Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 302042 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 441 PM EDT TUE SEP 30 2014 .SYNOPSIS... MID/UPPER LEVEL DISTURBANCE EXITS TONIGHT. WEAK HIGH PRESSURE FOLLOWS WEDNESDAY AND THURSDAY. STRONG COLD FRONT CROSSES FRIDAY. MUCH COOLER WEEKEND. REINFORCING FRONT MAY ARRIVE EARLY NEXT WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... SFC OBS SHOWING WEAK COLD FRONT/SFC TROUGH-LIKE FEATURE GENERALLY BISECTING THE STATE OF OHIO FROM NE TO SW...JUST EAST OF CLE-CMH-CVG AT 18Z. AHEAD OF IT AND OUT AHEAD OF AN UPPER LOW OVER THE SE GREAT LAKES IS A LINE OF SHOWERS ACROSS WESTERN PA STRETCHING SSW-WARD INTO MORGAN/PERRY COUNTIES IN OHIO. THESE WILL CONTINUE SLOWLY EASTWARD MAINLY ALONG AND NORTH OF US HWY 50 THIS AFTERNOON...AND WILL LIKELY SHOW SOME SIGNS OF DISSIPATION AS THEY PROGRESS. FOR THIS EVENING AND TONIGHT...CLOSED UPPER LOW WILL SLOWLY PUSH EASTWARD ACROSS PENNSYLVANIA BY 12Z WED. PRECIP CHANCES THIS EVENING ARE A BIT PROBLEMATIC...WITH NEAR-TERM CONVECTIVE MODELS INSISTING ON SOME WEAK REDEVELOPMENT ALONG THE FRONT AS IT CONTINUES INTO OUR AREA THIS EVENING. SHOULD THIS OCCUR IT WILL BE MAINLY OVER THE CENTRAL AND NORTHERN ZONES...WHILE THE SOUTHERN COALFIELDS REMAIN DRY. AT ANY RATE...ANY PRECIP SHOULD END BY THE 03Z-06Z TIME FRAME OVER THE NORTHEAST ZONES...AND ANYTHING WHICH DOES DEVELOP THIS EVENING WILL BE ON THE LIGHT SIDE. THE FRONT/TROUGH WILL CONTINUE SOUTH OVERNIGHT BUT BEGIN TO BECOME MORE DIFFUSE OVERNIGHT...LAYING UP SOMEWHERE OVER THE CENTRAL WV LOWLANDS. BEHIND IT...LOW STRATUS WILL TAKE HOLD...WHILE EAST AND SOUTH OF IT SKIES SHOULD REMAIN MOSTLY CLEAR TO PARTLY CLOUDY...ALLOWING A BETTER POTENTIAL FOR FOG FORMATION. WEDNESDAY...EARLY MORNING CLOUDS AND FOG WILL GRADUALLY DISSIPATE WITH AT LEAST PARTLY CLOUDY SKIES BY LATE MORNING FOR MOST AS UPPER RIDGING BUILDS IN BEHIND THE DEPARTING UPPER LOW TO THE NORTHEAST. KEPT A SLIGHT CHANCE OF A SHOWER MAINLY ON THE EASTERN SLOPES OF THE EASTERN MOUNTAINS WITH SOME RIDGETOP CONVERGENCE AND LLVL MOISTURE POOLED IN THAT AREA. VERY LITTLE CHANGE FROM PREV FCST REGARDING TEMPS. OVERNIGHT MINS GENERALLY MID/UPPER 50S LOWLANDS AND MAX TEMPS MID/UPPER 70S STILL APPEAR ON TRACK. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... QUIET START TO THE PERIOD AS RIDGING RULES SFC AND ALOFT WED NT INTO THU NT. MEANWHILE...L/W TROUGH RESIDING OVER THE WRN CONUS OF LATE...SLIDES E TO THE CENTRAL CONUS BY THU...AND TO THE ERN CONUS FRI-FRI NT. MODELS IN BETTER AGREEMENT ON BEHAVIOR OF INDIVIDUAL S/W TROUGHS ROTATING THROUGH THE BASE OF THE LARGER L/W AS THE ENTIRE SYSTEM MOVES THROUGH. THE FIRST S/W IS A SOUTHERN STREAM SYSTEM THAT GETS DRAWN NEWD ON FRONT SIDE OF L/W...CROSSING FRI. THIS WILL HAVE THE BEST AVAILABLE MOISTURE AND LIKELY BE ASSOCIATED WITH THE MAIN PRECIPITATION EVENT AHEAD OF THE COLD FRONT. DEPICTED A MORE NEGATIVELY TILTED PATTERN IN THE POP GRIDS. DYNAMICS WITH THIS FEATURE AHEAD OF THE COLD FRONT WILL LIKELY RESULT IN BUOYANCY WHICH...WITH STRONG MID LEVEL FLOW...GIVE RISE TO STRONG THUNDERSTORMS...THE ONLY MITIGATING FACTOR BEING THE TIMING WILL BE A BIT EARLY IN RELATIONSHIP TO DIURNAL HEATING. WOULD NOT BE SURPRISED TO AT LEAST SEE A SEE TEXT AS THE EVENT GETS CLOSER. WILL DEFER TO THE MID SHIFT WITH THE NEW SWODY3 FOR AN HWO INTRODUCTION. THE FRONT WHIPS THROUGH FRI NT...DRIVEN BY THE MAIN S/W TROUGH AXIS WHICH DIGS IN AND CLOSES OFF INTO AN UPPER LEVEL LOW SOMEWHERE