Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 271733 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 133 PM EDT THU AUG 27 2015 .SYNOPSIS... HIGH PRESSURE OVER THE OHIO VALLEY WILL MOVE EAST TODAY AND TONIGHT. LOW PRESSURE WILL REMAIN OVER THE SOUTHEAST UNITED STATES WITH A FRONT TRAILING UP THE CAROLINA COAST THROUGH SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM EDT THURSDAY... QUIET DAY ACROSS THE REGION. SCT TO BKN CLOUD COVER ACROSS THE MOUNTAINS WHILE MOSTLY CLEAR ACROSS THE PIEDMONT. HELD TEMPERATURES IN CHECK WITH PREVIOUS FORECAST PACKAGE. SLIGHT CHANCE OF AN ISOLATED SHOWER ACROSS THE NW NC MOUNTAINS AND SOUTHERN BLUE RIDGE HOWEVER WITH LITTLE FORCING PRESENT HAVE KEPT POPS LOW. AS OF 300 AM EDT THURSDAY... SATELLITE PICTURES SHOWED SCATTERED TO BROKEN CLOUD COVER EARLY THIS MORNING. FOG WAS ALREADY DEVELOPING IN AREA THAT REMAINED CLEAR. MSAS ANALYSIS INDICATED A LARGE SPREAD IN SURFACE DEW POINTS ACROSS THE FORECAST AREA FROM AROUND 50 IN SOUTHEAST WEST VIRGINIA TO THE LOWER 60S SOUTHEAST OF DANVILLE. AS SURFACE HIGH PRESSURE OVER THE OHIO VALLEY MOVES EAST TODAY AND A COASTAL TROF REMAINS ALONG THE CAROLINAS...SURFACE AND LOW LEVEL WINDS WILL TURN TO THE NORTHEAST AND EAST. THIS KEEP HIGHER DEW POINTS OVER THE FOOTHILLS AND PIEDMONT. HAVE TRIMMED BACK PROBABILITY OF PRECIPITATION IN THE SOUTHWEST COUNTY WARNING AREA FOR THIS AFTERNOON AND EVENING. ASIDE FROM AN EASTERLY COMPONENT TO THE WIND...LITTLE FORCING IS EXPECTED TODAY. STAYED CLOSE TO MAV GUIDANCE FOR HIGHS TODAY AND LOWS TONIGHT. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM EDT THURSDAY... UPPER LEVEL TROUGHING AFFECTING THE EASTERN UNITED STATES THE PAST FEW DAYS WILL FILL AND RETROGRADE WESTWARD ON FRIDAY...ALLOWING THE SOUTHEAST AND MID ATLANTIC TO COME INCREASINGLY UNDER THE INFLUENCE OF SUBTROPICAL RIDGING NUDGING IN FROM THE ATLANTIC. ON FRIDAY...WINDS WILL SHIFT FROM NORTHEASTERLY IN THE MORNING TO EAST SOUTHEASTERLY LATER IN THE DAY AS HIGH PRESSURE MOVES OFFSHORE OF NEW ENGLAND. THE EASTERLY FLOW WILL OPEN OUR AREA TO MARINE AIR...WHICH WILL RESULT IN INCREASED CLOUDS AREAWIDE...AND A SLIGHT CHANCE FOR AFTERNOON/EVENING MOUNTAIN SHOWERS AS THE MOISTURE IS FORCED UPSLOPE. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL...WITH HIGHS RANGING FROM THE LOW/MID 70S ACROSS THE MOUNTAINS...TO THE LOW 80S ACROSS THE PIEDMONT. WITH LITTLE CHANGE IN THE WEATHER PATTERN FOR SATURDAY...SIMILAR WEATHER CONDITIONS CAN BE EXPECTED...ALBEIT WITH SLIGHTLY HIGHER COVERAGE OF SHOWER ACTIVITY ACROSS THE MOUNTAINS. INCREASED INFLUENCE FROM THE SUBTROPICAL RIDGE WILL HELP SATURDAY AFTERNOON HIGHS WARM 2 TO 3 DEGREES OVER THOSE OF FRIDAY. FOR SUNDAY...A WAVE OF LOW PRESSURE APPROACHING FROM THE SOUTH WILL LIFT A PLUME OF TROPICAL MOISTURE NORTHWARD ALONG THE APPALACHIAN CHAIN...RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS FOR MUCH OF OUR AREA. AS MOISTURE CREEPS BACK INTO THE AREA OVER THE WEEKEND...EXPECT OVERNIGHT TEMPERATURES TO BECOME INCREASINGLY MILD EACH NIGHT. OVERNIGHT LOWS WILL BE IN THE MID 50S TO THE LOW 60S MOST LOCATIONS FRIDAY NIGHT...WARMING INTO THE LOW TO MID 60S AREAWIDE BY SUNDAY NIGHT. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 1240 PM EDT WEDNESDAY... UPPER LEVEL TROUGHING WILL DRIFT ACROSS THE APPALACHIANS ON MONDAY...WITH SLIGHTLY WEAKENING RIDGING TO THE EAST. GIVEN CONTINUED SOUTHERLY FLOW...WILL MAINTAIN DIURNAL OROGRAPHIC DRIVEN CONVECTION IN THE FORECAST...BUT GIVEN PROGGED WEAK INSTABILITY AND WEAK UPPER DIFFLUENCE AHEAD OF THE UPPER LOW TO THE WEST...COULD BE MORE WIDESPREAD IF A WEAK WAVE DOES SLIDE UP FROM THE SOUTHEAST. UPPER RIDGING WILL STRENGTHEN AGAIN BY MID WEEK AIDED BY SUBSIDENCE TO THE NORTH PER THE PROBABLE ARRIVAL OF ERIKA OVER FLORIDA. THUS WILL KEEP MORE ISOLATED MOUNTAIN CONVECTION FOR TUESDAY INTO WEDNESDAY WITH HIGHER HEIGHTS IN PLACE. OTHERWISE WILL BE RETURNING TO QUITE A WARM/MUGGY SCENARIO THROUGH THE PERIOD WITH HIGHS MOSTLY 80S AND POSSIBLY NEAR 90 SE...AND LOWS MOSTLY IN THE 60S. && .AVIATION /18Z THURSDAY THROUGH MONDAY/... AS OF 1230 PM EDT THURSDAY... A RELATIVELY QUIET WEATHER PATTERN WITH SUBTLE FEATURES TO CONTEND WITH THROUGH THIS TAF PERIOD. SURFACE HIGH PRESSURE WILL BE SLIDING BY TO OUR NORTH AND GIVING US LIGHT ELY/NELY WINDS...WHILE A PROGRESSIVE PATTERN FEATURING WEAK TROFING ALOFT WILL KEEP SOME SHORT WAVE ENERGY FLOWING THROUGH THE REGION. BELIEVE THERE WILL BE ENOUGH OROGRAPHIC FORCING ALONG AND WEST OF THE BLUE RIDGE TO GENERATE A MOSTLY VFR CEILING...BUT BELIEVE ANY SHOWERS WILL BE ISOLATED AND NOT MERIT A MENTION IN TAFS AT KLWB/KBLF/KBCB. EXPECT SITES EAST OF THE BLUE RIDGE TO BE DRY WITH SCT/V/BKN VFR CLOUDS. TONIGHT SHOULD BE ANOTHER MOSTLY CLEAR NIGHT WITH DECENT RADIATIONAL COOLING. THIS SHOULD GENERATE LIFR CONDITIONS AT KLWB WITH THIN FOG AND SCT STRATUS FOR KBLF/KBCB. THERE MAY BE SOME THIN FOG ALSO AT KLYH AND KDAN BUT BELIEVE PROBABILITY IS LOW ENOUGH AVOID USING A TEMPO GROUP TOWARD DAYBREAK SO WILL NOT INDICATE ANY OBVIS. ANY FOG/STRATUS WILL DISSIPATE AFTER DAYBREAK AND MODEL SOUNDINGS INDICATE MAINLY SCT CLOUDS THEREAFTER. EXTENDED AVIATION DISCUSSION... EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY INCREASES BY THE WEEKEND WITH ISOLATED TO SCATTERED CONVECTION POSSIBLE...WITH BRIEF PERIODS OF MVFR CIGS/VSBYS POSSIBLE. TYPICAL LATE NIGHT/EARLY MORNING MVFR TO LIFR FOG THREAT AT LWB/BCB/LYH THROUGH THE PERIOD. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/CF SHORT TERM...NF LONG TERM...JH AVIATION...MBS/AMS

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