Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 011227 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 727 AM EST SUN FEB 1 2015 .SYNOPSIS... LOW PRESSURE CENTERED NEAR KANSAS CITY THIS MORNING WILL MOVE EAST TODAY AND TONIGHT AND WILL BE CENTERED NEAR PITTSBURGH BY DAYBREAK MONDAY BEFORE MOVING OFF THE NEW ENGLAND COAST MONDAY AFTERNOON. A STRONG COLD FRONT WILL TRAIL SOUTH FROM THE LOW...SWEEPING ACROSS THE MID MISSISSIPPI VALLEY TODAY...INTO THE OHIO AND TENNESSEE VALLEYS TONIGHT...CROSSING THE APPALACHIANS MOUNTAINS EARLY MONDAY MORNING. WIDESPREAD PRECIPITATION WILL ACCOMPANY THIS STORM SYSTEM WITH SNOW NORTH OF INTERSTATE 70 AND RAIN TO THE SOUTH. && .NEAR TERM /THROUGH TONIGHT/... AS OF 400 AM EST SUNDAY... CLOUDS CONTINUE TO THICKEN ACROSS THE FORECAST AREA...ALL OF WHICH ARE THE RESULT OF THE DEVELOPING STORM SYSTEM OVER THE MIDDLE PART OF THE COUNTRY. OUR RADAR INDICATES SOME LIGHT RETURNS...BUT MOST OF THIS IS VIRGA...PRECIPITATION THAT DRIES UP BEFORE REACHING THE GROUND. SURFACE DEWPOINTS REMAIN IN THE TEENS...INDICATIVE OF THE DRY LOW LEVEL AIR. IT MAY TAKE MOST OF THE DAY BEFORE THE AIRMASS OVER OUR FORECAST AREA SATURATES ENOUGH TO PERMIT PRECIPITATION TO REACH THE SURFACE. BY THAT TIME IS SHOULD BE WARM ENOUGH FOR ANYTHING THAT REACHES THE GROUND TO BE RAIN. SOUNDING PROFILES THIS MORNING ARE CERTAINLY COLD ENOUGH TO SUPPORT A WINTRY FORM EARLY IN THE DAY...BUT THE CHANCE OF GETTING ANYTHING TO THE SURFACE IS PRETTY SMALL. CERTAINLY CAN`T RULE OUT A BRIEF PERIOD OF LIGHT SLEET OR SNOW THIS MORNING...BUT THE CHANCE FOR MEASURABLE IS LESS THAN 20 PERCENT. THE CYCLONE WHICH HAS EVOLVED OVER THE CENTRAL PART OF THE COUNTRY IS FAIRLY LARGE. THE CENTER OF THE LOW WAS NEAR KANSAS CITY THIS MORNING WITH SNOW FALLING FROM NEBRASKA TO OHIO...AND RAIN FALLING FROM MISSOURI TO THE WESTERN GULF COAST. THIS AREA OF LOW PRESSURE IS EXPECTED TO STRENGTHEN AS IT MOVES EAST TODAY...PRODUCING HEAVY SNOW FROM CHICAGO TO TOLEDO...AND MODERATE RAINS FOR THE MID MS VALLEY. THE AREA OF LOW PRESSURE IS EXPECTED TO REACH WESTERN PENNSYLVANIA BY DAYBREAK MONDAY WITH A COLD FRONT TRAILING SOUTH ALONG THE SPINE OF THE APPALACHIANS. AHEAD OF THE FRONT TONIGHT...STRONG WARM AIR ADVECTION PER SOUTHWEST WINDS WILL DRAW MOISTURE FROM THE GULF OF MEXICO NORTHWARD INTO THE TENNESSEE VALLEY AND MID ATLANTIC. THIS WILL RESULT IN A WIDESPREAD WETTING RAIN FOR OUR AREA WHICH WILL PERSIST UNTIL THE ARRIVAL OF THE FRONT MONDAY MORNING. RAINFALL AMOUNTS OF A HALF /0.50/ TO THREE QUARTERS /0.75/ OF AN INCH ARE LIKELY WITH THIS RAIN EPISODE. TEMPERATURES TODAY...PENDING CLOUD THICKNESS...SHOULD CLIMB INTO THE 40S...AND REMAIN THERE FOR TONIGHT PER THE STRONG WARM AIR ADVECTION. THE ONLY AREA WHICH MAY DIP BACK INTO THE 30S BEFORE DAYBREAK WOULD BE THE FAR WESTERN CWA WHERE THE ARRIVAL OF THE COLD FRONT WILL SIGNAL A DOWNWARD TREND OF THE TEMPERATURE PER COLD AIR ADVECTION