Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 012239 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 639 PM EDT WED OCT 1 2014 .SYNOPSIS... BACK DOOR FRONT SINKS SOUTH INTO THE CAROLINAS TONIGHT. HIGH PRESSURE WILL AGAIN WEDGE SOUTH ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH THURSDAY. A STRONG COLD FRONT ARRIVES LATER FRIDAY FOLLOWED BY MUCH COOLER AIR FOR THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/...
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AS OF 635 PM EDT WEDNESDAY... RADAR HAS INDICATED A FEW SHOWERS TRYING TO DEVELOP ALONG THE BLUE RIDGE EARLY THIS EVENING...ALTHOUGH VERY WEAK INSTABILITY HAS PREVENTED THEM FROM BECOMING SUSTAINED. RAPID UPDATE MODELS INDICATE THAT ISOLATED SHOWERS WILL BRIEFLY POP UP FROM TIME TO TIME DURING THE EVENING...MAINLY NORTH OF HIGHWAY 460 ACROSS THE PIEDMONT. HAVE THEREFORE ADDED MENTION OF ISOLATED SHOWERS FOR THIS AREA THROUGH MIDNIGHT. WILL SEE 500 MB HEIGHT RISES OVERNIGHT AS OUR AREA BECOME SITUATED UNDER IN A WEAK RIDGE IN BETWEEN DEPARTING UPPER LOW WELL OFF THE EAST COAST AND THE DIGGING TROF OVER THE CENTRAL UNITES STATES. WEAK SURFACE COLD FRONT CROSSING INTO NORTH CAROLINA TONIGHT WILL DISSIPATE BY THURSDAY MORNING. HIGH PRESSURE WILL BE OVER THE FORECAST AREA ON THURSDAY. THERE MAY BE SOME EASTERLY FLOW ALONG THE BLUE RIDGE TONIGHT BUT ANY UPSLOPE WILL BE MINIMAL. MODELS AGAIN BRING LOW CLOUDS BACK IN OVERNIGHT EAST OF THE BLUE RIDGE. GOOD AGREEMENT IN THE SHORT TERM GUIDANCE THAT CLOUDS WILL FILL IN BETWEEN 06Z/2AM AND 08Z/4AM. BASED ON THE TRENDS THE PAST TWO NIGHTS...MAY SPEED THIS UP A COUPLE HOURS. WILL AGAIN HAVE DENSE FOG IN THE WESTERN RIVER VALLEYS THROUGH EARLY MORNING ON THURSDAY. GUIDANCE IN THE PIEDMONT HAS BEEN TOO COLD THE PAST TWO NIGHTS. WILL TREND A FEW DEGREES WARMER FOR OVERNIGHT LOWS. WILL ALSO LOWER TEMPERATURES AT HIGHER ELEVATIONS IN THE WESTERN COUNTY WARNING AREA. PREVAILING SLOW ON THURSDAY IS WESTERLY. LOCATIONS THAT HAVE ANY CLEARING IN THE MORNING WILL AGAIN HAVE ABOVE NORMAL HIGH TEMPERATURES.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 257 PM EDT WEDNESDAY... A COLD FRONT WILL APPROACH THE REGION THURSDAY NIGHT. WITH AN INCREASE IN MIXING AHEAD OF THIS FRONT...A SHALLOW WEDGE WILL CONTINUE TO ERODE WITH A PIECE HANGING OVER THE PIEDMONT INTO FRIDAY MORNING. AS EXPECTED...MODELS HAVE SLOWED DOWN THE TIMING OF THE FRONT AND PREFRONTAL SHOWERS ENTERING THE AREA. THE FRONT WILL ENTER THE OHIO VALLEY LATE IN THE MORNING WITH PREFRONTAL SHOWERS TRACKING ACROSS EXTREME WESTERN PORTION OF THE COUNTY WARNING AREA (SW VA/SE WV). BY EARLY AFTERNOON...THE FRONT MOVES OVER THE OHIO VALLEY AND SHOWERS ADVANCE EAST TO THE BLUE RIDGE. THE FRONT CROSSES OVER THE MOUNTAINS DURING THE EVENING WITH SHOWERS OVER THE FOOTHILL AND PIEDMONT COUNTIES...EXITING DURING THE EARLY MORNING HOURS SATURDAY. PRECIPITATION TIMING MAY VARY BY A COUPLE OF HOURS...AS THE CLOSED LOW CYCLES AND REORGANIZES OVER THE UPPER MISSISSIPPI FRIDAY. AS THE FRONT TRACKS TO THE EAST COAST SATURDAY MORNING...THE CLOSED LOW WILL MOVE EAST INTO THE OHIO VALLEY. A SHORT WAVE WITH THIS LOW LOOKS TO TRACK FARTHER TO THE SOUTH AND OVER THE TENNESSEE VALLEY. WITH THIS TRACK...THICK CLOUDS WILL REMAIN OVER THE MOUNTAINS...ESPECIALLY ALONG WESTERN SLOPES THROUGH SATURDAY