Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 010001 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 801 PM EDT TUE SEP 30 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL BEGIN TO SHIFT OUT OF THE AREA THIS EVENING. A BACK DOOR COLD FRONT WILL SLIDE SOUTH INTO THE AREA WEDNESDAY. A STRONG COLD FRONT ARRIVES FRIDAY. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 345 PM EDT TUESDAY... MOST LOCATIONS ARE OBSERVING MOSTLY SUNNY TO PARTLY CLOUDY SKIES THIS AFTERNOON...WITH THE EXCEPTION OF PORTIONS OF FAR EASTERN CHARLOTTE THROUGH BUCKINGHAM COUNTIES...WHERE A STUBBORN STRATUS DECK HAS BEEN SLOW TO ERODE ALL DAY. AT THE RATE THE STRATUS IS DISSIPATING...FOLKS UNDER THESE CLOUDS SHOULD AT LEAST GET TO SEE A NICE SUNSET. STRONGER HEATING FURTHER WEST IS SUPPORTING VERTICAL CLOUD DEVELOPMENT ALONG THE BLUE RIDGE. ALTHOUGH RADAR IS CLEAR AT THE MOMENT...CANNOT RULE OUT A SHOWER OR TWO DEVELOPING THROUGH 8 PM. OVERNIGHT...MOISTURE WILL CONTINUE TO POOL AHEAD OF AN APPROACHING COLD FRONT. WITH MOSTLY CLEAR SKIES AND LIGHT WINDS EXPECTED... PATCHY FOG WILL AGAIN BE AN ISSUE BEGINNING DURING THE EARLY HOURS OF WEDNESDAY. FOG IS ESPECIALLY LIKELY IN THE MOUNTAIN RIVER VALLEYS...AS WELL AS LOCATIONS EAST OF A DANVILLE TO LYNCHBURG LINE...WHERE CLOUD COVER HELPED LIMIT DRYING OF MOISTURE FROM RAINFALL ON MONDAY EVENING. OVERNIGHT LOWS ARE EXPECTED TO REMAIN MILD...RANGING FROM THE LOW TO MID 50S ACROSS THE MOUNTAINS...TO THE UPPER 50S ACROSS THE SOUTHSIDE. AN AREA OF LOW PRESSURE SOUTH OF THE GREAT LAKES WILL DROP SOUTHWARD INTO THE MID ATLANTIC WEDNESDAY MORNING...BRINGING A COLD FRONT TO THE INTERSTATE 64 CORRIDOR BY SUNRISE...WITH THE FRONT CONTINUING TO DRIFT SOUTH THROUGH THE DAY. BEST INSTABILITY... WHICH OVERALL IS VERY MODEST...WILL BE LOCATED IN THE VICINITY OF THE LOW...AND WILL SUPPORT SPOTTY SHOWER ACTIVITY FROM THE ALLEGHANY HIGHLANDS INTO THE PIEDMONT. EVEN WITH THE FRONT SINKING ACROSS THE AREA...TRULY COOLER AIR WILL REMAIN TO THE NORTH. EXPECT AFTERNOON HIGHS TO RANGE FROM THE LOW TO MID 70S ALONG THE INTERSTATE 64 CORRIDOR AND THE NORTH CAROLINA MOUNTAINS...TO THE LOW 80S ACROSS THE NORTH CAROLINA PIEDMONT. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 257 PM EDT TUESDAY... A CLOSED LOW WILL MOVE OFF THE NORTHEAST COAST WEDNESDAY AFTERNOON. NORTHERLY FLOW ON THE BACK SIDE OF THIS LOW WILL HELP PUSH A WEAK COOL FRONTAL BOUNDARY SOUTH OF THE AREA WEDNESDAY NIGHT. THIS WEDGE OF HIGH PRESSURE WILL HAVE LIGHT EASTERLY FLOW AND...COMBINED WITH MOISTURE...LOW CLOUDS/FOG/DRIZZLE ARE LIKELY ALONG AND