BEHIND THE FRONT. TEMPERATURES AT 3-5KFT ABOVE THE SURFACE ARE FORECAST TO WARM TO +6 DEG C ACROSS THE ENTIRE CWA TONIGHT...SO NOT EXPECTING ANY PRECIPITATION TYPE ISSUES DURING THE OVERNIGHT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 330 AM EST SUNDAY... AS THE LOW SLIDES BY TO OUR NORTH IT WILL SWING A STRONG COLD FRONT THROUGH THE AREA MONDAY MORNING...BRINGING AN END TO WIDESPREAD PRECIPITATION AND KICKING OFF UPSLOPE SNOW SHOWERS FOR THE FAR WESTERN SLOPES. SNOW FALL AMOUNTS LOOK TO BE ON THE LIGHT SIDE AND DO NOT CURRENTLY SEE A NEED FOR ANY WINTER WEATHER ADVISORIES. EXPECT TEMPERATURES TO BE FALLING ALL DAY WEST OF THE BLUE RIDGE...BUT TEMPS MAY RISE JUST A TAD BEFORE THE FRONT MOVES INTO THE PIEDMONT SO TEMPS WILL NOT START FALLING THERE UNTIL LATE MORNING. AS THE COLD AIR ADVECTION BECOMES ESTABLISHED AND DOWNWARD MOMENTUM TRANSFER INCREASES...NORTHWEST WINDS WILL START TO HOWL MONDAY AFTERNOON. THE LOW LEVEL WIND FIELD DOES INCREASE BUT THE MIXED LAYER WILL BE FAIRLY DEEP WHICH WILL PREVENT GUSTS FROM MAXIMIZING. THIS IS SIMILAR TO SEVERAL RECENT EVENTS AND WE MAY END UP NEEDING A WIND ADVISORY ALONG AND WEST OF THE BLUE RIDGE...BUT CURRENTLY EXPECT WINDS TO REMAIN BELOW 50KTS AND NOT REACH WARNING CRITERIA. THE WIND WILL COMBINE WITH COLD TEMPERATURES MONDAY NIGHT TO BRING WIND CHILL VALUES INTO THE SINGLE DIGITS WEST OF THE BLUE RIDGE. COLD HIGH PRESSURE WILL BRING AN END TO THE UPSLOPE SNOW SHOWERS ON TUESDAY AS IT SETTLES OVER THE REGION AND BRINGS US QUIET WEATHER AND BELOW NORMAL TEMPERATURES. AS THE HIGH SLIPS BY TO OUR EAST ON WEDNESDAY WE WILL SEE TEMPS REBOUND NICELY AND RISE TO ABOVE NORMAL LEVELS AHEAD OF THE NEXT COLD FRONT APPROACHING FROM THE WEST. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 300 AM EST SUNDAY... WEATHER FORECAST MODELS HAVE NOT CHANGED MUCH CONCERNING THE APPROACH OF THE UPPER TROUGH AND ITS SUPPORT OF DEVELOPMENT OF A LOW PRESSURE SYSTEM ALONG THE SOUTHEAST COAST WEDNESDAY NIGHT. AS SUCH...EXPECT THE COLD FRONT APPROACHING FROM THE NORTHWEST TO PUSH RAPIDLY ACROSS OUR AREA LATE WEDNESDAY EVENING...FOLLOWED BY HIGH PRESSURE PASSING ACROSS THE GREAT LAKES INTO NEW ENGLAND...WITH THE HIGH THEN BUILDING SOUTHWARD ACROSS THE MID ATLANTIC TO WEDGE AGAINST THE EASTERN FACE OF THE APPALACHIANS BY THURSDAY AFTERNOON. MEANWHILE...THE LOW ALONG THE SOUTHEAST COAST WILL GRADUALLY DEEPEN AND DRIFT NORTHWARD...RADIATING MOISTURE INLAND ACROSS THE SOUTHEAST STATES INTO THE MID ATLANTIC. THE BIG QUESTION IS TO WHAT DEGREE THAT THE COASTAL LOW WILL AFFECT OUR WEATHER FOR THURSDAY. THE GFS FORECAST MODEL IS MOST AGGRESSIVE IN PUSHING MOISTURE ACROSS OUR AREA...WITH THE CANADIAN MODEL SIMILAR BUT NOT QUITE AS AGGRESSIVE. ON THE OTHER END OF THE SPECTRUM IS THE ECMWF MODEL WHICH DOES NOT DEVELOP THE COASTAL LOW AS DEEPLY AND THEREFORE KEEPS OUR AREA DRY IN THE WAKE OF THE COLD FRONT. RIGHT NOW...AM LEANING