136  
FXUS63 KLSX 071748  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
1248 PM CDT MON JUL 7 2025  
   
KEY MESSAGES  
 
- SCATTERED THUNDERSTORMS ARE POSSIBLE MAINLY THIS AFTERNOON  
ACROSS THE EASTERN OZARKS. THEY ARE NOT EXPECTED TO BE AS STRONG  
AS SUNDAY'S STORMS.  
 
 
- ANOTHER ROUND OF STRONG TO ISOLATED SEVERE STORMS IS POSSIBLE ON  
TUESDAY. ISOLATED GUSTY WINDS UP TO 60 MPH AND LOCALLY HEAVY  
RAIN ARE THE THREATS ON TUESDAY.  
 
 
   
SHORT TERM  
(THROUGH LATE TONIGHT)  
ISSUED AT 407 AM CDT MON JUL 7 2025  
 
THE "COLD FRONT" IS DIFFICULT TO DISCERN IN SURFACE OBS THIS  
MORNING, HOWEVER THERE IS A PRESSURE TROUGH WHICH LIES GENERALLY  
ALONG THE I-70 CORRIDOR. SHORT RANGE GUIDANCE SHOWS IT SAGGING  
SOUTH TODAY AS A WEAK HIGH PRESSURE SYSTEM MOVES ACROSS THE UPPER  
MIDWEST AND PUSHES SOMEWHAT DRIER AIR SOUTH INTO EASTERN MISSOURI  
AND CENTRAL AND SOUTHERN ILLINOIS. THE LOWER HUMIDITY WILL BE  
NOTICEABLE ACROSS NORTHEAST MISSOURI AND WEST CENTRAL/SOUTH CENTRAL  
ILLINOIS, BUT TEMPERATURES WILL BE VERY SIMILAR TO SUNDAY'S RANGING  
FROM THE MID 80S TO AROUND 90. THE LOWER DEW POINT TEMPERATURES ARE  
EXPECTED TO LEAD TO LOWER INSTABILITY THIS AFTERNOON, PARTICULARLY  
NORTH OF I-70 WHERE RAP MLCAPE VALUES ARE HARD PRESSED TO BREAK 1000  
J/KG. HOWEVER, 1500-2000 J/KG MLCAPE VALUES ARE FORECAST BY THE RAP  
FARTHER SOUTH ACROSS THE EASTERN OZARKS, AND THIS IS WHERE THE  
BEST CHANCE FOR THUNDERSTORMS IS TODAY. MOST SHORT RANGE GUIDANCE IS  
NOT PARTICULARLY BULLISH ON DEVELOPING THUNDERSTORMS THIS AFTERNOON  
SO HAVE LIMITED POPS TO 30-40 PERCENT.  
 
MODELS ARE DEVELOPING AN MCS OVER SOUTH DAKOTA OR NEBRASKA LATE THIS  
AFTERNOON OR EARLY THIS EVENING. THE MCS DROPS SOUTHEAST INTO  
WESTERN IOWA AND NORTHWEST MISSOURI LATE IN THE EVENING INTO THE  
OVERNIGHT HOURS. THERE ARE SPEED AND STRENGTH DIFFERENCES IN HOW  
EACH MODEL HANDLES THE MCS TONIGHT, BUT A FEW BRING THE DISSIPATING  
STORMS INTO CENTRAL AND NORTHEAST MISSOURI AFTER 09Z TONIGHT. THERE  
MAY BE SOME GUSTY WINDS ASSOCIATED WITH THE OUTFLOW BOUNDARY SHOULD  
THIS OCCUR, BUT SEVERE GUSTS ARE NOT EXPECTED.  
 
CARNEY  
 
 
   
LONG TERM  
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 407 AM CDT MON JUL 7 2025  
 
THE UPPER LEVEL PATTERN SHIFTS SLOWLY TUESDAY AND WEDNESDAY WITH THE  
UPPER LEVEL RIDGE OVER THE DESERT SOUTHWEST AND A LONG WAVE TROUGH  
DRIFTING EAST THROUGH THE CENTRAL U.S. INTO THE OHIO VALLEY. THE  
TROUGH AXIS IS FORECAST TO PASS OVER MISSOURI AND ILLINOIS TUESDAY  
INTO TUESDAY EVENING. SYNOPTIC SCALE LIFT WITH THE TROUGH AS WELL  
AS LOW LEVEL MOISTURE CONVERGENCE AHEAD OF THE 850 TROUGH WILL  
PRODUCE ANOTHER ROUND OF CONVECTION TUESDAY AFTERNOON AND EVENING  
WHICH SHOULD BE MORE WIDESPREAD THAN TODAY'S. MOST GUIDANCE FOCUSES  
THE CONVECTION ALONG AND EAST OF THE MISSISSIPPI RIVER TUESDAY  
AFTERNOON, WHICH MAKES SENSE GIVEN THE TROUGH AXIS IS FORECAST TO BE  
STRETCHING FROM WEST CENTRAL ILLINOIS INTO CENTRAL/EAST CENTRAL  
MISSOURI AT THAT TIME. HOWEVER, SMALL DIFFERENCES IN THE SPEED OF  
THE TROUGH WILL CHANGE THE POSITION OF THE BEST FORCING, WHICH WOULD  
PRODUCE CONVECTION FARTHER WEST OR EAST THAN THE CURRENT FORECAST.  
THE GFS CONTINUES TO LOOK LIKE IT'S CONTAMINATED BY CONVECTIVE  
FEEDBACK, BUT THE EXTENDED RAP LOOKS CLEAN WITH MLCAPE REACHING 2500-  
3000 J/KG TUESDAY AFTERNOON/EVENING. THIS MAY BE A HIGHER-END VALUE  
AS THE LREF SHOWS ABOUT THAT MUCH CAPE AT THE 75TH PERCENTILE. 0-  
6KM SHEAR IS NOT VERY IMPRESSIVE AT ~20KTS, BUT THOSE LEVELS OF  
INSTABILITY AND SHEAR WILL BE CAPABLE OF SUSTAINING MARGINALLY  
SEVERE CLUSTERS AND INVERTED V FORECAST SOUNDINGS WILL BE CONDUCIVE  
TO WET MICROBURSTS. PRECIPITABLE WATER VALUES WILL BE NEAR 2 INCHES,  
AND WARM CLOUD DEPTHS WILL BE IN EXCESS OF 12,000FT AS WELL, SO  
LOCALLY HEAVY RAIN WILL CONTINUE TO BE POSSIBLE TUESDAY AFTERNOON  
AND EVENING.  
 
