FXUS63 KJKL 152240
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
540 PM EST TUE DEC 15 2009

.SHORT TERM.../TONIGHT THROUGH THURSDAY NIGHT/

AN UPPER LEVEL TROUGH AXIS IS SHIFTING ACROSS THE AREA AT
PRESENT...WITH THE AXIS EXTENDING SOUTH INTO THE OH VALLEY FROM A
TROUGH OVER EASTERN CANADA. RIDGING REMAINS ANCHORED SE OF FL AND
EXTENDS NORTH IN THE WESTERN ATLANTIC. UPPER LEVEL SHORTWAVE RIDGING
WAS OVER THE DESERT SW NE INTO THE NORTHERN ROCKIES. AT THE
SFC...STRONG HIGH PRESSURE OVER THE PLAINS WAS BUILDING INTO THE
LOWER OH AND TN VALLEY REGIONS BEHIND THE COLD FRONT ASSOCIATED WITH
THIS UPPER TROUGH. EXTENSIVE STRATOCU REMAINS ACROSS THE REGION FROM
NORTHERN IN SOUTH TO NEAR PAH.

THE OVER THE NEXT FEW DAY...THE UPPER LEVEL TROUGH AND THE COLDEST OF
THE AIR AT 850 MB WILL PASS THROUGH THE AREA BY AROUND 6Z....WITH
UPPER LEVEL HEIGHTS RISING THROUGH AT LEAST MIDDAY ON WED. AT THE
SAME TIME THE SFC HIGH WILL SETTLE INTO THE OH VALLEY ON WED...WITH
THE AXIS OF THE HEIGHT GRADUALLY MOVING TO THE EAST OF THE AREA BY THE
END OF THE PERIOD. AT THE SAME TIME...THE SOUTHERN END OF THE ABOVE
NAMED TROUGH WILL GRADUALLY MOVE ACROSS TX AND LEAD TO A SFC LOW
DEVELOPING OVER THE GULF COAST REGION WED/THU WITH THIS LOW TRACKING
ACROSS THE NORTHERN GULF OF MEXICO REGION LATE. ALSO...AT THE END OF
THE PERIOD...AN UPPER LEVEL TROUGH WILL BEGIN TO APPROACH THE AREA
WITH UPPER LEVEL SHORTWAVE RIDGING ANTICIPATED. 

THE STRATOCU SHOULD BE A BIT SLOW TO EXIT BASED ON CURRENT SAT
TRENDS. IN FACT...WE MAY MAKE A LAST MINUTE DECISION ON WHETHER OR
NOT TO RAISE SKY COVER FOR A FEW HOURS IN THE EVENING. HOWEVER...BY
6Z...SCATTERING OUT SHOULD BE OCCURRING AND WITH A PRESS GRADIENT
GRADUALLY SLACKENING BY LATE...TEMPS SHOULD DROP OFF...ESPECIALLY
LATE IN ADDITION TO THE ADVECTION. IN GENERAL...WENT WITH TEMPS CLOSE
TO PERSISTENCE OR CLOSEST TO THE COLDEST GUIDANCE.

MOS AND MODEL GUIDANCE INDICATES DRY ADVECTION LEADING TO DEWPOINTS
DROPPING INTO THE TEENS TONIGHT AND POSSIBLY BELOW 10 ON WED. THIS
DRYING OUT APPEARS REASONABLE GIVEN UPSTREAM OBS OVER IL AND IN.
OPTED TO LOWER DEWPOINTS A BIT LATER TONIGHT AND ESPECIALLY 18Z WED
THROUGH WED NIGHT. THE AIRMASS WILL MODERATE A BIT ON WED FROM HOW
COLD IT WILL BE TONIGHT...BUT NORTHERN AND EASTERN LOCATIONS SHOULD
BE THE COLDEST...POSSIBLY NOT GETTING OUT OF THE 30S...WITH LOW TO
MID 40S IN THE SW. THE PATTERN OF THE SFC HIGH PRESSURE GRADUALLY
SHIFTING EAST OF THE AREA ON WED NIGHT SHOULD LEAD TO A RIDGE/VALLEY
SPLIT. THERE WILL BE SOME MAINLY CIRRUS CLOUDS FROM TIME TO
TIME...WED AND WED NIGHT BUT THIS SHOULD NOT SLOW DOWN RADIATIONAL
COOLING MUCH. BOTH THE MAV AND MET ARE 19 FOR HTS...AND FEEL THAT
EASTERN VALLEY LOCATIONS SHOULD BE COLDER THAN THAT GIVEN EXPECTED
DEWPOINTS AND CERTAINLY COLDER THAN COOP MOS VALUES.

FURTHER WARM ADVECTION WILL LEAD TO WARMING ON THU. TIME HEIGHT
SECTIONS INDICATE SOME MID AND HIGH CLOUDS FROM TIME TO TIME ON THU
AS WELL. WITH THE BRIEF UPPER LEVEL RIDGING AND MAINLY HIGH CLOUDS
ANTICIPATED...ANOTHER RIDGE/VALLEY SPLIT IS ANTICIPATED FOR THU NIGHT
AS WELL. 

.LONG TERM.../FRIDAY THROUGH TUESDAY/

THERE IS GENERAL MODEL AGREEMENT WITH DOMINATING THE EASTERN HALF OF 
THE CONUS WITH TROUGHINESS...YIELDING WELL BELOW NORMAL TEMPERATURES 
AND OCCASIONAL SNOW SHOWERS FOR EASTERN KENTUCKY. DETAILS ON THE 
TIMING OF SHORT WAVE ENERGY WILL BE DIFFICULT...SO HAVE MAINTAINED 
SLIGHT CHANCE TO CHANCE POPS THROUGHOUT THE PERIOD...WITH THE 
HIGHEST POPS CENTERED AROUND SATURDAY...WITH GOOD AGREEMENT ON 
SWINGING A TROUGH AXIS THROUGH THE AREA. COULD SEE AROUND AN INCH OF 
SNOW...WITH PERHAPS UP TO 2 INCHES ON THE HIGHEST TERRAIN IN THE 
SOUTHEAST IF THE QPF HOLDS. STAYED ON THE COOL SIDE OF MOS GUIDANCE 
FOR THE HIGHS...AND CLOSE FOR THE LOWS WITH THE COLD AIR MASS IN 
PLACE...MOSTLY CLOUDY SKIES AND SOME SNOW FLYING AT TIMES. 

&&

.AVIATION.../00Z TO 24Z/...UPDATED

MVFR STRATOCU SHOULD LINGER INTO THE EVENING...THOUGH THESE SHOULD
SCATTER OUT AS UPPER AND SFC HIGH PRESSURE ADVECT DRIER AIR INTO THE
REGION. WITH THIS IN MIND...HAVE TRENDED OUT THE MVFR CIGS BETWEEN 0Z
AND 5Z FROM WEST TO SE. AT THIS TIME...SCATTERING OUT IS EXPECTED AT
THE TAF SITES ABOUT 3Z TO 4Z. CLEARING COULD TAKE A LITTLE LONGER IN
THE SE AS THE NW WINDS PUSH THE LOW LEVEL MOISTURE UP AGAINST THE
MOUNTAINS. AFTER THIS VFR WILL PREVAIL THROUGH THE END OF THE PERIOD.
WINDS WILL SLACKEN...ESPECIALLY 6Z TO 12Z AS THE HIGH GETS CLOSER TO
THE REGION AND THE PRESS GRADIENT SLACKENS.

&&

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

&&

$$

SHORT TERM...JP
LONG TERM....GEOGERIAN
AVIATION...DUSTY