Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 200527 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 127 AM EDT SUN APR 20 2014 .SYNOPSIS... SLOW MOVING LOW PRESSURE ALONG THE SOUTHEAST COAST WILL DRIFT EAST AND OFFSHORE TONIGHT. STRONG HIGH PRESSURE WILL BUILD INTO THE AREA FROM OFF THE MID ATLANTIC COAST SUNDAY PROVIDING A RETURN OF DRIER AIR INTO EARLY NEXT WEEK. ANOTHER COLD FRONT ARRIVES LATER TUESDAY WITH THE NEXT CHANCE OF SHOWERS AND STORMS. && .NEAR TERM /THROUGH TODAY/... AS OF 815 PM EDT SATURDAY... LATEST RADAR TRENDS SUPPORTING EARLIER GFS MODEL DEPICTION OF EXPANDING AREA OF PRECIPITATION NORTHEAST TO AS FAR NORTH AS THE NC/VA STATE LINE EARLY THIS EVENING...BEFORE BEING SHUNTED OFF TO THE EAST DURING THE EARLY MORNING HOURS AS UPPER DIFFLUENCE AND ASSOCIATED UPWARD VERTICAL MOTION FIELDS THROUGH MOIST MID LAYER MOVES AWAY FROM THE BLACKSBURG FORECAST AREA. AS A RESULT...JUST ISSUED QUICK UPDATE TO BOOST THREAT OF PRECIPITATION ACROSS THE FOOTHILLS AND PIEDMONT OF NORTH-CENTRAL NC FOR MUCH OF THE REST OF THIS EVENING. HOWEVER...CONTINUED ENTRAINMENT OF DRIER AIR IN LOWER LEVELS SHOULD ENSURE THAT OVERALL PRECIPITATION AMOUNTS ALONG AND SOUTH OF THE VA STATE LINE REMAIN LIGHT...GENERALLY LESS THAN ONE TENTH OF AN INCH. REST OF FORECAST FOR TONIGHT STILL APPEARS ON TRACK...SO NO ADDITIONAL ADJUSTMENTS WERE NEEDED. AS OF 215 PM EDT SATURDAY... DEFORMATION TYPE AXIS AROUND THE UPPER LOW NOW OVER SE GA REMAINS PERSISTENT ATTM WITH A LINGERING BAND OF RAIN MOSTLY OVER NW NC WHERE FEED OF LOW LEVEL EASTERLY FETCH REMAINS BEST. HOWEVER FARTHER NORTH...DRYING CONTINUES UNDER A MORE PREDOMINANT NE FLOW WITH QUITE A DROPOFF IN MOISTURE CROSSING THE VA/NC BORDER. UPPER LOW WILL AGAIN BE SLOW TO MOVE OVERNIGHT WITH THIS FEATURE BEING BLOCKED EAST TO OFF THE SE COAST BY SUNDAY MORNING. MODELS CONTINUE TO STRUGGLE WITH THE LEFTOVER DEFORMATION BAND OVERNIGHT IN JUST HOW LONG AXIS OF DEEPER MOISTURE WILL REMAIN AND WHETHER OR NOT IT JOGS BACK NORTH AS ANOTHER WAVE PIVOTS IN FROM THE WEST. LATEST GFS AGAIN REMAINS WETTEST IN KEEPING PCPN GOING FROM NW NC INTO SOUTHSIDE VA...WHILE THE EC/HRRR LESS WITH ONLY SPOTTY RESIDUAL -RA...AND MOST OTHER SOLUTIONS DRY. GIVEN CURRENT TRENDS WILL CONTINUE TO LEAN TOWARD THE GFS/ENSEMBLE BLEND AND KEEP HIGHER POPS FAR SOUTHERN SECTIONS INTO THIS EVENING WHICH MAY BE OVERDONE GIVEN CURRENT DRY ADVECTION. OTRW MIXTURE OF HIGH/MID CLOUDS LIKELY WITH DEEPER MOISTURE PERHAPS PUSHING BACK NORTH ACROSS THE EAST OVERNIGHT