Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 291920 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 320 PM EDT FRI AUG 29 2014 .SYNOPSIS... WARM FRONT CROSSES TONIGHT INTO SATURDAY. TURNING HOT AND MORE HUMID SATURDAY IN DEEP SOUTHWEST FLOW. MOISTURE INCREASES IN THAT FLOW...WITH AN UPPER LEVEL DISTURBANCE FROM THE GULF CROSSING SUNDAY. && .NEAR TERM /THROUGH SATURDAY/... CLEAR TO START BENEATH UPPER LEVEL RIDGE...AS SFC HIGH MOVES OFFSHORE. CU WAS STARTING TO POP ACROSS SW VA AND SWRN WV...ALONG AND S OF A WARM FRONT THERE. HAVE SCHC / ISO CONVECTION THERE LATE THIS AFTERNOON INTO THIS EVENING. ANY EARLY EVENING CONVECTION WILL LIKELY DIE WITH THE SUNSET...BUT THEN REFIRE OVERNIGHT OVER CENTRAL PORTIONS OF THE AREA AS ELEVATED CONVECTION AHEAD OF THE ADVANCING WARM FRONT...ALONG AXIS OF 345K H85 THETA E AND NEGATIVE SHOWALTER. HAVE 20 KTS OF FEED...30 KTS W OF THE OHIO RIVER BUT NO REAL FOCUSED LLJ SPATIALLY AND FORCING IS WEAK...SO EXPECT AREA COVERAGE OVERNIGHT INTO SAT TO BE SCT AT BEST. LATEST NEAR TERM MODELS HAVE ACTUALLY BACKED OFF ON CONVECTION LATE OVERNIGHT INTO SAT MORNING. AFTERNOON CONVECTION MAY FIRE ALONG AND SW OF THE WARM FRONT OVER THE NRN WV MOUNTAINS SAT. CONVECTION MAY ALSO START FIRING OVER THE WRN FRINGES OF THE FCST AREA LATE SAT...AS THE FIRST OF A SERIES OF WAVES COMING OUT OF THE GULF OF MEXICO...AHEAD OF AN UPPER LEVEL S/W TROUGH APPROACHING FROM THE W...APPROACHES. LIKED HIGHER MET VALUES FOR LOWS TONIGHT...BLENDED IN BIAS CORRECTED VERSION. LITTLE CHANGE ON HIGHS SAT...WHICH ARE BETWEEN THE MET AND MAV. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
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SATURDAY NIGHT - SUNDAY... AREA REMAINS UNDER SW FLOW ALOFT AS A S/W TROUGH PROGRESSES EASTWARD ACROSS THE GREAT LAKES. DEEP LAYER MOISTURE WILL ARRIVE OVERNIGHT SATURDAY NIGHT AND...ALONG WITH AN APPROACHING S/W TROUGH FROM THE SW...WILL INCREASE POPS TO CATEGORICAL BY 12Z SUN FOR MOST LOWLAND LOCATIONS. IT APPEARS THAT THERE WILL BE TWO WAVES OF PRECIP SUNDAY...WITH THE FIRST WAVE CROSSING W/SW TO NE DURING THE MORNING HOURS AND A SECOND WAVE TOWARDS THE LATE AFTERNOON AND EARLY EVE HOURS. WITHOUT BEING MORE DETERMINISTIC THAN THE SCIENCE CAN OFFER...DID MAKE AN ATTEMPT TO DEPICT THE TWO WAVES OF PRECIP WITH CATEGORICAL POPS WITH EACH...SURROUNDED BY LIKELY AND HIGH CHANCE POPS. DID IN FACT LOWER POPS TO HIGH CHANCE FOR LOCATIONS TO THE NORTHWEST OF THE MOUNTAINS AROUND THE 18Z-21Z TIME FRAME...WHEN AND WHERE CROSS SECTION ANALYSIS INDICATES DECENT DOWNWARD MOTION ALMOST UP TO 500MB IN THE S/SE DOWNSLOPING FLOW. IN REALITY...PRECISE TIMING OF CONVECTIVE PRECIP IS A BIT TOUGH AND MAY CERTAINLY