Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 011755
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
155 PM EDT MON SEP 1 2014

.UPDATE...
ISSUED AT 155 PM EDT MON SEP 1 2014

UPDATED THE FORECAST TO BETTER TIME A LINE OF SCATTERED SHOWERS AND
THUNDERSTORMS MOVING IN FROM THE WEST. THIS LINE IS OUT AHEAD OF THE
COLD FRONT IN THE WARM AIR. THERE IS A BIT OF CURVATURE TO THE LINE
OF HEAVIEST STORMS;...SO WILL BE WATCHING FOR SOME POTENTIALLY STRONG
WIND GUSTS AS THE LINE GOES THROUGH. THE MERCER AND LINCOLN COUNTY
MESONET SITES SAW WIND GUSTS OF 30 MPH AS THE LINE WENT THROUGH.
CURRENT THINKING IS THE MAX GUSTS WILL STAY BELOW 40 MPH AND WILL BE
IN THE 20 TO 30 MPH RANGE AS THE STORMS MOVE INTO EASTERN KENTUCKY.
THE HEATING WILL BE A LITTLE BETTER...HOWEVER THE STORMS SEEM TO BE
WEAKENING A LITTLE BIT. SO FAR...HAVE ONLY BEEN SEEING UP TO ONE
QUARTER OF AN INCH OF RAIN FROM THE STORMS. HAVE A LITTLE CONCERN FOR
PARTS OF EASTERN KENTUCKY THAT GOT HAMMERED LAST NIGHT FROM THE HEAVY
RAIN...HOWEVER THESE STORMS HAVE BEEN QUITE PROGRESSIVE AND HAVE NOT
YET SEEN ANY TRAINING OF THE ECHOES.

UPDATE ISSUED AT 1048 AM EDT MON SEP 1 2014

UPDATED THE FORECAST TO INCLUDE ALL OF EASTERN KENTUCKY IN THE CHANCE
OF PRECIPITATION TODAY BASED ON THE HIGH HRRR AND RUC MODEL OUTPUT AS
WELL AS THE CURRENT RADAR. BASED ON THE NAM BUFFER SOUNDINGS...DO
HAVE SOME CONCERN THAT SOME OF THE STORMS TODAY COULD PRODUCE
STRONG...BUT SUB SEVERE...WIND GUSTS TODAY. THERE IS SUFFICIENT
INSTABILITY AND SOME DRY AIR ALOFT THAT WOULD MAKE THIS FAVORABLE.
STILL HAVE CONCERN FOR SOME STRONG STORMS FOR TUESDAY AFTERNOON AND
EVENING AS WELL. WOULD NOT BE TOO SURPRISED TO SEE EASTERN KENTUCKY IN
AN SPC SLIGHT RISK BOX FOR TOMORROW. THE REST OF THE FORECAST IS ON TRACK.

UPDATE ISSUED AT 647 AM EDT MON SEP 1 2014

CLOUD COVER HAS EXPANDED A BIT FROM EARLIER...SO HAVE ADJUSTED THE
SKY COVER TO REFLECT CLOUDIER SKIES THROUGH DAYBREAK. ALSO ADJUSTED
TEMPERATURES UP A FEW DEGREES ACROSS THE BOARD AS THE CLOUDS ARE
HOLDING TEMPERATURES UP MAINLY IN THE LOW 70S. HRRR CONTINUES TO
PAINT OUT SOME ISOLATED TO SCATTERED SHOWERS AND STORMS THIS
AFTERNOON...AND THE 06Z NAM HAS ALSO NOW SUPPORTING A FEW SHOWERS AND
STORMS. THUS IT DOES LOOK LIKE SOME ACTIVITY CAN BE EXPECTED BY THE
AFTERNOON HOURS.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 331 AM EDT MON SEP 1 2014

