Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 261407 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1007 AM EDT THU MAR 26 2015 .SYNOPSIS... A COLD FRONT TRAILED FROM THE GREAT LAKES TO A LOW OVER THE SOUTHERN PLAINS EARLY THIS MORNING. THIS LOW WILL TRACK NORTHEAST AND WILL PUSH A STRONG COLD FRONT THROUGH THE AREA TONIGHT. MUCH COLDER AIR WILL BE MOVING IN BEHIND THE COLD FRONT FOR THIS WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1007 AM EDT THURSDAY... ADJUSTED CLOUD COVER THIS MORNING INTO THIS AFTERNOON TO BETTER CAPTURE SUNSHINE NOTED ON THIS MORNINGS SATELLITE IMAGES. USED A BLEND OF CANDIAN AND HRRR FOR CLOUD COVER INTO THE AFTERNOON. MODIFIED TEMPERATURES FOR THIS MORNING WITH LATEST SFC OBS AND MODEL TRENDS. LEANED TOWARDS THE WARM MOS FOR LATE MORNING WITH THE SUNSHINE IN THE WEST. DECREASED POPS FOR THIS MORNING AND ADJUSTED THEM TOWARDS A BLEND OF THE NAM AND HRRR INTO THIS AFTERNOON. WITH MOST OF THE CONVECTION NOT RETURNING TO AFTER 21Z THIS AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY AND PRECEDE A COLD FRONT THIS AFTERNOON INTO TONIGHT. TIMING OF FRONT LOOKS TO BE BETWEEN 23Z AND 05Z. THE CAPE LOOKED MARGINAL/WEAK THIS AFTERNOON BECAUSE OF WARM LAYER AT 700 MB. AS OF 13Z DAY ONE CONVECTION OUTLOOK STILL HAS OUR REGION IN THE GENERAL THUNDERSTORM AREA WITH THE MRGL TO OUR EAST ALONG THE COASTAL PLAINS OF VIRGINIA AND NORTH CAROLINA. MORE CHANGES LATER THIS MORNING. AS OF 430 AM EDT THURSDAY... PERSISTENT WEDGE REMAINED IN PLACE EARLY THIS MORNING. BAND OF SHOWERS AND ISOLATED THUNDERSTORMS TRACKING TOWARD DANVILLE AND SOUTHEAST COUNTIES OF THE FORECAST AREA WILL BE ELEVATED OVER A SHALLOW BUT STRONG INVERSION. JUST ABOVE THE INVERSION LEVEL...STRATUS HAD FORMED IN ALL BUT THE FAR WESTERN COUNTY WARNING AREA. HIGHER ELEVATIONS WERE IN THE CLOUDS WITH DRIZZLE AND FOG REPORTED. LATEST HRRR AND WRF RUNS HAD BEST PROBABILITY OF SHOWERS THIS MORNING IN SOUTHEAST HALF OF THE FORECAST AREA...ESPECIALLY EAST OF DANVILLE AND LYNCHBURG. BUFKIT SOUNDINGS SHOWED THE WEDGE BREAKING IN MOST LOCATIONS BY NOON WITH THE STRATUS AND FOG LIFTING AND WINDS COMING AROUND TO THE SOUTHWEST. THIS AFTERNOON WHEN THE FORECAST AREA IS OUT OF THE WEDGE AND INTO THE WARM SECTOR AHEAD OF THE FRONT EXPECTING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. TEMPERATURES WILL BE ABOUT 10 TO 15 DEGREES ABOVE NORMAL...BUT EVEN WITH THE WARMING...ONLY MARGINAL CAPE IS EXPECTED DUE A WARM LAYER AROUND 700 MB THIS AFTERNOON. AT 4AM THE COLD FRONT EXTENDED FROM PITTSBURGH TO LITTLE ROCK. LOW PRESSURE WILL MOVE ALONG THE BOUNDARY TONIGHT. A STRONG UPPER TROF BEGINS TO DIG IN THE CENTRAL UNITED STATES TONIGHT. SHOWERS WILL BE WIDESPREAD ALONG AND BEHIND THE FRONT. KEPT THE CHANCE OF THUNDERSTORMS IN FOR THIS EVENING. 