Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 242109 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 409 PM EST MON NOV 24 2014 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA TONIGHT...FOLLOWED BY WEAK HIGH PRESSURE TUESDAY. LOW PRESSURE TRACKS UP THE EAST COAST TUESDAY NIGHT THROUGH WEDNESDAY. THIS AREA OF LOW PRESSURE DEPARTS TO THE NORTHEAST WEDNESDAY NIGHT. A SECONDARY LOW TRACKS ACROSS THE REGION EARLY THURSDAY...BEFORE HIGH PRESSURE BUILDS IN FROM THE WEST LATER THURSDAY INTO FRIDAY. && .NEAR TERM /THROUGH TUESDAY/... LATEST REGIONAL RADAR MOSAIC DEPICTS LIGHT PRECIP ASSOCIATED WITH SWLY FLOW AND A NARROW BAND OF MOISTURE (STUCK BTWN TROUGH IN THE CNTRL CONUS AND A RIDGE OVER THE WRN ATLANTIC) LIFTING ALONG THE SE COAST INTO NE NC. STRONG 155+ KT JET STREAK ORIENTED SW-NE ACROSS THE OH VALLEY PROVIDING DIVERGENCE ALOFT TO HELP MAINTAIN THIS AREA OF PRECIP. AT THE SFC...COLD FRONT STILL LOCATED TO THE WEST...WITH LATEST SFC ANALYSIS PLACING THE FRONT OVER THE CNTRL APPALACHIANS...STRETCHING NEWD INTO QUEBEC. HI-RES GUIDANCE CONTINUES TO JUMP AROUND WITH LIFTING THE PRECIP INTO THE REGION LATE THIS AFTERNOON INTO THE EVENING. BEST UVM REMAINS NEAR THE COAST...ASSOCIATED WITH THE NARROW BAND OF MOISTURE/THETA-E RIDGE AND A NARROW RIBBON OF VORTICITY...SO HAVE KEPT THE BEST POPS NEAR THE COAST (30-40%). WITH THE LOSS OF DAYTIME HEATING...EXPECT PRECIP TO DISSIPATE OVER ERN NC/NE NC AND S-SW WINDS TO DECREASE. THE COLD FRONT WILL CROSS THE REGION THIS EVENING...REACHING THE COAST AFTER MIDNIGHT INTO EARLY TUES MORNING. THE ADDED CONVERGENCE IN TANDEM WITH THE THETA-E RIDGE WILL LIKELY RESULT IN ADDITIONAL LIGHT PRECIP IN THE SE. BUMPED POPS UP INTO LOW END CHANCE POPS AGAIN AFTER MIDNIGHT TONIGHT (30-40%). CLOUDS WILL INCREASE FROM THE SOUTH INTO CNTRL VA TONIGHT...WITH SKIES AVG PARTLY CLOUDY NW TO CLOUDY SE. DEWPOINTS IN THE 50S TO LOW 60S...5-10 KT OF WIND AND CLOUD COVER WILL RESULT IN MILD OVERNIGHT TEMPS IN THE UPPER 40S NW TO LOW 60S SE. FOR TUESDAY...FRONT STALLS JUST OFFSHORE AS FLOW ALOFT REMAINS SWLY. STRONG SHORTWAVE WILL DIG INTO THE SRN PLAINS AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE FRONT OVER THE NRN GULF. THIS LOW WILL BE A MAJOR PLAYER DURING THE SHORT TERM AS IT LIFTS ALONG THE FRONT. WEAK AREA OF HIGH PRESSURE WILL BUILD INTO CNTRL VA...WHILE THE FRONT REMAINS JUST OFF THE SE COAST. UPPER JET MOVES VERY LITTLE TUES...BUT STRENGTHENS TO 175+ KT. MODELS DEPICT ANOTHER SHEAR AXIS/VORT LOBE OVER THE SE ASSOCIATED WITH NARROW BAND OF MOISTURE...WHICH WILL BE ENOUGH FOR LIGHT PRECIP TO CONTINUE ALONG THE COAST. POPS INCREASE LATE ALONG THE COAST TO LIKELY AS THE LOW EMERGES OFF THE SE COAST AND MOISTURE ADVECTION INCREASES. HIGHS TUES FORECAST IN THE UPPER 50S NW TO MID 60S SE. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... DEVELOPING LOW PRESSURE OFF THE SOUTHEAST COAST TUESDAY TRACKS NNE TUESDAY NIGHT REACHING A POSITION NEAR CAPE LOOKOUT BY 12Z WED. THE 24/12Z SUITE OF NUMERICAL GUIDANCE CONTINUES TO DEMONSTRATE GOOD AGREEMENT WITH THIS SYSTEM. A BAND OF MID-LEVEL FRONTOGENESIS IS PROGGED TO LIFT OVER THE REGION TUESDAY EVENING...WHICH WILL PERSIST OVERNIGHT. MID-LEVEL THERMAL ADVECTION RAPIDLY INCREASES AFTER MIDNIGHT...AND COMBINED WITH THE FRONTOGENESIS SHOULD RESULT IN AREAS OF MODERATE TO HEAVY RAIN ACROSS THE REGION. POPS INCREASE TO LIKELY TUESDAY EVENING ACROSS SE PORTIONS...WITH CATEGORICAL POPS AFTER MIDNIGHT. TEMPERATURES TO BEGIN THE NIGHT SHOULD BE IN THE UPPER 40S NW...TO MID 50S SW...AND GRADUALLY FALL OVERNIGHT AS IN SITU WEDGING DEVELOPS DUE TO RAIN AND A LIGHT N WIND. BY 12Z WED TEMPERATURES SHOULD RANGE FROM THE UPPER 30S NW...TO NEAR 50 SW. MODERATE TO OCCASIONALLY HEAVY PCPN SHOULD CONTINUE INTO WED MORNING AS MOISTURE REMAINS DEEP AND FORCING REMAINS STRONG. CAA REMAINS RATHER WEAK. HOWEVER...DYNAMICAL COOLING SHOULD DRIVE TEMPERATURES DOWN INTO THE LOW/MID 30S OVER THE NW PIEDMONT COUNTIES THROUGH WED MORNING...WITH UPPER 30S/LOW 40S ELSEWHERE. GIVEN THE TRACK OF THE SURFACE/850MB LOW AND CLIMO THE MOST LIKELY LOCATIONS TO RECEIVE ACCUMULATING SN WOULD BE ACROSS THE FAR NW PIEDMONT COUNTIES. AT THIS TIME A 1-2IN ACCUMULATION IS FORECAST OVER LOUISA/FLUVANNA...BORDERED BY LESS THAN 1IN. MOISTURE SHALLOWS WEDNESDAY AFTERNOON...SO PCPN SHOULD STEADILY LESSEN IN INTENSITY BEFORE ENDING LATE WED AFTERNOON/EARLY EVENING. LOCATIONS THAT CHANGE TO SN COULD ACTUALLY SWITCH BACK OVER TO -RA AS THE INTENSITY WANES. OVERALL LIGHT SN ACCUMULATION SHOULD BE NW OF THE RIC METRO AREA. A BRIEF LULL IS EXPECTED WED NIGHT...BEFORE A SECONDARY CLIPPER-TYPE SYSTEM DIVES ACROSS THE REGION LATE WED NIGHT/EARLY THANKSGIVING DAY. THIS WILL BRING A CHC OF -SHRA OR -SHSN (OR A MIX THEREOF) TO PORTIONS OF CENTRAL AND ERN VA. HIGH PRESSURE BUILDS IN FROM THE WEST BY AFTERNOON WITH PARTIAL CLEARING EXPECTED FROM W-E. MORNING LOWS SHOULD RANGE FROM AROUND 30 NW...TO THE MID 30S SE...FOLLOWED BY HIGHS IN THE MID/UPPER 40S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... GOING WITH A BLEND OF THE 00Z/24 GFS/ECMWF FOR THE EXTENDED PD. STRONG LO PRES WILL BE JUST OFF THE DE CST AT 00Z THU...AND WILL CONTINUE TO INTENSIFY AS IT TRACKS NNE AND JUST OFF THE MAINE CST BY 12Z THU. PCPN WILL BE TAPERING OFF AND END FM SW TO NE WED EVE INTO EARLY THU MORNG (AS EITHER SNOW SNOWERS OR A MIX OF RA/SN). A MAINLY DRY FRONT SWINGS ACRS THE AREA THU AFTN INTO THU NGT. HI PRES WILL BLD INTO AND OVR THE REGION FRI INTO SAT...THEN SLIDES OFF THE MID ATLC/SE CST FOR SAT AFTN THRU SUN. MAX TEMPS WILL BE IN THE MID 40S TO LWR 50S THU...IN THE 40S FRI...IN THE MID 40S TO LWR 50S SAT...AND