Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 280144 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 944 PM EDT FRI MAR 27 2015 .SYNOPSIS... A TROF OF LOW PRESSURE PUSHES ACROSS THE AREA THROUGH SATURDAY MORNING. HIGH PRESSURE RETURNS SATURDAY AFTERNOON THROUGH SUNDAY. A WEAK COLD FRONT WILL MOVE ACROSS THE REGION SUNDAY NIGHT INTO EARLY MONDAY...WITH HIGH PRESSURE RETURNING MONDAY AFTERNOON. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... PCPN SLOWLY MOVG OFFSHORE LATE THIS EVEN AS LOW PRESSURE SLOWLY MOVES EAST. THUS...CHC POPS (RAIN) CONTS LATE THIS EVENING AND ERLY MORNING WITH HIGHEST POPS ALONG THE COAST. PCPN FROM APPRCHG TROF SPREADING ACROSS THE PIEDMONT CNTYS LATE THIS EVE. PCPN STILL LIQUID IN FORM AS TMPS/DP TMPS REMAIN ABOVE FREEZING. HOWEVER...COLDER AIR OVERSPREADS THE FA AFTR MIDNIGHT ALLOWING THE RAIN TO BECOME MIXED WITH OR CHANGE TO SNOW SHWRS OR FLRYS. COULD ALSO SEE SOME SLEET MIXED IN DURING THE CHANGEOVER BUT LIMITED GRIDS TO ONLY 2 P-TYPES FOR NOW. THE CHANGEOVER OCCURS OVR THE PIEDMONT FIRST THEN TOWARDS THE CHES BAY AND COASTAL AREAS AFTR 09Z. ANY QFP AFTR MIDNIGHT WILL BE LIGHT SO NO IMPACT ISSUES ARE EXPECTED LATE TONIGHT. LOWS NR 30F NW TO THE M/U30S SE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... THE UPR TROUGH MOVES DIRECTLY OVERHEAD ON SAT...THEN OFFSHORE BY SUN MRNG. HIGHS ON SAT ARE ONLY EXPECTED TO REACH INTO THE M/U40S. IF THERE ARE ANY LINGERING SHWRS IN THE MORNING...THERE COULD STILL BE A MIX OF RAIN AND SNOW. AFTN INSTABILITY W/ THE TROUGH OVERHEAD WILL LIKELY RESULT IN WIDESPREAD CUMULUS WHICH MAY RESULT IN ISOLATED SHWRS THAT SHOULD STAY CONFINED ALONG THE COAST. ALL SHWRS FINALLY COME TO AN END EARLY SAT EVE...THE SKY CLRS...AND TEMPS PLUMMET INTO THE 20S BY SUN MRNG. SFC HIGH PRES MOVES ACRS THE RGN ON SUN. XPCG SUNNY/DRY/COOL WX W/ LGT WINDS. LIMITED MIXING WILL KEEP TEMPERATURES IN CHECK WITH READINGS ONLY RISING INTO THE M/U40S ALONG THE CST TO THE L/M50S ACRS INTERIOR VA AND NE NC. NEXT TROUGH ALOFT AND ACCOMPANYING SFC CDFNT TO CROSS THE RGN LT SUN NGT/MON MRNG...W/ VRB CLDS AND LO PROB FOR PCPN (15-30%). XPCG MORE OF A DP LYRD WSW LO LVL FLO ON MON LEADING TO BETTER WARMING. SKY AVGG OUT PSNY ON MON...W/ HI TEMPS FM THE L/M60S E...TO THE L70S W. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... SPLIT FLOW PATTERN PREVAILS THRU THE EXTENDED...AS NRN STREAM EXPECTED TO REMAIN ACTIVE. THE FIRST NRN STREAM SHORTWAVE EXITS THE COAST LATE MON NIGHT...WITH ANOTHER SHORTWAVE REACHING THE OH VALLEY LATE TUES. ASSOCIATED LOW PRESSURE EXPECTED TO LIFT ACROSS NEW ENGLAND TUES AS HIGH PRESSURE BUILDS ACROSS THE SE STATES. HOWEVER...THERE IS A GREAT DEAL OF UNCERTAINTY WITH THE EXACT TRACK OF THE NRN STREAM LOW...WITH THE 27/12Z GFS LIFTING IT THRU NE...THE 27/12Z ECMWF THRU THE NRN MID-ATLANTIC REGION AND THE 27/12Z CMC THRU NC. BASED ON THE OVERALL PROGRESSIVE PATTERN AND UPPER LEVEL FLOW...PREFER THE NRN TRACK...KEEPING THE FA DRY. ASSOCIATED WEAK COLD FRONT PUSHES ACROSS THE REGION TUES NIGHT-WEDS. LIMITED MOISTURE AND LITTLE APPRECIABLE FORCING WILL RESULT IN A DRY FRONTAL PASSAGE. UPPER/SFC HIGH PRESSURE BUILDS OVER THE ERN CONUS WEDS. THEREAFTER...MODELS DIVERGE WITH THE HANDLING OF A SRN STREAM SYSTEM LIFTING FROM THE SRN PLAINS INTO THE GULF STATES WEDS-WEDS NIGHT. GFS QUICKER TO RETURN MOISTURE TO THE REGION AS HIGH PRESSURE LOCATES OFF THE SE COAST WEDS-WEDS NIGHT...WHILE ITS ECMWF AND CMC COUNTERPARTS ARE SLOWER WITH THE MOISTURE RETURN. THEREAFTER...THE NEXT NRN STREAM SYSTEM PROGGED TO REACH THE GREAT LAKES/OH VALLEY LATE