FXUS61 KRLX 251124 AFDRLX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CHARLESTON WV 725 AM EDT SUN JUL 25 2004 .AVIATION... PATCHY 3-5KFT DECK AGAIN FORMED ON COOLING OF THE TOP OF THE MIXING LAYER. CRW STILL SOCKED IN WITH RADIATION FOG AND EKN JUST WENT DOWN. THIS WILL BREAK INTO LOW CLOUDS NEXT HOUR AND THEN LIFT ABV 3KFT BY LATE MORNING. SURFACE TROUGH SETS UP OVER AREA TURNING FLOW SE IN MOUNTAINS WHILE REMAINING NORTHEAST OVER THE LOWLANDS. THE PATCHY CLOUDS WILL AGAIN EVOLVE INTO CU DECK FOR THE AFTERNOON. A LOW PRESSURE CENTER WILL APPROACH FROM THE SOUTHWEST TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND THUNDERSTORMS AS FAR NORTHEAST AS HTS-CRW-BKW LATE TODAY. THIS IS OUT AHEAD OF THE APPROACHING WEATHER SYSTEM AND MAY BE DIURNALLY DRIVEN TO A LARGE EXTENT...SO SLIGHT CHANCE THUNDER ANYWHERE THIS EVENING THAN DECREASING CHANCE TOWARD 6Z. CHANCE THUNDER STILL TOO SMALL TO CODE IN EXPLICITLY AT THIS TIME. FLOW TONIGHT NE WEST OF OHIO AND VARIABLE EAST OF THERE WITH SURFACE TROUGH ACROSS CENTRAL WV...SE GLOW IN THE MOUNTAINS. EKN WILL AGAIN RADIATE WITH MVFR ON VIS BY 6Z WHILE LOW (MVFR) CLOUDS ROLL BACK INTO BKW ON SE FLOW. INCREASING CHANCE FOR RAIN ALL SITES AFTER 6Z INTO MONDAY AS LOW PRESSURE CENTER APPROACHES THE AREA. CODED UP MOSTLY MVFR FOR THIS LATER TONIGHT. THE CHANCE FOR THUNDER WILL INCREASE AGAIN MONDAY. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 428 AM EDT SUN JUL 25 2004 SHORT TERM (TODAY THROUGH MONDAY)... SOME EVIDENCE OF CLOUD FORMATION AT TOP OF MIXING LAYER ON COOLING ONCE AGAIN THOUGH NOT NEAR AS PREVALENT AS YESTERDAY. RAN SKY FROM ETA40 RH FROM LOW LEVELS FOR STARTERS TO ACCOUNT FOR THIS AS WELL AS LOW LEVEL MOISTURE COMING AS FAR WEST AS BKW ON SOUTHEASTERLY FLOW THIS MORNING AND AGAIN TONIGHT (MIXES INTO CU DECK THIS AFTERNOON). MODELS DO NOT RESOLVE ALTOCU DECK APPROACHING FROM THE WEST WELL AND HAD TO ACCOUNT FOR THIS TODAY. WITH SOME SUNSHINE AND SOME CLOUDS STAYED CLOSE TO GUIDANCE ON TEMPERATURES TODAY. LOW PRESSURE CENTER APPROACHES FROM THE SOUTHWEST TONIGHT AND TRACKS UP WEST OF AREA MONDAY. ETA FARTHER WEST THAN GFS AND PLAYED A COMPROMISE PER HPC. INSTABILITY AND CONVERGENCE ZONE BEGINNING TO SET UP OVER THE AREA CAN LEAD TO CONVECTION AS EARLY AS LATE TODAY SOUTHWEST PART OF CWA. THIS SPREADS NORTH AND EAST THIS EVENING BEFORE ATMOSPHERE STABILIZES. ROLLED WITH JUST SHOWERS FOR LATTER HALF OF NIGHT. ISENTROPIC LIFT BEGINS IN ERNEST LATE TONIGHT AS LOW APPROACHES. GIVEN LOW TRACK...MOST OF WARM ADVECTION PRECIPITATION SHOULD TRACK NORTHWEST OF THE AREA THOUGH CLIPPING OHIO COUNTIES. FOR MONDAY MORNING WENT WITH SHOWERS EAST AND SHOWERS AND THUNDERSTORMS WEST CLOSER TO WARM SECTOR AND INSTABILITY. BY LATE MONDAY MUCH OF AREA IS IN WARM SECTOR WITH GOOD THETA E FEED AND INSTABILITY SO LIKELY SHOWERS AND THUNDERSTORMS WARRANTED ALL ZONES BEFORE THE DAY IS OUT. HIGH PW WITH THIS SYSTEM SUPPORTS POTENTIAL FOR HEAVY BUT NOT NECESSARILY EXCESSIVE RAINFALL AS AREA SHOULD BE ABLE TO HANDLE IT GIVEN SUMMER VEGETATION AND DRY JULY FOR THE MOST PART. CLOSE TO GUIDANCE TEMPERATURES FOR TONIGHT. GUIDANCE IS SPREAD MONDAY AND THIS IS TIED TO DIFFERENCES IN TRACK OF LOW WHICH IN TURN DETERMINES PROGRESS OF WARM SECTOR NORTHWARD INTO THE AREA. WENT WITH COMPROMISE HERE GIVEN COMPROMISE SOLUTION ACCEPTED ON LOW TRACK. POTENTIAL FOR STRONG THUNDERSTORMS EXISTS MONDAY AFTERNOON BUT CAPE AND WIND FIELD COMBINATION FALLS SHY OF SEVERE THREAT. PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 316 AM EDT SUN JUL 25 2004 LONG TERM (MONDAY NIGHT THROUGH SATURDAY)... IT STILL LOOKS LIKE A WET START TO THE LONG TERM WITH A SFC WARM FRONT CROSSING MONDAY NIGHT THEN A COLD FRONT TUESDAY. 