Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 261945 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 345 PM EDT SUN JUL 26 2015 .SYNOPSIS...
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A WEAK COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST MONDAY. SCATTERED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONT. ANOTHER FRONT WILL MOVE INTO THE AREA FROM THE WEST THURSDAY...THEN STALL JUST TO THE SOUTHEAST OF THE AREA FRIDAY INTO THE WEEKEND...BRINGING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS TO THE AREA. OTHERWISE...IT WILL REMAIN WARM AND HUMID THROUGHOUT THE WEEK.
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&& .NEAR TERM /THROUGH MONDAY/...
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AS OF 330 PM EDT SUNDAY... SURFACE HIGH REMAINS OVER THE REGION WITH WEAK SOUTHERLY FLOW ACROSS THE PIEDMONT AND SOUTHEASTERLY FLOW ACROSS THE FOOTHILLS AND BLUE RIDGE. THERE STILL EXIST AN UPPER LEVEL TROUGH WITH WEAK STEERING CURRENTS FROM THE WEST-NORTHWEST. THIS PATTERN IS SIMILAR TO YESTERDAY. EXPECT ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE MOUNTAINS...MORESO ALONG THE BLUE RIDGE...THEN DRIFT EASTWARD INTO THE FOOTHILLS AND POSSIBLY THE PIEDMONT THIS EVENING. ANY OF THESE DIURNAL STORMS THIS AFTERNOON/EVENING SHOULD REMAIN SMALL BUT COULD PRODUCE VERY LOCALIZED HEAVY DOWNPOURS AS PWATS HAVE INCREASED TO OVER AN INCH. MODELS ARE AGGRESSIVE WITH BRINGING FRONTAL SHOWERS...CURRENTLY OVER THE OHIO VALLEY...IN ACROSS CENTRAL AND NORTHERN VIRGINIA OVERNIGHT. WITH VERY LITTLE UPPER LEVEL SUPPORT AND LACK OF MOVEMENT FROM CURRENT CONVECTION...WILL LOWER CHANCES FOR PRECIPITATION OVERNIGHT AND KEEP A MAINLY DIURNAL THEME. THIS FRONT MAY WASHOUT BEFORE CROSSING OVER THE AREA ON MONDAY. IF THIS IS FACT...WE WILL HAVE ANOTHER DAY OF DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS FOR THE AREA. COVERAGE SHOULD BE MORE WIDESPREAD ON MONDAY COMPARED TO THIS WEEKEND. WITH NO FRONTAL PASSAGE AND JUST EXPECTING DIURNAL CONVECTION...INCREASE TEMPERATURES A FEW DEGREES WITH MORE SUNSHINE EXPECTED.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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AS OF 333 PM EDT SUNDAY... WILL SEE THE HEAT RETURN AND ESPECIALLY THE HUMIDITY AS 5H HEIGHTS BUILD FROM THE SOUTHERN PLAINS RIDGE. WILL SEE A WEAK FRONTAL BOUNDARY WITH SHORTWAVE IMPULSE SET UP FROM THE OHIO VALLEY INTO THE CAROLINAS THIS PERIOD. QUESTION WILL BE STRENGTH OF WARMING ALOFT AND WEAKENING OF CAP IN THE EVENING FOR STORM DEVELOPMENT. MODELS ALL ADVERTISE SCATTERED CONVECTION ACROSS MOST OF THE FA MONDAY EVENING BEFORE WEAKENING OVERNIGHT. TUESDAY WILL SEE THE IMPULSE WORK SWD INTO KY/NE TN AND NC...WITH THE GFS/ECMWF HINTING AT CONVECTION FIRING UP ACROSS THE SRN CWA....WHILE THE 12Z NAM IS SCATTERED WITH CONVECTIVE FEEDBACK BULLSEYES ACROSS THE MTNS. WILL MAINTAIN CLOSE TO WHAT THE ECMWF/GFS SHOW WITH 30-40 POPS SOUTH OF HIGHWAY 460 AND ROANOKE RIVER WITH LOWER THREAT NORTH. CONVECTION WANES TUESDAY NIGHT WITH HEIGHTS BUILDING MORE THAN TUESDAY AND THINK WEDNESDAY WILL BE OUR HOTTEST DAY THIS WEEK WITH LESS CONVECTION. WILL LIMIT STORMS TO THE MOUNTAINS...MAINLY SW VA/NW NC. BY WED NIGHT THE UPPER LOW OVER CENTRAL CANADA WORKS EAST TOWARD THE JAMES BAY AREA WITH TROUGH OFFERING LOWER HEIGHTS AND PUSH OF FRONTAL BOUNDARY TOWARD THE OHIO VALLEY BY 12Z THURSDAY. WILL KEEP A FEW EVENING STORMS AROUND IN THE SW...THEN DRY LATE...THINKING ANY FRONTAL CONVECTION WILL WAIT TIL THURSDAY.