THIS WEEK INTO EARLY NEXT WEEKEND. SIGNIFICANT SPATIAL AND TIMING DIFFERENCES EXIST...WITH THE GFS PUSHING THE FRONT THRU 18 HRS BEFORE THE ECMWF (FRI VS. SAT MORNING). WILL MAINTAIN LOW END CHANCE POPS BEGINNING THURS. WILL CARRY LOW END CHANCE POPS THROUGH FRI...BUT AGAIN CONFIDENCE IS NOT HIGH ATTM. TEMPS TO BEGIN THE EXTENDED WILL BE RIGHT AROUND SEASONABLE NORMS...IN THE 60S INLAND AND UPPER 50S-LOW 60S ERN SHORE AND COASTAL AREAS. THURS HIGHS WILL BE DEPENDENT ON POTENTIAL CLOUD COVER/PRECIP. HAVE OPTED FOR A BLEND...RESULTING IN HIGHS IN THE UPPER 60S TO NEAR 70 INLAND AND LOW-MID 60S ERN SHORE AND COASTAL AREAS. LOWS GENERALLY IN THE LOW-MID 40S. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... A COLD FRONT NEAR THE CAROLINA COAST SOUTH OF CAPE HATTERAS HAS A LOW PRESSURE SYSTEM THAT WILL MOVE TO THE NORTHEAST OUT TO SEA THIS AFTN. A DEEP UPPER LEVEL TROUGH WILL APPROACH THE MID ATLANTIC STATES FROM THE WEST SATURDAY MORNING. HIGH PRESSURE BUILDS INTO THE REGION SATURDAY NIGHT AND SUNDAY. CONDITIONS AT THE TAF SITES HAVE FREQUENTLY VARIED FROM VFR TO IFR WITH MVFR BEING THE MOST PREDOMINANT CONDITION EXCEPT MOSTLY IFR AT ECG. IT HAS BEEN DIFFICULT TO NAIL DOWN THE TRENDS BUT BUFR SOUNDINGS WOULD INDICATE AN OVERALL DECREASE IN LOW LEVEL MOISTURE TOWARD EVENING. THE SOUNDINGS BECOME MORE SATURATED AGAIN WITH THE APPROACH OF THE TROUGH EARLY SATURDAY MORNING. DID NOT LOWER CEILINGS VERY MUCH DURING THIS TIME FRAME AND ANY PCPN WILL BE TOO SPARSE AND UNCERTAIN TO INCLUDE IN THE TAF. AN IMPROVING TREND RETURNS TOWARD MIDDAY SATURDAY. WINDS DIMINISH LATE TODAY AS THE PRESSURE GRADIENT WEAKENS BUT THEY STRENGTHEN AGAIN SATURDAY MORNING AS THE LOW OFF THE COAST INTENSIFIES WITH THE APPROACH OF THE UPPER LEVEL TROUGH. OUTLOOK...MAINLY DRY WEATHER DURING THE NEXT SEVERAL DAYS SHOULD PROMOTE GOOD FLYING CONDITIONS. && .MARINE... COLD FRONT HAS LOCATED OFF THE SE COAST THIS AFTERNOON. AN AREA OF LOW PRESSURE HAS DEVELOPED ALONG THE FRONT OFF THE SC COAST. MEANWHILE...HIGH PRESSURE HAS CENTERED OVER THE GREAT LAKES REGION. CURRENT OBS OVER THE WATER INDICATE NLY WINDS AVG 15-20 KT WITH WAVES 2-4 FT AND SEAS 4-6 FT. SFC LOW LIFTS NEWD TONIGHT TONIGHT AS HIGH PRESSURE REMAINS OVER THE GREAT LAKES. THIS WILL RESULT IN ANOTHER SURGE TONIGHT. STRONGEST CAA ARRIVES AFTER MIDNIGHT...WITH NW WINDS INCREASING TO 20-25 KT WITH GUSTS TO 30 KT OVER THE WATER. HIGH PRESSURE SLOWLY BUILDS SEWD THRU SAT NIGHT-SUN MORNING...RESULTING IN AN EXTENDED PERIOD OF CAA. SCA CONDITIONS WILL LIKELY PERSIST THRU SUN MORNING UNTIL HIGH PRESSURE FINALLY BUILDS OVER THE WATER. WAVES GENERALLY 3-4 FT AND SEAS 4-6 FT. NW WINDS SUBSIDE TO 10-15 KT SUN AFTERNOON WITH SEAS DROPPING BELOW 5 FT. EXTENDED SCA HEADLINES THRU SUN MORNING. HIGH PRESSURE QUICKLY PASSES OVER THE REGION SUN...AND THEN MOVES OFFSHORE SUN NIGHT. FLOW SHIFTS TO THE SSW. THE NEXT (WEAK) COLD FRONT APPROACHES FROM THE W LATE SUN. SW FLOW INCREASES LATE SUN NIGHT...WITH MODELS INDICATING SCA CONDITIONS. HOWEVER...BASED ON WAA AND COLD WATER...DO NOT ANTICIPATE SCA CONDITIONS. VERY LITTLE CAA IN WAKE OF THE FRONT LATE SUN NIGHT-MON MORNING...SO SCA CONDITIONS ARE NOT ANTICIPATED ATTM. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 1 AM SATURDAY TO 7 AM EDT SUNDAY FOR ANZ635>638. SMALL CRAFT ADVISORY UNTIL 11 AM EDT SUNDAY FOR ANZ630>634. SMALL CRAFT ADVISORY UNTIL NOON EDT SUNDAY FOR ANZ650-652-654- 656-658. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...ALB/JDM LONG TERM...SAM AVIATION...LSA MARINE...AJZ/SAM

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