00Z LOCAL WRF WAS AN HOUR OF TWO FASTER WITH THE FRONTAL PASSAGE THAN THE NAM AND GFS. AT THIS TIME EXPECT THE FRONT TO REACH THE FAR WESTERN COUNTY WARNING AREA AROUND 00Z/8PM AND EXIT THE EASTERN COUNTIES AROUND 05Z/1AM. TEMPERATURES WILL DROP QUICKLY BEHIND THE FRONT TONIGHT. AIR MASS WILL BE COLD ENOUGH TO SUPPORT SNOW IN THE HIGHEST ELEVATIONS WEST OF THE BLUE RIDGE BY EARLY FRIDAY MORNING. THE STRONG COLD AIR ADVECTION COMBINED WITH PRESSURE RISES OF 5 TO 10MB/6HRS WILL RESULT IN GUSTY WINDS TONIGHT. BUFKIT SOUNDINGS SUGGESTED OCCASIONAL GUST OF 25 TO 35 MPH. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... AS OF 345 AM EDT THURSDAY... MODEL GENERATION OF WAVES ALONG THE COLD FRONT HAVE SLOWED ITS PROJECTED PASSAGE ACROSS THE REGION. AND WHILE THE FRONT WILL BE CLEAR OF US TO THE EAST BY FRIDAY...THE FRONTAL WAVES BEING DRIVEN BY UPPER LEVEL SHORT WAVE ENERGY WILL KEEP RESIDUAL PRECIPITATION ACROSS THE EAST FRIDAY MORNING. AT THE SAME TIME NORTHWEST WINDS WILL BE GENERATING UPSLOPE PRECIPITATION WEST OF THE BLUE RIDGE AS MUCH COLDER COLDER AIR MOVES IN. THE UPSLOPE PRECIPITATION WILL BE RAIN FOR MOST LOCATIONS WEST OF THE RIDGE BUT THE HIGHER ELEVATIONS OF THE FAR WESTERN SLOPES WILL SEE SNOW SHOWERS. GIVEN THE STRENGTH OF THE SUN THIS TIME OF YEAR AND WARM ANTECEDENT CONDITIONS NO ACCUMULATION IS EXPECTED DURING THE DAYTIME ON FRIDAY. BY FRIDAY NIGHT THE HEART OF THE VERY COLD AIR WILL SURGE INTO THE REGION...ALLOWING FOR UPSLOPE PRECIPITATION TO CHANGE TO SNOW FOR ALL LOCATIONS WEST OF THE RIDGE. WITH NO SUN TO COMPETE WITH...SOME ACCUMULATION IS POSSIBLE FRIDAY NIGHT MAINLY FOR THE FAR WESTERN SLOPES WHERE AMOUNTS WILL GENERALLY BE AN INCH OR LESS. HIGH PRESSURE WILL THEN BUILD IN FOR THE WEEKEND...BRINGING AN END TO THE SNOW SHOWERS SATURDAY MORNING WITH FAIR WEATHER ON TAP THROUGH SUNDAY. TEMPERATURES WILL BE RUNNING 10 TO 15 DEGREES BELOW NORMAL THROUGH THE PERIOD WITH SATURDAY BEING THE COLDEST DAY OF THIS STRETCH. LOWS SATURDAY MORNING WILL BOTTOM OUT GENERALLY IN THE TEENS WEST OF THE RIDGE TO MIDDLE 20S EAST. WINDS WILL ALSO BE BLUSTERY AS THE COLDER AIR MOVES IN FRIDAY AND FRIDAY NIGHT...PRODUCING WIND CHILL VALUES SATURDAY MORNING OF ZERO TO 10 ABOVE WEST TO THE LOWER AND MIDDLE 20S EAST. HIGHS SATURDAY WILL ONLY BE IN THE LOW TO MID 30S WEST AND IN THE MID TO UPPER 40S EAST. THANKFULLY TEMPERATURES WILL START TO REBOUND AS WE CLOSE OUT THE WEEKEND WITH THE COLD AREA OF HIGH PRESSURE SINKING TO OUR SOUTHEAST...ALLOWING OUR WINDS TO COME AROUND TO A SOUTHWESTERLY DIRECTION AND BRING WARMER AIR BACK INTO THE REGION. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AS OF 400 PM EDT WEDNESDAY... NORTHWEST FLOW PREVAILS THROUGH MONDAY WITH AN ALBERTA CLIPPER PROGGED TO TRACK ACROSS THE REGION SUNDAY NIGHT TO MONDAY. THE GFS IS FASTER AND STRONGER WITH THIS SYSTEM THAN THE ECMWF...BUT GIVEN THE PATTERN IN PLACE AT THAT POINT...THE GFS FORECAST SEEMS MORE REASONABLE. POPS ARE QUESTIONABLE WITH THIS SYSTEM...SO HAVE JUST INDICATED LOW CHC POPS IN THE WEST FOR NOW UNTIL BETTER CONSENSUS IS OBTAINED FROM THE MODELS ON THIS SYSTEM. BEYOND THAT...THE UPPER FLOW BECOMES MORE ZONAL AND THE FOCUS WILL BE ON A HIGHLY KINEMATIC...PACIFIC BASED SYSTEM IN THE SOUTHERN STREAM EXPECTED TO REACH THE CWA AT THE END OF THE FORECAST PERIOD. THIS COULD BE A SEVERE WEATHER SYSTEM FOR THE SOUTHERN PLAINS TO THE SOUTHEAST STATES...BUT MORE QUESTIONABLE FOR OUR AREA. YIELDED TOWARD THE SUPERBLEND FOR POPS IN THE LAST TWO PERIODS TO BETTER AGREE WITH NEIGHBORS. HOWEVER...TIMING OF THE ARRIVAL OF WARM ADVECTION PRECIPITATION ASSOCIATED WITH THIS SYSTEM REMAINS HIGHLY QUESTIONABLE AT THIS POINT. THE ZONAL FLOW WILL YIELD TO NEAR NORMAL TEMPERATURES THROUGH THE PERIOD. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... AS OF 720 AM EDT THURSDAY... RADAR SHOWED CLUSTER OF SHOWERS AND ISOLATED THUNDERSTORMS IN SOUTH CENTRAL VIRGINIA MOVING NORTH THIS MORNING. SHOWERS WILL BE OUT OF THE KLYH BY 13Z/9AM. BUFKIT FORECAST SHOWED CEILINGS LOWERING TO IFR EARLY THIS MORNING UNDER A SHALLOW BUT STRONG INVERSION. PERSISTENT WEDGE AND INVERSION WILL BREAK THIS MORNING. MEDIUM CONFIDENCE THAT CEILINGS WILL IMPROVE BACK TO VFR AT KROA/KBCB/KDAN AND KLYH BY 17Z/NOON. WINDS WILL BE GUSTY OUT OF THE SOUTHWEST ONCE THE WEDGE ERODES. HIGH CONFIDENCE THAT A STRONG COLD FRONT WILL CROSS THROUGH THE REGION JUST AFTER 00Z/7PM AT KLWB AND KBLF. THE FRONT IS EXPECTED TO REACH KLYH AROUND 04Z/MIDNIGHT AND KDAN AROUND 05Z/1AM. EXPECT A BAND OF MODERATE TO HEAVY SHOWERS ALONG AND JUST BEHIND THE FRONT. VISIBILITY MAY DROP TO MVFR LEVELS IN THE HEAVIER RAIN. WINDS WILL BECOME NORTHWEST BEHIND THE FRONT WITH GUSTS AT 20 TO 30 KNOTS. SHOWERS AND GUSTY WINDS WILL CONTINUE THROUGH FRIDAY AS MUCH COLDER AIR SURGES INTO THE REGION. SNOW SHOWERS ARE LIKELY WITH MVFR CEILINGS AND VISIBILITIES IN THE WESTERN UPSLOPE AREAS OF THE MOUNTAINS LATE TONIGHT THROUGH FRIDAY NIGHT. WINDS WILL DIMINISH SATURDAY WITH VFR CONDITIONS AS HIGH PRESSURE BUILDS INTO THE AREA. VFR WEATHER IS EXPECTED SUNDAY AND MONDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/KK SHORT TERM...MBS LONG TERM...RAB AVIATION...AMS

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