Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 180015 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
815 PM EDT FRI OCT 17 2014

.UPDATE...
ISSUED AT 800 PM EDT FRI OCT 17 2014

23Z SFC ANALYSIS SHOWS DEEP LOW PRESSURE OVER THE EASTERN GREAT
LAKES. A COLD FRONT STRETCHES SOUTHWEST FROM THIS AND IS NOW CROSSING
INTO KENTUCKY FROM THE NORTHWEST. THIS FRONT WILL BRING A REINFORCING
SHOT OF COOL AIR TO EAST KENTUCKY THROUGH THE NIGHT. IN ADDITION...
MID AND LOWER LEVEL CLOUDS WILL BUILD INTO THIS PART OF THE STATE
POST FRONTAL. THIS WILL GIVE THE NIGHT A CAA PATTERN FOR OVERNIGHT
LOWS...EVEN THOUGH SOME EASTERN VALLEY DROP OFF IN TEMPERATURES WILL
BE POSSIBLE THROUGH THE EVENING AHEAD OF THE THICKER CLOUDS ARRIVING.
HAVE TRIED TO REPRESENT THAT IN THE TEMPERATURE GRIDS THROUGH THE
REST OF THE NIGHT. OTHERWISE THE REST OF THE FORECAST WAS ON TRACK SO
ONLY MINOR CHANGES WERE MADE TO THE GRIDS. DID FINE TUNE THE T AND TD
ONES PER THE LATEST OBS...TRENDS...AND GUIDANCE. THE UPDATES HAVE
BEEN SENT TO THE NDFD AND WEB SERVERS. WILL ALSO UPDATE THE ZFP LATER
TO REMOVE THE EVENING WORDING AND BETTER REFLECT THE SKY COVER ONCE
THE CLOUDS MOVE IN FOR THE REST OF THE NIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 313 PM EDT FRI OCT 17 2014

AFTER A ABSOLUTELY BEAUTIFUL DAY...A SHORT WAVE AND ASSOCIATED FRONT
WILL BE MOVING INTO THE AREA ON SATURDAY. THE MODELS ALL HAVE SOME
LIGHT PRECIPITATION FORECAST FOR THE SATURDAY AND SATURDAY EVENING.
THIS IS PRETTY MUCH LIKE A CLIPPER SYSTEM...IN THAT IT WILL NOT HAVE
A LOT OF LOW LEVEL MOISTURE WITH IT. WITH THIS TYPE OF A SYSTEM...THE
CLOUDS WILL GRADUALLY LOWER AND THEN AS PRECIPITATION FALLS INTO THE
LOWER LAYERS TO SATURATE IT...IT WILL FINALLY START HITTING THE
GROUND. SO IT WILL LIKELY START OUT AS SPRINKLES AND THEN CHANGE TO
LIGHT SHOWERS. IN EITHER CASE...JUST A COUPLE OF HUNDREDTHS OF RAIN
IS EXPECTED WITH THIS SYSTEM...WITH THE GREATEST CHANCES AND AMOUNTS
EXPECTED IN THE FAR EASTERN PORTION OF THE STATE. THE BIG STORY IS
THE POTENTIAL FOR SOME PATCHY FROST ON SATURDAY NIGHT. THIS IS A
DIFFICULT FORECAST BECAUSE IT WILL DEPEND SO MUCH ON THE WINDS AND
HOW QUICKLY THE CLOUDS CLEAR OUT. PUT SOME PATCHY FROST IN THE
FORECAST. DEPENDING OF THE WINDS AND CLOUDS...IT COULD BE BETTER OR
WORSE...BUT FOR NOW DECIDED ON PATCHY AND MOSTLY IN THE VALLEYS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 313 PM EDT FRI OCT 17 2014

