Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 081109 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 709 AM EDT TUE JUL 8 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE NORTHWEST TODAY BEFORE SPILLING SLOWLY SOUTHEAST INTO THE AREA ON WEDNESDAY. THIS COMBINED WITH DAYTIME HEATING AND INCREASING MOISTURE...WILL BRING AN INCREASING THREAT FOR SHOWERS AND THUNDERSTORMS...FIRST IN THE FAR WEST LATER TODAY...AND THEN FOR MUCH OF THE AREA BY WEDNESDAY. THE FRONT WILL STRUGGLE TO CLEAR THE PIEDMONT AREAS ON THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 225 AM EDT TUESDAY... HEAT AND HUMIDITY WILL CONTINUE TO SURGE TODAY AS LOW LEVEL SW FLOW ENHANCES AHEAD OF THE APPROACHING UPSTREAM COLD FRONT THIS AFTERNOON. THIS COMBINED WITH DECENT HEATING ESPCLY EARLY ON AND 85H TEMPS AROUND +21C OUT EAST SHOULD AGAIN PUSH HIGHS INTO THE LOW/MID 90S EAST...AND 80S TO PERHAPS CLOSE TO 90 IN SPOTS NEAR THE BLUE RIDGE. HOWEVER STILL WELL BELOW ANY ADVISORY HEADLINES WITH DEWPOINTS AGAIN MIXING LOWER UNDER THE GUSTY SW BREEZE LATER ON. OTRW MAIN CONCERN REMAINS WITH CONVECTIVE COVERAGE ESPCLY VERY LATE THIS AFTERNOON OVER THE FAR WEST AS MODELS SUGGEST AT LEAST A BROKEN LINE OF STORMS WELL IN ADVANCE OF THE BOUNDARY DROPPING SE INTO THE AREA. THIS LOOKS TO AFFECT MAINLY THE SE WVA COUNTIES DOWN TO JUST WEST OF I-77 AFTER 20-22Z OR SO...WITH QUESTIONS TO JUST HOW FAR EAST OR SE THESE STORMS MAY GO GIVEN BEST SUPPORT TO THE NORTH WITH THE UPPER TROF...AND MORE OF A DEEPER WESTERLY FLOW UPON HEADING EAST. IF CAN ORGANIZE MORE AND GET SOME FORWARD IN WAKE OF THE UPSTREAM COOL POOL...APPEARS JUST ENOUGH INSTABILITY TO BRING SOME OF THIS COVERAGE EAST TO THE BLUE RIDGE AND PERHAPS EAST OF THE MOUNTAINS IN A WEAKENED STATE MAINLY AFTER SUNSET. THIS SUPPORTED MORESO BY THE LATEST NAM/CMC AND SPC WRF AND LESS BY THE GFS WITH THE EC IN BETWEEN. INCREASING UNIDIRECTIONAL FLOW ALOFT AND HIGH FORECAST DCAPES WOULD SUPPORT MORE OF A WIND THREAT AND SEEN VIA THE CURRENT SWODY1. THUS BUMPED UP LIKELY POPS A BIT MORE WESTERN THIRD AND ADDED GUSTY WIND MENTION...WITH A SHARP CUTOFF TO SLIGHT POPS OR LESS OUT EAST THIS AFTERNOON...AS THINK ANYTHING AHEAD OF THIS LINE FEATURE MOSTLY ISOLATED GIVEN SUCH A WELL MIXED BOUNDARY LAYER. FRONT WILL STILL BE WEST OF THE MOUNTAINS OVERNIGHT AS A WEAK WAVE HANGS IT UP AND HELPS FOCUS BEST CONVERGENCE ACROSS THE SW UNDER DEEPENING WESTERLY FLOW. THIS SHOULD PIN THE NEXT ROUND OF HIGHER POPS ACROSS THE MTN EMPIRE AREA INTO NW NC OVERNIGHT WITH AGAIN A QUICK DROPOFF IN COVERAGE HEADING EAST PER DOWNSLOPE LIMITING SHRA EAST OF THE BLUE RIDGE AFTER MIDNIGHT. OTRW MOSTLY CLOUDY WEST TO PC ELSW BUT MUGGY WITH LOWS MOSTLY MID 60S VALLEYS TO LOW/MID 70S EAST. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 310 AM EDT TUESDAY... A BROAD UPPER LEVEL TROUGH WILL ENCOMPASS THE NORTHEAST QUARTER OF THE UNITED STATES...FROM THE NORTH AND CENTRAL PLAINS TO THE CAROLINAS AND MID ATLANTIC REGION...WEDNESDAY AND THURSDAY. A SURFACE FRONT WILL SLIDE ACROSS THE FORECAST AREA WEDNESDAY...STALLING ACROSS THE CAROLINAS WEDNESDAY NIGHT. THIS FRONT WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA WEDNESDAY. 00Z MODEL SOLUTIONS FOR WEDNESDAY ARE QUITE DIFFERENT FROM 24 HOURS AGO. LATEST SOLUTIONS LIMITING STRONG STORMS WITH MORE MORNING RAIN AND CLOUDS OVER THE AREA. BULK OF THE STRONGER DYNAMICS AND STORMS APPEARS TO BE MOVING SOUTH INTO THE TENNESSEE VALLEY. THE FRONT BUCKLES TO THE NORTHWEST ON THURSDAY AS A WEAK REFLECTION TRACKS ALONG THE STALLED BOUNDARY ACROSS THE CAROLINAS. IF THIS BOUNDARY DOES BUCKLE...AREAS EAST OF THE BLUE RIDGE...PARTICULARLY SOUTHSIDE...WILL SEE ANOTHER ROUND OF PASSING SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON AND NIGHT. MORNING CLOUDS AND RAIN SHOULD KEEP MOUNTAIN TEMPERATURES NEAR NORMAL...WHILE THE PIEDMONT SEES WARMER THAN NORMAL TEMPERATURES WEDNESDAY. WITH MOST AREAS RESIDING BEHIND THE FRONT ON THURSDAY...TEMPERATURES WILL RUN COOLER THAN NORMAL. