Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280157 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 957 PM EDT WED AUG 27 2014 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE SOUTH INTO THE REGION TONIGHT AND STALL ACROSS OUR AREA THROUGH THURSDAY AND FRIDAY...PROVIDING THE FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS. THE FRONT WILL LIFT NORTH AGAIN FRIDAY NIGHT. && .NEAR TERM /THROUGH THURSDAY/...
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AS OF 945 PM EDT WEDNESDAY... WATCHING A BROKEN LINE OF THUNDERSTORMS APPROACHING FROM THE NORTHWEST. HRRR 23Z RUN SHOWS SOME OF THIS ACTIVITY REACHING WESTERN GREENBRIER COUNTY. ADDED SLIGHT CHANCE TO CHANCE POPS FOR THE NEXT FEW HOURS ALONG WITH ADDING THUNDER TO THE GRIDS. BUMPED UP CLOUD COVER ACROSS THIS AREA AS WELL. AS OF 225 PM EDT WEDNESDAY... NOT SEEING MUCH IN THE WAY OF SHRA DEVELOPMENT THIS AFTERNOON. BEST CU FIELD LIES FROM THE MTNS OF GREENBRIER COUNTY NEWD ALONG THE ALLEGHANY FRONT. INSTABILITY IS MARGINAL WITH BEST SITUATED ACROSS KY INTO OHIO AND PA. WILL KEEP ISOLATED THREAT OF SHRA/TSRA THIS EVENING ACROSS THE WRN FRINGES OF SE WV/FAR SW VA AND BATH VA. MAINLY LOOKING AT CLEAR SKIES ELSEWHERE BUT MOISTURE IS STARTING TO INCREASE AS NOTED BY DEWPOINTS ASCENDING INTO THE 60S. LOW TEMPS AS SUCH ARE GOING TO BE MILDER THAN PREVIOUS SEVERAL NIGHTS WITH LOWS IN THE MID TO UPPER 50S MOUNTAIN VALLEYS TO MID 60S PIEDMONT. BACKDOOR FRONT WILL SHIFT ACROSS THE VA/NC BORDER LATE TONIGHT/THU MORNING. MODELS SHOW AXIS OF CONVERGENCE TO ALIGN ACROSS THE NC MTNS INTO THE PIEDMONT OF VA TOMORROW AFTERNOON AND THIS WILL BE WHERE TSRA WILL FORM...BUT COVERAGE WILL BE SCATTERED AT BEST...SO KEPT POPS IN THE 20/30 RANGE. MAINLY DRY NORTH OF A BLF-ROA LINE. CLOUDS WILL BE SCATTERED/BKN AFTER ANY MORNING FOG LIFTS...WITH HIGHS SURGING INTO THE 80S MOST AREAS WITH LOWER 90S SOUTHEAST.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 330 PM EDT WEDNESDAY... MODELS ARE IN GOOD AGREEMENT THAT A WEAK FRONT WILL BE STALLED ACROSS NORTHERN NORTH CAROLINA THURSDAY NIGHT AND FRIDAY...PROVIDING THE FOCUS FOR SHOWER ACTIVITY...POSSIBLY WITH A FEW THUNDERSTORMS DEVELOPING FRIDAY AFTERNOON/EVENING WITH DAYTIME HEATING. CANNOT IDENTIFY WITHIN THE MODEL DATA ANY STRONG DISTURBANCES RIDING ALONG THE FRONT...SO BELIEVE THE RAINFALL WILL BE OF THE LIGHT AND OCCASIONAL VARIETY. LOW PRESSURE PASSING ACROSS THE GREAT LAKES WILL DRAW THE FRONTAL BOUNDARY BACK TO THE NORTH AS A WARM FRONT FRIDAY NIGHT...WITH WEAK HIGH PRESSURE BUILDING BACK ACROSS OUR AREA ON SATURDAY FROM THE CAROLINAS. CANNOT RULE OUT A FEW SHOWERS OR STORMS DEVELOPING ACROSS THE MOUNTAINS DURING SATURDAY AFTERNOON AND EVENING...BUT THE DIP IN ATMOSPHERIC MOISTURE ASSOCIATED WITH THE HIGH WILL KEEP THIS ACTIVITY RATHER ISOLATED. SATURDAY NIGHT...SOUTHWESTERLY FLOW WILL BECOME FIRMLY REESTABLISHED