Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290559 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 159 AM EDT SAT AUG 29 2015 .SYNOPSIS... HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL SLIDE SOUTH AND REMAIN ABOUT OVERHEAD INTO SATURDAY. A WEAK UPPER LEVEL DISTURBANCE WILL LIFT NORTH ALONG THE APPALACHIANS SUNDAY INTO MONDAY AHEAD OF A WEAK COLD FRONT TO THE WEST. UPPER LEVEL HIGH PRESSURE WILL STRENGTHEN IN THE WAKE OF THIS FEATURE...RESULTING IN MORE DIURNAL NATURE SHOWERS AND STORMS INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 1137 PM EDT FRIDAY... OUTER RING OF HIGH CLOUDS FROM WHAT WAS LEFT OF DANNY STREAMING ACROSS THE SRN CWA WITH MID CLOUDS ACROSS THE MOUNTAINS AND NORTHERN SECTIONS OF THE VIRGINIA PIEDMONT ALONG/NORTH FROM LYH TO ROA. FORECAST OVERNIGHT FAVORS A MIX OF CLOUDS AND STARS...WITH SOME VALLEY FOG FORMING. OVERNIGHT LOWS WILL BE WARMER THAN PREVIOUS NIGHTS AS DEWPOINTS ARE IN THE UPPER 50S TO LOWER 60S. ADJUSTED SOME TEMPS UP. LOWS BE IN THE MID TO UPPER 50S...WITH SOME URBAN AREAS IN THE LOWER 60S. PREVIOUS VALID DISCUSSION... THE MAIN WEATHER FEATURE DRIVING OUR WEATHER INTO THE FIRST PART OF THE WEEKEND WILL CONTINUE TO BE AN AREA OF HIGH PRESSURE LINGERING OVER THE EASTERN SEABOARD WITH ANY SIGNIFICANT SYNOPTIC SHORT WAVE ENERGY SLIDING BY WELL TO OUR NORTH. SATURDAY WILL HAVE A SIMILAR FLAVOR WITH ISOLATED SHOWERS POSSIBLE WEST OF THE RIDGE. HIGHS SATURDAY WILL BE IN THE MIDDLE 80S EAST TO UPPER 70S/AROUND 80 WEST. && .SHORT TERM /TONIGHT THROUGH MONDAY/... AS OF 230 PM EDT FRIDAY... RIDGING BOTH SURFACE AND ALOFT WILL LINGER INTO SATURDAY NIGHT BEFORE GIVING WAY TO AN UPSTREAM UPPER TROUGH AND ASSOCIATED WEAK FRONTAL BOUNDARY SUNDAY INTO MONDAY. THIS SHOULD ALLOW FOR A PLUME OF DEEPER MOISTURE ACROSS THE SOUTHEAST TO BE PULLED NORTHWARD ALONG THE APPALACHIANS WITH EMBEDDED SHORTWAVE ENERGY AIDING LIFT ALONG WITH HEATING. MODELS CONTINUE TO SHOW THE BEST FOCUS IN AN ARC ACROSS THE MOUNTAINS WITH BETTER INSTABILITY...DIFFLUENCE AND THETA-E RIGHT ALONG THE WESTERN SLOPES ESPECIALLY LATER SUNDAY INTO EARLY MONDAY. HOWEVER THIS AGAIN WITHIN AN AREA OF LOW LEVEL SUBSIDENCE ENHANCED VIA WEAK SURFACE RIDGING ACROSS THE MOUNTAINS SO EXPECTING MORE SCATTERED NATURE COVERAGE AT THIS POINT. THUS HOLDING OFF ON GOING MUCH MORE THAN MID CHANCE POPS...MAINLY BLUE RIDGE WEST FROM SUNDAY AFTERNOON INTO LATE MONDAY...WITH HIGHEST ACROSS THE FAR WESTERN COUNTIES WHERE FORECAST SOUNDINGS SHOW QUITE A MOIST/WEAKLY VEERED PROFILE BY MONDAY AFTERNOON. WITH LOW LEVEL MOISTURE A BIT LESS EAST OF THE MOUNTAINS...APPEARS SHOWERS MORE ISOLATED SO ONLY KEEPING A 20ISH POP OUT EAST FOR NOW. WARMING 85H TEMPS SUPPORT RATHER WARM TEMPS EAST OF THE MOUNTAINS BOTH SUNDAY AND MONDAY WHEN TEMPS MAY GET CLOSE TO 90 PIEDMONT PENDING DEGREE OF CLOUDS. OTHERWISE BECOMING MORE MUGGY GIVEN INCREASING DEWPOINTS...AND HIGHS MOSTLY IN THE 80S WITH SOME 70S POSSIBLE FAR WEST ESPECIALLY IF SHOWERS ARE MORE WIDESPREAD SUNDAY/MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 1240 PM EDT FRIDAY... OVERALL PERSISTENCE FORECAST AT LEAST EARLY ON AS UPPER RIDGING STRENGTHENS ACROSS THE