Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 040233 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1033 PM EDT THU SEP 3 2015 .SYNOPSIS... A WEAK TROUGH OF LOW PRESSURE WILL PERSIST OVER THE LOCAL AREA OVERNIGHT WITH HIGH PRESSURE CENTERED OVER THE OHIO VALLEY. STRONGER HIGH PRESSURE THEN SLOWLY DROPS DOWN FROM THE NORTHEAST STATES FRIDAY AFTERNOON THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... WEAK SFC TROUGH PERSISTS ACRS THE REGION THIS EVENING...WITH LIGHT NW FLOW ALOFT. AIRMASS REMAINS SLIGHTLY UNSTABLE AS OF 02Z...EVIDENCED BY SOME MODEST ML CAPES PER SPC MESOANALYSIS AND ISOLATED/WIDELY SCATTERED TSTMS CONTINUING OVER NORTHERN VA AND PORTIONS OF THE PIEDMONT. HAVE EXTENDED 20-30% POPS OVER THE FAR NORTH AND IN THE PIEDMONT THROUGH 1 AM. OTHERWISE...WARM/HUMID UNDER VARIABLY CLOUDY SKIES WITH TEMPS MAINLY IN THE 70S. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 60S IN RURAL AREAS OF INTERIOR VA/MD TO THE LWR 70S ELSEWHERE. PATCHY FOG DEVELOPING IN SOME AREAS...THOUGH WITH DEW PTS THIS HIGH RARELY SEE DENSE FOG DEVELOPMENT AND EXPECT MOST AREAS TO MAINTAIN VSBY OF 2SM OR GREATER OVERNIGHT. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... ANOMALOUS UPPER RIDGE BUILDS OVER THE NE CONUS DURING THE SHORT TERM. A WEAKNESS UNDER THE RIDGE LOCATES OVER THE -SE STATES...RESULTING IN WEAK FLOW ALOFT. LARGE SCALE CONFLUENCE OVER ERN CANADA AND NEW ENGLAND WILL ALLOW STRONG SFC HIGH PRESSURE TO BUILD SWD INTO NEW ENGLAND...PUSHING A BACKDOOR FRONT INTO THE RGN FRI MRNG-AFTN. SFC WNDS TURN TO THE NE FRI...RESULTING IN THE BEGINNINGS OF A COOL DOWN. A WARM/MOIST AND MODERATELY UNSTABLE AIR MASS (SREF MLCAPE VALUES 1000-1500 J/KG) WILL REMAIN OVVR THE FA IN ADVANCE OF THE FRONT. MORE STABLE ALONG THE COAST DUE TO ONSHORE FLOW. HAVE MAINTAINED SLGT CHC TO CHC POPS E AND CNTRL...BUT HAVE CONTD W/ SOLID CHANCE (40-50%) OVR THE PIEDMONT AS WEAK S/W DROPS OVR THE RGN. VRB CLDS- PARTLY CLOUDY CONDS W/ HI TEMPS FM THE M-U80S INVOF ERN SHORE/ALG THE CST TO THE U80S-ARND 90F INLAND. THE WX FM FRI NGT THROUGH SUN LOOKING MORE UNSETTLED THAN BEFORE. PDS OF LO LVL CLDS XPCD INTO SUN W/ CONTD ENE WNDS. GUSTS UP TO 25 MPH NR THE CST LT FRI NGT. MDLS TDA ARE LESS EMPHATIC ABT DRIER AIR MASS PUSHING SSW INTO/ACRS THE FA THIS WKND. COMBO HI PRES TO THE NNE AND LO PRES OVR SE CONUS TO KEEP MOIST ONSHORE WNDS AND LIKELIHOOD OF WK IMPULSES TRACKING ACRS THE FA FM THE E. WILL HAVE 20-40% POPS SAT-SUN...HIGHEST IN SE VA/NE NC. CONTD BREEZY (GUSTS TO 25-30 MPH NR THE CST IN ERN VA/NE NC) ON SAT...LESS WND XPCD SUN. HI TEMPS SAT FM THE M-U70S NR THE CST TO ARND 80F INLAND. LO TEMPS SAT NGT FM THE M60S TO ARND 70F. HI TEMPS SUN FM THE U70S TO