Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 210632 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
132 AM EST FRI NOV 21 2014

.UPDATE...
ISSUED AT 132 AM EST FRI NOV 21 2014

THE FORECAST REMAINS ON TRACK. JUST MADE A FEW TWEAKS TO THE HOURLY
TEMPERATURES AND DEW POINTS TO ACCOUNT FOR THE LATEST TRENDS IN
OBSERVATIONS.

UPDATE ISSUED AT 1018 PM EST THU NOV 20 2014

THE FORECAST OVERALL HAS BEEN CLOSELY IN TUNE WITH HOURLY OBS SO FAR
THIS EVENING. HOURLY TEMPERATURES AND DEW POINTS HAVE BEEN TWEAKED A
FEW TIMES USING OBS DATA...BUT OVERALL NO CHANGES WERE MADE THAT
WARRANTED ISSUING A NEW ZONE UPDATE AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 307 PM EST THU NOV 20 2014

A COLD FRONT EXITED SE OUT OF THE AREA THIS MORNING...ALLOWING
ANOTHER BRIEF SURGE OF CHILLY AIR TO MOVE IN. THE AIR BEHIND THE
FRONT IS DRY...AND WITH NO PRECIP TO LEAVE RESIDUAL MOISTURE ALONG
THE WESTERN SLOPES OF THE APPALACHIANS...CLOUDS DISSOLVED QUICKLY.
HIGH PRESSURE BUILDING IN FROM THE WEST WILL BE CENTERED OVER OUR
REGION AROUND DAWN. THIS WILL RESULT IN GOOD RADIATING CONDITIONS AND
LIGHT WINDS TONIGHT...ALLOWING TEMPS TO FALL TO THE TEENS AND LOWER
20S. THE HIGH WILL SLOWLY SHIFT TO OUR EAST BY LATE IN THE DAY
FRIDAY...BRINGING AN EVENTUAL RETURN OF WARM AIR ADVECTION.
HOWEVER...IT WILL BE TOO LATE IN THE DAY TO MAKE A BIG DIFFERENCE IN
MAX TEMPS. THE WARM AIR ADVECTION PERSISTS FRIDAY NIGHT...WITH
ISENTROPIC LIFT LEADING TO AN INCREASE IN CLOUDS...ESPECIALLY IN OUR
NW COUNTIES. THERE REMAINS A SLIGHT CHANCE FOR SOME LIGHT PRECIP
THERE TOWARD DAWN. TEMPERATURES WILL LIKELY BOTTOM OUT WELL BEFORE
DAWN AND THEN LEVEL OUT OR BEGIN TO RISE. THE BIGGEST CONCERN WOULD
BE WHETHER TEMPS MAKE IT BACK ABOVE FREEZING IN OUR FAR NW BEFORE ANY
PRECIP MIGHT OCCUR. TEMPS ALOFT LOOK TOO WARM FOR ANYTHING BUT LIQUID
TO FALL...SO HAVE INCLUDED RA AND FZRA AS POTENTIAL PRECIP TYPES
TOWARD DAWN.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 336 PM EST THU NOV 20 2014

SURFACE HIGH PRESSURE WILL PROGRESS TO THE EAST OF THE REGION BY
SATURDAY WITH RETURN FLOW FINALLY BRINGING HIGH TEMPERATURES BACK
INTO THE LOWER 50S. SYNOPTICALLY IN THE UPPER LEVELS GENERALLY
EXPECTING ZONAL FLOW ACROSS MUCH OF THE EASTERN HALF OF THE U.S.
WITH DEVELOPING SHORTWAVE TROUGH ACROSS THE SOUTHERN FOUR CORNER
STATES/NORTHERN MEXICO. THIS FEATURE WILL BRING THE NEXT BEST CHANCE
OF PRECIP TO EASTERN KY. RIGHT NOW FOR SATURDAY THE 06Z GFS DOES SHOW
SIGNALS OF LIGHT PRECIP WHILE BOTH THE ECMWF/NAM. GIVEN THAT THE
SIGNALS ARE VERY LIGHT AND 12Z IS LESS DO NIGHT PLAN TO PUT ANY
SLIGHT POPS ON SATURDAY.

AFTER THIS UPPER LEVEL SHORTWAVE EJECTS OUT OF THE SOUTHERN FOUR
CORNER STATES/NORTHERN MEXICO NE INTO THE SOUTHERN MISSISSIPPI RIVER
VALLEY BY EARLY SUNDAY MORNING. AHEAD OF THIS NEGATIVELY TILTED UPPER
LEVEL SHORTWAVE AND ASSOCIATED DEEPENING SURFACE LOW THERE WILL BE DEEP
SE TO SOUTHERLY FLOW. THIS UNIDIRECTIONAL FLOW WILL TRANSLATE TO DEEP
LAYER MOISTURE AND WAA COMING FROM THE GULF OF MEXICO AS WE MOVE INTO
SATURDAY NIGHT AND SUNDAY. THIS DEEP MOISTURE IS EVIDENT IN THE
FORECAST SOUNDINGS FROM BOTH NAM/GFS WHERE PWAT INDEX ARE AOA INCH.
BY SUNDAY AFTERNOON WE WILL CONTINUE TO SEE MOISTURE STREAMING NORTH
WITH ASSOCIATED WARM FRONT. AFOREMENTIONED SURFACE LOW WILL CONTINUE
TO MOVE NE INTO THE MIDDLE MISSISSIPPI RIVER VALLEY AS WE GO THROUGH
THE DAY SUNDAY. IN TERMS OF SENSIBLE WEATHER EXPECTING THIS SYSTEM TO
BRING GOOD CHANCE OF RAIN TO THE EASTERN KY ESPECIALLY SUNDAY
AFTERNOON INTO SUNDAY NIGHT. DID OPT TO LEAVE SLIGHT CHANCE OF
THUNDER WITH MEAGER INSTABILITY. THE GFS HAS TRENDED A BIT SLOWER
WITH ONSET OF PRECIP AND WILL GO THAT DIRECTION WHICH WILL AID IN
BETTER COLLABORATION WITH OTHER OFFICES.

MOVING INTO THE REST OF THE EXTENDED FORECAST EXPECT THE WARM FRONT
TO CONTINUE TO SURGE NORTH OF THE CWA SUNDAY NIGHT INTO MONDAY. COLD
FRONT WILL BRING CHANCES OF RAIN SHOWERS ACROSS THE REGION EARLY
MONDAY. MODELS DO DIVERGE AT TIMES DURING THE LONGER RANGE PERIOD. GIVEN
THE UNCERTAINTY WILL STICK CLOSER TO THE MODEL BLEND. OVERALL BEHIND
THE COLD FRONT EXPECT A MOSTLY QUIET MORE ZONAL FLOW TO SETUP ACROSS
THE REGION WITH TEMPERATURES DROPPING BACK BELOW NORMAL TUESDAY
THROUGH THURSDAY AND SLIGHT CHANCE PRECIP EVENTS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 132 AM EST FRI NOV 21 2014

HIGH PRESSURE WILL PROVIDE MOSTLY CLEAR SKIES AND LIGHT WINDS THROUGH
THE MAJORITY OF THE FORECAST. SOME INCREASE IN HIGH CLOUD COVER WILL
MOVE IN LATE IN THE PERIOD OUT AHEAD OF THE NEXT APPROACHING SYSTEM.

&&

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

$$

UPDATE...GEOGERIAN
SHORT TERM...HAL
LONG TERM...DJ
AVIATION...GEOGERIAN





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