00Z NCEP CHAIN HANDLING THINGS QUITE DIFFERENTLY WITH ETA HAVING A MORE AMPLIFIED SOLUTION...WHICH GETS BACKING FM 12Z ECMWF...WHILE GFS OFFERS A MORE PROGRESSIVE OUTPUT AND TRACKS SFC LOW 300 MILES FARTHER E AND N THAN THE ETA. OPTED FOR THE ETA MODEL SINCE IT HAS RUN TO RUN CONTINUITY. DRY CONVEYOR BELT WORKS IN TUESDAY AFTERNOON AND ALIGNS ITSELF ALONG AND IMMEDIATELY BEHIND THE BAROCLINIC ZONE. THIS WILL BE MONITORED GIVEN A GOOD SHOT OF MID LEVEL DRYING OCCURS AS H5 DEWPOINTS FALL TO -45 TO -50C. THIS COULD LEAD TO GUSTY THUNDERSTORM WINDS WHEN THE FRONT PASSES TUESDAY AFTERNOON AND EVENING EVEN THOUGH CONVECTIVE PARAMETERS REMAIN MARGINAL FOR THIS TIME OF YEAR (LI/S OF -1C AND SBCAPES RUN 0.7 KJ/KG). POST FRONTAL AIRMASS REMAINS UNSTABLE WITH MID LEVEL LAPSE RATES OF 6.0 C/KM COURTESY OF H5 LOW REMAINING STATIONARY IN THE GREAT LAKES. TIME HEIGHTS AND BUFKIT SOUNDINGS ILLUSTRATE LLVL MSTR NEVER CLEARS OUT...SO CONTINUED CHANCE OF RW/TRW...MAINLY DURING THE AFTN AND EVENING. INCREASED POPS TO LKLY MON NGT AND TUES AREA WIDE WITH LKLYS EXTENDING INTO TUES NGT FOR HEADWATERS OF THE GREENBRIER RIVER AND CENTRAL WV MTNS...CHC ELSW. HIGHS TUESDAY WERE LOWERED ACCOUNTING FOR A OVC SKY AND RA. QPF TOTALS OFF THE GFS MON NGT THROUGH TUES NGT ARE PROGGED TO REACH 2.5 INCHES IN THE MOUNTAINS WITH 1.5 INCHES WEST OF THE OHIO RIVER. PAST SYNOPTIC SETUPS SIMILAR TO THIS FAVOR AXIS OF HIGHER PRECIP ALONG AND WEST OF THE OHIO RIVER...WHICH THE ETA SUGGEST. RIGHT NOW...NOT KEEN ON FFA POTENTIAL...HOWEVER IF TRAINING OCCURS AHEAD OF THE WARM FRONT THEN THINGS WOULD CHANGE. PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 229 AM EDT SUN JUL 25 2004 AVIATION... LIGHT NORTHEAST FLOW OVERNIGHT. 2-3.5KFT DECK AGAIN FORMING ON COOLING OF THE TOP OF THE MIXING LAYER. CRW ALREADY SOCKED IN WITH RADIATION FOG. THIS WILL ACTUALLY BREAK UP AT TIMES WITH AFOREMENTIONED DECK ROLLING IN AND OUT OF THE AREA. EKN BACK UP TO 5SM BUT WILL GO LIFR ON FOG AT TIMES OVERNIGHT. AGAIN STRATOCU DECK FORMING ABOVE THIS WILL KEEP EKN FROM STAYING LIFR. MVFR TO IFR DECK MAY SHOW UP AT BKW BEFORE DAWN ON SE FLOW. SURFACE TROUGH SETS UP OVER AREA TURNING FLOW SE IN MOUNTAINS WHILE REMAINING NORTHEAST OVER THE LOWLANDS. PATCHY CLOUDS WILL AGAIN EVOLVE INTO CU DECK FOR THE AFTERNOON. A LOW PRESSURE CENTER WILL APPROACH FROM THE SOUTHWEST TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND THUNDERSTORMS AS FAR NORTHEAST AS HTS-CRW-BKW LATE TODAY. THIS IS OUT AHEAD OF THE APPROACHING WEATHER SYSTEM AND MAY BE DIURNALLY DRIVEN TO A LARGE EXTENT...SO DECREASING CHANCE TOWARD 6Z. CHANCE TOO SMALL TO CODE IN EXPLICITLY AT THIS TIME. OTHERWISE NO CHANGE IN THE FLOW TONIGHT OTHER THAN DIMINISHING WIND SPEEDS. EKN WILL AGAIN RADIATE WITH MVFR ON VIS BY 6Z WHILE LOW (MVFR) CLOUDS ROLL BACK INTO BKW ON SE FLOW. INCREASING CHANCE FOR RAIN ALL SITES AFTER 6Z INTO MONDAY AS LOW PRESSURE CENTER APPROACHES THE AREA. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. VA...NONE. KY...NONE. OH...NONE. && $$ AVIATION...TRM SHORT TERM...TRM LONG TERM...FWM