Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301959 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 359 PM EDT SAT AUG 30 2014 .SYNOPSIS...
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AN UPPER LEVEL SYSTEM MOVES FROM MISSISSIPPI TO THE OHIO VALLEY THROUGH SUNDAY. THE AREA WILL REMAIN IN A TYPICAL SUMMER AIRMASS INTO TUESDAY. A FRONT ARRIVES FROM THE NORTH BY THURSDAY.
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&& .NEAR TERM /THROUGH SUNDAY/...
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AS OF 300 PM EDT SATURDAY... JUST ISOLATED CONVECTION THIS AFTERNOON ALONG A NOSE OF HIGHER THETAE AND DEEP MOISTURE CONVERGENCE THAT RUNS FROM THE NC MTNS NORTHEAST TO THE ALLEGHANY HIGHLANDS OF VA INTO SE WV. STILL NOT EXPECT MUCH COVERAGE THRU THE EVENING. WILL KEEP THE SLIGHT CHANCE OF SHOWERS ACROSS THE FAR WEST OVERNIGHT...INCREASING THEM 40 POPS BY MORNING AS STRONG UPPER SHORTWAVE MOVES FROM THE LOWER MS VALLEY TO THE OHIO VALLEY. MAIN FLUX OF MOISTURE WILL STAY WEST OF OUR CWA BUT LOOKING AT INCREASED SW FLOW AND CONVERGENCE ALONG WITH OUTFLOW WILL BRING SHOWER CHANCES AS FAR EAST AS INTERSTATE 81 BY 8 AM SUNDAY. LOWS TONIGHT WITH INCREASING CLOUDS AND HIGHER DEWPOINTS WILL BE MUGGY...FROM THE MID 60S TO AROUND 70 AREAWIDE. SUNDAY...MODELS IN SIMILAR AGREEMENT ON TRACK OF UPPER SHORTWAVE BUT DIFFER ON EASTWARD EXTENT AND AMOUNT OF PRECIP. THE 12Z NAM OVERALL LOOKED TO BULLSEYEISH WITH FINGERS OF HIGHER QPF ACROSS THE NC MTNS INTO SW VA...SO LEANED THE FORECAST TOWARD THE 12Z ECMWF/GFS...WHICH FOR THE MOST PART TAKE THE HIGHER POPS ACROSS THE NW NC/SW VA/SRN WV AREA INTO THE SHENANDOAH VALLEY TOMORROW...WITH LESS THREAT OF SHOWERS AND STORMS EAST OF THE DAN/LYH CORRIDOR. TEMPS WILL BE TEMPERED BY THE CLOUD COVER SO LOOKING AT HUMID CONDITIONS WITH HIGHS RANGING FROM THE UPPER 70S-LOWER 80S MOUNTAINS...TO MID TO UPPER 80S EAST.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
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AS OF 315 PM EDT SATURDAY... SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL PERSIST THROUGH SUNDAY NIGHT INTO MONDAY MORNING...WITH GREATEST RAIN CHANCES FOUND WEST OF INTERSTATE 81...AS AN UPPER LEVEL DISTURBANCE SHIFTS ACROSS THE GREAT LAKES FROM THE OHIO RIVER VALLEY. WITH A VERY MOIST ATMOSPHERE IN PLACE...MAY SEE A FEW AREAS OF EXCESSIVE RAINFALL... BUT BELIEVE THE FLOODING THREAT WILL BE LOW DUE TO A WEEK OF DRY CONDITIONS. MAY SEE A FEW SHOWERS REDEVELOP MONDAY AFTERNOON AS WE APPROACH MAXIMUM HEATING...BUT BELIEVE THIS ACTIVITY WILL BE MORE DISORGANIZED DUE TO DRIER CONDITIONS AS HIGH PRESSURE MOVES IN FROM THE SOUTH...AS WELL AS A LACK OF UPPER LEVEL SUPPORT. RAINFALL WILL DIMINISH QUICKLY AS THE SUN SETS AND SHOULD SEE DRY...ALBEIT WARM AND MUGGY...CONDITIONS PERSIST THROUGH MONDAY NIGHT. RAIN CHANCES WILL INCREASE AGAIN ON TUESDAY AS ANOTHER LOW PRESSURE SYSTEM MOVING ACROSS EASTERN CANADA WILL DRAG A COLD FRONT SOUTH OF THE GREAT LAKES. BETTER CHANCES FOR RAIN WILL BE FOUND ACROSS THE MOUNTAINS...WHERE STRONGER UPPER LEVEL SUPPORT WILL BE LOCATED. BELIEVE MODELS ARE TOO AGGRESSIVE IN PUSHING