REMAINS SIMILAR WITH A BROAD UPPER RIDGE ACROSS THE SOUTHERN U.S AND A WEAK STATIONARY FRONT ACROSS SOUTHERN MISSOURI. EXPECT MCS DEVELOPMENT ALONG THIS FRONT EACH NIGHT WITH THE BEST CHANCES OF PRECIP ALONG THE NORTHERN TIER OF THE MIDSOUTH. CONTINUED TO PREFER THE COOLER MET GUIDANCE THOUGH PARTS OF NORTH MISSISSIPPI AND EAST CENTRAL ARKANSAS WILL FLIRT WITH HEAT ADVISORY CRITERIA ON FRIDAY. SATURDAY THROUGH SUNDAY...CONFIDENCE STARTING TO WANE AT THIS POINT. UPPER RIDGE REMAINS ACROSS THE SOUTHERN U.S. WHILE THE WEAK BOUNDARY TRIES TO SLIP SOUTH INTO THE MIDSOUTH BUT REALLY DOES NOT MOVE MUCH. CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE REGION. MEX STILL TOO WARM. MONDAY THROUGH WEDNESDAY...MEDIUM RANGE MODELS INDICATE THAT AN UPPER TROF WILL DEVELOP OVER THE EASTERN U.S. EARLY NEXT WEEK. THE GFS IS NOT AS DEEP WITH THE TROF WHICH REESTABLISHES NORTHWEST FLOW ACROSS THE REGION AND KEEPS THE SURFACE BOUNDARY IN THE AREA RESULTING IN A RENEWED MCS PATTERN. THE ECMWF HAS A DEEPER TROF AND ACTUALLY PUSHES THE FRONT SOUTH...SHUTTING OFF PRECIP CHANCES. FOR NOW JUST WENT WITH A COMPROMISE OF 20 POPS AND SLIGHTLY COOLER THAN NORMAL TEMPS. SJM && .AVIATION... 06Z TAF CYCLE GROWING CONFIDENCE THAT THIS TAF PERIOD WILL BECOME A BIT MORE ACTIVE THEN PREVIOUS 00Z THINKING...WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPING IN THE MEM...JBR...MKL CORRIDOR BEFORE SUNRISE WITH MVFR VISIBILITIES AT TIMES. BETTER CHANCES FOR THUNDER WILL BE LATER IN THE DAY AS THE CURRENT DISTURBANCE IN THE SOUTHERN PLAINS MOVES ACROSS THE OZARKS. FOR NOW...PLACED TEMPO IN AT JBR...AND VCTS ELSEWHERE...BUT TIMING/COVERAGE COULD EASILY CHANGE WITH LATER FORECASTS. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT...WITH THE EXCEPTION OF SOUTH WINDS AT MEM. OUTFLOW BOUNDARY FROM MORNING COMPLEX WILL SHIFT THE WINDS MORE EASTERLY AT 6-8 KTS FOR MEM...MKL AND JBR...WHILE TUP REMAINS SOUTH. WINDS WILL AGAIN BECOME LIGHT FROM THE EAST AND SUTHEAST NEAR SUNSET. JAB && .PRELIMINARY POINT TEMPS/POPS... MEM 77 93 78 94 / 30 30 10 30 MKL 73 88 74 91 / 50 60 30 40 JBR 75 90 75 92 / 50 40 30 40 TUP 75 93 75 93 / 20 40 10 40 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1030 AM EDT THU AUG 8 2013 .SYNOPSIS... SHOWERS AND HUMIDITY WILL INCREASE TODAY AS A WEAK WARM FRONT MOVES NORTH OF THE REGION. A COLD FRONT WILL SHIFT SLOWLY INTO NEW ENGLAND THURSDAY AND FRIDAY BRINGING SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY RAINFALL. THIS FRONT WILL FINALLY PUSH OFF THE COAST SATURDAY. HIGH PRESSURE BUILDS OVER THE REGION SUNDAY AND MONDAY. ANOTHER COLD FRONT BRINGS SHOWERS ON TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1030 AM UPDATE... MORNING ACTIVITY LOCALIZED ALONG THE H85 DEWPOINT GRADIENT AND ATTENDANT LOW- TO MID-LEVEL WARM FRONT PRESSING EAST THRU THE GULF OF MAINE DRAPING SOUTHWESTWARD TOWARDS NANTUCKET. AS SEEN PER WSR-88D RETURNS...RAIN DIMINISHING ACROSS THE SOUTHEAST OUTER WATERS. WILL CONTINUE CHANCE POPS ALONG THE DEWPOINT GRADIENT THRU THE DAY WITH SLIGHT CHANCE POPS EAST OF THERE WITHIN THE MORE DRIER AIR. FOCUSING BACK ON THE INTERIOR...ENTRENCHING INTO THE WARM-MOIST SECTOR AS THE SURFACE WARM FRONT ACROSS THE NORTHERN HUDSON RIVER VALLEY DRAPED SOUTH THROUGH WESTERN AND CENTRAL PORTIONS OF NEW ENGLAND SLOWLY PUSHES EAST AGAINST OFFSHORE HIGH PRESSURE AND DRIER AIR. MODEST SURFACE-H85 SOUTHWEST MOISTURE TRANSPORT PUSHING UPPER 60S INTO 70S DEWPOINTS INTO NEW ENGLAND /RETURN OF MUGGY CONDITION/ RESULTING IN PWATS GETTING UP TO 2 INCHES. SO WE HAVE THE MOISTURE...NOW ITS A QUESTION OF DESTABILIZATION. BUT A CAVEAT. 12Z ALBANY SOUNDING AND RAP MESOANALYSIS SHOWS A DRY POCKET OF AIR ACROSS THE CENTRAL TO LOWER HUDSON RIVER VALLEY. EARLIER LINE OF STORMS ACROSS UPSTATE NY INTO NORTHERN PA HAS RUN INTO THIS AIRMASS AND DIMINISHED ENTIRELY. RAP FORECAST GUIDANCE HAS THIS AIRMASS MOVING EAST INTO NEW ENGLAND DURING THE DAY RESULTING IN THE POSSIBILITY OF LITTLE TO NO ACTIVITY. ADDITIONAL GUIDANCE IS FAIRLY QUIET AS WELL WITH THE WRF-ARW THE MOST ROBUST. CONSIDERING THE 12Z SOUNDING OUT OF BUFFALO WHICH LOOKS MORE FAVORABLE FOR THUNDERSTORM DEVELOPMENT...FEEL THIS AIRMASS WILL PUSH EAST INTO THE HUDSON VALLEY DURING THE DAY. FACTORING IN SUNSHINE AND A DESTABILIZING BOUNDARY LAYER...EXPECT MLCAPE INSTABILITY UP TO 2K J/KG SHOULD BE UTILIZED. USING A THRESHOLD OF SURFACE LIFTED INDICES OF -4C...HAVE DEFINED WHERE THERE IS A BETTER CHANCE OF THUNDERSTORMS WHICH IS MAINLY ACROSS WESTERN AND CENTRAL PORTIONS OF NEW ENGLAND. WILL KEEP POPS AT CHANCE. WILL NOT MENTION ANY THREATS TILL ACTIVITY DEVELOPS DUE TO CONTINUED UNCERTAINTY. MID-LEVEL LAPSE RATES ARE POOR. BULK SHEAR IS WEAK WHILE UNI-DIRECTIONAL. SO ANY THREATS LOOK TO BE POSSIBLE WIND DAMAGE WITH HEAVY RAIN AND NUISANCE FLOODING. HAVE A FEELING TODAY MAY NOT MATERIALIZE INTO MUCH THAN SCATTERED ACTIVITY WEST THAT REMAINS FAIRLY WEAK. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... TONIGHT AND FRIDAY... SEVERAL MEMBERS OF THE MODEL SUITE...NAMELY THE 00Z GFS AND 12Z ECMWF ALONG WITH THEIR ENSEMBLES APPEAR TO HAVE A GOOD HANDLE ON THE EVOLUTION OF THE SLOW MOVING COLD FRONT ACROSS THE REGION. H5 WINDS WITH THE UPPER TROUGH BACK TO SW...WHICH WILL ALLOW DEEP MOISTURE PLUME TO MOVE ACROSS THE REGION. EXPECT SHOWERS AND THUNDERSTORMS TO PRODUCE LOCALLY HEAVY RAINFALL DURING THIS TIMEFRAME. MORE DETAILS IN THE HYDRO SECTION BELOW. FRIDAY COULD BE INTERESTING WITH SOME OF THE THUNDERSTORMS. MIXED LAYER CAPE VALUES FORECAST TO 1000-1500 J/KG DURING THE AFTERNOON AHEAD OF THE FRONT...ALONG WITH A WEAK MID LEVEL DISTURBANCE MOVING ACROSS THE REGION. ALSO FAIRLY GOOD SHEAR IN PLACE WITH SW WINDS AROUND 30 KT. THIS MAY PRODUCE SOME LOCALLY GUSTY WINDS IN ANY STRONGER THUNDERSTORMS. WILL NEED TO MONITOR THIS FOR POSSIBILITY OF LOCALLY DAMAGING WINDS. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... BIG PICTURE/PREFERENCES... SUBTROPICAL RIDGE HOLDS ACROSS THE SOUTHERN USA AND BUILDS OVER THE ROCKIES INTO WESTERN CANADA. CLOSED UPPER LOW EJECTS THROUGH EASTERN CANADA FRIDAY-SATURDAY. A SHORTWAVE FROM THE CANADIAN ARCTIC THEN DROPS SOUTH THROUGH HUDSON BAY...MAINTAINING AND POSSIBLY DEEPENING THE UPPER TROUGH OVER EASTERN CANADA/NORTHEAST USA DURING THE FIRST HALF OF NEXT WEEK. THERMAL FIELDS SHOW COOLING ALOFT OVER THE WEEKEND AND EARLY NEXT WEEK. THE ECMWF SHOWS A COUPLE OF DEGREES MORE COOLING THAN THE GFS. OUR MAIN PREFERENCE WAS HPC/WPC GRIDS WHERE AVAILABLE...A BLEND OF GFS/ECMWF GRIDS OTHERWISE. THE DAILIES... FRIDAY NIGHT-SATURDAY... A COLD FRONT MOVES THROUGH THE REGION OVERNIGHT. THIS IS DRIVEN BY THE UPPER LOW PASSING NORTH OF NEW ENGLAND. THERE IS SOME VARIATION IN THE PLACEMENT OF THE COLD FRONT FRIDAY EVENING...BUT THE 00Z ECMWF AND GENERAL CONSENSUS CENTER ON THE HUDSON VALLEY. SUFFICIENT LIFT/INSTABILITY AND PRECIPITABLE WATER VALUES 2 INCHES OR HIGHER ALL POINT TO SHOWERS/TSTMS LEADING THE FRONT. COVERAGE MAY NOT BE 100 PERCENT AS IS NORMAL FOR SHOWERS...BUT STRONG CONFIDENCE IN OCCURRENCE. DEEP MOISTURE/HIGH PW VALUES SUGGEST HEAVY DOWNPOURS WITH POTENTIAL FOR URBAN/POOR DRAINAGE FLOODING. A FLASH FLOOD WATCH MAY BE NEEDED IN THE NEAR FUTURE TO COVER THIS PRE-FRONTAL WEATHER. THE COLD FRONT SWEEPS ACROSS SOUTHERN NEW ENGLAND DURING THE NIGHT WITH SHOWERS TAPERING OFF WITH FRONTAL PASSAGE AND THE WIND SHIFT TO NORTHWEST. HIGH DEWPOINTS IN THE EVENING...BUT LOWERING AFTER FROPA OVERNIGHT. COULD BE SOME LINGERING CLOUDS/SHOWERS ALONG THE EAST AND SOUTH COASTS SATURDAY MORNING BUT THE OVERALL TREND WILL BE FOR CLEARING AND DIMINISHING HUMIDITY. MIXING SHOULD REACH TO AT LEAST 850 MB AND POSSIBLY HIGHER. TEMPS AT THE TOP OF THE MIXED LAYER SHOULD REACH 12-15C...WHICH WOULD ALLOW MAX TEMPS IN THE LOW TO MID 80S. A MILD START COULD ADD A COUPLE OF DEGREES TO THE HIGH SIDE OF THIS RANGE. WINDS AT THE TOP OF THIS MIXED LAYER WILL REACH AROUND 20 KNOTS...SO WE ARE FORECASTING A POTENTIAL FOR AFTERNOON GUSTS 20-25 MPH. SUNDAY-MONDAY... HIGH PRESSURE BUILDS OVER THE EAST AND SHOULD PROVIDE DRY SEASONABLE WEATHER BOTH DAYS. SHORTWAVE MOVING ALONG THE CANADIAN BORDER MAY BRING SOME COOLING ALOFT SUNDAY AND DESTABILIZE THE AIRMASS FOR SOME DIURNAL CUMULUS. DEWPOINTS IN THE 50S AND LIGHT WINDS WILL ALLOW EARLY MORNING LOWS IN THE 50S AND LOWER 60S EACH DAY. TEMPS AT THE TOP OF THE MIXED LAYER WILL SUPPORT MAX TEMPS AROUND 80 SUNDAY AND 80-85 MONDAY. IF MIXING GOES A LITTLE DEEPER THAN FORECAST THEN WE MAY GET A COUPLE OF DEGREES WARMER. TUESDAY... SHORTWAVE DROPPING SOUTH TO THE GREAT LAKES MONDAY WILL SWING EAST AND DRIVE PAST NORTHERN NEW ENGLAND TUESDAY. THIS WILL BRING A COLD FRONT THROUGH THE REGION WHICH MAY GENERATE A FEW SHOWERS/TSTMS. PW VALUES CLIMB ABOVE 1.5 INCHES WITH THE 2 INCH CONTOUR LURKING JUST TO OUR SOUTH. SO HEAVY DOWNPOURS MAY AGAIN BE A CONCERN. WEDNESDAY... THE NEXT HIGH PRESSURE AREA MOVES IN WITH DRY SEASONABLE AIR. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW THROUGH FRIDAY...HIGH CONFIDENCE IN TRENDS...LOW CONFIDENCE IN TIMING. TODAY...EXPECT MVFR-IFR CIGS ACROSS MOST AREAS WHICH SHOULD IMPROVE TO VFR BY AFTERNOON. VSBYS MAINLY VFR...THOUGH WILL SEE LOCAL MVFR-IFR VSBYS IN SHOWERS AND ISOLD TSTMS OFF AND ON THROUGH THE DAY. TONIGHT AND FRIDAY...EXPECT CIGS/VSBYS TO LOWER TO MVFR-IFR IN LOW CLOUDS...PATCHY FOG AND SHOWERS/TSTMS. WILL SEE LOCALLY HEAVY RAINFALL WHICH WILL ALSO LOWER VSBYS. MAY SEE SLOWLY IMPROVING CONDITIONS LATE FRIDAY ACROSS SW NH/W MA...DEPENDING UPON THE TIMING OF THE COLD FRONT. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS...LOW CONFIDENCE IN TIMING. KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS...LOW CONFIDENCE IN TIMING. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT... LOW CIGS AND POOR VSBYS IN SHOWERS/TSTMS AND AREAS OF FOG. LOCALLY HEAVY DOWNPOURS ARE EXPECTED WITH POTENTIAL FOR POOR DRAINAGE FLOODING. THE COLD FRONT SHOULD CROSS THE CT VALLEY AROUND OR JUST AFTER SUNSET...AND REACH THE COASTAL AREAS AROUND MIDNIGHT OR A LITTLE LATER. EXPECT SHOWERS TO TAPER OFF AFTER THE FRONT MOVES THROUGH. LOCALLY LOW CIGS/VSBY POSSIBLE OVERNIGHT IN FOG. SATURDAY-SUNDAY-MONDAY... VFR THROUGH THE PERIOD. NORTHWEST WINDS SATURDAY MAY GUST TO 25 KNOTS DURING THE AFTERNOON AS DAYTIME HEATING DRAWS THE STRONGER WINDS LOWER FROM HIGH ALTITUDES. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY THROUGH FRIDAY...HIGH CONFIDENCE. TODAY AND TONIGHT...EXPECT S WINDS TO PICK UP DURING THE DAY WITH AN INCREASING S SWELL. WINDS AND SEAS REMAIN BELOW SMALL CRAFT CRITERIA. SHOWERS/SCT TSTMS EXPECTED WITH REDUCED VSBYS. MAY SEE HEAVY DOWNPOURS IN SOME SHOWERS AND STORMS TONIGHT. PATCHY FOG DEVELOPS TONIGHT WITH VSBYS 1-3NM. FRIDAY...SW WINDS PICK UP DURING THE LATE MORNING AND AFTERNOON... GUSTING TO 25 KT ON THE OPEN WATERS. SEAS ALSO INCREASE...UP TO 5-6 FT...HIGHEST ON THE SOUTHERN OUTER WATERS. DECIDED TO HOLD OFF ON PUTTING SMALL CRAFT UP FOR NOW. WILL SEE SHOWERS/TSTMS WHICH MAY PRODUCE HEAVY DOWNPOURS AND BRIEF GUSTY WINDS. PATCHY FOG AGAIN REDUCING VSBYS. OUTLOOK...FRIDAY NIGHT INTO MONDAY... MODERATE CONFIDENCE. FRIDAY NIGHT... SHOWERS/TSTMS MOVE THROUGH DURING THE FIRST PART OF THE NIGHT. A COLD FRONT WILL MOVE ACROSS THE WATERS LATER IN THE NIGHT WITH SHOWERS ENDING AND WINDS SHIFTING TO NORTHWEST. SEAS WILL REMAIN AROUND 5-6 FEET ON THE EXPOSED WATERS UNTIL THE WIND SHIFT AND THEN DIMINISH. SMALL CRAFT ADVISORY WILL BE LIKELY FOR THESE AREAS. SATURDAY THROUGH MONDAY... WINDS AND SEAS BELOW SMALL CRAFT THRESHOLDS DURING THIS PERIOD. && .HYDROLOGY... INCREASING LOW LEVEL MOISTURE FEED WILL MOVE INTO THE REGION LATE TONIGHT AND FRIDAY ALONG A SLOW MOVING COLD FRONT. THE FRONT MAY STALL FOR A TIME DURING FRIDAY...ALLOWING FOR TRAINING OF PRECIP ACROSS THE REGION. EXPECT PWATS TO INCREASE TO 2 TO 2.25 INCHES LATE TONIGHT AND FRIDAY. THIS...ALONG WITH THE INCREASING MOISTURE CONVERGENCE AND SLOW MOVEMENT OF THE FRONT WILL BRING LOCALLY HEAVY RAINFALL WITH THE SHOWERS/TSTMS AHEAD OF THE FRONT. QPF AMOUNTS FORECAST TO BE A GENERAL 1-2 INCHES...BUT COULD SEE LOCALLY HIGHER AMOUNTS IN HEAVIER PRECIP. HOWEVER...THE LOCATION AND TIMING OF HEAVIEST RAINS REMAINS IN QUESTION. MAIN THREAT WILL BE MINOR URBAN AND POOR DRAINAGE FLOODING...BUT FLASH FLOODING IS POSSIBLE WITH ANY TRAINING CONVECTION. FLASHY SMALL STREAM FLOODING COULD BECOME A CONCERN IF SEVERAL ROUNDS OF CONVECTION OCCUR OVER THE SAME BASINS. THIS ASPECT WILL NEED TO BE MONITORED CLOSELY...AND A FLASH FLOOD WATCH MAY NEED TO BE ISSUED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/EVT NEAR TERM...SIPPRELL SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT HYDROLOGY...WFO BOX STAFF
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1133 AM EDT THU AUG 8 2013 .SYNOPSIS... LOW PRESSURE MOVING ACROSS SOUTHEASTERN CANADA WILL ALLOW A COLD FRONT TO APPROACH THE REGION ON FRIDAY AND CROSS THE AREA BY LATE FRIDAY OR EARLY SATURDAY. THIS FRONT WILL EVENTUALLY STALL TO OUR SOUTH FOR SUNDAY. EARLY NEXT WEEK, A FEW WAVES OF LOW PRESSURE ARE FORECAST TO MOVE ALONG THE STALLED BOUNDARY. HIGH PRESSURE WILL THEN BUILD IN TOWARD MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT A CONFIDENT ESTF UPDATE. WE HAVE DECIDED TO COMPROMISE BETWEEN PREVIOUS FCST AND CURRENT SUGGESTIONS BY THE HRRR AND COSPA. WE ARE SEEING A SHORT WAVE EMERGE FROM WV AND COUPLED WITH CONVECTIVE TEMPERATURES BEING REACHED BELIEVE THIS SHOULD START TRIGGERING AND ENHANCING CONVECTION AS WE MOVE FORWARD. THE PREVIOUS MCS HAS LEFT A RELATIVELY STABLE POOL NW OF OUR CWA FOR NOW. SO THE ADJUSTMENTS GOING FORWARD WERE TO LOWER POPS INITIALLY NORTHWEST AND GIVE THAT SHORT WAVE A BIT MORE CREDIT AND INCREASE POPS IN THE CENTRAL THIRD OF OUR CWA FOR THIS AFTERNOON. WE DID SEE A NOTICEABLE DROP OFF IN 925MB OR 850MB MOISTURE OFF THE WALLOPS SOUNDING THIS MORNING, SO CHANCES WERE KEPT IN THE SERN PART OF OUR CWA. WE ARE WARMING AT 700MB AND 500MB, SO WITH BULK SHEAR VALUES BEST NORTH AS WELL AS FORECAST TT(S), WE KEPT THE SOMEWHAT ENHANCED WORDING TIED TO LIKELY POPS. THE FCST DCAPES ARE NOT IMPRESSIVE AND NEITHER ARE THETA E DROP WITH HEIGHT, SO ANY STRONG TO SEVERE ARE GOING TO HAVE TO BE TIED TO SOME RELATIVELY STRONGER UPDRAFTS OR IF AN EFFECTIVE COOL POOL CAN FORM. THE LATTER DOES NOT LOOK PROMISING. WE HAVE NOT HAD MANY DRY STRETCHES THIS SUMMER, BUT THE RELATIVE LACK OF FLOODING RAINS LAST SEVERAL DAYS HAS PERMITTED FFG AND FFH GUIDANCE TO GET CLOSER TO NORMAL SUMMER VALUES. SO WHILE A FFW MIGHT STILL OCCUR, THIS WOULD SEEM TO BE MORE OF AN ISOLATED OCCURRENCE. 12Z SOUNDINGS GIVE 90F AS A POSSIBLE HIGH SOUTHERN PART OF OUR CWA (CONVECTIVE TEMP LOW 80S), SO BUMPED MAX TEMPS UPWARD IN DELMARVA, KEPT THE REST RELATIVELY THE SAME. UPPER HEIGHTS WILL BE RISING THRU THE DAY AND THERE ARE ONLY WEAK S/W MOVING THRU THE FLOW. BREAKS WILL OCCUR TODAY ALLOWING FOR POCKETS OF HEATING/INSTABILITY TO DEVELOP. WE WILL GO ALONG WITH THE DETERMINISTIC MODELS AND MOS AND MOSTLY KEEP THE HIGHER CHC FOR POPS NORTH MOSTLY THIS AFTERNOON WITH SLGT CHC OR LOW CHC POPS SOUTH/EAST. THERE WILL BE SOME CAPE VALUES AROUND 750-1250 J/KG ACROSS THE AREA...BUT THE HIGHEST VALUES WILL OCCUR WITH ANY BREAKS IN THE CLOUDS TODAY. SPC HAS OUR AREA IN `SEE TEXT` AND MENTIONS ONLY SMALL POSSIBILITY OF SOME STRONGER WIND GUSTS WITH ANY CONVECTION THAT DEVELOPS. QPF BASIN AVERAGES...1/2 INCH NORTH RANGING DOWN TO LIGHT AMTS SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... WE WILL CONTINUE IN THE WARM SECTOR TONIGHT WITH THE UPPER FLOW BECOMING A BIT MORE SWRLY ALOFT. A COLD FRONT WILL BE SLOWING ITS APPROACH INTO WRN NY AND WRN PA. SHOWERS AND SCT THUNDERSTORMS WILL CONTINUE FROM THE LATE AFTERNOON INTO THE EARLY OVERNIGHT PERIODS. THE AREAS NORTH/WEST WILL HAVE THE BETTER CHCS FOR THE RAINS. WE WILL CARRY THE LIKELY POPS INTO THE OVERNIGHT NORTH/WEST AND HOLD THE HIGHER CHC POPS SOUTH/EAST. QPF...1/2 INCH NORTH 1/10 INCH SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AN AREA OF LOW PRESSURE IN SERN CANAD WILL WORK ITS WAY EWD. AS IT DOES A CDFNT WILL CROSS THE AREA FROM W TO E ON FRI INTO FRI NIGHT. THE LATEST MDL GUID CURRENTLY INDICATES THAT THE FRI DAYTIME PD COULD BE FAIRLY WET, FOR AT LEAST A PORTION OF THE AREA, AND THERE COULD BE LOCALIZED CONVECTION WHICH COULD MAKE FOR PDS OF HEAVY RAIN. IT IS PSBL, IF THE MDLS CONTINUE TO AGREE ON A LOCATION AS THEY ARE NOW (N AND W) THAT A FFA MAY BE NEEDED AS RNFL AMTS APPEAR TO BE AOA 1 INCH. THE FRONT SHUD CLEAR THE AREA DURG THE OVERNIGHT HOURS ON FRI AND CLEARING WILL OCCUR FROM N TO S. PRECIP MAY LINGER ACRS THE DELMARVA INTO ERLY SAT. THE ECMWF DOES CLEAR THINGS OUT FASTER THAN THE GFS. BOTH MDLS KEEP THE FRONT CLOSE BY, SO IT WON`T TAKE MUCH IN THE WAY OF A PERTURBATION FOR IT TO BRING ANOTHER SHOT OF PRECIP, BUT FOR BOTH MDLS DRY THINGS OUT BY LATER SAT AT THE LATEST, AS HIGH PRESSURE BUILDS IN. SUN THEN LOOKS DRY. MUCH LESS CONFIDENCE INTO MON AS THE GFS WANTS TO BRING A WAVE ACRS THE STALLED FRONT, WHICH WOULD BRING PRECIP, MAINLY ACRS THE S. THE ECMWF IS DRY DURG THIS TIME. THE CMC ALSO HAS A WAVE ON MON, BUT ITS OVERALL SYNOPTIC PATN IS A BUT SUSPECT OVERALL. BY TUE, THE MDLS BRING ANOTHER LOW TO THE N AND ANOTHER CDFNT ACRS THE REGION, AND ANOTHER CHC OF RAIN. THIS IS A LOW CONFIDENCE FCST FOR THE EARLY PORTION OF NEXT WEEK AS IT WILL BE DEPENDENT ON THE POSN OF THE FRONT AND IF ANY WAVES DEVELOP ALG IT AND WHERE THEY MOVE. BASED ON THE ECMWF`S GENLY SUPERIOR PERFORMANCE, WANT TO GIVE IT A BIT OF A NOD, BUT CAN`T RULE OUT A MORE PESSIMIST SOLN EITHER. FOR NOW, WILL BRING IN LOW POPS MON, LOW CHC POPS ON TUE TO SEE HOW THINGS PLAY OUT AND THEN A DRY FCST ON WED AS HIGH PRESSURE BUILDS IN. TEMPS WILL GENLY BE AT OR SLIGHTLY ABV NRML THRU THE PD. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...IMPROVING CIGS WITH BREAKS IN THE CLOUDS AND SLOW MIXING OUT OF ANY LIGHT FOG THIS MORNING...THEN SCT SHOWERS/TSTMS OCCUR LATER TODAY. LOWER CONDITIONS WITH THE CONVECTION. TONIGHT...SHOWERS/TSTMS GRADUALLY ENDING. LOWER CIGS/VSBYS AGAIN INDICTED IN THE GUIDANCE MVFR?...IFR? LOW CONFID OVERALL. OUTLOOK... FRIDAY THROUGH EARLY MORNING SATURDAY...MAINLY MVFR OR IFR CONDITIONS EXPECTED IN SHOWERS AND PSBL TSTMS. SOME HVY RAIN PSBL. MDT CONFIDENCE. REMAINDER OF SATURDAY THROUGH MONDAY...MOSTLY VFR CONDITIONS. ISOLATED SHWRS/TSTMS REMAIN POSSIBLE, ESPECIALLY MON. SUN SHOULD BE DRY. MDT TO HIGH CONFIDENCE. && .MARINE... A MODERATE SOUTH WIND CONTINUES ACROSS THE OCEAN WATERS AND MORE OF A SWLY WIND ACROSS DEL BAY. OVERALL...THE WIND SPEEDS AND SEAS WILL REMAIN BELOW SCA CRITERIA TODAY AND TONIGHT. A FEW WIND GUSTS TO 25 KTS MAY OCCUR EARLY THIS MORNING AND LATER TONIGHT...BUT THEY WILL NOT PERSIST. THE MAIN MARINE HAZARD TODAY AND TONIGHT WOULD BE ANY GUSTY WINDS ASSD WITH TSTMS WHICH WILL BE AROUND EARLY THIS MORNING...THIS AFTERNOON AND TONIGHT. SEAS...ON THE OCEAN 3-4 FT AND DEL BAY 1-2 FT (NORTH) AND 2-3FT (SOUTH). OUTLOOK... OVERALL, SUB-SCA CONDITIONS ARE EXPECTED FOR OUR AREA WATERS THROUGH THE BULK OF THE OUTLOOK PERIOD. GUIDANCE IS SHOWING AN INCREASE IN THE SOUTHERLY TO SOUTHWESTERLY FLOW DURING FRIDAY AHEAD OF AN APPROACHING CDFNT. THE WIND CUD GUST TO AROUND 20 KTS OR SO AS WELL DURG THIS TIME. IN ADDITION, WAVEWATCH GUIDANCE ALSO INDICATES SEAS RISING TO AROUND 5 OR PSBLY 6 FEET FOR OUR COASTAL WATERS DURING THIS TIMEFRAME. HOWEVER, THIS GUIDANCE TENDS TO RUN A LITTLE HIGH IN SOUTHERLY FLOW, AND CONFIDENCE IS BELOW AVERAGE. SO WILL CONTINUE TO MONITOR FOR ANY PSBL FLAGS. SEAS SHOULD THEN LOWER BEHIND THE CFP INTO THE WEEKEND, AS WINDS SHIFT TO THE NW. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...NIERENBERG NEAR TERM...GIGI/O`HARA SHORT TERM...O`HARA LONG TERM...NIERENBERG AVIATION...NIERENBERG/O`HARA MARINE...NIERENBERG/O`HARA
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
908 AM EDT THU AUG 8 2013 .SYNOPSIS... LOW PRESSURE MOVING ACROSS SOUTHEASTERN CANADA WILL ALLOW A COLD FRONT TO APPROACH THE REGION ON FRIDAY AND CROSS THE AREA BY LATE FRIDAY OR EARLY SATURDAY. THIS FRONT WILL EVENTUALLY STALL TO OUR SOUTH FOR SUNDAY. EARLY NEXT WEEK, A FEW WAVES OF LOW PRESSURE ARE FORECAST TO MOVE ALONG THE STALLED BOUNDARY. HIGH PRESSURE WILL THEN BUILD IN TOWARD MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... QUITE THE FORECASTING CONUNDRUM FOR TODAY ACROSS OUR CWA. AS BEST KINEMATIC AND THERMODYNAMIC SUPPORT FOR CONVECTION IS AT ODDS WITH ONGOING CLOUD COVER AND LOWER EXPECTED TEMPERATURES. LIKE YESTERDAY MOST OF THE MESOSCALE MODELS ARE NOT VERIFYING WELL AT ALL IN OUR CWA THIS MORNING AND THIS INCLUDES THE RAP. CLOSEST TO REALITY IN OUR CWA HAS BEEN THE NSSL WRF. BECAUSE OF THEIR HOURLY INITIALIZATION THE HRRR AND COSPA HAVE BEEN DOING OK 1-3HRS DOWN THE ROAD; THE SAME CAN NOT BE SAID FOR THE RAP. THE LATTER PAIR ARE DISSIPATING THE MCS BEFORE MUCH OF IT CAN GET INTO OUR NRN CWA THIS MORNING AND THEN ARE ESTABLISHING A DIFFERENTIAL HEATING BOUNDARY INDUCED CONVECTION CLOSE TO THE PHL METRO AREA LATER THIS MORNING. GOING AGAINST THIS IS RELATIVELY DRIER AIR COMING IN FROM THE ATLANTIC ACROSS THE SERN PART OF OUR CWA. WANT TO SEE HOW CLEARING EVOLVES BEFORE MAKING ANY BIG CHANGES AS THIS ESTF UPDATE WILL KEEP THE HIGHEST POPS NW. THERE IS CLEARING BEHIND THE DEPARTING MCS WESTERN NY AND FORECAST CONVECTIVE TEMPS ARE LOWER NORTH THAN SOUTH. 12Z SOUNDINGS GIVE 90F AS A POSSIBLE HIGH SOUTHERN PART OF OUR CWA (CONVECTIVE TEMP LOW 80S), SO BUMPED MAX TEMPS UPWARD IN DELMARVA, KEPT THE REST RELATIVELY THE SAME. AN ILL DEFINED WARM FRONT ACROSS THE AREA EARLY THIS MORNING WILL MOVE OFF TO THE NORTH/EAST LATER TODAY. WE WILL SPEND THE REST OF TODAY (AND TONIGHT) IN THE WARM SECTOR. ABUNDANT MOISTURE WILL REMAIN IN PLACE ACROSS THE REGION. ANOTHER BATCH OF SHOWERS/TSTMS ACROSS WRN NY APPEARS TO BE WEAKENING SLOW ALSO. IT MAY BRING EXTRA CLOUDINESS LATER THIS MORNING ACROSS THE NORTH. UPPER HEIGHTS WILL BE RISING THRU THE DAY AND THERE ARE ONLY WEAK S/W MOVING THRU THE FLOW. BREAKS WILL OCCUR TODAY ALLOWING FOR POCKETS OF HEATING/INSTABILITY TO DEVELOP. WE WILL GO ALONG WITH THE DETERMINISTIC MODELS AND MOS AND MOSTLY KEEP THE HIGHER CHC FOR POPS NORTH/WEST MOSTLY THIS AFTERNOON WITH SLGT CHC OR LOW CHC POPS SOUTH/EAST. THERE WILL BE SOME CAPE VALUES AROUND 750-1250 J/KG ACROSS THE AREA...BUT THE HIGHEST VALUES WILL OCCUR WITH ANY BREAKS IN THE CLOUDS TODAY. SPC HAS OUR AREA IN `SEE TEXT` AND MENTIONS ONLY SMALL POSSIBILITY OF SOME STRONGER WIND GUSTS WITH ANY CONVECTION THAT DEVELOPS. QPF...1/2 INCH NORTH RANGING DOWN TO LIGHT AMTS SOUTH. TEMPERATURES WILL BE HELD IN CHECK EARLY TODAY WITH ABUNDANT AMOUNTS OF CLOUDS EARLY. WE WENT WITH MOSTLY MAV MOS AND OFFERED LOW 80S OVER MOST AREAS TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... WE WILL CONTINUE IN THE WARM SECTOR TONIGHT WITH THE UPPER FLOW BECOMING A BIT MORE SWRLY ALOFT. A COLD FRONT WILL BE SLOWING ITS APPROACH INTO WRN NY AND WRN PA. SHOWERS AND SCT THUNDERSTORMS WILL CONTINUE FROM THE LATE AFTERNOON INTO THE EARLY OVERNIGHT PERIODS. THE AREAS NORTH/WEST WILL HAVE THE BETTER CHCS FOR THE RAINS. WE WILL CARRY THE LIKELY POPS INTO THE OVERNIGHT NORTH/WEST AND HOLD THE HIGHER CHC POPS SOUTH/EAST. QPF...1/2 INCH NORTH 1/10 INCH SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AN AREA OF LOW PRESSURE IN SERN CANAD WILL WORK ITS WAY EWD. AS IT DOES A CDFNT WILL CROSS THE AREA FROM W TO E ON FRI INTO FRI NIGHT. THE LATEST MDL GUID CURRENTLY INDICATES THAT THE FRI DAYTIME PD COULD BE FAIRLY WET, FOR AT LEAST A PORTION OF THE AREA, AND THERE COULD BE LOCALIZED CONVECTION WHICH COULD MAKE FOR PDS OF HEAVY RAIN. IT IS PSBL, IF THE MDLS CONTINUE TO AGREE ON A LOCATION AS THEY ARE NOW (N AND W) THAT A FFA MAY BE NEEDED AS RNFL AMTS APPEAR TO BE AOA 1 INCH. THE FRONT SHUD CLEAR THE AREA DURG THE OVERNIGHT HOURS ON FRI AND CLEARING WILL OCCUR FROM N TO S. PRECIP MAY LINGER ACRS THE DELMARVA INTO ERLY SAT. THE ECMWF DOES CLEAR THINGS OUT FASTER THAN THE GFS. BOTH MDLS KEEP THE FRONT CLOSE BY, SO IT WON`T TAKE MUCH IN THE WAY OF A PERTURBATION FOR IT TO BRING ANOTHER SHOT OF PRECIP, BUT FOR BOTH MDLS DRY THINGS OUT BY LATER SAT AT THE LATEST, AS HIGH PRESSURE BUILDS IN. SUN THEN LOOKS DRY. MUCH LESS CONFIDENCE INTO MON AS THE GFS WANTS TO BRING A WAVE ACRS THE STALLED FRONT, WHICH WOULD BRING PRECIP, MAINLY ACRS THE S. THE ECMWF IS DRY DURG THIS TIME. THE CMC ALSO HAS A WAVE ON MON, BUT ITS OVERALL SYNOPTIC PATN IS A BUT SUSPECT OVERALL. BY TUE, THE MDLS BRING ANOTHER LOW TO THE N AND ANOTHER CDFNT ACRS THE REGION, AND ANOTHER CHC OF RAIN. THIS IS A LOW CONFIDENCE FCST FOR THE EARLY PORTION OF NEXT WEEK AS IT WILL BE DEPENDENT ON THE POSN OF THE FRONT AND IF ANY WAVES DEVELOP ALG IT AND WHERE THEY MOVE. BASED ON THE ECMWF`S GENLY SUPERIOR PERFORMANCE, WANT TO GIVE IT A BIT OF A NOD, BUT CAN`T RULE OUT A MORE PESSIMIST SOLN EITHER. FOR NOW, WILL BRING IN LOW POPS MON, LOW CHC POPS ON TUE TO SEE HOW THINGS PLAY OUT AND THEN A DRY FCST ON WED AS HIGH PRESSURE BUILDS IN. TEMPS WILL GENLY BE AT OR SLIGHTLY ABV NRML THRU THE PD. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...IMPROVING CIGS WITH BREAKS IN THE CLOUDS AND SLOW MIXING OUT OF ANY LIGHT FOG THIS MORNING...THEN SCT SHOWERS/TSTMS OCCUR LATER TODAY. LOWER CONDITIONS WITH THE CONVECTION. THE PROB30 FROM EARLIER WAS RETAINED IN THE 06Z TAFS...WE`LL DECIDE LATER WHAT TO DO FOR THE 12Z TAFS...SINCE THE 9 HOUR WINDOW OF `NO PROB30S` WILL BE OPEN AT THAT POINT. TONIGHT...SHOWERS/TSTMS GRADUALLY ENDING. LOWER CIGS/VSBYS AGAIN INDICTED IN THE GUIDANCE MVFR?...IFR? LOW CONFID OVERALL. OUTLOOK... FRIDAY THROUGH EARLY MORNING SATURDAY...MAINLY MVFR OR IFR CONDITIONS EXPECTED IN SHOWERS AND PSBL TSTMS. SOME HVY RAIN PSBL. MDT CONFIDENCE. REMAINDER OF SATURDAY THROUGH MONDAY...MOSTLY VFR CONDITIONS. ISOLATED SHWRS/TSTMS REMAIN POSSIBLE, ESPECIALLY MON. SUN SHOULD BE DRY. MDT TO HIGH CONFIDENCE. && .MARINE... A MODERATE SOUTH WIND CONTINUES ACROSS THE OCEAN WATERS AND MORE OF A SWLY WIND ACROSS DEL BAY. OVERALL...THE WIND SPEEDS AND SEAS WILL REMAIN BELOW SCA CRITERIA TODAY AND TONIGHT. A FEW WIND GUSTS TO 25 KTS MAY OCCUR EARLY THIS MORNING AND LATER TONIGHT...BUT THEY WILL NOT PERSIST. THE MAIN MARINE HAZARD TODAY AND TONIGHT WOULD BE ANY GUSTY WINDS ASSD WITH TSTMS WHICH WILL BE AROUND EARLY THIS MORNING...THIS AFTERNOON AND TONIGHT. SEAS...ON THE OCEAN 3-4 FT AND DEL BAY 1-2 FT (NORTH) AND 2-3FT (SOUTH). OUTLOOK... OVERALL, SUB-SCA CONDITIONS ARE EXPECTED FOR OUR AREA WATERS THROUGH THE BULK OF THE OUTLOOK PERIOD. GUIDANCE IS SHOWING AN INCREASE IN THE SOUTHERLY TO SOUTHWESTERLY FLOW DURING FRIDAY AHEAD OF AN APPROACHING CDFNT. THE WIND CUD GUST TO AROUND 20 KTS OR SO AS WELL DURG THIS TIME. IN ADDITION, WAVEWATCH GUIDANCE ALSO INDICATES SEAS RISING TO AROUND 5 OR PSBLY 6 FEET FOR OUR COASTAL WATERS DURING THIS TIMEFRAME. HOWEVER, THIS GUIDANCE TENDS TO RUN A LITTLE HIGH IN SOUTHERLY FLOW, AND CONFIDENCE IS BELOW AVERAGE. SO WILL CONTINUE TO MONITOR FOR ANY PSBL FLAGS. SEAS SHOULD THEN LOWER BEHIND THE CFP INTO THE WEEKEND, AS WINDS SHIFT TO THE NW. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...NIERENBERG NEAR TERM...GIGI/O`HARA SHORT TERM...O`HARA LONG TERM...NIERENBERG AVIATION...NIERENBERG/O`HARA MARINE...NIERENBERG/O`HARA
AREA FORECAST DISCUSSION
NWS BOISE ID
950 AM MDT THU AUG 8 2013 .DISCUSSION...SPEED MAX MOVING NORTH ON THE EAST SIDE OF THE UPPER LOW IS EVIDENT IN FAR NE CA AS OF 930 AM MDT. THIS IS ALREADY HELPING TO INITIATE AND STRENGTHEN CONVECTION IN SE OREGON...AND THE EFFECT IS GOING TO BE FELT EVEN IN OUR SW IDAHO ZONES. AS WE HEAT UP TODAY...WE EXPECT SCATTERED SHOWERS AND THUNDERSTORMS OVER A LARGE PORTION OF THE CWA. RED FLAG WARNINGS ARE STILL IN EFFECT FOR MUCH OF THE AREA. LATEST HRRR OUTPUT HAS BEEN CONSISTENT IN BRINGING CONVECTION EVEN INTO THE VALLEYS...SO HAVE SLIGHTLY RAISED POPS IN THE LOWER ELEVATIONS FOR THIS AFTERNOON. CONCERNING TOMORROW...THE DRY SLOT APPEARS HEADED MAINLY FOR THE IDAHO SIDE OF OUR CWA. WE HAVE ALREADY UPDATED POP GRIDS TO TAKE THIS INTO ACCOUNT FOR FRIDAY...AND MAY TWEAK THEM A BIT MORE THIS AFTERNOON BEFORE THE FINAL PACKAGE COMES OUT. ANOTHER UPDATE WILL BE DONE SHORTLY. && .AVIATION...VFR. THIS MORNING...SCATTERED TO BROKEN MID LEVEL CLOUDS AND ISOLATED SHOWERS. THIS AFTERNOON THROUGH TONIGHT... ISOLATED THUNDERSTORMS OVER THE WEST CENTRAL IDAHO AND BOISE MOUNTAINS. SCATTERED THUNDERSTORMS ACROSS EASTERN OREGON AND SOUTHWEST IDAHO SOUTH OF THE SNAKE RIVER VALLEY. SURFACE WINDS... LIGHT THIS MORNING THEN NORTH TO NORTHWEST 5-15 KTS THIS AFTERNOON AND TONIGHT. LOCAL GUSTY WINDS NEAR THUNDERSTORMS. WINDS ALOFT... NORTHEAST TO SOUTHEAST AROUND 10 KTS. && .PREV DISCUSSION... SHORT TERM...TODAY THROUGH FRIDAY...UPPER LOW OFF THE NORTHERN CALIFORNIA COAST WILL MOVE LITTLE THROUGH FRIDAY AS IT MEANDERS OFFSHORE. LATEST SATELLITE IMAGERY REVEALS PARTLY TO MOSTLY CLOUDY SKIES ACROSS SE OREGON AND SW IDAHO...BUT RADAR RETURNS ONLY SHOWED ISOLATED SHOWERS ACROSS PORTIONS OF SE OREGON AND IN SW IDAHO SOUTH OF THE SNAKE RIVER. THERE HAS NOT BEEN LIGHTNING FOR SEVERAL HOURS AND EXPECT ONLY ISOLATED SHOWERS THIS MORNING. SHORTWAVES ROTATING THROUGH THE REGION ASSOCIATED WITH UPPER LOW...COMBINED WITH INSTABILITY FROM DAYTIME HEATING...WILL SUPPORT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON. THE COVERAGE WILL BE GREATER THAN WEDNESDAY IN SW IDAHO...ESPECIALLY IN THE HIGHER TERRAIN...DUE TO AN INCREASE IN MOISTURE. THERE WILL ALSO BE ANOTHER ROUND OF SCATTERED THUNDERSTORMS IN SE OREGON THIS AFTERNOON. CONVECTION WILL REMAIN ACTIVE THIS EVENING THEN GRADUALLY DIMINISH OVERNIGHT. MODELS SHOW THE MOST ACTIVE AREA WILL BE ACROSS SE OREGON WITH CONVECTION LINGERING INTO FRIDAY MORNING AS MORE SHORT WAVES PIVOT AROUND THE UPPER LOW. MEANWHILE...MUCH DRIER AIR OVER SOUTHERN NEVADA WILL MOVE NORTHWARD AND REACH PORTIONS OF SW IDAHO ON FRIDAY. POPS MAY NEED TO BE TRIMMED LOWER IF THIS MODEL TREND CONTINUES. IN THE MEANTIME...WILL KEEP GENERALLY ISOLATED POPS ACROSS THE HIGHER TERRAIN WITH NO MENTION OF CONVECTION IN THE SW IDAHO VALLEYS. CHANCE OF SHOWERS/THUNDERSTORMS WILL CONTINUE IN SE OREGON INTO THE AFTERNOON DUE TO THE CLOSER PROXIMITY TO THE LOW. TEMPERATURES WILL BE A FEW DEGREES LOWER TODAY AND FRIDAY...ALTHOUGH STILL A LITTLE ABOVE NORMAL. NO SIGNIFICANT WINDS ARE FORECAST...EXCEPT LOCALLY STRONG WIND GUSTS WILL ACCOMPANY THE THUNDERSTORMS. LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...LITTLE CHANGE IN THE WEATHER PATTERN AS A CLOSED UPPER LEVEL LOW WILL BE OVER NORTHERN CALIFORNIA FRIDAY NIGHT AND THEN SLOWLY LIFT TO THE NORTH ALONG THE WEST COAST SATURDAY THROUGH MONDAY NIGHT AND THEN REMAIN NEARLY STATIONARY JUST OFF THE WEST COAST OF WASHINGTON TUESDAY THROUGH WEDNESDAY. WITH THE LOW SHIFTING TO THE NORTH PRECIPITATION ASSOCIATED WITH THIS LOW WILL ALSO SHIFT TO NORTHERN ZONES AND DECREASE TO A SLIGHT CHANCE. TEMPERATURES THROUGH THE EXTENDED PERIOD WILL REMAIN A FEW DEGREES ABOVE NORMAL. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...RED FLAG WARNING UNTIL 6 AM MDT FRIDAY IDZ402-403-421-426. RED FLAG WARNING UNTIL MIDNIGHT MDT FRIDAY NIGHT IDZ423. OR...RED FLAG WARNING UNTIL MIDNIGHT MDT /11 PM PDT/ FRIDAY NIGHT ORZ636-637. && $$ WEATHER.GOV/BOISE DISCUSSION...SP AVIATION.....JT PREV SHORT TERM...BW PREV LONG TERM....JA
