FXUS63 KPAH 120856
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
256 AM CST SAT DEC 12 2009

.DISCUSSION...
BIGGEST CHALLENGES WITH THIS PACKAGE WILL BE POP COVERAGE WITH THE
SYSTEM AFFECTING THE REGION THIS AFTERNOON INTO SUNDAY
MORNING..AND THEN A SECOND SYSTEM MONDAY INTO MODAY NIGHT.

THE LARGE AREA OF ARCTIC HIGH PRESSURE THAT HAS PROVIDED PLENTY OF
SHUNSHINE FOR THE PAST COUPLE OF DAYS HAS MOVED TO THE EAST OF THE
REGION. AS A RESULT...SOUTH TO SOUTHWEST FLOW IN THE LOWER LEVELS
WILL CONTINUE TO ADVECT MOISTURE AND WARMER AIR INTO THE AREA. A
5-6K FT DECK OF CLOUDS STREAMING ACROSS OUR CWA FORMED AS A RESULT
OF ISENTROPIC UPGLIDE ON THE 290K SURFACE COUPLED WITH THE
AFOREMENTIONED MOISTURE. MODELS DONT INDICATE THE ATMOSPHERE
SATURATING DOWN TO THE SURFACE UNTIL THIS AFTERNOON...SO KEPT IT
DRY THIS MORNING.

THIS AFTERNOON THE COMBINATION OF THE SATURATION OF THE LOWEST
LEVELS...INCREASING ISENTROPIC UPGLIDE ON THE 290K AND 295K SURFACES...AND
FRONTOGENETICAL FORCING IN THE 850-700MB LAYER...PRECIP SHOULD
SPREAD QUICKLY INTO THE REGION...WITH THE BEST CHANCES BEING OVER
THE OVER THE SOUTHERN SECTIONS.

BUMPED UP POPS THIS EVENING (00-06Z)...ESPECIALLY OVER THE NORTHERN AND
NORTHWEST SECTIONS AS AN AREA OF MID LEVEL LIFT (UVV) AND MAXIMUM
ISENTROPIC UPGLIDE ON THE 295K SURFACE COMES TOGETHER OVER OUR
REGION. THE GFS AND GFS ENSEMBLE MEAN KEEP THE PRECIP CHANCES BEST
OVER THE SOUTHEAST SECTIONS WITH POPS TAPERING OFF TO THE NORTH
AND WEST...BUT THE NAM 80/12 SHOW THE MID LEVEL LIFT TRACKING A
BIT FARTHER NORTH AND WEST. WITH THAT IN MIND AND TO BETTER
COORDINATE WITH THE NEIGHBORS...BUMPED UP POPS CONSIDERABLY NORTH
AND WEST FOR THIS EVENING.

AFTER MIDNIGHT TONIGHT (06-12Z) WITH DECENT MOISTURE AND
ISENTROPIC UPGLIDE ON THE 295K SURFACE OVER THE SOUTHEAST
SECTIONS...BUMPED UP POPS TO LIKELY THERE. KEPT SCHC TO CHC POPS
ELSEWHERE. WITH MOISTURE LINGERING OVER THE EASTERN THIRD OF THE
REGION SUNDAY MORNING...KEPT SCHC POPS GOING THERE. WITH STILL
PLENTY OF 1000-850MB MOISTURE ACROSS THE ENTIRE REGION...KEPT
PATCHY DRIZZLE ELSEWHERE.

AFTER A BRIEF RESPITE...ANOTHER SYSTEM WILL BEGIN TO AFFECT THE
REGION MONDAY. WITH IT COMING SUCH A SHORT TIME AFTER THE FIRST
SYSTEM...THIS SYSTEM WILL BE SOMEWHAT MOISTURE STARVED. AS A
RESULT...POP CHANCES ON MONDAY WILL BE MINIMAL. LOW LEVEL MOISTURE
AND SYSTEM DYNAMICS BEGIN TO COME INTO PHASE AS THE SYSTEM REACHES
OUR EASTERN SECTIONS...SO WITH THE EXCEPTION OF OUR NORTHERN AND
WESTERN SECTIONS...THE HIGHEST POPS WITH THIS SYSTEM WILL BE
MONDAY EVENING. AFTER MIDNIGHT MOISTURE AND DYNAMICS MOVE QUITE A
BIT EAST...SO JUST LINGERED SCHC POPS OVER THE EXTREME SOUTHEAST
SECTIONS.

&&

.AVIATION...
MID LEVEL VFR CLOUDS...CEILINGS 6-8KFT...WILL CONTINUE TO SPREAD 
ACROSS THE REGION THIS MORNING. SOME BREAKS ARE POSSIBLE EARLY 
TODAY...BUT THE SKY SHOULD BE SHROUDED IN CLOUDINESS MOST OF THE 
DAY. THE APPROACH OF AN UPPER LEVEL WAVE WILL BRING LIGHT RAIN TO 
THE REGION LATE THIS AFTERNOON INTO TONIGHT...WITH A RAPID 
DETERIORATION TO MVFR AND IFR CEILINGS WITHIN A FEW HOURS OF 
PRECIPITATION ONSET. LIGHT WINDS THE REST OF TONIGHT WILL PICK UP 
FROM THE SOUTH/SOUTHEAST AROUND 10 KNOTS THROUGH THE REST OF THE 
FORECAST PERIOD.

&&

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

$$

AVIATION...CW
PUBLIC.....JP