Area Forecast Discussion
Issued by NWS Wakefield, VA

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569 FXUS61 KAKQ 092149 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 449 PM EST TUE FEB 9 2016 .SYNOPSIS... LOW PRESSURE LIFTS WELL OFF THE NORTHEAST COAST TONIGHT. AN UPPER LEVEL TROUGH SWINGS THROUGH THE REGION LATER TONIGHT. HIGH PRESSURE SLOWLY RETURNS WEDNESDAY THROUGH FRIDAY. LOW PRESSURE LIFTS ALONG THE SOUTHEAST COAST FRIDAY AND FRIDAY NIGHT. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... LATEST REGIONAL RADAR MOSAIC DEPICTS SCATTERED SHOWERS GENERALLY ALONG AND EAST OF INTERSTATE 95 THIS AFTERNOON. EARLIER OBS/REPORTS INDICATED EMBEDDED SLEET WITH MUCH OF THE PRECIP OVER THE REGION. THIS PROVES JUST HOW COLD AND DYNAMIC THE SYSTEM IS...WITH H85 TEMPS -6 TO -8C ALONG WITH STEEP MID LEVEL LAPSE RATES. NO ACCUMULATION EXPECTED AS TEMPERATURES REMAIN IN THE LOW/MID 40S. ANOMALOUS MERIDIONAL FLOW PREVAILS OVER THE CONUS...HIGHLIGHTED BY A DEEP TROUGH ENCOMPASSING MUCH OF THE ERN CONUS. AT THE SFC...~991MB LOW PRESSURE HAS CENTERED WELL OFF THE MID-ATLANTIC COAST WITH ANOTHER AREA OF LOW PRESSURE OVER THE ERN GREAT LAKES REGION. A WEAK SFC TROUGH REMAINS OVER THE NERN LOCAL AREA...PROVIDING BETTER LOW LEVEL CONVERGENCE FOR THE NRN NECK AND MD ERN SHORE. NAM 285K THETA SURFACES HAVE HANDLED THE EARLIER PRECIP WELL...SO CONTINUING WITH THAT TREND FAVORS THE AFOREMENTIONED AREAS OF THE NRN NECK AND ERN SHORE...AS WELL AS SE VA/NE NC THRU THE REST OF THE AFTERNOON. EXPECT A WINTRY MIX OF RAIN/SNOW OVER THE NRN NECK AND MD ERN SHORE...BUT EXPECT ALL RAIN SE VA/NE NC AS THE WARM LAYER IS DEEPER AND BETTER MIXED NEAR THE COAST. NO SNOW ACCUMULATION IS EXPECTED FOR THE MD ERN SHORE THRU 6PM AS SFC TEMPS REMAIN IN THE LOW 40S WITH DEWPOINTS IN THE MID/UPPER 30S. FOR THE OVERNIGHT...EMBEDDED SHORTWAVE/VORT MAX REACHES NRN VA THIS EVENING...DEVELOPING A WEAK WAVE OF LOW PRESSURE ALONG THE SFC TROUGH OFF THE NEW JERSEY COAST. EXPECT PRECIP TO LINGER OVER THE NRN NECK/ERN SHORE THRU THE EVENING HOURS. LOW LEVEL CRITICAL THICKNESSES BEGIN TO DROP OFF SHARPLY THIS EVENING AS A COLDER/DRIER AIR MASS SURGES INTO THE REGION. EXPECT A WINTRY MIX TO TRANSITION TO SNOW SHOWERS THIS EVENING FOR THE NRN NECK/MD ERN SHORE...BUT SFC TEMPS FORECAST TO HOVER IN THE MID 30S. DEWPOINTS WILL FALL INTO THE UPPER 20S RESULTING IN WET BULBS IN THE LOW 30S. DO NOT EXPECT THE BEST DYNAMICS TO