FXUS63 KPAH 241150
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
549 AM CST THU DEC 24 2009

.UPDATE...
UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE. DISCUSSION SECTION IS 
UNCHANGED FROM THE 252 AM ISSUANCE.

&&

.DISCUSSION...
INTENSE UPPER LEVEL SHORTWAVE WILL ACQUIRE A STRONG NEGATIVE TILT AS 
IT MOVES NORTHEAST ACROSS OUR REGION THIS EVENING. ASSOCIATED 
SURFACE LOW WILL DEEPEN TO AROUND 990 MB AS IT TRACKS NORTH ACROSS 
EASTERN MISSOURI TONIGHT. THIS SYSTEM WILL BE ACCOMPANIED BY STRONG 
DEEP FORCING FOR ASCENT...RESULTING IN HEAVY RAINFALL. MOST GUIDANCE 
REMAINS IN GOOD AGREEMENT THAT AXIS OF HEAVIEST QPF WILL BE ACROSS 
SOUTHEAST MISSOURI...CLOSEST TO THE SURFACE LOW TRACK AND POSSIBLY 
AIDED BY OROGRAPHIC EFFECTS WITH EAST/SOUTHEAST FLOW ENCOUNTERING 
THE OZARK FOOTHILLS. LOCATION AND TIMING OF FLOOD WATCH LOOKS VERY 
GOOD. TOTAL RAINFALL STILL LOOKS ON THE ORDER OF A COUPLE OR THREE 
INCHES IN THE WATCH AREA...LOCALLY HIGHER IN THE HILLY TERRAIN OF SE 
MISSOURI.

AS FOR THE WIND THREAT...THERE WILL BE A STRONG LOW LEVEL FRONTAL 
INVERSION. DESPITE TREMENDOUS LOW LEVEL WIND FIELDS /80 KNOTS AT 850 
MB/...MIXING THIS WIND DOWN WILL BE DIFFICULT. GFS HAS BEEN 
INDICATING 40 KNOTS BARELY OFF THE SURFACE...SO EVEN THE WEAKEST 
MIXING CONDITIONS COULD STILL YIELD ADVISORY LEVEL WIND GUSTS. 
FOLLOWING THE PASSAGE OF THE OCCLUDED FRONT LATER TONIGHT...MIXING 
HEIGHTS WILL RISE RAPIDLY. HOWEVER...WIND FIELDS WILL BE DECREASING 
STEADILY. AS A RESULT...WIND GUSTS SHOULD BE MARGINAL FOR AN 
ADVISORY. COULD SEE A MESOSCALE TYPE WIND EVENT IMMEDIATELY BEHIND 
THE FRONT TONIGHT...BUT THIS IS TOUGH FOR MOST CONVENTIONAL MODELS 
TO PICK UP.   

ONCE THE OCCLUDED FRONT PASSES...COLDER AIR WILL RUSH IN LATER 
TONIGHT AND REMAIN THROUGH THE NEXT SEVERAL DAYS. THE UPPER LOW WILL 
BECOME QUASI STATIONARY OVER THE UPPER MISSISSIPPI VALLEY INTO THE 
WEEKEND. MODELS ARE INCREASINGLY SHOWING STRONGER IMPULSES ROTATING 
AROUND THE LOW...WHICH RESULT IN SOME SPOTTY QPF AND HIGHER MODEL 
POPS. DUE TO LIMITED MOISTURE AND MODEL DIFFERENCES IN THE STRENGTH 
AND TIMING OF THESE IMPULSES...FLURRIES OR A SLIGHT CHANCE OF LIGHT 
SNOW WILL BE FORECAST FRIDAY NIGHT THROUGH SUNDAY.

TEMPS WILL BE A BLEND OF GFS MOS AND SREF 2 METER TEMPS THROUGH 
CHRISTMAS NIGHT...THEN AT OR SLIGHTLY BELOW GFS MOS THIS WEEKEND.

AT LONGER RANGES...HIGH PRESSURE WILL MOVE EAST ACROSS THE REGION 
EARLY IN THE WEEK. A 500 MB SHORTWAVE OF PACIFIC ORIGIN WILL 
APPROACH FROM THE SOUTHWEST ABOUT MID WEEK. THIS SHORTWAVE WILL 
INCREASE CLOUDS...BUT FORECAST WILL BE KEPT DRY DUE TO CONCERNS 
ABOUT MOISTURE AVAILABILITY AND LACK OF LOW LEVEL FORCING.  

&&

.AVIATION...
EMPHASIZED THE FIRST 3-4 HOURS OF THE PERIOD FOR WIDESPREAD MVFR 
CONDITIONS IN MODERATE TO HEAVY RAINFALL. IFR CONDITIONS WILL BE 
VERY POSSIBLE IN THE WEST INCLUDING KCGI AND KPAH. THE MIDDLE PART 
OF THE DAY SHOULD SEE AN IMPROVEMENT...AS WE SHOULD BE BETWEEN WAVES 
OF PRECIPITATION WITH MVFR TO VFR CONDITIONS. 

IFR OR LOW MVFR CONDITIONS ARE EXPECTED WITH THE PRIMARY FRONTAL 
BAND OF RAINS WHICH WILL PASS THROUGH THE AREA FROM MID AFTERNOON IN 
THE FAR WEST THROUGH AROUND MIDNIGHT IN THE EAST. 

TRIED TO KEEP GUSTS IN REASONABLE CHECK THROUGH THE DAY...AND THEN 
HIT THEM HARDEST BEHIND THE FRONT TONIGHT...WHEN THE BOUNDARY/MIXED 
LAYER DEEPENS AND STRONGER WINDS WILL BE ABLE TO REACH THE GROUND.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
KY...WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR 
     BALLARD-CALDWELL-CALLOWAY-CARLISLE-CHRISTIAN-CRITTENDEN-
     DAVIESS-FULTON-GRAVES-HENDERSON-HICKMAN-HOPKINS-LIVINGSTON-
     LYON-MARSHALL-MCCRACKEN-MCLEAN-MUHLENBERG-TODD-TRIGG-UNION 
     KY-WEBSTER.

MO...FLOOD WATCH THROUGH THIS EVENING FOR BOLLINGER-BUTLER-CAPE 
     GIRARDEAU-CARTER-MISSISSIPPI-NEW MADRID-PERRY MO-RIPLEY-
     SCOTT-STODDARD-WAYNE MO.

     WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR 
     BOLLINGER-BUTLER-CAPE GIRARDEAU-CARTER-MISSISSIPPI-NEW 
     MADRID-PERRY MO-RIPLEY-SCOTT-STODDARD-WAYNE MO.

IL...FLOOD WATCH THROUGH THIS EVENING FOR ALEXANDER-EDWARDS-FRANKLIN-
     HAMILTON-JACKSON-JEFFERSON-JOHNSON-PERRY IL-PULASKI-SALINE-
     UNION IL-WABASH-WAYNE IL-WHITE-WILLIAMSON.

     WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR 
     ALEXANDER-EDWARDS-FRANKLIN-GALLATIN-HAMILTON-HARDIN-JACKSON-
     JEFFERSON-JOHNSON-MASSAC-PERRY IL-POPE-PULASKI-SALINE-UNION 
     IL-WABASH-WAYNE IL-WHITE-WILLIAMSON.

IN...WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR 
     GIBSON-PIKE-POSEY-SPENCER-VANDERBURGH-WARRICK.

&&

$$

PUBLIC...MY
AVIATION...DRS