Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191123 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 623 AM 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/... AS OF 218 AM EST FRIDAY... CLOUDS AGAIN THE MAIN CONCERN TODAY AS SHORTWAVE EXITS EARLY THIS MORNING AND WEAK SUBSIDENCE FILLS IN BEFORE THE NEXT WAVE APPROACHES FROM THE SW LATE TONIGHT. IR PICS SHOW A VARIETY OF MID DECK AS WELL AS HIGH END STRATO-CU PASSING ACROSS WITH LINGERING LOW CLOUDS PINNED ALONG THE NW SLOPES. GUIDANCE HANGS ON TO THIS SCENARIO INTO MID MORNING BEFORE SHOWING PERHAPS ENOUGH DRYING ALOFT TO AID CLEARING BY EARLY AFTERNOON AS BRIEF SHORTWAVE RIDGING BUILDS EAST. THIS SUPPORTS GOING WITH MORE SUN BY THIS AFTERNOON BEFORE HIGH/MID CLOUDS MAKE A RETURN OVER THE SW LATE. HIGH TEMPS REMAIN A BIT TRICKY GIVEN THE WIDE RANGE OF VALUES TO INIT THIS MORNING AND TIMING OF CLOUD EXODUS THIS AFTERNOON. OVERALL MOS A BIT COOLER THAN PREVIOUS SO LOWERED A DEGREE OR TWO IN SPOTS BUT NOT AS COOL AS THE MET TODAY PER MORE EXPECTED INSOLATION. MID LEVEL WAVE CURRENTLY HEADING NE OUT OF NEW MEXICO 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 WOULDNT 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. && .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 /12Z FRIDAY THROUGH TUESDAY/...
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AS OF 605 AM EST FRIDAY... FLYING CONDITIONS SLOWLY IMPROVING THIS MORNING BUT STILL LOOKING AT MVFR/OCNL IFR CIGS AT KBLF WITH LOW CLOUDS BANKED UP ALONG THE WESTERN SLOPES...AND PERHAPS A PERIOD OF MVFR AT KLWB. LATEST BUFKIT SOUNDINGS SUGGEST THAT MOST RESIDUAL UPSTREAM LOW CLOUDS SHOULD MIX OUT LATER THIS MORNING WITH ALL WESTERN LOCATIONS BECOMING VFR AROUND MID MORNING. SOME LOW END VFR SCT-BKN CLOUDS POSSIBLE OUT EAST THIS MORNING AS WELL BUT SHOULD ONLY LAST A FEW MORE HOURS AT BEST. OTRW SHOULD SEE WIDESPREAD VFR THIS AFTERNOON/ EVENING UNDER REDUCED CLOUDINESS BEFORE MID/HIGH LEVEL MOISTURE STARTS TO RETURN FROM THE SW...AND LOW CLOUDS POSSIBLY SNEAK BACK INTO KBLF/KLWB LATE WHERE INCLUDED SOME MVFR CIGS LATE. LIGHT PRECIP WITH WEAK LOW PRESSURE TO THE SOUTH SHOULD APPROACH THE REGION VERY LATE TONIGHT WHILE LATEST FORECAST SOUNDINGS SUGGEST ENOUGH LOW LEVEL DRY AIR TO PRECLUDE MUCH FROM REACHING THE SURFACE. THEREFORE MAINTAINING VFR UNDER LOWERING CIGS ELSW OUTSIDE OF THE SE WEST VA SITES BUT WITHOUT ANY PRECIP MENTION AT THIS POINT. EXTENDED DISCUSSION... WEAK SYSTEM WILL PASS TO THE SOUTH AND EAST SATURDAY PERHAPS BRINGING A PERIOD OF SNOW OR WINTRY MIX ACROSS SOUTHERN/SW SECTIONS INTO EARLY AFTERNOON BEFORE TAPERING. HOWEVER WITH THE MAJORITY OF THE PRECIP LOOKING TO PASS SOUTH ONLY LOOKING AT BRIEF VSBY REDUCTIONS AT WORSE...MAINLY ALONG THE KBLF-KBCB-KDAN CORRIDOR...WHERE A PERIOD OF MVFR CIGS LOOKS LIKELY INTO SATURDAY AFTERNOON. ONCE THIS FEATURE EXITS BY LATE SATURDAY...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 SHORT TERM...NF LONG TERM...KK AVIATION...JH/RCS/WP

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