ARRIVE UNTIL LATE TONIGHT...BUT NOT BEFORE THE BEST MOISTURE PUSHES OFFSHORE. MINOR SNOWFALL ACCUMULATIONS ARE POSSIBLE ON ELEVATED AND GRASSY SURFACES...WITH AMOUNTS GENERALLY AOB HALF AN INCH...MAINLY OVER THE MD ERN SHORE. WILL HOLD ON TO CHANCE POPS FOR SNOW SHOWERS THRU LATE TONIGHT FOR THE MD ERN SHORE AS THE VORT MAX PUSHES THRU. SKY REMAINS GENERALLY PARTLY CLOUDY TO MOSTLY CLOUDY WITH WLY WINDS 10-15 MPH...PREVENTING A SHARP DROP OFF IN TEMPS. LOWS IN THE MID/UPPER 20S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... ANOMALOUS/DEEP UPPER TROUGH PREVAILS ACROSS THE ERN CONUS WEDS AS A STRONG RIDGE PERSISTS ALONG THE WEST COAST. SFC LOW PRESSURE LIFTS OFF THE NEW ENGLAND COAST THRU THE DAY WEDS AS HIGH PRESSURE BUILDS OVER THE GULF OF MEXICO. WILL MAINTAIN SLIGHT CHANCE FOR SNOW SHOWERS EARLY WEDS MORNING AS THE POTENT VORT MAX PUSHES OFF THE DELMARVA. OTHERWISE...DRY CONDITIONS PREVAIL WEDS AS A COLD/DRY AIR MASS ADVECTS INTO THE REGION. STEEP LAPSE RATES STILL PRESENT DUE TO THE COLD POOL ALOFT SO EXPECT PARTLY CLOUDY TO MOSTLY CLOUDY CONDITIONS. HAVE STAYED ON THE COLD SIDE OF GUIDANCE...WITH HIGHS GENERALLY IN THE LOW/MID 40S. WLY WIND 10-15 MPH. TROUGH AXIS ALIGNS ALONG THE MID-ATLANTIC COAST WEDS NIGHT AS ADDITIONAL SHORTWAVE ENERGY DIVES DOWN THE BACK SIDE OF THE UPPER TROUGH. EXPECT MOSTLY DRY CONDITIONS AS PWATS WILL BE AOB 0.10 INCHES...BUT AS COLDER AIR SPILLS IN...COULD SEE A FEW BAY ENHANCED SNOW SHOWERS ACROSS MAINLY THE VA ERN SHORE SO WILL MAINTAIN 20-30 POPS THERE. COLD WEDS NIGHT WITH LOWS IN THE UPPER TEENS PIEDMONT TO MID 20S ALONG THE COAST. DRY/COLD THURS AS THE TROUGH AXIS PUSHES OFFSHORE...USHERING IN AN EVEN COLDER AND DRIER ARCTIC AIR MASS. HIGHS GENERALLY IN THE LOW/MID 30S...OR -1 TO -1.5 STD DEV. SKY AVERAGES SUNNY TO MOSTLY SUNNY. HIGH PRESSURE SETTLES OVER THE REGION THURS NIGHT AND FRI AS ADDITIONAL ENERGY DIGS OVER THE MIDWEST INTO THE GULF STATES. ASSOCIATED AREA OF LOW PRESSURE PROGGED TO DEVELOP OFF THE SOUTHEAST COAST FRI...WITH A SLIGHT CHANCE FOR RAIN/SNOW ACROSS THE SOUTHEAST LATE FRIDAY. SLIGHTLY WARMER...BUT STILL COLD WITH HIGHS IN THE MID/UPPER 30S (-1 STD DEV). && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... STRONG COLD FRONT CROSSES THE REGION THROUGH THE DAY ON SATURDAY. BEHIND THE FRONT...ARCTIC AIRMASS IS USHERED INTO THE MID-ATLANTIC. STRONG UPPER LEVEL DYNAMICS MAY BE ENOUGH TO FORM A FEW SNOW SHOWER SAT