Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 201822 CCA AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 102 PM EST SAT DEC 20 2014 .SYNOPSIS... A WEAK DISTURBANCE EXITS TONIGHT. WEAK HIGH PRESSURE CROSSES SUNDAY. SYSTEM MAY CLIP MOUNTAINS MONDAY. STRONG OCCLUSION CROSSES LATE TUESDAY THROUGH CHRISTMAS EVE. && .NEAR TERM /THROUGH SUNDAY/... MID LEVEL BAROCLINIC LEAF OVER THE AREA EARLY THIS AFTERNOON DRIFTS ENEWD OUT OF THE AREA TONIGHT AS AN UPPER LEVEL S/W TROUGH CROSSES. WEAK HIGH PRESSURE SETTLES INTO THE FCST LATE TONIGHT BENEATH UPPER LEVEL RIDGING IN THE WAKE OF THE S/W TROUGH...AND THEN BEGINS DRIFTING ENEWD OUT OF THE AREA SUNDAY AFTERNOON...AS THE UPPER LEVEL FLOW STARTS TO BACK TO THE SW. LOW LEVEL MOISTURE REMAINS IN PLACE AT PERSISTENT H8-9 INVERSION ALTHOUGH THE STRATOCU HAD BROKEN UP ACROSS MOST OF WV. WITH LITTLE FLOW TO WORK WITH...THIS IS LIKELY TO REFORM TONIGHT OR AT THE LATEST FIRST THING SUNDAY MORNING ON MIXING. DAYTIME MIXING WILL EVENTUALLY LEAD TO A MORE CELLULAR CU FIELD SUNDAY AFTERNOON WITH A SIGNIFICANT DECREASE IN CLOUD AMOUNT BY THE END OF THE DAY SUNDAY. LOWS LOOKED GOOD IN LIGHT OF LATEST GUIDANCE FOR TONIGHT ALTHOUGH BIAS CORRECTED VALUES WERE HIGHER. CONTINUING THE TREND OF LOWER HIGHS WITH ANOTHER DAY OF STRATOCU FOR SUNDAY. THE LATE DAY CLEARING SHOULD STILL ALLOW TEMPERATURES TO BREAK 40 ACROSS MUCH OF THE AREA. && .SHORT TERM /SUNDAY NIGHT 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 NRN 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 SATURDAY/... 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 /17Z SATURDAY THROUGH WEDNESDAY/...
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CKB OBSERVATION MISSING SINCE 13Z ON ACCOUNT OF A COMMS ISSUE WHICH IS BEING INVESTIGATED...ISSUED TAF WITH AMEND NOT SKED THERE. THE MVFR STRATOCU HAD LIKELY BROKEN UP THERE BUT REMAINS IN PLACE IN PKB AND MUCH OF THE MIDDLE OHIO VALLEY. THIS DECK MAY RETREAT FARTHER NWWD INTO THE MIDDLE OHIO VALLEY THIS AFTERNOON...BEFORE RETURNING OR REFORMING TONIGHT. LOWER MVFR STRATUS HAD ALREADY RETURNED TO BKW FROM THE SE. IT WILL PERSIST THROUGH MUCH OF THE PERIOD...WITH HIGH IFR CIGS POSSIBLE THERE THIS AFTERNOON. IFR CIGS IN THE MIDDLE OHIO VALLEY TONIGHT MAY MAKE IT TO THE RIVER AND AFFECT PKB AND HTS SUNDAY MORNING. IFR CIGS ARE ALSO POSSIBLE AT EKN SUNDAY MORNING. ONCE RETURNED...CIGS AT LEAST AS LOW AS MVFR CIGS PERSIST THROUGH THE BALANCE OF THE PERIOD ALL SITES. SFC FLOW WILL REMAIN CALM TO LIGHT AND VARIABLE...WHILE LIGHT W TO SW FLOW ALOFT WILL BE MOST WERLY SUNDAY MORNING. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: LOW TO MEDIUM ON THE TIMING AND PLACEMENT OF THE STRATUS DECK...HIGH OTHERWISE. ALTERNATE SCENARIOS: TIMING OF THE STRATUS DECK RETREATING NWWD EARLY ON AND THEN RETURNING / REFORMING OVERNIGHT TONIGHT COULD CHANGE CONSIDERABLY. 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 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H M M M H H H H M M M M BKW CONSISTENCY H H H H H H H H H M M M EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H M M M M M M M M M M CKB CONSISTENCY M H H H H H H H H H H M AFTER 18Z SUNDAY... IFR POSSIBLE IN MOUNTAINS LATE SUNDAY NIGHT AND MONDAY IN A WINTRY MIX. IFR POSSIBLE IN RAIN TUESDAY NIGHT INTO WEDNESDAY...CHANGING TO SNOW SHOWERS LATE WEDNESDAY...AS AN INTENSE LOW PRESSURE CENTER PASSES.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/RPY/SL/30 NEAR TERM...TRM SHORT TERM...30 LONG TERM...SL AVIATION...TRM

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