Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 301747 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 147 PM EDT MON MAR 30 2015 .SYNOPSIS... A WEAK FRONTAL BOUNDARY CROSSES THE REGION THIS MORNING...WITH HIGH PRESSURE RETURNING THIS AFTERNOON INTO TONIGHT. LOW PRESSURE TRACKS ACROSS THE NORTHERN MID ATLANTIC TUESDAY WITH THE ASSOCIATED COLD FRONT DROPPING THROUGH THE REGION TUESDAY NIGHT. CANADIAN HIGH PRESSURE BUILDS INTO THE REGION WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...LIGHT RAIN SHOWERS HAVE BECOME FOCUSED ALONG THE MD/VA EASTERN SHORE AND DOWN INTO FAR SE VA AND ALL OF NE NC LATE THIS MORNING. RADAR ECHOES APPEAR MUCH WORSE THAN IS HAPPENING AT THE SFC...WITH ONLY VERY LIGHT QPF AMTS OF 0.02 INCHES OR LESS OCCURRING. SFC COLD FRONT IS NOW DRAPED ACROSS CNTRL VA WHERE SOME BREAKS IN THE CLOUD COVER CAN BE SEEN IN VISIBLE SATELLITE IMAGERY. BEHIND THE FRONT...SW WINDS WILL VEER AROUND TO W-NW DURING THE AFTN AND ADDITIONAL CLEARING WILL OCCUR AS DRIER AIR ALOFT MOVES INTO THE REGION. COOLED HIGHS BY A FEW DEGREES...ESPECIALLY CLOSER TO THE COAST DUE TO EVAPORATIVE COOLING FROM PRECIP AND DELAYED CLEARING THIS AFTN. LOWER 60S WEST TO MID-UPPER 50S ALONG THE COAST. PREVIOUS DISCUSSION...CURRENT GOES WV IMAGERY SHOWS A MID-LEVEL TROUGH LIFTING NE OF THE GREAT LAKES REGION...WITH A MID-LEVEL FRONTAL BOUNDARY TRAILING BACK THROUGH THE OHIO VALLEY. AT THE SURFACE...LOW PRESSURE IS CENTERED N OF THE GREAT LAKES...WITH HIGH PRESSURE OFF THE SOUTHEAST COAST. THE SURFACE BOUNDARY (ASSOCIATED WITH THE COLD FRONT ALOFT) CONSISTS MAINLY OF A WIND SHIFT FROM SW TO WNW. LOCALLY...THE AIRMASS REMAINS RATHER DRY WITH DEWPOINTS RANGING FROM THE UPPER TEENS TO LOW 20S...WITH TEMPERATURES IN THE UPPER 30S TO MID 40S. THE INITIAL BAND OF RADAR ECHOES THAT HAVE PASSED ACROSS THE REGION HAVE AT MOST PRODUCED A BRIEF PERIOD OF -IP ACROSS THE FAR NRN TIER COUNTIES. THE NEXT BATCH IS PASSING ACROSS THE CENTRAL APPALACHIANS. THIS WILL PRODUCE ISO/SCT -SHRA OVER THE NW HALF OF THE AREA THROUGH MID-MORNING. THE SURFACE AIRMASS WILL REMAIN DRY THROUGHOUT SO EXPECT VERY LITTLE MEASURABLE QPE. THE BOUNDARY IS EXPECTED TO ENCOUNTER SOMEWHAT BETTER MOISTURE OVER SE VA/NE NC LATER THIS MORNING...SO A PERIOD OF LIKELY -SHRA HAS BEEN MAINTAINED. STILL EVENTUAL QPE AMOUNTS ARE EXPECTED TO AVERAGE ~0.1IN OR LESS. OTHERWISE...MOSTLY CLOUDY TO OVERCAST CONDITIONS THIS MORNING SHOULD BECOME PARTLY TO MOSTLY SUNNY BY AFTERNOON...WITH THE CLEARING TREND PROGRESSING NW-SE. FAVORABLE DOWNSLOPE FLOW (A WNW WIND OF 10-15MPH WITH GUSTS TO AROUND 20MPH) SHOULD PUSH HIGHS INTO THE LOW/MID 60S OVER INTERIOR VA/NE NC. FARTHER E...HIGHS SHOULD BE IN THE MID/UPPER 50S WHERE CLOUD COVER