REGION IN THE WAKE OF THE PASSING WAVE ALOFT AND IN INCREASING SUBSIDENCE WELL NORTH OF ERIKA. THIS SHOULD RESULT IN A MORE DIURNALLY DRIVEN TREND OF DAILY SHOWERS AND ISOLATED STORMS EACH AFTERNOON/EVENING WITH A GRADUAL INCREASE IN COVERAGE/EXPANSE FROM TUESDAY THROUGH THURSDAY GIVEN BETTER PWATS/MOISTURE AND SLIGHT COOLING ALOFT. HOWEVER THINK LOW/MEDIUM CHANCE POPS CONFINED MAINLY ALONG/WEST OF THE BLUE RIDGE PER OROGRAPHICS...AND MORE ISOLATED ELSEWHERE ESPECIALLY GIVEN MOISTURE OVER TOP A LINGERING SURFACE RIDGE. THUS FOLLOWED CLOSER TO TRENDS FROM WPC WITH A GRADUAL BOOST IN POPS EACH DAY BUT LITTLE DURING THE OVERNIGHTS INTO THURSDAY. THINGS BECOME MORE UNCERTAIN BY DAY7 WITH MODELS LOWERING HEIGHTS ACROSS THE APPALACHIANS AND FROM THE NE WITH A POSSIBLE ASSOCIATED BACKDOOR COOL FRONT. THIS COULD HELP FOCUS MOISTURE GIVEN A BETTER EASTERLY TRAJECTORY TO THE NORTH OF ERIKA OR ITS REMNANTS ON FRIDAY. THEREFORE GOING WITH MORE WIDESPREAD CHANCE POPS PER POTENTIAL TROPICAL TYPE PWATS OVER THE AREA DURING HEATING FRIDAY AFTERNOON. OTHERWISE LITTLE CHANGE IN DAILY TEMPS GIVEN SUCH A HUMID/WARM AIRMASS...SUPPORTING HIGHS MOSTLY IN THE 80S AND LOWS IN THE 60S EXCEPT PERHAPS A BIT COOLER FRIDAY PENDING CLOUDS/SHOWERS. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 155 AM EDT SATURDAY... HIGH PRESSURE IS CENTERED OVER THE DELMARVA THIS MORNING...MAKING FOR VERY LIGHT SOUTH SOUTHEASTERLY WINDFLOW ACROSS THE AREA. LOW LEVEL MOISTURE IS GRADUALLY INCREASING AS THIS WINDFLOW DRAWS ATLANTIC AIR UPSLOPE INTO THE MOUNTAINS. AS SUCH...SURFACE OBSERVATIONS ACROSS THE MOUNTAINS AND FOOTHILLS HAVE DETECTED SCATTERED CEILINGS IN THE 4KFT TO 6KFT RANGE...WHICH ARE EXPECTED TO PERSIST THROUGH THE NIGHT. MAY ALSO SEE THE VISIBILITY BOUNCE UP AND DOWN IN SPOTS...DEPENDING ON CLOUD COVER...AS PATCHY GROUND FOG DEVELOPS ACROSS LOCATIONS WHERE THE SKIES CLEAR. ANY FOG WILL BURN OFF QUICKLY AFTER 29/14Z WITH DAYTIME HEATING... RESULTING IN VFR CONDITIONS AREAWIDE. INCREASING MOISTURE WILL MAKE FOR A SCT CU FIELD DEVELOPING LATE MORNING...POSSIBLY BECOMING BKN ACROSS THE MOUNTAINS DURING LATE AFTERNOON...WITH CEILING BASES 4KFT TO 6KFT. INSTABILITY IS LIMITED...BUT MAY BE SUFFICIENT TO TRIGGER ISOLATED SHOWERS ACROSS SOUTHEAST WEST VIRGINIA...POSSIBLY AS FAR EAST AS KBCB. EVEN THEN...SHOWER THREAT IS NOT EXPECTED TO RESULT IN SUB VFR CONDITIONS WHERE THEY OCCUR FOR MORE THAN A FEW MINUTES. CONVECTION WILL WANE TOWARD SUNSET. EXTENDED AVIATION DISCUSSION... AS OF 130 PM EDT FRIDAY... EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY INCREASES...WHICH WILL RAISE OUR CHANCES FOR DIURNAL SHOWERS AND STORMS AS WE HEAD INTO THE FIRST PART OF NEXT WEEK. SHORT WAVE ENERGY MOVING UP FROM THE SOUTH WILL GIVE THE BEST CHANCES FOR MORE WIDESPREAD CONVECTIVE ACTIVITY IN THE SUNDAY/MONDAY TIME FRAME. GENERALLY EXPECT THE BEST CHANCES FOR MVFR/IFR TO BE LATE NIGHT/EARLY MORNING DUE TO FOG AND STRATUS DEVELOPMENT FROM THE BLUE RIDGE WEST ESPECIALLY AT KLWB/KBCB. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...MBS/WP SHORT TERM...JH LONG TERM...JH AVIATION...NF/WP

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