Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 241737 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 137 PM EDT FRI APR 24 2015 .UPDATE... ISSUED AT 942 AM EDT FRI APR 24 2015 UPDATED THE FORECAST TO REMOVE THE FREEZE WARNING AS TEMPERATURES HAVE WARMED INTO THE MID TO UPPER 30S. ALSO UPDATED THE HWO AND ZFP FOR THESE CHANGES. UPDATE ISSUED AT 807 AM EDT FRI APR 24 2015 UPDATED TO BLEND EARLY MORNING OBS INTO THE FORECAST. NO SUBSTANTIAL CHANGES WERE MADE. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 416 AM EDT FRI APR 24 2015 COOL SURFACE HIGH PRESSURE WAS OVERHEAD EARLY THIS MORNING...WITH SUBFREEZING TEMPERATURES IN MANY PLACES. AN UPPER LEVEL RIDGE WAS JUST TO OUR WEST...AND HIGH CLOUDS WERE SPILLING OVER THE RIDGE INTO OUR SOUTHWEST COUNTIES. THE NEXT STORM SYSTEM WAS TAKING SHAPE OVER THE PLAINS...AND WILL HEAD EAST TO THE LOWER OHIO VALLEY BY THE END OF THE PERIOD. THE SURFACE HIGH WILL MOVE TO OUR EAST TODAY AND WARM AIR ADVECTION WILL BRING GULF OF MEXICO MOISTURE NORTHWARD AHEAD OF THE NEXT STORM SYSTEM. THIS WILL CAUSE CLOUDS TO LOWER AND THICKEN THIS AFTERNOON AND EVENING...AND SHOWERS WILL DEVELOP FROM SW TO NE LATE TONIGHT AND ON SATURDAY MORNING. BOTH THE GFS AND NAM SUGGEST THE PRECIP ASSOCIATED WITH THE WARM AIR ADVECTION WILL SHIFT TO OUR NE ON SATURDAY AFTERNOON...AND A WARM FRONT WILL MOVE NORTH INTO KY. AREAS NEAR AND SOUTH OF THE WARM FRONT ARE EXPECTED TO BECOME VERY UNSTABLE. THE GREATEST INSTABILITY IN THE JKL FORECAST AREA SHOULD BE OVER THE CUMBERLAND RIVER BASIN. FORECAST SOUNDINGS SHOW STRONG SHEAR...DRY MID LEVELS...AND LARGE MID LEVEL CAPE IN THAT AREA. IF THUNDERSTORMS ARE ABLE TO DEVELOP NEAR THE WARM FRONT AND IN THE WARM SECTOR AS SURFACE LOW PRESSURE APPROACHES FROM THE WEST AT THE END OF THE DAY...THEY WOULD POSE A SIGNIFICANT SEVERE WX THREAT. LARGE HAIL IS ESPECIALLY A CONCERN...BUT DAMAGING WINDS AND TORNADOES COULD ALSO OCCUR. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 330 AM EDT FRI APR 24 2015 THE MODELS HAVE FINALLY COME INTO PRETTY AGREEMENT IN THE EXTENDED. THE LATEST RUN OF THE GFS NOW CLOSELY RESEMBLES THE LATEST ECMWF FOR MOST OF THE EXTENDED PERIOD. THE PERIOD IS PROGGED TO START OFF WITH FAIRLY WIDESPREAD RAINFALL ACROSS EASTERN KENTUCKY. BASED ON THE LATEST MODEL SOUNDINGS...IT ALSO APPEARS THERE WILL BE A GOOD CHANCE OF SOME THUNDERSTORMS ONGOING AT THE START OF THE PERIOD...LIKELY THROUGH EARLY SUNDAY MORNING BEFORE THE INSTABILITY AND LIFT MOVES FAR ENOUGH EAST FOR THUNDER TO COME TO AN END. LOCALLY HEAVY RAINFALL WILL POSSIBLE DURING THE HIGHEST PRECIPITATION