Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 120829 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 429 AM EDT SAT APR 12 2014 .SYNOPSIS...
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A WEAK FRONT WAS STALLED FROM NEW JERSEY TO NORTHERN KENTUCKY THIS MORNING. THIS FRONT WILL SINK INTO EASTERN VIRGINIA TODAY BEFORE MOVING BACK NORTH AS A WARM FRONT TONIGHT. A MUCH STRONGER COLD FRONT WILL PUSH THROUGH THE AREA FROM THE WEST ON TUESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 400 AM EDT SATURDAY... SHORT WAVE OVER MOVING INTO ALABAMA AND GEORGIA WITH JUST A FEW SHOWERS LEFT. OTHERWISE HEIGHTS RISING AT 500 MB TODAY AND TONIGHT. AT THE SURFACE WEAK BOUNDARY MOVES BACK NORTH. SURFACE AND LOW LEVEL WINDS BECOME SOUTH TO SOUTHEAST. MAY BE ENOUGH UPSLOPE ALONG THE BLUE RIDGE AND SURFACE CONVERGENCE WHILE THE FRONT IS STILL IN THE FORECAST AREA FOR ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. MODELS WERE FORECASTING CAPES FROM 800-1000 J/KG. BUFKIT SHOWING A DEEP ENOUGH LAYER OF MOISTURE BELOW 10KFT TO SUPPORT SHOWERS. CHALLENGING TO NARROW DOWN WHERE THREAT OF PRECIPITATION IS THIS AFTERNOON...BUT ALLEGHANY HIGHLANDS LOOK LIKE THE MOST LIKELY REGION WITH THE BEST CHANCE OF PRECIPITATION. WITH THE LOSS OF HEATING THIS EVENING ANY REMAINING PRECIPITATION AND CLOUD COVER WILL DISSIPATE. FORECAST AREA WILL BE WELL WITHIN THE WARM AIR SOUTH OF THE FRONT. BOTH MET/MAV GUIDANCE LOOKED REASONABLE.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
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AS OF 330 AM EDT SATURDAY... STRONG SOUTHERLY FLOW BETWEEN HIGH PRESSURE OFFSHORE AND AN APPROACHING COLD FRONT WILL MAKE FOR ANOTHER WARM DAY ON SUNDAY... AS AFTERNOON TEMPERATURES CLIMB INTO THE MID/UPPER 70S ACROSS THE MOUNTAINS AND INTO THE LOW 80S FURTHER EAST. WITH ABUNDANT SUNSHINE TO START THE DAY TO PRODUCE MODEST INSTABILITY...IN ADDITION TO INCREASING ATMOSPHERIC MOISTURE...MAY SEE A FEW SHOWERS DEVELOP ALONG THE RIDGELINES...POSSIBLY AN ISOLATED WEAK THUNDERSTORM. MODELS DO NOT SEEM TOO IMPRESSED WITH CHANCES FOR CONVECTION HOWEVER...SO WILL STICK WITH VERY LOW RAIN CHANCES FOR NOW. MID AND HIGH CLOUDS WILL INCREASE DURING THE EVENING AS THE COLD FRONT PUSHES EAST OF THE MISSISSIPPI RIVER...AND BELIEVE WE MAY SEE A FEW LIGHT SHOWERS OR AREAS OF DRIZZLE DEVELOP ALONG THE BLUE RIDGE TOWARD DAWN TUESDAY. EXPECT OVERNIGHT LOWS TO HOLD IN THE 50S. BELIEVE THAT SHOWER ACTIVITY WILL START MONDAY RATHER HIT AND MISS AND BRIEF IN DURATION...MAINLY AFFECTING THE MOUNTAINS. HOWEVER... SHOWERS WILL BECOME INCREASINGLY WIDESPREAD FROM WEST TO EAST DURING THE AFTERNOON AS WEAK UPPER LEVEL DISTURBANCES PASS ACROSS THE AREA FROM THE SOUTHWEST. MAY SEE A FEW THUNDERSTORMS DEVELOP...ALTHOUGH INSTABILITY DOES NOT APPEAR TO BE THAT IMPRESSIVE DURING THE AFTERNOON DUE TO INCREASED CLOUD COVER AND SHOWER ACTIVITY EARLY IN THE DAY. SLIGHTLY BETTER CHANCES FOR ANY THUNDERSTORMS WILL BE EAST OF THE BLUE RIDGE...ESPECIALLY IF CLOUD COVER MANAGES TO BREAK FOR AN EXTENDED PERIOD OF TIME...BUT IT DOES NOT SEEM LIKELY. AFTERNOON HIGHS WILL CLIMB INTO THE UPPER 60S TO MID 70S AREAWIDE. THE COLD FRONT WILL ENTER OUR SOUTHEAST WEST VIRGINIA AND MOUNTAIN EMPIRE COUNTIES SHORTLY BEFORE SUNRISE TUESDAY MORNING...AND WILL PASS EAST ACROSS OUR AREA...EXITING OUR EASTERN-MOST COUNTIES BY MID AFTERNOON. MODELS ARE STILL TRYING TO RESOLVE THE TIMING OF A WAVE OF LOW PRESSURE RIDING NORTH ALONG THE FRONT FROM THE CAROLINAS ON TUESDAY AFTERNOON...WHICH HAS THE POTENTIAL OF BRINGING PERIODS OF HEAVY RAIN TO THE AREA. THE GFS FORECAST MODEL TENDS TO PUSH COLD FRONTS ACROSS THE MID ATLANTIC A LITTLE TOO QUICKLY...AND THEREFORE WILL STICK CLOSER TO THE SLOWER ECMWF MODEL TIMING...WHICH BRINGS THE WAVE ACROSS THE PIEDMONT DURING LATE AFTERNOON INTO THE EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...BUT MAY NOT SEE RESIDUAL SHOWER ACTIVITY TOTALLY EXIT THE AREA TUESDAY NIGHT AS YET ANOTHER WAVE PASSES NORTH ALONG THE FRONT...THIS ONE OFF THE ATLANTIC COAST.
