Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 151739 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 139 PM EDT MON SEP 15 2014 .SYNOPSIS... HIGH PRESSURE OVER THE AREA THIS MORNING WILL SHIFT EAST AND OFFSHORE THIS AFTERNOON BRINGING WARMER TEMPERATURES AS LIGHT RETURN SOUTHWEST FLOW DEVELOPS. THE NEXT COLD FRONT MOVES THROUGH LATER TONIGHT RESULTING IN A FEW SHOWERS FOLLOWED BY DRIER AND COOLER WEATHER INTO MID WEEK. STRONG HIGH PRESSURE WILL BUILD NORTH OF THE AREA FOR THE REST OF THE WEEK KEEPING RATHER COOL BUT OVERALL DRY WEATHER IN PLACE. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 100 PM EDT MONDAY... MAIN CHANGE WAS TO REMOVE ISOLATED THUNDER FROM GRIDS OVER THE SW BLUE RIDGE WEHER. CLOUDS ARE HOLDING INSTABILITY TO NEARLY NIL PER SPC MESOSCALE ANALYSIS. AMONG SHORT-RANGE MODELS ONLY NAM GENERATES EVEN MODEST CAPE (<500 J/KG) ON FORECAST BUFKIT SOUNDINGS BY LATE THIS AFTERNOON AT KTNB AND NOTHING MUCH AT ALL FURTHER NORTHEAST. FEW CHANGES TO T/TD GRIDS OR POPS OTHERWISE.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... AS OF 315 AM EDT MONDAY... A COLD FRONT WILL HEAD SOUTH OF THE REGION DURING THE DAY TUESDAY. FORECAST 850 MB NORTHWEST WINDS BEHIND THE FRONT SHOULD YIELD SURFACE GUSTS OF 15 TO 20 MPH ACROSS THE MOUNTAINS DURING THE MORNING HOURS. ALSO...ENOUGH RESIDUAL MOISTURE AND UPSLOPE FLOW WILL HELP MAINTAIN SOME ISOLATED SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA...NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA...AND THE NORTHERN MOUNTAINS OF NORTH CAROLINA PRIMARILY DURING THE MORNING AS WELL. TUESDAY NIGHT THROUGH THURSDAY NIGHT...A BROAD UPPER TROUGH IS FORECAST TO BECOME POSITIONED ACROSS THE U.S. EAST COAST. SURFACE HIGH PRESSURE WILL BUILD OVER PENNSYLVANIA...AND AN ASSOCIATED LEE SIDE TROUGH WILL EXTEND SOUTH THROUGH OUR REGION. WHILE THE FORECAST WILL BE A DRY ONE FOR MUCH OF THE REGION...LOW LEVEL FLOW WILL GRADUALLY TAKE ON PRIMARILY AN E-SE COMPONENT WHICH WILL POOL MOISTURE INTO THE CREST OF THE BLUE RIDGE...ALLOWING FOR THE POTENTIAL FOR SOME UPSLOPE LIGHT RAIN SHOWERS IN THE NORTHERN MOUNTAINS AND FOOTHILLS OF NORTH CAROLINA AND NEIGHBORING PARTS OF SOUTHWEST VIRGINIA. THIS E-SE FETCH MAXIMIZES...AND POTENTIALLY TAPS SOME ATLANTIC MOISTURE ON THURSDAY AND THURSDAY NIGHT. THIS WOULD ALLOW FOR A BIT MORE OF THE REGION...ESPECIALLY ALONG AND NEAR THE CREST OF THE BLUE RIDGE...TO EXPERIENCE SOME ISOLATED SHOWERS. CANNOT RULE OUT SOME ISOLATED THUNDERSTORMS BOTH TUESDAY AFTERNOON AND WEDNESDAY AFTERNOON IN THE NC MOUNTAINS. TEMPERATURES WILL TREND COOLER DURING THIS PORTION OF THE FORECAST BEHIND THE COLD FRONT PASSAGE AND AS DRIER DEW POINT AIR SETTLES INTO THE REGION. && .LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 