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000
FXUS63 KJKL 180815
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
415 AM EDT TUE JUN 18 2013

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 415 AM EDT TUE JUN 18 2013

LIGHT TO MODERATE RAIN WAS OCCURRING OVER MUCH OF THE AREA DURING THE
PREDAWN HOURS. THIS FOLLOWED AN EVENING WITH LOCALLY HEAVY RAINFALL
AND ISOLATED FLASH FLOODING. WILL EXPECT PRECIP TO CONTINUE INTO THE
DAY...WITH A POSSIBILITY OF THUNDER AS WELL. HOWEVER...LIMITED
INSOLATION WILL PREVENT SUBSTANTIAL DESTABILIZATION. THE BIGGEST
CONCERN WILL BE HEAVY RAINFALL DUE TO WEAK FLOW AND A VERY MOIST
ATMOSPHERIC COLUMN. HOWEVER...WITH LIMITED DESTABILIZATION...THERE IS
NOT A LOT OF CONFIDENCE IN GETTING EXTREME RAINFALL RATES SUCH AS
LAST EVENING. WE MAY END UP WITH SUBSTANTIAL RAINFALL...BUT OCCURRING
OVER A LONGER TIME FRAME. THE GFS WAS THE HEAVIEST ON PRECIP...BUT IT
WAS NOT VERIFYING WELL UPSTREAM IN NW TN AND SOUTH CENTRAL KY...WITH
AREAL AVERAGE RAINFALL SO FAR BEING LESS THAN THE GFS SUGGESTED. THIS
BEING THE CASE...HAVE OPTED NOT TO GO WITH A FLASH FLOOD WATCH AT
THIS POINT. HOWEVER...IT WILL NEED TO CONTINUE TO BE EVALUATED AS THE
EVENT EVOLVES THIS MORNING.

THE SHORTWAVE TROUGH...RIGHT ENTRANCE REGION OF UPPER JET...AND
SURFACE LOW COMBINING TO BRING PRECIP WILL BE MOVING OUT DURING THE
DAY...AND BY EARLY EVENING MOST OF THE PRECIP SHOULD HAVE ENDED.
HOWEVER...ANOTHER SHORTWAVE TROUGH WILL BE DROPPING IN FROM THE NW
TONIGHT. IT WILL NOT HAVE AS MUCH MOISTURE TO WORK WITH...BUT THE
MODELS DO SHOW SOME PRECIP ASSOCIATED WITH IT...AND 20-40 PERCENT
POPS WILL BE USED LOCALLY.

THIS WAVE WILL BE EXITING TO THE EAST WEDNESDAY MORNING. MODELS SHOW
SOME LIGHT PRECIP LINGERING INTO WEDNESDAY...BUT FORECAST SOUNDINGS
DO NOT LOOK VERY SUPPORTIVE. THINK THAT COVERAGE WOULD BE LOW...AND
HAVE OPTED FOR SUB-20 POPS AT THIS POINT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE JUN 18 2013

STATIONARY 500MB CUT OFF LOW OFF NW COAST TODAY WILL FINALLY BEGIN
TO ROTATE EASTWARD AND INLAND ACROSS WA AND OR BY START OF EXTENDED
FORECAST PERIOD. AS IT MOVES INLAND...ZONAL PATTERN ACROSS MUCH OF
THE CONUS WILL TRANSITION TO MORE MERIDIONAL...WITH STRONG RIDGING
FORMING OVER THE EXTREME SOUTH-CENTRAL CONUS. THIS PATTERN WILL
REMAIN IN PLACE THROUGH MUCH OF THE EXTENDED PERIOD...WITH LOW
STAYING STATIONARY OFF THE NW COAST THROUGH THE WORK WEEK. FOR
KY...WE WILL BE IN A SLIGHT TROUGHING PATTERN...WITH MULTIPLE
SHORTWAVES AND SURFACE BOUNDARIES EXPECTED TO DEVELOP OFF OF THE
MAIN 500MB LOW AND MIGRATE THROUGH THE TROUGH.
UNFORTUNATELY...MODELS ARE STILL HAVING QUITE A BIT OF DISAGREEMENT
ON TIMING AND IMPACTS OF THESE SHORTWAVES ACROSS EASTERN KY. 500MB
TROUGH OVER THE NW WILL FINALLY START TO MOVE EASTWARD AGAIN
SATURDAY. THOUGH MODELS ARE VERY DIVERGENT ON SOLUTIONS AT THIS
POINT...GENERAL CONSENSUS IS THAT THIS WILL PUSH A RIDGING PATTERN
FROM THE SOUTH-CENTRAL CONUS EASTWARD AND ACROSS THE MISSISSIPPI AND
OHIO VALLEYS. RIDGING WILL PERSIST THROUGH THE REST OF THE FORECAST
PERIOD /THROUGH THE WEEKEND AND BEGINNING OF NEXT WEEK/. THAT BEING
SAID...THIS WILL NOT STOP THE POTENTIAL FOR SOME AFTERNOON
CONVECTION OVER THE CWA...BUT BEING SO FAR OUT IN THE
FORECAST...WENT WITH A MODEL CONSENSUS FOR POPS AND QPF.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 208 AM EDT TUE JUN 18 2013

CONDITIONS WERE LARGELY VFR AT TAF ISSUANCE...WITH AREAS OF MVFR.
SHOWERS WERE ONGOING IN MANY AREAS. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE EXPECTED TOWARD DAWN AND LASTING INTO TUESDAY
MORNING. MUCH OF THE FORECAST AREA CAN EXPECT A DETERIORATION TO IFR
AND MVFR WITH THIS. THE PRECIP WILL DEPART TO THE SOUTHEAST DURING
THE DAY...ALLOWING A RETURN TO MOSTLY VFR BY LATE AFTERNOON.


&&

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

$$

SHORT TERM...HAL
LONG TERM...JMW
AVIATION...HAL