Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 251323 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 923 AM EDT TUE AUG 25 2015 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST FROM THE PLAINS THROUGH THE WEEK...KEEPING US DRY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 923 AM EDT TUESDAY... HIGH PRESSURE FROM THE PLAINS WILL SLIDE EASTWARD AND NUDGE YESTERDAYS COLD FRONT EAST TOWARDS THE ATLANTIC OCEAN. DRIER AIR WILL CONTINUE TO ADVANCE SOUTHEAST TODAY INTO TONIGHT. SUNSHINE WITH SOME CU EXPECTED THIS AFTERNOON OVER THE PIEDMONT EARLY AND IN THE TROUGH AXIS ACROSS THE WESTERN MOUNTAINS. HIGH THIS AFTERNOON WILL BE PLEASANT WITH READINGS FROM THE LOWER 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT. TONIGHT...THE AXIS OF THE 5H TROUGH MOVES EAST ALONG WITH THE SFC RIDGE. MOSTLY CLEAR CONDITIONS ANTICIPATED WITH LOW TEMPERATURES FROM LOWER 40S IN THE COLDER VALLEYS TO THE LOWER 60S IN THE PIEDMONT. ENJOY THE GREAT WEATHER ! AS OF 345 AM EDT TUESDAY... AREA OF HIGH PRESSURE WILL EXTEND FROM THE PLAINS EASTWARD INTO WV/PA...WHILE A FRONT EAST OF US STAYS SITUATED FROM THE MID ATLANTIC COAST SOUTH TO SC. QUITE A SHARP GRADIENT IN AIRMASS TO BE FELT FROM WEST TO EAST TODAY WITH DRIER AIR PUSHING INTO THE BLUE RIDGE...WHILE THE PIEDMONT THOUGH DRIER WILL STILL HAVE SOME MID 60S DEWPOINTS. THE 00Z NAM SEEMS TO GRAB THE SHOWERS OVER THE TRIAD OF NC INTO SOUTHSIDE VA THIS MORNING. AS WE HEAD THROUGH THE MORNING ISOLATED SHOWERS WILL BE FOUND MAINLY EAST OF A DANVILLE TO REIDSVILLE LINE...THEN SHOULD DEFINITELY SEE THE MAIN FOCUS SHIFT FURTHER EAST BY MID MORNING. SHOULD BE SUNNY TODAY...THOUGH SOME CU SITUATED OVER THE PIEDMONT EARLY ON AND A FEW IN THE TROUGH AXIS ACROSS THE WV/FAR SW VA MTNS...BUT NO IMPACT ON TEMPS. HIGHS TODAY WILL BE ABOUT 5 TO 8 DEGREES COOLER THAN LATE AUGUST NORMS OVER THE MOUNTAINS...WITH MID 70S EXPECTED. FROM THE ROANOKE VALLEY EAST TO THE PIEDMONT...TEMPS WILL MAX OUT IN THE MID 80S. TONIGHT...THE AXIS OF THE 5H TROUGH MOVES EAST AS DOES THE SFC RIDGE. WE SHOULD BE GENERALLY CLEAR MOST OF THE NIGHT...WITH LIGHT WINDS. COOP MOS SHOWING LOWER 40S DEEPER VALLEYS OF THE WEST...AND TREND HAS BEEN A FEW DEGREES WARMER THAN 2 NIGHTS AGO...WHERE IT WAS FORECASTING 40 FOR BURKES GARDEN. WILL STILL ALLOW FOR SOME MID 40S INTO THE HIGHER MOUNTAIN VALLEYS...WHILE MOST OF THE MOUNTAINS DROP INTO THE UPPER 40S TO LOWER 50S. THERE WILL STILL BE DEWPOINT GRADIENT IN THE PIEDMONT AND THINK ROANOKE AND POINTS EAST TO HAVE OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 430 AM EDT TUESDAY... LARGE LONGWAVE UPPER TROUGH ASSOCIATED WITH GREAT LAKES LOW PRESSURE CENTER WILL CONTINUE TO SLIDE EAST THROUGH THE FORECAST PERIOD...ALLOWING COOL SURFACE HIGH PRESSURE TO BUILD JUST NORTH AND WEST OF THE AREA. PRECIPITATION CHANCES THROUGH THE PERIOD WILL REMAIN MINIMAL...AS THE COOL HIGH PRESSURE SLOWLY PUSHES EAST. PREDOMINANT WIND