Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250546 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1246 AM EST TUE NOV 25 2014 .SYNOPSIS... A COLD FRONT WILL MOVE EAST ACROSS THE REGION TONIGHT. NORTHWEST FLOW BEHIND THE FRONT WILL BRING COLDER TEMPERATURES TUESDAY INTO WEDNESDAY. A STORM SYSTEM MOVING UP ALONG THE CAROLINA COAST WILL BRING THE NEXT ROUND OF PRECIPITATION FOR THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 930 PM EST MONDAY... SFC COLD FRONT IS ALONG THE SPINE OF THE APPALACHIANS AND IS SLOWLY INCHING ITS WAY EAST. COOLER/DRIER AIR LAGS WELL BEHIND FRONT...THUS AREAS ALONG AND EAST OF BLUE RIDGE LIKELY TO REMAIN MILD OVERNIGHT. BUMPED UP LOW TEMPS OVERNIGHT ACROSS SOUTHSIDE VA AND THE PIEDMONT OF NC TO ACCOUNT FOR THIS LAG. WARM/MOIST AIR ADVECTION AHEAD OF THE SFC FRONT IS ALSO RESULTING IN RISING DEWPOINTS ACROSS THE PIEDMONT...DANVILLES DEWPOINT CLIMBING FROM 53 TO 60 SINCE SUNSET. THESE DEWPOINTS WILL LIKELY REMAIN ELEVATED UNTIL FROPA LATE TONIGHT...THUS FAVORING WARMER T-MINS. LATEST SAT PIX INDICATES THICKENING CLOUDS OVER THE CAROLINAS...THIS UPPER LEVEL MOISTURE ASSOCIATED WITH THE UPPER JET. MODEL RH FIELDS AT 250 MB SUGGEST ALL AREAS EAST OF THE BLUE RIDGE WILL DEVELOP LAYER OF HIGH LEVEL CIRRUS...WHICH WILL BECOME BKN-OVC DURING THE OVERNIGHT. INCREASED CLOUD COVER TO ACCOUNT FOR THIS DEVELOPING CIRRUS SHIELD. LIGHT RAIN IS CURRENTLY FALLING FROM RALEIGH NC SOUTHWARD INTO SOUTH CAROLINA...PRIMARILY ALONG I95 CORRIDOR. MODELS KEEP THIS PRECIP CONFINED TO AREAS JUST SOUTHEAST OF OUR CWA IN THE NEAR TERM. SURFACE COLD FRONT IS FORECAST TO MOVE EAST TO ALONG THE COAST ON TUESDAY...COOLER/DRIER AIR TRICKLING INTO THE FORECAST AREA VIA A LIGHT NORTHWEST WIND. HIGH PRESSURE WILL BUILD EAST OUT OF THE OHIO VALLEY DURING THE DAY TUESDAY...ENSURING A DRY DAY. ANY SUN HOWEVER WILL BE FILTERING THROUGH HIGH CLOUDS FOR MOST OF THE AREA...JET STREAM CIRRUS REMAINING OVERHEAD. HIGH TEMPERATURES WILL RANGE FROM THE 40S IN THE WESTERN MOUNTAINS TO AROUND 60 ACROSS THE SOUTHEAST. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... AS OF 335 PM EST MONDAY... TWO STRONG SHORT WAVES COME THROUGH THE LONG WAVE TROF OVER THE EASTERN UNITED STATES THIS TIME FRAME. THE FIRST CROSSES THE FORECAST AREA FROM THE SOUTHERN STREAM ON WEDNESDAY AND THE NEXT FROM THE NORTHERN STREAM ON WEDNESDAY NIGHT. IN ADDITION TO THE POSITIVE VORTICITY ADVECTION ON WEDNESDAY THERE WILL ALSO BE GOOD Q-VECTOR FORCING AND UPPER DIFFLUENCE. WILL BE INCREASING PROBABILITY OF PRECIPITATION FOR LATE TUESDAY NIGHT INTO WEDNESDAY NIGHT ACROSS THE SOUTHERN COUNTY WARNING AREA. MODELS HAVE COME INTO BETTER AGREEMENT AND HAVE TRENDED WEST WITH TRACK OF THE 850MB AND SURFACE LOWS. 12Z NAM IS COLDER WITH THE TEMPERATURE PROFILE ON TUESDAY NIGHT AND WEDNESDAY THAN 12Z GFS. AT THIS TIME WILL BE TAKING A BLEND. LOWEST LAYERS DROP BELOW FREEZING IN THE WEST LATE TUESDAY NIGHT WITH BUFKIT WAS SHOWING PERIODS OF ISOTHERMAL TEMPERATURES. PRECIPITATION TYPE WILL ALSO BE DEPENDENT ON INTENSITY AND RATES. TEMPERATURES WEDNESDAY WILL BE NEARLY STEADY AND 10 TO 15 DEGREES BELOW NORMAL. SOME OF COOLING IS EXPECTED AS THE TEMPERATURE DROPS TOWARD WET BULB VALUES...BUT EVEN SO...ONLY HIGHER ELEVATIONS OF THE BLUE RIDGE AND AREAS WEST WILL HAVE SURFACE TEMPERATURES COLD ENOUGH FOR SNOW ACCUMULATION. COMBINING THE PRECIPITATION AMOUNTS AND SNOWFALL FROM THE TUESDAY NIGHT AND WEDNESDAY SYSTEM WITH THE SNOWFALL FROM THE CLIPPER ON WEDNESDAY NIGHT MAY PUSH SNOWFALL TOTALS IN SOME LOCATIONS ABOVE WARNING CRITERIA. CHALLENGING TO SAY AT THIS POINT HOW WIDESPREAD THIS WILL BE AND HOW MUCH OF A GAP THERE WILL BE FROM THE TIME THE COASTAL LOW PRECIPITATION EXITS TO THE TIME THE SNOW WITH THE CLIPPER COMES THROUGH. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 130 PM EST MONDAY... HIGH PRESSURE WILL KEEP THE REGION DRY ON FRIDAY AND THROUGH THE START OF THE UPCOMING WEEKEND. BY SUNDAY...AND TO A SLIGHTLY BETTER DEGREE ON MONDAY...THE CENTER OF THE HIGH WILL SHIFT TO THE COAST...AND A COLD FRONT WILL BECOME STALLED OVER THE OHIO VALLEY. THIS WILL SET THE REGION UP FOR A SOUTHWEST FLOW...WARM AIR ADVECTION PATTERN. LIFT WITHIN THE VICINITY OF THE STALLED FRONT WILL ALLOW FOR LIGHT PRECIPITATION TO SLOWLY INCREASE IN COVERAGE FROM NORTHWEST TO SOUTHEAST AS WE HEAD FROM SUNDAY INTO MONDAY. THERE MAY BE A PRECIPITATION TYPE ISSUE THESE TWO DAYS WHERE SURFACE TEMPERATURES ARE BELOW OR HOVER AROUND THE FREEZING MARK DURING THE LATE OVERNIGHT AND EARLY MORNING HOURS AND A STRONG WARM NOSE EXISTS ALOFT. AT THIS TIME...WILL HAVE A RAIN VERSUS FREEZING RAIN FORECAST...WITH VERY LITTLE IN THE WAY OF FREEZING RAIN COVERAGE AND ALSO IN TIME DURATION. TEMPERATURES THROUGH THIS PERIOD WILL TREND MILDER EACH DAY SO THAT BY MONDAY UPPER 50S TO LOWER 60S WILL BE COMMON ACROSS THE REGION FOR HIGH TEMPERATURES. THIS CONTRASTS TO HIGHS IN THE MID 30S TO NEAR 40 ACROSS THE MOUNTAINS AND LOW TO MID 40S ACROSS THE PIEDMONT ON FRIDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1235 AM EST TUESDAY... SURFACE COLD FRONT IS CURRENTLY MOVING ACROSS THE MOUNTAINS...BUT FORWARD SPEED HAS BEEN SLOWING WITH TIME PER WIND FLOW ALOFT BECOMING PARALLEL WITH FRONT. THIS FRONT IS EXPECTED TO MOVE EAST OF THE MOUNTAINS DURING THE OVERNIGHT...THEN TO ALONG THE COAST TUESDAY AFTERNOON. WINDS BEHIND THE FRONT WILL SHIFT TO THE WEST INITIALLY...THEN TREND MORE NORTHERLY WITH TIME DURING THE DAY TUESDAY AS HIGH PRESSURE BUILDS INTO THE FORECAST AREA FROM THE NORTHWEST. CLOUD BASES THROUGH THE 24 HR TAF PERIOD ARE EXPECTED BE VFR EXCEPT ACROSS THE FAR SOUTHEAST AROUND KDAN WHERE A PERIOD OF MVFR IN LOWER STRATO-CU COULD OCCUR THROUGH DAYBREAK TUESDAY. MEDIUM TO HIGH FCST CONFIDENCE DURING THE TAF PERIOD. EXTENDED DISCUSSION... A DEVELOPING STORM SYSTEM IS EXPECTED TO MOVE UP THE SOUTHEAST COAST BY EARLY WEDNESDAY WHICH MAY BRING WINTRY PRECIP TO THE AREA ALONG WITH SUB VFR AT ALL SITES. LOOKS LIKE FLIGHTS WILL BE IMPACTED GREATLY ACROSS THE MID ATLANTIC INTO THE NORTHEAST WITH THIS SYSTEM WITH WITH WIDESPREAD PRECIPITATION. FOR THE CENTRAL APPALACHIANS BEST CHC FOR SUB VFR WILL OCCUR WED INTO EARLY THANKSGIVING BEFORE HIGH PRESSURE WORKS IN FROM THE WEST. WESTERN SLOPES...VCNTY OF BLF/LWB...MAY KEEP LOWER CIGS UNTIL FRIDAY AFTERNOON. && .CLIMATE... NO RECORD HIGH TEMPERATURES OCCURRED YESTERDAY...HOWEVER DANVILLE SET A NEW RECORD HIGH MINIMUM TEMPERATURE OF 57 DEGREES FOR THE 24TH. THIS BREAKS THE OLD RECORD HIGH MINIMUM FOR DANVILLE OF 56 DEGREES FROM 2004. && .EQUIPMENT... AS OF 330 AM EST MONDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/KK NEAR TERM...KK/PM SHORT TERM...AMS LONG TERM...DS AVIATION...JH/KK/WP CLIMATE...JH EQUIPMENT...JH

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