WEAK NORTHWEST FLOW ALOFT ON WEDNESDAY WILL TRANSITION TO MORE ZONAL  
THURSDAY AND FRIDAY WITH A SERIES OF WAVES MOVING ACROSS THE UPPER  
MIDWEST. GUIDANCE SHOWS THE ENERGY FROM THESE WAVES STAYING NORTH  
OF THE FORECAST AREA SO OUR CONVECTION WILL LIKELY BE DRIVEN  
PRIMARILY BY DAYTIME HEATING LINGERING OUTFLOW BOUNDARIES, AND WEAK  
OVERNIGHT LOW LEVEL JETS. IT WILL BE TOUGH TO FIND A TIME DURING  
THAT PERIOD WHERE THERE IS NO CHANCE FOR RAIN, BUT COVERAGE THROUGH  
THAT PERIOD IS NOT EXPECTED TO BE GREATER THAN ISOLATED TO WIDELY  
SCATTERED (20-30%). A STRONGER SHORT WAVE WILL MOVE ALONG THE  
U.S./CANADA BORDER ON SATURDAY AND SUNDAY, DRIVING A SURFACE COLD  
FRONT THROUGH THE NORTHERN PLAINS INTO IOWA AND NORTHERN MISSOURI.  
THE FRONT COULD MAKE IT AS FAR SOUTH AS THE I-70 CORRIDOR BY SUNDAY  
AFTERNOON AND BE A FOCUS FOR MORE WIDESPREAD (40-50%) STORMS.  
GUIDANCE CONTINUES TO SHOW SEASONABLY WARM TEMPERATURES AND HUMID  
CONDITIONS, TYPICAL FOR EARLY TO MID JULY.  
 
CARNEY  
 
 
   
AVIATION  
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 1232 PM CDT MON JUL 7 2025  
 
DESPITE THE DRY FORECAST AT ALL BUT KUIN (PROB30), THERE ARE  
SEVERAL CAVEATS TO WHAT IS AN UNCERTAIN FORECAST WITH RESPECT TO  
POINT-SPECIFIC IMPACTS. WHAT IS ESSENTIALLY A WASHED OUT COLD  
FRONT OVER SOUTHEASTERN MO AND SOUTHWESTERN IL WILL BE THE PRIMARY  
FOCUS FOR AFTERNOON/EVENING THUNDERSTORM POTENTIAL. THEN, ANOTHER  
AREA IN QUESTION IS CENTRAL MO, WHERE ISOLATED SHOWERS AND PERHAPS  
A THUNDERSTORM OR TWO IS BEING SUPPORTED BY ASCENT FROM MID/UPPER  
LEVEL VORTICITY.  
 
THE BEST POTENTIAL FOR THUNDERSTORMS WILL RIDE ALONG THE SURFACE  
BOUNDARY SOUTH OF THE TERMINALS THIS AFTERNOON. THE ONE EXCEPTION  
WILL BE CENTRAL MO, WHERE TRENDS WILL HAVE TO BE MONITORED, BUT AS  
OF NOW, SHOWERS HAVE REMAINED NORTH OF KCOU/KJEF WITH LITTLE  
INDICATION THAT IT WILL MOVE MUCH FURTHER SOUTH. KUIN'S PROB30  
ADDRESSES THE POTENTIAL THAT ISOLATED/WIDELY SCATTERED  
THUNDERSTORMS IMPACT AREAS OF NORTHEASTERN MO AND WEST-CENTRAL IL  
BETWEEN LATE MORNING/EARLY AFTERNOON TUESDAY AS A WEAKENING  
COMPLEX PROGRESSES SOUTHEAST OUT OF THE PLAINS. CONSIDERING THE  
SUMMER PATTERN, EACH ROUND WILL DEPENDENT ON THE PRIOR ROUND,  
WHICH RESULTS IN A HIGHER DEGREES OF UNCERTAINTY AT ANY GIVEN  
POINT. THAT SAID, BETTER PROBABILITIES FOR THUNDERSTORMS WILL BE  
NEAR THE END OR JUST BEYOND THE 24 HOUR TAF PERIOD TUESDAY, WHEN  
ADDITIONAL CONVECTION REDEVELOPS AND PRESENT POTENTIAL FOR BROADER  
COVERAGE IN SCATTERED THUNDERSTORMS. UNTIL THEN, VFR IS FAVORED.  
 
MAPLES  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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