Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 182037 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 337 PM EST TUE NOV 18 2014 .SYNOPSIS...
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ARCTIC HIGH PRESSURE WILL SINK SOUTH OF THE AREA TONIGHT INTO WEDNESDAY KEEPING COLD AND DRY WEATHER IN PLACE. ANOTHER COLD FRONT WILL PUSH IN FROM THE NORTHWEST WEDNESDAY NIGHT INTO THURSDAY FOLLOWED BY COLD HIGH PRESSURE FOR THE END OF THE WEEK. A COMPLEX LOW PRESSURE SYSTEM PASSING TO THE WEST WILL BRING WARMER TEMPERATURES ALONG WITH THE NEXT CHANCE OF RAIN LATER IN THE WEEKEND.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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AS OF 300 PM EST TUESDAY... 850 WINDS STAY AROUND 30 KNOTS OVERNIGHT FROM THE WEST THEN BACK TO THE SOUTHWEST DURING DAY WITH WIND SPEEDS INCREASING TO NEARLY 50 KNOTS. THIS SHOULD PROVIDE GOOD WARM AIR ADVECTION ON WEDNESDAY. BY THE END OF THE DAY...850 MB TEMPERATURES WILL BE IN THE -3 TO +1 RANGE. SURFACE HIGH PRESSURE WAS CENTERED OVER THE LOWER MISSISSIPPI VALLEY THIS AFTERNOON. THIS HIGH WILL MOVE ACROSS THE GULF COAST STATES. WHILE THE CENTER OF THE HIGH WILL REMAIN WELL TO THE SOUTH OF THE FORECAST AREA...THE RIDGE AXIS WILL CROSS THE FORECAST AREA LATE TONIGHT. THIS IS CLOSE ENOUGH TO ALLOW THE WINDS TO BECOME LIGHT AND VARIABLE...ESPECIALLY IN THE VALLEY OF THE SOUTHWEST COUNTY WARNING AREA. LOW LEVEL MOISTURE WAS VERY SHALLOW THIS AFTERNOON. EXPECT A CLEAR SKY...EVEN IN THE WESTERN MOUNTAINS THIS EVENING. CLOUDS COVER FILLS BACK IN FROM THE WEST WEDNESDAY AFTERNOON...MAINLY MID AND HIGH CLOUDS. WITH SURFACE DEW POINTS IN THE SINGLE DIGITS...EVEN A BRIEF LULL IN THE WINDS WOULD ALLOW TEMPERATURES TO DROP QUICKLY. STAYED TOWARD COOLER GUIDANCE...ESPECIALLY IN THE VALLEYS. IF RIDGES STAY WELL MIXED...MINIMUM TEMPERATURES MAY END UP BEING SLIGHTLY WARMER. WILL BE STARTING OUT UNSEASONABLY COLD WEDNESDAY MORNING AND WITH CLOUDS MOVING IN LATER IN THE DAY HEATING MAY BE LIMITED. WILL GO WITH COOLER BIAS CORRECTED GUIDANCE FOR MAXIMUM TEMPERATURES.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
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AS OF 150 PM EST TUESDAY... AXIS OF THE ARCTIC HIGH WILL CONTINUE TO SINK SE OF THE AREA WEDNESDAY NIGHT IN RESPONSE TO THE NEXT UPSTREAM 5H TROUGH THAT WILL PROPEL ANOTHER COLD FRONT TOWARD THE AREA BY EARLY THURSDAY. THIS WILL ACT TO TIGHTEN THE PRESSURE GRADIENT ACROSS THE AREA AGAIN OVERNIGHT WITH MODELS SHOWING A GOOD 40-45 KT 85H JET IN PLACE. HOWEVER WITH QUITE A BIT OF HIGH/MID CLOUDS ABOVE A RATHER HIGH FORECAST INVERSION EXPECT ONLY THE RIDGES WILL SEE MUCH OF THE WIND MIX DOWN BEFORE THE FRONT