Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 281734 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 134 PM EDT FRI AUG 28 2015 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST TOWARD NEW ENGLAND TODAY...SHIFTING WINDS FROM THE SOUTHEAST BY THIS EVENING. 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. HIGH PRESSURE WILL THEN STRENGTHEN IN THE WAKE OF THIS FEATURE...RESULTING IN DRIER AND WARMER WEATHER BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM EDT FRIDAY... NO SIGNIFICANT CHANGES NEEDED TO THE FORECAST AS EVERYTHING IS IN GOOD SHAPE. SATELLITE IMAGES SHOW PATCHY FOG HAS DISSIPATED BUT SOME CLOUDINESS LINGERS ALONG AND WEST OF THE BLUE RIDGE. EXPECT CU FIELD TO BLOOM ONCE AGAIN TODAY WITH DIURNAL HEATING WITH OROGRAPHIC EFFECTS HELPING TO GENERATE AN ISOLATED SHOWER OR TWO WEST OF THE RIDGE THIS AFTERNOON. LOW CHANCE POPS WILL COVER THE SITUATION FROM THE MOUNTAINS OF NC UP THROUGH THE MOUNTAIN EMPIRE OF VA AND INTO WESTERN GREENBRIER COUNTY. MORNING RNK SOUNDING SUPPORTS TEMPERATURES A BIT WARMER THAN YESTERDAY...IN LINE WITH THE CURRENT FORECAST OF LOW/MID 80S EAST WITH MID/UPPER 70S WEST. PREVIOUS AFD... AS HIGH PRESSURE SHIFTS TOWARD NEW ENGLAND...EXPECT OUR WINDS TO BECOME EASTERLY TODAY...THEN SOUTHEASTERLY DURING THE EVENING. THE MORE EASTERLY DIRECTION WILL CONTINUE TO DRAW ATLANTIC MOISTURE INTO OUR AREA...PUSHING IT UPSLOPE INTO THE MOUNTAINS. AS SUCH...WE CAN EXPECT ISOLATED TO WIDELY SCATTERED SHOWERS TO DEVELOP DURING THE AFTERNOON ACROSS THE RIDGES. OTHERWISE...EXPECT PARTLY CLOUDY SKIES...PERHAPS BECOMING MOSTLY CLOUDY AT TIMES ACROSS THE MOUNTAINS. SLIGHTLY WARMER TODAY AS WELL THANKS TO THE INCREASED INFLUENCE FROM THE SUBTROPICAL RIDGE. AFTERNOON HIGH TEMPERATURES WILL RANGE FROM THE MID/UPPER 70S ACROSS THE MOUNTAINS TO THE LOW/MID 80S ACROSS THE PIEDMONT. SOUTHEASTERLY WINDFLOW WILL REMAIN FOR TONIGHT...PUSHING MARINE MOISTURE INTO THE MOUNTAINS. AS SUCH...EXPECT PARTLY TO MOSTLY CLOUDY SKIES TO REDEVELOP ACROSS THE MOUNTAINS AND FOOTHILLS... POSSIBLY WITH AN ISOLATED BRIEF SHOWER. OVERNIGHT TEMPERATURES WILL FALL INTO THE MID 50S TO LOW 60S. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 400 AM EDT FRIDAY... FORECAST BECOMES INCREASINGLY UNCERTAIN DURING THIS PERIOD...FOCUSED PRIMARILY AROUND THE TRACK AND INTENSITY OF TROPICAL STORM ERIKA LATE IN THE PERIOD. SEVERAL WEAK FEATURES DRIVING THE SYNOPTIC CONDITIONS AT THE BEGINNING OF THE PERIOD. A BROAD...REMNANT UPPER TROUGH LINGERS ACROSS THE EASTERN U.S...WHILE A NEW UPPER TROUGH DRIFTS INTO THE OHIO VALLEY. BOTH SYSTEMS UNDERLIE A BROAD UPPER RIDGE PRESENT AND BUILDING ACROSS MUCH OF THE REGION...BOTH FROM THE WESTERN ATLANTIC AND THE CENTRAL U.S. MEANWHILE...A TROUGH/EARLIER WEEK FRONTAL PASSAGE...LINGERS ALONG THE NC/SC COAST INTO THE SOUTHEAST STATES. WEAK REMNANTS OF FORMER HURRICANE DANNY EVIDENT ACROSS THE EASTERN GULF COASTAL REGION. THE TROUGH TO THE WEST WILL SLOWLY APPROACH THE REGION...BUT WILL WEAKEN AND LIFT NORTH AS IT APPROACHES THE ALLEGHANYS SUN...WITH ONLY A WEAK REMNANT TROUGH LINGERING ACROSS THE NORTHERN PORTIONS OF THE AREA BY MON. MEANWHILE...SOUTHERLY FLOW BETWEEN THE WESTERN ATLANTIC RIDGE AND THE BROAD UPPER LOW PERSISTING ACROSS THE MID-SOUTH...WILL ALLOW GULF/TROPICAL MOISTURE TO GRADUALLY BE DRAWN NORTHWARD INTO THE REGION THROUGH THE WEEKEND. WITH EASTERLY FLOW AND MOISTURE POOLED/UPLIFTED ACROSS THE MOUNTAINS IN THE SOUTHWEST PART OF THE CWA...WE SHOULD START TO SEE SLIGHTLY BETTER COVERAGE EACH DAY OF SHOWERS AND THUNDERSTORMS IN THAT REGION. EASTERN AREAS WILL SEE GREATER SUBSIDENCE AND DRIER/MORE STABLE NORTHEAST FLOW...CONSEQUENTLY LITTLE TO NO PRECIPITATION EXPECTED. ALL OF THIS IS BEST REPRESENTED BY SLIGHT CHANCE POPS WESTERN MOUNTAINS SATURDAY...INCREASING TO CHANCE POPS AND CREEPING SLIGHTLY EASTWARD TOWARD THE BLUE RIDGE BY MONDAY. 