Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0752 AM CDT Mon May 04 2026

Valid 041300Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
KANSAS ACROSS NORTHERN/CENTRAL MISSOURI INTO WEST-CENTRAL
ILLINOIS...

...SUMMARY...
Strong to severe thunderstorms capable of large hail and damaging
wind are possible across portions of the Midwest this afternoon into
tonight. A conditional threat for severe storms with large to very
large hail extends into portions of the central/southern Plains.

...Synopsis...
Early-morning satellite imagery shows a large upper low off the
central CA coast, with an extensive fetch of southwesterly flow
aloft from the base of this low through northern Mexico and the
Southwest States into the southern High Plains. A deep cyclone
exists over central Canada as well. Between these two primary
features, a low-amplitude shortwave trough is currently moving
southeastward across NE. 

Several shortwave troughs are forecast to rotate around the Canadian
cyclone, contributing to some deepening and eastward progression. An
associated surface low, currently over northwestern Ontario, will
move eastward as well. The deepening of the upper trough across the
northern Plains and progression of the surface low will force a cold
front southward/southeastward across the Upper Midwest and Middle MO
Valley by this evening, and through the central Plains, and Lower MO
and Mid MS Valleys by early tomorrow. Increasing low-level moisture
is anticipated ahead of this cold front, supporting the potential
for thunderstorms as this front interacts with this moisture and
associated buoyancy.

...Eastern KS into Mid MS Valley and Lower MI...
Thunderstorm development is anticipated during the afternoon, both
along the front, which should extend through southern WI and
eastern/southern IA, and within the warm-air advection regime ahead
of the front. Thunderstorms along the front will initially be
displaced north of the better shear and buoyancy, so somewhat
transient updraft structures and/or frontal undercutting will likely
limit storm severity. Even so, high cloud bases and a deeply mixed
boundary layer could result in a few strong gusts. Later in the
evening, more storm development appears likely on the front as it
moves into eastern KS and northern/central MO. Here, stronger shear
and buoyancy should support more robust updrafts and a relatively
higher probability for severe storms. Large hail is the primary
risk.  

Any thunderstorms that develop within the warm-air advection regime
ahead of the front during the afternoon and early evening should
interact with greater buoyancy (particularly from northeast IL,
northern IL and southern Lower MI where less boundary-layer mixing
could result in slightly higher dewpoints) and moderate vertical
shear. A few stronger, more organized storms are possible in this
area, although weaker upper flow could limit discreteness and result
in a trend towards a more clustered storm mode.  

...Central Kansas into Oklahoma and northern Texas...
A sharp dryline is expected to develop from central KS
south-southwestward into northwest TX. Given the veering surface
winds, convergence along the dryline will likely be modest
throughout much of the afternoon. However, some backing is possible
during the evening as a surface low moves eastward across southwest
KS towards northwest OK. Strong diurnal heating will likely erode
most convective inhibition by the early evening, while steep lapse
rates contribute to moderate buoyancy. These factors could be enough
to force isolated initiation on the dryline from central KS into
northwest TX. Upper-level flow will be strengthening across the
region throughout the period, and any storms that do form will have
ample deep-layer shear to support supercells. Large to very large
hail would be the primary risk early in the convective cycle, with
dry mid-levels also supporting strong downdrafts as storms begin to
weaken and collapse.

..Mosier/Dean.. 05/04/2026