Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270056 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 756 PM EST THU FEB 26 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA OVERNIGHT. COLD HIGH PRESSURE WILL BUILD IN BEHIND IT...AND BE ACROSS OUR AREA THROUGH SATURDAY. SUNDAY THROUGH AT LEAST THE MIDDLE OF NEXT WEEK...A SERIES OF LOW PRESSURE SYSTEMS HAVE THE POTENTIAL TO BRINGING MORE ROUNDS OF PRECIPITATION TO OUR AREA...AND TEMPERATURES ON AVERAGE WILL BE MILDER THAN THIS WEEK. && .NEAR TERM /THROUGH FRIDAY/...
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AS OF 715 PM EST THURSDAY... NOT SEEING ANYTHING ON RADAR IN OUR AREA NOR IN OBSERVATIONS. MESOANALYSIS DEPICTS WEAK CONVERGENCE WITH THE SFC TROUGH...THEREFORE LOWERED THREAT OF PRECIP THIS EVENING...THOUGH FORECAST SOUNDINGS IN THE EAST SUGGEST POTENTIAL FOR A LITTLE DZ/FZDZ. NEXT UPSTREAM SHORTWAVE WILL BE SHIFTING TOWARD THE WV MTNS OVERNIGHT AND UPSLOPE SNOW SHOWERS STILL LOOK GOOD...THOUGH THE OVERALL MOISTURE PROFILE STILL SUGGESTS LOW THREAT OF ANY ACCUMULATION OVER 1-2 INCHES IN THE HIGHER TERRAIN OF WRN GREENBRIER. PREVIOUS VALID DISCUSSION... A WINTER WEATHER ADVISORY REMAINS FOR BLACK ICE FOR OUR NORTH CAROLINA COUNTIES VIA OUR WORKING POLICY WITH THAT STATE. FOR SOUTHWEST VIRGINIA AND SOUTHEAST WEST VIRGINIA...A SPECIAL WEATHER STATEMENT HIGHLIGHTING THE BLACK ICE WAS ISSUED. EXPECT INCREASING NORTHWEST WINDS...THAT WILL BE FULLY REALIZED DURING THE DAY FRIDAY AFTER THE BREAKING OF THE NOCTURNAL INVERSION. COLDER AND LOWER DEW POINT AIR WILL WORK ITS WAY INTO THE AREA OVERNIGHT. A WEAK DISTURBANCE WILL RIDE PIGGY BACK WITH THE FRONT...AND BRING THE POTENTIAL FOR SOME LIGHT PRECIPITATION TO AREAS EAST OF THE CREST OF THE BLUE RIDGE...WHERE NORMAL THE IMPACT OF DOWNSLOPING WIND WOULD LIMIT IF NOT COMPLETELY RULE OUT THE POTENTIAL FOR PRECIPITATION. THIS DISTURBANCE IS EXPECTED TO BRING A SLIGHT CHANCE OF PRECIPITATION TO AREAS NEAR THE NC/VA BORDER EAST OF THE FOOTHILLS. THIS SATURATION WITHIN THIS AREA WILL BE LIMITED TO A NARROW BAND BETWEEN 850 MB AND THE SURFACE. THE COLDEST TEMPERATURE WITHIN THIS BAND WILL RANGE FROM ROUGHLY -8 TO -11 C. WITH VERY LIMITED OPPORTUNITIES FOR DENDRITIC GROWTH...THE PRECIPITATION FOR THIS PART OF THE FORECAST AREA IS MORE LIKELY TO BE FREEZING RAIN...RATHER THAN SNOW. ALTHOUGH WITH -10 TO -11 C AS A COLD LIMIT...WE CANNOT RULE OUT AT LEAST A LITTLE LIGHT SNOW WITHIN THE MIX. ON FRIDAY...NORTHWEST FLOW ALOFT AND INCREASING NORTHWEST SURFACE WINDS WILL HAVE THE IMPACT OF A DOWNSLOPING COMPONENT THAT WILL GRADUALLY ERODE THE CLOUD COVER EAST OF THE CREST OF THE BLUE RIDGE. CLOUDS ACROSS THE MOUNTAINS WILL BE LESS LIKELY TO ERODE AS FAST...AND UPSLOPE SNOW SHOWERS WILL CONTINUE...BUT TREND TOWARDS DECREASING COVERAGE AND INTENSITY. HIGH TEMPERATURES TOMORROW WILL RANGE FROM THE LOW TO MID 20S ACROSS THE MOUNTAINS WITH AROUND 30 TO UPPER 30S ACROSS THE PIEDMONT.