Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 041847 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 147 PM EST WED MAR 4 2015 .SYNOPSIS... A COLD FRONT WILL EAST ACROSS THE REGION THIS AFTERNOON INTO TONIGHT...BEFORE MOVING OFFSHORE LATE THURSDAY. HIGH PRESSURE OVER THE MISSISSIPPI VALLEY WILL MOVE INTO THE AREA FOR FRIDAY THROUGH SUNDAY. WIDESPREAD RAIN IS EXPECTED TODAY WITH WINTER PRECIPITATION TONIGHT AND THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 146 PM EST WEDNESDAY... ADJUSTED TEMPERATURES AND RAISED HIGH TEMPERATURES ESPECIALLY IN THE WEST FOR THIS AFTERNOON. DECREASED POPS IN THE SOUTHEAST FOR THIS AFTERNOON INTO THIS EVENING. AS 907 AM EST WEDNESDAY... RAIN CONTINUES THIS MORNING AS COLD FRONT APPROACHES FROM THE WEST. THE HEAVIEST RAIN WAS LOCATED ACROSS THE NORTHWEST CWA. FLOOD WARNINGS POSTED THIS MORNING FOR TAZEWELL NORTHWARD INTO SOUTHEAST WEST VIRGINIA...WHERE COMBINED WET SOILS AND SNOW MELT WITH THIS RAIN WILL CAUSE FLOODING. NAM...RAP AND GFS WERE SIMILAR WITH TIMING OF THE COLD FRONT WHICH MOVES SOUTHEAST TODAY INTO TONIGHT. HIGH TEMPERATURES TODAY WILL BE MILD WITH READINGS FROM THE MID 40S IN THE NORTHWEST TO THE MID 60S IN THE SOUTHEAST. MAXIMUM TEMPERATURES WILL BE REACHED EARLY IN THE NORTHWEST PORTIONS OF AREA. MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND POPS. EXPECT AN ACTIVE DAY WITH MANY ISC UPDATES. AS OF 515 AM EST WEDNESDAY... BROAD BAND OF PRECIPITATION EXTENDED FROM MASSACHUSETTS TO MISSOURI EARLY THIS MORNING...WITH THE SOUTHERN EDGE OF THE RAIN ROUGHLY THROUGH OUR AREA WEST OF A LYNCHBURG TO BOONE LINE. AT 4AM...A COLD FRONT EXTENDED FROM NEW YORK TO WESTERN TENNESSEE. THE RAIN AND COLD FRONT WILL ADVANCE SLOWLY SOUTHWEST TODAY. SHORT RANGE MODELS WERE SIMILAR IN THE TIMING OF THE FRONT AND THE AREA WITH THE BEST COVERAGE OF LIGHT TO MODERATE RAIN. BY NOON EXPECTING THE FRONT TO EXTEND FROM AROUND BUCKINGHAM TO TAZEWELL. HAVE INCREASED PROBABILITY OF RAIN NORTH OF THE BOUNDARY. WINDS THIS MORNING AHEAD OF THE FRONT WILL BE OUT OF THE SOUTHWEST. WIND GUSTS AT HIGHER ELEVATIONS MAY REACH 40 MPH THIS MORNING DUE TO A STRONG LOW LEVEL JET. WINDS WILL TURN TO THE NORTH AND NORTHWEST BEHIND THE FRONT. THERE WAS A WIDE RANGE IN TEMPERATURES THIS MORNING. SOME VALLEYS WERE IN THE UPPER 30S TO LOWER 40S WHILE WESTERN PARTS OF THE FORECAST AREA AND THE HIGHER ELEVATIONS HAVE CLIMBED INTO THE LOWER TO MID 50S. TEMPERATURES WILL REMAIN MILD ON THE SOUTH SIDE OF THE FRONT BUT WILL BE STEADY OR FALLING TO THE NORTH. THROUGH LATE THIS AFTERNOON...TEMPERATURES WILL REMAIN WARM ENOUGH FOR ONLY RAIN TODAY. MAXIMUM TEMPERATURES COULD BE REACHED EARLY IN THE NORTHWEST PART OF THE FORECAST AREA...BUT TIMING WILL BE VERY DEPENDENT ON THE LOCATION OF THE FRONT. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... AS OF 530 AM TUESDAY... PRECIPITATION WILL STILL BE FALLING AS RAIN AT SUNSET THIS EVENING...HOWEVER ARCTIC AIR WILL CONTINUE TO ADVANCE FROM THE NORTHEAST AS A COLD FRONT MAKES ITS WAY ACROSS OUR AREA. WHILE THERE WILL BE SPOTTY SHOWERS AHEAD OF THE COLD FRONT...THE MAJORITY OF RAIN WILL ACTUALLY FALL BEHIND THE FRONT AS THE ARCTIC AIR UNDERCUTS THE UNUSUALLY MOIST AIR IN PLACE. PRECIPITABLE WATER VALUES RANGING FROM 1.0 INCHES WEST OF THE INTERSTATE 77 CORRIDOR TO AROUND 1.25 INCHES ACROSS THE SOUTHSIDE WILL SUPPORT PERIODS OF LOCALLY HEAVY RAIN THROUGH LATE EVENING...MORE SO FOR THE MOUNTAINS WHERE OROGRAPHICS CAN HELP PRODUCE LOCALLY HIGHER PRECIPITATION AMOUNTS. WILL START TO SEE RAIN CHANGE OVER TO FREEZING RAIN AND SLEET BY MIDNIGHT THURSDAY ACROSS SOUTHEAST WEST VIRGINIA...WITH THE CHANGEOVER LINE WORKING SOUTHEAST TOWARD THE BLUE RIDGE THROUGH THE NIGHT. DO NOT EXPECT FREEZING RAIN TO LAST LONG BEFORE CHANGING TO SLEET AS THE DEPTH OF COLD AIR INCREASES QUICKLY...AND THEREFORE EXPECT ICE ACCUMULATIONS TO BE LESS THAN A TENTH OF AN INCH WHERE FREEZING RAIN OCCURS. THE COLDEST AIR WILL BE FOUND NORTH OF INTERSTATE 64...WHICH IS WHERE THE CHANGEOVER TO SNOW WILL HAPPEN FASTEST. THE COMPLEXITY OF THE FORECAST INCREASES AFTER SUNRISE THURSDAY AS A WAVE OF LOW PRESSURE PASSES ALONG THE COLD FRONT...WHICH WILL BE SITUATED ACROSS THE COASTAL PLAIN BY THAT POINT. STRONG CONVERGENCE IN THE LOW LEVELS AND GREATER INSTABILITY ALOFT AS THE SUPPORTING UPPER LEVEL TROUGH APPROACHES WILL MAKE FOR AN INCREASE OF PRECIPITATION AMOUNTS ACROSS CENTRAL VIRGINIA...WHICH WILL FALL MAINLY AS SNOW BY LATE MORNING. HIGHEST SNOWFALL TOTALS WILL BE FOUND NORTH OF INTERSTATE 64...WHERE 4 TO 6 INCHES ARE EXPECTED WITH LOCALLY HIGHER AMOUNTS...AND HAVE ENOUGH CONFIDENCE TO ISSUE A WINTER STORM WARNING FOR THIS AREA. LESSER AMOUNTS OF 1 TO 4 INCHES ARE EXPECTED FURTHER SOUTH...WHERE THERE IS A BETTER POTENTIAL FOR SLEET TO MIX WITH SNOW AND THEREFORE KEEP ACCUMULATIONS LOWER. WHEN ALSO CONSIDERING THE POTENTIAL FOR FREEZING RAIN IN AREAS...HAVE PLACED A WINTER WEATHER ADVISORY IN EFFECT FOR THE BLUE RIDGE WESTWARD SOUTH OF INTERSTATE 64. THE LATEST RUN OF WEATHER FORECAST MODELS HAS A SIGNIFICANT SPREAD OF EXPECTED PRECIPITATION AMOUNTS FOR AREAS NORTH