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1032 AM EDT THU AUG 8 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 210 AM EDT THU AUG 8 2013 WARM AND HUMID AIR WILL REMAIN OVER INDIANA FOR THE NEXT FEW DAYS AS A FRONTAL BOUNDARY LINGERS ACROSS SOUTHERN INDIANA. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH FRIDAY NIGHT AS SEVERAL UPPER LEVEL WEATHER DISTURBANCES PUSH INTO THE OHIO VALLEY. DRY AND LESS HUMID WEATHER WILL ARRIVE SATURDAY AS HIGH PRESSURE FROM CANADA BUILDS ACROSS THE REGION. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1003 AM EDT THU AUG 8 2013 LOW STRATUS STUBBORNLY HANGING ON ACROSS A GOOD PORTION OF THE FORECAST AREA...WITH CLOUDS HAVING ACTUALLY INCREASED IN COVERAGE OVER NORTHERN COUNTIES SINCE 12Z. SCATTERED CONVECTION HAS ALSO DEVELOPED OVER THE NORTHERN WABASH VALLEY OVER THE LAST HOUR OR SO. 13Z SURFACE ANALYSIS PLACES THE WEAK REMNANT BOUNDARY ACROSS THE FORECAST AREA...ROUGHLY EXTENDING FROM NEAR RICHMOND W/SW TO JUST SOUTH OF THE INDY METRO AND KHUF. MUGGY MORNING WITH TEMPS MAINLY IN THE 70S. COMPLEX FORECAST FOR THE REMAINDER OF THE DAY AS CONVECTION HAS DEVELOPED SOONER THAN ANTICIPATED. VERY WEAK FORCING ALOFT WITHIN A POORLY DEFINED UPPER TROUGH COMBINED WITH AN AREA OF LOW LEVEL MOISTURE CONVERGENCE APPEAR TO BE CONTRIBUTING TO THE CONVECTIVE DEVELOPMENT NORTHWEST OF INDY THIS MORNING. HRRR GUIDANCE IS CAPTURING THIS TO SOME DEGREE...AND TRENDS TOWARDS FURTHER CONVECTIVE DEVELOPMENT ACROSS THE FORECAST AREA INTO THE AFTERNOON. CONSIDERING INCREASING INSTABILITY OVER THE NEXT FEW HOURS COMBINED WITH THE DEEP LOW LEVEL MOISTURE PRESENT...WEAK FORCING ALOFT AND THE PRESENCE OF THE BOUNDARY ACROSS THE REGION...REALLY HARD TO ARGUE WITH THIS SCENARIO AT THIS POINT. BUMPED UP POPS TO BEGIN NORTHWEST OF INDY NOW...THEN INCREASE TO 30-50 POPS OVER ENTIRE FORECAST AREA FOR THE AFTERNOON. MENTIONING ONLY ISOLATED THUNDER THROUGH MIDDAY AS MESOANALYSIS SHOWS LITTLE INSTABILITY PRESENT RIGHT NOW. EXPECT A BETTER CHANCE FOR THUNDER THIS AFTERNOON AS INSTABILITY INCREASES WITH DIURNAL HEATING. WHILE THERE ARE BREAKS IN THE CLOUD COVER THIS MORNING... ESPECIALLY OVER SOUTHERN COUNTIES...HAVE INCREASED CLOUD COVERAGE FOR THE AFTERNOON AS CU LIKELY TO FILL IN AS CONVECTIVE TEMPS ARE MET. ADDITIONALLY...CLOUD DEBRIS FROM WEAKENING MCS OVER THE OZARKS POISED TO EXPAND INTO THE REGION THIS AFTERNOON. WITH THE INCREASE IN CLOUDS...DROPPED HIGH TEMPS A COUPLE DEGREES AS WELL. ZONE AND GRID UPDATES OUT SHORTLY. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 210 AM EDT THU AUG 8 2013 LITTLE CHANGE APPEARS IN THE OVERALL PATTERN THROUGH FRIDAY AFTERNOON. GFS AND NAM CONTINUE TO SUGGEST WEAK...POORLY ORGANIZED SHORT WAVES PUSHING THROUGH THE FLOW ALOFT. MEANWHILE THE FRONTAL BOUNDARY LINGERS NEAR THE OHIO VALLEY. 310K GFS ISENTROPIC SURFACE FAILS TO SHOW MUCH IN THE WAY OF LIFT...BUT DOES MANAGE TO ILLUSTRATE THE VERY MOIST AIR MASS ACROSS THE AREA SHOWING SPECIFIC HUMIDITIES IN EXCESS OF 4 G/KG ON FRIDAY. FORECAST SOUNDINGS THROUGH FRIDAY SHOW LESS FAVORABLE LAPSE RATES WITH LESS CAPE THAN TODAY. HOWEVER WITH THE MOIST FLOW ALOFT...MOIST AIR IN PLACE AT THE SURFACE AND UNCERTAINTY REMAINING WITH ANY EMBEDDED SHORT WAVES WILL CONTINUE TO KEEP LOW CHC POPS TONIGHT AND AGAIN ON FRIDAY. WILL TREND LOWS WARMER THAN MAVMOS AND STICK CLOSE ON HIGHS FOR FRIDAY. ON FRIDAY NIGHT THE GFS AND NAM BOTH SUGGEST A STRONG SHORT WAVE ALOFT SWEEPING THROUGH THE FLOW. TIME HEIGHT SECTIONS BEGIN TO SHOW MORE VV WHILE THE NAM SOUNDINGS SHOW DEEP SATURATION. THE GFS IS MUCH LESS AGGRESSIVE WITH SATURATION...BUT STILL DOES SHOW THE MAIN WAVE ALOFT. MEANWHILE GFS 310K ISENTROPIC SURFACE SHOWS MINIMAL LIFT...BUT A VERY MOIST AIR MASS IN PLACE WITH SPECIFIC HUMIDITIES OVER 5 G/KG AGAIN. IN THE LOWER LEVELS...BEST CONVERGENCE REMAINS NEAR THE FRONT...LINGERING NEAR THE OHIO RIVER. THUS WILL USE A BLEND OF THE LOW GFS POPS AND THE HIGHER NAM POPS FOR FRIDAY NIGHT. A MUCH DIFFERENT AIR MASS ARRIVES ON SATURDAY AND SATURDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS THE AREA FROM CANADA. FORECAST SOUNDINGS AGREE AS THE COLUMN DRIES OUT DRAMATICALLY AMID SUBSIDENCE. CONVECTIVE TEMPERATURES LOOK QUITE REACHABLE WITH A MID LEVEL CAP IN PLACE...THUS EXPECTED SOME AFTERNOON CU ON SATURDAY AND MOSTLY CLEAR SKIES THAT NIGHT. GIVEN THE FORECAST SOUNDINGS WILL TREND HIGHS ON SATURDAY COOLER THAN MAVMOS AND STICK CLOSE ON LOWS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... ISSUED AT 230 AM EDT THU AUG 8 2013 LONG TERM PERIOD CONTINUES TO BE CHARACTERIZED BY ZONAL TO MODERATELY CYCLONIC FLOW...SUGGESTING TEMPERATURES NEAR TO A FEW DEGREES BELOW NORMAL. INITIALIZATION HANDLES THIS WELL AND FEW CHANGES REQUIRED. DID CONFINE ONLY SLIGHT CHANCE POPS TO MONDAY AS GFS SUGGESTS A WEAK FRONTAL PASSAGE WHICH COULD POP A SHOWER OR ISOLATED STORM. BEYOND MONDAY...IN OTHER PERIODS POPS ARE NOT MERITED...AND WERE REMOVED. && .AVIATION /DISCUSSION FOR THE 081500Z TAF UPDATE/... ISSUED AT 1032 AM EDT THU AUG 8 2013 LOW LEVEL STRATUS HAS BROKEN UP...BUT ADDITIONAL CLOUDS AROUND 5000FT HAVE DEVELOPED. A WEAK SURFACE TROUGH WILL CONTINUE TO MEANDER NEAR KIND FOR THE NEXT FEW HOURS...KEEPING WINDS VARIABLE IN DIRECTION. SCATTERED SHOWERS WILL CONTINUE TO POP-UP AS WELL...SO ADDED VCSH. CANNOT RULE OUT MVFR CONDITIONS IN SHOWERS. PREVIOUS DISCUSSION FOLLOWS... SO FAR THIS MORNING...IND HAS MADE IT TO IFR BUT OTHER SITES HAVE ONLY FLIRTED WITH MVFR. ANY RESTRICTIONS SHOULD END BY MID MORNING...WITH BROKEN VFR STRATOCU REPLACING THEM. CANNOT ENTIRELY RULE OUT A FEW SHOWERS OR STORMS TODAY...BUT WITH MAJOR UNCERTAINTY IN TIMING AND PLACEMENT...CANNOT MENTION RIGHT NOW. LATE IN THE PERIOD...GUIDANCE WANTS TO REDEVELOP RESTRICTIONS...QUITE LOW IN SOME SPOTS. LAMP WAS SIGNIFICANTLY OVERAGGRESSIVE TONIGHT...SO WILL LEAVE ANY MENTION OF RESTRICTIONS OUT FOR NOW EXCEPT AT BMG...WHICH IS ONE OF THE FOGGIER SITES AND WILL BE A BIT CLOSER TO THE BOUNDARY AND IN A SLIGHTLY RICHER AIRMASS. WINDS WILL BE BELOW 10KT THROUGHOUT THE PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...PUMA NEAR TERM...RYAN SHORT TERM...PUMA LONG TERM....NIELD AVIATION...NIELD/50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1003 AM EDT THU AUG 8 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 210 AM EDT THU AUG 8 2013 WARM AND HUMID AIR WILL REMAIN OVER INDIANA FOR THE NEXT FEW DAYS AS A FRONTAL BOUNDARY LINGERS ACROSS SOUTHERN INDIANA. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH FRIDAY NIGHT AS SEVERAL UPPER LEVEL WEATHER DISTURBANCES PUSH INTO THE OHIO VALLEY. DRY AND LESS HUMID WEATHER WILL ARRIVE SATURDAY AS HIGH PRESSURE FROM CANADA BUILDS ACROSS THE REGION. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1003 AM EDT THU AUG 8 2013 LOW STRATUS STUBBORNLY HANGING ON ACROSS A GOOD PORTION OF THE FORECAST AREA...WITH CLOUDS HAVING ACTUALLY INCREASED IN COVERAGE OVER NORTHERN COUNTIES SINCE 12Z. SCATTERED CONVECTION HAS ALSO DEVELOPED OVER THE NORTHERN WABASH VALLEY OVER THE LAST HOUR OR SO. 13Z SURFACE ANALYSIS PLACES THE WEAK REMNANT BOUNDARY ACROSS THE FORECAST AREA...ROUGHLY EXTENDING FROM NEAR RICHMOND W/SW TO JUST SOUTH OF THE INDY METRO AND KHUF. MUGGY MORNING WITH TEMPS MAINLY IN THE 70S. COMPLEX FORECAST FOR THE REMAINDER OF THE DAY AS CONVECTION HAS DEVELOPED SOONER THAN ANTICIPATED. VERY WEAK FORCING ALOFT WITHIN A POORLY DEFINED UPPER TROUGH COMBINED WITH AN AREA OF LOW LEVEL MOISTURE CONVERGENCE APPEAR TO BE CONTRIBUTING TO THE CONVECTIVE DEVELOPMENT NORTHWEST OF INDY THIS MORNING. HRRR GUIDANCE IS CAPTURING THIS TO SOME DEGREE...AND TRENDS TOWARDS FURTHER CONVECTIVE DEVELOPMENT ACROSS THE FORECAST AREA INTO THE AFTERNOON. CONSIDERING INCREASING INSTABILITY OVER THE NEXT FEW HOURS COMBINED WITH THE DEEP LOW LEVEL MOISTURE PRESENT...WEAK FORCING ALOFT AND THE PRESENCE OF THE BOUNDARY ACROSS THE REGION...REALLY HARD TO ARGUE WITH THIS SCENARIO AT THIS POINT. BUMPED UP POPS TO BEGIN NORTHWEST OF INDY NOW...THEN INCREASE TO 30-50 POPS OVER ENTIRE FORECAST AREA FOR THE AFTERNOON. MENTIONING ONLY ISOLATED THUNDER THROUGH MIDDAY AS MESOANALYSIS SHOWS LITTLE INSTABILITY PRESENT RIGHT NOW. EXPECT A BETTER CHANCE FOR THUNDER THIS AFTERNOON AS INSTABILITY INCREASES WITH DIURNAL HEATING. WHILE THERE ARE BREAKS IN THE CLOUD COVER THIS MORNING... ESPECIALLY OVER SOUTHERN COUNTIES...HAVE INCREASED CLOUD COVERAGE FOR THE AFTERNOON AS CU LIKELY TO FILL IN AS CONVECTIVE TEMPS ARE MET. ADDITIONALLY...CLOUD DEBRIS FROM WEAKENING MCS OVER THE OZARKS POISED TO EXPAND INTO THE REGION THIS AFTERNOON. WITH THE INCREASE IN CLOUDS...DROPPED HIGH TEMPS A COUPLE DEGREES AS WELL. ZONE AND GRID UPDATES OUT SHORTLY. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 210 AM EDT THU AUG 8 2013 LITTLE CHANGE APPEARS IN THE OVERALL PATTERN THROUGH FRIDAY AFTERNOON. GFS AND NAM CONTINUE TO SUGGEST WEAK...POORLY ORGANIZED SHORT WAVES PUSHING THROUGH THE FLOW ALOFT. MEANWHILE THE FRONTAL BOUNDARY LINGERS NEAR THE OHIO VALLEY. 310K GFS ISENTROPIC SURFACE FAILS TO SHOW MUCH IN THE WAY OF LIFT...BUT DOES MANAGE TO ILLUSTRATE THE VERY MOIST AIR MASS ACROSS THE AREA SHOWING SPECIFIC HUMIDITIES IN EXCESS OF 4 G/KG ON FRIDAY. FORECAST SOUNDINGS THROUGH FRIDAY SHOW LESS FAVORABLE LAPSE RATES WITH LESS CAPE THAN TODAY. HOWEVER WITH THE MOIST FLOW ALOFT...MOIST AIR IN PLACE AT THE SURFACE AND UNCERTAINTY REMAINING WITH ANY EMBEDDED SHORT WAVES WILL CONTINUE TO KEEP LOW CHC POPS TONIGHT AND AGAIN ON FRIDAY. WILL TREND LOWS WARMER THAN MAVMOS AND STICK CLOSE ON HIGHS FOR FRIDAY. ON FRIDAY NIGHT THE GFS AND NAM BOTH SUGGEST A STRONG SHORT WAVE ALOFT SWEEPING THROUGH THE FLOW. TIME HEIGHT SECTIONS BEGIN TO SHOW MORE VV WHILE THE NAM SOUNDINGS SHOW DEEP SATURATION. THE GFS IS MUCH LESS AGGRESSIVE WITH SATURATION...BUT STILL DOES SHOW THE MAIN WAVE ALOFT. MEANWHILE GFS 310K ISENTROPIC SURFACE SHOWS MINIMAL LIFT...BUT A VERY MOIST AIR MASS IN PLACE WITH SPECIFIC HUMIDITIES OVER 5 G/KG AGAIN. IN THE LOWER LEVELS...BEST CONVERGENCE REMAINS NEAR THE FRONT...LINGERING NEAR THE OHIO RIVER. THUS WILL USE A BLEND OF THE LOW GFS POPS AND THE HIGHER NAM POPS FOR FRIDAY NIGHT. A MUCH DIFFERENT AIR MASS ARRIVES ON SATURDAY AND SATURDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS THE AREA FROM CANADA. FORECAST SOUNDINGS AGREE AS THE COLUMN DRIES OUT DRAMATICALLY AMID SUBSIDENCE. CONVECTIVE TEMPERATURES LOOK QUITE REACHABLE WITH A MID LEVEL CAP IN PLACE...THUS EXPECTED SOME AFTERNOON CU ON SATURDAY AND MOSTLY CLEAR SKIES THAT NIGHT. GIVEN THE FORECAST SOUNDINGS WILL TREND HIGHS ON SATURDAY COOLER THAN MAVMOS AND STICK CLOSE ON LOWS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... ISSUED AT 230 AM EDT THU AUG 8 2013 LONG TERM PERIOD CONTINUES TO BE CHARACTERIZED BY ZONAL TO MODERATELY CYCLONIC FLOW...SUGGESTING TEMPERATURES NEAR TO A FEW DEGREES BELOW NORMAL. INITIALIZATION HANDLES THIS WELL AND FEW CHANGES REQUIRED. DID CONFINE ONLY SLIGHT CHANCE POPS TO MONDAY AS GFS SUGGESTS A WEAK FRONTAL PASSAGE WHICH COULD POP A SHOWER OR ISOLATED STORM. BEYOND MONDAY...IN OTHER PERIODS POPS ARE NOT MERITED...AND WERE REMOVED. && .AVIATION /DISCUSSION FOR THE 08/12Z TAFS/... ISSUED AT 705 AM EDT THU AUG 8 2013 SO FAR THIS MORNING...IND HAS MADE IT TO IFR BUT OTHER SITES HAVE ONLY FLIRTED WITH MVFR. ANY RESTRICTIONS SHOULD END BY MID MORNING...WITH BROKEN VFR STRATOCU REPLACING THEM. CANNOT ENTIRELY RULE OUT A FEW SHOWERS OR STORMS TODAY...BUT WITH MAJOR UNCERTAINTY IN TIMING AND PLACEMENT...CANNOT MENTION RIGHT NOW. LATE IN THE PERIOD...GUIDANCE WANTS TO REDEVELOP RESTRICTIONS...QUITE LOW IN SOME SPOTS. LAMP WAS SIGNIFICANTLY OVERAGGRESSIVE TONIGHT...SO WILL LEAVE ANY MENTION OF RESTRICTIONS OUT FOR NOW EXCEPT AT BMG...WHICH IS ONE OF THE FOGGIER SITES AND WILL BE A BIT CLOSER TO THE BOUNDARY AND IN A SLIGHTLY RICHER AIRMASS. WINDS WILL BE BELOW 10KT THROUGHOUT THE PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...PUMA NEAR TERM...RYAN SHORT TERM...PUMA LONG TERM....NIELD AVIATION...NIELD VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS WICHITA KS
708 AM CDT THU AUG 8 2013 UPDATED 12Z AVIATION SECTION. .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 TODAY & TONIGHT: AS ALL OBVIOUSLY KNOW...FLOODING TO CONTINUE BEINGING THE HIGHLIGHT OF FOR PERIODS AS FLOOD WATCH REMAINS IN EFFECT TIL 7 AM FRIDAY. DURING THE NIGHT A POORLY-DEFINED STATIONARY FRONT WAS DRAPED IN AN E-W MANNER GENERALLY THROUGH CNTRL OK WITH A WEAK 700-MB TROF SITUATED FROM THE UT/CO BORDER TO ~CA/AZ BORDER. WITH THE TROF SLOWLY EVOLVING INTO A WEAK LOW AS IT VENTURES E TO WRN KS RICH & DEEP MOISTURE WILL CONTINUE TO SPREAD NE ACROSS KS. WITH THE MID-LVL "KICKER" LACKING THE SFC-850MB FRONTS WILL MOVE VERY LITTLE...IF AT ALL...THEREBY PROMOTING BROAD ECHO TRAINING OVER KICT COUNTRY WHICH IN TURN WOULD EXACERBATE THE FLOODING SITUATION ACROSS THE CWA. ONLY CHANGES TO INHERITED FORECAST WERE TO SHIFT THE POP GRADIENT TO GENERALLY A N/S ORIENTATION TO BETTER ALIGN WITH THE BROAD LWR-MID DECK MOISTURE CHANNEL. ASSIGNED 80-100% TO CNTRL & SC KS THIS MORNING WITH HIGHEST POPS & ASSOCIATED TSRA SHIFTED E OVER SE KS THIS AFTERNOON AS HRRR DEPICTS. PW`S REMAIN IN 175-200% RANGE SO CONTINUED TO HIT QPFS HARD. FRI & FRI NIGHT: A FAIRLY BROAD UPR-DECK RIDGE IS FORECAST MOVE SLOWLY MOVG E TOWARD THE CNTRL ROCKIES...THE WEAK MID-LVL LOW WILL GET FORCED E TOWARD...THEN ACROSS...ERN KS. THIS WOULD THEREFORE SHIFT BULK OF +TSRA E ACROSS THE KS/MO BORDER ON FRI WITH -TSRA CONFINED FROM GENERALLY THE FLINT HILLS E FRI NGT. AS SUCH WILL CONTINUE TO SCHEDULE THE FLOOD WATCH TO END AT 7AM FRI. SAT & SAT NGT: MOST AREAS WILL EXPERIENCE AN INTERMISSION FROM TSRA. A FEW TSRA SHOULD VENTURE TOWARD THE WRN CORRIDOR SAT NGT AS WEAK LWR-DECK TROFFING BEGINS ALONG THE FRONT RANGE. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 ALL AREAS TO BE UNDER A WEAK NW FLOW REGIME FOR MOST OF THESE PERIODS. A WEAK COLD FRONT WILL VENTURE SE TOWARD & PERHAPS ACROSS KICGT COUNTRY EARLY NEXT WEEK WHICH WOULD INCREASE TSRA CHANCES FOR MUCH OF THESE PERIODS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 706 AM CDT THU AUG 8 2013 LARGE MESOSCALE CONVECTIVE SYSTEM (MCS)CONTINUES TO MAKE SLOW PROGRESS ACROSS THE ERN HALF OF KS AT THIS TIME. THIS WILL LEAD TO MVFR VSBYS WITH SHRA/VCTS FOR MOST TAF SITES UNTIL 15-16Z. AFTER THIS MCS MOVES EAST...WILL SEE SOME MID LEVEL CLOUDS AT 4K FEET HAND AROUND FOR THE AFTERNOON HOURS. SHOWERS/STORMS COULD REDEVELOP AND BECOME FAIRLY WIDESPREAD LATE THIS EVENING INTO THE OVERNIGHT...ESPECIALLY ACROSS SRN KS. COULD SEE SOME VSBY/CIG REDUCTIONS INTO AT LEAST THE MVFR RANGE AT TIMES OVERNIGHT. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 80 68 79 65 / 100 90 40 10 HUTCHINSON 78 65 76 63 / 100 90 40 10 NEWTON 78 66 76 63 / 100 90 50 10 ELDORADO 79 67 79 64 / 100 90 50 20 WINFIELD-KWLD 82 70 82 66 / 100 70 30 10 RUSSELL 77 63 76 62 / 100 70 40 10 GREAT BEND 77 63 75 61 / 100 80 40 10 SALINA 78 65 77 63 / 100 80 50 10 MCPHERSON 78 65 76 63 / 100 80 50 10 COFFEYVILLE 85 71 86 68 / 80 80 40 20 CHANUTE 81 69 81 66 / 80 80 60 20 IOLA 80 68 80 66 / 80 80 70 20 PARSONS-KPPF 83 70 84 67 / 80 80 50 20 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ032-033-047>053- 067>072-082-083-091>096-098>100. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
554 AM MDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 446 AM MDT THU AUG 8 2013 FORECAST CONCERNS WILL BE THREAT OF HEAVY RAINFALL AND CHANCES OF PRECIPITATION. SATELLITE SHOWING LITTLE CHANGE AS A COMPLEX AND AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO NORTH AMERICA REMAINS IN PLACE. COMPLEX AND SLOW MOVING UPPER HAS MOVED INTO COLORADO AND NEW MEXICO. SEVERAL SHORTWAVE TROUGHS ROTATING AROUND THIS MAIN SYSTEM. AIR MASS REMAINS MOIST THROUGH A DEEP LAYER. PERSISTENT FRONTAL BOUNDARY REMAINS DRAPED TO OUR SOUTH AND WEST. AT JET LEVEL...THE CANADIAN AND THE UKMET INITIALIZED BEST ON THE JET THAT IS OVER/NEAR OUR AREA. AT MID LEVELS...SATELLITE AND UPPER AIR ANALYSIS SHOW THAT THE ECMWF/CANADIAN FOLLOWED BY THE GFS ARE HANDLING CURRENT SYSTEM THE BEST. SREF AND RUC WERE DOING BEST AT THE SURFACE. COMPLICATED AND DIFFICULT PRECIPITATION FORECAST MADE MORE DIFFICULT BY THE FACT THAT MOST IF NOT ALL THE MODEL OUTPUT HAS CURRENT PRECIPITATION SHIELD TOO FAR SOUTH AND IS BASICALLY IGNORING IT. TODAY/TONIGHT...WEAK RIGHT REAR QUADRANT OF THE UPPER JET REMAINS OVER THE AREA FOR MOST OF THE DAY. MODELS ARE IN A LITTLE MORE DISAGREEMENT ON HOW FAST TO MOVE THIS SEGMENT EAST. ALTHOUGH THE GENERAL TREND IS TO HAVE THIS SLOWER/FURTHER WEST THAN THE PREVIOUS TWO DAYS. THE SLOWEST OF THE MODELS DO NOT TAKE THIS RIGHT REAR QUADRANT TO THE EAST OF THE FORECAST AREA UNTIL BETWEEN 06Z AND 12Z. BASED ON CURRENT SATELLITE...LATEST ECMWF IS CATCHING THE POSITION AND COMPLEXITY OF THE UPPER TROUGH THE BEST. CONSIDERING THE POSITION OF THE 700 MB LOW CIRCULATION...MODELS INDICATING WARM ADVECTION/UPGLIDE IN ADVANCE OF IT...PLUS STRONG UPPER DIVERGENCE INDICATED THE EASTERN PORTION OF THE AREA...BELIEVE THE CURRENT PRECIPITATION WILL CONTINUE TO MOVE AND DEVELOP AND MAINLY AFFECT THE EASTERN THIRD TO HALF OF THE FORECAST AREA. THIS LOOKS TO BE THE BEST AREA FOR MODERATE TO HEAVY RAINFALL TO CONTINUE THROUGH AT LEAST THIS AFTERNOON. GREELEY AND WALLACE COUNTIES APPEAR TO BE ON THE EDGE THIS AREA AT THIS TIME. HOWEVER... BOTH OF THOSE COUNTIES...ESPECIALLY WALLACE...GOT AT LEAST 2 TO 5 INCHES OF RAINFALL LAST. SO BELIEVE CHEYENNE COUNTY COLORADO DID NOT RECEIVE A LOT OF HEAVY RAINFALL AND DO NOT EXPECT IT TODAY... REMOVED THEM FROM THE FLASH FLOOD WATCH. KEPT THE REMAINDER IN THE WATCH AND EXTENDED IT THROUGH THE AFTERNOON HOURS DUE TO THE SLOW PROGRESSION OF THE SYSTEM ACROSS THE AREA. QUESTION THEN BECOMES HOW FAR WEST TO BRING THE PRECIPITATION. THE ECMWF IS SHOWING WRAP AROUND PRECIPITATION AND THE HRRR INDICATING THE SAME IDEA. VERY INTERESTING OCCURRENCE FOR THIS TIME OF YEAR. CURRENT RADAR TRENDS WOULD INDICATE THIS IS TAKING PLACE. SO KEPT HIGHER POPS FURTHER WEST AS A RESULT. OVERALL...IF THE ECMWF IS RIGHT AND IT IS SUPPORTED BY THE GEFS...THIS RAINFALL...EVEN AFTER THE INTENSITY LETS UP...WILL BE SLOW TO END AND WILL PROBABLY NOT DO SO UNTIL LATE TONIGHT. DID NOT INSERT AT THIS TIME BUT FOG WILL BE POSSIBLE IF RAIN QUITS SOONER AND CLEARING CAN OCCUR. LOWERED MAXES TODAY DUE TO CONTINUED PRECIPITATION AND THICK CLOUD COVER. FRIDAY/FRIDAY NIGHT...INTEREST PATTERN CONTINUES. THE ECMWF SHOWING IT MORE BUT ALSO INDICATED BY THE OTHER MODELS AND GEFS OUTPUT... MID LEVEL TROUGH REMAINS NEAR TO OVER THE AREA WITH WHAT LOOKS TO BE A DECENT AMOUNT OF MOISTURE LEFT. ALSO A LEFT FRONT QUADRANT OF A SOUTHERN JET BECOMES ESTABLISHED OVER THE AREA...ESPECIALLY THE SOUTHEAST HALF...BY THE MIDDLE OF THE DAY. THIS CONTINUES TO AFFECT THE AREA...ESPECIALLY THE SOUTHERN HALF...THROUGH THE ENTIRE NIGHT. SO INSERTED POPS WITH THE HIGHEST IN THE SOUTHEAST PORTION. WITH PERSISTENT CLOUD COVER AND UNFAVORABLE SURFACE WINDS...TRENDED MAXES DOWN A LITTLE. IF ENOUGH CLEARING CAN OCCUR AND WITH THE MOIST AIR MASS AND WET GROUND IN PLACE...WOULD NOT BE SURPRISED TO SEE FOG DEVELOP. SATURDAY/SATURDAY NIGHT...SOME DIFFERENCE IN THE JET STRUCTURE THROUGH THE DAY. AS A RESULT IT LOOKS LIKE SOME OR MOST OF THE AREA COULD GET LIFT FROM THE JET IN THE AREA. MID LEVEL RIDGE MOVES A LITTLE EAST WITH A SHORTWAVE TROUGH APPROACHING FROM THE WEST IN THE AFTERNOON. LEE TROUGH STRENGTHENS WITH SOUTHERLY WINDS INCREASING. POSSIBILITY OF SOME SURFACE CONVERGENCE IN THE FAR WEST. SO PUT IN A SLIGHT CHANCE IN THE FAR WEST. ABOVE MENTIONED SHORTWAVE TROUGH AND INCREASING MID LEVEL WARM AIR ADVECTION PATTERN ALONG WITH INCREASING JET LIFT COULD CAUSE SOME ISOLATED THUNDERSTORMS OVER THE MOST OF THE AREA. SO PULLED THE SLIGHT CHANCE FURTHER EAST DURING THE NIGHT. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 446 AM MDT THU AUG 8 2013 UPPER PATTERN THIS PERIOD WILL SLOWLY EVOLVE FROM AN ELONGATED EAST-WEST UPPER HIGH OVER THE SOUTHERN U.S. TO A HIGH CENTERED OVER NEW MEXICO AND A SUBSEQUENT GRADUAL BUILDING OF HEIGHTS OVER THE CENTRAL ROCKIES. MEANWHILE...UPPER LOWS WILL REMAIN ANCHORED OFF THE PAC NW COAST AND NEAR JAMES BAY...RESULTING IN WEAK TO MODERATE NORTHWEST FLOW ALOFT ACROSS THE NORTHERN AND CENTRAL PLAINS. A FEW WEAK SHORT WAVE TROUGHS WILL LIFT OUT OF THE WEST COAST TROUGH AND RIDE OVER THE TOP OF THE ROCKIES RIDGE...PROVIDING A FEW OPPORTUNITIES FOR PRECIP NEXT WEEK AS THEY EMERGE ONTO THE PLAINS. CURRENT GUIDANCE SUGGESTS THE MON-TUE TIME FRAME WILL PROVIDE SOMEWHAT BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS...AND THIS IS INDICATED WITH 30-40 POPS COMPARED TO 20 POPS ON REMAINING DAYS. NORTHWEST FLOW ALOFT WILL BRING A SURFACE CANADIAN AIRMASS DOWN NEXT WEEK SUGGESTING HIGH TEMPERATURES WILL REMAIN SEASONAL IN THE 80S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 549 AM MDT THU AUG 8 2013 COMPLEX AND UNCERTAIN SET OF TAFS. MODEL PERFORMANCE HAS BEEN POOR TONIGHT WITH THE HRRR FINALLY HAVING SOME GLIMMER AS TO WHAT REALITY IS. AT THIS TIME EXPECT THE WORST CONDITIONS TO BE AT KGLD. AT KGLD HAVE IFR CONDITIONS DUE TO STRATUS. HOWEVER THAT MAY LIFT WITH THE APPROACHING OF PRECIPITATION. AS IT STANDS NOW IFR CEILINGS ARE EXPECTED FOR MOST OF THE PERIOD AT KGLD. RAINFALL ENDS AT KGLD BY LATE AFTERNOON INTO EARLY EVENING WITH FOG THEN DEVELOPING. VFR CONDITIONS ARE EXPECTED AT KMCK UNTIL EARLY THIS EVENING IFR TO MVFR CONDITIONS ARE EXPECTED TO OCCUR. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR KSZ027>029-041-042. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...DLF AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
446 AM MDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 446 AM MDT THU AUG 8 2013 FORECAST CONCERNS WILL BE THREAT OF HEAVY RAINFALL AND CHANCES OF PRECIPITATION. SATELLITE SHOWING LITTLE CHANGE AS A COMPLEX AND AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO NORTH AMERICA REMAINS IN PLACE. COMPLEX AND SLOW MOVING UPPER HAS MOVED INTO COLORADO AND NEW MEXICO. SEVERAL SHORTWAVE TROUGHS ROTATING AROUND THIS MAIN SYSTEM. AIR MASS REMAINS MOIST THROUGH A DEEP LAYER. PERSISTENT FRONTAL BOUNDARY REMAINS DRAPED TO OUR SOUTH AND WEST. AT JET LEVEL...THE CANADIAN AND THE UKMET INITIALIZED BEST ON THE JET THAT IS OVER/NEAR OUR AREA. AT MID LEVELS...SATELLITE AND UPPER AIR ANALYSIS SHOW THAT THE ECMWF/CANADIAN FOLLOWED BY THE GFS ARE HANDLING CURRENT SYSTEM THE BEST. SREF AND RUC WERE DOING BEST AT THE SURFACE. COMPLICATED AND DIFFICULT PRECIPITATION FORECAST MADE MORE DIFFICULT BY THE FACT THAT MOST IF NOT ALL THE MODEL OUTPUT HAS CURRENT PRECIPITATION SHIELD TOO FAR SOUTH AND IS BASICALLY IGNORING IT. TODAY/TONIGHT...WEAK RIGHT REAR QUADRANT OF THE UPPER JET REMAINS OVER THE AREA FOR MOST OF THE DAY. MODELS ARE IN A LITTLE MORE DISAGREEMENT ON HOW FAST TO MOVE THIS SEGMENT EAST. ALTHOUGH THE GENERAL TREND IS TO HAVE THIS SLOWER/FURTHER WEST THAN THE PREVIOUS TWO DAYS. THE SLOWEST OF THE MODELS DO NOT TAKE THIS RIGHT REAR QUADRANT TO THE EAST OF THE FORECAST AREA UNTIL BETWEEN 06Z AND 12Z. BASED ON CURRENT SATELLITE...LATEST ECMWF IS CATCHING THE POSITION AND COMPLEXITY OF THE UPPER TROUGH THE BEST. CONSIDERING THE POSITION OF THE 700 MB LOW CIRCULATION...MODELS INDICATING WARM ADVECTION/UPGLIDE IN ADVANCE OF IT...PLUS STRONG UPPER DIVERGENCE INDICATED THE EASTERN PORTION OF THE AREA...BELIEVE THE CURRENT PRECIPITATION WILL CONTINUE TO MOVE AND DEVELOP AND MAINLY AFFECT THE EASTERN THIRD TO HALF OF THE FORECAST AREA. THIS LOOKS TO BE THE BEST AREA FOR MODERATE TO HEAVY RAINFALL TO CONTINUE THROUGH AT LEAST THIS AFTERNOON. GREELEY AND WALLACE COUNTIES APPEAR TO BE ON THE EDGE THIS AREA AT THIS TIME. HOWEVER... BOTH OF THOSE COUNTIES...ESPECIALLY WALLACE...GOT AT LEAST 2 TO 5 INCHES OF RAINFALL LAST. SO BELIEVE CHEYENNE COUNTY COLORADO DID NOT RECEIVE A LOT OF HEAVY RAINFALL AND DO NOT EXPECT IT TODAY... REMOVED THEM FROM THE FLASH FLOOD WATCH. KEPT THE REMAINDER IN THE WATCH AND EXTENDED IT THROUGH THE AFTERNOON HOURS DUE TO THE SLOW PROGRESSION OF THE SYSTEM ACROSS THE AREA. QUESTION THEN BECOMES HOW FAR WEST TO BRING THE PRECIPITATION. THE ECMWF IS SHOWING WRAP AROUND PRECIPITATION AND THE HRRR INDICATING THE SAME IDEA. VERY INTERESTING OCCURRENCE FOR THIS TIME OF YEAR. CURRENT RADAR TRENDS WOULD INDICATE THIS IS TAKING PLACE. SO KEPT HIGHER POPS FURTHER WEST AS A RESULT. OVERALL...IF THE ECMWF IS RIGHT AND IT IS SUPPORTED BY THE GEFS...THIS RAINFALL...EVEN AFTER THE INTENSITY LETS UP...WILL BE SLOW TO END AND WILL PROBABLY NOT DO SO UNTIL LATE TONIGHT. DID NOT INSERT AT THIS TIME BUT FOG WILL BE POSSIBLE IF RAIN QUITS SOONER AND CLEARING CAN OCCUR. LOWERED MAXES TODAY DUE TO CONTINUED PRECIPITATION AND THICK CLOUD COVER. FRIDAY/FRIDAY NIGHT...INTEREST PATTERN CONTINUES. THE ECMWF SHOWING IT MORE BUT ALSO INDICATED BY THE OTHER MODELS AND GEFS OUTPUT... MID LEVEL TROUGH REMAINS NEAR TO OVER THE AREA WITH WHAT LOOKS TO BE A DECENT AMOUNT OF MOISTURE LEFT. ALSO A LEFT FRONT QUADRANT OF A SOUTHERN JET BECOMES ESTABLISHED OVER THE AREA...ESPECIALLY THE SOUTHEAST HALF...BY THE MIDDLE OF THE DAY. THIS CONTINUES TO AFFECT THE AREA...ESPECIALLY THE SOUTHERN HALF...THROUGH THE ENTIRE NIGHT. SO INSERTED POPS WITH THE HIGHEST IN THE SOUTHEAST PORTION. WITH PERSISTENT CLOUD COVER AND UNFAVORABLE SURFACE WINDS...TRENDED MAXES DOWN A LITTLE. IF ENOUGH CLEARING CAN OCCUR AND WITH THE MOIST AIR MASS AND WET GROUND IN PLACE...WOULD NOT BE SURPRISED TO SEE FOG DEVELOP. SATURDAY/SATURDAY NIGHT...SOME DIFFERENCE IN THE JET STRUCTURE THROUGH THE DAY. AS A RESULT IT LOOKS LIKE SOME OR MOST OF THE AREA COULD GET LIFT FROM THE JET IN THE AREA. MID LEVEL RIDGE MOVES A LITTLE EAST WITH A SHORTWAVE TROUGH APPROACHING FROM THE WEST IN THE AFTERNOON. LEE TROUGH STRENGTHENS WITH SOUTHERLY WINDS INCREASING. POSSIBILITY OF SOME SURFACE CONVERGENCE IN THE FAR WEST. SO PUT IN A SLIGHT CHANCE IN THE FAR WEST. ABOVE MENTIONED SHORTWAVE TROUGH AND INCREASING MID LEVEL WARM AIR ADVECTION PATTERN ALONG WITH INCREASING JET LIFT COULD CAUSE SOME ISOLATED THUNDERSTORMS OVER THE MOST OF THE AREA. SO PULLED THE SLIGHT CHANCE FURTHER EAST DURING THE NIGHT. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 446 AM MDT THU AUG 8 2013 UPPER PATTERN THIS PERIOD WILL SLOWLY EVOLVE FROM AN ELONGATED EAST-WEST UPPER HIGH OVER THE SOUTHERN U.S. TO A HIGH CENTERED OVER NEW MEXICO AND A SUBSEQUENT GRADUAL BUILDING OF HEIGHTS OVER THE CENTRAL ROCKIES. MEANWHILE...UPPER LOWS WILL REMAIN ANCHORED OFF THE PAC NW COAST AND NEAR JAMES BAY...RESULTING IN WEAK TO MODERATE NORTHWEST FLOW ALOFT ACROSS THE NORTHERN AND CENTRAL PLAINS. A FEW WEAK SHORT WAVE TROUGHS WILL LIFT OUT OF THE WEST COAST TROUGH AND RIDE OVER THE TOP OF THE ROCKIES RIDGE...PROVIDING A FEW OPPORTUNITIES FOR PRECIP NEXT WEEK AS THEY EMERGE ONTO THE PLAINS. CURRENT GUIDANCE SUGGESTS THE MON-TUE TIME FRAME WILL PROVIDE SOMEWHAT BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS...AND THIS IS INDICATED WITH 30-40 POPS COMPARED TO 20 POPS ON REMAINING DAYS. NORTHWEST FLOW ALOFT WILL BRING A SURFACE CANADIAN AIRMASS DOWN NEXT WEEK SUGGESTING HIGH TEMPERATURES WILL REMAIN SEASONAL IN THE 80S. && .AVIATION....FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1110 PM MDT WED AUG 7 2013 AS TEMPERATURES COOL TO SATURATION...LOW CEILINGS SHOULD BECOME PREDOMINANT BY SUNRISE...WITH OCCASIONAL REDUCTIONS IN VISIBILITY IN LIGHT RAIN AND/OR FOG. FLIGHT CATEGORIES WILL BE SLOW TO IMPROVE THURSDAY WITH MOIST CONDITIONS AND LIGHT SOUTHERLY WINDS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...FLASH FLOOD WATCH UNTIL 11 PM MDT /MIDNIGHT CDT/ THIS EVENING FOR KSZ027>029-041-042. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...DLF AVIATION...024
AREA FORECAST DISCUSSION
NWS JACKSON KY
