Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 300643 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 243 AM EDT THU JUL 30 2015 .UPDATE... ISSUED AT 243 AM EDT THU JUL 30 2015 COLD FRONT WAS POSITIONED FROM NEAR KBNA TO NEAR KDAY. CONVECTION HAS ALMOST DIED OUT OVER THE LOCAL AREA...BUT CAN NOT RULE OUT SOMETHING POPPING UP YET AHEAD OF THE FRONT. HAVE LOWERED POPS TO 20 PERCENT...AND THEN DROPPING BELOW THE THRESHOLD FOR THE MENTION OF PRECIP AFTER THE FRONT PASSES SOUTHEAST IN THE MORNING. UPDATE ISSUED AT 1020 PM EDT WED JUL 29 2015 THE COLD POOL ASSOCIATED WITH THE LINE OF STORMS HAS CONTINUED TO CONSOLIDATE TO THE WEST AND SOUTH OF OUR AREA. ONLY A FEW OF OUR SOUTHWEST COUNTIES WILL SEE LIKELY RAINS OVER THE NEXT HOUR OR SO. THE REMNANT STRATIFORM RAINFALL ACROSS CENTRAL KENTUCKY IS NOT MOVING MUCH...AND WILL GRADUALLY WEAKEN...MAINLY IN PLACE. THE LAST FEW RUNS OF THE HRRR HAS GENERALLY CAUGHT ON TO THE ONGOING CONVECTIVE TRENDS. AS SUCH...IT APPEARS THAT THERE MAY NOT BE MUCH IN THE WAY OF ACTIVITY UNTIL THE ACTUAL FRONTAL BOUNDARY MOVES SOUTHEAST ACROSS THE AREA DEEPER INTO THE OVERNIGHT HOURS...WHEN A SLIGHT UPTICK IN ACTIVITY MAY OCCUR. WILL THEREFORE HANG ONTO SLIGHT TO CHANCE POPS. ALSO ADJUSTED THE LOWS UP A TOUCH...AS THE PUSH BEHIND THE FRONT IS NOT VERY STRONG. THE BEST CHANCE OF SEEING SOME UPPER 60 DEGREE READINGS LOOKS TO BE ALONG AND NORTH OF I-64. UPDATES HAVE BEEN SENT. UPDATE ISSUED AT 813 PM EDT WED JUL 29 2015 THE LATEST RADAR MOSAIC SHOWS A CONVECTIVE LINE ACROSS CENTRAL AND WESTERN KENTUCKY. NEW CELLS HAD BEEN MORE LIVELY A BIT FURTHER NORTHEAST EARLIER...BUT SOME PRECURSORY STORMS TAPPED INTO THE BETTER AVAILABLE AIR MASS...AND NOW THERE IS GENERALLY A WEAKENING TREND ON THE EASTERN FLANK OF THE LINE...WITH BETTER COLD POOL AND ASSOCIATED NEW DEVELOPMENT ALIGNING MORE TOWARDS THE SOUTH...WHERE BETTER INSTABILITY REMAINS. STILL...THINK THAT SOME DEBRIS CELLS WILL MAKE IT INTO THE WEST IN THE NEXT 1 TO 2 HOURS...AND HAVE UPPED THE POPS TO HIGH CHANCE TO LIKELY FOR THOSE LOCATIONS. AS WE LOSE HEATING...EXPECT AN OVERALL GRADUAL DIMINISHMENT...HOWEVER WILL STILL HAVE TO KEEP AN EYE ON HEAVY RAINERS...GIVEN THE HIGH PWATS AND THE POTENTIAL FOR TRAINING. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 343 PM EDT WED JUL 29 2015 AS OF MID AFTERNOON A MID LEVEL RIDGE WAS CENTERED OVER THE SOUTHERN PLAINS REGION...WITH A CLOSED MID LEVEL LOW OVER NORTHWESTERN ONTARIO AND THE ASSOCIATED TROUGH SOUTH INTO THE MS VALLEY REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS CENTERED OVER ONTARIO WITH A COLD FRONT SOUTH INTO THE CENTRAL GREAT LAKES AND THEN SOUTHWEST INTO THE MID MS VALLEY AND CENTRAL PLAINS. CONVECTION HAS DEVELOPED ALONG OR IN ADVANCE OF THIS FRONT OVER OH AND IN SOUTHWEST INTO WESTERN KY. ADDITIONAL CONVECTION HAS DEVELOPED NEAR A MOISTURE GRADIENT EVIDENT IN PW FROM NORTHERN KY SOUTH INTO CENTRAL KY. THIS CONVECTION HAS BEEN GENERALLY SLOW MOVING WITH HEAVY RAINFALL RATES. AREA WIDE...A WARM AND MOIST AIR MASS IS IN PLACE WITH TEMPERATURES IN THE MID TO UPPER 80S TO NEAR 90 AND DEW POINTS IN THE UPPER 60S TO MID 70S. THE CLOSED MID LEVEL LOW WILL TRACK TO HUDSON BAY WITH THE TRAILING SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES AND MID AND UPPER OH VALLEY REGION TONIGHT. THIS SHORTWAVE TROUGH WILL MOVE INTO THE NORTHEASTERN CONUS THROUGH THURSDAY. AT THE SAME TIME...THE MID LEVEL RIDGE WILL RETROGRADE AND AMPLIFY AND BECOME CENTERED OVER THE SOUTHERN ROCKIES OR FOUR CORNERS REGION. THIS