Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 161419 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 919 AM EST TUE DEC 16 2014 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA TODAY WITH AN OPPORTUNITY FOR SHOWERS. HIGH PRESSURE IS EXPECTED TO RETURN FOR WEDNESDAY ASSOCIATED WITH DRY WEATHER FOR MID WEEK. UNSETTLED WEATHER WILL RETURN FOR THE WEEKEND AS AN AREA OF LOW PRESSURE MOVES ACROSS THE SOUTHEAST STATES...REACHING INTO THE MID ATLANTIC REGION SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 919 AM EST TUESDAY... FRONTAL BOUNDARY MOVING INTO THE MOUNTAINS THIS MORNING WILL MOVE EAST THIS AFTERNOON INTO TONIGHT. KFCX 88D SHOWED A FEW BANDS OF SHOWERS MOVING EAST ACROSS OUR AREA. PRECIPITATION IS QUITE PROGRESSIVE AND WILL EXIT FORECAST AREA QUICKLY. ADJUSTED POPS IN THE WEST TO ALLOW FOR DRY SLOT LATE MORNING INTO THIS AFTERNOON. RAP...NAM AND HIRESW-ARW-EAST SHOWED THE MAIN BATCH OF RAIN CLEARING AREA BY 21Z. MODIFIED TEMPERATURES THIS MORNING INTO THIS AFTERNOON LEANING TOWARDS THE LAV. TEMPERATURES WILL REBOUND THIS AFTERNOON TO HIGHS IN THE UPPER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT. ADDITIONAL CHANGES LATER THIS MORNING... AS OF 500 AM EST TUESDAY... EARLY THIS MORNING...AN AREA OF LOW PRESSURE WAS CENTERED NEAR CHICAGO WITH A COLD FRONT ARCING TO THE SOUTHEAST THROUGH OH/TN VALLEYS INTO THE GULF COAST STATES. THIS FRONT IS PROGGED TO CROSS OUR FORECAST AREA TODAY. AS OF 5AM...FRONTAL SHOWERS WERE OCCURRING FROM OHIO AND WESTERN PENNSYLVANIA...SOUTHWARD THROUGH WEST VIRGINIA INTO SOUTHWEST VIRGINIA AND THE MOUNTAINS OF NC/TN. RAIN AMOUNTS OF A FEW HUNDREDTHS TO AS MUCH AS A QUARTER OF AN INCH WERE OBSERVED OVER ERN KY/TN AS THE RAIN MOVED THROUGH THAT AREA DURING THE OVERNIGHT. ALL MODELS RACE THIS RIBBON OF SHOWER ACTIVITY ACROSS THE ENTIRE CWA BETWEEN 12Z/7A AND 18Z/1P TODAY...QPF AVERAGING A TENTH OF AN INCH OR LESS. THE NAM IS THE ONLY MODEL THAT MAINTAINS ANY SORT OF AMOUNTS NEAR A QUARTER OF AN INCH. EITHER WAY...DON`T EXPECT TO NET MUCH FROM THE PASSAGE OF THIS FRONT...SKIES CLEARING IN ITS WAKE THIS AFTERNOON. TEMPERATURES TODAY SHOULD RISE BACK INTO THE 50S MOST AREAS BEFORE SUCCUMBING TO COLD AIR ADVECTION BEHIND THE FRONT LATER THIS AFTERNOON. FOR TONIGHT...THE FRONT WILL MOVE EAST AND OFF THE COAST WHILE THE PARENT AREA OF LOW PRESSURE MOVES NORTHEAST THROUGH THE GREAT LAKES AND INTO QUEBEC CANADA. WRAP AROUND MOISTURE FROM THIS SYSTEM WILL BRING A SHALLOW LAYER OF MOISTURE BACK INTO THE MOUNTAINS WITH AN OPPORTUNITY FOR SOME LIGHT SHOWERS/FLURRIES OR FREEZING DRIZZLE DURING THE OVERNIGHT ALONG THE WESTERN SLOPES. ON THE EAST SIDE OF THE MOUNTAINS...STRONG DOWNSLOPE FLOW WILL MAINTAIN CLEAR SKIES. WEST TO NORTHWEST WINDS OF 30-35 KTS ARE PROGGED AT 85H...SO SURFACE WINDS WILL BECOME GUSTY...ESPECIALLY ALONG THE RIDGE CRESTS AND JUST LEE OF THE BLUE RIDGE. THESE WINDS WILL KEEP US WELL MIXED TONIGHT...TEMPERATURES ONLY DIPPING INTO THE 30S. THE ONLY EXCEPTION WILL BE THE HIGHEST ELEVATIONS... ABOVE 3500 FT...WHERE TEMPERATURES WILL DIP INTO THE U20S. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EST TUESDAY... BLUSTERY NW WINDS WILL CONTINUE INTO WEDNESDAY. EXPECTING FAIR WEATHER EAST OF THE BLUE RIDGE...BUT TO THE WEST MODEL SOUNDINGS ARE SHOWING A MOISTURE PROFILE SIMILAR TO WHAT WE JUST WENT THROUGH THE PAST FEW DAYS FOR THE FAR WESTERN SLOPES...WITH A VERY SHALLOW MOIST LAYER LOCKED IN UNDER THE SUBSIDENCE INVERSION WITH NW FLOW. EXPECT CLOUDS TO PERSIST FOR THE FAR WESTERN SLOPES UNTIL THE MOISTURE FINALLY PULLS OUT THURSDAY MORNING. WILL CONTINUE THE UPSLOPE LIGHT RA/FZRA THROUGH THE MORNING HOURS...BUT WOULD NOT BE SURPRISED IF LINGERS A BIT LONGER. JUST AS THE LOW LEVEL MOISTURE DEPARTS THURSDAY MORNING...A WEAK SHORT WAVE WILL MOVE THROUGH THE SOUTHERN STREAM OF QUASI ZONAL SPLIT FLOW. MODELS HAVE BEEN INCONSISTENT IN HANDLING THIS SUBTLE FEATURE...BUT IT APPEARS WORTH SLIGHT CHANCE POPS FOR A SPRINKLE OR MAYBE A FLURRY ON THE RIDGES. FRIDAY WILL GET OFF TO A DECENT START WITH WEAK RIDGING ALOFT AND FAIR WEATHER...BUT THINGS GO DOWNHILL AS A HIGH PRESSURE WEDGE BECOMES ESTABLISHED AHEAD OF AN APPROACHING LOW MOVING OUT OF THE GULF COAST. LATEST GUIDANCE IS A BIT MORE PROGRESSIVE AND WARMER WITH THIS LOW. DO NOT SEE ANY THREAT OF PCPN UNTIL LATE FRIDAY NIGHT AND IT APPEARS LIKELY TO START AS RAIN OR A MIX. IF LATER MODEL RUNS CONTINUE THE TREND TOWARD A WARMER SOLUTION...THIS WILL LIMIT POTENTIAL SNOWFALL ACCUMULATIONS. WILL HAVE TO SEE WHAT EVOLUTION BECOMES THE DOMINANT SOLUTION. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 PM EST MONDAY... AS HIGH PRESSURE BUILDS IN...WE WILL NOTICE WINDS SHIFTING INCREASINGLY NORTHEASTERLY...WHICH WILL DRAW COOLER AIR INTO OUR AREA FROM NEW ENGLAND. THE OTHER MAJOR FEATURE WE WILL SEE TAKE SHAPE IS THE PASSAGE OF A LARGE UPPER LEVEL TROUGH FROM THE ROCKIES EASTWARD ACROSS THE PLAINS. THIS TROUGH WILL SUPPORT DEVELOPMENT OF A LOW PRESSURE SYSTEM ALONG THE TEXAS COAST THAT WILL PUSH EAST NORTHEAST SATURDAY. THIS LOW PRESSURE SYSTEM WILL BE A MAJOR FACTOR IN OUR WEATHER FOR THE COMING WEEKEND...LIKELY BRINGING WINTER STORM CONDITIONS TO PORTIONS OF OUR AREA. WEATHER FORECAST MODELS ARE IN BETTER AGREEMENT WITH ONE ANOTHER TODAY CONCERNING THIS SYSTEM...BUT HAVE NOTICEABLY SHIFTED IN THE TRACK THAT THE STORM IS EXPECTED TO FOLLOW. MOST CONSISTENT OVER THE PAST COUPLE DAYS HAS BEEN THE ECMWF...AND HAVE STEERED THE LONG- RANGE FORECAST IN ITS FAVOR THIS AFTERNOON...ALONG WITH THE SIMILAR CANADIAN MODEL. HOWEVER...UNCERTAINTY STILL REMAINS AND HAVE NOT COMPLETELY BOUGHT INTO THE ECWMF/CANADIAN SOLUTIONS AS THE 15/12Z RUNS HAVE SHIFTED THE LOW EAST FROM THE PREVIOUS RUNS...WITH THE LOW NOW EXPECTED TO PASS NORTHEAST ALONG THE