Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 311352 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 952 AM EDT SUN MAY 31 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN CENTERED WELL OFF THE MID ATLANTIC COAST THROUGH SUNDAY. A SLOW MOVING COLD FRONT WILL APPROACH FROM THE NORTHWEST SUNDAY NIGHT INTO MONDAY...THEN DROP ACROSS THE REGION MONDAY NIGHT THROUGH TUESDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/...
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LATEST GOES WATER VAPOR IMAGERY DEPICTS STUBBORN UPPER RIDGE REMAINING ALONG THE ERN SEABOARD. HOWEVER...A PATTERN CHANGE IS TAKING SHAPE OVER THE CENTRAL CONUS IN THE FORM OF A DEEPENING UPPER TROUGH. AT THE SFC...HIGH PRESSURE REMAINS OVER THE AREA. ISO SHOWERS OVER MECKLENBURG/LUNENBURG COUNTIES ARE CURRENTLY DISSIPATING. OTHERWISE...PARTLY TO MOSTLY SUNNY CONDITIONS ARE OCCURRING MID-MORNING...WITH TEMPERATURES AVERAGING FROM 75-80F. SHORTWAVE ENERGY WILL SHEAR/DAMPEN AS IT LIFTS OVER THE OH VALLEY TODAY. SFC LOW ALSO LIFTS OVER THE OH VALLEY. TRAILING COLD FRONT WILL LOCATE OVER THE OH/TN VALLEY THIS AFTERNOON. A MOISTURE PLUME DEPICTED ON MORNING WATER VAPOR WILL SPREAD INTO THE TN/KY VALLEYS THIS AFTERNOON...WITH PWATS REMAINING NEARLY IDENTICAL TO 24 HOURS AGO. WHILE THETA-E ADVECTION AND WARM TEMPS WILL PRODUCE MLCAPE VALUES OF 1000-1500 J/KG THIS AFTERNOON...LIMITED MOISTURE AND A LACK OF APPRECIABLE FORCING UNDER THE RIDGE WILL RESULT IN ONLY ISOLATED (AT BEST) CONVECTION OVER THE PIEDMONT THIS AFTERNOON. WARM TEMPS ALOFT/MODEST MID-LEVEL LAPSE RATES WILL ALSO WORK AGAINST UPDRAFTS. AS A RESULT...HAVE TRIMMED POPS BACK TO SLIGHT CHANCE OVER THE PIEDMONT AND NRN COUNTIES. SILENT POPS (POP ~10%) WILL BE MAINTAINED IN THE SE COUNTIES WHERE VERY ISO SEABREEZE CONVECTION IS POSSIBLE. ANOTHER WARM DAY WITH H85 TEMPS AND THICKNESSES SIMILAR TO 24 HRS AGO. HIGHS MID-UPPER 80S (COOLER ALONG THE COAST) UNDER A PARTLY CLOUDY SKY. WITH THE LOSS OF UPPER LEVEL SUPPORT...THE WEAK SFC LOW AND TRAILING COLD FRONT ARE PROGGED TO STALL TONIGHT AS THE BETTER DYNAMICS REMAIN OVER THE MIDWEST. EXPECT MUCH OF THE LOCAL AREA TO REMAIN DRY TONIGHT...BUT INCREASING MOISTURE AND MODEST ELEVATED INSTABILITY MAY BE ENOUGH FOR ISOLATED SHOWERS. MILD AGAIN TONIGHT...WITH LOWS IN THE MID-UPPER 60S (8-10 DEGS ABOVE AVERAGE).
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&& .SHORT TERM /MONDAY THROUGH TUESDAY/... MODELS CONTINUING THE TREND OF BREAKING THE MIDWEST SHORTWAVE OFF FROM THE WESTERLIES SUN NIGHT THRU TUES. THE UPPER LOW DIGS OVER THE GULF STATES MON-TUES...POSSIBLY CLOSING OFF TUES. MEANWHILE...A NRN STREAM SHORTWAVE TRAVERSES THE GREAT LAKES MON NIGHT-TUES. SFC LOW OVER THE NRN MID-ATLANTIC REGION WEAKENS MON...BUT THE APPROACHING NRN STREAM ENERGY WILL RE-INTENSIFY THE LOW OVER THE NRN MID-ATLANTIC REGION MON NIGHT-TUES. THE COLD FRONT WILL LOCATE JUST WEST OF THE LOCAL AREA MON. THIS WILL PROVIDE LOW-LEVEL CONVERGENCE IN WHAT IS FORECAST TO BE A WARM/HUMID/UNSTABLE AIRMASS. HAVE MAINTAINED LIKELY POPS NORTH AND WEST OF RICHMOND MON AFTERNOON...WITH CHANCE-SOLID CHANCE POPS SOUTH AND EAST. ONLY A SLIGHT CHANCE ALONG THE IMMEDIATE COAST. WILL CONTINUE CHANCE POPS MON NIGHT AS DEEPENING MOISTURE AND ELEVATED INSTABILITY EXIST IN ADVANCE OF THE FRONT. LOCALLY HEAVY RAINFALL WILL BE THE MAIN THREAT AS MOISTURE INCREASES AND STEERING FLOW IS WEAK. WARM AGAIN MON AS THE AREA REMAINS UNDER THE INFLUENCE OF WARM RETURN FLOW. HIGHS MID- UPPER 80S (COOLER ALONG THE COAST). MILD YET AGAIN MON NIGHT WITH LOWS IN THE MID- UPPER 60S. BEST CHANCES FOR WIDESPREAD BENEFICIAL RAINFALL WILL BE TUESDAY