Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191925 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 325 PM EDT FRI SEP 19 2014 .SYNOPSIS... HIGH PRESSURE WILL WEDGE SOUTH ALONG THE EASTERN SLOPES OF THE APPALACHIANS TONIGHT INTO SUNDAY...WHICH WILL KEEP DRY WEATHER IN PLACE. A COLD FRONT SHOULD CROSS THE AREA FROM THE NORTHWEST LATER SUNDAY NIGHT INTO MONDAY...FOLLOWED BY COOLER AND DRIER WEATHER INTO NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 300 PM EDT FRIDAY... SFC HIGH PRESSURE OVER NEW ENGLAND THIS AFTERNOON WILL SLIDE EAST TONIGHT INTO SATURDAY. FLOW AROUND THE HIGH CENTER WILL RESULT IN EASTERLY WINDS PUSHING MOISTURE UP AGAINST THE APPALACHIANS. LOW LEVEL MOISTURE CONVERGENCE WILL COMBINE WITH PASSING TROUGH UNDER DECENT 85H THETA-E RIDGING TO CREATE AREAS OF RAIN. SURFACE RIDGING STRENGTHENS FROM THE NORTHEAST OVERNIGHT HELPING PUSH THE RESIDUAL AXIS OF MOISTURE FARTHER WEST WHICH SHOULD BRING AN END OR TAPER OFF POPS FOR RAIN DURING THE EVENING INTO TONIGHT. BANKED UP LOW LEVEL MOISTURE THOUGH LIKELY TO REDEVELOP OR PERSIST BLUE RIDGE WHERE LOTS OF LOW CLOUDS/FOG AND DRIZZLE ARE POSSIBLE. PLAYED LOW TEMPERATURES TONIGHT CLOSE TO ADJMAVBC WITH READINGS FROM THE LOWER 50S IN THE MOUNTAINS TO AROUND 60 DEGREES IN THE SOUTH. THE HIGH PRESSURE CENTER WILL MOVE OUT INTO THE ATLANTIC OCEAN SATURDAY. THE RIDGE WILL WEDGE BACK OVER THE MID ATLANTIC AND SOUTHEASTERN STATES INTO SATURDAY NIGHT. LEANED HIGH TEMPERATURES SATURDAY TOWARDS ADJMAV WITH VALUES FROM LOWER 70S IN THE MOUNTAINS TO AROUND 80 DEGREES IN THE PIEDMONT. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 315 PM EDT FRIDAY... A SLIVER OF HIGH PRESSURE WILL REMAIN WEDGED AGAINST THE EASTERN SIDE OF THE BLUE RIDGE ON SATURDAY NIGHT...WHILE AN AREA OF LOW PRESSURE HEADS NORTHWARD OVER THE GULF STREAM. BY SUNDAY MORNING...A COLD FRONT SHOULD APPROACH THE APPALACHIAN MOUNTAINS...WHICH WOULD ERODE THE COOL WEDGE. MOST OF THE DYNAMICS WITH THIS COLD FRONT WILL STAY WELL TO THE NORTH IN EASTERN CANADA...SO QPF DOES NOT APPEAR IMPRESSIVE FOR SUNDAY EVENING. CAPE APPROACHES 500-1000 J/KG ALONG THE WESTERN SLOPES IN MODEL SOUNDINGS...AS TEMPERATURES WARM INTO THE MID 70S TO THE MID 80S...SO THE CHANCE OF SHOWERS AND THUNDERSTORMS WAS INCLUDED WEST OF THE BLUE RIDGE. WITH AN EXPECTED WEST WIND THAT WILL AID IN DOWNSLOPE FLOW EAST OF THE BLUE RIDGE...IT WILL BE DIFFICULT TO GENERATE ANYTHING OVER THE PIEDMONT. BY SUNDAY NIGHT...THE COLD FRONT SHOULD CROSS OVER THE CWA. WITH DECENT NORTHWEST FLOW EXPECTED BEHIND THIS FRONT...IT IS POSSIBLE FOR A FEW UPSLOPE RAIN SHOWERS ALONG THE WESTERN SLOPES OVERNIGHT INTO MONDAY MORNING. THE WINDS SHOULD SUBSIDE LATER DURING THE DAY...AS A LARGE 1026 MB HIGH HEADS TOWARD THE OHIO RIVER VALLEY JUST IN TIME FOR THE AUTUMNAL EQUINOX. IT WILL CERTAINLY FEEL LIKE THE FIRST DAY OF FALL BY TUESDAY MORNING...WITH MOS GUIDANCE DEPICTING LOW TEMPERATURES VARYING FROM THE LOWER 40S IN THE COOLER MOUNTAIN VALLEYS...TO THE LOWER 50S IN SOUTHSIDE VIRGINIA AND THE NORTH CAROLINA PIEDMONT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 PM EDT FRIDAY... HIGH PRESSURE WILL BE IN CONTROL OF THE FORECAST REGION ON TUESDAY...STARTING THE DAY CENTERED OVER THE MID OHIO RIVER VALLEY. THE