Area Forecast Discussion
Issued by NWS Blacksburg, VA

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874 FXUS61 KRNK 141037 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 537 AM EST SUN FEB 14 2016 .SYNOPSIS... COLD HIGH PRESSURE MOVES EAST AND OFF THE MID ATLANTIC COAST BY TONIGHT. A WARM FRONTAL BOUNDARY WORKS TOWARD THE TENNESSEE VALLEY BY THIS EVENING WITH SNOW MOVING INTO THE MOUNTAINS. BY MONDAY...LOW PRESSURE WORKS FROM THE LOWER MISSISSIPPI VALLEY TO THE SOUTHERN APPALACHIANS. WITH COLD AIR IN PLACE EXPECT SNOW CHANGING TO A WINTRY MIX MONDAY INTO MONDAY NIGHT. THIS SYSTEM MOVES EAST BY TUESDAY AFTERNOON. && .NEAR TERM /THROUGH TONIGHT/... AS OF 400 AM EST SUNDAY... WIND CHILL ADVISORY CANCELLED EARLY AS WINDS HAVE DROPPED FOR MOST OF THE AREA TO BELOW 5 MPH. ONLY AREAS WITH NEAR WIND CHILL ADVISORY LEVELS ARE ELEVATIONS ABOVE 3500 FT LIKE HOT SPRINGS...SO MAJORITY OF THE AREA WILL STAY WARMER...THAN -5F THROUGH THE MORNING. NOW OUR EYES FOCUS ON THE WINTER STORM THREAT TAKING SHAPE OVER THE MIDDLE PART OF THE COUNTRY EARLY THIS MORNING. MODELS SHOW DECENT AGREEMENT IN BRINGING LIGHT SNOW TOWARD THE MOUNTAIN EMPIRE OF SW VA INTO NW NC BY LATE AFTERNOON...THEN SHIFTING IN BANDS EAST ACROSS THE NEW RIVER VALLEY INTO THE PIEDMONT. AIRMASS WILL STAY VERY COLD WITH THERMAL PROFILE STAYING BELOW ZERO THROUGH 12Z MONDAY. HENCE WILL SEE SNOW THROUGH TONIGHT. QUESTION REMAINS ON HOW ANY MESOSCALE BANDS WILL LINE UP. MODELS FAVOR A MTN EMPIRE TO ALLEGHANY HIGHLAND CORRIDOR FOR HEAVIER SNOW BAND POTENTIAL BY MIDNIGHT TONIGHT. SMALLER BAND SHOULD SLIDE EAST TO THE PIEDMONT THROUGH THE NIGHT. THIS ARCTIC AIRMASS IN PLACE SHOULD START THE SNOW TO LIQUID RATIOS PRETTY HIGH IN THE 20:1 RANGE...DROPPING TOWARD 15:1 BY 12Z MONDAY. SNOWFALL TOTALS LATE THIS AFTERNOON THROUGH TONIGHT WILL RANGE FROM 6 TO 10 INCHES WEST OF THE BLUE RIDGE TO 2 TO 5 INCHES EAST. WE HAVE GONE WITH A WINTER STORM WARNING TO ACCOUNT FOR SNOW IN THE WEST...WITH MIX OF SNOW/SLEET AND FREEZING RAIN IN THE EAST. MORE DETAILS ON THE WINTRY MIX PART OF THE STORM WILL BE MENTIONED IN THE SHORT TERM DISCUSSION BELOW. LOOK FOR INCREASING CLOUDS TODAY WITH HIGHS IN THE LOWER TO MID 20S WEST TO UPPER 20S EAST. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 400 AM EST SUNDAY... STARTING THE PERIOD IN THE MIDDLE OF A WINTER STORM. THE BAND OF ISENTROPIC LIFT NORTH OF A WARM FRONT TO OUR SOUTH SHOULD CONTINUE INTO THE AFTERNOON. MOST AREAS SHOULD STILL SEE SNOW AT 12Z MON AS THE ENTIRE COLUMN OF THE SOUNDING IS BELOW FREEZING THROUGHOUT THE CWA. LEANING TOWARD THE COLDER NAM FOR TEMPERATURES AND THE GFS FOR STORM TRACK AND QPF...SHOULD SEE PRECIPITATION CHANGING TO SLEET ACROSS THE PIEDMONT AND SOUTHSIDE AROUND MIDDAY OR EARLY AFTERNOON...GRADUALLY WORKING ITS WAY NORTH AND WEST TOWARD THE BLUE RIDGE AS THE