ARRIVES ACROSS THE NW LATE. COMBO OF THE TWO LIKELY TO HOLD TEMPS UP WITH RANGE FROM 20S VALLEYS/EAST TO PERHAPS ONLY THE LOW-MID 30S AT ELEVATION WHERE MORE IN THE WAY OF A GUSTY WEST WIND POSSIBLE. MODELS SUGGEST A SWATH OF PRE-FRONTAL LOW LEVEL MOISTURE WILL ARRIVE ALONG THE NW SLOPES AFTER MIDNIGHT WITH PERHAPS ENOUGH DEPTH TO SUPPORT A FEW UPSLOPE AIDED SNOW SHOWERS MAINLY BLF NORTH INTO EARLY THURSDAY. THUS KEPT IN LOW CHANCE POPS MAINLY IN THE 09Z-16Z WINDOW ACROSS THE EXTREME NW...WITH MOISTURE FADING CROSSING THE RIDGES...MAKING FOR MOSTLY SUNNY SKIES BUT GUSTY WINDS BLUE RIDGE EAST ON THURSDAY. PASSAGE OF THE WEAK BOUNDARY WILL ACT TO STYMIE THE SLOW WARMUP WITH A SLIGHT SOUTHWARD SHIFT IN COLD ADVECTION INTO THURSDAY EVENING AS THE CORE OF THIS NEXT SHOT OF ARCTIC AIR PASSES NORTH WHILE HOLDING THE 85H BAROCLINIC ZONE TROFFINESS OVERHEAD. THIS ALONG WITH CLOUDS SHOULD KEEP THE FAR WEST MOSTLY IN THE 30S FOR HIGHS WITH 40S OUT EAST THURSDAY AFTERNOON. ANY LINGERING LOW LEVEL MOISTURE LOOKS TO SLOWLY FADE THURSDAY NIGHT INTO FRIDAY IN RESPONSE TO HIGH PRESSURE BUILDING IN ALONG WITH BETTER SUBSIDENCE WITHIN A WEAKER DOWNSLOPING FLOW. HOWEVER WITH THE SURFACE RIDGE ABOUT OVERHEAD APPEARS BETTER RADIATIONAL COOLING IN STORE THURSDAY NIGHT WHEN LIKELY TO SEE SOME MID/UPPER TEENS TO LOW 20S WEST...AND MOSTLY MID/UPPER 20S INTO THE PIEDMONT. MORE SUNSHINE AND SLOW WARMING ALOFT SHOULD HELP TEMPS BOUNCE BACK INTO THE 40S MOST SPOTS FRIDAY WITH HEATING OF DRY AIR POSSIBLY HELPING PUSH 50 SE.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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AS OF 300 PM EST TUESDAY... LOOKING INTO SATURDAY MORNING...HIGH PRESSURE WILL SHIFT EAST OFF THE NEW ENGLAND COAST...WITH WINDS FROM THE SOUTHEAST ACROSS OUR AREA. UNDERCUT MODEL GUIDANCE A FEW DEGREES FOR AFTERNOON HIGHS AS COOLER MARINE AIR CONTINUES TO FLOW INTO THE AREA...COMBINED WITH INCREASING UPPER LEVEL CLOUDS DURING THE AFTERNOON TO LIMIT HEATING. WILL BE LOOKING FOR HIGHS RANGING FROM THE MID 40S TO LOW 50S AREAWIDE. WINDS WILL SHIFT MORE SOUTHERLY DURING LATE EVENING... MAKING FOR A STRONG RETURN OF MOISTURE ACROSS THE MID ATLANTIC. EXPECT LIGHT RAIN AND/OR DRIZZLE TO DEVELOP ACROSS THE REGION EARLY SUNDAY MORNING. MAY SEE A FEW POCKETS OF LIGHT FREEZING RAIN ACROSS THE ALLEGHANY HIGHLANDS...BUT THESE SHOULD BE ISOLATED AND ARE HARD TO PINPOINT AT THIS TIME...IF THEY DEVELOP AT ALL. A DEEP LOW PRESSURE SYSTEM WILL PASS NORTH ALONG THE MISSISSIPPI VALLEY SUNDAY MORNING. RAIN WILL BECOME WIDESPREAD ACROSS OUR AREA BY EARLY AFTERNOON...AND MAY BE HEAVY AT TIMES. IN ADDITION...WILL ALSO BE ON THE LOOKOUT FOR THE POSSIBILITY OF SEVERE WEATHER DUE TO