Severe Thunderstorm Warning 246, NWS St. Louis, MO

102 
WWUS53 KLSX 261005
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
505 AM CDT Wed Aug 26 2026

MOC186-261030-
/O.CON.KLSX.SV.W.0246.000000T0000Z-260826T1030Z/
Sainte Genevieve MO-
505 AM CDT Wed Aug 26 2026

...SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 AM CDT FOR
CENTRAL SAINTE GENEVIEVE COUNTY...

At 505 AM CDT, a severe thunderstorm was located near Weingarten, or
10 miles southwest of Ste. Genevieve, moving southeast at 20 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to
         roofs, siding, and trees.

Locations impacted include...
  Rocky Ridge, Weingarten, River Aux Vases, Coffman, St. Mary and
  Minnith.

This includes Interstate 55 in Missouri between exits 141 and 154.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing damaging winds and large
hail.

&&

LAT...LON 3801 9015 3787 8994 3782 9000 3780 9002
      3771 9015 3793 9030
TIME...MOT...LOC 0947Z 335DEG 15KT 3794 9021

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Carney

856 
WWUS53 KLSX 261025
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
525 AM CDT Wed Aug 26 2026

MOC186-261035-
/O.EXP.KLSX.SV.W.0246.000000T0000Z-260826T1030Z/
Sainte Genevieve MO-
525 AM CDT Wed Aug 26 2026

...SEVERE THUNDERSTORM WARNING WILL EXPIRE AT 530 AM CDT FOR CENTRAL
SAINTE GENEVIEVE COUNTY...

The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However, gusty
winds and heavy rain are still possible with this thunderstorm.

&&

LAT...LON 3801 9015 3787 8994 3782 9000 3780 9002
      3771 9015 3793 9030
TIME...MOT...LOC 1005Z 335DEG 15KT 3787 9016

$$

Carney

Area Forecast Discussion
National Weather Service St Louis MO
319 AM CDT Wed Aug 26 2026

.KEY MESSAGES...

- Isolated to widely scattered showers and thunderstorms are expected
  along a cold front this afternoon/evening, mainly across
  south-central Illinois. A couple may be strong to severe with
  damaging winds the main threat.

- Near to slightly below normal temperatures are expected behind today's
  cold front heading into the weekend before more summerlike
  heat returns Sunday into next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 318 AM CDT Wed Aug 26 2026

Weak low-level moisture convergence across the area has led to
some isolated rain showers across parts of southeast Missouri
and south-central Illinois. The latest RAP analysis shows the
south-central Illinois activity is likely being aided by the
approach of a weak midlevel shortwave trough as well. CAMs are
still all over the place through this morning, but it does look
like the very aggressive models (HiRes ARW, NSSL WRF) are too
early and too widespread/organized with convection. Reality will
most likely be closer to the quieter HRRR/FV3 CAMs, which show
some spotty showers/weak thunderstorms through mid morning. A
stronger storm is not out of the question given 1500+ J/kg of
MUCAPE and 30+ knots of effective shear on the latest
mesoanalysis, though that seems like an unlikely scenario at
this time. Small hail would be the main concern with anything
that develops through this morning.

Attention will then turn to a surface cold front moving southeast
out of the mid-Missouri Valley/Upper Midwest. This boundary looks a
bit quicker than it did 24 hours ago, and should approach central
Missouri into west-central Illinois just after midday. By early this
evening, the front is forecast to be just southeast of the I-44/I-55
corridors in Missouri and Illinois respectively. Convective coverage
along the boundary looks isolated to widely scattered, at best.
There is very weak mid/upper level forcing for ascent overhead, with
also weak surface convergence. Therefore, the expectation is for
only isolated to possibly widely scattered showers and thunderstorms
to develop mid to late afternoon, mainly across south-central
Illinois. This is where the surface convergence is slightly
stronger. The much better chance of showers and thunderstorms is
from far eastern Illinois into the Ohio Valley/Great Lakes. Another
area of stronger mid/upper level forcing and surface convergence is
ahead of a remnant MCV across the mid south. Our area will be
between these two more focused areas of convection. The environment
today likely would be supportive of a mixed mode of mainly pulse
convection, but also some multicellular clusters, and potentially
even a transient supercell, are also possible. Damaging winds are
the primary threat due to high DCAPE values courtesy of inverted-V
profiles. However, the very weak surface convergence does make this
threat quite conditional in our area.

Temperatures today are expected to warmup ahead of the cold front,
with some aid via compressional warming and downsloping off of the
Ozark Plateau. Highs in the upper 80s to near 90 degrees are favored
for most, though low 90s are most likely in/near the St. Louis metro
area.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 318 AM CDT Wed Aug 26 2026

(Thursday - Friday Night)

Dry weather with low humidity and near to slightly below normal
temperatures are forecast to end the work week thanks to a ridge of
high pressure moving into the mid-Mississippi Valley. Highs each day
are expected to be in the mid 80s, with lows in the upper 50s to mid
60s.

(Saturday - Tuesday)

Ensemble guidance is in good agreement that the mid/upper level
ridge will shift back eastward by late this weekend. This portends
to a return to summertime heat beginning Sunday. Dewpoint (humidity)
levels though look slower to increase, and likely will stay
relatively low until Tuesday. This is when dewpoints may pool closer
to a cold front that may get hung up just to our north. Heat index
values are more likely to approach or exceed the century mark by
Tuesday. All in all, this looks like a fairly typical late August
heat where dewpoints (relative humidity) levels are quite a bit
lower than early to mid summer levels.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1014 PM CDT Tue Aug 25 2026

There are three distinct low chances for impacts through the
period at the local terminals. The first is fog developing
across north-central portions of Missouri. There is a very low
chance that this spreads far enough east-southeast to impact
KUIN, KCOU, and KJEF. If this does happen, fog will dissipate
shortly after sunrise. Secondly, a very weak weather system will
pass south of the local terminals through the morning hours.
There is a low chance (20%) that this system produces scattered
showers and thunderstorms around KCOU, KJEF, KSUS, KSTL, and/or
KCPS. Lightning and reduced visibilities would be the primary
impacts from any convection. Lastly, a cold front sweeping
through the region during the afternoon hours will serve as the
focus for additional scattered showers and thunderstorms. The
coverage of this convection and the low probability of its
occurrence around the local terminals leaves confidence too low
in impacts to include in the TAFs at this time.

&&

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

&&

SHORT TERM...Gosselin
LONG TERM...Gosselin
AVIATION...Elmore