Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 310018 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 818 PM EDT THU JUL 30 2015 .SYNOPSIS... A COLD FRONT CROSSES THE AREA THIS EVENING AND TONIGHT. HIGH PRESSURE RETURNS FRIDAY INTO SATURDAY. A WEAK COLD FRONT CROSSES THE AREA SATURDAY NIGHT...BEFORE HIGH PRESSURE RETURNS TO START NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... THE MUCH ANTICIPATED COLD FRONT HAS REACHED THE SPINE OF THE APPALACHIANS AS OF MID AFTERNOON...AND WILL CONTINUE TO MOVE EAST INTO THE LOCAL AREA THIS EVENING BEFORE PUSHING OFF THE COAST PRIOR TO DAYBREAK. AS EXPECTED...A BROKEN LINE OF SHWRS AND TSTMS HAS DEVELOPED AHEAD OF THE FRONT ACROSS THE EASTERN PIEDMONT AND WILL SLOWLY PROGRESS EASTWARD THRU THE EVENING HOURS. THERE`S CERTAINLY PLENTY OF INSTABILITY AROUND THIS AFTERNOON WITH DEW PTS IN THE LOW/MID 70S AND TEMPS IN THE UPR 80S/LOW 90S...CREATING MIXED LAYER CAPE VALUES OF 1500-2000 J/KG ALONG/WEST OF I-95. HOWEVER...EFFECTIVE SHEAR VALUES REMAIN QUITE WEAK (<20 KT) WHICH WILL IN TURN LIMIT THE SVR POTENTIAL OF ANY TSTM THRU THE EVENING. THAT BEING SAID...CANNOT RULE OUT BRIEF GUSTY WINDS TO 40 MPH AND HEAVY RAIN WITH THE STRONGEST CELLS. WILL CONTINUE WITH 40-60% POPS N-NW THROUGH THE EARLY EVENING HOURS WHERE BEST CHANCE OF CONVECTION WILL REMAIN...SLIGHT CHC (20%) POPS ACROSS THE SE. AS THE FRONT MAKES IS WAY INTO AND ACROSS THE REGION LATER THIS EVENING AND OVERNIGHT...WILL LOWER POPS ACROSS N-NW AREAS WHILE MAINTAINING 30-40% POPS FROM THE I-95 CORRIDOR ONTO THE EASTERN SHORE. EXPECTING DRY WX TO RETURN TO N-NW AREAS AFTER MIDNIGHT WITH 30% POPS E-SE ZONES THROUGH DAYBREAK AS THE FRONT EXITS THE COAST. GRADUALLY CLEARING SKIES ACROSS THE N-NW OVERNIGHT. LOW TEMPS FROM THE MID 60S NW TO THE LOW/MID 70S ALONG THE COAST. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... FRIDAY IS LOOKING DRY FOR ALL BUT THE FAR SE PARTS OF THE FA AS HIGH PRESSURE ARRIVES BEHIND THE DEPARTING FRONT. THE HUMIDITY WILL BE LOWER AS WELL. HAVE 20% POPS FAR SE...CLOSEST TO THE STALLING FRONTAL BOUNDARY. HIGHS IN THE UPR 80S TO LOW 90S...EXCEPT MID 80S COAST. FRIDAY NIGHT AND SATURDAY... HIGH PRESSURE WILL REMAIN OVER THE AREA FOR DRY WX AND A MOSTLY CLEAR TO PARTLY CLOUDY SKY. HUMIDITY LEVELS START TO INCREASE A LITTLE ON SAT. LOWS FRI NIGHT IN THE 60S TO LWR 70S. HIGHS ON SAT IN THE LOW 90S...EXCEPT MID 80S COAST. SATURDAY NIGHT AND SUNDAY... A WEAK COLD FRONT IS NOW SHOWN TO MOVE ACROSS THE AREA SATURDAY NIGHT. WHAT REMAINS TO BE SEEN IS WHETHER OR NOT IT CAN MUSTER UP ENOUGH MOISTURE TO PRODUCE A FEW SHOWERS AS IS PASSES. FOR NOW...HAVE LEFT THE FORECAST DRY AS MODELS NOT ALL THE CONVINCED THAT IT WILL. MAINLY CLR TO PTLY CLDY WITH LOWS IN THE MID 60S TO LOW 70S. REMAINING DRY MOST PLACES ON SUNDAY AS HIGH PRESSURE REBOUNDS. THERE`S A SMALL (20%) CHANCE OF ISOLD SHOWERS ACROSS THE FAR SE WITH A WEAK COASTAL BOUNDARY STILL IN PLACE. HIGHS SUNDAY IN THE UPR 80S TO LOW 90S...EXCEPT MID 80S COAST. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... PATTERN BEGINS WITH A MID/UPPER LEVEL RIDGE CENTERED OVER THE SW CONUS AND AN UPPER LEVEL LOW NEAR HUDSON BAY CANADA. GFS/ECMWF ARE IN GOOD AGREEMENT WITH THIS OVERALL SETUP INTO TUE...BUT THEN DIVERGE QUITE A BIT WED/THU...THE OPERATIONAL GFS BEING MUCH STRONGER/PUSHING FARTHER SOUTH WITH THE UPPER TROUGH THAN THE ECMWF (OR THE GFS ENSEMBLE MEANS). TYPICAL SUMMERTIME TEMPERATURES CAN BE EXPECTED MON WITH HIGHS MAINLY RANGING FROM THE MID 80S/AROUND 90 F ALONG THE COAST TO THE LOWER 90S INLAND. GENLY LOOKS DRY ALTHOUGH WILL MAINTAIN A 20-30% POP IN