Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 021737 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1237 PM EST MON MAR 2 2015 .SYNOPSIS... A COLD FRONT WILL CONTINUE TO MOVE EAST AND OFF THE COAST THIS MORNING. HIGH PRESSURE WILL FOLLOW BEHIND THE FRONT...CROSSING THE OHIO VALLEY TONIGHT AND EXTENDING SOUTH INTO THE MID ATLANTIC REGION TONIGHT. A LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS ON TUESDAY WILL MOVE NORTHEAST AND WILL PUSH A STRONG COLD FRONT THROUGH OUR AREA ON WEDNESDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 930 AM EST MONDAY... A COLD FRONT MOVING EAST ACROSS THE REGION THIS MORNING. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO OUR REGION THIS AFTERNOON INTO TONIGHT. WSR-88D SHOWED A FEW NARROW BANDS OF SNOW AND RAIN DIMINISHING THIS MORNING. MADE A QUICK UPDATE TO DIMINISH POPS THIS MORNING WITH DRY AIR PUNCH AND DOWNSLOPING EFFECT. LEANED POPS TOWARDS RNK WRF-ARW FOR NEXT COUPLE OF HOURS. MODIFIED TEMPERATURES FOR THIS MORNING INTO THIS AFTERNOON ACCORDING TO SFC OBS AND MODEL TRENDS. AS OF 500 AM EST MONDAY... A COLD FRONT COMES THROUGH THE MORNING AND WILL BE EAST OF THE FORECAST AREA BY NOON. MODELS HOLD A MAJORITY OF THE PRECIPITATION ALONG AND AHEAD OF THE FRONT IN THE FAR WESTERN COUNTY WARNING AREA THIS MORNING. PUSH OF DRIER AIR BEHIND THE FRONT WILL BE ENOUGH TO END CHANCE OF PRECIPITATION AND CLEAR OUR MUCH OF THE FOG AND CLOUD COVER THIS AFTERNOON. HIGH PRESSURE MOVES ACROSS THE OHIO VALLEY TODAY AND WEDGES DOWN THE EAST SLOPES OF THE APPALACHIANS TONIGHT. 850 MB WINDS BEHIND THE FRONT WILL BE 45 TO 55 KNOTS WITH PRESSURE RISES 5 TO 7 MB/6 HOURS THIS MORNING. WILL HAVE WINDS GUSTING JUST BELOW ADVISORY LEVEL...UP TO 50 MPH THIS MORNING. WINDS DIMINISH THIS AFTERNOON AND THE TURN TO THE EAST THEN SOUTHEAST TONIGHT AS THE WEDGE BECOMES ESTABLISHED. THE EAST TO SOUTHEAST WINDS WILL BRING LOW LEVEL MOISTURE BACK NORTH ALONG THE BLUE RIDGE AND EASTERN SLOPES OVERNIGHT. COLDER AIR COMES IN BEHIND THE FRONT TODAY...BUT WITH SHRINKING AREAL COVERAGE OF PRECIPITATION AND SOME SUN IN THE AFTERNOON...TEMPERATURES WILL HOLD STEADY OR SLOWLY RISE. AS WIND DROPS OFF THIS EVENING...TEMPERATURES WILL COOL BUT AS CLOUD FILL BACK IN LATE TONIGHT DROP IN TEMPERATURES WILL BE LIMITED. HAVE ADDED PATCHY DRIZZLE AND FREEZING DRIZZLE AFTER MIDNIGHT FOR THE TYPICAL UPSLOPE AREA ALONG AND EAST OF THE SOUTHERN BLUE RIDGE. BUFKIT SHOWED A WARM NOSE AROUND 3000 FT AGL AND SURFACE TEMPERATURES DROPPING BELOW FREEZING.