1125 AM EDT THU AUG 8 2013 .UPDATE... ISSUED AT 1125 AM EDT THU AUG 8 2013 HEAVY RAINFALL DID NOT MATERIALIZE OVER THE FORECAST AREA THIS MORNING...BUT STAYED TO OUR SOUTHWEST. THE MAIN PORTION OF AN MCS REMAINED ANCHORED IN TN...WITH JUST DEBRIS/BLOW-OFF STREAMING OVER OUR SOUTHERN COUNTIES IN KY. NOT CONFIDENT IN HEAVY RAINFALL TODAY THROUGH FRIDAY...BUT WILL NOT DISPUTE THAT WITH THE HIGH MOISTURE CONTENT OF THE ATMOSPHERE...RECENT HISTORY TO OUR WEST...AND WEAK TO MODERATE LARGELY UNIDIRECTIONAL FLOW WITH HEIGHT...THAT SOME POTENTIAL FOR TRAINING AND HEAVY RAINFALL EXISTS. WITH FFA ALREADY IN PLACE...WILL LEAVE IT AS IS. HAVE REDUCED POPS A BIT FOR TODAY...HOLDING ON TO LIKELY CATEGORY IN OUR SOUTHEAST COUNTIES WHERE NUMEROUS SHOWERS WERE ONGOING LATE THIS MORNING...BUT ONLY USING 50 PERCENT POPS ELSEWHERE. UPDATE ISSUED AT 628 AM EDT THU AUG 8 2013 AFTER TALKING WITH NEIGHBORING OFFICES LMK AND RLX...AS WELL AS SEEING THE LATEST HPC QPF GUIDANCE...MADE THE DECISION TO ISSUE AN FFA FOR THE REGION THROUGH FRIDAY EVENING. SCT CONVECTION CONTINUES TO DEVELOP ALONG THE BOUNDARY CURRENTLY PUSHING SOUTH INTO KENTUCKY...WITH PWAT VALUES EXPECTED TO BE IN THE 2.0 AND ABOVE RANGE FOR A 6 HOUR TIME PERIOD BOTH THIS MORNING AND FRIDAY MORNING. WITH SOME OF THESE SHOWERS AND THUNDERSTORMS...RAIN RATES OF 2 TO 3 INCHES AN HOUR ARE VERY POSSIBLE. LOCALIZED FLASH FLOODING WILL BE A THREAT THEREFORE...ESPECIALLY IN AREAS THAT HAVE MULTIPLE STORMS PASS OVER THEIR LOCATION IN THE NEXT 48 HOURS. LATEST NAM IS ALSO TARGETING ANOTHER SWATH OF HEAVIER PRECIP MOVING INTO THE REGION SATURDAY MORNING...AFTER THE EXPIRATION OF THE FFA. THIS IS SUBJECT TO CHANGE WITH LATER MODEL RUNS...SO FIGURED IT WOULD BE EASIER TO EXTEND THE FFA IN THE FUTURE IF NEEDED RATHER THAN HAVE TO CANCEL IT AND END UP NEEDING TO REISSUE. THE LATEST SPENES PRODUCT FROM THE SATELLITE BRANCH ALSO PINPOINTED A LARGE SECTION OF OUR SOUTHWESTERN CWA IN THEIR AREA OF CONCERN FOR EXCESSIVE RAINFALL THIS MORNING. THIS JUST FURTHER SOLIDIFIED THE DECISION TO GO AHEAD AND ISSUE THE FFA FOR THE REGION. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE COLD FRONT THAT HAS REMAINED NEARLY STATIONARY JUST NORTH OF THE OHIO RIVER VALLEY YESTERDAY WILL FINALLY BEGIN ITS PUSH SEWARD ACROSS KY DURING THE DAY TODAY...REACHING THE SE PORTION OF THE STATE BY EVENING. AS WAS THE CASE WITH THIS SYSTEM YESTERDAY...HIGH HUMIDITY VALUES IN ADDITION TO THE ISENTROPIC LIFT PROVIDED BY THIS FRONT WILL WORK TO SPAWN CONVECTION...ESPECIALLY WITH THE ADDITION OF DAYTIME HEATING AND GREATER INSTABILITY. EXPECT A LARGE AREA OF SHOWERS AND POTENTIAL THUNDERSTORMS TO DEVELOP JUST AHEAD OF THE FRONT AND ENCOMPASS MUCH OF THE CWA...THEN SHIFT SLIGHTLY EASTWARD AS THE FRONT NEARS INTO THE REGION. CURRENT RADAR TRENDS ARE ALREADY SUPPORTING THIS IDEA...WITH SCATTERED SHOWERS CONTINUING TO DEVELOP ACROSS THE WESTERN HALF OF THE CWA. WHILE MODELS REMAIN FAIRLY CONSISTENT THAT PRECIP WILL OVERSPREAD THE AREA...THERE IS STILL SOME SUBTLE DIFFERENCES IN RESOLUTION AS TO WHERE THE HEAVIEST PRECIP WILL OCCUR. BASED ON THE LATEST HRRR AND NAM12...EXPECT BEST PRECIP DEVELOPMENT ACROSS THE SOUTHERN EXTENT OF THE CWA IN THE MORNING...SPREADING TO THE NORTH BY THE AFTERNOON. BY 0Z FRIDAY...FRONT WILL ONCE AGAIN BECOME STATIONARY...THIS TIME PARKING ITSELF ACROSS EASTERN KY. WITH SUCH HUMID AND UNSTABLE CONDITIONS IN PLACE...WILL CONTINUE WITH ONGOING FORECAST OF SOME SCT CONVECTIVE POSSIBILITY THROUGHOUT THE NIGHT...SINCE ANY STORM ONGOING IN THE AFTERNOON WILL TAKE SOME TIME TO DIE OFF...AND THERE IS ALWAYS THE POSSIBILITY THAT ANY LITTLE AREA OF LIFT COULD INITIATE SOME MORE SHOWERS. LUCKILY...WITH LOSS OF DAYTIME HEATING...BEST INSTABILITY AND THUNDERSTORM POTENTIAL WILL LESSON. HIGH DEW POINTS WILL ALSO LEAD TO LITTLE VARIATION FOR TEMPERATURES...WITH LOWS ONLY DROPPING TO AROUND 70. FRIDAY WILL BRING ABOUT SIMILAR CONDITIONS TO TODAY...WITH THE STATIONARY FRONT LIFTING SLIGHTLY JUST TO THE NORTH OF THE CWA. AN UPPER LEVEL SHORTWAVE MOVING THROUGH EASTERN KY BY FRIDAY MORNING WILL BE ENOUGH TO KICK START SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE REGION. WHILE PRECIPITABLE WATER VALUES WERE NEARING 2 INCHES FOR TODAY/S FORECAST...ACCORDING TO LATEST NAM12 SOUNDINGS...FRIDAY/S SOUNDINGS ARE POINTING AT WELL OVER 2.10 INCHES IN MANY LOCATIONS WITHIN A 6 HOUR PERIOD. IF A STRONG SHOWER OR THUNDERSTORM DEVELOPS AND MOVES OVER A PARTICULAR SITE...FLASH FLOODING IS A DEFINITE THREAT...ESPECIALLY IF THEY ARE IMPACTED BY TODAY/S CONVECTIVE ACTIVITY. MOST OF THIS MOISTURE IS EXPECTED TO FALL DURING THE MORNING AND EARLY AFTERNOON HOURS...WITH PWAT VALUES SLIGHTLY LESS...IN THE 1.5-2.0 RANGE IN THE AFTERNOON HOURS. TEMPERATURES SHOULD REMAIN FAIRLY SIMILAR TO TODAY WITH LITTLE CHANGE IN THE OVERALL PATTERN. SINCE A LOT OF THE EXPECTED PRECIP IS BASED ON MESOSCALE DEVELOPMENT...DISCUSSED THE IDEA OF ISSUING A FFA FOR THE AREA...BUT ULTIMATELY DECIDED TO HOLD OFF FOR RIGHT NOW. FUTURE SHIFTS MAY DECIDE TO PULL THE TRIGGER BASED ON HOW WIDESPREAD AND HEAVY THE DAY/S CONVECTIVE DEVELOPMENT PROVES TO BE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT ON THE GENERAL UPPER AIR PATTERN THAT WILL GUIDE OUR WEATHER THROUGH THE EXTENDED PORTION OF THE FORECAST. THIS CONSISTS PRIMARILY OF A DEEP AND PERSISTENT TROUGH OVER SOUTHEAST CANADA AND A FLAT RIDGE OVER THE SOUTHERN TIER OF THIS NATION. BETWEEN THESE...FAIRLY FAST MID LEVEL FLOW WILL CARRY SHORT WAVE ENERGY FROM THE WEST COAST THROUGH THE OHIO VALLEY BEFORE EXITING OFF THE EASTERN SEABOARD. THIS FLOW WILL BE FAIRLY ZONAL OVER KENTUCKY THROUGH THE WEEKEND BEFORE A WESTERN RESURGENCE IN THE CANADIAN TROUGH INDUCES A DIP SOUTH THROUGH THE GREAT LAKES AND INTO THE NORTHERN OHIO VALLEY. THIS WILL RESULT IN MORE OF A NORTHWEST FLOW PATTERN FOLLOWING THE WEEKEND INTO THE MIDDLE OF NEXT WEEK. THE GFS AND ECMWF DIFFER MOST DURING THE LATTER PORTION OF THE FORECAST AS THE ECMWF RUNS A BIT FASTER AND FURTHER EAST WITH THE CANADIAN LOW/S REDEVELOPMENT INTO THE DAY MONDAY. THE GFS TAKES THE CORE OF THIS LOW FURTHER SOUTH ON TUESDAY...DIPPING INTO THE STATES...BEFORE LIFTING IT JUST NORTH OF EAST. DURING THIS TIME OF LARGER GFS/ECMWF DISCREPANCY THE GEM SEEMS TO BE SIDING WITH THE ECMWF SO THE MORE EXTREME GFS SOLUTION FOR MONDAY TO WEDNESDAY WILL BE DISCOUNTED. ALSO...ITS RUN TO RUN CONSISTENCY HAS BEEN POOR...NOT THAT THE ECMWF HAS BEEN ALL THAT MUCH BETTER/JUST NOT SO OUT THERE AT TIMES...FOR THE LATTER PART OF THE EXTENDED. ACCORDINGLY...WILL FAVOR THE BLENDED RESULTS THROUGH THE WEEKEND BEFORE LEANING MORE TOWARD THE ECMWF INTO THE MIDDLE OF NEXT WEEK. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF OUR WET PATTERN THAT IS PRIMED FOR BOUTS OF HEAVY RAIN. THE SFC BOUNDARY WILL REMAIN STALLED THROUGH THE REGION INTO THE WEEKEND WITH EACH SFC WAVE RIPPLING PAST...POTENTIALLY SENDING THE BOUNDARY AND ITS HEAVIEST RAIN OUR WAY. HIGH PW AIR AND DAYTIME INSTABILITY WILL PROVIDE THE FUEL FOR THIS MCS ACTIVITY. THEREFORE...POPS WILL REMAIN HIGH INTO THE WEEKEND WITH MAX TEMPERATURES CAPPED BELOW NORMAL DUE TO CLOUDS AND CONVECTION. FOR THE START OF NEXT WEEK...IT LOOKS LIKE THE AMPLIFYING TROUGH ALOFT WILL BE ENOUGH TO EVENTUALLY PUSH THE FRONT SOUTH OF THE AREA AND ALLOW DRIER AIR TO FLOW INTO THE STATE. THE FAVORED 12Z ECMWF DOES TAKE THE DEEPER MOISTURE SOUTH LATER MONDAY WHILE THE GFS WAITS UNTIL A SECONDARY FRONT PUSHES THROUGH ON TUESDAY NIGHT. WILL CONTINUE SMALL POPS INTO TUESDAY FOR THIS TRANSITION...BUT NOT AS HIGH AS THE GFS WOULD IMPLY. HOPEFULLY WEDNESDAY WILL TURN OUT AS PLEASANT AS THE MODEL CONSENSUS SUGGESTS WITH A RETURN OF DECENT SUNSHINE AND MUCH DRIER AIR. WE WILL SEE... BUT AT LEAST THIS SEEMS TO BE A BUILDING AND STABILIZING ASPECT OF THE FORECAST FROM THE LATEST MEDIUM RANGE MODELS. THE CR GRID LOAD CAME IN NICELY FOR THIS UNSETTLED FORECAST THROUGH THE WEEKEND. DID TWEAK POPS TO ADD MORE OF A DIURNAL CYCLE AND ALSO TOWARD THE LATEST SPECIFICS FROM THE 12Z ECMWF FOR MONDAY ON INTO WEDNESDAY. ONLY MADE MINOR TERRAIN BASED ADJUSTMENTS FOR TEMPS THROUGHOUT THE BULK OF THIS EXTENDED PERIOD GIVEN THE HIGH MOISTURE CONTENT...AT LEAST THROUGH TUESDAY MORNING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 750 AM EDT THU AUG 8 2013 FOR THE MOST PART...EXPECT VFR CONDITIONS AT TAF SITES UNLESS INFLUENCED BY THE PASSAGE OF A RAIN SHOWER. BEST CONVECTIVE CHANCES WILL DEVELOP IN THE MORNING...WITH POSSIBLE MVFR CIGS EXPECTED AT ONSET. THE EXACT SET UP OF THESE STORMS IN RELATION TO HOW THEY WILL AFFECT THE TAF SITES IS STILL SOMEWHAT UNCERTAIN. IF A HEAVY SHOWER OR THUNDERSTORM DOES IMPACT A SITE DURING THE DAY...VIS COULD TEMPORARILY BE REDUCED BELOW MVFR. SHOWERS AND THUNDERSTORMS WILL DIE DOWN LATER THIS EVENING WITH LOSS OF DAYTIME HEATING...THOUGH SOME SCT CONVECTION IS STILL POSSIBLE THROUGH THE REMAINDER OF THE TAF PERIOD. MUCH LIKE THIS PAST NIGHT...EXPECT OVERALL CONDITIONS TO IMPROVE TO VFR WITH LOWER CONDITIONS EXPECTED IF A SHOWER OR LINGERING THUNDERSTORM PASSES OVER A TAF SITE. AS FAR AS FOG...SOME TEMPORARY BR IS BEING REPORTED AT KJKL IN CONJUNCTION WITH THE EARLIER RAIN INTERACTING WITH THE WARM HUMID CONDITIONS. LIKEWISE... FOR TONIGHT WITH EXTENSIVE CLOUD COVER EXPECTED ACROSS MUCH OF THE REGION...ANY WIDESPREAD FOG DEVELOPMENT IS UNLIKELY...ESPECIALLY TO A DEGREE THAT IT WILL SIGNIFICANTLY AFFECT THE TAF SITES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH FRIDAY EVENING FOR KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...HAL SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW/GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
750 AM EDT THU AUG 8 2013 .UPDATE... ISSUED AT 628 AM EDT THU AUG 8 2013 AFTER TALKING WITH NEIGHBORING OFFICES LMK AND RLX...AS WELL AS SEEING THE LATEST HPC QPF GUIDANCE...MADE THE DECISION TO ISSUE AN FFA FOR THE REGION THROUGH FRIDAY EVENING. SCT CONVECTION CONTINUES TO DEVELOP ALONG THE BOUNDARY CURRENTLY PUSHING SOUTH INTO KENTUCKY...WITH PWAT VALUES EXPECTED TO BE IN THE 2.0 AND ABOVE RANGE FOR A 6 HOUR TIME PERIOD BOTH THIS MORNING AND FRIDAY MORNING. WITH SOME OF THESE SHOWERS AND THUNDERSTORMS...RAIN RATES OF 2 TO 3 INCHES AN HOUR ARE VERY POSSIBLE. LOCALIZED FLASH FLOODING WILL BE A THREAT THEREFORE...ESPECIALLY IN AREAS THAT HAVE MULTIPLE STORMS PASS OVER THEIR LOCATION IN THE NEXT 48 HOURS. LATEST NAM IS ALSO TARGETING ANOTHER SWATH OF HEAVIER PRECIP MOVING INTO THE REGION SATURDAY MORNING...AFTER THE EXPIRATION OF THE FFA. THIS IS SUBJECT TO CHANGE WITH LATER MODEL RUNS...SO FIGURED IT WOULD BE EASIER TO EXTEND THE FFA IN THE FUTURE IF NEEDED RATHER THAN HAVE TO CANCEL IT AND END UP NEEDING TO REISSUE. THE LATEST SPENES PRODUCT FROM THE SATELLITE BRANCH ALSO PINPOINTED A LARGE SECTION OF OUR SOUTHWESTERN CWA IN THEIR AREA OF CONCERN FOR EXCESSIVE RAINFALL THIS MORNING. THIS JUST FURTHER SOLIDIFIED THE DECISION TO GO AHEAD AND ISSUE THE FFA FOR THE REGION. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE COLD FRONT THAT HAS REMAINED NEARLY STATIONARY JUST NORTH OF THE OHIO RIVER VALLEY YESTERDAY WILL FINALLY BEGIN ITS PUSH SEWARD ACROSS KY DURING THE DAY TODAY...REACHING THE SE PORTION OF THE STATE BY EVENING. AS WAS THE CASE WITH THIS SYSTEM YESTERDAY...HIGH HUMIDITY VALUES IN ADDITION TO THE ISENTROPIC LIFT PROVIDED BY THIS FRONT WILL WORK TO SPAWN CONVECTION...ESPECIALLY WITH THE ADDITION OF DAYTIME HEATING AND GREATER INSTABILITY. EXPECT A LARGE AREA OF SHOWERS AND POTENTIAL THUNDERSTORMS TO DEVELOP JUST AHEAD OF THE FRONT AND ENCOMPASS MUCH OF THE CWA...THEN SHIFT SLIGHTLY EASTWARD AS THE FRONT NEARS INTO THE REGION. CURRENT RADAR TRENDS ARE ALREADY SUPPORTING THIS IDEA...WITH SCATTERED SHOWERS CONTINUING TO DEVELOP ACROSS THE WESTERN HALF OF THE CWA. WHILE MODELS REMAIN FAIRLY CONSISTENT THAT PRECIP WILL OVERSPREAD THE AREA...THERE IS STILL SOME SUBTLE DIFFERENCES IN RESOLUTION AS TO WHERE THE HEAVIEST PRECIP WILL OCCUR. BASED ON THE LATEST HRRR AND NAM12...EXPECT BEST PRECIP DEVELOPMENT ACROSS THE SOUTHERN EXTENT OF THE CWA IN THE MORNING...SPREADING TO THE NORTH BY THE AFTERNOON. BY 0Z FRIDAY...FRONT WILL ONCE AGAIN BECOME STATIONARY...THIS TIME PARKING ITSELF ACROSS EASTERN KY. WITH SUCH HUMID AND UNSTABLE CONDITIONS IN PLACE...WILL CONTINUE WITH ONGOING FORECAST OF SOME SCT CONVECTIVE POSSIBILITY THROUGHOUT THE NIGHT...SINCE ANY STORM ONGOING IN THE AFTERNOON WILL TAKE SOME TIME TO DIE OFF...AND THERE IS ALWAYS THE POSSIBILITY THAT ANY LITTLE AREA OF LIFT COULD INITIATE SOME MORE SHOWERS. LUCKILY...WITH LOSS OF DAYTIME HEATING...BEST INSTABILITY AND THUNDERSTORM POTENTIAL WILL LESSON. HIGH DEWPOINTS WILL ALSO LEAD TO LITTLE VARIATION FOR TEMPERATURES...WITH LOWS ONLY DROPPING TO AROUND 70. FRIDAY WILL BRING ABOUT SIMILAR CONDITIONS TO TODAY...WITH THE STATIONARY FRONT LIFTING SLIGHTLY JUST TO THE NORTH OF THE CWA. AN UPPER LEVEL SHORTWAVE MOVING THROUGH EASTERN KY BY FRIDAY MORNING WILL BE ENOUGH TO KICK START SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE REGION. WHILE PRECIPITABLE WATER VALUES WERE NEARING 2 INCHES FOR TODAY/S FORECAST...ACCORDING TO LATEST NAM12 SOUNDINGS...FRIDAY/S SOUNDINGS ARE POINTING AT WELL OVER 2.10 INCHES IN MANY LOCATIONS WITHIN A 6 HOUR PERIOD. IF A STRONG SHOWER OR THUNDERSTORM DEVELOPS AND MOVES OVER A PARTICULAR SITE...FLASH FLOODING IS A DEFINITE THREAT...ESPECIALLY IF THEY ARE IMPACTED BY TODAY/S CONVECTIVE ACTIVITY. MOST OF THIS MOISTURE IS EXPECTED TO FALL DURING THE MORNING AND EARLY AFTERNOON HOURS...WITH PWAT VALUES SLIGHTLY LESS...IN THE 1.5-2.0 RANGE IN THE AFTERNOON HOURS. TEMPERATURES SHOULD REMAIN FAIRLY SIMILAR TO TODAY WITH LITTLE CHANGE IN THE OVERALL PATTERN. SINCE A LOT OF THE EXPECTED PRECIP IS BASED ON MESOSCALE DEVELOPMENT...DISCUSSED THE IDEA OF ISSUING A FFA FOR THE AREA...BUT ULTIMATELY DECIDED TO HOLD OFF FOR RIGHT NOW. FUTURE SHIFTS MAY DECIDE TO PULL THE TRIGGER BASED ON HOW WIDESPREAD AND HEAVY THE DAY/S CONVECTIVE DEVELOPMENT PROVES TO BE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT ON THE GENERAL UPPER AIR PATTERN THAT WILL GUIDE OUR WEATHER THROUGH THE EXTENDED PORTION OF THE FORECAST. THIS CONSISTS PRIMARILY OF A DEEP AND PERSISTENT TROUGH OVER SOUTHEAST CANADA AND A FLAT RIDGE OVER THE SOUTHERN TIER OF THIS NATION. BETWEEN THESE...FAIRLY FAST MID LEVEL FLOW WILL CARRY SHORT WAVE ENERGY FROM THE WEST COAST THROUGH THE OHIO VALLEY BEFORE EXITING OFF THE EASTERN SEABOARD. THIS FLOW WILL BE FAIRLY ZONAL OVER KENTUCKY THROUGH THE WEEKEND BEFORE A WESTERN RESURGENCE IN THE CANADIAN TROUGH INDUCES A DIP SOUTH THROUGH THE GREAT LAKES AND INTO THE NORTHERN OHIO VALLEY. THIS WILL RESULT IN MORE OF A NORTHWEST FLOW PATTERN FOLLOWING THE WEEKEND INTO THE MIDDLE OF NEXT WEEK. THE GFS AND ECMWF DIFFER MOST DURING THE LATTER PORTION OF THE FORECAST AS THE ECMWF RUNS A BIT FASTER AND FURTHER EAST WITH THE CANADIAN LOW/S REDEVELOPMENT INTO THE DAY MONDAY. THE GFS TAKES THE CORE OF THIS LOW FURTHER SOUTH ON TUESDAY...DIPPING INTO THE STATES...BEFORE LIFTING IT JUST NORTH OF EAST. DURING THIS TIME OF LARGER GFS/ECMWF DISCREPANCY THE GEM SEEMS TO BE SIDING WITH THE ECMWF SO THE MORE EXTREME GFS SOLUTION FOR MONDAY TO WEDNESDAY WILL BE DISCOUNTED. ALSO...ITS RUN TO RUN CONSISTENCY HAS BEEN POOR...NOT THAT THE ECMWF HAS BEEN ALL THAT MUCH BETTER/JUST NOT SO OUT THERE AT TIMES...FOR THE LATTER PART OF THE EXTENDED. ACCORDINGLY...WILL FAVOR THE BLENDED RESULTS THROUGH THE WEEKEND BEFORE LEANING MORE TOWARD THE ECMWF INTO THE MIDDLE OF NEXT WEEK. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF OUR WET PATTERN THAT IS PRIMED FOR BOUTS OF HEAVY RAIN. THE SFC BOUNDARY WILL REMAIN STALLED THROUGH THE REGION INTO THE WEEKEND WITH EACH SFC WAVE RIPPLING PAST...POTENTIALLY SENDING THE BOUNDARY AND ITS HEAVIEST RAIN OUR WAY. HIGH PW AIR AND DAYTIME INSTABILITY WILL PROVIDE THE FUEL FOR THIS MCS ACTIVITY. THEREFORE...POPS WILL REMAIN HIGH INTO THE WEEKEND WITH MAX TEMPERATURES CAPPED BELOW NORMAL DUE TO CLOUDS AND CONVECTION. FOR THE START OF NEXT WEEK...IT LOOKS LIKE THE AMPLIFYING TROUGH ALOFT WILL BE ENOUGH TO EVENTUALLY PUSH THE FRONT SOUTH OF THE AREA AND ALLOW DRIER AIR TO FLOW INTO THE STATE. THE FAVORED 12Z ECMWF DOES TAKE THE DEEPER MOISTURE SOUTH LATER MONDAY WHILE THE GFS WAITS UNTIL A SECONDARY FRONT PUSHES THROUGH ON TUESDAY NIGHT. WILL CONTINUE SMALL POPS INTO TUESDAY FOR THIS TRANSITION...BUT NOT AS HIGH AS THE GFS WOULD IMPLY. HOPEFULLY WEDNESDAY WILL TURN OUT AS PLEASANT AS THE MODEL CONSENSUS SUGGESTS WITH A RETURN OF DECENT SUNSHINE AND MUCH DRIER AIR. WE WILL SEE... BUT AT LEAST THIS SEEMS TO BE A BUILDING AND STABILIZING ASPECT OF THE FORECAST FROM THE LATEST MEDIUM RANGE MODELS. THE CR GRID LOAD CAME IN NICELY FOR THIS UNSETTLED FORECAST THROUGH THE WEEKEND. DID TWEAK POPS TO ADD MORE OF A DIURNAL CYCLE AND ALSO TOWARD THE LATEST SPECIFICS FROM THE 12Z ECMWF FOR MONDAY ON INTO WEDNESDAY. ONLY MADE MINOR TERRAIN BASED ADJUSTMENTS FOR TEMPS THROUGHOUT THE BULK OF THIS EXTENDED PERIOD GIVEN THE HIGH MOISTURE CONTENT...AT LEAST THROUGH TUESDAY MORNING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 750 AM EDT THU AUG 8 2013 FOR THE MOST PART...EXPECT VFR CONDITIONS AT TAF SITES UNLESS INFLUENCED BY THE PASSAGE OF A RAIN SHOWER. BEST CONVECTIVE CHANCES WILL DEVELOP IN THE MORNING...WITH POSSIBLE MVFR CIGS EXPECTED AT ONSET. THE EXACT SET UP OF THESE STORMS IN RELATION TO HOW THEY WILL AFFECT THE TAF SITES IS STILL SOMEWHAT UNCERTAIN. IF A HEAVY SHOWER OR THUNDERSTORM DOES IMPACT A SITE DURING THE DAY...VIS COULD TEMPORARILY BE REDUCED BELOW MVFR. SHOWERS AND THUNDERSTORMS WILL DIE DOWN LATER THIS EVENING WITH LOSS OF DAYTIME HEATING...THOUGH SOME SCT CONVECTION IS STILL POSSIBLE THROUGH THE REMAINDER OF THE TAF PERIOD. MUCH LIKE THIS PAST NIGHT...EXPECT OVERALL CONDITIONS TO IMPROVE TO VFR WITH LOWER CONDITIONS EXPECTED IF A SHOWER OR LINGERING THUNDERSTORM PASSES OVER A TAF SITE. AS FAR AS FOG...SOME TEMPORARY BR IS BEING REPORTED AT KJKL IN CONJUNCTION WITH THE EARLIER RAIN INTERACTING WITH THE WARM HUMID CONDITIONS. LIKEWISE... FOR TONIGHT WITH EXTENSIVE CLOUD COVER EXPECTED ACROSS MUCH OF THE REGION...ANY WIDESPREAD FOG DEVELOPMENT IS UNLIKELY...ESPECIALLY TO A DEGREE THAT IT WILL SIGNIFICANTLY AFFECT THE TAF SITES. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH FRIDAY EVENING FOR KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW/GREIF
AREA FORECAST DISCUSSION
NWS JACKSON KY
628 AM EDT THU AUG 8 2013 .UPDATE... ISSUED AT 628 AM EDT THU AUG 8 2013 AFTER TALKING WITH NEIGHBORING OFFICES LMK AND RLX...AS WELL AS SEEING THE LATEST HPC QPF GUIDANCE...MADE THE DECISION TO ISSUE AN FFA FOR THE REGION THROUGH FRIDAY EVENING. SCT CONVECTION CONTINUES TO DEVELOP ALONG THE BOUNDARY CURRENTLY PUSHING SOUTH INTO KENTUCKY...WITH PWAT VALUES EXPECTED TO BE IN THE 2.0 AND ABOVE RANGE FOR A 6 HOUR TIME PERIOD BOTH THIS MORNING AND FRIDAY MORNING. WITH SOME OF THESE SHOWERS AND THUNDERSTORMS...RAIN RATES OF 2 TO 3 INCHES AN HOUR ARE VERY POSSIBLE. LOCALIZED FLASH FLOODING WILL BE A THREAT THEREFORE...ESPECIALLY IN AREAS THAT HAVE MULTIPLE STORMS PASS OVER THEIR LOCATION IN THE NEXT 48 HOURS. LATEST NAM IS ALSO TARGETING ANOTHER SWATH OF HEAVIER PRECIP MOVING INTO THE REGION SATURDAY MORNING...AFTER THE EXPIRATION OF THE FFA. THIS IS SUBJECT TO CHANGE WITH LATER MODEL RUNS...SO FIGURED IT WOULD BE EASIER TO EXTEND THE FFA IN THE FUTURE IF NEEDED RATHER THAN HAVE TO CANCEL IT AND END UP NEEDING TO REISSUE. SPENES ALSO PINPOINTED A LARGE SECTION OF OUR SOUTHWESTERN CWA IN THEIR AREA OF CONCERN FOR EXCESSIVE RAINFALL THIS MORNING. THIS JUST FURTHER SOLIDIFIED THE DECISION TO GO AHEAD AND ISSUE THE FFA FOR THE REGION. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE COLD FRONT THAT HAS REMAINED NEARLY STATIONARY JUST NORTH OF THE OHIO RIVER VALLEY YESTERDAY WILL FINALLY BEGIN ITS PUSH SEWARD ACROSS KY DURING THE DAY TODAY...REACHING THE SE PORTION OF THE STATE BY EVENING. AS WAS THE CASE WITH THIS SYSTEM YESTERDAY...HIGH HUMIDITY VALUES IN ADDITION TO THE ISENTROPIC LIFT PROVIDED BY THIS FRONT WILL WORK TO SPAWN CONVECTION...ESPECIALLY WITH THE ADDITION OF DAYTIME HEATING AND GREATER INSTABILITY. EXPECT A LARGE AREA OF SHOWERS AND POTENTIAL THUNDERSTORMS TO DEVELOP JUST AHEAD OF THE FRONT AND ENCOMPASS MUCH OF THE CWA...THEN SHIFT SLIGHTLY EASTWARD AS THE FRONT NEARS INTO THE REGION. CURRENT RADAR TRENDS ARE ALREADY SUPPORTING THIS IDEA...WITH SCATTERED SHOWERS CONTINUING TO DEVELOP ACROSS THE WESTERN HALF OF THE CWA. WHILE MODELS REMAIN FAIRLY CONSISTENT THAT PRECIP WILL OVERSPREAD THE AREA...THERE IS STILL SOME SUBTLE DIFFERENCES IN RESOLUTION AS TO WHERE THE HEAVIEST PRECIP WILL OCCUR. BASED ON THE LATEST HRRR AND NAM12...EXPECT BEST PRECIP DEVELOPMENT ACROSS THE SOUTHERN EXTENT OF THE CWA IN THE MORNING...SPREADING TO THE NORTH BY THE AFTERNOON. BY 0Z FRIDAY...FRONT WILL ONCE AGAIN BECOME STATIONARY...THIS TIME PARKING ITSELF ACROSS EASTERN KY. WITH SUCH HUMID AND UNSTABLE CONDITIONS IN PLACE...WILL CONTINUE WITH ONGOING FORECAST OF SOME SCT CONVECTIVE POSSIBILITY THROUGHOUT THE NIGHT...SINCE ANY STORM ONGOING IN THE AFTERNOON WILL TAKE SOME TIME TO DIE OFF...AND THERE IS ALWAYS THE POSSIBILITY THAT ANY LITTLE AREA OF LIFT COULD INITIATE SOME MORE SHOWERS. LUCKILY...WITH LOSS OF DAYTIME HEATING...BEST INSTABILITY AND THUNDERSTORM POTENTIAL WILL LESSON. HIGH DEWPOINTS WILL ALSO LEAD TO LITTLE VARIATION FOR TEMPERATURES...WITH LOWS ONLY DROPPING TO AROUND 70. FRIDAY WILL BRING ABOUT SIMILAR CONDITIONS TO TODAY...WITH THE STATIONARY FRONT LIFTING SLIGHTLY JUST TO THE NORTH OF THE CWA. AN UPPER LEVEL SHORTWAVE MOVING THROUGH EASTERN KY BY FRIDAY MORNING WILL BE ENOUGH TO KICK START SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE REGION. WHILE PRECIPITABLE WATER VALUES WERE NEARING 2 INCHES FOR TODAY/S FORECAST...ACCORDING TO LATEST NAM12 SOUNDINGS...FRIDAY/S SOUNDINGS ARE POINTING AT WELL OVER 2.10 INCHES IN MANY LOCATIONS WITHIN A 6 HOUR PERIOD. IF A STRONG SHOWER OR THUNDERSTORM DEVELOPS AND MOVES OVER A PARTICULAR SITE...FLASH FLOODING IS A DEFINITE THREAT...ESPECIALLY IF THEY ARE IMPACTED BY TODAY/S CONVECTIVE ACTIVITY. MOST OF THIS MOISTURE IS EXPECTED TO FALL DURING THE MORNING AND EARLY AFTERNOON HOURS...WITH PWAT VALUES SLIGHTLY LESS...IN THE 1.5-2.0 RANGE IN THE AFTERNOON HOURS. TEMPERATURES SHOULD REMAIN FAIRLY SIMILAR TO TODAY WITH LITTLE CHANGE IN THE OVERALL PATTERN. SINCE A LOT OF THE EXPECTED PRECIP IS BASED ON MESOSCALE DEVELOPMENT...DISCUSSED THE IDEA OF ISSUING A FFA FOR THE AREA...BUT ULTIMATELY DECIDED TO HOLD OFF FOR RIGHT NOW. FUTURE SHIFTS MAY DECIDE TO PULL THE TRIGGER BASED ON HOW WIDESPREAD AND HEAVY THE DAY/S CONVECTIVE DEVELOPMENT PROVES TO BE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 413 AM EDT THU AUG 8 2013 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT ON THE GENERAL UPPER AIR PATTERN THAT WILL GUIDE OUR WEATHER THROUGH THE EXTENDED PORTION OF THE FORECAST. THIS CONSISTS PRIMARILY OF A DEEP AND PERSISTENT TROUGH OVER SOUTHEAST CANADA AND A FLAT RIDGE OVER THE SOUTHERN TIER OF THIS NATION. BETWEEN THESE...FAIRLY FAST MID LEVEL FLOW WILL CARRY SHORT WAVE ENERGY FROM THE WEST COAST THROUGH THE OHIO VALLEY BEFORE EXITING OFF THE EASTERN SEABOARD. THIS FLOW WILL BE FAIRLY ZONAL OVER KENTUCKY THROUGH THE WEEKEND BEFORE A WESTERN RESURGENCE IN THE CANADIAN TROUGH INDUCES A DIP SOUTH THROUGH THE GREAT LAKES AND INTO THE NORTHERN OHIO VALLEY. THIS WILL RESULT IN MORE OF A NORTHWEST FLOW PATTERN FOLLOWING THE WEEKEND INTO THE MIDDLE OF NEXT WEEK. THE GFS AND ECMWF DIFFER MOST DURING THE LATTER PORTION OF THE FORECAST AS THE ECMWF RUNS A BIT FASTER AND FURTHER EAST WITH THE CANADIAN LOW/S REDEVELOPMENT INTO THE DAY MONDAY. THE GFS TAKES THE CORE OF THIS LOW FURTHER SOUTH ON TUESDAY...DIPPING INTO THE STATES...BEFORE LIFTING IT JUST NORTH OF EAST. DURING THIS TIME OF LARGER GFS/ECMWF DISCREPANCY THE GEM SEEMS TO BE SIDING WITH THE ECMWF SO THE MORE EXTREME GFS SOLUTION FOR MONDAY TO WEDNESDAY WILL BE DISCOUNTED. ALSO...ITS RUN TO RUN CONSISTENCY HAS BEEN POOR...NOT THAT THE ECMWF HAS BEEN ALL THAT MUCH BETTER/JUST NOT SO OUT THERE AT TIMES...FOR THE LATTER PART OF THE EXTENDED. ACCORDINGLY...WILL FAVOR THE BLENDED RESULTS THROUGH THE WEEKEND BEFORE LEANING MORE TOWARD THE ECMWF INTO THE MIDDLE OF NEXT WEEK. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF OUR WET PATTERN THAT IS PRIMED FOR BOUTS OF HEAVY RAIN. THE SFC BOUNDARY WILL REMAIN STALLED THROUGH THE REGION INTO THE WEEKEND WITH EACH SFC WAVE RIPPLING PAST...POTENTIALLY SENDING THE BOUNDARY AND ITS HEAVIEST RAIN OUR WAY. HIGH PW AIR AND DAYTIME INSTABILITY WILL PROVIDE THE FUEL FOR THIS MCS ACTIVITY. THEREFORE...POPS WILL REMAIN HIGH INTO THE WEEKEND WITH MAX TEMPERATURES CAPPED BELOW NORMAL DUE TO CLOUDS AND CONVECTION. FOR THE START OF NEXT WEEK...IT LOOKS LIKE THE AMPLIFYING TROUGH ALOFT WILL BE ENOUGH TO EVENTUALLY PUSH THE FRONT SOUTH OF THE AREA AND ALLOW DRIER AIR TO FLOW INTO THE STATE. THE FAVORED 12Z ECMWF DOES TAKE THE DEEPER MOISTURE SOUTH LATER MONDAY WHILE THE GFS WAITS UNTIL A SECONDARY FRONT PUSHES THROUGH ON TUESDAY NIGHT. WILL CONTINUE SMALL POPS INTO TUESDAY FOR THIS TRANSITION...BUT NOT AS HIGH AS THE GFS WOULD IMPLY. HOPEFULLY WEDNESDAY WILL TURN OUT AS PLEASANT AS THE MODEL CONSENSUS SUGGESTS WITH A RETURN OF DECENT SUNSHINE AND MUCH DRIER AIR. WE WILL SEE... BUT AT LEAST THIS SEEMS TO BE A BUILDING AND STABILIZING ASPECT OF THE FORECAST FROM THE LATEST MEDIUM RANGE MODELS. THE CR GRID LOAD CAME IN NICELY FOR THIS UNSETTLED FORECAST THROUGH THE WEEKEND. DID TWEAK POPS TO ADD MORE OF A DIURNAL CYCLE AND ALSO TOWARD THE LATEST SPECIFICS FROM THE 12Z ECMWF FOR MONDAY ON INTO WEDNESDAY. ONLY MADE MINOR TERRAIN BASED ADJUSTMENTS FOR TEMPS THROUGHOUT THE BULK OF THIS EXTENDED PERIOD GIVEN THE HIGH MOISTURE CONTENT...AT LEAST THROUGH TUESDAY MORNING. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 137 AM EDT THU AUG 8 2013 SIMILAR SITUATION TO LAST NIGHT...WITH SCT PRECIP ACROSS THE AREA AND CLOUD HEIGHTS VARYING FROM POCKETS OF MVFR TO MID LEVEL VFR ACROSS THE AREA. WHERE THE TAF SITES WILL CONTINUE TO FALL WITHIN THIS PATTERN WILL BE THE MAIN CONCERN OVERNIGHT. FOR THE MOST PART...EXPECT VFR CONDITIONS AT TAF SITES UNLESS INFLUENCED BY THE PASSAGE OF A RAIN SHOWER. BEST CONVECTIVE CHANCES WILL DEVELOP IN THE MORNING...WITH POSSIBLE MVFR CIGS EXPECTED WITH ONSET. THE EXACT SET UP OF THESE STORMS IN RELATION TO HOW THEY WILL AFFECT THE TAF SITES IS STILL SOMEWHAT UNCERTAIN. IF A HEAVY SHOWER OR THUNDERSTORM DOES IMPACT A SITE DURING THE DAY...VIS COULD TEMPORARILY BE REDUCED BELOW MVFR. SHOWERS AND THUNDERSTORMS WILL DIE DOWN TOMORROW EVENING WITH LOSS OF DAYTIME HEATING...THOUGH SOME SCT CONVECTION IS STILL POSSIBLE THROUGH THE REMAINDER OF THE TAF PERIOD. MUCH LIKE TONIGHT...EXPECT OVERALL CONDITIONS TO IMPROVE TO VFR WITH SOME POSSIBLE ADJUSTMENTS IF A SHOWER OR LINGERING THUNDERSTORM PASSES OVER TAF SITE. AS FAR AS FOG OVERNIGHT...SOME TEMPORARY BR IS BEING REPORTED AT KJKL IN CONJUNCTION WITH THE RAIN THAT JUST PASSED OVER INTERACTING WITH THE WARM HUMID CONDITIONS. OTHERWISE...WITH CLOUD COVER ACROSS MUCH OF THE REGION...ANY WIDESPREAD FOG DEVELOPMENT IS UNLIKELY...ESPECIALLY TO A DEGREE THAT IT WILL AFFECT THE TAF SITES. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH FRIDAY EVENING FOR KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
1154 AM EDT THU AUG 8 2013 .SYNOPSIS... A WARM FRONT WILL LIFT INTO THE AREA TODAY AND STALL ACROSS THE HIGHER TERRAIN THROUGH FRIDAY. A COLD FRONT MOVES THROUGH ON FRIDAY AND FRIDAY EVENING. HIGH PRESSURE BUILDS IN FOR THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK. LOW PRESSURE WILL APPROACH FROM THE WEST IN THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... .UPDATE... PLENTY OF CLEARING/INSOLATION TO OUR WEST IN NY BUT LITTLE SUN THIS FAR EAST. SOME STORMS STILL EXPECTED LATER THIS AFTERNOON AND EVENING...ESPECIALLY OVER SOUTHERN NH AND NORTHERN MAINE WITH SURFACE TROUGH IN THE AREA. HAVE UPDATED TEMPERATURES...DEW POINTS...AND POPS. POPS WERE LOWERED QUITE A BIT AND ONLY EXPECTING 20-40% COVERAGE THIS EVENING. && PREVIOUS DISCUSSION... FIRST LINE OF SHOWERS HAS NOW EXITED THE FORECAST AREA. HAVE ADJUSTED POPS DOWN QUITE A BIT. MOST AREAS ARE STILL OVERCAST BUT THERE ARE A FEW BREAKS SHOWING UP IN NORTHERN NH. THIS TREND SHOULD CONTINUE AS NEXT SURFACE TROUGH ARRIVES LATER THIS AFTERNOON. SHOULD GET ENOUGH INSOLATION FOR A FEW STORMS DEVELOPING/MOVING OUT OF VT EARLY THIS AFTERNOON. HRRR INITIALIZES WELL AND HAVE FOLLOWED IT FOR THIS AFTERNOON`S CONVECTION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... ATTENTION THEN TURNS TO FNT STALLING ALONG OR S OF THE SRN CWFA BORDER. TO THE S WILL BE AN EXTREMELY MOIST AIR MASS...WITH PWAT VALUES INCREASING TO NEAR 2 INCHES. FOR THE GYX AREA THIS REPRESENTATION AOA +2 SD ABOVE NORMAL. HEAVY RNFL IS LIKELY WITH ANY CONVECTION...WITH EXTREME RNFL RATES AT TIMES. IN ADDITION...BOUNDARY WILL PROVIDE A FOCUS FOR TRAINING CELLS. ATTM UNCERTAINTY STILL EXISTS ON LOCATION FNT STALLS...BUT AS CONFIDENCE GROWS SOME SORT OF FLOOD/FLASH FLOOD HEADLINE MAY BE NECESSARY FOR A PORTION OF THE AREA. MUCH OF THAT MAY ALSO DEPEND ON WHERE HEAVY RAIN FALLS TODAY. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... A COLD FRONT WILL SLOWLY PUSH THROUGH THE REGION FRIDAY EVENING...SWEEPING THE HIGHER SURFACE DEW POINTS AND PRECIPITABLE WATER VALUES OFF THE COAST. MODELS STILL HAVE SOME ISSUES WITH THE TIMING OF THE PASSAGE OF THE FRONT. HAVE USED A BLEND BETWEEN THE VERY PROGRESSIVE...FAST MOVING FRONTAL PASSAGE WITH THE GFS/EURO SOLUTION...AND THE SLOWER FROPA WITH THE NAM/GGEM SOLUTION. SURFACE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SATURDAY. HOWEVER...STILL PLENTY OF COLD AIR AND CYCLONIC FLOW ALOFT ALLOWING FOR A FEW DIURNALLY DRIVEN SPRINKLES OR SCATTERED SHOWERS...MAINLY ACROSS THE HIGHER TERRAIN OF THE MOUNTAINS. THIS AIR MASS WILL BE NOTICEABLY COOLER AND DRIER. EXPECT CHILLY NIGHTS WITH PATCHY FOG AS THIS SYSTEM BUILDS OVERHEAD. MODELS IN GOOD AGREEMENT ADVANCING THE AREA OF HIGH PRESSURE OVER OUR REGION SUNDAY INTO MONDAY. BY TUESDAY...LOW PRESSURE WILL BEGIN TO EXIT THE GREAT LAKES REGION...BRINGING MORE SCATTERED SHOWERS TO OUR REGION DURING THE MIDWEEK PERIOD. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... SHORT TERM...CONDS EXPECTED TO DETERIORATE INTO GENERALLY MVFR CIGS AND VSBYS AS FNT APPROACHES TODAY. SOME LOCAL IFR IS PSBL IN NEAR COAST STRATUS OR SHRA/TSTM. IFR CONDS COULD BECOME MORE WIDESPREAD NEAR THE COAST AS FNT STALL TONIGHT AND FRI AND DEEPER MOISTURE WORKS NWD. LONG TERM...SHOWERS AND A FEW EMBEDDED THUNDERSTORMS EARLY FRIDAY EVENING MAY BRING MVFR TO IFR CONDITIONS. EXPECT IMPROVING CONDITIONS BEHIND A COLD FRONT FRIDAY NIGHT WITH VFR CONDITIONS CONTINUING INTO EARLY NEXT WEEK. && .MARINE... SHORT TERM...SUSTAINED ONSHORE FLOW WILL DEVELOP TODAY AHEAD OF AN APPROACHING FNT. THIS WILL GRADUALLY BUILD SEAS TO NEAR 5 FT BY LATE THIS EVENING...DESPITE WINDS REMAINING BLO 25 KTS. USED A BLEND OF THE NAM BASED SWAN WITH THE WNA4 IN THE FIRST PERIOD...AS GFS IS USUALLY TOO AGGRESSIVE WITH WINDS AND SEAS IN SLY FLOW. LONG TERM...SOUTHERLY FLOW WILL END FRIDAY EVENING. HOWEVER SEAS STILL EXPECTED TO BE RELATIVELY HIGH IN THE 4 TO 6 FOOT RANGE. THEREFORE....SMALL CRAFT ADVISORIES MAY STILL BE NEEDED THROUGH MUCH OF FRIDAY NIGHT AND POSSIBLY INTO EARLY SATURDAY MORNING. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ UPDATE...HANES
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
942 AM EDT THU AUG 8 2013 .SYNOPSIS... A WARM FRONT WILL LIFT INTO THE AREA TODAY AND STALL ACROSS THE HIGHER TERRAIN THROUGH FRIDAY. A COLD FRONT MOVES THROUGH ON FRIDAY AND FRIDAY EVENING. HIGH PRESSURE BUILDS IN FOR THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK. LOW PRESSURE WILL APPROACH FROM THE WEST IN THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FIRST LINE OF SHOWERS HAS NOW EXITED THE FORECAST AREA. HAVE ADJUSTED POPS DOWN QUITE A BIT. MOST AREAS ARE STILL OVERCAST BUT THERE ARE A FEW BREAKS SHOWING UP IN NORTHERN NH. THIS TREND SHOULD CONTINUE AS NEXT SURFACE TROUGH ARRIVES LATER THIS AFTERNOON. SHOULD GET ENOUGH INSOLATION FOR A FEW STORMS DEVELOPING/MOVING OUT OF VT EARLY THIS AFTERNOON. HRRR INITIALIZES WELL AND HAVE FOLLOWED IT FOR THIS AFTERNOON`S CONVECTION. && PREVIOUS DISCUSSION...FNT WILL APPROACH THE AREA TODAY AND BRING AT LEAST A COUPLE ROUNDS OF SHRA/TSTMS. EARLY TODAY AN INCREASINGLY MOISTENING ATMOSPHERE WILL RESULT IN CLOUDS SPREADING EWD AND THICKENING. ADDITIONALLY...WAA WILL SUPPORT WIDELY SCT SHRA ACROSS THE AREA THRU SUNRISE. A LINE OF SHRA AND TSTMS ALONG THE FNT WILL ALSO PUSH EWD INTO WRN ZONES IN THE NEXT SEVERAL HOURS. SO IN THE NEAR TERM HAVE TRIED TO TIME POP WITH THIS TREND...WHICH THE HRRR SEEM TO HAVE A DECENT HANDLE ON. A BLEND OF THAT AND THE LOCAL WRF WAS USED AS THE BASE FOR THE FIRST HALF OF THE DAY. AS THIS EARLY CONVECTION WEAKENS AND MOVES E...EXPECT THAT A FEW PARTIAL BREAKS IN THE OVERCAST WILL DEVELOP THIS AFTERNOON. IT IS THESE POCKETS OF SFC HEATING THAT WILL BECOME THE FOCUS FOR THE AFTERNOON FORECAST. LAPSE RATES ARE MARGINAL AT BEST...BUT DEW POINTS INCREASING TO THE UPR 60S TO NEAR 70 WILL SUPPORT MODERATE INSTABILITY FOR LOCATIONS THAT CAN GLIMPSE SOME SUNSHINE. AMPLE MID LVL WLY FLOW WILL SUPPORT ENOUGH EFFECTIVE SHEAR FOR SOME STORM ORGANIZATION. AT LEAST TRANSIENT SUPERCELL STRUCTURE WILL LEAD TO STRONGER CONVECTION CONTAINING GUSTY WINDS AND SMALL HAIL. GREATER THREAT IS PROBABLY WIND...AS DEEP...MOIST AIR MASS WILL BE MORE SUPPORTIVE OF MELTING HAIL. PCPN LOADING IN THE COLUMN AND STEEP LLVL LAPSE RATES WHERE SUN PEEKS OUT IS MORE THAN ENOUGH FOR SOME GUSTY DOWNDRAFTS. THIS HAS BEEN ADDED TO THE GRIDS...MAINLY ACROSS NH AND EXTREME WRN ME. NOT EXPECTING ANYTHING WIDESPREAD...BUT AN ISOLD SEVERE WX REPORT IS ENTIRELY PSBL TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... ATTENTION THEN TURNS TO FNT STALLING ALONG OR S OF THE SRN CWFA BORDER. TO THE S WILL BE AN EXTREMELY MOIST AIR MASS...WITH PWAT VALUES INCREASING TO NEAR 2 INCHES. FOR THE GYX AREA THIS REPRESENTATION AOA +2 SD ABOVE NORMAL. HEAVY RNFL IS LIKELY WITH ANY CONVECTION...WITH EXTREME RNFL RATES AT TIMES. IN ADDITION...BOUNDARY WILL PROVIDE A FOCUS FOR TRAINING CELLS. ATTM UNCERTAINTY STILL EXISTS ON LOCATION FNT STALLS...BUT AS CONFIDENCE GROWS SOME SORT OF FLOOD/FLASH FLOOD HEADLINE MAY BE NECESSARY FOR A PORTION OF THE AREA. MUCH OF THAT MAY ALSO DEPEND ON WHERE HEAVY RAIN FALLS TODAY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A COLD FRONT WILL SLOWLY PUSH THROUGH THE REGION FRIDAY EVENING...SWEEPING THE HIGHER SURFACE DEW POINTS AND PRECIPITABLE WATER VALUES OFF THE COAST. MODELS STILL HAVE SOME ISSUES WITH THE TIMING OF THE PASSAGE OF THE FRONT. HAVE USED A BLEND BETWEEN THE VERY PROGRESSIVE...FAST MOVING FRONTAL PASSAGE WITH THE GFS/EURO SOLUTION...AND THE SLOWER FROPA WITH THE NAM/GGEM SOLUTION. SURFACE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SATURDAY. HOWEVER...STILL PLENTY OF COLD AIR AND CYCLONIC FLOW ALOFT ALLOWING FOR A FEW DIURNALLY DRIVEN SPRINKLES OR SCATTERED SHOWERS...MAINLY ACROSS THE HIGHER TERRAIN OF THE MOUNTAINS. THIS AIR MASS WILL BE NOTICEABLY COOLER AND DRIER. EXPECT CHILLY NIGHTS WITH PATCHY FOG AS THIS SYSTEM BUILDS OVERHEAD. MODELS IN GOOD AGREEMENT ADVANCING THE AREA OF HIGH PRESSURE OVER OUR REGION SUNDAY INTO MONDAY. BY TUESDAY...LOW PRESSURE WILL BEGIN TO EXIT THE GREAT LAKES REGION...BRINGING MORE SCATTERED SHOWERS TO OUR REGION DURING THE MIDWEEK PERIOD. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... SHORT TERM...CONDS EXPECTED TO DETERIORATE INTO GENERALLY MVFR CIGS AND VSBYS AS FNT APPROACHES TODAY. SOME LOCAL IFR IS PSBL IN NEAR COAST STRATUS OR SHRA/TSTM. IFR CONDS COULD BECOME MORE WIDESPREAD NEAR THE COAST AS FNT STALL TONIGHT AND FRI AND DEEPER MOISTURE WORKS NWD. LONG TERM...SHOWERS AND A FEW EMBEDDED THUNDERSTORMS EARLY FRIDAY EVENING MAY BRING MVFR TO IFR CONDITIONS. EXPECT IMPROVING CONDITIONS BEHIND A COLD FRONT FRIDAY NIGHT WITH VFR CONDITIONS CONTINUING INTO EARLY NEXT WEEK. && .MARINE... SHORT TERM...SUSTAINED ONSHORE FLOW WILL DEVELOP TODAY AHEAD OF AN APPROACHING FNT. THIS WILL GRADUALLY BUILD SEAS TO NEAR 5 FT BY LATE THIS EVENING...DESPITE WINDS REMAINING BLO 25 KTS. USED A BLEND OF THE NAM BASED SWAN WITH THE WNA4 IN THE FIRST PERIOD...AS GFS IS USUALLY TOO AGGRESSIVE WITH WINDS AND SEAS IN SLY FLOW. LONG TERM...SOUTHERLY FLOW WILL END FRIDAY EVENING. HOWEVER SEAS STILL EXPECTED TO BE RELATIVELY HIGH IN THE 4 TO 6 FOOT RANGE. THEREFORE....SMALL CRAFT ADVISORIES MAY STILL BE NEEDED THROUGH MUCH OF FRIDAY NIGHT AND POSSIBLY INTO EARLY SATURDAY MORNING. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ UPDATE...HANES