345 PM EDT SUNDAY... FOR MOST OF THE LONG TERM PERIOD A BROAD UPPER TROF WILL CONTINUE TO HOLD OVER THE EASTERN U.S. WITH SFC HIGH PRESSURE EXTENDING FROM THE NORTHEAST THROUGH THE MID-ATLANTIC...KEEPING A WEDGE IN PLACE THROUGH THE PERIOD. A REINFORCING SHOT OF DRIER AIR ARRIVES BY FRIDAY AS A NORTHERN STREAM WAVE BRIEFLY AMPLIFIES THE UPPER TROF. ECMWF/GFS ENSEMBLE MEANS AND DETERMINISTIC RUNS NOW SHOW AN UPPER RIDGE TRYING TO BUILD LATE IN THE LONG TERM PERIOD (SATURDAY/SUNDAY) WHICH WILL WEAKEN THE WEDGE OF HIGH PRESSURE AT THE SFC AND ALLOW TEMPS TO MODERATE. UNTIL THEN...TEMPS WILL BE BELOW NORMAL AND MORNING LOWS IN THE 40S WILL BE COMMON FOR MANY MOUNTAIN VALLEY LOCATIONS. OUTSIDE OF UPSLOPE SHOWERS IN THE SOUTHERN BLUE RIDGE/NW NC MOUNTAINS AND FOOTHILLS...MOST AREAS SHOULD REMAIN DRY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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AS OF 130 PM EDT MONDAY... CIGS HAVE BEEN VARIABLE TODAY BUT HOLDING MAINLY IN MVFR RANGES UNDER LIGHT SOUTH TO SOUTHEASTERLY FLOW..BUT VSBYS HAVE ALL RECOVERED TO VFR AT THE TERMINALS. WILL MAINTAIN SIMILAR OR SLIGHTLY IMPROVED CONDITIONS REST OF THE DAY AND RAINFALL AS ANY SHOWER COVERAGE WILL BE VERY SPARSE AND LIGHT. WEAK COLD FRONT STILL FORECAST TO PUSH THROUGH THIS EVENING WITH AGAIN MOSTLY ISOLATED SHOWERS BUT LIKELY ENOUGH WESTERLY FLOW TO KEEP THINGS MOSTLY VFR DURING THE EVENING. POTENTIAL FOR LOWER CIGS TO DEVELOP...MAINLY KBLF/KLWB...LOOKS TO COME LATER TONIGHT WITH INCREASING UPSLOPE FLOW AND PERHAPS A FEW MORE SHOWERS AROUND. SOME POTENTIAL TO ALSO SEE FOG REDEVELOP ACROSS THE EAST AS WELL DESPITE THE FRONTAL PASSAGE GIVEN LIGHT WINDS AND LINGERING MOISTURE WILL INCLUDE A LATE NIGHT VSBY REDUCTION OUT EAST EXCLUDING KROA OTRW SHOULD REMAIN VFR OUTSIDE OF FOG. EXTENDED AVIATION DISCUSSION... UPSLOPE MOISTURE MAY PERSIST INTO TUESDAY ALONG THE WESTERN SLOPES WHILE EXPECT BRIEF DOWNSLOPE TO BRING MAINLY VFR ELSW INTO TUESDAY AFTERNOON AS WEAK HIGH PRESSURE BUILDS IN. BROAD UPPER TROUGH REMAINS IN PLACE ACROSS THE EASTERN STATES FOR THE REMAINDER OF THE WEEK ALLOWING A LARGE AREA OF HIGH PRESSURE TO BUILD SOUTH FROM THE GREAT LAKES FOR MID WEEK BEFORE WEDGING IN FROM OFF THE MID ATLANTIC COAST BY THE WEEKEND. THIS SHOULD PUSH THE PESKY DEEP MOISTURE FURTHER SOUTH AWAY FROM THE REGION. HOWEVER BIGGER CONCERN WILL BE WITH TRAPPED RESIDUAL LOW LEVEL MOISTURE THAT MAY KEEP SOUTHERN/WESTERN LOCATIONS STUCK IN PERIODS OF MVFR CIGS ESPCLY WEDNESDAY INTO FRIDAY AS THE LOW LEVEL EAST/SE FLOW TAKES SHAPE.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/PC SHORT TERM...DS LONG TERM...PH AVIATION...JH/PC

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