862  
FXUS63 KLSX 050346  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
1046 PM CDT FRI JUL 4 2025  
   
KEY MESSAGES
 
 
- WARM, HUMID CONDITIONS WILL PERSIST THROUGH SATURDAY BEFORE  
TEMPERATURES COOL CLOSER TO AVERAGE BY NEXT WEEK.  
 
- NEARLY DAILY CHANCES OF SHOWERS AND THUNDERSTORMS EXIST FROM  
SATURDAY AFTERNOON (CENTRAL, NORTHEASTERN MO AND WEST-CENTRAL  
IL) THROUGH NEXT WEEK. A FEW STRONGER THUNDERSTORMS COULD  
PRODUCE GUSTY WINDS AND LOCALLY HEAVY RAINFALL SUNDAY AFTERNOON.  
 

 
   
SHORT TERM
 
(THROUGH LATE SATURDAY NIGHT)  
ISSUED AT 238 PM CDT FRI JUL 4 2025  
 
AN UPPER-LEVEL RIDGE HAS BECOME POSITIONED OVER THE MISSISSIPPI  
RIVER VALLEY TODAY, RESULTING IN LARGELY DRY CONDITIONS ASIDE FROM  
ISOLATED SHOWERS IN MORE AGITATED CUMULUS IN A CORRIDOR OF WEAK LOW-  
LEVEL CONVERGENCE ACROSS CENTRAL MO THIS AFTERNOON. OTHERWISE,  
ANOTHER SEASONABLY WARM DAY IS UNDERWAY WITH SIMILAR DEWPOINTS TO  
THURSDAY, LOWERING WITH DEEP BL MIXING, KEEPING HEAT INDEX VALUES  
FROM BECOMING EXCESSIVE. THE ONLY THING NOTEWORTHY FOR TONIGHT WILL  
BE PATCHY SMOKE IN THE ST. LOUIS METRO FROM 4TH OF JULY FIREWORKS,  
TRAPPED BENEATH A SHALLOW TEMPERATURE INVERSION DEVELOPING AFTER  
SUNSET WITH LIGHT SOUTHERLY WINDS. THIS SMOKE COULD TRANSITION TO  
FOG IN RIVER VALLEYS BY SATURDAY MORNING. HOWEVER, CONFIDENCE IS LOW  
THAT VISIBILITIES (SMOKE OR FOG) WILL BE LOW ENOUGH TO HAVE ANY  
SIGNIFICANT IMPACT.  
 
THE UPPER-LEVEL RIDGE WILL SHIFT EASTWARD THROUGH THE GREAT LAKES  
INTO THE NORTHEAST/MID-ATLANTIC ON SATURDAY, PERMITTING A WEAKENING  
TROUGH TO REACH THE MID-MISSISSIPPI RIVER VALLEY SATURDAY  
NIGHT/SUNDAY THAT FORCES A COLD FRONT INTO THE CWA. AROUND 20 TO 40  
PERCENT OF HREF MEMBERSHIP DEPICTS SHOWERS AND THUNDERSTORMS ACROSS  
CENTRAL, NORTHEASTERN MO AND WEST-CENTRAL IL DURING THE AFTERNOON  
AND EVENING, BOTH LIKELY FROM SHOWERS AND THUNDERSTORMS OR THEIR  
REMNANTS ARRIVING FROM NORTHERN AND WESTERN MO. CAMS INDICATE THAT A  
MODEST (20 KT) SOUTHWESTERLY LLJ AND THE INCOMING COLD FRONT WILL  
ALLOW SHOWERS AND THUNDERSTORMS SATURDAY EVENING TO SURVIVE LONGER  
INTO THE CWA AT NIGHT. SATURDAY'S HIGH TEMPERATURES WILL BE SIMILAR  
TO TODAY'S ASIDE FROM GREATER CLOUDS AND SCATTERED SHOWERS AND  
THUNDERSTORMS KEEP TEMPERATURES SLIGHTLY COOLER IN CENTRAL,  
NORTHEASTERN MO AND WEST-CENTRAL IL.  
 
