Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 091124 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 724 AM EDT WED JUL 9 2014 .SYNOPSIS...
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A SLOW MOVING COOL FRONT WILL SLIDE SOUTHEAST INTO THE MOUNTAINS TODAY...BEFORE DRIFTING INTO NORTH CAROLINA AND STALLING OVERNIGHT. WEAK HIGH PRESSURE WILL FOLLOW THE FRONT FOR THURSDAY INTO SATURDAY. A MUCH STRONGER COLD FRONT WILL BE PASSING THROUGH THE REGION NEXT MONDAY AND TUESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 230 AM EDT WEDNESDAY... WEAK FRONT ALONG THE OHIO RIVER EARLY THIS MORNING WILL SLIDE SE INTO THE AREA THIS AFTERNOON BEFORE STALLING JUST SOUTH OF THE AREA LATE TONIGHT. RESIDUAL AXIS OF DEEPER MOISTURE STRUNG OUT AHEAD OF THE BOUNDARY WILL BE THE MAIN CONCERN FOR ADDED CONVECTION ESPCLY OVER THE FAR WEST EARLY THIS MORNING...AND THEN BLUE RIDGE AND POINTS SOUTH/EAST BY MID AFTERNOON. HOWEVER IFFY AS TO EXACTLY WHERE THE BEST COVERAGE WILL BE THIS AFTERNOON GIVEN CLOUDS/SHRA AROUND THIS MORNING AND THEN DRYING ALOFT PER VAPOR LOOP FROM THE NW LATER IN THE AFTERNOON. GUIDANCE HAS THE BEST LIFT OVER THE SOUTH/SE THIS AFTERNOON WHERE THE BETTER HEATING AND LOW LEVEL BACKED FLOW COINCIDES WITH THE RIBBON OF LEFTOVER PRE- FRONTAL MOISTURE. THIS LOOKS TO POSSIBLY INIT ALONG THE CENTRAL/SOUTHERN BLUE RIDGE PER FORECAST 85H THETA-E RIDGING AND PERHAPS ALONG THE GRADIENT OF DIFFERENTIAL HEATING FROM WESTERN CLOUDS TO STRONGER HEATING OUT EAST. WINDS ALOFT ARE WEAKER...BUT STILL UNIDIRECTIONAL THIS AFTERNOON AS SUPPORT ALOFT LACKING... ALTHOUGH LAPSES GIVEN HEATING REMAIN STEEP...WHILE CAPES PUSH 1500-2000 J/KG PIEDMONT PROVIDED ENOUGH INSOLATION AHEAD OF THE FRONT. THIS SUPPORTS INCREASING CHANCE POPS TO SOME DEGREE EASTERN HALF THIS AFTERNOON...AND ALONG THE BLUE RIDGE WHERE OLD OUTFLOW MAY LEAD TO MORE STORM CLUSTERS...PER LATEST HRRR/HIRES-ARW OUTPUT EARLY BEFORE DRYING ALOFT AND LOW LEVEL WEST WINDS WIN OUT. THUS WILL KEEP SOME SEVERE MENTION IN THE HWO FOR THIS AFTERNOON AS POPS MAY NEED TO GO HIGHER PENDING INSTABILITY LATER ON. HIGHS A BIT TRICKY GIVEN EXTENSIVE EARLY MORNING CLOUDS AND SLIGHT COOLING ALOFT. HOWEVER APPEARS ENOUGH OF A WEST WIND TO HELP SCOUR CLOUDS OUT OF THE EAST...WITH SOME BREAKS ESPCLY NW SO UPPED TEMPS A FEW DEGREES BUT OVERALL STILL AOB MOS OUTSIDE OF THE SE. BOUNDARY SINKS ACROSS AND JUST SOUTH OF THE REGION LATE TONIGHT BUT MAY BE SLOWER THAN GUIDANCE GIVEN A WEAK WAVE ALONG THE FRONT. THIS SHOULD BE ENOUGH TO KEEP A FEW SHRA/TSRA BANDS GOING OVER THE FAR SOUTH/SE MAINLY BEFORE MIDNIGHT WITH GRADUAL DRYING TAKING PLACE OVER THE NW THIRD WHERE EVEN DEWPOINTS SHOULD FALL A BIT. THEREFORE STAYED WITH CHANCE POPS MAINLY SE OF A LYH TO HLX LINE THIS EVENING AND CUT TO JUST ISOLATED MENTION FAR SOUTHERN COUNTIES LATE. OTRW PARTLY TO MOSTLY CLOUDY WITH MORE CLEARING WORKING IN ACROSS THE NW LATE WHICH SHOULD ALLOW A RANGE IN LOWS FROM THE SLIGHTLY COOLER UPPER 50S/LOW 60S NW TO THE STILL MUGGY MID/UPPER 60S SE.