NE NC DUE TO POTENTIAL SEABREEZE. FOR TUE-WED...FAIRLY CONFIDENT IN HOT WX FOR TUE...AS BOTH MODELS HAVE RISING H8 TEMPS AND A W/SW FLOW IN LOW LEVELS. WILL MAINTAIN A 20% POP DUE MAINLY TO A WEAK CAP WITH H5 HEIGHTS ONLY 585-588 DM. HIGHS MAINLY IN THE MID 90S INLAND AND 90-95 F AT THE COAST. LESS CONFIDENCE FOR WED/THU...GFS WOULD SUGGEST MUCH COOLER CONDS...WHILE THE ECMWF WOULD SUPPORT HIGHS IN THE MID 90S TO PERHAPS 100 F. WHILE THE ECMWF/WPC PATTERN WILL GENLY BE FAVORED (COLD FRONT TO OUR NORTH UNTIL THU AFTN)...THINK THE DRIER/HOTTER WX WILL ULTIMATELY NOT BE AS HOT AS PREDICTED DUE TO ANTECEDENT WET/HUMID CONDITIONS OF THE PAST MONTH. FOR NOW WILL SHOW A SLIGHT COOLING WITH HIGHS WED 90-95 F AND THU UPPER 80S TO LWR 90S. DEW PTS ARE FORECAST BY MODELS TO MIX OUT INTO THE LOW 60S WEST OF I-95 THROUGH THE PERIOD...GENLY STAYED A LITTLE HIGHER THAN THIS...MID 60S WEST TO LWR 70S EAST. FOR NOW THIS YIELDS HEAT INDICES STAYING BELOW 105 F NEXT WEEK. AS FOR POPS...WILL ONLY HAVE ~20% POPS WED...RISING TO 30% MOST AREAS THU W/ THE APPROACH OF THE COLD FRONT FROM THE N. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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AS OF 00Z...WIDELY SCT SHOWERS/TSTMS HAVE DIMINISHED BUT HAVE NOT ENDED AND WILL THREATEN SOME OF THE TAF SITES DURING THE REMAINDER OF THE EVENING. A COLD FRONT NEAR CHARLOTTESVILLE AND SE OF ROANOKE WILL PUSH SOUTHEAST AND FORECAST TO PASS THROUGH RIC BY 06Z AND ECG AROUND 12Z. MOS HAS MVFR VSBYS AT SBY THROUGHOUT THE EVENING AND OVERNIGHT. HAVE MVFR AT SBY FROM 04 TO 08Z. N/NW WINDS DEVELOP BEHIND THE COLD FRONT. A MOSTLY CLEAR SKY WILL PREVAIL ON FRIDAY. OUTLOOK...DRY WEATHER PREVAILS SATURDAY. A SLGT CHC OF TSTMS IS IN THE FCST SUNDAY THROUGH TUESDAY...ESPECIALLY SRN PORTIONS.
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&& .MARINE... LATEST OBS REFLECT SE FLOW ACROSS THE WATERS THIS AFTN...SHIFTING TO THE S/SW AND TO AVG ~15 KT THIS EVENING. WINDS TURN TO THE NNW AFTER MIDNIGHT THROUGH FRI MORNING. NOT ANTICIPATING A STRONG COOL SURGE ON FRI BUT WILL NOT TAKE MUCH TO GET ~15 KT WINDS FRI MORNING WITH SFC WATER TEMPS AT OR ABOVE 80 F OVER THE BAY/RIVERS (STAYING JUST BELOW SCA THRESHOLDS FOR NOW BUT WOULD NOT BE SURPRISED TO SEE A FEW HRS WITH GUSTS TO 20 KT FRI MORNING). EXPECT WAVES IN THE BAY 2-3 FT THIS EVENING DROP OFF TO 1-2 FT AFTER MIDNIGHT THEN INCREASE BACK TO 2-3 FT FRI MORNING BEFORE DIMINISHING FRI AFTN. SEAS AVG 3-4 FT N AND 2-3 FT S. WINDS SHIFT TO THE NNE MIDDAY FRI...BECOMING E BY LATE IN THE DAY/FRI EVENING. WINDS THEN TURN BACK TO THE SSW FOR FRI NGT AND SAT...AS THE FRONT WEAKENS JUST TO OUR SSE ALONG THE CAROLINA COAST. A WEAK FRONT NOW PROGGED TO CROSS THE AREA SAT NIGHT/EARLY SUN...BEFORE TURNING BACK TO THE SOUTH LATE SUN INTO NEXT WEEK AS SFC HIGH PRESSURE BECOMES ANCHORED OVER THE WESTERN ATLANTIC. WAVES SAT INTO NEXT WEEK AVG 1-2 FT IN THE BAY WITH SEAS 2-4 FT. && .TIDES/COASTAL FLOODING... SLY CHANNELING HAS RESULTED IN SOME NUISANCE-TYPE TIDAL ANOMALIES ON THE ORDER OF A HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL AT BISHOPS HEAD/CAMBRIDGE. WATER LEVELS LOOK TO APPROACH, BUT STILL FALL SHORT OF MINOR FLOOD THRESHOLDS WITH ASTRONOMICALLY HIGHER TIDE CYCLE LATE TONIGHT. FALLING WATER LEVELS THEREAFTER AS FLOW TURNS NORTHERLY INTO FRI MORNING. ANOMALIES MAY RISE AGAIN LATE SAT/SAT NIGHT IN S FLOW UP THE BAY AHEAD OF ANOTHER WEAK COLD FRONT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM LONG TERM...LKB AVIATION...LSA MARINE...LKB TIDES/COASTAL FLOODING...

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