Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 291152 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 652 AM EST THU JAN 29 2015 .SYNOPSIS... LOW PRESSURE NEAR CHICAGO THIS MORNING WILL MOVE RAPIDLY EAST ACROSS SOUTHERN MICHIGAN TODAY AND INTO NEW ENGLAND TONIGHT. A SURFACE COLD FRONT WILL TRAIL SOUTH FROM THE LOW...AND WILL SWEEP SOUTHEAST ACROSS THE OHIO VALLEY TODAY...THEN THROUGH THE MID ATLANTIC REGION TONIGHT. HIGH PRESSURE WILL THEN BUILD ACROSS THE REGION FOR FRIDAY AND SATURDAY...FOLLOWED BY AN AREA OF LOW PRESSURE WHICH WILL MOVE FROM TEXAS SUNDAY...TO THE MID ATLANTIC COAST BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 430 AM EST THURSDAY... ANOTHER COLD START WITH TEMPERATURES IN THE 20S THIS MORNING. A FEW LOCATIONS DIPPED INTO THE TEENS DURING THE NIGHT BUT INCREASING CLOUD COVER HAS PUT A HALT TO THE FALLING TEMPERATURES. IN SPITE OF THE INCREASING UPPER LEVEL CLOUD COVER...THE BOUNDARY LAYER REMAINS VERY DRY WITH DEWPOINTS IN THE TEENS AND SINGLE DIGITS. FOR TODAY...WATCHING AN AREA OF LOW PRESSURE VCNTY OF CHICAGO. THIS CLIPPER LIKE SYSTEM WILL MOVE RAPIDLY EAST TODAY...REACHING BUFFALO NEW YORK BY THIS EVENING. A COLD FRONT TRAILS SOUTH FROM THE LOW AND IS ASSOCIATED WITH A NARROW CORRIDOR OF LOW LEVEL MOISTURE WHICH IS RESULTING IN SOME LIGHT PRECIPITATION ACROSS THE OHIO VALLEY. SURFACE OBS INDICATE MOST OF THIS PRECIP TO BE LIGHT RAIN OR VIRGA YIELDING TRACE AMOUNTS TO AS MUCH AS 2 HUNDREDTHS OF AN INCH /0.02/. THIS BAND OF LIGHT PRECIPITATION IS FORECAST TO PROGRESS EAST THIS MORNING...CROSSING OHIO/KENTUCKY/TENNESSEE. MODELS INDICATE THE LEADING EDGE OF THE PRECIPITATION WILL REACH OUR FAR WESTERN CWA AROUND 18Z/1PM TODAY...THEN DRY UP AS IT ENCOUNTERS THE VERY DRY BOUNDARY LAYER AIR ON THE EAST SIDE OF THE MOUNTAINS THIS AFTERNOON. THIS SEEMS REASONABLE...AND HAVE PRETTY MUCH FOLLOWED GUIDANCE WITH RESPECT TO POPS CONFINING THE HIGHEST POPS AND BEST CHANCE FOR MEASURABLE PRECIPITATION TO OUR WESTERN COUNTIES...WITH ONLY A SLIGHT CHANCE ANYTHING MAKES IT EAST OF THE MOUNTAINS THIS AFTERNOON. AS FAR AS P-TYPE...IT LOOKS LIKE THE BOUNDARY LAYER WILL BE TOO WARM TO SUPPORT SNOW... SO WILL GO WITH MAINLY RAIN OR SPRINKLES. SINCE THE BOUNDARY LAYER IS SO DRY AND THE WETBULB WILL BE NEAR FREEZING...CAN`T RULE OUT SOME SLEET MIXING IN AT THE ONSET. BEST CHANCE FOR SEEING SLEET WOULD BE ALONG AND NORTH OF INTERSTATE 64. WITH TEMPERATURES CLIMBING ABOVE FREEZING THIS SHOULD HAVE