Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0230 PM CDT Fri Jun 27 2025

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SUNDAY ACROSS
PARTS OF THE UPPER MIDWEST...

...SUMMARY...
Scattered strong to severe storms appear possible Sunday from the
central Great Plains into the upper Great Lakes region, with at
least some potential for the evolution of a large, organized severe
storm cluster across parts of the mid into lower Missouri Valley and
central Great Plains late Sunday through Sunday night.

...Discussion...
Stronger westerlies will remain confined to the northern
mid-latitudes, but models indicate further amplification of flow
across the northeastern Pacific into interior North America through
this period.  This is forecast to include building mid/upper ridging
across British Columbia through the western Canadian Prairies and
northern U.S. Rockies, and digging downstream troughing across the
international border toward the Upper Midwest.  As mid-level flow
transitions from westerly to northwesterly across the northern
Rockies toward the middle/lower Missouri Valley, an initially
prominent plume of warm elevated mixed-layer air advecting to the
east of the Rockies is likely to become increasingly suppressed
southward/southwestward into and through the central Great Plains by
early Monday.  Although the main surface cold front may only reach
the Upper Midwest into high plains to the south of the Black Hills,
this may be preceded by a notable wind shift, reinforced by
considerable convective outflow through much of the central Great
Plains into middle Mississippi Valley.

...Central Great Plains into middle/lower Missouri Valley...
There is a notable signal within the model output that a large
reservoir of moderate to strong potential instability, beneath the
plume of warm elevated mixed-layer air, may provide support for one
or two significant upscale growing clusters of thunderstorms Sunday
through Sunday night.  There remains sizable spread among the
various output concerning where, ranging from near/east of the mid
into lower Missouri Valley to portions of western Nebraska into
Kansas.  Much may depend on the evolution of a possible evolving
cluster of storms, and its outflow, across southern South
Dakota/northern Nebraska Saturday night, and the extent of the
suppression of the elevated mixed-layer by early Sunday, which
remain unclear.

Stronger instability may tend to become displaced to the south of
the stronger westerlies, but modest shear due to veering winds with
height, coupled the thermodynamic profiles, characterized by
unsaturated lower/mid-levels, with steep lapse rates and large CAPE,
seem likely to become supportive of organized convection with strong
cold pools capable of producing swaths of strong to severe surface
gusts.

Severe probabilities will probably need to be upgraded once
lingering uncertainties become better resolved.

...Upper Midwest...
If early period convection does not impact subsequent
destabilization near/ahead of the southeastward advancing frontal
zone, it still appears possible that deep-layer shear and forcing
for ascent downstream of the digging short wave trough could support
scattered strong to severe storm development in a corridor across
southwestern through northeastern Wisconsin and portions of adjacent
states.

..Kerr.. 06/27/2025