Area Forecast Discussion
Issued by NWS Wakefield, VA

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779 FXUS61 KAKQ 130619 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 119 AM EST SAT FEB 13 2016 .SYNOPSIS... A COLD FRONT CROSSES THE AREA EARLY THIS MORNING. ARCTIC HIGH PRESSURE BUILDS IN FOR THE UPCOMING WEEKEND...RESULTING IN THE COLDEST TEMPERATURES SO FAR THIS YEAR. LOW PRESSURE LIFTS FROM THE DEEP SOUTH INTO THE MID ATLANTIC REGION EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... PER CRNT RADAR TRENDS...ADDED SCT FLURRIES TO GRIDS NEXT SVRL HRS AS ARCTIC BNDRY PUSHES ACROSS THE RGN. NW WINDS INCREASE TO 10 TO 20 MPH WITH GUSTS 25 TO 30 MPH COASTAL AREAS AND THE ERN SHORE. DCRG CLDNS SW TO NE LATE. LOWS IN THE TEENS TO L20S. WIND CHILLS WILL DROP INTO THE SINGLE DIGITS. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... DEEP UPPER TROUGH LOCATES OVER NEW ENGLAND INTO THE MID-ATLANTIC STATES SAT AS THE ARCTIC BOUNDARY PUSHES OFFSHORE. POLAR FRONT PROGGED TO REMAIN NORTH OF THE LOCAL AREA. THE ARCTIC HIGH BUILDS INTO THE OH VALLEY LATE SAT...USHERING IN SOME OF THE COLDEST AIR OF THE SEASON. H85 TEMPS PLUMMET TO AROUND -18 TO -20C (-2 TO -3 STD DEV). HIGHS ONLY FORECAST IN THE MID/UPPER 20S INLAND TO LOW 30S SE. WINDY...WITH NORTHWEST WINDS GENERALLY 15 TO 25 MPH WITH GUSTS 30 TO 35 MPH. GUSTS OVER THE EASTERN SHORE AND COASTAL AREAS EXPECTED TO REACH 40 MPH. WHILE THE AIR MASS REMAINS VERY DRY (DEWPOINTS BELOW 0)...BAY STREAMERS AND LIGHT SNOW SHOWERS ARE POSSIBLE OVER THE ERN SHORE. WILL HOLD ONTO SLIGHT CHANCE POPS THERE. SKY AVERAGES SUNNY SOUTHWEST TO PARTLY CLOUDY NE. LARGE SCALE CONFLUENCE IN WAKE OF THE DEPARTING UPPER LOW WILL ALLOW HIGH PRESSURE TO BUILD INTO THE REGION SAT NIGHT. WINDS DIMINISH INLAND...ALLOWING FOR GREAT RADIATIONAL COOLING AND LOWS PLUNGING INTO THE SINGLE DIGITS TO LOW TEENS INLAND TO UPPER TEENS NEAR THE COAST. WIND CHILL VALUES GENERALLY 0 TO 5 ABOVE INLAND AND AROUND 5 BELOW NRN NECK TO THE ERN SHORE. WILL HOLD OFF ON WIND CHILL ADVISORY ATTM. THE ARCTIC HIGH CENTERS OVER THE MID-ATLANTIC SUN...WITH HIGHS ONLY WARMING INTO THE MID/UPPER 20S (-2 STD DEV). SKY AVERAGES MOSTLY SUNNY WITH A LIGHT NY WIND. MID/UPPER LEVEL CLOUDS BEGIN TO INCREASE LATE SUNDAY AS THE NEXT STORM SYSTEM APPROACHES. THE HIGH SHIFTS TOWARD NEW ENGLAND SUN NIGHT AS THE NEXT STORM SYSTEM DEVELOPS OVER THE DEEP SOUTH MONDAY. NRN STREAM ENERGY LIFTS NORTH OF THE REGION SUN NIGHT/MONDAY AS A MID LEVEL TROUGH TRACKS ACROSS THE CENTRAL CONUS MON. SWLY FLOW ALOFT WILL RESULT IN MOISTURE RETURN INTO THE MID-ATLANTIC REGION. POPS INCREASE LATE SUN NIGHT AS THE NRN STREAM SYSTEM WEAKENS AND WEAK ISENTROPIC LIFT ADVECTS INTO THE REGION. AIR MASS WILL EASILY BE COLD ENOUGH SUN NIGHT FOR ALL SNOW AS LOWS SUN NIGHT WILL BE IN THE UPPER TEENS TO AROUND 20. PRECIP CHANCES INCREASE MON AS A COASTAL TROUGH SHARPENS ALONG THE COAST AND THE AFOREMENTIONED DEEP SOUTH LOW BEGINS TO LIFT NEWD TOWARD THE LOCAL AREA. HAVE INCREASE POPS TO LIKELY ACROSS THE NW MONDAY MORNING...WITH LIKELY POPS ACROSS ALL BUT SE VA/NE NC MON AFTERNOON. WAA ALOFT/CRITICAL THICKNESSES STILL INDICATING A CHANGE OVER FROM SN/IP