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... AS OF 320 PM EST THURSDAY... ZONAL PATTERN AT 500 MB THROUGH SUNDAY WITH NO SIGNIFICANT SHORT WAVES THROUGH THE PERIOD. MID AND HIGH LEVEL CLOUDS MOVE IN FROM THE WEST ON FRIDAY NIGHT AND SATURDAY. TRULY DEEP MOISTURE FILLS IN ACROSS THE FORECAST AREA ON SATURDAY NIGHT AND SUNDAY. FRIDAY NIGHT HAS THE POTENTIAL TO HAVE MINIMUM TEMPERATURES BELOW GUIDANCE DUE TO SNOW COVER AND LIGHT WINDS. HOWEVER...CLOUD COVER MAY COUNTERACT THAT COOLING. LEANED TOWARD BIAS CORRECTED ECMWF GUIDANCE FOR LOWS ON FRIDAY NIGHT THEN MAV NUMBERS FOR SATURDAY THROUGH SUNDAY. HIGH PRESSURE THAT WILL BE CENTERED OVER THE OHIO VALLEY ON FRIDAY NIGHT WILL MOVE EAST AND WEDGE DOWN THE EAST SIDE OF THE APPALACHIANS ON SATURDAY AND SUNDAY. SFC AND LOW LEVEL WINDS WILL HAVE AND EASTERLY COMPONENT BUT AT 850MB THE HIGH IS OFF THE SOUTHEAST COAST AND FLOW AROUND THE HIGH BRINGS MOISTURE RIGHT OUT OF THE GULF AND ADVECTS WARMER TEMPERATURES INTO THE REGION. 850MB TEMPERATURES RISE ABOVE ZERO ON SATURDAY NIGHT AND SUNDAY. THE NAM IS MUCH FASTER THAN THE GFS/ECMWF BRINGING PRECIPITATION BACK INTO THE COUNTY WARNING AREA ON SUNDAY. WILL KEEP BEST CHANCE OF PRECIPITATION IN THE WESTERN COUNTY WARNING AREA LATE ON SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 315 PM EST THURSDAY... SHOWER ACTIVITY WILL INCREASE SUNDAY NIGHT AS ANOTHER COLD FRONT APPROACHES THE REGION FROM THE WEST. INCREASED CLOUD COVER AND SOUTHWESTERLY WINDS WILL MAINTAIN WARMER OVERNIGHT TEMPERATURES COMPARED TO PREVIOUS NIGHTS...AND THEREFORE EXPECT MAINLY RAIN SOUTH OF THE INTERSTATE 64 CORRIDOR...POSSIBLY BECOMING A WINTRY MIX TOWARD SUNRISE MONDAY AS TEMPERATURES FALL NEAR FREEZING. ALONG AND NORTH OF INTERSTATE 64...EXPECT POCKETS OF FREEZING RAIN OR SLEET TO DEVELOP. SOUTHWESTERLY WINDS WILL ALLOW FOR SIGNIFICANTLY WARMER TEMPERATURES FOR MONDAY...WITH TEMPERATURES RANGING FROM THE MID 40S ACROSS SOUTHEAST WEST VIRGINIA TO THE MID 50S ACROSS THE SOUTHSIDE. A COLD FRONT WILL PASS ACROSS THE REGION DURING THE AFTERNOON...BRINGING A NORTHWESTERLY WIND SHIFT AND AN INCREASE IN RAIN SHOWER ACTIVITY ALONG THE BOUNDARY. SHOWERS WILL THEN DIMINISH IN COVERAGE DURING THE EVENING IN THE DOWNSLOPE WINDFLOW...WITH A FEW SHOWERS LINGERING ACROSS THE WESTERN SLOPES FROM WEST VIRGINIA INTO NORTHERN NORTH CAROLINA. HIGH PRESSURE WILL BUILD ACROSS THE SOUTHERN GREAT LAKES MONDAY EVENING...EVENTUALLY CROSSING TO NEW