Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310445 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1145 PM EST FRI JAN 30 2015 .SYNOPSIS... COLD HIGH PRESSURE WILL GRADUALLY BUILD EAST INTO THE AREA TONIGHT AND ABOUT OVERHEAD ON SATURDAY. THIS WILL ALLOW FOR DRIER WEATHER UNDER DIMINISHING WINDS LATER TONIGHT INTO SATURDAY. ANOTHER AREA OF LOW PRESSURE WILL MOVE OUT OF THE SOUTHWESTERN UNITED STATES ON SATURDAY...CROSSING THE CENTRAL PART OF THE NATION SUNDAY...AND REACHING THE EAST COAST BY MONDAY MORNING. && .NEAR TERM /THROUGH SATURDAY/...
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AS OF 1135 PM EST FRIDAY... WIND ADVISORY WILL EXPIRE AT MIDNIGHT FOR THE NORTH CAROLINA MOUNTAINS INTO GRAYSON HIGHLANDS. WINDS HAVE DIMINISHED TO UNDER 35 MPH OVERALL IN GUSTS. HIGH PRESSURE WAS OVER THE OHIO VALLEY AND WILL SHIFT EAST INTO THE MOUNTAINS BY SATURDAY MORNING...CAUSING WINDS TO SUBSIDE MORE. SKIES WILL BE MAINLY CLEAR WITH A FEW STRATOCU LINGERING IN THE MTNS OF GREENBRIER COUNTY. WIND CHILLS STILL LOOK LIKE THEY WILL HIT THE -5 TO -10 F THRESHOLD IN THE MTNS OF BATH AND GREENBRIER...SO NO CHANGES TO THE ONGOING WIND CHILL HEADLINES OVERNIGHT. PREVIOUS VALID DISCUSSION... EXPECT ENOUGH COLD ADVECTION TO CAUSE TEMPS TO FALL INTO THE TEENS WITH A FEW SINGLE DIGITS MOUNTAINS...AND UPPER TEENS TO LOW 20S EAST DESPITE CONTINUED MIXING FOR MUCH OF THE AREA. SURFACE HIGH BUILDS OVERHEAD SATURDAY UNDER DEVELOPING ZONAL FLOW ALOFT ALLOWING FOR LIGHTER WINDS AND WARMER TEMPS GIVEN 85H WARMING. SOME INCREASE IN WARM ADVECTION MID/HIGH CLOUDS LIKELY BY MID/LATE AFTERNOON UNDER THE FAST FLOW ALOFT FROM THE WEST BUT OVERALL MOSTLY SUNNY. WITH WEAK DOWNSLOPE/DRY AIR...WENT ON THE WARMER SIDE OF MOST ESPCLY EAST WHERE LOW/MID 40S LIKELY WHILE KEEPING THE WEST MAINLY 30S TO AROUND 40 GIVEN THE 85H NW TRAJECTORY.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AS OF 240 PM EST FRIDAY... A LARGE AREA OF HIGH PRESSURE WILL MOVE SOUTH ACROSS THE REGION SATURDAY AND BE CENTERED NEAR THE SOUTH CAROLINA COAST SUNDAY MORNING. THIS HIGH PRESSURE WILL STILL HAVE AN INFLUENCE ON OUR WEATHER KEEPING DRY AIR...DEW POINTS IN THE TEENS...IN THE REGION. A WARM FRONT ALOFT WILL TRACK ACROSS THE OHIO VALLEY EARLY SUNDAY MORNING. ISENTROPIC LIFT MAY GENERATE PRECIPITATION ACROSS THE GREENBRIER VALLEY TO THE ALLEGHANY HIGHLANDS SUNDAY MORNING AS THIS WARM FRONT TRACKS NORTH TO THE MASON-DIXON LINE DURING THE DAY SUNDAY. ANY PRECIPITATION FALLING INTO THIS DRY AIR WILL KEEP THE AIR COLUMN COLD ENOUGH FOR LIGHT SNOW TO FALL IN THE MORNING. THIS PRECIPITATION WILL MOVE NORTH OF THE AREA BY NOON. THE ENTIRE AREA WILL BE IN THE WARM SECTOR SUNDAY AFTERNOON WITH TEMPERATURES WARMING INTO THE 40S WEST AND LOWER 50S EAST. ALSO ON SUNDAY...A NORTHERN STREAM TROUGH WILL COME OUT OF THE ROCKIES SPAWNING A SURFACE LOW OVER THE RED RIVER VALLEY OF TX. THIS LOW WILL THEN TRACK TO THE OZARKS SUNDAY MORNING...THEN OVER THE SOUTHERN OHIO VALLEY IN THE AFTERNOON. THE CURRENT