Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 291943 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 343 PM EDT WED JUL 29 2015 .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. AREAWIDE...A WARM AND MOIST AIRMASS IS IN PLACE WITH TEMPERATURES IN THE MID TO UPPER 80S TO NEAR 90 AND DEWPOINTS 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 AIRMASS 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 DEWPOINTS 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 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 125 PM EDT WED JUL 29 2015 MVFR LINGERS WHERE THE EARLY MORNING FOG AND STRATUS HAS LIFTED INTO CU. THIS SHOULD CONTINUE LIFTING...WITH VFR EXPECTED OUTSIDE OF ANY SHRA AND TSRA BY 20Z. ISOLATED TO SCATTERED SHRA AND TSRA SHOULD DEVELOP DURING THE FIRST 4 HOURS OF THE PERIOD...WITH A POSSIBLE LULL IN ACTIVITY BEFORE MORE SCATTERED SHRA AND TSRA AS A COLD FRONT MOVES INTO THE REGION AFTER 0Z. ANY HEAVIER SHRA OR TSRA WILL BRING BRIEF IFR VIS AND OR CIGS. BEHIND THE FRONT...GENERALLY AFTER THE 4Z TO 6Z PERIOD...ANOTHER PERIOD OF IFR TO MVFR IS POSSIBLE. THESE LOW CIGS WOULD LIFT BEFORE THE END OF THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...JVM AVIATION...JP

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