L80S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... LONG TERM PERIOD STARTS OFF SUN NGT AND MON WITH SFC LO PRES SPINNING OFF THE CAROLINA CST WITH HI PRES N AND W OF THE FA. RESULTANT ONSHORE FLOW WILL LEAD TO TEMPS ONLY MAKING IT INTO THE MID 80S MON UNDER A PRTLY-MSTLY SKY. WITH THE MOIST ONSHORE FLOW DID HOLD ONTO SOME SLGT CHANCE-CHANCE POPS OVER MUCH OF THE FA SUN NGT/MON. KEPT THUNDER OUT DUE TO A LACK OF INSTABILITY. THE SFC LO WEAKENS AND STARTS SLIDING E TUE ALLOWING FOR DRIER CONDS AND TEMPS REBOUNDING INTO THE MID/UPR 80S UNDER A PRTLY CLOUDY SKY. DRY WX CONTINUES MIDWEEK WITH TEMPS FURTHER INCREASING AS SLY FLOW DEVELOPS AHEAD OF THE NEXT COLD FRNT...WITH HI TEMPS IN THE UPR 80S TO NR 90 WED AND THUR. THE FRNT WILL CROSS THE AREA SOMETIME LATE THU OR FRI. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... SOME WIDELY SCATTERED CONVECTION STILL REMAINING ACROSS THE REGION WHICH SHOULD GENERALLY DISSIPATE DURING THE OVERNIGHT. NO TAF SITES ARE AT RISK FOR ANY ACTIVITY. EXPECT SOME AREAS OF MVFR FOG/HAZE TO AGAIN DEVELOP OVERNIGHT WITH THE CHC FOR PTCHY IFR CONDS. SCATTERED DIURNAL CONVECTION POSSIBLE AGAIN FRIDAY ALONG BACKDOOR COLDFRONT PASSAGE. DRY WEATHER AND VFR CONDITIONS THROUGH THE WEEKEND. && .MARINE... SCA HEADLINES HAVE BEEN ISSUED WITH THIS FORECAST PACKAGE FOR THE OCEAN/BAY/LWR JAMES. FOR TNGT...WEAK TROF OF LO PRES OVER THE WTRS WILL LEAD TO VRB WINDS UNDER 10 KT. NE FLOW THEN DEVELOPS FRI AS A BACKDOOR COLD FRNT DROPS TWRDS THE REGION AND HI PRES OVERSPREADS THE NE STATES. WINDS WILL SLOWLY INCREASE THRU THE DAY OVER ALL WTRS...TO 15-20 KT OVER THE BAY/OCEAN BY THE EVENG HRS AND LWR JAMES BY ERLY OVRNGT. AT THE SAME TIME...WAVES OVER THE LWR BAY WILL INCREASE TO 4 FT WITH SEAS OVER CSTL WTRS UP TO 6 FT. THE SCA WILL RUN THRU THE END OF THE 4TH PERIOD FOR NOW (SAT AFTN) BUT MAY HAVE TO BE EXTENDED FURTHER OUT IN TIME ESPECIALLY OVER CSTL WTRS WITH SEAS AOA 5 FT LIKELY CONTINUING INTO SAT NGT/SUN. IN ADDITION...THE ONSHORE FLOW AND HI WAVES WILL ENHANCE THE RIP CURRENT THREAT FOR THE HOLIDAY WKEND. GUID CONTS TO BUILD TIDES TO 1 FOOT ABOVE NRML BY SAT...CLOSE TO MINOR FLOODING THRESHOLDS IN SOME LOCATIONS. WINDS/WAVES/SEAS DECREASE INTO ERLY NEXT WEEK AS THE SFC HI WEAKENS AND FLOW BCMS MORE OUT OF THE E THAN NE. WINDS THEN TURN TO THE S MIDWEEK AHEAD OF THE NEXT COLD FRNT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM FRIDAY TO 7 PM EDT SATURDAY FOR ANZ630>632-634-650-652-654-656-658. SMALL CRAFT ADVISORY FROM 10 PM FRIDAY TO 7 PM EDT SATURDAY FOR ANZ638. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...ALB/SAM LONG TERM...MAS AVIATION...DAP/JEF MARINE...MAS

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