Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 261125 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 725 AM EDT TUE APR 26 2016 .SYNOPSIS... FRONT WITH WAVES OF LOW PRESSURE EXTENDED FROM NEW JERSEY TO MISSOURI THIS MORNING. THIS FRONT WILL DRIFT SOUTH THEN STALL OVER THE MID ATLANTIC REGION ON WEDNESDAY. ANOTHER LOW PRESSURE SYSTEM WILL TRACK FROM THE MID MISSISSIPPI VALLEY TO THE EAST COAST ON THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 355 AM EDT TUESDAY... LOW PRESSURE OVER MICHIGAN WILL MOVE EAST ALONG A FRONT INTO EASTERN PENNSYLVANIA TODAY. THEN THE FRONT WILL MOVE SOUTH INTO THE MID ATLANTIC REGION LATE TODAY INTO TONIGHT. THE SURFACE BOUNDARY REACHES THE FORECAST AREA AFTER 00Z/8PM...WHILE THE 850MB FRONT STAYS WELL TO THE NORTH. STARTING OUT WITH LITTLE CLOUD COVER THIS MORNING SO TEMPERATURES WILL WARM QUICKLY AFTER SUNRISE. WITH SURFACE DEW POINTS IN THE 50S...CONVECTIVE AVAILABLE POTENTIAL ENERGY WAS FORECAST TO BE AROUND 1500 J/KG THIS AFTERNOON AHEAD OF THE FRONT. SOME GUIDANCE SUGGESTED POOLING OF DEW POINTS IN THE LOWER 60S JUST AHEAD OF THE BOUNDARY WHICH WOULD RESULT IN EVEN LARGER CAPE. 00Z NAM AS WELL AS THE RAP AND LOCAL WRF HAVE A BULK OF THE PRECIPITATION THAT WILL BE AHEAD OF THE FRONT REACHING THE NORTHERN COUNTY WARNING AREA JUST AFTER 18Z/2PM. BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS MAY NOT PROGRESS SOUTH...REACHING THE VIRGINIA/NORTH CAROLINA BORDER UNTIL AROUND 00Z/8PM. BETTER VORTICITY ADVECTION AND JET SUPPORT REACH THE FORECAST AREA TONIGHT SO HAVE INCREASED THE PROBABILITY OF PRECIPITATION FOR TONIGHT. GUIDANCE WAS TOO COOL FOR MAXIMUM TEMPERATURES ON MONDAY. HAVE GONE CLOSER TO WARMER GUIDANCE AND PERSISTENCE FROM MONDAY FOR MAXIMUM TEMPERATURES TODAY. CLOUDS AND MILD DEW POINTS WILL KEEP TEMPERATURES FROM DROPPING MUCH OVERNIGHT. HAVE RAISED MINIMUM TEMPERATURES SLIGHTLY ACROSS THE PIEDMONT TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... AS OF 330 AM EDT TUESDAY... THE UPPER LEVEL PATTERN WILL REMAIN UNSETTLED AS THE WESTERN TROF SPLINTERS INTO PIECES WITH SEVERAL BITS OF SHORT WAVE ENERGY MOVING IN OUR DIRECTION INTERSPERSED WITH PERIODS OF GENERALLY FLAT RIDGING. AND WITHOUT SOLID UPPER LEVEL SUPPORT TO MOVE IT ALONG...THE FRONTAL ZONE AT THE SURFACE WILL SIMPLY LINGER OVER THE REGION THROUGH THE END OF THE WEEK. AMPLE CONVERGENCE AND INSTABILITY IN THE FRONTAL ZONE WILL KEEP UP WITH A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. BY FRIDAY IT APPEARS THAT A SHORT WAVE REMNANT OF THE WESTERN TROF WILL SWING BY TO OUR NORTH AND HELP PUSH THE FRONTAL BOUNDARY FURTHER TO THE SOUTH AND ALLOW A WEDGE OF HIGH PRESSURE TO BUILD DOWN EAST OF THE APPALACHIANS. HOWEVER ANY IMPROVEMENT IN OUR WEATHER LOOK TO BE MARGINAL SINCE CLOUDS AND SOME LIGHT PRECIPITATION WILL ACCOMPANY THE WEDGE. TEMPERATURES WILL GENERALLY BE A BIT ABOVE NORMAL THROUGH THE END OF THE WEEK WITH HIGHS IN THE MID 70S TO AROUND 80 EAST OF THE BLUE RIDGE...AND IN THE LOW TO MID 70S WEST. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 245 PM EDT MONDAY... WEAK UPPER RIDGING THROUGH SATURDAY WILL KEEP PRECIP CHANCES CONFINED TO ISOLATED/WIDELY SCATTERED IN COVERAGE. AT THE SFC...12Z ECMWF KEEPS WEDGE IN PLACE THROUGH SATURDAY. WHILE TEMPS WERE BROUGHT DOWN A COUPLE OF DEGREES DURING THIS TIME...THESE FORECAST VALUES STILL MAY BE TOO WARM. HOWEVER...BETTER CHANCES FOR MORE WIDESPREAD PRECIPITATION ARRIVE LATER SUNDAY INTO MONDAY...DEPENDING ON THE ARRIVAL OF AN OPENING UPPER LOW MOVING THROUGH THE OHIO VALLEY. AS IT TYPICAL FOR THE LONG RANGE MODELS...THERE IS DISAGREEMENT IN THE TIMING AND TRACK OF THIS SYSTEM...BUT INDIVIDUAL GEFS ENSEMBLE MEMBERS SUGGEST THE BEST CHANCES FOR PRECIPITATION WILL BE LATE SUNDAY INTO EARLY MONDAY...AND THIS IS THE TIME PERIOD WHERE THE POPS ARE HIGHEST. TEMPS ARE EXPECTED TO BE BELOW NORMAL EARLY WITH THE WEDGE IN PLACE TO NEAR NORMAL LATER IN THE LONG TERM PERIOD. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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AS OF 720 AM EDT TUESDAY... A COLD FRONT EXTENDED FROM PENNSYLVANIA TO MISSOURI THIS MORNING. THIS FRONT WILL MOVE SOUTH INTO THE MID ATLANTIC REGION TODAY. WITH THE BOUNDARY IN THE AREA AND MOISTURE ON THE INCREASE...SCATTERED SHOWERS AND THUNDERSTORM WITH MVFR CEILINGS AND VISIBILITIES WILL DEVELOP THIS AFTERNOON...MAINLY ACROSS THE MOUNTAINS. BY THE LATE MORNING SURFACE WIND GUSTS WILL BE IN THE 15 TO 20 KT RANGE. MODELS BRING THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS INTO THE AREA AFTER 3PM IN KLWB AND NOT UNTIL 5PM AT KDAN. MEDIUM CONFIDENCE ON THE TIMING OF THE PRECIPITATION AND ON THE OCCURRENCE OF AN ADDITIONAL PRECIPITATION OVERNIGHT. EXTENDED AVIATION DISCUSSION... THIS FRONT WILL REMAIN STALLED OVERHEAD WEDNESDAY...BEFORE A STRONGER COLD FRONT ENTERS FROM THE WEST TO PUSH THE WEAKER FRONT OFFSHORE. DURING THIS TIME...SCATTERED SHOWERS WITH A FEW AFTERNOON THUNDERSTORMS APPEAR LIKELY. THE GREATEST CHANCE OF RAIN AND MVFR/IFR CONDITIONS WILL ACCOMPANY THE STRONGER COLD FRONT ON THURSDAY. SOME CLEARING SHOULD TAKE PLACE DURING FRIDAY...ALTHOUGH A FEW MOUNTAIN SHOWERS AND MVFR CLOUDS ARE POSSIBLE.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PH LONG TERM...PH AVIATION...AMS/DS

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