MON MORNING TO RA CLOSER TO THE COAST MON AFTERNOON. PTYPE LIKELY TO REMAIN ALL SNOW NW. THERE STILL REMAINS SOME TIMING AND SPATIAL DIFFERENCES IN THE MODELS...BUT CURRENT SNOWFALL FORECAST CALLS FOR 1-2 INCHES ALONG THE INTERSTATE 85 CORRIDOR INTO CENTRAL VA AND NRN VA...WITH 2-4 INCHES ACROSS THE NW COUNTIES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 12/12Z NUMERICAL MODELS DEPICT LOW PRESSURE TRACKING NE FROM THE DEEP SOUTH TO THE SRN APPALACHIANS MONDAY EVENING...THEN RAPIDLY DEEPENING AS IT LIFTS NE INTO THE MID-ATLANTIC REGION BY MIDDAY TUESDAY AS A VIGOROUS UPPER TROUGH DIGS ACROSS THE SRN/CENTRAL APPALACHIANS. THERMAL PROFILES SUGGEST MIXED PCPN COULD CONTINUE INTO THE EVENING OVER THE PIEDMONT. OVERNIGHT LOWS SHOULD OCCUR IN THE EVENING...WITH RISING TEMPERATURES OVERNIGHT AS THE LOW-LEVEL FLOW BECOMES SSE. COLDER TEMPERATURES WILL LIKELY PERSIST THE LONGEST IN THE FAR NW PIEDMONT COUNTIES WHERE SOME POCKETS OF -FZRA COULD CONTINUE OVERNIGHT...BUT GENERALLY ALL RAIN IS EXPECTED BY EARLY TUESDAY MORNING. PERIODS OF MODERATE RAIN ARE POSSIBLE LATE MONDAY NIGHT INTO TUESDAY AS A BAND OF STRONG VERTICAL ASCENT PASSES OVER THE REGION. STRONG PRESSURE FALLS COULD PRODUCE A MODESTLY STRONG SOUTHERLY WIND ACROSS THE ERN THIRD OF THE AREA FOR A 3-6HR PERIOD TUESDAY. TEMPERATURES WARM TO AT LEAST THE MID/UPPER 50S ACROSS THE ERN HALF OF THE AREA TUESDAY...WITH LOW 60S POSSIBLE ALONG THE COAST...WHILE THE PIEDMONT STRUGGLES TO RISE ABOVE THE UPPER 40S/LOW 50S. GENERALLY EXPECTING DRIER CONDITIONS BY TUESDAY NIGHT...ALTHOUGH SOME 20-30% POPS WILL LINGER ACROSS THE N AS A SECONDARY TROUGH SWINGS ACROSS THE NRN MID-ATLANTIC. DRY AND MILD WEDNESDAY UNDER WNW FLOW WITH HIGHS IN THE UPPER 40S TO MID 50S. A COLD FRONT TRACKS ACROSS THE AREA WEDNESDAY NIGHT...FOLLOWED BY CANADIAN HIGH PRESSURE THURSDAY. THIS SHOULD PUSH TEMPERATURES BELOW NORMAL...BUT WITHIN -1 ST DEV. A MODERATING TREND COMMENCES LATE WEEK AS HIGH PRESSURE MOVES OFFSHORE AND LOW PRESSURE TRACKS THROUGH THE GREAT LAKES. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... PLENTY OF CLOUDINESS ACROSS THE AREA AS LOW PRESSURE MOVES WELL OFFSHORE AND THE BASE OF AN UPPER TROUGH SWINGS ACROSS THE REGION. MODIFIED ARCTIC HIGH PRESSURE BUILDS INTO THE MIDWEST THE REST OF TONIGHT INTO SATURDAY WITH A MUCH COLDER AIRMASS FILTERING INTO THE MID ATLANTIC REGION DURING THIS TIME. TEMPERATURE AND PRESSURE GRADIENTS WILL RESULT IN NW WINDS BECOMING BREEZY FROM NW TO SE THE REST OF TONIGHT...BECOMING GUSTY AFTER 13/1100Z AND CONTINUING THROUGH THE REST OF SATURDAY. INLAND WINDS AVERAGING 15KT WITH GUSTS UP TO 20-25KT...ALONG THE COAST WINDS WILL AVERAGE 20-25KT WITH GUSTS UP TO 30-35KT. SKIES REMAIN MOSTLY CLOUDY AND THEN START TO BREAK UP AROUND SUNSET. SFC HIGH FINALLY BUILDS INTO THE REGION BY SUN MORNING...HOWEVER NW WINDS WILL BE SLOW TO DIMINISH OVERNIGHT (ESPECIALLY ALONG THE IMMEDIATE COAST) DUE TO A VERY GRADUAL RELAXING OF THE TEMP/PRESSURE GRADIENT. HIGH PRESSURE DOMINATES ON SUNDAY WITH DRY WX...GENERALLY LIGHT WINDS...AND VFR CONDITIONS. NEXT COMPLEX WEATHER SYSTEM BEGINS TO IMPACT THE AREA LATE SUNDAY NIGHT. PLENTY OF COLD AIR IN PLACE FOR