Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 120511 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1211 AM EST FRI FEB 12 2016 .SYNOPSIS... HIGH PRESSURE BUILDS OVER THE AREA TONIGHT. WEAK LOW PRESSURE DEVELOPS ALONG THE SOUTHEAST COAST FRIDAY MORNING...LIFTING NORTHEAST OFF THE NORTH CAROLINA AND VIRGINIA COASTS FRIDAY AFTERNOON AND EVENING. ARCTIC HIGH PRESSURE BUILDS IN FOR THE UPCOMING WEEKEND...RESULTING IN THE COLDEST TEMPERATURES SO FAR THIS YEAR. ANOTHER STORM SYSTEM WILL IMPACT THE REGION EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FORECAST REMAINS ON TRACK TNGT WITH DRY CONDS...SOME INCREASING CLOUDS LATE...AND LO TEMPS MAINLY IN THE UPR TEENS TO LWR 20S. PREVIOUS DISCUSSION... LATEST SFC ANALYSIS CENTERS ~1030MB HIGH PRESSURE OVER THE OH VALLEY. A STATIONARY BOUNDARY REMAINS OVER THE GULF STATES. COLD THIS AFTERNOON...WITH TEMPS GENERALLY IN THE LOW TO MID 30S. WIND CHILLS IN THE 20S UNDER A SUNNY SKY. FOR TONIGHT...HIGH PRESSURE SETTLES OVER THE REGION. WINDS DECOUPLE ALLOWING FOR EXCEPTIONAL RADIATIONAL COOLING THIS EVENING AS DEWPOINTS REMAIN IN THE SINGLE DIGITS. MID-LEVEL CLOUDS INCREASE LATE TONIGHT AS ATTENTION TURNS TO SHORTWAVE ENERGY DIGGING INTO THE DEEP SOUTH. HEIGHT FALLS WILL INDUCE CYCLOGENESIS OFF THE SC/NC COAST BY LATE TONIGHT/EARLY FRIDAY MORNING. TEMPS WILL LEVEL OFF THRU LATE TONIGHT WITH LOWS GENERALLY IN THE MID/UPPER TEENS TO LOW 20S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... LOW PRESSURE DEEPENS OFF THE NC COAST FRI MORNING AS THE SHORTWAVE ENERGY PUSHES OVER THE CAROLINAS. SHORTWAVE AND INCREASING WINDS ALOFT WILL PROVIDE ADEQUATE UVM OVER AN AREA OF 280-285K ISENTROPIC LIFT ON THE NW PERIPHERY OF THE LOW. MOISTURE ADVECTION WILL BE MODEST...BUT MIXING RATIOS PROGGED TO REACH 3.0 TO 4.0 G/KG. THERMAL PROFILES INDICATE HIGH RH/ICE IN THE SNOW GROWTH LAYER ALONG WITH ABUNDANT LIFT DUE TO AFOREMENTIONED UPPER LEVEL DYNAMICS. THE NET RESULT WILL BE INCREASING POPS THRU MID TO LATE MORNING FRI AS SNOW SPREADS INTO THE REGION. PRECIP CONTINUES THRU THE AFTERNOON AS THE LOW LIFTS OFF THE MID-ATLANTIC COAST. QUESTION BECOMES HOW FAR NW THE PRECIP SPREADS FRI AFTERNOON. HAVE INCREASED POPS ACROSS THE SE COUNTIES TO CATEGORICAL...TAPERING OFF THE CHANCE OVER THE NW COUNTIES. WITH THE LUXURY OF COLD CRITICAL THICKNESS VALUES...SNOW IS EXPECTED TO BE THE PREDOMINATE PTYPE THRU THE DURATION OF THE EVENT. THE EXCEPTION MAY BE LATE FRIDAY NEAREST THE ALBEMARLE SOUND WHERE A LITTLE SLEET MAY MIX WITH THE SNOW TOWARD THE END OF THE EVENT. HIGHEST AMOUNTS EXPECTED ACROSS NORTHEAST NORTH CAROLINA WHERE BANDING FROM FRONTOGENETIC FORCING ON THE NW PERIPHERY OF THE LOW IS INDICATED IN THE MODELS. 