Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 270716 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 316 AM EDT MON JUL 27 2015 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 316 AM EDT MON JUL 27 2015 A WEAK SURFACE BOUNDARY HAS SHIFTED SOUTH ACROSS THE OHIO RIVER AND CURRENTLY SITS JUST NORTH OF OUR CWA. SHOWERS AND THUNDERSTORMS ARE STILL SHOWING UP ALONG AND NEAR THIS BOUNDARY EARLY THIS MORNING...BUT ARE CONTINUING TO SHOW A DIMINISHING TREND. AS SUCH...NOT EXPECTING THIS CONVECTION TO MAKE IT INTO THE CWA BEFORE 12Z. WPC SHOWS THE FRONT REMAINING NEARLY STATIONARY THROUGH THE MORNING HOURS...BEFORE FINALLY SHIFTING SLOWLY SOUTHWARD THROUGH CENTRAL KY LATE IN THE AFTERNOON. WITH THE INTRODUCTION OF DAYTIME HEATING AFTER 12Z THIS MORNING...EXPECT THIS BOUNDARY...THOUGH WEAK...TO PROVIDE ENOUGH LIFT AND INSTABILITY TO SPARK A NEW SET OF SHOWERS AND THUNDERSTORMS. MODELS CONTINUE TO PEG THE FAR SE AS THE EPICENTER FOR MOST OF THESE SHOWERS AND THUNDERSTORMS...PERHAPS DUE TO THE EASTERLY AND SLIGHT UPSLOPE FLOW. HOWEVER...GIVEN THE WEAK NATURE OF THE BOUNDARY...IN ADDITION TO THE VERY LIGHT WINDS...DO NOT EXPECT THUNDERSTORMS TO BE STRONG IN NATURE OR VERY SUSTAINABLE/LONG LIVED ACROSS ANY PART OF THE CWA. THE BOUNDARY WILL LIKELY REMAIN PARKED ACROSS KY TONIGHT AND POSSIBLY EVEN INTO THE DAY TUESDAY BEFORE IT FINALLY FADES OUT. THIS COULD KEEP ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE CWA THROUGH THIS ENTIRE TIME PERIOD...THOUGH LOSS OF DAYTIME HEATING WILL LIKELY CUT DOWN ON THUNDER CHANCES OVERNIGHT TONIGHT...ALONG WITH SOME OF THE CU DEVELOPMENT. DIURNALLY DRIVEN CU WILL BEEF BACK UP THE CLOUD COVER SOMEWHAT DURING THE DAY TUESDAY AS BETTER CONVECTION ENSUES. HOWEVER...AS THE BOUNDARY CONTINUES TO FADE...SO TO WILL THE BEST LIFT...MOISTURE...CLOUDS...AND PRECIP CHANCES DURING THE AFTERNOON TUESDAY. EXPECT MOST OF THE PRECIP TO HAVE DIMINISHED BY TUESDAY EVENING. AS FAR AS TEMPERATURES...THIS FRONTAL BOUNDARY...AS ADVERTISED... WILL BE WEAK ENOUGH TO CAUSE LITTLE EFFECT ON THE WARM AIRMASS. LIGHT WINDS AT THE SURFACE WILL GIVE WAY TO A STRONGER NW FLOW ALOFT. HOWEVER...WITH A BUILDING UPPER LEVEL RIDGE OVER THE CENTRAL CONUS...WARM AIR ALOFT WILL BE PULLED FROM THE SOUTH CENTRAL CONUS/GULF COAST...NORTHWARD INTO THE CENTRAL PLAINS...AND THEN EASTWARD TOWARDS THE OHIO VALLEY. IN ESSENCE...NW FLOW WILL ACTUALLY RESULT IN THE CONTINUED PULL OF WARMER AIR INTO THE REGION. AS SUCH...HIGH TEMPS BOTH TODAY AND TOMORROW WILL CONTINUE TO HOVER IN THE UPPER 80S TO AROUND 90. TEMPERATURES OVERNIGHT WILL MIMICS THOSE OF EARLY THIS MORNING...STAYING NEAR THE 70 DEGREE MARK WITH HIGH HUMIDITIES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 304 PM EDT SUN JUL 26 2015 THE EXTENDED PERIOD BEGINS WITH MID AND UPPER LEVEL RIDGING OVER THE EASTERN