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
725 AM EDT THU AUG 8 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 518 AM EDT THU AUG 8 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP MID LEVEL LOW OVER NRN ONTARIO JUST E OF THE MANITOBA/ONTARIO BORDER. FOR THIS TIME OF YEAR...THE LOW IS UNUSUALLY DEEP WITH 500MB HEIGHTS 2.5 STANDARD DEVIATIONS BELOW THE LONG TERM AVG. THE UPPER LAKES ARE UNDER THE SRN PORTION OF ITS RATHER EXPANSIVE CIRCULATION. IN THE WAKE OF THE SHORTWAVES THAT PASSED ACROSS THE UPPER LAKES YESTERDAY...A DRY AIR MASS HAS PUSHED INTO UPPER MI. COMBINED WITH CLEAR SKIES AND LIGHT/CALM WIND...TEMPS HAVE ONCE AGAIN DIPPED AS LOW AS THE UPPER 30S IN SOME OF THE TRADITIONAL COLD SPOTS IN THE INTERIOR (DOE LAKE AND SPINCICH LAKE IN PARTICULAR). JUST TO THE W...A SHORTWAVE THAT WAS MUCH MORE WELL DEFINED YESTERDAY AFTN HAS WEAKENED/SHEARED E INTO MN...AND IT IS SPREADING A BAND OF MID CLOUDS ACROSS NRN MN AND WRN LAKE SUPERIOR. AFTER DIMINISHING...A BAND OF SHRA HAS REDEVELOPED ACROSS NRN MN IN ASSOCIATION WITH THE SHORTWAVE. TO THE NW OVER MANITOBA...A SHORTWAVE SPOKE IS EVIDENT ROTATING AROUND THE DEEP MIDLEVEL LOW OVER NRN ONTARIO. BOTH OF THESE SHORTWAVES WILL HAVE SOME IMPACT ON THE WEATHER HERE TODAY/TONIGHT. FIRST UP...THE WEAKENING SHORTWAVE OVER MN WILL PASS ACROSS THE AREA THIS MORNING. SEVERAL OF THE HIGH RES MODELS INCLUDING NAM AND HIGH RES WRF-ARW/WRF-NMM HAVE DONE A NICE JOB PICKING UP ON THE LOCATION OF SHRA TO THE W AND SUGGEST SHRA WILL TEND TO DISSIPATE AS THEY SHIFT E INTO WRN UPPER MI THIS MORNING. WILL GENERALLY FOLLOW THIS IDEA AND SPREAD ISOLD -SHRA INTO PORTIONS OF WRN UPPER MI THIS MORNING. DURING THE AFTN...NEXT SHORTWAVE CURRENTLY ROTATING THRU SRN MANITOBA SHOULD PROVIDE FORCING FOR ISOLD TO PERHAPS SCT AFTN CONVECTION WITH LAKE BREEZES PROVIDING A LOW LEVEL FOCUS AS WELL. WITH MLCAPES ONLY UP TO A COUPLE HUNDRED J/KG...THUNDER POTENTIAL IS MINIMAL...BUT PROBABLY STILL WORTHY OF INCLUDING MENTION IN FCST. ISOLD/SCT SHRA SHOULD SLOWLY SHIFT E AND SE TONIGHT AS PRONOUNCED MID LEVEL DRYING PUSHES IN FROM THE W. THIS SHOULD ALSO LEAD TO CLEARING OVER AT LEAST THE W HALF OR SO OF THE FCST AREA. LEANED SOMEWHAT TOWARD THE LOWER SIDE OF AVBL GUIDANCE FOR MINS OVER THE W WITH EXPECATION OF CLEARING AND A DRYING COLUMN. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 518 AM EDT THU AUG 8 2013 OMEGA BLOCKING FROM ALASKA TO EASTERN CANADA WILL FINALLY BEGIN TO BREAKDOWN...ALBEIT SLOWLY...BY THIS WEEKEND. BESIDE A CHANCE FOR SHOWERS AND STORMS SUNDAY AFTERNOON INTO MONDAY NIGHT...THE LONG TERM TREND WILL BE DRY AND SLIGHTLY COOLER THAN NORMAL. FRIDAY THROUGH SATURDAY NIGHT...A DEEP CLOSED MID-LEVEL LOW OVER NORTHERN ONTARIO WILL BE SENDING A SHORTWAVE TROUGH ACROSS THE CWA THURSDAY NIGHT. THE ASSOCIATED COLD FRONT IS PROGGED TO CLEAR THE CWA BY 12Z FRIDAY...WITH MUCH DRIER AIR USHERING IN BEHIND IT. SOME LOW-LEVEL MOISTURE COULD LINGER ACROSS THE EAST HALF AFTER 12Z UNDER INCREASING SUBSIDENCE BEHIND THE FRONT...SO KEPT SLIGHT CHANCE POPS FOR A FEW HOURS BEYOND 12Z FOR THE FAR EAST. THE MAIN TROUGH AXIS WILL THEN PUSH SOUTHEASTWARD ACROSS THE CWA FRIDAY AFTERNOON INTO LATE FRIDAY NIGHT. WHILE MOISTURE IS LACKING IN THE MID-LEVELS...H8 TO H7 FGEN UNDER MODEST MID-LEVEL Q-VECTOR CONVERGENCE WILL LEAD TO INCREASED CLOUDINESS BELOW H5. THE NAM IS THE ONLY MODEL TO INDICATE A SHOT AT ISOLATED SHOWERS ACROSS THE NORTH CLOSER TO THE MAIN FORCING. HAVE OPTED TO KEEP ANY PRECIP OUT OF THE FORECAST FOR NOW GIVEN VERY DRY LOW LEVELS AND THAT MOST MODELS HAVE BEEN CONSISTENT WITH ALL PRECIP REMAINING OUT OF THE CWA. MODEL TRENDS HAVE ALSO SHOWED A STRONGER PRESSURE GRADIENT...ESPECIALLY NORTH....WITH THE TROUGH PASSAGE. WEAK STABILITY SUGGESTS THAT MIXING COULD BRING GUSTY WNW OF UP TO 25 MPH TO MUCH OF THE NORTH HALF BY THE AFTERNOON. SFC HIGH PRESSURE WILL THEN BUILD INTO THE UPPER GREAT LAKES WITH MID-LEVEL SHORTWAVE RIDGING FRIDAY NIGHT THROUGH SATURDAY. GENERALLY CLEAR SKIES AND LOW PWATS OF AROUND 0.5 INCHES WILL BE CONDUCIVE FOR GOOD RADIATIONAL COOLING ACROSS MUCH OF THE CWA...PARTICULARLY THE INTERIOR WEST HALF. HAVE FOLLOWED THE PREVIOUS SHIFTS TREND OF LOWERING TEMPS. WIDESPREAD 40S ARE LIKELY FOR ALL BUT THE IMMEDIATE GREAT LAKES SHORELINES. WEAK LOW-LEVEL MOISTURE RETURN WILL BEGIN ACROSS THE WEST SATURDAY AFTERNOON AS THE SFC HIGH MOVES EAST. WITH THIS MOISTURE INCREASE...AFTERNOON CUMULUS DEVELOPMENT WILL BE COMMON. A FEW ISOLATED DIURNAL SHOWERS COULD EVEN BE POSSIBLE...BUT ONCE AGAIN...CONFIDENCE IS TOO LOW TO INTRODUCE ANY PRECIP ATTM. LOW TO MID-LEVEL CLOUDINESS WILL CONTINUE TO INCREASE WITH THE MOISTURE RETURN SATURDAY NIGHT...KEEPING TEMPS SEVERAL DEGREES WARMER THAN FRIDAY NIGHT. SUNDAY THROUGH MONDAY...ANOTHER SHORTWAVE TROUGH ON THE BACKSIDE OF THE DEEP EASTERN CANADIAN MID-LEVEL TROUGH WILL BE DIGGING SOUTHWARD ACROSS FAR WESTERN ONTARIO LATE SATURDAY NIGHT. THE ECMWF HAS SLOWED THIS TROUGH PASSAGE OVER THE LAST FEW RUNS...AND NOW LINES UP WELL WITH THE GFS IN BRINGING THE MAIN TROUGH AXIS THROUGH MONDAY EVENING. BOTH MODELS HAVE ALSO RECENTLY PICKED UP ON A WEAK LEAD SHORTWAVE TROUGH FROM PHASING BETWEEN A PORTION OF THE MAIN TROUGH AND A WEAK WAVE MOVING EASTWARD FROM WESTERN CANADA. THE TIMING OF THIS WEAK WAVE IS A LITTLE DIFFERENT BETWEEN THE TWO MODELS...WITH THE CONSENSUS BEING EARLY SUNDAY EVENING. INSTABILITY WILL BE QUITE POOR NORTH OF THE WI BORDER AND SHOULD PRECLUDE ANY STRONG THUNDERSTORM THREAT ATTM. THE TROUGH WILL CONTINUE TO SLOWLY WORK EASTWARD ACROSS THE CWA AND BRING ISOLATED TO SCATTERED SHOWERS THROUGH MONDAY AFTERNOON. MONDAY NIGHT THROUGH WEDNESDAY...BY THIS POINT...THE ECMWF AND GFS HAVE SOME DISAGREEMENT ON THE STRENGTH OF THE SHORTWAVE...AND HOW QUICK IT WILL DEPART. THE ECMWF IS MUCH QUICKER AND BRINGS GENERALLY DRY CONDITIONS THROUGH WEDNESDAY. THE GFS SWINGS A STRONG SECONDARY TROUGH ACROSS THE EASTERN CWA ON TUESDAY...BUT LIMITS SHOWERS TO ONLY THE EAST HALF. STUCK WITH OVERALL MODEL CONSENSUS FOR NOW...THROUGH MUCH OF THE PERIOD SHOULD REMAIN DRY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 724 AM EDT THU AUG 8 2013 VFR CONDITIONS WILL PERSIST THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW AS AIR MASS REMAINS DRY IN THE LOW-LEVELS. A COUPLE OF DISTURBANCES WILL BRING THE POTENTIAL FOR A FEW -SHRA...FIRST OVER WRN UPPER MI THIS MORNING AND THEN MAINLY OVER CNTRL UPPER MI THIS AFTN/EVENING. PER RADAR TRENDS...IT APPEARS THAT IF -SHRA/SPRINKLES CURRENTLY OVER WRN LAKE SUPERIOR HOLD TOGETHER...THEY WILL PASS BTWN KIWD/KCMX THIS MORNING. EVEN IF PCPN REACHES EITHER TERMINAL...CONDITIONS WILL REMAIN VFR. CONFIDENCE IN PLACEMENT/COVERAGE OF ANY AFTN -SHRA IN CNTRL UPPER MI IS TOO LOW RIGHT NOW TO WARRANT ANYTHING MORE THAN A MENTION OF VCSH AT KSAW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 518 AM EDT THU AUG 8 2013 EXPECT WINDS UNDER 20KT ACROSS LAKE SUPERIOR TODAY/TONIGHT UNDER A GENERALLY WEAK PRES GRADIENT. HOWEVER...WINDS WILL BEGIN TO INCREASE OVERNIGHT TONIGHT AHEAD OF THE NEXT COLD FRONT DROPPING SE. AN INCREASING PRESSURE GRADIENT BETWEEN HIGH PRESSURE BUILDING IN FROM SOUTH CENTRAL CANADA AND LOW PRESSURE EXITING TO THE EAST ACROSS EASTERN ONTARIO WILL CREATE W TO WNW WINDS OF 15 TO 25 KNOTS ACROSS WESTERN LAKE SUPERIOR FRIDAY MORNING...AND CENTRAL AND EASTERN LAKE SUPERIOR FRIDAY AFTERNOON. WEST WINDS UNDER 15 KNOTS WILL THEN BE THE RULE THROUGH THE WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE UPPER GREAT LAKES. ANOTHER TROUGH WILL CROSS LAKE SUPERIOR ON MONDAY AND BRING NW WINDS UNDER 15 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...KLUBER AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1010 AM CDT Thu Aug 8 2013 .UPDATE: Issued at 1004 AM CDT Thu Aug 8 2013 Have updated forecast to reflect that area of showers and thunderstorms over the Ozarks continues to moves east and slightly north. In addition, scattered thunderstorms have developed recently along the across Gasconade and Franklin counties. Latest runs of the HRRR and RAP are showing that a low level moisture convergence maximum will move east into southern Illinois later this morning. Now believe that north edge of the rain will move north to about the Missouri River before diminishing with greatest chances shifting eastward from the Ozarks into southern Illinois. Will keep with the idea that areal coverage of the rain will diminish early-mid afternoon. Then the atmosphere will become increasing unstable by late afternoon, particularly over southern Missouri at the same time that low level moisture convergences increases from southern Missouri into central Missouri between 21-00Z. HRRR reflectivity shows that discrete storms may initially develop late this afternoon into early this evening. A few severe thunderstorms will be possible depending on the amount of instability that is able to work into the area. Storms will also be possible of producing heavy rainfall rates. Britt && .SHORT TERM: (Through Sunday) Issued at 404 AM CDT Thu Aug 8 2013 Cold front is now over southern portions of forecast area early this morning. Storms that had fired along it have long since dissipated. Otherwise...storms have fired on nose of low level jet once again, but further south over far southwestern Missouri. Also, an MCS has developed over north central Oklahoma and it`s associated MCV will continue to track to the east along frontal boundary today. So will see scattered storms fire and move along front, making some progress to the north, but remain along and south of I-70. Because of the light surface winds and plenty of low level moisture, some patchy dense fog has developed over far southern and eastern portions of forecast area this morning, but should dissipate as high and mid clouds move in later this morning. As for high temperatures, low to mid 80s a good bet. By tonight, models continue to develop another MCS over eastern Kansas and slide it east, but have differing opinions on placement of system, with NAM the furthest north. Will go with a blend of the models and keep likely pops going for tonight for a good portion of the forecast area, but back off main area of activity til after 06z and continue through day on Friday before tapering off Friday night. Will see decent qpf amounts, but placement of heaviest rains still hard to pin down, so will not issue a Flash Flood Watch at this time. One may be needed for late tonight through Friday, especially for central and southern portions of forecast area. Lows tonight will be in the mid 60s to around 70 with highs on Friday in the upper 70s to mid 80s. Weak surface ridge is still expected to build in for the weekend and into early next week, so precipitation chances to shift off to the south, though kept chance pops for southeast Missouri and far southwestern Illinois through Sunday. Highs to remain below normal in the low to mid 80s through the weekend. Byrd .LONG TERM: (Sunday Night through Wednesday) Issued at 404 AM CDT Thu Aug 8 2013 Surface ridge to move off to the east ahead of next weather system by Monday, so have chances of showers and thunderstorms across the area on Monday as system moves through, tapering off Monday night. Then dry conditions return to the region for the rest of the forecast period with below normal temperatures. Byrd && .AVIATION: (For the 12z TAFs through 12z Friday Morning) Issued at 642 AM CDT Thu Aug 8 2013 Areas of ifr cigs are floating around far eastern missouri early this morning while they become more continuous into illinois. this low cloud may impact the st louis area taf sites through 14z then expecting generally vfr conditions with scattered cu and high clouds to prevail through the evening. the exception to this is central missouri and kcou where I`m still expecting vfr conditions but some showers could move into around midday and last for several hours. for tonight mvfr cigs should redevelop across the area late tonight with showers and maybe a few thunderstorms spreading from west to east. Specifics for KSTL: Areas of ifr cigs are floating around far eastern missouri early this morning and they could impact the terminal through 14z. thereafter expecting generally vfr conditions with scattered cu and high clouds to prevail through the evening. mvfr cigs should redevelop across the area late tonight with showers and maybe a few thunderstorms spreading in from the west near daybreak friday. Glass && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
647 AM CDT Thu Aug 8 2013 .SHORT TERM...(Today through Friday) Issued at 322 AM CDT THU AUG 8 2013 Another night of conceptual forecasting as none of the 00Z solutions have initialized the anticipated MCS riding along the KS/OK border, and continue to poorly handle the subtle but key features emanating out of the western trough each afternoon. The HRRR continues to perform exceptionally well (albeit slow on timing), but its short- term guidance only goes so far. In any case, 07Z surface analysis depicts a strongly convergent frontal zone across nrn OK/AR with the greatest lift once again focused about 50 miles north of this boundary. A secondary elevated boundary, roughly juxtaposed with the southern extent of dry surface air, extends NE from Wichita to Clinton to Jefferson City. Developing MCV along over SW KS will likely begin to make the turn ENE along this northern boundary. With that said, dry northeasterly flow should keep most of the CWA quiet through daybreak. Much like the past several nights, a sub- synoptic occlusion should occur as the eastward advancing MCS overtakes the W-E stationary front. This would place the southwestern zones under the best chances for thunder by 12Z, with a rapid transition to a stratiform rain/embedded thunder event as an enlarging precipitation shield pushes into the dry air over east central KS/west central MO. A well-defined MCV should lift slowly across the southern CWA during the day, with QPF diminishing. The MCV passage will mark the return of deeper warm/air moisture advection that will place us back in a preferred zone for deep moist convection tonight and Friday. As for highs today, generally went around 80 across the board. Despite better chances for sunshine over the NE CWA (at least early), CAA should yield similar readings as points further south. Convective debris/showers should limit insolation over the srn CWA through the morning, but expect some PM sun to boost them back up. For tonight, the large scale mid-level trough will begin to finally eject out of the central Rockies, establishing a surface low across OK. Deepening southwesterly flow aloft will lift the surface warm front back to near I-44. This will place the southern CWA in a precarious region of strong deep layer ascent/convergence amidst increasing moisture advection. Based only on persistence from the past 4-5 days, greatest QPF should fall in the 06-15Z time frame Friday. Given the frontogenetic forcing, upper support and boundary- relative shear profiles, have significantly bumped POPs and QPF from 06Z-18Z Friday. A flash flood watch will likely be required south of the MO river given antecedent rainfall and prospects for very heavy rainfall tonight/Friday morning. Highs Friday honestly a hedge toward some afternoon clearing, but could conceivably end up in the low-mid 70s if this doesn`t occur. Friday Night remains the biggest question mark given the large model spread in timing of the upper trough passage. Areas along/ahead of this mid level wind shift certainly remain under the gun for additional precipitation and have retained moderate POPs across all but far NW MO for that reason. .LONG TERM...(Saturday through Wednesday) Issued at 322 AM CDT THU AUG 8 2013 The upcoming weekend should remain dry as the region will fall under the influence of high pressure moving southeast through the Great Lakes. With little change in the synoptic pattern and a continuance of progressive zonal to northwesterly flow heading into into next week, it appears there will only be a short break to the rainfall in the region. By Monday, upper troughing will temporarily deepen over Manitoba and Ontario, pushing a weak shortwave into the Central Plains. Increasing warm advection ahead of this wave will induce showers and thunderstorms over a large area of the central CONUS Monday into Monday night. Have increased PoPs from late Sunday night into Tuesday morning. Latest guidance suggests a cold front will sweep southward through the region by Tuesday morning, with high pressure once again moving into the western Great Lakes providing dry conditions to the local area. As far as temperatures are concerned, warm advection and southwesterly surface flow on Sunday will push temperatures back towards seasonal normals. However, past the frontal passage on Tuesday, temperatures will likely remain below normal into the middle of next week. && .AVIATION...(For the 12Z TAFS through 12Z Friday Morning) Issued at 644 AM CDT THU AUG 8 2013 Mesoscale convective complex continues to move ENE across southern KS early this morning. As cloud tops have begun to warm, sharp linear convection has now broadened into an expanding area of stratiform rain with embedded thunder. This precipitation will be moving into an area of drier air, so uncertainty remains as to how far northeast lightning will persist as the system approaches. Since conditions will otherwise be VFR, this is really the only aspect of this MCC that is impactful to the terminals this morning. For now went with a tempo group for thunder across the KC terminals from 14-16Z based on linear extrapolation. Otherwise, as the system decays, winds should remain east-northeast to northeast at 6-8 knots, with speeds slowly increasing tonight ahead of the next disturbance. Conditions appear favorable, especially south of Kansas City, for an organized thunderstorm complex once again after midnight. Outlook period of the TAF reflects a somewhat higher confidence for rain/embedded thunder and perhaps some lower ceilings after midnight. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...FLASH FLOOD WATCH from late tonight through Friday morning FOR KSZ057-060-105. MO...FLASH FLOOD WATCH from late tonight through Friday morning FOR MOZ037>040-043>046-053-054. && $$ SHORT TERM...Bookbinder LONG TERM...Dux AVIATION...Bookbinder
AREA FORECAST DISCUSSION
NWS GLASGOW MT
905 AM MDT THU AUG 8 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY... FAIRLY QUIET AND RELATIVELY STABLE ATMOSPHERE OVER THE REGION THIS MORNING. DOESN/T LOOK LIKE SHOWER/THUNDERSTORM ACTIVITY THIS MORNING WILL BE GENERATED SO REMOVED THEM...BUT DID EXPAND A BIT ACROSS THE NORTHERN ZONES FOR THE AFTERNOON. WILL AGAIN LEAN ON THE HRRR AND RAP (RUC) MODELS AS THEY HAVE DONE BETTER AS OF LATE. TFJ PREVIOUS DISCUSSION... NORTHWEST FLOW ALOFT WILL CONTINUE TODAY WITH DEEP UPPER LOW OVER WESTERN ONTARIO AND UPPER RIDGE OVER IDAHO. SHORTWAVE TROUGH OVER SOUTHERN ALBERTA IS BRING SOME SHOWERS AND THUNDERSTORMS TO THAT AREA AND TO A LESSER DEGREE NORTH CENTRAL MONTANA. THE SHOWERS HAVE BEEN DISSIPATING WHEN THEY GET TO THE HAVRE AREA OVERNIGHT. HOWEVER... WITH THE WAVE MOVING TO THE EAST... A FEW OF THESE SHOWERS/T-STORMS COULD MAKE INTO THE NORTHERN PARTS OF THE FORECAST AREA THIS MORNING. WILL MENTION ISOLATED SHOWERS AND THUNDERSTORMS. SURFACE HIGH BUILDS INTO THE AREA FROM THE NORTH THIS AFTERNOON WITH DRY WEATHER. THE UPPER LOW MOVES TO THE EAST TONIGHT AND FRIDAY AND UPPER RIDGE BUILDS INTO MONTANA. WITH AN UPPER TROUGH/CUT OFF LOW OVER CALIFORNIA...SOUTHERLY FLOW ALOFT TO THE SOUTH OF MONTANA WILL ALLOW MONSOONAL MOISTURE TO ADVECT NORTH INTO THE STATE. THIS MOISTURE WILL MAKE INTO THE SOUTHERN ZONES FRIDAY AFTERNOON AND SPREAD INTO THE ENTIRE FORECAST AREA FRIDAY NIGHT. THE SHOWERS AND THUNDERSTORMS WILL BE SPOTTY SO WILL MENTION A CHANCE OR SLIGHT CHANCE. THE RIDGE CONTINUES TO BUILD INTO MONTANA ON SATURDAY WITH SOMEWHAT WARMER TEMPERATURES. UNSTABLE AIRMASS WILL COMBINE WITH WEAK FRONTAL BOUNDARY AND LINGERING MONSOONAL MOISTURE FOR A SLIGHT CHANCE OF THUNDERSTORMS. FORRESTER .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY... SYNOPTIC SET UP...A LARGE BROAD COOL CORE TROUGH EXISTS OVER THE HUDSON BAY AND THE CANADIAN SHIELD AND PRAIRIES. A LARGE HIGH PRESSURE HEAT DOME RESIDES OVER THE SOUTHERN AND CENTRAL PLAINS... THE DESERT SOUTHWEST... AND INTERMOUNTAIN WEST. A RIDGE JUTS OUT OF THIS DOME THROUGH NORTHERN IDAHO INTO BRITISH COLUMBIA. NORTHEAST MONTANA LIES BETWEEN THESE TWO FEATURES IN ZONAL TO NORTHWEST FLOW. TO THE WEST A TROUGH IS STEPPING ON SHORE OF NORTHERN CALIFORNIA AND IS PUMPING SHORTWAVES INTO THE FLOW TOWARD MONTANA AND MONSOONAL MOISTURE INTO THE DESERT SOUTHWEST AND INTERMOUNTAIN WEST WHICH WILL CLIP SOUTHERN MONTANA. SATURDAY NIGHT THROUGH MONDAY...FLOW ALOFT WILL BECOME NORTHWEST WHILE THE RIDGE TO THE EAST SLOWLY ACCUMULATES MORE MOISTURE AND MIGRATES EASTWARD INTO CENTRAL MONTANA. SLIGHT CHANCE TO CHANCE POPS FOR AFTERNOON THUNDER COULD INITIATED ALONG A SURFACE BOUNDARY ORIENTED NORTHWEST TO SOUTHEAST ACROSS CENTRAL AND EASTERN MONTANA AND THEN FURTHER CONTINUED OVERNIGHT AS AIR-MASS THUNDERSTORM DYNAMICS FED BY MONSOONAL MOISTURE TAKE OVER. TEMPERATURES SHOULD ALSO BE TICKING UP SLOWLY. THE ONLY QUESTION IS WHERE IS THE SURFACE BOUNDARY DRIFTING AT ANY PARTICULAR TIME. MONDAY NIGHT TO WEDNESDAY... THE TROUGH TO THE WEST WILL MOVE NORTH UP THE COAST OF THE PACIFIC NORTHWEST AND BRITISH COLUMBIA AND ALLOW THE MAIN RIDGE AXIS TO MOVE EAST ACROSS MONTANA. THE TOP OF THE RIDGE WILL BE BLUNTED AROUND THE INTERNATIONAL BORDER AND ALLOW A FEW SHORTWAVES TO PASS BY. THIS WILL CONTINUE THE CHANCES FOR RAIN SHOWERS EACH AFTERNOON AND OVERNIGHT PERIOD BUT FROM A SLIGHTLY DIFFERENT LIFT MECHANISM AS THE OLD SURFACE BOUNDARY MOVES OFF TO THE EAST AND A LEE SURFACE TROUGH TAKES OVER THE ROLE OF AFTERNOON INITIATION. WEDNESDAY NIGHT ONWARD... SOME DISCREPANCIES BETWEEN THE MODELS BEGIN TO PRESENT THEMSELVES HERE AND THEREFORE DECREASE CONFIDENCE. MAIN ISSUE IS WITH THE RIDGE BROADENING OVER THE CANADIAN ROCKIES AND PLAINS. THIS IS A COMMON WARMING SUMMER OCCURRENCE. HOWEVER... THIS YEAR HAS BEEN LESS THAN COMMON WITH FAR COOLER CONDITIONS. EC AND GEM HAVE TYPICALLY CAUGHT ONTO THIS WHERE THE GFS HAS FAILED OVER THE LAST MONTH. YET AGAIN... WE GET A GFS THAT IS GUNG HO ON A VERY SOLID WARMING RIDGE WHILE THE EC ENSEMBLES ALONG WITH THE UKMET... GEM... AND NOGAPS MEMBERS LITERALLY POKE HOLES IN THE RIDGE TO THE NORTH WITH EMBEDDED TROUGHS AND COLD CLOSED LOWS. AT THIS TIME FAR MORE LIKELY TO BELIEVE THE OTHER MODELS AND PREDICT SOME WEAK COOLER AIR DROPPING BACK DOWN THAN A DRAMATIC WARM UP... OR AT LEAST KEEPING TEMPERATURES TRENDING STABLE THIS FAR OUT. GAH && .AVIATION... VFR CEILINGS AND VISIBILITIES ARE ANTICIPATED AT THE TERMINALS THROUGH THE TAF PERIOD. EAST TO NORTHEAST WINDS ARE EXPECTED TO RANGE AROUND 10 KTS THROUGH THE PERIOD AS WELL. MALIAWCO && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
528 AM MDT THU AUG 8 2013 .AVIATION... 12Z TAF CYCLE SOME PATCHES OF LOW STRATUS CLOUDS AND FOG HAVE DEVELOPED OVER SELECT PARTS OF NORTHERN NEW MEXICO...MAINLY WHERE HEAVIER RAIN FELL YESTERDAY AND BEST LOW LAYER MOISTURE IS. GREATEST POTENTIAL FOR MVFR/IFR CONDITIONS WILL BE IN THE NORTHEASTERN HIGHLANDS TO NORTHEASTERN PLAINS...NEAR KLVS...KAXX...KRTN... KCAO...AND KTCC. ANY LOW CLOUDS WILL BURN OFF BY 08/1600UTC. SHOWERS AND STORMS WILL THEN FAVOR NORTH CENTRAL TO NORTHEASTERN SECTIONS OF NEW MEXICO THIS AFTERNOON AND EVENING WITH MINIMAL COVERAGE ELSEWHERE. BREEZES WILL REMAIN LIGHT TO MODERATE OUTSIDE OF THUNDERSTORM OUTFLOWS...AND ANY STORM DOWNPOURS WILL BE CAPABLE OF REDUCING VISIBILITIES/CEILINGS BRIEFLY. 52 && .PREV DISCUSSION...330 AM MDT THU AUG 8 2013... SURFACE BOUNDARY ATTM IN APPROXIMATELY THE SAME LOCATION AS ONE 24 HOURS. STILL CONSIDERABLE MOISTURE LINGERING OVER THE STATE WITH SIGNIFICANTLY DRIER DEWPOINTS AS WELL AS A MUCH DRIER AIR MASS OVERALL ACROSS CENTRAL/WRN AZ. SOMEWHAT MORE ORGANIZED CLOUD COVER ROTG SE OVER THE FOUR CORNERS REGION...AND RUC13 CONTINUES TO ANALYZE A WEAK CLOSED CIRCULATION AT H5 OVER NW NM/SW CO THROUGH EARLY THIS AFTERNOON. AS THE DAY PROGRESSES...A SURFACE BOUNDARY IS FORECAST TO BECOME MORE DEFINED OVER NE NM. THEREFORE HAVE TRENDED TOWARDS THE HIGHER GUIDANCE POPS TODAY FOR THE NORTHEAST THIRD TO HALF OF THE FORECAST AREA. LATEST SPC OUTLOOK HAS SLIGHT RISK FOR SVR STORMS IN AN AREA SIMILAR TO WHAT WAS PREDICTED 24 HOURS AGO. HAVE NOT HIGHLIGHTED THAT POSSIBILITY IN THE WX GRIDS...SO LATER SHIFTS WILL NEED TO MONITOR. FRONT TO PLUNGE INTO THE EASTERN PLAINS TONIGHT BUT NOT MUCH INDICATION MODEL WISE IT WILL REACH THE RGV. FRIDAY NIGHT APPEARS AS IF THIS POSSIBILITY IS MORE LIKELY...TRENDING SHOWER AND STORM CHANCES UPWARD AND WESTWARD. HIGHS TODAY WILL BE A FEW DEGREES BELOW AVERAGE MAINLY NORTH OF INTERSTATE 40...AND MAINLY OVER THE NORTHEAST QUARTER FRIDAY. WITH POTENTIAL FORECAST FOR A MONSOON BURST...HIGHS SATURDAY ACROSS THE NORTHWEST HALF WILL BE SEVERAL DEGREES BELOW AVERAGE. ANOTHER TRANSITION FORECAST IN THE WEATHER PATTERN FOR NEXT WEEK...WITH A TREND TOWARDS WARMER AND DRIER. THE UPPER HIGH CENTER DRIFTS BACK OVER NEW MEXICO...AND FAR ENOUGH WESTWARD TO PUT THE NORTHEAST UNDER NORTHWEST FLOW AS LEAST FOR A DAY OR TWO. .FIRE WEATHER... BACK DOOR COLD FRONT HAS MOVED INTO THE EASTERN PLAINS WITH A REINFORCEMENT OF THIS BOUNDARY EXPECTED FRIDAY NIGHT. CURRENTLY THE REMNANTS OF THE UPPER LOW FROM AZ CONTINUE TO BECOME LESS ORGANIZED OVER SOUTHERN CO. MOISTURE AND LINGERING ENERGY FROM THE LEFTOVER DISTURBANCE WILL KEEP THE BEST WETTING RAIN CHANCES OVER NORTH CENTRAL TO NORTHEASTERN NM TODAY. MODELS CONTINUE TO ADVERTISE DRIER AIR WORKING IN FROM THE WEST TODAY...AND WATER VAPOR SATELLITE IMAGERY SUPPORTS THIS. THEREFORE...EXPECT MINIMAL SHOWER/STORM COVERAGE IN THE CENTRAL TO WEST CENTRAL AND NORTHWESTERN ZONES TODAY. MINIMUM RH WILL STILL STAY AOA 20 PERCENT WITH MODERATE SURFACE BREEZES EXHIBITING A NORTHWESTERLY COMPONENT OVER MUCH OF THE FORECAST AREA. EXCELLENT RH RECOVERY IS EXPECTED OVER THE NORTHEASTERN HALF OF THE FORECAST AREA TONIGHT WITH STILL GOOD RECOVERY OF 60-80 PERCENT FARTHER WEST. CONVECTION FROM THE LATE EVENING MAY ATTEMPT TO SHOVE AN EAST WIND BEYOND THE CENTRAL MOUNTAIN CHAIN TONIGHT...BUT MODELS ARE NOT ENTHUSIASTIC ABOUT IT. AT THIS TIME NO STRONG GAP/CANYON WINDS HAVE BEEN BUILT INTO THE FORECAST THROUGH FRIDAY MORNING. MOISTURE WILL HAVE AT LEAST WORKED TOWARD THE CENTRAL MOUNTAIN CHAIN EARLY ON FRIDAY WITH THE AFOREMENTIONED EASTERLY WINDS...AND THIS MOISTURE PUSH WILL CONTINUE WESTWARD INTO THE AFTERNOON. STORMS WILL BECOME A BIT MORE WIDESPREAD ALONG THE CENTRAL MOUNTAIN CHAIN AND TOWARD THE CONTINENTAL DIVIDE AS TEMPERATURES WARM CLOSE TO AVERAGE IN MOST ZONES. LOWEST MINIMUM RH VALUES WILL BE IN THE SAN JUAN BASIN FRIDAY WHERE VALUES WILL SLIP TO 20 PERCENT OR JUST SLIGHTLY BELOW. ANY CONVECTION LATE FRIDAY EAST OF THE CENTRAL MOUNTAINS WILL AID THE PUSH OF A REINFORCING BACK DOOR FRONT. THIS WILL CONTINUE TO CARRY MOISTURE WESTWARD WHILE ALSO PRODUCING MODERATE TO STRONG GAP/CANYON WINDS NEAR CENTRAL VALLEY LOCATIONS THROUGH SATURDAY MORNING. BETTER LOW LAYER MOISTURE TRANSPORTED FROM THE EAST WILL COUPLE WITH A MID LEVEL MONSOON PLUME SQUEEZING INTO NM...AND THIS WILL SET THE STAGE FOR AN ACTIVE THUNDERSTORM DAY SATURDAY. NAM MODEL IS MOST BULLISH WITH WETTING PRECIP CHANCES AND CONSEQUENTLY BOASTS MUCH COOLER TEMPERATURES WHICH WOULD CERTAINLY MITIGATE ANY FIRE WX CONCERNS. PLENTY OF LEFTOVER MOISTURE TO RECYCLE ON SUNDAY WILL ALSO YIELD A GOOD CROP OF STORMS. INTO NEXT WEEK THE UPPER HIGH IS STILL DEPICTED AS MOVING WESTWARD OVER OR CLOSE TO NM WHILE ELONGATING SOME ON A WEST-EAST AXIS. ANOTHER BACK DOOR FRONT IN THE NORTHEAST COULD KEEP CONVECTIVE ACTIVITY GOING IN THE NORTHEAST LATE TUESDAY. 52 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1025 AM EDT THU AUG 8 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL EVENTUALLY MOVE PAST THE REGION ON FRIDAY NIGHT. IN THE MEANTIME...CHANCES FOR PERIODIC SHOWERS AND A THUNDERSTORM OR TWO WILL CONTINUE FOR TODAY AND FRIDAY. A DRIER WEEKEND IS IN STORE WITH TEMPERATURES REMAINING ON THE COOLER SIDE OF NORMAL FOR AUGUST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1025 AM UPDATE... AREA OF SHOWERS AND SOME THUNDER CONTINUES TO DIMINISH. WHILE MOST OF THE AREA WILL REMAIN DRY THROUGH EARLY AFTERNOON...SHOWERS WILL STILL BE POSSIBLE OVER THE NORTHERN TIER OF PA AND OTSEGO/DELAWARE COUNTIES AS THESE CONTINUE TO DIMINISH. MEANWHILE AN AREA OF CLEARING OVER THE FINGER LAKES AND CNY MAY BE ENOUGH WITH A COLD FRONT OVER LAKE ERIE TO PROVIDE ANOTHER CHANCE THIS AFTERNOON. BLENDED WITH THE PREVIOUS FORECAST OF HIGH CHANCE TO LOW LIKELY LATER TODAY...BUT I DID TRY TO SHOW A NICE GAP OF MAINLY DRY WEATHER BETWEEN NOW AND THEN. THE PREVIOUS AFD IS BELOW... 730 AM UPDATE... QUICK UPDATE TO ACCOUNT FOR LINE OF STORMS MVG ACRS THE AREA EARLY THIS MRNG. HV TRIED TO TRACK CATEGORICAL POPS THRU THE REGION THRU NOON TDA. TSTMS WL TAKE AWHILE TO REACH THE I-81 CORRIDOR IN NEPA AND MAY FALL APART BFR THEY DO AS THEY WL BE MVG INTO INCREASINGLY STABLE AIRMASS. MLCAPE IS 500+ JOULES WHERE THEY ARE LOCATED NOW AND FURTHER TO THE EAST IT DIMINISHES TO NR 250 J/KG PER SPC MESOANALYSIS PAGE. HWVR THINK THAT A GOOD CHUNK OF THE AREA BTWN I-86/I-88 AND I-80 WILL SEE SOME FORM OF PCPN THIS MORNING AND HV BUMPED POPS TO LKLY- CATEGORICAL TO ACCNT FOR THIS. ONCE THIS LINE OF STORMS ROLLS THRU THINK THAT MANY PLACES WL STABILIZE FOR THE REMAINDER OF THE DAY WITH LITTLE ELSE EXPECTED. BUT THAT WL BE LOOKED AT IN FURTHER DETAIL FOR THE NEXT UPDATE. PREV DISCO BLO... TODAY WILL BE A CRAZY...CONVOLUTED AND LOW CONFIDENCE FORECAST GIVEN THE NATURE OF ZONAL FLOW PATTERNS IN THE SUMMER MONTHS. THE FIRST ORDER OF BUSINESS WITH THIS MORNING`S UPDATE IS TO TRACK AND TIME THE CONVECTION MOVING THROUGH WESTERN NEW YORK AND IT`S IMPACT HERE IN CENTRAL DURING THE EARLY HOURS. CONVECTION LOOKS TO BE MAINLY DRIVEN NOW BY COLD POOL INTERACTION WITHIN A BROAD UNSTABLE ENVIRONMENT...AS WV LOOP SHOWS INITIATING SHORT WAVE IS RUNNING OUT AHEAD OF THE CONVECTION ACROSS LOWER ONTARIO. LINEAR TRACKING TAKES THE RAIN AND EMBEDDED TSRA ACROSS MAINLY THE FINGER LAKES REGION AND NORTHERN PORTIONS OF THE SOUTHERN TIER DURING THE EARLY DAYLIGHT HOURS AND HAVE ACCOUNTED FOR THIS WITH ABOUT 4-6 HOURS OF CATEGORICAL-LIKELY POPS OVER NORTHERN COUNTIES WITH SOME SLACK ON THE SOUTHERN END OF THE POP FIELD FOR NEW DEVELOPMENT. THINK THERE WILL ALSO CONTINUE TO BE WEAKENING OF THIS FEATURE AS THE MORNING WEARS ON. THEN...ATTENTION TURNS TO SLOWLY APPROACHING FRONTAL BOUNDARY FOR LATER THIS AFTERNOON. AFTER SCOURING MANY MODEL SOLUTIONS...AND PICKING THROUGH THE NOISE OF CONVECTIVE FEEDBACK...WE ARE HARD PRESSED TO FIND MUCH IN THE WAY OF FORCING FOR NEW CONVECTION THIS AFTERNOON ASIDE FROM MINOR HEIGHT AND PRESSURE FALLS ASSOCIATED WITH THE FRONTAL BOUNDARY...FORMING IN TANDEM WITH DECREASING DIURNAL STABILITY. THE MESOSCALE MODELS LIKE THE HRRR AND WRF-ARW CONVECT MAINLY ALONG THE FRONTAL BOUNDARY MOVING INTO WRN NY THIS AFTERNOON WITH SPOTTY ACTIVITY IN OUR AREA. WE THEREFORE FEEL MUCH OF THE DAY WILL FEATURE...AT BEST... SCATTERED NEW CONVECTIVE DEVELOPMENT ONCE THIS LINGERING RAIN FEATURE MAKES ITS WAY THROUGH OR DISSIPATES IN THE PROCESS. HAVE THUS SCALED BACK ON ANY LIKELY POPS WE HAD GOING THIS AFTERNOON. OTHER PARAMETERS ARE FAIRLY ROUTINE. TEMPERATURES AS A BLEND OF PREV FORECAST/00Z MOS AND 2M MODEL TEMPS AND LOOK TO BE MAINLY IN THE UPPER 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE FORECAST GETS NO EASIER TONIGHT WITH FRONT ONLY SAGGING INTO THE REGION. 