2-4 INCHES IS EXPECTED IN THAT AREA...REQUIRING A WINTER STORM WARNING. FARTHER NORTH AND WEST INTO HAMPTON ROADS AND THE LOWER PENINSULA AND EASTERN SHORE...SNOWFALL AMOUNTS WILL TAPER OFF TO 1 TO 3 INCHES...WITH WINTER WEATHER ADVISORIES IN EFFECT. PLEASE SEE LATEST WSW FOR MORE INFO. SNOWFALL AMOUNTS TAPER OFF TO 0.5 TO 1.0 INCH TOWARD THE TRI CITIES AND MD ERN SHORE...THEN A DUSTING TO HALF AN INCH RICHMOND NORTH AND WEST. SNOW COMES TO AN END FRI EVENING AS THE SFC LOW PUSHES WELL OFF THE MID-ATLANTIC COAST AND THE ARCTIC BOUNDARY PUSHES THRU THE REGION. CLOSED UPPER LOW/ENERGY ASSOCIATED WITH THE POLAR VORTEX DIGS OVER NEW ENGLAND SATURDAY. ~1040MB ARCTIC HIGH PRESSURE BUILDS OVER THE MIDWEST...USHERING IN THE COLDEST AIR MASS OF THE SEASON FOR THE UPCOMING WEEKEND. WINDY SAT WITH NW WINDS GENERALLY 15 TO 25 MPH WITH GUSTS OF 30 TO 40 MPH (STRONGER NEAR THE COAST AND OVER THE EASTERN SHORE). HIGHS SAT FORECAST TO WARM ONLY INTO THE MID 20S NW TO LOW 30S SE (-2 STD DEV) UNDER A SUNNY TO MOSTLY SUNNY SKY. WIND CHILL VALUES WILL BE IN THE TEENS...RESULTING IN A RAW/COLD/WINDY DAY. TEMPS PLUMMET INTO THE SINGLE DIGITS TO LOW TEENS SAT NIGHT. WINDS DECOUPLE INLAND AS THE HIGH BUILDS INTO THE REGION...BUT WIND CHILLS STILL FORECAST IN THE SINGLE DIGITS INLAND TO 0 TO 8 BELOW NRN NECK TO THE ERN SHORE. THE HIGH CENTERS OVER THE LOCAL AREA SUNDAY WITH NLY WINDS 5 TO 10 MPH. SLIGHTLY COLDER SUN WITH DECREASED MIXING. HIGHS GENERALLY IN THE MID/UPPER 20S (-2 STD DEV) UNDER A SUNNY TO MOSTLY SUNNY SKY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... HIGH PRESSURE SHIFTS TOWARD NEW ENGLAND SUNDAY NIGHT WITH ATTENTION TURNING TO A DEVELOPING SYSTEM OVER THE DEEP SOUTH MONDAY. THERE REMAINS PLENTY OF UNCERTAINTY WITH RESPECT TO THE DETAILS...ALTHOUGH THE 11/12Z NUMERICAL GUIDANCE IS TRENDING SLOWER...AND WARMER FOR MONDAY NIGHT AND ESPECIALLY TUESDAY. THE 11/12Z GFS CONTINUES TO SHOW SOME LIGHT PCPN MONDAY AS A NRN STREAM TROUGH SWINGS ACROSS THE AREA. THIS WOULD MAINLY FALL AS SN OR SN/IP...WITH A TRANSITION TO RA CLOSER TO THE COAST BY AFTERNOON. SUBSTANTIAL WARMING ALOFT WOULD GENERALLY RESULT IN A TRANSITION TO RA MONDAY NIGHT...ASIDE FROM THE FAR NW WHERE MIXED PCPN COULD PERSIST INTO TUESDAY MORNING WITH AN IN-SITU WEDGE IN PLACE. THE LATEST DATA SCOURS OUT THE WEDGE BY AFTERNOON WITH P-TYPE BECOMING RA EVEN IN THE FAR NW. DRYING OCCURS MIDWEEK IN THE WAKE OF THE DEPARTING SYSTEM...WITH A NRN STREAM WAVE CLIPPING THE AREA LATE IN THE PERIOD. THIS WILL BRING ANOTHER SHOT OF COOLER AIR AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA THURSDAY/THURSDAY NIGHT. HIGHS MONDAY WILL LIKELY STRUGGLE TO GET OUT OF THE LOW 30S ALONG AND W OF I-95...WHILE COASTAL LOCATIONS WARM INTO THE UPPER 30S TO LOW 40S. TEMPERATURES REMAIN STEADY MONDAY EVENING AND BEGIN TO RISE OVERNIGHT EVENTUALLY WARMING INTO THE 40S TO LOW 50S TUESDAY. HIGHS WEDNESDAY ARE FORECAST TO REACH THE MID 40S TO LOW 50S...FOLLOWED BY LOW 40S NE...TO UPPER 40S SW THURSDAY. MORNING LOWS ARE FORECAST TO BE IN THE UPPER 20S TO MID 30S WEDNESDAY MORNING. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR CNDTNS ALL AREAS THRU AT LEAST 15Z AS HIGH/MID LVL CLDS OVRSPRD THE RGN. SNOW FROM APPRCHG LOW PRS TO THE SW OVRSPRDS THE SERN TAF SITES ARND 18Z. VSBY XPCTD TO DROP TO 1/2SM FOR A 2-4 HR PRD (20-00Z) AT ECG ORF AND PHF PER LTST MODEL GUID. THIS WUD BE THE TIME FRAME FOR SNOW ACCUMLS. ADDED SOME IP AT ECG AS PCPN COMES TO AN END ARND 00Z DUE TO MARINE INFLUENCES. CUD EVEN SEE SOME PL MIXING IN AT ORF...BUT THNK SNOW WILL BE THE MAIN PCPN TYPE THERE. SBY LOOKS TO GET SOME SNOW BTWN 22-02Z AS WELL BUT DID NOT GO AS LOW WITH THE VSBY THERE AS LESS THAN ONE INCH OF SNOW IS EXPECTED. LOW DP TMPS AND DRY AIRMASS OVR THE PIEDMONT SHUD PREVENT ANYTHING MORE THAN SCT FLURRIES AT RIC. OUTLOOK...GUSTY NW WINDS DEVELOP FRIDAY EVENING AND CONTINUE INTO SATURDAY. VFR AND DRY WEATHER WILL PREVAIL THROUGH SUNDAY NIGHT. PCPN DEVELOPS MONDAY AS THE NEXT WEATHER SYSTEM APPROACHES FROM THE SW. PCPN BEGINS AS SNOW UNDER A HIGH PRESSURE RIDGE BUT THIS BREAKS DOWN AND WARMER AIR WORKS IN AND CHANGES SNOW TO RAIN FROM SE TO NW. RAIN CONTINUES INTO TUESDAY AS LOW PRESSURE MOVES ACROSS THE AREA. DRY WEATHER RETURNS WEDNESDAY. && .MARINE... HIGH PRESSURE BUILDS IN FORM THE NW TONIGHT AND SETTLES OVER THE MID ATLANTIC COAST FRIDAY MORNING. THE WIND WILL DIMINISH AND SEAS WILL SUBSIDE THIS EVENING...WITH SCA HEADLINES GRADUALLY ENDING THROUGH THE EVENING. HIGH PRESSURE LIFTS TO THE NE FRIDAY WITH A LOW PRESSURE SYSTEM TRACKING OFF THE SOUTHEAST COAST FRIDAY AFTERNOON AND EVENING. BY AFTERNOON THE WIND WILL BECOME E/NE S OF CAPE CHARLES WITH GENERALLY A S/SE DIRECTION N OF CAPE CHARLES. SPEEDS WILL BE AOB 15KT. ADDITIONALLY...THIS LOW WILL BRING A PERIOD OF SN...WHICH WILL REDUCE VSBY. AS THE LOW LIFTS TO THE NE FRIDAY NIGHT A STRONG ARCTIC COLD FRONT WILL PASS ACROSS THE REGION WITH STRONG CAA DEVELOPING LATE FRIDAY NIGHT AND CONTINUING THROUGH SATURDAY INTO SATURDAY NIGHT AS ARCTIC HIGH PRESSURE BUILDS IN FROM THE NW. A NW WIND WILL AVERAGE 25-30KT WITH FREQUENT GUSTS OF 35-40KT OVER THE OCEAN AND BAY. SEAS BUILD TO 5- 8FT WITH 4-5 FT WAVES IN THE BAY. GALE FLAGS HAVE BEEN RAISED FOR LATE FRIDAY NIGHT INTO SATURDAY (4TH PERIOD). THESE WILL LIKELY NEED TO BE EXTENDED INTO SATURDAY NIGHT...ESPECIALLY ACROSS THE NRN OCEAN ZONES. FOR THE RIVERS AND SOUND...WIND SPEEDS HAVE BEEN CAPPED AT HIGH-END SCA AT THIS TIME. FREEZING SPRAY IS LIKELY AS TEMPERATURES PLUMMET SATURDAY AND ESPECIALLY SATURDAY NIGHT. THE WIND WILL DIMINISH SUNDAY INTO SUNDAY NIGHT AS THE HIGH SETTLES ACROSS THE AREA. LOW PRESSURE APPROACHES FORM THE SW EARLY NEXT WEEK. && .TIDES/COASTAL FLOODING... STRONG NW FLOW ASSOCIATED WITH AN ARCTIC COLD FRONT COULD PRODUCE BLOW-OUT TIDES SATURDAY AFTERNOON INTO SATURDAY NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...WINTER WEATHER ADVISORY FROM 7 AM FRIDAY TO MIDNIGHT EST FRIDAY NIGHT FOR NCZ012>014. WINTER STORM WARNING FROM 7 AM FRIDAY TO MIDNIGHT EST FRIDAY NIGHT FOR NCZ015>017-030>032-102. VA...WINTER WEATHER ADVISORY FROM 7 AM FRIDAY TO MIDNIGHT EST FRIDAY NIGHT FOR VAZ092-093-095>098-100-523>525. MARINE...GALE WARNING FROM 4 AM TO 7 PM EST SATURDAY FOR ANZ630>632-634- 650-652-654-656-658. SMALL CRAFT ADVISORY FROM 4 AM TO 7 PM EST SATURDAY FOR ANZ633- 635>638. && $$ SYNOPSIS...SAM/TMG NEAR TERM...MAS/SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...MPR/LSA MARINE...AJZ TIDES/COASTAL FLOODING...AKQ

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