Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 201005 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 503 AM EST SAT DEC 20 2014 .SYNOPSIS... A WEAK DISTURBANCE CLIPS THE AREA TODAY. DRY SUNDAY. SYSTEM MAY CLIP MOUNTAINS MONDAY. && .NEAR TERM /THROUGH TONIGHT/... MODELS SHOW AN UPPER LEVEL DISTURBANCE MOVING OVER THE REGION TODAY WHILE A SURFACE LOW STAYS WELL SOUTH OF THE REGION. RADAR SHOWS LOTS OF RETURNS TO THE WEST...BUT MOST OF THIS IS STRUGGLING TO GET THROUGH A LOWER LEVEL DRY LAYER. SOME PRECIPITATION IN SOUTHERN IL AND WESTERN KY IS MAKING IT TO THE GROUND WHERE THE MESO NAM SHOWS THAT THE LOWER LEVELS HAVE MOSTLY SATURATED. BASED ON THIS...THINK SOME LIGHT PRECIPITATION COULD MAKE IT TO THE GROUND AS THE DISTURBANCE MOVES ACROSS OUR REGION...AS THE MESO NAM SHOWS THAT MOISTURE MAKING IT INTO THE LOWER LEVELS HERE. THEREFORE WILL ADD SOME SMALL POPS IN THE WESTERN COUNTIES TODAY AND THIS EVENING. THE SYSTEM MOVES OFF TO THE EAST TONIGHT...BUT MESO NAM SHOWS THE STRATUS DECK THAT RETREATS NORTHWESTWARD TODAY...PUSHING BACK SOUTHEASTWARD TONIGHT. WILL GO ON THE WARMER SIDE OF MOS LOW TEMPERATURE GUIDANCE IN SOUTHEAST OHIO DUE TO THIS DECK PERSISTING THROUGH THE NIGHT. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... S/W RIDGING WORKS IN ON SUNDAY AS WAA SLOWLY BEGINS TO SPREAD ACROSS THE AREA. THE LOW LEVEL FLOW TO VEER AROUND TO SE IN THE AFTERNOON. THIS SHOULD HELP IN ERADICATING ANY LINGERING STRATUS ALTHOUGH FLOW IS RATHER WEAK. WILL ALSO HAVE SOME WAA FROM THE S TO HELP. UNFORTUNATELY...QUITE A BIT OF CIRRUS WILL BE STREAKING IN FROM THE W IN THE AFTERNOON...TO FILTER WHAT SUNSHINE WE MANAGE TO GET. INHERITED TEMPS CLOSE TO NEW GUIDANCE WITH LITTLE TWEAKING. CIRRUS SUNDAY NIGHT ALONG WITH STRATUS DEVELOPING ON E SLOPES MAY KEEP TEMPS FROM BOTTOMING OUT. TREND IN MODELS IS FOR A WEAKER SURFACE LOW ALONG SE COAST EARLY MONDAY. AS SUCH...PROBABLY LOOKING JUST LIGHT PRECIP ACROSS THE MOUNTAINS MONDAY MORNING...WITH THERMAL PROFILES SUPPORTING MAINLY -FZRA WITH A BRIEF SHOT OF SN ON THE FRONT END. MOST OF THIS CONCERN WOULD LIKE IN POCAHONTAS CO. ELSEWHERE...OUTSIDE OF THE MOUNTAINS...JUST HAVE SOME SCHC POPS FOR A PASSING -SHRA IN THE MORNING. THERE MAY BE SOME LINGERING -RA OR DZ IN THE N MOUNTAINS MONDAY AFTERNOON...OTHERWISE LOOKING AT A DRY BUT CLOUDY END TO THE DAY. TRIED TO CODE UP SOME WARMER TEMPS E OF I79 CORRIDOR TO W SLOPES AIDED BY SOME DOWNSLOPING...WHERE SOME MID 50S POSSIBLE IN THE AFTERNOON. HAVE GENERALLY UPPER 40S TO LOWER 50S ELSEWHERE. CAD LOCATIONS WILL