WILL PUT THE REGION IN NW FLOW ALOFT LATE IN THE PERIOD. AT THE SFC...THE COLD FRONT WILL CROSS THE REGION BY LATE TONIGHT OR EARLY ON THURSDAY. THEN...HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING COLD FRONT AND USHER IN SLIGHTLY COLDER...BUT MORE NOTICEABLY DRIER AIR INTO THE REGION. RATHER MEAGER MID LEVEL FORCING AND NON OPTIMAL TIMING OF THE FROPA DURING THE LATE EVENING INTO OVERNIGHT HOURS SHOULD LIMIT CONVECTION THIS EVENING AND TONIGHT TO ISOLATED TO SCATTERED COVERAGE. IT STILL APPEARS THAT THERE SHOULD BE A PEAK IN COVERAGE OVER THE NEXT 3 HOURS OR SO...AND THEN MORE ORGANIZED CONVECTION WITH A POSSIBLE BROKEN LINE OR LINE SEGMENTS OF SHOWERS AND THUNDERSTORMS AS THE COLD FRONT MOVES THROUGH. WITH RELATIVELY SLOW STORM MOTIONS EXPECTED DUE TO WEAK FLOW ALOFT AND A MOIST AIR MASS IN PLACE...ANY STRONGER THUNDERSTORMS COULD PRODUCE VERY HEAVY RAINFALL RATES AND OUTFLOW WIND GUSTS IN EXCESS OF 30 MPH WILL BE POSSIBLE THIS EVENING SIMILAR TO A GUST OBSERVED OVER CENTRAL KY EARLIER THIS AFTERNOON. A SHOWER OR POSSIBLY A THUNDERSTORM COULD LINGER EARLY ON THU...OVER THE SOUTHEASTERN CWA...PARTICULARLY NEAR THE VA BORDER. OTHERWISE... AS DRIER AIR MOVES IN THROUGHOUT THE COLUMN SKIES SHOULD BECOME MOSTLY SUNNY IN MOST LOCATIONS ON THU AFTERNOON. WITH THE HIGH BUILDING IN...CLEAR SKIES AND LIGHT WINDS SHOULD SET THE STAGE FOR VALLEY FOG FORMATION LATE IN THE PERIOD. ENOUGH DRIER AIR SHOULD WORK IN FOR SOME OF THE NORMALLY COLDER LOCATIONS ALONG...OR NORTH OF THE MTN PARKWAY COULD TOUCH THE UPPER 50S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 256 PM EDT WED JUL 29 2015 THE EXTENDED PERIOD LOOKS FAIRLY BENIGN AS SURFACE HIGH PRESSURE TAKES CONTROL OF THE REGION THROUGH EARLY NEXT WEEK. THIS WILL ALLOW FOR SLIGHTLY COOLER AND DRIER AIR TO FILTER INTO THE REGION FOR THE WEEKEND. HIGHS FRIDAY THROUGH SUNDAY WILL BE IN THE LOW TO MID 80S...BUT DEW POINTS IN THE UPPER 50S AND LOW 60S WILL MAKE THOSE READINGS FEEL MUCH MORE PLEASANT THAN THEY HAVE RECENTLY. A WEAK AND MOISTURE STARVED FRONT APPROACHES THE REGION SATURDAY MORNING...WITH BOTH THE GFS AND ECMWF SHOWING THE PRECIP FALLING APART BEFORE IT REACHES THE FORECAST AREA. THIS IS LIKELY DUE TO THE DRY AIR/RIDGING AT THE SURFACE. THERE IS SOME MID LEVEL MOISTURE AND WEAK ENERGY WITH THE FRONT AS IT PASSES TO OUR NORTH SO HAVE KEPT A SLIGHT CHANCE OF AN ISOLATED SHOWER IN THE FAR NORTHERN COUNTIES. BUT DO NOT EXPECT MUCH MORE THAN AN INCREASE IN SOME MID LEVEL CLOUDS ON SATURDAY FOR MOST AREAS. SHOWER CHANCES RETURN TO THE REGION BY TUESDAY AS THE UPPER LEVEL PATTERN BECOMES MORE ACTIVE. MODELS INDICATE THAT SEVERAL UPPER LEVEL IMPULSES EMBEDDED IN THE NW FLOW WILL MOVE ACROSS EASTERN KENTUCKY THROUGH THE END OF THE FORECAST PERIOD BRINGING INCREASED SHOWER AND THUNDERSTORM CHANCES THROUGH THE END OF THE WORK WEEK. TEMPERATURES (AND HUMIDITY) WILL INCREASE BACK INTO THE UPPER 80S BY THE END OF THE PERIOD...WITH HEAT INDICES LIKELY SURPASSING THE 90 DEGREE MARK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 243 AM EDT THU JUL 30 2015 CONDITIONS WERE MOSTLY VFR AT THE START OF THE PERIOD. A DETERIORATION TO IFR AND MVFR IS EXPECTED OVERNIGHT. IMPROVEMENT BACK TO VFR SHOULD OCCUR ON THURSDAY MORNING. A SHOWER OR THUNDERSTORM WILL BE POSSIBLE UP UNTIL A COLD FRONT MOVES THROUGH FROM NW TO SE. THIS WILL HAPPEN BETWEEN ABOUT 09Z AND 16Z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JP LONG TERM...JVM AVIATION...HAL

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