274 FXUS61 KRLX 051805 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 200 PM EDT SUN AUG 5 2012 .SYNOPSIS... NUMEROUS SHOWERS AND STORM EXPECTED TODAY AND TONIGHT AS A COLD FRONT MOVES THROUGH. THE ACTUAL COLD FRONT LINGERS ACROSS THE SOUTH THROUGH MONDAY MORNING. DRY AIR TUESDAY. && .NEAR TERM /THROUGH MONDAY/... MESSY SITUATION ACROSS THE FORECAST AREA...WITH CONVECTION CURRENTLY ONGOING WEST OF A HTS-CRW-CKB LINE...AND MOVING ENE. ADDITIONAL DEVELOPMENT IS STARTING TO SHOW UP ON RADAR ACROSS CENTRAL AND WESTERN OHIO ASSOCIATED WITH SHORTWAVE TROUGH AND VORT MAX AHEAD OF THE SURFACE COLD FRONT. EXPECTING THIS TO CONTINUE DEVELOPING TO THE SOUTH...WITH THE WHOLE /COMPLEX/ MOVING EAST TOWARDS CWA. ALSO TRACKING CONVECTION IN SOUTH CENTRAL KY...WHICH ON ITS CURRENT TRACK COULD CLIP SOUTHERN ZONES. EXACT TIMING AND COVERAGE IS TOUGH WITH THESE SYSTEMS...AS WELL AS DETERMINING JUST HOW STRONG THE CONVECTION WILL BE. WE HAVE HAD LOTS OF CLOUDS AROUND THIS MORNING...LIMITING DAYTIME HEATING AND REDUCING LOW LEVEL INSTABILITY. STILL...IMPRESSIVE UPPER LEVEL DYNAMICS MOVING THROUGH. ACCORDING TO VISIBLE SATELLITE WE DO HAVE A MORE BROKEN DECK OF CLOUDS MOVING IN FROM WEST...AHEAD OF THE BEST UPPER LEVEL SUPPORT...SO WE MAY BE ABLE TO BUILD ENOUGH INSTABILITY TO SUPPORT AT LEAST ISOLATED STRONG TO SEVERE STORMS LATE THIS AFTERNOON INTO THIS EVENING...BUT NOT REAL EXCITED ABOUT THIS. NAM SUGGESTING PWAT VALUES WILL BE IN THE 2.0-2.3 RANGE THROUGH THE AFTERNOON...WHICH IS SUPPORTED BY THE 12Z ILN SOUNDING. THIS IS A LOWER THAN PREVIOUS RUNS WERE SHOWING...BUT STILL HIGH ENOUGH THAT VERY HEAVY RAIN IS LIKELY IN SHORT PERIODS OF TIME WITH STRONGEST CELLS. THREE HOUR FLASH FLOOD GUIDANCE STILL COMING IN AT 1.5-2.5 INCHES IN MANY AREAS DUE TO RAIN IN THE LAST FEW DAYS. SO WILL LEAVE FLASH FLOOD WATCH AS IS FOR NOW. IN ADDITION...IT STILL LOOKS LIKE APPROACHING SURFACE COLD FRONT COULD SLOW AND ORIENT MORE W-E OVERNIGHT OVER SOUTHERN ZONES...WHICH WOULD INCREASE THREAT OF TRAINING CELLS. SPEAKING OF COLD FRONT...EXPECT IT TO MOVE THROUGH OVERNIGHT WITH POPS DECREASING FROM NW TO SE AFTER THE FRONT PASSES. WILL HOLD ON TO SOME POPS IN VERY SOUTHEAST ZONES AT END OF NEAR TERM PERIOD AS FRONT SLOWS. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... THE NAM/GFS/AND ECWMF IN AGREEMENT WITH SLOWING THE FRONT DOWN KEEPING AT LEAST SHOWERS THRU EARLY MONDAY MORNING ALONG AND EAST OF A LINE FROM HTS...NORTHEAST TO CKB. KEPT CHANCE POPS FROM PREVIOUS PACKAGE AS THESE SHOWERS SHOULD CONTINUE DIMINISHING IN INTENSITY AND COVERAGE THRU THE MID MONDAY MORNING. ALTHOUGH DO EXPECT NORTHWEST TO NORTH LIGHT FLOW AT THE SFC...DO NOT SEE A STRONG PUNCH OF COOL AIR BEHIND THE FRONT AS H850 TEMPS REMAINS AROUND 15C. SKY