Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 261752 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1252 PM EST FRI DEC 26 2014 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH TONIGHT. LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY WILL TRACK ALONG A COLD FRONT SATURDAY AND SUNDAY AND WILL BE OVER THE CAROLINA BY MONDAY MORNING. HIGH PRESSURE GRADUALLY BUILDS ACROSS THE EASTERN UNITED STATES TUESDAY AND WEDNESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1245 PM EST FRIDAY... MINOR UPDATES TO FORECAST GRIDS FOR THIS AFTERNOON BASED ON CURRENT SKY COVER AND TEMPS CLIMBING A LITTLE FASTER ACROSS HIGHER ELEVATIONS ACROSS THE NW NC MTNS. ADJUSTED MAX TEMP UPWARD FOR NW NC MTNS. ALSO DEW PTS A LITTLE HIGHER THAN ANTICIPATED. DOES LOOK LIKE SOME BROKEN CIRRUS MAY REACH SW PART OF AREA BY VERY LATE IN THE DAY. PREV DISCUSSION AS OF 935 AM EST FRIDAY... TEMPS A LITTLE SLOWER TO WARM UP SO FAR THIS MORNING UNDER STRONG BUT SHALLOW INVERSION THAT RNK AND GSO SOUNDINGS ARE SHOWING...BUT THAT WILL CHANGE VERY QUICKLY BY 10AM OR SO. RIVER VALLEY FOG HOLDING ON STRONG ESPECIALLY NEW RIVER IN GILES WESTWARD AND THE GREENBRIER VALLEY...AND AS OF 930AM THIS WAS STILL FREEZING FOG SO HAVE KEPT A STATEMENT GOING THERE A LITTLE LONGER. AFTER THIS DISSIPATES OVER THE NEXT HOUR...SKIES WILL BE MOSTLY SUNNY WITH ONLY A FEW THIN AND VERY SCATTERED HIGH CLOUDS DRIFTING ACROSS AT TIMES. SHOULD AHVE NO IMPACT ON HIGH TEMPS...AND WITH GOOD MIXING...COULD GET CLOSE TO 60 IN A NUMBER OF LOCATIONS BASED ON PROFILES FROM SOUNDINGS. JUST HOW DEEP THE MIXING WILL BE IS THE QSTN. NUDGED UP HIGHS A DEG OR TWO MAINLY IN THE MTNS...BUT STILL KEEPING MID TO UPPER 50S. A VERY NICE LATE DECEMBER DAY TO BE OUTSIDE! PREV DISCUSSION AS OF 330 AM EST FRIDAY... SOUTHEAST UPPER RIDGE BUILDS TODAY AND TONIGHT WITH MODEST RISE IN HEIGHTS OVER THE FORECAST AREA. SHORT WAVE OVER THE LOWER MISSISSIPPI VALLEY WILL TRACK AROUND THE RIDGE INTO THE COUNTY WARNING AREA LATE TONIGHT. MODELS SHOWED SOME UPPER LEVEL MOISTURE WITH THIS FEATURE LATE TONIGHT. OTHERWISE HUMIDITY BELOW 700 MB REMAINS LOW AND UNTIL THEN...LITTLE TO NO CLOUD COVER IS EXPECTED. SURFACE HIGH PRESSURE REMAINS OVER THE AREA UNTIL LATE TONIGHT. WINDS WILL GRADUALLY TURN TO THE SOUTHWEST AS THE HIGH MOVES OFFSHORE EARLY SATURDAY MORNING. HIGHS TODAY WILL BE 5 TO 10 DEGREES ABOVE NORMAL. APPEARS A REASONABLE RISE IN TEMPERATURES FROM VALUES THIS MORNING SINCE VERY DRY AIR MASS IS IN PLACE. LOWS TONIGHT WILL AGAIN BE COOLER IN THE VALLEYS AND WARMER ON THE RIDGES. STAYED CLOSE TO GRIDDED LAV GUIDANCE FOR MAXIMUM TEMPERATURES TODAY AND MET GUIDANCE FOR LOWS TONIGHT.