837 FXUS63 KJKL 221920 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 320 PM EDT SAT JUN 22 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 320 PM EDT SAT JUN 22 2013 CONVECTION ACROSS THE CWA HAS BEEN LIMITED SO FAR THIS AFTERNOON. APPEARS MID LEVEL CAPPING IS JUST A BIT TOO STRONG TO OVERCOME AND IS RESPONSIBLE FOR DAMPENING ACTIVITY THUS FAR. AS A RESULT PULLED BACK SLIGHTLY ON POPS FOR THE REMAINDER OF THE AFTERNOON. ALOFT A WEAK UPPER LOW WILL MOVE SLOWLY NORTHWARD ACROSS THE REGION DURING THE NEXT 24 HOURS. CAPPING SHOULD WEAKEN A BIT ON SUNDAY AS THE UPPER LOW MOVES OVERHEAD. SO CONTINUED TO ADVERTISE SLIGHTLY BETTER COVERAGE OR SCATTERED ACTIVITY SUNDAY AFTERNOON FOR AT LEAST A GOOD PORTION OF THE CWA. NO SIGNIFICANT CHANGES TO TEMPS. DID NUDGE THEM TOWARDS A BLEND OF LATEST MODEL GUIDANCE. WITH A PERSISTENT PATTERN IN PLACE THERE SHOULD NOT BE TOO MUCH VARIATION IN DAY TO DAY SENSIBLE WEATHER...A TYPICAL SUMMER LIKE PATTERN. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 320 PM EDT SAT JUN 22 2013 DURING THE FIRST HALF OF THE TIME FRAME THE MAIN WESTERLIES SHOULD BE TO OUR NORTH...WITH AN UPPER LEVEL RIDGE AXIS ORIENTED WEST/EAST OVER THE SOUTHERN CONUS. WITHOUT A CRUSHING RIDGE OVER US AND WITH A WARM AND MOIST AIR MASS STILL IN PLACE...WILL EXPECT SHOWERS AND THUNDERSTORMS TO POP UP AT TIMES. IT SHOULD BE LARGELY A DIURNAL TREND LINKED WITH PEAK HEATING. HOWEVER...DUE TO LACK OF FEATURES TO FOCUS CONVECTION...POPS WILL BE LOW...GENERALLY 20-30 PERCENT EACH AFTERNOON...AND DROPPING OFF AT NIGHT. LATE IN THE WEEK...THE UPPER RIDGE IS EXPECTED TO BUILD MUCH STRONGER OVER THE SOUTHWEST CONUS...ALLOWING TROUGHING TO DEVELOP IN THE EAST. SHORTWAVE TROUGHS DROPPING INTO THE SYNOPTIC SCALE TROUGH WILL THEN PROVIDE A FOCUS FOR CONVECTION. ONE SUCH SHORTWAVE TROUGH...ALBEIT FAIRLY WEAK...IS SHOWN BY BOTH THE ECMWF AND GFS MODELS ARRIVING ON THURSDAY. WILL USE LOW CHANCE POPS AREA WIDE WITH THIS. MODELS THEN SHOW THE LARGE SCALE UPPER TROUGH CONTINUING TO DEEPEN...AND BRINGING A SURFACE COLD FRONT INTO THE AREA FROM THE NORTHWEST ON FRIDAY. WILL RAISE POPS TO 50 PERCENT WITH THIS FEATURE. IF THE CURRENT FORECAST SCENARIO HOLDS IN FUTURE RUNS... POPS WILL LIKELY GO HIGHER. BOTH THE ECMWF AND GFS GENERATE PRECIP BEHIND THE COLD FRONT UNDER THE UPPER TROUGH ON SATURDAY. THE GFS DOES SHOW A SURFACE TROUGH MOVING THROUGH...AND GFS MEX MOS HAS 50 PERCENT POPS ON SATURDAY. HOWEVER...FORECAST SOUNDINGS DO NOT LOOK ALL THAT SUPPORTIVE OF PRECIP...AND THE ECMWF IS LIGHTER WITH ITS QPF FIELD THAN THE GFS. WILL UNDERCUT THE MOS AND GO WITH 30 PERCENT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 140 PM EDT SAT JUN 22 2013 OTHER THAN SOME LIGHT FOG FOR A COUPLE HOURS NEAR DAWN SUNDAY...LOOKING FOR VFR CONDITIONS THROUGH THE BULK OF THE FORECAST. WILL ALL THINGS BEING PRETTY MUCH EQUAL DECIDED TO LEAN HEAVILY ON PERSISTENCE FOR TIMING OF LIGHT FOG AT EACH TERMINAL. OTHERWISE...LOOKING FOR DIURNAL ISOLD TO SCATTERED SHOWERS AND THUNDERSTORMS TO BEGIN FIRING ACROSS THE AREA THIS AFTERNOON. EXPECT TO REACH OUR CONVECTIVE TEMP OF ABOUT 85...SOMETIME BETWEEN 19Z AND 20Z. THEREFORE ATTEMPTED TO MATCH UP MENTION OF THUNDERSTORMS WITHIN THE TAFS FOR THAT SAME TIME FRAME. OTHERWISE...WINDS WILL BE LIGHT THROUGH THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...RAY LONG TERM...HAL AVIATION...RAY