Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 281736 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 136 PM EDT MON JUL 28 2014 .SYNOPSIS... COOLER DRIER CANADIAN AIR WILL MOVE INTO THE MID ATLANTIC BEHIND A COLD FRONT TODAY. AN UPPER LEVEL DISTURBANCE PASSING ACROSS THE GREAT LAKES WILL BRING GUSTY WINDS TO THE FORECAST REGION LATE THIS MORNING AND THIS AFTERNOON...IN ADDITION TO SPOTTY UPSLOPE SHOWERS ALONG THE WESTERN RIDGES. COOLER CONDITIONS WILL REMAIN ACROSS THE AREA THROUGH MUCH OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1245 PM EDT MONDAY... ISOLATED LIGHT RAIN SHOWERS HAVE ARRIVED ACROSS PARTS OF SOUTHEAST WEST VIRGINIA AS OF 1200 PM. COVERAGE IS EXPECTED TO CONTINUE TO INCREASE THIS AFTERNOON...STILL MAINLY OVER SOUTHEAST WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA. A FEW SHOWERS MAY DEVELOP OR MOVE INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA. SOUTHEAST WEST VIRGINIA MAY ALSO EXPERIENCE A STRAY THUNDERSTORM OR TWO. HAVE MADE LIMITED ADJUSTMENTS TO THE PREVIOUSLY FORECAST AREA OF COVERAGE AND TIMING. HAVE TWEAKED FORECAST HIGH TEMPERATURE UPWARD A FEW DEGREES ACROSS MOST AREA EAST OF THE CREST OF THE BLUE RIDGE...A SOME LOCATIONS WITHIN THE MOUNTAINS. CURRENT TEMPERATURES ACROSS THE AREA ARE RISING MORE QUICKLY THAN EARLIER FORECAST...AND ADDITIONAL HEATING IS STILL EXPECTED THROUGH THE AFTERNOON. AS OF 955 AM EDT MONDAY... HAVE MADE ONLY MINOR ADJUSTMENTS TO THE FORECAST THIS MORNING. HAVE REMOVED ISOLATED TO SCATTERED SHOWERS ACROSS THE WESTERN PART OF THE AREA FOR ABOUT THEN NEXT 2 TO 3 HOURS. EXPECTING MORE OF A NOON TO 100 PM INITIATION TIME FOR ANY SHOWER ACTIVITY IN THIS REGION. CURRENT COVERAGE HAS WANED TO ONLY A FEW SPRINKLES OVER WESTERN GREENBRIER COUNTY WV. HAVE ALSO ADJUSTED TEMPERATURE AND DEW POINT TO REFLECT THE LATEST OBSERVATIONS AND EXPECTED TRENDS INTO THE EARLY AFTERNOON. AS OF 400 AM EDT MONDAY... ASIDE FROM A FEW SPRINKLES LEFT OVER ACROSS THE MOUNTAINS THIS MORNING...ALL SHOWER ACTIVITY HAS EXITED THE AREA FOR THE TIME BEING. THE COLD FRONT CONTINUES TO MAKE STEADY PROGRESS ACROSS WEST VIRGINIA AS THE PARENT SURFACE LOW SHIFTS EAST OVER EASTERN PENNSYLVANIA...AND EXPECT THE COLD FRONT TO ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES BY AROUND SUNRISE...PUSHING RAPIDLY EAST THROUGH THE MORNING. THE MAIN CONCERN FOR THE MORNING WILL BE GUSTY WINDS ACROSS THE MOUNTAINS BEHIND THE FRONT AS A DEEP UPPER LEVEL DISTURBANCE PASSES ACROSS THE EASTERN GREAT LAKES. STRONG WINDS WRAPPING AROUND THE SOUTHERN END OF THE DISTURBANCE WILL PUSH ACROSS THE MOUNTAINS DURING LATE MORNING AND EARLY AFTERNOON...AND EXPECT GUSTS TO MAX OUT AS HIGH AS 40 MPH AT TIMES AT ELEVATIONS OF 30OO FEET AND UP. THE MAIN ENERGY MOVING AROUND THE UPPER DISTURBANCE WILL SHIFT EAST OF THE AREA DURING MID AFTERNOON...AND EXPECT TO SEE WIND SPEEDS GRADUALLY DIMINISH THEREAFTER. WITH WINDS SHIFTING NORTHWESTERLY AROUND THE BACKSIDE OF THE DISTURBANCE DURING EARLY AFTERNOON...WILL ALSO SEE SPOTTY UPSLOPE SHOWER ACTIVITY DEVELOP ACROSS OUR WESTERN RIDGELINES OF SOUTHEAST WEST VIRGINIA INTO THE NORTH CAROLINA MOUNTAINS. LAPSE RATES WILL BECOME STEEP ENOUGH FOR A FEW HOURS DURING THE AFTERNOON THAT