Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 241507 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1107 AM EDT THU JUL 24 2014 .UPDATE...
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ISSUED AT 1107 AM EDT THU JUL 24 2014 WEAK LOW PRESSURE IS TRACKING SLOWLY ACROSS SOUTHEAST KENTUCKY WITH NORTHERLY WINDS STARTING TO PULL DRIER AIR INTO OUR NORTHERN COUNTIES. SCATTERED SHOWERS CONTINUE TO PLAGUE AREAS SOUTH OF I-64 ALONG WITH AN OCCASIONAL ISOLATED THUNDERSTORM. THESE WILL GRADUALLY PULL EAST AS THE LOW PRESSURE DEPARTS TO THE EAST DURING THE AFTERNOON WITH DECREASING RAIN CHANCES EXPECTED FROM WEST TO EAST THROUGH THE AFTERNOON. CLOUD COVER WILL LIKELY HANG IN TOUGH THROUGH MOST OF THE DAY WITH CU DEVELOPING QUICKLY WHERE ANY BREAKS DEVELOP DURING THE AFTERNOON. UPDATE ISSUED AT 540 AM EDT THU JUL 24 2014 UPDATED THE FORECAST TO ADD AREAS OF DENSE FOG INTO THE GRIDS FOR THIS MORNING GIVEN THE OBSERVATIONS AND WEB CAMS. THE LIGHT WINDS AND MOIST BOUNDARY LAYER IS RESULTING IN NUMEROUS PLACES WITH VISIBILITY BELOW A QUARTER OF A MILE. THE FOG SHOULD START TO BREAK UP BY 8 AM. ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST OBS AND TRENDS. THE GRIDS...AN SPS...UPDATED ZONES...AND HWO HAVE BEEN ISSUED.
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&& .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 325 AM EDT THU JUL 24 2014 06Z SFC ANALYSIS SHOWS A WEAK AREA OF LOW PRESSURE OVER EAST KENTUCKY ALONG A COLD FRONT THAT IS GRADUALLY SETTLING THROUGH THE CWA. THIS BOUNDARY AND LOW IS RESPONSIBLE FOR THE SHOWERS AND STORMS WE SAW EARLIER IN THE EVENING AND THE ONES THAT STILL LINGER OVER NORTH CENTRAL KENTUCKY. NORTHWEST OF THIS FRONT...A COOL AND DRY AREA OF HIGH PRESSURE IS IN PLACE OVER THE MIDWEST ON FINAL APPROACH TO EAST KENTUCKY...SCHEDULED TO ARRIVE BY THURSDAY EVENING. MEANWHILE... SCATTERED SHOWERS AND STORMS WILL REMAIN A THREAT THROUGH THE REST OF THE MORNING AND INTO THE START OF THURSDAY. PATCHY FOG AND PLENTY OF LOW CLOUDS ARE FOUND THROUGH EAST KENTUCKY AT THE MOMENT...AS WELL. THIS ALL IS EXPECTED TO LINGER THROUGH SUNRISE AS TEMPERATURES AND DEWPOINTS STAY ABOUT WHERE THEY ARE CURRENTLY...IN THE UPPER 60S AND LOWER 70S. SIMILARLY...THE WINDS WILL REMAIN LIGHT AND VARIABLE WELL INTO THE DAY THURSDAY. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS THEY ALL SHIFT THE EASTERN TROUGH SLIGHTLY NORTHEAST IN RESPONSE TO A FLATTENING OF THE STRONG WESTERN RIDGE. LEADING OFF THIS TRANSITION ARE A COUPLE OF SHORTWAVES THAT WILL CROSS THE SOUTHERN OHIO VALLEY AND KENTUCKY INTO THE AFTERNOON THURSDAY. RISING HEIGHTS WILL FOLLOW LATER TONIGHT AND THROUGH THE DAY FRIDAY HELPING TO KEEP ANY ENERGY PACKETS IN THE NORTHWEST FLOW FROM AMOUNTING TO MUCH OVER OUR AREA. WITH THE MODEL AGREEMENT HAVE FAVORED THE HRRR AND NAM12 SOLUTIONS FOR THE FORECAST TODAY AND THEN A GENERAL MODEL BLEND INTO FRIDAY. OF NOTE...BOTH THE NAM12 AND THE ECMWF DO MAKE MORE OUT OF A BAND OF PCPN THAT THEY FORECAST TO ACCOMPANY THE COLD FRONT AS IT EXITS LATER TODAY...IN COMPARISON TO THAN THE GFS AND GEM. SENSIBLE WEATHER WILL FEATURE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS SLOWLY EXITING EAST KENTUCKY AS A SFC WAVE AND COLD FRONT DEPARTS TO THE SOUTHEAST BY LATE AFTERNOON. COOLER AIR WITH THIS BOUNDARY...LOW CLOUDS...AND THE PCPN WILL KEEP TEMPERATURES ONLY IN THE 70S TODAY. HIGH PRESSURE THEN SETTLES INTO THE AREA TONIGHT WITH DRIER AIR AND EVEN COOLER TEMPERATURES. THE MAIN QUESTION FOR TONIGHT WILL BE HOW MUCH CLOUD COVER WILL REMAIN OVER EAST KENTUCKY IN THE WAKE OF THE FRONT. THE TIME SECTIONS FROM THE NAM12 SUGGEST THAT LOW CLOUDS WILL BE TOUGH TO CLEAR THROUGH DAWN SO HAVE GONE CLOUDIER WITH THE GRIDS...WITH LIMITED RADIATIONAL COOLING AND FOG ANTICIPATED FOR THIS REASON. THESE CLOUDS SHOULD START TO BREAK UP MORE EFFECTIVELY ON FRIDAY ALLOWING FOR A WARMUP BACK INTO THE LOW 80S...ALONG WITH PLEASANT HUMIDITY LEVELS. HAVE USED THE CONSSHORT AS A STARTING POINT FOR TEMPERATURES... DEWPOINTS...AND WINDS THROUGH THE FIRST 24 HOURS AND THEN THE CONSALL THEREAFTER. AS FOR POPS...HAVE ENDED UP ON THE HIGH SIDE OF THE MOS NUMBERS...CLOSER TO THE MET...TODAY WITH LOW POPS TONIGHT AND FRIDAY...IN LINE WITH THE GUIDANCE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 350 AM EDT THU JUL 24 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A CONTINUED AND PRONOUNCED RIDGE OVER THE WEST AND DEEPENING TROUGH OVER THE EASTERN CONUS. BOTH THE GFS AND EURO HINT AT A POSSIBLE WEAKENING MCS TRAVERSING OVER THE RIDGE AND THROUGH THE UPPER MS RIVER VALLEY AND INTO THE OH VALLEY ON FRIDAY NIGHT. FOLLOWING THIS WILL BE A STRONG SHORT WAVE MOVING SOUTHEAST FROM MN AND INTO THE OH VALLEY BY SUNDAY AND SUNDAY NIGHT. AS THIS WAVE SWINGS THROUGH THE BASE OF THE TROUGH...A 90 KNOT JET MAX WILL PUSH THROUGH DEEPENING THE LONG WAVE TROUGH OVER THE EASTERN CONUS AND KEEPING THE QUITE AMPLIFIED TROUGH IN PLACE THROUGH THE REST OF THE EXTENDED. IN RESPONSE...THE WESTERN RIDGE INCREASES IN STRENGTH KEEPING A RARE MERIDIONAL PATTERN IN PLACE FOR THIS TIME OF YEAR. WITH THE MODELS SHOWING SOME AGREEMENT IN THIS TREND IT CAN BE SAFE TO SHOW A HIGH LEVEL OF CONFIDENCE WITH THE ALL MODEL BLEND SOLUTION. FOR SOME MORE DETAILS IN THE LOWER LEVELS...THE MODELS SEEM TO BE IN AGREEMENT WITH THE DECAYING MCS MAKING IT INTO