FXUS63 KPAH 231246
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
646 AM CST WED DEC 23 2009

.UPDATE...
UPDATED AVIATION SECTION FOR 12Z TAFS. NO CHANGE TO PUBLIC.

&&

.DISCUSSION...
POWERFUL SYSTEM WILL DEVELOP OVER THE MIDDLE OF THE COUNTRY BY THE 
CHRISTMAS HOLIDAY AS NRN AND SRN BRANCH UPPER LOWS MERGE OVER THE 
SOUTHERN AND CENTRAL PLAINS THU. IN RESPONSE...SFC LOW WILL DEVELOP 
AND TREK FROM OK UP INTO MO TONIGHT AND THURSDAY. SFC FRONT WILL 
SWING OUT AHEAD OF THIS FEATURE AND CROSS OUR FORECAST AREA LATER 
THU AND THU NIGHT. LOTS OF MID LEVEL DYNAMICS/UPWARD FORCING OUT 
AHEAD OF THE FRONT...AND EXPECT A RATHER EXTENSIVE BAND OF HEAVY 
RAINS WITH EMBEDDED THUNDERSTORMS TO SET UP TONIGHT ALONG A STRONG 
SOUTHERLY LOW LEVEL JET WHICH SHOULD SET UP OVER OUR SE MO COUNTIES. 
MEANWHILE...MAY BE LITTLE IF ANY OVER OUR EASTERN COUNTIES TONIGHT 
AS MOST OF THE FORCING WILL REMAIN FURTHER WEST. 

EXTENSIVE AREA OF SHOWERS WILL FINALLY COME ACROSS THE REMAINDER OF 
THE FORECAST AREA THU/THU EVENING AS THE FRONT PUSHES EAST. RAIN 
COULD BE HEAVY AT TIMES...BUT THINKING NOW IS THAT MOST AREAS CAN 
TAKE A BOUT OF HEAVY RAINFALL WITHOUT MUCH FLOODING IMPACT. 3 AND 6 
HR FLASH FLOOD GUIDANCE IS RUNNING CLOSE TO 3 INCHES MOST LOCATIONS. 
SE MO AND SW IL COUNTIES AMY FLIRT WITH THOSE AMOUNTS...BUT THINKING 
IT WOULD COME OVER MORE LIKE A 12 HOUR PERIOD. WILL HOLD OFF ON ANY 
FLOOD WATCHES AT THIS TIME. PROGGED K INDICES EXCEEDING 30 SUGGEST 
ENOUGH INSTABILITY ALOFT FOR A MENTION OF THUNDER OVER ALL EXCEPT SW 
IN AND EAST OF THE LAKES IN WRN KY.

OTHER IMPACT OF THIS SYSTEM MAY COME WITH STRONG SURFACE WINDS AHEAD 
OF THE FRONT THU...AND BEHIND THE FRONT ON CHRISTMAS. WINDS WILL BE 
ALIGNED IN THE VERTICAL...AND LIKELY 50 TO 70 MPH AT H85. BUFKIT 
SOUNDINGS OFF THE GFS STILL SUGGEST WIND GUSTS COULD EXCEED 45 MPH 
THU AND SUSTAINED WINDS COULD BE CLOSE TO 30 MPH IN SOME AREAS. MAY 
WARRANT A WIND ADVISORY IN LATER FORECASTS.    

STILL LOOKS AS THOUGH A HUGE DRY SLOT WILL NOSE IN ACROSS THE REGION 
FROM THE SW ON CHRISTMAS DAY...BEFORE WRAP AROUND MOISTURE IN THE 
UPPER LOW UP OVER IA TRIES TO ROTATE BACK IN FRI NIGHT AND INTO THE 
WEEKEND. WILL ALSO BE A TRANSITION BACK TO COLDER CONDITIONS FRI 
THRU SUN...BUT NO SIGNIFICANT PRECIP SHOULD OCCUR. WILL STICK CLOSE 
TO MEX MOS TEMPS.

&&

.AVIATION...
PATCHY LIGHT RAIN WILL CONTINUE THROUGH THE DAY...FOLLOWED BY A MORE 
WIDESPREAD AND HEAVIER RAIN TONIGHT. MAINLY VFR CONDITIONS ARE 
EXPECTED TODAY...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. LOWER 
CONDITIONS WILL VERY SLOWLY SPREAD EAST LATE THIS AFTERNOON AND 
TONIGHT. THE EXACT TIMING AND EXTENT OF THIS LOWERING WILL NEED 
ADJUSTMENT IN LATER FORECASTS. WINDS WILL SLOWLY INCREASE 
ALOFT...AND LOW LEVEL WIND SHEAR MAY BECOME AN ISSUE BY 12Z 
THURSDAY. 

&&

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

$$

DISCUSSION...MEFFERT
AVIATION...MY