Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 302343 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 743 PM EDT THU JUL 30 2015 .SYNOPSIS... A COLD FRONT WILL SLIDE EAST ACROSS OUR REGION TONIGHT...STALLING ALONG THE SOUTHEAST COAST FRIDAY INTO SATURDAY. THIS WILL ALLOW FOR HIGH PRESSURE TO KEEP MOST OF THE AREA DRY THROUGH THE WEEKEND...AS IT MOVES IN FROM THE WEST. && .NEAR TERM /THROUGH FRIDAY/... AS OF 310 PM EDT THURSDAY... SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN THE UNSTABLE AIR AHEAD AND ALONG THE COLD FRONT THIS AFTERNOON. THE STORM PREDICTION CENTER IN THEIR DAY 1 CONVECTIVE OUTLOOK HAS REMOVED THE MARGINAL RISK AREAS FROM OUR COUNTY WARNING AREA...LEAVING US IN THE GENERAL THUNDERSTORM AREA. THE COLD FRONT ALONG THE MOUNTAINS THIS AFTERNOON WILL MOVE EAST THIS EVENING INTO TONIGHT. LOOKING AT THE LATEST SPC MESOSCALE ANALYSIS...THE RICHEST CAPES AROUND 2K J/KG AND SFC BASED LIS AROUND MINUS 5 WHERE EAST OF THE BLUE RIDGE MOUNTAINS. HOWEVER...THE BEST DYNAMICS AND MOISTURE CONVERGENCE WILL REMAIN NORTH OF OUR AREA. LEANED POPS THIS AFTERNOON INTO TONIGHT TOWARDS THE LATEST HRRR WITH JUST A SLIGHTLY SLOWER TIMING AND KEPT THE HIGHEST CHANCES IN THE EAST. DRIER AIR OVERSPREADING OUR WESTERN CWA TONIGHT...WHILE THE FRONT SLOWS DOWN IN THE EAST AND KEEPS THE HIGHER DEWPOINTS LINGERING LONGER. SHOWERS AND THUNDERSTORMS SHOULD MOVE OUT OF THE PIEDMONT BY MIDNIGHT...WITH SKIES CLEARING. LIGHT WINDS AND LOW LEVEL MOISTURE MAY RESULTS IN SOME PATCHY VALLEY FOG OVERNIGHT INTO FRIDAY MORNING. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE LOWER TO MID 50S IN THE DEEPER VALLEYS OVER SOUTHEAST WEST VIRGINIA AND FAR SOUTHWEST VIRGINIA TO THE LOWER TO MID 60S IN THE PIEDMONT. HIGH PRESSURE BUILDS EASTWARD FROM THE CENTRAL PLAINS FRIDAY. THE HIGH CENTER WILL BRING WITH IT DRIER AIR...PUSHING DEWPOINTS INTO THE 50S AND LOWER 60S. THE LOWER RELATIVE HUMIDITIES WILL BE A WELCOME CHANGE FOR MANY. HIGH TEMPERATURES FRIDAY AFTERNOON WILL BE IN THE MID 70S IN THE NORTHWEST MOUNTAINS TO AROUND 90 DEGREES IN THE PIEDMONT. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 215 PM EDT THURSDAY... A QUIET AND RATHER COMFORTABLE PERIOD LOOKS IN STORE UNDER BROAD UPPER TROFFINESS ENHANCED VIA SURFACE HIGH PRESSURE BUILDING OVERHEAD THROUGH THE WEEKEND. THIS SHOULD RESULT IN MAINLY SUNNY WARM DAYS AND CLEAR/PLEASANT NIGHTS GIVEN DRIER DEWPOINTS AND SUBSEQUENT LOWER HUMIDITY THROUGH AT LEAST SUNDAY. ONLY EXCEPTIONS COULD BE WITH MORE CLOUDS AND POSSIBLY A FEW LIGHT SHOWERS NW UNDER SLIGHTLY BETTER UPSLOPE LATE SATURDAY...AND THEN PERHAPS OVER THE WESTERN HALF SUNDAY EVENING WITH A PASSING MID LEVEL SHORTWAVE. HOWEVER GIVEN PROGGED DRYNESS AND LIKELY ISOLATED NATURE TO ANY SHOWERS OPTING TO LEAVE OUT ANY POPS OR SHOWER MENTION FOR NOW. TEMPS LOOK TO REMAIN QUITE PERSISTENT THROUGH THE PERIOD WITH WEAK DOWNSLOPE/HEATING OF DRY AIR ALLOWING HIGHS TO REMAIN IN THE 85-90 RANGE EAST...AND MOSTLY LOW/MID 80S MOUNTAINS DESPITE THE COOLER/DRIER AIRMASS. BETTER IMPACT OF THE DRY AIR TO BE FELT DURING THE OVERNIGHTS WITH LOWS IN THE 50S VALLEYS AND LOW/MID 60S ELSEWHERE. COOLEST NIGHT AT THIS POINT LOOKS TO BE EARLY SUNDAY WITH THE PASSING OF THE 85H TROUGH...AND HIGH PRESSURE ABOUT OVERHEAD POSSIBLY ALLOWING A FEW 40S IN THE DEEPEST NW VALLEYS PENDING ANY RIVER FOG LATE. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 1230 PM EDT THURSDAY... MEAN 5H TROUGH TO REMAIN ACROSS THE MID ATLANTIC REGION THROUGH MUCH OF NEXT WEEK WITH STEADY NW FLOW ALOFT BETWEEN UPPER LEVEL LOW PRESSURE WELL TO THE NORTH AND STRONG RIDGING OVER THE SW STATES. THIS SHOULD ALLOW FOR AN OVERALL PERSISTENCE TYPE FORECAST THROUGH THE EXTENDED WITH TOLERANT HUMIDITY LEVELS ALONG WITH LOWS MOSTLY IN THE 60S AND HIGHS 80S TO LOWER 90S. COVERAGE OF SHOWERS AND STORMS ALSO LIKELY LIMITED PENDING PROGRESSION OF THE NEXT POSSIBLE COOL SURGE LATE IN THE PERIOD. HOWEVER WILL ALSO HAVE TO WATCH LINGERING MOISTURE WITH THE RESIDUAL FRONT NEAR THE COAST WHICH COULD BE LIFTED BACK NORTH BY APPROACH OF WEAK IMPULSES ALOFT ESPECIALLY EARLY NEXT WEEK. THIS ALONG WITH HEATING MAY BE ENOUGH TO SPARK ISOLATED CONVECTION MAINLY SOUTH MONDAY...AND ALONG A PASSING SHORTWAVE TROUGH AXIS CROSSING FROM THE NW TUESDAY...BUT LOW POPS AT BEST BOTH DAYS. UPPER TROUGH JUST NORTH OF THE LAKES WILL DEEPEN AGAIN BY MIDWEEK AS MORE SHORTWAVE ENERGY ROTATES THROUGH AND SLIDES AN ASSOCIATED COLD FRONT SOUTH TOWARD/INTO THE REGION. HOWEVER MODELS DISAGREE ON THE AMPLITUDE OF THE DIGGING TROUGH WITH THE GFS MOST AGGRESSIVE WHILE OTHER SOLUTIONS SLOWER/WEAKER WHILE MAINTAINING MORE CONVECTION ALONG THE BOUNDARY. FOR NOW WILL GO WITH A WEAKER/SLOWER SCENARIO BUT LEAN TOWARD THE GFS IN DRIVING THE COOL ADVECTION IN BY THE END OF THE PERIOD SINCE IT HAS BEEN BEST OF LATE. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 740 PM EDT THURSDAY... A COLD FRONT WILL CONTINUE TO MOVE EAST ACROSS THE REGION THIS EVENING. ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG THE FRONT. RADAR SHOWED A STORM UPSTREAM OF KDAN AND AT CURRENT SPEED AND DIRECTION...THIS FEATURE WILL REACH THE AIRPORT AROUND 01Z. NO CHANCE OF SHOWERS AND THUNDERSTORMS FOR THE OTHER LOCAL TAF SITES...WHICH WERE BEHIND THE FRONT. WITH DRIER AIR WORKING IN TONIGHT AND SURFACE DEW POINTS LOWERING INTO THE LOWER 50S TO LOWER 60S...THE FOG THREAT SHOULD BE MINIMIZED...THOUGH THERE IS A SMALL CHANCE THAT LWB/BCB COULD FOG IN GIVEN SOME SLIGHTLY COOLER AIR OVER THE NEW AND GREENBRIER RIVERS. VFR CONDITIONS EXPECTED FRIDAY. HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE PERIOD. EXTENDED AVIATION FORECAST... UNDER HIGH PRESSURE...DRY AND VFR FRIDAY NIGHT THROUGH SUNDAY. THE NEXT CHANCE OF MVFR CONDITIONS WILL BE ON MONDAY AND TUESDAY AS MOISTURE AND A LOW PROBABILITY OF SHOWERS AND THUNDERSTORMS RETURN TO THE REGION. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/WP NEAR TERM...KK SHORT TERM...JH LONG TERM...JH AVIATION...AMS/KK

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