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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AS OF 220 PM EDT SUNDAY... OVERALL NOT TOO MUCH CHANGE IN THE FORECAST THIS PERIOD. LOOKS LIKE FRONT WILL SLIDE SOUTHEAST THROUGH OUR AREA BY FRIDAY MORNING. QUESTION ARISES ON HOW FAR SOUTHEAST THIS FRONT GETS AS UPPER FLOW WEAKENS AND BECOMES PARALLEL TO THE FRONT. MODELS SHOWING SEVERAL WAVES OF LOW PRESSURE THIS WEEKEND GOING FROM THE GULF COAST TO THE SOUTHEAST COAST...SUCH THAT THIS COULD PUSH THE FRONT NW TOWARD CENTRAL NC. SWING IN THE UPPER TROUGH FAVORS MOST OF THE DEEPER MOISTURE TO STAY OVER THE ATLANTIC COAST INTO THE COASTAL PLAINS SOUTHWEST TOWARD UPSTATE SC. STILL WILL MAINTAIN LOW CHANCE POPS THIS WEEKEND MAINLY FROM THE SOUTHEAST TO UP ACROSS THE BLUE RIDGE OF VA...WITH LITTLE TO NO CHANCE IN THE VIRGINIA/WEST VIRGINIA MOUNTAINS. PRIOR TO THIS...FRONT SWINGS IN AND BOOSTS OUR THREAT OF SHRA/STORMS THURSDAY INTO THURSDAY NIGHT. MAIN IMPACT LOOKS WEAK AS BETTER JET DYNAMICS STAYS WELL NORTH OVER THE MID ATLANTIC/NORTHEAST...SO FORCING WILL BE JUST WITH THE FRONT. SVR THREAT LOOKS LOW WITH THIS FEATURE AND MODELS HAVE BACKED OFF ON RAINFALL AMOUNTS. TEMPS THIS PERIOD WILL START OUT AT OR SLIGHTLY ABOVE NORMAL THURSDAY THEN START TO GET AT OR JUST BELOW NORMAL FOR THE WEEKEND AS WE STAY ON THE NORTHWEST SIDE OF THE FRONTAL BOUNDARY. DEWPOINTS MAY SINK INTO THE 50S BY SATURDAY MORNING INTO WV/ALLEGHANYS.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/... AS OF 114 PM EDT SUNDAY... A HUMID BUT WEAK SURFACE HIGH PRESSURE WILL RESIDE OVER THE REGION TODAY. SOUTHERLY WINDS WILL BE LIGHT THROUGH THIS EVENING BUT COULD HELP PROMOTE SHOWERS ALONG THE BLUE RIDGE THIS AFTERNOON. WINDS ARE ALSO WEAK ALOFT BUT OUT OF THE WEST- NORTHWEST. SHOWERS EXPECTED TO GENERATE ACROSS THE MOUNTAINS THIS AFTERNOON...THEN DRIFT INTO THE FOOTHILLS THROUGH THIS EVENING. COVERAGE OF STORMS WILL BE ISOLATED AND WITH LOW CONFIDENCE WILL MENTION VICINITY SHOWERS AT BLF/LWB/BCB/ROA FOR LATE THIS AFTERNOON. DEBRIS CLOUDS MAY LINGER THROUGH MOST OF THE NIGHT BUT ANY CLEARING COULD LEAD TO FOG FORMING...ESPECIALLY IN AREAS THAT HAVE RAIN TODAY AND IN MOUNTAIN VALLEYS. THE WEAK COLD FRONT WILL DRIFT SLOWLY SOUTHEAST THROUGH MONDAY. SHOWER AND THUNDERSTORM ACTIVITY WILL BECOME MORE WIDESPREAD ON MONDAY WITH THE FRONT IN CLOSE PROXIMITY. OUTSIDE MAINLY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS AND LATE NIGHT/EARLY MORNING MAINLY VALLEY FOG...EXPECT MOSTLY VFR CONDITIONS. EXTENDED AVIATION FORECAST... MOSTLY VFR CONDITIONS EXPECTED MID WEEK AS HIGH PRESSURE RETURNS...BEFORE BETTER CHANCES FOR SHOWERS/THUNDERSTORMS RETURN LATE IN THE COMING WORKWEEK WITH THE NEXT FRONTAL BOUNDARY AND A POTENTIAL DEEP FETCH OF GULF MOISTURE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...WP LONG TERM...WP AVIATION...RCS

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