ACUS01 KWNS 260536
SWODY1
SPC AC 260534

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CDT Thu Mar 26 2026

Valid 261200Z - 271200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID-MISSISSIPPI VALLEY AND OHIO VALLEY...

...SUMMARY...
Scattered severe thunderstorms are expected late this afternoon and
evening across parts of the Mid-Mississippi and Ohio Valleys. Very
large hail, a few tornadoes, and severe wind gusts will be possible.

...Mid-Mississippi Valley and Ohio Valley...

Early-morning water-vapor imagery depicts a weak short-wave trough
topping the dominant southwestern anticyclone over southern WY.
Latest lightning data supports this with isolated thunderstorms
currently noted from southern WY into the NE Panhandle. 00z model
guidance suggests this feature will advance into the Mid-MO Valley
by 18z, then progress into the Mid-MS Valley by 27/00z. As this
short wave advances east, surface ridging will build south across
the Plains and force a pronounced cold front across much of IA by
early afternoon with the sharp boundary settling south across
northern IL as a weak surface wave tracks toward southern Lower MI.

Deep westerly flow should allow surface temperatures to warm quickly
into the lower-mid 80s south of the front over IL/western IN. Even
so, convective temperatures may struggle to be breached until late
afternoon. Current thinking is upper 50s to near 60 F dew points
should return to this region prior to frontal passage, thus modest
MLCAPE is expected to develop. Forecast soundings suggest weak
capping may hold across the warm sector so it's not entirely clear
how much activity will develop well ahead of the front. However,
strong frontal forcing will easily encourage thunderstorm
development and convection will evolve within a strongly sheared
environment. Profiles favor organized rotating updrafts and
supercells are expected, especially early in the convective cycle.
Given the strength of the front there is an expectation for storm
mergers and line segments to evolve. Very large hail is possible,
especially with early supercell development. As a frontal MCS
evolves, damaging winds are expected to be more common with the LLJ strengthening into the evening hours across the OH Valley. Some
tornado threat also exists with storms that are not undercut by the
surging cold front, both with supercells and within the extensive
frontal squall line. This activity will spread toward the Ohio River
where gradual weakening is expected during the late-night hours.

..Darrow/Chalmers.. 03/26/2026

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