GUIDANCE FROM THE GMOS/CMC/NAM SUGGEST CLEARING WILL BEGIN TO SPREAD NORTHWEST TO SOUTHEAST BY MID MONDAY MORNING. MOSTLY CLEAR SKIES WILL PREVAIL OVERNIGHT MONDAY INTO TUESDAY MORNING...ALLOWING DENSE FOG DEVELOPMENT OVER AREAS THAT RECEIVE RAINFALL. KEPT PREVIOUS TEMPERATURES THROUGH THE PERIOD WITH SEASONAL LOW TO MID 80S MONDAY PER RELATIVELY FRESHER AIR AND CLOUDS DIMINISHING DURING THE AFTERNOON...BUT WARMER THAN NORMAL FOR TUESDAYS HIGHS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... 12Z GFS AND 12Z ECMWF SOLUTIONS CONTINUE TO AGREE THAT THE MID LEVEL RIDGE...BAKING THE PLAINS THIS SUMMER...WILL SLIDE BACK WEST INTO THE GREAT BASIN...WITH A STRONG TROF SWINGING THROUGH OUR VICINITY ON DAY 7...WITH THE SURFACE FRONT LIKELY AHEAD OF IT...ON DAY 6/FRIDAY. PROBLEM FOR WEDNESDAY AND THURSDAY IS THE DEEP MOISTURE LINGERING TO OUR SOUTHEAST. WILL TRY TO HOLD WEDNESDAY DRY MAINLY FOR COUNTIES NORTH OF A HTS-CRW-EKN LINE...WITH SOME 20/30 POPS ALONG OUR SOUTHEASTERN COUNTIES WEDNESDAY. WENT ALONG WITH HPC MEDIUM RANGE CHANCE POPS FOR THURSDAY AND FRIDAY...WITH A COOL DOWN FOR SATURDAY. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... CONVECTIVE SHOWERS CURRENTLY ONGOING...MAINLY WEST OF A LINE FROM HTS-CRW-CKB. THIS ACTIVITY WILL MOVE EAST...MAINLY BKW AND EKN IN THE NEXT COUPLE HOURS. ADDITIONAL DEVELOPMENT IS EXPECTED FROM THE WEST THROUGH THE AFTERNOON...AND A COMPLEX CURRENTLY IN CENTRAL KY WILL MOVE ENE...SO EXPECTING AN UPSWING IN CONVECTIVE COVERAGE THROUGH THE AFTERNOON AND EVENING. WITH A VERY JUICY ATMOSPHERE...HEAVY RAIN WILL BE A THREAT...REDUCING VISIBILITIES INTO THE MVFR AND EVEN IFR RANGE. PLUGGED SOME GENERAL TRENDS INTO THE TAFS WITH THIS...BUT MAY NEED REFINEMENT AS CONVECTION MOVES IN. EVEN AFTER SHOWERS AND STORMS TAPER OFF...THINK LOW MVFR STRATUS DECK WILL REMAIN WELL INTO MONDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND INTENSITY OF SHOWERS AND THUNDERSTORMS TODAY MAY VARY. . 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 14 15 16 17 18 19 20 21 22 23 00 01 EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 CRW CONSISTENCY H H H H M M M M M M M M HTS CONSISTENCY H H H H H H H M H H H H BKW CONSISTENCY H H H H H H H H M M M M EKN CONSISTENCY H H H H H H H H H H M M 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 MONDAY... IFR CONDITIONS IN FOG MAY BE POSSIBLE MONDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WVZ005-006-013>020- 024>040-046-047. OH...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OHZ087. KY...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR KYZ101>103-105. VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ003-004. && $$ SYNOPSIS...ARJ/MZ NEAR TERM...MZ SHORT TERM...ARJ LONG TERM...KTB AVIATION...MZ