850MB TEMPS WILL BE ON THE INCREASE THROUGH THE PERIOD AS BROAD UPPER RIDGING DEVELOPS ACROSS MUCH OF THE EASTERN 2/3RD OF THE U.S. 850MB TEMPS RISE FROM THEIR CURRENT LEVELS IN THE +10C TO +15C RANGE...CLOSER TO +20C BY EARLY NEXT WEEK. WITH DEWPOINTS ALSO ON THE INCREASE...MIN TEMPS WILL RANGE FROM MID TO UPPER 50S MOUNTAINS TO MID 60S EAST...WITH HIGHS 70S MOUNTAINS TO MID AND UPPER 80S PIEDMONT. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 415 AM EDT FRIDAY... THE FORECAST BEYOND MONDAY IS LARGELY DEPENDENT ON THE TRACK AND INTENSITY OF ERIKA. CURRENT MODEL TRENDS ARE ALL OVER THE PLACE WITH THE CANADIAN SHOWING A MAJOR HURRICANE TRACKING NORTHWEST INTO OUR CWA WITH ASSOCIATED WIND/RAIN...WHILE THE GFS/ECMWF HAVE LITTLE MORE THAN A TROPICAL LOW...POTENTIALLY SHEARED INTO TWO PARTS...ONE WHICH REMAINS OFF THE ATLANTIC COAST AND THE OTHER TRACKING WESTWARD...EITHER INTO THE MID-SOUTH OR POSSIBLY INTO THE TN VALLEY. WITH THE CONSIDERABLE DEGREE OF UNCERTAINTY IN PLACE...SIMPLY CANNOT INCLUDE ANY EFFECTS IN THE GRIDS AT THIS POINT. LATEST NHC TRENDS ARE FOR A WEAKER SYSTEM AND MUCH WILL DEPEND ON ITS INITIAL INTERACTION WITH THE CARIBBEAN ISLANDS BEFORE IT EVEN REACHES THE U.S. MAINLAND. HAVE MADE ONLY MINOR ADJUSTMENTS TO POPS BEYOND DAY 5...WHICH GENERALLY ADVERTISED JUST SLIGHT CHANCE/CHANCE POPS...HIGHLY DIURNAL IN NATURE...ALL SUBJECT TO CHANGE BASED ON THE EVENTUAL TRACK AND FATE OF ERIKA. TEMPS BASICALLY A PERSISTENCE FORECAST THROUGH THE PERIOD UNDER WEAK SURFACE HIGH PRESSURE AND BROAD RIDGING ALOFT...THUS LITTLE CHANGE IN THE AIRMASS EXCEPT FOR SLOWLY INCREASING MOISTURE. OVERALL...MIN AND MAX TEMPS SHOULD BE SLIGHTLY ABOVE NORMAL WITH 850MB TEMPS HOVERING NEAR +20C THROUGH THE PERIOD. EXPECT LOWS MOSTLY IN THE 60S...A FEW 50S MOUNTAINS...WITH HIGHS 70S MOUNTAINS TO MID AND UPPER 80S PIEDMONT. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 130 PM EDT FRIDAY... LITTLE CHANGE IN THE SYNOPTIC PATTERN THROUGH THE TAF PERIOD WILL LEAD TO A PERSISTENCE FORECAST. EXPECT DIURNALLY FORCED BKN/V/SCT VFR CEILINGS AT ALL LOCATIONS THROUGH THIS AFTERNOON. ANY SHOWER DEVELOPMENT WILL BE OROGRAPHICALLY DRIVEN WEST OF THE BLUE RIDGE AND ISOLATED IN COVERAGE SO WILL NOT INCLUDE ANY MENTION IN TAFS. INDICATIONS ARE THAT CLOUDS WILL NOT STAY LOCKED IN AFTER SUNSET AS LAST NIGHT...BUT WILL LINGER CIGS FROM THE BLUE RIDGE WEST UNTIL THE 04Z/08Z TIME FRAME. THE LINGERING CLOUDS WILL KEEP FOG DEVELOPMENT IN CHECK...THOUGH DISSIPATION/BREAKS IN THE CLOUDS WILL ALLOW FOR DEVELOPMENT LATE. WILL KEEP THINGS TEMPO MVFR AT KBCB AND LIMIT KLWB TO MEDIUM IFR. EXPECT PATCHY FOG EAST OF THE RIDGE AND KDAN SHOWED SOME FOG DEVELOPMENT LAST NIGHT SO WILL GO WITH A TEMPO MVFR GROUP TOWARD DAYBREAK THERE AS WELL. ANY FOG/STRATUS WILL BURN OFF AFTER DAYBREAK TOMORROW AND EXPECT SCT/V/BKN VFR CLOUDS TO DEVELOP ONCE AGAIN LATE IN THE VALID PERIOD. EXTENDED AVIATION DISCUSSION... AS OF 130 PM EDT FRIDAY... EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY INCREASES...WHICH WILL INCREASE 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.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF NEAR TERM...MBS/NF SHORT TERM...RAB LONG TERM...JH/RAB AVIATION...MBS/NF

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