FXUS63 KJKL 031733
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1233 PM EST THU DEC 3 2009

.SHORT TERM.../THE REST OF TODAY/

NORTHWEST FLOW IN THE LOWER LAYERS... PROMOTING WEAK UPSLOPE FLOW...
IS KEEPING LOW CLOUDS AND -DZ IN THE FCST. DO NOT EXPECT TEMPS ANY
WARMER THAN CURRENT AND HAVE ANNOTATED FCST TO REPRESENT THIS. FCST
UPDATE HAS LOWERED MAX TEMPS A COUPLE DEG AND GRIDS NOTE NEARLY
CONSTANT TEMPS. MAY DROP A DEG OR TWO BY THIS AFTN. HAVE REMOVED
MORNING WORDING.

THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...

/TODAY THROUGH SATURDAY NIGHT/

DEEP LOW PRESSURE AND THE UPPER LEVEL LOW ARE PULLING AWAY QUICKLY.
MEASURABLE PRECIPITATION WILL BE GONE BEFORE 12Z...SO WILL ONLY
MENTION SOME DRIZZLE INTO TONIGHT...WITH ONGOING COLD AIR ADVECTION.
HIGHS WILL LIKELY BY AROUND 12Z...WITH STEADY OR SLOWLY FALLING
TEMPERATURES FOR THE REST OF THE DAY. HIGH PRESSURE WILL BUILD IN FOR
FRIDAY...HOWEVER PLENTY OF CLOUDS WILL LINGER ACROSS THE AREA WITH
WNW LOW LEVEL FLOW. 

THE NEXT SYSTEM OF INTEREST WILL APPROACH EARLY SATURDAY MORNING AS
A TROUGH AXIS SHIFTS EAST ACROSS THE AREA. THE MODELS HAVE ALL BEEN
CONSISTENTLY SHOWING LIGHT QPF FOR THE MAJORITY OF THE AREA DURING
THE DAY ON SATURDAY. COLD TEMPERATURES ALOFT WILL ALLOW THIS TO BE
ALL SNOW.

THE TIME HEIGHTS REVEAL A TIGHT GRADIENT FROM NORTHWEST TO SOUTHEAST
ON HOW QUICKLY THE COLUMN CAN SATURATE WHILE FORCING IS AVAILABLE.
HAVE BUMPED POPS UP TO GOOD CHANCE FOR THE SOUTHEASTERN TWO THIRDS OF
THE AREA. DESPITE THIS FALLING ALL AS SNOW...THE WINDOW OF SNOW LOOKS
TO BE FROM THE LATE MORNING HOURS THROUGH THE EARLY AFTERNOON...SO DO
NOT EXPECT MUCH ACCUMULATION ON THE ROADS. IN THE SOUTHEASTERN
TERRAIN...ESPECIALLY ABOVE 2500 FEET...THE IMPACT WILL BE GREATER
WITH TEMPERATURES LIKELY REMAINING BELOW FREEZING ALL DAY. COULD SEE
LOCATIONS PICKING UP AN INCH OR SO FOR THESE LOCATIONS. WILL
HIGHLIGHT THIS IN THE HWO. 

FORCING WILL END BY 00Z SUNDAY...WITH DECREASING CLOUDS AND A COLD
NIGHT DOWN INTO THE LOWER 20S EXPECTED.

FOR TEMPERATURES...GENERALLY STAYING COLDER THAN GUIDANCE ON
ON THE HIGHS...AND CLOSER ON THE LOWS...AS A DIURNALLY LIMITED RANGE
WORKS WELL IN COLD AIR ADVECTION.

.LONG TERM.../SUNDAY THROUGH WEDNESDAY/

IN GENERAL...THE MODELS ARE IN BETTER THAN AVERAGE AGREEMENT...WITH 
SLIGHT UPPER RIDGING AND SURFACE HIGH OVER THE OHIO VALLEY. BY 
MONDAY MORNING..THE SURFACE RIDGE BEGINS TO BE PUSHED TO THE EAST 
AND SOME RETURN FLOW AT THE SURFACE WILL BRING SOME WARMER AND 
MOISTER AIR INTO THE AREA AHEAD OF THE APPROACHING FRONT. A WEAK 
WARM FRONT WILL MOVE ACROSS THE AREA BY MONDAY AFTERNOON AND THEN A 
WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON MONDAY NIGHT. THE ECMWF 
IS NOW SHOWING A FAIRLY POTENT SYSTEM WITH A STRONG UPPER LOW WILL 
MOVE ACROSS THE AREA ON TUESDAY NIGHT AND WEDNESDAY. IN 
GENERAL...TRENDED TOWARD THE ECMWF AND USED SOME RAW MODEL DATA TO 
BLEND WITH THE GFS MOS. THE BIGGEST QUESTIONS WILL BE TEMPERATURES 
AS THE SYSTEMS MOVE ACROSS THE AREA. AT THIS TIME...DO NOT SEE AND 
LARGE SNOW PRODUCERS. THE BEST CHANCE FOR MEASURABLE SNOW WILL BE 
WITH THE POST FRONTAL PRECIPITATION ON THURSDAY.   

&&

.AVIATION.../18Z TO 18Z/...UPDATED

COLD AIR ADVECTION FROM THE NORTHWEST...COMBINED WITH UPSLOPE FLOW OF
MOISTURE IS KEEPING CLOUDS AROUND 800 TO 1500 FEET... AND A LITTLE
LOWER ON THE HILL AT JKL. THIS SHOULD CONTINUE THROUGH A GOOD PORTION
OF THE EARLY AFTERNOON... UNTIL SOME DRIER AIR CAN ADVECT INTO THE
REGION. TIMING ON THE BACK EDGE OF THE CLOUDS LOOKS TO BE AFTER
SUNSET BUT BEFORE MIDNIGHT. SOME COLD CU BUILDING BEHIND THE CURRENT
STRATOCU AND WILL HAVE TO WATCH THIS FOR LATER TONIGHT. UPSLOPE HAS
ALSO WRUNG SOME OF THE LIMITED MOISTURE IN THE FORM OF -DZ. CROSS
SECTION DOES NOT SHOW THIS MOISTURE TO BE VERY THICK AND SHOULD END
WITH THE ADVECTING DRIER AIR. IF THE COLD CU DOES NOT CONTINUE TO
DEVELOP AND WE CLEAR OUT TONIGHT... WILL HAVE TO UPDATE FOR DENSE
FOG. 

&&

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

&&

$$

SHORT TERM...GEOGERIAN/DUSTY
LONG TERM....JJ
AVIATION...DUSTY