Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191736 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1236 PM EST FRI DEC 19 2014 .SYNOPSIS... HIGH PRESSURE OVER THE UPPER MIDWEST WILL GRADUALLY BUILD SOUTHEAST ACROSS THE AREA RESULTING IN OVERALL DRY WEATHER INTO TONIGHT. A WEAK AREA OF LOW PRESSURE WILL DEVELOP ALONG THE GULF COAST STATES LATE TONIGHT AND MOVE EAST OVER THE SOUTHEAST STATES ON SATURDAY. THIS SYSTEM WILL BRING A PERIOD OF LIGHT WINTRY PRECIPITATION TO MAINLY SOUTHERN AND WESTERN AREAS SATURDAY MORNING BEFORE TAPERING OFF SATURDAY AFTERNOON. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1228 PM EST FRIDAY... DRYING TAKING PLACE IN THE LOW LVLS WITH LOW CLOUDS SHRINKING OVER THE WV MTNS. JUST A FEW SC/CU THIS AFTERNOON LEFT IN THE MTNS WITH HIGH CLOUDS STARTING TO INCREASE...MAINLY THIN BUT WILL LEAD TO A MILKY SKY BY LATE AFTERNOON IN THE SW. MADE MINOR ADJUSTMENTS TO TEMPS BUT OVERALL STILL LOOKING AT MID 30S FOR HIGHS IN THE HIGHER MOUNTAINS TO LOWER 50S SOUTHEAST. PREVIOUS VALID DISCUSSION... MID LEVEL WAVE OVER TX LATE THIS MORNING WILL GIVE RISE TO WEAK SURFACE LOW PRESSURE ALONG THE NORTHERN GULF LATE TONIGHT WITH PLENTY OF SHEARED MOISTURE ZIPPING NE INTO THE REGION OVERNIGHT. HOWEVER THE SYSTEM STILL LOOKS TO REMAIN WEAK GIVEN THE MAIN UPPER JET WELL TO THE SOUTH AND DAMPENING OF THE MID LEVEL SHORTWAVE AS IT GETS BOOTED EAST WITHOUT PHASING VIA A SEPARATE NORTHERN STREAM VORT. BEST MOISTURE TRANSPORT WITH THE WEAK SURFACE LOW WILL STAY SOUTH WITH PERHAPS A SECOND ZONE OF LIGHT PRECIP FARTHER NORTH DRIVEN BY THE COMBO OF THE WAVE ALOFT AND WEAK ISENTROPIC LIFT INTO SW SECTIONS LATE. MODELS CONTINUE TO ONLY SHOW VERY LIGHT QPF AND WOULDN`T TAKE MUCH LIFT TO THE SOUTH TO TOTALLY CUT OFF MOISTURE INTO THE CWA PER LATEST EURO. HOWEVER WITH SOME SPOTTY QPF OF UP TO A TENTH OF AN INCH OFF THE NAM OVER THE NW NC MOUNTAINS...BROUGHT IN LOW LIKELYS THERE BY DAYBREAK WHILE SPREADING LOW CHANCES FARTHER NORTH ACROSS MOST OF THE MOUNTAINS/FOOTHILLS UNDER THE WAVE AXIS. FORECAST SOUNDINGS SHOW MOST OF THE REGION BELOW FREEZING ALOFT SO PTYPE MAINLY SNOW WITH PERHAPS THE WARMER BOUNDARY LAYER IN SPOTS CAUSING A BIT MORE RAIN TO INIT FOOTHILLS EAST. SOME SLEET ALSO POSSIBLE DURING THE CHANGE TO SNOW AT THE ONSET IN THESE SPOTS AS WELL SO INCLUDED MENTION. OVERALL SNOWFALL LOOKS TO BE LESS THAN A HALF INCH AT BEST BY MORNING...THUS NO HEADLINES GIVEN LIGHT AMOUNTS AND POTENTIAL FOR JUST MORE CLOUDS THAN SIGNIFICANT QPF AT THIS POINT. OTRW BECOMING CLOUDY ALL SECTIONS WITH LOWS IN THE 20S TO LOW 30S...MAINLY THIS EVENING...THEN STEADYING OR RISING LATE AS CLOUDS THICKEN.