Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 281753 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 153 PM EDT THU AUG 28 2014 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE SOUTH THROUGH THE REGION THIS AFTERNOON AND STALL ACROSS NORTH CAROLINA TONIGHT. FRIDAY AND SATURDAY THE FRONT WILL LIFT WELL NORTH OF THE AREA. BROAD HIGH PRESSURE CENTERED OFF THE COAST WILL BE OVER THE REGION SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 120 PM EDT THURSDAY... MESOANALYSIS EARLY THIS AFTERNOON SHOWED BEST INSTABILITY AND MOISTURE CONVERGE ALONG AND EAST OF THE BLUE RIDGE ACROSS CENTRAL VA. CU FIELD PER WEB CAM MAINLY FAIR WX...WITH SOME VERTICAL DEVELOPMENT OVER THE NC HIGH COUNTRY NEAR GRANDFATHER MTN. HIGH RES MODELS AND 12Z NAM/GFS CONTINUE TO PAINT ISOLATED/SCATTERED CONVECTION FIRING UP SHORTLY FROM THE NC MTNS INTO THE VA PIEDMONT. KEPT POPS IN THE 20/30 RANGE MAINLY. SHOULD SEE SOME SEWD TRANSITION THROUGH EARLY EVENING AS THE FRONT SINKS SWD. SKIES IN THE NORTH SHOULD STAY MAINLY SUNNY AS DRIER AIR WORKS IN FROM THE MID ATLANTIC. MEANWHILE...EXPECT THE SRN CWA TO STILL GET SUNSHINE...BUT MORE CU FIELD AND WIDELY SCATTERED TCU/CBS. TEMPS RUNNING WARMER BY ABOUT 2 DEGREES BUT OVERALL HIGH TEMP FORECAST OF L-MID 80S WEST TO LOW 90 EAST STILL SEEMS REASONABLE. PREVIOUS VALID DISCUSSION... THE FRONT STALLS AROUND THE VIRGINIA/NORTH CAROLINA BORDER THIS EVENING. MAIN CORRIDOR OF HIGHER RELATIVE HUMIDITIES MOVES LITTLE TONIGHT. CLOUDS AND MILDER DEW POINTS WILL HOLD TEMPERATURES ACROSS THE SOUTH IN THE 60S. SREF AND LOCAL WRF HAD DEW POINTS IN THE EXTREME NORTHERN COUNTY WARNING AREA DROPPING INTO THE 50S TONIGHT. IF THIS AREA CLEARS OUT ENOUGH TEMPERATURES WILL DROP INTO THE MID TO UPPER 50S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 245 AM EDT THURSDAY... FRIDAY START WITH AN AREA OF HIGH PRESSURE OVER NEW ENGLAND AND THE MID ATLANTIC STATES. ALOFT...A RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHEASTERN STATES STRETCHING NORTH OVER THE MID ATLANTIC REGION. OVER THE FORECAST AREA...A STALL FRONTAL BOUNDARY WILL BE IN THE VICINITY OF THE NC/VA BORDER. THROUGH FRIDAY AFTERNOON AND NIGHT...BOTH HIGH PRESSURE SYSTEMS WILL DRIFT EAST...WHILE THE FRONTAL BOUNDARY RETREATS NORTH AS A WARM FRONT. WITH AN INCREASE IN MOISTURE AND AFTERNOON HEATING...THIS FRONTAL BOUNDARY WILL BE THE FOCUS FOR AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. TEMPERATURES FRIDAY WILL BE INFLUENCE MAINLY BY THE UPPER LEVEL RIDGE OVER THE SOUTHEAST AND WILL