383  
FXUS63 KLSX 110340  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
1040 PM CDT THU OCT 10 2024  
   
KEY MESSAGES  
 
- ABOVE NORMAL TEMPERATURES IN THE 80S WILL CONTINUE INTO SATURDAY.  
 
- A DRY COLD FRONT WILL TREK ACROSS THE REGION ON SUNDAY AND BRING  
A MUCH COLDER AIR INTO THE REGION NEXT WEEK. FROST IS LIKELY  
TUESDAY AND WEDNESDAY MORNINGS WITH THE POTENTIAL FOR MORE  
SHELTERED LOCATIONS TO SEE THEIR FIRST FREEZE OF THE SEASON.  
 
 
   
SHORT TERM  
(THROUGH SATURDAY)  
ISSUED AT 241 PM CDT THU OCT 10 2024  
 
DEPARTING SURFACE HIGH PRESSURE AND WEAK FORCING ALOFT WILL CONTINUE  
TO BE THE MAIN CATALYST FOR OUR DRY WEATHER AND ABOVE NORMAL  
TEMPERATURES THROUGH SATURDAY. WITH ANOTHER DAY OF CUMULATIVE  
INSOLATION, TEMPERATURES TODAY ARE A FEW DEGREES WARMER THAN  
YESTERDAY. FRIDAY'S HIGH TEMPERATURES WILL BE A FEW DEGREES WARMER  
THEN TODAY AS SURFACE HIGH BEGINS TO SHIFT TO THE SOUTHEAST,  
PROMOTING SOUTHWESTERLY LOW-LEVEL FLOW AND WARM AIR ADVECTION INTO  
SATURDAY. MEAN ENSEMBLE 850-MB TEMPERATURES (APPROXIMATELY 18C) ON  
SATURDAY CONTINUE TO TREND ABOVE THE 90TH PERCENTILE OF CLIMATOLOGY.  
SHOULD WE MIX OUT UP TO 850-MB, WE ARE NEAR RECORD DAILY HIGH  
TEMPERATURES AT KSTL (89F) AND KUIN (88F)(SEE CLIMATE SECTION).  
HOWEVER, CURRENT GUIDANCE IS INDICATING AN INCREASE IN HIGH CLOUDS  
ON SATURDAY AS WELL AS A WEAK STATIONARY FRONT ACROSS THE NORTHERN  
MOST PARTS OF THE CWA. EITHER OF THESE TWO THINGS COULD LIMIT HOW  
WARM WE GET ON SATURDAY.  
 
MMG/PFAHLER  
 
 
   
LONG TERM  
(SUNDAY THROUGH NEXT THURSDAY)  
ISSUED AT 241 PM CDT THU OCT 10 2024  
 
THERE REMAINS CONSENSUS AMONG ENSEMBLE GUIDANCE THAT AN UPPER-LEVEL  
TROUGH WILL BEGIN DIGGING ACROSS THE UPPER MIDWEST AND PUSH A STRONG  
COLD FRONT ACROSS THE REGION SUNDAY MORNING. THERE IS SOME  
UNCERTAINTY AS TO HOW QUICKLY THE POST-FRONTAL COLDER AIRMASS MAKES  
IT INTO THE REGION, ULTIMATELY AFFECTING SUNDAY'S HIGH TEMPERATURES  
AND THIS IS REFLECTED IN A 7 DEGREE SPREAD IN THE NBM INTERQUARTILE  
RANGE. THE CURRENT FORECAST SUPPORTS THE COLDER AIR ARRIVING TO THE  
NORTHERN HALF OF THE CWA BY SUNDAY AFTERNOON. THE COLD FRONT IS  
EXPECTED TO BE DRY WITH THE GREATEST UPPER-LEVEL SUPPORT AND  
MOISTURE REMAINING TO OUR NORTHEAST.  
 
THE INITIAL BRUNT OF THE COLDER AIRMASS WILL BE FELT ON MONDAY  
WITH MUCH COOLER TEMPERATURES BUT THE PRIMARY QUESTIONS ARE COOL  
WE GET AT NIGHT AND HOW LONG THE COOLER TEMPERATURES WILL STAY.  
SHOULD THE CORE OF THE COLDER AIRMASS (SURFACE HIGH PRESSURE) BE  
CENTERED OVER THE REGION DURING THE NIGHTTIME HOURS, WE CAN EXPECT  
THE COLDEST LOW TEMPERATURES TUESDAY AND WEDNESDAY MORNINGS.  
CURRENT NBM PROBABILITIES OF <=32F ARE 50-60% IN MISSOURI WHICH  
WOULD SUPPORT A FREEZE, WHEREAS PROBABILITIES OF <=36 ARE UP TO  
75% AREA WIDE. TEMPERATURES <=36F WOULD BRING CHANCES OF  
WIDESPREAD FROST. ANOTHER UNCERTAINTY IS HOW LONG THE SURFACE HIGH  
REMAINS IN PLACE OVER US BEFORE SHIFTING EAST AND LOW-LEVEL  
SOUTHERLY FLOW RETURNS. CURRENT DETERMINISTIC GUIDANCE MEMBERS ARE  
IN AGREEMENT THAT THE SURFACE HIGH WILL BE IN PLACE THROUGH MID-  
WEEK.  
 
MMG/PFAHLER  
 
 
   
AVIATION  
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1038 PM CDT THU OCT 10 2024  
 
CONFIDENCE REMAINS HIGH IN DRY AND VFR FLIGHT CONDITIONS AT ALL  
LOCAL TERMINALS THROUGH THE FORECAST PERIOD. FOG CAN'T COMPLETELY  
BE RULED OUT AT KJEF, KSUS, AND KCPS, THOUGH WITH TEMPERATURES  
TRENDING WARMER TONIGHT COMPARED TO THE LAST COUPLE OF NIGHTS,  
CONFIDENCE IN FOG DEVELOPING AND IMPACTING THESE TERMINALS REMAINS  
LOW.  
 
ELMORE  
 
 
   
CLIMATE  
 
ISSUED AT 220 PM CDT WED OCT 9 2024  
 
OCTOBER 12TH RECORD DAILY HIGH TEMPERATURES:  
 
KSTL: 89 IN 1890  
KCOU: 94 IN 1899  
KUIN: 88 IN 1975  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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