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 300 AM EST FRIDAY... THE CENTER OF AN AREA OF HIGH PRESSURE WILL CONTINUE TO SHIFT EAST OF THE REGION DURING THE DAY SATURDAY. SOUTHWEST FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR ANOTHER DAY OF VERY MILD TEMPERATURES FOR THIS TIME OF YEAR. TO OUR WEST WILL BE A CONVEYER BELT OF MOISTURE BETWEEN OUR DEPARTING HIGH...AND HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS. WEAK AREAS OF LOW PRESSURE ARE EXPECTED TO TRACK NORTHEAST ALONG THIS BOUNDARY. SATURDAY NIGHT INTO SUNDAY THIS FEATURE WILL SHIFT EASTWARD ACROSS OUR REGION...ALONG WITH INCREASING CHANCES OF RAIN. BY SUNDAY AND SUNDAY NIGHT RAIN IS LIKELY ACROSS THE ENTIRE AREA WITH CONDITIONS STILL ON THE MILD SIDE. BY MONDAY INTO MONDAY NIGHT...THE MOISTURE FETCH WILL SHIFT EAST OF OUR AREA. COOLER AIR WILL START TO ENTER THE REGION IN THE WEST...ALLOWING FOR THE POTENTIAL FOR SOME LIGHT SNOW ON THE BACKSIDE OF THE EXITING SYSTEM. TEMPERATURES SATURDAY THROUGH MONDAY WILL BE VERY MILD...10 TO 15 DEGREES ABOVE NORMAL...FOR THIS TIME OF THE YEAR...BUT TREND COOLER TO ABOUT FIVE DEGREES ABOVE NORMAL MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM EST THURSDAY... EARLY PART OF NEXT WEEK LOOKS TO BE UNSETTLED WITH LARGE SCALE TROUGH OVER THE WESTERN TWO THIRDS OF THE COUNTRY EJECTING AT LEAST ONE FINAL S/WV PIECE OF ENERGY TOWARD SRN APPALACHIANS ON MONDAY...WITH POTENTIALLY SOME VERY LIMITED LINGERING MOISTURE ON WESTERN SLOPES INTO TUESDAY. STILL SOME MODEL DIFFERENCES IN 12Z CYCLES...WITH ECMWF AND CANADIAN REMAINING MOST AGGRESSIVE WITH S/WV AND AMOUNT OF MOISTURE OVERRUNNING THE RNK FCST AREA AS SFC LOW TRACKS TO THE SOUTH. ECMWF IS FASTER THAN WET CANADIAN AND HAS ANY PRECIP EXITING BY MIDDAY MONDAY. GFS AND AT LEAST SOME OF ITS ENSEMBLES ARE WEAKER AND MORE PROGRESSIVE WITH THIS S/WV...KEEPING MOST LIGHT PRECIP TO OUR SOUTH. IN ALL CASES...LOW LEVEL THERMAL PROFILES TOO WARM FOR ANY WINTRY PRECIP. BEST FOR NOW TO GO WITH COMPROMISE OF ALL THESE IDEAS...WHICH ENDS UP BEING CLOSE TO ECMWF BUT LEANING A LITTLE TOWARD GFS. NOT GOING AS WET SLOW AS CANADIAN. BUT WITH UNCERTAINTY THROUGH LATE MONDAY DO NOT FEEL IT PRUDENT TO GO WITH HIGHER THAN 50 POP ANYWHERE...BUT HAVE HIGHEST POPS IN EAST MONDAY WITH EXITING SYSTEM...AS WELL AS LINGERING UPSLOPE CHANCE POPS FAR WEST...AND KEEPING SOME VERY LOW CHANCE POPS INTO MON NIGHT PERIOD. AFTER THAT MODELS NOW IN BETTER AGREEMENT THAT BY MID WEEK A FLAT UPPER TROUGH SETTLES MORE INTO THE EASTERN THIRD OF THE COUNTRY WITH SPLIT FLOW OVER THE ROCKIES...AS SIGNIFICANT ENERGY CUTS OFF FROM THE FLOW OVER SRN CALIFORNIA. GOOD TO SEE ALL THE MODELS AGREEING ON THIS IDEA...YET HAVE TO BE A LITTLE LEERY OF MODEL SKILL IN DEVELOPING THIS CUTOFF...SO STILL CANNOT RULE OUT SOME