Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 300536 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 136 AM EDT SAT AUG 30 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 TODAY/... UPDATE... ISOLATED CONVECTION IS LESS THAN IMPRESSIVE...BUT REALLY CANNOT TAKE IT OUT OF THE FORECAST THROUGH 12Z GIVEN THE WARM FRONT...AS WEAK AS IT IS...MOVING NORTHEAST. PREVIOUS DISCUSSION BELOW... 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 /TONIGHT THROUGH MONDAY/... 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. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 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. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... CRW TRYING TO GO INTO FOG AT THIS TIME...BUT HAVE SOME DEVELOPING CLOUD COVER OFF TO THE SOUTHWEST AND LIKELY MOVING IN. BIG QUESTION IS WILL IT PREVENT THE FOG FROM FULLY DEVELOPING OVER THE NEXT HALF HOUR...OR WILL IT SNEAK DOWN BRIEFLY. ALSO...THE NATURE OF THE CLOUD COVER DOES NOT LEND MUCH CONFIDENCE TO IT REMAINING ESTABLISHED THROUGH THE NIGHT. YET ANOTHER WRINKLE TO DEAL WITH IN THE FOG FORECASTING TONIGHT. ALL IN ALL...BELIEVE THAT THE CLOUDS WILL WIN OUT...AND DO NOT CARRY MANY RESTRICTIONS TONIGHT. EKN AND CKB LOOK TO STAY CLEAR THE LONGEST...BUT HAVE CLOUDS MOVING IN AFTER 09Z OR SO. NEITHER SITE SHOWS SIGNS OF FOGGING JUST YET WITH A 3-4 DEGREE DEWPOINT DEPRESSION. WOULD REALLY LOVE ANOTHER OB BEFORE ISSUING THESE...BUT THAT IS NOT GOING TO HAPPEN. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING...EXTENT AND DISSIPATION OF FOG OVERNIGHT 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. DATE SAT 08/30/14 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 M H H H H H H H H H HTS CONSISTENCY H H M M H H H 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 M M M H H H H H PKB CONSISTENCY H H M M H H H H H H H H CKB CONSISTENCY H H M M H H H H H H H H AFTER 06Z SUNDAY... IFR POSSIBLE IN SHOWERS/STORMS SUNDAY...AND THEN IN DENSE EARLY MORNING VALLEY FOG EARLY NEXT WEEK. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/50 NEAR TERM...TRM/26 SHORT TERM...50 LONG TERM...50 AVIATION...26

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