00Z NAM AND GFS ARE SIMILAR IN FRONTAL PLACEMENT AND UPPER AIR MASS FIELDS...BUT THE RESULTANT QPF FIELDS ARE VERY DIFFERENT TONIGHT AND FRIDAY AND SEEM OVERDONE WITH RESPECT TO VERY SUBTLE FORCING MECHANISMS. AGAIN...WEEDING THROUGH THE CONVECTIVE FEEDBACK PROBLEMS AS BOTH MODELS TRY TO LIFT SOUTHERN PLAINS CONVECTIVE VORTS THROUGH OUR REGION OVERNIGHT...WE ARE AGAIN HARD PRESSED TO FIND SIGNIFICANT SYNOPTIC SUPPORT FOR AS MUCH RAIN AS THESE MODELS ARE CRANKING OUT ON US. THAT SAID...THE SFC FRONT WILL BE MOVING INTO THE REGION AND THERE IS A POSSIBILITY THAT SOME MINOR UPPER LEVEL FEATURE COULD RUN FAST THROUGH THE REGION. BOTH MODELS ALSO HINT AT AN INCRG SOUTHERLY LOW LEVEL JET IMPINGING ON THE FRONTAL ZONE AND OUR HIGHER TERRAIN AREAS IN NEPA/SENY LATE TONIGHT. WITHOUT MAKING TOO DRAMATIC A SWING IN THE FORECAST...HAVE LOWERED SOME OF THE PREVIOUS FORECAST POPS FOR TONIGHT AND FRIDAY...BUT HAVE MAINTAINED THE LIKELY TERMINOLOGY AS THERE JUST DOESN`T SEEM TO BE MUCH THERE TO WARRANT WIDESPREAD AREAS OF SHOWERS/TSRA. ALSO SHIFTED THE AXIS OF HIGHER POPS A BIT WESTWARD TO LINE UP BETTER WITH THE FRONTAL MOVEMENT. THE FOCUS ON THE SOUTHEAST ZONES JUST SEEMS UNREALISTIC AND THE GFS SEEMED TO HAVE TRENDED A BIT WEST THIS RUN WITH NAM MORE IN OUR EASTERN ZONES. THE TRENDS THEN SUPPORT THE FRONT TO MOVE EAST OF THE REGION FRIDAY NIGHT WITH DECREASING PRECIP PROBABILITY FROM WEST TO EAST THROUGH THE DAY FRIDAY AND EVENTUALLY A DRY OVERNIGHT INTO SATURDAY. HIGH PRESSURE AND COOL NORTHWESTERLY FLOW OVERSPREADS THE REGION THIS WEEKEND. BEST CHANCE FOR SUNSHINE LOOKS TO BE SUNDAY AS COLD ADVECTION CLOUDS ON THE FIRST DAY (SATURDAY) BEHIND A COLD FROPA HERE SPELLS STRATOCU FIELDS GALORE AND PARTLY TO MOSTLY CLOUDY CONDITIONS. FOLLOWED MOS AND 2M MODEL BLENDED TEMPS ALONG WITH PREVIOUS FORECAST WHICH HELPED TO COOL THINGS SLIGHTLY ON FRIDAY AND SATURDAY FROM PREV FORECAST. THE TREND ON SATURDAY WILL CERTAINLY FIT THE CLOUD IDEA. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 4 AM UPDATE... VERY FEW CHANGES MADE TO INHERITED GRIDS AS GOOD AGREEMENT BETWEEN THE GFS AND ECMWF SUPPORTS BETTER THAN AVERAGE CONFIDENCE THROUGH THE PERIOD. UPPER PATTERN THROUGH THE TIME FRAME WILL BE DOMINATED BY BROAD CYCLONIC FLOW ALOFT AS A BLOCKY MID-LATITUDE PATTERN PERSISTS THANKS TO STRONG HIGH PRESSURE ACROSS THE NORTHERN ATLANTIC AND CANADIAN PRAIRIE PROVINCES. BOTH THE GFS AND ECMWF AGREE THAT A SECOND UPPER LOW WILL SWING SOUTH FROM HUDSON BAY BY LATE MON/EARLY TUESDAY WHICH WILL SEND A COLD FRONT EAST ACROSS OUR REGION AS LOW PRESSURE TRACKS JUST OFF TO OUR NORTH. THUS EXPECT RENEWED SHWR AND THUNDERSTORM CHANCES BY TUESDAY BEFORE DRY WX RETURNS TO CONCLUDE THE PERIOD. BELOW NORMAL TEMPS EXPECTED WITH NO HINTS OF ANY MAJOR WARMING SEEN FOR THE FORESEEABLE FUTURE. 200 PM UPDATE... AREA REMAINS UNDER A BROAD LONG WAVE UPPER LEVEL TROUGH THROUGH THE PERIOD AND SLIGHTLY COOLER THAN NORMAL TEMPERATURES WITH HIGHS IN LOWER TO MIDDLE 70S AND NIGHTTIME LOWS IN THE 50S. A FRONT THAT MOVED THROUGH THE AREA EARLY SATURDAY IS FORECAST TO STALL IN A EAST-WEST MANNER ACROSS VIRGINA SATURDAY NIGHT INTO SUNDAY. FROM THIS POINT MODELS HAVE DIFFERENCES OF TIMING AND POSITIONING OF WAVES MOVING EASTWARD ALONG THIS FRONT THROUGH MIDWEEK CAUSING SOME UNCERTAINTY IN THE FORECAST. FORECASTED CLOUDS TO SPREAD NORTH WITH A WAVE ON SUNDAY BUT JUST PLACED A SLIGHT CHANCE THUNDERSTORMS IN THE POCONOS FOR SUNDAY AFTERNOON. HIGH PRESSURE BUILDS ACROSS SUNDAY NIGHT BEHIND THIS WAVE. A SHORT-WAVE MOVING AROUND THE UPR LEVEL LOW TO OUR NORTH MAY BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE AFTERNOON MONDAY. UNCERTAINTY INCREASES TUESDAY AS GFS LINKS A SHORT-WAVE MOVING AROUND THE UPR LOW TO THE NORTH WITH A SURFACE LOW AND WAVE MOVING NORTHEAST ALONG THAT FRONTAL ZONE AND SPREADS CLOUDS AND PRECIPITATION NORTHEAST ACROSS THE AREA TUESDAY. ON THE OTHER HAND THE ECMWF DOES NOT LINK A WAVE UP FROM THE SOUTH WITH JUST AN ISOLATED CHANCE. PUT A 30 POP IN TUESDAY AFTERNOON. SURFACE HIGH PRESSURE BUILDS IN FOR WEDNESDAY WITH A SHORTWAVE RIDGE ALOFT. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... AN AREA OF SHWRS AND EMBEDDED THUNDER WILL CONTINUE MOVING EAST THROUGH THE REGION THIS MORNING. BASED ON LATEST RADAR TRENDS...MOST CONCENTRATED ACTIVITY WILL PREVAIL FROM THE CENTRAL FINGER LAKES SOUTH THROUGH THE TWIN TIERS WHERE TEMPORARY MVFR AND POTENTIALLY SOME SHORT DURATION IFR WILL BE POSSIBLE. ELSEWHERE AT SYR AND RME...CURRENT ACTIVITY WILL LIKELY POSE LITTLE IF ANY RESTRICTIONS AS HEAVIEST RAINS REMAIN SOUTH. A LITTLE MORE UNCERTAIN DOWN AT AVP AS A FAIR AMOUNT OF LAND STILL NEEDS TO BE COVERED BEFORE REACHING THE TERMINAL. FOR NOW...HAVE INSERTED A TEMPO GROUP STARTING AT 14Z FOR POSSIBLE MVFR RESTRICTIONS. AFTER THIS PASSES...FCST BECOMES MUCH MORE CONVOLUTED AS MODELS CONTINUE TO SHOW SEVERAL CLUSTERS OF SHWRS/STORMS DEVELOPING AFTER THE 18Z TIME FRAME. FOR NOW...HAVE DECIDED TO OFFER A TEMPO TSRA MENTION EVERYWHERE BETWEEN 18-21Z UNDER THE PREMISE THAT DAYSHIFT CAN UPDATE ONCE TRENDS BEHIND THIS MORNING/S DEPARTING WAVE BECOME A LITTLE MORE CERTAIN. BY TONIGHT...MAIN ACTIVITY TO LIKELY IMPACT AVP AS ADDITIONAL MOISTURE BEGINS WORKING NORTH ALONG A COLD FRONT. ELSEWHERE...WIDESPREAD MVFR RESTRICTIONS EXPECTED TO DEVELOP WITH OCCASIONAL IFR POSSIBLE AT BGM AND ITH AS MOISTURE BECOMES TRAPPED BELOW DEVELOPING FRONTAL INVERSION. OUTLOOK... FRI...VFR BUT MVFR IN SCATTERED SHRA/TSRA MAINLY SOUTH. SAT THRU MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...JAB NEAR TERM...HEDEN/JAB/PVN SHORT TERM...JAB LONG TERM...BMW/CMG AVIATION...CMG
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
747 AM EDT THU AUG 8 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL EVENTUALLY MOVE PAST THE REGION ON FRIDAY NIGHT. IN THE MEANTIME...CHANCES FOR PERIODIC SHOWERS AND A THUNDERSTORM OR TWO WILL CONTINUE FOR TODAY AND FRIDAY. A DRIER WEEKEND IS IN STORE WITH TEMPERATURES REMAINING ON THE COOLER SIDE OF NORMAL FOR AUGUST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 730 AM UPDATE... QUICK UPDATE TO ACCOUNT FOR LINE OF STORMS MVG ACRS THE AREA EARLY THIS MRNG. HV TRIED TO TRACK CATEGORICAL POPS THRU THE REGION THRU NOON TDA. TSTMS WL TAKE AWHILE TO REACH THE I-81 CORRIDOR IN NEPA AND MAY FALL APART BFR THEY DO AS THEY WL BE MVG INTO INCREASINGLY STABLE AIRMASS. MLCAPE IS 500+ JOULES WHERE THEY ARE LOCATED NOW AND FURTHER TO THE EAST IT DIMINISHES TO NR 250 J/KG PER SPC MESOANALYSIS PAGE. HWVR THINK THAT A GOOD CHUNK OF THE AREA BTWN I-86/I-88 AND I-80 WILL SEE SOME FORM OF PCPN THIS MORNING AND HV BUMPED POPS TO LKLY-CATEGORICAL TO ACCNT FOR THIS. ONCE THIS LINE OF STORMS ROLLS THRU THINK THAT MANY PLACES WL STABILIZE FOR THE REMAINDER OF THE DAY WITH LITTLE ELSE EXPECTED. BUT THAT WL BE LOOKED AT IN FURTHER DETAIL FOR THE NEXT UPDATE. PREV DISCO BLO... TODAY WILL BE A CRAZY...CONVOLUTED AND LOW CONFIDENCE FORECAST GIVEN THE NATURE OF ZONAL FLOW PATTERNS IN THE SUMMER MONTHS. THE FIRST ORDER OF BUSINESS WITH THIS MORNING`S UPDATE IS TO TRACK AND TIME THE CONVECTION MOVING THROUGH WESTERN NEW YORK AND IT`S IMPACT HERE IN CENTRAL DURING THE EARLY HOURS. CONVECTION LOOKS TO BE MAINLY DRIVEN NOW BY COLD POOL INTERACTION WITHIN A BROAD UNSTABLE ENVIRONMENT...AS WV LOOP SHOWS INITIATING SHORT WAVE IS RUNNING OUT AHEAD OF THE CONVECTION ACROSS LOWER ONTARIO. LINEAR TRACKING TAKES THE RAIN AND EMBEDDED TSRA ACROSS MAINLY THE FINGER LAKES REGION AND NORTHERN PORTIONS OF THE SOUTHERN TIER DURING THE EARLY DAYLIGHT HOURS AND HAVE ACCOUNTED FOR THIS WITH ABOUT 4-6 HOURS OF CATEGORICAL-LIKELY POPS OVER NORTHERN COUNTIES WITH SOME SLACK ON THE SOUTHERN END OF THE POP FIELD FOR NEW DEVELOPMENT. THINK THERE WILL ALSO CONTINUE TO BE WEAKENING OF THIS FEATURE AS THE MORNING WEARS ON. THEN...ATTENTION TURNS TO SLOWLY APPROACHING FRONTAL BOUNDARY FOR LATER THIS AFTERNOON. AFTER SCOURING MANY MODEL SOLUTIONS...AND PICKING THROUGH THE NOISE OF CONVECTIVE FEEDBACK...WE ARE HARD PRESSED TO FIND MUCH IN THE WAY OF FORCING FOR NEW CONVECTION THIS AFTERNOON ASIDE FROM MINOR HEIGHT AND PRESSURE FALLS ASSOCIATED WITH THE FRONTAL BOUNDARY...FORMING IN TANDEM WITH DECREASING DIURNAL STABILITY. THE MESOSCALE MODELS LIKE THE HRRR AND WRF-ARW CONVECT MAINLY ALONG THE FRONTAL BOUNDARY MOVING INTO WRN NY THIS AFTERNOON WITH SPOTTY ACTIVITY IN OUR AREA. WE THEREFORE FEEL MUCH OF THE DAY WILL FEATURE...AT BEST... SCATTERED NEW CONVECTIVE DEVELOPMENT ONCE THIS LINGERING RAIN FEATURE MAKES ITS WAY THROUGH OR DISSIPATES IN THE PROCESS. HAVE THUS SCALED BACK ON ANY LIKELY POPS WE HAD GOING THIS AFTERNOON. OTHER PARAMETERS ARE FAIRLY ROUTINE. TEMPERATURES AS A BLEND OF PREV FORECAST/00Z MOS AND 2M MODEL TEMPS AND LOOK TO BE MAINLY IN THE UPPER 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE FORECAST GETS NO EASIER TONIGHT WITH FRONT ONLY SAGGING INTO THE REGION. 00Z NAM AND GFS ARE SIMILAR IN FRONTAL PLACEMENT AND UPPER AIR MASS FIELDS...BUT THE RESULTANT QPF FIELDS ARE VERY DIFFERENT TONIGHT AND FRIDAY AND SEEM OVERDONE WITH RESPECT TO VERY SUBTLE FORCING MECHANISMS. AGAIN...WEEDING THROUGH THE CONVECTIVE FEEDBACK PROBLEMS AS BOTH MODELS TRY TO LIFT SOUTHERN PLAINS CONVECTIVE VORTS THROUGH OUR REGION OVERNIGHT...WE ARE AGAIN HARD PRESSED TO FIND SIGNIFICANT SYNOPTIC SUPPORT FOR AS MUCH RAIN AS THESE MODELS ARE CRANKING OUT ON US. THAT SAID...THE SFC FRONT WILL BE MOVING INTO THE REGION AND THERE IS A POSSIBILITY THAT SOME MINOR UPPER LEVEL FEATURE COULD RUN FAST THROUGH THE REGION. BOTH MODELS ALSO HINT AT AN INCRG SOUTHERLY LOW LEVEL JET IMPINGING ON THE FRONTAL ZONE AND OUR HIGHER TERRAIN AREAS IN NEPA/SENY LATE TONIGHT. WITHOUT MAKING TOO DRAMATIC A SWING IN THE FORECAST...HAVE LOWERED SOME OF THE PREVIOUS FORECAST POPS FOR TONIGHT AND FRIDAY...BUT HAVE MAINTAINED THE LIKELY TERMINOLOGY AS THERE JUST DOESN`T SEEM TO BE MUCH THERE TO WARRANT WIDESPREAD AREAS OF SHOWERS/TSRA. ALSO SHIFTED THE AXIS OF HIGHER POPS A BIT WESTWARD TO LINE UP BETTER WITH THE FRONTAL MOVEMENT. THE FOCUS ON THE SOUTHEAST ZONES JUST SEEMS UNREALISTIC AND THE GFS SEEMED TO HAVE TRENDED A BIT WEST THIS RUN WITH NAM MORE IN OUR EASTERN ZONES. THE TRENDS THEN SUPPORT THE FRONT TO MOVE EAST OF THE REGION FRIDAY NIGHT WITH DECREASING PRECIP PROBABILITY FROM WEST TO EAST THROUGH THE DAY FRIDAY AND EVENTUALLY A DRY OVERNIGHT INTO SATURDAY. HIGH PRESSURE AND COOL NORTHWESTERLY FLOW OVERSPREADS THE REGION THIS WEEKEND. BEST CHANCE FOR SUNSHINE LOOKS TO BE SUNDAY AS COLD ADVECTION CLOUDS ON THE FIRST DAY (SATURDAY) BEHIND A COLD FROPA HERE SPELLS STRATOCU FIELDS GALORE AND PARTLY TO MOSTLY CLOUDY CONDITIONS. FOLLOWED MOS AND 2M MODEL BLENDED TEMPS ALONG WITH PREVIOUS FORECAST WHICH HELPED TO COOL THINGS SLIGHTLY ON FRIDAY AND SATURDAY FROM PREV FORECAST. THE TREND ON SATURDAY WILL CERTAINLY FIT THE CLOUD IDEA. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 4 AM UPDATE... VERY FEW CHANGES MADE TO INHERITED GRIDS AS GOOD AGREEMENT BETWEEN THE GFS AND ECMWF SUPPORTS BETTER THAN AVERAGE CONFIDENCE THROUGH THE PERIOD. UPPER PATTERN THROUGH THE TIME FRAME WILL BE DOMINATED BY BROAD CYCLONIC FLOW ALOFT AS A BLOCKY MID-LATITUDE PATTERN PERSISTS THANKS TO STRONG HIGH PRESSURE ACROSS THE NORTHERN ATLANTIC AND CANADIAN PRAIRIE PROVINCES. BOTH THE GFS AND ECMWF AGREE THAT A SECOND UPPER LOW WILL SWING SOUTH FROM HUDSON BAY BY LATE MON/EARLY TUESDAY WHICH WILL SEND A COLD FRONT EAST ACROSS OUR REGION AS LOW PRESSURE TRACKS JUST OFF TO OUR NORTH. THUS EXPECT RENEWED SHWR AND THUNDERSTORM CHANCES BY TUESDAY BEFORE DRY WX RETURNS TO CONCLUDE THE PERIOD. BELOW NORMAL TEMPS EXPECTED WITH NO HINTS OF ANY MAJOR WARMING SEEN FOR THE FORESEEABLE FUTURE. 200 PM UPDATE... AREA REMAINS UNDER A BROAD LONG WAVE UPPER LEVEL TROUGH THROUGH THE PERIOD AND SLIGHTLY COOLER THAN NORMAL TEMPERATURES WITH HIGHS IN LOWER TO MIDDLE 70S AND NIGHTTIME LOWS IN THE 50S. A FRONT THAT MOVED THROUGH THE AREA EARLY SATURDAY IS FORECAST TO STALL IN A EAST-WEST MANNER ACROSS VIRGINA SATURDAY NIGHT INTO SUNDAY. FROM THIS POINT MODELS HAVE DIFFERENCES OF TIMING AND POSITIONING OF WAVES MOVING EASTWARD ALONG THIS FRONT THROUGH MIDWEEK CAUSING SOME UNCERTAINTY IN THE FORECAST. FORECASTED CLOUDS TO SPREAD NORTH WITH A WAVE ON SUNDAY BUT JUST PLACED A SLIGHT CHANCE THUNDERSTORMS IN THE POCONOS FOR SUNDAY AFTERNOON. HIGH PRESSURE BUILDS ACROSS SUNDAY NIGHT BEHIND THIS WAVE. A SHORT-WAVE MOVING AROUND THE UPR LEVEL LOW TO OUR NORTH MAY BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE AFTERNOON MONDAY. UNCERTAINTY INCREASES TUESDAY AS GFS LINKS A SHORT-WAVE MOVING AROUND THE UPR LOW TO THE NORTH WITH A SURFACE LOW AND WAVE MOVING NORTHEAST ALONG THAT FRONTAL ZONE AND SPREADS CLOUDS AND PRECIPITATION NORTHEAST ACROSS THE AREA TUESDAY. ON THE OTHER HAND THE ECMWF DOES NOT LINK A WAVE UP FROM THE SOUTH WITH JUST AN ISOLATED CHANCE. PUT A 30 POP IN TUESDAY AFTERNOON. SURFACE HIGH PRESSURE BUILDS IN FOR WEDNESDAY WITH A SHORTWAVE RIDGE ALOFT. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AN AREA OF SHWRS AND EMBEDDED THUNDER WILL CONTINUE MOVING EAST THROUGH THE REGION THIS MORNING. BASED ON LATEST RADAR TRENDS...MOST CONCENTRATED ACTIVITY WILL PREVAIL FROM THE CENTRAL FINGER LAKES SOUTH THROUGH THE TWIN TIERS WHERE TEMPORARY MVFR AND POTENTIALLY SOME SHORT DURATION IFR WILL BE POSSIBLE. ELSEWHERE AT SYR AND RME...CURRENT ACTIVITY WILL LIKELY POSE LITTLE IF ANY RESTRICTIONS AS HEAVIEST RAINS REMAIN SOUTH. A LITTLE MORE UNCERTAIN DOWN AT AVP AS A FAIR AMOUNT OF LAND STILL NEEDS TO BE COVERED BEFORE REACHING THE TERMINAL. FOR NOW...HAVE INSERTED A TEMPO GROUP STARTING AT 14Z FOR POSSIBLE MVFR RESTRICTIONS. AFTER THIS PASSES...FCST BECOMES MUCH MORE CONVOLUTED AS MODELS CONTINUE TO SHOW SEVERAL CLUSTERS OF SHWRS/STORMS DEVELOPING AFTER THE 18Z TIME FRAME. FOR NOW...HAVE DECIDED TO OFFER A TEMPO TSRA MENTION EVERYWHERE BETWEEN 18-21Z UNDER THE PREMISE THAT DAYSHIFT CAN UPDATE ONCE TRENDS BEHIND THIS MORNING/S DEPARTING WAVE BECOME A LITTLE MORE CERTAIN. BY TONIGHT...MAIN ACTIVITY TO LIKELY IMPACT AVP AS ADDITIONAL MOISTURE BEGINS WORKING NORTH ALONG A COLD FRONT. ELSEWHERE...WIDESPREAD MVFR RESTRICTIONS EXPECTED TO DEVELOP WITH OCCASIONAL IFR POSSIBLE AT BGM AND ITH AS MOISTURE BECOMES TRAPPED BELOW DEVELOPING FRONTAL INVERSION. OUTLOOK... FRI...VFR BUT MVFR IN SCATTERED SHRA/TSRA MAINLY SOUTH. SAT THRU MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...JAB NEAR TERM...JAB/PVN SHORT TERM...JAB LONG TERM...BMW/CMG AVIATION...CMG
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
652 AM EDT THU AUG 8 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL EVENTUALLY MOVE PAST THE REGION ON FRIDAY NIGHT. IN THE MEANTIME...CHANCES FOR PERIODIC SHOWERS AND A THUNDERSTORM OR TWO WILL CONTINUE FOR TODAY AND FRIDAY. A DRIER WEEKEND IS IN STORE WITH TEMPERATURES REMAINING ON THE COOLER SIDE OF NORMAL FOR AUGUST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TODAY WILL BE A CRAZY...CONVOLUTED AND LOW CONFIDENCE FORECAST GIVEN THE NATURE OF ZONAL FLOW PATTERNS IN THE SUMMER MONTHS. THE FIRST ORDER OF BUSINESS WITH THIS MORNING`S UPDATE IS TO TRACK AND TIME THE CONVECTION MOVING THROUGH WESTERN NEW YORK AND IT`S IMPACT HERE IN CENTRAL DURING THE EARLY HOURS. CONVECTION LOOKS TO BE MAINLY DRIVEN NOW BY COLD POOL INTERACTION WITHIN A BROAD UNSTABLE ENVIRONMENT...AS WV LOOP SHOWS INITIATING SHORT WAVE IS RUNNING OUT AHEAD OF THE CONVECTION ACROSS LOWER ONTARIO. LINEAR TRACKING TAKES THE RAIN AND EMBEDDED TSRA ACROSS MAINLY THE FINGER LAKES REGION AND NORTHERN PORTIONS OF THE SOUTHERN TIER DURING THE EARLY DAYLIGHT HOURS AND HAVE ACCOUNTED FOR THIS WITH ABOUT 4-6 HOURS OF CATEGORICAL-LIKELY POPS OVER NORTHERN COUNTIES WITH SOME SLACK ON THE SOUTHERN END OF THE POP FIELD FOR NEW DEVELOPMENT. THINK THERE WILL ALSO CONTINUE TO BE WEAKENING OF THIS FEATURE AS THE MORNING WEARS ON. THEN...ATTENTION TURNS TO SLOWLY APPROACHING FRONTAL BOUNDARY FOR LATER THIS AFTERNOON. AFTER SCOURING MANY MODEL SOLUTIONS...AND PICKING THROUGH THE NOISE OF CONVECTIVE FEEDBACK...WE ARE HARD PRESSED TO FIND MUCH IN THE WAY OF FORCING FOR NEW CONVECTION THIS AFTERNOON ASIDE FROM MINOR HEIGHT AND PRESSURE FALLS ASSOCIATED WITH THE FRONTAL BOUNDARY...FORMING IN TANDEM WITH DECREASING DIURNAL STABILITY. THE MESOSCALE MODELS LIKE THE HRRR AND WRF-ARW CONVECT MAINLY ALONG THE FRONTAL BOUNDARY MOVING INTO WRN NY THIS AFTERNOON WITH SPOTTY ACTIVITY IN OUR AREA. WE THEREFORE FEEL MUCH OF THE DAY WILL FEATURE...AT BEST... SCATTERED NEW CONVECTIVE DEVELOPMENT ONCE THIS LINGERING RAIN FEATURE MAKES ITS WAY THROUGH OR DISSIPATES IN THE PROCESS. HAVE THUS SCALED BACK ON ANY LIKELY POPS WE HAD GOING THIS AFTERNOON. OTHER PARAMETERS ARE FAIRLY ROUTINE. TEMPERATURES AS A BLEND OF PREV FORECAST/00Z MOS AND 2M MODEL TEMPS AND LOOK TO BE MAINLY IN THE UPPER 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE FORECAST GETS NO EASIER TONIGHT WITH FRONT ONLY SAGGING INTO THE REGION. 00Z NAM AND GFS ARE SIMILAR IN FRONTAL PLACEMENT AND UPPER AIR MASS FIELDS...BUT THE RESULTANT QPF FIELDS ARE VERY DIFFERENT TONIGHT AND FRIDAY AND SEEM OVERDONE WITH RESPECT TO VERY SUBTLE FORCING MECHANISMS. AGAIN...WEEDING THROUGH THE CONVECTIVE FEEDBACK PROBLEMS AS BOTH MODELS TRY TO LIFT SOUTHERN PLAINS CONVECTIVE VORTS THROUGH OUR REGION OVERNIGHT...WE ARE AGAIN HARD PRESSED TO FIND SIGNIFICANT SYNOPTIC SUPPORT FOR AS MUCH RAIN AS THESE MODELS ARE CRANKING OUT ON US. THAT SAID...THE SFC FRONT WILL BE MOVING INTO THE REGION AND THERE IS A POSSIBILITY THAT SOME MINOR UPPER LEVEL FEATURE COULD RUN FAST THROUGH THE REGION. BOTH MODELS ALSO HINT AT AN INCRG SOUTHERLY LOW LEVEL JET IMPINGING ON THE FRONTAL ZONE AND OUR HIGHER TERRAIN AREAS IN NEPA/SENY LATE TONIGHT. WITHOUT MAKING TOO DRAMATIC A SWING IN THE FORECAST...HAVE LOWERED SOME OF THE PREVIOUS FORECAST POPS FOR TONIGHT AND FRIDAY...BUT HAVE MAINTAINED THE LIKELY TERMINOLOGY AS THERE JUST DOESN`T SEEM TO BE MUCH THERE TO WARRANT WIDESPREAD AREAS OF SHOWERS/TSRA. ALSO SHIFTED THE AXIS OF HIGHER POPS A BIT WESTWARD TO LINE UP BETTER WITH THE FRONTAL MOVEMENT. THE FOCUS ON THE SOUTHEAST ZONES JUST SEEMS UNREALISTIC AND THE GFS SEEMED TO HAVE TRENDED A BIT WEST THIS RUN WITH NAM MORE IN OUR EASTERN ZONES. THE TRENDS THEN SUPPORT THE FRONT TO MOVE EAST OF THE REGION FRIDAY NIGHT WITH DECREASING PRECIP PROBABILITY FROM WEST TO EAST THROUGH THE DAY FRIDAY AND EVENTUALLY A DRY OVERNIGHT INTO SATURDAY. HIGH PRESSURE AND COOL NORTHWESTERLY FLOW OVERSPREADS THE REGION THIS WEEKEND. BEST CHANCE FOR SUNSHINE LOOKS TO BE SUNDAY AS COLD ADVECTION CLOUDS ON THE FIRST DAY (SATURDAY) BEHIND A COLD FROPA HERE SPELLS STRATOCU FIELDS GALORE AND PARTLY TO MOSTLY CLOUDY CONDITIONS. FOLLOWED MOS AND 2M MODEL BLENDED TEMPS ALONG WITH PREVIOUS FORECAST WHICH HELPED TO COOL THINGS SLIGHTLY ON FRIDAY AND SATURDAY FROM PREV FORECAST. THE TREND ON SATURDAY WILL CERTAINLY FIT THE CLOUD IDEA. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 4 AM UPDATE... VERY FEW CHANGES MADE TO INHERITED GRIDS AS GOOD AGREEMENT BETWEEN THE GFS AND ECMWF SUPPORTS BETTER THAN AVERAGE CONFIDENCE THROUGH THE PERIOD. UPPER PATTERN THROUGH THE TIME FRAME WILL BE DOMINATED BY BROAD CYCLONIC FLOW ALOFT AS A BLOCKY MID-LATITUDE PATTERN PERSISTS THANKS TO STRONG HIGH PRESSURE ACROSS THE NORTHERN ATLANTIC AND CANADIAN PRAIRIE PROVINCES. BOTH THE GFS AND ECMWF AGREE THAT A SECOND UPPER LOW WILL SWING SOUTH FROM HUDSON BAY BY LATE MON/EARLY TUESDAY WHICH WILL SEND A COLD FRONT EAST ACROSS OUR REGION AS LOW PRESSURE TRACKS JUST OFF TO OUR NORTH. THUS EXPECT RENEWED SHWR AND THUNDERSTORM CHANCES BY TUESDAY BEFORE DRY WX RETURNS TO CONCLUDE THE PERIOD. BELOW NORMAL TEMPS EXPECTED WITH NO HINTS OF ANY MAJOR WARMING SEEN FOR THE FORESEEABLE FUTURE. 200 PM UPDATE... AREA REMAINS UNDER A BROAD LONG WAVE UPPER LEVEL TROUGH THROUGH THE PERIOD AND SLIGHTLY COOLER THAN NORMAL TEMPERATURES WITH HIGHS IN LOWER TO MIDDLE 70S AND NIGHTTIME LOWS IN THE 50S. A FRONT THAT MOVED THROUGH THE AREA EARLY SATURDAY IS FORECAST TO STALL IN A EAST-WEST MANNER ACROSS VIRGINA SATURDAY NIGHT INTO SUNDAY. FROM THIS POINT MODELS HAVE DIFFERENCES OF TIMING AND POSITIONING OF WAVES MOVING EASTWARD ALONG THIS FRONT THROUGH MIDWEEK CAUSING SOME UNCERTAINTY IN THE FORECAST. FORECASTED CLOUDS TO SPREAD NORTH WITH A WAVE ON SUNDAY BUT JUST PLACED A SLIGHT CHANCE THUNDERSTORMS IN THE POCONOS FOR SUNDAY AFTERNOON. HIGH PRESSURE BUILDS ACROSS SUNDAY NIGHT BEHIND THIS WAVE. A SHORT-WAVE MOVING AROUND THE UPR LEVEL LOW TO OUR NORTH MAY BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS IN THE AFTERNOON MONDAY. UNCERTAINTY INCREASES TUESDAY AS GFS LINKS A SHORT-WAVE MOVING AROUND THE UPR LOW TO THE NORTH WITH A SURFACE LOW AND WAVE MOVING NORTHEAST ALONG THAT FRONTAL ZONE AND SPREADS CLOUDS AND PRECIPITATION NORTHEAST ACROSS THE AREA TUESDAY. ON THE OTHER HAND THE ECMWF DOES NOT LINK A WAVE UP FROM THE SOUTH WITH JUST AN ISOLATED CHANCE. PUT A 30 POP IN TUESDAY AFTERNOON. SURFACE HIGH PRESSURE BUILDS IN FOR WEDNESDAY WITH A SHORTWAVE RIDGE ALOFT. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AN AREA OF SHWRS AND EMBEDDED THUNDER WILL CONTINUE MOVING EAST THROUGH THE REGION THIS MORNING. BASED ON LATEST RADAR TRENDS...MOST CONCENTRATED ACTIVITY WILL PREVAIL FROM THE CENTRAL FINGER LAKES SOUTH THROUGH THE TWIN TIERS WHERE TEMPORARY MVFR AND POTENTIALLY SOME SHORT DURATION IFR WILL BE POSSIBLE. ELSEWHERE AT SYR AND RME...CURRENT ACTIVITY WILL LIKELY POSE LITTLE IF ANY RESTRICTIONS AS HEAVIEST RAINS REMAIN SOUTH. A LITTLE MORE UNCERTAIN DOWN AT AVP AS A FAIR AMOUNT OF LAND STILL NEEDS TO BE COVERED BEFORE REACHING THE TERMINAL. FOR NOW...HAVE INSERTED A TEMPO GROUP STARTING AT 14Z FOR POSSIBLE MVFR RESTRICTIONS. AFTER THIS PASSES...FCST BECOMES MUCH MORE CONVOLUTED AS MODELS CONTINUE TO SHOW SEVERAL CLUSTERS OF SHWRS/STORMS DEVELOPING AFTER THE 18Z TIME FRAME. FOR NOW...HAVE DECIDED TO OFFER A TEMPO TSRA MENTION EVERYWHERE BETWEEN 18-21Z UNDER THE PREMISE THAT DAYSHIFT CAN UPDATE ONCE TRENDS BEHIND THIS MORNING/S DEPARTING WAVE BECOME A LITTLE MORE CERTAIN. BY TONIGHT...MAIN ACTIVITY TO LIKELY IMPACT AVP AS ADDITIONAL MOISTURE BEGINS WORKING NORTH ALONG A COLD FRONT. ELSEWHERE...WIDESPREAD MVFR RESTRICTIONS EXPECTED TO DEVELOP WITH OCCASIONAL IFR POSSIBLE AT BGM AND ITH AS MOISTURE BECOMES TRAPPED BELOW DEVELOPING FRONTAL INVERSION. OUTLOOK... FRI...VFR BUT MVFR IN SCATTERED SHRA/TSRA MAINLY SOUTH. SAT THRU MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...JAB NEAR TERM... SHORT TERM...JAB LONG TERM...BMW/CMG AVIATION...CMG
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
705 AM EDT THU AUG 8 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS FROM THE EAST OVER THE NEXT SEVERAL DAYS. WARMER AND MORE HUMID AIR WILL MOVE INTO THE CAROLINAS ON SOUTH WINDS...ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS. A COLD FRONT WILL STALL NEAR OR JUST NORTH OF THE AREA MONDAY THROUGH WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...LOW STRATUS DID NOT DEVELOP AT ALL INLAND THIS MORNING...RATHER UNEXPECTED GIVEN THE VERY GOOD RADIATIONAL COOLING CONDITIONS WE HAD. OVER THE NEXT 3 HOURS LOOK FOR SCATTERED SHOWERS TO DEVELOP NEAR CAPE FEAR AND SPREAD NORTH ACROSS SOUTHEASTERN NORTH CAROLINA. OTHERWISE NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... AFTER ENJOYING SEVERAL DAYS OF BELOW-NORMAL TEMPERATURES AND HUMIDITY...THE REALITY OF AUGUST RETURNS TO THE CAROLINAS TODAY. THE SURFACE RIDGE AXIS THAT HELD OUR SURFACE WINDS EASTERLY OVER THE PAST SEVERAL DAYS IS GONE. BERMUDA HIGH PRESSURE WILL ESTABLISH A SOUTH FLOW ACROSS THE AREA TODAY WITH TEMPERATURES RISING TO AROUND 90 INLAND AND UPPER 80S NEAR THE COAST. WITH NO SUBSIDENCE INVERSIONS TO DEAL WITH TODAY AND SURFACE-BASED CAPE BUILDING TO AROUND 1000 J/KG...LOOK FOR SCATTERED SHOWERS AND A FEW T-STORMS TODAY AS WELL. ACTIVITY COULD GET A VERY EARLY START ALONG THE COAST AND PARTICULARLY IN THE CAPE FEAR REGION WHERE THE LAST SEVERAL RUNS OF THE HRRR INDICATE SHOWERS MAY DEVELOP AS EARLY AS SUNRISE NEAR SOUTHPORT AND WILMINGTON. BY LATE MORNING SCATTERED CONVECTION SHOULD BE LINING UP ALONG THE DEVELOPING SEABREEZE BOUNDARY...LIFTING SLOWLY INLAND THROUGH THE AFTERNOON HOURS. FORECAST POPS RANGE FROM 20-40 PERCENT...HIGHEST ACROSS SE NORTH CAROLINA. FOR TONIGHT...INLAND CONVECTIVE ACTIVITY SHOULD GRADUALLY DIMINISH DURING THE EVENING HOURS WITH SKIES BECOMING MOSTLY CLEAR TO PARTLY CLOUDY. SOME LOW STRATUS MAY DEVELOP VERY LATE TONIGHT INLAND AS SATURATION OCCURS WITHIN THE BOUNDARY LAYER BUT 1000-FOOT WINDS REMAIN A LITTLE TOO STRONG FOR FOG. LOWS WILL FALL TO 72-74 INLAND AND 73-78 NEAR THE COAST. SOME SOUTH-FACING BEACHES COULD SEE LOW TEMPERATURES STRUGGLE TO DROP BELOW 80 IF THE ONSHORE WIND CONTINUES THROUGH THE NIGHT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...MID LEVEL RIDGE WILL REMAIN ACROSS THE AREA AS A WESTERLY PATTERN DEVELOPS AT THE MID LEVELS. HOWEVER THERE WILL BE INTERVALS OF RICHER THETA-E AIR TRAVERSING THE ZONAL FLOW WHICH WARRANTS AT LEAST LOW CHANCE POPS THROUGH THE PERIOD. THE NUMEROUS CLUSTERS OF THUNDERSTORMS WE HAVE SEEN MOVING ACROSS THE TENNESSEE VALLEY WILL NOW TAKE AIM ON THE CAROLINAS. THE PIEDMONT TROUGH WILL BE ENHANCED WITH THE WESTERLY FLOW WHICH WILL ASSIST IN THE FORCING AS WELL. I HAVE MAINTAINED THE CHANCE POPS...MAINLY ON A DIURNAL BASIS THROUGH THE PERIOD. AS WE GET CLOSER TO THE WEEKEND...THERE WILL BE TIMES WHEN LIKELY POPS WILL BE WARRANTED BUT THIS WILL BE BETTER ADDRESSED WITH THE NEAR TERM FORECAST. TEMPERATURE TRENDS REMAIN RELATIVELY UNCHANGED WITH THE STRONG RIDGE AND DOWNSLOPE COMPONENT LEADING TO READINGS SLIGHTLY ABOVE CLIMATOLOGY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY...MEDIUM RANGE GUIDANCE IS TRENDING TOWARD A RATHER WET SCENARIO FOR THE EXTENDED PERIOD. ELONGATED MID LEVEL RIDGE SHIFTS WEST AND TROUGHING DEVELOPS ACROSS THE OHIO VALLEY. THE TROUGH REMAINS IN PLACE AS DOES THE FRONT ASSOCIATED WITH IT...WHICH IS POSITIONED RIGHT ACROSS OUR AREA. THIS WILL PROVIDE A GOOF FOCUSING MECHANISM FOR INTERVALS OF SHOWERS AND THUNDERSTORMS. HAVE INCREMENTALLY INCREASED POPS TO REPRESENT THIS TREND. TEMPERATURES FORECAST IS ALREADY SHOWING LOWER THAN USUAL DIURNAL RANGE WITH THE MOISTURE AND NEEDED NO CHANGES WITH THE MORNING UPDATE. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 12Z...HRRR MODEL HAS BEEN PRETTY CONSISTENT IN DEVELOPING CONVECTION BY LATE MORNING ALONG THE COAST...ASSOCIATED WITH THE CONVERGING RESULTANT BOUNDARY. ISOLATED/SCATTERED CONVECTION WILL TAKE A WHILE TO DEVELOP INLAND...DUE TO RELATIVELY HIGH LFC`S. MOST OF THE CONVECTION WILL END BY 22Z OR SO. THERE IS A CHANCE OF SOME NEAR IFR TO IFR STRATUS AFTER MIDNIGHT. WILL REEVALUATE THIS SCENARIO WITH THE NEXT SET OF MODEL RUNS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...SEAS HAVE BUILT TO 3 FT ABOUT 6 HOURS FASTER THAN ANTICIPATED AT THE WRIGHTSVILLE BEACH NEARSHORE BUOY. ASIDE FROM THIS CHANGE...THE PREVIOUS FORECAST REMAINS IN GOOD SHAPE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... THE SURFACE RIDGE AXIS THAT HAS HELD OUR WIND DIRECTIONS EASTERLY FOR THE PAST SEVERAL DAYS HAS FINALLY BROKEN DOWN. RATHER THAN CANADIAN HIGH PRESSURE POKING DOWN FROM THE NORTHEAST...OUR WEATHER TODAY AND TONIGHT WILL COME UNDER THE INFLUENCE OF BERMUDA HIGH PRESSURE FROM THE EAST. THIS MEANS WINDS WILL BECOME SOUTHERLY TODAY AND SOUTH-SOUTHWESTERLY TONIGHT...WITH SPEEDS AVERAGING 10-12 KNOTS. SEAS ARE CURRENTLY 2-3 FT WITH PERIODS SPLIT BETWEEN A 6 SECOND WIND WAVE AND A WEAK 9-10 SECOND SOUTHEAST SWELL. SEAS MAY BUILD HALF A FOOT THROUGH TONIGHT AS SOUTH WINDS FURTHER DEVELOP THE WIND WAVE COMPONENT. RADAR CURRENTLY SHOWS ONLY ISOLATED SHOWERS OUT BEYOND 30 MILES FROM SHORE...BUT MODELS ARE SHOWING WE SHOULD HAVE SCATTERED SHOWERS DEVELOPING NEARSHORE NEAR AND NORTH OF CAPE FEAR THIS MORNING. CONVECTIVE ACTIVITY SHOULD LARGELY SHIFT INLAND THIS AFTERNOON AS THE SEABREEZE CIRCULATION BECOMES BETTER DEVELOPED. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...ELEMENTS REMAIN THE SAME FOR THE COASTAL WATERS THROUGH THE PERIOD AS BERMUDA HIGH PRESSURE AND THE PIEDMONT TROUGH KEEP A SOUTHWESTERLY FLOW IN PLACE. SPEEDS REMAIN STABLE IN A RANGE OF 10-15 KNOTS...WHICH IF ANYTHING MAY BE ON THE HIGHER END SATURDAY AFTERNOON AS THE TROUGH STRENGTHENS. THE TEPID INCREASE IN WINDS ISN/T ENOUGH TO IMPACT SIGNIFICANT SEAS...WHICH REMAIN IN A 2-3 FOOT RANGE. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM THURSDAY...DIFFUSE FRONT WILL REMAIN JUST INLAND...AT LEAST LOOKING AT THE LATEST WPC FORECAST AND THIS WILL KEEP A RATHER WEAK SOUTHWESTERLY FLOW IN PLACE. SPEEDS CONTINUE TO HOVER AROUND TEN KNOTS OR BELOW. CAN/T RULE OUT BRIEF DISRUPTIONS IN THE SYNOPTIC FLOW WITH INTERVALS OF CONVECTION EXPECTED BUT THIS OF COURSE IS ALL BUT IMPOSSIBLE TO FORECAST THIS FAR OUT IN TIME. SIGNIFICANT SEAS SHOW LITTLE CHANGE AS WELL WITH 2-3 FEET AND LITTLE IN THE WAY OF A SWELL COMPONENT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...SHK LONG TERM...SHK AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
