Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 271119 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 719 AM EDT MON JUL 27 2015 .UPDATE...
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ISSUED AT 634 AM EDT MON JUL 27 2015 ISOLATED SHOWERS HAVE BEGUN POPPING UP OVER THE LAST COUPLE OF HOURS ACROSS PORTIONS OF CENTRAL AND EASTERN KY. THIS WAS A FEW HOURS SOONER THAN FORECASTED...SO MAIN CHANGE DURING THIS UPDATE WAS TO MAKE SURE THE POPS AND WEATHER BETTER REFLECTED THE ONGOING CONDITIONS. KEPT ISOLATED POPS IN THROUGH THE MORNING...THOUGH IF THE LARGER AREA OF SHOWERS CURRENTLY MOVING OVER CENTRAL KY IS ABLE TO HOLD TOGETHER AS IT REACHES OUR WESTERN CWA...POPS MAY NEED TO BE UPGRADED ONCE MORE. AS THE SUN RISES...BETTER INSTABILITY WILL LIKELY RESULT IN MORE LIGHTNING STRIKES AND RUMBLES OF THUNDER WITH ANY OF THESE CELLS. PARAMETERS ARE STILL NOT LOOKING VERY FAVORABLE FOR SEVERE DEVELOPMENT TODAY...THOUGH THE SLOW WEST TO EAST NATURE OF THE STORMS ALONG THE NEARLY STATIONARY BOUNDARY MAY LEAD TO SOME TRAINING OR LOCATIONS EXPERIENCING HEAVY RAINS FOR AN EXTENDED PERIOD OF TIME. THIS WILL NEED TO BE MONITORED AS WE GO THROUGHOUT THE DAY. FINALLY...LOADED IN THE LATEST OBSERVATIONAL DATA FOR TEMPS...DEW POINTS...AND WINDS...TO MAKE SURE THAT THESE NEAR TERM GRIDS WERE REFLECTING THE CURRENT CONDITIONS.
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&& .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 AIR MASS. 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 MIMIC THOSE OF EARLY THIS MORNING...STAYING NEAR THE 70 DEGREE MARK WITH HIGH HUMIDITIES. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 502 AM EDT MON JUL 27 2015 A STRONG UPPER LEVEL HIGH WILL BE OVER THE SOUTHERN PLAINS AT THE START OF THE PERIOD...WITH RIDGING EXTENDING NORTHEAST OVER THE GREAT LAKES. THIS WILL RESULT IN LIGHT FLOW ALOFT WITH VERY LITTLE IN THE WAY OF FEATURES. ENOUGH HEATING AND SURFACE MOISTURE MAY BE PRESENT TO FUEL SOME THUNDERSTORMS TUESDAY EVENING AND AGAIN WEDNESDAY AFTERNOON...MAINLY OVER THE HIGHER TERRAIN. HOWEVER...MOSTLY DRY WEATHER IS EXPECTED. AN UPPER LOW RIDING ACROSS THE TOP OF THE RIDGE OVER CANADA WILL FLATTEN THE RIDGE AND SEND IT RETROGRADING TO THE WEST LATE IN THE WEEK...WITH A BROAD TROUGH RESULTING OVER THE EASTERN CONUS. THIS WILL SEND A COLD FRONT SOUTHEAST THROUGH THE JKL FORECAST AREA WEDNESDAY NIGHT AND THURSDAY. MODELS GENERATE SOME PRECIP WITH THE FRONT...BUT ARE LOOKING LESS IMPRESSIVE IN RECENT RUNS. HAVE USED 20-30 PERCENT POPS. SURFACE HIGH PRESSURE BUILDING IN BEHIND THE COLD FRONT WILL BRING A DRIER AIR MASS FOR THURSDAY NIGHT INTO THE WEEKEND...RESULTING IN MOSTLY CLEAR SKIES WITH COOL NIGHTS AND WARM DAYS. && .AVIATION...
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(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 718 AM EDT MON JUL 27 2015 A WEAK FRONTAL BOUNDARY CURRENTLY DRAPED ACROSS KY WILL BE THE EPICENTER FOR POTENTIAL SHOWER AND THUNDERSTORM DEVELOPMENT FOR THE DURATION OF THE TAF PERIOD. GIVEN THE WEAK NATURE OF THE BOUNDARY...THE STORMS SHOULD NOT POSE MUCH OF A SEVERE THREAT...BUT HEAVY DOWNPOURS AND SOME GUSTY WINDS COULD POSE LOCAL THREATS AND BRIEF REDUCED VIS AT TAF SITES. OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS...EXPECT VFR CONDITIONS...WITH CIGS GENERALLY ABOVE 3500 TO 5000 FT. OVERNIGHT...EXPECT BEST CONVECTION TO DIMINISH WITH LOSS OF DAYTIME HEATING. TRENDED TAF SITES TOWARD FOG DEVELOPMENT OVERNIGHT...BUT ULTIMATELY THE IMPACTS FOR VIS WILL BE DEPENDENT ON IF...WHEN...AND HOW MUCH A SINGLE TAF SITE RECEIVES RAIN. WINDS WILL REMAIN LIGHT AND GENERALLY VARIABLE THROUGH THE TAF PERIOD.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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