Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 AM CDT Mon Jul 27 2026
Valid 271300Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDWEST/LAKE MICHIGAN VICINITY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
HIGH PLAINS...
...SUMMARY...
Severe storms capable of strong to severe wind gusts and large hail
are expected across the Great Lakes and Midwest through tonight.
More sporadic occurrences of damaging wind are possible in the
Mid-Atlantic, Tennessee Valley, central High Plains, and southeast
Arizona.
...Midwest/Great Lakes to the Ohio/Tennessee Valleys...
A complex forecast scenario again exists today complicated by
numerous mesoscale factors and well-above-normal short-term guidance
variability. There nonetheless is an appreciable broad regional
severe potential, at least conditionally, attributable to robust or
even extreme source-region buoyancy and an appreciable belt of
northwesterly flow aloft (50+ kt at 500 mb), which could easily
support well-organized wind-producing swaths regionally into the
afternoon and tonight.
A high-moisture-content airmass is prevalent regionally to the south
of a cold front that extends across South Dakota/Minnesota toward
Lake Superior. Several corridors of storms are ongoing early this
morning, including across the western Upper Peninsula of
Michigan/far northern Wisconsin, as well as southwest lower
Michigan, with some uptick in ACCAS/mid-level convection in the
predawn hours across eastern Iowa/far southwest Wisconsin.
Increasing daytime storms, in terms of coverage/intensity/
organization, may stem from, but are not limited to, these early day
corridors. Bouts of large hail will be possible given the degree of
vertical shear/buoyancy, and some tornado risk could exist, but the
most prominent concern would be for damaging wind potential,
particularly if one or more south/southeast-moving
forward-propagating clusters emerge, which currently appear most
probable this afternoon and tonight across eastern Wisconsin/western
Michigan and Lake Michigan vicinity southeastward into Indiana,
western Ohio, and Illinois.
...Central High Plains...
Moist, post-frontal surface flow is expected across much of
Nebraska/South Dakota, shifting from northerly early in the day to
more easterly by the afternoon. Dewpoints will initially be in the
mid to upper 70s F, although strong boundary-layer mixing will
likely result in dewpoints ranging from the upper 50s/low 60s across
the Nebraska Panhandle to the low 70s across eastern Nebraska. This
reservoir of low-level moisture coupled with strong heating and
steep mid-level lapse rates will result in a corridor of moderate to
extreme buoyancy from eastern Wyoming/northeast Colorado/southwest
South Dakota eastward across south-central
South Dakota and much of Nebraska.
Most of the guidance indicates a subtle, convectively augmented
vorticity maximum will progress eastward through the northern
periphery of the Four Corner upper ridge. This should contribute to
thunderstorm development across the high terrain, which would then
progress downstream into a more moist and unstable airmass. One or
more clusters could evolve, but the overall predictability of the
convective evolution is low. That said, environmental conditions
support the potential for strong to severe gusts, including the
potential for some over 75 mph.
...Mid-Atlantic States/Delmarva...
Isolated damaging wind potential will exist during the
afternoon/evening, especially near/east of I-95 in vicinity of a
surface trough, where marginal buoyancy and deep-layer shear could
support a few stronger updrafts/downdrafts.
...Southeast Arizona...
Isolated severe-caliber wind gusts are possible over southeast
Arizona as mid-level moisture and diurnal heating leads to scattered
storms over the higher terrain. Cells are expected to move westward
into warmer temperatures and deeper boundary-layer mixing, with PWAT
over 1.25" and steep low-level lapse rates supporting strong
convective outflows.
..Guyer/Wendt.. 07/27/2026
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