Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Thu Jul 24 2025
Valid 242000Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST/GREAT
LAKES...
...SUMMARY...
Locally damaging thunderstorm wind gusts are possible from parts of
the Great Lakes to the central and southern Plains this afternoon
and evening. Isolated severe storms will also pose a risk of hail
and severe wind gusts over portions of the northern and central High
Plains.
...20z Update...
The previous forecast largely remains on track. Thunderstorm
development is underway across portions of northern IL, which should
intensify and track into northern IN and southern MI through the
evening hours. Severe hail/wind risk probabilities were reduced
across far northern lower MI due to the recent passage of deep
convection and an influx of cooler/lower theta-e air. See the
previous discussion below as well as MCDs #1771 and #1772 for
additional details.
..Moore.. 07/24/2025
.PREV DISCUSSION... /ISSUED 1134 AM CDT Thu Jul 24 2025/
...Northern Lower Michigan...
Ahead of an MCV, a well-organized cluster of storms will pose at a
short-term severe risk across far northern Lower Michigan early this
afternoon, although there is some potential for additional
development southwestward along the front this afternoon.
...Midwest/Lake Michigan vicinity to south-central Plains...
Aside from an MCV nearing northern Lake Michigan, at least one
additional eastward-moving MCV exists across eastern Iowa, nearing
the southwest Wisconsin/northwest Illinois border vicinity as of
midday. Some multi-layer cloud debris still persists, and a
pre-frontal veering of winds (westerly component) has occurred in
some areas. However, heating of a very moist air mass (70s F surface
dewpoints) will lead to strong destabilization (2500-4000 J/kg
MLCAPE) and relatively weak boundary-layer inhibition this afternoon
near/ahead of the front. Most 12z global guidance/HREF members are
more aggressive in the coverage/intensity of convection than morning
HRRR/RRFS/MPAS runs, particularly for northern portions of
Illinois/Indiana into Lower Michigan.
Where deep convection does develop/sustain this afternoon, MCV-aided
enhancement of low/mid-tropospheric flow will support some
well-organized bands/clusters of storms with wind damage as the most
common severe risk across northern Missouri, northern portions of
Illinois/Indiana, into Lower Michigan. A more localized/pulse-type
severe risk is anticipated farther southwest into southern
Kansas/northwest Oklahoma.
...High Plains...
Moderate instability will develop across parts of the
northern/central High Plains this afternoon. Large-scale ascent will
tend to be weak behind a departing mid-level shortwave trough. Even
so, convective development should occur near the adjacent higher
terrain this afternoon. Effective shear of 25-40 kt will support
some updraft organization. Initially discrete cells may pose an
isolated threat for hail. Some outflow amalgamation/mergers could
eventually occur, with a threat of strong to locally severe gusts
spreading eastward into the evening before convection eventually
weakens. Farther south across portions of the southern High Plains,
scattered to numerous thunderstorms are also expected to develop
this afternoon/early evening. Deep-layer shear will remain weak
across this region, but localized strong to severe outflow gusts may
still be possible.
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