MORNING. WRAP AROUND MOISTURE FROM WEAK AREA OF LOW PRESSURE DEVELOPING OFF THE COAST OF THE CAROLINAS MAY BRING A SLIGHT CHANCE FOR -SN/-RASN ACROSS NE NC. STRONG COLD AIR ADVECTION CONTINUES THROUGH THE DAY ON SAT WITH 925MB TEMPS DROPPING 10C THROUGH THE DAY. THICKNESSES AND TEMPERATURES ALOFT CONTINUE DROPPING THROUGH THE WEEKEND AS UPPER TROUGH SWINGS ACROSS THE AREA AND SURFACE HIGH PRESSURE BUILDS WEST...CENTERING OVER THE GREAT LAKES REGION. EXPECT HIGH TEMPS IN THE MID/UPR 30S. COLDEST AIRMASS OF THE SEASON SETTLES IN SAT NIGHT WITH LOWS DROPPING INTO THE SINGLE DIGITS AND LOW TEEN SUN MORNING(LOWS OVER 20F BELOW NORMAL). EXPECT HIGHS IN MID/UPR 20S ON SUN WITH TEMPERATURES FALLING BACK INTO THE TEENS SUN NIGHT. ACTIVE WEATHER PATTERNS CONTINUES FOR THE BEGINNING OF THE WORK WEEK. WITH THE SURFACE HIGH PRESSURE MOVING OFF THE COAST...ANOTHER POTENT UPPER TROUGH SWINGS ACROSS THE DEEP SOUTH. THIS WILL HELP FORM AN AREA OF LOW PRESSURE ACROSS THE SE U.S. THAT WILL MOVE NE LATE MONDAY INTO TUE. UNCERTAINTY EXISTS WITH THIS FEATURE DUE TO SLIGHT MODEL DIFFERENCES IN TIMING OF LOW DEVELOPMENT AND TRACK OF LOW. THE MODELS DO SUGGEST A MULTI-PRECIPITATION TYPE EVENT WITH AN ONSET OF WINTER PRECIP TRANSITIONING TO A MIX ON TUES. PRECIP PROGGED TO MOVE NE OFF THE COAST BY TUE NIGHT && .AVIATION /22Z TUESDAY THROUGH SUNDAY/... SFC LO PRES DEVELOPS OFF THE DELMARVA CST THIS AFTN WITH ANOTHER AREA OF LO PRES OVER THE ERN GREAT LAKES REGION. BETWEEN THESE TWO FEATURES...BKN-OVC SKIES ARE COMMONPLACE OVER THE FA WITH MAINLY VFR CONDS WITH THE EXCEPTION OF KSBY WHERE MVFR CIGS ARE CONTINUING THIS AFTN. PREVAILED -RA THERE WITH A TEMPO GROUP INCLUDED FOR A RA/SN MIX LATER THIS AFTN AS COLDER TEMPS ALOFT MAY HELP CHANGEOVER THE PCPN. ELSEWHERE...VFR CONDS EXPECTED FOR THE DURATION OF THE TAF PERIOD WITH A CHANCE OF -RA THIS AFTN AT KRIC. WINDS REMAIN WLY AVGG 8-12 KT. OUTLOOK...VFR CONDITIONS SHOULD PREVAIL WED NGT THRU FRI...AS HI PRES BLDS INTO THE MID ATLC REGION. && .MARINE... 7-9FT SEAS IN THE ATLANTIC CONTINUE THROUGH THIS EVENING BEFORE DROPPING TO 5-7FT OVERNIGHT. MODERATELY STRONG PRESSURE GRADIENT AND CONTINUAL SHOTS OF COLD AIR ALOFT WILL HELP STRENGTHEN WESTERLY FLOW OVER THE WATERS TONIGHT THROUGH THURS NIGHT. THE RESULT WILL BE PROLONGED SCA CONDITIONS ACROSS THE CHES BAY AND NC/VA/MD COASTAL WATERS. EXPECT WIND GUSTS TO AVG 25-30KT WED MORNING THROUGH THUR NIGHT OVER THE COASTAL