Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 271034
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
634 AM EDT MON JUL 27 2015

.UPDATE...
ISSUED AT 634 AM EDT MON JUL 27 2015

ISOLATED SHOWERS HAVE BEGAN POPPING UP OVER THE LAST COUPLE OF
HOURS ACROSS PORTIONS OF CENTRAL AND EASTERN KY. THIS WAS A FEW
HOURS SOONER THAN FORECASTED...SO MAIN CHANGE DURING THIS UPDATE
WAS TO MAKE SURE THE POPS AND WEATHER BETTER REFLECTED THE ONGOING
CONDITIONS. KEPT ISOLATED POPS IN THROUGH THE MORNING...THOUGH IF
THE LARGER AREA OF SHOWERS CURRENTLY MOVING OVER CENTRAL KY IS
ABLE TO HOLD TOGETHER AS IT REACHES OUR WESTERN CWA...POPS MAY
NEED TO BE UPGRADED ONCE MORE.

SHOWERS ARE STILL LIGHT ENOUGH OVER OUR CWA AT THIS POINT THAT
LEFT OUT MENTION OF THUNDER THROUGH THE EARLY MORNING /11Z/...BUT
ONCE THE SUN RISES...BETTER INSTABILITY WILL LIKELY RESULT IN MORE
LIGHTNING STRIKES AND RUMBLES OF THUNDER WITH ANY OF THESE CELLS.
PARAMETERS ARE STILL NOT LOOKING VERY FAVORABLE FOR SEVERE
DEVELOPMENT TODAY...THOUGH THE SLOW WEST TO EAST NATURE OF THE
STORMS ALONG THE NEARLY STATIONARY BOUNDARY MAY LEAD TO SOME
TRAINING OR LOCATIONS EXPERIENCING HEAVY RAINS FOR AN EXTENDED
PERIOD OF TIME. THIS WILL NEED TO BE MONITORED AS WE GO THROUGHOUT
THE DAY.

FINALLY...LOADED IN THE LATEST OBSERVATIONAL DATA FOR TEMPS...DEW
POINTS...AND WINDS...TO MAKE SURE THAT THESE NEAR TERM GRIDS WERE
REFLECTING THE CURRENT CONDITIONS.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 316 AM EDT MON JUL 27 2015

A WEAK SURFACE BOUNDARY HAS SHIFTED SOUTH ACROSS THE OHIO RIVER AND
CURRENTLY SITS JUST NORTH OF OUR CWA. SHOWERS AND THUNDERSTORMS ARE
STILL SHOWING UP ALONG AND NEAR THIS BOUNDARY EARLY THIS
MORNING...BUT ARE CONTINUING TO SHOW A DIMINISHING TREND. AS
SUCH...NOT EXPECTING THIS CONVECTION TO MAKE IT INTO THE CWA BEFORE
12Z. WPC SHOWS THE FRONT REMAINING NEARLY STATIONARY THROUGH THE
MORNING HOURS...BEFORE FINALLY SHIFTING SLOWLY SOUTHWARD THROUGH
CENTRAL KY LATE IN THE AFTERNOON. WITH THE INTRODUCTION OF DAYTIME
HEATING AFTER 12Z THIS MORNING...EXPECT THIS BOUNDARY...THOUGH
WEAK...TO PROVIDE ENOUGH LIFT AND INSTABILITY TO SPARK A NEW SET OF
SHOWERS AND THUNDERSTORMS. MODELS CONTINUE TO PEG THE FAR SE AS THE
EPICENTER FOR MOST OF THESE SHOWERS AND THUNDERSTORMS...PERHAPS DUE
TO THE EASTERLY AND SLIGHT UPSLOPE FLOW. HOWEVER...GIVEN THE WEAK
NATURE OF THE BOUNDARY...IN ADDITION TO THE VERY LIGHT WINDS...DO
NOT EXPECT THUNDERSTORMS TO BE STRONG IN NATURE OR VERY
SUSTAINABLE/LONG LIVED ACROSS ANY PART OF THE CWA.

THE BOUNDARY WILL LIKELY REMAIN PARKED ACROSS KY TONIGHT AND
POSSIBLY EVEN INTO THE DAY TUESDAY BEFORE IT FINALLY FADES OUT. THIS
COULD KEEP ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS
THE CWA THROUGH THIS ENTIRE TIME PERIOD...THOUGH LOSS OF DAYTIME
HEATING WILL LIKELY CUT DOWN ON THUNDER CHANCES OVERNIGHT
TONIGHT...ALONG WITH SOME OF THE CU DEVELOPMENT. DIURNALLY DRIVEN CU
WILL BEEF BACK UP THE CLOUD COVER SOMEWHAT DURING THE DAY TUESDAY AS
BETTER CONVECTION ENSUES. HOWEVER...AS THE BOUNDARY CONTINUES TO
FADE...SO TO WILL THE BEST LIFT...MOISTURE...CLOUDS...AND PRECIP
CHANCES DURING THE AFTERNOON TUESDAY. EXPECT MOST OF THE PRECIP TO
HAVE DIMINISHED BY TUESDAY EVENING.