638 AM EDT THU AUG 8 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS FROM THE EAST OVER THE NEXT SEVERAL DAYS. WARMER AND MORE HUMID AIR WILL MOVE INTO THE CAROLINAS ON SOUTH WINDS...ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS. A COLD FRONT WILL STALL NEAR OR JUST NORTH OF THE AREA MONDAY THROUGH WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...LOW STRATUS DID NOT DEVELOP AT ALL INLAND THIS MORNING...RATHER UNEXPECTED GIVEN THE VERY GOOD RADIATIONAL COOLING CONDITIONS WE HAD. OVER THE NEXT 3 HOURS LOOK FOR SCATTERED SHOWERS TO DEVELOP NEAR CAPE FEAR AND SPREAD NORTH ACROSS SOUTHEASTERN NORTH CAROLINA. OTHERWISE NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... AFTER ENJOYING SEVERAL DAYS OF BELOW-NORMAL TEMPERATURES AND HUMIDITY...THE REALITY OF AUGUST RETURNS TO THE CAROLINAS TODAY. THE SURFACE RIDGE AXIS THAT HELD OUR SURFACE WINDS EASTERLY OVER THE PAST SEVERAL DAYS IS GONE. BERMUDA HIGH PRESSURE WILL ESTABLISH A SOUTH FLOW ACROSS THE AREA TODAY WITH TEMPERATURES RISING TO AROUND 90 INLAND AND UPPER 80S NEAR THE COAST. WITH NO SUBSIDENCE INVERSIONS TO DEAL WITH TODAY AND SURFACE-BASED CAPE BUILDING TO AROUND 1000 J/KG...LOOK FOR SCATTERED SHOWERS AND A FEW T-STORMS TODAY AS WELL. ACTIVITY COULD GET A VERY EARLY START ALONG THE COAST AND PARTICULARLY IN THE CAPE FEAR REGION WHERE THE LAST SEVERAL RUNS OF THE HRRR INDICATE SHOWERS MAY DEVELOP AS EARLY AS SUNRISE NEAR SOUTHPORT AND WILMINGTON. BY LATE MORNING SCATTERED CONVECTION SHOULD BE LINING UP ALONG THE DEVELOPING SEABREEZE BOUNDARY...LIFTING SLOWLY INLAND THROUGH THE AFTERNOON HOURS. FORECAST POPS RANGE FROM 20-40 PERCENT...HIGHEST ACROSS SE NORTH CAROLINA. FOR TONIGHT...INLAND CONVECTIVE ACTIVITY SHOULD GRADUALLY DIMINISH DURING THE EVENING HOURS WITH SKIES BECOMING MOSTLY CLEAR TO PARTLY CLOUDY. SOME LOW STRATUS MAY DEVELOP VERY LATE TONIGHT INLAND AS SATURATION OCCURS WITHIN THE BOUNDARY LAYER BUT 1000-FOOT WINDS REMAIN A LITTLE TOO STRONG FOR FOG. LOWS WILL FALL TO 72-74 INLAND AND 73-78 NEAR THE COAST. SOME SOUTH-FACING BEACHES COULD SEE LOW TEMPERATURES STRUGGLE TO DROP BELOW 80 IF THE ONSHORE WIND CONTINUES THROUGH THE NIGHT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...MID LEVEL RIDGE WILL REMAIN ACROSS THE AREA AS A WESTERLY PATTERN DEVELOPS AT THE MID LEVELS. HOWEVER THERE WILL BE INTERVALS OF RICHER THETA-E AIR TRAVERSING THE ZONAL FLOW WHICH WARRANTS AT LEAST LOW CHANCE POPS THROUGH THE PERIOD. THE NUMEROUS CLUSTERS OF THUNDERSTORMS WE HAVE SEEN MOVING ACROSS THE TENNESSEE VALLEY WILL NOW TAKE AIM ON THE CAROLINAS. THE PIEDMONT TROUGH WILL BE ENHANCED WITH THE WESTERLY FLOW WHICH WILL ASSIST IN THE FORCING AS WELL. I HAVE MAINTAINED THE CHANCE POPS...MAINLY ON A DIURNAL BASIS THROUGH THE PERIOD. AS WE GET CLOSER TO THE WEEKEND...THERE WILL BE TIMES WHEN LIKELY POPS WILL BE WARRANTED BUT THIS WILL BE BETTER ADDRESSED WITH THE NEAR TERM FORECAST. TEMPERATURE TRENDS REMAIN RELATIVELY UNCHANGED WITH THE STRONG RIDGE AND DOWNSLOPE COMPONENT LEADING TO READINGS SLIGHTLY ABOVE CLIMATOLOGY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY...MEDIUM RANGE GUIDANCE IS TRENDING TOWARD A RATHER WET SCENARIO FOR THE EXTENDED PERIOD. ELONGATED MID LEVEL RIDGE SHIFTS WEST AND TROUGHING DEVELOPS ACROSS THE OHIO VALLEY. THE TROUGH REMAINS IN PLACE AS DOES THE FRONT ASSOCIATED WITH IT...WHICH IS POSITIONED RIGHT ACROSS OUR AREA. THIS WILL PROVIDE A GOOF FOCUSING MECHANISM FOR INTERVALS OF SHOWERS AND THUNDERSTORMS. HAVE INCREMENTALLY INCREASED POPS TO REPRESENT THIS TREND. TEMPERATURES FORECAST IS ALREADY SHOWING LOWER THAN USUAL DIURNAL RANGE WITH THE MOISTURE AND NEEDED NO CHANGES WITH THE MORNING UPDATE. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 06Z...ISOLATED SHRA OVER THE ATLANTIC SHOULD REMAIN JUST EAST OF THE ILM AIRPORT THROUGH DAYBREAK. ANTICIPATE DEVELOPMENT OF MVFR CIGS ALONG THE COAST...WITH POSSIBLE IFR/LIFR INLAND DUE TO FOG & LOW CIGS AN HOUR OR TWO BEFORE DAYBREAK. FLIGHT CATEGORY SHOULD IMPROVE TO VFR NO LATER THAN 13-14Z. CANNOT RULE OUT ISOLATED SHOWERS...THUS HAVE OPTED TO INTRODUCE VCSH AT ALL SITES...BEGINNING ALONG THE COAST FIRST. SHOWERS WILL TAPER OFF IN THE EVENING HOURS. EXTENDED OUTLOOK...ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY THROUGH SATURDAY...BECOMING SCATTERED SUNDAY AND MONDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...SEAS HAVE BUILT TO 3 FT ABOUT 6 HOURS FASTER THAN ANTICIPATED AT THE WRIGHTSVILLE BEACH NEARSHORE BUOY. ASIDE FROM THIS CHANGE...THE PREVIOUS FORECAST REMAINS IN GOOD SHAPE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... THE SURFACE RIDGE AXIS THAT HAS HELD OUR WIND DIRECTIONS EASTERLY FOR THE PAST SEVERAL DAYS HAS FINALLY BROKEN DOWN. RATHER THAN CANADIAN HIGH PRESSURE POKING DOWN FROM THE NORTHEAST...OUR WEATHER TODAY AND TONIGHT WILL COME UNDER THE INFLUENCE OF BERMUDA HIGH PRESSURE FROM THE EAST. THIS MEANS WINDS WILL BECOME SOUTHERLY TODAY AND SOUTH-SOUTHWESTERLY TONIGHT...WITH SPEEDS AVERAGING 10-12 KNOTS. SEAS ARE CURRENTLY 2-3 FT WITH PERIODS SPLIT BETWEEN A 6 SECOND WIND WAVE AND A WEAK 9-10 SECOND SOUTHEAST SWELL. SEAS MAY BUILD HALF A FOOT THROUGH TONIGHT AS SOUTH WINDS FURTHER DEVELOP THE WIND WAVE COMPONENT. RADAR CURRENTLY SHOWS ONLY ISOLATED SHOWERS OUT BEYOND 30 MILES FROM SHORE...BUT MODELS ARE SHOWING WE SHOULD HAVE SCATTERED SHOWERS DEVELOPING NEARSHORE NEAR AND NORTH OF CAPE FEAR THIS MORNING. CONVECTIVE ACTIVITY SHOULD LARGELY SHIFT INLAND THIS AFTERNOON AS THE SEABREEZE CIRCULATION BECOMES BETTER DEVELOPED. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...ELEMENTS REMAIN THE SAME FOR THE COASTAL WATERS THROUGH THE PERIOD AS BERMUDA HIGH PRESSURE AND THE PIEDMONT TROUGH KEEP A SOUTHWESTERLY FLOW IN PLACE. SPEEDS REMAIN STABLE IN A RANGE OF 10-15 KNOTS...WHICH IF ANYTHING MAY BE ON THE HIGHER END SATURDAY AFTERNOON AS THE TROUGH STRENGTHENS. THE TEPID INCREASE IN WINDS ISN/T ENOUGH TO IMPACT SIGNIFICANT SEAS...WHICH REMAIN IN A 2-3 FOOT RANGE. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM THURSDAY...DIFFUSE FRONT WILL REMAIN JUST INLAND...AT LEAST LOOKING AT THE LATEST WPC FORECAST AND THIS WILL KEEP A RATHER WEAK SOUTHWESTERLY FLOW IN PLACE. SPEEDS CONTINUE TO HOVER AROUND TEN KNOTS OR BELOW. CAN/T RULE OUT BRIEF DISRUPTIONS IN THE SYNOPTIC FLOW WITH INTERVALS OF CONVECTION EXPECTED BUT THIS OF COURSE IS ALL BUT IMPOSSIBLE TO FORECAST THIS FAR OUT IN TIME. SIGNIFICANT SEAS SHOW LITTLE CHANGE AS WELL WITH 2-3 FEET AND LITTLE IN THE WAY OF A SWELL COMPONENT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...SHK LONG TERM...SHK AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
729 AM EDT THU AUG 8 2013 .SYNOPSIS... MOIST HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH SATURDAY. A WEAK COLD FRONT WILL ARRIVE FROM THE NORTH ON SUNDAY. THIS FRONT WILL SLOWLY CROSS THE AREA THROUGH TUESDAY...BEFORE MOVING SOUTH OF THE AREA ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 700 AM EDT THURSDAY...ONLY A FEW LIGHT SHOWERS ARE CURRENTLY OVER NE GA AND BACK ACROSS THE WRN NC PIEDMONT. POPS HAVE BEEN TRIMMED TO MATCH THE CURRENT TRENDS. EVERYTHING ELSE LOOKS GOOD RIGHT NOW. PREVIOUS DISCUSSION...THE LATEST GSP-WSR88D WIND PROFILER DATA SHOW NORTHERLY FLOW BETWEEN 9-13 KFT. WHILE AT THE TCLT TDWR THE FLOW AT THIS LEVEL IS OUT OF THE WSW. THE TROUGH IS ALSO EVIDENT IN THE REFLECTIVITIES AS PATCHY LIGHT SHOWERS ARE MOVING OUT OF THE NORTH OVER THE CENTRAL PART OF THE UPSTATE...BUT THEY ARE MOVING FROM THE SOUTH OVER TOWARD UNION AND GAFFNEY. WHILE THIS IS A WEAK FEATURE IT MAY BE ENOUGH TO FINALLY KEEP IT DRY THROUGH SUNRISE ON THE BACK SIDE OF THE TROUGH ACROSS THE BLUE RIDGE. A COUPLE CONVECTION ALLOWING MODELS FIRE UP HEAVIER SHOWERS AND STORMS EAST OF THE TROUGH AXIS PRIOR TO SUNRISE HOWEVER. I/M NOT CERTAIN THAT THIS WON/T HAPPEN...BUT I DOUBT IT AT THIS POINT. LATER IN THE MORNING THE NAM AND RUC DEVELOP CONVECTION BACK ACROSS THE BLUE RIDGE AS A STRONGER MID-TROPOSPHERIC TROUGH APPROACHES. THIS FEATURE IS CURRENTLY EVIDENT ON THE RUC...AND MODESTLY EVIDENT ON WATER VAPOR IMAGERY...OVER MIDDLE TN AND SW KY. THE SHORT WAVE IS EXPECTED TO TRIGGER NUMEROUS SHOWERS AND TSTMS OVER MOUNTAINS AND FOOTHILLS TODAY. EVEN THE PIEDMONT MIGHT GET INTO THE ACT AS THE LLVL FLOW IS A LITTLE MORE SOUTHWESTERLY TODAY. AS SEVERAL INCHES OF RAIN HAS FALLEN OVER PARTS OF NE GA...UPSTATE SC AND THE SRN MTNS OF NC OVER THE PAST 3 DAYS...I/VE ISSUED A FLASH FLOOD WATCH FOR THIS AREA. I DID NOT TAKE IT ACROSS NRN MTNS...NRN FOOTHILLS OR THE WRN NC/SC PIEDMONT AS ANTECEDENT CONDITIONS ARE DRIER. I HOPE I DON/T REGRET THIS...BUT THE NEIGHBORING OFFICES ARE IN AGREEMENT ON THIS APPROACH AS WELL. OVERNIGHT THE AREA OF MID-LEVEL TROUGHING STRENGTHENS JUST A LITTLE WITH SOUTHWESTERLY H5 WINDS INCREASING TO 25 KTS OVER THE WRN ZONES ALONG WITH A COMMISERATE RESPONSE AND BACKING IN THE LLVL WIND FIELD. THIS MAY SET THE STAGE FOR CONVECTION TO LAST A WAYS INTO THE OVERNIGHT HOURS...OR EVEN REDEVELOP AT SOME POINT DURING THE THE NIGHT. THE FLASH FLOOD WATCH WILL BE RUN THROUGH 6 AM FRIDAY TO ACCOUNT FOR THIS. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AT 230 AM EDT THURSDAY...AN UPPER RIDGE WILL EXTEND ACROSS THE SOUTHEAST STATES ON FRIDAY...WHILE A CLOSED UPPER LOW CROSSES SOUTH CENTRAL CANADA AND AN EASTERLY WAVE MOVES INTO THE SOUTHEAST GULF OF MEXICO. THE RIDGE PERSISTS INTO SATURDAY...WHILE THE UPPER LOW REACHES EASTERN CANADA...AND THE EASTERLY WAVE REACHES THE WESTERN GULF. AN ATLANTIC SURFACE RIDGE WILL MAINTAIN A HOLD ON THE CAROLINAS AND GA ON FRIDAY...WHILE A RIVER OF GULF MOISTURE WILL EXTEND TO THE SOUTHERN APPALACHIANS. ISENTROPIC UPGLIDE OVER THE RIDGE WILL BE RATHER WEAK...AND UPSLOPE FLOW LIMITED BY THE SOUTHWESTERLY NATURE OF THE WINDS. THE RIVER OF GULF MOISTURE BECOMES REORIENTED ON SATURDAY AS THE EASTERLY WAVE AFFECTS THE GULF INFLOW...AND LOW LEVEL WINDS VEER TO THE WEST...FAVORING THE TN BORDER FOR PRECIPITATION. MEANWHILE...A SLOW MOVING COLD FRONT WILL OUT OF THE OH RIVER VALLEY...APPROACHING OUR AREA FROM THE NORTH ON SUNDAY NIGHT. WITH DEEP MOISTURE REMAINING OVER OUR AREA...POPS WILL BE ABOVE CLIMATOLOGY...AND WILL CONTINUE OVERNIGHT...DESPITE THE LACK OF WELL DEFINED FORCING. ALTHOUGH QPF WILL BE LIMITED...ESPECIALLY AS FLOW VEERS SATURDAY...THE LONG DURATION OF THE EVENT COULD PRODUCE RUNOFF PROBLEMS IN AREAS THAT HAD GREATER RAINFALL EARLIER ON. A LIMITED DIURNAL TEMPERATURE RANGE IS EXPECTED TO CONTINUE...WITH CLOUDS KEEPING MAXIMUMS SLIGHTLY BELOW NORMAL...AND MINIMUMS SLIGHTLY ABOVE NORMAL. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AT 230 AM EDT THURSDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST COAST FROM SUNDAY THROUGH WEDNESDAY. A COLD FRONT WILL DROP VERY SLOWLY SOUTH INTO THE NORTHERN PORTION OF THE AREA ON SUNDAY... CROSSING MUCH OF WESTERN NC ON MONDAY...THE INTERSTATE 85 CORRIDOR TUESDAY...AND FINALLY MOVING SOUTH OF THE AREA ON WEDNESDAY. ALTHOUGH THIS BOUNDARY WILL SERVE AS A FOCUSING MECHANISM FOR PRECIPITATION...SOUTHERLY INFLOW AHEAD OF THE FRONT IS EXPECTED TO DECREASE BASED ON A REORIENTATION OF THE SURFACE RIDGE TO THE SOUTH. UPSLOPE WILL BE LIMITED TO THE TN BORDER AREA TO BEGIN WITH AS LOW LEVEL WINDS WILL BE WESTERLY...AND WILL DIMINISH IN THE LEE OF THE MOUNTAINS AS THE FRONT SETTLES SOUTH AND WINDS VEER MORE TO THE NORTHWEST. POPS WILL REMAIN ABOVE CLIMATOLOGY...AND WITH SOME UNCERTAINTY AS TO THE TIMING OF THE FRONT...POPS WILL BE ALLOWED TO REMAIN INTO WEDNESDAY. TEMPERATURES WILL DECREASE AS HEIGHTS FALL ALOFT...BUT THE DIURNAL RANGE WILL REMAIN LIMITED DUE TO CLOUDS AND MOISTURE. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AT KCLT...MID-LEVEL CLOUDS AND LIGHT WINDS HELPED KEEP LOW STRATUS FROM DEVELOPING THIS MORNING. AFTER SUNRISE...HOWEVER...ONCE THERE IS A LITTLE HEATING SOME MVFR CIGS COULD DEVELOP...PROBABLY CLOSE TO 2KFT. WILL HINT THAT WAY WITH A SCT LAYER. SCT SHRA AND TSTMS ARE EXPECTED IN THE AFTN...THOUGH CHANCES WILL CONTINUE TO BE HIGHER A LITTLE CLOSER TO THE MOUNTAINS. STRATUS IS POSSIBLE AGAIN TONIGHT...ESPECIALLY AS THE LOW LEVEL FLOW WILL BE A LITTLE STRONGER. WENT WITH AN MVFR DECK TO ACCOUNT FOR THIS. CONFIDENCE ISN/T VERY HIGH AS A LOT WILL DEPEND ON HOW MUCH PRECIPITATION FALLS TODAY AND TONIGHT. ELSEWHERE...HIGH CLOUDS AND LIGHT LLVL WINDS HAVE KEPT STRATUS FROM DEVELOPING FOR THE MOST PART ACROSS MOST OF THE FOOTHILLS AND PIEDMONT THIS MORNING. ASHEVILLE DID GO DOWN AND SHOULD GRADUALLY LIFT OUT OF THE LIFR/VLIFR RANGE THIS MORNING. THERE IS STILL A CHANCE THAT AN MVFR OR EVEN IFR DECK WILL DEVELOP ONCE THERE IS A LITTLE HEATING AND MIXING AFTER SUNRISE. SCATTERED LAYERS WERE ADDED OUTSIDE THE MOUNTAINS TO ACCOUNT FOR THIS. AN UPPER LOW WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO THE REGION THIS AFTERNOON AND TEMPO GROUPS FOR THUNDER HAVE BEEN ADDED TO ALL THE TAF SITES. OUTLOOK...MOISTURE AND INSTABILITY CONTINUE THROUGH THE WEEKEND... LEADING TO CONTINUED CHANCES FOR MAINLY DIURNAL CONVECTION. EARLY MORNING PATCHY FOG AND LOW CLOUDS MAY OCCUR OVER AREAS OF RECENT RAINFALL AND IN MTN VALLEYS. CONFIDENCE TABLE... 11-17Z 17-23Z 23-05Z 05-11Z KCLT MED 70% HIGH 81% HIGH 100% HIGH 85% KGSP MED 67% MED 76% HIGH 87% LOW 54% KAVL MED 63% HIGH 85% MED 63% MED 76% KHKY MED 67% MED 74% MED 62% LOW 59% KGMU MED 68% HIGH 81% HIGH 87% MED 63% KAND LOW 57% HIGH 81% HIGH 100% HIGH 80% 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...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR GAZ010-017-018-026- 028-029. NC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ062>065-509-510. SC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR SCZ001>007-010>012- 019. && $$ SYNOPSIS...HG/JAT NEAR TERM...MCAVOY SHORT TERM...JAT LONG TERM...JAT AVIATION...HG/MCAVOY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
947 AM CDT THU AUG 8 2013 .UPDATE...REST OF TODAY MADE A FEW ADJUSTMENTS TO WX/POPS FOR TODAY...MAINLY JUST SHAVING OFF THE NORTH END WHERE CONDITIONS LOOK TO BE DRY NORTH OF THE STALLED FRONTAL BOUNDARY. ANY ADDITIONAL SHOWER AND STORM DEVELOPMENT THROUGH THE DAY LOOKS TO BE MAINLY NEAR AND SOUTH OF HWY 212. LATEST HRRR RUN AND LAST NIGHTS 00Z NSSL WRF RUN ALSO SUGGESTING THIS. CURRENT HIGHS APPEAR ON TRACK AT THIS POINT AND NO CHANGES THERE. READINGS WILL TOP OUT IN THE 70S FOR MOST LOCATIONS...STILL BELOW NORMAL FOR THIS TIME OF YEAR. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH SATURDAY AN AREA OF HIGH PRESSURE MOVING INTO THE REGION FROM THE NORTH WILL PUSH A WEAK FRONTAL BOUNDARY DRAPED FROM WEST TO EAST ACROSS CENTRAL SOUTH DAKOTA SOUTHWARD TODAY. MODELS GENERALLY AGREE WITH PLACEMENT OF THIS FRONTAL BOUNDARY ACROSS SOUTHERN SOUTH DAKOTA WHERE STORMS HAVE THE BEST POTENTIAL OF DEVELOPING LATER THIS AFTERNOON. BECAUSE OF THE SOUTHERN PLACEMENT OF THE FRONTAL BOUNDARY HAVE REMOVED POPS ACROSS THE NORTHERN PORTION OF THE CWA FOR THIS AFTERNOON. CANADIAN HIGH PRESSURE BUILDING INTO THE REGION TONIGHT WILL PRODUCE DRY CONDITIONS THROUGH THE DAY ON FRIDAY. RETURN FLOW WILL QUICKLY DEVELOP ON THE BACK SIDE OF THE HIGH PRESSURE ON FRIDAY NIGHT OVER THE WESTERN DAKOTAS. A FAIRLY STRONG SHORT WAVE MOVING ACROSS THE REGION WILL INTERACT WITH THE INCREASING LLM TO RESULT IN EARLY MORNING CONVECTION FOR THE WESTERN CWA ON SATURDAY. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY NIGHT DESPITE ALLBLEND`S GENEROUS SMATTERING OF POPS OVER SEVERAL OF THE EXTENDED FORECAST PERIODS...SATURDAY NIGHT/SUNDAY STILL STANDS THE BEST CHANCE OF NUMEROUS/WIDESPREAD COVERAGE OF SHOWERS AND THUNDERSTORMS. INSTABILITY/SHEAR AND FORCING IS ALL THERE IN SUPPORT OF SOME SORT OF ORGANIZED CONVECTIVE SYSTEM EVOLVING/MOVING ACROSS THE CWA SATURDAY NIGHT INTO SUNDAY MORNING. BEYOND THAT...AS WAS PREVIOUSLY MENTIONED...DETAILS GET A LITTLE BIT FUZZIER AS SOLUTIONS BEGIN TO DIVERGE ON THE HANDLING OF PLACEMENT/STRENGTH OF THE WESTERN CONUS UPPER LEVEL RIDGE /AND ANY SHORT-WAVE IMPULSES EMBEDDED WITHIN THE FLOW/ WHICH IS THOUGHT TO BE SHIFTING A BIT EAST TOWARD THE DAKOTAS BY MID-WEEK. ALSO STILL LOOKS AS THOUGH TEMPERATURES MAY TRY TO MODERATE/WARM-UP A BIT TOWARD THE MID TO LATE PART OF THIS COMING WEEK...AT LEAST...CLOSER TO NORMAL FOR AUGUST. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS JUST A COUPLE OF WEAK SHOWERS LEFT ACROSS THE CWA THIS MORNING AS FORCING/LIFT FOR CONVECTION IS DIMINISHING. CURRENT VFR CONDITIONS...EXCEPT AT KATY /MVFR CIGS THERE/...ARE EXPECTED TO CONTINUE TODAY AND TONIGHT. KATY SHOULD SEE CONDITIONS GRADUALLY IMPROVING BY LATE THIS MORNING/EARLY AFTERNOON TO VFR. A FEW SHOWERS AND THUNDERSTORMS COULD FIRE ALONG/SOUTH OF A SLOWLY SAGGING FRONTAL BOUNDARY. KPIR COULD SEE A COUPLE OF THESE STORMS NEARBY. BUT OVERALL...DRY CONDITIONS AMID GOOD VFR IS EXPECTED TO PREVAIL. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...TMT SHORT TERM...SD LONG TERM...DORN AVIATION...DORN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
752 AM EDT THU AUG 8 2013 .SYNOPSIS... A COUPLE OF DISTURBANCES SHIFT ACROSS THE AREA THROUGH TONIGHT. A FRONT MOVES INTO THE MOUNTAINS BY SATURDAY AND SLOWLY SHIFTS TO THE SOUTH OF US AFTER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 720 AM EDT THURSDAY... POCKETS OF SHOWERS/ISOLATED THUNDER MOVING ACROSS SE WV AT THE MOMENT WILL AFFECT THE ALLGHENY HIGHLANDS SOON...WITH ISOLATED SHOWERS PUSHING ACROSS THE TRIAD OF NC. FURTHER WEST A LINE OF SHOWERS AND STORMS EXTENDS FROM LONDON KY WSW TO NASHVILLE TN. THE LATEST HRRR APPEARS TO BE PICKING THIS UP PRETTY WELL BUT LINGERS IT GOING INTO THIS MORNING WITH ONLY SCATTERED SHOWERS AFFECTING THE WESTERN CWA. THE 00Z ECM MODEL WAS STILL DOING A GOOD ENOUGH JOB BRINGING EMBEDDED IMPULSE OVER WV THIS MORNING INTO THE SHENANDOAH VALLEY THIS AFTERNOON...WHILE THE KY WAVE MOVING INTO FAR SW VA INTO NE TN. MADE SOME MINOR ADJUSTMENTS TO POPS BUT OVERALL CONFIDENT IN HIGH CHANCE TO LIKELYS WEST TO LOWER CHANCES OUT EAST. IF THERE IS ANY SUN...THE THUNDERSTORM CHANCES WILL INCREASE...BUT OVERALL LOOKS LIKE ANOTHER MOSTLY CLOUDY TO OVC DAY IN THE GRAND SCHEME OF THINGS. PREVIOUS VALID DISCUSSION... WITH PWATS AROUND 2.0 THE STORMS WILL BE EFFICIENT HEAVY RAIN PRODUCERS...BUT GIVEN LACK OF WIDESPREAD RAINFALL LATELY A FLASH FLOOD WATCH IS NOT WARRANTED. HOWEVER...SOME PLACES LIKE SUMMERS COUNTY WV WHICH SAW SOME HEAVY RAIN WEDNESDAY IS MORE LIKELY TO BE IMPACTED IF HEAVY RAIN MOVES SLOWLY OVER THEM TODAY. WILL HOLD OFF AND SEE HOW THE CONVECTION TRANSPIRES TODAY BEFORE ISSUING A WATCH. THE ONE MAIN VORT MOVES EAST OF THE CWA BY EVENING SO EXPECT SOME WEAKENING/DIMINISHING TREND IN THE POPS OUT EAST. THE FLOW ALOFT AND MODEL VORTICITY FIELDS OF THE ECMWF CONTINUE TO SHOW EMBEDDED WAVES MOVING FROM KENTUCKY INTO VIRGINIA/WEST VIRGINIA TONIGHT...AND POSSIBLY INTO NC. LIKE THE ECMWF IDEA OF MAINTAIN HIGHER POPS ACROSS SE WV INTO FAR SW VA...WITH LESS IN THE SOUTHEAST. FOR TEMPS TODAY AND TONIGHT KEPT CLOSE TO WEDNESDAYS HIGHS WITH MID 70S NC MOUNTAINS TO NEAR 80S BLF-BCB AND LOWER TO MID 80S EAST. TONIGHT...SAME AIRMASS SO LOW SHOULD BE IN THE MID TO UPPER 60S WEST TO LOWER 70S EAST. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... AS OF 400 AM EDT THURSDAY... LOOKING AT AN INCREASED THREAT OF LOCALLY HEAVY RAIN AND POSSIBLY FLASH FLOODING ON FRIDAY AS A STRONG SHORTWAVE TROUGH PASSES EAST ACROSS THE GREAT LAKES DURING THE AFTERNOON AND EVENING. THE COMBINATION OF DEEP ATMOSPHERIC MOISTURE BUILDING ALONG THE CENTRAL APPALACHIAN CHAIN AHEAD OF THE TROUGH...MODEST INSTABILITY AND RELATIVELY LIGHT WINDS ALOFT WILL RESULT IN SCATTERED SLOW MOVING STORMS WITH HIGH RAINFALL RATES. THE NEED FOR A FLASH FLOOD WATCH APPEARS LIKELY FOR SOME AREAS WEST OF THE BLUE RIDGE FOR FRIDAY... BUT WHICH COUNTIES TO INCLUDE IN A WATCH REMAINS UNCLEAR. WOULD LIKE TO SEE HOW RAINFALL DEVELOPS THURSDAY AFTERNOON AND EVENING BEFORE FINALIZING ANY DETAILS OF A POTENTIAL WATCH. IN ANY EVENT...RAINFALL WILL DIMINISH IN INTENSITY DURING LATE EVENING AS INSTABILITY DECREASES AND WINDS SHIFT MORE WESTERLY...RESULTING IN MORE OF A DOWNSLOPE WINDFLOW. THE SHORTWAVE TROUGH WILL PASS RAPIDLY ACROSS EASTERN CANADA SATURDAY MORNING...GIVING A SOUTHWARD PUSH TO A STATIONARY FRONT NEAR THE OHIO RIVER VALLEY. THE FRONT WILL ADVANCE TO AROUND THE INTERSTATE 81 CORRIDOR BY SATURDAY EVENING...AND INTO THE CAROLINAS BY SUNDAY EVENING. SIGNIFICANTLY DRIER AIR WILL LAG BEHIND THE COLD FRONT HOWEVER...AND WILL EXPECT REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS FOR SATURDAY AND SUNDAY AFTERNOON/EVENING...MORE SPOTTY IN NATURE...WITH COVERAGE CONCENTRATED MORE ACROSS THE MOUNTAINS...ESPECIALLY IN OUR NORTHWEST FLOW UPSLOPE AREAS. BY LATE SUNDAY NIGHT...DRIER AIR WILL WORK ITS WAY INTO THE MOUNTAINS... LOWERING DEWPOINTS INTO THE UPPER 50S AND LOW 60S. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 400 PM EDT WEDNESDAY... WITH THE UPPER RIDGE CONSOLIDATING AND MOVING TO THE FOUR CORNERS REGION...TROUGHING WILL DEEPEN AND STRENGTHEN ACROSS THE EAST AND MIDDLE ATLANTIC. WITH THE COOLER TEMPS AND LESS MOISTURE...SHOWERS AND STORMS WILL BECOME LESS LIKELY AND SUPPRESSED SOUTH AS THE WEEK WEARS ON. HOWEVER...CAN`T TOTALLY RULE OUT A FEW POP UP SHOWERS REGIONWIDE WITH SUCH CHILLY TEMPS ALOFT FOR THIS TIME OF YEAR. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 740 AM EDT THURSDAY... GOING TO SEE SKIES STAYING BKN-OVC TODAY WITH MOSTLY VFR TAKING PLACE. OVERALL LOOKING AT RAIN SHOWERS AND STORMS MOVING INTO THE WV MTNS LATER THIS MORNING THEN INCREASING INTO THE BCB/ROA AREA BY MIDDAY. HAVE ADDED PREDOMINANT SHOWERS AT THESE SITES WITH CONFIDENCE HIGH THAT BLF/LWB WILL GET MVFR VSBYS WITH MODERATE SHOWERS AND ISOLATED THUNDER DURING THE AFTERNOON. LOOKS LIKE DANVILLE WILL BE THE ONLY SITE THAT HAS A LOWER THREAT SO KEPT EVEN VCTS OUT THERE. THE SHOWERS WILL BE LINGERING AS ANOTHER WAVE MOVES INTO THE MOUNTAINS LATER TONIGHT. WILL BE ENOUGH CLOUD COVER FOR MVFR TO POTENTIAL IFR CIGS AT ALL SITES TONIGHT WITH POTENTIAL FOG IF LOWER CLOUDS CLEAR OUT SOME. BY FRIDAY-MONDAY A FRONTAL BOUNDARY WILL BE IN THE VICINITY TO SEE MORE COVERAGE OF SHOWERS/STORMS AREA WIDE. THIS WILL KEEP TERMINALS DEALING WITH DELAYS DUE TO STORMS...BUT OVER HALF THE TIME...IT SHOULD BE VFR. DRIER AIR PUSHES INTO NORTH ON MONDAY WITH SCATTERED CONVECTION STILL POSSIBLE ESPECIALLY IN THE SOUTH. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...NF LONG TERM...KM AVIATION...DS/WP
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1032 AM CDT THU AUG 8 2013 .UPDATE... BROKEN CLOUD DECK OVER THE SOUTHWEST AREA AND BROKEN CLOUD DECK OVER NORTHWEST WISCONSIN EXPECTED TO MIX OUT LATER THIS MORNING. BASED ON CURRENT MOVEMENT AND RAP FORECAST 700 MB RH...THE CLOUD DECK TO THE NORTHWEST LOOKS TO ARRIVE IN NORTHWEST SAUK AND MARQUETTE COUNTY BY 18Z. BY THEN THE DECK IS EXPECTED TO BE SCATTERED OUT. HIGHS IN THE MID TO UPPER 70S STILL SEEM REASONABLE. RIGHT NOW HAVE COOLER TEMPS FORECAST NEAR THE LAKE WITH THE EAST WINDS...BUT MKE...RAC...AND ENW HAVE ALREADY REACHED 70 DEGREES...SO WOULDN/T BE SURPRISED IF THEY MADE IT TO THE MID 70S THERE AS WELL. && .AVIATION/18Z TAFS/... MVFR CIGS ACROSS THE WESTERN HALF OF THE FORECAST AREA WILL LIKELY SCATTER LATE THIS MORNING...WITH BASE HEIGHTS ALSO RISING. VFR CONDITIONS ARE THEN EXPECTED THIS AFTERNOON THROUGH FRIDAY. COULD SEE A FEW SHOWERS LATE TONIGHT INTO FRIDAY...BUT ANY PRECIP WOULD BE LIGHT. && .PREV DISCUSSION... /ISSUED 330 AM CDT THU AUG 8 2013/ SHORT TERM... TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH DRY HIGH PRESSURE SETTLES OVER SOUTHERN WISCONSIN TODAY. KEPT TEMPERATURES CLOSE TO PREVIOUS FORECAST AS 925 MB TEMPERATURES SUPPORT UPPER 70S INLAND...WITH COOLER READINGS ALONG AND EAST OF THE KETTLE MORAINE DUE TO LIGHT EAST WINDS OFF OF LAKE MICHIGAN. NAM IS THE MOST PRODUCTIVE MODEL WITH PRECIPITATION ALONG SURFACE TROUGH TONIGHT. IN SPITE OF A SHARPER MID LEVEL TROUGH AND ..FRONTOGENETIC FORCING AND Q-VECTOR CONVERGENCE RELATIVELY WEAK AND WITH OTHER MODELS BARELY SHOWING ANY FORCING OR PCPN WILL HOLD POPS TO SCATTERED. WILL KEEP PRECIPITATION TYPE AS RAIN SHOWERS WITH MINIMAL ELEVATED CAPE...THOUGH NAM HAS 200 J/KG...AND EQUILIBRIUM LEVELS BARELY MAKING IT TO -10C. WHILE A RUMBLE OF THUNDER NOT OUT OF THE QUESTION TOO LOW A PROBABILITY TO MENTION. NAM HAS MORE OF A 925 MB THERMAL RIDGE PASSING THRU OVERNIGHT AND IS ABOUT 1C TO 2C WARMER THAN GFS OR ECMWF. HOWEVER ALL MODELS SHOWING COOLING TEMPS THROUGH 06Z OR SO THEN LEVELING OUT WITH INCREASING CLOUDS AND WEAK WAA WITH SWLY WINDS AHEAD OF TROUGH. FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. THE SURFACE TROUGH IS EXPECTED TO CLEAR SOUTHEAST WI BY 18Z FRIDAY. KEPT THE SCATTERED SHOWERS IN THERE UNTIL THAT TIME. SOME MODELS MAINTAIN THAT THE FORCING WILL NOT BE STRONG ENOUGH TO SUSTAIN ANY SHOWERS INTO SOUTHEAST WI FRIDAY MORNING...SO LOWER CONFIDENCE IN THE POP VALUES. EXPECT SOME SUNSHINE TO RETURN IN THE AFTERNOON AS DRY AIR AND HIGH PRESSURE SPREAD BACK INTO THE REGION. TEMPS WILL REBOUND INTO THE UPPER 70S. SATURDAY THROUGH SUNDAY...FORECAST CONFIDENCE HIGH. SURFACE HIGH PRESSURE WILL SETTLE OVER THE GREAT LAKES REGION ONCE AGAIN WHILE THE 500MB FLOW REMAINS IN A PERSISTENT PATTERN WITH RIDGING OVER THE WEST AND SLIGHT TROUGHING OVER THE EAST. 925MB TEMPS WILL DROP TO AROUND 14C EARLY SATURDAY MORNING OVER SOUTHERN WI...WITH FRI NIGHT LOWS DROPPING INTO THE LOWER 50S. HIGHS ON SATURDAY WILL BE IN THE MID 70S ONCE AGAIN AND THERE SHOULD BE PLENTY OF SUNSHINE. TEMPS WILL BE COOLER NEAR THE SHORE DUE TO A LAKE BREEZE. SUNDAY WEATHER WILL BE QUIET...BUT EXPECT INCREASING MID AND HIGH CLOUDS WITH ANOTHER SYSTEM APPROACHING. HIGHS WILL BE JUST A BIT WARMER WITH RETURN FLOW AROUND THE DEPARTING SURFACE HIGH. LONG TERM... SUNDAY NIGHT AND BEYOND...FORECAST CONFIDENCE MEDIUM. THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE SUNDAY NIGHT AND MONDAY AS A 500MB TROUGH SWINGS DOWN ACROSS WISCONSIN. THERE IS DECENT SUPPORT FROM AN 850MB LOW LEVEL JET NOSING INTO WI AND UPPER DIVERGENCE ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF AN UPPER JET MOVING ACROSS THE STATE. THE MODELS ARE ALL SHOWING MORE QPF WITH THIS FEATURE NOW...SO THERE IS INCREASING CONFIDENCE IN AT LEAST SCATTERED STORM DEVELOPMENT. SURFACE HIGH PRESSURE WILL SETTLE BACK INTO WISCONSIN BY MONDAY EVENING AS THE UPPER LEVEL TROUGH AMPLIFIES OVER THE NORTHEAST AND THE UPPER LEVEL RIDGE AMPLIFIES OVER THE SOUTHWEST. THE ECMWF IS CONTINUING TO BRING AN UPPER TROUGH THROUGH WI ON WED WHICH WOULD GENERATE SHOWERS...WHILE THE GFS MAINTAINS UPPER RIDGING. SINCE THE 00Z ECMWF CAME IN DRY ACROSS SOUTHERN WI WITH ONLY LIGHT QPF ACROSS NORTHERN WI...OPTED TO REMOVE THE MENTION OF PRECIP FROM THE MKX AREA PER COORDINATION WITH SURROUNDING OFFICES. TEMPS WILL REMAIN STEADY AND JUST A LITTLE BELOW NORMAL THROUGH THE END OF NEXT WEEK. AVIATION/12Z TAFS/... ONCE ANY PATCHY MVFR FOG LIFTS BY MID-MORNING...EXPECTING VFR CONDITIONS THROUGH THE REMAINDER OF THE FORECAST. WILL SEE BRIEF MVFR CONDITIONS WITH SCATTERED RAIN SHOWERS AFTER 06Z...MAINLY FOR KMSN. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...MEB/DDV TODAY/TONIGHT AND AVIATION/MARINE...REM FRIDAY THROUGH WEDNESDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
615 AM CDT THU AUG 8 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 344 AM CDT THU AUG 8 2013 AT 3 AM...A RIDGE OF HIGH PRESSURE EXTENDED FROM NORTHWEST MINNESOTA SOUTHEAST INTO THE UPPER MISSISSIPPI RIVER VALLEY. THIS HIGH IS PRODUCING LIGHT WINDS ACROSS THE REGION. LOOKING OUT ACROSS THE MISSISSIPPI RIVER...ONE CAN SEE THAT THE BOUNDARY LAYER EXTENDS UP TO THE RIDGE TOPS AND IT IS SLOWLY MOISTENING. THERE IS ALSO SIGNS THAT A STRATUS DECK STARTING TO DEVELOP AROUND 500 TO 600 FEET ABOVE THE VALLEY FLOOR. THE TEMPERATURE AND DEW POINT SPREAD AT LA CROSSE HAS FALLEN TO 1 DEGREE AND THE VISIBILITY HAS RECENTLY DROPPED TO 4 MILES. THERE IS STILL SOME CONCERN THAT THE CLOUDS STREAMING OFF OF THE CONVECTION OVER SOUTH DAKOTA MIGHT KEEP WIDESPREAD VALLEY FOG FROM DEVELOPING...SO JUST WENT WITH AREAS OF FOG AT THIS TIME. WILL CONTINUE TO MONITOR THROUGH THE REMAINDER OF THE NIGHT FROM THE ROAD AND OUR CAM. FROM TODAY THROUGH TONIGHT...A COLD FRONT...CURRENTLY EXTENDING FROM DULUTH MINNESOTA TO PIERRE SOUTH DAKOTA...WILL MOVE SLOWLY SOUTH THROUGH CENTRAL MINNESOTA AND NORTHERN WISCONSIN TODAY...AND THROUGH MUCH OF OUR FORECAST AREA TONIGHT. AREAS ALONG AND NORTH OF THE INTERSTATE 90 CORRIDOR WILL REMAIN IN THE RIGHT ENTRANCE REGION OF A 110 KNOT JET. ONE CAN SEE THE UNDULATIONS ASSOCIATED WITH THIS JET FROM ABERDEEN SOUTH DAKOTA EAST TO THE TWIN CITIES. IN ADDITION...THE ML CAPES CLIMB UP TO 500 J/KG IN THIS SAME AREA BETWEEN 08.21Z AND 09.03Z...AND WEAK 900 TO 700 MB FRONTOGENESIS. THIS IS ENOUGH FORCING AND INSTABILITY FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP. THE DETERMINISTIC MODELS ARE MUCH MORE ROBUST WITH THEIR PRECIPITATION CHANCES THAN WHAT THE ARW OR NMM WOULD SUGGEST. AS A RESULT...JUST WENT WITH A 20 TO 40 PERCENT CHANCE OF RAIN ASSOCIATED WITH THIS FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 251 AM CDT THU AUG 8 2013 ON FRIDAY MORNING...THE COLD FRONT WILL MOVE SOUTH THROUGH NORTHEAST IOWA AND SOUTHWEST WISCONSIN. AS THIS IS OCCURRING...IT WILL BE LOSING THE 900 TO 800 MB FRONTOGENESIS...BUT THERE WILL STILL BE WEAK 800 TO 600 MB FRONTOGENESIS. AS A RESULT...KEPT A 20 TO 30 PERCENT CHANCE RAIN ACROSS THIS AREA. FROM LATE SATURDAY NIGHT INTO MONDAY MORNING...THE 08.00Z ECMWF...GEM...AND GFS ARE NOW IN AGREEMENT WITH THEIR TIMING OF A COLD FRONT THROUGH THE AREA. BOTH THE GEM AND GFS HAVE BEEN VERY CONSISTENT WITH THE TIMING OF THIS FRONT AND ITS UPPER LEVEL SHORT WAVE. MEANWHILE THE ECMWF HAS SLOWED ITS PASSAGE OF THIS FRONT BY NEARLY 24 HOURS FROM ITS 07.12Z RUN. AS A RESULT...MUCH UNCERTAINTY STILL REMAINS WITH THIS SYSTEM. DUE TO THIS...STAYED WITH THE ALL BLEND PRECIPITATION CHANCES. WHILE THERE HAS BEEN ISSUES WITH TIMING...THE MODELS HAVE BEEN CONSISTENTLY SHOWING THAT THERE WILL BE RATHER LIMITED 925 TO 850 MB MOISTURE TRANSPORT INTO THE AREA...AND THAT THE ML CAPES WILL REMAIN LESS THAN 1000 J/KG. WITH THE 0-3 KM AND 0-6 KM MARGINAL SHEAR...NOT ANTICIPATING ANY SEVERE WEATHER WITH THIS FRONTAL PASSAGE. FROM TUESDAY NIGHT INTO WEDNESDAY...BOTH THE GFS AND ECMWF ARE SHOWING THAT MUCH OF THE FORECAST AREA WILL BE STILL UNDER THE INFLUENCE OF A CANADIAN HIGH PRESSURE SYSTEM. THIS TREND HAS BEEN RATHER CONSISTENT DURING THE LAST 3 RUNS OF ECMWF. THE ONLY PLACE THAT MAY SEE SOME SHOWERS AND THUNDERSTORMS IS NORTH OF THE INTERSTATE 90 WHERE A SHORT WAVE MOVING THROUGH NORTHERN MINNESOTA AND UPPER MICHIGAN MAY PRODUCE ENOUGH LIFT AND MOISTURE TRANSPORT INTO THE AREA FOR SOME SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP. SINCE IT LOOKS DRY...REMOVED THE PRECIPITATION CHANCES THAT THE ALL BLEND PRODUCED ACROSS THE ENTIRE AREA ON TUESDAY NIGHT...AND ACROSS NORTHEAST IOWA...AND CENTRAL AND SOUTHWEST WISCONSIN ON WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 615 AM CDT THU AUG 8 2013 VALLEY FOG STILL A CONCERN AT KLSE. WHILE SFC WINDS HAVE BEEN LIGHT TO CALM...JUST OFF THE SFC THE WINDS CONTINUE TO STIR...HAMPERING DENSE FOG FORMATION. RAP BUFKIT SOUNDINGS HAVE TRENDED LIGHTER WITH THE NEAR SFC WINDS...AND WINDS WERE LIGHT AT THE NWS ARX OFFICE...600 FT OFF THE VALLEY FLOOR. VISUAL INTO THE VALLEY SHOWS SOME LOW STRATUS HANGING ABOVE THE MISSISSIPPI. T/TD SPREAD HAS HELD AT 2 F THROUGH THE OVERNIGHT. STILL...SEE SOME POTENTIAL IT COULD DROP TO 1SM OR SO IN THE 12-14Z TIME FRAME...AND IF SO...WOULD QUICKLY MIX OUT AFTER THAT. WILL MONITOR TRENDS UP TO TAF ISSUANCE. BCFG MIGHT MOST APPROPRIATE. EXPECT INCREASING CLOUDS FROM THE WEST TODAY INTO TONIGHT...ASSOCIATED WITH AN APPROACHING SFC TROUGH AND UPPER LEVEL ENERGY. ENOUGH LIFT TO TRIGGER SCT SHRA/TS...ALTHOUGH THE TS WILL LIKELY BE MORE ISOLATED AS INSTABILITY IS LIMITED AND CONFINED TO THE LATE AFTERNOON/EVENING HOURS. WILL CONTINUE VCSH MENTION IN THE TAFS FOR NOW...ALLOWING FOR INCREASED CONFIDENCE TO REFINE TIMING AND CONDITIONAL WORDING AS NEEDED. BUFKIT SOUNDINGS AND RH FIELDS DO POINT TO A LOWERING OF CIG DECK/SWITCH IN WINDS AS THE TROUGH SINKS SOUTH OVERNIGHT. WILL TREND THIS WAY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM....BOYNE AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