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/... AS OF 500 AM EST MONDAY... WE WILL START OUT TUESDAY DEALING WITH ANOTHER WEDGE SITUATION SIMILAR TO WHAT WE JUST WENT THROUGH ON SUNDAY...BUT WITH MORE SYNOPTIC PRECIPITATION TO DEAL WITH. COLD HIGH PRESSURE WEDGES DOWN THE EASTERN SEABOARD WILL GET OVER RUN BY MUCH WARMER AIR AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. SOUNDINGS ON BUFKIT SHOW THE DEPTH OF THE COLD AIR IN THE BOUNDARY LAYER TO BE SUBSTANTIALLY DEEP AND COLD AT THE ONSET OF PRECIPITATION. THIS WILL FAVOR SOME SLEET AND HELP KEEP DOWN ICING ACCUMULATIONS FROM FREEZING RAIN AS PRECIPITATION MOVES IN. AS IS TYPICALLY THE CASE...THE WARMER AIR WILL MOVE IN FROM THE SOUTHWEST WITH GOOD WARMING AND THE LEAST POTENTIAL FOR ICING FROM THE MOUNTAIN EMPIRE AND GRAYSON HIGHLANDS OF VA INTO THE NW MOUNTAINS OF NC. EXPECTING THE WARMER AIR TO INTRUDE INTO THE NEW RIVER AND ROANOKE VALLEYS DURING THE AFTERNOON...BUT THE COLD AIR WILL MODERATE ONLY SLOWLY ACROSS THE GREENBRIER VALLEY...ALLEGHANY HIGHLANDS...AND PIEDMONTS OF NC/VA. HOWEVER...EVEN THIS SLIGHT TEMPERATURE MODERATION SHOULD BE ENOUGH TO END THE THREAT OF FREEZING RAIN FOR THE VAST MAJORITY OF THE AREA BY MID TO LATE AFTERNOON WITH TEMPS IN THE LOW TO MID 30S. RAIN WILL CONTINUE ACROSS THE REGION AS THE FRONT APPROACHES TUESDAY NIGHT BEFORE IT MOVES THROUGH ON WEDNESDAY. BASED ON THE LATEST QPF FORECASTS AND EXPECTED SNOW MELT...CURRENT HYDROLOGIC MODELS DO NOT INDICATE A SIGNIFICANT RIVER FLOOD THREAT BUT SMALLER STREAMS AND CREEKS ARE STILL A CONCERN. HOWEVER...CONSENSUS TIMING OF THE FRONTAL PASSAGE IS NOT CLEAR CUT AND BELIEVE IT BEST TO WAIT FOR LATER MODEL RUNS BEFORE DECIDING IF ANY HYDRO WATCHES ARE NEEDED. AS COLDER AIR MOVES IN BEHIND THE FRONT ON BLUSTERY NORTHWEST WINDS CONDITIONS APPEAR FAVORABLE FOR A BURST OF SNOW AS THE COLD AIR CATCHES UP TO THE BACK EDGE OF PRECIPITATION STARTING ON WEDNESDAY NIGHT AND CONTINUING INTO THURSDAY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE FRONT. IT LOOKS TO BE A FINE LINE BETWEEN WHERE THE AIR TEMPERATURES WILL SUPPORT SNOW AND WHERE THE HIGHEST PRECIPITATION WILL BE. THE MOST LIKELY LOCATION TO RECEIVE SEVERAL INCHES OF WET SNOW CURRENTLY APPEARS TO BE 30 MILES OR SO EITHER SIDE OF THE BLUE RIDGE...BUT THIS WILL LIKELY CHANGE AS THE SITUATION DEVELOPS. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... AS OF 130 PM EST SUNDAY... THURSDAY NIGHT...SOME LINGERING SNOW SHOWER WILL STILL BE POSSIBLE EAST OF THE BLUE RIDGE. HOWEVER...BY MIDNIGHT...PRECIPITATION IS EXPECTED TO COME TO AN END...AND CLOUD COVER ACROSS THE ENTIRE REGION WILL TREND FROM CLOUDY TO PARTLY CLOUDY THROUGH THE NIGHT. LOW TEMPERATURES WILL RANGE FROM THE SINGLE DIGITS TO THE LOWER TEENS ACROSS THE MOUNTAINS WITH MID TO UPPER TEENS ACROSS THE PIEDMONT. FRIDAY INTO SATURDAY...A BROAD AREA OF HIGH PRESSURE IS EXPECTED TO BUILD INTO...OVER...AND THEN EAST OF THE AREA. THIS WILL HAVE THE IMPACT TO KEEP OUR REGION PRECIPITATION FREE WITH A TREND FROM COLDER CONDITIONS TO MILDER CONDITIONS AS WE START GETTING ON THE RETURN SIDE SW-W FLOW OF THE HIGH BY SATURDAY AFTERNOON. THE TREND WILL CONTINUE INTO SUNDAY WITH NO PRECIPITATION AND EVEN MILDER CONDITIONS AS A TROUGH DEEPENS IN THE CENTRAL U.S. AND A SHORTWAVE RIDGE ALOFT BUILDS OVER THE REGION. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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AS OF 1237 PM EST MONDAY... THE COLD FRONT WILL CONTINUE TO PUSH EAST INTO THE ATLANTIC OCEAN THIS AFTERNOON INTO TONIGHT. SCT TO BKN MVFR CLOUDS ARE POSSIBLE THIS AFTERNOON INTO TONIGHT...MAINLY IN THE MOUNTAINS. HIGH PRESSURE WILL WEDGE DOWN THE EAST SLOPES OF THE APPALACHIANS TONIGHT. AS SURFACE AND LOW LEVEL WINDS TURN TO THE EAST AND SOUTHWEST...LOW LEVEL MOISTURE WILL RETURN NORTH ALONG THE SOUTHERN BLUE RIDGE. HIGH CONFIDENCE OF CEILINGS LOWERING TO MVFR AT KBCB AND KDAN AFTER 06Z/1AM. LIGHT RAIN...FREEZING RAIN AND SLEET WILL LIFT NORTHEAST ACROSS OUR REGION LATE TONIGHT INTO TUESDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH QUICKLY LATE THIS AFTERNOON AND EVENING AS HIGH PRESSURE BUILDS IN. A WINTRY MIXTURE TUESDAY MORNING WILL TRANSITION TO MAINLY RAIN TUESDAY AFTERNOON. MEDIUM CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE PERIOD. EXTENDED FORECAST... ANOTHER LOW PRESSURE SYSTEM THAT WILL IMPACT ALL OF THE REGION WILL TRACK FROM THE CENTRAL PLAINS INTO NEW ENGLAND TUESDAY NIGHT INTO WEDNESDAY. THIS WILL RESULT IN SUB-VFR CONDITIONS WEDNESDAY AND THURSDAY WITH WIDESPREAD RAIN AHEAD OF THE FRONT ON WEDNESDAY AND WINTER PRECIPITATION BEHIND THE FRONT WEDNESDAY NIGHT AND THURSDAY. FRIDAY SHOULD SEE A RETURN TO HIGH PRESSURE AND VFR WEATHER.
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&& .HYDROLOGY...
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AS OF 500 AM EST MONDAY... THERE IS A CONCERN FOR THE POTENTIAL OF FLOODING BECAUSE OF THE COMBINATION OF SNOW MELT AND HEAVY RAINFALL ACROSS THE GREENBRIER...UPPER JAMES RIVER BASINS WHERE UP TO TWO FEET OF SNOW HAS FALLEN DURING THE PAST COUPLE OF WEEKS. SOME MELTING HAS OCCURRED AND MORE IS EXPECTED TODAY AND TUESDAY. FORECAST RAIN AMOUNTS ON TUESDAY NIGHT AND WEDNESDAY MAY REACH 1.5 INCHES. THE COMBINATION OF SNOW MELT AND THIS MODERATE TO HEAVY RAINFALL MAY RESULT IN MINOR RISES ON AREA CREEKS AND STREAMS. MAJOR FLOODING IS NOT ANTICIPATED AT THIS TIME. THE NEXT WAVE OF HEAVIER PRECIPITATION SHOULD TRACK ACROSS THE PIEDMONT...WHERE THERE IS LITTLE TO NO SNOWPACK OF CONCERN.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/KK SHORT TERM...MBS LONG TERM...DS AVIATION...AMS/PM HYDROLOGY...AMS/RAB

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