Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 300818 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 418 AM EDT MON MAR 30 2015 .SHORT TERM...
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(TODAY THROUGH TUESDAY) ISSUED AT 358 AM EDT MON MAR 30 2015 A COLD FRONT ASSOCIATED WITH A LOW PRESSURE SYSTEM TRACKING WELL NORTH OF THE AREA FROM THE GREAT LAKES REGION AND INTO ONTARIO AND QUEBEC IS WORKING FROM CENTRAL KY INTO EASTERN KY ATTM. BEHIND THIS FRONT...PLENTY OF CLEARING IS OCCURRING OVER WESTERN KY AND MUCH OF THE MID MS VALLEY REGION. IN ADVANCE OF THE FRONT...SOME SHOWERS HAVE MOVED ACROSS THE AREA AND THESE ARE NOW GENERALLY CONFINED TO THE SOUTHERN HALF OF THE AREA. IN ADDITION...THE GUSTY WINDS THAT WE HAD EXPERIENCED AS THE SHOWERS ARRIVED AND IN THE HIGHER TERRAIN HAVE ALSO SLACKENED AS THE CORE OF THE LOW LEVEL JET HAS BEEN SHIFTING EAST OF THE AREA. THE COLD FRONT WILL MOVE ACROSS THE AREA FOR THE REMAINDER OF THE NIGHT...AND SHOULD HAVE MOVED INTO VA PRIOR TO DAYBREAK. AS THE FRONT...THIS SHOULD BRING AN END TO THE SHOWER CHANCES AND THE LOW CLOUDS SHOULD BEGIN TO THIN BEHIND IT AS WELL. SOME SHALLOW CU DEVELOPMENT IS ANTICIPATED BEHIND THE FRONT WITH MIXING AND DAYTIME HEATING...BUT IF THESE DEVELOP THESE SHOULD GENERALLY BECOME RATHER SPARSE BY AFTERNOON. WINDS WILL ALSO SHIFT TO THE WEST BEHIND THE FRONT...AND THEN RATHER QUICKLY TO THE NORTHWEST...USHERING DRIER AIR BACK INTO THE REGION...BUT NOT AS DRY AS THE AIRMASS THAT WAS EXPERIENCED ON SUNDAY. THIS AIRMASS SHOULD ALSO WARM INTO THE UPPER 50S TO LOWER 60S...WHILE DEWPOINTS DROP OFF TO AROUND 30 AND PROBABLY BELOW FOR A TIME. THE MAV NUMBERS AT PRESENT ARE TOO DRY AND ARE LIKELY TOO DRY FOR THIS AFTERNOON. HOWEVER...THE DEEP MIXING AND UPSTREAM DEWPOINTS SUGGEST SOME UPPER 20S BY MID TO LATE AFTERNOON. THIS WILL BRING RH BOTTOMING OUT AROUND 30 PERCENT THIS AFTERNOON...WITH SOME PLACES A COUPLE OF PERCENT BELOW 30 PERCENT. THIS INITIALLY DRY AIRMASS AND ANTICIPATED BREAK IN CLOUDS THIS EVENING INTO THE OVERNIGHT FOR MANY VALLEY LOCATIONS TO DECOUPLE THIS EVENING AND INTO AT LEAST PART OF THE OVERNIGHT AS SFC HIGH PRESSURE WORKS ACROSS THE TN VALLEY REGION AND SETTLES NEAR THE UPSTATE SC REGION BY SUNRISE ON TUESDAY. THIS DECOUPLING SHOULD OCCUR IN ADVANCE OF THE NEXT NORTHERN STREAM COLD FRONT THAT IS PROGGED TO DROP SOUTH OF THE GREAT LAKES AND APPROACH THE AREA LATE TONIGHT AND ON TUESDAY WITH THE PRESSURE GRADIENT ALSO INCREASING LATE TONIGHT...ESPECIALLY ACROSS THE NORTH. THIS LEADS TO A POTENTIAL TRICKY HOURLY TEMPERATURE FOR VALLEY LOCATIONS THAT GUIDANCE WILL LIKELY NOT HANDLE WELL. THE BOTTOM LINE IS A MODERATE RIDGE/VALLEY TEMPERATURE SPLIT IS ANTICIPATED...ESPECIALLY FOR VALLEYS ALONG OR SOUTH OF INTERSTATE 64 AND TO THE EAST OF INTERSTATE 75. SOME LOW TO MID 30S ARE EXPECTED IN VALLEY LOCATIONS... WHILE RIDGETOP AREAS LIKE JKL SHOULD HOLD IN THE LOWER 40S. AS THE COLD FRONT DROP SOUTH INTO THE OH VALLEY ON TUESDAY...THE PRESSURE GRADIENT SHOULD KEEP WINDS A BIT STRONGER THAN AVERAGE. WINDS