Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 281930 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 330 PM EDT THU MAY 28 2015 .SHORT TERM...
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(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 330 PM EDT THU MAY 28 2015 18Z SFC ANALYSIS SHOWS A WEAK PRESSURE PATTERN THROUGH THE AREA - AWASH IN A WARM AND HUMID AIR MASS. ALOFT - AN MCV IS MOVING SLOWLY NORTHEAST THROUGH THE CUMBERLAND VALLEY. THIS IS SUPPORTING A LARGE AREA OF THICK CIRRUS IN THE FORM OF DEBRIS CLOUDS COVERING THE SOUTHERN PORTION OF THE CWA. THIS HAS ALSO SUPPORTED AN AREA OF LIGHT RAIN BENEATH THE THICK CLOUDS...LIKEWISE SUPPRESSING TEMPERATURES KEEPING THEM IN THE LOW TO MID 70S. ON THE FRINGES OF THIS AREA...THE CLOUDS ARE MORE CUMULIFORM AND TEMPERATURES HAVE RISEN INTO THE 80S. THESE CONDITIONS ARE MORE CONDUCIVE TO THE DEVELOPMENT OF STORMS...THOUGH SO FAR IT HAS BEEN SLOW GOING... DESPITE AN UPTICK IN THE STRENGTH OF SHOWERS ALONG THE VIRGINIA BORDER. THROUGHOUT THE AREA...WINDS HAVE BEEN LIGHT AND VARIABLE WHILE DEWPOINTS HOLD IN THE LOW TO MID 60S. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST. THEY ALL DEPICT A MINOR CONVECTIVELY INDUCED SHORTWAVE LIFTING NORTHEAST THROUGH EASTERN KENTUCKY DURING THE REST OF THE DAY AND INTO TONIGHT. THIS WAVE IS MOVING THROUGH GENERALLY HIGH HEIGHTS OVER THE SOUTHEAST PORTION OF THE NATION. THESE HEIGHTS WILL HOLD THROUGH THE PERIOD...BUT A TROUGH DOES APPROACH THE WESTERN PORTION OF THE REGION BY SATURDAY MORNING. OTHERWISE...THE INFLUENCE OF THE MID LEVELS ON THE WX THROUGH EAST KENTUCKY WILL BE MINIMAL IN COMPARISON TO THE DIURNAL CYCLE. AS SUCH...HAVE FOLLOWED THE HIGHER RESOLUTION MODELS OF THE HRRR AND NAM12. SENSIBLE WEATHER WILL FEATURE CONVECTIVE ACTIVITY WINDING DOWN THROUGH THE EVENING...THOUGH THE SLOW PROGRESS OF THE MCV MAY SUSTAIN SOME SHOWERS BENEATH IT THROUGH THE NIGHT. PATCHY FOG... LOCALLY DENSE...CAN BE ANTICIPATED AGAIN TONIGHT IN LOCATIONS THAT SEE GOOD CLEARING AND THAT HAD PICKED UP SOME RAIN EARLIER IN THE DAY. FOR FRIDAY THE ONLY LIMITATION ON THE CONVECTION DEVELOPING WILL BE A LACK OF A TRIGGER AS THERE SHOULD BE PLENTY OF INSTABILITY AROUND. THE NAM12 AND ECMWF/GFS DO SHOW A WAVE OF CONVECTION PASSING THROUGH EASTERN KENTUCKY FRIDAY AFTERNOON HELPING TO JUSTIFY OUR HIGHER POPS FORECAST THAN THIS AFTERNOON. SIMILAR TO TONIGHT...EXPECT PARTIAL CLEARING AS THE CONVECTION WANES ALLOWING FOR PATCHY VALLEY FOG TO FORM AFTER MIDNIGHT AND LINGER INTO DAWN. USED THE SHORTBLEND AS A STARTING POINT FOR THE T/TD/WIND GRIDS INTO FRIDAY BEFORE SWITCHING TO THE SUPERBLEND THROUGH 12Z SATURDAY. MADE SOME MINOR RIDGE TO VALLEY TEMPERATURE DIFFERENCES FOR LOWS AND HOURLY TEMPS EACH NIGHT. AS FOR POPS...ENDED UP SIMILAR TO A BLEND OF THE DRIER MAV AND WETTER MET GUIDANCE THROUGH THE SHORT TERM WITH A MORE EXAGGERATED DIURNAL CYCLE IN THE HOURLY POPS/WX GRIDS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU MAY 28 2015 RIDGING WILL DAMPEN OUT A BIT THROUGH THE WEEKEND. A SHORTWAVE TROUGH WILL PUSH ACROSS THE OHIO RIVER VALLEY ON SATURDAY...WITH A FRONTAL BOUNDARY SHIFTING SOUTHEAST INTO THE REGION. THIS WILL LEAD TO INCREASING CHANCES FOR SHOWERS AND STORMS THROUGH THE UPCOMING WEEKEND. THE BETTER CHANCE FOR LESS ACTIVITY WILL BE SATURDAY...BUT BY SUNDAY...FRONTAL ZONE WILL BE VIRTUALLY OVERHEAD AND WEATHER LOOKS VERY UNSETTLED. A WEAK UPPER LEVEL TROUGH WILL THEN DEVELOP OVER THE LOWER MISSISSIPPI RIVER VALLEY INTO EARLY NEXT WEEK...WITH SOME WEAK IMPULSES KEEPING THE THREAT FOR SHOWERS AND STORMS GOING WELL INTO NEXT WEEK. BY WEEKS END...UPPER LEVEL RIDGING WILL BUILD BACK OVER THE REGION WITH HEIGHTS AGAIN ON THE INCREASE. HOWEVER...AN AFTERNOON SHOWER AND THUNDERSTORM WILL REMAIN POSSIBLE BENEATH THE RIDGE AS WE SHOULD HAVE PLENTY OF LOW LEVEL MOISTURE IN PLACE. HIGHS WILL REMAIN ABOVE NORMAL WELL INTO NEXT WEEK WITH 80S EXPECTED. LOWS WILL ALSO REMAIN ABOVE NORMAL IN THE 60S. NO REAL SIGNS OF ANY COOL DOWNS ON THE HORIZON.
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&& .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 230 PM EDT THU MAY 28 2015 HIGH AND MID LEVEL CLOUDS WILL BE THE RULE THROUGH THE TAF PERIOD WITH DIURNALLY DRIVEN CONVECTION AROUND MAINLY IN THE AFTERNOON AND EARLY EVENING. HAVE INTRODUCED VCTS FOR THIS THROUGH THE REST OF THE AFTERNOON AND AGAIN STARTING AT MIDDAY FRIDAY. CANNOT RULE OUT FOG FOR THE VALLEYS AGAIN TONIGHT...BUT MOST OF THE TAF SITES SHOULD STAY CLEAR. DID ADD A TEMPO FOR SOME MVFR VIS WITH BR AT THE SME SITE FOR LATE TONIGHT WHERE RAIN FROM THE PAST DAY MAY CONTRIBUTE ENOUGH EXTRA MOISTURE FOR ITS DEVELOPMENT. WINDS WILL REMAIN LIGHT AND GENERALLY FROM THE SOUTH THROUGH THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF

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