WARM ABOVE NORMAL FOR THE MAJORITY OF THE AREA. LOCATIONS FROM THE SOUTHERN SHENANDOAH VALLEY TO THE VA PIEDMONT WILL REMAIN UNDER THE INFLUENCE OF THE SURFACE HIGH THROUGH MUCH OF FRIDAY. AS LONG AS THIS AREA MAINTAINS AN EASTERLY WIND...TEMPERATURES WILL REMAIN BELOW NORMAL. BY THE END OF THE DAY...EXPECTING FRONTAL BOUNDARY TO BE NORTH OF THE FORECAST AREA...ALLOWING NORTHERN COUNTIES TO HAVE A LATE DAY SURGE IN TEMPERATURES. FRIDAY AFTERNOON TEMPERATURES WILL RANGE FROM THE L/M 80S WEST TO M/U 80S EAST. THE NORTHERN AND SOUTHERN JET STREAMS ARE SPLIT ON SATURDAY. THE NORTHERN STREAM FEATURES A LOW PRESSURE SYSTEM THAT WILL TRACK EAST FROM THE GREAT LAKES TO NEW ENGLAND. THE UPPER LEVEL RIDGE OVER THE SOUTHEASTERN STATES WILL BLOCK ANY SOUTHERN STREAM SYSTEMS FROM ADVANCING EAST THROUGH THE PERIOD. THE OUTER RINGS OF THIS RIDGE START AT THE TEXAS GULF COAST...TO THE TENNESSEE VALLEY...AND OVER THE CENTRAL APPALACHIANS. SHORT WAVES WITH TROPICAL MOISTURE WILL TRACK ON THESE OUTER RINGS...INCREASING THE CHANCES FOR SHOWERS AND THUNDERSTORMS LATE SATURDAY INTO SATURDAY NIGHT. THE BEST CHANCE FOR AREAWIDE RAIN LOOKS TO BE SUNDAY. WITH ONLY SCATTERED STORMS EXPECTED SATURDAY AND MAINLY OVER THE MOUNTAINS...TEMPERATURES WILL WARM INTO THE M/U 80S WITH THE PIEDMONT WARMING INTO THE L90S. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 345 PM EDT WEDNESDAY... DEEP GULF MOISTURE FLOWING NORTH ALONG THE APPALACHIAN CHAIN WILL MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY FOR THE EARLY HALF OF NEXT WEEK. FOR SUNDAY...RAINFALL IS LOOKING INCREASINGLY LIKELY AS AN UPPER LEVEL TROUGH MOVES UP THE OHIO RIVER VALLEY. WITH PERCEPTIBLE WATER VALUES IN THE BALLPARK OF 2 INCHES ACROSS OUR AREA...BELIEVE THAT LOCALLY EXCESSIVE RAINFALL WILL BE POSSIBLE IN SOME AREAS... ESPECIALLY IF STORMS BEGIN TO PASS REPEATEDLY OVER THE SAME LOCATIONS. ON MONDAY...UPPER LEVEL FLOW BEGINS TO TRANSITION TO A MORE WEST TO EAST ORIENTATION...WITH NO STRONG DISTURBANCES EXPECTED. BELIEVE SHOWER AND THUNDERSTORM ACTIVITY WILL BE MORE DRIVEN BY DAYTIME HEATING THAN ANYTHING ELSE...MEANING RAINFALL WILL BE MORE OF THE HIT AND MISS VARIETY. LOOKING TO TUESDAY...EXPECT A SLIGHTLY BETTER CHANCE OF SHOWERS AND THUNDERSTORMS AS A COLD FRONT APPROACHES OUR REGION FROM THE NORTHWEST. BEST CHANCES FOR SHOWER AND THUNDERSTORM ACTIVITY WILL BE DURING THE EVENING AS THE FRONT APPROACHES THE OHIO RIVER...HOWEVER WITH NO REAL PUSH OF COLD AIR BEHIND THE FRONT...IT IS ENTIRELY POSSIBLE THAT THE OHIO RIVER IS AS FAR SOUTH