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 310 AM EDT WEDNESDAY... AN UPPER LEVEL TROUGH WILL REMAIN OVER THE EAST COAST THROUGH THE PERIOD. MEANWHILE...A SURFACE HIGH PRESSURE SYSTEM WILL DRIFT EAST FROM THE GREAT LAKES TO NEW ENGLAND. ACROSS THE SOUTHEAST...A STALLED FRONTAL BOUNDARY IS EXPECTED TO MOVE NORTH AND WEST...EVENTUALLY BUCKLING BACK OVER THE FORECAST AREA ON THURSDAY...AS A SURFACE REFLECTION DEVELOPS OVER THE CAROLINAS. THIS BOUNDARY AND ASSOCIATED SURFACE WAVES WILL BRING SHOWERS ALONG AND EAST OF THE BLUE RIDGE...PARTICULARLY THE PIEDMONT THURSDAY...AND TO SOUTHSIDE FRIDAY. INSTABILITIES WILL INCREASE FROM EAST TO WEST THURSDAY AFTERNOON TO BRING A CHANCE FOR THUNDERSTORMS ACROSS THE PIEDMONT. DESPITE THE INCREASE IN MOISTURE AND INSTABILITIES...STORMS ARE NOT EXPECTED TO BECOME SEVERE. AREAL COVERAGE OF SHOWERS WILL DECREASE THURSDAY EVENING WITH LOSE OF HEATING AND THE FRONTAL BOUNDARY DRIFTING EAST. LESS ACTIVITY AND AREAL COVERAGE OF SHOWERS FRIDAY. BEING MOSTLY BEHIND THE FRONT AND HAVING AN EASTERLY FLOW AND ABUNDANT CLOUD COVER WILL KEEP THURSDAY AFTERNOON TEMPERATURES BELOW NORMAL. EASTERLY FLOW REMAINS FRIDAY BUT MORE SUN IS EXPECTED TO HAVE TEMPERATURES APPROACHING NORMAL LEVELS ONCE AGAIN. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 310 PM EDT TUESDAY... DAILY THREAT OF WIDELY SCATTERED TO SCATTERED DIURNALLY DRIVEN SHOWERS/THUNDERSTORMS APPEARS TO BE IN THE OFFING DURING THE LONG TERM PERIOD AS A SERIES OF WEAK SHORT WAVES IN RELATIVELY ZONAL FLOW FORECAST TO MOVE EAST THROUGH THE BLACKSBURG FORECAST AREA. FIRST WAVE EXPECTED ON SATURDAY...WITH SECOND WAVE ON SUNDAY...TO BE FOLLOWED BY MUCH MORE SUBSTANTIAL WAVE IN MONDAY/TUESDAY TIMEFRAME AS EASTERN CANADIAN UPPER LOW AMPLIFIES AND RETROGRESSES SOUTHWESTWARD INTO THE UPPER GREAT LAKES AREA. DEEPENING VERY BROAD UPPER TROF/CLOSED SYSTEM WILL SUPPORT A GOOD PUSH OF UNUSUALLY COOL AIR INTO THE MID APPALACHIAN AND MID ATLANTIC REGION BY THE END OF THE LONG TERM PERIOD...BUT WITH THE COOLEST PORTION OF THE AIRMASS TO ARRIVE JUST OUTSIDE OF THIS FORECAST PERIOD...ON WEDNESDAY. AT LEAST THROUGH MONDAY...EXPECT RELATIVELY SEASONAL TEMPERATURES WITH NO SIGNIFICANT DAY TO DAY CHANGES IN AIRMASS. HIGHS SHOULD RANGE FROM THE MID 70S TO LOWER 80S ACROSS THE HIGHER ELEVATIONS TO UPPER 80S TO LOWER 90S ACROSS THE PIEDMONT. OVERNIGHT LOWS SHOULD BE GENERALLY IN THE 60S...BUT WITH SOME UPPER 50S POSSIBLE ACROSS THE HIGHEST ELEVATIONS AND IN THE DEEPER MOUNTAIN VALLEYS. TEMPERATURES SHOULD BEGIN TRENDING DOWNWARD ABOUT 5F DAILY BEGINNING TUESDAY AS LEADING EDGE OF SUCCESSIVE WAVES OF COOLER AIR BEGIN TO IMPINGE UPON THE AREA. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 702 AM EDT WEDNESDAY... COMMS ISSUES REMAIN AT KDAN DESPITE AN INTERMITTENT RETURN OF OBSERVATION DATA. AMD NOT SKED CONTINUED IN THE TAF. WIDELY SCATTERED SHOWERS AND ISOLATED TSRA CONTINUE TO WORK EAST THROUGH PARTS OF THE REGION THIS MORNING AND APPEARS THIS WILL PREVAIL UNTIL MID MORNING WHEN MIXING CAUSES COVERAGE TO DECREASE. THESE SHOWERS MAY BRING A PERIOD OF MVFR TO KLWB AND KBLF SO WILL TEMPO IN SOME LOWER VSBYS ESPCLY AROUND KLWB WHERE BRIEF IFR MAY OCCUR IN THE NEXT HOUR OR TWO. ELSW EXPECTING SHRA TO BE QUITE LIGHT WITH VFR CONTINUING UNDER MAINLY MID DECK. FRONT WILL BE MOVING SLOWLY INTO THE AREA LATER TODAY WITH A MIX OF MVFR TO VFR CIGS THROUGH MID OR LATE MORNING BEFORE THINGS SLOWLY IMPROVE TO VFR MOST SPOTS BY MIDDAY. BEST CHANCE FOR MVFR/IFR THUNDERSTORMS THIS AFTERNOON WILL BE IN AREAS ALONG AND EAST OF THE BLUE RIDGE WHERE THE INSTABILITY WILL COMBINE WITH OUTFLOW FROM PREVIOUS STORMS AND DEEPER MOISTURE. HOWEVER CANT TOTALLY RULE OUT SHRA/TSRA DEVELOPING BY LATE MORNING WEST OF THE BLUE RIDGE GIVEN MOISTURE AND ONSET OF HEATING. THUS GOING WITH A VCTS/VCSH FOR MOST SPOTS THIS AFTERNOON WITH COVERAGE MORE ISOLATED OVER THE NW. DRY AIR ALOFT SHOULD START TO ARRIVE LATER IN THE AFTERNOON ALLOWING FOR LESS CONVECTION NW THIRD WHERE WILL CUT OUT PRECIP MENTION FROM KROA AND POINTS NW BY MID AFTERNOON. WINDS SHOULD BE LIGHTER AND MORE WESTERLY TODAY JUST AHEAD OF THE FRONT WITH A STEADY WEST/SW COMPONENT AT 5-15 KTS. EXTENDED AVIATION... THE COLD FRONT WILL FINALLY PUSH THROUGH THE REGION LATER TONIGHT BEFORE STALLING JUST TO THE SOUTH. THIS BOUNDARY WILL LINGER ACROSS SOUTHERN/EASTERN AREAS THROUGH THE END OF THE WEEK WITH IMPULSES RIDING ALONG IT. THIS WILL KEEP UNSETTLED CONDITIONS AT TAF SITES THROUGH THE END OF THE WEEK. EXPECT DIURNAL TRENDS FOR AFTERNOON CONVECTIVE PRECIPITATION WITH ASSOCIATED MVFR OR LOWER CONDITIONS... ESPECIALLY FOR KDAN/KLYH ON THURSDAY BUT LIKELY LESS CONVECTION ACROSS THE AREA ON FRIDAY AND PERHAPS SATURDAY AS WEAK HIGH PRESSURE SLIDES IN FROM THE NORTH. MOISTURE AND MORE WIDESPREAD SHRA/TSRA LIKELY TO RETURN FOR THE END OF THE WEEKEND AS THE FRONT RETURNS NORTH RESULTING IN PERIODS OF MVFR CONDITIONS. OTRW PATCHY FOG RESULTING IN LOCAL MVFR TO IFR CONDITIONS LIKELY DURING THE LATE NIGHTS AND EARLY MORNINGS ESPCLY VALLEY LOCATIONS AND WHERE EARLIER AFTERNOON RAINFALL OCCURRED.
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&& .EQUIPMENT... AS OF 330 AM EDT WEDNESDAY... COMMUNICATIONS OUTAGE CONTINUES WITH KDAN ASOS NOT TRANSMITTING. THE FAA IS AWARE OF THE OUTAGE AND WILL BE WORKING ON IT...BUT NO ESTIMATED TIME OF WHEN IT WILL BE WORKING AGAIN. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/JH NEAR TERM...JH SHORT TERM...RCS LONG TERM...AMS/WERT AVIATION...AMS/JH/KK EQUIPMENT...WP

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