Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 250602 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 202 AM EDT SAT APR 25 2015 .UPDATE... ISSUED AT 202 AM EDT SAT APR 25 2015 WITH EXTENSIVE CLOUD COVER IN PLACE...TEMPS HAVE NOT DROPPED OFF AS QUICKLY AS WAS FORECAST. HAVE RAISED OVERNIGHT FORECAST MIN TEMPS A BIT...ESPECIALLY IN EASTERN VALLEYS. UPDATE ISSUED AT 1050 PM EDT FRI APR 24 2015 DID AN UPDATE TO FINE TUNE THE POPS AND WX THROUGH THE REST OF THE NIGHT BASED ON THE NEWEST HRRR AND NAM12 GUIDANCE AS WELL AS CURRENT RADAR/OBS. ALSO MATCHED UP THE HOURLY T AND TD GRIDS PER THE LATEST OBS AND TRENDS...WHERE A 5 DEGREE OR SO RIDGE TO VALLEY SPLIT CURRENTLY EXISTS IN THE EAST. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS...ALONG WITH THE ISSUANCE OF A FRESHENED SET OF ZONES. UPDATE ISSUED AT 745 PM EDT FRI APR 24 2015 23Z SFC ANALYSIS SHOWS HIGH PRESSURE CLINGING ON IN THE FAR EAST IN THE FACE OF AN APPROACHING AREA OF LOW PRESSURE...POISED TO BRING SVR WX TO KY LATER ON SATURDAY...FROM THE WEST. THIS WESTERN LOW/S WARM FRONT WILL SWING TOWARD THE AREA BY DAWN... AFFECTING THE FAR SOUTHWEST INITIALLY THEN LIFTING DEEPER INTO EAST KENTUCKY THROUGH MIDDAY SATURDAY. THE PCPN WILL HAVE A TOUGH TIME REACHING THE GROUND ACROSS THE AREA THROUGH THE BULK OF THE NIGHT AS THE VERY DRY LOWER ATMOSPHERE ONLY SLOWLY SATURATES... DESPITE THE HRRR/NAM12 INDICATIONS. IN THIS ENVIRONMENT...EXPECT THE EASTERN VALLEYS TO DROP OFF QUICKLY FOLLOWING SUNSET...EVEN WITH THE THIN HIGH CLOUDS NOW IN PLACE OVERHEAD. ELSEWHERE... TEMPERATURES WILL STAY UP THROUGH THE NIGHT...MUCH WARMER THAN LAST NIGHT. HAVE UPDATED THE FORECAST TO NUDGE TEMPS IN THE EASTERN VALLEYS DOWN A BIT...BUT EXPECT THEM TO MIX OUT BY DAWN AS THE AIR SATURATES AND SHOWERS PUSH OVER THIS PART OF THE STATE. IN ADDITION TO THE SEVERE THREAT FOR SATURDAY...THE LATEST MODEL RUNS CONTINUE TO INDICATE THAT THERE IS ALSO A POTENTIAL FOR EXCESSIVE RAINFALL DEPENDING ON THE TRACKS OF THE INDIVIDUAL CELLS AND/OR AN MCS TRACKING ACROSS THE CWA IN THE AFTERNOON/EVENING THAT CERTAINLY LOOKS POSSIBLE. THESE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 350 PM EDT FRI APR 24 2015 CURRENT CONDITIONS ACROSS THE AREA FEATURE SURFACE HIGH PRESSURE SLOWLY SLIDING OFF TO THE EAST TODAY. MID AND UPPER LEVEL CLOUD COVER AT THIS TIME IS BEGINNING TO STREAM INTO EASTERN KENTUCKY THIS EVENING. THIS IS AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM OUT WEST OVER THE CENTRAL PLAINS. CLOUD COVER OVER THE AREA WILL LIKELY KEEP TEMPERATURES OVERNIGHT NEARLY UNIFORM WITH SOUTHERLY WARM AIR MOVING INTO THE AREA THROUGH THE NIGHT. AT THIS TIME OVERNIGHT...THE SURFACE LOW SLIDES EAST AS A WARM FRONT DEVELOPS IN THE LOWER MS VALLEY AND MOVING NORTHEAST. THIS WILL BRING SHOWERS INTO EASTERN KENTUCKY BY MIDNIGHT OR SHORTLY AFTERWARD. HEADING INTO THE PREDAWN HOURS SATURDAY MORNING...THE MAIN SURFACE LOW BEGINS TO MOVE INTO THE MID MS RIVER VALLEY AND INTO THE MIDWEST WITH SOME INSTABILITY BEGINNING TO ENTER THE SOUTHWESTERN COUNTIES AND THIS MAY LEAD TO A FEW EARLY NON SEVERE STORMS AND MAY NEED TO ADD THUNDER TO THE TONIGHT PERIOD OF THE HWO. HEADING INTO THE DAY ON SATURDAY...AFTER EARLIER RAINFALL HAS MOVED THROUGH...SOME CLEARING SKIES AND RECOVERING ENERGY AND DESTABILIZATION WILL THEN OCCUR WITH MOST UNSTABLE CAPE AROUND 1000 TO 1500 J/KG OVER SOUTHEASTERN KENTUCKY BY THE 18Z TIME FRAME. THIS ALSO WITH SOME 60 KNOT SFC TO 6KM BULK SHEAR WILL BE ENOUGH FOR SOME ROTATING STORMS TOMORROW AFTERNOON. DUE