ACUS11 KWNS 251812
SWOMCD
SPC MCD 251811=20
INZ000-KYZ000-ILZ000-MOZ000-252015-

Mesoscale Discussion 1310
NWS Storm Prediction Center Norman OK
0111 PM CDT Thu Jun 25 2026

Areas affected...Eastern Missouri into southern Illinois and
southwest Indiana

Concerning...Severe potential...Watch unlikely=20

Valid 251811Z - 252015Z

Probability of Watch Issuance...20 percent

SUMMARY...Scattered thunderstorms will continue to develop through
late afternoon. Sporadic instances of large hail and damaging winds
appear possible, but will most likely remain too isolated to warrant
watch issuance.

DISCUSSION...Over the past hour, thunderstorms have been slowly
deepening in the St. Louis area and eastward into southern IL. This
activity appears to be driven primarily by a combination of weak
low-level confluence and glancing ascent from a passing upper-level
wave to the north across central/northern IL. Despite the weak
ascent, very moist low-level conditions coupled with continued
diurnal warming are quickly eroding any lingering MLCIN and should
result in scattered to somewhat widespread thunderstorm coverage
from eastern MO to southwest IN over the next several hours. The
moist low-level conditions are also compensating for the otherwise
limited mid-level lapse rates and supporting MLCAPE values on the
order of 2000 J/kg. Recent VWP observations from KLSX are sampling
0-6 km bulk wind values on the order of 20-25 knots, which aligns
well with recent RRFS solutions and suggests some storm organization
is possible, including the potential for transient supercell
structures across southern IL where deep-layer wind shear should be
slightly stronger. However, weak low-level winds will likely promote outflow-dominant convection that may modulate storm lifespans and
favor clustered storm modes. Nonetheless, sporadic instances of
large hail (possibly as high as 1.5 inches) and damaging winds
appear possible through late afternoon based on the convective
environment and output from the past few RRFS solutions.

..Moore/Guyer.. 06/25/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6Ri-YUJZiCRoV0iJi8zCnUjyluLLEPZ1WxQZtxR35FHKJBJc_vOvYYoULMAS87eU2x2ATdBlv= YC4DxOCK_Uu7crsMVs$ for graphic product...

ATTN...WFO...LMK...IND...PAH...ILX...LSX...

LAT...LON 39069079 39218752 39228683 38958657 38688655 38368674
38078709 37948743 37788835 37768971 37859051 38109087
38399105 38849111 39069079=20

MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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