Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 030732 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 332 AM EDT THU SEP 3 2015 .SYNOPSIS... WEAK HIGH PRESSURE AND WEAK STEERING FLOW. SOUTHEAST FLOW DEVELOPS FRIDAY NIGHT INTO SATURDAY. INSTABILITY DRIVEN BY DIURNAL HEATING PRODUCES ISOLATED TO SCATTERED CONVECTION. && .NEAR TERM /THROUGH TODAY/... MADE SOME ADJUSTMENT TO SKY GRIDS BASED ON LATEST SATELLITE IMAGES AND SFC OBS. REST OF FORECAST REMAINS ON TRACK. PREVIOUS DISCUSSION BELOW... WAS A BIT STRONGER ON THE FOG OVERNIGHT...DUE TO THE SCATTERED LATE AFTERNOON AND EVENING CONVECTION. PLACES AFFECTED BY THE RAIN HAD TEMP/DEW POINT SPREADS OF LESS THAN 10 DEGREES AT SUNSET. HOWEVER...PATCHES OF CLOUDS AND EVEN AN ISOLATED SHOWER COULD STILL BE AROUND DURING THE LATE NIGHT...TO MESS WITH THAT FOG FORMATION. LOWERED MIN TEMP A DEG OR SO IN PLACES OVERNIGHT. WAS A BIT HIGHER ON THE POPS FOR THURSDAY AFTERNOON. DESPITE LACK OF A DEFINITE 500 MB VORT MAX...FORECAST SOUNDINGS SHOW SIMILAR INSTABILITY WITH EQUILIBRIUM LEVELS 35 TO 40 THSD FT. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... BROAD AREA OF LOW PRESSURE IS CAUSING WEAK FLOW GIVING WIDELY SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS FOR FRIDAY AND SATURDAY. THESE WOULD BE SLOW MOVERS...WITH A LOCAL DOWNPOUR. OVERALL THOUGH...THE AREA REMAINS IN A RELATIVELY DRY PATTERN THROUGH LABOR DAY AND SHOWERS MAY EVEN BE HARD PRESSED TO FORM ON LABOR DAY AS A WEAK LOBE OF HIGH PRESSURE NUDGES IN. WEAK VORT MAXES CONTINUE TO LINGER IN THE REGION...BUT THEIR WHEREABOUTS ARE ERRATIC AND DIFFICULT TO PREDICT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... 12Z GFS SOLUTION WAS FASTER THAN THE 12Z ECMWF WITH A SHORT WAVE AND ASSOCIATED SURFACE FRONT TRYING TO DENT THE RIDGE BY DAY 7/TUESDAY. AT THIS DISTANCE IN TIME...WILL NOT JUMP ON THE FASTER SOLUTION BUT STILL HAVE CHANCE POPS IN SE OHIO AND NORTHERN WV TUESDAY AFTERNOON AND EVENING. TRIED TO HOLD MAXIMUM TEMPERATURE DOWN A BIT FOR DAY 4/SATURDAY IN THE SOUTHEAST UPSLOPE AREAS...OTHERWISE NO MAJOR CHANGES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SOME SITES RECEIVED RAINFALL YESTERDAY AFTERNOON AND ALREADY SHOWING MVFR/IFR CONDITIONS DUE TO FOG AT 05Z. THE QUESTION IS IF THESE CONDITIONS COULD PREVAIL OVERNIGHT INTO THE PREDAWN HOURS. SATELLITE IMAGES SHOW MID TO UPPER LEVEL CLOUDS MOVING INTO SOUTHEAST OH. THE TREND IS THAT THEY ARE DISSIPATING AS THEY ENTER SOUTHEAST OH. IF THIS IS THE CASE...THEN IFR/LIFR CONDITIONS WILL PREVAIL OVERNIGHT AT PKB...EKN...HTS AND CKB QUICKLY LIFTING TO VFR BY 12-13Z. OTHER SITES COULD EXPERIENCE MVFR/IFR CONDITIONS LATER AFTER 09-10Z. CONFIDENCE IS RUNNING MEDIUM PER POSSIBLE CLOUDS ACROSS THE AREA. MODEL SOUNDINGS STILL SHOWING SIMILAR INSTABILITY WITH EQUILIBRIUM LEVELS 35 TO 40 THSD 18Z THURSDAY TO 00Z FRIDAY. OF COURSE...ANY STORM WILL HAVE BRIEF IFR. JUST CODED VCTS FOR MOST SITES AROUND 18Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND COVERAGE OF FOG TONIGHT MAY VARY FROM 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. DATE THU 09/03/15 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 CRW CONSISTENCY H H H M M L L L L L H H HTS CONSISTENCY H H H H H L L L L L H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY M M M L L L L L L L H H PKB CONSISTENCY H H H H H L L L L L H H CKB CONSISTENCY M M M L L L L L L L H H AFTER 06Z FRIDAY... IFR POSSIBLE IN ISOLATED/SCATTERED CONVECTION 00Z TO 06Z FRIDAY RIVER VALLEY FOG DURING 06Z TO 13Z TIME FRAMES FRIDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JSH/JMV NEAR TERM...KTB/ARJ SHORT TERM...JMV LONG TERM...FB/KTB AVIATION...ARJ

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