HIGH WILL MAINTAIN DRY NORTHERLY WIND FLOW ACROSS OUR AREA THAT WILL KEEP TEMPERATURES A FEW DEGREES BELOW NORMAL...WITH HIGHS HOLDING IN THE UPPER 60S TO MID 70S. THE DRY ATMOSPHERE WILL ALSO RESULT IN MOSTLY CLEAR SKIES. WE CAN EXPECT SIMILAR CONDITIONS FOR THE EARLY HALF OF WEDNESDAY... ALTHOUGH A REINFORCING COLD FRONT WILL BUILD SOUTHWARD FROM EASTERN CANADA...CROSSING NEW ENGLAND INTO THE MID ATLANTIC DURING THE EVENING...WHERE THE FRONT IS THEN EXPECTED TO STALL AS IT RUNS INTO UPPER LEVEL RIDGING ACROSS THE SOUTHEAST. WINDS WILL SHIFT MORE EASTERLY WEDNESDAY NIGHT AS HIGH PRESSURE PUSHES OFFSHORE...DRAWING AN INCREASING AMOUNT OF MARINE AIR INTO OUR REGION. AS SUCH...EXPECT INCREASED STRATUS ACROSS THE MOUNTAINS WEDNESDAY NIGHT...POSSIBLY WITH PATCHY DRIZZLE. MARINE AIR WILL ALSO SUPPORT SPOTTY LIGHT RAIN ACROSS THE PIEDMONT THURSDAY AFTERNOON. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... AS OF 200 PM EDT FRIDAY... RADAR INDICATES LIGHT RAIN CONTINUING TO DRIFT NORTH THIS AFTERNOON...THINNING AS IT PROGRESSES...AS IT MOVES INTO THE INCREASINGLY STABLE AIR ASSOCIATED WITH HIGH PRESSURE WEDGED AGAINST THE EASTERN FACE OF THE APPALACHIANS. WIND FLOW REMAINS OUT OF THE NORTH-NORTHWEST EAST OF THE BLUE RIDGE...BECOMING EASTERLY TO SOUTHEASTERLY ACROSS THE MOUNTAINS. THE UPSLOPE FLOW IS MAINTAINING IFR CEILINGS FOR LYH/ROA/BCB/LWB...WHILE BLF REMAINS OUTSIDE THE WEDGE. LOW CEILINGS HAVE MIXED OUT IN THE SLIGHTLY MORE UNSTABLE AIR NEAR DAN. LOW CEILINGS WILL LINGER THROUGH THE DAY...WITH ONLY MODEST IMPROVEMENT...AS DRIER AIR WORKS IN FROM THE NORTHEAST. HOWEVER... FORECAST MODELS ARE IN GOOD AGREEMENT THAT MVFR/IFR CONDITIONS WILL REMAIN ACROSS THE AREA THROUGH TONIGHT...WITH LOW CEILINGS HOLDING ACROSS THE MOUNTAIN AIRPORTS. FURTHER EAST...CLEARING IS EXPECTED...ONLY FOR PATCHES OF FOG TO DEVELOP SHORTLY BEFORE SUNRISE AS THE ATMOSPHERE SATURATES. LITTLE CHANGE IN WIND DIRECTION OR SPEED IS ANTICIPATED. WITH INCREASINGLY DRIER AIR WORKING IN THROUGH THE NIGHT...MVFR AND IFR CONDITIONS WILL ERODE QUICKLY AFTER 9 AM SATURDAY ONCE DAYTIME HEATING INCREASES. DEEPER MOUNTAIN VALLEYS MAY MAINTAIN FOGGY CONDITIONS FOR AN HOUR OR TWO LONGER. VFR CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE DAY. EXTENDED AVIATION DISCUSSION... WEDGE SHOULD ERODE FAIRLY QUICKLY SATURDAY NIGHT IN RESPONSE TO AN UPSTREAM TROUGH. SOME LOW CLOUDS MAY LINGER THROUGH THE MORNING ALONG WITH PATCHY FOG...BUT OVERALL VFR CONDITIONS EXPECTED SAT. A FRONTAL SYSTEM WILL APPROACH SUN WITH -SHRA AND PERHAPS AN ISOLD TSRA WEST OF THE ALLEGHANY FRONT. INSTABILITY IS QUITE LIMITED AND SO IS DEEP MOISTURE. WITH A POSSIBLE TROPICAL SYSTEM DEVELOPING OFF THE COAST AT THE SAME TIME...WE MAY BE IN A STRONG SUBSIDENCE AREA AND SEE LITTLE MORE THAN -SHRA OR SPRINKLES EAST OF THE ALLEGHANY FRONT. EXPECT MOSTLY VFR-PERIODS OF MVFR CIGS SUN-EARLY MON AS THE TROUGH MOVES THROUGH. HIGH PRESSURE BUILDS IN FOR THE FIRST HALF OF NEXT WEEK WITH DRY NW FLOW. THUS...EXPECT MOSTLY VFR CONDITIONS THROUGH THE PERIOD WITH LOCAL EARLY MORNING MVFR-IFR FOG CONDITIONS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...KK SHORT TERM...PW LONG TERM...NF AVIATION...JH/NF

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