Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 062353 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 753 PM EDT MON JUL 6 2015 .SYNOPSIS... AN UPPER LOW OVER REGION WILL WEAKEN AND SHIFT NORTHEAST TONIGHT. A COLD FRONT APPROACH FROM THE NORTHWEST TUESDAY INTO TUESDAY NIGHT. THE FRONT IS EXPECTED TO STALL JUST NORTH OF THE REGION BY WEDNESDAY...THEN LIFT BACK NORTH AS A WARM FRONT LATE IN THE WEEK...AS HIGH PRESSURE ALOFT BUILDS ACROSS THE SOUTHEAST STATES. && .NEAR TERM /THROUGH TUESDAY/... AS 323 PM EDT MONDAY EDT... AN UPPER LOW AND ASSOCIATED WEAK SURFACE LOW OVER THE REGION WILL LIFT NORTHEAST TONIGHT. SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE TO MOVE NORTHEAST ACROSS OUR AREA THIS AFTERNOON INTO TONIGHT. SOME OF THE STORMS COULD CONTAIN LOCALLY HEAVY RAINS. OVERALL AREAL COVERAGE LOOKS TOO LIMITED TO SUPPORT FLASH FLOOD WATCH. ALS0 CAN NOT COMPLETELY RULE OUT A STRONG STORM IN THE EAST...BUT THE BEST INSTABILITY...MLCAPE VALUES OF 500-1000 AND FORCING ARE NORTHEAST OF OUR AREA. THIS IS HIGHLIGHTED IN THE DAY 1 CONVECTIVE OUTLOOK FROM SPC WITH A MARGINAL RISK OF SEVERE THUNDERSTORMS WITH GUSTY WINDS THE MAIN THREAT. CONVECTION WILL DIMINISH THIS EVENING WITH LOSS OF SOLAR HEATING AND UPPER LOW LIFTING AWAY. WITH SOME CLEARING...ADDED THE MENTION OF FOG TO GRIDS OVERNIGHT. LOW TEMPERATURES TONIGHT WILL RANGE FROM AROUND 60 DEGREES IN THE MOUNTAINS TO THE UPPER 60S IN THE PIEDMONT. A COLD FRONT WILL APPROACH OUR REGION FROM THE OHIO VALLEY ON TUESDAY. CLOUD COVER WILL INCREASE AHEAD OF THE BOUNDARY. ALLOWED FOR ISOLATED POPS OF CONVECTION IN THE WEST TUESDAY AFTERNOON. HOWEVER...MOST AREAS WILL BE DRY FOR TUESDAY. SOUTHWEST FLOW WILL BOOST HIGH TEMPERATURES INTO THE UPPER 70S IN THE NORTHWEST MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 320 PM EDT MONDAY... STRONG COLD FRONT BY JULY STANDARDS WILL APPROACH THE FORECAST AREA FROM THE NORTHWEST TUESDAY NIGHT. IN SPITE OF THE PROGRESSIVE FLOW...THE FRONT IS EXPECTED TO STALL JUST NORTH OF THE REGION PER BUILDING HEIGHTS ASSOCIATED WITH HIGH PRESSURE ALOFT ACROSS THE SOUTHEAST CONUS. RESULT WILL BE FOR OUR FORECAST AREA TO REMAIN ON THE WARM/MOIST SIDE OF THE FRONT...AND SUBJECT TO DAILY THREAT FOR SHOWERS/STORMS. MODELS ARE IN AGREEMENT THAT CONVERGENCE ALONG THE FRONT WILL PROVIDE TRACK FOR ORGANIZED DEEP CONVECTION WITH MARGINAL RISK FOR SEVERE WEATHER PER FASTER WESTERLIES ALOFT NEAR THE FRONTAL ZONE. INCREASING INSTABILITY OUTSIDE OF THE HIGHER WIND ENVELOPE WILL ALSO SUPPORT PULSE STRONG-SEVERE STORMS DURING THE PEAK HEATING WEDNESDAY...AND POSSIBLY THURSDAY PENDING EXTENT OF WARMING ALOFT ASSOCIATED WITH THE BUILDING UPPER LEVEL RIDGE. FORECAST FOR THE FORECAST AREA WILL REFLECT HIGHER POPS ACROSS THE NORTHERN CWA CLOSER TO THE FRONT...AND TO A MUCH LESSER DEGREE ACROSS THE SOUTH...ACROSS OUR NC COUNTIES. TEMPERATURES FOR MID WEEK WILL FAVOR ABOVE NORMAL READINGS PER INCREASING HEIGHTS/THICKNESSES AND A WESTERLY WIND COMPONENT WHICH SHOULD AID IN ADIABATIC WARMING EAST OF THE BLUE RIDGE. WITH 85H TEMPS APPROACHING +20 DEG C...SURFACE READING SHOULD EASILY CLIMB WELL INTO THE 80S AND POSSIBLY THE L-M 90S PENDING SUNSHINE. MINIMUM TEMPERATURES WILL ALSO AVERAGE ABOVE NORMAL...PER THE HIGH MOISTURE CONTENT OF THE ATMOSPHERE. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 200 PM EDT MONDAY... MODELS ARE IN AGREEMENT THE SUBTROPICAL RIDGE THAT BUILDS OVER THE SOUTHEAST STATES FOR MID/LATE WEEK WILL RETROGRADE TOWARD TEXAS/OKLAHOMA FOR THE WEEKEND THEN EXPAND NORTHWEST INTO THE ROCKIES FOR THE FIRST PART OF NEXT WEEK...JULY 13-17. SHORT WAVE ENERGY WHICH WILL INITIALLY TRAVERSE THE NORTHERN TIER STATES THIS WEEK WITH AN ACTIVE FRONTAL ZONE TO OUR NORTH...WILL BEGIN TO TRACK FARTHER SOUTH OVER THE WEEKEND AS THE UPPER RIDGE WANES OVER THE EASTERN CONUS. AS TROUGHING ALOFT INCREASES...EXPECT FRONTAL BOUNDARY TO DRIFT SOUTH OVER THE REGION PROVIDING A BETTER OPPORTUNITY FOR SHOWERS/STORMS IN ADDITION TO MORE CLOUD COVER AND LOWER DAYTIME HIGH TEMPERATURES. HAVE NOT BEEN ABLE TO IDENTIFY ANY GIVEN DAY WHERE WE COULD COMPLETELY REMOVE THREAT FOR SHOWERS/STORMS...THUS ENTIRE EXTENDED PERIOD OF THE FORECAST WILL REFLECT DAILY CHC OF SHOWERS. TEMPERATURES...ALTHOUGH NOTHING EXTREME...WILL FAVOR THE WARM SIDE OF GUIDANCE THIS WEEKEND...THEN RETREAT TO SOMETHING NEAR OR JUST BELOW NORMAL FOR THE START OF THE FOLLOWING WEEK. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 740 PM EDT MONDAY... BASED ON LATEST RADAR TRENDS...CLUSTER OF THUNDERSTORMS WILL BE WITHIN 5SM OF KLYH JUST AT THE 00Z START OF THE TAF PERIOD. THE STORMS WERE MOVING EAST AT 16KTS AND WILL EXIT EAST OF THE AIRPORT BY 01Z/9PM. THUNDERSTORMS ARE NOT EXPECTED TO IMPACT ANY OF THE OTHER REGIONAL AIRPORTS THIS EVENING. LOW PRESSURE WAS NEAR PITTSBURGH THIS EVENING AND WAS MOVING NORTHEAST AWAY FROM THE AREA. MODELS SHOWED DRIER AIR IN THE REGION TONIGHT. HIGH CONFIDENCE THAT CLOUDS WILL CLEAR OUT OVERNIGHT. THERE IS A LOW CHANCE FOR A STRIP OF MVFR STRATOCUMULUS ON THE WESTERN UPSLOPE SIDE OF THE APPALACHIANS LATE TONIGHT. ONCE CLOUDS CLEAR OUT AND DRIER AIR MOVES IN AT MID AND UPPER LEVELS...FOG WILL FORM IN FAVORED VALLEYS AND IN LOCATIONS...INCLUDING KLYH...THAT HAD RAIN MONDAY AFTERNOON AND EVENING. MEDIUM TO HIGH CONFIDENCE OF LIFR VISIBILITIES AT KLWB AND KBCB BETWEEN 09Z/5AM AND 12Z/8AM. CONDITIONS WILL QUICKLY IMPROVE TO VFR AFTER SUNRISE. EXTENDED AVIATION DISCUSSION... A COLD FRONT WILL APPROACH FROM THE OHIO VALLEY BY TUESDAY NIGHT INTO WEDNESDAY. THIS FRONT IS EXPECTED TO STALL JUST NORTH OF THE REGION PER BUILDING HEIGHTS ASSOCIATED WITH HIGH PRESSURE ALOFT ACROSS THE SOUTHEAST CONUS. SOUTH OF THE BOUNDARY...WE WILL REMAIN ON THE WARM/MOIST SIDE OF THE FRONT...AND SUBJECT TO DAILY THREAT FOR MVFR SHOWERS/STORMS. EXPECT WIDESPREAD LATE NIGHT/EARLY MORNING LOW CLOUDS/FOG WITH IFR-LIFR CIGS/VSBYS. OVERALL...CONDITIONS SHOULD IMPROVE TO MVFR- VFR OUTSIDE SHRA/TSRA ACTIVITY DURING THE AFTERNOONS. && .EQUIPMENT... AS OF 700 PM EDT MONDAY... 00Z UPPER AIR RELEASE WAS TRUNCATED DUE TO EQUIPMENT MALFUNCTION. DATA IS ONLY AVAILABLE UP THROUGH 850 MB. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/WP NEAR TERM...KK SHORT TERM...PM LONG TERM...PM AVIATION...AMS/KK EQUIPMENT...AMS

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