Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 130812 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 412 AM EDT SUN JUL 13 2014 .SYNOPSIS...
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HIGH PRESSURE WILL GIVE WAY TO RETURN SOUTHWEST FLOW AND INCREASING MOISTURE TODAY. A STRONG COLD FRONT APPROACHES FROM THE WEST ON MONDAY AND CROSS THE REGION ON TUESDAY. COOL HIGH PRESSURE FOLLOWS THE FRONT FOR THE LATTER HALF OF NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 400 AM EDT SUNDAY... CLOUD COVER SHOWN BY SATELLITE PICTURES OVER THE OHIO VALLEY AND CIRRUS FROM THE THUNDERSTORMS OVER INDIANA AND ILLINOIS WILL MOVE INTO THE FORECAST AREA THIS MORNING. TEMPERATURES WERE ALREADY MILD...IN THE MID 60S TO LOWER 70S SO EVEN WITH ONLY OCCASIONAL BREAKS IN THE CLOUDS...MAXIMUM TEMPERATURES WILL CLIMB INTO THE LOWER 80S TO LOWER 90S. BUFKIT FORECAST SOUNDINGS SHOWED NARROW CAPE...POSSIBLY UP TO 800 J/KG WITH ENOUGH OF A WARM LAYER ABOVE 600 MB TO CAP SOME OF THE DEVELOPMENT OF THUNDERSTORMS. EXPECT COVERAGE OF THUNDERSTORMS TO BE SIMILAR TO SATURDAY...MAINLY ALONG AND JUST EAST OF THE BLUE RIDGE...ESPECIALLY SOUTH OF ROANOKE WHERE THE LOW LEVEL CONVERGENCE IS THE BEST THIS AFTERNOON. MODELS WERE SHOWING DIFFERENT SOLUTIONS TO HOW MUCH THE UPSTREAM SHOWERS AND THUNDERSTORMS WILL IMPACT THE NORTHWEST COUNTY WARNING AREA OVERNIGHT. AXIS OF HEAVIEST PRECIPITATION AND BEST PRECIPITATION POTENTIAL PLACEMENT LOOKS LIKE IT WILL EXTENDED FROM SOUTHWEST PENNSYLVANIA TO SOUTHEAST MISSOURI...STAYING JUST NORTHWEST OF THE FORECAST AREA. HAVE HELD PROBABILITY TO CHANCE RANGE FOR TONIGHT.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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AS OF 320 AM EDT SUNDAY... THE UPPER TROUGH WILL AMPLIFY AND SHIFT SOUTHEAST THE GREAT LAKES AND OHIO VALLEY REGIONS. THE MAIN COLD FRONT WILL APPROACH FROM THE WEST ON MONDAY WITH INCREASING SHEAR AND MOISTURE. SWODY2 HAS PLACED OUR AREA IN A SLIGHT RISK FOR WELL-ORGANIZED MULTICELLS/LINE SEGMENTS CAPABLE OF DAMAGING WINDS AND SOME HAIL. MONDAY MORNING SHOWERS AND THUNDERSTORMS WITH ASSOCIATED CLOUD COVER MAY BE INFLUENTIAL FACTORS IN THE OVERALL INSTABILITY. SOME GOOD CONVERGENCE IN LEE TROUGH DEVELOPS LATER MONDAY AFTERNOON WHICH SUGGEST THAT THERE MAY BE BETTER SEVERE POTENTIAL ALONG AND EAST OF THE BLUE RIDGE. IN GENERAL...DECREASED MORNING POPS AND QPF ESPECIALLY OUT EAST. KEPT THE HIGHEST POPS IN THE WEST BUT NUDGED THE EAST UP MONDAY AFTERNOON. PLAYED HIGH TEMPERATURES CLOSE TO ADJMAVBC WITH