AS THE FRONT SINKS. ABUNDANT GULF MOISTURE WILL MAKE FOR MUGGY AND WARM CONDITIONS FOR THE EARLY HALF OF NEXT WEEK. LOOK FOR HIGHS TO RANGE FROM THE UPPER 70S/LOW 80S ACROSS THE MOUNTAINS...TO THE UPPER 80S ACROSS THE PIEDMONT. OVERNIGHT LOWS WILL RANGE FROM THE MID 60S TO LOW 70S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 130 PM EDT THURSDAY... EXPECT MAINLY SCT CU FIELD THIS AFTERNOON IN THE 3-5KFT RANGE...BKN AT TIMES SOUTH OF A BLF-BCB-DAN LINE. ISOLATED/SCATTERED SHRA/TSRA TO FORM FROM GEV/TNB ENE TOWARD DAN/FVX THIS AFTERNOON. COVERAGE IS SUCH THAT NO MENTION IN TAFS NEEDED. THIS EVENING FRONT WILL SLOW OVER THE NC/VA LINE...GRADUALLY SINKING SWWD THROUGH FRI MORNING. MAY STILL SEE SHOWERS/STORMS LINGERING SOUTH AND EAST OF DAN. MAIN CONCERN OVERNIGHT IS HOW MUCH OF A HIGH PRESSURE WEDGE SETS UP FROM THE NORTH...WITH THE 12Z NAM SHOWING MODEST AMOUNT OF LOWER CIGS FROM THE NEW RIVER VALLEY/BCB EAST TO LYH/DAN. GIVEN DRY NATURE OF THE AIRMASS TO THE NORTH...WHILE TAKING INTO ACCOUNT THE MOIST AIRMASS OVERHEAD NOW...THINK A LEANING TOWARD THE NAM IS NEEDED...BUT TAKING INTO THE OTHER MODELS LACKING IN CLOUD COVER. WILL ADVERTISE SCT/BKN VFR CIGS AT LYH/DAN WITH SOME FOG POSSIBLE AT DAN IF IT STORMS NEARBY. FURTHER WEST...THE LACK OF CLOUD COVER AND SOME GROUND MOISTURE MAY ALLOW FOR FOG FORMATION...SO ADDED IFR/MVFR VSBYS AT BLF/LWB AND BCB AFTER 08Z. SHOULD SEE IMPROVEMENTS TO VFR AFTER 13-14Z AT ALL SITES FRIDAY. EXTENDED DISCUSSION... THE WEAK FRONT IS FORECAST TO RETURN NORTH AS A WARM FRONT FRIDAY. WIDELY SCATTERED SHRA/TSRA ARE EXPECTED ALONG THIS BOUNDARY FRIDAY AND SATURDAY...WITH THE GREATEST COVERAGE DURING THE PEAK HEATING OF THE DAY. WHERE SHRA/TSRA OCCUR EXPECT BRIEF PERIODS OF SUB VFR CONDITIONS. AN AREA OF LOW PRESSURE IS FORECAST TO MOVE THROUGH THE GREAT LAKES SATURDAY NIGHT AND SUNDAY...THE ASSOCIATED COLD FRONT TRAILING SOUTH AND MOVING ACROSS THE OHIO/TN VALLEYS. SHOWERS AND THUNDERSTORMS WILL LIKELY BE ASSOCIATED WITH THIS FRONT...THIS ACTIVITY SPREADING EAST INTO THE CENTRAL APPALACHIANS SUNDAY AND MONDAY. SHOWER COVERAGE SUNDAY/MONDAY IS EXPECTED TO BE MORE WIDESPREAD AS COMPARED TO FRIDAY AND SATURDAY. && .EQUIPMENT... AS OF 100 PM EDT THURSDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...REMAINS OUT OF SERVICE. A PART HAS BEEN ORDERED. REPAIRS WILL BE DONE THIS FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/WP SHORT TERM...RCS LONG TERM...NF AVIATION...AMS/WP EQUIPMENT...AMS

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