Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251920 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 320 PM EDT FRI JUL 25 2014 .SHORT TERM...
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(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 320 PM EDT FRI JUL 25 2014 HIGH PRESSURE WILL RULE OUR WEATHER TONIGHT. NORTHWEST FLOW ALOFT WILL TRANSPORT DEBRIS CLOUDS FROM THE THUNDERSTORM COMPLEX WELL TO OUR WEST OVER OUR AREA LATER THIS AFTERNOON INTO THE OVERNIGHT HOURS. THESE CLOUDS WILL HELP TO LIMIT FOG FORMATION TONIGHT AND HELP KEEP TEMPS GENERALLY IN THE UPPER 50S TO LOWER 60S. THE NORTHWEST FLOW PATTERN ALOFT WILL EASE UP BRIEFLY ON SATURDAY BEFORE REAMPLIFYING AGAIN FOR THE SECOND HALF OF THE WEEKEND. SHORTWAVE RIDGING AND A RETURN TO SOUTHWEST FLOW IN THE LOW LEVELS WILL BOOST TEMPS DURING THE DAY INTO THE UPPER 80S TO NEAR 90. DEWPOINTS WILL STAY BEARABLE DURING THE DAY...BUT BEGIN TO CLIMB BACK TOWARD 70 SATURDAY NIGHT. THUNDERSTORM ACTIVITY ASSOCIATED WITH AN ADVANCING COLD FRONT OVER THE UPPER MIDWEST AND GREAT LAKES IS EXPECTED TO SLOWLY SAG SOUTHEASTWARD ACROSS THE OHIO VALLEY SATURDAY. WILL INCLUDE A SLIGHT CHANCE OF A STORM LATE IN THE DAY ALONG AND NORTH OF I-64. THUNDERSTORMS CHANCES WILL THEN INCREASE FROM NORTH TO SOUTH SATURDAY NIGHT WITH THE POSSIBILITY OF A THUNDERSTORM COMPLEX DROPPING INTO THE AREA. STILL CONSIDERABLE UNCERTAINTY WITH THE PLACEMENT AND POTENTIAL STRENGTH OF THIS SYSTEM...BUT AREAS NORTH OF JKL STAND THE BEST CHANCE OF SEEING STORMS BEFORE DAWN ON SUNDAY. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 357 AM EDT FRI JUL 25 2014 AN AMPLIFIED LONG WAVE TROUGH WILL BE THE MAIN WEATHER PLAYER DURING THE EXTENDED FORECAST. A CLOSED UPPER LEVEL LOW OVER NE CANADA WILL SLOWLY PUSH SOUTHWARD DURING THE COURSE OF THE EXTENDED PERIOD...WITH SEVERAL SHORTWAVES FOLLOWING THE LONG WAVE PATTERN...DRIVING OUR TEMPS AND PRECIP. THE FIRST OF THESE SHORTWAVES WILL MOVE INTO THE GREAT LAKES BY SUNDAY AFTERNOON. AT THE SURFACE...A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL BE JUST AHEAD OF THE SHORTWAVE...PUSHING SE AS THE SHORTWAVE PROGRESSES. WARM HUMID AND UNSTABLE AIR WILL FILTER INTO THE REGION WELL AHEAD OF THE COLD FRONT...ALLOWING CONVECTION TO BEGIN AS EARLY AS 6 TO 12Z SUNDAY. IT SEEMS AS THOUGH THE LATEST MODELS ARE BACKING OFF ON THE START TIME OF THE PRECIP...SO THE ABOVE MENTIONED TIME HAS BEEN PUSHED BACK SLIGHTLY FROM THE PREVIOUS FORECAST. IN GOOD NEWS...ALL THE MID RANGE MODELS SEEM TO BE IN DECENT AGREEMENT WITH THIS SYSTEM...BOOSTING CONFIDENCE IN THIS LATER ONSET TIME. LOOKING AT THE LATEST FORECAST SOUNDINGS...STILL SUPPORTIVE OF A POSSIBLE SEVERE THREAT BY AFTERNOON/EVENING SUNDAY...WITH STEEP LAPSE RATES...CAPE VALUES 3-4.5 J/KG...STRONG WINDS IN BOTH THE MID AND UPPER LEVELS...AND DRYING IN THE MID LEVELS. NOT TO MENTION PWAT AMOUNTS WILL BE CLOSE TO 2 INCHES /1.93 FOR PIKEVILLE ACCORDING TO THE LATEST NAM/ FOR A 6 HOUR