WILL PERSIST THROUGH EARLY AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST STATES TONIGHT AS LOW PRESSURE MOVES INTO THE GREAT LAKES. A CLEAR AND SEASONABLY COOL NIGHT IS EXPECTED WITH LOWS RANGING FROM THE UPPER 30S TO LOW 40S. THE AFOREMENTIONED LOW PRESSURE SYSTEM DRIVEN BY ZONAL FLOW ALOFT QUICKLY TRACKS ACROSS THE NRN MID ATLANTIC TUESDAY AFTERNOON. EXPECT MOSTLY SUNNY CONDITIONS TO BEGIN THE DAY WITH INCREASING CLOUDS ACROSS THE N BY AFTERNOON. A RIBBON OF 20-30% POPS (FOR -SHRA) HAS BEEN MAINTAINED PRIMARILY FOR THE NRN INTERIOR VA COUNTIES AND THE MD LOWER EASTERN SHORE DURING THE AFTERNOON/EVENING HOURS. IT WILL BE DIFFICULT TO GET ANY PCPN S OF THE LOW TRACK WITH DEEP LAYERED WSW FLOW. LOW-LEVEL THICKNESS VALUES CONTINUE TO SUPPORT HIGHS AROUND 70F ON TUESDAY OVER INTERIOR VA/NE NC. THIS IS CERTAINLY POSSIBLE WITH LOW PRESSURE TRACKING N OF THE REGION RESULTING IN DEEP LAYERED WSW FLOW. FORECAST HIGHS REMAIN IN THE UPPER 60S TO LOW 70S ACROSS MUCH OF THE AREA...WITH MID 60S OVER THE INTERIOR ERN SHORE...AND LOCALLY COOLER VALUES ALONG THE IMMEDIATE ATLANTIC COAST. LOW PRESSURE EXITS THE DELMARVA AFTER MIDNIGHT TUESDAY NIGHT. COOLER CONDITIONS ARE EXPECTED WEDNESDAY UNDER A SUNNY SKY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. HIGHS ARE FORECAST TO RANGE FROM THE LOW 50S ALONG THE COAST...TO THE UPPER 50S/LOW 60S OVER INTERIOR VA/NE NC...AFTER MORNING LOWS IN THE UPPER 30S N...TO MID 40S S. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... SPLIT FLOW CONTINUES TO BE PROBLEMATIC DURING THE EXTENDED PERIOD...BUT MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH A LATE WEEK FRONTAL PASSAGE. TO BEGIN THE EXTENDED...HIGH PRESSURE PRESSURE SLIDES OFFSHORE WEDS NIGHT. INCREASING SLY FLOW ON THE BACK SIDE OF THE DEPARTING HIGH AND A FLATTENING SRN STREAM WAVE WILL PUSH A WARM FRONT THRU THE LOCAL AREA THURS. RESULTANT WAA WILL PUSH TEMPS INTO THE LOW 70S INLAND AND LOW-UPPER 60S ERN SHORE AND COASTAL AREAS. MODEL CONSENSUS IS TO KEEP THURS FRONTAL PASSAGE DRY THANKS TO LIMITED MOISTURE AND A LACK OF APPRECIABLE FORCING. HAVE REMOVED SLIGHT CHANCE POPS OVER THE PIEDMONT THURS. POTENT NRN STREAM WAVE LOCATES OVER THE GREAT LAKES REGION THURS NIGHT-FRI PUSHING AN ASSOCIATED/DEEPENING SFC LOW INTO SE CANADA. ATTENDANT COLD FRONT PROGGED TO REACH THE CNTRL APPALACHIANS DURING THE LATE THURS-FRI TIMEFRAME. GFS CONTINUES TO BE LESS AMPLIFIED WITH THE NRN STREAM SYSTEM...PUSHING THE FRONT THRU THE REGION AROUND 12 HR QUICKER THAN THE MORE AMPLIFIED/SLOWER ECMWF. REGARDLESS OF SPATIAL AND TIMING DIFFERENCES...EXPECT INCREASING CHANCES FOR PRECIP BEGINNING THURS NIGHT AND CONTINUING THRU SAT. 28/12Z ECMWF PUSHES THE PRECIP OFFSHORE FRI NIGHT...BUT