Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 120748 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 348 AM EDT SAT JUL 12 2014 .SYNOPSIS... HIGH PRESSURE BUILDS SOUTH ACROSS THE MID ATLANTIC REGION THROUGH THE WEEKEND. LOW PRESSURE MOVES ACROSS THE GREAT LAKES REGION WITH THE TRAILING COLD FRONT APPROACHING FROM THE NORTHWEST EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... ***NWS SURVEY TEAM CONFIRMS BOTH AN EF-0 TORNADO AND STRAIGHT LINE WINDS IN VIRGINIA BEACH*** (SEE PNSAKQ FOR DETAILS) ***NWS CONFIRMS STRAIGHT LINE WIND DAMAGE IN THE CAPRON AREA AND ACROSS SOUTHAMPTON COUNTY*** A WEAK FRONTAL BOUNDARY WILL DISSIPATE OVER SE NORTH CAROLINA TODAY AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. STILL SOME WEAK INSTABILITY OVER NE NC AND WITH LIGHT FLOW COULD SEE A SEABREEZE INDUCED ISOLATED STORM IN THE AFTN SO WILL KEEP SLIGHT CHC DIURNAL POPS ACROSS INTERIOR NE NC. OTW...PT TO MSTLY SUNNY AND WARMER TODAY AS H85 TEMPS RISE A BIT. HIGHS LWR-MID 80S AT THE COAST TO UPPER 80S/LOW 90S ALONG/WEST OF THE I-95 CORRIDOR. MAINLY CLEAR TONIGHT WITH LOWS IN THE 60S TO AROUND 70 F. && .SHORT TERM /SUNDAY THROUGH MONDAY/... HOT WX RETURNS ON SUNDAY. NEXT S/W PROGGED TO MOVE ACROSS THE GREAT LAKES AND NE STATES WITH A SFC THERMAL TROF PROGGED EAST OF THE MTS DURING THE AFTN. HOWEVER...RISING HEIGHTS ALOFT LOOKS TO CAP THE ATMOSPHERE FOR THE MOST PART SO WILL ONLY CARRY SLIGHT CHC POPS (~20%) AT MOST FOR AFTN TSTMS WELL INLAND AND OVER THE NORTH...KEEPING IT DRY ACRS SE VA/NE NC. HIGHS LOW-MID 90S...EXCEPT M80S AT THE BEACHES. FLOW TURNS TO THE SSW IN EARNEST ON MON AHEAD OF AN APPROACHING COLD FRONT...WITH INCREASING MOISTURE AND BUILDING HEAT. ENOUGH INSTABILITY PROGGED FOR SCTD AFTN TSTMS ALL AREAS (30-40% POPS)... EXCEPT NC OUTER BANKS WHERE A 20% POP WILL BE MAINTAINED. HIGHS 90-95...EXCEPT MID 80S AT THE BEACHES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... HIGHLY ANOMALOUS FLOW WILL DEVELOP OVER THE CONUS DURING THE MEDIUM RANGE...AS A STRONG CLOSED LOW DROPS OVER THE GREAT LAKES REGION. THE RESULT WILL BE BELOW NORMAL TEMPS AND WET CONDITIONS FROM THE UPPER MIDWEST TO THE OH VALLEY. HOWEVER...THE LOCAL AREA REMAINS SEASONABLY WARM AS MUCH OF THE COOLER AIR WILL BE LOCKED WEST OF THE CNTRL APPALACHIANS. AS AN ANOMALOUS TROUGH DEVELOPS OVER THE ERN CONUS...HEIGHT FALLS AND INCREASE WINDS ALOFT WILL RESULT IN BETTER FORCING FOR ASCENT OVER THE LOCAL AREA. WITH A WARM/MOIST AIRMASS ALREADY IN PLACE (MODEL DERIVED PRECIP WATERS ~ 2+ INCHES)...EXPECT BETTER COVERAGE OF SHOWERS/THUNDERSTORMS MON AFTERNOON ALONG A SHARPENING LEE/THERMAL TROUGH. HOWEVER...THE BEST DYNAMICS WILL REMAIN WEST OF THE LOCAL AREA ALONG THE COLD FRONT...SO THE BEST CHANCES WILL BE IN THE NORTH AND WEST. ANOTHER AREA OF SHOWERS/THUNDERSTORMS WILL LIKELY DEVELOP ALONG THE TROUGH/BOUNDARIES...CLOSEST TO THE BEST INSTABILITY. HIGHS TUE EXPECTED IN THE LOW 90S WITH DEW POINTS IN THE NEAR 70. STRONG SPEED MAX ROUNDS THE DEEP CLOSED LOW OVER THE GREAT LAKES TUES...EJECTING THE LOW NEWD INTO SE CANADA. THE COLD FRONT DROPS INTO THE REGION TUES NIGHT. STRONGEST DYNAMICS LIFT WELL NORTH OF THE REGION WITH THE CLOSED LOW...BUT HEIGHT FALLS