OVER THE GREAT LAKES. THERE REMAINS MODEL DISCREPANCY AS TO HOW FAR S THE LOW CLOSES OFF...BUT CLEARING...DRYING AND FALLING TEMPERATURES FOLLOW EITHER WAY. BLENDED IN BIAS CORRECTED MOS GUIDANCE FOR LOWS...A LITTLE LOWER THAN PREVIOUS. PREVIOUS FCST LOOKED GOOD FOR HIGHS THU. BLENDED IN A COMBINATION OF NAM AND GFS MODEL TEMPERATURES FOR FRI...HIGHS ENDED UP CLOSE TO PREVIOUS AS A RESULT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... L/W TROUGH DOMINATES THE ERN CONUS THIS PERIOD WITH INITIAL SHOT OF COLD AIR FIRMLY IN PLACE FRI. THE GFS TAKES MOST OF SAT TO GET THE MAIN TROUGH AXIS THROUGH WHILE THE ECMWF IS FASTER...BUT BRINGS ANOTHER S/W TROUGH AROUND THE BACK SIDE OF THE L/W THROUGH ON SAT. EITHER WAY...A FEW SHOWERS COULD OCCUR IN THE COLD ADVECTION UPSLOPE FLOW BENEATH THE COLD AIR ALOFT. THE AREA DOES REMAIN IN THE BAROCLINIC ZONE MUCH OF THE PERIOD AFTER THAT AS THE SWD EXTENT OF THE L/W DOES RETREAT. THIS MAKES IT DIFFICULT TO TIME THE COOLEST WEATHER OTHER THAN THE INITIAL SHOT SAT...WHICH IS NOW CODED UP AS THE COOLEST PART OF THE FCST. THIS INCLUDES POTENTIALLY FROSTY TEMPERATURES FOR THE NRN WV MOUNTAINS AND IN SE OH COME SUN MORNING. THE NEXT REINFORCING S/W TROUGH BRINGS THE CHANCE FOR SHOWERS SOMETIME EARLY NEXT WEEK...WITH MODEL DIFFERENCES AS TO ITS TIMING ALONG WITH TIMING THE ARRIVAL OF THE REINFORCING COOL AIR BEHIND IT SO COULD NOT REALLY DEPICT NEXT COOL DOWN EVEN ON DAY 7 NT. BLENDED IN GFS...THE COLDER MODEL...FOR TEMPERATURES SAT AND HAVE HIGHS SAT ON LOW EDGE OF GUIDANCE AND WELL BELOW NORMAL...UPPER 50S LOWLANDS. BLENDED IN WPC AND THE LOW MEX FOR LOWS SAT NT...AGAIN ON LOW END OF GUIDANCE. WILL NOT HWO FROST DAY 4 NT THOUGH PENDING HOW FAVORABLE SAT NT TURNS OUT FOR RADIATIVE COOLING. BLENDED IN WPC TEMPERATURES FOR THE LESS CERTAIN BALANCE OF THE EXTENDED. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... GENERALLY VFR CONDITIONS BEING EXPERIENCED THIS AFTERNOON. A LINE OF SHOWERS CURRENTLY PUSHING SLOWLY ACROSS SE OHIO INTO THE PANHANDLE OF WV SHOULD CONTINUE SLOWLY EASTWARD THIS AFTERNOON...MAINLY NEAR AND NORTH OF US HWY 50. BRIEF MVFR/IFR VIS IS POSSIBLE UNDERNEATH A HEAVIER SHOWER BUT AGAIN...VFR CONDITIONS SHOULD BE PREVALENT OTHERWISE. EXPECT LOWER MVFR/IFR CEILINGS TO MOVE SOUTH INTO SOUTHEAST OHIO 00Z TO 06Z WEDNESDAY...BEHIND THE FRONT CURRENTLY JUST TO THE NORTHWEST. A GOOD DEAL OF UNCERTAINTY EXISTS MAINLY FOR THE CENTRAL WV LOWLANDS WITH EXACTLY HOW FAR EAST AND SOUTH IT PROGRESSES...WITH LOW STRATUS AND/OR FOG POSSIBLE IN THIS GENERAL AREA. THINKING MORE DIURNAL FOG WILL FORM ACROSS SOUTHERN WEST VIRGINIA BY 06Z WEDNESDAY. EXPECT SLOWLY IMPROVING CONDITIONS DURING THE MORNING HOURS BTWN 15Z-18Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: COVERAGE OF SHOWERS MAY BE MORE THAN FORECAST IN THE PKB-CKB-EKN VCNTY. ARRIVAL OF LOWER STRATUS CEILING INTO SOUTHEAST OHIO AND MID OHIO VALLEY AROUND PKB MAY BE FASTER THAN 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 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 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 H H H H H H H H 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 M M M M CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z WEDNESDAY... BRIEF IFR POSSIBLE IN FAST MOVING SHOWERS AND/OR THUNDERSTORMS FRIDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/50 NEAR TERM...50 SHORT TERM...TRM LONG TERM...TRM AVIATION...50

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