THE DEEP SHEAR ASSOCIATED WITH THE SYSTEM. AT THIS POINT...BETTER CHANCES FOR STRONG STORMS WOULD BE LOCATED ACROSS THE MOUNTAINS... WHERE THE HIGHER SHEAR AND HELICITY ASSOCIATED WITH A SUPPORTING NEGATIVELY TILTED TROUGH IS LOCATED. WITH RAIN ENTERING EARLY IN THE DAY...AGAIN UNDERCUT GUIDANCE FOR AFTERNOON HIGHS...WITH MOST LOCATIONS HOLDING IN THE 50S. WINDS WILL SHIFT SOUTHWESTERLY WITH THE PASSAGE OF THIS LOW PRESSURE SYSTEM ON SUNDAY EVENING...AND EXPECT STRONGER HEATING DURING MONDAY AFTERNOON AS HIGHS RANGE FROM THE LOW 60S WEST TO AROUND 70 EAST. EXPECT A COLD FRONT TO ARRIVE AS EARLY AS MONDAY NIGHT TO RETURN OUR TEMPERATURES CLOSER TO NORMAL...HOWEVER THE WEATHER FORECAST MODELS ARE STILL TRYING TO GET A HANDLE ON FRONTAL PASSAGE TIMING
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&& .AVIATION /21Z TUESDAY THROUGH SUNDAY/... AS OF 1225 PM EST TUESDAY... GUSTY WEST TO NW WINDS WILL CONTINUE THROUGH THE EARLY AFTERNOON BEFORE WINDING DOWN AFTER DUSK. SUSTAINED WINDS OF 10 TO 20 KNOTS...WITH GUSTS TO 20 TO 30 KTS WILL BE COMMON THIS AFTERNOON. EXPECT WINDS TO TAPER DOWN TO AROUND 5 TO 10 KNOTS AFTER MIDNIGHT. AREA RADAR STILL SHOWING LIGHT SNOW SHOWERS IN SOUTHEAST WEST VIRGINIA. THERE MAY BE BRIEF PERIODS OF MVFR VISIBILITY SNOW SHOWERS AT KLWB OR KBLF UNTIL 21Z/4PM. CLOUDS COVER WILL DIMINISH THIS EVENING AS MOISTURE BECOMES VERY SHALLOW. THE UNSEASONABLY COLD AIR MASS WILL LIFT NORTHEAST AS SURFACE HIGH PRESSURE BUILDS IN FROM THE LOWER MISSISSIPPI VALLEY. VFR CONDITIONS ARE EXPECTED ACROSS THE REGION TONIGHT AND WEDNESDAY. HIGH CONFIDENCE ON BOTH WIND AND CLOUD COVER FORECAST THROUGH THE TAF PERIOD. EXTENDED DISCUSSION... EXPECT MAINLY VFR WEATHER THROUGH WEDNESDAY. NEXT SYSTEM ARRIVES THURSDAY MORNING WITH MVFR CIGS IN THE MTNS. THURSDAY NIGHT THROUGH SATURDAY WILL AGAIN BE VFR WITH HIGH PRESSURE IN THE REGION. A MORE SIGNIFICANT SYSTEM WILL APPROACH THE AREA WITH RAIN AND SUB-VFR CONDITIONS POSSIBLE ON SUNDAY. && .CLIMATE...
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AS OF 335 PM EST TUESDAY... NOVEMBER 19TH: RECORD LOWS... FORECAST LOW BLACKSBURG VA...13 IN 1997 12 BLUEFIELD WV....14 IN 2008 10 DANVILLE VA.....21 IN 2005 19 ROANOKE VA......21 IN 1951 18 LEWISBURG WV....16 IN 2005 11 LYNCHBURG VA....20 IN 2005 15
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&& .EQUIPMENT... AS OF 1230 PM EST TUESDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. KFCX RADAR HAS RETURNED TO SERVICE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/MBS NEAR TERM...AMS SHORT TERM...JH LONG TERM...NF AVIATION...AMS/WP CLIMATE...RCS/WP/JH/AMS EQUIPMENT...AMS/WERT/WP

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