DIRECTION SLOWLY SHIFTS FROM NORTHWESTERLY...AROUND TO NORTHERLY ON THURSDAY BEFORE EVENTUALLY TURNING EASTERLY BY FRIDAY AFTERNOON. FRIDAY...A BIT OF UNCERTAINTY REMAINS WITH THE STRENGTH OF THE WIND FIELD AROUND THE SURFACE HIGH LATER IN THE PERIOD...ESPECIALLY WITH TIMING OF MOISTURE RETURN. FOR NOW...LIMITED ISOLATED SHOWERS/STORMS TO THE FAR EASTERN SLOPES OF THE BLUE RIDGE...WHERE BETTER PWATS AND LIFTING MAY OCCUR...WITHIN NORTHWEST NORTH CAROLINA AND FAR SOUTHERN VIRGINIA. TEMPERATURE WISE...TENDED SLIGHTLY LOWER THAN GUIDANCE...ESPECIALLY WITH THE OVERNIGHT LOWS. PREDOMINANTLY CLEAR SKIES AND LOWER DEWPOINT VALUES SHOULD ALLOW FOR A SIGNIFICANT LOSS OF DAYTIME HEATING THROUGH MOST OF THE PERIOD...WITH A SLIGHT WARMING AND MOISTENING TREND AS EASTERLY FLOW GETS ESTABLISHED FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AS OF 1245 PM EDT MONDAY... UPPER TROUGH WILL BE LIFTING OUT ACROSS THE REGION LATE IN THE WEEK RESULTING IN BRIEF ZONAL 5H FLOW BEFORE ANOTHER WEAKER SHORTWAVE TROUGH DROPS SE AROUND THE UPPER RIDGE TO THE WEST AND INTO THE AREA EARLY NEXT WEEK. THIS SHOULD ALLOW A RATHER LARGE AREA OF HIGH PRESSURE TO THE NORTH LATE IN THE WEEK TO SETTLE SOUTH AND OVERHEAD DURING THE WEEKEND BEFORE WEAKENING INTO NEXT WEEK. MOST MODELS DEPICT THIS SCENARIO IN KEEPING DEEPER MOISTURE WITH THE OLD FRONT NEAR THE COAST WITH PERHAPS THE REMNANT WAVE OF DANNY SPAWNING A WEAK LOW OFF THE SOUTHEAST COAST EARLY NEXT WEEK. HOWEVER GUIDANCE ALSO INDICATES JUST ENOUGH TROPICAL MOISTURE RETURN BY DAYS 6/7 UNDER THE WEAKENING SURFACE RIDGE AND SLIGHT COOLING ALOFT TO BRING A RETURN OF LEAST SOME DIURNAL ISOLATED/SCATTERED MAINLY MOUNTAIN CONVECTION FROM LATE SATURDAY INTO MONDAY. OTRW SHOULD BE MAINLY DRY WITH SEASONAL TEMPS EARLY IN THE PERIOD...THEN A REBOUND TOWARD HOTTER AND MORE HUMID CONDITIONS BY EARLY NEXT WEEK...WITH HIGHS 80S TO PERHAPS NEAR 90 SOUTHEAST AS RETURN FLOW DEVELOPS. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... AS OF 710 AM EDT TUESDAY... GENERALLY VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD. LATE TONIGHT...THERE COULD BE SOME FOG AT LWB...BUT THINK AIRMASS WILL STAY DRY ENOUGH THAT FOG WILL BE LIMITED...SO FOR NOW KEPT IT MVFR AFTER 09Z. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE CONTROLS OUR WEATHER THROUGH MIDWEEK KEEPING IT VFR. MAY SEE SOME LATE NIGHT/EARLY MORNING PATCHY FOG THAT DISSIPATES QUICKLY AFTER SUNRISE IN THE FAVORED TERMINALS LWB/BCB. INCREASED CHANCES FOR SHOWERS/THUNDERSTORMS BY LATE THIS WEEKEND AS MOISTURE FROM THE SOUTHEAST STATES WORKS ITS WAY NORTHWARD INTO THE AREA. && .EQUIPMENT... BLACKSBURG RADAR TO BE DOWN FOR SOFTWARE AND HARDWARE UPGRADES THIS MORNING TIL ABOUT EARLY AFTERNOON. RADAR SHOULD BE UP BY 18Z/2PM EDT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...KK/WP SHORT TERM...JM/NF LONG TERM...JH AVIATION...KK/RAB/WP EQUIPMENT...

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