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&& .LONG TERM /WEDNESDAY THROUGH FRIDAY/...
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AS OF 345 PM EDT FRIDAY... EXPECT HIGH PRESSURE TO CONTROL THE WEATHER PATTERN FOR WEDNESDAY THROUGH FRIDAY. CHANGE IN AIRMASS WILL BRING COOL DRY CONDITIONS TO THE AREA WEDNESDAY AND THURSDAY WITH POTENTIAL FOR A COUPLE OF FROSTY MORNINGS. MODERATING TEMPERATURES WILL BEGIN TOWARD NEXT WEEKEND AS THE AIRMASS BEGINS TO MODIFY.
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&& .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 145 PM EDT FRIDAY... SCATTERED TO BROKEN LAYER OF MID TO HIGH CLOUDS...ALL VFR...MOVING THROUGH THE MOUNTAINS AS A SHORT WAVE TRACK FROM CENTRAL TENNESSEE TO SOUTH CAROLINA. HIGH CONFIDENCE THAT THE PRECIPITATION WITH THIS WAVE WILL STAY SOUTH OF BLF AND BCB. MAY SEE SOME FOG DEVELOP EARLY THIS MORNING AS CLOUDS MOVE OUT OF THE AREA. LOW CONFIDENCE AT KLWB ABOUT FORMATION OF ANY DENSE FOG ALONG THE GREENBRIER RIVER. MODELS INDICATE SOME POTENTIAL FOR A PERIOD OF LOW CONDITIONS IN STRATUS/FOG LATE TONIGHT AS FAR EAST AS KBCB GIVEN RESIDUAL MOISTURE AND A WESTERLY TRAJECTORY AT KBLF. SINCE APPEARS AT LEAST THE SE WVA SITES WILL SEE -SHRA WENT AHEAD AND INCLUDED A LATE NIGHT/DAWN PERIOD OF MVFR AT KBLF. EXPECT ANY LOW CIGS OR VSBYS TO SCOUR OUT BY MID MORNING PROVIDING FOR OVERALL VFR INTO THE AFTERNOON. HOWEVER WITH THE FRONT NEARBY...EXPECT HEATING TO PRODUCE A WIDESPREAD CU FIELD WITH PERHAPS ISOLD SHRA/-TSRA AROUND ESPCLY OVER THE MOUNTAINS BY MID/LATE AFTERNOON. LEFT OUT MENTION OF ANY SHOWERS FOR NOW SINCE COVERAGE WILL BE ISOLATED. WINDS TURN BACK SOUTHERLY AROUND 10 KTS AS THE SURFACE FRONT RECEDES BACK TO THE NORTH. .EXTENDED AVIATION DISCUSSION... SUNDAY AND EARLY MONDAY SHOULD SEE A RETURN TO VFR FOR ALL SITES. BY MONDAY AFTERNOON...A POTENT COLD FRONT WILL ARRIVE FROM THE WEST TO TRIGGER A CHANCE OF SHOWERS AND THUNDERSTORMS...SOME WITH IFR/MVFR CONDITIONS BY EVENING. SHOWERS LOOK TO CONTINUE INTO TUESDAY...WITH WIDESPREAD MVFR/IFR LIKELY AT THIS POINT INTO TUESDAY NIGHT. DRIER AIR LOOKS TO WORK IN BEHIND THE SYSTEM FOR WEDNESDAY ALTHOUGH RESIDUAL MOISTURE AND COLD AIR ALOFT MAY ACT TO KEEP MVFR CIGS AROUND ESPCLY OVER THE MOUNTAINS.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...NF LONG TERM...PM AVIATION...AMS/JH

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