WITH THE NEXT IMPULSE ALOFT. KEPT LOW TEMPS SIMILAR TO MOS EXCEPT COLDER NW VALLEYS WHERE RADIATIONAL COOLING SHOULD BE BEST. UPPER LOW FINALLY SHIFTS FAR ENOUGH OFFSHORE DURING SUNDAY TO ALLOW A DRIER EASTERLY FLOW TO DEVELOP AS HIGH PRESSURE ALONG THE MID ATLANTIC COAST STRENGTHENS UNDER GRADUAL SHORTWAVE RIDGING ALOFT. THIS SHOULD ALLOW SKIES TO CLEAR BY AFTERNOON PER MODEL RH CROSS SECTIONS WITH HIGHS BOUNCING BACK INTO THE 60S TO AROUND 70 GIVEN HEATING OF DRY AIR AND SLIGHT 85H WARMING. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... AS OF 200 PM EDT SATURDAY... MODERATING TEMPERATURES ARE EXPECTED THROUGH AT LEAST MONDAY NIGHT AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDS OVER THE APPALACHIANS. LOW LEVEL SOUTHERLY WARM AIR ADVECTION AND PLENTY OF SUNSHINE WILL CONTRIBUTE TO THIS. HOWEVER...ONE LAST COOL NIGHT IS EXPECTED SUNDAY NIGHT. SOME PATCHY FROST WILL BE POSSIBLE FOR A COUPLE OF HOURS AROUND SUNRISE FOR PARTS OF THE NEW RIVER...GREENBRIER AND SOUTHERN SHENANDOAH VALLEYS. BY LATE IN THE DAY MONDAY...CLOUD COVER WILL START TO OVERSPREAD THE AREA FROM WEST TO EAST IN ADVANCE OF AN APPROACHING COLD FRONT. THIS TREND WILL CONTINUE INTO MONDAY NIGHT WITH MOSTLY CLOUDY TO CLOUDY SKIES ACROSS THE ENTIRE AREA BY SUNRISE TUESDAY. WITH THE CLOUDS WILL COME INCREASING CHANCE OF SHOWERS LATE MONDAY NIGHT THROUGH THE DAY TUESDAY AS THE FRONT APPROACHES AND THEN CROSSES THE REGION. MODEL CONVECTIVE PARAMETERS STILL OFFER THE POTENTIAL FOR THUNDERSTORMS DURING THE DAY ON TUESDAY. DESPITE MORE CLOUD COVER AND THE PRECIPITATION...THE STRENGTH OF THE WARM AIR ADVECTION WILL HELP TEMPERATURES ON TUESDAY BE A FEW DEGREES WARMER THAN THOSE OF MONDAY. A MIX OF MID 60S TO LOWER 70S LOOKS PROMISING ACROSS THE AREA. TUESDAY NIGHT...COVERAGE OF SHOWERS WILL BE ON THE DECREASE AS THE FRONT EXITS THE REGION. BY MIDNIGHT...ALL THAT IS EXPECTED TO REMAIN IS A SMALL REGION OF ISOLATED TO SCATTERED SHOWERS ACROSS THE PREFERRED UPSLOPE AREAS OF SOUTHEAST WEST VIRGINIA THANKS TO GUSTY NORTHWEST WINDS IN THE WAKE OF THE COLD FRONT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 1245 PM EDT SATURDAY... ON WEDNESDAY...WE STILL EXPECT WINDS TO BE ON THE GUSTY SIDE DURING THE MORNING HOURS IN THE WAKE OF THE TUESDAY/TUESDAY NIGHT COLD FRONT. WHILE THERE WILL STILL BE SOME UPSLOPE CLOUDS ACROSS SOUTHEAST WV IN THE MORNING...THE REMAINDER OF THE REGION WILL BE MOSTLY SUNNY TO SUNNY. CLOUDS WILL BE ON THE DECREASE ACROSS SE WV DURING THE DAY AS WINDS WEAKEN AS DRIER HIGH PRESSURE BUILDS TOWARD THE REGION. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE AREA WEDNESDAY NIGHT AND BECOME SITUATED OFF THE EAST COAST BY FRIDAY. CONCURRENTLY...AN UPPER LEVEL RIDGE WILL BUILD OVER THE APPALACHIANS WHILE STRENGTHENING SOUTHWEST FLOW ALLOWS FOR GOOD WARM AIR ADVECTION. EXPECT WEDNESDAY NIGHT THROUGH THURSDAY TO BE A PERIOD OF NO PRECIPITATION AND MODERATING TEMPERATURES. A COLD FRONT WILL APPROACH THE AREA THURSDAY NIGHT AND CROSS THE REGION FRIDAY INTO FRIDAY NIGHT. ANTICIPATE TEMPERATURES TO REMAIN MILD IN ADVANCE OF THE FRONT THURSDAY NIGHT INTO FRIDAY...BUT WITH INCREASING CLOUD COVER AND CHANCES OF SHOWERS. MODEL GUIDANCE CURRENTLY OFFERS THE POTENTIAL FOR SOME CONVECTIVE WEATHER WITH THE PASSAGE OF THE FRONT. HAVE INCLUDED A SLIGHT CHANCE OF THUNDERSTORMS ACCORDINGLY ON FRIDAY. COOLER AIR ARRIVES FRIDAY NIGHT INTO SATURDAY...WHILE LINGERING RAIN SHOWERS DECREASE IN COVERAGE...ENDING LAST ACROSS SOUTHEAST WEST VIRGINIA WHERE UPSLOPE CONDITIONS WILL MAINTAIN THE PRECIPITATION THE LONGEST. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/...
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AS OF 120 AM EDT SUNDAY... A LOW LEVEL NORTHEAST FLOW HAS ALLOWED DRIER AIR TO INFILTRATE THE FORECAST AREA...KEEP VFR CONDITIONS AT ALL TAF SITES WHICH SHOULD CONTINUE THROUGH 06Z MONDAY. A FEW SPRINKLES OR PATCHY LIGHT RAIN MAY CLIP THOSE AREAS FROM KDAN SOUTHWARD THIS MORNING AS A WEAK UPPER LEVEL IMPULSE DRIFTS ACROSS NORTHERN NC. AS THE UPPER LEVEL LOW OFF THE SOUTHEAST U.S. COAST THIS MORNING CONTINUES TO PUSH EAST AND UPPER LEVEL RIDGING BUILDS...CANOPY OF HIGH/MID LEVEL CLOUDS WILL CLEAR FROM WEST TO EAST DURING THE DAY SUNDAY. DRY AIR ALOFT MIXING DOWN TO THE SURFACE WITH CLEARING SKIES MAY BRING SOME LOCALIZED WIND GUSTS TO 15-20KTS BETWEEN 15-23Z SUNDAY. EXTENDED AVIATION DISCUSSION... WITH HIGH PRESSURE IN PLACE THROUGH MONDAY...VFR CONDITIONS ARE EXPECTED. THE NEXT COLD FRONT APPROACHES MONDAY NIGHT WITH MORE SHOWERS AND POSSIBLE THUNDERSTORMS...WITH LOCALIZED MVFR FLIGHT RESTRICTIONS ON TUESDAY. THE FRONT EXITS TUESDAY NIGHT...RESULTING IN A RETURN TO VFR WEATHER WEDNESDAY...EXCEPT FOR THE POTENTIAL OF SOME MVFR CIGS OVER THE FAR WESTERN UPSLOPE SITES IN SE WEST VA. HIGH PRESSURE BUILDS IN FOR THURSDAY...WITH WIDESPREAD VFR LIKELY.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/RAB NEAR TERM...JH/WERT SHORT TERM...DS LONG TERM...DS AVIATION...PH/WERT

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