Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 030729 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 329 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 /UNTIL 6 PM THIS EVENING/... 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 /6 PM THIS EVENING THROUGH SUNDAY 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 /MONDAY 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 /08Z THURSDAY THROUGH MONDAY/... LOWERED CONFIDENCE TO MEDIUM. WITH THE SCATTERED LATE AFTERNOON CONVECTION BECOMING ISOLATED THIS WEDNESDAY EVENING...WAS FASTER FORMING FOG IN PLACES AFFECTED BY THE RAIN EARLIER...SUCH AS PKB AND CKB AIRPORTS. YET...THERE COULD STILL BE PATCHES OF CLOUDS AND AN ISOLATED SHOWER AROUND 06Z TO 12Z THURSDAY TO MESS WITH THAT FOG FORMATION. TO TIMING THE FOG...ITS COVERAGE AND ITS THICKNESS WAS IN QUESTION. DESPITE THE LACK OF A WELL DEFINED 500 MB VORT MAX... 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...BUT COULD NOT INSERT INTO TAFS AT THIS DISTANCE IN TIME. 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 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY M M L L L L L H H H H H HTS CONSISTENCY H H L L L L L H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY L L L L L L L H H H H H PKB CONSISTENCY H H L L L L L H H H H H CKB CONSISTENCY L L L L L L L H H H 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...JW LONG TERM...FB/KTB AVIATION...ARJ

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