ENGLAND...WHERE IT WILL THEN BUILD SOUTHWARD ACROSS THE MID ATLANTIC BY TUESDAY MORNING. ANOTHER DEEPER LOW PRESSURE SYSTEM WILL DEVELOP OVER THE PLAINS ON TUESDAY...AND PUSH RAPIDLY NORTHEAST TOWARD THE GREAT LAKES. COLD SURFACE TEMPERATURES PROVIDED BY HIGH PRESSURE COMBINED WITH THE WARM AIR ALOFT AND DEEP MOISTURE AS PROVIDED BY THE LOW PRESSURE SYSTEM TO OUR WEST WOULD MAKE FOR A CHANCE FOR FREEZING RAIN FROM THE INTERSTATE 64 CORRIDOR...POSSIBLY AS FAR SOUTH AS THE NEW RIVER VALLEY. THE LOW PRESSURE SYSTEM WILL DRAG A COLD FRONT ACROSS OUR AREA ON WEDNESDAY...POTENTIALLY BRINGING A ROUND OF LOCALLY HEAVY RAIN TO THE MOUNTAINS. CHILLY ARCTIC AIR WILL BUILD INTO THE REGION BEHIND THE COLD FRONT. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... AS OF 715 PM EST THURSDAY... RADAR IS CLEAR THIS EVENING...HOWEVER A BLANKET OF LOW CLOUDS REMAINS IN PLACE ACROSS THE REGION...WITH CEILINGS RANGING FROM 4KFT AND UP EAST OF THE BLUE RIDGE...TO BETWEEN 1KFT AND 3KFT ACROSS THE MOUNTAINS. OVERNIGHT...A WEAK COLD FRONT WILL CROSS THE AREA...WITH ANOTHER ROUND OF COLD CANADIAN HIGH PRESSURE BUILDING IN ITS WAKE. MAY SEE A REDEVELOPMENT OF SPOTTY LIGHT SNOW SHOWERS ACROSS THE RIDGES OF SOUTHEAST WEST VIRGINIA BEHIND THE FRONT...AFFECTING KBLF/KLWB... POSSIBLY KBCB WITH OCCASIONAL FLURRIES...BUT REDUCTIONS IN VISIBILITY SHOULD NOT BE LONG LIVED. CEILINGS ACROSS THE AREA WILL TREND TO IFR LEVELS. ON FRIDAY...OCCASIONAL UPSLOPE SNOW SHOWERS WILL CONTINUE...BUT TREND LESS IN COVERAGE AND INTENSITY. THE NORTHWEST FLOW WILL START MIXING TO THE SURFACE SO THAT A PREVAILING 10 KT WIND WILL BE COMMON ACROSS THE MOUNTAINS WITH 5 TO 10 KT COMMON ACROSS THE PIEDMONT. THE DOWNSLOPING AFFECT WILL YIELD A TREND TOWARD DECREASING CLOUDS ACROSS THE PIEDMONT BY MIDDAY. FRIDAY AFTERNOON AND EVENING...MVFR CLOUDS ACROSS THE MOUNTAINS WILL DECREASE IN COVERAGE AND SNOW SHOWERS WILL DWINDLE TO FLURRIES. VFR COLD HIGH PRESSURE WILL PREVAIL ON SATURDAY. SUNDAY INTO MONDAY...OUR NEXT WEATHER SYSTEM WILL MOVE THROUGH THE AREA. CONFIDENCE IS LOW CONCERNING THE EXACT DETAILS ON TIMING AND PRECIP TYPE. HOWEVER...IT IS PROBABLE THAT THIS TIME PERIOD WILL BE ONE WITH SUB-VFR CONDITIONS FOR MANY PARTS OF THE AREA. ON THE HEELS OF THE SUNDAY/MONDAY SYSTEM WILL BE YET ANOTHER POTENTIALLY POTENT SYSTEM THAT MAY IMPACT ALL OR PARTS OF THE REGION LATE MONDAY NIGHT INTO AND THROUGH TUESDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR NCZ001-002- 018. WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR NCZ003>006- 019-020. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS/WP SHORT TERM...AMS LONG TERM...NF AVIATION...DS/NF

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