Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250505 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 105 AM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE EXTENDING FROM NEW ENGLAND SOUTHWARD ALONG THE EASTERN FACE OF THE APPALACHIANS WILL BE REINFORCED TONIGHT AS A SURGE OF CANADIAN AIR MOVES IN FROM THE EASTERN GREAT LAKES. HIGH PRESSURE WILL BRING COOLER AND MUCH DRIER AIR TO THE MID ATLANTIC THROUGH MID WEEK. ANOTHER COLD FRONT WILL APPROACH THE AREA LATE IN THE WORK WEEK...BRINGING ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TODAY/... AS OF 1139 PM EDT SUNDAY... HIGH PRESSURE WEDGE CONTINUES TO STRENGTHEN FROM THE NORTHEAST...BUT CLOUDS ARE SLOWER TO CLEAR WEST OF A LYH-DAN LINE. LOCAL WRF KEEPING THE MAIN CLOUD COVER SHIFTING SLOWLY WEST THROUGH THE NIGHT...SO IT SPILLS INTO FAR SW VA/NW NC...WHILE THE EAST CLEARS OUT. THINK BY MORNING MOSTLY CLOUDY SKIES WILL REMAIN ACROSS THE BLUE RIDGE SOUTH OF ROANOKE...WITH THE REST OF THE AREA SEEING SOME CLEARING. NOT SEEING MUCH OF DRIZZLE PROFILE IN THE SOUNDINGS...BUT TOWARD THE NC MTNS SOME LIGHT DRIZZLE MAY OCCUR OVERNIGHT. WITH MOISTURE IN THE GROUND RUNNING HIGH...AND LIGHT WINDS...THINK PATCHY FOG...LOCALLY DENSE WILL OCCUR IN AREAS THAT CLEAR OUT. ONLY MINOR CHANGES TO TEMPS AS THEY ARE RUNNING A LITTLE WARMER THAN FORECAST DUE TO CLOUD COVER...BUT SHOULD COOL OFF TO FORECAST LOWS IN THE UPPER 50S TO LOWER 60S AREAWIDE. PREVIOUS VALID DISCUSSION... FOR MONDAY...UPPER LEVEL RIDGING THAT IS PROVIDING THE MID MISSISSIPPI RIVER VALLEY WITH VERY WARM CONDITIONS WILL BUILD UP THE OHIO RIVER VALLEY TOWARD OUR AREA. AS SUCH...STRONGER HEATING IS EXPECTED WHICH WILL HELP ERODE ANY LOW CLOUDS AND FOG QUICKLY AFTER 9 AM. ASIDE FROM FAIR WEATHER CLOUDS DURING THE AFTERNOON... MOSTLY CLEAR SKIES CAN BE EXPECTED FOR THE REMAINDER OF THE DAY. EXPECT AFTERNOON HIGHS TO BE MUCH CLOSER TO SEASONABLE...WITH HIGHS RANGING FROM THE MID/UPPER 70S ACROSS THE MOUNTAINS...TO THE LOW 80S ACROSS THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... AS OF 145 PM EDT SUNDAY... FORECAST AREA WILL REMAIN UNDER A 500 MB RIDGE THROUGH THE PERIOD. PRECIPITATION AROUND THE EDGE OF THE RIDGE WILL STAY OUT OF THE COUNTY WARNING AREA BUT THERE MAY BE PERIODS OF MORE CLOUD COVER FROM STORMS IN THE MISSISSIPPI AND OHIO VALLEYS. MODELS HAVE SOME RESIDUAL LOW LEVEL MOISTURE...WELL BELOW 850 MB...ALONG THE EAST SLOPES OF THE SOUTHERN BLUE RIDGE MONDAY NIGHT. OTHERWISE EXPECTING A DRY AIR MASS. 850 MB TEMPERATURES RISE TO AROUND +20 BY WEDNESDAY. SO WITH ANY DECENT SUNSHINE AND MIXING...MAXIMUM TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL THAT DAY. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 1145 AM EDT SUNDAY... UPPER FLOW IS ZONAL WEDNESDAY NIGHT THROUGH THURSDAY WITH STRONG TROUGHING OVER THE GREAT LAKES AND HIGH 500 MB HEIGHTS OVER THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST UNITED STATES. ECMWF KEEPS THE UPPER RIDGE OVER THE SOUTHEAST THROUGH SATURDAY. THE NEXT TROF DOES NOT REACH THE OHIO VALLEY UNTIL EARLY NEXT WEEK. SURFACE FRONT OVER THE OHIO VALLEY MAY DRIFT SOUTH INTO THE FORECAST AREA BY SATURDAY. ANY THREAT OF PRECIPITATION WILL BE UNORGANIZED UNTIL THIS BOUNDARY GETS CLOSER. EVEN THEN THE FORCING LOOKS WEAK. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 1245 AM EDT MONDAY... HIGH END MVFR/LOW END VFR STRATO-CU CIGS CONTINUING TO SLOWLY DIMINISH ACROSS MOST TAF SITES TONIGHT EXCLUDING KBLF WHERE SEEING A SOLID MVFR LAYER STUCK IN PLACE. EXPECTING DRY AIR PUSHING IN FROM THE NE TO ERODE THE REMAINDER OF THE LOWER CIGS FROM THE BLUE RIDGE EAST OVERNIGHT WHILE THE FAR WESTERN AREAS ESPCLY FROM KBLF SOUTH TO KTNB STAY WITH AT LEAST PERIODS OF MVFR TO IFR INCLUDING SOME PATCHY DRIZZLE. MAIN OTHER ISSUE OVERNIGHT WILL BE WITH POSSIBLE FOG/STRATUS FORMATION GIVEN THE WET GROUND AND EASTERLY FLOW WHERE SKIES DO CLEAR AND WINDS GO CALM. THIS MOST LIKELY ACROSS THE EAST WHERE SHOULD SEE SOME LATE NIGHT MVFR AT BOTH KLYH/KDAN WITH PERHAPS LOCAL IFR RIGHT AT SUNRISE. MUCH MORE LOW CONFIDENCE FARTHER WEST WITH QUICK FOG FORMATION POSSIBLE AT KLWB/KBCB PENDING CLEARING WHICH MAY COME TOO LATE FOR ONLY POCKETS OF FOG MAINLY AROUND KLWB. THUS TWEAKED VSBYS UP SOME AT BOTH LOCATIONS AND DELAYED FOG FORMATION GIVEN CURRENT CANOPY SEEN OFF LATEST IR PICS. ANY FOG/LOW CLOUDS WILL ERODE BY MID MORNING IF NOT SOONER...WITH VFR FORECAST FOR MOST OF THE DAY MONDAY. EXPECT A CONTINUED LIGHT EASTERLY FLOW AT 10 KTS OR LESS AND HEATING OF RESIDUAL SURFACE MOISTURE MAKING FOR A SCATTERED CU FIELD BETWEEN 4-6K FEET. SEE THE EQUIPMENT SECTION FOR INFORMATION CONCERNING THE KLYH ASOS. EXTENDED DISCUSSION... HIGH PRESSURE STRETCHING FROM NEW ENGLAND SOUTHWARD ALONG THE EASTERN FACE OF THE APPALACHIANS WILL MAINTAIN DRY CONDITIONS THROUGH MIDWEEK. THE MAIN CONCERNS DURING THIS TIME WILL BE LOCALIZED FOG DURING THE PREDAWN HOURS OF EACH MORNING DUE TO MOIST SOILS...LIGHT WINDS AND MINIMAL CLOUD COVER. THE OFFICIAL NHC FORECAST INDICATES THAT TROPICAL CYCLONE CRISTOBAL NEAR THE BAHAMAS WILL REMAIN WELL OFF THE EAST COAST AND WILL NOT IMPACT THE LOCAL WEATHER. A COLD FRONT WILL SINK SOUTHWARD FROM THE GREAT LAKES ON THURSDAY AND WEAKEN ACROSS OR JUST NORTH OF THE REGION BY FRIDAY. THIS BOUNDARY MAY BRING WIDELY SCATTERED SHOWERS AND STORMS MAINLY TO THE MOUNTAINS FOR WEEKS END WITH ONLY BRIEF PERIODS OF SUB VFR EXPECTED FOR NOW. && .EQUIPMENT... AS OF 200 PM SUNDAY... THE ASOS TEMPERATURE AT LYNCHBURG (LYH) VA REMAINS INOP DUE TO A BOARD FAILURE. TECHNICIANS ARE EXPECTED TO WORK ON THIS MONDAY. TOWER OBSERVERS ARE AUGMENTING DURING NORMAL SERVICE HOURS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF NEAR TERM...CF/NF/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/NF/WP EQUIPMENT...WP

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