WOULD NOT BE SURPRISED TO SEE A FEW SHOWERS DEVELOP INTO THUNDERSTORMS...BUT BELIEVE THOSE WILL BE FEW AND FAR IN BETWEEN AT BEST. SHOWER ACTIVITY WILL DECREASE INTO THE EVENING AS WIND SPEEDS CONTINUE TO DIMINISH...BUT EXPECT A FEW SHOWERS TO LINGER INTO EARLY TUESDAY. TEMPERATURES WILL BE COOLER ACROSS THE MOUNTAINS TODAY ONCE THE FRONT PASSES...HOWEVER THERE WILL BE TIME FOR DECENT HEATING BEFORE THE FRONT ARRIVES ACROSS THE PIEDMONT CONSIDERING THE DECREASING CLOUD COVER AND DRY DOWNSLOPE WESTERLY WINDS. EXPECT HIGHS TO RANGE FROM THE LOW 70S ACROSS THE WESTERN RIDGES TO THE UPPER 80S ACROSS THE SOUTHSIDE. LOWS TONIGHT WILL FALL INTO THE LOW 50S WEST AND THE LOW 60S EAST. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM EDT MONDAY... MODELS ARE IN GOOD AGREEMENT THAT A FULL LATITUDE UPPER TROF WILL COVER THE EASTERN HALF OF THE U.S. DURING THE SHORT TERM PERIOD...KEEPING TEMPERATURES WELL BELOW AVERAGE FOR LATE JULY. WITH ONLY A THIN LAYER OF MOISTURE EXPECTED BETWEEN 5-10KT TUESDAY...PRECIPITATION WILL BE HARD TO COME BY...BUT KEPT A SMALL CHANCE IN FAR SOUTHWEST VA AND NW NC...AS A WEAK UPPER LEVEL IMPULSE ROUNDS THE BASE OF THE UPPER TROF. OTHERWISE...ONLY SOME CUMULUS CLOUDS WILL COVER THE REGION. TUESDAY SHOULD BE THE COOLEST DAY DURING THIS PERIOD WITH THE GEFS FORECASTING 850MB TEMPS 2-3 STANDARD DEVIATIONS BELOW NORMAL. MODEL GUIDANCE HAS BEEN VERY CONSISTENT FROM RUN TO RUN WITH ITS HIGH TEMPERATURE FORECAST....SO STRAYED LITTLE FROM THE UPPER 60S/LOWER 70S FORECAST IN THE MOUNTAINS TO UPPER 70S/LOWER 80S EAST OF THE BLUE RIDGE. A WEAK LOW THAT FORMS OFF THE CAROLINA COAST TUESDAY LIFTS NORTHEAST INTO THE ATLANTIC SHOULD REMAIN FAR ENOUGH EAST TO NOT INFLUENCE OUR WEATHER. SFC HIGH PRESSURE BUILDS INTO THE WESTERN PORTION OF THE FORECAST AREA BY 12Z (8 AM EDT) WEDNESDAY. GOOD RADIATIONAL COOLING CONDITIONS SHOULD ALLOW LOW TEMPS TO FALL INTO THE 40S IN SOME LOCATIONS IN THE MOUNTAINS TO THE MID TO UPPER 50S IN THE EAST. THESE VALUES WILL BE CLOSE TO THE RECORDS FOR JULY 30TH. SEE CLIMATE SECTION BELOW FOR RECORD LOWS FOR WEDNESDAY. UPPER TROF RELAXES SOME ON WEDNESDAY...ALLOWING 850MB TEMPS TO WARM A COUPLE OF DEGREES VERSUS TUESDAY. STILL...TEMPS WILL BE WELL BELOW NORMAL. THE 00Z NAM AND 21Z SREF APPEAR BULLISH ON DEVELOPING UPSLOPE SHOWERS WEDNESDAY AFTERNOON. CONSIDERING THE AMOUNT OF DRY AIR IN PLACE...KEPT THE FORECAST DRY. SFC HIGH PRESSURE FORECAST TO SIT OVER THE WESTERN HALF OF THE FORECAST AREA WEDNESDAY NIGHT...BUT WITH DEW POINTS SLIGHTLY HIGHER...LOWS WILL BE A DEGREE OR TWO WARMER THURSDAY MORNING...BUT STILL WELL BELOW NORMAL AND CLOSE TO RECORD LOWS IN SOME LOCATIONS LIKE LWB. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 1200 PM EDT SUNDAY... A SURFACE HIGH THURSDAY OVER SOUTHERN MICHIGAN WILL SHIFT EAST TOWARDS NEW ENGLAND BY FRIDAY AND SATURDAY. AT THE MID LEVELS A PERSISTENT TROUGH IS SET UP OVER THE EASTERN US WITH A RIDGE OVER THE WESTERN US. THURSDAY LACKS LOW AND MID LEVEL MOISTURE SO EXPECT THE DAY TO BE DRY. MOISTURE AND INSTABILITY INCREASE FOR FRIDAY AND THROUGH THE REST OF THE PERIOD AS SEVERAL DISTURBANCES PIVOT ACROSS THE REGION AROUND THE BASE OF THE TROUGH. EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP EACH AFTERNOON/EVENING AND TAPER OFF TO JUST SCATTERED SHOWERS DURING THE EVENING. FOCUS OF THE HIGHEST CHANCE POPS ARE OVER THE MOUNTAINS WHERE THE BEST CONVERGENCE WILL BE LOCATED...WITH LOWER CHANCE POPS OUT EAST. THURSDAY WILL BE THE WARMEST DAY OF THE PERIOD WITH 850MB TEMPS AROUND +16C. THIS WILL CORRESPOND TO SURFACE HIGH TEMPS IN THE MID 80S OUT EAST AND NEAR 80 ACROSS THE MOUNTAINS. AS THE HIGH SHIFTS EAST ON FRIDAY THE WINDS WILL SHIFT FROM N/NW TO AN EASTERLY DIRECTION. THIS WILL WEDGE THE AREA IN THROUGH THE REMAINDER OF THE PERIOD. WITH THE INCREASED LOW/MID LEVEL MOISTURE EXPECT CLOUDY CONDITIONS. THIS ALONG WITH EXPECTED SCATTERED PRECIP AND 850MB TEMPS FALLING TO +11-14C...SURFACE HIGH TEMPS WILL BE 5-10 DEGREES BELOW NORMAL FRIDAY THROUGH SUNDAY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 130 PM EDT MONDAY... GUSTY SURFACE CONDITIONS WITH MAINLY VFR CONDITIONS PREVAIL ACROSS THE AREA CURRENTLY. ISOLATED SHOWERS ARE ACROSS SOUTHEAST WEST VIRGINIA. AS THE REMAINDER OF THE AFTERNOON PROGRESSES...SURFACE WIND AND GUSTS WILL GRADUALLY DECREASE AS THE 850 MB SPEED MAX EXITS THE REGION. WITH THE DEVELOPMENT OF THE NOCTURNAL INVERSION...LIGHT WINDS ARE ANTICIPATED ACROSS THE REGION OVERNIGHT. MOST OF THE SHOWERS WILL ALSO DISSIPATE AROUND SUNSET. TONIGHT...WE EXPECT A RETURN OF MVFR CIGS AND SOME POCKETS OF MVFR VSBYS ACROSS THE MOUNTAINS. ANY SUB-VFR CONDITIONS WILL RAPIDLY IMPROVE TO VFR TUESDAY MORNING. SOME ISOLATED SHOWERS CANNOT BE RULED OUT LATE TONIGHT INTO EARLY TUESDAY MORNING ACROSS THE SOUTHWEST PART OF THE FORECAST AREA AS A WEAK DISTURBANCE SWEEPS THROUGH THE OVERALL LONGWAVE TROUGH PATTERN. EXTENDED AVIATION DISCUSSION... PERSISTENT TROUGH PATTERN IN THE EAST WILL GRADUALLY RETROGRADE WEST BY THE END OF THE WEEK. MAINLY VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST THURSDAY SAVE SOME LATE NIGHT EARLY MORNING PATCHY MVFR FOG IN THE MOUNTAIN AND RIVER VALLEYS. AFTER THURSDAY...WITH THE TROUGH AXIS FARTHER WEST...THIS WILL ALLOW FOR A RETURN OF ATLANTIC MOISTURE AND A GREATER ABUNDANCE OF SHOWERS...AND POTENTIALLY STORMS...IN THE FORECAST HEADING INTO THE WEEKEND. THIS ALSO WILL ALLOW FOR INCREASED CHANCES OF SUB-VFR CONDITIONS WITHIN THE AREA OF THE SHOWERS...AND THEN AGAIN OVERNIGHT IN THE FORM OF LIGHT FOG OR STRATUS AS BOUNDARY MOISTURE GETS TRAPPED UNDER THE NOCTURNAL INVERSION. && .CLIMATE... JULY 30TH RECORD LOWS: ROANOKE......54...1997 BLUEFIELD....50...1981 DANVILLE.....60...1972/81/83/2013 LEWISBURG....46...2013 LYNCHBURG....52...1997 BLACKSBURG...50...1973/81 JULY 31ST RECORD LOWS: ROANOKE......49...1914 BLUEFIELD....49...1997 DANVILLE.....55...1966 LEWISBURG....48...1997 LYNCHBURG....49...1997 BLACKSBURG...44...1997 && .EQUIPMENT... THE NOAA WEATHER RADIO AT HINTON WEST VIRGINIA IS BACK ON THE AIR. HOWEVER...THE NOAA WEATHER RADIO AT WYTHEVILLE VA...WZ2500...BROADCASTING ON A FREQUENCY OF 162.450 MHZ...IS OFF THE AIR. TECHNICIANS ARE BEING NOTIFIED. NO ESTIMATE FOR RETURN TO SERVICE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS/NF NEAR TERM...DS/NF SHORT TERM...PH LONG TERM...CF AVIATION...DS CLIMATE...PH EQUIPMENT...DS

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