WATER AND 20-25KT OVER THE BAY. EXPECT SEAS 3FT NEARSHORE UP TO 5/6FT 20NM OFF THE COAST WITH THE OFFSHORE FLOW. WEAK AREA OF HIGH PRESSURE SETTLES OVER THE MID-ATLANTIC BY FRI ALLOWING FOR A BRIEF PERIOD OF NON-SCA CONDITIONS. STRONG ARCTIC FRONT PROGGED TO CROSS THE WATERS SAT NIGHT. GALE CONDITIONS WILL BE POSSIBLE SAT NIGHT THROUGH SUN NIGHT AS STRONG CAA ADVECTION TAKES PLACE AND SURFACE PRESSURE GRADIENT TIGHTENS BETWEEN DEPARTING LOW TO THE NE AND BUILDING HIGH FROM THE WEST. A PERIOD OF FREEZING SPRAY WILL ALSO EXIST AS TEMPERATURES WILL QUICKLY DROP INTO THE 20S AND TEENS SUN MORNING WITH WINDS GUSTING OVER 30KT. WINDS DIMINISH QUICKLY SUN NIGHT AS SURFACE HIGH CENTERS OVER THE WATERS. && .HYDROLOGY... RIVER FLOOD WARNINGS REMAIN IN EFFECT FOR THE BLACKWATER ABOVE FRANKLIN AND NOTTOWAY AT SEBRELL. SEE FLSAKQ FOR DETAILS. && .TIDES/COASTAL FLOODING... FORECAST UPDATED TO RAISE CSTL FLOOD WARNGS FOR THE ENTIRE BAY SIDE OF THE LWR ERN SHORE AS WELL AS THE WRN SHORE OF THE BAY NR THE NRN NECK AND MIDDLESEX COUNTY TDA WHERE MODERATE FLOODING IS EXPECTED. HI SURF ADVSRYS HAVE ALL EXPIRED. PREVIOUS DISCUSSION... A HIGH SURF ADVISORY REMAINS IN EFFECT ALONG THE ENTIRE ATLC COAST THRU 8 AM THIS MORNING...AS NEARSHORE WAVES REMAIN HIGH (8-11 FT). WATER LEVELS HAVE RISEN QUITE HIGH ACRS THE BAY AS ELEVATED SEAS ARE PREVENTING WATER FROM EXITING THE BAY AND TIDAL RIVERS. IN MOST AREAS THE SURGE HAS RISEN TO 2 FT OR GREATER. THUS...COASTAL FLOOD ADVISORIES HAVE BEEN ISSUED FOR ALL ZONES ADJACENT TO THE CHES BAY (BOTH THE WESTERN AND EASTERN SHORE) AS WELL AS THE TIDAL RIVERS THROUGH THE UPCOMING HIGH TIDE CYCLE (SEE CFWAKQ FOR DETAILS ON TIMES). THE COASTAL FLOOD ADVISORIES HAVE BEEN MAINTAINED FOR THE ATLC COAST AREAS THROUGH THE UPCOMING MORNING HIGH TIDE CYLE. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...COASTAL FLOOD WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ021>023. NC...NONE. VA...COASTAL FLOOD ADVISORY UNTIL 2 AM EST WEDNESDAY FOR VAZ099-100. COASTAL FLOOD WARNING UNTIL 5 PM EST THIS AFTERNOON FOR VAZ075>078-085. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR ANZ634-650- 652-654-656-658. SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR ANZ630>633. && $$ SYNOPSIS...LKB/SAM NEAR TERM...SAM SHORT TERM...LKB/SAM/JAO LONG TERM...DAP AVIATION...MAS MARINE...DAP HYDROLOGY... TIDES/COASTAL FLOODING...

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