Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 150815 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 415 AM EDT TUE APR 15 2014 .SYNOPSIS...
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A STRONG COLD FRONT WILL CROSS THE AREA TODAY...THEN MOVE OFF THE COAST THIS EVENING. CANADIAN HIGH PRESSURE BUILDS IN FROM THE NORTHWEST TUESDAY NIGHT AND SETTLES OVER THE MID ATLANTIC AND NORTHEAST WEDNESDAY AND THURSDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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LITTLE CHANGE COMPARED TO PREVIOUS FORECASTS AS A STRONG COLD FRONT IS SET TO IMPACT THE REGION THIS AFTERNOON. REST OF THIS MORNING... LATEST WATER VAPOR IMAGERY AND UPPER AIR RAOB PLOTS DEPICT ANOMALOUS LONGWAVE TROUGH OVER THE CENTRAL CONUS...SLOWLY PROGRESSING EWD. ASSOCIATED COLD FRONT IS STRETCHING FROM THE OH VALLEY SWD INTO THE LOWER MS VALLEY/NRN GULF. ALSO VISIBLE ON WATER VAPOR IS A PLUME OF MOISTURE FROM THE NRN GULF NEWD INTO NEW ENGLAND...THANKS TO DEEP LAYER SWLY FLOW. PER BLENDED TOTAL PRECIP WATERS...PRECIP WATER VALUES HAVE REACHED 200+ PCT OVER THE LOCAL AREA. UPSLOPE FLOW AND ANOMALOUS MOISTURE HAS RESULTED IN WIDESPREAD PRECIP OVER THE CNTRL APPALACHIANS...WITH MOST OF THE PRECIP STAYING TO THE WEST OF OUR ERN VA PIEDMONT COUNTIES. ANOTHER AREA OF UPGLIDE ALONG THE COAST HAS PRODUCED SCT SHOWERS FROM ELIZABETH CITY NWD TO SALISBURY. ANOTHER AREA OF SHOWERS OVER S CNTRL NC WILL LIKELY LIFT OVER THE PIEDMONT INTO CNTRL VA EARLY THIS MORNING...AIDED STRONG UPPER LEVEL SUPPORT. FOR TODAY... STRONG SPEED MAX EMERGING FROM THE BASE OF THE UPPER TROUGH WILL EJECT THE TROUGH NEWD TODAY. THIS WILL RESULT IN THE TROUGH BECOMING NEGATIVELY TILTED AS IT LIFTS OVER THE MID-ATLANTIC REGION. COLD FRONT PROGGED TO REACH THE LOCAL AREA LATE MORNING- EARLY AFTERNOON. MODELS HAVE A GOOD HANDLE ON THE TIMING OF THE FRONT...PUSHING IT THRU THE LOCAL AREA THIS AFTERNOON AND OFFSHORE THIS EVENING. STRONG HEIGHT FALLS AND A SHARP TEMPERATURE CONTRAST WILL RESULT IN STRONG FRONTOGENETIC FORCING ALONG THE FRONT. RRQ OF 160+KT UPPER JET AND VORTICITY ADVECTION WILL PROVIDE STRONG UPPER LEVEL FORCING FOR ASCENT ALONG THE FRONT. INCREASING WINDS ALOFT WILL ALSO RESULT IN A STRONG LLJ...WITH 850 WINDS 50-60 KT (+3 TO +4 STD DEV). THE RESULT IS A FAVORABLE SYNOPTIC SETUP. INSTABILITY WILL BE RATHER LIMITED...BUT THETA-E ADVECTION AND TEMPS IN THE MID-UPPER 70S WILL PRODUCE A MARGINALLY UNSTABLE AIRMASS (MLCAPE 500-750 J/KG) DESPITE CLOUD COVER. THE EXCEPTION WILL LIKELY BE OVER THE PIEDMONT WHERE RAINFALL WILL FURTHER LIMIT INSTABILITY. 