251  
FXUS63 KLSX 092341  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
641 PM CDT WED JUL 9 2025  
   
KEY MESSAGES  
 
- THERE ARE MULTIPLE CHANCES FOR SHOWERS AND THUNDERSTORMS BETWEEN THURSDAY  
AND THE MIDDLE OF NEXT WEEK. SEVERE WEATHER IS NOT EXPECTED.  
 
- FRIDAY WILL BE THE WARMEST DAY OF THE WEEK AS HEAT INDEX VALUES  
CLIMB TO AROUND 100 DEGREES FOR MOST. THE ST. LOUIS METRO AREA  
WILL SEE VALUES CLOSER TO 105 DEGREES.  
 
 
   
SHORT TERM  
(THROUGH LATE THURSDAY NIGHT)  
ISSUED AT 142 PM CDT WED JUL 9 2025  
 
SURFACE ANALYSIS SHOWS A DIFFUSE QUASI-STATIONARY FRONT EXTENDING  
FROM THE CENTRAL PLAINS THROUGH CENTRAL IOWA. THIS FRONT WILL CREEP  
SOUTH INTO NORTHEAST MISSOURI/WEST-CENTRAL ILLINOIS THROUGH THIS  
AFTERNOON AND WILL HAVE NO NOTICEABLE IMPACT ON OUR SENSIBLE  
WEATHER. HOWEVER, THE BOUNDARY HAS BEEN A CATALYST FOR CONVECTIVE  
INITIATION IN NEBRASKA AND THE DAKOTAS TODAY. AS THE NOCTURNAL  
LOW-LEVEL JET RAMPS UP TONIGHT, THESE SHOWERS AND THUNDERSTORMS  
WILL CONGEAL INTO AN MCS AND FOLLOW THE FRONT INTO NORTHEAST  
MISSOURI. SCATTERED SHOWERS AND THUNDERSTORMS FROM THE MCS ARE  
FORECAST TO ARRIVE IN THE MIDDLE TO LATE MORNING TOMORROW AND  
LINGER THROUGH THE AFTERNOON. THE AREAL EXTENT OF CONVECTION WILL  
DEPEND ON THE PRESENCE OF ANY OUTFLOW BOUNDARIES LAID OUT BY THE  
MORNING CONVECTION. LATEST CAMS ARE KEEN ON OUTFLOW BOUNDARIES  
PLAYING A ROLE IN UPSTREAM CONVECTION TOMORROW AFTERNOON, AND I'M  
NOT INCLINED TO DISAGREE GIVEN 1) THAT WE'LL HAVE UP TO 2000 J/KG  
OF SBCAPE AND 2) THAT OUTFLOW HAS PLAYED A LARGE ROLE IN  
THUNDERSTORM PROPAGATION THIS PAST WEEK. BECAUSE OF THIS AND THE  
CHAOTIC NATURE OF OUTFLOW BOUNDARIES, I'VE SPREAD SLIGHT CHANCE  
POPS OVER THE REST OF THE CWA TOMORROW AFTERNOON. WITH EFFECTIVE  
SHEAR ONLY AROUND 15 KTS, SEVERE WEATHER IS NOT EXPECTED.  
 
OTHERWISE, TOMORROW WILL BE A SEASONABLE DAY WITH LOWS NEAR 70  
DEGREES AND HIGHS AROUND 90.  
 
JAJA  
 
 
   
LONG TERM  
(FRIDAY THROUGH NEXT WEDNESDAY)  
ISSUED AT 142 PM CDT WED JUL 9 2025  
 
A SERIES OF SHORTWAVES WILL KEEP OUR WEATHER PATTERN ACTIVE UNTIL AT  
LEAST THE MIDDLE OF NEXT WEEK. THE GREATEST CHANCE FOR RAIN (UP TO  
50%) WILL COME FRIDAY NIGHT INTO SATURDAY AS A SHORTWAVE INTERACTS  
WITH A STATIONARY FRONT IN THE VICINITY OF THE CWA. NOT EVERYONE  
WILL SEE RAIN OUT OF THIS DUE TO THE SCATTERED NATURE OF THE  
CONVECTION. THOSE WHO DO SEE RAIN, HOWEVER, HAVE THE POTENTIAL TO  
BRIEF HEAVY RAINFALL SINCE PWATS WILL BE HOVERING AROUND 1.7" DURING  
THIS TIMEFRAME. THIS FORECAST IS GENERALLY TRUE THROUGH WEDNESDAY.  
THE FRONT WILL LINGER IN THE AREA THROUGH SUNDAY PROVIDING ANOTHER  
CHANCE OF SHOWERS AND THUNDERSTORMS. MONDAY LOOKS DRIER AS THE FRONT  
MOVES OFF, BUT RAIN CHANCES RAMP UP AGAIN ON TUESDAY AS ANOTHER  
SHORTWAVE TRIGGERS A COLD FRONT AT THE SURFACE. A LACK OF SUFFICIENT  
EFFECTIVE SHEAR EACH DAY (ONLY 10 - 15 KTS) WILL KEEP THE POTENTIAL  
FOR SEVERE WEATHER LOW.  
 
THE TEMPERATURE FORECAST THROUGH WEDNESDAY WILL GENERALLY BE  
SEASONABLE WITH HIGHS IN THE 80S TO 90 DEGREES AND LOWS IN THE 60S  
AND 70S. FRIDAY IS EXPECTED TO BE THE WARMEST DAY AS HEAT INDEX  
VALUES CLIMB TO AROUND 100 DEGREES FOR MOST AND NEAR 105 IN THE ST.  
LOUIS METRO AREA. OVERALL, NOTHING UNCHARACTERISTIC FOR JULY.  
 
JAJA  
 
 
   
AVIATION  
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 633 PM CDT WED JUL 9 2025  
 
VFR CONDITIONS ARE LIKELY TO PREVAIL THROUGHOUT THE 00Z TAF CYCLE.  
AFTERNOON VFR CUMULUS CLOUDS ARE EXPECTED TO DIMINISH NEAR THE  
START OF THE PERIOD, WITH LIGHT WINDS AND OCCASIONAL HIGH LEVEL  
CLOUDS OVERNIGHT. A FEW RIVER VALLEY LOCATIONS MAY SEE SOME PATCHY  
FOG TONIGHT, BUT CONFIDENCE REMAINS TOO LOW THAT THIS WILL IMPACT  
ANY OF OUR LOCAL TERMINALS LIKE IT DID THE PRIOR MORNING.  
 
DURING THE DAY, THERE WILL BE A LOW PROBABILITY OF RAIN SHOWERS  
AND THUNDERSTORMS, WITH BEST CHANCES (~40%) DURING THE LATE  
AFTERNOON AT UIN. HOWEVER, SHOWER CHANCES AT OTHER TERMINALS  
REMAIN NEAR 20% OR LESS, AND ARE TOO LOW FOR TAF MENTION AT THIS  
TIME. OTHERWISE, EXPECT ANOTHER VFR AFTERNOON CUMULUS FIELD AND  
LIGHT SOUTHERLY WINDS.  
 
BRC  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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