THE FRONT INTO NORTH CAROLINA PER THE 30/12Z RUNS...AND EXPECT THE COLD FRONT WILL STALL FURTHER NORTH DUE TO THE UPPER LEVEL RIDGING IN PLACE ACROSS THE SOUTHEAST STATES...PERHAPS SOMEWHERE BETWEEN THE INTERSTATE 64 AND HIGHWAY 460 CORRIDORS DURING TUESDAY NIGHT. TEMPERATURES WILL REMAIN SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF THE WEEK...WITH HIGHS RANGING FROM THE UPPER 70S/LOW 80S ACROSS THE MOUNTAINS...TO THE LOW 90S ACROSS THE SOUTHSIDE. LOWS WILL FALL INTO THE MID 60S TO LOW 70S.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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AS OF 330 PM SATURDAY... UPPER LEVEL RIDGING WILL SHIFT NORTHWARD FROM THE SOUTHEAST STATES OVER THE MID ATLANTIC DURING THE SECOND HALF OF THE WEEK...RESULTING IN BOTH WARMER TEMPERATURES AND WEAKER WINDS ALOFT. THIS WILL MAKE FOR MORE STABLE CONDITIONS THAT WILL KEEP SHOWER AND THUNDERSTORM ACTIVITY DISORGANIZED THROUGH THE PERIOD. ANY RAINFALL WHICH DEVELOPS WILL BE DRIVEN MAINLY BY DAYTIME HEATING...WHICH WILL ALLOW THIS ACTIVITY TO FIZZLE AFTER SUNSET. EXPECT WIDELY SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM OR TWO TO DEVELOP WEDNESDAY AFTERNOON ALONG THE STALLED FRONTAL BOUNDARY... WHEREVER IT IS LOCATED. HIGH PRESSURE PASSING ACROSS THE GREAT LAKES SHOULD KEEP THE NORTHERN HALF OF OUR AREA DRY. HIGH PRESSURE WILL PASS OFF THE NEW ENGLAND COAST ON THURSDAY... RESULTING IN A WEAK WEDGING PATTERN WITH EASTERLY FLOW OFF THE ATLANTIC. THIS WILL LIKELY BE THE DRIEST DAY OF THE PERIOD. WINDS WILL SHIFT SOUTHWESTERLY AGAIN ON FRIDAY AS ANOTHER COLD FRONT SINKS SOUTH FROM THE GREAT LAKES. STRONGER FLOW OFF THE ATLANTIC WILL RESULT IN INCREASED MOISTURE...AND WILL EXPECT SPOTTY SHOWER AND THUNDERSTORM ACTIVITY DURING THE AFTERNOON AND EVENING. EXPECT TEMPERATURES TO REMAIN SLIGHTLY ABOVE NORMAL FOR THE PERIOD.
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&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/... AS OF 130 PM EDT SATURDAY... AUTOMATED OBS SHOWING MORE CLOUD COVER THAN REALITY PER SAT/WEB CAMS. MAINLY SCT FIELD OF CU THIS AFTERNOON...AT TIMES BKN. NOT REALLY SEEING ANY TAF SITE THREATENED BY SUB VFR OR CONVECTION. BEST CHANCE OF ANY SHRA/TSRA WOULD BE NEAR ROA/LWB...BUT GIVEN LACK OF VERTICAL STRUCTURE WILL NOT HIGHLIGHT ANY IN THE TAFS. TONIGHT...MODELS SHOWING THE UPPER SHORTWAVE THAT IS OVER THE LOWER MS VALLEY THIS AFTERNOON...TO MOVE INTO THE OHIO VALLEY OVERNIGHT. WILL NOT REALLY SEE ANY GOOD THREAT OF SHOWERS UNTIL SUNDAY MORNING AFTER 12Z WEST OF A LWB/BLF LINE...AND ADDED VCSH AT BLF BY 14Z. OVERALL WILL SEE VFR THOUGH SOME FOG AND/OR LOW CLOUDS COULD FORM NEAR DAN/LWB/ROA/BCB LATE...BUT CONFIDENCE OVERALL IS LOW. EXTENDED DISCUSSION... SUNDAY AN AREA OF LOW PRESSURE WILL HEAD EASTWARD THROUGH THE SOUTHERN QUEBEC. ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION. ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS. && .EQUIPMENT... AS OF 730 AM EDT FRIDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...NF LONG TERM...NF AVIATION...AMS/WP EQUIPMENT...AMS

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