TO THIS THREAT SPC HAS PUT THE SOUTHERN AREA IN AN ENHANCED THREAT OF SEVERE WEATHER AND HAVE PUT THIS THREAT IN THE HWO AND MAY NEED AN SPS TO HIGHLIGHT THE THREAT IN DETAIL. THE ONLY THREAT THAT IS A BIT QUESTIONABLE TOMORROW WILL BE THE FLASH FLOOD THREAT. THOUGH THE LAST HEAVY RAINFALL WAS LONG ENOUGH AGO THAT MOST PLACES HAVE BEEN ALLOWED TO DRAIN AND DRY OUT. AS WELL...GREEN HAS GONE INTO FULL SWING ACROSS THE AREA ALLEVIATING THE RUNOFF POTENTIAL. HOWEVER...THE DISCRETE SUPER CELL POTENTIAL WILL ADD TO THE THREAT OF FLASH FLOODING AS WELL AS IF AN MCS DEVELOPS BY LATE IN THE EVENING ON SATURDAY. MAY NEED TO EVALUATE THIS DURING THE NEXT MODEL RUN. HEADING INTO SATURDAY EVENING...THE WARM FRONT MOVES THROUGH TO THE NORTHEAST AND THEN THE SURFACE LOW TRACKS RIGHT ACROSS EASTERN KENTUCKY WITH ANOTHER STRONG SHOT OF RAINFALL WHICH MAY BE ENOUGH TO INITIATE THE FLASH FLOOD THREAT. HAVE ADJUSTED THE QPF FOR THE 00Z TO 06Z SUNDAY NIGHT PERIOD FOR THIS RAINFALL. RAINFALL AMOUNTS WILL BE LESSENING BY 06Z TO 12Z RANGE SUNDAY NIGHT AS THE EVENT WILL BE WINDING DOWN. FOR NOW...WILL HIGHLIGHT THE SEVERE AND FLOOD THREAT IN THE HWO AND MAY NEED AN SPS TO FURTHER HIGHLIGHT THIS. THE ZFP WILL HAVE SEVERE POTENTIAL AND HEAVY RAINFALL MENTIONED AS WELL. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 PM EDT FRI APR 24 2015 ANY REMAINING RAINFALL SHOULD BE WINDING DOWN BY SUNDAY MORNING AS THE SFC LOW AND TRAILING COLD FRONT PUSH EAST OF KY. BEHIND THIS... SKIES WILL GRADUALLY CLEAR AS DRY AIR FILTERS INTO THE REGION SUNDAY EVENING...ALLOWING FOR EASTERN KENTUCKY TO RECEIVE A BREAK FROM THE WET WEATHER TO START THE WORK WEEK. THIS IS DUE TO AN AREA OF HIGH PRESSURE FORECAST TO MOVE SLOWLY ACROSS THE OH AND TN VALLEYS MONDAY AND TUESDAY. A LARGE CUTOFF LOW WILL THEN GRADUALLY MOVE EWD FROM TX ACROSS THE SOUTHEASTERN US WEDNESDAY THROUGH THURSDAY. AS THE LOW MOVES EWD ITS ENERGY IS FORECASTED TO GET WRAPPED INTO A DEEPENING NORTHERN STREAM TROUGH. THE MODELS HAVE COME INTO BETTER AGREEMENT IN THE PAST COUPLE OF RUNS WITH THE EVOLUTION OF THIS SYSTEM...WHERE THE ECMWF SOLUTION HAS THE AREA OF LOW PRESSURE MOVING ALONG A TRACK SIMILAR TO THAT OF THE GFS. HOWEVER...THE ECMWF SOLUTION KEEPS THE LOW CUT OFF AND SEPARATE FROM THE NORTHERN STREAM TROUGH...CREATING QUITE A BIT MORE PRECIP THAN THE GFS ACROSS EASTERN KENTUCKY THROUGH THE END OF THE WORK WEEK. WITH UNCERTAINTY STILL EXISTING IN THIS PART OF THE EXTENDED...DECIDED TO KEEP PRECIP IN DURING THE WED/THURS TIME FRAME...AND STUCK CLOSE TO THE CR SUPERBLEND. TEMPERATURES WILL GENERALLY BE BELOW NORMAL AND STAY IN THE 60S FOR HIGHS AND IN THE 40S FOR LOWS THROUGHOUT THE EXTENDED. DURING THE DRIER PERIODS...TEMPS WILL BE CLOSER TO NORMAL VALUES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 202 AM EDT SAT APR 25 2015 VFR CONDITIONS WERE PRESENT AT TAF ISSUANCE...BUT WILL DEGRADE TO MVFR FROM SW TO NE BETWEEN ABOUT 06Z AND 14Z AS RAIN DEVELOPS. IFR IS ALSO EXPECTED AT TIMES THROUGH EARLY AFTERNOON. STEADY PRECIPITATION WILL TAPER OFF FROM SW TO NE DURING THE LATE MORNING AND EARLY AFTERNOON...AND WILL BE REPLACED BY SCATTERED SHOWERS AND THUNDERSTORMS. THEY WILL BECOME MORE NUMEROUS LATE IN THE DAY AND THIS EVENING. SOME LOCATIONS MAY DESCEND BACK TO IFR WITH THE SHOWERS AND STORMS THIS EVENING. SOME OF THESE STORMS COULD PRODUCE HAIL AND HIGH WINDS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...SHALLENBERGER LONG TERM...JVM AVIATION...HAL

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