Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 040852 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 452 AM EDT FRI SEP 4 2015 .SYNOPSIS...
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EVER PRESENT WEAK UPPER LEVEL DISTURBANCES AND A VERY WARM AND HUMID AIR MASS SPELL MAINLY AFTERNOON AND EVENING CONVECTION. SOUTHEAST FLOW INCREASES TONIGHT INTO SATURDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A THUNDERSTORM COMPLEX OVER LOWER MICHIGAN AND ERN OHIO WAS LOCATED RIGHT IN THE DIFFLUENT ZONE SE OF AN UPPER LEVEL LOW OVER LOWER MICHIGAN. HOWEVER...THE FLOW REGIME IS A LITTLE TOO LIGHT FOR MODELS TO RESOLVE DETAILS...WITH TIME...OF THIS AND OTHER WEAK UPPER LEVEL FEATURES...PLACED IN AN AXIS ROUGHLY NW TO SE...FROM THE GREAT LAKES...TO THE U.S. SE COAST...AND BEYOND...BETWEEN UPPER LEVEL HIGHS LOCATED OVER THE NERN U.S..AND THE DEEP S. THE COMPLEX ITSELF WAS HAVING TROUBLE MAKING IN ROADS SWD INTO THE FCST AREA EARLY THIS MORNING...CONSISTENT WITH THE VIRTUALLY NIL CORFIDI VECTORS. WHAT IS LEFT OF IT SHOULD FALL APART ON POST- SUNRISE CLOUD TOP WARMING. THE FCST AREA REMAINING IN THE UPPER LEVEL WEAKNESS BETWEEN THE TWO UPPER LEVEL HIGHS SPELLS SCATTERED AFTERNOON CONVECTION THAT...IN THE MOISTURE RICH AIR...ONLY SLOWLY DIMINISHES TONIGHT. THE SLOW MOVING STORMS WILL RESULT IN HEAVY BUT MANAGEABLE RAINFALL. THE ATMOSPHERE WILL RESOLVE THE UPPER LEVEL DETAILS VIA WHERE THE LAST OF THE STORMS PERSIST TONIGHT. MEANWHILE...A SFC HIGH BUILDS SWD BEHIND A BACK DOOR COLD FRONT PUSHING SWD ALONG THE E COAST. THIS WILL INTRODUCE LOW LEVEL MOISTURE INTO THE EASTERN SLOPES BY SAT MORNING...AS THE LOW LEVEL FLOW VEERS TO E TO SE. BLENDED IN MET/MAV FOR HIGHS TODAY AND BIAS CORRECTED MET FOR LOWS TONIGHT. NOT MUCH OF A BAROCLINIC ZONE INVOLVED SO THE TEMPERATURE VARIATIONS WILL MAINLY BE A FUNCTION OF CONVECTION.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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NO SIGNIFICANT CHANGES WERE NECESSARY TO THE SHORT TERM FORECAST PERIOD. AREA REMAINS IN A WARM HUMID PATTERN...WITH UPPER RIDGE HOLDING ACROSS THE EASTERN U.S...AND TEMPERATURES ABOVE NORMAL FOR THIS TIME OF YEAR. WEAK DISTURBANCES IN THE FLOW...WILL KEEP A MENTION OF SHOWERS AND THUNDERSTORMS IN THE FORECAST...PARTICULARLY DURING PEAK HEATING HOURS. WITH THE HIGH MOISTURE CONTENT OF THE AIR...STORMS WILL CONTAIN HEAVY DOWNPOURS...AND WITH THE WEAK FLOW...WILL BE SLOW TO MOVE. THUS...THE PATTERN OF ANY STORM THAT DEVELOPS COULD PRODUCE A GOOD INCH OR MORE OF RAIN OVER A PARTICULAR LOCATION. FOR TEMPERATURES...CONTINUED TO HUG THE WARM SIDE OF GUIDANCE WITH BUILDING RIDGE ACROSS THE AREA OVER WEEKEND...AND KEPT OVERNIGHT LOWS ON THE WARM SIDE WITH HUMID AIR MASS IN PLACE.
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&& .LONG TERM /MONDAY THROUGH THURSDAY/... MORE OF THE SAME THROUGH WEDNESDAY...HOT AND MUGGY CONDITIONS WITH JUST AN ISOLATED SHRA/TSRA. PATTERN FINALLY BEGINS TO BREAK TOWARD THURSDAY WITH FALLING HEIGHTS AMID A TRANSITION MORE INTO A E CONUS TROF. THE COLD FRONT THAT WILL MARK THIS TRANSITION LOOKS TO CROSS LONG ABOUT THURSDAY. IT IS LOOKING LIKE A WAVE WILL DEVELOP ALONG THE FRONT WITH A GOOD SHOT A MUCH NEEDED RAIN OVER THE AREA...PARTICULARLY ALONG THE OH RIVER. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... VALLEY FOG FORMATION WAS ALREADY WELL UNDERWAY...BUT A THUNDERSTORM COMPLEX MOVING SEWD INTO THE MIDDLE OHIO VALLEY MAY CAUSE THE FOG TO BREAK UP THERE...AND THE CHANCE FOR A THUNDERSTORM IMPACTING AN AIRPORT DIRECTLY DEPENDS UPON TO WHAT DEGREE THE COMPLEX HOLDS TOGETHER OVERNIGHT. PKB AND PERHAPS CKB ARE MORE LIKELY TO BE IMPACTED OVERNIGHT...VERSUS POINTS FARTHER TO THE S AND E. DAYBREAK WILL BRING AN END TO BOTH FOG AND THUNDER CONCERNS BY MID MORNING...BUT SCATTERED AFTERNOON CONVECTION WILL FIRE UP AGAIN FRI AFTERNOON...AS AN UPPER LEVEL DISTURBANCE OVER OHIO OVERNIGHT...DRIFTS OVER WV FRI. FRI NT WILL BE ANOTHER TOUGH CALL. ON THE ONE HAND...AFTERNOON AND EVENING RAINFALL GREATLY INCREASES THE CHANCE OF AND HASTENS THE TIMING OF THE FORMATION OF OVERNIGHT FOG. ON THE OTHER HAND...OVERNIGHT CONVECTION INTERFERES WITH DENSE FOG. MAINLY CALM SFC WIND OVERNIGHT WILL BE LIGHT AND VARIABLE...MAINLY N...ON FRI...AND THEN LIGHT AND VARIABLE FRI NT. LIGHT N TO NE FLOW ALOFT OVERNIGHT AND FRI WILL BECOME LIGHT NE TO E FRI NT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND COVERAGE OF FOG OVERNIGHT MAY VARY FROM FORECAST. MAY NEED AMENDMENTS AND TEMPOS IF STORMS FORM/MOVE TOWARDS TERMINALS AT ANYTIME. 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 FRI 09/04/15 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 M M M L L L L L M M HTS CONSISTENCY H H H M M L L L L L H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY M M L L L L L L L L M M PKB CONSISTENCY M M M L L L L L L L M M CKB CONSISTENCY H M M L L L L L L L M M AFTER 06Z SATURDAY... IFR POSSIBLE IN VALLEY FOG OVERNIGHT FRIDAY NIGHT INTO SATURDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...30 AVIATION...TRM

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