FXUS63 KLSX 040553
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1153 PM CST THU DEC 3 2009

.UPDATE...
/905 PM CST THU DEC 3 2009/

UPDATED FORECAST TO LOWER MINIMUM TEMPERATURES TONIGHT AND MAX
TEMPERATURES TOMORROW. 00Z 850MB ANALYSIS INDICATES TEMPERATURES
WELL BELOW -10C UPSTREAM...WHICH TRANSLATES TO AFTERNOON SURFACE
TEMPERATURES IN THE UPPER 20S TO PERHAPS AROUND FREEZING. FURTHER
DOWNWARD ADJUSTMENT MAY BE NEEDED BY MIDSHIFT ACROSS THE NORTH
WHERE MORE CLOUD COVER WILL LIMIT INSOLATION.

CVKING

&&

.DISCUSSION...
/208 PM CST THU DEC 3 2009/

SECONDARY SHORTWAVE DROPPING SOUTHEASTWARD ACROSS IOWA AND NORTHERN 
IL THIS AFTERNOON. SO SEEING PLENTY OF DIURNAL SC DEVELOPING OVER 
THE REGION TODAY...THAT COMBINED WITH CAA IS KEEPING TEMPS FROM 
RISING MUCH. MAIN FORECAST ISSUES IN THE SHORT TERM WILL BE THESE 
CLOUDS...POSSIBLE FLURRIES AND COLD TEMPS.

FOR TONIGHT...WILL SEE CLOUDS LINGER...ESPECIALLY OVER NORTHEAST MO 
AND WEST CENTRAL IL...WITH FLURRIES POSSIBLE IN THIS AREA. AS FOR 
TEMPS...STRONG CAA TO CONTINUE TO MAKE ITS WAY INTO THE REGION WITH 
850 TEMPS DIPPING TO AROUND MINUS 14 BY MIDDAY ON FRIDAY. LOWS 
TONIGHT WILL BE THE COLDEST OF THE YEAR SO FAR...IN THE UPPER TEENS 
TO LOW 20S. HIGHS ON FRIDAY WILL ONLY RISE INTO THE LOW TO MID 30S.

BY FRIDAY NIGHT...RIDGE OF HIGH PRESSURE TO BEGIN MOVING OFF TO OUR 
EAST...ALLOWING SOUTHERLY WINDS TO RETURN ONCE AGAIN. SO WILL SEE 
TEMPERATURES MODERATE OVER THE WEEKEND WITH HIGHS IN THE UPPER 30S 
TO LOWER 40S SATURDAY AND SUNDAY. DO EXPECT SOME LIGHT PRECIPITATION 
BY SUNDAY NIGHT AS A COLD FRONT QUICKLY SLIDES THROUGH THE REGION. 
SINCE TEMPS WILL BE AT OR BELOW FREEZING...ANY RAIN THAT FALLS WILL 
MIX WITH THEN CHANGE OVER TO LIGHT SNOW. QPF AMOUNTS WILL BE LIGHT 
WITH THIS SYSTEM...SO DO NOT EXPECT ANY ACCUMULATIONS WITH IT.

BEYOND THAT...WILL SEE A BIT OF A BREAK ON MONDAY THEN MODELS 
CONTINUE TO INDICATE ANOTHER SYSTEM APPROACHING THE REGION FROM THE 
SOUTHWESTERN U.S. LATER IN THE DAY ON MONDAY...WITH BEST CHANCES OF 
PRECIPITATION TUESDAY THROUGH WEDNESDAY. THE PRECIPITATION WILL BE A 
MIXTURE OF LIGHT RAIN AND SNOW AT TIMES...AS DAYTIME TEMPS WILL BE 
IN THE LOW 30S TO LOWER 40S TUESDAY AND IN THE 30S ON WEDNESDAY AND 
MAIN SYSTEM STAYS TO THE SOUTH OF THE AREA. STILL NOT CONFIDENT ON 
EXACT TIMING AND LOCATION OF SYSTEM...SO KEPT POPS IN THE CHANCE 
CATEGORY FOR NOW. ALL MODELS QUICKLY MOVE THIS SYSTEM OUT BY 
WEDNESDAY NIGHT WITH DRY WEATHER FOR THE REMAINDER OF THE EXTENDED.

BYRD

&&

.AVIATION...
/1136 PM CST THU DEC 3 2009/

FOR THE 06Z TAFS...
VFR CIGS AROUND 3500-4000FT CONTINUE TO SPREAD SLOWLY SOUTHEAST
INTO THE BI-STATE REGION. AM UNCERTAIN HOW FAR SOUTH THEY WILL
MAKE IT...PERHAPS NOT GOING ANY FURTHER SOUTH THAN THE MISSOURI
RIVER...AND IT SEEMS LIKE THE CLOUDS ARE HAVING TROUBLE MAKING
INROADS INTO EAST CENTRAL MISSOURI AND SOUTHWEST ILLINOIS. ONE WAY
OR ANOTHER...THE CIGS SHUD STAY AOA 3000FT TONIGHT...SO THERE
WON'T BE MUCH OPERATIONAL IMPACT.

CARNEY

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&

$$

WFO LSX