Issued by NWS Charleston, WV
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KRLX 222350 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 650 PM EST SUN NOV 22 2009 .SYNOPSIS... UPPER LEVEL SYSTEMS TRAVERSE THE AREA TONIGHT INTO TUESDAY. COLD FRONT MOVES EAST WEDNESDAY WITH LIMITED MOISTURE. STRONG UPPER LEVEL LOW TO AFFECT THE AREA DURING THE THANKSGIVING WEEKEND. && .NEAR TERM /THROUGH MONDAY/... JUST AS PATCHY LOW CLOUDS UP N ARE EXODUS...HIGH CLOUDS WERE ARRIVING FROM THE S IN RESPONSE TO S/W FEATURE OVER THE TN VALLEY. NAM AND ECMWF BEAT GFS AND UKMET ON EVOLUTION OF THIS FEATURE...WHICH WILL TAKE MOST OF ITS DYNAMICS S AND E OF THE AREA TONIGHT THROUGH MON. THE BEST CHANCE FOR PRECIPITATION LATER TONIGHT AND MON IS UPSLOPE SE FLOW COMBINED WITH DEEP MOISTURE AND FORCING. FARTHER W...FLOW IS DOWNSLOPING AND FORCING IS MUCH LESS EVEN THOUGH THE COLUMN IS ALMOST AS SATURATED. SREF STILL SUPPORTS SOMEWHAT HIGHER CHANCE FOR RAIN IN OHIO IN RESPONSE TO WESTERN VORT LOBE ASSOCIATED WITH AFOREMENTIONED S/W FEATURE. INCREASED WIND SPEEDS THIS PACKAGE IN GRADIENT BETWEEN HIGH OVER NEW ENGLAND AND LOW PRESSURE TRAVERSING GULF AND THEN SE COASTS. THIS SET UP WEAKENS LATE MON AS NEW ENGLAND HIGH IS EXODUS AND LOW IS E OF THE AREA OFF MIDDLE ATLANTIC SEABOARD. NO IMPORTANT DEVIATIONS FROM MOS ANTICIPATED ON LOWS TONIGHT NOR HIGHS MON. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... 12Z MODELS ARE IN AGREEMENT WITH WEAK H5 VORT MAX REACHING THE AREA BY TUE 00Z...UNDER A DESCENT MOISTURE LAYER UP TO H7. THEREFORE...BY 00Z TUE...BULK OF PCPN PROBABLY MOVING NORTHEAST MONDAY NIGHT. ADJUSTED DOWN POPS ACROSS THE WEST AND SOUTH AS THE PCPN MOVES NORTHEAST MON NIGHT. WITH LESS FORCING AND MOISTURE BECOMES SHALLOW UP TO H8 BY TUE EVENING...ONLY SLIGHT CHANCE POPS WERE KEPT ACROSS THE NORTHERN THIRD AND NORTHEAST MOUNTAINS UNDER NORTHEAST FLOW ALOFT. BY WED...AN UPPER LOW PRESSURE SYSTEM MOVE OVER MI. MODELS SOLUTIONS SEEMS SPLIT ON THE WED 12Z LOWS CENTER WITH THE NAM/ECMWF BEEN A BIT WEST WHEN COMPARED WITH THE GFS/GEM POSITIONS. HOWEVER...THE GEM AND GFS SUGGEST A STRONG SHORT WAVE/VORT MAX ACROSS THE OH VALLEY INTO WV BY THE SAME TIME. THIS FEATURE COULD BE PUSHING A COLD FRONT ACROSS THE AREA WITH HIGHER CHANCE FOR RAIN SHOWERS. ATTM...WITH VERY LOW BUOYANCY IF ANY...AND PW UNDER ONE INCH...KEPT THUNDER OUT FOR WED. ALMOST IDENTICAL BIAS CORRECTED SOLUTIONS FROM THE SREF AND GMOS FOR LOW TEMPERATURES WERE NOTICED TUE AND WED MORNING...WHICH RESULTED INTO A BLEND FORECAST...GENERALLY IN THE MID TO LOWER 40S. MINOR CHANGES MADE TO HIGH TEMPS GENERALLY AROUND 60 DEGREES ON TUE...AND FEW DEGREES COOLER ON WED AS H5 TEMPS DROP 3-4 DEGREES ACCORDING TO THE SREF. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... ON THURSDAY A SECONDARY UPPER LOW WILL DROP SOUTH AND MOVE EAST TOWARDS THE GREAT LAKES REGION...DEEPENING THE UPPER LEVEL TROUGH...AND SWEEPING A SECONDARY COLD FRONT ACROSS THE CWA. THIS WILL USHER IN MUCH COOLER TEMPERATURES INTO THE FORECAST AREA. MODELS SOUNDINGS AND 1000-500MB THICKNESSES SUGGEST SNOW WILL BE POSSIBLE FRIDAY MORNING ACROSS MUCH OF THE HIGHER TERRAIN...NORTHERN WV...AND SE OHIO...WITH A RAIN/SNOW MIX OVER MUCH OF THE WEST VIRGINIA LOWLANDS. MUCH OF THE PRECIPITATION WILL GRADUALLY TAPER OFF AS THE DAY PROGRESSES ON FRIDAY...HOWEVER...STRONG NW WINDS ALOFT WILL KEEP UPSLOPE SHOWERS GOING OVER THE HIGHER TERRAIN FOR MUCH OF THE DAY. PRECIPITATION WILL TAPER OFF ACROSS THE REGION ON SATURDAY...AS HIGH PRESSURE BUILDS IN BRIEFLY. MODELS INDICATING ANOTHER SYSTEM MOVING INTO THE REGION LATE IN THE EXTENDED. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...-- Changed Discussion --AS UPPER LEVEL SYSTEM APPROACHES...ATMOSPHERE MOISTENS FROM THE TOP DOWN...AND WILL SEE GRADUALLY LOWERING CEILINGS TONIGHT. WILL END UP A MVFR GENERALLY BEYOND 10Z GIVE OR TAKE A COUPLE HOURS. WILL NEED TO WATCH BKW AS IT MAY DROP TO IFR...AND THIS MAY NEED A TEMPO GROUP FOR MONDAY. IFR CEILINGS LIKELY ALONG THE EASTERN SLOPES WITH UPSLOPE LOW LEVEL CLOUDS DEVELOPING. SOUTHEAST WINDS INCREASE...AND WILL BE STRONGER ACROSS THE HIGHER ELEVATIONS WITH GUSTS TO 20KTS POSSIBLE...ESPECIALLY AT BKW. AFTER 00Z TUESDAY... IFR/LIFR CONDITIONS POSSIBLE ACROSS PORTIONS OF VA AS WELL THE WV MTNS...MAINLY ALONG THE E TO SE FACING SLOPES...MON AFTERNOON INTO MON NIGHT IN LIGHT RAIN...PRIMARILY ON CIGS.-- End Changed Discussion --&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/ARJ/SL NEAR TERM...TRM SHORT TERM...ARJ LONG TERM...SL AVIATION...26
