Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280611 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 211 AM EDT FRI AUG 28 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST TONIGHT AND REMAIN ENTRENCHED ACROSS THE AREA INTO SATURDAY. A WEAK UPPER LEVEL DISTURBANCE WILL SLIDE NORTH ALONG THE APPALACHIANS SUNDAY INTO MONDAY BRINGING BETTER CHANCES OF SHOWERS AND STORMS...MAINLY TO THE MOUNTAINS INTO EARLY NEXT WEEK. HIGH PRESSURE STRENGTHENS IN THE WAKE OF THIS FEATURE RESULTING IN DRIER AND WARMER WEATHER BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 1000 PM EDT THURSDAY... CLOUD COVER PERSISTS ALONG THE EASTERN...UPSLOPE AREAS OF THE MOUNTAINS FROM NORTHWEST NC TO SOUTHEAST WV. ALL INDICATIONS ARE THAT THIS WILL CONTINUE WITH AN INTENSIFYING MARINE INVERSION AROUND 700MB SUPPORTED BY EASTERLY LOW-LEVEL FLOW. WITH NO CHANGE IN THE SYNOPTIC SITUATION...THIS PATTERN SHOULD PERSIST. THIS COMBINED WITH SLOWLY INCREASING DEWPOINTS SHOULD HOLD MIN TEMPS UP A FEW DEGREES TONIGHT IN THE WEST. LESS CLOUDS IN THE EAST SHOULD GENERALLY SUPPORT ADVERTISED MIN TEMPS. OTHER THAN THESE CHANGES TO THE TEMP/MIN T/SKY GRIDS...SO OTHER CHANGES WERE NEEDED AT THIS TIME. AS OF 300 PM EDT THURSDAY... WITH NO MAJOR SYNOPTIC CHANGES WE WILL CONTINUE TO SEE RELATIVELY QUIET WEATHER THROUGH THE END OF THE WORKWEEK. 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. VISIBLE SATELLITE IMAGES SHOW A FAIRLY EXTENSIVE CU FIELD ACROSS THE REGION BUT AS OF EARLY THIS AFTERNOON RADAR DOES NOT INDICATE ANY SHOWERS. HOWEVER...BELIEVE THERE WILL BE ENOUGH OROGRAPHIC FORCING ALONG AND WEST OF THE BLUE RIDGE TO GENERATE AN ISOLATED SHOWER OR TWO. WILL CONTINUE WITH SLIGHT CHANCE POPS ACROSS THE FAR WEST WITH ANY SHOWERS DISSIPATING AFTER SUNSET. OVERNIGHT SHOULD SEE SOME FOG FORMATION AGAIN MAINLY IN THE VALLEYS WEST OF THE RIDGE. FRIDAY LOOKS TO FEATURE VERY SIMILAR CONDITIONS TO WHAT WE HAVE TODAY WITH ANOTHER SLIGHT CHANCE FOR AN AFTERNOON SHOWER WEST OF THE RIDGE. TEMPERATURES TONIGHT AND FRIDAY WILL BE AT OR SLIGHTLY BELOW NORMAL WITH LOWS AROUND 60S ACROSS THE PIEDMONT TO THE LOW/MID 50S WEST OF THE RIDGE...AND HIGHS IN THE MIDDLE 80S EAST TO GENERALLY MIDDLE 70S WEST. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... AS OF 245 PM EDT THURSDAY... RIDGING BOTH SURFACE AND ALOFT WILL REMAIN DOMINANT TO START THE WEEKEND WITH DEEPER MOISTURE AND INSTABILITY STAYING TO THE SOUTH/WEST OF THE REGION INTO SATURDAY EVENING. THIS SEEN IN THE LATEST MODELS INCLUDING FORECAST SOUNDINGS THAT SHOW A MUCH DRIER COLUMN ALOFT THAN SEEN FROM YESTERDAY. THEREFORE KEPT POPS OUT FRIDAY NIGHT AND CUT BACK TO MORE ISOLATED MOUNTAIN COVERAGE SATURDAY INTO SATURDAY EVENING WITH SLIGHT CHANCES WEST. UPPER TROUGH SLIDING IN FROM THE NW BY SUNDAY WILL CAUSE HEIGHTS TO LOWER WHILE IN TURN SCOOPING UP A WEAK SHORTWAVE FROM THE SOUTH ALONG AN AXIS OF HIGHER PWATS. THIS WAVE ALONG WITH SOME UPPER DIFFLUENCE TO THEN SLIDE NORTH ACROSS THE MOUNTAINS SUNDAY WITH GUIDANCE SHOWING A DECENT AMOUNT OF WEAK LIFT DESPITE SURFACE HIGH PRESSURE IN PLACE. AGAIN THINK ENOUGH TO BRING A PERIOD OF SHOWERS IN FROM THE SOUTH LATE SATURDAY NIGHT AND PERHAPS A CLUSTER OF SHOWERS AND STORMS ESPECIALLY WESTERN HALF SUNDAY. COULD EVENTUALLY GO TO LOW LIKELY POPS SUNDAY AFTERNOON BUT GIVEN TREND OF MOISTURE/UVV SLIDING FARTHER WEST WILL HOLD WITH HIGHER CHANCE POPS...EXCEPT MAINLY SLIGHT POPS PIEDMONT. LITTLE CHANGE TO GOING TEMPS EXCEPT TO GO A BIT COOLER WEST UNDER MORE CLOUDS/SHOWERS SUNDAY...OTHERWISE CLEAR/PC WITH HIGHS LOW/MID 80S AND LOWS 58-65. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 1230 PM EDT THURSDAY... WEAKNESS ALOFT SPLITTING THROUGH THE UPPER EASTERN RIDGE WILL BE ALONG THE APPALACHIANS SUNDAY NIGHT PRIOR TO PINCHING OFF ALLOWING A WEAK UPPER LOW TO SHIFT TO THE SW BEFORE HEIGHTS REBUILD EARLY NEXT WEEK NORTH OF ERIKA. THIS COMBINED WITH A PIECE OF WEAK SHORTWAVE ENERGY SLIDING UP FROM THE SOUTH...AND HIGHER PWATS SUPPORTS BETTER CHANCES OF CONVECTION SUNDAY EVENING/OVERNIGHT AND AGAIN MONDAY ESPECIALLY ALONG THE MOUNTAIN CHAIN. HOWEVER GIVEN WEAK SURFACE RIDGING IN PLACE...WONT GO MUCH HIGHER THAN MEDIUM CHANCES WEST INTO MONDAY AND KEEP MOSTLY ISOLATED FAR EAST. PASSING OF THIS FEATURE SHOULD ALLOW RIDGING ALOFT TO BUILD BACK INTO THE REGION FROM THE EAST...AND ENHANCED BY LIKELY SUBSIDENCE TO THE NORTH OF ERIKA OFF THE FLORIDA/SE COAST TUESDAY INTO WEDNESDAY. THUS EXPECTING A GRADUAL DECREASE IN POPS STARTING TUESDAY WITH PERHAPS ONLY ISOLATED MOUNTAIN COVERAGE AT BEST BY WEDNESDAY INTO THURSDAY. HOWEVER PENDING TRACK OF ERIKA COULD SEE ENOUGH MOISTURE PUSHED INTO THE PIEDMONT WITHIN THE EASTERLY FETCH AHEAD OF THE SYSTEM TO SPARK A FEW SHOWERS SOUTHEAST ON DAY7 SO KEPT MAINLY ISOLATED POPS IN SPOTS. OTHERWISE MORE CLOUDS SUNDAY NIGHT INTO MONDAY...THEN PC TO MOSTLY SUNNY AND MOSTLY CLEAR AT NIGHT INTO MIDWEEK FOR NOW. TEMPS BASICALLY A PERSISTENCE FORECAST THROUGH THE PERIOD UNDER WEAK SURFACE HIGH PRESSURE AND LITTLE CHANGE IN THE AIRMASS EXCEPT FOR INCREASING MOISTURE. THUS RUNNING WITH MAINLY LOW 80S WEST TO MID/UPPER 80S EAST...WITH OVERALL LOWS IN THE LOW/MID 60S...CLOSER TO THE WARMER EC MOS THROUGH THE PERIOD. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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AS OF 200 AM EDT FRIDAY... HIGH PRESSURE IS PASSING EAST ACROSS THE LOWER GREAT LAKES THIS MORNING...SHIFTING WINDS ACROSS THE MID ATLANTIC INCREASINGLY FROM THE NORTHEAST. CURRENTLY OBSERVING SCT TO BKN CLOUDS FROM THE BLUE RIDGE WESTWARD...MAINLY VFR WITH BASES IN THE 4KFT TO 6KFT RANGE. EXPECT CEILINGS TO DROP IN SPOTS ACROSS THE MOUNTAINS TOWARD DAWN...RESULTING IN SPOTTY MVFR BASES IN THE 2KFT TO 3KFT RANGE. WILL ALSO SEE RIVER VALLEY FOG DEVELOP IN SPOTS THAT REMAIN CLOUD- FREE FOR EXTENDED PERIODS OF TIME. FOG WILL DISSIPATE AND CEILINGS LIFT AFTER 28/14Z AS DAYTIME HEATING INCREASES. WINDS WILL SHIFT INCREASINGLY EASTERLY THROUGH LATE MORNING...BECOMING SOUTHEASTERLY DURING EARLY EVENING...WITH SPEEDS IN THE 5KT TO 10KT RANGE. WITH WIND DIRECTION BECOMING UPSLOPE...EXPECT A FEW SHOWERS TO DEVELOP ACROSS THE RIDGES WITH MAXIMUM AFTERNOON HEATING...HOWEVER LACK OF DEEP MOISTURE IN THE AREA WILL KEEP COVERAGE LIMITED. OTHERWISE...EXPECT SCT CU ACROSS THE PIEDMONT...AND SCT TO BKN CU ACROSS THE MOUNTAINS...AGAIN WITH BASES IN THE 4KFT TO 6KFT RANGE. EXTENDED AVIATION DISCUSSION... AS OF 200 AM EDT FRIDAY... 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.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...MBS/RAB SHORT TERM...JH LONG TERM...JH AVIATION...DS/NF

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