MORNING. AS THIS SHORT WAVE EXITS THE FORECAST AREA...WEST WINDS WILL INCREASE AND CLOUDS WILL EVENTUALLY DISSIPATE. UNTIL THE CLOUDS ARE GONE...BREEZY/GUSTS WINDS SHOULD REMAIN ALONG HIGHER RIDGES THEN MIX DOWN SATURDAY AFTERNOON. HIGH PRESSURE TRACKING ALONG THE GULF STATES WILL STRETCH NORTH SATURDAY NIGHT ALLOWING WINDS TO SUBSIDE. WITH THE SLOWER ARRIVAL OF SHOWERS ON FRIDAY...WARMED TEMPERATURES A FEW DEGREES WITH L/M 70S WEST AND U70S/L80S EAST. ALONG WITH WARMER TEMPERATURES...INSTABILITIES WILL INCREASE...THEREFORE INCREASE THUNDERSTORMS ACTIVITY FROM ISOLATED TO SCATTERED FRIDAY AFTERNOON/EVENING. A DRAMATIC CHANGE IN TEMPERATURES AND HUMIDITY WILL BE FELT SATURDAY AS TEMPERATURES WILL RUN 5F-10F COOLER THAN NORMAL. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 310 PM EDT WEDNESDAY... FOLLOWING THE PASSING OF A COLD FRONT FRIDAY NIGHT...THE REGION WILL REMAIN UNDER AN UPPER LEVEL TROUGH THROUGH EARLY NEXT WEEK. COOLER THAN NORMAL AFTERNOON TEMPERATURES LIKELY THROUGH MONDAY...THEN MODERATING TOWARDS NORMAL BY MID WEEK. OVERNIGHT LOWS SATURDAY AND POSSIBLY SUNDAY NIGHT WILL BE COLD WITH MOUNTAINS TEMPERATURES DROPPING INTO THE 30S...40S IN THE EAST. FROST IS POSSIBLE ACROSS THE WEST IF WINDS COULD DECOUPLE EARLY SUNDAY MORNING. GROUND TEMPERATURES WILL REMAIN WARM ENOUGH TO LIMIT ANY FROST TO ISOLATED AREAS. THE EASTERN HALF OF THE USA WILL REMAIN UNDER A BROAD BUT FLAT TROUGH THROUGH TUESDAY. THERE COULD BE A MID LEVEL DISTURBANCE MOVING ACROSS THE OHIO VALLEY MONDAY...BUT WITH LIMITED MOISTURE...JUST SEEING AN INCREASE IN CLOUD COVER FOR THE AREA. TUESDAY MAYBE THE NEXT CHANCE FOR RAIN...AS A FRONT IS SCHEDULED TO MOVE OVER THE REGION. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... AS OF 130 PM EDT WEDNESDAY... VISIBLE SATELLITE LOOP SHOWED STRATUS EAST OF THE BLUE RIDGE CONTINUING TO LIFT AND BECOME SCATTERED EARLY THIS AFTERNOON. EXPECT VFR CONDITIONS AT KLYH AT THE BEGINNING OF THE 18Z TAF FORECAST PERIOD. A WEAK SHORT WAVE CROSSING THROUGH THE MID ATLANTIC REGION MAY TRIGGER ISOLATED TO SCATTERED SHOWERS LATE THIS AFTERNOON INTO THIS EVENING. THE PROBABILITY WAS TOO LOW AT THIS TIME TO INCLUDE IN THE TAFS. THE MOST LIKELY LOCATION FOR SHOWERS WILL BE JUST NORTH AND EAST OF KLYH. TONIGHT...WEDGE EXPECTED TO SET UP AND LOOKING AT MVFR/IFR CIGS/VSBYS REFORMING AT LYH/DAN OVERNIGHT. NSSL WRF AND NAM BUFKIT FORECAST BOTH SHOWED REDEVELOPMENT OF THE LOW CLOUDS AROUND 07Z/1AM TONIGHT. FOG AGAIN AT BCB/LWB IN THE IFR/LIFR RANGE LATE. HIGH CONFIDENCE THAT IFR CONDITIONS WILL PERSIST UNTIL 13Z/9AM. EXTENDED AVIATION DISCUSSION... EXPECT VFR THU AFTERNOON INTO THU NIGHT. FRONTAL BOUNDARY AND ASSOCIATED SHOWERS TO IMPACT THE MOUNTAINS BY LATE FRIDAY MORNING AND THE PIEDMONT IN THE AFTERNOON. SUB VFR EXPECTED IN HEAVIER SHOWERS OR ISOLATED TSRA. SHOWERS EXITING THE MTNS BY LATE FRIDAY EVENING AND THE PIEDMONT TOWARD DAWN SATURDAY. TIMING OF CLEARING IS STILL TRICKY. SATURDAY SHOULD BE CLEARING OUT IN THE PIEDMONT TO ROANOKE/BLACKSBURG BUT UPSLOPE MVFR CIGS AT BLF/LWB MAY OCCUR INTO SAT AFTERNOON...WITH BREEZY NW WINDS. WINDS DIMINISH SATURDAY NIGHT. THEN VFR SUNDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...AMS/NF SHORT TERM...RCS LONG TERM...RCS AVIATION...AMS

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