ZONAL FLOW RESIDES ACROSS KENTUCKY THIS MORNING...WITH A SHORTWAVE
TROUGH PUSHING ACROSS THE NORTHERN PLAINS. THE ZONAL FLOW FOR TODAY
WILL MEAN A QUIETER DAY. HOWEVER...A SUBTLE UPPER LEVEL WAVE WILL
PUSH ACROSS CENTRAL/NORTHEAST KENTUCKY THIS AFTERNOON AND EVENING.
WHILE OPERATIONAL GUIDANCE SUGGESTS VERY LITTLE IF ANY PRECIPITATION
TODAY...HI RES MODELS HAVE BEEN CONSISTENT ON SHOWING ISOLATED TO
SCATTERED CONVECTION DEVELOPING TODAY. THE MODEL GUIDANCE DOESN`T
SEEM TO MATCH UP TO WHAT THE HI RES MODELS ARE SHOWING. GIVEN THE
RECENT HISTORY OF HI RES MODELS DOING FAIRLY WELL WITH
CONVECTION...HAVE OPTED TO GO WITH ISOLATED TO SCATTERED SHOWERS AND
STORMS THIS AFTERNOON WITH THE HIGHEST CORRIDOR OF POPS FROM SOUTH
CENTRAL KENTUCKY...INTO NORTHERN AND NORTHEAST KENTUCKY.
HOWEVER...CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS DEVELOPING
ON THE HIGHER TERRAIN TO THE SOUTHEAST. WITH MODEST PRECIPITABLE
WATER VALUES AROUND 1.7 AND VERY HIGH FREEZING LEVELS (>15KFT)
POTENTIAL MAY EXISTS FOR SOME PERIODS OF VERY HEAVY RAIN.
FORTUNATELY...STORM MOVEMENT SHOULD BE SUFFICIENT TO LIMIT ANY
FLOODING CONCERNS TODAY.

THE SHOWERS/STORMS TODAY WILL BE TIED TO THE PEAK INSTABILITY HOURS
FROM MID AFTERNOON TO EARLY EVENING...BEFORE DYING OFF. THIS WILL
YIELD A QUITE NIGHT ACROSS THE AREA TODAY. CLEARING SKIES COULD YIELD
SOME PATCHY FOG...BUT WE MAY KEEP ENOUGH WIND AGAIN TO LIMIT IT TO
SOME DEGREE. THE SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SEND
A WEAK COLD FRONT INTO THE OHIO RIVER VALLEY REGION. THIS WILL SPARK
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP ON
TUESDAY. THESE WILL TRACK SOUTHEAST ACROSS EASTERN KENTUCKY THROUGH
THE AFTERNOON AND EVENING HOURS. WITH MODEST 30-40KT BULK SHEAR
VALUES...THE POTENTIAL WILL EXISTS FOR SOME LINEAR STORM SEGMENTS
CAPABLE OF DAMAGING WINDS. PLAN TO CONTINUE TO HIGHLIGHT THIS
POTENTIAL IN THE HWO. THE FRONT WILL WASH OUT AND STALL OVER SOUTHERN
KENTUCKY BY THE EVENING HOURS WITH ACTIVITY DYING OUT WITH THE LOSS
OF DAYTIME HEATING.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 410 AM EDT MON SEP 1 2014

WARM WEATHER IS EXPECTED TO CONTINUE INTO THE EXTENDED PERIOD. THE
EXTENDED PERIOD OF THE FORECAST WILL BEGIN WITH THE TROUGH IN THE
NEAR TERM DEPARTING TO THE NORTH AND EAST...WITH A RATHER ZONAL
PATTERN TO START OVERALL. THE NEAR TERM COLD FRONT IS EXPECTED TO
BE DROPPING OR HAVE DROPPED ACROSS THE REGION AT THE START OF THE
PERIOD...FROM TUE NIGHT INTO EARLY ON WEDNESDAY AND BRING ISOLATED TO
SCATTERED CONVECTION. THE BOUNDARY SHOULD BECOME MORE ILL DEFINED AND
RATHER WASHED OUT ON WEDNESDAY AS IT REACHES THE TN VALLEY REGION.
WITH THE BOUNDARY IN THE AREA...CONVECTION WILL REMAIN POSSIBLE
MAINLY ACROSS THE SOUTH AND SOUTHEAST ON WEDNESDAY. MID AND UPPER
LEVEL RIDGING IS THEN EXPECTED TO BRIEFLY AMPLIFY ACROSS THE
SOUTHEASTERN AND MID ATLANTIC STATES THROUGH FRIDAY.