VARY...BUT IN THE END DO BELIEVE THAT BY THE TIME SUNDAY COMES TO AN END MANY LOCATIONS WILL SEE SOME PRECIP SUNDAY. GENERALLY EXPECTING AROUND A HALF INCH...WITH THE USUAL HIGHER AMOUNTS IN STRONGER STORMS. WILL LEAVE THE POTENTIAL FOR FLASH FLOODING IN THE HWO AS THERE IS SOME POTENTIAL FOR TRAINING CELLS. PREV FCST HAD A GOOD HANDLE ON MAX TEMPS...STILL EXPECTING GENERAL LOW 80S IN THE LOWLANDS. SUNDAY EVENING - MONDAY... PROGGED SECOND BATCH OF PRECIP WILL BE EXITING TO THE NORTHEAST MID/LATE EVENING. LINGERED SLIGHT/LOW CHANCE POPS THROUGH THE ENTIRE OVERNIGHT PERIOD FOR MOST LOCATIONS WITH A DECENT AMOUNT OF LLVL MOISTURE REMAINING YET SUSPECT THAT MOST LOWLANDS WILL BE DRY AFTER MIDNIGHT-2AM HEADING INTO MON MORNING. HOWEVER...ANOTHER S/W WITH LESSER MOISTURE WILL BE ARRIVING FOR LABOR DAY AND HAVE MID/HIGH CHANCE POPS WITH THIS FEATURE BY MON AFTERNOON...WHICH PREV FCST HAD A GOOD HANDLE ON. MAX TEMPS MONDAY WILL BE SIMILAR TO SUNDAY/S...PERHAPS A DEGREE OR TWO WARMER.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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LONG TERM PERIOD CAN GENERALLY BE CHARACTERIZED BY ZONAL FLOW ALOFT. LEANED WPC FOR THE MOST PART WITH A FEW TWEAKS HERE AND THERE. WARM AND MUGGY CONDITIONS WILL CONTINUE FOR THE MOST PART WITH PERIODIC DISTURBANCES AND SUBSEQUENT MAINLY DIURNALLY-DRIVEN PRECIP CHANCES.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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VFR AFTERNOON AND EVENING. FOG WILL BEGIN FORMING OVERNIGHT...BUT MID AND HIGH CLOUD ASSOCIATED WITH A WARM FRONT APPROACHING FROM THE SW...WILL STOP IT DEAD IN ITS TRACKS MOST SITES AT MVFR OR BETTER. EXCEPTION IS EKN WHICH WILL LIKELY HAVE DENSE FOG BY 06Z AGAIN...BUT EVEN THERE...THE FOG SHOULD THIN OUT AS THE CLOUDS INCREASE. A THUNDERSTORMS IS POSSIBLE IN THE AFTERNOON HEAT IN THE MOUNTAINS ON SAT. LIGHT AND VARIABLE SFC FLOW WILL BECOME LIGHT S TO SW ON SAT...WHILE FLOW ALOFT REMAINS LIGHT SW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING...EXTENT AND DISSIPATION OF FOG OVERNIGHT TONIGHT DEPENDING UPON TIMING OF CLOUDS ASSOCIATED WITH THE APPROACHING WARM FRONT. 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 20 21 22 23 00 01 02 03 04 05 06 07 EDT 1HRLY 16 17 18 19 20 21 22 23 00 01 02 03 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 L L PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z SATURDAY... IFR POSSIBLE IN SHOWERS/STORMS SUNDAY...AND THEN IN DENSE EARLY MORNING VALLEY FOG EARLY NEXT WEEK.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/50 NEAR TERM...TRM SHORT TERM...50 LONG TERM...50 AVIATION...TRM

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