Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 071137 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 737 AM EDT TUE JUL 7 2015 .SYNOPSIS... A COLD FRONT APPROACHES FROM THE NORTHWEST TONIGHT. 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 TONIGHT/... AS OF 710 AM EDT TUESDAY... FOG...DENSE OVER PORTIONS OF THE NEW RIVER VLY INTO GREENBRIER EXPECTED TO BURN OFF/DISSIPATE BY 9-10AM. NO OTHER MAJOR ADJUSTMENTS MADE TO THE PREVIOUS FORECAST. PREVIOUS DISCUSSION... TODAY WILL BE OUR DRIER OF THE NEXT FEW DAYS AS WE ARE BETWEEN IMPULSES IN THE UPPER LEVELS. STILL NOT A 100 PERCENT CHANCE OF DRY...AS THERE WILL BE SOME WEAK CONVERGENCE IN THE MOUNTAINS AIDED BY DIFFERENTIAL HEATING...TO ALLOW FOR SOME POP UP STORMS. AT THIS TIME...THE BEST CHANCES WILL BE ALONG AND WEST OF INTERSTATE 77 AND MORE INTO WV/FAR SW VA INTO KY. A VERY WARM DAY SINCE MORE SUNSHINE IS EXPECTED WITH SW FLOW AND BUILDING HEIGHTS. PREVIOUS FORECAST OF MID 80S WEST TO LOWER 90S EAST LOOKS GOOD. TONIGHT...A FRONTAL BOUNDARY WILL SAG SOUTHEAST TOWARD THE UPPER OHIO VALLEY INTO KY AND MODELS ARE KEEPING THE MAJORITY OF THE FORECAST AREA DRY WITH THE ACTIVE WX STAYING IN A REGION FROM MISSOURI TO WRN PA. STILL CONVECTIVE OUTFLOWS AHEAD OF THIS ACTIVITY MAY WORK INTO THE MTNS OF WV OVERNIGHT...SO KEPT HIGHER POPS OVER THE GREENBRIER VALLEY...WITH SLIGHT CHANCE AS FAR EAST AS THE SHENANDOAH VALLEY TO NC MTNS. MUGGY LOWS EXPECTED WITH MID TO UPPER 60S MOUNTAINS...TO LOWER 70S EAST. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 330 AM EDT TUESDAY... UPPER LEVEL RIDGING ACROSS THE SOUTHEAST STATES WILL BUILD WEST ALONG THE GULF COAST ON WEDNESDAY...ALLOWING FOR INCREASINGLY ZONAL FLOW ACROSS THE MID ATLANTIC. THE BUILDING RIDGE WILL HELP KEEP AN APPROACHING COLD FRONT NORTH OF OUR AREA FOR WEDNESDAY AFTERNOON AND EVENING...CAUSING IT TO STALL NEAR THE OHIO RIVER. REGARDLESS... STILL SUFFICIENT INSTABILITY ASSOCIATED WITH A PASSING UPPER LEVEL DISTURBANCE RIDING ALONG THE FRONT TO TRIGGER WIDELY SCATTERED THUNDERSTORMS DURING LATE AFTERNOON AND EVENING...WITH RAIN CHANCES HIGHEST NEAR THE INTERSTATE 64 CORRIDOR. INSTABILITY PARAMETERS ARE MODEST FOR THE MOST PART...BUT INDICATE ENOUGH CAPE AND LOW LEVEL SHEAR TO TRIGGER A FEW STRONG TO SEVERE STORMS...CAPABLE OF PRODUCING HAIL AND LOCALLY STRONG WINDS. THE FRONT WILL DRIFT NORTHWARD ON THURSDAY AS YET ANOTHER LOW PRESSURE SYSTEM PASSES JUST SOUTH OF THE GREAT LAKES...AND EXPECT MINIMAL SHOWER AND THUNDERSTORM ACTIVITY FOR MUCH OF THE DAY. RAIN CHANCE WILL INCREASE DURING THE EVENING HOWEVER AS THE LOW PUSHES EAST FOR THE UPPER MID ATLANTIC...DRAGGING A COLD FRONT SOUTHWARD TOWARD OUR REGION. BEST RAIN CHANCES WILL BE ACROSS THE WESTERN SLOPES...WITH NORTHWESTERLY DOWNSLOPE WINDFLOW FURTHER EAST CAUSING SHOWERS AND THUNDERSTORMS TO BREAK UP. THE COLD FRONT WILL PASS ACROSS OUR ARE THURSDAY NIGHT...AND STALL JUST TO OUR SOUTH FOR FRIDAY. WILL HAVE TO KEEP AN EYE TO OUR NORTHWEST FOR ANY APPROACHING DISTURBANCES AS THE CENTER OF UPPER LEVEL RIDGING SHIFTS TO THE LOWER MISSISSIPPI RIVER VALLEY...SHIFT UPPER LEVEL WINDS ACROSS THE MID ATLANTIC FROM THE NORTHWEST. WITH OUR AREA SOUTH OF THE FRONT ON WEDNESDAY THURSDAY...EXPECT AFTERNOON HIGHS TO RANGE FROM THE LOW/MID 80S ACROSS THE MOUNTAINS...TO THE UPPER 80S/LOW 90S ACROSS THE PIEDMONT. FRONTAL PASSAGE THURSDAY NIGHT WILL KNOCK OFF A FEW DEGREES FOR HIGHS ON FRIDAY...RANGING FROM LOW 80S WEST TO LOW 90S EAST. OVERNIGHT LOWS WILL RANGE FROM THE MID 60S TO THE LOW 70S. && .LONG TERM /SATURDAY 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 /12Z TUESDAY THROUGH SATURDAY/... AS OF 110 AM EDT TUESDAY... FOG AT ALL SITES BUT ROANOKE...AND VLIFR ATTM AT LWB/BCB. THIS FOG WITH SOME LOW CIGS WILL LIFT/ERODE BY 13-14Z. VFR EXPECTED THROUGH THIS AFTERNOON AND EVENING. STORMS THIS AFTERNOON SHOULD BE MAINLY ISOLATED AND CONFINED WEST OF THE WV/VA BORDER. BETTER EASTWARD SHIFT OF THE FRONT TONIGHT MAY BRING A FEW SHRA/TSRA TOWARD BLF/LWB LATE...SO ATTM HAVE ADDED VCSH FOR LWB...AS THINK THE TIMING IS IFFY. OVERNIGHT AS WELL FOG SHOULD FORM AGAIN AT LWB/BCB AND PERHAPS DAN...THOUGH MORE HIGH CLOUDS FROM UPSTERAM CONVECTION MAY LIMIT FOG BECOMING DENSE. EXTENDED AVIATION DISCUSSION... A COLD FRONT WILL STALL NEAR THE WV/MD BORDER WEST TO OHIO BY WEDNESDAY. SOUTH OF THIS 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. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/WP NEAR TERM...WP SHORT TERM...NF LONG TERM...PM AVIATION...AMS/KK/WP

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