Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 211455 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1055 AM EDT TUE OCT 21 2014 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE AREA TODAY. FLOW BEHIND THE FRONT WILL REMAIN GUSTY FROM THE NORTHWEST THROUGH THURSDAY BETWEEN THE DEPARTING PARENT LOW PRESSURE SYSTEM...AND A BUILDING RIDGE ACROSS THE CENTRAL UNITED STATES. THIS RIDGE OF HIGH PRESSURE WILL GRADUALLY BUILD IN OUR DIRECTION...PROVIDING FOR MODERATING TEMPERATURES AND DRY CONDITIONS HEADING INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM EDT TUESDAY... VISIBLE SATELLITE PICS SHOWING TYPICAL PATTERN OF CLEAR EAST TO CLOUDY WEST AND SOME VERY LIGHT SHOWERS STARTING TO REFORM AS UPSLOPE FLOW COMBINES WITH ENERGY ROTATING AROUND UPPER TROF CENTERED OVER THE GREAT LAKES. EXPECT THIS OVERALL FLAVOR TO CONTINUE WITH SHOWERS ON THE INCREASE WITH AN EXPECTED DIURNAL TREND. HAVE FRESHENED THE GRIDS WITH CURRENT DATA BUT NO MAJOR CHANGES NEEDED. .PREVIOUS AFD... UPPER LEVEL TROUGH AND SURFACE COLD FRONT WILL MOVE EAST TODAY INTO TONIGHT. ANTICIPATE A RESURGENCE OF UPSLOPE SHOWERS IN THE WEST...WITH A BIT MORE COVERAGE EAST OF THE BLUE RIDGE BY MIDDAY. A REINFORCING PIECE OF ENERGY WILL BUILD INTO THE AREA IN THE WAKE OF THE COLD FRONT. KEPT THE HIGHEST POPS IN THE WEST TO NORTHWEST AND TAPER CHANCES IN THE SOUTHEAST. NORTHWEST WINDS WILL BECOME QUITE GUSTY THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER TERRAIN. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE LOWER 50S IN THE NORTHWEST MOUNTAINS TO THE LOWER 70S IN THE PIEDMONT WITH DOWNSLOPE COMPRESSIONAL WARMING IN THIS REGION. UPPER LOW WILL PIVOT DOWN INTO THE AREA TONIGHT AND TO THE MID ATLANTIC COAST ON WEDNESDAY. PLAYED POPS CLOSE TO THE SUPERBLEND WITH BEST CHANCE IN THE NORTHWEST TONIGHT. LOW TEMPERATURES TONIGHT WILL GENERALLY RANGE FROM THE MID 30S IN THE MOUNTAINS TO THE MID 40S IN THE PIEDMONT. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 415 AM EDT TUESDAY... THROUGH THURSDAY...THE FOCUS FOR THIS PERIOD WILL BE ON A DEEP CLOSED UPPER LOW PROGGED TO DIVE DOWN INTO THE DELMARVA REGION...THEN SLOWLY LIFT INTO NEW ENGLAND FOR THE WEEKEND. THE LOW WILL KEEP A PERSISTENT CYCLONIC FLOW OVER THE REGION WITH VARIABLE CLOUD COVER...ESPECIALLY ACROSS THE MOUNTAINS...SCATTERED LIGHT RAIN SHOWERS...AND COOL TEMPERATURES. WITH THE REGION REMAINING ON THE WEST TO SOUTHWEST...DRIER SIDE OF THE SYSTEM...QPF WILL BE MINIMAL...MAINLY A FEW SPRINKLES OR HUNDREDTHS OF AN INCH NORTH OF U.S. 460...AND PERHAPS UP TO 1/4 INCH OVER THE THREE DAY PERIOD EASTERN WV MOUNTAIN UPSLOPE AREAS. IN ADDITION...WITH A DEEP SFC LOW DEVELOPING OFF THE DELMARVA IN ASSOCIATION WITH THE UPPER LOW...GUSTY NW WINDS WILL DEVELOP WED- THU. SO...WHILE THE PRECIPITATION AMOUNTS WILL BE