AS THE RIDGE BUILDS AND A SHORTWAVE TROUGH OR TWO IN THE ZONAL FLOW
MOVES FROM THE CENTRAL PLAINS TOWARD THE LOWER OH VALLEY REGION AND
INTO THE MIDDLE OH VALLEY REGION...WHAT IS LEFT OF THE BOUNDARY AND
DEEPER MOISTURE SHOULD ALSO BEGIN TO RETREAT BACK INTO THE REGION BY
WED NIGHT INTO THU. THIS SHOULD LEAD TO AN ADDITIONAL PERIOD WHERE
CONVECTION IS POSSIBLE. THE MODEL CONSENSUS IS FOR THE RIDGE TO
BUILD IN BEHIND THIS SHORTWAVE FOR THU NIGHT AND INTO EARLY ON FRI.
OVERALL...CONVECTION FROM THU NIGHT INTO FRIDAY MAY HAVE SOMEWHAT OF
A DIURNAL FLAVOR.

ALSO DURING THIS TIME...A SERIES OF TROUGHS WILL TRAVERSE THE
NORTHERN STREAM AND SEND A COLD FRONT SOUTH INTO AND GRADUALLY ACROSS
THE THE LOWER OH VALLEY REGION AND EASTERN KENTUCKY THIS WEEKEND.
THIS WILL BRING PERIOD OF UNSETTLED WEATHER...WITH PROLONGED CHANCES
FOR SHOWERS AND THUNDERSTORMS FROM SATURDAY INTO SUNDAY.

TEMPERATURES ARE EXPECTED TO AVERAGE NEAR TO A FEW DEGREES ABOVE
NORMAL FROM WED INTO SATURDAY FOR DAYTIME HIGHS...WITH OVERNIGHT LOW
HAVING THE GREATER DEPARTURE OF NEARLY 5 DEGREES ON AVERAGE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 155 PM EDT MON SEP 1 2014

A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS ARE MOVING IN FROM THE
WEST. THIS LINE IS OUT AHEAD OF THE COLD FRONT IN THE WARM AIR. THERE
IS A BIT OF CURVATURE TO THE LINE OF HEAVIEST STORMS;...SO WILL BE
WATCHING FOR SOME POTENTIALLY STRONG WIND GUSTS AS THE LINE GOES
THROUGH. THE MERCER AND LINCOLN COUNTY MESONET SITES SAW WIND GUSTS
OF 30 MPH AS THE LINE WENT THROUGH. CURRENT THINKING IS THE MAX GUSTS
WILL STAY BELOW 40 MPH AND WILL BE IN THE 20 TO 30 MPH RANGE AS THE
STORMS MOVE INTO EASTERN KENTUCKY. THE HEATING WILL BE A LITTLE
BETTER...HOWEVER THE STORMS SEEM TO BE WEAKENING A LITTLE BIT. SOME
TEMPO IFR IS POSSIBLE WITH THE HEAVIEST STORMS. OTHERWISE VFR
CONDITIONS WILL PREVAIL UNTIL 6 TO 8Z WHEN SOME MVFR MIST MAY BE
EFFECTING THE TAF SITES. LOOKING FOR VSBY DOWN TO ABOUT 2 SM AT THE
TAF SITES BUT DOWN TO 1/2SM IN THE RIVER VALLEYS...ESPECIALLY IN
AREAS THAT GET RAIN TODAY. ONCE THE MIST CLEARS IN THE
MORNING...EXPECTING TO SEE SOME CONVECTION DEVELOP AGAIN TOMORROW.
THE CHANCE FOR STRONG THUNDERSTORMS IS GREATER FOR TOMORROW THAN IT
WAS TODAY. THE TIMING OF STORMS FOR TOMORROW IS TOO
UNCERTAIN...HOWEVER SHOULD BE AFTER 16Z.

&&

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

$$

UPDATE...JJ
SHORT TERM...KAS
LONG TERM...JP
AVIATION...JJ






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