Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 211419 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 919 AM EST SUN DEC 21 2014 .SYNOPSIS... HIGH PRESSURE OVER THE OHIO VALLEY WILL MOVE EAST TODAY AND WEDGE DOWN THE EAST SIDE OF THE APPALACHIANS TONIGHT. LOW PRESSURE WILL REMAIN ALONG THE CAROLINA COAST TODAY THROUGH MONDAY. A VERY STRONG COLD FRONT WILL MOVE THROUGH THE REGION ON WEDNESDAY...BRINGING RAIN AND GUSTY WINDS TO THE AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM EST... QUIET WEATHER IN THE FORECAST FOR TODAY. WATER VAPOR LOOP SHOWS DRY AIR MOVING OVER THE SHALLOW LOW LEVEL MOISTURE OVER THE AREA AND ALREADY SEEING SOME CLEARING WORKING IN FROM THE WEST. EXPECT THIS TREND WILL CONTINUE ACROSS THE NORTH AND DOWN THROUGH THE PIEDMONT...WITH CLOUDS LINGERING LONGEST ALONG AND WEST OF THE BLUE RIDGE FROM ROA SOUTH. TEMPS RUNNING A BIT AHEAD OF GRIDS SO WILL BUMP FORECAST MAX UP JUST A BIT FOR TODAY AND AFTERNOON READINGS SHOULD APPROACH 50F FOR NC PIEDMONT AND SOUTHSIDE VA. ...PREVIOUS AFD... SURFACE HIGH PRESSURE OVER THE OHIO VALLEY MOVES EAST TODAY THEN WEDGES DOWN THE EAST SIDE OF THE APPALACHIANS TONIGHT. BY LATE TONIGHT LOW PRESSURE WILL DEVELOP ALONG THE SOUTHEAST COAST AND HELP RE-ENFORCE THE WEDGE. CLOUDS FILL BACK IN FROM THE SOUTH TONIGHT. MODELS SIMILAR WITH TIMING OF ISENTROPIC LIFT AND UPSLOPE SOUTHEAST WINDS...BRINGING THE PROBABILITY OF PRECIPITATION INTO THE SOUTHERN COUNTY WARNING AREA AFTER MIDNIGHT...THEN SPREADING NORTH THROUGH 12Z/7AM MONDAY. STAYED CLOSE TO MAV GUIDANCE FOR TEMPERATURES THROUGH THE PERIOD. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 330 AM EST SUNDAY... FOR MONDAY...AN UPPER LEVEL TROUGH APPROACHING FROM THE WEST WILL SUPPORT LOW PRESSURE DEEPENING OFF THE CAROLINA COAST...WHILE HIGH PRESSURE WILL BE WEDGED AGAINST THE EASTERN FACE OF THE APPALACHIANS. MOISTURE RADIATING INLAND FROM THE LOW WILL ALREADY BE SPREADING ACROSS OUR AREA BY SUNRISE...AND FORECAST TEMPERATURE PROFILES SUPPORT A MIXTURE OF SLEET AND FREEZING RAIN ACROSS THE MOUNTAINS THROUGHOUT THE DAY...AS RAIN FALLING FROM THE WARM AIR RIDING IN ALOFT FROM THE SOUTH FALLS THROUGH THE COLD AIR BEING DRAWN IN BY THE HIGH PRESSURE FROM THE NORTHEAST. EAST OF THE MOUNTAINS...SURFACE TEMPERATURES ARE EXPECTED TO BE WARM ENOUGH THAT ALL PRECIPITATION WILL REMAIN LIQUID. BEST CHANCES FOR PRECIPITATION WILL BE EAST OF THE BLUE RIDGE...CLOSER TO THE LOW PASSING ALONG THE COAST...WITH PRECIPITATION CHANCES DIMINISHING FURTHER WEST AS THE MOISTURE FIGHTS THE DRY AIR ALREADY IN PLACE. PRECIPITATION WILL BE MOST WIDESPREAD DURING THE MORNING AND AFTERNOON...AND WILL DECREASE BY EARLY EVENING AS THE COASTAL LOW BEGINS TO PUSH AWAY FROM THE AREA. STRONG NORTHEASTERLY FLOW AND WIDESPREAD PRECIPITATION WILL STRICTLY LIMIT HEATING THROUGH THE DAY...AND HAVE UNDERCUT MODEL GUIDANCE FOR TEMPERATURES...HOLDING HIGHS IN THE 30S AND LOW 40S MOST LOCATIONS. FOR TUESDAY...THE HIGH PRESSURE WEDGE WILL ONLY SLIGHTLY WEAKEN... BUT WILL DO SO SUFFICIENTLY TO SUPPORT WARMER TEMPERATURES...MAKING FOR RAIN ACROSS THE REGION...PERHAPS WITH A RESIDUAL AND ISOLATED POCKET OF LIGHT FREEZING RAIN IN THE MOUNTAINS. RAIN CHANCES WILL BEGIN TO INCREASE DURING THE EVENING AS A DEEP UPPER LEVEL TROUGH APPROACHES FROM THE SOUTHERN PLAINS...SUPPORTING DEVELOPMENT OF A LOW PRESSURE SYSTEM ALONG THE GULF COAST. THE LOW WILL LIFT NORTH INTO THE TENNESSEE VALLEY OVERNIGHT...RESULTING IN WIDESPREAD