NO IMPACT...AT LEAST DURING THE DAY LIGHT HOURS. FOR TONIGHT...PASSAGE OF THE COLD FRONT DURING THE EVENING WILL BRING FALLING TEMPERATURES. ANY LINGERING MOISTURE WILL THEN CHANGE BACK OVER TO SNOW. MAIN FOCUS FOR SNOW WILL BE OVER THE WESTERN CWA WHERE PERSISTENT LOW LEVEL MOISTURE WILL REMAIN ON THE WESTERN SLOPES OF THE APPALACHIANS...YIELDING OCCASIONAL SNOW SHOWERS AND FLURRIES. HIGHEST ACCUMULATIONS ARE EXPECTED TO BE OVER THE WV HIGHLANDS... WITH 2 TO 4 INCHES POSSIBLE FOR WESTERN GREENBRIER. AN INCH OR TWO IS ALSO POSSIBLE FROM BLUEFIELD SOUTHWARD INTO THE NORTH CAROLINA HIGH COUNTRY...BUT AGAIN...FOCUS FOR THE GREATEST ACCUMULATIONS WILL BE ACROSS THE HIGHER TERRAIN. ON THE EAST SIDE OF THE MOUNTAINS... DOWNSLOPE FLOW WILL RESULT IN DRYING...WITH LITTLE OR NO PRECIP. A FEW FLURRIES MAY BE ENCOUNTERED AS FAR EAST AS THE BLUE RIDGE. IT WILL BECOME BREEZY THIS AFTERNOON AHEAD OF THE FRONT...SOUTHWEST WINDS INCREASING TO 10 TO 15 MPH. PASSAGE OF THE FRONT WILL BRING A WIND SHIFT TO THE WEST...THEN TRENDING MORE TO THE NORTHWEST LATE TONIGHT. THE INCREASING PRESSURE GRADIENT ASSOCIATED WITH THE STRENGTHENING AREA OF LOW PRESSURE OVER NEW ENGLAND WILL RESULT IN INCREASING WIND SPEEDS OVERNIGHT WITH SURFACE GUSTS APPROACHING 40 MPH ACROSS THE RIDGES BY DAYBREAK FRIDAY. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... AS OF 400 AM EST THURSDAY... WINDY AND COLD IS ON THE WAY FOR FRIDAY AS A COLD FRONT PUSH OUT INTO THE ATLANTIC OCEAN. SERIES OF SHORT WAVES SHARPENS UPPER TROF WITH A 500MB LOW CLOSING OFF OVER LONG ISLAND BY LATE FRIDAY. THE SECOND RE-ENFORCING SHOT OF MUCH COLDER 850MB AIR ARRIVES ON FRIDAY WITH A PUNCH. ALONG WITH THE COLD AIR ADVECTION...LOW LEVEL JET COMES AROUND TO THE NORTHWEST STARTING LATE THURSDAY NIGHT WITH SPEEDS OF AROUND 50 KNOTS INTO FRIDAY NIGHT. STRONG WINDS WILL BE ALONG THE SOUTHERN APPALACHIANS FRIDAY...THEN ROTATE TO THE NORTHERN APPALACHIANS ON FRIDAY NIGHT AS THE SURFACE LOW DEEPENS OFF THE NEW ENGLAND COAST. 6 HOUR PRESSURE RISES...BUFKIT SOUNDINGS...AND LOW LEVEL JET SUPPORT THE POTENTIAL FOR ADVISORY LEVEL WINDS ALONG THE BLUE RIDGE BEHIND THE COLD FRONT FRIDAY INTO FRIDAY EVENING. WITH TIMING BEING THE THIRD AND FOURTH PERIODS...THIS WIND THREAT WILL REMAIN HIGHLIGHTED IN HAZARDOUS WEATHER OUTLOOK AS COORDINATED WITH WBC AND GSP. WITH THE STRONG NORTHWEST FLOW...SNOW SHOWERS AND SNOW FLURRIES WILL CONTINUE FRIDAY IN THE WEST ESPECIALLY DURING THE MORNING. INCREASED