THE AREA FRIDAY NIGHT. THIS SHOULD ERODE THE ADVERTISED CAP THROUGH FRIDAY NIGHT AND ALLOW SOME ADDITIONAL DEVELOPMENT INTO THE DAY ON SATURDAY WITH DECENT INSTABILITY AVAILABLE AND SOME UPPER LEVEL SUPPORT ARRIVING AHEAD OF A POTENT SHORTWAVE. THE BEST CHANCE FOR SHOWER AND THUNDERSTORM DEVELOPMENT WILL COME ON SUNDAY AND INTO MONDAY WITH A STRONG COLD FRONT MOVING THROUGH. WENT WITH THE LIKELY POPS INHERITED FROM THE ALL MODEL BLEND. AT AN EARLY LOOK TO THIS SCENARIO...QUITE A BIT OF DYNAMICS ARE WITH THIS FEATURE WITH THE STRONG JET STREAK MOVING THROUGH THE OH VALLEY AND AFTERNOON CAPE VALUES REACHING 2500 J/KG...A SEVERE WEATHER THREAT IS CERTAINLY NOT OUT OF THE QUESTION IF THE STRENGTH OF THE WAVE HOLDS TRUE THROUGH THE DAYS LEADING UP TO THE EVENT. THIS WILL BE THE REAL FORECAST CHALLENGE AS THE POTENTIAL IS THERE...BUT WILL HAVE TO SEE HOW THE MODELS TREND UP TO THE EVENT. A COUPLE WEAK DISTURBANCES WILL FOLLOW BEHIND THIS WAVE AND WILL PROVIDE A LOW CHANCE FOR PRECIP INTO TUESDAY BEFORE HIGH PRESSURE SETTLES IN FOR THE REST OF THE EXTENDED. THE AIR MASS MOVING IN BEHIND THIS FRONT IS QUITE COOL WITH HIGH TEMPERATURES FOR MONDAY THROUGH WEDNESDAY IN THE MID 70S...AROUND 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. MODEL TRENDS WOULD SUGGEST THAT AN OVERALL COOLER PATTERN FOR THE LAST WEEK OF JULY WILL BE THE CASE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 655 AM EDT THU JUL 24 2014 SCATTERED SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL CONTINUE TO SLOWLY DRIFT SOUTHEAST THROUGH THE MORNING. AREAS OF DENSE FOG ARE AFFECTING MANY OF THE AIRPORTS THIS MORNING IN LIEU OF THE CONVECTION. EXPECT VIS AND CIG CONDITIONS TO GRADUALLY IMPROVE FOLLOWING SUNRISE. HAVE KEPT THUNDER AND EVEN VCTS OUT OF THE TAFS AS THE INSTABILITY WILL BE FAIRLY LOW THROUGH THE DAY...THOUGH A STRAY STORM CANNOT BE RULED OUT. THE LATEST HRRR AND NAM12 CONTINUE TO INDICATE THAT THE CURRENT BAND OF CONVECTION ALONG THE FRONT WILL HOLD TOGETHER AS IT MAKES ITS FINAL PUSH ACROSS THE AREA. HAVE A VCSH FOR THIS IN ALL SITES WITH CIGS GENERALLY AROUND 2K FEET. IN THE WAKE OF THE FRONT LATER THIS EVENING...DRIER AIR IS EXPECTED TO LIFT THE CIGS AND REMOVE THE THREAT OF SHOWERS. WINDS THROUGH THE PERIOD WILL BE MAINLY LIGHT AND VARIABLE...THOUGH FAVORING THE NORTHERLY DIRECTION LATER TODAY AND INTO THE EVENING. PATCHY FOG WILL BE A CONCERN LATER TONIGHT AS WELL...BUT GENERALLY ONLY IF WE MANAGE TO CLEAR OUT. FOR NOW WILL LEAVE THIS OUT OF THE TAFS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ABE SHORT TERM...GREIF LONG TERM...SHALLENBERGER AVIATION...GREIF

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