Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Mon May 04 2026
Valid 041630Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MISSOURI VALLEY INTO THE SOUTHERN GREAT LAKES...
...SUMMARY...
Scattered severe thunderstorms capable of large hail and damaging
wind gusts 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.
...IL into the southern Great Lakes...
A mid-level vorticity maximum over the lower MO Valley is forecast
to move east across IL through the late afternoon and into IN-OH
tonight. An associated speed maximum at 700 mb will intensify and
overspread IL (40-50 kt) east into the southern Great Lakes while a
pronounced strengthening of 850-mb flow (50 kt) occurs during the
21-03z period. Cold mid-level temperatures (-18 deg C at 500 mb)
will act to offset initially meager moisture. Model guidance varies
considerably regarding moisture quality with ample spread amongst
different model cores/PBL schemes. However, it seems a narrow
corridor of lower to mid 50s surface dewpoints will extend
east-northeast from the lower MO Valley into the southern Great
Lakes by mid to late afternoon. Forecast soundings show weak to
moderate buoyancy (500-1250 J/kg MLCAPE). Morning model guidance
shows widely scattered to scattered storms developing within the
warm conveyor during peak heating as convective inhibition erodes.
Have expanded the Slight Risk farther east into this region to
account for a hail/wind risk with the stronger storms. Uncertainty
remains regarding quality of boundary-layer moisture across the
northern third of IN into northwest OH where hodographs become
enlarged later this afternoon into the early evening. Will
re-evaluate the tornado risk for the 20 UTC outlook if in fact
moisture quality seems sufficient for a focused, short-duration
tornado risk across the aforementioned corridor.
...Eastern KS into the Mid MS Valley...
Thunderstorm development is anticipated during the afternoon along a
cold forecast to extend through southern WI and
eastern/southern IA. 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 to very large hail is
the primary risk.
...Central Kansas into Oklahoma and northern Texas...
A dryline will extend from central KS south-southwestward into
northwest TX by mid afternoon as a surface low evolves near the TX
Panhandle/OK/KS border region. Strong diurnal heating will likely
erode most convective inhibition by the early evening, while steep
lapse rates contribute to moderate buoyancy along the dryline.
Isolated thunderstorms are possible on the dryline from central KS
into northwest TX during the 22-02 UTC period. Veering and
strengthening flow with height beneath 100-kt westerly 200-mb flow
will support supercells. Isolated large to very large hail will be
the primary risk with the stronger storms, although severe gusts are
also possible.
..Smith/Chalmers.. 05/04/2026
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