619  
FXUS63 KLSX 080234  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
934 PM CDT MON JUL 7 2025  
   
KEY MESSAGES
 
 
- SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING  
FROM THE EASTERN OZARKS THROUGH SOUTHWESTERN ILLINOIS. ISOLATED  
TO PERHAPS SCATTERED THUNDERSTORMS ARE POSSIBLE OVER CENTRAL  
MISSOURI.  
 
- ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE TUESDAY. A FEW  
THUNDERSTORMS MAY BECOME STRONG WITH ISOLATED SEVERE POTENTIAL.  
THE PRIMARY THREAT WILL BE DAMAGING WIND GUSTS TO 60 MPH AND A  
LOCALIZED THREAT FOR HEAVY RAIN.  
 

 
   
SHORT TERM
 
(THROUGH LATE TUESDAY NIGHT)  
ISSUED AT 231 PM CDT MON JUL 7 2025  
 
REGIONAL ANALYSIS SHOWS A DIFFUSE OR REMNANT COLD FRONT SLOWLY  
SINKING SOUTHWARD ACROSS SECTIONS OF SOUTHERN MISSOURI AND ILLINOIS.  
SCATTERED SHOWERS AND THUNDERSTORMS HAVE LARGELY BEEN FOCUSED ALONG  
THIS BOUNDARY EARLY THIS AFTERNOON. CURVING BACK TO THE NORTHWEST  
THROUGH CENTRAL MISSOURI IS ISOLATED ACTIVITY THAT IS LARGELY  
SUPPORTED BY MID/UPPER LEVEL VORTICITY RIDING OVER TOP THE WASHED  
OUT SURFACE BOUNDARY AND THETA-E GRADIENT THAT EXTENDS THROUGH  
MID- MISSOURI FROM NW TO SE.  
 
THE BOUNDARY, WHICH IS ESSENTIALLY WASHED OUT/QUASI STATIONARY, WILL  
REMAIN THE PRIMARY DRIVER FOR ADDITIONAL SHOWERS AND THUNDERSTORMS  
THROUGH THIS EVENING. TRENDS OVER THE LAST FEW HOURS HAVE SHOWED A  
SLIGHT REINFORCEMENT TOWARD THE SOUTH AS A RESULT OF COOLER AIR  
PRODUCED BY ONGOING THUNDERSTORMS IN THIS REGION. IF THE COOLER AIR  
PRODUCED BY THUNDERSTORMS CONTINUES TO PUSH THE BOUNDARY SOUTH,  
WHICH COME CAMS SUGGEST, MUCH OF IT WILL SHIFT THAT DIRECTION OVER  
THE NEXT FEW HOURS. THAT LEAVES US WITH ISOLATED TO PERHAPS  
SCATTERED CONVECTION OVER CENTRAL MISSOURI, WHERE MID/UPPER  
VORTICITY IS CURRENTLY TRACKING EAST-SOUTHEAST ALONG A THETA-E  
GRADIENT THAT SEPARATES THE MOIST ATMOSPHERE FROM THE COPIOUS  
MOISTURE FURTHER SOUTHWEST. FORTUNATELY, THUNDERSTORMS ARE DEVELOPING  
IN A WEAK SHEAR ENVIRONMENT AND OTHER THAN THE SEMI-LINEAR  
ORIENTATION ALONG THE DIFFUSE BOUNDARY, THERE ISN'T MUCH  
ORGANIZATION EXPECTED. THEREFORE, SHOULD A THUNDERSTORM BECOME  
STRONG, THE PRIMARY THREAT WOULD BE GUSTY WINDS. EVEN THAT POTENTIAL  
IS LOW CONSIDERING THE INVERTED-V SIGNATURE ISN'T AS PRONOUNCED AS  
I'D LIKE TO OTHERWISE SEE (MARKED BY 10 DEWPOINT DEPRESSIONS).  
 
THUNDERSTORM CHANCES NEVER REALLY ZERO OUT, BUT WILL WANE LATE THIS  
EVENING AS DIURNAL INSTABILITY IS LOST AFTER SUNSET. TUESDAY SETS UP  
ANOTHER COMPLICATED SCENARIO WHICH POSES SLIGHTLY BETTER CHANCES FOR  
STRONGER THUNDERSTORMS. CAMS SHOW SOME SEMBLANCE OF AN MCS TAKING  
SHAPE OVER SECTIONS OF EASTERN NEBRASKA, THEN SLIDING SOUTHEAST NEAR  
THE IA/MO BORDER OVERNIGHT. BY TUESDAY MORNING, THE COMPLEX WEAKENS,  
IF NOT ENTIRELY DISSIPATES AS IT OUTRUNS ITS H8 THETA-E SOURCE AND  
BECOME OUTFLOW DOMINANT. SLIGHT CHANCE/CHANCE POPS COVER THIS  
POTENTIAL OVER CENTRAL MO INTO WEST-CENTRAL IL. THE BIGGEST QUESTION  
WAS HOW FAR EAST TO SPREAD SLIGHT CHANCE POPS CONSIDERING THE  
UNCERTAINTY WITH HOW LONG THE COMPLEX SURVIVES. THIS WILL CERTAINLY  
BE AN AREA OF OPPORTUNITY FOR FINE TUNING IN SUBSEQUENT UPDATES.  
 
