275  
FXUS63 KLSX 012300  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
600 PM CDT TUE JUL 1 2025  
   
KEY MESSAGES  
 
- SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL PERSIST THROUGH  
THURSDAY WITH WARMER AND MORE HUMID CONDITIONS RETURNING ON THE  
4TH OF JULY INTO THE HOLIDAY WEEKEND.  
 
- DRY CONDITIONS ARE EXPECTED THROUGH THE 4TH OF JULY, BUT  
OPPORTUNITIES FOR SHOWERS AND THUNDERSTORMS WILL BE PRESENT OVER  
THE HOLIDAY WEEKEND INTO EARLY NEXT WEEK.  
 
 
   
SHORT TERM  
(THROUGH LATE WEDNESDAY NIGHT)  
ISSUED AT 219 PM CDT TUE JUL 1 2025  
 
IN THE WAKE OF MONDAY'S UPPER-LEVEL TROUGH AND COLD FRONT, DEEP,  
NORTHWESTERLY FLOW HAS FILTERED A DRIER AND MORE SEASONABLE AIRMASS  
INTO THE REGION TRANSLATING TO TEMPERATURES IN THE 80S AND DEWPOINTS  
IN THE UPPER 50S TO MID-60S F ACROSS THE CWA UNDER LARGE-SCALE  
SUBSIDENCE WITH ONLY FAIR DIURNAL CUMULUS. AS SURFACE ANTICYCLONE  
ARRIVES TONIGHT, CONDITIONS WILL BE FAVORABLE FOR EFFICIENT  
RADIATIONAL COOLING TO NEAR TODAY'S DEWPOINTS RESULTING IN LOW  
TEMPERATURES IN THE 60S F, UPPER 50S F IN A FEW SHELTERED/LOW-LYING  
LOCATIONS, AS WELL AS PATCHY RIVER VALLEY FOG WEDNESDAY MORNING  
AIDED BY INCREASING AIR-WATER TEMPERATURE DISPARITY.  
 
ON WEDNESDAY CONDITIONS WILL BE VERY SIMILAR TODAY, WITH THE ONLY  
DIFFERENCE BEING TEMPERATURES A DEGREE OR TWO WARMER AS LOW-LEVEL  
FLOW BECOMES WEAKLY WESTERLY AS THE ANTICYCLONE VERY SLOW MIGRATES  
JUST SOUTH OF THE CWA. PATCHY RIVER VALLEY FOG WILL BE POSSIBLE  
AGAIN LATE WEDNESDAY NIGHT/EARLY THURSDAY MORNING BUT CONDITIONS  
WILL NOT BE QUITE AS FAVORABLE WITH REPEATED DAYS OF DEEPER BL  
MIXING.  
 
PFAHLER  
 
 
   
LONG TERM  
(THURSDAY THROUGH NEXT TUESDAY)  
ISSUED AT 219 PM CDT TUE JUL 1 2025  
 
THURSDAY THROUGH FRIDAY/4TH OF JULY, UPPER-LEVEL NORTHWESTERLY FLOW  
WILL GIVE WAY TO AN AMPLIFYING RIDGE TRAVERSING THE UPPER/MID-  
MISSISSIPPI RIVER VALLEY ON FRIDAY. MODEL GUIDANCE INDICATE THAT A  
SERIES OF MID-LEVEL PERTURBATIONS IN CONJUNCTION WITH NOCTURNAL LLJS  
COULD RESULT IN SOME SHOWERS AND THUNDERSTORMS ACROSS THE UPPER  
MIDWEST EARLY THURSDAY MORNING AND AGAIN EARLY FRIDAY MORNING BUT 90  
PERCENT OF ENSEMBLE MODEL MEMBERSHIP DISSIPATES PRECIPITATION BEFORE  
ITS ABLE TO REACH NORTHEASTERN MO/WEST-CENTRAL IL. LARGELY DRY  
CONDITIONS WILL BE ACCOMPANIED BY A CONTINUED WARMING TREND AS LOW-  
LEVEL FLOW BECOMES MORE SOUTHERLY. IN RESPONSE, HIGH TEMPERATURES IN  
THE 90S WILL BECOME COMMON BY FRIDAY WITH HEAT INDEX VALUES IN THE  
MID-90S TO NEAR 100 F AS DEWPOINTS ALSO RISE INTO THE UPPER 60S TO  
LOW-70S F.  
 
GLOBAL MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT THAT THE UPPER-  
LEVEL RIDGE WILL MIGRATE INTO THE GREAT LAKES AND ALLOW A SERIES OF  
UPPER-LEVEL TROUGHS OR SHORTWAVE TROUGHS TO ENTER THE MID-  
MISSISSIPPI RIVER VALLEY OVER THE WEEKEND INTO NEXT WEEK WITH A COLD  
FRONT ARRIVING AROUND SUNDAY AND POTENTIALLY LINGERING IN THE  
VICINITY OF THE REGION INTO NEXT WEEK. THIS EVOLUTION WILL LEAD TO  
OPPORTUNITIES FOR SHOWERS AND THUNDERSTORMS AT TIMES FROM SATURDAY  
ONWARD WITH ENSEMBLE MODEL MEMBERSHIP WITH MEASURABLE PRECIPITATION  
VARYING BETWEEN 30 AND 60 PERCENT. AS A RESULT, THERE IS ALSO  
DECREASING CONFIDENCE IN TEMPERATURES THROUGH THAT TIME WITH THE NBM  
75TH PERCENTILE ONLY SLIGHTLY COOLING BUT THE 25TH PERCENTILE  
COOLING CLOSER TO AVERAGE INTO EARLY NEXT WEEK.  
 
PFAHLER  
 
 
   
AVIATION  
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)  
ISSUED AT 553 PM CDT TUE JUL 1 2025  
 
MAINLY DRY AND VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. THE  
ONLY EXCEPTION WILL BE RIVER FOG LATE TONIGHT INTO EARLY WEDNESDAY  
THAT WILL LIKELY AFFECT JEF AND SUS, SO HAVE MAINTAINED THE TEMPO  
GROUPS AT THESE AIRPORTS BETWEEN 09-13Z. OTHERWISE WINDS WILL  
TURN LIGHT AND VARIABLE THIS EVENING AS HIGH PRESSURE MOVES INTO  
THE AREA.  
 
BRITT  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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