DAY PROGRESSES. STILL CONCERNED GIVEN THE INTENSITY OF THE ANTECEDENT ARCTIC COLD AIR MASS...THAT IT WILL NOT RECOVER AS QUICKLY AS THE MODELS INDICATE...ESPECIALLY THE GFS. LIKE THE WAY THE NAM HOLDS ONTO THE COLD LAYER AT THE SURFACE...EVEN ACROSS SOUTHSIDE...WELL INTO EARLY TUESDAY MORNING. A DECREASE IN PRECIPITATION APPEARS LIKELY MONDAY EVENING AS THE BEST ISENTROPIC LIFT SHIFTS NORTH IN RESPONSE TO INCREASING MID- LEVEL WARM ADVECTION AS A SOUTHERN STREAM SHORT WAVE INDUCES A DEEPENING AREA OF LOW PRESSURE ACROSS THE CUMBERLAND PLATEAU. A DRY SLOT IS EVIDENT AMONG MOST MODELS...SPREADING INTO THE REGION FROM THE NC FOOTHILLS/PIEDMONT AREA DURING THE EVENING. THIS WILL RESULT IN A DECREASE IN SYNOPTIC-SCALE INDUCED PRECIPITATION...RESULTING IN MUCH OF THE AREA SEEING A CHANGE OVER TO FREEZING DRIZZLE DURING THE EVENING. OVERNIGHT...INTO TUESDAY MORNING...THE MAIN SYNOPTIC SYSTEM LIFTS THROUGH THE REGION AS THE SURFACE LOW MOVES NORTH INTO THE EASTERN OH VALLEY. QPF IS HIGHEST DURING THIS TIME FRAME...AVERAGING AROUND 1/2 INCH FOR MUCH OF THE CWA. BY THIS TIME...PRECIPITATION SHOULD BE MOSTLY SNOW/SLEET GREENBRIER VALLEY/I-64 AREA...SLEET NEW RIVER VALLEY...SLEET/FREEZING RAIN/RAIN FAR SW VA...AND FREEZING RAIN/RAIN PIEDMONT/SOUTHSIDE. WILL NEED TO WATCH THIS PERIOD VERY CAREFULLY IF WARMING IS NOT AS ADVERTISED OR GREATER THAN EXPECTED...AS THIS WILL RESULT IN SUBSTANTIAL CHANGES IN AMOUNTS OF SNOW/SLEET/ICE. EXPECTING ALL SNOW MOST AREAS THROUGH 18Z MON...THEN SNOW/SLEET/FREEZING RAIN ENCROACHING FROM THE S/SE/SW REMAINDER OF THE PERIOD...HAVE USED TOP DOWN PROCEDURE FOR 18Z MON ONWARD...AND GENERALLY SNOW AMOUNTS FROM QPF AND THICKNESS AFTER 18Z. GIVEN CONSIDERATION FOR SLEET ACCUMULATIONS...HAVE LOWERED SNOW/LIQUID RATIOS TO MUCH LESS THAN 10/1 DURING THE LATER HALF OF THE EVENT. ALL OF THIS IN CONSIDERATION...HAVE ISSUED A WINTER STORM WARNING FOR THE ENTIRE CWA AS NOTED ABOVE AS IN AREAS WHERE THE SNOW ACCUMULATIONS DO NOT MEET CRITERIA...SNOW/SLEET/ICE ACCUMULATIONS SHOULD. QUICKLY ON THE HEELS OF THE MAIN WEATHER SYSTEM IS A STRONG ALBERTA CLIPPER THAT APPEARS DESTINED TO BRING ADDITIONAL SNOWFALL TO THE REGION...ESPECIALLY WEST OF THE BLUE RIDGE. AS ONE WOULD TYPICALLY EXPECT FROM THIS TYPE OF SYSTEM...THE BULK OF THE SNOWFALL WILL BE ACROSS THE ALLEGHANYS DOWN THROUGH THE CUMBERLAND MOUNTAINS OF SW VA INTO THE BLUE RIDGE MOUNTAINS OF NORTHWEST NC. AN ADDITIONAL 1-4 INCHES OF SNOW APPEARS POSSIBLE AS A RESULT OF THIS CLIPPER. TEMPERATURES WILL REMAIN WELL BELOW NORMAL AND MOSTLY BELOW FREEZING MONDAY...CLOSER TO NORMAL VALUES FOR TUE-WED. NO SIGNIFICANT WARMING IS EXPECTED THROUGH THIS PERIOD BY ANY MEANS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 530 AM EST SUNDAY... A QUIETER WEATHER PERIOD...AND POTENTIALLY WARMER. NORTHWEST FLOW ALOFT REMAINS OVER