TRACK OF THIS LOW WILL KEEP THE AREA IN A WARM AIRMASS THROUGH THE DAY SUNDAY. SHORT WAVES AND SOUTHEAST FLOW WILL BRING LIGHT SHOWERS INTO THE AREA DURING THE AFTERNOON. PRECIPITATION FALLING IN THE AFTERNOON SHOULD KEEP TEMPERATURES MILD WHILE DEW POINTS AND WET BULB INCREASE INTO THE 30S. DEPENDING ON HOW FAST PRECIPITATION MOVES INTO THIS DRY AIR IT MAY START OUT AS A BRIEF PERIOD OF A SNOW/SLEET MIX...BUT WILL TRANSITION OVER TO A COLD RAIN. MODELS CONTINUE TO TRACK THE SURFACE LOW NORTH OF THE AREA AND ACROSS NORTHERN VIRGINIA/MARYLAND SUNDAY NIGHT. SOUTHERLY FLOW WILL CONTINUE TO BRING WARM AIR INTO THE REGION WITH 85H TEMPERATURES 4C OR WARMER. THE COLD FRONT DOES NOT ENTER RNK MOUNTAIN COUNTIES UNTIL EARLY MONDAY MORNING. THEREFORE WILL DELAY CHANGE-OVER TO SNOW UNTIL AFTER MIDNIGHT ACROSS SOUTHEASTERN WEST VIRGINIA. THE SURFACE LOW TRACKS OFF THE MID ATLANTIC COAST MONDAY MORNING WITH PRECIPITATION ENDING OVER THE PIEDMONT BY NOON. THE UPPER LEVEL PORTION OF THIS SYSTEM WILL TRACK OVER THE FORECAST AREA DURING THE AFTERNOON. THE DEFORMATION ZONE AND BRIEF UPSLOPE WILL BRING SCATTERED SNOW SHOWERS TO THE MOUNTAINS THROUGH THE AFTERNOON...THEN HIGH PRESSURE MOVES OVER THE OHIO VALLEY SHUTTING OFF MOISTURE FEED. FOLLOWING THE FRONT...A SURGE OF ARCTIC AIR WILL SEND TEMPERATURES DOWN THROUGH THE DAY MONDAY. MORNING HIGHS IN THE 30F-35F RANGE IN THE WEST TO A LATE MORNING MAX IN THE EAST IN THE M/U 40S. ALSO BEHIND THE FRONT...STRONG PRESSURE RISES AND COLD AIR ADVECTION WILL BRING HIGH WINDS AND GUSTY CONDITIONS TO THE AREA. ONLY THING LACKING FOR A HIGH CONFIDENCE HIND WIND WATCH/WARNING IS A STRONG LOW LEVEL JET. MODELS ARE ONLY DISPLAYING A 40KT JET OVER THE BLUE RIDGE WITH HIGHER SPEEDS TO THE NORTH. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 320 PM EST FRIDAY... THE LONG TERM PERIOD BEGINS QUIET WITH COLD HIGH PRESSURE DRIFTING ACROSS THE REGION BEHIND THE EARLY WEEK COASTAL LOW. 850MB TEMPS BOTTOM OUT EARLY TUE MORNING IN THE -13C RANGE GREENBRIER COUNTY TOWARD -6C ACROSS THE PIEDMONT. RADIATIONAL COOLING UNDER THE SFC HIGH SHOULD BE IDEAL...ESPECIALLY WESTERN AREAS WHERE THERE SHOULD BE AMPLE SNOW COVER ON THE GROUND...LEADING TO LOW TEMPS IN THE SINGLE DIGITS VALLEYS WESTERN MOUNTAINS TO THE UPPER TEENS AND LOW 20S ACROSS THE PIEDMONT. GIVEN THAT THE AIR MASS IS NOT BITTERLY COLD...AS IN SOME PREVIOUS EVENTS WITH 850MB TEMPS -20C OR BETTER...AS HIGH PRESSURE SLIDES EAST OF THE REGION BY AFTERNOON/EVENING...WE SHOULD SEE TEMPERATURES MODERATE IN THE 30S WEST TO LOWER 40S EAST. WEDNESDAY...OUR ATTENTION TURNS TO THE NEXT POTENTIAL WINTER WEATHER SYSTEM. AS WITH THE PAST SEVERAL...THERE DO NOT APPEAR TO BE ANY CLEAR ANSWERS FOR THIS EVENT EITHER. DISTINCT NORTHERN STREAM AND SOUTHERN STREAM SYSTEMS ARE EVIDENT WED...WITH AN ARCTIC COLD FRONT FROM NEAR CHI-MCI...REASONABLY CONSISTENT AMONG BOTH MODELS. WHAT IS NOT CONSISTENT...HOWEVER...IS A POTENT SOUTHERN STREAM SYSTEM. THE GFS HAS THIS SYSTEM RACING INTO THE SOUTHEAST STATES...WHILE