THE BEST POTENTIAL FOR THUNDERSTORMS COMES TUESDAY AFTERNOON INTO  
TUESDAY EVENING WITH THE CAVEAT THAT PRIOR CONVECTION WILL BE LONG  
GONE, ALLOWING INSTABILITY TO BUILD THROUGH THE AFTERNOON. THE  
COMPLEX ADDRESSED IN THE PRIOR PARAGRAPH WILL SEND AND OUTFLOW  
BOUNDARY SOUTHWARD, ENCOUNTERING DEWPOINTS IN THE LOW TO MID-70S AND  
SBCAPE VALUES OF 2500-3500 J/KG PER HRRR/RAP/NAM GUIDANCE, AS WELL  
AS INTERACTION WITH THE REMNANT SURFACE BOUNDARY TO ITS SOUTH. HOW  
IT PLAYS OUT IS DEPENDENT ON TIMING AND PLACEMENT, WHICH HAS NOT  
BEEN SO CONSISTENT ACROSS INDIVIDUAL GUIDANCE. SHOULD A SLOW  
SOLUTION PLAY OUT, THUNDERSTORMS WOULD INITIALIZE FURTHER NORTHWEST  
AND TAKE ADVANTAGE OF AN UNSTABLE ATMOSPHERE THAT IS LARGELY  
UNDISTURBED OR MERELY RIDDLES WITH ISOLATED TO SCATTERED ACTIVITY.  
SHOULD THE QUICKER SOLUTION PLAY OUT, THE INTERACTION WITH THE  
SURFACE BOUNDARY COULD RESULT IN DEVELOPMENT SOONER, WHICH WOULD  
HAVE BROADER GEOGRAPHICAL COVERAGE THAT MONDAY. THIS WOULD THEN LEAD  
TO COMPETING UPDRAFTS IN A LOW SHEAR (20 KNOTS OR LESS) ENVIRONMENT  
WITH MOISTURE LOADED THUNDERSTORMS FALLING INTO A SURFACE LAYER THAT  
IS MARGINALLY SUPPORTIVE OF WET DOWNBURST. THEREFORE, THE SPC'S  
MARGINAL OUTLOOK SEEMS REASONABLE WITH THE POTENTIAL FOR ISOLATED  
DAMAGING WIND GUST TO AROUND 60 MPH.  
 
ADDITIONALLY, PWAT VALUES AROUND 2 INCHES SUGGEST HEAVY RAINFALL  
WILL BE POSSIBLE WITHIN THUNDERSTORMS. HOWEVER, THESE LOOK SOMEWHAT  
PROGRESSIVE AND WHILE LOCALIZED PONDING OR NUISANCE FLOODING IS  
POSSIBLE, IT DOES NOT LOOK LIKE A WIDESPREAD ISSUE AT THIS TIME.  
 
MAPLES  
 

 
   
LONG TERM
 
(WEDNESDAY THROUGH NEXT MONDAY)  
ISSUED AT 231 PM CDT MON JUL 7 2025  
 
THE MAIN FEATURES THAT DRAW ATTENTION IN THE LONG TERM PERIOD ARE  
THE STRENGTHENING UPPER LEVEL RIDGE OVER THE DESERT SOUTHWEST AND  
THE STACKED RIDGE CENTERED OVER THE WESTERN ATLANTIC THAT EXTENDS  
WESTWARD THROUGH THE GULF STATES.  
 
BY WEDNESDAY, THE SURFACE FRONT THAT AIDS IN THUNDERSTORM  
DEVELOPMENT TUESDAY INTO TUESDAY EVENING WILL BE REINFORCES  
SOUTHWARD AS THE MID/UPPER TROUGH PASSES OVER THE MID-MISSISSIPPI  
VALLEY. AS IS TYPICAL FOR MID-SUMMER PATTERNS, GUIDANCE VARIES  
ON THE EXACT POSITION AND RESULTING PRECIPITATION POTENTIAL.  
NONETHELESS, THE GENERAL CONSENSUS IS THAT THUNDERSTORMS WILL BE  
CONCENTRATED ALONG AND SOUTH OF I-70 AS HIGH PRESSURE BUILDS IN  
FRONT THE NORTHWEST AND NORTHWESTERLY FLOW DRAWS IN SLIGHTLY  
COOLER AND DRIER AIR.  
 