THE REGION...SO AM RELUCTANT TO INDICATE TOO MUCH WARMING. MAIN FOCUS THIS MORNING WAS ON THE WINTER STORM...SO NO SIGNIFICANT CHANGES WERE MADE TO THE LONG TERM FORECAST AT THIS TIME. PREVIOUS VALID DISCUSSION... CHILLY HIGH PRESSURE BUILDS OVERHEAD AND TO THE NORTH EARLY THURSDAY RESULTING IN A COLD BUT DRY START WITH LOWS 20S TO A FEW TEENS VALLEYS. SHORTWAVE RIDGING BUILDS IN LATER THURSDAY AND LINGERS INTO FRIDAY BEFORE THE NEXT TROUGH AND ASSOCIATED COLD FRONT ARRIVE FOR DAY 7. WITH GRADUAL WARMING ALOFT ON THURSDAY SHOULD SEE TEMPS RETURN TO MORE SEASONAL LEVELS UNDER SUNSHINE BEFORE MUCH WARMER AIR SURGES IN FRIDAY INTO SATURDAY AHEAD OF THE FRONT. THIS SHOULD FINALLY PUSH HIGHS INTO THE 40S AND 50S UNDER INCREASING RETURN SW FLOW FRIDAY...AND POSSIBLY 50S TO NEAR 60 PIEDMONT SATURDAY DESPITE MORE CLOUDS AND PERHAPS A FEW MOUNTAIN RAIN SHOWERS. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... AS OF 1201 AM EST SUNDAY... VFR ANTICIPATED THROUGH LATE SUNDAY AFTERNOON WITH HIGH CLOUDS BECOMING MID DECK BY 12Z THEN LOW END VFR BY 18-22Z. WARM FRONT AND SNOW WILL MOVE INTO THE WESTERN AREAS BY 22Z...AND SHIFT EAST BY THE END OF THIS TAF PERIOD. LOOK FOR VSBYS/CIGS TO DROP TO MVFR AND LOWER ESPECIALLY WEST OF THE BLUE RIDGE BY 06Z. WINDS LIGHT OR FROM THE NW SWING TO THE EAST AND SOUTHEAST SUNDAY AFTERNOON...SOME GUSTS OVER BLF TO 20KTS AFTER 00Z MON. EXTENDED DISCUSSION... WINTER STORM IS EXPECTED TO IMPACT THE AREA WITH WINTRY PRECIPITATION INTO TUESDAY. CONFIDENCE IS HIGH THAT POOR FLYING CONDITIONS WILL EXIST FROM SUNDAY NIGHT THROUGH TUESDAY. THIS WINTER STORM WILL PRODUCE A VARIETY OF WINTRY PRECIPITATION...STARTING AS SNOW SUNDAY NIGHT...THEN TRANSITIONING TO SLEET AND FREEZING RAIN MONDAY. AFTER THE EARLY WEEK WINTER STORM...THERE IS ANOTHER CLIPPER SYSTEM THAT MAY IMPACT THE AREA FOR MID WEEK...POSSIBLY RESULTING IN THE CONTINUATION OF POOR FLYING CONDITIONS THROUGH WEDNESDAY. HIGH PRESSURE BUILDS IN THURSDAY WITH VFR RETURNING. && .CLIMATE... COLDEST AIR OF THE SEASON HAS SETTLED OVER THE MID ATLANTIC REGION. SEVERAL RECORD LOW MAX TEMPERATURES AND LOW TEMPERATURES ARE POSSIBLE. BELOW ARE THE CURRENT RECORDS FOR SUNDAY 2/14. LOOKS LIKE BLF TIED A RECORD LOW FOR 2/13. SUNDAY 02/14/2016 SITE MINT YEAR LOMAX YEAR KBLF 5 1971 16 1960 KDAN 15 1986 32 1986 KLYH 4 1899 24 1905 KROA 10 1943 26 1986 KRNK -2 1969 24 1986 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST TUESDAY FOR VAZ007-009>020-022>024-032>035-043>047-058- 059. NC...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST TUESDAY FOR NCZ001>006-018>020. WV...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST TUESDAY FOR WVZ042>044-507-508. && $$ SYNOPSIS...JH/WP NEAR TERM...WP SHORT TERM...RAB LONG TERM...JH AVIATION...PM/WP CLIMATE...CF

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