IN THE UPR 40S TO MID 50S SUN. MIN TEMPS WILL BE IN THE UPR 20S TO MID 30S THU MORNG...IN THE MID 20S TO LWR 30S FRI AND SAT MORNGS...AND IN THE 30S SUN MORNG. && .AVIATION /21Z MONDAY THROUGH SATURDAY/... PRESSURE GRADIENT IN ADVANCE OF AN APPROACHING COLD FRONT HAS PRODUCED GUSTY S-SW WINDS OVER THE LOCAL AREA. GUSTS HAVE REACHED AS HIGH AS 33 KNOTS AT THE TAF SITES. MID-LEVEL DECK INLAND CONTINUES TO SCATTER OUT...WITH ONLY FEW-SCT CLOUDS WITH DECKS 3-4K FT AGL REMAINING. AN AREA OF SHOWERS AND LOW-MID CLOUDS LOCATED ALONG THE SE COAST THIS AFTERNOON WILL CONTINUE TO LIFT NEWD...POSSIBLY REACHING NE NC AND TAF SITE KECG BY MID-LATE AFTERNOON. LEFT MENTION OUT OF 18Z TAFS DUE TO LOW CONFIDENCE BUT WILL ADJUST ACCORDINGLY. COLD FRONT CROSSES THE REGION THIS EVENING INTO THE OVERNIGHT...WITH WINDS DIMINISHING AOB 10-12 KT THIS EVENING AND AOB 10 KT OVERNIGHT. CIGS MAY LOWER THIS EVENING AHEAD OF THE FRONT...RESULTING IN SOME PATCHY IFR CONDITIONS. GUIDANCE CONTINUES TO SUGGEST IFR VSBYS AS WELL...BUT BASED ON MIXING/DISPERSION AND SUFFICIENT DEWPOINT DEPRESSIONS...HAVE STAYED MVFR/VFR WITH THE OVERNIGHT TAFS. THE EXCEPTION WILL BE KECG WHERE DEWPOINT DEPRESSIONS WILL BE SMALLER. TRENDED CIGS DOWN AS WELL...BUT KEPT MENTION OF IFR OUT ATTM BASED ON CONFIDENCE. WEAK HIGH PRESSURE BUILDS IN TUES WITH VFR CONDITIONS. SOME LIGHT RAIN AND LOW CLOUDS IS STILL EXPECTED ACROSS THE SE. LOW PRESSURE DEVELOPS ALONG THE COLD FRONT TUES NIGHT...LIFTING ALONG THE SE AND MID-ATLANTIC COASTS WEDS. MVFR AND IFR CONDITIONS ARE POSSIBLE IN WIDESPREAD RAIN. GUSTY WINDS ALSO POSSIBLE ALONG THE COAST. && .MARINE... WILL CONTINUE INHERITED HEADLINES WITH THIS FORECAST PACKAGE AS WINDS OVR CSTL WTRS CONTINUE TO GUST NEAR 35 KT (GALE WARNING) WHILE OVR THE BAY THEY ARE MORE IN THE 25-30 KT RANGE (SCA). THE GALE WILL END LATE THIS MORNG...AND WILL BE REPLACED BY A SCA THRU TNGT WITH SEAS AOA 5 FT. THE SCA OVR THE BAY ENDS LATE THIS AFTN AS STRONG SLY FLOW CONTINUES AHEAD OF AN APPROACHING COLD FRNT. THE FRNT CROSSES THE WTRS LATE TNGT INTO TUE MORNG...WITH IMPROVING MARINE CONDS THEN INTO TUE AFTN WITH WEAK HI PRES OVR THE AREA. STRONG NE TO NW FLOW IS THEN EXPECTED TUE NGT THRU WED NGT...AS LO PRES TRACKS NEWRD JUST OFF THE E CST. EXPECT ANOTHER ROUND OF STRONG SCA CONDS EVERYWHERE AND PSBL GALES OVR THE CSTL WTRS WITH THIS SYSTM. && .CLIMATE... UNSEASONABLY WARM WX EXPECTED TODAY. RECORD HIGH TEMPERATURES FOR TODAY (11/24). RIC 76 1979 ORF 78 1983 SBY 78 1931 ECG 77 1983 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ630>634-638. SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ650-652-654- 656-658. && $$ SYNOPSIS...AJZ NEAR TERM...SAM SHORT TERM...AJZ/ALB LONG TERM...ALB/TMG/JEF AVIATION...MAS/SAM MARINE...MAS CLIMATE...AKQ

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