POPS ALONG THE WESTERN SLOPES IN GREENBRIER COUNTY FRIDAY MORNING. CLEARING EXPECTED EAST OF THE BLUE RIDGE FRIDAY. THE REMAINING LOW LEVEL MOISTURE ON THE WESTERN SLOPES ON FRIDAY ERODES AS THE DAY PROGRESSES. USED A NON-DIURNAL TEMPERATURE CURVE FOR FRIDAY WITH HIGHS FROM THE LOWER 20S IN THE NORTHWEST TO THE LOWER 40S IN THE SOUTHEAST. HIGH PRESSURE SLOWLY BUILDS EAST INTO OUR AREA FRIDAY NIGHT. LOW TEMPERATURES FRIDAY NIGHT INTO SATURDAY MORNING WILL RANGE FROM THE SINGLE DIGITS IN THE MOUNTAINS TO THE LOWER 20S IN THE PIEDMONT. A WEAK SURFACE HIGH PRESSURE SLIDE SOUTHEAST SATURDAY. THIS WILL ALLOW SURFACE AND LOW LEVEL WINDS TO DIMINISH AND BACK MORE TO THE WEST. LOOK FOR INCREASING CLOUDS SATURDAY AS MOISTURE SPREAD EAST FROM THE SOUTHERN PLAINS SYSTEM. HIGH TEMPERATURES SATURDAY WILL RANGE FROM THE MID 20S IN THE NORTHWEST TO THE LOWER AND MID 40S IN THE SOUTHEAST. WITH BOTH THE GFS AND ECMWF A LITTLE SLOWER WITH MOISTURE...DECIDE TO HOLD BACK LIGHT POPS TO LATE SATURDAY NIGHT. LOWS SATURDAY NIGHT WILL GENERALLY BE FROM AROUND 20 DEGREES TO AROUND THE FREEZING MARK. AS THE HIGH PRESSURE PUSHES TO OUR EAST AND WAVES OF LOW PRESSURE RIDE ALONG AN APPROACHING COLD FRONT...EXPECT OUR CHANCES FOR PRECIPITATION TO INCREASE FOR SUNDAY AND SUNDAY NIGHT. PTYPE WILL BE WINTRY MIXTURE AT THE START THEN EXPECT A MOSTLY RAIN EVENT...THEN BACK TO SOME UPSLOPE SNOW SHOWERS WEST OF THE BLUE RIDGE AS WE GET ON THE BACK SIDE OF THE LOW INTO MONDAY. THE PLACEMENT OF THE LOW CENTER AND ITS TRACK WHETHER SOUTH OR WEST OF US HAS BEEN PROBLEMATIC FOR OUR FORECAST WITH MODEL DIFFERENCES. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 400 AM EST THURSDAY... COLD HIGH PRESSURE THEN BUILDS AS UPSLOPE SNOW SHOWERS WIND DOWN MONDAY INTO MONDAY NIGHT AND...AFTER A VERY COLD MORNING...QUIET WEATHER SHOULD BE THE RULE FOR TUESDAY. HEADING INTO WEDNESDAY...THE REMNANTS OF THE CLOSED UPPER LOW WILL BE EJECTING TOWARD US AS THE NRN AND SRN STREAMS PHASE. LONG RANGE MODELS ARE INDICATING THE POTENTIAL FOR A /MILLER A/ TYPE LOW TO DEVELOP OVER THE GULF COAST WEDNESDAY AND TRACK THROUGH THE SOUTHEAST US AND OFF THE MIDDLE ATLANTIC COAST WEDNESDAY NIGHT. TEMPERATURES ARE CURRENTLY EXPECTED TO BE BORDERLINE AT BEST ACROSS OUR AREA FOR WINTRY WEATHER. NOTHING TO GET EXCITED ABOUT AT THIS POINT...BUT WE WILL BE WATCHING TO SEE HOW LATER MODEL RUNS HANDLE THE EVOLUTION OF THIS SYSTEM. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 700 AM EST THURSDAY... HIGH CLOUDS WILL INCREASE FROM THE WEST THIS MORNING...MAINLY ACROSS NORTHERN PORTIONS OF THE CWA...IN ADVANCE OF AN ALBERTA CLIPPER...THE MAIN DYNAMICS OF WHICH WILL REMAIN NORTH OF OUR CWA. ALL CLOUD BASES SHOULD REMAIN VFR THROUGH NOON TODAY. NOT EXPECTING ANY PROBLEMS WITH VISIBILITY THIS MORNING AS THE SFC AIR MASS IS VERY DRY. BY THIS EVENING...THE CLIPPER WILL RACE ACROSS THE GREAT LAKES INTO WESTERN NEW YORK/QUEBEC. A NARROW BAND OF PRECIPITATION WILL ACCOMPANY THE COLD FRONT WHICH TRAILS SOUTH FROM THE AREA OF LOW PRESSURE. THE MOISTURE IS EXPECTED TO DRY UP AS IT CROSSES THE MOUNTAINS THIS AFTERNOON. SHOWERS WILL BE FOUND MAINLY NORTH OF U.S. 460 AND WEST OF I-81...WITH ONLY SPRINKLES EXPECTED TO THE SOUTH AND EAST. PRECIPITATION WILL BE FALLING FROM MID-BASED CLOUDS AND LIGHT...SO VISIBILITY WILL NOT BE AN ISSUE...EXCEPT POSSIBLY AT BLF/LWB WHERE DYNAMICS/LIFT ARE BETTER AND CLOUD CIGS COULD LOWER TO LOW END VFR OR HIGH END MVFR DURING THIS ACTIVITY...POTENTIALLY REDUCING VSBY THEN TO MVFR CATEGORY IN -SHRA. SFC/850MB TEMPS SHOULD REMAIN WARM ENOUGH FOR ALL LIQUID THROUGH 00Z/7PM THIS EVENING. BEHIND THE COLD FRONT...ROUGHLY FROM 02Z/9PM FAR WEST TO AFT 06Z/1AM FRIDAY FAR EASTERN PIEDMONT...THERE WILL BE AN INCREASING THREAT FOR MOUNTAIN SNOW SHOWERS AND FLURRIES...INCLUDING LWB/BLF. CIGS WILL ALSO DROP INTO THE MVFR RANGE AND VISIBILITY POTENTIALLY INTO THE MVFR RANGE AT TIMES IN THE MOUNTAINS. EAST OF THE MOUNTAINS...DOWNSLOPE DRYING WILL RESULT IN LESS CLOUD COVER AND LITTLE OR NO PRECIP. WINDS WILL BECOME THE MAIN CONCERN BY FRIDAY AS THE CLIPPER MOVES EAST OF THE REGION AND VERY STRONG NORTHWEST WINDS DEVELOP IN ITS WAKE. WINDS BY FRIDAY MORNING ARE EXPECTED TO BE OUT OF THE WNW 12-18KTS WITH GUSTS 25-30KTS THROUGHOUT THE DAY FRIDAY. EXTENDED DISCUSSION... MVFR CIGS MAY LINGER OVER THE MOUNTAINS INTO FRIDAY NIGHT WITH STRONG NW WINDS...AFTER WHICH LOOK FOR IMPROVING CONDITIONS WITH VFR EXPECTED SATURDAY AND SATURDAY NIGHT COURTESY OF HIGH PRESSURE PASSING OVERHEAD THE FIRST HALF OF THE WEEKEND. THE NEXT LOW PRESSURE SYSTEM HEADING OUT OF THE SW STATES WILL BRING A RETURN OF CLOUDS AND SOME PRECIPITATION ON SUNDAY AND MONDAY WITH WIDESPREAD MVFR TO IFR LIKELY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON EST FRIDAY FOR WVZ508. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...KK LONG TERM...MBS AVIATION...PM

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