Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 290758 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 358 AM EDT MON SEP 29 2014 .SHORT TERM...
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(TODAY THROUGH TUESDAY) ISSUED AT 357 AM EDT MON SEP 29 2014 SHOWERS FALLING FROM A HIGH CLOUD BASE WERE NEAR THE KY/VA BORDER OVERNIGHT. THIS REGIME IS EXPECTED TO MOVE OUT TO THE SOUTHEAST EARLY MONDAY MORNING. AFTER A LULL...THERE WILL BE A POTENTIAL FOR MORE SHOWERS TO DEVELOP DURING THE DAY AS HEATING LEADS TO SHALLOW INSTABILITY. IT SHOULD BE CAPPED AROUND 650 MB. THIS LEVEL IS TOO WARM FOR GLACIATION OF CLOUD TOPS...BUT ALLOWS FOR A DEEP ENOUGH CLOUD TO PERHAPS GET SOME LIGHT SHOWERS OR SPRINKLES. THESE WILL DIE OUT WITH LOSS OF HEATING MONDAY EVENING. DURING THE NIGHT...SLIGHTLY DRIER AIR IS EXPECTED TO ARRIVE IN THE LOWER LEVELS...WHILE SLIGHT WARMING OCCURS IN THE MID LEVELS. THIS WILL KEEP TUESDAY DRY AND MOSTLY SUNNY WITH LITTLE OR NO CU DEVELOPMENT. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 357 AM EDT MON SEP 29 2014 MODELS ARE STARTING TO WAVER A BIT WITH AN EXPECTED COLD FRONT ON FRIDAY...BUT OVERALL STILL IN AGREEMENT ON WIDESPREAD SHOWERS FOR EASTERN KENTUCKY AS IT PUSHES ACROSS THE AREA. MODELS ARE ALSO DIVERGING ON POSSIBLE SOLUTIONS HEADING THROUGH NEXT WEEKEND. THUS...WHILE CONFIDENCE REMAINS HIGH ON PRECIPITATION CHANCES...CONFIDENCE IS DEGRADED AROUND THE TIMING OF THE RAIN LATE IN THE WEEK...THEN EXACTLY HOW COLD/CLOUDY IT WILL END UP THIS WEEKEND. THE PERIOD WILL START WITH SFC HIGH PRESSURE IN CONTROL...SETTING UP DRY AND MILD CONDITIONS INTO THE DAY ON THURSDAY. A SHARP MID LEVEL TROUGH AXIS WILL THEN PUSH ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY...DRAGGING A WEAK COLD FRONT ACROSS THE AREA. GOOD UPPER LEVEL DIVERGENCE...COMBINED WITH GOOD LOW LEVEL CONVERGENCE SHOULD PROVIDE PLENTY OF SUPPORT FOR WIDESPREAD SHOWERS. WHILE INSTABILITY IS WEAK...FORCING MAY BE STRONG ENOUGH JUST AHEAD OF THE FRONT TO PRODUCE A LIGHTNING STRIKE AS IT PUSHES ACROSS THE AREA. THUS...WILL MAINTAIN THE SLIGHT CHANCE OF THUNDERSTORMS. THE 00Z ECMWF SUPPORTS THE 12Z RUN WITH A FASTER SYSTEM...BRINGING PRECIPITATION IN FASTER THURSDAY NIGHT...WITH EVERYTHING EXITING EARLIER ON FRIDAY. HOWEVER...THE 00Z GFS HAS ALSO REMAINED SUPPORTIVE OF A SLOWER SYSTEM...WITH MORE PRECIPITATION OCCURRING ON FRIDAY. THUS...WILL MAINTAIN A LONGER PERIOD OF HIGHER POPS TO ACCOUNT FOR THIS UNCERTAINTY. REGARDLESS...THIS SYSTEM SHOULD PRODUCE DECENT LIGHT TO MODERATE RAINFALL ACROSS THE AREA. AS THE INITIAL FRONT DEPARTS...A SECONDARY COLD FRONT WILL BRING A SURGE OF MUCH COLDER WEATHER INTO THE AREA FOR THE START OF THE UPCOMING WEEKEND AS A 500MB VORT MAX PUSHES ACROSS THE GREAT LAKES. THE 00Z ECMWF CUTS OFF THIS SYSTEM...WITH A MUCH SHARPER TROUGH PUSHING SOUTH INTO THE OHIO RIVER VALLEY. THIS SCENARIO WOULD SUPPORT MORE CLOUDS AND MUCH COOLER READINGS. MEANWHILE...THE GFS DOES NOT CUT OFF THIS SYSTEM...AND IS MUCH WEAKER WITH THE TROUGH. GIVEN WE ARE HEADING INTO THE COLD SEASON...TENDENCY IS TO WANT TO SUPPORT THE SHARPER TROUGH SEEN IN THE ECMWF AS THE PATTERN WOULD BE SUPPORTIVE FOR THIS TIME OF THE YEAR. THUS...STAYING WELL BELOW GUIDANCE ON HIGHS AND LOWS FROM SATURDAY THROUGH SATURDAY NIGHT. IF THINGS PLAY OUT AS THE ECMWF SUPPORTS...WE MAY STRUGGLE TO REACH 60 ON SATURDAY WITH LOWS SATURDAY NIGHT INTO THE UPPER 30S/LOWER 40S. AT THIS TIME...REGARDLESS WHICH SOLUTIONS PLAYS OUT...FROST APPEARS UNLIKELY AS THE COLDER ECMWF WOULD SUPPORT MORE CLOUD COVER...AND THE GFS SIMPLY WOULD NOT BE COLD ENOUGH. IN FACT... THE ECMWF MAY SUPPORT A FEW RAIN SHOWERS ON SATURDAY OR SATURDAY NIGHT AS A VORT MAX DROPS SOUTH INTO THE OHIO RIVER VALLEY. GOING TO LEAVE THINGS DRY FOR NOW...BUT MAY NEED TO ADD SOME RAIN CHANCES IF THE ECMWF GAINS SUPPORT. BY SUNDAY...WE SHOULD SEE THE AIR MASS PERHAPS START TO MODIFY WITH TEMPERATURES REBOUNDING BACK INTO THE MID TO UPPER 60S.
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&& .AVIATION...
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(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 204 AM EDT MON SEP 29 2014 A FEW SHOWERS WERE OCCURRING NEAR THE VA BORDER AT THE START OF THE PERIOD. THEY WERE LIGHT AND WILL REMAIN SO UNTIL THEY TAPER OFF ON MONDAY MORNING. A FEW MORE SHOWERS MAY DEVELOP AFTER HEATING TAKES PLACE ON MONDAY...THEN DIE OUT TOWARD EVENING. HOWEVER...THE MAIN CONCERN WILL BE FOG THROUGH EARLY MORNING. ITS DEVELOPMENT WAS ALREADY WELL UNDERWAY IN VALLEYS AND BEGINNING TO SPREAD. TAF SITES ARE EXPECTED TO DROP TO IFR OR LOWER BEFORE DAWN. FOG SHOULD DISSIPATE BY LATE MORNING...LEAVING VFR.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HAL LONG TERM...KAS AVIATION...HAL

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