AS UPPER LEVEL RIDGING RESIDES ACROSS THE SOUTHEAST STATES...WHILE AN UPPER LEVEL TROUGH MOVES TOWARDS THE GREAT LAKES. AS SUCH... EXPECT ATMOSPHERIC MOISTURE TO RAMP UP OVERNIGHT THANKS TO A DIRECT WINDFLOW OFF THE GULF OF MEXICO. CLOUD COVER WILL INCREASE AFTER SUNSET...WITH A FEW SHOWERS ENTERING THE MOUNTAINS TOWARD SUNRISE SUNDAY. TEMPERATURES THROUGH THE PERIOD WILL BE CLOSER TO NORMAL FOR LATE AUGUST THANKS TO INCREASED CLOUD COVER/MOISTURE POOLING ALONG THE FRONT. LOOK FOR HIGHS TO REACH INTO THE 80S MOST LOCATIONS FRIDAY AND SATURDAY...WHILE OVERNIGHT LOWS WILL BE MILDER THAN PREVIOUS NIGHTS...GENERALLY HOLDING IN THE 60S. && .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 /02Z THURSDAY THROUGH MONDAY/... AS OF 815 PM EDT WEDNESDAY... BKN LINE OF SHRA/TSRA FROM MGW-LEX...APPROACHING FROM THE NORTHWEST...EXPECTED TO WEAKEN AND DISSIPATE B4 MIDNIGHT. DEBRIS CLOUDINESS...BASES AOA 10KFT...MAY PASS THROUGH SOUTHERN WV INTO SOUTHERN VA OVERNIGHT. CURRENT THINKING IS DEBRIS CLOUDINESS WILL BE PRETTY THIN...THUS PROMOTING ANOTHER GOOD RADIATIONAL COOLING NIGHT WITH FORMATION OF RIVER VALLEY FOG IN THE MOUNTAIN VALLEYS. THIS WILL MAINLY IMPACT KLWB/KBCB WHERE IFR/LIFR CONDITIONS POSSIBLE FOR A FEW HOURS TOWARD DAYBREAK THURSDAY...ANY FOG/STRATUS LIFTING MID MORNING. WEAK SURFACE COLD FRONT WILL CROSS THE FORECAST AREA EARLY THURSDAY...THEN BECOME STATIONARY ACROSS NORTH CAROLINA LATE THURSDAY INTO FRIDAY. CONVERGENCE ALONG THE FRONT WILL PERMIT SCATTERED SHRA/TSRA AGAIN THURSDAY AFTERNOON. POSITION OF FRONT BY THAT TIME SUGGESTS SHRA/TSRA ACTIVITY WILL DEVELOP VCNTY OF THE VA/NC BORDER...THEN DRIFT SOUTHEAST INTO NORTH CAROLINA WITH THE MEAN WIND WHICH WILL BE OUT OF THE NORTHWEST. SCT-BKN CU SEEMS LIKE THE MOST LIKELY SCENARIO ACROSS THE VIRGINIAS THURSDAY AFTERNOON...TOWERING CU LIMITED TO THE FRONTAL ZONE WHICH WILL BE DRIFTING INTO NORTH CAROLINA. BEHIND THE FRONT WINDS WILL GENERALLY BE OUT OF THE NORTHWEST...4-7KTS AT THE MOST. EXTENDED DISCUSSION... THE WEAK SURFACE COLD FRONT IS FORECAST TO STALL OVER THE CAROLINAS THURSDAY NIGHT...REMAIN NEARLY STATIONARY FRIDAY...THEN RETURN NORTH AS A WARM FRONT SATURDAY. 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 BRIEF PERIOD OF SUB VFR CONDITIONS CAN BE EXPECTED. 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 MUCH MORE WIDESPREAD AS COMPARED TO FRIDAY AND SATURDAY. AS SUCH...THE FIRST HALF OF THE HOLIDAY WEEKEND LOOKS MORE FAVORABLE TO VFR FLYING COMPARED TO THE SECOND HALF. && .EQUIPMENT... AS OF 1130 AM EDT WEDNESDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...REMAINS OUT OF SERVICE. A PART HAS BEEN ORDERED BUT APPEARS REPAIRS WILL NOT BE DONE UNTIL THIS FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...CF/WP SHORT TERM...NF LONG TERM...NF AVIATION...PM EQUIPMENT...AMS

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