FXUS63 KPAH 262133
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
333 PM CST SAT DEC 26 2009

.SHORT TERM...
WATER VAPOR IMAGERY INDICATED A PROUNCED DRY SLOT OVER THE PAH FCST 
AREA ALL THE WAY UP THE OH RIVER VALLEY. THIS HELPED TO LIMIT THE 
DEPTH OF THE MOISTURE THROUGH THE ATMOSPHERIC COLUMN TODAY. AS A 
RESULT...TEMPS IN SOME AREAS SUCH AS THE PENNYRILE REGION OF KY GOT 
INTO THE LOWER AND MIDDLE 40S WHERE CLOUD COVER WAS VIRTUALLY 
NON-EXISTENT. CLOUDS WERE RATHER THIN FARTHER NORTH.

THE PERSISTENT UPPER MIDWEST CLOSED/STACKED LOW IS EXPECTED TO THROW 
OUT A COUPLE OF LOBES OF ENERGY OUR WAY OVER THE WEEKEND. THE FIRST 
ONE WILL BE TONIGHT...CREATING ONLY A SLGT CHC OF MEASURABLE 
SNOWFALL FOR ROUGHLY THE NRN THIRD OF THE PAH FCST AREA. ON 
SUNDAY...THE SECOND...MORE SIGNIFICANT LOBE OF ENERGY SHOULD RESULT 
IN A DECENT CHC OF MEASUREABLE SNOW FOR ROUGHLY THE NRN HALF OF THE 
REGION...WITH AT LEAST A HALF INCH POSSIBLE FOR THE INTERSTATE 64 
CORRIDOR DURING THE DAY. THE NAM WAS FAVORED FOR THE NEAR TERM FCST 
DUE TO ITS SEEMINGLY BETTER INITIALIZATION. NAM SOUNDINGS INDICATED 
ENOUGH MOISTURE IN THE ICE NUCLEATION REGION FOR THIS TO HAPPEN. 
FLURRIES MAY LINGER SUNDAY EVE AS THE LOW BEGINS TO ACCELERATE AWAY 
FROM THE REGION. A 100+KT JET BETWEEN A WRN CANADIAN MID LEVEL RIDGE 
AND A HUDSON BAY LOW IS PROGGED BY THE MODELS TO KICK THE UPPER 
MIDWEST LOW EAST. IT SHOULD PHASE WITH THE HUDSON BAY LOW...FORMING 
MORE OF A MID/UPPER LEVEL TROF. DRY NWRLY FLOW ALOFT AND HIGH SFC 
PRESSURE IS EXPECTED TO KICK IN OVER THE FCST AREA LATE MON. THE NAM 
NUMERICAL GUIDANCE WAS GIVEN MORE WEIGHT THAN THE GENERALLY WARMER 
GFS FOR THE NEAR-TERM TEMPS/DEWPOINTS. 

.LONG TERM...
/TUESDAY THROUGH NEXT SUNDAY/
MAIN CHANGE TO THIS PACKAGE WAS TO SLOW DOWN THE ONSET OF
PRECIPITATION TUESDAY NIGHT...AS IT WILL TAKE A LITTLE MORE TIME
TO SATURATE THE LOWER LEVELS...AS LOW LEVEL THICKNESSES INCREASE
ALONG A DEVELOPING WSW-ENE SURFACE DEVELOPS ACROSS AR AND TN.

THE ECMWF/NAM-WRF ARE MORE ROBUST WITH ISENTROPIC LIFT ALONG A
INTERMITTENT WARM CONVEYOR BELT WEDNESDAY/THURSDAY...WITH BETTER
SATURATION THAN THE GFS. HOWEVER...GIVEN THE DISORGANIZED AND
DISRUPTED W/SWLY FLOW ALOFT...LEFT THE BEST CHANCE OF
PRECIPITATION IN A LOW CHANCE CATEGORY. GIVEN THE RELATIVELY
COOLER THICKNESSES EARLY ON...LEFT A MIX OF PRECIPITATION OF PART
OF THE DAYTIME PERIOD...BEFORE CHANGING EITHER TO RAIN DURING THE
REMAINDER OF THE DAY...OR SNOW AT NIGHT. WHATEVER THE OUTCOME OF
PRECIPITATION TYPES...AMOUNTS WILL BE MARGINAL AS THE MOST
SIGNIFICANT LOW LEVEL MOISTURE AND CONVERGENCE WILL REMAIN ACROSS
THE GULF STATES. 

&&

.AVIATION...
SOUTHWARD INCREASE IN COVERAGE OF VFR CEILINGS THROUGH 00Z SUNDAY
FOR ALL TAF SITES...ALTHOUGH THE SCATTERED VERSUS BROKEN COVERAGE
MAY BE SLOWED SLIGHTLY AT KPAH/KOWB THAN CURRENTLY FORECAST.
SOUTHWEST SURFACE SUSTAINED SURFACE WIND AND GUSTS SHOULD
GRADUALLY DECREASE THROUGH THE REST OF THE AFTERNOON AS THE
MECHANICAL MIXING DUE SUNSHINE /INSOLATION/ WANES OVER EACH OF
THE TAF SITES.

SCATTERED TO BROKEN MVFR CEILINGS BETWEEN 2-2.5KFT AGL WILL MOVE
OVER THE KCGI/KEVV SITES FIRST BETWEEN 04-08Z...GRADUALLY MOVING
TO THE KPAH/KOWB SITES BETWEEN 08Z-12Z. INTERMITTENT VFR
VISIBILITY RESTRICTIONS WILL BE LIKELY AFTER 10Z OVER EACH OF THE
TAF SITES...AS MINOR IMPULSE MOVES ACROSS THE AREA AHEAD A SURFACE
COLD FRONT SUNDAY AFTERNOON.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&

$$

SHORT TERM/FIRE WEATHER...DB
AVIATION/LONG TERM/FIRE WEATHER...SMITH