PFAHLER  
 

 
   
LONG TERM
 
(SUNDAY THROUGH NEXT FRIDAY)  
ISSUED AT 238 PM CDT FRI JUL 4 2025  
 
ON SUNDAY, THERE WILL LIKELY BE A MINIMUM IN SHOWERS AND  
THUNDERSTORMS DURING THE MORNING, BEFORE REDEVELOPMENT OCCURS DURING  
THE AFTERNOON. THE GREATEST FOCUS OF SHOWERS AND THUNDERSTORMS WILL  
BE NEAR THE COLD FRONT AND ANY OUTFLOW THAT LINGERS, WHICH 50 TO 60  
ENSEMBLE MODEL GUIDANCE INDICATES WILL BE GENERALLY NEAR AND SOUTH  
OF THE I-44 AND I-70 CORRIDORS. COVERAGE STILL REMAINS AN  
UNCERTAINTY WITH WEAK FORCING BUT SOME TRANSIENT CLUSTERING OF  
THUNDERSTORMS COULD LEAD TO AREAS OF MORE NUMEROUS COVERAGE. WITH  
WEAK DEEP-LAYER WIND SHEAR AROUND 10 KT, THUNDERSTORMS WILL BE  
DISORGANIZED, PULSE TYPE IN NATURE, WHICH IS NOT FAVORABLE FOR  
WIDESPREAD SEVERE WEATHER. THAT BEING SAID, PW WILL BE AROUND 2" AND  
FORECAST SOUNDINGS HAVE "INVERTED V" SIGNATURES THAT POINT TO VERY  
LOCALIZED HEAVY RAINFALL WITH SLOW-MOVING THUNDERSTORMS AND GUSTY  
WINDS WITH POTENTIAL ISOLATED MICROBURSTS. SHOWERS, THUNDERSTORMS,  
AND CLOUDS ALONG WITH THE FRONTAL PASSAGE IN THE NORTHWESTERN HALF  
OF THE CWA WILL LEAD TO FURTHER COOLING OF HIGH TEMPERATURES,  
RANGING FROM THE MID-80S TO LOW-90S F.  
 
A RELATIVELY ACTIVE PATTERN WILL PERSIST THROUGH MOST OF NEXT WEEK  
WITH NEARLY DAILY OPPORTUNITIES FOR SHOWERS AND THUNDERSTORMS AS  
UPPER-LEVEL FLOW VARIES FROM QUASI-ZONAL TO NORTHWESTERLY, NAVIGATED  
BY A SERIES OF MID-LEVEL PERTURBATIONS AND/OR MCVS. THE SPECIFICS OF  
THIS PATTERN ARE DIFFICULT TO DETERMINE, INCLUDING THE TIMING OF  
EACH OF THESE FEATURES AND THE WAVERING OF THE FRONT THROUGHOUT THE  
WEEK BUT IT WILL NOT RAIN THE ENTIRE WEEK LIKE OUR CURRENT POPS  
COULD BE INTERPRETED. ENSEMBLE MODEL PROBABILITIES OF MEASURABLE  
RAINFALL ARE BETWEEN 30 AND 60 PERCENT ACROSS MOST OF THE CWA EACH  
DAY. BUT THERE HAS BEEN A TREND TOWARD LOWER PROBABILITIES (20  
PERCENT OR LESS) ON MONDAY NORTH OF I-70 AND THE ENTIRE CWA MONDAY  
NIGHT DUE TO THE FRONT TEMPORARILY SHIFTING SOUTHWARD AND THE AREA  
BEING BETWEEN WAVES. THE NBM HIGH TEMPERATURE DISTRIBUTION IS  
GENERALLY CENTERED ON AVERAGE THROUGH NEXT WEEK WITH THE  
INTERQUARTILE RANGE INCREASING FROM AROUND 3 F DURING THE FIRST HALF  
TO 7 F IN THE SECOND HALF AS UNCERTAINTIES IN THE EXACT POSITION OF  
THE FRONT AND PRESENCE/COVERAGE OF SHOWERS AND THUNDERSTORMS  
INCREASE.  
 
PFAHLER  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1045 PM CDT FRI JUL 4 2025  
 
VFR CONDITIONS ARE EXPECTED TO CONTINUE OVERNIGHT AND THROUGH THE  
DAY TOMORROW WITH LIGHT SOUTHERLY WINDS, INCREASING A BIT  
TOMORROW. SOME FOG IN THE VALLEYS IS POSSIBLE BY MORNING, BUT IS  
NOT EXPECTED TO BE WIDESPREAD. CUMULUS DEVELOPS AROUND MIDDAY  
TOMORROW, AND BY EVENING SOME SHOWERS AND STORMS ARE POSSIBLE IN  
THE VICINITY OF QUINCY.  
 
KIMBLE  
 

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

 
 

 
 
WFO LSX  
 
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