THE GFS STALLS THE FRONT OVER THE REGION THROUGH SAT. HAVE MAINTAINED SLIGHT CHANCE TO LOW END CHANCE POPS SAT TO ACCOUNT FOR UNCERTAINTY. MILD TEMPS EXPECTED THURS NIGHT BEHIND THE WARM FRONT...WITH TEMPS GENERALLY IN THE LOW- MID 50S. WARM SECTOR/SWLY FLOW PUSHES TEMPS INTO THE MID 70S INLAND (POSSIBLY WARMER DEPENDING ON CLOUD COVER) AND UPPER 60S-LOW 70S ERN SHORE AND COASTAL AREAS. COOLER SAT WITH HIGHS MID 60S INLAND AND UPPER 50S-LOW 60S ERN SHORE AND COASTAL AREAS. HIGH PRESSURE PROGGED TO BUILD OVER THE SE STATES SAT NIGHT-SUN...WITH DECREASING CHANCES FOR PRECIP. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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AN AREA OF -RA WILL PUSH EAST OF KECG BY 19Z. OTW...EXPECTING VFR CONDITIONS THRU THE 18Z TAF PERIOD. GUSTY SW TO WEST WINDS ARE EXPECTED TIL AROUND 22-23Z BEFORE DIMINISHING. HIGH PRESSURE BREIFLY BUILDS BACK INTO THE AREA TUE BEFORE A COLD FRONT MOVES THROUGH THE AREA TUE NIGHT. AHEAD OF THIS FRONT... GUSTY SW WINDS ARE EXPECTED TUE AFTN. A BRIEF -SHRA CANNOT BE RULED OUT AT KSBY TUE EVE. DRY WX AND VFR CONDITIONS THEN EXPECTED WED AND THU. GUSTY SW WINDS MAY AGAIN BE POSSIBLE THU AFTN.
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&& .MARINE... LATEST SFC ANALYSIS REVEALS SFC HI PRES CENTERED OFF THE SE CST WITH A COLD FRNT PUSHING EWD THRU THE OH VALLEY. BETWEEN THESE TWO FEATURES...A PREFRNTAL SLY SURGE IS NOW BEGINNING OVER THE LOCAL WTRS. TRICKY CALL REGARDING SCA HEADLINES...BUT LOOKING AT CURRENT WINDS AND EXPECTED SLIGHT INCREASE THRU THE FIRST HALF OF THE DAY TO FREQUENT GUSTS ~20 KT...HOISTED A SCA FOR THE BAY AND LWR JAMES. A SCA HAS ALSO BEEN ISSUED FOR THE NRN CSTL WTRS DUE TO SEAS OUT 20 NM CLOSE TO 5 FT AND GUSTS UP TO ~25 KT. ONLY MARGINAL SCA CONDS EXPECTED DUE TO WEAK WAA OVER COLD WATER PREVENTING THE HIGHEST WINDS FM MIXING DOWN TO THE SFC. THE COLD FRNT CROSSES THE WTRS THIS AFTN/EVENG...WITH SUB-SCA CONDS ANTICIPATED POST FRONTAL TONIGHT DUE TO WEAK GRADIENT WINDS AND LIMITED CAA. HIGH PRESSURE BRIEFLY BUILDS OVER THE WATERS LATE TONIGHT-TUES MORNING WITH THE FLOW SWITCHING FROM THE NW BACK TO THE SW TUES. LOW PRESSURE AND AN ATTENDANT COLD FRONT APPROACH THE WATERS TUES...CROSSING THE REGION TUES NIGHT. SCA CONDITIONS ARE POSSIBLE POST FRONTAL TUES NIGHT-WEDS MORNING. BUT AGAIN IT WOULD BE MARGINAL. HIGH PRESSURE RETURNS TO THE AREA WEDS- THURS...RESULTING IN SUB-SCA CONDITIONS. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR ANZ632- 634-638-650.
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&& $$ SYNOPSIS...AJZ/BMD NEAR TERM...AJZ/BMD SHORT TERM...AJZ/BMD LONG TERM...SAM AVIATION...JDM MARINE...MAS

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