Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 181053
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
653 AM EDT FRI APR 18 2014

.UPDATE...
ISSUED AT 653 AM EDT FRI APR 18 2014

MID/HIGH CLOUDS HAVE CONTINUED TO THICKEN EARLY THIS MORNING. HAVE
INCREASED CLOUD COVER IN THE FORECAST FOR THE MORNING HOURS. WITH
THICKER CLOUDS TO PREVENT RADIATING...TEMPERATURES IN THE COLDER
VALLEY HAVE CREPT HIGHER...AND HAVE ACCOUNTED FOR THIS TREND IN THE
HOURLY TEMPERATURE GRIDS.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 336 AM EDT FRI APR 18 2014

DURING THE NIGHT...A MID/UPPER LEVEL TROUGH AND A DYING SURFACE COLD
FRONT WAS WERE APPROACHING THE REGION FROM THE WEST AND NORTHWEST
RESPECTIVELY. THE MOST SIGNIFICANT PORTION OF THE TROUGH WAS HEADING
TOWARD THE GULF COAST REGION AND WAS TRIGGERING SURFACE LOW
DEVELOPMENT THERE. AN EXTENSIVE CIRRUS SHIELD EXTENDED NORTH TO THE
OHIO VALLEY.

THE COLD FRONT SHOULD DEGRADE TO AN INVERTED TROUGH ASSOCIATED WITH
THE SOUTHERN LOW AND WILL NOT BRING ANY SIGNIFICANT CHANGE IN AIR
MASS. THE SOUTHERN LOW WILL PROGRESS SLOWLY TO THE ENE THROUGH
SATURDAY. WE WILL REMAIN AT THE NW PERIPHERY OF ITS INFLUENCE. OUR
LOW LEVEL AIR MASS IS NOT EXPECTED TO MOISTEN ENOUGH TO ALLOW FOR
PRECIP. HOWEVER...EXTENSIVE CLOUDS WILL BE PRESENT THIS MORNING. THE
CLOUD SHIELD IS EXPECTED TO SHOW AN OVERALL SHIFT TO THE SE WITH
TIME...EVENTUALLY ALLOWING FOR SUNNY TO PARTLY SUNNY SKIES OVER THE
LOCAL AREA ON SATURDAY.

WITH THE CLOUDS BEING MOSTLY CIRRUS TODAY...WILL LOOK FOR ENOUGH
INSOLATION FOR MILD AFTERNOON TEMPS AROUND 70. HOWEVER...THIS WILL BE
DEPENDENT ON THE THICKNESS OF THE CLOUDS. IF THE CLOUDS ARE DENSE
ENOUGH...IT COULD HOLD TEMPS DOWN...WHICH LOWERS CONFIDENCE IN THE
TEMPERATURE FORECAST FOR TODAY.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM EDT FRI APR 18 2014

DECENT AGREEMENT BETWEEN THE MODELS IN THE EXTENDED. THE OVERALL
LARGE SCALE WILL FEATURE A LARGE RIDGE OF HIGH PRESSURE PARKED OVER
THE EASTERN CONUS DURING THE LATTER HALF OF THE WEEKEND. WITH PLENTY
OF WARM DRY AIR IN PLACE WE SHOULD SEE MOSTLY CLEAR SKIES...LIGHT
WINDS...AND ABOVE NORMAL TEMPERATURES ACROSS THE AREA SATURDAY NIGHT
THROUGH MOST OF THE DAY ON MONDAY. BY MONDAY EVENING...HOWEVER...IS
WHERE THE PATTERN BEGINS SHIFTING...AS A TROUGH OF LOW PRESSURE
EJECTS OUT OF THE PLAINS AND ACROSS THE OHIO AND TENNESSEE VALLEY
REGIONS. A COLD FRONT TRAILING FROM THE ATTENDANT SURFACE LOW WOULD
BE OUR WEATHER PRODUCER MONDAY NIGHT AND TUESDAY...SHOULD THE MODELS
TURN OUT TO BE RIGHT. INITIALLY THERE WERE SOME TIMING DIFFERENCES
BETWEEN THE ECMWF AND GFS WITH THIS SYSTEM...BUT THE TWO MODELS
QUICKLY CAME INTO AGREEMENT. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WOULD THE WEATHER FEATURES OF NOTE ALONG AND AHEAD OF
THE ADVANCING FRONT TO BEGIN THE WEEK. WITH MEAGER INSTABILITY AND
FAIRLY WEAK UPPER LEVEL DYNAMICS...NOTHING MORE THAN GARDEN VARIETY
THUNDERSTORMS ARE EXPECTED WITH THE FRONT. ONCE THE FRONT MOVES
THROUGH...A SLIGHTLY DRIER AIR MASS IS PROGGED TO SETTLE OVER THE
ARE THROUGH THE END OF THE WEEK.

TEMPERATURES ARE EXPECTED TO BE A BIT ABOVE NORMAL TO BEGIN THE
PERIOD...WITH STRONG HIGH PRESSURE IN PLACE AND DRY AIR SPILLING
INTO THE AREA. STRONG SUBSIDENCE ALOFT WILL BE THE PRIMARY MECHANISM
BY WHICH OUR TEMPERATURES WARM AS THEY ARE EXPECTED TO SUNDAY AND
MONDAY. IN GENERAL...DAYTIME HIGHS SUNDAY AND MONDAY COULD TOP OUT
IN THE MID TO POSSIBLY UPPER 70S DEPENDING ON HOW MUCH WIND AND
CLOUDS WE END UP GETTING. THE PASSAGE OF THE COLD FRONT WILL LIKELY
NOT COOL THING OFF VERY MUCH AS IT LOOKS TO BE AN ILL DEFINED
BOUNDARY WILL LITTLE CHANGE IN AIR MASS AS IT PASSES BY. HIGHS
TUESDAY AND WEDNESDAY WILL STILL PROBABLY TOP OUT AROUND 70 EACH
DAY. THE AIR MASS IS THEN EXPECTED TO QUICKLY MODIFY TOWARD THE END
OF THE WEEK...WITH HIGHS AGAIN POSSIBLY RISING INTO THE MID 70S
ACROSS THE AREA ON THURSDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 653 AM EDT FRI APR 18 2014

VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL THROUGH THE PERIOD.

&&

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

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...AR
AVIATION...HAL





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