0-3KM BULK SHEAR OF 50-60 KT WILL LIKELY RESULT IN ANY DEVELOPING CONVECTION TO ORGANIZE INTO LINE SEGMENTS...WITH SOME BOWING SEGMENTS POSSIBLE. THIS WILL LEAD TO AN ENHANCED THREAT FOR DAMAGING WINDS IN EXCESS OF 50 KT THANKS TO STRONG LLG. LATEST NAM/SREF/ECMWF GUIDANCE INDICATE A WAVE DEVELOPING ALONG THE FRONT OVER CNTRL NC EARLY THIS AFTERNOON...LIFTING INTO NE NC/POSSIBLE SE VA. IF THIS OCCURS...THIS WOULD INCREASE LOW LEVEL HELICITY...WITH ISOLATED WEAK TORNADOES POSSIBLE IN BROKEN LINE SEGMENTS. MUCH OF THE LOCAL AREA REMAINS UNDER A SLIGHT RISK FOR SEVERE WEATHER. BEST CHANCES FOR SEVERE WEATHER WILL BE MID-LATE AFTERNOON ALONG THE IMMEDIATE FRONT AS IT REACHES INTERSTATE 95 AND POINTS EWD. THE EXCEPTION WILL BE THE MD/VA ERN SHORE WHERE A MARINE ENVIRONMENT WILL LIMIT SEVERE POTENTIAL. ANOMALOUS MOISTURE AND STRONG DYNAMICS WILL ALSO RESULT IN PERIODS OF HEAVY RAINFALL. COLD FRONT MAY SLOW SLIGHTLY AS IT REACHES THE COAST...BUT WILL PUSH OFFSHORE EARLY THIS EVENING...WITH PRECIP ENDING SHORTLY THEREAFTER. TOTAL QPF AMOUNTS WILL RANGE FROM 1-1.5 INCHES. THE IMPACT THEN BECOMES INCREASING NW WINDS AND THE ASSOCIATED COLD AIR SURGING INTO THE REGION. SKIES WILL ALSO BEGIN TO CLEAR QUICKLY W-E AS THE BEST MOISTURE QUICKLY PUSHES OFFSHORE AND THE TROUGH LIFTS NE OF THE REGION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... STRONG SFC HIGH PRESSURE REMAINS ANCHORED OVER NEW ENGLAND TO BEGIN THE MEDIUM RANGE FORECAST PERIOD, RESULTING IN CONTINUED NE FLOW OVER THE MID ATLANTIC FRIDAY. TEMPERATURES WILL BE COOL TO BEGIN THE PERIOD FRIDAY...ABOUT ONE STANDARD DEVIATION BELOW NORMAL...WITH TEMPS MODERATING A BIT SATURDAY. ALOFT, NORTHERN STREAM SHORTWAVE TROUGH, AND ATTENDANT SFC LOW IS EXPECTED TO PUSH ACROSS THE MID MS VLY TOWARDS THE EASTERN GREAT LAKES FRI-SAT, EVENTUALLY PUSHING A MAINLY DRY COLD FRONT THROUGH SAT NGT AND EARLY SUNDAY. BOTH MODELS DO TAKE A PIECE OF SHORTWAVE ENERGY ACROSS THE MID-SOUTH TOWARDS THE CAROLINA COAST FRIDAY-SATURDAY, WITH RESULTANT WEAK INVERTED TROUGHING THAT DEVELOPS PROMPTING SOME LOW POPS LATER FRIDAY AND SATURDAY. THE 12Z/14 EURO SOLUTION REMAINS A BIT WETTER THAN THE PROGRESSIVE GFS SOLUTION. HAVE SPLIT THE DIFFERENCE BETWEEN THE GFS/UKMET FOR THIS PACKAGE. RIGHT NOW, IT APPEARS THAT THE BEST RAIN CHC WOULD BE OVER EASTERN SECTIONS ALONG THE COASTAL TROUGH FRIDAY NIGHT THROUGH MIDDAY SATURDAY. UPPER TROUGH EJECTS NORTHEAST LATER SATURDAY, WITH SHORTWAVE RIDGING ARRIVING FROM THE WEST SHUNTING SYSTEM OFFSHORE. QUICK CLEARING EXPECTED THEREAFTER TOWARDS THE TAIL END