FXUS63 KJKL 120810
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
310 AM EST SAT DEC 12 2009

.SHORT TERM.../TODAY THROUGH MONDAY/...UPDATED

SURFACE HIGH PRESSURE OVER THE MIDATLANTIC STATES WILL GIVE US ONE
MORE DRY DAY. HOWEVER...IT WILL DRIFT FURTHER EAST AND THE FLOW
AROUND IT WILL BRING WARM AIR ADVECTION. THE RESULTING BROAD AND DEEP
ISENTROPIC LIFT WILL BRING INCREASING CLOUDS LATE TODAY AND THIS
EVENING...WITH PRECIPITATION TO FOLLOW FOR TONIGHT. WITH SUCH A DRY
AIR MASS IN PLACE...STILL HAVE CONCERNS THAT A COMBINATION OF LIMITED
RADIATIONAL COOLING THIS EVENING FOLLOWED BY EVAPORATIONAL COOLING
COULD RESULT IN SOME SLEET OR FREEZING RAIN FOR A BRIEF TIME AT THE
ONSET OF PRECIP IN OUR NE COUNTIES. AFTER THIS...WARM AIR ADVECTION
WILL BRING A WARM-UP OVERNIGHT WITH ANY PRECIP GOING TO PLAIN RAIN.

MOISTURE WILL BECOME MORE SHALLOW BY SUNDAY MORNING AND THE CHANCE OF
MEASURABLE PRECIP WILL NOT BE AS HIGH AS TONIGHT. THE DEEPEST AND
LONGEST LINGERING MOISTURE WILL BE IN OUR EASTERN COUNTIES...GIVING
THAT AREA THE BEST SHOT AT PRECIP. FORECAST SOUNDINGS SUGGEST LOW
CLOUDS WILL HANG TOUGH BENEATH AN INVERSION FOR MOST OF THE DAY
SUNDAY. THINK THAT THIS WILL LIMIT OUR WARM-UP.

LOW CLOUDS ARE MORE LIKELY TO DEVELOP BREAKS SUNDAY NIGHT. AFTER A
PERIOD OF WET WEATHER...THIS COULD LEAD TO VALLEY FOG. CONFIDENCE IS
NOT VERY HIGH AT THIS TIME...SO WILL USE PATCHY FOG IN THE FORECAST.
WITH A STEEP INVERSION ON MONDAY MORNING AND JUST HIGH CLOUDS
ANTICIPATED...WE SHOULD SEE A SUBSTANTIAL WARM-UP DURING THE DAY.
TEMPS SHOULD BE WELL INTO THE 50S AND POSSIBLY TOUCHING 60.

.LONG TERM.../MONDAY NIGHT THROUGH FRIDAY/

COLD FRONT TO ARRIVE EARLY TUE. GFS/ECMWF/CANADIAN SHOW FAIR 
AGREEMENT ON TIMING AND EACH WITH LESS THAN 0.10 INCH QPF. GFS
HAS MOISTURE NO DEEPER THAN 800 MB BUT UPWARD MOTION IS A LITTLE 
BETTER THAN PREVIOUS RUNS AND BETTER COINCIDENT WITH THE MOISTURE 
AVAILABLE. SO VERY LIGHT RAIN WITH THIS EVENT LOOKS GOOD BUT KEPT 
PROBABILITY AT CHANCE AND MUCH TOO WARM FOR ANY PHASE OTHER THAN 
LIQUID PRECIPITATION.  

THEREAFTER THE LONGWAVE PATTERN AMPLIFIES FROM THIS FAST ZONAL FLOW 
TO TROUGH OVER EAST COAST. GFS ENSEMBLE SHOWS A FAIRLY WIDE SOLUTION 
AT THE END OF THE WEEK OVER SNOW POSSIBILITIES AND SOME INDICATE A 
LAKE EFFECT SNOW CONNECTION TO LAKE MI. THAT SCENARIO IS A MAJOR 
CHANGE FROM 00Z AND 06Z RUNS AND DIFFERENT STILL FROM ECMWF. BUT 
SOMETHING TO WATCH.

STUCK CLOSE TO MEX TEMPERATURES THOUGH ENSEMBLE 850 MB STANDARD 
DEVIATION BECOMES QUITE LARGE TOWARD THE LATTER HALF OF WEEK...WHICH 
JUST HIGHLIGHTS THAT A PATTERN CHANGE IS COMING.  

&&

.AVIATION.../06Z TO 06Z/

HIGH PRESSURE SLIDING OFF TO OUR EAST WILL CONTINUE TO PROVIDE VFR
CONDITIONS AND LIGHT SOUTHEASTERLY WINDS THROUGH THE PERIOD. HIGH
CLOUDS WILL MOVE INTO THE REGION DURING THE DAY TODAY WITH LOWER
CLOUDS ARRIVING LATE IN THE AFTERNOON AHEAD OF THE NEXT APPROACHING
SYSTEM. RAIN WILL BE OVERSPREADING THE AREA FROM SOUTHWEST TO
NORTHEAST TOWARD THE END OF THE PERIOD... BUT DRY ANTECEDENT
CONDITIONS SHOULD MEAN ANY PRECIP PRIOR TO 06Z WILL BE VERY LIGHT.
IT SHOULD ALSO BE AFTER 06Z BEFORE CIGS OR VSBYS FALL BELOW VFR
LEVELS.

&&

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

&&

$$
SHORT TERM...HAL
LONG TERM...GV
AVIATION...ABE