SHOULD INITIALLY BE FROM A DRY SOUTHERLY DIRECTION ON TUESDAY...BUT SHOULD BECOME INCREASINGLY MORE WEST WHICH SHOULD ALLOW FOR THE AIRMASS TO RECOVER AND DEWPOINTS TO GRADUALLY COME UP AHEAD OF THE FRONT DESPITE DEEP MIXING. RH SHOULD BOTTOM OUT NOT FAR FROM 30 PERCENT ACROSS MUCH OF THE AREA...WHILE WINDS SHOULD AVERAGE 10 TO 15 MPH. MODEL GUIDANCE SUGGESTS THERE MAY BE ENOUGH INSTABILITY AHEAD OF THE FRONT FOR POSSIBLY A SHOWER NEAR THE VA BORDER...OTHERWISE...THIS FRONT IS NOT EXPECTED TO BRING MORE THAN AN INCREASE IN CLOUDS ON TUE AFTERNOON. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 355 AM EDT MON MAR 30 2015 SHORT WAVE RIDGING BUILDS IN OVER KENTUCKY AFTER A WEAK COLD FRONT MOVES THROUGH THE REGION TUESDAY NIGHT. THIS WILL ALLOW RETURN FLOW FROM THE GULF TO SET UP BEGINNING WEDNESDAY NIGHT BEFORE A SERIES OF DISTURBANCES LIFT NEWD OUT OF THE SOUTHERN PLAINS ON THURSDAY. SOME OF THE DETAILS...INCLUDING QPF AMOUNTS...ARE STILL A BIT UNCLEAR DUE TO MODEL DIFFERENCES... BUT IN GENERAL IT LOOKS LIKE WE WILL HAVE SHOWERS WITH A CHANCE OF THUNDERSTORMS COME THROUGH THURSDAY/THURSDAY NIGHT AND THEN AGAIN FRIDAY/FRIDAY NIGHT WITH THE PASSAGE OF A COLD FRONT. THE BETTER UPPER LEVEL SUPPORT COMES ON FRIDAY WITH THE FRONT BUT THERE APPEARS TO BE BETTER SURFACE BASED INSTABILITY ON THURSDAY. SO HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS THURSDAY AFTERNOON THROUGH EARLY SATURDAY MORNING. ONCE THE LOW PRESSURE SYSTEM DEPARTS KENTUCKY...HIGH PRESSURE BUILDS IN OVERHEAD. THIS WILL ALLOW FOR SEASONABLE TEMPERATURES AND MOSTLY SUNNY SKIES TO DOMINATE THE SENSIBLE WEATHER THROUGH MONDAY.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 215 AM EDT MON MAR 30 2015 A WEAK COLD FRONT IS WORKING ACROSS THE COMMONWEALTH ATTM. THE DRY LOW LEVEL AIR THAT WAS INITIALLY IN PLACE ACROSS THE REGION IS KEEPING CIGS IN THE VFR RANGE. WITH VFR CIGS AND VIS OBSERVED UPSTREAM WHERE THE AIRMASS WAS MORE MOIST AND THE FACT THAT THE BAND OF SHOWERS WILL TAPER OFF DURING THE FIRST 2 HOURS OF THE PERIOD AT SYM...JKL...LOZ AND SME AND THE HEAVIEST SHOWERS SHOULD STAY SOUTH OF SJS...WE HAVE OPTED TO KEEP THE CIGS AND VIS IN THE VFR RANGE JUST ABOVE THE VFR/MVFR BREAK THROUGH THE PERIOD. A BRIEF DROP TO MVFR CIGS AND OR VIS IS POSSIBLE ESPECIALLY AT ANY LOCATIONS THAT EXPERIENCE THE HEAVIEST SHOWERS DURING THE FIRST 3 TO 4 HOURS OF THE PERIOD. THE LOW CLOUDS SHOULD LIFT INTO SOME HIGH BASED FLAT CU 12 THROUGH AROUND 17Z...BEFORE MIXING OUT ALTOGETHER. WINDS WILL BE A BIT GUSTY AT TIMES DURING THE FIRST 3 HOURS OF THE PERIOD OR SO WITH SOME GUSTS UP TO 20KT POSSIBLE. WINDS WILL INITIALLY BE MAINLY SOUTH TO SOUTHWEST...WITH SOME SHIFTS TO WEST IN SHOWERS. THE WINDS WILL SHIFT TO WEST BEHIND THE FRONT...BETWEEN ABOUT 9Z AND 12Z...THEN NORTHWEST AROUND 15Z WITH SPEEDS AT ALL OF THESE DIRECTIONS UPWARDS OF 10KT. WINDS WILL SLACKEN AND BECOME VARIABLE AS HIGH PRESSURE BUILDS IN LATE IN THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...JVM AVIATION...JP

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