909  
FXUS63 KLSX 060404  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
1104 PM CDT TUE AUG 5 2025  
   
KEY MESSAGES  
 
- DRY CONDITIONS WITH WARMING TEMPERATURES WILL LAST FROM  
WEDNESDAY THROUGH THE END OF THE WEEK.  
 
 
   
SHORT TERM  
(THROUGH LATE WEDNESDAY NIGHT)  
ISSUED AT 143 PM CDT TUE AUG 5 2025  
 
THE MID-MISSISSIPPI VALLEY IS CURRENTLY ON THE BACKSIDE OF A MID-  
LEVEL SHORTWAVE TROUGH. THE BEST OF THE FEATURE'S LIFT HAS EXITED  
THE REGION, BUT WE STILL HAVE A BIT LINGERING BEHIND THE REST. THIS  
WEAK LIFT IN ADDITION TO INCREASING INSTABILITY OVER SOUTHERN AND  
CENTRAL ILLINOIS HAS RESULTED IN ISOLATED SHOWERS AND  
THUNDERSTORMS. THESE WILL REMAIN SUB-SEVERE GIVEN THE LACK OF  
APPRECIABLE WIND SHEAR. SHOWERS AND THUNDERSTORMS WILL DISSIPATE  
THIS EVENING AS DAYTIME INSTABILITY WANES.  
 
PATCHY FOG IS EXPECTED AGAIN TONIGHT PRIMARILY IN RIVER VALLEYS AND  
WHERE RADIATIONAL COOLING CONDITIONS ARE PRESENT. OVERNIGHT LOWS  
WILL FALL INTO THE 60S AREAWIDE.  
 
JAJA  
 
 
   
LONG TERM  
(THURSDAY THROUGH NEXT TUESDAY)  
ISSUED AT 143 PM CDT TUE AUG 5 2025  
 
A MID-LEVEL RIDGE CURRENTLY CENTERED OVER SOUTHERN NEW MEXICO WILL  
EXPAND INTO THE CENTRAL CONUS THROUGH THE MIDDLE OF THIS WEEK. WE'LL  
SEE THE INFLUENCE OF THE SUBSEQUENT HEIGHT RISES AS EARLY AS  
WEDNESDAY IN THE FORM OF DRY CONDITIONS AND WARMER TEMPERATURES.  
WHERE TODAY WIDESPREAD 80S ARE BEING OBSERVED THIS AFTERNOON,  
TOMORROW LOW-90S WILL BEGIN TO CREEP INTO PORTIONS OF CENTRAL AND  
SOUTHEAST MISSOURI. THIS TREND WILL CONTINUE THROUGH THE END OF THE  
WEEK WITH WIDESPREAD HIGHS IN THE LOW TO MID-90S FORECAST BY  
SATURDAY. DEWPOINTS IN THE 70S WILL BRING US BACK TO THE  
UNCOMFORTABLY HUMID SIDE OF SUMMER, BUT HEAT INDEX VALUES AS A  
WHOLE WILL REMAIN BELOW HEAT ADVISORY CRITERIA DURING THE STRETCH.  
 
THE RIDGE WILL BEGIN TO ERODE LATE THIS WEEK AND GIVE WAY TO A  
TROUGH DEEPENING OVER THE NORTHERN CONUS. A COLD FRONT WILL  
ACCOMPANY THE TROUGH AND WILL IMPACT THE CWA'S SENSIBLE WEATHER, BUT  
TO WHAT DEGREE IS STILL UNCLEAR. THE TROUGH'S SPEED AND STRENGTH AND  
THE NUMBER OF ANY SHORTWAVES ALONG ITS SOUTHERN PERIPHERY WILL  
DICTATE THE BEHAVIOR OF THE COLD FRONT AT THE SURFACE. THAT INCLUDES  
IF THE COLD FRONT WAVERS ABOUT THE REGION OR IF IT PUSHES THROUGH  
COMPLETELY. AS OF NOW, ENSEMBLE GUIDANCE IS VERY SPREAD ON WHEN  
EXACTLY THE FRONT AND RAIN CHANCES WILL ENTER THE CWA AND HOW LONG  
IT'LL ALL LAST. FOR INSTANCE, 60%+ OF ENSEMBLE MEMBERS HAVE AT LEAST  
A TRACE OF RAIN FALLING DURING ALL 6 HOUR PERIODS BETWEEN SUNDAY  
NIGHT AND WEDNESDAY. THIS IS OBVIOUSLY QUITE WASHED OUT AND SHOWS  
THAT GUIDANCE HAS YET TO REALLY KEY IN ON ANY SPECIFIC SOLUTION. THE  
NBM INTERQUARTILE RANGE REFLECTS THESE UNCERTAINTIES AS WELL AS IT  
SPREADS TO 5+ DEGREES AFTER SUNDAY.  
 
JAJA  
 
 
   
AVIATION  
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 1104 PM CDT TUE AUG 5 2025  
 
VFR FLIGHT CONDITIONS ARE EXPECTED TO PREVAIL THROUGH WEDNESDAY.  
FOG IS POSSIBLE BEFORE SUNRISE WEDNESDAY MORNING, PRIMARILY IN  
RIVER VALLEYS AND OTHER SHELTERED SPOTS. ANY FOG THAT DEVELOPS  
SHOULD LIFT AND DISSIPATE QUICKLY AFTER SUNRISE.  
 
CARNEY  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab MO Page
The Nexlab IL Page
Main Text Page