TOWARD THE GFS/CANADIAN SOLUTION... WHICH WILL BRING LIGHT WINTRY PRECIPITATION TO OUR AREA FOR THURSDAY INTO THURSDAY NIGHT. ALL MODELS AGREE THAT ATMOSPHERIC TEMPERATURES WILL BE COLD ENOUGH FOR ALMOST EXCLUSIVELY SNOW FOR OUR ENTIRE AREA. BECAUSE OF THE WIDE RANGE IN PRECIPITATION AMOUNTS WITHIN THE MODELS...HAVE NO CONFIDENCE AT THIS POINT IN THE AMOUNT OF SNOW WE WOULD RECEIVE...BUT NONE OF THE MODELS TODAY ARE CALLING FOR ACCUMULATIONS THAT WOULD CONSTITUTE A WINTER STORM ANYWHERE IN OUR AREA. MOISTURE WILL DECREASE LATE THURSDAY NIGHT AS THE LOW CONTINUES NORTHWARD OFF THE COAST. COOL HIGH PRESSURE WILL PASS ACROSS THE APPALACHIAN CHAIN ON FRIDAY...RESULTING IN MOSTLY CLEAR SKIES AND LIGHT WINDS. TEMPERATURES IN THE AFTERNOON WILL REMAIN IN THE 30S AREAWIDE. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... AS OF 800 AM EST SUNDAY... VFR TODAY WILL DETERIORATE TO IFR AFTER SUNSET. EXTENSIVE MID/UPPER LEVEL MOISTURE HAS BEEN CAST OVER THE CENTRAL APPALACHIANS IN ADVANCE OF AN APPROACHING MID CONUS STORM. PRECIPITATION FROM THESE HIGHER LEVEL CLOUDS IS EVAPORATING BEFORE REACHING THE GROUND...WITH RADAR SHOWING VIRGA OVER THE ENTIRE AREA THIS MORNING. ITS NOT OUT OF THE QUESTION TO ENCOUNTER SOME VERY LIGHT SNOW/SLEET TODAY...BUT IT SHOULD NOT RESTRICT VISIBILITY AT THE SURFACE. BY THIS EVENING...AFTER 21Z/4PM...CLOUD BASES WILL LOWER WITH APPROACH OF DEEPER MOISTURE FROM THE TENNESSEE VALLEY. FLIGHT CONDITIONS WILL DETERIORATE TO MVFR BETWEEN 21Z/4PM AND 02Z/9PM THIS EVENING THEN TO IFR BETWEEN 02Z/9PM AND 06Z/1AM. CONDITIONS WILL THEN REMAIN IFR UNTIL A FRONTAL PASSAGE MONDAY MORNING. STRONG SOUTHWEST WINDS ALOFT THIS EVENING WILL RESULT IN WARMING TEMPERATURES. THIS WILL KEEP ALL OF THE PRECIPITATION IN THE LIQUID FORM AS IT REACHES THE SURFACE TONIGHT WITH NO P-TYPE ISSUES FOR ANY OF THE TERMINALS WITHIN THE BLACKSBURG/ROANOKE SERVICE AREA. EXTENDED DISCUSSION... LOW PRESSURE WILL BE CENTERED OVER PENNSYLVANIA EARLY MONDAY WITH A COLD FRONT TRAILING SOUTH ALONG THE SPINE OF THE APPALACHIANS. A SWEEPING COLD FRONT WILL CROSS ALL OF THE FLIGHT TERMINALS IN THE CENTRAL APPALACHIANS EARLY IN THE DAY...WINDS SHIFTING TO THE NORTHWEST AND BECOMING GUSTY FOR THE AFTERNOON. PASSAGE OF THE FRONT WILL BRING AN END TO THE RAIN WITH IMPROVING CIGS/VSBYS. THE MAIN WEATHER HAZARD WILL THEN BE THE 25 TO 40 KT WIND GUSTS. MONDAY NIGHT...SKIES CLEAR AND WINDS DIMINISH...RETURN OF VFR. TUESDAY AND WEDNESDAY...HIGH PRESSURE PASSES OVERHEAD WITH VFR. THURSDAY...LOW PRESSURE MOVING ACROSS THE SOUTHEAST U.S. MAY BRING SUB-VFR CONDITIONS AND PRECIPITATION...POSSIBLY SNOW TO THE REGION. SINCE THIS STORM IS TAKING A GULF COAST TRACK...WINTRY PRECIPITATION MAY IMPACT SOUTHERN TERMINAL ROUTES INCLUDING CHARLOTTE AND ATLANTA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...MBS LONG TERM...MBS/NF AVIATION...PM

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