AND PERTURBATIONS IN THE WSW FLOW WILL RESULT IN SCT-NUMEROUS SHOWERS/THUNDERSTORMS. STRONG TO SEVERE THUNDERSTORMS ALSO POSSIBLE AS MODELS DEPICT MARGINAL SHEAR AND MLCAPE > 2000 J/KG. ANOMALOUS TROUGH WILL PUSH THE SRN PORTION OF THE FRONT INTO THE DEEP SOUTH...BUT THE ERN PORTION LIKELY STALLING OVER/OFF THE MID-ATLANTIC COAST AS AN ANOMALOUS UPPER RIDGE REMAINS PARKED OVER THE WRN ATLANTIC. WILL MAINTAIN SLIGHT CHANCE-CHANCE POPS WEDS ACROSS THE SE AS THE FRONT WILL LIKELY LINGER OVER THE REGION. SFC HIGH PRESSURE WILL BE SLOW TO BUILD INTO THE REGION IN WAKE OF THE FRONT AS UPPER TROUGH REMAINS OVER THE ERN CONUS. BUT...WITH THE STALLED BOUNDARY ACROSS THE SE AND A PASSING SHORTWAVE TROUGH...SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE NEXT WEEKEND. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... SURFACE HIGH PRESSURE IS CENTERED FROM THE MID ATLANTIC TO NEW ENGLAND AS OF 06Z. THE SKY IS MAINLY CLEAR ASIDE FROM SOME PATCHY STRATUS ALONG THE COAST AND A ~10K FT MID-CLOUD DECK OVER W-CENTRAL VA. FOG IS DEVELOPING ACROSS THE AREA WITH SURFACE HIGH PRESSURE IN PLACE AND ABUNDANT LOW-LEVEL MOISTURE. AT PHF IFR FOG HAS DEVELOPED AS OF 06Z. IFR CONDITIONS ARE EXPECTED TO PREVAIL AT PHF THROUGH ~11Z...ALTHOUGH THE VSBY WILL LIKELY VARY GREATLY THROUGH THIS TIME PERIOD. A PERIOD OF IFR FOG IS EXPECTED AT THE REMAINING TERMINALS IN A WINDOW BETWEEN 08-12Z...WITH THE EXCEPTION OF ORF WHICH WILL LIKELY REMAIN VFR. THERE IS SOME UNCERTAINTY AT RIC WHERE THE MID-CLOUDS MAY INHIBIT FOG DEVELOPMENT. MOSTLY CLEAR CONDITIONS ARE EXPECTED TO PREVAIL TODAY AND TONIGHT WITH ONLY PASSING HIGH CLOUDS. A LIGHT WIND WILL SHIFT TO SE TODAY THEN S TONIGHT AS HIGH PRESSURE SHIFTS OFFSHORE. DRY WEATHER CONTINUES INTO SUNDAY WITH THE HIGH OFFSHORE AND LOW PRESSURE TRACKING WELL NW OF THE LOCAL AREA. A COLD FRONT WILL BRING THE POTENTIAL FOR SHRA/TSRA MONDAY AND TUESDAY. && .MARINE... LIGHT E/SE FLOW AOB 10KT SHOULD PREVAIL TODAY AS HIGH PRESSURE DRIFTS OFF THE NEW ENGLAND COAST. THE WIND WILL SHIFT TO S TONIGHT AS THE HIGH SETTLES OFF THE COAST...AND THEN SSW SUNDAY INTO MONDAY WITH HIGH PRESSURE ANCHORED OFF THE COAST. SPEEDS SHOULD INCREASE SUNDAY NIGHT INTO MONDAY AND AVERAGE 15-20KT OVER THE OCEAN AND 10-15KT BAY/SOUND/RIVERS. A COLD FRONT APPROACHES FROM THE NW MONDAY NIGHT. 12/00Z GFS IS FASTER THAN THE 12/00Z NAM (THROUGH 84HR) AND THE 12/00Z ECMWF/CMC. THE CURRENT FORECAST WILL FOLLOW MORE TOWARD THE 00Z ECMWF FOR WIND DIRECTION/FRONTAL TIMING. THIS WILL ALLOW THE WIND TO REMAIN SSW THROUGH TUESDAY NIGHT...BEFORE SHIFTING TO NORTHERLY WEDNESDAY. HIGH PRESSURE BUILDS OVER THE AREA BEHIND THE FRONT WITH THE WIND BECOMING LIGHT AND VARIABLE. SEAS SHOULD AVERAGE 2-3FT THROUGH SUNDAY WITH 1-2FT WAVES IN THE BAY. THE PERSISTENT (AND ENHANCING) SSW WIND SHOULD BUILD SEAS TO 3-4FT N SUNDAY NIGHT INTO MONDAY...WITH PERHAPS A PERIOD OF ~5FT FAR N BY MONDAY NIGHT. SEAS SHOULD REMAIN 2-3FT ACROSS THE SRN COASTAL ZONES. WAVES IN THE BAY SHOULD AVERAGE 2-3FT SUNDAY NIGHT THROUGH MONDAY NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM/LKB LONG TERM...SAM/DAP AVIATION...AJZ MARINE...AJZ

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