Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 292346 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 746 PM EDT FRI MAY 29 2015 .UPDATE... ISSUED AT 635 PM EDT FRI MAY 29 2015 SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE THROUGH EASTERN KENTUCKY THIS EVENING. THE MOST PROMINENT SHOWERS AND STORMS ARE CURRENTLY IMPACTING KNOTT/FLOYD/JOHNSON COUNTIES AND POINTS EAST...WHERE SEVERAL OUTFLOW BOUNDARIES HAVE COLLIDED TOGETHER. OTHERWISE...ISOLATED SHOWERS ARE EXPECTED TO CONTINUE ACROSS THE AREA FOR AT LEAST THE NEXT COUPLE OF HOURS. IN TERMS OF THE FORECAST...GRIDS APPEAR ON TRACK SO ONLY MADE MINOR ADJUSTMENTS TO THE TEMP GRIDS TO REFLECT MOST RECENT OBS. SENT UPDATED GRIDS TO NDFD AND WEB SERVERS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 330 PM EDT FRI MAY 29 2015 18Z SFC ANALYSIS SHOWS HIGH PRESSURE STILL OVER FAR EASTERN KENTUCKY WHILE LOW PRESSURE IS FOUND TO THE WEST OF THE AREA. BETWEEN THESE...A SOUTHERLY FLOW OF AIR IS SUPPORTING WARM TEMPERATURES AND HUMID CONDITIONS. WITH PARTLY SUNNY SKIES THE INSTABILITY WAS SUFFICIENT TO KICK OFF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE AREA BY EARLY AFTERNOON. THIS CONVECTION IS FAVORING THE WESTERN PORTION OF THE CWA WHERE A BIT MORE SUNSHINE WAS SEEN EARLIER IN THE DAY AND DEWPOINTS WERE HIGHER. OTHERWISE...TEMPERATURES MADE IT INTO THE LOW TO MID 80S BEFORE THE PRECIPITATION KNOCKED THEM BACK INTO THE 70S...FOR A TIME...IN MANY LOCATIONS. WINDS HAVE BEEN GENERALLY FROM THE SOUTH AT 5 TO 10 KTS ACROSS THE AREA WHILE DEWPOINTS MADE IT INTO THE MID AND UPPER 60S IN THE WEST...BUT FELL INTO THE UPPER 50S IN THE FAR EAST...CLOSER TO THE HEART OF THE HIGH PRESSURE. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST. THEY ALL SHOW THE WEAK SOUTHEAST RIDGE SHIFTING OFF TO THE EAST IN THE FACE OF AN APPROACHING TROUGH FROM THE SOUTHERN PLAINS. THE ENERGY FROM THIS WILL MOVE INTO KENTUCKY ON SATURDAY AND PASS THROUGH THE STATE BY SUNDAY MORNING...WITH ITS CORE PASSING BY TO THE NORTHWEST. IMPROVING UPPER LEVEL CONDITIONS SHOULD FAVOR CONVECTION ACROSS THE AREA DURING THE AFTERNOON AND EARLY EVENING HOURS WITH THE HIGHER RESOLUTION NAM12 AND HRRR MODELS FAVORED FOR SPECIFICS. SENSIBLE WEATHER WILL FEATURE THE SCATTERED CONVECTION SETTLING DOWN AFTER SUNSET ACROSS THE AREA...THOUGH ISOLATED SHOWERS WILL BE POSSIBLE THROUGH THE NIGHT. THIS WILL SET THE STAGE FOR PATCHY FOG DEVELOPING LATER IN THE NIGHT...BECOMING LOCALLY DENSE IN THE VALLEYS TOWARD DAWN WITH MILD AND MUGGY CONDITIONS IN PLACE. THE APPROACH OF A COLD FRONT...ASSOCIATED WITH THE SFC LOW PASSING THROUGH SOUTHERN INDIANA SATURDAY WILL BRING A THREAT OF STORMS AGAIN FOR THE AREA...MAINLY IN THE MID AND LATE AFTERNOON HOURS AND OVER THE WESTERN PARTS OF THE CWA. THE GFS HAS THE BEST TIMING AND PROGRESSION OF THE FRONT AS IT PASSES THROUGH EAST KENTUCKY. AND WAS USED AS A TEMPLATE THROUGH 12Z SUNDAY. MEANWHILE...THE NAM12 AND ECMWF SPLIT THE FRONT MOVING IT THROUGH EAST KENTUCKY LATER SATURDAY NIGHT AND INTO SUNDAY MORNING...TAKING THE MAIN LOW INTO OHIO AND BYPASSING THIS PART OF THE STATE TO THE NORTH. THIS TRANSITION MAY LIMIT THE QPF OVER THE CWA COMPARED TO THE WEST AND NORTH...ALSO SEEN IN THE GFS...LOWERING CONFIDENCE IN A NEEDED SOAKING RAIN FOR MUCH OF THE AREA. ACCORDINGLY...HAVE KEPT POPS IN THE MID TO HIGH CHANCE RANGE THROUGH 12Z SUNDAY. AGAIN USED THE SHORTBLEND AS A STARTING POINT FOR THE T/TD/WIND GRIDS INTO SATURDAY BEFORE SWITCHING TO THE SUPERBLEND THROUGH 