019 FXUS61 KRLX 191555 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1036 AM EST SUN FEB 19 2012 .SYNOPSIS... LOW PRESSURE PASSES WELL SOUTH OF THE AREA INTO TONIGHT...WITH ACCUMULATING SNOW OVER THE SOUTHEAST HALF OF THE AREA. HIGH PRESSURE CROSSES MONDAY. UNSETTLED PERIOD STARTS WITH COLD FRONT LATE TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... SOUTHWARD MODEL TRENDS OF HEAVIEST SNOW CONTINUE...HAVE REMOVED 4 COUNTIES FROM NORTHWESTERN EDGE OF ADVISORIES....ESPECIALLY WITH THE WARM GROUND. WHILE WINTER POTENTIAL ACCORDING TO MODELS IS ALSO DECREASING ELSEWHERE...WILL RETAIN THE REST OF THE HEADLINES AS THE WINDOW OF OPPORTUNITY HAS NOT YET CLOSED FOR BURSTS OF HEAVY SNOW THIS AFTERNOON TO TEMPORARILY OFFSET WARM GROUND AND MARGINAL SURFACE TEMPS. WATER VAPOR IMAGERY TRENDS INDICATE THE NORTHERN STREAM KICKER FOR OUR SOUTHERN STREAM SYSTEM MAY YET DIG IN BEHIND THE SYSTEM A LITTLE MORE THAN MODELS INDICATE...THUS LIFTING THINGS A BIT FURTHER NORTH. PREVIOUS DISCUSSION... VERY TRICKY FORECAST IN THE NEAR TERM. SURFACE LOW...CURRENTLY OVER SOUTHEAST UNITED STATES...WILL PUSH EAST ACROSS THE SOUTHEAST U.S...THEN PUSH TOWARDS THE CAROLINAS BEFORE FINALLY BEING PUSHED OUT TO SEA AS AN UPPER TROUGH OVER THE MIDWEST PUSHES IT EASTWARD. MOISTURE...SPREADING NORTHWARD FROM THIS LOW...WILL COMBINE WITH THE UPPER TROUGH TO THE WEST TO CREATE PRECIPITATION...MAINLY IN THE FORM OF SNOW ACROSS PARTS OF THE CWA TODAY. AS OF 08Z...DRY AIR REMAINS ACROSS THE CWA BEHIND YESTERDAYS DRY COLD FRONT. IN ADDITION...TEMPERATURES ACROSS THE CWA...PARTICULARLY ACROSS THE SOUTHERN 1/2 OF THE CWA...REMAIN IN THE MID 30S TO LOWER 40S. THESE TWO FORCES...WILL COMBINE TOGETHER TO INITIALLY LIMIT SNOWFALL THIS MORNING AS MOISTURE CONTINUES TO CREEP NORTHWARD. HOWEVER...AS THE ATMOSPHERE DOES MOISTEN FROM TOP TO BOTTOM...EXPECTING EVAPORATIVE COOLING TO TAKE HOLD...THEREBY CHANGING ANY RAIN OR RAIN/SNOW MIX INITIALLY OBSERVED THIS MORNING...TO ALL SNOW BY MID TO LATE MORNING. A FEW THINGS MAY ALSO AID IN POTENTIALLY LIMITING ACCUMULATIONS ACROSS THE AREA ESPECIALLY INITIALLY. ONE BEING THE WARM GROUND TEMPERATURES ACROSS THE AREA...AND MAY NOT SEE ANY ACCUMULATIONS INITIALLY...UNTIL THE HEAVIER BURSTS OF SNOWFALL CAN TAKE HOLD LATER TODAY. ANOTHER STILL IS THE NORTHWARD EXTENT OF MOISTURE WITH THIS SYSTEM. CURRENT RUNS ARE TRENDING FARTHER AND FARTHER SOUTH WITH PRECIP SHIELD...AND HAVE LOWERED BOTH POPS AND ACCUMULATIONS ACROSS NORTHERN/CENTRAL ZONES AS A RESULT. IN ADDITION...CURRENT RUNS SEEM TO INDICATE AREAS EAST SUCH AS RALEIGH COUNTY MAY JUST BE GRAZED BY PRECIP SHIELD...THEREBY SIGNIFICANTLY LIMITING ACCUMULATIONS THERE. WILL REMOVE LAWRENCE OHIO AND GREENUP COUNTIES FROM THE ADVISORY AS HAVE LITTLE CONFIDENCE IN MUCH IF ANY SNOWFALL IN THESE AREAS...BUT WILL KEEP REMAINING HEADLINES THE SAME. THIS WILL BE A HEAVY WET SNOW...WITH SNOW RATIOS AROUND 10-14:1...AND COULD DEFINITELY CAUSE SIGNIFICANT TRAVEL PROBLEMS AND POWER OUTAGES...ESPECIALLY OVER SOUTHERN COAL FIELDS AND SOUTHERN MOUNTAIN COUNTIES. UPPER TROUGH WILL KICK THE LOW PRESSURE SYSTEM OFF TO THE EAST LATER TONIGHT...FOR GRADUALLY DRYING AND CLEARING WEATHER. DID ELECT TO GO ON THE COLD SIDE OF GUIDANCE TONIGHT...BUT MAY NEED TO GO SLIGHTLY LOWER THAN CURRENTLY FORECAST DEPENDING ON CLEARING. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... JUST A BIT OF LEFT OVER LOW CLOUD IN THE CENTRAL AND SOUTHERN MOUNTAINS FIRST THING MON MORNING MAY MIX INTO MORNING CU BEFORE MIXING OUT ALTOGETHER. OTHERWISE HIGH PRESSURE BRINGS ABOUT CLEAR SKY AND NEAR NORMAL TEMPERATURES MON AND MON NT. QUICK MOVING S/W TROF IN FAST FLOW PUSHES SURFACE COLD FRONT THROUGH THE AREA TUE AFTERNOON AND EVENING. FRONT IS ACTUALLY OVERRUN BY UPPER SYSTEM...AND THEN WASHES OUT TUE NT...AS YET ANOTHER SYSTEM FOLLOWS QUICKLY ON ITS HEELS WED. DID INCREASE POPS AND FINE TUNE TIMING A BIT BASED ON THE SREF. BLENDED IN VARYING MIXES OF CONSALL AND ADJMET ON TEMPERATURES...WITH NO MAJOR CHANGES. BELOW GUIDANCE ON HIGHS MON AS LIGHT FLOW UNDER HIGH PRESSURE MAY NOT ALLOW FULL MIXING TO BE REALIZED. LOWERED HIGHS TUE A BIT ON ACCOUNT OF CLOUDIER FCST WITH HIGHER POPS DESPITE BETTER MIXING GIVEN STRONG FLOW. TUE SYSTEM IS ACTUALLY A BIT OF A WIND BAG. TEMPERATURES MAY START TO RISE TOWARD DAWN TUE MORNING...ESPECIALLY ON THE RIDGES...AS SW WINDS AHEAD OF THE SYSTEM INCREASE. WARM ADVECTION AHEAD OF THE SYSTEM IS NOT THAT STRONG THROUGH 12Z TUE THOUGH. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED FORECAST WILL REMAIN PROGRESSIVE WITH RAPID MOVEMENT OF SYSTEMS FROM MID WEEK THROUGH THE WEEKEND. LEANED HEAVILY ON THE WEIGHTING SCHEME FROM HPC AS THE OPERATIONAL LONG TERM MODELS HAVE AGAIN STRUGGLED BEYOND WEDNESDAY. LOOKING AT THE BROADER SCALE FOR TRENDS...THINK THAT DESPITE THE BROAD TROUGHY NATURE OF THE EASTERN CONUS...TEMPERATURES WILL LEAN TOWARDS THE MILDER SIDE...WITH THE BACKING FROM THE OUTLOOK FROM CPC. WITH THE AFOREMENTIONED ACTIVE PATTERN IN PLAY...THIS DOES NOT LEAVE MUCH ROOM FOR CLEAR DAYS AND NIGHTS...AND HAVE CLOUD COVER GENERALLY DOMINATING THE FORECAST. ALSO HAD TROUBLE COMPLETELY ELIMINATING POPS FROM THE FORECAST GIVEN THE DIFFICULTY OF THE TIMING OF THE INDIVIDUAL SYSTEMS DURING THAT PERIOD. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... 15Z SUNDAY THRU 12Z MONDAY... STORM SYSTEM TRACKS SOUTH OF OUR AREA THIS AFTERNOON AND EVENING. NORTH OF A HTS-CRW-EKN LINE MAINLY VFR CEILINGS WITH PERHAPS BRIEF FLURRIES OR VERY LIGHT SNOW/RAIN. SOUTH OF THIS LINE...MVFR TO IFR IN MAINLY SNOW. HEAVIEST SNOW AND LIFR MOST LIKELY ALONG AND SOUTH OF JKL-BKW LINE. LOW PRESSURE WILL MOVE OFF TO THE EAST TONIGHT...WITH PRECIPITATION DECREASING FROM WEST TO EAST AFTER 00Z. EXPECTING A RETURN TO VFR CONDITIONS AREA WIDE AFTER 06Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: NORTHWARD EXTENT OF MVFR AND IFR IN SNOW DEPENDS ON EXACT TRACK OF STORM. CLEARING TO VFR TONIGHT MAY BE QUICKER FROM CURRENT FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 EST 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20 CRW CONSISTENCY H H M M M H M M M H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY M M L M L M M M L L L L EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z MONDAY... NO WIDESPREAD AREAS OF IFR EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ005-013-015-027. WINTER STORM WARNING UNTIL 1 AM EST MONDAY FOR WVZ024>026- 033>036. WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR WVZ037-038- 046-047. OH...NONE. KY...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR KYZ105. VA...WINTER STORM WARNING UNTIL 1 AM EST MONDAY FOR VAZ003-004. && $$ SYNOPSIS...TRM/SL NEAR TERM...JMV/SL SHORT TERM...TRM LONG TERM...26 AVIATION...JMV