Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 242215 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 615 PM EDT SUN AUG 24 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 MONDAY/... AS OF 614 PM EDT SUNDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES ACCORDING TO LAST OBS AND TRENDS ESPECIALLY WHERE CLOUDS ARE THINNING. THE RNKWRFARW LOOKED OVERDONE WITH CONVECTION...ELECTED TO HOLD ON TO LIGHT RAIN AND DRIZZLE FADING TONIGHT. KEPT THE RICHEST CLOUD COVER AND MOISTURE ALONG THE SOUTHERN BLUE RIDGE MOUNTAINS TONIGHT. HIGH PRESSURE WILL BUILD INTO FROM THE NORTHEAST TONIGHT INTO MONDAY. AS OF 230 PM EDT SUNDAY... THE CENTRAL APPALACHIANS AND MID ATLANTIC REMAINS UNDER A BROAD AREA OF LOW CLOUDS THIS AFTERNOON...ALTHOUGH SATELLITE IMAGERY INDICATES THAT A FEW BREAKS ARE DEVELOPING ACROSS THE PIEDMONT AS DRY AIR ASSOCIATED WITH HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. A FEW PATCHES OF VERY LIGHT RAIN OR DRIZZLE REMAIN ALONG THE BLUE RIDGE SOUTH OF ROANOKE...BUT THESE CONTINUE TO FADE AS DRIER AIR WORKS IN. ONLY AREA IT SEEMS THAT IS EXPERIENCING A TRUE SUMMER DAY IN OUR FORECAST REGION IS IN PORTIONS OF THE MOUNTAIN EMPIRE...WHERE DOWNSLOPE FLOW HAS ALLOWED THE CLOUDS TO SCATTER SO THAT TEMPERATURES CAN WARM TO AROUND 80. LOW CLOUDS WILL PERSIST THROUGH THE REMAINDER OF SUNDAY FOR MOST OF THE FORECAST AREA. OVERNIGHT...WINDS WILL SHIFT MORE NORTHEASTERLY AS A REINFORCING PUSH OF HIGH PRESSURE CROSSES THE EASTERN GREAT LAKES AND MOVES OVER NEW ENGLAND. THE WIND SHIFT WILL CUT OFF THE FLOW OF MARINE AIR FILTERING INTO OUR AREA IN FAVOR OF THAT FROM THE DRIER CANADIAN AIR MASS. THAT STATED... MODELS SEEM TO BE A LITTLE AGGRESSIVE IN ERODING THE LOW CLOUDS IN FAVOR OF DRIER AIR...SO MAINTAINED INCREASED CLOUDS ACROSS THE MOUNTAINS AND FOOTHILLS THROUGH MOST OF THE NIGHT. CLOUDS HAVE A BETTER CHANCE OF SCATTERING ACROSS THE PIEDMONT...HOWEVER MAY SEE PATCHY FOG DEVELOP BECAUSE OF THE LIGHT WINDS AND MOIST SOIL CONDITIONS. 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 /MONDAY NIGHT 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 /22Z SUNDAY THROUGH FRIDAY/... AS OF 200 PM EDT SUNDAY... RADAR INDICATES ONLY PATCHES OF DRIZZLE OR VERY LIGHT RAIN REMAIN...MAINLY ALONG THE BLUE RIDGE SOUTH OF KROA...AS HIGH PRESSURE WEDGING AGAINST THE EASTERN FACE OF THE APPALACHIANS HAS BECOME THE DOMINANT WEATHER FEATURE FOR THE AREA. LOWERING OF DEWPOINTS AND SCATTERING OF CLOUDS IN THE VICINITY OF KLYH/KDAN ARE INDICATORS THAT DRIER AIR IS GRADUALLY WORKING ITS WAY IN... HOWEVER IMPROVEMENTS IN IFR/MVFR CONDITIONS WILL BE SLOWER THAN WHAT MOST MODELS SUGGEST. MVFR AND HIGH IFR CONDITIONS WILL REMAIN WIDESPREAD THROUGH THE REMAINDER OF SUNDAY INTO EARLY MONDAY. CLOUDS WILL CONTINUE TO DIMINISH THROUGH THE NIGHT AS LOW LEVEL WINDS SHIFT MORE NORTHEASTERLY...CUTTING OFF THE MAJORITY OF MARINE AIR FLOWING INTO THE REGION. BELIEVE LOW CLOUDS WILL LINGER LONGEST ALONG THE LIP OF THE BLUE RIDGE WHERE UPSLOPE WILL MAINTAIN THE CLOUD COVER. AS CEILINGS ERODE OVERNIGHT...MOIST SOIL CONDITIONS AND LIGHT WINDS MAY CAUSE FOG TO DEVELOP...WHICH WOULD PERSIST UNTIL AFTER 13Z MONDAY. UPPER LEVEL RIDGING BUILDING UP THE OHIO RIVER VALLEY WILL MAKE FOR STRONGER HEATING ON MONDAY...WHICH WILL HELP LOW CLOUDS AND FOG TO ERODE QUICKLY AFTER SUNRISE. AFTER MVFR/IFR ERODES...EXPECT DRY VFR CONDITIONS AND LIGHT NORTHEASTERLY FLOW TO PERSIST THROUGH THE REMAINDER OF THE DAY. 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 THE EARLY HALF OF THE WORK WEEK. 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 CRISTOBOL 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...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS AS WELL AS MVFR/IFR CONDITIONS. && .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...KK/NF SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/NF EQUIPMENT...WP

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