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 330 AM EST FRIDAY... WEATHER FORECAST MODELS OVER THE PAST FEW RUNS ARE SETTLING ON A MODEST UPPER LEVEL TROUGH PASSING ACROSS THE AREA ON SATURDAY...WITH A WEAK LOW PRESSURE SYSTEM MOVING NORTHEAST ALONG THE ATLANTIC COAST. THIS WILL BRING LIGHT SNOW ACROSS THE AREA DURING THE MORNING AND AFTERNOON...WITH SPOTTY ACCUMULATIONS...MOSTLY LESS THAN AN INCH...CONFINED TO THE HIGHER RIDGES...PARTICULARLY ALONG THE BLUE RIDGE PARKWAY SOUTH OF ROANOKE INTO THE MOUNTAIN EMPIRE. ENERGY ASSOCIATED WITH THE UPPER TROUGH WILL EXIT TO THE EAST DURING THE AFTERNOON...LEAVING ONLY LIGHT SNOW SHOWERS ALONG THE WESTERN RIDGES DURING THE EVENING. OTHERWISE...WILL BE LOOKING AT DRY WEATHER THROUGH SATURDAY NIGHT...AS ANOTHER ROUND OF HIGH PRESSURE PASSES ACROSS EASTERN CANADA...AND BUILDS SOUTHWARD ACROSS NEW ENGLAND AND THE MID ATLANTIC TO WEDGE AGAINST THE EASTERN FACE OF THE APPALACHIANS. YET ANOTHER TROUGH WILL APPROACH FROM THE WEST ON SUNDAY... SUPPORTING DEVELOPMENT OF LOW PRESSURE ALONG THE CENTRAL GULF COAST. SOUTHERLY FLOW OFF THE SURFACE WILL PUSH WARM GULF AIR ALONG THE CENTRAL APPALACHIANS TO OVERRUN THE COLD NORTHEASTERLY WIND FLOW ASSOCIATED WITH THE HIGH PRESSURE WEDGE. AS SUCH...EXPECT TO SEE A WINTRY MIX DEVELOP SUNDAY NIGHT AS PRECIPITATION ENTERS OUR AREA. FORECAST MODEL SOUNDINGS INDICATE THAT THE COLD AIR ASSOCIATED WITH THE WEDGE IS DEEP ENOUGH TO CAUSE MUCH OF THE PRECIPITATION ACROSS THE MOUNTAINS TO FALL AS A MIXTURE OF SLEET AND RAIN NORTH OF HIGHWAY 460...WITH TEMPERATURES TOWARD THE INTERSTATE 64 CORRIDOR BECOMING COLD ENOUGH THAT SNOW WILL BECOME MORE OF A POSSIBILITY. STILL A LITTLE EARLY TO DISCUSS ACCUMULATIONS...BUT AS OF THIS MORNING...IT IS LOOKING MORE LIKE AN ADVISORY CRITERIA EVENT RATHER THAN A WARNING EVENT...ALTHOUGH THIS CAN EASILY CHANGE OVER THE NEXT DAY OR TWO. TEMPERATURES WILL WARM ENOUGH BY EARLY MONDAY AFTERNOON TO ALLOW PRECIPITATION TO CHANGE MAINLY TO RAIN...POSSIBLY WITH A FEW POCKETS OF SLEET OR FREEZING RAIN REMAINING THROUGH THE DAY. THE MAIN ENERGY ASSOCIATED WITH THE SYSTEM WILL PASS EAST DURING MONDAY EVENING...LEAVING ONLY PATCHES OF LIGHT PRECIPITATION TO PASS ACROSS THE AREA OVERNIGHT. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 230 PM EST THURSDAY... A DEEP LONGITUDINAL TROUGH DEVELOPS SOUTH TO THE GULF OF MEXICO ON TUESDAY WITH INCREASING SOUTHERLY LOW LEVEL FLOW ACROSS OUR REGION...ACCOMPANIED BY INCREASING MOISTURE ADVECTION. TEMPERATURES WILL TREND MILDER FOR HIGHS TUESDAY FROM THE MID 40S TO THE LOWER 50S. BY TUESDAY NIGHT INTO WEDNESDAY...BOTH GFS AND ECWMF DEEPEN THE UPPER LOW AND ASSOCIATED TROUGH AND NEGATIVELY TILT THE FEATURE SO THAT THE TROUGH AXIS SHIFTS TO OFF THE NORTH CAROLINA COAST... COINCIDENT TO THE POSITION OF THE ASSOCIATED SURFACE OCCLUDED FRONT...WITH THE TRIPLE POINT PASSING SOMEWHERE NEAR OR JUST SOUTH OF OUR REGION. AT THIS TIME...SPC DOES NOT HAVE ANY THUNDERSTORMS IN ITS DAY 4-8 CONVECTIVE OUTLOOK. IT LOOKS LIKE...THERE IS THE POTENTIAL FOR OUR REGION TO HAVE ACTIVE WEATHER LATE TUESDAY NIGHT INTO WEDNESDAY WITH PLENTY OF SHOWERS...PERHAPS VERY GUSTY WINDS AND A FEW THUNDERSTORMS. COLD AIR PUSHES INTO THE REGION TUESDAY NIGHT INTO WEDNESDAY MORNING...ALLOWING FOR SOME RAIN AND SNOW SHOWERS. IF ENOUGH COLD AIR ARRIVES QUICKLY...THERE COULD BE SOME ACCUMULATING SNOW IN THE WESTERN MOUNTAINS. KEPT THE HIGHEST POPS OF RAIN AND SNOW SHOWERS IN THE WEST AS THE LOW CENTER MARCHES NORTHEAST PUSHES A COLD FRONT TO THE COAST. IN THE WAKE OF THE COLD FRONT A COOLING TRENDS WILL CONTINUE WEDNESDAY INTO THURSDAY...WITH WEST TO NORTHWEST FLOW ALOFT. UPPER FLOW SHIFTS TO THE SOUTHWEST AS TROF CURVES OUT IN THE CENTRAL US WITH SFC INFLECTION OF LOW PRESSURE DEVELOPS OVER THE TENNESSEE VALLEY BY FRIDAY MORNING. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 1230 PM EST FRIDAY... VFR EXPECTED THROUGH EARLY TONIGHT WITH LOW CLOUDS SHRINKING WEST OF BLF-LWB THIS AFTERNOON. HIGH CLOUDS INCREASE THROUGH THIS EVENING THEN LOWER TO A MID DECK BY MIDNIGHT. LATEST MODELS CONTINUE THE TREND OF LESS PRECIP FOR SAT MORNING BUT STILL CAN EXPECT SOME LIGHT SNOW/FLURRIES AT ALL SITES BEFORE 18Z...WITH HIGHEST IMPACT FOR AVIATION LOOKING TO STAY SOUTH OF A TRI-FVX LINE...SO WENT WITH MVFR VSBYS/CIGS AT DAN AROUND 15Z...WITH POSSIBLE MVFR CIGS AT BLF. EXTENDED DISCUSSION... THIS SYSTEM MOVES OUT FAIRLY QUICK WITH PRECIP ENDING SAT AFTERNOON. ONCE THIS FEATURE EXITS WILL SEE THE NEXT WAVE ALONG THE COAST BRING ANOTHER ROUND OF SUB-VFR CONDITIONS FOR LATER SUNDAY NIGHT INTO MONDAY. THIS SYSTEM LOOKS TO IMPACT AREAS ALONG AND EAST OF THE BLUE RIDGE...WITH YET ANOTHER SYSTEM SLATED FOR LATE TUESDAY INTO WEDNESDAY AHEAD OF A STRONG COLD FRONT. THESE SYSTEMS ARE EXPECTED TO BRING A PERIOD MAINLY RAIN BUT COULD BE SOME WINTRY WX AS WELL ESPECIALLY IN THE MOUNTAINS WITH THE SUNDAY NIGHT/MONDAY EVENT. EXPECT POTENTIAL LOW LEVEL WIND SHEAR AS WELL AND POOR FLYING WEATHER FOR EARLY NEXT WEEK.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/RCS NEAR TERM...JH/WP SHORT TERM...NF LONG TERM...KK AVIATION...JH/WP

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