Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280602 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 202 AM EDT TUE JUL 28 2015 .SYNOPSIS... AHEAD OF A COLD FRONT...SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON AND EVENING THROUGH WEDNESDAY. A COLD FRONT WILL ARRIVE THURSDAY WITH THE NEXT CHANCE FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS. WEAK HIGH PRESSURE AND MOSTLY DRY WEATHER IS EXPECTED BY THE WEEKEND. OTHERWISE...IT WILL REMAIN WARM AND HUMID FOR THE NEXT SEVERAL DAYS. && .NEAR TERM /THROUGH TODAY/... AS OF 1155 PM EDT MONDAY... SHOWERS AND THUNDERSTORMS HAVE DEVELOP ALONG AN AXIS FROM SOUTHERN ALLEGHENY COUNTY VIRGINIA TO DANVILLE. SIMILAR TO MOST OF THE STORMS MONDAY AFTERNOON AND EVENING...STORMS WERE SLOW MOVING AND WILL PRODUCE HEAVY RAIN. HAVE ADJUSTED PROBABILITY OF PRECIPITATION TO ACCOUNT FOR THE LATEST RADAR TRENDS. FLOW IS RELATIVELY WEAK ALOFT BUT ENOUGH ENERGY AND INSTABILITIES REMAINS OVERNIGHT TO KEEP SHOWERS ACTIVITY ONGOING UNTIL THE EARLY MORNING HOURS TUESDAY. THERE SHOULD BE A LULL IN ACTIVITY TUESDAY MORNING...THEN ANOTHER WAVE ROUNDING THE UPPER LEVEL RIDGE OVER THE SOUTHERN PLAINS IS EXPECTED TO TRACK ACROSS THE REGION TUESDAY AFTERNOON. LESS CLOUD COVER IS EXPECTED TOMORROW...THEREFORE WE SHOULD SEE TEMPERATURES WARMING TO NEAR NORMAL WITH MID 80S WEST TO THE LOWER 90S EAST. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... AS OF 305 PM EDT MONDAY... SCATTERED DIURNAL SHOWERS AND THUNDERSTORMS WILL DIMINISH TUESDAY EVENING INTO TUESDAY NIGHT. THE COMBINATION OF THE DIFFUSE FRONTAL BOUNDARY AND DIFFERENTIAL HEATING ACROSS THE HIGHER ELEVATIONS SHOULD FOCUS THE BEST CHANCE OF CONVECTION ACROSS SOUTHERN PORTIONS OF FORECAST AREA...ESPECIALLY NORTHWEST NORTH CAROLINA. MOST OF THE CONVECTION WILL END BEFORE MIDNIGHT. PARTLY TO MOSTLY CLOUDY SKIES WITH AREAS OF FOG EXPECTED TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW TEMPERATURES TUESDAY NIGHT WILL BE MILD WITH READINGS FROM THE MID 60S IN THE MOUNTAINS TO AROUND 70 DEGREES. A COLD FRONT WILL APPROACH FROM THE OHIO VALLEY ON WEDNESDAY. SOLAR HEATING AND LINGERING SFC BOUNDARIES WILL RESULT SCATTERED DIURNAL SHOWERS AND THUNDERSTORMS...WITH BEST POTENTIAL WEST OF INTERSTATE 77. HIGH TEMPERATURES WEDNESDAY AFTERNOON WILL CLIMB INTO THE MID 80S IN THE MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. THE STRONG SUBTROPICAL RIDGE IN CENTRAL UNITED STATES RETROGRADES INTO SOUTHWEST...AS LOW PRESSURE ALOFT MOVES EASTWARD ALONG CANADIAN BORDER. THIS WILL DRIVE A COLD FRONT SOUTHEAST ACROSS THE REGION. THE FRONTAL BOUNDARY ENTERS OUR WESTERN MOUNTAINS WEDNESDAY NIGHT INTO THURSDAY...ON BOTH THE ECMWF AND GFS. LOWS WEDNESDAY NIGHT WILL VARY FROM THE MID 60S IN THE WEST TO THE LOWER 70S IN THE EAST. A COLD FRONT WITH SEVERAL WAVES OF LOW PRESSURE ALONG IT MOVES EAST ACROSS THE AREA ON THURSDAY INTO THURSDAY NIGHT. SHOWERS AND THUNDERSTORMS WILL SPREAD FROM WEST TO EAST ACROSS OUR AREA. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE UPPER 70S IN THE WESTERN MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. PLACED THE HIGHEST POPS IN THE EAST THURSDAY NIGHT AS FRONT PUSHES INTO THE ATLANTIC OCEAN. LOWS THURSDAY NIGHT WILL BE FROM THE MID 60S IN THE WEST TO LOWER 70S IN THE EAST. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 305 PM EDT MONDAY... THE DEEPENING UPPER TROUGH OVER NORTHEAST WILL ENABLE THE FRONTAL BOUNDARY TO MOVE SOUTH INTO THE SOUTHEAST STATES BEFORE IT STALLS. CONSEQUENTLY...ANY SUBSEQUENT LOW PRESSURE WILL REMAIN SOUTH OF THE REGION RIDING ALONG THE FRONTAL BOUNDARY. HIGH PRESSURE WILL BUILD EAST OUT OF THE OHIO VALLEY INTO OUR AREA FRIDAY INTO FRIDAY NIGHT. THE BEST CHANCE FOR ANY CONVECTION ON FRIDAY WILL OCCUR ACROSS THE SOUTHEAST. THIS IS BECAUSE DRIER AIR WITH LOWER DEWPOINTS WILL MOVE INTO OUR AREA...HINDERING INSTABILITIES. WITH A WAVE OF LOW PRESSURE LIFTING THE BOUNDARY NORTH AS IT TRAVERSES EASTWARD ON SATURDAY. DECIDED TO USED THE SUPERBLEND WITH ITS SLIGHT CHANCE OF CONVECTION IN THE SOUTHERN HALF OF FORECAST AREA SATURDAY INTO SATURDAY NIGHT. WITH THE DIFFERENCES IN GFS AND ECMWF...IT IS HARD TO TELL HOW FAR NORTH MOISTURE ACTUALLY LIFTS. ON SUNDAY...BOTH THE ECMWF AND GFS TRANSPORT SOME MOISTURE IN NORTHERN NORTH CAROLINA. BY MONDAY...THE UPPER TROUGH ACROSS THE GREAT LAKES DEEPENS AS SHORT WAVE ENERGY TRACKS THROUGH THE BASE OF THE TROUGH. THIS WILL PUSH THE NEXT COLD FRONT AND ITS ASSOCIATED PRECIPITATION SOUTHEAST. THE COLD FRONT WILL BE JUST TO OUR WEST SUNDAY NIGHT AND TRAVEL EAST ACROSS THE REGION MONDAY INTO MONDAY NIGHT. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 200 AM EDT TUESDAY... LATEST RADAR IMAGES INDICATE THE BURST OF LATE NIGHT CONVECTIVE ACTIVITY IN THE DIFFUSE FRONTAL ZONE OVER THE REGION IS DIMINISHING BUT ACTIVE WEATHER STILL CONTINUES NEAR KLYH. BELIEVE COHESIVE ACTIVITY WILL PERSIST FOR ANOTHER 1 TO 3 HOURS AS BOUNDARY INTERACTION RUNS ITS COURSE. AMOUNT OF FOG FORMATION IS QUESTIONABLE GIVEN RESIDUAL CLOUD COVER SO WILL KEEP THINGS GENERALLY MVFR EAST OF THE BLUE RIDGE BUT TEMPO TO IFR TO THE WEST. OBSERVATIONS FROM KLWB SHOW A LIGHT NORTHEAST FLOW AND MODEL GUIDANCE INDICATES THIS FLOW WILL BE IN AND OUT THROUGH TONIGHT. THIS USUALLY MITIGATES DENSE FOR AT KLWB BUT WHEN THE WIND GOES CALM LIFR CONDITIONS CAN WAFT IN. WILL USE A TEMPO LIFR GROUP AT KLWB AND TAG IT WITH CALM WIND CONDITIONS TO CONVEY THIS TRAIN OF THOUGHT. NOT MUCH CHANGE WITH THE SYNOPTIC PATTERN FOR TODAY AS THE FRONTAL BOUNDARY WILL LINGER IN THE AREA AND HELP KICK OFF MORE SHOWERS AND STORMS THIS AFTERNOON. ISOLATED ACTIVITY WILL BE FLOATING AROUND THROUGHOUT THE MORNING BUT THINGS REALLY DONT GET GOING UNTIL THE AFTERNOON SO WILL CONFINE MENTION OF THUNDER TO AFTER 16Z. ENVIRONMENT CONTINUES TO BE WEAKLY FORCED SO EXPECT HEAVY RAINERS WITH A LOW SEVERE THREAT. ACTIVITY WILL THEN START TO WIND DOWN WITH LOSS OF HEATING AFTER SUNSET. EXTENDED AVIATION FORECAST... WEDNESDAY WILL BE ANOTHER DAY OF MVFR TO IFR VALLEY FOG IN THE MORNING AND SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED ON THURSDAY AS A COLD FRONT CROSSES THROUGH REGION FROM THE NORTHWEST. THIS FRONT SHOULD PUSH SOUTH OF THE AREA AND ALLOW FOR DRIER AND MOSTLY VFR CONDITIONS FRI-SAT.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...KK LONG TERM...KK AVIATION...MBS/AMS

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