530
ACUS03 KWNS 220730
SWODY3
SPC AC 220729

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CDT Tue Jul 22 2025

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THURSDAY ACROSS
PARTS OF EASTERN IOWA...MUCH OF SOUTHERN AND EASTERN
WISCONSIN...NORTHERN ILLINOIS...LOWER MICHIGAN AND ADJACENT PORTIONS
OF NORTHERN INDIANA AND NORTHWESTERN OHIO...

...SUMMARY...
One or two clusters of thunderstorms could develop across parts of
the Upper Midwest into Great Lakes region Thursday, accompanied by
potential for producing damaging wind gusts.

...Discussion...
Models indicate that a notable short wave trough may merge into the
stronger westerlies across Ontario through Quebec, to the south of a
lingering mid-level low slowly progressing east of Hudson Bay.  It
appears that this will be trailed by another increasingly sheared
perturbation, progressing around the northwestern periphery of
initially more prominent mid-level ridging centered near the Ohio
Valley.  This is forecast to lead to gradual mid-height falls across
much of the Great Lakes region through this period, while mid/upper
heights otherwise remain high across much of the southern Rockies,
and central/southern Great Plains into middle and southern Atlantic
Seaboard.

In lower levels, a cold front initially across the Upper
Midwest/Great Lakes region 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 central and southern Great Plains, the front probably will
weaken, but continuing southward advancement beneath the mid-level
ridging remains more unclear.

...Rockies/Great Plains into Great Lakes...
Models indicate that moderate to large potential instability will
develop with insolation Thursday, along the surface front and within
moist easterly flow across the high plains into Rockies.  Stronger
deep-layer mean flow/shear and synoptic forcing for ascent would
seem to favor better potential for organized strong to severe
thunderstorm development across parts of the Midwest into Great
Lakes region.  However, the extent of this potential remains unclear
at this time, as this may still be considerably impacted by
sub-synoptic developments with low predictability at this time
frame.

Steeper lapse rates to the lee of the Rockies and across parts of
the central and southern high plains could contribute to a risk for
severe wind and perhaps hail in developing storms.  However, in the
presence of a generally benign large-scale synoptic environment, any
such activity may remain highly sparse in coverage.

..Kerr.. 07/22/2025

$$