RAIN REACHING THE CENTRAL APPALACHIANS BEFORE SUNRISE WEDNESDAY. AS THE LOW LIFTS TOWARD THE GREAT LAKES ON CHRISTMAS EVE...IT WILL CONTINUE TO DEEPEN. WITH IT...THE LOW WILL DRAG A COLD FRONT EASTWARD...WHICH WILL ENTER OUR WESTERN MOST COUNTIES BY AROUND SUNSET. STRONG LOW LEVEL WINDS ASSOCIATED WITH THE LOW MAY REACH TO THE SURFACE AT TIMES...AND MAY RESULT IN SPORADIC TREE DAMAGE AND POWER OUTAGES. ALSO...WITH PRECIPITABLE WATER VALUES REACHING THE BALLPARK OF 1.2 INCHES...MAY SEE LOCALLY HEAVY RAIN AS THE COLD FRONT BEGINS TO PASS ACROSS THE AREA. THE COLD FRONT WILL PASS RAPIDLY EAST LATE CHRISTMAS EVE EVENING... AND MAY SEE A BRIEF SHOT OF STRONG WINDS IN THE WAKE OF THE FRONT...ESPECIALLY ALONG THE HIGHER RIDGES. PRECIPITATION WILL RAPIDLY DIMINISH HOWEVER AS DRIER AIR WORKS IN FROM THE WEST...RESULTING IN ONLY RESIDUAL UPSLOPE SHOWERS THAT WILL CHANGE OVER TO SNOW BY SUNRISE CHRISTMAS DAY. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 300 PM EST SATURDAY... WEST TO NORTHWEST UPPER FLOW WILL CONTINUE INTO THURSDAY WITH MOUNTAIN RAIN AND SNOW SHOWERS. HIGHS CHRISTMAS DAY WILL VARY FROM AROUND 30 DEGREES IN THE NORTHWEST MOUNTAINS TO AROUND 50 DEGREES IN PIEDMONT. WINDS WILL BE QUITE STRONG ON THURSDAY AS A 50 TO 55 KNOT 850MB JET PIVOTS ACROSS THE REGION. AT THIS TIME...LOOKS LIKE VALUES SHOULD REMAIN BELOW WIND ADVISORY LEVELS. AS HIGH PRESSURE SLIDES OFF THE COAST...DRY WEATHER IS EXPECTED CHRISTMAS NIGHT/THURSDAY NIGHT WITH LOW TEMPERATURES GENERALLY IN THE UPPER 20S AND LOWER 30S. THE UPPER FLOW SHIFTS TO THE SOUTHWEST FRIDAY INTO FRIDAY NIGHT AS TROF CURVES OUT IN THE CENTRAL US WITH SFC LOW PRESSURE DEVELOPING OVER THE MIDWEST WITH A FRONTAL BOUNDARY TRAILING SOUTH. HIGHS ON FRIDAY WILL VARY FROM THE LOWER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT. MOISTURE SLOWLY RETURN FRIDAY NIGHT INTO SATURDAY AS FRONTAL BOUNDARY APPROACHES. LOWS FRIDAY NIGHT DROP INTO THE LOWER AND MID 30S IN MOST LOCATIONS. A COLD FRONT MOVES ACROSS OUR REGION SATURDAY INTO SATURDAY NIGHT. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... AS OF 720 AM EST SUNDAY... LOW CLOUDS COVERED THE REGION OVERNIGHT. CEILINGS WERE MAINLY MVFR IN THE MOUNTAINS AND VFR ALONG AND EAST OF THE BLUE RIDGE. THE CLOUDS WERE CLEARING SLOWLY FROM WEST TO EAST WITH SATELLITE PICTURES SHOWING THE WESTERN EDGE VERY CLOSE TO KBLF. CLEARING WILL CONTINUE DURING THE DAY. A WEDGE OF HIGH PRESSURE WILL BUILD SOUTH DOWN THE EAST SLOPES OF THE APPALACHIANS TONIGHT AND WILL BE ENHANCED DUE TO LOW PRESSURE OFF THE CAROLINA COAST. RAIN WILL SPREAD FROM SOUTH TO NORTH AFTER 00Z/7PM. HIGH CONFIDENCE THAT KROA/KDAN/KBCB/KLYH WILL HAVE RAIN AFTER 06Z/1AM...BUT IT MAY BE AT THE END OF THE TAF PERIOD THAT THE PRECIPITATION REACHES KBLF AND KLWB. SOME FREEZING RAIN AND SLEET ARE POSSIBLE LATE TONIGHT...ESPECIALLY AT KLWB. CEILINGS WILL LOWER TO MVFR AS THE RAIN BEGINS. EXTENDED DISCUSSION... MONDAY AFTERNOON THROUGH TUESDAY...MVFR WITH SHOWERS. TUESDAY NIGHT AND WEDNESDAY...MVFR WITH SHOWERS AND THE PASSAGE OF A STRONG COLD FRONT. LLWS POSSIBLE AS WELL AS GUSTY SURFACE WINDS AHEAD OF THE FRONT AND FOLLOWING THE FRONT. WEDNESDAY NIGHT AND THURSDAY...GUSTY NORTHWEST WINDS. MVFR CLOUDS AND RAIN/SNOW SHOWERS IN THE MOUNTAINS. VFR CONDITIONS EAST OF THE BLUE RIDGE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/MBS SHORT TERM...NF LONG TERM...KK AVIATION...AMS

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