Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 031839 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 139 PM EST TUE MAR 3 2015 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE MID ATLANTIC COAST TODAY...THEN A WARM FRONT WILL LIFT NORTH THROUGH THE REGION THIS EVENING. LOW PRESSURE OVER THE CENTRAL PLAINS WILL TRACK INTO SOUTHEAST CANADA AND WILL PUSH A COLD FRONT INTO THE REGION ON WEDNESDAY. COLDER AIR BEHIND THE FRONT WILL ALLOW FOR A TRANSITION FROM RAIN TO SNOW WEDNESDAY NIGHT AND THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 138 PM EST TUESDAY... WITH TEMPERATURES RISING THIS AFTERNOON INTO THIS EVENING. THE THREAT FOR WIDESPREAD ICING PROBLEMS HAS ENDED...THUS THE WINTER WEATHER ADVISORY IS CANCELLED. SOME LIGHT RAIN AND PATCHES OF DRIZZLE ARE EXPECTED FOR THE THIS AFTERNOON. ISOLATED POCKETS OF ICE MAY BE POSSIBLE ON THE COLDEST SURFACES. DRIVER SHOULD WATCH FOR SLICK ICY SPOTS ON ROADWAYS. AS OF 1000 AM EST TUESDAY... CANCELLED THE WINTER WEATHER ADVISORY MAINLY WEST OF I77 WHERE TEMPERATURES WERE ABOVE FREEZING MARK AND EXPECTED TO REMAIN AS SUCH...AND RADAR COVERAGE IS LIGHT. STILL CONCERN OVER DIABATIC COOLING OF TEMPERATURES WITH LIGHT PRECIPITATION...THUS WILL HOLD WITH REST OF WINTER WEATHER ADVISORY AT THIS TIME. MODIFIED POPS WITH LATEST RADAR TRENDS. SHAPED MORNING TEMPERATURES WITH SFC OBS AND LATEST MODEL TRENDS. MORE CHANGES LATER THIS MORNING IN THE ACTIVE WEATHER PATTERN . AS OF 415 AM EST TUESDAY... LOWER CLOUDS WERE JUST FILLING IN ACROSS THE FORECAST AREA THIS MORNING. HAVE MADE ADJUSTMENTS TO THE TIMING OF THE PRECIPITATION BASED ON RADAR TRENDS AND THE TIMING SHOWN ON THE LAST FEW RUNS OF THE HRRR AND THE LATEST WRF GUIDANCE. HAVE THEREFORE MADE ADJUSTMENTS TO THE VALID TIME OF THE ADVISORIES. APPEARS A MORE ORGANIZED AREAS OF PRECIPITATION WILL CROSS THE NORTHERN COUNTY WARNING AREA BETWEEN 8AM AND NOON. STILL EXPECTING A BETTER PROBABILITY OF PRECIPITATION ON THE EASTERN SLOPES OF THE BLUE RIDGE. OTHERWISE...NO WELL DEFINED FEATURES THAT WILL DEFINE WHERE AND WHEN PRECIPITATION WILL FALL. WHEREVER THE PRECIPITATION IS...IT WILL BE LIGHT. BUFKIT NOT SHOWING GOOD DENDRITIC GROWTH AND BY 15Z/10AM...WARM NOSE WILL BE WELL STRONG ENOUGH TO RESULT IN LIQUID AS THE HYDROMETEORS FALL THROUGH THAT LAYER. SO SURFACE TEMPERATURES WILL BE THE DECIDING FACTOR IN PRECIPITATION TYPE. NEW RIVER VALLEY THROUGH THE ALLEGHANY HIGHLANDS WERE BELOW FREEZING. ONLY A SLOW RISE IN