Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 230744 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 344 AM EDT THU APR 23 2015 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 326 AM EDT THU APR 23 2015 SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION TODAY WITH COOL AND VERY DRY AIR UNDER NW FLOW ALOFT. A RESPECTABLE PRESSURE GRADIENT AHEAD OF THE HIGH WILL ALLOW WINDS TO BE GUSTY ONCE MIXING OCCURS TODAY. AS THE HIGH CENTER APPROACHES AND PASSES OVER TONIGHT...WINDS WILL DIMINISH. WITH DRY AIR AND CLEAR SKIES...THIS WILL ALLOW TEMPS TO FALL OFF QUICKLY. THINK THAT MOST AREAS WILL SEE AT LEAST SOME FROST. IT SHOULD BE EXTENSIVE IN OUR NORMALLY COLD VALLEYS...WHERE READINGS AT LEAST DOWN TO THE UPPER 20S ARE EXPECTED. HAVE USED A FROST ADVISORY AREA-WIDE AT THIS POINT...AND A FREEZE WARNING WAS DISCUSSED. IF THE NEXT SHIFT FEELS THE NEED...THERE WILL STILL BE TIME TO UPGRADE TO A WARNING. THE HIGH WILL MOVE TO OUR EAST ON FRIDAY AND WARM AIR ADVECTION OFF THE GULF OF MEXICO WILL ENSUE. THIS WILL BRING INCREASING CLOUDS...BUT PRECIP IS QUESTIONABLE...AND IS LIKELY TO HOLD OFF UNTIL THE LONG TERM PERIOD. THE NAM SHOWS .01-.02 INCHES IN OUR FAR SW BY 00Z SATURDAY...BUT THE GFS AND ECMWF ARE BOTH DRY. HAVE USED ONLY A 20 PERCENT POP IN THE FAR SW. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 344 AM EDT THU APR 23 2015 THE MODELS ARE IN PRETTY GOOD AGREEMENT TO BEGIN THE EXTENDED PERIOD...WITH BOTH THE GFS AND ECMWF DEPICTING A LARGE SCALE UPPER TROUGH EJECTING OUT OF THE WEST CENTRAL PLAINS AND ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS SATURDAY AND SUNDAY. THIS SYSTEM IS POISED TO BRING ANOTHER GOOD SOAKING RAIN EVENT TO EASTERN KENTUCKY FOR THE UPCOMING WEEKEND. THE LATEST SOUNDINGS INDICATE THAT THUNDERSTORMS WILL BE POSSIBLE FROM SATURDAY AFTERNOON THROUGH EARLY SUNDAY MORNING...AS AN AREA OF LOW PRESSURE MOVES ACROSS KENTUCKY. THE RAIN COULD BE LOCALLY HEAVY AT TIMES SATURDAY AND SATURDAY NIGHT. AT THIS TIME...THERE IS EVEN AN OUTSIDE CHANCE THAT A FEW STRONG TO SEVERE STORMS MAY OCCUR ON SATURDAY ACROSS SOUTHWESTERN AND SOUTHERN PORTIONS OF THE FORECAST AREA. THERE IS STILL SOME UNCERTAINTY AS TO HOW MUCH INSTABILITY WILL BE AVAILABLE TO SUPPORT STRONGER STORMS...SO THIS SITUATION WILL CONTINUE TO BE MONITORED CLOSELY IN THE COMING DAYS. ONCE THIS INITIAL WEATHER SYSTEM DEPARTS THE REGION ON SUNDAY...IT DOES APPEAR THAT THERE WILL BE A PERIOD OF QUIET WEATHER SUNDAY NIGHT THROUGH LATE IN THE DAY ON TUESDAY AS A RIDGE OF HIGH PRESSURE SETTLES OVER THE AREA. AFTER THAT...HOWEVER...IS WHEN THE MODELS DIVERGE GREATLY IN THEIR RESPECTIVE SOLUTIONS. THE ECMWF MODEL KEEPS THE OHIO AND TENNESSEE VALLEYS FREE OF PRECIPITATION FOR THE REST OF THE WEEK...WHILE THE GFS BRINGS ANOTHER LARGE AND MOISTURE LADEN WEATHER SYSTEM OUT OF THE SOUTHERN PLAINS AND ACROSS OUR NECK OF THE WOODS. IN FACT...IF THE GFS VERIFIES...WE WOULD SEE A PROLONGED PERIOD OF WET WEATHER FROM LATE TUESDAY THROUGH THURSDAY. WITH ALL THAT BEING SAID...IT DID NOT MAKE SINCE TO GO ALL IN ON EITHER MODEL SOLUTION...SO A COMPROMISE WAS MADE. AFTER INGESTING THE MODEL BLEND DATA...DECIDED TO DECREASE THE RESULTING POPS FOR TUESDAY ONWARD TO WELL BELOW THE ORIGINAL NUMBERS...GOING WITH GENERAL SLIGHT CHANCE TO CHANCE PROBABILITIES OF PRECIPITATION FOR THE PERIOD TUESDAY ONWARD. THIS SECOND AREA OF LOW PRESSURE LOOKS TO LACK GOOD INSTABILITY...AT LEAST THE GFS VERSION THAT HAS PRECIP...SO THUNDER WAS LEFT OUT AT THIS TIME WITH THE SECOND WEATHER SYSTEM. TEMPERATURES DURING THE EXTENDED PERIOD LOOK LIKE THEY WILL BE SLIGHTLY BELOW NORMAL FOR THE TIME OF YEAR. THE PRIMARY REASONS FOR THIS WILL BE CLOUD COVER AND PRECIPITATION ASSOCIATED WITH THE AFOREMENTIONED WEATHER SYSTEMS. HIGHS EACH DAY ARE EXPECTED TO TOP OUT IN THE 60S...WITH OVERNIGHT LOWS MOSTLY IN THE LOW TO MID 40S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 143 AM EDT THU APR 23 2015 VFR CONDITIONS WILL PERSIST THROUGH THE PERIOD. THE ONLY CONCERN WILL BE WINDS. THEY WILL INCREASE FROM THE WEST NORTHWEST DURING THE DAY...WITH GUST FROM 15-20 KTS. WINDS WILL THEN DIMINISH ON THURSDAY EVENING. && .JKL WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR KYZ044-050>052- 058>060-104-106-108-111. && $$ SHORT TERM...HAL LONG TERM...AR AVIATION...HAL

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