PRECIP TO BEGIN AS ALL SNOW SUNDAY NIGHT INTO MONDAY MORNING. HOWEVER...A DEEPENING LOW MOVING IN FROM THE SW IS EXPECTED TO PULL WARMER AIR INTO THE REGION. THIS WILL COMPLICATE PRECIP FORECAST...ESPECIALLY ACROSS CNTRL VA WHERE COLDER AIR MAY LINGER AT THE SFC. COULD SEE A WINTRY MIX NORTHWEST HALF OF FA AND A CHANGEOVER TO ALL RAIN ACROSS THE SOUTHEAST. REGARDLESS OF PRECIP TYPE...EXPECT CIG/VIS REDUCTIONS ONCE PRECIP BEGINS SUNDAY NIGHT AND CONTINUING INTO TUESDAY. A BREAK IN PRECIP AND FLIGHT RESTRICTIONS IS ANTICIPATED TUESDAY NIGHT BUT COULD BE SHORT- LIVED. ANOTHER WEATHER DISTURBANCE MAY BRUSH ACROSS NRN VA AND THE MD LOWER EASTERN SHORE WEDNESDAY MORNING BUT IMPACTS ARE NOT ANTICIPATED AT LOCAL TAF SITES AT THE MOMENT. && .MARINE... 10 PM UPDATE...BEGAN MARINE HEADLINES WITH 10 PM ISSUANCE. SCA CONDITIONS TO BEGIN ACROSS NRN WATERS IN THE BALLPARK OF 400 AM... WITH WINDS INCREASING RAPIDLY TO GALE FORCE GUSTS FROM NORTH TO SOUTH AROUND SUNRISE. PREVIOUS DISCUSSION... LOW PRESSURE IS TRACKING ENE OFF THE NC COAST THIS AFTERNOON. MEANWHILE...ANOTHER AREA OF LOW PRESSURE IS TRACKING ACROSS THE ERN LAKES...WITH AN ARCTIC COLD FRONT TRAILING THROUGH THE OHIO VALLEY...AND ARCTIC HIGH PRESSURE SPILLING INTO THE UPPER MIDWEST. THE COASTAL LOW WILL BRING A PERIOD OF SN...WHICH WILL REDUCE VSBY LATE THIS AFTERNOON AND EVENING (MAINLY S). AS THE LOW LIFTS TO THE NE TONIGHT THE ARCTIC COLD FRONT WILL PASS ACROSS THE REGION WITH STRONG CAA DEVELOPING LATE TONIGHT...AND CONTINUING THROUGH SATURDAY INTO SATURDAY NIGHT AS THE ARCTIC HIGH 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 CONTINUE FOR LATE TONIGHT THROUGH SATURDAY NIGHT. FOR THE RIVERS AND SOUND...WIND SPEEDS REMAIN CAPPED AT HIGH-END SCA AT THIS TIME. FREEZING SPRAY IS EXPECTED AS TEMPERATURES PLUMMET SATURDAY AND ESPECIALLY SATURDAY NIGHT/SUNDAY MORNING...WITH A FREEZING SPRAY ADVISORY IN EFFECT FOR SATURDAY NIGHT INTO SUNDAY MORNING. THE WIND WILL DIMINISH SUNDAY INTO SUNDAY NIGHT AS THE HIGH SETTLES ACROSS THE AREA. LOW PRESSURE APPROACHES FORM THE SW EARLY NEXT WEEK...AND TRACKS UP THE PIEDMONT TUESDAY. THIS WILL ALLOW FOR A MODESTLY STRONG SSE WIND AND BUILDING SEAS/WAVES. && .TIDES/COASTAL FLOODING... STRONG NW FLOW ASSOCIATED WITH AN ARCTIC COLD FRONT WILL PRODUCE BLOW-OUT TIDES / LOW WATER ADVISORIES FOR SOME AREAS EARLY SATURDAY MORNING...AND MUCH OF THE COASTLINES SATURDAY AFTERNOON AND NIGHT. THE MAIN AREAS EARLY SATURDAY MORNING THAT COULD HAVE LOW WATER ARE ALONG THE ATLANTIC COAST N OF CAPE CHARLES. A LOW WATER ADVISORY HAS BEEN ISSUED FROM 08-13Z (3 TO 8 AM). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR ANZ633-635>638. FREEZING SPRAY ADVISORY FROM 7 AM THIS MORNING TO NOON EST SUNDAY FOR ANZ630>632-634-650-652-654-656. GALE WARNING UNTIL 4 AM EST SUNDAY FOR ANZ630>632-634-650-652- 654-656-658. LOW WATER ADVISORY UNTIL 8 AM EST THIS MORNING FOR ANZ650-652- 654. FREEZING SPRAY ADVISORY FROM 7 PM THIS EVENING TO NOON EST SUNDAY FOR ANZ658. && $$ SYNOPSIS...SAM NEAR TERM...MAS/MPR/SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...BMD MARINE...AJZ TIDES/COASTAL FLOODING...AKQ

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