TEMPERATURES EXPECTED TODAY. GUIDANCE KEPT THE NORTHEAST COUNTIES...MAINLY FROM LYNCHBURG INTO AMHERST AND ROCKBRIDGE COUNTY BELOW FREEZING FOR MUCH OF THE DAY. HAVE DELAYED THE START OF THE WINTER WEATHER ADVISORY AND EXTENDED THE ADVISORY THROUGH LATER IN THE DAY WHERE THE TEMPERATURE REMAINS BELOW FREEZING. TONIGHT...A STRONG LOW LEVEL JET PUSHES UP TEMPERATURES AND DEW POINTS. LOWS WILL OCCUR IN THE EVENING. AFTER MIDNIGHT...THE COLD FRONT APPROACHES AND THE PROBABILITY OF MODERATE RAIN IN THE NORTHWEST COUNTY WARNING AREA INCREASES. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 430 AM EST TUESDAY... EXPECT TO START WEDNESDAY WITH A COLD FRONT SITUATED FROM THE ALLEGHANY HIGHLANDS THROUGH THE MOUNTAIN EMPIRE. STRONG MOISTURE FLOW INTO THE AREA ON A 50KT TO 60KT SOUTHWESTERLY LOW LEVEL JET WILL PUSH PRECIPITABLE WATER VALUES TO 1.0-1.1 INCHES IN THE WEST...AND AS HIGH AS 1.4 INCHES FURTHER EAST...ALL SIGNIFICANTLY ABOVE NORMAL FOR EARLY MARCH. DURING THE MORNING...RAIN WILL BE WIDESPREAD WEST OF THE BLUE RIDGE...ALTHOUGH THE STRONGEST LIFT/HEAVIEST RAINFALL IS EXPECTED TO BE WEST OF THE CONTINENTAL DIVIDE...JUST SKIRTING OUR SOUTHEAST WEST VIRGINIA COUNTIES...PARTICULARLY THE WEST FACING SLOPES. FURTHER EAST...WILL LIKELY SEE A BAND OF HEAVY RAIN JUST AHEAD OF THE FRONT AS IT SLOWLY DRIFTS EAST THROUGH THE DAY...WITH SOME DRYING TAKING PLACE BEHIND THE BOUNDARY AS WINDS SHIFT NORTHWESTERLY AND DOWNSLOPE. DURING WEDNESDAY AFTERNOON AND EVENING...THE COLD FRONT WILL SLOW/STALL ACROSS THE SOUTHSIDE AND NORTH CAROLINA PIEDMONT AS A STRONG WAVE DEVELOPS OVER NORTHERN GEORGIA AND PUSHES NORTHEAST ALONG THE BOUNDARY. THE WAVE WILL PASS JUST SOUTHEAST OF OUR AREA DURING THE EARLY MORNING HOURS OF THURSDAY...WITH STRONG CONVERGENCE DEVELOPING FROM THE ALLEGHANY HIGHLANDS SOUTHWARD ALONG THE BLUE RIDGE...SUPPORTING AN ADDITIONAL ROUND OF POTENTIALLY HEAVY RAIN. AS THE WAVE PASSES OUR AREA DURING LATE THURSDAY MORNING...IT WILL ENHANCE THE NORTHWESTERLY FLOW ACROSS THE MOUNTAINS...DRAWING COLD AIR ASSOCIATED WITH ARCTIC HIGH PRESSURE FURTHER ACROSS OUR AREA. THE SURGE OF COLDER AIR HUGGING THE SURFACE WILL CAUSE RAIN TO CHANGE TO SLEET AND/OR FREEZING RAIN FOR A FEW HOURS ACROSS THE MOUNTAINS...BEFORE FINALLY CHANGING TO SNOW BY THURSDAY AFTERNOON. BECAUSE WE ARE EXPECTING MORE SLEET AND FREEZING RAIN THAN PREVIOUSLY FORECAST...WENT WITH LOWER SNOWFALL TOTALS FOR THURSDAY. RIGHT NOW...LOOKING AT THE POSSIBILITY OF