COAST RATHER THAN FURTHER INLAND. THE SHIFT IN TRACK KEEPS OUR AREA FURTHER AWAY FROM THE WARM AIR WRAPPING AROUND THE LOW...WHICH NOW INTRODUCES A STRONGER POTENTIAL FOR SNOW AND SLEET FURTHER EAST...POSSIBLY TO INCLUDE THE SOUTHSIDE...AS COLDER AIR IS DRAWN ACROSS OUR AREA TOWARD THE LOW CENTER. ALSO SEE A POSSIBILITY OF REDUCED PRECIPITATION FOR OUR AREA AS THUNDERSTORM ACTIVITY DEVELOPING ALONG THE GULF COAST MAY ABSORB SOME OF THE MOISTURE RIDING NORTHWARD INTO THE MID ATLANTIC. AT ANY RATE...THE FORECAST FOR THIS SYSTEM IS FAR FROM SET IN STONE...AND ADDITIONAL CHANGES/ADJUSTMENTS ARE LIKELY OVER THE NEXT COUPLE OF MODEL RUNS. THE LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT OUR AREA MAINLY FROM THE PREDAWN HOURS OF SATURDAY THROUGH LATE SATURDAY EVENING. AS THE LOW MOVES AWAY SATURDAY NIGHT...WINDS WILL SHIFT NORTHWESTERLY... RESULTING IN LINGERING UPSLOPE SNOW SHOWERS ACROSS THE WESTERN RIDGES...WHILE CLEARING CONDITIONS CAN BE EXPECTED FURTHER EAST. HIGH PRESSURE WILL BEGIN TO SETTLE ACROSS OUR AREA LATE SUNDAY EVENING. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... AS OF 700 AM EST TUESDAY... SURFACE FRONT WILL CROSS THE APPALACHIANS THIS MORNING...THEN MOVE EAST ACROSS THE PIEDMONT DURING THE AFTERNOON. SCATTERED SHOWERS WITH A PERIOD OF MVFR CIGS/VSBYS LIKELY THIS MORNING...FOLLOWED BY PARTIAL CLEARING THIS AFTERNOON. WINDS WILL INCREASE BEHIND THE FRONT...REMAINING GUSTY TONIGHT AND WEDNESDAY. HIGH CONFIDENCE FOR VFR CONDITIONS EAST OF THE MOUNTAINS TONIGHT AND WEDNESDAY. MOISTURE WILL LINGER ON THE WEST SIDE OF THE MOUNTAINS WITH MVFR CIGS PERSISTING WEST OF THE APPALACHIAN DIVIDE TONIGHT AND WEDNESDAY. LCL IFR CONDITIONS ARE POSSIBLE TONIGHT ALONG THE WESTERN SLOPES VCNTY OF KBLF AND JUST WEST OF KLWB WITH THE POTENTIAL FOR LIGHT FREEZING DRIZZLE AND FOG. EXTENDED DISCUSSION... THURSDAY AND FRIDAY LOOK RELATIVELY BENIGN. THERE IS THE POTENTIAL FOR A PERIOD OF MVFR THURSDAY ASSOCIATED WITH AN UPPER LEVEL DISTURBANCE WHICH IS FORECAST TO PASS JUST SOUTH OF THE REGION VCNTY OF THE VA/NC BORDER. POTENTIAL EXISTS FOR A WINTER STORM TO IMPACT THE REGION THIS WEEKEND...FLIGHT CONDITIONS DETERIORATING ACROSS THE AREA LATE FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE IS EXPECTED TO FORM OVER TEXAS FRIDAY...THEN TRACK NORTHEAST TO NEAR THE MID ATLANTIC COAST BY LATE SATURDAY. THIS TRACK WILL PLACE OUR FORECAST AREA ON THE COLD SIDE OF THE SYSTEM PROVIDING AN OPPORTUNITY FOR ACCUMULATING SNOW OR A WINTRY MIX. AVIATION INTERESTS WILL NEED TO MONITOR THIS SITUATION AS LATER FORECASTS BECOME AVAILABLE. THIS WILL LIKELY HAVE AN IMPACT ON AIR TRAVEL OVER THE WEEKEND...FROM THE SOUTHERN APPALACHIANS AND CAROLINAS NORTH TO THE MID ATLANTIC. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...KK/PM SHORT TERM...MBS LONG TERM...NF AVIATION...PM

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