AS FAR AS TEMPERATURES...THIS FRONTAL BOUNDARY...AS ADVERTISED...
WILL BE WEAK ENOUGH TO CAUSE LITTLE EFFECT ON THE WARM AIR MASS.
LIGHT WINDS AT THE SURFACE WILL GIVE WAY TO A STRONGER NW FLOW
ALOFT. HOWEVER...WITH A BUILDING UPPER LEVEL RIDGE OVER THE CENTRAL
CONUS...WARM AIR ALOFT WILL BE PULLED FROM THE SOUTH CENTRAL
CONUS/GULF COAST...NORTHWARD INTO THE CENTRAL PLAINS...AND THEN
EASTWARD TOWARDS THE OHIO VALLEY. IN ESSENCE...NW FLOW WILL ACTUALLY
RESULT IN THE CONTINUED PULL OF WARMER AIR INTO THE REGION. AS
SUCH...HIGH TEMPS BOTH TODAY AND TOMORROW WILL CONTINUE TO HOVER IN
THE UPPER 80S TO AROUND 90. TEMPERATURES OVERNIGHT WILL MIMIC THOSE
OF EARLY THIS MORNING...STAYING NEAR THE 70 DEGREE MARK WITH HIGH
HUMIDITIES.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 502 AM EDT MON JUL 27 2015

A STRONG UPPER LEVEL HIGH WILL BE OVER THE SOUTHERN PLAINS AT THE
START OF THE PERIOD...WITH RIDGING EXTENDING NORTHEAST OVER THE
GREAT LAKES. THIS WILL RESULT IN LIGHT FLOW ALOFT WITH VERY
LITTLE IN THE WAY OF FEATURES. ENOUGH HEATING AND SURFACE MOISTURE
MAY BE PRESENT TO FUEL SOME THUNDERSTORMS TUESDAY EVENING AND
AGAIN WEDNESDAY AFTERNOON...MAINLY OVER THE HIGHER TERRAIN.
HOWEVER...MOSTLY DRY WEATHER IS EXPECTED.

AN UPPER LOW RIDING ACROSS THE TOP OF THE RIDGE OVER CANADA WILL
FLATTEN THE RIDGE AND SEND IT RETROGRADING TO THE WEST LATE IN THE
WEEK...WITH A BROAD TROUGH RESULTING OVER THE EASTERN CONUS. THIS
WILL SEND A COLD FRONT SOUTHEAST THROUGH THE JKL FORECAST AREA
WEDNESDAY NIGHT AND THURSDAY. MODELS GENERATE SOME PRECIP WITH THE
FRONT...BUT ARE LOOKING LESS IMPRESSIVE IN RECENT RUNS. HAVE USED
20-30 PERCENT POPS.

SURFACE HIGH PRESSURE BUILDING IN BEHIND THE COLD FRONT WILL BRING
A DRIER AIR MASS FOR THURSDAY NIGHT INTO THE WEEKEND...RESULTING
IN MOSTLY CLEAR SKIES WITH COOL NIGHTS AND WARM DAYS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 137 AM EDT MON JUL 27 2015

MAINLY VFR CONDITIONS WILL BE SEEN OVER THE NEXT 24 TO 36 HOURS.
ANOTHER ROUND OF VALLEY FOG MAY DEVELOP LATE TONIGHT...WITH A
POSSIBILITY OF A FEW OF THE TAF SITES BRIEFLY GOING DOWN TO MVFR
VISIBILITIES. HOWEVER...THE IMPACT OF THE CLOUD COVER REMAINS
UNCERTAIN TONIGHT SO HAVE JUST ADDED A BIT OF FOG TO THE LOWER
ELEVATION SITES THAT TEND TO BE MORE PRONE TO SEEING ITS
DEVELOPMENT. CANNOT RULE OUT SHOWER OR A THUNDERSTORM AT ANY SITE
DURING THE LATE MORNING AND AFTERNOON HOURS OF MONDAY...BUT
PLACEMENT AND TIMING IS TOO UNCERTAIN TO INCLUDE IN ANY OF THE
TAFS AT THIS TIME. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH
THE PERIOD.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JMW
SHORT TERM...JMW
LONG TERM...HAL
AVIATION...GRIEF/JMW



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