533 AM MDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON) ISSUED AT 312 AM MDT THU AUG 8 2013 AREAS OF FOG HAVE DEVELOPED ACROSS FAR SOUTHEAST WY THIS MORNING IN RESPONSE TO MOIST SOUTH-TO-SOUTHEAST LLVL FLOW ALONG AND EAST OF THE LARAMIE RANGE. VSBYS AT KCYS HAVE BEEN REDUCED TO ONE QUARTER OF A MILE AT TIMES OVER THE PAST FEW HOURS...AND AREA WEBCAMS SHOW DENSE FOG TO BE FAIRLY WIDESPREAD ACROSS CENTRAL AND EASTERN PORTIONS OF LARAMIE COUNTY. MAIN QUESTION IS HOW LONG THIS FOG WILL LAST AS WINDS MAY DEVELOP A SLIGHT SOUTHWEST COMPONENT EARLY THIS AM...WHICH WOULD TEND TO SCOUR OUR EXISTING LLVL MOISTURE. ASSOCIATED -DZ COULD ALSO LIMIT DENSE FOG POTENTIAL. LATEST HRRR RUNS STILL SHOW VERY LOW VSBYS THROUGH ABOUT 15Z THOUGH...SO HAVE ISSUED A DENSE FOG ADVISORY FOR THE I80 CORRIDOR BETWEEN THE SUMMIT AND NEBRASKA STATE LINE THROUGH MID AM TO COVER AT LEAST THE NEAR TERM THREAT FOR HAZARDOUS TRAVEL. EVEN IF FOG DOES NOT PERSIST...LOW STRATUS SHOULD CREATES A FORECAST HEADACHE FOR THU AFTN AND EVE. 11-3.9 MICROMETER IR CHANNEL SUGGESTS LLVL CLOUDS ARE BECOMING RATHER WIDESPREAD FROM THE LARAMIE RANGE EWD INTO THE WESTERN NE PANHANDLE. MIGHT BE TOUGH TO BURN OFF CLOUD COVER TODAY AS EASTERLY UPSLOPE FLOW BECOMES ESTABLISHED OVER THE HIGH PLAINS. GIVEN THIS AND 700 MILLIBAR TEMPS TO BE PROGGED ABOUT 1-2 DEG COOLER THAN WED...HAVE TRENDED A FEW DEGREES BELOW MOS GUID FOR FCST HIGHS WHERE CLOUDS SHOULD BE THICKEST. NATURALLY THIS ALSO LEADS TO QUESTIONS WITH INSTABILITY AND POSSIBLE CONVECTION LATER IN THE DAY ON TOP OF AN ALREADY COMPLICATED SYNOPTIC SETUP. A DIRTY UPPER-LEVEL RIDGE WILL BUILD INTO SOUTH CENTRAL WY THIS AFTN WITH NUMEROUS MIDLVL DISTURBANCES LIKELY INTERACTING WITH MONSOONAL MOISTURE IN THE 700-300 MILLIBAR LAYER. THIS...ALONG WITH UPPER-LEVEL DIVERGENCE IN THE RIGHT REAR QUADRANT OF A MIDWEST US JET STREAK AND UPSLOPING LLVL FLOW SHOULD CONTRIBUTE TO SUFFICIENT LIFT FOR SHOWER AND TSTM DEVELOPMENT LATER TODAY. THE BEST DYNAMICS APPEAR TO DROP TO THE SOUTH WITH A STRONGER WAVE EVIDENT ON WATER VAPOR SATELLITE OVER EASTERN UT AND WESTERN CO...WHICH COULD LIMIT OVERALL COVERAGE OF PCPN IN OUR CWA. ESSENTIALLY BETWEEN SYSTEMS...FLOW ALOFT SHOULD BE WEAK WITH ONLY AROUND 10-15 KTS OF 700-500 MILLIBAR FLOW. LESS THAN 30 KTS OF EFFECTIVE SHEAR SHOULD KEEP SEVERE STORMS AT BAY... EVEN IF THE MUCH MORE UNSTABLE NAM WOULD VERIFY WITH SURFACE CAPES IN EXCESS OF 1500 J/KG. THINKING INSTABILITY WILL BE MODEST AT BEST THOUGH WITH LIMITED DAYTIME HEATING...BUT MIDLVL COOLING WILL YIELD SUFFICIENT ELEVATED INSTABILITY FOR TSTM DEVELOPMENT. OVERALL THREAT FROM CONVECTION WILL BE HEAVY RAIN FROM SLOW MOVING STORMS...THOUGH PWATS ARE NOT PARTICULARLY HIGH WITH SOME MOISTURE BEING ROBBED BY THE SYSTEM TO THE SOUTH. TRYING NOT TO SOUND LIKE A BROKEN RECORD...PERSISTENCE IS THE NAME OF THE GAME AS WE HEAD INTO FRIDAY. SEVERAL WEAK DISTURBANCES ARE LIKELY TO TRAVERSE THE FLOW ALONG THE EDGE OF THE CENTRAL ROCKIES RIDGE...MOST OF WHICH ARE TOO WEAK TO ACCURATELY PREDICT WITH ANY REASONABLE DEGREE OF ACCURACY. WITH ABUNDANT SUBTROPICAL MOISTURE REMAINING IN PLACE OVER THE AREA...OVERALL PATTERN FAVORS ANOTHER COOL DAY WITH SCATTERED SHOWERS AND STORMS WITH CONTINUED UPSLOPE FLOW IN THE LLVLS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 342 AM MDT THU AUG 8 2013 ACTIVE WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE EXTENDED FORECAST PERIOD. THE ONLY POTENTIAL CHANGE IS FOR THE UPPER LEVEL RIDGE CURRENTLY OVER THE ROCKIES TO EXPAND NORTHWARD. BOUTS OF MONSOON MOISTURE SHOULD CONTINUE TO SNEAK UNDER THE RIDGE AND INFLUENCE THE FORECAST AREA WITH CHANCES FOR AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...WHILE TEMPERATURES SHOULD BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD. WITH THE RIDGE IN PLACE UPPER LEVEL WINDS WILL BE ON THE LIGHT SIDE WHICH SHOULD SERVE TO MINIMIZE SEVERE WEATHER CHANCES. HIGH TEMPERATURES WILL MAINLY BE IN THE 80S WITH LOWS IN THE 50S FOR AREAS OUTSIDE OF THE MOUNTAINS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 412 AM MDT THU AUG 8 2013 WIDESPREAD LOW CLOUDS AND FOG WILL BE FOUND OVER SOUTHEAST WYOMING MAINLY EAST OF THE LARAMIE RANGE EARLY THIS MORNING WITH AREAS OF DENSE FOG. CEILINGS WILL DROP TO ONLY A FEW HUNDRED FEET AGL WITH VISIBILITIES 1/4 MILE OR LESS AT TIMES. FOG WILL ALSO BE FOUND OVER PORTIONS OF THE NEBRASKA PANHANDLE. FOG WILL BEGIN TO LIFT AFTER SUNRISE BUT SOME FOG AND LOW CLOUDS TO HANG THROUGH LATE THIS MORNING. ATTENTION TURNS TO CHANCES FOR THUNDERSTORMS THIS AFTERNOON. EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING THIS AFTERNOON BUT ACTUAL COVERAGE WILL DEPEND ON HOW LONG THE FOG HOLDS THIS MORNING. GUSTY WINDS AND SMALL HAIL POSSIBLE WITH SOME THUNDERSTORMS THIS AFTERNOON AND EVENING. FOG MAY REDEVELOP AFTER MIDNIGHT TONIGHT IN THE EAST. && .FIRE WEATHER... ISSUED AT 312 AM MDT THU AUG 8 2013 FIRE WEATHER CONCERNS WILL BE MINIMAL OVER THE NEXT FEW DAYS AS MONSOON MOISTURE REMAINS IN PLACE OVER THE REGION. TEMPERATURES WILL BE NORMAL OR SLIGHTLY BELOW WITH AT LEAST SCATTERED SHOWERS AND STORMS EACH AFTERNOON AND EVENING THROUGH FRIDAY. DRYING IS EXPECTED ACROSS WESTERN CARBON AND CONVERSE COUNTIES DURING THE WEEKEND WITH AFTERNOON RELATIVE HUMIDITY VALUES FALLING BELOW 15 PERCENT. HOWEVER WINDS ARE EXPECTED TO REMAIN BELOW THE CRITICAL THRESHOLDS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...DENSE FOG ADVISORY UNTIL 9 AM MDT THIS MORNING FOR WYZ117>119. NE...NONE. && $$ SHORT TERM...HAMMER LONG TERM...LIEBL AVIATION...LIEBL FIRE WEATHER...HAMMER
AREA FORECAST DISCUSSION
NWS EUREKA CA
349 PM PDT THU AUG 8 2013 .SYNOPSIS...AN UPPER LEVEL LOW CONTINUES TO SIT JUST OFFSHORE. THIS MAY BRING SOME ISOLATED THUNDERSTORMS TO THE INLAND AREAS THIS EVENING AND TONIGHT...MAINLY NORTH OF HIGHWAY 36. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ALONG THE COAST TONIGHT NORTH OF ORICK. FRIDAY THUNDERSTORMS ARE POSSIBLE AGAIN BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND. && .SHORT TERM...UPPER LEVEL LOW CONTINUES TO SIT AND SPIN THIS AFTERNOON. IT CURRENTLY IS CENTERED SOUTHWEST OF CAPE MENDOCINO. THIS IS CONTINUING TO BRING SHOWERS AND THUNDERSTORMS TO NORTHERN CA. HOWEVER...IN THE EUREKA CWA CONVECTION IS STRUGGLING. THIS LOOKS TO BE DUE A AN AREA OF POOR LAPSE RATES AROUND 600 MB. THE NAM AND RUC ARE STILL INDICATING THAT LATER THIS EVENING A FEW SHOWERS WILL POP UP...MAINLY IN TRINITY COUNTY. TRIMMED BACK POPS SLIGHTLY FOR THIS AFTERNOON...BUT MAINLY LEFT THINGS ALONE WITH ISOLATED TO SCATTERED COVERAGE. ALONG THE COAST SKIES HAVE PARTIALLY CLEARED OUT WITH THE INCREASED MIXING...BUT EXPECT CLOUDS WILL RETURN THIS EVENING. THIS INCREASED MIXING HAS ALSO LIFTED TEMPERATURES INTO THE LOW 60S AT THE COAST. LATE TONIGHT INTO FRIDAY MORNING THE MODELS ARE SHOWING A SHORTWAVE ROTATING AROUND THE LOW. MODELS ARE INDICATING SOME ELEVATED INSTABILITY WITH THIS SO IT MAY KICK OFF A FEW THUNDERSTORMS. THE BEST CHANCE WILL BE NORTH OF HWY 299. SINCE THESE ARE ELEVATED SEE NO REASON IF THEY DO FORM THAT THEY WONT MAKE IT ALL THE WAY THE COAST. AS WITH MOST NOCTURNAL THUNDERSTORMS IN THIS AREA CONFIDENCE IS LOW. THERE IS AN OUTSIDE CHANCE A FEW COULD MAKE IT AS FAR SOUTH AS EUREKA...BUT WAS NOT CONFIDENT ENOUGH IN THIS TO PUT THEM IN THE FORECAST. FRIDAY AFTERNOON THERE IS AN ADDITIONAL CHANCE FOR THUNDERSTORMS OVER THE INLAND AREAS. LAPSE RATES LOOK MARGINAL...SO LEFT THE FORECAST BASICALLY UNCHANGED. ALONG THE COAST EXPECT THERE WILL BE CLEARING AGAIN IN THE AFTERNOON AND TEMPERATURES MAY REACH THE LOW 60S ONCE AGAIN. INLAND TEMPERATURES WILL BE SIMILAR TO TODAY AS WELL. SATURDAY AND SUNDAY THE LOW STARTS TO PULL OFF TO THE NORTH AND THE AIR STABILIZES. SATURDAY THERE IS AN SLIGHT CHANCE FOR SOME THUNDERSTORMS ALONG THE SISKIYOU/TRINITY COUNTY...BUT EVEN THAT IS DOUBTFUL. TEMPERATURES INLAND WILL GRADUALLY START TO WARM AGAIN AS THE LOW PULLS OFF THE NORTH. ALONG THE COAST THERE MAY BE SOME CLEARING EACH AFTERNOON...BUT THIS WILL LIKELY BE BRIEF. MKK && .LONG TERM(MONDAY THROUGH THURSDAY)... NOT MUCH TO SAY REGARDING THE FORECAST NEXT WEEK. IT SHOULD BE A PRETTY QUIET PERIOD OVERALL, AND WHILE WE LEFT SOME `GHOST POPS` OVER THE MTS OF ERN MENDO/TRINITY MON PM, THE ATMOSPHERE LOOKS INCREASINGLY DRY AND STABLE HEADING THROUGH THE WEEK. TEMPERATURES WILL WARM TO NEAR SEASONABLE LEVELS WITH HIGHS IN THE LOW 90S ACROSS THE WARMER INTERIOR VALLEYS. AT THE COAST, SOME INCREASE IN NORTHERLY WINDS AND THE LACK OF A STRONG RIDGE OF HIGH PRESSURE LENDS HOPE FOR SOME PARTIALLY SUNNY AFTERNOONS, ESPECIALLY ALONG THE MENDOCINO COAST. HOWEVER GIVEN THE TIME OF YEAR, AND STILL PLENTY OF BOUNDARY LAYER MOISTURE AROUND WITH NORTHERLY AND ONSHORE FLOW, MORNING AND OVERNIGHT LOW CLOUDS AND FOG WILL REMAIN PERSISTENT. AAD && .AVIATION...RELATIVELY LOW CONFIDENCE FORECAST TONIGHT. CURRENT VISIBLE IMAGERY SHOWS 1000-1500FT DECK OVER THE INLAND COASTAL HILLS OF HUMBOLDT COUNTY WITH SCATTERED LOWER STRATUS IN PATCHES ALONG THE MENDOCINO COAST AND DEL NORTE COUNTY NEAR KCEC. EXPECT THE CLEAR SPOTS TO FILL BACK BETWEEN 02Z AND 05Z AND GO BELOW 1000FT BY 8Z-12Z. HOWEVER WITH THE UPPER LOW MOVING THROUGH WOULD NOT BE SURPRISED TO SEE THE CEILINGS LIFT A BIT BEFORE COMING BACK DOWN CLOSER TO DAWN TOMORROW. HIGHER CONFIDENCE THAT VSBYS WILL STAY MOSTLY UNRESTRICTED, DESPITE THE GUIDANCE SHOWING OTHERWISE. CLEARING TOMORROW SHOULD BE A BIT EASIER TO COME BY WITH THE LESS STABLE ENVIRONMENT, BUT DO NOT EXPECT MUCH MORE THAN A FEW HOURS WITH LIGHT NORTHERLY WINDS IN THE BL NOT SUPPORTING MUCH MIXING. CIGS SHOULD AT LEAST BE ABOVE 1000 OR 1500 FT AFTER EARLY TO MID MORNING. AWAY FROM THE COAST...THERE WILL BE A THREAT FOR SCATTERED SHOWERS AND A STRAY THUNDERSTORM OR TWO OVER THE SISKIYOUS OR TRINITY ALPS. SMOKE NEAR FIRES IN SRN SISKIYOU COUNTY WILL CONTINUE TO LOWER VISIBILITY IN LOCALIZED AREAS. AAD && .MARINE...VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. SEAS WERE RUNNING 2 TO 4 FEET ACROSS THE COASTAL WATERS AS OF THIS WRITING, WITH VERY LIGHT WINDS WITHIN 5 TO 10 NM OF SHORE. NO ASCAT PASS YET TODAY, BUT NORTHERLY WINDS ARE PROBABLY PICKING UP A BIT MORE ACROSS THE OUTER WATERS BEYOND 10 NM, ON THE ORDER OF 10 TO 15 KNOTS, ESPECIALLY TO THE LEE OF CAPE MENDOCINO. ISOLATED SHOWER ACTIVITY WILL BE POSSIBLE LATER TONIGHT AND TOMORROW MORNING. WITH THE UPPER LOW STILL TRACKING THROUGH, BUT DO NOT EXPECT ANY LIGHTNING AS THE BETTER DYNAMICS AND FORCING SHIFT EAST AND NORTH. AS THE UPPER LOW PASSES BY AND RIDGING TRIES TO BUILD BACK IN, NORTHERLY WINDS WILL INCREASE BY SUNDAY OR MONDAY. HOWEVER, WE ARE THINKING 20-25 KTS OVER THE SRN OUTER WATERS AND NEAR CAPE MENDOCINO AT WORST, AS THE RIDGE REMAINS FLAT AT BEST, AND HIGH PRESSURE OFFSHORE REMAINS WEAK. OTHERWISE, OUTSIDE OF LOCALLY GENERATED LOW WAVES GENERATED BY THESE NORTHERLIES, A NW SWELL AROUND 10-12 SEC PERIOD WILL PEAK AT ABOUT 4 FT ON SATURDAY BEFORE GRADUALLY DECAYING. A 1-2 FT SOUTHERLY SWELL NEAR 14 SEC PERIOD MAY ALSO BE NOTICEABLE WHERE THE WINDS AND SEAS ARE OTHERWISE LIGHT AND LOW. AAD && .FIRE WEATHER...A FEW SHOWERS HAVE STARTED TO POP UP THIS AFTERNOON SO IT LOOKS REASONABLE THAT WE WILL GET SOME STRIKES...ALTHOUGH THE EXACT COVERAGE AND LOCATION MAY BE SLIGHTLY LESS THAN FORECASTED. LEFT THE RED FLAG WARNING IN PLACE FOR THIS EVENING. LATE TONIGHT A SHORTWAVE ROTATING AROUND THE LOW LOOKS TO SPARK OFF SOME THUNDERSTORMS. EXPECT THESE WILL MAINLY BE NORTH OF HWY 299 SO UPGRADED THE FIRE WEATHER WATCHES TO WARNINGS IN THE NORTH AND CANCELLED THE WATCHES IN THE SOUTH. CONFIDENCE REMAINS LOW ON THIS NOCTURNAL CONVECTION. FRIDAY AFTERNOON SOME CONVECTION MAY RETURN...HOWEVER THE LAPSE RATES ALOFT LOOK A BIT MARGINAL SO LEFT THE FIRE WEATHER WATCH IN PLACE. THE BEST CHANCE FOR THUNDERSTORMS LOOK TO BE ALONG THE SISKIYOU/TRINITY COUNTY BORDER. FOR THE WEEKEND THE THREAT LOOKS TO DIMINISH AS THE LOW PULLS AWAY SO IT IS UNLIKELY THAT ANY ADDITIONAL WATCHES OR WARNINGS WILL BE ISSUED FOR THEN. MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING CAZ076. FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING CAZ003-004-076. RED FLAG WARNING UNTIL 11 AM PDT FRIDAY CAZ003-004. NORTHWEST CALIFORNIA COASTAL WATERS...NONE. && $$ VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA FOLLOW US ON FACEBOOK AND TWITTER AT: HTTP://WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.EUREKA.GOV HTTP://WWW.TWITTER.COM/NWSEUREKA
AREA FORECAST DISCUSSION
NWS ALBANY NY
134 PM EDT THU AUG 8 2013 .SYNOPSIS... AHEAD OF A SLOW MOVING COLD FRONT...A MUGGY AIR MASS IN PLACE WILL ALLOW FOR SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON. AS THE COLD FRONT MOVES ACROSS THE REGION...ADDITIONAL SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY RAINFALL...WILL OCCUR TONIGHT INTO TOMORROW. DRIER AND LESS HUMID CONDITIONS WILL RETURN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM EDT...RADARS INDICATING STILL NO REAL CONVECTION HAS DEVELOPED OVER THE AREA. THERE WERE PLENTY OF CU AND SOME HIGH CLOUDS AND MSAS ANALYSIS INDICATED SURFACE BASED CAPES UP TO 1500 J/KG. THE LATEST HRRR AND HIRES WRF MODELS CONTINUE TO INDICATE CONVECTION WILL DEVELOP DURING THE AFTERNOON. FORCING REMAINS WEAK BUT ANY WEAK BOUNDARIES INCLUDING A DEWPOINT BOUNDARY WELL TO OUR WEST IN SW NY...AND EVEN TERRAIN ASPECT COULD ALLOW FOR SOME CONVECTION TO DEVELOP LATER IN THE AFTERNOON. THERE ARE BREAKS OF SUNSHINE...ALBEIT NOT MANY...THAT COULD HELP THE CAUSE. FOR THIS UPDATE...PUSHED BACK THE TIME OF DEVELOPMENT (LATER) AND LOWERED POPS A TAD...GENERALLY HELD TO THE 30-50 PERCENT FOR LATE AFTERNOON. THE 12Z ALY/MODEL SOUNDINGS DO INDICATE A DISTINCT MID LEVEL DRY AREA THAT COULD ALLOW FOR MOMENTUM OF MODEST WINDS ALOFT TO MIX DOWN...ALTHOUGH THEY ARE ONLY AROUND 40 KTS AROUND THE 20,000+ LEVEL. WILL LEAVE THEM IN KEPT HIGH TEMPERATURES VERY SIMILAR TO BEFORE DESPITE THE FACT THAT SOME AREAS WERE ALREADY APPROACHING HIGH TEMPERATURES. THE CLOUDS SHOULD KEEP HIGH TEMPERATURES FROM RISING MUCH MORE. LOOK FOR HIGHS WITHIN A FEW DEGREES OF 80. HOWEVER DEWPOINTS 65 TO 70 WILL ACTUALLY MAKE THESE READINGS FEEL A TAD HIGHER. SOME OF THE MORE SPECIFIC PARAMETERS AFFECTING CONVECTIVE MODE THIS AFTERNOON AND EVENING ARE DESCRIBED IN THE PREVIOUS AFD BELOW... WITH SFC CAPE VALUES EXPECTED TO REACH AROUND 1000 J/KG...AND 500 HPA WINDS OF AROUND 25-30 KTS IN PLACE...THERE MAY BE JUST ENOUGH INGREDIENTS IN PLACE FOR A FEW STRONG STORMS ACROSS OUR AREA. WHILE WIDESPREAD SVR STORMS IS NOT ANTICIPATED...IT/S POSSIBLE THAT A ROGUE STORM OR TWO COULD PRODUCE GUSTY WINDS...ESP CONSIDERING INCREASING HIGH PWAT VALUES AROUND 1.50 INCHES MAY ALLOW FOR A PRECIP LOADING INDUCED WIND GUST WITHIN ANY HEAVY SHOWER OR THUNDERSTORM. SPC HAS PLACED OUR AREA IN A 5% PROB FOR SVR WX...AND THIS LOOKS TO BE RIGHT. WE WILL MENTION THE POTENTIAL FOR GUSTY WINDS IN THE ZONES AND HWO PRODUCT. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... THE SFC FRONT WILL STALL CLOSE TO OR OVER OUR AREA TONIGHT INTO FRIDAY WHILE THE UPPER LEVEL ENERGY SLOWLY BARRELS ACROSS ONTARIO. A STRONG JET STREAK AT 250 HPA OF AROUND 125 KTS WILL UNDERCUT THE UPPER LEVEL LOW AND BE SITUATED OVER THE UPPER GREAT LAKES AND SOUTHERN CANADA. WITH THE UPSTREAM JET STREAK...HIGH MOISTURE IN PLACE...AND PROXIMITY OF THE SFC BOUNDARY...SHOWERS AND THUNDERSTORMS LOOK LIKELY TONIGHT INTO FRIDAY OVER MUCH OF THE REGION. A WEAK SURFACE WAVE MAY DEVELOP ALONG THE BOUNDARY FOR FRIDAY AS WELL...WHICH MAY HELP INCREASE COVERAGE OF SHOWERS/STORMS...AS WELL AS HELP MOVE THE BOUNDARY SOUTHEAST SOMEWHAT BY LATE IN THE DAY FRIDAY. IT WILL BE DIFFICULT TO SAY EXACTLY WHERE AND WHEN SHOWERS/TSTMS WILL TRACK THROUGH THE PERIOD. WITH THE CONVECTIVE NATURE OF THE PRECIP...THERE IS THE POTENTIAL FOR QPF AMOUNTS TO BE RATHER VARIABLE ACROSS THE REGION. HOWEVER WE CAN SAY WITH CERTAINTY THAT WITH PWATS STILL AROUND TWO INCHES...HEAVY RAINFALL WILL BE A POSSIBILITY WITH ANY SHOWER/STORM...AND WE WILL CONTINUE TO MENTION THIS IN BOTH THE GRIDS AND HWO. SEE OUR HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL TO IMPACT THE HSA. SIMILAR TO TODAY /THURS/...SPC HAS OUR REGION IN A /SEE TEXT/ FOR STORMS ON FRIDAY WITH A 5% PROB FOR SVR IN PLACE. AGAIN...LIMITED INSTABILITY AND WEAK LAPSE RATES WILL PREVENT WIDESPREAD SVR WX...BUT ANY BREAKS IN THE CLOUDS WILL INCREASE THE THREAT FOR A ROGUE STRONGER STORM. MIN TEMPS TONIGHT WILL BE WARM AND MUGGY...WITH MID 60S TO LOW 70S EXPECTED. MAX TEMPS ON FRIDAY WILL GENERALLY BE IN THE 70S TO NEAR 80. THE FRONT WILL FINALLY START TO MOVE AWAY ON FRIDAY NIGHT. SOME SHOWERS MAY LINGER ACROSS SOUTHEASTERN AREAS INTO FRIDAY EVENING...BUT THE ENTIRE REGION SHOULD BE CLEARED OUT BY SAT MORNING. MIN TEMPS ON FRI NIGHT WILL STILL BE IN THE 60S IN MOST PLACES. DRIER AND LESS HUMID CONDITIONS ARE EXPECTED SAT INTO SAT NIGHT AS SFC HIGH PRESSURE BUILDS INTO THE REGION FROM THE GREAT LAKES. MAX TEMPS ON SAT WILL BE IN THE 70S TO LOW 80S AND MIN TEMPS SAT NIGHT WITH BE IN THE 40S AND 50S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... MAINLY DRY WEATHER IS EXPECTED DURING THE LONG TERM PERIOD WITH ONLY A CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY. SUNDAY THROUGH MONDAY NIGHT...EXPECT DRY CONDITIONS AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS THE REGION AT THE SURFACE. EXPECT HIGHS ON SUNDAY AND MONDAY TO RANGE FROM THE LOWER 70S NORTHWEST TO THE LOWER 80S SOUTHEAST. LOWS SATURDAY NIGHT ARE EXPECTED TO RANGE FROM THE LOWER 40S NORTHWEST TO MID 50S SOUTHEAST WITH LOWS SUNDAY NIGHT RANGING FROM THE UPPER 40S NORTHWEST TO UPPER 50S SOUTHEAST AND LOWS MONDAY NIGHT IN THE 50S TO LOWER 60S. TUESDAY...A WEAK TROUGH OF LOW PRESSURE WILL SLIDE SOUTHEAST FROM THE EASTERN GREAT LAKES AND SOUTHEAST CANADA. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF THIS FEATURE WITH SB CAPES RISING TO BTWN 500 AND 1000 J/KG HIGHS ON TUESDAY ARE EXPECTED TO BE IN THE 70S TO AROUND 80 WITH A FEW AREAS ACROSS THE SRN ADIRONDACKS IN THE UPPER 60S. TUESDAY NIGHT AND WEDNESDAY...EXPECT A RETURN TO DRY CONDITIONS AS HIGH PRESSURE BUILDS BACK INTO THE NORTHEAST. LOWS TUESDAY NIGHT ARE EXPECTED TO RANGE FROM THE UPPER 40S NORTHWEST TO UPPER 50S SOUTHEAST WITH HIGHS ON WEDNESDAY RANGING FROM THE UPPER 60S NORTHWEST TO UPPER 70S SOUTHEAST. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... SOME ISOLATED SHOWERS AND THUNDERSTORMS ARE BEGINNING TO FORM IN THE EASTERN CATSKILLS AND COULD TRACK TOWARD KPOU LATER THIS AFTERNOON. OTHERWISE...VERY LITTLE ORGANIZED FORCING TO TRIGGER SHOWERS AND THUNDERSTORMS IN OTHER AREAS THROUGH THIS AFTERNOON...EVEN INTO EARLY THIS EVENING. THERE ARE SCATTERED VARIABLE BROKEN CLOUDS NEAR AND ABOVE 3000 FEET ACROSS THE REGION AND SOME ISOALTED TO SCATTERED SHOWERS AND THUNDERSTORMS COULD FORM IN THE WESTERN MOHAWK VALLEY OR SOUTHERN ADIRONDACKS THAT COULD TRACK TOWARD KALB...KGFL AND KPSF THIS EVENING. MORE ORGANIZED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO TRACK INTO THE REGION FROM THE GREAT LAKES OVERNIGHT INTO TOMORROW MORNING WITH SOLID MVFR CEILINGS AND VISIBILITIES TONIGHT INTO TOMORROW... POSSIBLY DROPPING INTO IFR. UNTIL CONFIDENCE IN IFR IS HIGHER... KEEPING LOW MVFR TONIGHT AND TOMORROW MORNING WITH SHOWERS. SOUTH TO SOUTHWEST WINDS AT 10 MPH OR LESS THIS AFTERNOON SHOULD BECOMING LIGHT SOUTH TONIGHT AND THEN INCREASE AGAIN TO 6-10 KT TOMORROW MORNING. OUTLOOK... THURSDAY NIGHT AND FRIDAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA. SATURDAY THROUGH MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... NO FIRE WX ISSUES ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS. SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE REGION TODAY THROUGH TOMORROW NIGHT. DRY WEATHER WILL RETURN OVER THE WEEKEND. RH VALUES WILL ONLY DROP TO 65 PERCENT THIS AFTERNOON WITH SOUTHERLY WINDS OF 5 TO 10 MPH. RH VALUES WILL RETURN TO NEAR 100 PERCENT TONIGHT WITH SOUTH WINDS AT 5 MPH. RH VALUES GENERALLY GREATER THAN 70 PERCENT WILL BE IN PLACE FOR TOMORROW WITH RAIN SHOWERS LIKELY. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE REGION TODAY THROUGH TOMORROW NIGHT AS A COLD FRONT MOVES ACROSS THE REGION. THE MOST LIKELY PERIOD FOR SEEING RAINFALL WILL BE TONIGHT INTO FRIDAY. AREAS SOUTH AND EAST OF THE CAPITAL REGION LOOK TO SEE THE HEAVIEST RAINFALL...AS THE FRONTAL BOUNDARY WILL STALL CLOSE TO THIS AREA...AND A WAVE OF LOW PRESSURE WILL MOVE ALONG THE BOUNDARY. WITH PWATS NEAR TWO INCHES AND DEWPOINTS IN THE MID 60S TO NEAR 70...HEAVY RAINFALL WILL BE POSSIBLE WITHIN ANY OF THE SHOWERS AND THUNDERSTORMS. FFG VALUES LOOK TO BE AT TYPICAL VALUES FOR EARLY AUGUST...AND IT WILL REQUIRE ABOUT TWO TO THREE INCHES OF RAINFALL IN A ONE HOUR PERIOD TO CAUSE FLASH FLOODING. DEPENDING ON WHERE SHOWERS AND THUNDERSTORMS TRACK...MINOR FLOODING OF URBAN...POOR DRAINAGE...AND LOW LYING AREAS WILL BE POSSIBLE THROUGH FRIDAY...MAINLY FOR AREAS SOUTH AND EAST OF THE CAPITAL REGION. DRIER WEATHER WILL RETURN TO THE REGION OVER THE WEEKEND. WHILE THERE MAY BE SOME IN BANKS RISES ON MAIN STEM RIVERS AND STREAMS LATE THIS WEEK...DRY WEATHER OVER THE WEEKEND WILL ALLOW THESE FLOWS TO RECEDE. 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...FRUGIS/NAS NEAR TERM...HWJIV/NAS SHORT TERM...FRUGIS LONG TERM...11 AVIATION...NAS FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
100 PM EDT THU AUG 8 2013 .SYNOPSIS... AHEAD OF A SLOW MOVING COLD FRONT...A MUGGY AIR MASS IN PLACE WILL ALLOW FOR SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON. AS THE COLD FRONT MOVES ACROSS THE REGION...ADDITIONAL SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY RAINFALL...WILL OCCUR TONIGHT INTO TOMORROW. DRIER AND LESS HUMID CONDITIONS WILL RETURN FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM EDT...RADARS INDICATING STILL NO REAL CONVECTION HAS DEVELOPED OVER THE AREA. THERE WERE PLENTY OF CU AND SOME HIGH CLOUDS AND MSAS ANALYSIS INDICATED SURFACE BASED CAPES UP TO 1500 J/KG. THE LATEST HRRR AND HIRES WRF MODELS CONTINUE TO INDICATE CONVECTION WILL DEVELOP DURING THE AFTERNOON. FORCING REMAINS WEAK BUT ANY WEAK BOUNDARIES INCLUDING A DEWPOINT BOUNDARY WELL TO OUR WEST IN SW NY...AND EVEN TERRAIN ASPECT COULD ALLOW FOR SOME CONVECTION TO DEVELOP LATER IN THE AFTERNOON. THERE ARE BREAKS OF SUNSHINE...ALBEIT NOT MANY...THAT COULD HELP THE CAUSE. FOR THIS UPDATE...PUSHED BACK THE TIME OF DEVELOPMENT (LATER) AND LOWERED POPS A TAD...GENERALLY HELD TO THE 30-50 PERCENT FOR LATE AFTERNOON. THE 12Z ALY/MODEL SOUNDINGS DO INDICATE A DISTINCT MID LEVEL DRY AREA THAT COULD ALLOW FOR MOMENTUM OF MODEST WINDS ALOFT TO MIX DOWN...ALTHOUGH THEY ARE ONLY AROUND 40 KTS AROUND THE 20,000+ LEVEL. WILL LEAVE THEM IN KEPT HIGH TEMPERATURES VERY SIMILAR TO BEFORE DESPITE THE FACT THAT SOME AREAS WERE ALREADY APPROACHING HIGH TEMPERATURES. THE CLOUDS SHOULD KEEP HIGH TEMPERATURES FROM RISING MUCH MORE. LOOK FOR HIGHS WITHIN A FEW DEGREES OF 80. HOWEVER DEWPOINTS 65 TO 70 WILL ACTUALLY MAKE THESE READINGS FEEL A TAD HIGHER. SOME OF THE MORE SPECIFIC PARAMETERS AFFECTING CONVECTIVE MODE THIS AFTERNOON AND EVENING ARE DESCRIBED IN THE PREVIOUS AFD BELOW... WITH SFC CAPE VALUES EXPECTED TO REACH AROUND 1000 J/KG...AND 500 HPA WINDS OF AROUND 25-30 KTS IN PLACE...THERE MAY BE JUST ENOUGH INGREDIENTS IN PLACE FOR A FEW STRONG STORMS ACROSS OUR AREA. WHILE WIDESPREAD SVR STORMS IS NOT ANTICIPATED...IT/S POSSIBLE THAT A ROGUE STORM OR TWO COULD PRODUCE GUSTY WINDS...ESP CONSIDERING INCREASING HIGH PWAT VALUES AROUND 1.50 INCHES MAY ALLOW FOR A PRECIP LOADING INDUCED WIND GUST WITHIN ANY HEAVY SHOWER OR THUNDERSTORM. SPC HAS PLACED OUR AREA IN A 5% PROB FOR SVR WX...AND THIS LOOKS TO BE RIGHT. WE WILL MENTION THE POTENTIAL FOR GUSTY WINDS IN THE ZONES AND HWO PRODUCT. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... THE SFC FRONT WILL STALL CLOSE TO OR OVER OUR AREA TONIGHT INTO FRIDAY WHILE THE UPPER LEVEL ENERGY SLOWLY BARRELS ACROSS ONTARIO. A STRONG JET STREAK AT 250 HPA OF AROUND 125 KTS WILL UNDERCUT THE UPPER LEVEL LOW AND BE SITUATED OVER THE UPPER GREAT LAKES AND SOUTHERN CANADA. WITH THE UPSTREAM JET STREAK...HIGH MOISTURE IN PLACE...AND PROXIMITY OF THE SFC BOUNDARY...SHOWERS AND THUNDERSTORMS LOOK LIKELY TONIGHT INTO FRIDAY OVER MUCH OF THE REGION. A WEAK SURFACE WAVE MAY DEVELOP ALONG THE BOUNDARY FOR FRIDAY AS WELL...WHICH MAY HELP INCREASE COVERAGE OF SHOWERS/STORMS...AS WELL AS HELP MOVE THE BOUNDARY SOUTHEAST SOMEWHAT BY LATE IN THE DAY FRIDAY. IT WILL BE DIFFICULT TO SAY EXACTLY WHERE AND WHEN SHOWERS/TSTMS WILL TRACK THROUGH THE PERIOD. WITH THE CONVECTIVE NATURE OF THE PRECIP...THERE IS THE POTENTIAL FOR QPF AMOUNTS TO BE RATHER VARIABLE ACROSS THE REGION. HOWEVER WE CAN SAY WITH CERTAINTY THAT WITH PWATS STILL AROUND TWO INCHES...HEAVY RAINFALL WILL BE A POSSIBILITY WITH ANY SHOWER/STORM...AND WE WILL CONTINUE TO MENTION THIS IN BOTH THE GRIDS AND HWO. SEE OUR HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL TO IMPACT THE HSA. SIMILAR TO TODAY /THURS/...SPC HAS OUR REGION IN A /SEE TEXT/ FOR STORMS ON FRIDAY WITH A 5% PROB FOR SVR IN PLACE. AGAIN...LIMITED INSTABILITY AND WEAK LAPSE RATES WILL PREVENT WIDESPREAD SVR WX...BUT ANY BREAKS IN THE CLOUDS WILL INCREASE THE THREAT FOR A ROGUE STRONGER STORM. MIN TEMPS TONIGHT WILL BE WARM AND MUGGY...WITH MID 60S TO LOW 70S EXPECTED. MAX TEMPS ON FRIDAY WILL GENERALLY BE IN THE 70S TO NEAR 80. THE FRONT WILL FINALLY START TO MOVE AWAY ON FRIDAY NIGHT. SOME SHOWERS MAY LINGER ACROSS SOUTHEASTERN AREAS INTO FRIDAY EVENING...BUT THE ENTIRE REGION SHOULD BE CLEARED OUT BY SAT MORNING. MIN TEMPS ON FRI NIGHT WILL STILL BE IN THE 60S IN MOST PLACES. DRIER AND LESS HUMID CONDITIONS ARE EXPECTED SAT INTO SAT NIGHT AS SFC HIGH PRESSURE BUILDS INTO THE REGION FROM THE GREAT LAKES. MAX TEMPS ON SAT WILL BE IN THE 70S TO LOW 80S AND MIN TEMPS SAT NIGHT WITH BE IN THE 40S AND 50S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... MAINLY DRY WEATHER IS EXPECTED DURING THE LONG TERM PERIOD WITH ONLY A CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY. SUNDAY THROUGH MONDAY NIGHT...EXPECT DRY CONDITIONS AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS THE REGION AT THE SURFACE. EXPECT HIGHS ON SUNDAY AND MONDAY TO RANGE FROM THE LOWER 70S NORTHWEST TO THE LOWER 80S SOUTHEAST. LOWS SATURDAY NIGHT ARE EXPECTED TO RANGE FROM THE LOWER 40S NORTHWEST TO MID 50S SOUTHEAST WITH LOWS SUNDAY NIGHT RANGING FROM THE UPPER 40S NORTHWEST TO UPPER 50S SOUTHEAST AND LOWS MONDAY NIGHT IN THE 50S TO LOWER 60S. TUESDAY...A WEAK TROUGH OF LOW PRESSURE WILL SLIDE SOUTHEAST FROM THE EASTERN GREAT LAKES AND SOUTHEAST CANADA. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF THIS FEATURE WITH SB CAPES RISING TO BTWN 500 AND 1000 J/KG HIGHS ON TUESDAY ARE EXPECTED TO BE IN THE 70S TO AROUND 80 WITH A FEW AREAS ACROSS THE SRN ADIRONDACKS IN THE UPPER 60S. TUESDAY NIGHT AND WEDNESDAY...EXPECT A RETURN TO DRY CONDITIONS AS HIGH PRESSURE BUILDS BACK INTO THE NORTHEAST. LOWS TUESDAY NIGHT ARE EXPECTED TO RANGE FROM THE UPPER 40S NORTHWEST TO UPPER 50S SOUTHEAST WITH HIGHS ON WEDNESDAY RANGING FROM THE UPPER 60S NORTHWEST TO UPPER 70S SOUTHEAST. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... EARLY THIS MORNING EXPECT MAINLY VFR VSBYS AND VFR/MVFR CIGS WHICH WILL GIVE WAY TO ENTIRELY VFR CONDITIONS AFT 14Z. HAVE PLACED VCSH IN THE TAFS AFT 14Z AS CONVECTION TO THE WEST MOVES EAST INTO THE HUDSON VALLEY. THE BIG QUESTION WILL BE HOW MUCH OF THIS PCPN HOLDS TOGETHER AS IT MOVES INTO A SLIGHTLY MORE STABLE AIRMASS. THIS AFTERNOON THROUGH THIS EVENING LOOKS TO HAVE A BETTER CHANCE OF CONVECTION AND MORE WIDESPREAD SHOWER ACTIVITY IS EXPECTED LATE TONIGHT AFT 09Z WITH MAINLY MVFR CONDITIONS. WINDS SHOULD BE SOUTH TO SOUTHWEST AT 6-10 KTS WITH GUSTS TO 16 KTS AT KALB. WINDS WILL DIMINISH TONIGHT TO LESS THAN 6 KTS EXCEPT AT KALB WHERE SOUTH WINDS WILL REMAIN AT 8-10 KTS. OUTLOOK... THURSDAY NIGHT AND FRIDAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA. SATURDAY THROUGH MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... NO FIRE WX ISSUES ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS. SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE REGION TODAY THROUGH TOMORROW NIGHT. DRY WEATHER WILL RETURN OVER THE WEEKEND. RH VALUES WILL ONLY DROP TO 65 PERCENT THIS AFTERNOON WITH SOUTHERLY WINDS OF 5 TO 10 MPH. RH VALUES WILL RETURN TO NEAR 100 PERCENT TONIGHT WITH SOUTH WINDS AT 5 MPH. RH VALUES GENERALLY GREATER THAN 70 PERCENT WILL BE IN PLACE FOR TOMORROW WITH RAIN SHOWERS LIKELY. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE REGION TODAY THROUGH TOMORROW NIGHT AS A COLD FRONT MOVES ACROSS THE REGION. THE MOST LIKELY PERIOD FOR SEEING RAINFALL WILL BE TONIGHT INTO FRIDAY. AREAS SOUTH AND EAST OF THE CAPITAL REGION LOOK TO SEE THE HEAVIEST RAINFALL...AS THE FRONTAL BOUNDARY WILL STALL CLOSE TO THIS AREA...AND A WAVE OF LOW PRESSURE WILL MOVE ALONG THE BOUNDARY. WITH PWATS NEAR TWO INCHES AND DEWPOINTS IN THE MID 60S TO NEAR 70...HEAVY RAINFALL WILL BE POSSIBLE WITHIN ANY OF THE SHOWERS AND THUNDERSTORMS. FFG VALUES LOOK TO BE AT TYPICAL VALUES FOR EARLY AUGUST...AND IT WILL REQUIRE ABOUT TWO TO THREE INCHES OF RAINFALL IN A ONE HOUR PERIOD TO CAUSE FLASH FLOODING. DEPENDING ON WHERE SHOWERS AND THUNDERSTORMS TRACK...MINOR FLOODING OF URBAN...POOR DRAINAGE...AND LOW LYING AREAS WILL BE POSSIBLE THROUGH FRIDAY...MAINLY FOR AREAS SOUTH AND EAST OF THE CAPITAL REGION. DRIER WEATHER WILL RETURN TO THE REGION OVER THE WEEKEND. WHILE THERE MAY BE SOME IN BANKS RISES ON MAIN STEM RIVERS AND STREAMS LATE THIS WEEK...DRY WEATHER OVER THE WEEKEND WILL ALLOW THESE FLOWS TO RECEDE. 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...FRUGIS/NAS NEAR TERM...HWJIV/NAS/FRUGIS SHORT TERM...FRUGIS LONG TERM...11 AVIATION...11 FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