EAST OF THE BLUE RIDGE INTO AT LEAST THURSDAY MORNING. THROUGH THE DAY THURSDAY...AN UPPER LEVEL RIDGE AXIS WILL MOVE OVER THE EAST COAST AND WITH THE HELP OF WESTERLY FLOW...FOG AND STRATUS DECK SHOULD SCOUR BY THE AFTERNOON. ISENTROPIC LIFT MAY REMAIN OVER THE PIEDMONT LONGER WITH LOW CLOUDS LINGERING WELL INTO THE AFTERNOON...POSSIBLY THE EVENING. A COLD FRONT WILL APPROACH THE AREA THURSDAY NIGHT. INCREASED MIXING OVER THE REGION WILL ERODE WHAT IS LEFT OF THE WEDGE THROUGH THE NIGHT AND INTO FRIDAY MORNING. THE COLD FRONT WILL MOVE QUICKLY ACROSS THE EASTERN HALF OF THE USA FRIDAY AND FRIDAY NIGHT. AROUND SUNRISE FRIDAY...THE FRONT IS OVER THE MISSISSIPPI VALLEY. AROUND SUNSET...THE FRONT IS OVER THE OHIO/TENNESSEE VALLEYS MOVING INTO THE APPALACHIAN MOUNTAINS. THIS FRONT WILL BE ALONG THE EASTERN SEA BOARD BY SUNRISE SATURDAY MORNING. MODEL TIMING OF PREFRONTAL SHOWERS REMAINS CONSISTENT... OVER THE MOUNTAINS IN THE MORNING...ENTIRE FORECAST AREA IN THE AFTERNOON...EXITING THE PIEDMONT DURING THE EVENING. INSTABILITIES ARE NOT TOO IMPRESSIVE WITH THIS STRONG FRONT...SOME MAYBE LUCKY TO HEAR A FEW RUMBLES OF THUNDER. RAINFALL AMOUNTS WILL RANGE FROM A QUARTER TO HALF OF AN INCH /0.25-0.50/. BEHIND THE FRONT...A TIGHT PRESSURE GRADIENT WILL BRING BREEZY AND GUSTY CONDITIONS ALONG RIDGE TOPS...WITH STRONGER WINDS MIXING TO THE LOWER LEVELS DURING THE DAY SATURDAY. WEST-NORTHWEST FLOW MAY KEEP CLOUDS OVER THE MOUNTAINS FRIDAY NIGHT WITH SOME PATCHY DRIZZLE ALONG WESTERN SLOPES. DOWNSLOPE FLOW EAST OF THE BLUE RIDGE WILL ERODE CLOUDS AND BE CLEAR BY SUNRISE. WITH EASTERLY FLOW AND A WEAK WEDGE IN THE EAST...UNIFORM TEMPERATURES IN THE 70S ARE EXPECTED THURSDAY. SINCE SHOWERS WILL OVERSPREAD THE MOUNTAINS DURING THE MORNING...HIGH TEMPERATURES MAY REACH 70F. LATER ARRIVAL OF SHOWERS AND CLOUDS ACROSS THE FOOTHILLS AND PIEDMONT COULD HAVE TEMPERATURES PEAKING OUT IN THE UPPER 70S...POSSIBLY LOWER 80S TOWARDS SOUTHSIDE FRIDAY AFTERNOON. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 310 PM EDT TUESDAY... A COLD FRONT WILL BE ALONG THE EAST COAST SATURDAY MORNING WITH DRIER COOLER AIR MOVING IN ON WEST-NORTHWEST FLOW. HIGH PRESSURE ALONG THE GULF AND LOW PRESSURE OVER NEW ENGLAND WILL PLACE A PRESSURE GRADIENT OVER THE AREA SATURDAY. BREEZY AND GUSTY CONDITIONS THROUGH SATURDAY EVENING...THEN HIGH PRESSURE BUILDS NORTH INTO THE REGION. HIGH PRESSURE WILL CONTINUE TO TRACK EAST ALONG THE GULF OVER THE WEEKEND...SHUTTING DOWN ANY MOISTURE RETURNING INTO THE REGION. MODELS ARE MOVING A MID LEVEL DISTURBANCE ACROSS THE OHIO VALLEY MONDAY NIGHT INTO TUESDAY. AS THIS DISTURBANCE APPROACHES THE AREA...IT WILL BE HARD-PRESSED TO PRODUCE WIDESPREAD SHOWERS DUE TO A LACK OF MOISTURE RECOVERY. TEMPERATURES WILL RUN 5F-10F COOLER THAN NORMAL OVER THE WEEKEND. TEMPERATURES BEGIN TO MODERATE TOWARDS NORMAL MONDAY AND TUESDAY. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 800 PM EDT TUESDAY... SATELLITE IMAGERY INDICATES MOSTLY CLEAR SKIES ACROSS THE REGION THIS EVENING...ASIDE FROM A LITTLE STRATOCU ACROSS THE NORTH CAROLINA PIEDMONT. SURFACE OBSERVATIONS INDICATE A COLD FRONT SINKING SLOWLY SOUTHWARD FROM THE OHIO RIVER. MOISTURE CONTINUES TO POOL ACROSS THE AREA AHEAD OF THE FRONT...AS EVIDENCED BY RISING DEWPOINT TEMPERATURES FOR MANY LOCATIONS. OVERNIGHT...MAIN CONCERN WILL BE THE REDEVELOPMENT OF PATCHY FOG ACROSS THE AREA. WHILE MANY LOCATIONS HAVE HAD THE OPPORTUNITY TO DRY TODAY FROM RAINFALL THAT OCCURRED ON MONDAY...THE LIGHT WINDS AND MOSTLY CLEAR SKIES...COMBINED WITH SOME RESIDUAL MOISTURE... WILL MAKE FOR AT LEAST PATCHY FOG. MOST LIKELY LOCATIONS WILL BE KLYH/KLWB/KBCB DUE TO ALREADY NEAR SATURATION CONDITIONS. KDAN IS ALSO LIKELY TO EXPERIENCE FOG...BUT MAY TAKE UNTIL CLOSER TO SUNRISE WEDNESDAY. NOT NEARLY AS CONFIDENT FOR FOG AT KBLF/KROA. THE COLD FRONT WILL ENTER THE INTERSTATE 64 CORRIDOR BY SUNRISE WEDNESDAY...AND SINK SOUTHWARD THROUGH THE DAY. DO NOT EXPECT MUCH MORE THAN A NORTHERLY WIND SHIFT...AS SPEEDS WILL REMAIN LIGHT. AFTER MORNING FOG BURNS OFF...EXPECT MAINLY VFR CONDITIONS. SHOWER ACTIVITY WILL DEVELOP NEAR THE FRONT WITH AFTERNOON HEATING...MOST LIKELY IMPACTING KLWB/KLYH/KDAN WITH HIT AND MISS RAINFALL. SHOULD REMAIN MOSTLY SHOWER ACTIVITY DUE TO MODEST INSTABILITY...ALTHOUGH AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT. EXTENDED AVIATION DISCUSSION... VFR CEILINGS AND VISIBILITIES CAN BE EXPECTED FOR THURSDAY... ALTHOUGH LOCALIZED PERIODS OF SUB-VFR ARE LIKELY TO OCCUR FOR THE MOUNTAIN VALLEY AIRPORTS KBCB/KLWB AGAIN THURSDAY MORNING. THE NEXT THREAT FOR SUB VFR CEILINGS AND VISIBILITIES WILL COME WITH A STRONGER FRONTAL PASSAGE ON FRIDAY. THIS FRONT WILL LIKELY BE ASSOCIATED WITH A LINE OF SHOWERS AND FEW THUNDERSTORMS...SWEEPING WEST TO EAST ACROSS THE REGION. NORTHWEST WINDS WILL BE GUSTY BEHIND THE FRONT FRIDAY NIGHT INTO SATURDAY. SATURDAY SHOULD BE VFR ALTHOUGH SOME UPSLOPE MVFR CEILINGS ARE POSSIBLE AT KLWB AND ESPECIALLY KBLF. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF/PM NEAR TERM...NF/PM SHORT TERM...RCS LONG TERM...RCS AVIATION...NF/PM

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