WINTER STORM SNOW AND SLEET AMOUNTS FOR WESTERN GREENBRIER...AND PERHAPS BATH AND ROCKBRIDGE COUNTIES IN SPOTS...BUT DO NOT HAVE ENOUGH CONFIDENCE TO GO WITH A WINTER STORM WATCH AT THIS POINT. WILL LET THE DAY SHIFT HAVE ANOTHER LOOK AT THE COMING 03/12Z MODEL RUNS. PRECIPITATION WILL WIND DOWN THURSDAY AFTERNOON AND EVENING AS HIGH PRESSURE BUILDS IN FROM THE WEST...SETTLING ACROSS THE MID AND UPPER OHIO RIVER VALLEY BY FRIDAY MORNING. STRONG RADIATIONAL COOLING WILL MEAN ONE MORE SHOT OF SINGLE DIGIT TEMPERATURES TO START THE DAY ACROSS THE MOUNTAINS...WITH TEENS EXPECTED ACROSS THE PIEDMONT. HIGH PRESSURE WILL SHIFT TO NEW ENGLAND...WHERE IT WILL THEN WEDGE SOUTHWARD FRIDAY NIGHT...HUGGING THE EASTERN FACE OF THE APPALACHIANS. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 145 PM EST MONDAY... HIGH PRESSURE WILL BE IN CONTROL OF OUR WEATHER PATTERN THROUGH AT LEAST SATURDAY NIGHT. THE HIGH WILL GRADUALLY BUILD INTO THE AREA FROM THE WEST...AND MAKE ITS WAY TO THE COAST BY SATURDAY. THIS WILL ALLOW FOR A TREND TOWARD MILDER CONDITIONS AS THE LOW LEVEL FLOW ACROSS THE AREA BECOMES GRADUALLY MORE SW-W...WHILE A SHORTWAVE RIDGE AND RISING 850 TEMPS TAKE PLACE. SUNDAY INTO MONDAY A GENEROUS AMOUNT OF VARIATIONS IN THE MODELS TAKE PLACE. WHILE BOTH THE GFS AND THE NAM EVENTUALLY COME INTO AGREEMENT OF A LONG WAVE TROUGH OVER THE EASTERN THIRD OF CONUS BY MONDAY OR TUESDAY OR NEXT WEEK...HOW THE SOLUTIONS COME TO BE THAT WAY HAVE NOTABLE DIFFERENCES. THE GFS IS MORE PROGRESSIVE IN ESTABLISHING THE TROUGH IN THE EAST BY SUNDAY...AND ANY SOUTHERN STREAM SYSTEMS EASILY BYPASS OUR REGION EXITING THE U.S. NEAR THE GA/FL BORDER. THE ECWMF IS NOT A QUICK TO ESTABLISH AN EAST COAST TROUGH...AND A SUCH...SOUTHERN STREAM SYSTEMS HAVE A BETTER OPPORTUNITY TO PROGRESS NORTHEAST THROUGH OUR REGION ON THE EAST SIDE OF AN APPROACHING SHORTWAVE TROUGH. OUR FORECAST FOR SUNDAY INTO MONDAY WILL BE A CONSENSUS OF THESE TWO...WITH IT RESEMBLING A WATERED DOWN VERSION OF THE ECWMF IN TERMS OF PRECIPITATION POTENTIAL ON SUNDAY AND SUNDAY NIGHT...AND ALSO STAYING ON MORE OF THE MILD SIDE THAN COLD IN REGARDS TO MONDAY. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... AS OF 1230 PM EST TUESDAY... MVFR CONDITIONS WITH POCKETS OF IFR IN PRECIPITATION...CLOUDS AND FOG THIS AFTERNOON INTO TONIGHT. STRONG SOUTH TO SOUTHWEST WINDS ALOFT WILL BRING ABUNDANT MOISTURE INTO THE REGION THIS AFTERNOON INTO TONIGHT. TEMPERATURES WILL SLOWLY RISE THIS AFTERNOON INTO TONIGHT. THIS WILL END THE THREAT FOR FREEZING RAIN/FREEZING DRIZZLE ACROSS OUR AREA. TRIMMED BACK AND NARROWED THE WINDOW FOR LOW LEVEL WIND SHEAR IN THE TAFS FOR TONIGHT. CEILINGS AND VISIBILITIES WILL BE IFR TO LIFR FOR MUCH OF THE AREA IN LOW CLOUDS AND FOG THIS EVENING INTO WEDNESDAY MORNING. ANOTHER LOW PRESSURE SYSTEM THAT WILL IMPACT ALL OF THE REGION WILL TRACK FROM THE CENTRAL PLAINS INTO SOUTHEAST CANADA BY WEDNESDAY. THIS WILL RESULT IN WIDESPREAD SUB-VFR CONDITIONS ACROSS THE AREA WEDNESDAY AND THURSDAY WITH ABUNDANT RAIN. A COLD FRONT WILL CROSS THROUGH THE AREA ON WEDNESDAY. MEDIUM CONFIDENCE ON CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED FORECAST... WINTER PRECIPITATION IS LIKELY BEHIND THE FRONT WEDNESDAY NIGHT AND THURSDAY. AT THIS TIME THE MOST LIKELY PRECIPITATION TYPES ARE SNOW AND SLEET. FRIDAY AND SATURDAY WILL SEE A RETURN TO HIGH PRESSURE AND VFR WEATHER. && .HYDROLOGY... AS OF 300 PM EST MONDAY LIKELY TO SEE SOME SUBSTANTIAL RISES ON AREA RIVERS AND STREAMS IN RESPONSE TO UPCOMING RAIN EVENT AND SNOWMELT IN THE MOUNTAINS...QUESTIONS REMAIN ABOUT HOW SUBSTANTIAL. SIGNIFICANT SNOW AMOUNTS ARE NOW CONFINED TO PARTS OF THE UPPER JAMES AND GREENBRIER RIVER BASINS WHERE THE LATEST AVAILABLE ESTIMATES FROM THE NATIONAL OPERATIONAL REMOTE SENSING CENTER SHOW ROUGHLY 1 TO 3 INCHES OF SNOW WATER EQUIVALENT WITH ISOLATED 4 INCHES IN THE HIGHEST ELEVATIONS OF THE GREENBRIER. IN THE OTHER MAJOR RIVER BASINS...NEW...ROANOKE/DAN AND TENNESSEE... MELTING OVER THE WEEKEND AND TODAY HAS REDUCED THE SNOW TO LESS THAN 1 INCH OF SNOW WATER AND IN MOST PLACES ZERO. THE OTHER ELEMENT OF COURSE IS THE QPF. 12Z MODELS (INCLUDING LATEST EC) HAVE NUDGED THE HEAVIEST QPF A LITTLE MORE TO THE WEST...REDUCING AMOUNTS IN THE JAMES AND GREENBRIER SOME. IT STILL APPEARS AS IF 1 TO 2 INCHES COULD FALL ACROSS THE WESTERN BASINS BY 12Z THURSDAY AND COMBINED WITH SNOWMELT THIS COULD PRODUCE AT LEAST MINOR RIVER FLOODING ALONG THE GREENBRIER AND POSSIBLY THE UPPER JAMES. GUIDANCE RECEIVED FROM OHRFC THIS MORNING SUGGESTED MINOR FLOOD STAGE AT ALDERSON WV ON THE GREENBRIER LIKELY BY EARLY THURSDAY WITH THE COMBINED SNOWMELT AND QPF. HOWEVER...GIVEN THE CONTINUED UNCERTAINTIES WILL HOLD OFF ON A FLOOD WATCH AT THIS POINT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/KK SHORT TERM...NF LONG TERM...DS AVIATION...AMS/KK HYDROLOGY...PC

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.