OF THE PERIOD (EASTER SUNDAY AND MONDAY). && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS ACROSS AREA TERMINALS EARLY THIS EVENING. WINDS CONT TO BE BREEZY 15-25 KT. A FEW SPOTTY SPRINKLES ACROSS THE REGION WITH THE HEAVIER PRECIP STILL WEST AND SOUTH OF THE CWA. EXPECT CHANCE OF RAIN TO INCREASE AFTER MIDNIGHT AS FRONT APPROACHES. CIGS SLOWLY DETERIORATE TO MVFR TONIGHT...W/PERIODIC IFR CIGS POSSIBLE TOWARDS SUNRISE AS MOISTURE ADVECT IN ADVANCE OF THE FRONT. BREEZY SOUTHERLY WINDS CONTINUE TUESDAY (GUSTS OF 30-35 KT) AS THE FRONT APPROACHES FROM THE WEST. COLD FRONT CROSSES THE REGION TUESDAY, ACCOMPANIED BY WIDESPREAD RAINFALL TUES-TUES NIGHT WITH PERIODIC IFR VSBY RESTRICTIONS IN HEAVY RAIN. THERE IS ALSO THE POTENTIAL FOR A STRONG LINE OF CONVECTION ON THE LEADING EDGE OF THE FRONT TUES AFTERNOON MAINLY ACROSS SOUTHEASTERN TERMINALS (PHF-ORF- ECG)W/ HEAVY RAIN AND STRONG WIND GUSTS UP TO 50 KT POSSIBLE. OUTLOOK...BEHIND THE FRONT, LOOK FOR WINDS TO BACK TO THE NW AND REMAIN GUSTY. SOME GUSTS UP TO 40 KT POSSIBLE ALONG THE COAST. IMPROVING CONDITIONS WED THRU FRIDAY AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. && .MARINE... STRONG COLD FRONT WILL APPROACH FM THE W TNGT...THEN PUSH ACRS THE AREA TUE INTO TUE EVENG. DECENTLY STRNG SOUTHERLY WINDS IN ADVANCE OF THE FRONT TNGT THRU TUE...WILL BECOME VERY STRONG N WINDS BEHIND THE FRONT TUE NGT THRU MUCH OF WED...AS A MUCH COLDER/DRIER AIRMASS FILTERS INTO THE AREA. DURING THIS EVENT...WAVES WILL BLD TO 4 TO 6 FT OVR THE CHES BAY...AND SEAS WILL BLD TO 5 TO 9 FT ON THE CST. HI PRES WILL THEN BLD JUST TO THE N WED AFTN...THEN SLIDES NE ACRS NEW ENGLAND AND INTO THE CANADIAN MARITIMES WED NGT THRU THU. THIS WILL RESULT IN NE WINDS AND ELEVATED SEAS THRU THE END OF THE WEEK. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR MDZ021>024. NC...FREEZE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR NCZ012. VA...FREEZE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR VAZ078-084>090-092-093. FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR VAZ048-049- 060>077-079>083. MARINE...GALE WARNING UNTIL 1 PM EDT WEDNESDAY FOR ANZ650-652-654-656- 658. GALE WARNING FROM 8 AM THIS MORNING TO 7 AM EDT WEDNESDAY FOR ANZ635>638. GALE WARNING UNTIL 7 AM EDT WEDNESDAY FOR ANZ630>632-634. GALE WARNING FROM 8 AM THIS MORNING TO 1 PM EDT WEDNESDAY FOR ANZ633.
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&& $$ SYNOPSIS...LSA NEAR TERM...SAM SHORT TERM...MPR/LSA LONG TERM...MAM/JEF AVIATION...JEF MARINE...TMG

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