READINGS FROM THE LOWER 80S IN THE WEST TO THE MID 90S IN THE EAST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS CONTINUE MONDAY NIGHT WITH PLENTY OF MOISTURE AND FRONTAL BOUNDARY MOVING INTO WEST. LOW TEMPERATURES MONDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE MOUNTAINS TO THE LOWER 70S IN THE PIEDMONT. COLD FRONT WILL MOVE EAST ACROSS THE REGION TUESDAY WITH SHOWERS AND THUNDERSTORMS. MODELS SUGGESTING A MUCH STRONGER LEE TROUGH DEVELOPING AND IDEA THAT THE SFC FRONT WILL JUMP INTO THE PIEDMONT TUESDAY AFTERNOON. ANY SEVERE POTENTIAL SHOULD BE ACROSS EAST...AND DEPENDING ON WHERE THE BOUNDARY IS BY MID AFTERNOON...IT COULD ACTUALLY BE JUST SOUTHEAST OF THE FORECAST AREA. SWODY3 PLACED THE SLIGHT RISK OF SEVERE THUNDERSTORM WITH 15 PERCENT ACROSS THE CAROLINA AND SOUTHEASTERN VIRGINIA. WENT WITH THE COOLER ADJMET HIGHS FOR TUESDAY FROM THE MID 70S TO THE MID 80S DUE TO EXTENSIVE CLOUD COVER AND SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. SOME COOLER AND SLIGHTLY DRIER AIR TO BEGIN PUSHING IN FROM WEST OVERNIGHT TUESDAY NIGHT...BUT TRENDS ARE TO SLOW THIS MOISTURE BOUNDARY DOWN A BIT...AND STILL THINK THERE COULD BE LINGERING SHOWERS IN THE EAST MUCH OF THE NIGHT WITH SLOWLY MOVING BOUNDARY. LOW TEMPERATURES TUESDAY NIGHT WILL DROP TO THE MID 50S IN THE WEST TO THE MID 60S IN THE EAST.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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AS OF 1230 PM EDT SATURDAY... BY 12Z WEDNESDAY MORNING THE COLD FRONT WILL BE ALONG THE EAST COAST. HIGH PRESSURE BUILDS IN BRINGING DRIER AND MUCH COOLER CONDITIONS. AS THE HIGH SHIFTS TO THE EAST TOWARDS THE NE STATES BY THE END OF THE WEEK OUR WIND DIRECTION WILL GRADUALLY SHIFT FROM NW TO AN E/SE FLOW. THERE WILL BE A NOTICEABLE DROP IN HUMIDITY BEHIND THE FRONT AS DEWPOINTS CRASH INTO THE 40S AND 50S. 850MB TEMPS WILL RANGE FROM +11-15C WHICH WILL COORDINATE TO SURFACE TEMPS 5-10F BELOW NORMAL. HIGHER ELEVATIONS OF THE MOUNTAINS MAY NOT MAKE IT OUT OF THE 60S ON WEDNESDAY AND THURSDAY...WHILE EVEN LOWER LYING AREAS WILL ONLY RANGE FROM THE LOW 70S TO NEAR 80 EAST OF THE BLUE RIDGE. NIGHT TIME LOWS WILL ALSO BE 5-10F BELOW NORMAL. WHILE ITS TOO SOON TO TALK ABOUT ANY POTENTIAL RECORD LOWS...SEVERAL OF THEM MAY BE WITHIN REACH SHOULD WE GET SUFFICIENT RADIATIONAL COOLING. AT THE END OF THE PERIOD...THE GFS CONTINUES TO HINT AT A SHORTWAVE DISTURBANCE PIVOTING TOWARDS THE REGION FROM THE SOUTHERN PLAINS FOR FRIDAY AND SATURDAY. THE FLOW BECOMES MORE SOUTHERLY AND MOISTURE INCREASES AHEAD OF THE DISTURBANCE. PLACED A BROAD AREA OF LOW CHANCE POPS ACROSS THE AREA FOR THOSE TWO DAYS.