PROBABILITIES. AFTER THE LAST OF THE RAIN FINALLY EXITS THE AREA SUNDAY AFTERNOON...THE RESIDENTS OF EASTERN KENTUCKY SHOULD EXPERIENCE A NICE BREAK FROM THE WET WEATHER TO BEGIN THE NEW WORK WEEK. THE MODELS BOTH AGREE THAT A RIDGE OF HIGH PRESSURE...BOTH AT THE SURFACE AND ALOFT...IS EXPECTED TO MOVE SLOWLY ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS MONDAY AND TUESDAY. THIS RIDGE WILL BRING DRY AND WARMING WEATHER TO THE AREA TO START THE WEEK. A RATHER WELL DEVELOPED AREA OF LOW PRESSURE IS THEN FORECAST TO MIGRATE ACROSS CENTRAL MISSISSIPPI...ALABAMA...AND GEORGIA WEDNESDAY THROUGH THURSDAY. THE MODELS DO DIFFER A BIT HERE...HOWEVER...IN THAT THE ECMWF BRINGS MORE MOISTURE NORTHWARD INTO THE OHIO VALLEY THAN THE GFS DOES. THE ECMWF SOLUTION ALSO BRINGS HAS ITS AREA OF LOW PRESSURE MOVING ALONG TRACK THAT IS FURTHER NORTH THAN THE GFS. THE END RESULT IS FOR THE ECMWF SOUTHERN TRACK LOW TO PHASE WITH A TROUGH OF LOW PRESSURE THAT IT HAS MOVING DOWN FROM THE GREAT LAKES AREA WEDNESDAY NIGHT AND THURSDAY...WHILE THE GFS KEEPS ITS SOUTHERN TRACK LOW FAR ENOUGH SOUTH THAT IT DOES NOT COUPLE WITH THE NORTHERN STREAM TROUGH. THEREFORE...THE ECMWF IS PRODUCING QUITE A BIT MORE PRECIPITATION ACROSS EASTERN KENTUCKY TOWARD THE END OF THE PERIOD THAN THE GFS. WITH UNCERTAINTY STILL EXISTING DURING THIS PART OF THE EXTENDED...DECIDED TO KEEP IN PRECIPITATION FOR THE WEDNESDAY THURSDAY TIME PERIOD...BUT WITH MUCH LOWER PROBABILITIES THAN THE LATEST ECMWF MODEL DATA ARE CURRENTLY SUGGESTING. DAYTIME HIGHS IN THE EXTENDED LOOK TO BE BELOW NORMAL DURING THE PERIODS WITH WIDESPREAD CLOUD COVER AND PRECIPITATION...AND CLOSE TO NORMAL TOWARD THE END OF THE PERIOD WHEN THE WEATHER IS EXPECTED TO BE DRY. OVERNIGHT LOWS ARE EXPECTED TO FOLLOW THE SAME GENERAL PATTERN...WITH NORMAL VALUES ON TAP FOR THE END THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 140 PM EDT FRI APR 24 2015 VFR CONDITIONS ARE EXPECTED THROUGH LATE TONIGHT. RAIN WILL MOVE IN FROM THE SOUTHWEST OVERNIGHT AND CEILINGS WILL LOWER TO MVFR TOWARD DAWN. LATER IN THE AFTERNOON...THUNDERSTORMS ARE EXPECTED TO DEVELOP...SOME OF WHICH MAY BECOME SEVERE. WITH THESE STORMS...CONDITIONS CAN BE TEMPORARILY REDUCED TO NEAR ALTERNATE MINS OR BELOW DEPENDING ON THE SEVERITY OF THE STORM. SO HAVE LOWERED VIS TO ALTERNATE MINS ACROSS ALL TAF SITES WITH VCTS BETWEEN 15 AND 18Z. GUSTY WINDS ARE ALSO EXPECTED WITH ANY THUNDERSTORM ACTIVITY. OTHERWISE...WINDS WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...HAL LONG TERM...AR AVIATION...JVM/SHALLENBERGER

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