THE REMAINDER OF THE FORECAST IS SOMEWHAT OF A SQUEEZE PLAY, AS  
THE STRONG UPPER LEVEL RIDGE OVER THE SOUTHWESTERN CONUS BEGINS  
TO FLATTEN SHIFT SLIGHTLY WEST. WHAT INITIALLY STEERS THE ACTIVE  
TRACK OVER THE NORTHERN ROCKIES INTO THE PLAINS, WILL EVENTUALLY  
GIVE WAY TO ZONAL FLOW ALOFT. MEANWHILE, THE RIDGE OVER THE  
SOUTHEASTERN U.S. COULD BE A PLAYER IN CONVECTIVE TRENDS FURTHER  
OUT. IN SUMMER PATTERNS LIKE THIS, CONVECTION WILL OFTEN GET  
HINGED UP AT THE NORTHWEST SIDE OF THE SURFACE/MID-LEVEL RIDGE,  
BUT CAN ALSO BE INVIGORATED BY SHORTWAVE/TROUGHS THAT ARE  
INTRODUCED FROM THE WEST. CONSIDERING THAT UPPER LEVEL FLOW TURNS  
ZONAL IN TIME, ADDITIONAL CHANCES FOR THUNDERSTORMS WILL PRESS  
THROUGH THE REGION, ALONG WITH THE ENHANCEMENT OF SOUTHERLY FLOW  
AT THE BACK SIDE OF THE SOUTHEASTERN RIDGE AND AHEAD OF  
APPROACHING SYSTEMS. WHILE NO SINGLE DAY LOOKS COMPLETELY DRY, THE  
MOST OF THE DRY TIME MIGHT END UP BEING WEDNESDAY AFTERNOON INTO  
THURSDAY AS SURFACE HIGH PRESSURE CROSSES THE REGION.  
 
BY LATE WEEK INTO NEXT WEEKEND, A BETTER ORGANIZED TROUGH TRACKS  
WEST TO EAST ACROSS THE CENTRAL ROCKIES, RESULTING IN SURFACE  
CYCLOGENESIS OVER THE PLAINS. A COLD FRONT TRAILS THE SYSTEM AND  
COULD BE BEST CHANCE AT SHOWERS AND THUNDERSTORMS BEYOND  
WEDNESDAY.  
 
MAPLES  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)  
ISSUED AT 934 PM CDT MON JUL 7 2025  
 
DRY CONDITIONS ARE EXPECTED FOR THE MOST PART OVERNIGHT TONIGHT,  
THOUGH WE ARE WATCHING ORGANIZED CONVECTION MOVING SOUTHWARD  
ACROSS EASTERN NEBRASKA. THE MOST LIKELY SCENARIO IS FOR THIS  
ACTIVITY TO LARGELY OR COMPLETELY MISS US TO THE WEST. IN  
ADDITION, IT SHOULD WEAKEN WITH TIME. ADDITIONAL THUNDERSTORMS ARE  
FORECAST TO DEVELOP BY EARLY-MID AFTERNOON, MAINLY FROM CENTRAL  
MISSOURI EAST/NORTHEAST. THE BEST CHANCES FOR THUNDERSTORMS MAY BE  
AT THE METRO TERMINALS, LARGELY BETWEEN 2000 UTC TUESDAY AND 0000  
UTC WEDNESDAY. WASN'T QUITE CONFIDENT TO ADD A TEMPO, AS THERE  
REMAINS ENOUGH UNCERTAINTY ON TIMING AND WHERE CONVECTIVE  
DEVELOPMENT WILL BE PREFERRED. HOWEVER, ANY TERMINAL THAT DOES SEE  
A DIRECT IMPACT FROM A THUNDERSTORM TUESDAY WILL BE CAPABLE OF  
PRODUCING GUSTY WINDS AND BRIEF DOWNPOURS REDUCING VISIBILITIES.  
 
THE OTHER CONCERN IS FOR SOME FOG TONIGHT AT THE RIVER VALLEY  
SITES. THE BEST CHANCES LOOK TO BE ACROSS SOUTHEAST MISSOURI AND  
SOUTHWEST ILLINOIS, BUT CANNOT RULE OUT A BRIEF PERIOD OF SAY MVFR  
VISIBILITIES AT KSUS, KCPS, AND/OR KJEF. LEFT THIS MENTION OUT OF  
THE TAFS FOR NOW, BUT THIS WILL BE SOMETHING TO MONITOR OVERNIGHT.  
 
GOSSELIN  
 

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

 
 

 
 
WFO LSX  
 
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