PERIOD BY SUNDAY AFTERNOON. NAM IS TRENDING SLIGHTLY HIGHER ON THE WATER CONTENT COMPARED TO THE GFS...BUT BOTH ARE STILL CONCERNEDLY HIGH FOR POSSIBLE FLASH FLOODING THREATS AS WELL. SPC HAS ALSO PUT MUCH OF KY AND POINTS TO THE E/NE IN A DAY 3 SLIGHT RISK FOR SEVERE THUNDERSTORMS AS WELL. THE UPPER LEVEL SHORTWAVE WILL MOVE TO OHIO BY 12Z MONDAY...WHILE THE SURFACE FRONT WILL HAVE PUSHED SE OF THE REGION. BOTH DRIER AND COOLER AIR WILL BEGIN FILTERING IN TO KY AS HIGH PRESSURE MOVES IN OVERHEAD. HOWEVER...WITH THE LINGERING INFLUENCE OF THE SHORTWAVE...AS WELL AS SOME LINGERING LOW LEVEL MOISTURE...THERE IS CONTINUED SUPPORT FOR SOME ISL/SCT SHOWERS AND TSTORMS REOCCURRING DURING THE AFTERNOON HOURS MONDAY. ONCE THE SHORTWAVE FINALLY MOVES WELL EAST OF THE REGION AND DRIER AIR CONTINUES TO TAKE HOLD...AND WE LOSE DIURNAL HEATING INFLUENCE...EXPECT ANY PRECIP CHANCES TO BE CUT OFF BY MONDAY NIGHT. THE WEATHER FOR BOTH TUESDAY AND WEDNESDAY LOOK GREAT...AND VERY UNSEASONABLE. THE LONGWAVE TROUGH...HAVING DROPPED SOUTHWARD...WILL ALLOW UNSEASONABLY COOL TEMPERATURES TO ADVECT INTO THE REGION. WHILE HIGHS MONDAY WILL BE IN THE MID AND UPPER 70S...BY TUESDAY THEY WILL HAVE DROPPED FURTHER...INTO THE LOW 70S FOR MUCH OF EASTERN KY. AIRMASS MODIFICATION AND ABUNDANT SUNSHINE WILL ALLOW TEMPERATURES TO MODERATE SOME BY WEDNESDAY...BUT STILL EXPECT A COOL UPPER 70S TO AROUND 80. AND WITH SURFACE HIGH PRESSURE STILL IN PLACE...AND DRY NRLY WINDS...PRECIP CHANCES WILL BE VIRTUALLY NIL. SADLY ALL GOOD THINGS MUST COME TO AN END. MODELS START TO LOSE AGREEMENT THIS FAR OUT IN THE FORECAST...BUT GENERAL CONSENSUS IS THAT SOME DIURNAL CONVECTION WILL START TO KICK BACK IN BY AFTERNOON THURSDAY ALONG THE HIGHEST TERRAIN...AS DEEPER MOISTURE SITS TO OUR SE. THEN THERE IS THE POTENTIAL FOR ANOTHER SHORTWAVE TO IMPACT THE REGION BY FRIDAY...BRINGING MORE WIDESPREAD CHANCES FOR CONVECTION. CONFIDENCE IN BOTH OF THESE IS STILL QUITE LOW AT THIS POINT GIVEN THE MODEL CONSENSUS...SO ACTUALLY TRENDED THE GIVEN ALLBLEND SOLUTION LOWER TO ONLY INCLUDE SLIGHT CHANCES AT THIS POINT ACROSS MUCH OF THE REGION.
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&& .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 131 PM EDT FRI JUL 25 2014 LOW CLOUDS CONTINUE TO LIFT AND MIX OUT AND ALL SITES SHOULD RETURN TO VFR CONDITIONS BY 18Z...OR VERY SHORTLY THEREAFTER. SCATTERED TO BROKEN MID AND HIGH CLOUDS...DEBRIS FROM A THUNDERSTORM COMPLEX WELL TO OUR WEST...WILL DRIFT OVERHEAD TONIGHT. THESE CLOUDS ALONG WITH SOME DRYING OF THE LOW LEVEL AIRMASS ARE EXPECTED TO KEEP A REPEAT OF THE WIDESPREAD FOG AND LOW CIELINGS FROM DEVELOPING AGAIN TONIGHT. WILL HOWEVER HIGHLIGHT A BRIEF PERIOD OF MVFR CONDITIONS AT LOZ AND SME AROUND DAWN ON SATURDAY AS SOME PATCHY VALLEY FOG IS STILL LIKELY TO FORM. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ABE LONG TERM...JMW AVIATION...ABE

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