OF HIGHWAY 460. LONG STORY SHORT...DAY SHIFT WILL HAVE ANOTHER OPPORTUNITY TO LOOK AT THIS SYSTEM PER THE 04/12Z WEATHER MODELS. AS SUCH...IF THE SYSTEM APPEARS WETTER AND/OR COLDER...DAY SHIFT MAY DECIDE TO EXPAND THE WINTER STORM WARNING AND ADVISORY FURTHER SOUTH AND EAST. AT ANY RATE...AS THE WAVE PASSES OUR AREA DURING THURSDAY AFTERNOON...BELIEVE THAT PRECIPITATION WILL BEGIN TO CUT OFF SHARPLY FROM WEST TO EAST...WITH ALL BUT RESIDUAL UPSLOPE SNOW SHOWERS OUT OF THE AREA BY EARLY EVENING. WITH ARCTIC AIR CONTINUING TO BUILD IN FROM THE WEST...EXPECT THAT HIGH TEMPERATURES WILL OCCUR DURING THURSDAY MORNING...WITH TEMPERATURES THEN FALLING THROUGH THE DAY. THURSDAY NIGHT WILL BE MOSTLY CLEAR WITH LIGHT WINDS AS HIGH PRESSURE SETTLES OVER THE CENTRAL OHIO RIVER VALLEY. AS SUCH... EXPECT STRONG RADIATIONAL COOLING THAT WILL PUSH OVERNIGHT LOWS TO AROUND ZERO IN SPOTS ACROSS THE MOUNTAINS...AND TO THE UPPER TEENS/LOW 20S ACROSS THE NORTH CAROLINA PIEDMONT. THE SAME HIGH PRESSURE SYSTEM WILL REMAIN ACROSS THE REGION ON FRIDAY...KEEPING TEMPERATURES ON THE CHILLY SIDE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 215 PM EST TUESDAY... SATURDAY...HIGH PRESSURE BUILDS OVER THE REGION...WITH ITS CENTER SHIFTING EAST OF THE AREA BY SATURDAY NIGHT. THE RESULT WILL BE A DRY FORECAST...WITH MODERATING TEMPERATURES. AFTER HIGHS ON FRIDAY IN THE UPPER 20S TO MID 30S ACROSS THE FORECAST AREA...HIGHS ON SATURDAY WILL RANGE MORE IN THE 40S WEST TO LOWER 50S EAST. THERE HAS BEEN CONSIDERABLE VARIATION IN THE MODEL GUIDANCE DURING THE SUNDAY THROUGH TUESDAY TIME PERIOD. WHILE EACH IS FAIRLY CONSISTENT THAT A LONG WAVE TROUGH WILL DEVELOP ACROSS THE EASTERN THIRD OF CONUS...THERE HAVE BEEN INCONSISTENCIES AS TO WHETHER OR NOT...AND WHEN...AND WHAT TRACK A SOUTHERN STREAM SYSTEM MAY GET PICKED UP ON THE EAST SIDE OF THIS TROUGH AND PROGRESS NORTHEAST ACROSS OUR AREA. THE GFS HAS NOT BEEN FAVORABLE OF THIS OCCURRENCE. THE ECMWF WAS OPTIMISTIC ON AN ARRIVAL A SOUTHERN SYSTEM ON MONDAY IN YESTERDAYS SOLUTION. TODAYS SOLUTION PLACES THAT EVENT ABOUT 24 HOURS LATER ON TUESDAY. OUR FORECAST TODAY WILL REFLECT TEMPERATURES CONTINUING TO MODERATE THROUGH MONDAY...WITH THE THINKING THAT THE DEVELOPING TROUGH AXIS WILL REMAIN TO OUR WEST...AND WE WILL CONTINUE IN WARM AIR ADVECTION AT THE SURFACE. IT WILL ALSO REFLECT THE POTENTIAL FOR SOME ISOLATED TO SCATTERED UPSLOPE SNOW SHOWERS ACROSS SOUTHEAST WEST VIRGINIA WHERE 850 MB FLOW WILL BE MORE W-NW. IT WILL ALSO ALLOW FOR A SLIGHT CHANCE OF A SOUTHERN STREAM SYSTEM IMPACTING THE AREA ON TUESDAY WITH RAIN OR FREEZING RAIN. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... AS OF 1245 PM EST WEDNESDAY... MVFR CONDITIONS WITH POCKETS OF IFR/LIFR IN LOW CLOUDS...FOG AND RAIN THIS AFTERNOON INTO TONIGHT. SOUTHWESTERLY WINDS WILL GRADUALLY MIX TO THE SURFACE THIS AFTERNOON...RESULTING IN AN INCREASE OF WIND SPEEDS TO AROUND 10KTS WITH UP TO 20KT GUSTS. A COLD FRONT WILL PASS ACROSS THE MOUNTAINS THIS AFTERNOON INTO TONIGHT. THIS BOUNDARY SHOULD REACH KDAN AFTER 05/00Z. ARCTIC AIR WILL BUILD IN BEHIND THE FRONT...WHICH WILL CAUSE TEMPERATURES TO FALL TONIGHT. RAIN WILL TRANSITION TO SLEET AND FREEZING RAIN...THEN OVER TO SNOW IN MOST LOCATIONS. FOR TIMING EXPECT RAIN CHANGING TO SLEET BY AROUND 05/05Z FOR KBLF/KLWB...BEFORE CHANGING TO SNOW BY AROUND 05/10Z. CHANGE OVER TO SLEET FOR KBCB/KROA WILL HAPPEN CLOSER TO 05/10Z...WITH THE CHANGE TO SNOW NOT TAKING PLACE UNTIL AFTER SUNRISE THURSDAY. WITH THE CHANGE TO SNOW... SIGNIFICANT REDUCTIONS IN VISIBILITY CAN BE EXPECTED. CEILINGS WILL FALL TO IFR/LIFR LEVELS BEHIND THE FRONT. SLEET WILL CHANGE TO SNOW FROM NORTHWEST TO SOUTHEAST ON THURSDAY. ROUNDS OF HEAVY SNOW WILL BE POSSIBLE IN THE VICINITY OF THE BLUE RIDGE LATE THURSDAY MORNING AND DURING THE AFTERNOON AS A WAVE OF LOW PRESSURE PASSES ALONG THE COASTAL PLAIN. LOW MVFR/IFR CONDITIONS WILL BE WIDESPREAD THROUGH THE DAYTIME...WITH CLEARING DURING THE EVENING. MEDIUM CONFIDENCE ON CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED FORECAST... FRIDAY TO SUNDAY WILL SEE A RETURN TO HIGH PRESSURE AND VFR WEATHER. && .HYDROLOGY... AS OF 913 AM EST TUESDAY... FLOODING THREAT WILL CONTINUE IN THE NORTHWEST PORTIONS OF OUR CWA AS MODELS HAVE 1.5" OR MORE IN 12 HRS PROJECTED. COMBINATION OF VERY WET SOILS AND SNOW MELT WITH RAIN WILL CAUSE FLOODING IN SOUTHEAST WEST VIRGINIA AND TAZEWELL. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST THURSDAY FOR VAZ007-009>018-022-034. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM EST THURSDAY FOR VAZ019-020-023-024. WINTER WEATHER ADVISORY FROM 6 AM TO 10 PM EST THURSDAY FOR VAZ032-033-043>046-058-059. WINTER STORM WARNING FROM 3 AM TO 7 PM EST THURSDAY FOR VAZ035- 047. NC...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST THURSDAY FOR NCZ001-002-018. WV...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM EST THURSDAY FOR WVZ042>044-507-508. && $$ SYNOPSIS...AMS NEAR TERM...AMS/KK SHORT TERM...NF LONG TERM...DS AVIATION...AMS/KK HYDROLOGY...WP

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