AFTERNOON. NRN STREAM ENERGY PUSHES OFFSHORE AS THE CLOSED UPPER LOW REMAINS OVER THE GULF STATES. LARGE SCALE CONFLUENCE WILL REMAIN OVER SE CANADA...KEEPING SFC HIGH PRESSURE NORTH OF THE REGION. HAVE INCREASED ALL AREAS TO LIKELY EXCEPT FOR THE IMMEDIATE COAST. AGAIN...LOCALLY HEAVY RAINFALL WILL BE POSSIBLE AS ANOMALOUS PWATS COMBINE WITH WEAK STEERING FLOW. CLOUD COVER/PRECIP WILL LIMIT INSTABILITY...WITH ONLY 15-20 KT EFFECTIVE SHEAR EXPECTED...LIMITING THE POTENTIAL FOR SEVERE WEATHER. COOLER TUES WITH HIGHS IN THE LOW- MID 80S (COOLER ALONG THE COAST). GEFS/SREF PROBABILITIES INDICATE A WIDESPREAD BENEFICIAL ONE HALF INCH TO ONE INCH IS EXPECTED ACROSS MUCH OF THE LOCAL AREA. THE EXCEPTION WILL BE THE SE COUNTIES AND THE IMMEDIATE COAST...WITH ABOVE GENERALLY AOB ONE QUARTER OF AN INCH. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... LOW PRESSURE AND ITS ASSOCIATED COLD FRONT SLOWLY SAG SOUTH OF THE REGION TUE NIGHT. THE FRONT STALLS ALONG THE SE COAST WED THROUGH THE REMAINDER OF THE WEEK. MEANWHILE...SFC HIGH PRESSURE MOVES INTO NEW ENGLAND ON WED AND SLOWLY SHIFTS EWD THROUGH FRI. TO THE WEST OF THE STALLED FRONT AND SFC HIGH TO THE NORTH...AN UPPER TROUGH GETS STUCK OVER THE GULF COAST STATES. THE LOCATIONS OF ALL THE AFOREMENTIONED FEATURES WILL CAUSE MOISTURE AND SHORTWAVE ENERGY SPINNING AROUND THE TROUGH TO BE SQUEEZED UP THE COASTAL PLAIN OF THE CAROLINAS AND VIRGINIA...KEEPING UNSETTLED CONDITIONS ACROSS THE MID ATLANTIC REGION DURING THE MID TO END OF THE WEEK TIMEFRAME. 12Z MODEL TRENDS SHOW THE TROUGH SLOWLY SHIFTING OVER THE SE STATES DURING THE WEEKEND WITH A SFC LOW TRAVELLING UP THE SE/CAROLINA COASTS ALONG THE STALLED FRONTAL BOUNDARY. OVERALL...PERIODS OF SHOWERS AND THUNDERSTORMS SHOULD BE ANTICIPATED. GIVEN THE LIGHT STEERING FLOW ALOFT OF 5-15/20KT THROUGHOUT THE LONG TERM FORECAST PERIOD...IT IS TOO DIFFICULT TO NAIL DOWN THE EXACT TIMING AND PLACEMENT OF PRECIPITATION AND WILL THUS LEAN THE FORECAST TWD A 10-30 PERCENT CHANCE POP AT ANY GIVEN TIME. WITH THE PERIODIC SHOWERS/STORMS WILL COME PERIODS OF CLOUDS AND SUN. LOWS WILL GENERALLY BE IN THE 60S. HIGHS WILL GENERALLY BE IN THE UPPER 70S WED WITH A WARMING TREND THROUGH THE REST OF THE WEEK. HIGHS IN THE LOW-MID 80S THU/FRI...MID-UPPER 80S SAT (AROUND 5 DEGREES COOLER AT THE IMMEDIATE COAST). && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... SCT-BKN MID LVL CLDNS XPCT TODAY...WITH MOST IF NOT ALL DIURNAL CONVECTION REMAINING NW OF THE TAF SITES. S WINDS AOB 10 KTS. LCL C-BREEZE ALONG CSTL TAF SITE PSBL THIS AFTRN. OUTLOOK...NXT CHC FOR SHOWERS/TSTMS COMES LATE MON THRU TUES AS A COLD FRONT CROSSES THE REGION. ONSHORE FLOW LATE TUES INTO WED COULD RESULT IN MARGINAL CIGS/VSBYS ESPECIALLY SRN PORTIONS. && .MARINE... OFFSHORE RIDGE HOLDG FIRM WITH NOT MUCH CHANGE NOTED IN THE DAY TO DAY FCST...SO WILL FOLLOW PERSISTANCE AND KEEP THE S-SE WINDS BLO SCA LVLS. A FEW GUSTS TO 20 KTS PSBL ACROSS THE BAY THIS AFTRN AND EVE...BUT DON`T SEE ENUF SUSTAINED GUSTS TO WARRENT SCA HEADLINES. MWS`S SHUD SUFFICE MUCH LIKE YSTRDY. WAVES IN THE BAY AVGG ARND 2 FT WITH SEAS AVGG 3-4 FT...HIGHEST OUT NR 20 NM. LOW PRS TRACKS NE ACROSS NRN VA TUESDAY. THE TRAILING COLD FRNT PROGGED TO CROSS THE AREA TUE AFTRN AND NIGHT. SOME UNCERTAINITY AS TO HOW FAR S AND E THIS BNDRY ACTUALLY GETS (MAY STALL OVR THE RGN THRU THE MID WEEK PRD). DESPITE WNDS SHFTG TO AN ERLY DRCTN...SPEEDS XPCTD TO REMAN BLO SCA LVLS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM/SAM NEAR TERM...SAM/AJZ SHORT TERM...SAM LONG TERM...BMD AVIATION...MPR MARINE...MPR

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