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 300 PM EDT MONDAY... UPPER PATTERN IS AGAIN BECOMING ZONAL THURSDAY NIGHT AND FRIDAY BUT MODELS WERE BRINGING A SHORT WAVE THROUGH THE BASE OF THE EASTERN TROF AND ACROSS THE MID ATLANTIC REGION THURSDAY NIGHT. THE 500 MB TROF DEEPENS AGAIN ON SUNDAY AND MONDAY. SURFACE FRONT IS WELL TO THE SOUTHEAST OF THE FORECAST AREA THURSDAY NIGHT AND FRIDAY BUT ANY WAVE ALONG THE FRONT MAY BRING DEEPER MOISTURE AND A HIGHER PROBABILITY OF PRECIPITATION BACK TOWARD THE SOUTHERN COUNTY WARNING AREA. FORECAST AREA WILL RETURN TO WARM...HUMID...UNSTABLE AIR...AND THE ASSOCIATED CHANCE OF THUNDERSTORMS...SUNDAY AND MONDAY AHEAD OF THE NEXT COLD FRONT. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 650 AM EDT TUESDAY... COMMS ISSUES REMAIN AT KDAN DESPITE AN INTERMITTENT RETURN OF OBSERVATION DATA. AMD NOT SKED CONTINUED IN THE TAF...ALTHOUGH VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. LOW LEVEL MOISTURE HAS INCREASED ACROSS THE FAR WEST EARLY THIS MORNING WITH HIGH END MVFR TO VFR CIGS SPREADING EAST. EXPECT THESE LOWER CIGS TO AFFECT LOCATIONS OUT TO THE BLUE RIDGE THROUGH ABOUT MID MORNING BEFORE MIXING/HEATING CAUSE CLOUDS TO DIMINISH. A FEW SHRA/TSRA ALSO POSSIBLE MAINLY AROUND KBLF OVER THE NEXT COUPLE OF HOURS SO INCLUDED A VCSH MENTION AT BOTH KBLF/KLWB. OTRW STILL LOOKING AT OVERALL VFR CONDITIONS TO PREVAIL WITH EARLY CIGS EVOLVING INTO A BKN CU FIELD WEST AND AT LEAST SCTD HIGH BASED CU ACROSS THE EAST. STILL APPEARS THE BEST CHANCES FOR CONVECTION WILL BE AFTER 18Z/2PM AS THE COLD FRONT APPROACHES FROM THE WEST AND A PRE- FRONTAL BAND NEARS THE MOUNTAINS. GUIDANCE CONTINUES TO DIFFER ON TIMING AND EASTWARD EXTENT OF THIS CONVECTION WITH THE NAM/CMC PROGRESSING IT EAST THROUGH THE MOUNTAINS AND INTO THE EAST THIS EVENING...WHILE MOST OTHERS KEEP IT ALONG THE WESTERN SLOPES ONLY. FOR NOW KEPT THE MENTION OF VCTS IN THE WESTERN MOUNTAINS TUESDAY AFTERNOON AND ADDED IN PREVAILING MVFR IN TSRA AT KBLF/KLWB LATE WHERE THE BETTER COVERAGE LOOKS TO EXIST. ALSO ADDED A VCTS EAST TO KROA LATE THIS AFTERNOON AND OUT EAST AROUND 00Z/8PM THROUGH AROUND MIDNIGHT GIVEN LATEST WETTER TRENDS. SW WINDS WILL BECOME GUSTY AHEAD OF THE UPSTREAM COLD FRONT THIS AFTERNOON WITH GUSTS PERHAPS TOPPING 20-25 KTS OUTSIDE ANY CONVECTION. EXPECT MOST COVERAGE TO QUICKLY FADE IN MOST SPOTS AFTER MIDNIGHT AS WINDS DEEPEN FROM THE WEST AND BEST LIFT REDEVELOPS SW OF THE TAF SPOTS OVERNIGHT. PATCHY FOG MORE LIKELY LATER TONIGHT ESPCLY IN THE VALLEYS AND WHERE ANY EARLIER RAINFALL OCCURRED ALONG WITH SOME STRATUS PER NAM IFR BUT WONT GO THAT LOW FOR NOW GIVEN UNCERTAINTY. EXTENDED AVIATION... BEST CHANCE FOR THUNDERSTORMS LOOKS TO BE ON WEDNESDAY ESPCLY IN THE EAST WITH THE BEST PUSH OF UPPER DYNAMICS TO NUDGE THE SFC BOUNDARY THROUGH THE AREA. BUT THE FRONT 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...AND POSSIBLE IFR FOG LATE NIGHTS...MAINLY KBCB AND KLWB. && .EQUIPMENT... COMMS ISSUES WITH KDAN ASOS TRANSMITTING OUT. 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...JH/SK NEAR TERM...JH SHORT TERM...RCS LONG TERM...AMS AVIATION...JH/KK/MBS EQUIPMENT...WP

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