110  
FXUS63 KLSX 171040  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
440 AM CST FRI JAN 17 2025  
   
KEY MESSAGES  
 
- TODAY WILL BE THE WARMEST SO FAR THIS MONTH WITH HIGHS IN THE 40S  
AND 50S. TEMPERATURES WILL QUICKLY DROP ON SATURDAY WITH MUCH  
COLDER WEATHER EXPECTED FOR THE FIRST HALF OF NEXT WEEK.  
 
- WIDESPREAD LIGHT RAIN IS EXPECTED TONIGHT WITH THE HIGHEST  
CHANCE (70-100%) IN SOUTHWEST ILLINOIS AND SOUTHEAST MISSOURI.  
DRY WEATHER IS THEN EXPECTED THROUGH NEXT WEEK.  
 
 
   
SHORT TERM  
(THROUGH LATE SATURDAY AFTERNOON)  
ISSUED AT 339 AM CST FRI JAN 17 2025  
 
WE ARE STILL ON TRACK TO WARM BACK UP AGAIN TODAY WITH HIGH  
TEMPERATURES THIS AFTERNOON EXPECTED TO BE 10 TO 20 DEGREE ABOVE  
NORMAL. A SURFACE HIGH HAS ALREADY MOVED OFF TO THE EAST EARLY THIS  
MORNING ALLOWING WINDS TO BEGIN TO PICK UP OUT OF THE SOUTH ACROSS  
MISSOURI. THIS TREND WILL CONTINUE THROUGH THE DAY BRINGING WARMER  
AIR INTO THE CWA. THERE WILL BE A DECENT AMOUNT OF SUNSHINE TO HELP  
WITH THE WARM-UP BEFORE CLOUDS MOVE INTO THE AREA LATER TODAY. WENT  
CLOSE TO CAM GUIDANCE INCLUDING THE HRRR WHICH HAS LOW TO MID 50S  
ALONG AND WEST OF THE MS RIVER WITH 40S OVER SOUTH CENTRAL IL.  
 
THE ROUND OF LIGHT RAIN IS STILL EXPECTED TO MOVE INTO THE CWA BY  
LATE THIS AFTERNOON AND THIS EVENING AS THE NAM/GFS ARE SHOWING A  
SHORTWAVE TROUGH SHEARING OUT ON THE FRONT SIDE OF A LONGWAVE TROUGH  
THAT WILL BE DROPPING OUT OF CANADA. THERE WILL BE MODEST 850-700MB  
FRONTOGENESIS WITH THIS TROUGH THAT WILL BE CONCENTRATED ACROSS THE  
SOUTHEAST HALF OF THE CWA FROM LATE THIS AFTERNOON THROUGH TONIGHT.  
HREF PROBABILITIES SUPPORT 70-100% POPS TONIGHT OVER THIS SAME AREA  
WITH LPMM SHOWING 1/4-3/4" OF RAINFALL SOUTH OF I-44 IN MO AND I-70  
IN IL. WHILE THERE COULD BE SOME SNOWFLAKES MIXED IN AS THE RAIN  
ENDS, RAP/NAM FORECAST SOUNDINGS AND HREF PROBABILITIES STILL  
INDICATE THAT THIS WILL BE A SHORT WINDOW AND ACCUMULATING SNOW IS  
NOT EXPECTED.  
 
THE COLD FRONT THAT IS CURRENTLY OVER THE NORTHERN PLAINS IS STILL  
EXPECTED TO MOVE SOUTHEAST ACROSS THE CWA TONIGHT. STRONG CAA  
BEHIND IT ON SATURDAY WILL CAUSE HIGH TEMPERATURES TO BE 20 TO 25  
DEGREES COLDER THAN TODAY.  
 
BRITT  
 
 
   
LONG TERM  
(SATURDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 339 AM CST FRI JAN 17 2025  
 
THE COLD IS EXPECTED TO LAST THROUGH THE FIRST HALF OF THE NEXT WEEK  
AS THE ENSEMBLE CLUSTER ANALYSIS ARE SHOWING THE THE LONGWAVE TROUGH  
REMAINING OVER THE CENTRAL CONUS. TEMPERATURES WILL BE VERY COLD  
UNDERNEATH THE TROUGH WITH 850MB TEMPERATURES BETWEEN -15 TO -25C  
FROM SUNDAY INTO TUESDAY WHICH IS NEAR RECORD LOW VALUES FOR THIS  
TIME OF YEAR. THIS MEANS THAT THE CWA WILL STAY BELOW FREEZING UNTIL  
WEDNESDAY, WITH SOME SPOTS DROPPING NEAR OR BELOW ZERO ON SUNDAY AND  
MONDAY NIGHT AS A SURFACE HIGH MOVES ACROSS THE AREA. CONFIDENCE IN  
THE COLD IS FAIRLY HIGHS AS THE NBM IQR FROM SUNDAY TO TUESDAY AT  
STL IS 3-7F. WILL NEED TO MONITOR THE POTENTIAL FOR A COLD WEATHER  
ADVISORY AS LREF PROBABILITIES ARE SHOWING 30-70 PERCENT CHANCE OF AOB  
-10F APPARENT TS EARLY ON MONDAY AND TUESDAY MORNINGS ALONG AND  
NORTH OF I-70. WHILE THIS WILL BE A COLD AIRMASS, WE ARE NOT  
EXPECTING TO BREAK RECORD LOWS WHICH ARE WELL BELOW ZERO.  
TEMPERATURES WILL BEGIN TO MODERATE BY MID-LATE NEXT WEEK AS THE  
TROUGH BEGINS TO MOVE OFF TO THE EAST AND THE LOW LEVEL FLOW TURNS  
OUT OF THE SOUTHWEST.  
 
NEXT WEEK LOOKS TO BE DRY AT THIS POINT AS THE LONGWAVE TROUGH WILL  
DISPLACE THE SURFACE FRONT AND AVAILABLE MOISTURE WELL TO OUR SOUTH  
ALONG WITH THE UPPER JET. BOTH THE NBM AND LREF ARE SHOWING THE  
MAJORITY OF THEIR MODELS ARE DRY (PROBABILITIES AOB 15%) OVER OUR  
AREA.  
 
BRITT  
 
 
   
AVIATION  
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)  
ISSUED AT 432 AM CST FRI JAN 17 2025  
 
DRY AND VFR CONDITIONS THROUGH 00Z BEFORE A ROUND OF LIGHT RAIN  
WILL MOVE INTO THE AREA FROM THE SOUTHWEST. THE GREATEST COVERAGE  
WILL AFFECT THE ST. LOUIS TERMINALS THIS EVENING INTO THE  
OVERNIGHT HOURS (03-09Z) AND BRINGING LOW MVFR AND SOME IFR  
CEILINGS. THE MVFR CEILINGS WILL LINGER FOR THE REST OF THE  
PERIOD. THERE WILL LESS COVERAGE AT COU/JEF WARRANTING ONLY A  
PROB30 GROUP BETWEEN 00-06Z. LIGHT RAIN WILL BE POSSIBLE AT UIN,  
BUT THE CHANCES ARE NOT HIGH ENOUGH TO INCLUDE IN THE TAF AT THIS  
TIME. WINDS WILL BE LIGHT AT THE START OF THE TAF PERIOD BUT WILL  
PICK UP OUT OF THE SOUTH AND WILL GUST AT TIME TO AROUND 20 KNOTS  
TODAY. A COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT CAUSING  
WINDS TO SHIFT OUT OF THE NORTHWEST AT EACH TERMINAL.  
 
BRITT  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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