CONUS. THIS SEEMS TO REFLECT TO THE SURFACE WITH HIGH PRESSURE CENTERED OVER THE GREAT LAKES AND ANOTHER HIGH CENTERED OVER THE SOUTH. A LINGERING BOUNDARY REMAINS OVER THE EASTERN SIDE OF THE APPALACHIANS AND SOME NORTHEAST FLOW INTO THE AREA WILL LIKELY LEAD TO SOME SHOWER AND THUNDERSTORM DEVELOPMENT BUT THIS SHOULD REMAIN ON THE LEE SIDE AS MODEL SOUNDINGS OVER EASTERN KENTUCKY SHOW QUITE A CAP IN PLACE THAT SHOULD HINDER ANY STORM DEVELOPMENT...BUT PERHAPS A SPRINKLE OR A LIGHT SHOWER IS POSSIBLE WITH SOME DEVELOPMENT OF INSTABILITY DURING THE AFTERNOON BUT CONFIDENT THAT THE CAP WILL BE SUCH THAT GROWTH WILL BE LIMITED TO SPRINKLES AND A FEW SHOWERS. IF BY CHANCE A SHOWER DOES POP THE CAP...THIS WILL OCCUR IN THE FAR SOUTHEAST PORTION OF EASTERN KY. HEADING INTO WEDNESDAY...THE UPPER LEVEL RIDGE DOES FLATTEN AS A COLD FRONT BEGINS TO PUSH INTO THE OH VALLEY BY THE AFTERNOON ERODING THE MENTIONED CAP A BIT AND ALLOWING FOR THE POSSIBILITY OF SHOWER AND THUNDERSTORM DEVELOPMENT. MODEL SOUNDINGS WOULD SUGGEST SOME A REMAINING CAP AND SIGNIFICANT CONVECTION HOLDING OFF TILL THE AFTERNOON AND EVENING INTO WEDNESDAY NIGHT. RETREATING HIGH PRESSURE WILL KEEP A SLOWED FRONT FROM EXITING AND ALLOWING FOR CONTINUED SHOWER AND THUNDERSTORM DEVELOPMENT INTO THURSDAY AND THE SUPER BLEND DOES SUPPORT THIS NOTION. A POSSIBLE LAPSE IN CONSISTENCY MAY TAKE SHAPE BY FRIDAY AND INTO THE WEEKEND BUT AT THIS POINT THE LONGWAVE TROUGH SETS UP OVER THE EASTERN CONUS WITH THE MAIN TRACK OF THE SHORTWAVES TRACKING OVER THE GREAT LAKES. TO THE SOUTHEAST...RETURN FLOW ALLOWING LOW LEVEL MOISTURE TO INTRUDE OVER THE SOUTHEAST CONUS THROUGH THE END OF THE PERIOD. THIS SHOULD KEEP PRECIP ON THE LEE SIDE OF THE APPALACHIANS. EASTERN KENTUCKY DURING THIS TIME THROUGH THE END OF THE PERIOD SHOULD REMAIN UNDER SURFACE HIGH PRESSURE SANDWICHED IN BETWEEN ANOTHER APPROACHING WAVE FROM THE NORTHWEST AND SOUTHWEST FLOW OVER THE SOUTHEAST CONUS. MOST CURRENT OPERATION MODELS AGREE WITH THIS AS DOES THE SUPER BLEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 137 AM EDT MON JUL 27 2015 MAINLY VFR CONDITIONS WILL BE SEEN OVER THE NEXT 24 TO 36 HOURS. ANOTHER ROUND OF VALLEY FOG MAY DEVELOP LATE TONIGHT...WITH A POSSIBILITY OF A FEW OF THE TAF SITES BRIEFLY GOING DOWN TO MVFR VISIBILITIES. HOWEVER...THE IMPACT OF THE CLOUD COVER REMAINS UNCERTAIN TONIGHT SO HAVE JUST ADDED A BIT OF FOG TO THE LOWER ELEVATION SITES THAT TEND TO BE MORE PRONE TO SEEING ITS DEVELOPMENT. CANNOT RULE OUT SHOWER OR A THUNDERSTORM AT ANY SITE DURING THE LATE MORNING AND AFTERNOON HOURS OF MONDAY...BUT PLACEMENT AND TIMING IS TOO UNCERTAIN TO INCLUDE IN ANY OF THE TAFS AT THIS TIME. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...SHALLENBERGER AVIATION...GRIEF/JMW

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