ACUS02 KWNS 230452
SWODY2
SPC AC 230451

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1151 PM CDT Tue Jul 22 2025

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THURSDAY INTO
THURSDAY EVENING ACROSS PARTS OF EASTERN IOWA...NORTHERN
ILLINOIS...SOUTHEASTERN WISCONSIN...NORTHERN INDIANA...NORTHWESTERN
OHIO...LOWER MICHIGAN...PARTS OF EASTERN WYOMING...SOUTHWESTERN
SOUTH DAKOTA...THE WESTERN NEBRASKA PANHANDLE...EASTERN COLORADO AND
NORTHEASTERN NEW MEXICO...

...SUMMARY...
One or two organized thunderstorm clusters could develop across
parts of the Great Lakes region Thursday, accompanied by potential
for producing damaging wind gusts.  Additional scattered strong to
severe thunderstorm development is possible near the Rockies, from
eastern Wyoming toward the Black Hills, southward into northeastern
New Mexico.

...Discussion...
A belt of seasonably strong mid/upper westerlies across Ontario
through Quebec is forecast to continue a transition from broadly
anticyclonic to cyclonic during this period, to the south of a
significant mid-level low slowly migrating east-southeast of Hudson
Bay.  On the southern periphery of this regime, an increasing
sheared perturbation, progressing around the northwestern periphery
of an initially prominent mid-level high overspreading the Ohio
Valley, may contribute to mid-level height falls as far south as the
Upper Midwest through Great Lakes region during the day Thursday,
into the Northeast overnight.  Otherwise, mid/upper heights are
generally forecast to remain high across much of the southern
Rockies, and central/southern Great Plains into middle and southern
Atlantic Seaboard.

In lower levels, a segment of a cold front, initially across the
central/northern Wisconsin through Upper Michigan vicinity, appears
likely to advance southeastward across much of the remainder of the
Great Lakes region Thursday through Thursday night.  Southward
across the Missouri Valley into the southern Great Plains, the front
could be reinforced in some locations by convective outflow and
strengthening differential heating, otherwise it may tend to weaken
beneath the warm mid-level ridging.

...Great Lakes vicinity...
Although thermodynamic profiles are likely to be relatively warm,
with generally modest to weak mid-level lapse rates, models suggest
that seasonably high boundary-layer moisture content may still
support sizable CAPE with pre-frontal insolation.  Aided by 20-40+
kt west-southwesterly flow in the 850-500 mb layer, and weak forcing
for ascent ahead of the mid-level trough axis overspreading the
region, the environment may become conducive to the evolution of one
or two organizing clusters with potential to produce damaging wind
gusts, Thursday into Thursday evening.

...Rockies/Great Plains...
Models suggest that peak afternoon mixed-layer CAPE will be a bit
more modest along the remnant surface front across the lower
Missouri Valley and central Great Plains into Texas Panhandle
vicinity, and within moist low-level easterly flow across the high
plains into the Rockies.  Vertical shear is likely to also remain
modest to weak, within rather weak  deep-layer mean flow.  However,
at least modestly steep lower/mid-tropospheric lapse rates may
contribute to thermodynamic profiles supportive of localized
downbursts and developing cold pools with gusty winds in
thunderstorm activity late Thursday afternoon and evening.  Some
hail may also be possible near the higher terrain from north central
Colorado into northeastern Wyoming and southwestern South Dakota.

Given the higher probabilities/coverage of storms indicated by
convection allowing guidance, likely aided by orographic forcing,
and at least somewhat cooler mid-level thermodynamic profiles,
severe probabilities still appear a bit better near the Rockies.
Across the Great Plains into lower Missouri Valley, due to the
anticipated marginal nature and sparser coverage of strong
thunderstorm development, severe probabilities are being maintained
at less than 5 percent.

..Kerr.. 07/23/2025

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