564  
FXUS63 KLSX 180802  
AFDLSX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
302 AM CDT WED JUN 18 2025  
   
KEY MESSAGES
 
 
- SEVERE THUNDERSTORMS REMAIN POSSIBLE THIS AFTERNOON AND  
EVENING, PARTICULARLY OVER SOUTHEAST MISSOURI AND SOUTHWEST  
ILLINOIS.  
 
- HEAT INDEX VALUES MAY CLIMB ABOVE 100 DEGREES STARTING FRIDAY  
AND LAST INTO EARLY NEXT WEEK.  
 

 
   
SHORT TERM
 
(THROUGH LATE THURSDAY AFTERNOON)  
ISSUED AT 258 AM CDT WED JUN 18 2025  
 
LATEST RADAR MOSAIC IS SHOWING SCATTERED THUNDERSTORMS DEVELOPING  
OVER CENTRAL MISSOURI WITH AN ORGANIZED MCS MOVING EAST ACROSS  
SOUTHERN MISSOURI AND NORTHERN ARKANSAS. WHILE THE CAMS HAVE THE  
MCS STAYING SOUTH OF THE CWA, THEY DO SHOW A MCV MOVING NORTHEAST  
THAT WILL HELP GENERATE ADDITIONAL SHOWER AND THUNDERSTORMS, MAINLY  
ACROSS CENTRAL AND NORTHEAST MISSOURI INTO WEST ILLINOIS EARLY THIS  
MORNING BETWEEN 5 AND 9 AM. THE OUTFLOW FROM THIS ACTIVITY MAY  
VERY WELL EITHER PUSH INTO THE EASTERN AND SOUTHERN PARTS OF THE  
CWA THIS MORNING, OR PERHAPS OUT OF THE CWA ALTOGETHER DEPENDING  
ON THE STRENGTH OF THE OUTFLOW BOUNDARY. IF THE BOUNDARY DOES STAY  
IN THE THE CWA, IT WILL ACT AS A FOCUS FOR ADDITIONAL  
THUNDERSTORM ACTIVITY AS LATEST RUNS OF THE HRRR IS SHOWING SOME  
ADDITIONAL DEVELOPMENT OVER THE EASTERN CWA LATE THIS MORNING IN  
THE FORM OF DISCRETE CELLS. FORECAST SOUNDINGS FROM THE RAP AT SLO  
AND FAM THIS AFTERNOON ARE SHOWING MLCAPES OF 1000-2000 J/KG WITH  
DEEP LAYER SHEAR 30-40 KNOTS WHICH WILL BE ENOUGH TO SUPPORT  
ORGANIZED MULTI-CELLS AND PERHAPS SUPERCELLS, WITH THE MAIN  
THREAT BEING DAMAGING WINDS WITH LARGE HAIL AND TORNADOES ALSO  
POSSIBLE.  
 
THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL COME TO AN END FROM  
NORTHWEST TO SOUTHEAST AS FRONT CURRENTLY EXTENDING FROM IOWA INTO  
NEBRASKA WILL MOVE SOUTHEAST ACROSS THE AREA TONIGHT. DRY WEATHER  
IS EXPECTED ON THURSDAY AS AN UPPER RIDGE BEGINS TO BUILD IN FROM  
THE PLAINS.  
 
BRITT  
 

 
   
LONG TERM
 
(THURSDAY NIGHT THROUGH TUESDAY)  
ISSUED AT 258 AM CDT WED JUN 18 2025  
 
THE LREF HAS THE AFOREMENTIONED RIDGE BUILDING OVER THE MIDWEST  
BRINGING DRY AND WARM WEATHER LATE WEEK INTO THE WEEKEND. THE NBM  
IS SHOWING IQR OF ONLY 2-4 DEGREES AT STL FROM FRIDAY THROUGH  
MONDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. WITH DEWPOINTS  
FORECAST IN THE 70S, HEAT INDICES CLIMBING ABOVE 100 DEGREES SEEM  
REASONABLE WITH THE LREF PROBABILITIES AOA 50% OVER PARTS OF THE  
AREA ON SATURDAY AND SUNDAY AFTERNOONS.  
 
BRITT  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 1051 PM CDT TUE JUN 17 2025  
 
MOSTLY VFR CONDITIONS ARE EXPECTED OVERNIGHT INTO WEDNESDAY ASIDE  
FROM PERIODS OF THUNDERSTORMS. CONFIDENCE REMAINS LOW IN THE  
TIMING AND LOCATION OF THESE, BUT BEST ESTIMATES HAVE BEEN  
INCLUDED IN THE VARIOUS TAFS. THE PRIMARY THREAT FOR STORMS IS  
WEDNESDAY AFTERNOON FROM CENTRAL MO TO THE ST LOUIS METRO.  
CONDITIONS SHOULD IMPROVE WEDNESDAY EVENING.  
 
KIMBLE  
 

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

 
 

 
 
WFO LSX  
 
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