STRUGGLE TO GET OUT OF THE 30S HOWEVER. ATTENTION QUICKLY TURNS TO WELL ADVERTISED STRONG SYNOPTIC SYSTEM FOR MIDWEEK. UPPER TROF WILL UNDERGO SIGNIFICANT AMPLIFICATION ACROSS THE PLAINS AND UPPER MIDWEST MONDAY NIGHT AND TUESDAY. ENERGY ROTATING AROUND THE BASE OF THE TROF WILL CLOSE OF AN UPPER LOW MIDWEEK AMID STRONG UPPER JET DYNAMICS. AS THIS OCCURS SURFACE CYCLOGENESIS ACROSS THE DEEP SOUTH WILL OCCUR AND TRACK INTO GREAT LAKES BY WEDNESDAY. WHILE THE MODELS VARY ON EVENTUAL LOWEST PRESSURE WITH THIS...THEY ALL SEEM TO AGREE ON THE MAGNITUDE OF PRESSURE FALLS WITH BOMBOGENESIS LIKELY TO OCCUR BEFORE BECOMING VERTICALLY STACKED. THIS ALL MEANS CHAOTIC SENSIBLE WX HEADING INTO CHRISTMAS. WITH STRONG AND DEEP SE FLOW DEVELOPING TUESDAY AND TUESDAY NIGHT...FELT A DRIER FORECAST WAS THE WAY TO GO EXCEPT ALONG THE E SLOPES WHERE LIGHT RA OR DZ IS POSSIBLE. DID LEAVE SOME SCHC POPS IN THOUGH BUT THINKING MAINLY DRY FOR DAYLIGHT HOURS TUESDAY. IT WILL BE RATHER WARM DESPITE MID AND HI CLOUDS OVERHEAD. WARM GFS LOOKS TO BE THE WAY TO HEDGE WITH LOW 60S A GOOD POSSIBILITY ACROSS THE LOWLANDS AND ESPECIALLY DOWNSLOPE REGION JUST E I79 WHERE MID 60S IS NOT OUT OF THE QUESTION. QUITE A BIT COOLER ON E SLOPES. SHRA CHANCES BEGIN TO INCREASE TUESDAY NIGHT...FIRST ACROSS SE OH AND NE KY...INCREASING ACROSS REMAINDER OF CWA TOWARD WEDNESDAY MORNING AS THE SURFACE LOW STRENGTHENS AND RESULTING BAROCLINIC ZONE APPROACHES. LOWS TUESDAY NIGHT WERE HELD UP SIGNIFICANTLY GIVEN THE AMOUNT OF DOWNSLOPING BL WINDS. TEMPS WILL FALL QUICKLY BEHIND THE FRONT WITH SHSN EXPECTED. HIGHS WEDNESDAY TRICKY AS CKB TO EKN MAY BE ABLE TO SNEAK UP TO NEAR 60 BEFORE THE FRONT CROSSES. AS THE COLD FRONT PUSHES THROUGH SUSPECT SOME OF THOSE STRONG WINDS ALOFT WILL MIX DOWN...ESPECIALLY IN THE POST FRONTAL REGIME. FLOW NEARLY PERPENDICULAR ACROSS ISENTROPIC SURFACES ALONG WITH A TIGHT SURFACE GRADIENT AND CAA WILL ENSURE STRONG GUSTY WINDS...CHRISTMAS EVE NIGHT AND EARLY CHRISTMAS DAY ITSELF. 30 TO 35 KT GUSTS LOOKS TO BE IN THE CARDS...HIGHER ACROSS THE MOUNTAIN RIDGES. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... ACTIVE WEATHER PATTERN CONTINUES IN THE LONG TERM PERIOD. STILL A CHANCE FOR SOME LIGHT PRECIPITATION MONDAY NIGHT/ TUESDAY AS LOW PRESSURE MOVES NORTHEAST ALONG THE COAST. EXPECTING PRECIPITATION TO MOSTLY BE IN THE FORM OF RAIN...EXCEPT ACROSS THE MOUNTAINS THERE -SN OR A -RASN WILL BE OBSERVED. AT THIS POINT...IMPACTS FOR THIS EVENT LOOK MINIMAL. FOCUS THEN SHIFTS TO AN UPPER LOW ACROSS THE MIDWEST...WITH SURFACE LOW