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/... AS OF 125 AM EDT SUNDAY... HIGH PRESSURE WAS OFFSHORE WITH BROAD SOUTHWEST FLOW BRINGING DEEP MOISTURE BACK INTO THE REGION. MVFR FOG HAD DEVELOP AT KBCB WHERE IT RAINED BRIEFLY SATURDAY EVENING. VISIBILITY MAY OCCASIONALLY DROP TO LIFR THROUGH 12Z/8AM AT KBCB. EXPECTING VFR CONDITIONS FOR THE REST OF THE NIGHT AT KROA/KDAN AND KBLF. SOME MVFR FOG MAY DEVELOP AT KLYH AND KLWB...BUT THIS WILL BE DEPENDENT ON THE AMOUNT OF CLOUD COVER. AT 06Z/2AM SATELLITE PICTURES SHOWED A BAND OF MID LEVEL CLOUDS FROM NEW YORK TO NORTHWEST NORTH CAROLINA MOVING EAST. HIGH CONFIDENCE THAT MORE CLOUDS FROM OUT OF THE OHIO VALLEY AND FROM THUNDERSTORMS OVER ILLINOIS WILL REACH THE FORECAST AREA THIS MORNING.HOWEVER...CEILINGS WILL REMAIN VFR. SUNDAY WILL BE COMPARABLE TO SATURDAY WITH MAINLY VFR CONDITIONS. CLOUD BUILD-UPS EXPECTED BY EARLY AFTERNOON...WITH SCATTERED MID/LATE AFTERNOON SHOWERS...PRIMARY DEVELOPMENT VCNTY OF THE MOUNTAINS. KBCB AND KROA ARE THE MOST LIKELY LOCATIONS TO BE IMPACTED WITH A THUNDERSTORM. EXTENDED AVIATION DISCUSSION... MONDAY NIGHT THROUGH TUESDAY NIGHT...A BETTER CHANCE OF SHOWER AND THUNDERSTORM ACTIVITY...ALONG WITH THE POTENTIAL FOR A GREATER COVERAGE OF SUB-VFR CONDITIONS WILL EXIST THANKS TO A DEEP UPPER LEVEL LOW/TROUGH AND ITS ASSOCIATED DYNAMICS PROGRESSING EASTWARD THROUGH THE GREAT LAKES REGION AND THEN INTO NEW ENGLAND. ITS ASSOCIATED SURFACE FEATURES WILL OFFER A COLD FRONTAL PASSAGE TUESDAY AFTERNOON OR EVENING ALONG WITH A SLIGHT CHANCE OF SEVERE WEATHER AS OFFERED BY THE STORM PREDICTION CENTER. HIGH PRESSURE WILL TRY TO WORK ITS WAY INTO THE AREA WEDNESDAY INTO THURSDAY. THERE IS SOME QUESTION AS TO JUST HOW FAR SOUTH OF THE AREA THE COLD FRONT WILL MAKE IT BEFORE THE REGION IS ON THE WEST SIDE OF THE HIGH...AND THUS WE RETURN TO A SOUTHERLY FLOW OF MOISTURE INTO THE AREA. EITHER WAY...LOW LEVEL MOISTURE WILL LIKELY NOT COMPLETELY DRY OUT...AND THE POTENTIAL FOR OVERNIGHT IFR/MVFR FOG IS PROMISING...ESPECIALLY FOR AREAS THAT RECEIVE THE MOST RAINFALL MONDAY INTO TUESDAY. BY FRIDAY...MOST GUIDANCE IS IN AGREEMENT THAT A WAVE WILL MOVE ALONG THE STALLED FRONT AND BRING ANOTHER SUBSTANTIAL ROUND OF SHOWERS AND STORMS TO THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/SK NEAR TERM...AMS SHORT TERM...KK LONG TERM...CF AVIATION...AMS/PM

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