SCANT...CONDITIONS WED-THU WILL BE FAR FROM IDEAL WITH ABUNDANT CLOUDS...CHILLY WINDS...AND SCATTERED LIGHT RAIN SHOWERS. THE WORST CONDITIONS WILL BE ACROSS THE MOUNTAINS...WITH BETTER CONDITIONS...LESS CLOUDS AND WARMER TEMPERATURES...ACROSS THE NC PIEDMONT COUNTIES. WITH RESPECT TO WINTER WEATHER CONCERNS...THERE REALLY ARE NONE. THERE IS A POCKET OF NEAR 0C AIR WHICH DEVELOPS ON THE BACK SIDE OF THE UPPER LOW LATE WED INTO THU...BUT MOVES ACROSS RAIN FREE AREAS OF EASTERN KY/EASTERN TN/FAR SW VA...AND NW NC. AT THIS POINT...NO PRECIPITATION IS INDICATED IN THESE AREAS. OTHERWISE...LOW-LEVEL THICKNESS VALUES ACROSS THE COLDER WESTERN MOUNTAIN AREAS REMAIN MOSTLY IN THE 1330-1340 RANGE...MUCH TOO WARM FOR ANY CONCERN WITH WINTER PRECIPITATION. IN ADDITION...SFC TEMPS WILL REMAIN ABOVE FREEZING...SO HAVE NOT INCLUDED ANY WINTER PCPN IN THE GRIDS AND REMOVED THE FEW PIXELS OF SNOW PREVIOUSLY INDICATED ACROSS NW GREENBRIER. THE BIGGER CONCERN WITH THESE TEMPERATURES WILL BE THE FROST/FREEZE POTENTIAL IN AREAS THAT CLEAR...BUT TURBULENT MIXING/WIND MAY PREVENT THAT ONCE AGAIN. NEAR NORMAL MIN TEMPS AND BELOW NORMAL MAX TEMPS ARE EXPECTED THROUGH MID-WEEK IN NORTHERN AREAS...WITH READINGS CLOSER TO NORMAL IN SOUTHERN AREAS WHERE MORE SUNSHINE IS EXPECTED. FOR FRIDAY...THE MODELS HAVE BEEN AT ODDS AS TO WHAT TO DO WITH A NORTHERN STREAM TROUGH THAT FOLLOWS IMMEDIATELY BEHIND THE CLOSED LOW. WHILE A COUPLE OF RUNS BACK...THIS WAS SLATED TO STAY IN THE SOUTHERN STATES...A HIGH AMPLITUDE...SLOWLY PROGRESSIVE UPPER RIDGE THROUGH THE CENTRAL U.S. WILL KEEP THIS FEATURE FURTHER NORTH. IN ESSENCE...IT IS SOMEWHAT OF AN ALBERTA CLIPPER...BUT HAS PRECIOUS MOISTURE WITH WHICH TO WORK. GFS/ECMWF WANT TO GENERATE SOME -RA WITH THIS ACROSS THE MOUNTAINS...BUT FOR NOW WILL KEEP ALL POPS BELOW 15 PERCENT. USED A MODEL BLEND OF MAX/MIN TEMPS THROUGHOUT THE PERIOD...MAX TEMPS ABOUT 10 DEGREES BELOW NORMAL THROUGH MUCH OF THE WEEK...AND MIN TEMPS NEAR NORMAL. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 445 AM EDT TUESDAY... BENIGN...DRY WEATHER CONDITIONS EXPECTED TO DOMINATE THE REGION THROUGH THE WEEKEND AS THE AFOREMENTIONED BROAD UPPER RIDGE DRIFTS FROM THE CENTRAL U.S. INTO THE EASTERN U.S. THIS RIDGE WILL EFFECTIVELY SHUT OFF ANY INFLUX OF GULF MOISTURE...ACTUALLY SUPPRESSED WELL SOUTH OF THE GULF COAST EVEN...AND LOCK THE COLD CANADIAN AIR WELL NORTH OF THE BORDER WITH A STRONG ZONAL FLOW ACROSS THAT REGION. THE 850MB 0C ISOTHERM IS PROGGED TO REMAIN MOSTLY NORTH OF THE CANADIAN BORDER THROUGH THE END OF OCTOBER. THROUGH THE WEEKEND...850MB TEMPS ARE PROGGED TO RISE INTO THE +12C TO +14C...SO TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL...ESPECIALLY MAX TEMPS...WITH MIN TEMPS CREEPING TO SLIGHTLY ABOVE NORMAL LEVELS BY SUNDAY AS WELL. SHOULD BE A FANTASTIC WEEKEND TO VIEW THE BRILLIANT FALL FOLIAGE AROUND THE REGION...WHICH IS AT ITS PEAK NOW IN MANY PARTS OF THE CWA AND SURROUNDING AREAS. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... AS OF 730 AM EDT TUESDAY... LEADING SHORTWAVE IN ADVANCE OF DEEPENING...SOON TO BE CLOSED UPPER LOW MOVING EAST OF THE REGION THIS MORNING. NEXT LOBE OF PVA EXPECTED TO MOVE SOUTHEAST TOWARD THE REGION BY AFTERNOON...WHICH WILL AGAIN BE ASSOCIATED WITH -SHRA OR SPRINKLES...WEST OF THE BLUE RIDGE...AND INCREASINGLY STRONG/GUSTY W-WNW WINDS THROUGH THE REMAINDER OF THE TAF VALID PERIOD. OVERNIGHT/EARLY WED...UPPER LOW WILL DIVE TO A POSITION JUST SOUTH OF DCA/IAD...WITH SFC CYCLOGENESIS JUST TO THE EAST ALONG THE COAST. AS A RESULT WINDS WILL CONTINUE TO REMAIN STRONG AND GUSTY OVERNIGHT...WITH EVEN STRONGER/GUSTIER WINDS...POTENTIALLY TO 30KTS AT ROA/BCB/BLF...POSSIBLE DURING THE DAY WED. WITH RESPECT TO CIGS AND VSBYS...ALL TAF SITES WILL REMAIN ON THE DRIER...SW SIDE OF THE UPPER LOW. HOWEVER...THE AFOREMENTIONED SFC LOW WILL RESULT IN INCREASE UPSLOPE FLOW ACROSS THE ALLEGHANYS AND WEST OF THE BLUE RIDGE. THUS...CIGS WILL PROGRESSIVELY LOWER TO IFR...POTENTIALLY EVEN HIGH END LIFR AT BLF/LWB/BCB AFT 00Z...AND ESPECIALLY AFT 06Z. SCT -SHRA WILL ALSO CONTINUE AT TIMES...AT THIS POINT MAINLY BECAUSE OF UPSLOPE FLOW AND LOW-LEVEL CAA. VISIBILITIES SHOULD NOT BE A PROBLEM WITH STRONG CYCLONIC FLOW AND VERY LIGHT RAINFALL. MAY NEED TO WATCH BLF AFT 06Z IF CLOUD CIGS LOWER BELOW 004...WHICH COULD RESULT IN MVFR-IFR VSBYS AT THAT TIME. ROA/LYH/DAN ARE EXPECTED TO REMAIN VFR THROUGHOUT THE TAF VALID PERIOD WITH VFR CLOUD CIGS. WINDS WSW 5-8KTS WITH LOW END GUSTS THROUGH MIDDAY...BECOMING WNW AND INCREASING TO 10-12KTS WITH GUSTS 20-22KTS THROUGH THE REMAINDER OF THE TAF VALID PERIOD...ESPECIALLY WEST OF THE BLUE RIDGE. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... THE UPPER LEVEL LOW WILL SLOWLY MEANDER ABOUT THE MID-ATLANTIC REGION THROUGH THU...THEN BEGIN TO SHIFT TOWARD THE NORTHEAST BY FRI. THE MAIN IMPACT WILL BE A PERSISTENT NORTHWEST GUSTY WINDS AND SCATTERED -SHRA THAT WILL IMPACT PRIMARILY THE PREFERRED UPSLOPE REGION OF SOUTHEAST WEST VIRGINIA INTO WED NIGHT OR EVEN THURS MORNING. MVFR CLOUDS WILL THUS BE COMMON ACROSS THE MOUNTAINS DURING THIS TIME PERIOD...BUT FROM ROA TO LYH TO DAN CONDITIONS ARE LIKELY TO REMAIN VFR THROUGH THIS PERIOD. THE PERSISTENT TROUGH WITH NORTHWEST FLOW AND LOW-LEVEL UPSLOPE CLOUDS IN WEST WILL SLOWLY BE REPLACED BY AN UPPER LEVEL RIDGE BY FRIDAY AND INTO THE WEEKEND...FOR DRY AND WARM CONDITIONS. VFR CONDITIONS ARE EXPECTED AREAWIDE FRI-SUN. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...KK/MBS SHORT TERM...RAB LONG TERM...PM/RAB AVIATION...KK/RAB

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