THE ECMWF STILL HAS THIS BACK ALONG THE TX COAST. THE ECMWF TRACKS THIS FEATURE WELL SOUTH KEEPING IT ACROSS GA/SC...THEN INTO THE WESTERN ATLANTIC AS IT PLUNGES AN ARCTIC HIGH SOUTHEAST INTO THE OH/TN VALLEY...CLEARLY FOCUSING ON THE NORTHERN STREAM. MEANWHILE...THE GFS TRACKS THIS NORTHEAST TOWARD THE SC/NC COAST AND GENERATES A COASTAL LOW NEAR THE OUTER BANKS OF NC. THE GFS HAS AN EQUIVALENT ARCTIC HIGH...BUT HOLDS IT BACK NORTH IN THE UPPER MIDWEST UNTIL A SECONDARY SHORT WAVE LIFTS OUT OF THE CENTRAL PLAINS. HENCE...THERE ARE CONSIDERABLE DIFFERENCES BETWEEN THE PRECIPITATION AMOUNTS ADVERTISED WITH THESE TWO PATTERNS. THE GFS WOULD SUGGEST WIDESPREAD RAIN/SNOW TRACKING ACROSS MUCH OF THE CWA WED NIGHT/THU...WITH UPSLOPE SNOW SHOWERS INTO THU/FRI. MEANWHILE...THE ECMWF SOLUTION WOULD INDICATE LITTLE MORE THAN SOME LIGHT SNOW ALONG THE ARCTIC FRONT...FOLLOWED BY TYPICAL UPSLOPE MOUNTAIN SNOW SHOWERS INTO THU. HAVE TAKEN A MIDDLE OF THE ROAD APPROACH FOR NOW...WHICH GENERALLY AGREES WITH THE SUPERBLEND OUTPUT...AS OPPOSED TO ANY ONE MODEL. IF THE GFS SOLUTION IS RIGHT...THERE IS MORE SIGNIFICANT POTENTIAL FOR WINTER PRECIPITATION ACROSS THE CWA...AND AGAIN ISSUES WITH P-TYPE. FOR THE REMAINDER OF THE EXTENDED...THE NEXT SYSTEM OF INTEREST DOES NOT ARRIVE UNTIL LATE IN THE WEEKEND OR EARLY NEXT WEEK...SO AT THIS POINT THE WEEKEND LOOKS DRY WITH NEAR TO BELOW NORMAL TEMPERATURES. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 1120 PM EST FRIDAY... PRIMARILY WILL BE DEALING WITH A FEW MORE HOURS OF GUSTY WINDS IN THE MTNS BEFORE HIGH PRESSURE BRINGS WEAKER WINDS BY SATURDAY MORNING. LOOKING AT VFR CONDITIONS WITH INCREASING HIGH CLOUDS SATURDAY...WITH MORE ALTOCU OR ALTOSTRATUS ARRIVING BY DUSK IN THE WEST...AHEAD OF OUR NEXT WX MAKER FOR SUNDAY. EXTENDED DISCUSSION... THE NEXT LOW PRESSURE SYSTEM HEADING OUT OF THE SW STATES WILL BRING A RETURN OF CLOUDS AND PRECIPITATION ON SUNDAY WITH WIDESPREAD MVFR TO IFR CIGS/VSBYS LIKELY WITHIN THIS TIME FRAME. THE NORTHERN SECTIONS OF THE CWA WILL LIKELY SEE SOME WINTER PRECIPITATION WITH THIS EVENT...WHILE THE SOUTHERN AREAS SHOULD SEE MOSTLY RAIN. IN BETWEEN...LOCATIONS SUCH AS KBCB/KROA/KLYH...COULD SEE A BRIEF MIX OF RAIN AND SNOW AT THE ONSET WITH MOSTLY A RAIN EVENT OVERALL. MOUNTAIN SNOW SHOWERS WITH MVFR CIGS/VSBYS WILL CONTINUE INTO MONDAY...WITH STRONG AND GUSTY WINDS ALL AREAS BY MONDAY AFTERNOON. IMPROVING CONDITIONS ARE EXPECTED BY TUESDAY AND WEDNESDAY WITH VFR RETURNING FOR ALL LOCATIONS UNDER HIGH PRESSURE.
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&& .RNK WATCHES/WARNINGS/ADVISORIES...
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VA...WIND CHILL ADVISORY UNTIL 9 AM EST SATURDAY FOR VAZ020. NC...NONE. WV...WIND CHILL ADVISORY UNTIL 9 AM EST SATURDAY FOR WVZ507-508.
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&& $$ SYNOPSIS...JH/PM NEAR TERM...JH/WP SHORT TERM...RCS LONG TERM...RAB AVIATION...JH/PM/WP

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