820  
FXUS63 KLSX 070910  
AFDLSX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
410 AM 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 06Z TAFS THROUGH 06Z MONDAY NIGHT)  
ISSUED AT 1039 PM CDT SUN JUL 6 2025  
 
COOL AND HUMID CONDITIONS OVERNIGHT MAY LEAD TO THE FORMATION OF  
FOG. HOWEVER, EXTENSIVE MID LEVEL CLOUD COVER IN THE WAKE OF  
SUNDAY AFTERNOON'S THUNDERSTORMS WILL LIKELY PREVENT THIS FROM  
OCCURRING IN MANY AREAS. SOME BREAKS IN THE CLOUDS ACROSS CENTRAL  
MISSOURI HAVE MADE IT A BIT MORE LIKELY THAT FOG FORMS AT COU AND  
JEF, WHILE THE ST LOUIS METRO HAS A SIGNIFICANTLY LOWER CHANCE DUE  
TO THAT CLOUD COVER. WINDS REMAIN LIGHT OVERNIGHT AND TOMORROW.  
ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED DURING THE AFTERNOON,  
BUT IT IS FORECAST TO REMAIN SOUTH OF ALL THE TAF SITES.  
 
KIMBLE  
 
 
   
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