12Z SUNDAY. MADE SOME MINOR RIDGE TO VALLEY TEMPERATURE ADJUSTMENTS FOR LOWS AND HOURLY TEMPS EACH NIGHT. AS FOR POPS... ENDED UP A BIT HIGHER THAN A BLEND OF THE DRIER MET AND WETTER MAV GUIDANCE THROUGH THE SHORT TERM WITH AN EXAGGERATED DIURNAL CYCLE FOR THE HOURLY POPS/WX GRIDS THROUGH SATURDAY EVENING AND MORE OF A SYNOPTIC DRIVEN POP GRID FOR SATURDAY NIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 235 PM EDT FRI MAY 29 2015 BASED ON MODEL TRENDS OVER THE PAST 24 HOURS...WENT AHEAD AND MADE SOME FAIRLY SUBSTANTIAL CHANGES TO THE FORECAST FOR NEXT WEEK WHICH WILL INVOLVE MUCH LESS RAIN CHANCES. AT THE START OF THE PERIOD...ON SUNDAY...A VORT MAX WILL BE LIFTING NORTHWARD ACROSS WESTERN KENTUCKY INTO INDIANA AND OHIO. THIS SYSTEM WILL HAVE SOME GOOD DYNAMICS ASSOCIATED WITH IT TO PRODUCE GOOD COVERAGE OF SHOWERS AND PERHAPS SOME STORMS OVER THESE AREAS. HOWEVER...THIS FORCING JUST GRAZES THE BLUEGRASS REGION OF EASTERN KENTUCKY...WITH MOST OF THE FORCING STAYING TO OUR NORTH. HOWEVER...THIS WAVE WILL SEND A FRONTAL BOUNDARY SOUTH ACROSS THE AREA AND WITH THE POSSIBILITY OF SOME INSTABILITY DEVELOPING ON SUNDAY...WE COULD SEE SHOWERS AND STORMS INCREASE IN COVERAGE AS THE BOUNDARY PUSHES EAST THROUGH THE DAY. STILL PLENTY OF OPPORTUNITY FOR THE INSTABILITY TO NOT MATERIALIZE AND WE END UP DRIER THAN EXPECTED. SAFE TO SAY...CONFIDENCE IS NOT HIGH ON RAIN CHANCES ON SUNDAY. IN FACT...THE GFS GUIDANCE HAS BECOME MUCH MORE PESSIMISTIC ON RAIN CHANCES ON SUNDAY. ECMWF REMAIN A BIT SLOWER WITH THIS WAVE AND FRONT...WHICH WOULD PROVIDE BETTER SUPPORT FOR RAIN ON SUNDAY IF THE FRONT CAN STALL OVER OUR REGION. BY SUNDAY NIGHT INTO MONDAY...IT LOOKS LIKE BOUNDARY WILL SHIFT SOUTH AND EAST...WITH PERHAPS SOME SLIGHT CHANCES FOR SHOWERS LINGERING INTO MONDAY ACROSS SOUTHEAST KENTUCKY. HOWEVER...MODELS ARE COMING INTO BETTER AGREEMENT ON DRY WEATHER FROM LATE MONDAY THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE BUILDS EAST ACROSS THE OHIO RIVER VALLEY. THIS WARRANTS REMOVING RAIN CHANCES FROM MONDAY NIGHT ONWARD. AS THE HIGH SETTLES EAST BY THURSDAY...SOME RETURN FLOW MAY DEVELOP WITH SOME MOISTURE RETURNING...WHICH COULD BRING BACK THE POSSIBILITY OF AN AFTERNOON SHOWER OR THUNDERSTORM. REGARDLESS...RAIN CHANCES WILL REMAIN LOW THROUGH THE END OF NEXT WEEK. A BRIEF COOL DOWN...WITH LOWER HUMIDITIES WILL BE SEEN EARLY IN THE COMING WEEK BEHIND THE FRONTAL BOUNDARY...BUT TEMPERATURES WILL RETURN TO ABOVE NORMAL BY MIDDLE TO END OF NEXT WEEK ALONG WITH HIGHER HUMIDITY. && .AVIATION...
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(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 745 PM EDT FRI MAY 29 2015 SCATTERED CONVECTION IS EXPECTED TO CONTINUE FOR THE HOUR OR SO THEN WANE AFTER SUNSET. THIS WARRANTS KEEPING VCTS AT MOST OF THE TAF SITES THROUGH ABOUT 02Z. ONCE THE CONVECTION DISSIPATES SOME PATCHY FOG WILL LIKELY DEVELOP AGAIN IN THE VALLEYS AFTER 06Z AFFECTING MOST OF THE TAF SITES WITH SOME MVFR VIS. IFR VIS MAY ALSO BE POSSIBLE TONIGHT IN LOCATIONS WHERE IT RAINED...PARTICULARLY THE SJS...SME AND LOZ TAF SITES. ISOLATED TO SCATTERED CONVECTION WILL BE POSSIBLE BY EARLY AFTERNOON ON SATURDAY WITH VCTS AGAIN INCLUDED. WINDS WILL GENERALLY BE LIGHT AND VARIABLE FROM THE SOUTH THROUGH SATURDAY MORNING...PICKING UP AGAIN LATER IN THE DAY.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JVM SHORT TERM...GREIF LONG TERM...KAS AVIATION...JVM/GREIF

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