12Z SUNDAY STARTS OFF WITH A HIGH PRESSURE SETTLING INTO THE
TENNESSEE VALLEY REGION...ALLOWING FOR ABUNDANT SUNSHINE AND DRY
CONDITIONS. WINDS WILL GENERALLY BE OUT OF THE NW ON THE BACKSIDE OF
THE EXITING TROUGH...HELPING TO USHER IN A MUCH COOLER AIRMASS.
TEMPS SHOULD TOP OUT AROUND THE 60 DEGREE MARK ON SUNDAY...WHILE
SUNDAY NIGHT COULD SEE A GOOD RIDGE/VALLEY SPLIT WITH OPTIMAL
RADIATIONAL COOLING. TEMPS DROPPING INTO THE UPPER 30S ARE A GOOD
POSSIBILITY FOR SUNDAY NIGHT...WITH SOME PATCHY FROST NOT OUT OF THE
QUESTION ACROSS THE REGION.

A S/WV WILL MOVE ACROSS THE REGION DURING MONDAY AFTERNOON/EVENING.
BOTH THE 12Z GFS AND 00Z ECMWF SHOW A GOOD AMOUNT OF LOW-TO-MID LEVEL
MOISTURE OVER EASTERN KENTUCKY...THOUGH THE GFS SOLUTION IS A BIT
SLOWER AND WETTER. SO THE EXACT TIMING AND EXTENT OF THE PRECIP IS A
BIT UNCERTAIN. IF THE GFS PANS OUT...THE MOISTURE WILL RIDE ALONG THE
FRONT ACROSS MUCH OF KY WITH GOOD COVERAGE BETWEEN 00Z TUESDAY AND
06Z WEDNESDAY. MEANWHILE THE ECMWF SHOWS THE MAJORITY OF THE MOISTURE
WRAPPED AROUND THE LOW...WITH LESS PRECIP RIDING ALONG THE PROTRUDING
FRONT THAT EXTENDS SWD INTO OUR REGION. THIS SCENARIO WOULD KEEP LESS
MOISTURE ACROSS THE CWA MONDAY NIGHT. IT WOULD ALSO INCREASE THE QPF
AS UPSLOPE INFLUENCES TAKE AFFECT TUESDAY MORNING BEFORE THE SYSTEM
EXITS. UPSLOPE FLOW COULD LINGER AS THE UL S/WV STRENGTHENS INTO A
CLOSED LOW EAST OF KY...WITH STAGNANT MOTION EXPECTED MUCH OF WEDNESDAY.

THERE ARE SIGNIFICANT MODEL DIFFERENCES AS TO HOW THE CLOSED LOW
EVOLVES DURING THE THURSDAY/FRIDAY TIME FRAME. THE GFS IS MUCH FASTER
WITH THE LOWS MVMT UP THE NEW ENGLAND COAST...WHICH WOULD ALLOW FOR
A RIDGE TO BUILD IN TO OUR CWA ON THURSDAY. HOWEVER...THE ECMWF KEEPS
THE CLOSED LOW WOBBLING ALONG THE MID ATLANTIC COASTLINE THROUGH
FRIDAY MORNING. THIS SOLUTION WOULD KEEP SOME REMNANT MOISTURE AND
WEAK NW FLOW IN THE EASTERN PORTION OF OUR CWA DURING THAT PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 815 PM EDT FRI OCT 17 2014

VFR CONDITIONS WILL GIVE WAY TO MVFR LATER TONIGHT AS THE CLOUDS MOVE
BACK INTO THE AREA AND LOWER POST FRONTAL. SOME IFR CIGS WILL BE
POSSIBLE TOWARDS DAWN BUT CONDITIONS SHOULD IMPROVE BY MID MORNING...
BUT STILL BE IN THE MVFR RANGE THROUGH THE REST OF THE DAY ON
SATURDAY. WINDS WILL BE FROM THE NORTHWEST AT 5 TO 10 KTS THROUGH
EVENING BEFORE SETTLING INTO SATURDAY MORNING THEN PICKING UP AGAIN
AT 5 TO 10 KTS FROM THE NORTHWEST.

&&

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

$$

UPDATE...GREIF
SHORT TERM...JJ
LONG TERM...JVM
AVIATION...GREIF



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