PRESSURE AND ASSOCIATED COLD FRONT TUESDAY NIGHT INTO WEDNESDAY. OUT AHEAD OF THE FRONT...MOISTURE AND TEMPERATURES WILL BE ON THE INCREASE...WITH PW VALUES PROGGED TO RISE OVER AN INCH...AND TEMPERATURES EXPECTED TO BE WARM ENOUGH EVERYWHERE FOR PRECIPITATION TO INITIALLY FALL AS RAIN. THIS WILL CHANGE HOWEVER ON WEDNESDAY...AS A COLD FRONT MOVES THROUGH THE AREA TUESDAY NIGHT/EARLY WEDNESDAY...WITH TEMPERATURES FALLING BEHIND THE FRONT ON WEDNESDAY...GRADUALLY CHANGING ANY LINGERING PRECIPITATION TO SNOW CWA WIDE. IN ADDITION TO THE SNOW...WINDS WILL PICK UP ALONG AND POST FRONTAL PASSAGE. ALSO...A RUMBLE OF THUNDER CANT BE RULED OUT DURING THIS PERIOD WITH THE FRONTAL PASSAGE. THIS REMAINS A TRICKY SYSTEM TO FORECAST IN TERMS OF OVERALL IMPACTS...AS GROUND TEMPERATURES MAY AT LEAST INITIALLY REMAIN WARM ENOUGH...PARTICULARLY ACROSS LOWLANDS...TO LIMIT SNOWFALL ACCUMULATIONS. HAVE HOWEVER DECIDED TO GO AHEAD AND HIGHLIGHT THE STORM IN THE HWO...SINCE IT WILL AFFECT THE AREA CHRISTMAS EVE INTO CHRISTMAS. SPEAKING OF CHRISTMAS DAY...AREA WILL BE UNDER THE INFLUENCE OF THE UPPER LOW FOR AT LEAST THE FIRST PART OF THE DAY...WITH PERIODS OF -SHSN. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... STRATUS DECK SHOULD GRADUALLY LIFT NORTHWESTWARD EARLY THIS MORNING...BUT MAY REMAIN IN OHIO TODAY. A LOW PRESSURE SYSTEM MOVING WELL SOUTH OF THE REGION WILL PROVIDE SOME CLOUDS TODAY AND POSSIBLY SOME PRECIPITATION...MAINLY IN VA AND SOUTHEASTERN WV. SOME MVFR CLOUD RESTRICTIONS ARE ALSO POSSIBLE IN VA AND SOUTHEASTERN WV. AS THE SYSTEM MOVES AWAY...THE STRATUS DECK IS EXPECTED TO BUILD BACK SOUTHEASTWARD OVER MUCH OF THE AREA TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY... FORECAST CONFIDENCE: LOW ON THE TIMING AND PLACEMENT OF THE STRATUS DECK...MEDIUM OTHERWISE. ALTERNATE SCENARIOS: TIMING OF THE STRATUS DECK MOVING NORTHWESTWARD COULD CHANGE CONSIDERABLY. TIMING OF THE STRATUS DECK RETURNING SATURDAY NIGHT COULD VARY. 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. DATE SAT 12/20/14 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY L L H H H H M M H H H H 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 M M CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z SUNDAY... IFR POSSIBLE IN MOUNTAINS SUNDAY NIGHT MONDAY WITH A WINTRY MIX. IFR POSSIBLE IN RAIN CHANGING TO SNOW TUESDAY NIGHT INTO WEDNESDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...RPY/SL/30 NEAR TERM...RPY SHORT TERM...30 LONG TERM...SL AVIATION...RPY

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