WEAK WAVES HEADING IN OUR DIRECTION THROUGH MID WEEK...BUT CHANCES LOOK BETTER FOR BROAD DRY BUT COOL SURFACE HIGH TO DOMINATE WITH WESTERLY FLOW...AND PERHAPS STILL JUST ENOUGH MOISTURE TO SNEAK OUT SOME SPRINKLES OR FLURRIES IN THE FAR WEST AT TIMES. HAVE LOWERED POPS TUESDAY TO ONLY SLIGHT CHANCE IN FAR WEST...AND DECIDED TO TAKE OUT COMPLETELY FOR WED GIVEN MODEL AGREEMENT OF DRY HIGH PRESSURE REALLY PUSHING IN FROM WEST...ALTHOUGH STILL SOME WEAKLY CYCLONIC FLOW AT MID LEVELS AND LIKELY SOME LOW LEVEL CLOUDS IN WEST IN ADDITION TO POSSIBILITY OF HIGH LEVEL CLOUDS EVERYWHERE. MOST LIKELY DRY INTO THURSDAY AS WELL...BUT ECMWF ADVERTISING SOME BETTER ENERGY ONCE AGAIN TRYING TO PUSH INTO THE SFC RIDGE LATE IN THE WEEK...LATEST 12Z RUN SLOWED THIS DOWN A BIT...SO HAVE LEFT POPS OUT FOR NOW UNTIL PERHAPS OVERNIGHT...AND THEN WILL HAVE TO SEE WHAT FUTURE RUNS DO WITH THIS BY NEXT FRIDAY. GRADUAL COOLING TREND THROUGH THIS PERIOD DUE TO BROAD BUT RATHER FLAT UPPER TROUGH AND ASSOCIATED LARGE SFC HIGH FROM CENTRAL U.S. SHIFTING TOWARD APPALACHIANS...AND TEMPS WILL END UP PRETTY CLOSE TO SEASONAL NORMS BY MID WEEK. BOTTOM LINE IS NO MAJOR WINTRY WEATHER TO DEAL WITH THROUGH NEW YEARS DAY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 1253 PM EST FRIDAY... HIGH PRESSURE WILL COVER THE REGION THROUGH SATURDAY WITH VFR CONDITIONS AND LIGHT WINDS. SOME THIN MID/HIGH CLOUDS WILL CROSS THE REGION TONIGHT AND SHOULD PREVENT FOG FROM FORMING IN RIVER VALLEYS AS IT DID LAST NIGHT...SO AM LEAVING KLWB TAF VFR THROUGH SATURDAY MORNING. IF SKIES SHOULD HAPPEN TO CLEAR BEFORE DAWN THEN SOME FOG COULD FORM NEAR THE RIVER AGAIN...SO THAT WILL NEED TO BE MONITORED OVERNIGHT. EXTENDED DISCUSSION... ANOTHER COLD FRONT WILL APPROACH THE REGION LATE SATURDAY WITH VFR CLOUDS FILLING IN ACROSS THE REGION AND CEILINGS STEADILY LOWERING OVERNIGHT. SATURDAY NIGHT THROUGH MONDAY...THE FRONT WILL STALL NEAR THE WEST SIDE OF THE APPALACHIANS AS MULTIPLE WEAK WAVES OF LOW PRESSURE ARE EXPECTE TO RIDE UP THIS BOUNDARY... RESULTING IN A PROLONGED PERIOD OF RAIN AND IFR TO MVFR CONDITIONS. IFR CONDITIONS ARE NOT LIKELY TO DEVELOP INTO EARLY MORNING SUNDAY IN THE WEST...AND PERHAPS NOT UNTIL SATURDAY EVENING IN THE EAST. THE FRONT MAY LINGER JUST TO THE SOUTH OF THE AREA EARLY NEXT WEEK...BUT AT THIS TIME CONFIDENCE IS FAIRLY HIGH THAT AIRPORTS WILL REMAIN DRY WITH VFR CONDITIONS PREVAILING. SOME MVFR CEILINGS COULD LINGER AT KDAN INTO TUESDAY HOWEVER. THE NEXT CHANCE FOR WIDESPREAD IFR CONDITIONS WILL NOT COME UNTIL NEXT FRIDAY AT THE EARLIEST.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/SK SHORT TERM...DS LONG TERM...SK AVIATION...AMS/JH/SK

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