935
ACUS48 KWNS 230901
SWOD48
SPC AC 230900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Jul 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
Medium-range guidance continues to indicate that initially zonal
westerlies near the central Canadian/U.S. border will undergo
considerable amplification by the early to middle portion of next
week.  This is forecast to occur as a significant mid-level low digs
southeast of the Aleutians, before gradually pivoting eastward and
northeastward across the northeastern Pacific.  To the east of
building downstream ridging across the Canadian Prairies, another
significant low emerging from the Arctic is forecast to dig into and
across the Hudson Bay vicinity.  Before broad cyclonic flow to the
south of this latter feature encompasses much of the Upper Midwest
and Great Lakes through Northeast by the end of the period, a
prominent mid-level high may redevelop west-northwest of the
Southeast through central Great Plains.

As this regime evolves, it appears that a plume of elevated
mixed-layer air emerging from the Intermountain West will contribute
to steepening mid-level lapse rates across parts of the northern
Great Plains, then eastward and southeastward beneath increasingly
northwesterly mid-level flow across the Upper Midwest/Great Lakes
and parts of the Ohio Valley.  Beneath this regime seasonably high
boundary-layer moisture content northeast of the middle and lower
Missouri Valley likely will contribute to moderate to strong
potential instability.

Based on the latest ECENS and GEFS, rising mid-level heights are
forecast within broadly anticyclonic flow across the northern Great
Plains and Upper Midwest, through the international border vicinity,
on Saturday.  There appears a general signal that a subtle
perturbation may progress through this regime, across the
Minnesota/Wisconsin vicinity, Sunday through Sunday night.  As it
does, the environment could become potentially conducive to the
evolution of a substantive organized convective system, before
mid-level heights begin to gradually fall across the upper Great
lakes into Upper Midwest during the early to middle portion of next
week.  This could be accompanied by continuing potential for renewed
strong to severe thunderstorm development, with a tendency to
propagate eastward and southeastward into the Ohio Valley and
possibly parts of the Northeast.  However, much of this may
significantly depend on interacting sub-synoptic developments with
low predictability in the extended range.

..Kerr.. 07/23/2025