117 PM EDT THU AUG 8 2013 .SYNOPSIS... LOW PRESSURE MOVING ACROSS SOUTHEASTERN CANADA WILL ALLOW A COLD FRONT TO APPROACH THE REGION ON FRIDAY AND CROSS THE AREA BY LATE FRIDAY OR EARLY SATURDAY. THIS FRONT WILL EVENTUALLY STALL TO OUR SOUTH FOR SUNDAY. EARLY NEXT WEEK, A FEW WAVES OF LOW PRESSURE ARE FORECAST TO MOVE ALONG THE STALLED BOUNDARY. HIGH PRESSURE WILL THEN BUILD IN TOWARD MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT A CONFIDENT ESTF UPDATE. WE HAVE DECIDED TO COMPROMISE BETWEEN PREVIOUS FCST AND CURRENT SUGGESTIONS BY THE HRRR AND COSPA. WE ARE SEEING A SHORT WAVE EMERGE FROM WV AND COUPLED WITH CONVECTIVE TEMPERATURES BEING REACHED BELIEVE THIS SHOULD START TRIGGERING AND ENHANCING CONVECTION AS WE MOVE FORWARD. THE PREVIOUS MCS HAS LEFT A RELATIVELY STABLE POOL NW OF OUR CWA FOR NOW. SO THE ADJUSTMENTS GOING FORWARD WERE TO LOWER POPS INITIALLY NORTHWEST AND GIVE THAT SHORT WAVE A BIT MORE CREDIT AND INCREASE POPS IN THE CENTRAL THIRD OF OUR CWA FOR THIS AFTERNOON. WE DID SEE A NOTICEABLE DROP OFF IN 925MB OR 850MB MOISTURE OFF THE WALLOPS SOUNDING THIS MORNING, SO CHANCES WERE KEPT IN THE SERN PART OF OUR CWA. WE ARE WARMING AT 700MB AND 500MB, SO WITH BULK SHEAR VALUES BEST NORTH AS WELL AS FORECAST TT(S), WE KEPT THE SOMEWHAT ENHANCED WORDING TIED TO LIKELY POPS. THE FCST DCAPES ARE NOT IMPRESSIVE AND NEITHER ARE THETA E DROP WITH HEIGHT, SO ANY STRONG TO SEVERE ARE GOING TO HAVE TO BE TIED TO SOME RELATIVELY STRONGER UPDRAFTS OR IF AN EFFECTIVE COOL POOL CAN FORM. THE LATTER DOES NOT LOOK PROMISING. WE HAVE NOT HAD MANY DRY STRETCHES THIS SUMMER, BUT THE RELATIVE LACK OF FLOODING RAINS LAST SEVERAL DAYS HAS PERMITTED FFG AND FFH GUIDANCE TO GET CLOSER TO NORMAL SUMMER VALUES. SO WHILE A FFW MIGHT STILL OCCUR, THIS WOULD SEEM TO BE MORE OF AN ISOLATED OCCURRENCE. 12Z SOUNDINGS GIVE 90F AS A POSSIBLE HIGH SOUTHERN PART OF OUR CWA (CONVECTIVE TEMP LOW 80S), SO BUMPED MAX TEMPS UPWARD IN DELMARVA, KEPT THE REST RELATIVELY THE SAME. UPPER HEIGHTS WILL BE RISING THRU THE DAY AND THERE ARE ONLY WEAK S/W MOVING THRU THE FLOW. BREAKS WILL OCCUR TODAY ALLOWING FOR POCKETS OF HEATING/INSTABILITY TO DEVELOP. WE WILL GO ALONG WITH THE DETERMINISTIC MODELS AND MOS AND MOSTLY KEEP THE HIGHER CHC FOR POPS NORTH MOSTLY THIS AFTERNOON WITH SLGT CHC OR LOW CHC POPS SOUTH/EAST. THERE WILL BE SOME CAPE VALUES AROUND 750-1250 J/KG ACROSS THE AREA...BUT THE HIGHEST VALUES WILL OCCUR WITH ANY BREAKS IN THE CLOUDS TODAY. SPC HAS OUR AREA IN `SEE TEXT` AND MENTIONS ONLY SMALL POSSIBILITY OF SOME STRONGER WIND GUSTS WITH ANY CONVECTION THAT DEVELOPS. QPF BASIN AVERAGES...1/2 INCH NORTH RANGING DOWN TO LIGHT AMTS SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... WE WILL CONTINUE IN THE WARM SECTOR TONIGHT WITH THE UPPER FLOW BECOMING A BIT MORE SWRLY ALOFT. A COLD FRONT WILL BE SLOWING ITS APPROACH INTO WRN NY AND WRN PA. SHOWERS AND SCT THUNDERSTORMS WILL CONTINUE FROM THE LATE AFTERNOON INTO THE EARLY OVERNIGHT PERIODS. THE AREAS NORTH/WEST WILL HAVE THE BETTER CHCS FOR THE RAINS. WE WILL CARRY THE LIKELY POPS INTO THE OVERNIGHT NORTH/WEST AND HOLD THE HIGHER CHC POPS SOUTH/EAST. QPF...1/2 INCH NORTH 1/10 INCH SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AN AREA OF LOW PRESSURE IN SERN CANAD WILL WORK ITS WAY EWD. AS IT DOES A CDFNT WILL CROSS THE AREA FROM W TO E ON FRI INTO FRI NIGHT. THE LATEST MDL GUID CURRENTLY INDICATES THAT THE FRI DAYTIME PD COULD BE FAIRLY WET, FOR AT LEAST A PORTION OF THE AREA, AND THERE COULD BE LOCALIZED CONVECTION WHICH COULD MAKE FOR PDS OF HEAVY RAIN. IT IS PSBL, IF THE MDLS CONTINUE TO AGREE ON A LOCATION AS THEY ARE NOW (N AND W) THAT A FFA MAY BE NEEDED AS RNFL AMTS APPEAR TO BE AOA 1 INCH. THE FRONT SHUD CLEAR THE AREA DURG THE OVERNIGHT HOURS ON FRI AND CLEARING WILL OCCUR FROM N TO S. PRECIP MAY LINGER ACRS THE DELMARVA INTO ERLY SAT. THE ECMWF DOES CLEAR THINGS OUT FASTER THAN THE GFS. BOTH MDLS KEEP THE FRONT CLOSE BY, SO IT WON`T TAKE MUCH IN THE WAY OF A PERTURBATION FOR IT TO BRING ANOTHER SHOT OF PRECIP, BUT FOR BOTH MDLS DRY THINGS OUT BY LATER SAT AT THE LATEST, AS HIGH PRESSURE BUILDS IN. SUN THEN LOOKS DRY. MUCH LESS CONFIDENCE INTO MON AS THE GFS WANTS TO BRING A WAVE ACRS THE STALLED FRONT, WHICH WOULD BRING PRECIP, MAINLY ACRS THE S. THE ECMWF IS DRY DURG THIS TIME. THE CMC ALSO HAS A WAVE ON MON, BUT ITS OVERALL SYNOPTIC PATN IS A BUT SUSPECT OVERALL. BY TUE, THE MDLS BRING ANOTHER LOW TO THE N AND ANOTHER CDFNT ACRS THE REGION, AND ANOTHER CHC OF RAIN. THIS IS A LOW CONFIDENCE FCST FOR THE EARLY PORTION OF NEXT WEEK AS IT WILL BE DEPENDENT ON THE POSN OF THE FRONT AND IF ANY WAVES DEVELOP ALG IT AND WHERE THEY MOVE. BASED ON THE ECMWF`S GENLY SUPERIOR PERFORMANCE, WANT TO GIVE IT A BIT OF A NOD, BUT CAN`T RULE OUT A MORE PESSIMIST SOLN EITHER. FOR NOW, WILL BRING IN LOW POPS MON, LOW CHC POPS ON TUE TO SEE HOW THINGS PLAY OUT AND THEN A DRY FCST ON WED AS HIGH PRESSURE BUILDS IN. TEMPS WILL GENLY BE AT OR SLIGHTLY ABV NRML THRU THE PD. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE 18Z TAF PACKAGE IS NOT THAT OPTIMISTIC WITH A COUPLE OF ROUNDS OF SHOWERS AND THUNDERSTORMS EXPECTED WITH CONDITIONS GOING BACK TO PREDOMINATELY MVFR TONIGHT. FOR THIS AFTERNOON, CIGS SHOULD BECOME OR BE VFR FROM TAF ONSET TIME FROM THE KPHL AIRPORTS SOUTH AND EAST. NOT AS CONFIDENT ABOUT NW TERMINALS. WE ARE EXPECTING AN UPPER AIR DISTURBANCE TO INITIATE SHOWERS AND THUNDERSTORMS AND MOVE ACROSS (OR HAVE THE POTENTIAL TO) ALL THE TERMINALS LATER THIS AFTERNOON. MVFR CONDITIONS ARE LIKELY DURING THE CONVECTION. TIMING IS FROM THE SOUTHWEST TERMINALS TO THE NORTHEAST TERMINALS. SOUTH TO SOUTHWEST WINDS WILL AVERAGE AROUND 10 KTS, FOR TONIGHT AS A WHOLE, IT LOOKS AS THOUGH THERE WILL ONE, POSSIBLY A SECOND WAVE OF CONVECTION. THE INITIAL WAVE TIMING IS AN ESTIMATE AT THIS POINT AND THERE MIGHT BE A SECOND WAVE TOWARD MORNING. REGARDLESS OF THE WAVES, WE ARE EXPECTING CIGS AND VSBYS TO LOWER TO MVFR AGAIN WITH POSSIBLY SOME IFR CONDITIONS ESPECIALLY NWRN AIRPORTS AND TERMINALS. LIGHTER SOUTH WINDS EXPECTED. ON FRIDAY, EVEN MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED. THERE SHOULD BE A QUICKER STARTING TIME ALSO. WHILE NO THUNDER HAS BEEN PUT INTO THE TAFS, IT IS LIKELY THEY WILL HAVE AN IMPACT ON THE TERMINALS WHETHER OR NOT THEY DIRECTLY PASS OVER THEM. SOUTHWEST WINDS WILL AVERAGE AROUND 10 KNOTS. OUTLOOK... FRIDAY NIGHT THROUGH EARLY MORNING SATURDAY...MAINLY MVFR OR IFR CONDITIONS EXPECTED IN SHOWERS AND PSBL TSTMS. SOME HVY RAIN PSBL. MDT CONFIDENCE. REMAINDER OF SATURDAY THROUGH MONDAY...MOSTLY VFR CONDITIONS. ISOLATED SHWRS/TSTMS REMAIN POSSIBLE, ESPECIALLY MON. SUN SHOULD BE DRY. MDT TO HIGH CONFIDENCE. && .MARINE... A MODERATE SOUTH WIND CONTINUES ACROSS THE OCEAN WATERS AND MORE OF A SWLY WIND ACROSS DEL BAY. OVERALL...THE WIND SPEEDS AND SEAS WILL REMAIN BELOW SCA CRITERIA TODAY AND TONIGHT. A FEW WIND GUSTS TO 25 KTS MAY OCCUR EARLY THIS MORNING AND LATER TONIGHT...BUT THEY WILL NOT PERSIST. THE MAIN MARINE HAZARD TODAY AND TONIGHT WOULD BE ANY GUSTY WINDS ASSD WITH TSTMS WHICH WILL BE AROUND EARLY THIS MORNING...THIS AFTERNOON AND TONIGHT. SEAS...ON THE OCEAN 3-4 FT AND DEL BAY 1-2 FT (NORTH) AND 2-3FT (SOUTH). OUTLOOK... OVERALL, SUB-SCA CONDITIONS ARE EXPECTED FOR OUR AREA WATERS THROUGH THE BULK OF THE OUTLOOK PERIOD. GUIDANCE IS SHOWING AN INCREASE IN THE SOUTHERLY TO SOUTHWESTERLY FLOW DURING FRIDAY AHEAD OF AN APPROACHING CDFNT. THE WIND CUD GUST TO AROUND 20 KTS OR SO AS WELL DURG THIS TIME. IN ADDITION, WAVEWATCH GUIDANCE ALSO INDICATES SEAS RISING TO AROUND 5 OR PSBLY 6 FEET FOR OUR COASTAL WATERS DURING THIS TIMEFRAME. HOWEVER, THIS GUIDANCE TENDS TO RUN A LITTLE HIGH IN SOUTHERLY FLOW, AND CONFIDENCE IS BELOW AVERAGE. SO WILL CONTINUE TO MONITOR FOR ANY PSBL FLAGS. SEAS SHOULD THEN LOWER BEHIND THE CFP INTO THE WEEKEND, AS WINDS SHIFT TO THE NW. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...NIERENBERG NEAR TERM...GIGI/O`HARA SHORT TERM...O`HARA LONG TERM...NIERENBERG AVIATION...GIGI/NIERENBERG MARINE...NIERENBERG/O`HARA
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
438 PM EDT THU AUG 8 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 332 PM EDT THU AUG 8 2013 WEAK DIFFUSE FRONTAL BOUNDARY WILL SAG SOUTH THROUGH THE REGION INTO FRIDAY AS SEVERAL SURFACE WAVES RIPPLE ALONG THE BOUNDARY. THIS WILL KEEP SCATTERED SHOWERS AND THUNDERSTORMS ACROSS CENTRAL INDIANA INTO FRIDAY...AND OVER SOUTHERN PORTIONS OF THE AREA INTO EARLY SATURDAY AS THE FRONT MAKES ONLY SLOW PROGRESS SOUTH INTO THE TENNESSEE VALLEY. HIGH PRESSURE DRIFTING THROUGH THE GREAT LAKES WILL BRING DRIER AND SLIGHTLY COOLER WEATHER SATURDAY AND SUNDAY. A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK WITH RAIN...FOLLOWED BY REINFORCING SHOT OF COOLER AIR BY MIDWEEK AS THE UPPER TROUGH DEEPENS OVER THE EASTERN U S. && .NEAR TERM /TONIGHT/... ISSUED AT 332 PM EDT THU AUG 8 2013 MESOLOW RESIDES ACROSS NORTHERN COUNTIES WITH THE FRONTAL BOUNDARY EXTENDING SOUTHWEST INTO EAST CENTRAL ILLINOIS. LINEAR CONVECTION HAS DEVELOPED ALONG A DIFFUSE FRONT TO THE WEST OF THE INDY METRO...WITH ADDITIONAL CONVECTION NOW BEGINNING TO DEVELOP IN VICINITY OF THE BOUNDARY OVER SOUTH CENTRAL ILLINOIS. MUGGY AFTERNOON IN PROGRESS AS TEMPS HAVE RISEN INTO THE MID 80S OVER ALL BUT FAR NORTHERN COUNTIES. COMPLEX AND LOW CONFIDENCE FORECAST FOR THE REST OF THE AFTERNOON AND TONIGHT AS THE PRESENCE OF THE BOUNDARY SLOWLY SAGGING SOUTH THROUGH THE FORECAST AREA AND THE APPROACHING REMNANT MCV NEAR KSTL ARE LIKELY TO BE FACTORS IN CONVECTIVE COVERAGE INTO THE OVERNIGHT. HRRR HANDLING CURRENT CONVECTIVE COVERAGE REASONABLY WELL AND WAS USED AS A START FOR THE NEXT SEVERAL HOURS. CURRENT MESOANALYSIS INDICATES AIRMASS HAS SUFFICIENTLY DESTABILIZED ALONG AND IMMEDIATELY AHEAD OF THE BOUNDARY. MUCH OF THE CONVECTION HAS WEAKENED WITHIN THE VICINITY OF THE WELL DEFINED MCV OVER EASTERN MISSOURI. HOWEVER AS THIS FEATURE CONTINUES TO APPROACH CENTRAL INDIANA OVER THE NEXT SEVERAL HOURS AND INTERACTS WITH THE UNSTABLE AND VERY MOIST AIRMASS OVER THE REGION...EXPECT AN INCREASE IN CONVECTIVE COVERAGE INTO THE EVENING...LIKELY CONTINUING OVERNIGHT AS THE MCV MOVES THROUGH THE REGION. BOTH THE RAP AND 12Z GFS HINT AT THE LOW LEVEL JET REESTABLISHING ALONG THE OHIO RIVER TONIGHT...WITH A LOW LEVEL BAROCLINIC ZONE SETTING UP ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA. THINK ULTIMATELY SHOULD THIS COME TO PASS...THE HEAVIEST RAINFALL WILL SET UP OVER SOUTHERN COUNTIES OVERNIGHT AND WILL CARRY HIGHEST POPS IN THESE AREAS. IMPRESSIVE PRECIP WATER VALUES IN EXCESS OF 2 INCHES COMBINED WITH STORM MOTIONS UNDER 10KTS AND STEERING CURRENTS PARALLEL TO THE BOUNDARY ARE SUPPORTIVE OF TORRENTIAL RAINFALL...BACKBUILDING AND TRAINING ECHOES AND POTENTIAL FOR LOCALIZED FLOODING. WITH 1 HR/3 HR FLASH FLOOD GUIDANCE VALUES IN EXCESS OF 2 INCHES/2.5-3.5 INCHES AND UNCERTAINTY IN HOW EXTENSIVE THE PRECIP COVERAGE BECOMES...HAVE NO PLANS TO ISSUE A FLASH FLOOD WATCH AT THIS TIME. TEMPS...WARMER MAVMOS LOOKS REASONABLE CONSIDERING HIGH LOW LEVEL MOISTURE PRESENT OVER THE REGION. NAM APPEARS TO BE ADVECTING DRIER AIR INTO THE REGION TOO AGGRESSIVELY EARLY FRIDAY AND THIS IS LIKELY IMPACTING MET GUIDANCE LOWS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... ISSUED AT 332 PM EDT THU AUG 8 2013 FORECAST CHALLENGES REMAIN ON PRECIP CHANCES INTO EARLY SATURDAY AS THE FRONTAL BOUNDARY MAKES ONLY SLOW PROGRESS SOUTH. REMNANT MCV AND A WEAK SURFACE WAVE WILL BE SHIFTING EAST OF THE REGION BY 12Z FRIDAY. FOCUS FOR ADDITIONAL CONVECTIVE DEVELOPMENT WILL BE SOUTH OF I-70 AS THE BOUNDARY SETTLES OVER SOUTHERN INDIANA BY FRIDAY AFTERNOON. WILL ONCE AGAIN FOCUS HIGHEST POPS OVER SOUTHERN COUNTIES WITH LOW CHANCE POPS NORTH OF I-70 AS SLIGHTLY DRIER AIR BEGINS TO EXPAND SOUTH FROM THE GREAT LAKES. THE BOUNDARY WILL CONTINUE TO SHIFT SOUTH THROUGH KENTUCKY ON FRIDAY NIGHT AS AN UPPER LOW PIVOTS SOUTH OF JAMES BAY AND INTRODUCES A BROAD UPPER LEVEL TROUGH OVER THE EASTERN U S. WILL HANG ONTO LOW CHANCE POPS OVER SOUTHERN COUNTIES FRIDAY NIGHT AND EARLY SATURDAY DUE TO THE CLOSE PROXIMITY OF THE BOUNDARY...BUT OVERALL TREND INTO SATURDAY SHOULD BE TOWARDS DRIER AND SLIGHTLY COOLER AIR EXPANDING INTO THE FORECAST AREA AS THE DEEPER MOISTURE IS PUSHED SOUTH. SURFACE HIGH PRESSURE WILL BUILD ACROSS THE LOWER GREAT LAKES SATURDAY AFTERNOON THROUGH SUNDAY WITH DRY WEATHER. LOW LEVEL MOISTURE ATTEMPTS TO IMMEDIATELY RETURN BACK NORTH INTO THE OHIO VALLEY SUNDAY AFTERNOON AS THE HIGH SHIFTS AWAY TO THE EAST. HAVE KEPT DRY CONDITIONS THROUGH 00Z MONDAY AS LITTLE FORCING ALOFT PRESENT...ALTHOUGH WILL HAVE TO MONITOR FOR ISOLATED SHOWERS OVER THE LOWER WABASH VALLEY AS INSTABILITY AXIS WILL BE CLOSE BY ACROSS THE LOWER OHIO VALLEY. TEMPS...MOS GUIDANCE IN GENERAL WORKS WELL CONSIDERING LOW LEVEL THERMALS THROUGHOUT THE PERIOD. HIGH TEMPS FRIDAY AND SATURDAY WILL BE HIGHLY DEPENDENT ON CLOUD COVER...BUT GENERALLY LOOKING AT LOW TO MID 80S BOTH DAYS...SLIGHTLY COOLER WHERE RAIN/CLOUDS IMPACT. CORE OF THE COOLER AIR ASSOCIATED WITH THE UPPER TROUGH LIKELY DELAYED TO SUNDAY AS 850MB TEMPS FALL TO AROUND 11C. LOCATIONS SUNDAY SHOULD REMAIN IN THE UPPER 70S AND LOWER 80S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... ISSUED AT 229 PM EDT THU AUG 8 2013 MODELS ARE SIMILAR ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED FOR MOST ITEMS IN THE LONG TERM. UPPER TROUGH WILL DEEPEN ACROSS THE AREA IN THE EXTENDED. THIS WILL KEEP CENTRAL INDIANA IN COOLER NORTHWEST FLOW. TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH THE PERIOD. A COLD FRONT WILL WORK ITS WAY SOUTH MONDAY INTO TUESDAY BRINGING THE COOLER AIR TO THE AREA. MODELS AND SOME ENSEMBLES ARE SHOWING CHANCES FOR RAIN LINGERING INTO TUESDAY WITH SOME TIMING DIFFERENCES BETWEEN THEM. GIVEN THE UNCERTAINTIES INVOLVED WILL GO WITH ALLBLEND/S CHANCES FOR RAIN MONDAY INTO TUESDAY...BUT AT THE MOMENT && .AVIATION /DISCUSSION FOR THE 08/2100Z TAF UPDATE/... ISSUED AT 431 PM EDT THU AUG 8 2013 UPDATE... SCATTERED SHOWERS AND THUNDERSTORMS WILL IMPACT TAF SITES INTO EARLY EVENING...CAUSING PERIODS OF MVFR/IFR CONDITIONS. PREVIOUS DISCUSSION... LOW CONFIDENCE FORECAST...BUT GENERALLY VFR CONDITIONS GIVING WAY TO MVFR CONDITIONS OVERNIGHT WITH POTENTIAL FOR IFR. SCATTERED CONVECTION AROUND THROUGH THE PERIOD...ALONG WITH VARIABLE WINDS. WEAK BOUNDARY WILL REMAIN ACROSS CENTRAL INDIANA THIS AFTERNOON... MAKING WINDS VARIABLE. SCATTERED CONVECTION WILL PERSIST AROUND THIS BOUNDARY...BUT AT THE MOMENT IT APPEARS ORGANIZED CONVECTION WILL REMAIN OUT OF THE AREA. ANY CEILINGS BELOW MVFR SHOULD LIFT TO VFR BY VALID TIME EXCEPT FOR KLAF WHERE THEY WILL LINGER. DURING THE NIGHT...THREAT FOR CONVECTION WILL CONTINUE BUT AT THE MOMENT DO NOT EXPECT WIDESPREAD CONVECTION /ALTHOUGH SOME MODELS INDICATE THIS POSSIBILITY...BUT ODDS ARE LOW WITHOUT ANY SIGNIFICANT FORCING NEARBY/. MOIST AIRMASS WILL LEAD TO MVFR VISIBILITIES/CEILINGS WITH POTENTIAL FOR IFR. THESE SHOULD IMPROVE ON FRIDAY WITH DRIER AIR WORKING IN AS BOUNDARY SHIFTS FARTHER SOUTH. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....50 AVIATION...50/TDUD VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
332 PM EDT THU AUG 8 2013 .UPDATE... THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 332 PM EDT THU AUG 8 2013 WEAK DIFFUSE FRONTAL BOUNDARY WILL SAG SOUTH THROUGH THE REGION INTO FRIDAY AS SEVERAL SURFACE WAVES RIPPLE ALONG THE BOUNDARY. THIS WILL KEEP SCATTERED SHOWERS AND THUNDERSTORMS ACROSS CENTRAL INDIANA INTO FRIDAY...AND OVER SOUTHERN PORTIONS OF THE AREA INTO EARLY SATURDAY AS THE FRONT MAKES ONLY SLOW PROGRESS SOUTH INTO THE TENNESSEE VALLEY. HIGH PRESSURE DRIFTING THROUGH THE GREAT LAKES WILL BRING DRIER AND SLIGHTLY COOLER WEATHER SATURDAY AND SUNDAY. A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK WITH RAIN...FOLLOWED BY REINFORCING SHOT OF COOLER AIR BY MIDWEEK AS THE UPPER TROUGH DEEPENS OVER THE EASTERN U S. && .NEAR TERM /TONIGHT/... ISSUED AT 332 PM EDT THU AUG 8 2013 MESOLOW RESIDES ACROSS NORTHERN COUNTIES WITH THE FRONTAL BOUNDARY EXTENDING SOUTHWEST INTO EAST CENTRAL ILLINOIS. LINEAR CONVECTION HAS DEVELOPED ALONG A DIFFUSE FRONT TO THE WEST OF THE INDY METRO...WITH ADDITIONAL CONVECTION NOW BEGINNING TO DEVELOP IN VICINITY OF THE BOUNDARY OVER SOUTH CENTRAL ILLINOIS. MUGGY AFTERNOON IN PROGRESS AS TEMPS HAVE RISEN INTO THE MID 80S OVER ALL BUT FAR NORTHERN COUNTIES. COMPLEX AND LOW CONFIDENCE FORECAST FOR THE REST OF THE AFTERNOON AND TONIGHT AS THE PRESENCE OF THE BOUNDARY SLOWLY SAGGING SOUTH THROUGH THE FORECAST AREA AND THE APPROACHING REMNANT MCV NEAR KSTL ARE LIKELY TO BE FACTORS IN CONVECTIVE COVERAGE INTO THE OVERNIGHT. HRRR HANDLING CURRENT CONVECTIVE COVERAGE REASONABLY WELL AND WAS USED AS A START FOR THE NEXT SEVERAL HOURS. CURRENT MESOANALYSIS INDICATES AIRMASS HAS SUFFICIENTLY DESTABILIZED ALONG AND IMMEDIATELY AHEAD OF THE BOUNDARY. MUCH OF THE CONVECTION HAS WEAKENED WITHIN THE VICINITY OF THE WELL DEFINED MCV OVER EASTERN MISSOURI. HOWEVER AS THIS FEATURE CONTINUES TO APPROACH CENTRAL INDIANA OVER THE NEXT SEVERAL HOURS AND INTERACTS WITH THE UNSTABLE AND VERY MOIST AIRMASS OVER THE REGION...EXPECT AN INCREASE IN CONVECTIVE COVERAGE INTO THE EVENING...LIKELY CONTINUING OVERNIGHT AS THE MCV MOVES THROUGH THE REGION. BOTH THE RAP AND 12Z GFS HINT AT THE LOW LEVEL JET REESTABLISHING ALONG THE OHIO RIVER TONIGHT...WITH A LOW LEVEL BAROCLINIC ZONE SETTING UP ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA. THINK ULTIMATELY SHOULD THIS COME TO PASS...THE HEAVIEST RAINFALL WILL SET UP OVER SOUTHERN COUNTIES OVERNIGHT AND WILL CARRY HIGHEST POPS IN THESE AREAS. IMPRESSIVE PRECIP WATER VALUES IN EXCESS OF 2 INCHES COMBINED WITH STORM MOTIONS UNDER 10KTS AND STEERING CURRENTS PARALLEL TO THE BOUNDARY ARE SUPPORTIVE OF TORRENTIAL RAINFALL...BACKBUILDING AND TRAINING ECHOES AND POTENTIAL FOR LOCALIZED FLOODING. WITH 1 HR/3 HR FLASH FLOOD GUIDANCE VALUES IN EXCESS OF 2 INCHES/2.5-3.5 INCHES AND UNCERTAINTY IN HOW EXTENSIVE THE PRECIP COVERAGE BECOMES...HAVE NO PLANS TO ISSUE A FLASH FLOOD WATCH AT THIS TIME. TEMPS...WARMER MAVMOS LOOKS REASONABLE CONSIDERING HIGH LOW LEVEL MOISTURE PRESENT OVER THE REGION. NAM APPEARS TO BE ADVECTING DRIER AIR INTO THE REGION TOO AGGRESSIVELY EARLY FRIDAY AND THIS IS LIKELY IMPACTING MET GUIDANCE LOWS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... ISSUED AT 332 PM EDT THU AUG 8 2013 FORECAST CHALLENGES REMAIN ON PRECIP CHANCES INTO EARLY SATURDAY AS THE FRONTAL BOUNDARY MAKES ONLY SLOW PROGRESS SOUTH. REMNANT MCV AND A WEAK SURFACE WAVE WILL BE SHIFTING EAST OF THE REGION BY 12Z FRIDAY. FOCUS FOR ADDITIONAL CONVECTIVE DEVELOPMENT WILL BE SOUTH OF I-70 AS THE BOUNDARY SETTLES OVER SOUTHERN INDIANA BY FRIDAY AFTERNOON. WILL ONCE AGAIN FOCUS HIGHEST POPS OVER SOUTHERN COUNTIES WITH LOW CHANCE POPS NORTH OF I-70 AS SLIGHTLY DRIER AIR BEGINS TO EXPAND SOUTH FROM THE GREAT LAKES. THE BOUNDARY WILL CONTINUE TO SHIFT SOUTH THROUGH KENTUCKY ON FRIDAY NIGHT AS AN UPPER LOW PIVOTS SOUTH OF JAMES BAY AND INTRODUCES A BROAD UPPER LEVEL TROUGH OVER THE EASTERN U S. WILL HANG ONTO LOW CHANCE POPS OVER SOUTHERN COUNTIES FRIDAY NIGHT AND EARLY SATURDAY DUE TO THE CLOSE PROXIMITY OF THE BOUNDARY...BUT OVERALL TREND INTO SATURDAY SHOULD BE TOWARDS DRIER AND SLIGHTLY COOLER AIR EXPANDING INTO THE FORECAST AREA AS THE DEEPER MOISTURE IS PUSHED SOUTH. SURFACE HIGH PRESSURE WILL BUILD ACROSS THE LOWER GREAT LAKES SATURDAY AFTERNOON THROUGH SUNDAY WITH DRY WEATHER. LOW LEVEL MOISTURE ATTEMPTS TO IMMEDIATELY RETURN BACK NORTH INTO THE OHIO VALLEY SUNDAY AFTERNOON AS THE HIGH SHIFTS AWAY TO THE EAST. HAVE KEPT DRY CONDITIONS THROUGH 00Z MONDAY AS LITTLE FORCING ALOFT PRESENT...ALTHOUGH WILL HAVE TO MONITOR FOR ISOLATED SHOWERS OVER THE LOWER WABASH VALLEY AS INSTABILITY AXIS WILL BE CLOSE BY ACROSS THE LOWER OHIO VALLEY. TEMPS...MOS GUIDANCE IN GENERAL WORKS WELL CONSIDERING LOW LEVEL THERMALS THROUGHOUT THE PERIOD. HIGH TEMPS FRIDAY AND SATURDAY WILL BE HIGHLY DEPENDENT ON CLOUD COVER...BUT GENERALLY LOOKING AT LOW TO MID 80S BOTH DAYS...SLIGHTLY COOLER WHERE RAIN/CLOUDS IMPACT. CORE OF THE COOLER AIR ASSOCIATED WITH THE UPPER TROUGH LIKELY DELAYED TO SUNDAY AS 850MB TEMPS FALL TO AROUND 11C. LOCATIONS SUNDAY SHOULD REMAIN IN THE UPPER 70S AND LOWER 80S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... ISSUED AT 229 PM EDT THU AUG 8 2013 MODELS ARE SIMILAR ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED FOR MOST ITEMS IN THE LONG TERM. UPPER TROUGH WILL DEEPEN ACROSS THE AREA IN THE EXTENDED. THIS WILL KEEP CENTRAL INDIANA IN COOLER NORTHWEST FLOW. TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH THE PERIOD. A COLD FRONT WILL WORK ITS WAY SOUTH MONDAY INTO TUESDAY BRINGING THE COOLER AIR TO THE AREA. MODELS AND SOME ENSEMBLES ARE SHOWING CHANCES FOR RAIN LINGERING INTO TUESDAY WITH SOME TIMING DIFFERENCES BETWEEN THEM. GIVEN THE UNCERTAINTIES INVOLVED WILL GO WITH ALLBLEND/S CHANCES FOR RAIN MONDAY INTO TUESDAY...BUT AT THE MOMENT && .AVIATION /DISCUSSION FOR THE 081800Z TAF ISSUANCE/... ISSUED AT 100 PM EDT THU AUG 8 2013 LOW CONFIDENCE FORECAST...BUT GENERALLY VFR CONDITIONS GIVING WAY TO MVFR CONDITIONS OVERNIGHT WITH POTENTIAL FOR IFR. SCATTERED CONVECTION AROUND THROUGH THE PERIOD...ALONG WITH VARIABLE WINDS. WEAK BOUNDARY WILL REMAIN ACROSS CENTRAL INDIANA THIS AFTERNOON...MAKING WINDS VARIABLE. SCATTERED CONVECTION WILL PERSIST AROUND THIS BOUNDARY...BUT AT THE MOMENT IT APPEARS ORGANIZED CONVECTION WILL REMAIN OUT OF THE AREA. ANY CEILINGS BELOW MVFR SHOULD LIFT TO VFR BY VALID TIME EXCEPT FOR KLAF WHERE THEY WILL LINGER. DURING THE NIGHT THREAT FOR CONVECTION WILL CONTINUE BUT AT THE MOMENT DO NOT EXPECT WIDESPREAD CONVECTION /ALTHOUGH SOME MODELS INDICATE THIS POSSIBILITY...BUT ODDS ARE LOW WITHOUT ANY SIGNIFICANT FORCING NEARBY/. MOIST AIRMASS WILL LEAD TO MVFR VISIBILITIES/CEILINGS WITH POTENTIAL FOR IFR. THESE SHOULD IMPROVE ON FRIDAY WITH DRIER AIR WORKING IN AS BOUNDARY SHIFTS FARTHER SOUTH. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....50 AVIATION...50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
229 PM EDT THU AUG 8 2013 .UPDATE... THE LONG TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 210 AM EDT THU AUG 8 2013 WARM AND HUMID AIR WILL REMAIN OVER INDIANA FOR THE NEXT FEW DAYS AS A FRONTAL BOUNDARY LINGERS ACROSS SOUTHERN INDIANA. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH FRIDAY NIGHT AS SEVERAL UPPER LEVEL WEATHER DISTURBANCES PUSH INTO THE OHIO VALLEY. DRY AND LESS HUMID WEATHER WILL ARRIVE SATURDAY AS HIGH PRESSURE FROM CANADA BUILDS ACROSS THE REGION. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1003 AM EDT THU AUG 8 2013 LOW STRATUS STUBBORNLY HANGING ON ACROSS A GOOD PORTION OF THE FORECAST AREA...WITH CLOUDS HAVING ACTUALLY INCREASED IN COVERAGE OVER NORTHERN COUNTIES SINCE 12Z. SCATTERED CONVECTION HAS ALSO DEVELOPED OVER THE NORTHERN WABASH VALLEY OVER THE LAST HOUR OR SO. 13Z SURFACE ANALYSIS PLACES THE WEAK REMNANT BOUNDARY ACROSS THE FORECAST AREA...ROUGHLY EXTENDING FROM NEAR RICHMOND W/SW TO JUST SOUTH OF THE INDY METRO AND KHUF. MUGGY MORNING WITH TEMPS MAINLY IN THE 70S. COMPLEX FORECAST FOR THE REMAINDER OF THE DAY AS CONVECTION HAS DEVELOPED SOONER THAN ANTICIPATED. VERY WEAK FORCING ALOFT WITHIN A POORLY DEFINED UPPER TROUGH COMBINED WITH AN AREA OF LOW LEVEL MOISTURE CONVERGENCE APPEAR TO BE CONTRIBUTING TO THE CONVECTIVE DEVELOPMENT NORTHWEST OF INDY THIS MORNING. HRRR GUIDANCE IS CAPTURING THIS TO SOME DEGREE...AND TRENDS TOWARDS FURTHER CONVECTIVE DEVELOPMENT ACROSS THE FORECAST AREA INTO THE AFTERNOON. CONSIDERING INCREASING INSTABILITY OVER THE NEXT FEW HOURS COMBINED WITH THE DEEP LOW LEVEL MOISTURE PRESENT...WEAK FORCING ALOFT AND THE PRESENCE OF THE BOUNDARY ACROSS THE REGION...REALLY HARD TO ARGUE WITH THIS SCENARIO AT THIS POINT. BUMPED UP POPS TO BEGIN NORTHWEST OF INDY NOW...THEN INCREASE TO 30-50 POPS OVER ENTIRE FORECAST AREA FOR THE AFTERNOON. MENTIONING ONLY ISOLATED THUNDER THROUGH MIDDAY AS MESOANALYSIS SHOWS LITTLE INSTABILITY PRESENT RIGHT NOW. EXPECT A BETTER CHANCE FOR THUNDER THIS AFTERNOON AS INSTABILITY INCREASES WITH DIURNAL HEATING. WHILE THERE ARE BREAKS IN THE CLOUD COVER THIS MORNING... ESPECIALLY OVER SOUTHERN COUNTIES...HAVE INCREASED CLOUD COVERAGE FOR THE AFTERNOON AS CU LIKELY TO FILL IN AS CONVECTIVE TEMPS ARE MET. ADDITIONALLY...CLOUD DEBRIS FROM WEAKENING MCS OVER THE OZARKS POISED TO EXPAND INTO THE REGION THIS AFTERNOON. WITH THE INCREASE IN CLOUDS...DROPPED HIGH TEMPS A COUPLE DEGREES AS WELL. ZONE AND GRID UPDATES OUT SHORTLY. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 210 AM EDT THU AUG 8 2013 LITTLE CHANGE APPEARS IN THE OVERALL PATTERN THROUGH FRIDAY AFTERNOON. GFS AND NAM CONTINUE TO SUGGEST WEAK...POORLY ORGANIZED SHORT WAVES PUSHING THROUGH THE FLOW ALOFT. MEANWHILE THE FRONTAL BOUNDARY LINGERS NEAR THE OHIO VALLEY. 310K GFS ISENTROPIC SURFACE FAILS TO SHOW MUCH IN THE WAY OF LIFT...BUT DOES MANAGE TO ILLUSTRATE THE VERY MOIST AIR MASS ACROSS THE AREA SHOWING SPECIFIC HUMIDITIES IN EXCESS OF 4 G/KG ON FRIDAY. FORECAST SOUNDINGS THROUGH FRIDAY SHOW LESS FAVORABLE LAPSE RATES WITH LESS CAPE THAN TODAY. HOWEVER WITH THE MOIST FLOW ALOFT...MOIST AIR IN PLACE AT THE SURFACE AND UNCERTAINTY REMAINING WITH ANY EMBEDDED SHORT WAVES WILL CONTINUE TO KEEP LOW CHC POPS TONIGHT AND AGAIN ON FRIDAY. WILL TREND LOWS WARMER THAN MAVMOS AND STICK CLOSE ON HIGHS FOR FRIDAY. ON FRIDAY NIGHT THE GFS AND NAM BOTH SUGGEST A STRONG SHORT WAVE ALOFT SWEEPING THROUGH THE FLOW. TIME HEIGHT SECTIONS BEGIN TO SHOW MORE VV WHILE THE NAM SOUNDINGS SHOW DEEP SATURATION. THE GFS IS MUCH LESS AGGRESSIVE WITH SATURATION...BUT STILL DOES SHOW THE MAIN WAVE ALOFT. MEANWHILE GFS 310K ISENTROPIC SURFACE SHOWS MINIMAL LIFT...BUT A VERY MOIST AIR MASS IN PLACE WITH SPECIFIC HUMIDITIES OVER 5 G/KG AGAIN. IN THE LOWER LEVELS...BEST CONVERGENCE REMAINS NEAR THE FRONT...LINGERING NEAR THE OHIO RIVER. THUS WILL USE A BLEND OF THE LOW GFS POPS AND THE HIGHER NAM POPS FOR FRIDAY NIGHT. A MUCH DIFFERENT AIR MASS ARRIVES ON SATURDAY AND SATURDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS THE AREA FROM CANADA. FORECAST SOUNDINGS AGREE AS THE COLUMN DRIES OUT DRAMATICALLY AMID SUBSIDENCE. CONVECTIVE TEMPERATURES LOOK QUITE REACHABLE WITH A MID LEVEL CAP IN PLACE...THUS EXPECTED SOME AFTERNOON CU ON SATURDAY AND MOSTLY CLEAR SKIES THAT NIGHT. GIVEN THE FORECAST SOUNDINGS WILL TREND HIGHS ON SATURDAY COOLER THAN MAVMOS AND STICK CLOSE ON LOWS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... ISSUED AT 229 PM EDT THU AUG 8 2013 MODELS ARE SIMILAR ENOUGH THAT THE ALLBLEND INITIALIZATION CAN BE USED FOR MOST ITEMS IN THE LONG TERM. UPPER TROUGH WILL DEEPEN ACROSS THE AREA IN THE EXTENDED. THIS WILL KEEP CENTRAL INDIANA IN COOLER NORTHWEST FLOW. TEMPERATURES WILL REMAIN BELOW AVERAGE THROUGH THE PERIOD. A COLD FRONT WILL WORK ITS WAY SOUTH MONDAY INTO TUESDAY BRINGING THE COOLER AIR TO THE AREA. MODELS AND SOME ENSEMBLES ARE SHOWING CHANCES FOR RAIN LINGERING INTO TUESDAY WITH SOME TIMING DIFFERENCES BETWEEN THEM. GIVEN THE UNCERTAINTIES INVOLVED WILL GO WITH ALLBLEND/S CHANCES FOR RAIN MONDAY INTO TUESDAY...BUT AT THE MOMENT FEEL THAT BEST CHANCES WILL BE LATER ON MONDAY INTO MONDAY NIGHT. && .AVIATION /DISCUSSION FOR THE 081800Z TAF ISSUANCE/... ISSUED AT 100 PM EDT THU AUG 8 2013 LOW CONFIDENCE FORECAST...BUT GENERALLY VFR CONDITIONS GIVING WAY TO MVFR CONDITIONS OVERNIGHT WITH POTENTIAL FOR IFR. SCATTERED CONVECTION AROUND THROUGH THE PERIOD...ALONG WITH VARIABLE WINDS. WEAK BOUNDARY WILL REMAIN ACROSS CENTRAL INDIANA THIS AFTERNOON...MAKING WINDS VARIABLE. SCATTERED CONVECTION WILL PERSIST AROUND THIS BOUNDARY...BUT AT THE MOMENT IT APPEARS ORGANIZED CONVECTION WILL REMAIN OUT OF THE AREA. ANY CEILINGS BELOW MVFR SHOULD LIFT TO VFR BY VALID TIME EXCEPT FOR KLAF WHERE THEY WILL LINGER. DURING THE NIGHT THREAT FOR CONVECTION WILL CONTINUE BUT AT THE MOMENT DO NOT EXPECT WIDESPREAD CONVECTION /ALTHOUGH SOME MODELS INDICATE THIS POSSIBILITY...BUT ODDS ARE LOW WITHOUT ANY SIGNIFICANT FORCING NEARBY/. MOIST AIRMASS WILL LEAD TO MVFR VISIBILITIES/CEILINGS WITH POTENTIAL FOR IFR. THESE SHOULD IMPROVE ON FRIDAY WITH DRIER AIR WORKING IN AS BOUNDARY SHIFTS FARTHER SOUTH. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...PUMA NEAR TERM...RYAN SHORT TERM...PUMA LONG TERM....50 AVIATION...50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS WICHITA KS
108 PM CDT THU AUG 8 2013 .UPDATE... ISSUED AT 102 PM CDT THU AUG 8 2013 MCV OVER EASTERN KS WAS NOT WELL HANDLED BY OVERNIGHT GUIDANCE AND ONLY MARGINALLY WELL BY 1200 UTC RUNS. RADAR/SATELLITE TRENDS SHOW PRECIPITATION ON THE WANE. BEST CHANCES LIKELY WILL BE IN SOUTHEAST KS WHERE DEEPER MOISTURE/BETTER INSOLATION AND INSTABILITY MAY BE SUFFICIENT TO BREAK CAP LATE THIS AFTERNOON/EVENING. ANTICIPATING PRECIPITATION TO WANE THIS EVENING AND MUCH OF THE NIGHT...BUT SIMILAR TO THIS MORNING...BELIEVE PRECIPITATION WILL DEVELOP AND MOVE INTO SOUTH CENTRAL/SOUTHEAST KS JUST PRIOR TO DAYBREAK. EARLY LOOK APPEARS TO SUGGEST THAT PRECIPITATION MAY NOT BE AS HEAVY AS PREVIOUS DAYS. TEMPERATURES THIS AFTERNOON WILL LIKELY REBOUND WITH SOME BREAKS IN CLOUDS IN SOUTHEAST KS. -HOWERTON && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 TODAY & TONIGHT: AS ALL OBVIOUSLY KNOW...FLOODING TO CONTINUE BEINGING THE HIGHLIGHT OF FOR PERIODS AS FLOOD WATCH REMAINS IN EFFECT TIL 7 AM FRIDAY. DURING THE NIGHT A POORLY-DEFINED STATIONARY FRONT WAS DRAPED IN AN E-W MANNER GENERALLY THROUGH CNTRL OK WITH A WEAK 700-MB TROF SITUATED FROM THE UT/CO BORDER TO ~CA/AZ BORDER. WITH THE TROF SLOWLY EVOLVING INTO A WEAK LOW AS IT VENTURES E TO WRN KS RICH & DEEP MOISTURE WILL CONTINUE TO SPREAD NE ACROSS KS. WITH THE MID-LVL "KICKER" LACKING THE SFC-850MB FRONTS WILL MOVE VERY LITTLE...IF AT ALL...THEREBY PROMOTING BROAD ECHO TRAINING OVER KICT COUNTRY WHICH IN TURN WOULD EXACERBATE THE FLOODING SITUATION ACROSS THE CWA. ONLY CHANGES TO INHERITED FORECAST WERE TO SHIFT THE POP GRADIENT TO GENERALLY A N/S ORIENTATION TO BETTER ALIGN WITH THE BROAD LWR-MID DECK MOISTURE CHANNEL. ASSIGNED 80-100% TO CNTRL & SC KS THIS MORNING WITH HIGHEST POPS & ASSOCIATED TSRA SHIFTED E OVER SE KS THIS AFTERNOON AS HRRR DEPICTS. PW`S REMAIN IN 175-200% RANGE SO CONTINUED TO HIT QPFS HARD. FRI & FRI NIGHT: A FAIRLY BROAD UPR-DECK RIDGE IS FORECAST MOVE SLOWLY MOVG E TOWARD THE CNTRL ROCKIES...THE WEAK MID-LVL LOW WILL GET FORCED E TOWARD...THEN ACROSS...ERN KS. THIS WOULD THEREFORE SHIFT BULK OF +TSRA E ACROSS THE KS/MO BORDER ON FRI WITH -TSRA CONFINED FROM GENERALLY THE FLINT HILLS E FRI NGT. AS SUCH WILL CONTINUE TO SCHEDULE THE FLOOD WATCH TO END AT 7AM FRI. SAT & SAT NGT: MOST AREAS WILL EXPERIENCE AN INTERMISSION FROM TSRA. A FEW TSRA SHOULD VENTURE TOWARD THE WRN CORRIDOR SAT NGT AS WEAK LWR-DECK TROFFING BEGINS ALONG THE FRONT RANGE. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 328 AM CDT THU AUG 8 2013 ALL AREAS TO BE UNDER A WEAK NW FLOW REGIME FOR MOST OF THESE PERIODS. A WEAK COLD FRONT WILL VENTURE SE TOWARD & PERHAPS ACROSS KICGT COUNTRY EARLY NEXT WEEK WHICH WOULD INCREASE TSRA CHANCES FOR MUCH OF THESE PERIODS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 102 PM CDT THU AUG 8 2013 ANTICIPATE VFR CONDITIONS THIS AFTERNOON...ALTHOUGH A FEW SITES MAY BRIEFLY HAVE MVFR CEILINGS AT THE ONSET. ISOLATED/SCATTERED THUNDERSTORMS POSSIBLE AT KCNU/SE KS LATER THIS AFTERNOON/EVENING DRIVEN BY AFTERNOON HEATING AND DEEP LOW LEVEL MOISTURE. BETTER CHANCES OF PRECIPTATION WILL OCCUR CLOSER TO DAYBREAK AT KHUT/KICT/KCNU AS NEXT IN SERIES OF UPPER SHORTWAVES MOVE THROUGH THE AREA. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 68 79 65 83 / 50 40 10 10 HUTCHINSON 65 76 63 82 / 40 40 10 10 NEWTON 66 76 63 81 / 40 50 10 10 ELDORADO 67 79 64 82 / 50 50 20 10 WINFIELD-KWLD 70 82 66 84 / 60 30 10 10 RUSSELL 63 76 62 82 / 20 40 10 10 GREAT BEND 63 75 61 81 / 30 40 10 10 SALINA 65 77 63 83 / 30 50 10 10 MCPHERSON 65 76 63 82 / 30 50 10 10 COFFEYVILLE 71 86 68 84 / 80 40 20 10 CHANUTE 69 81 66 82 / 70 60 20 10 IOLA 68 80 66 81 / 60 70 20 10 PARSONS-KPPF 70 84 67 83 / 80 50 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ032-033-047>053- 067>072-082-083-091>096-098>100. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1159 AM MDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 446 AM MDT THU AUG 8 2013 FORECAST CONCERNS WILL BE THREAT OF HEAVY RAINFALL AND CHANCES OF PRECIPITATION. SATELLITE SHOWING LITTLE CHANGE AS A COMPLEX AND AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO NORTH AMERICA REMAINS IN PLACE. COMPLEX AND SLOW MOVING UPPER HAS MOVED INTO COLORADO AND NEW MEXICO. SEVERAL SHORTWAVE TROUGHS ROTATING AROUND THIS MAIN SYSTEM. AIR MASS REMAINS MOIST THROUGH A DEEP LAYER. PERSISTENT FRONTAL BOUNDARY REMAINS DRAPED TO OUR SOUTH AND WEST. AT JET LEVEL...THE CANADIAN AND THE UKMET INITIALIZED BEST ON THE JET THAT IS OVER/NEAR OUR AREA. AT MID LEVELS...SATELLITE AND UPPER AIR ANALYSIS SHOW THAT THE ECMWF/CANADIAN FOLLOWED BY THE GFS ARE HANDLING CURRENT SYSTEM THE BEST. SREF AND RUC WERE DOING BEST AT THE SURFACE. COMPLICATED AND DIFFICULT PRECIPITATION FORECAST MADE MORE DIFFICULT BY THE FACT THAT MOST IF NOT ALL THE MODEL OUTPUT HAS CURRENT PRECIPITATION SHIELD TOO FAR SOUTH AND IS BASICALLY IGNORING IT. TODAY/TONIGHT...WEAK RIGHT REAR QUADRANT OF THE UPPER JET REMAINS OVER THE AREA FOR MOST OF THE DAY. MODELS ARE IN A LITTLE MORE DISAGREEMENT ON HOW FAST TO MOVE THIS SEGMENT EAST. ALTHOUGH THE GENERAL TREND IS TO HAVE THIS SLOWER/FURTHER WEST THAN THE PREVIOUS TWO DAYS. THE SLOWEST OF THE MODELS DO NOT TAKE THIS RIGHT REAR QUADRANT TO THE EAST OF THE FORECAST AREA UNTIL BETWEEN 06Z AND 12Z. BASED ON CURRENT SATELLITE...LATEST ECMWF IS CATCHING THE POSITION AND COMPLEXITY OF THE UPPER TROUGH THE BEST. CONSIDERING THE POSITION OF THE 700 MB LOW CIRCULATION...MODELS INDICATING WARM ADVECTION/UPGLIDE IN ADVANCE OF IT...PLUS STRONG UPPER DIVERGENCE INDICATED THE EASTERN PORTION OF THE AREA...BELIEVE THE CURRENT PRECIPITATION WILL CONTINUE TO MOVE AND DEVELOP AND MAINLY AFFECT THE EASTERN TH