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...(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.

&&

.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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