702
ACUS03 KWNS 101928
SWODY3
SPC AC 101927

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 PM CDT Sun Aug 10 2025

Valid 121200Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered strong thunderstorms may impact parts of the upper Great
Lakes region Tuesday.  While the risk for severe weather still
appears low, locally strong gusts and hail might still be possible.

...Discussion...
An initially prominent mid-level high centered offshore of the
Pacific Northwest is forecast to become suppressed
west-southwestward across the northern mid-latitude eastern Pacific
during this period, as a consolidating short wave trough digs near
the Canadian Rockies.  As downstream flow trends more zonal, it
appears that a pair of short wave perturbations will consolidate
into a larger-scale short wave trough across northern Ontario into
Quebec by late Tuesday night.  This evolution may include a lead
perturbation continuing to dig across parts of the upper Midwest and
adjacent Great Lakes region, before pivoting east/northeast of the
Lake Huron/Georgian Bay vicinity, in advance of a trailing impulse
digging south of Hudson Bay.  More uncertain, due to greater model
spread, the lead short wave may be preceded across the Lower
Michigan vicinity by an increasingly sheared, convectively generated
perturbation emerging from the central Great Plains.

The evolution of this regime is forecast to include an initial
intrusion of somewhat cooler/drier air, which may maintain identity
while advancing across the Great Lakes region, Midwest and lower
Missouri Valley, before being overtaken by a more substantive
reinforcing cool intrusion across the Great Lakes by late Tuesday
night.  Both fronts will be preceded by the increasingly diffuse
remnants of a slow moving or stalled surface frontal zone extending
from the lower Great Lakes into the southern Great Plains, and
boundary layer moistening/destabilization ahead of the lead front
advancing across Upper Michigan and Wisconsin by late Tuesday
afternoon remains a bit unclear.

Barring complications from lingering convective cloud
cover/precipitation associated with the possible MCV emerging from
the Great Plains, it might not be out of the question that the
environment in a corridor along/ahead of the front could become
supportive of organized thunderstorms with potential to produce
strong wind gusts and hail.  Depending on the strength of the MCV,
which remains unclear due to model spread, wind fields may
strengthen sufficiently to support at least some risk for organized
strong/severe thunderstorm development across Lower Michigan, where
stronger pre-frontal destabilization appears most probable.

If/when these uncertainties become better resolved, it is possible
that severe probabilities in excess of 5 percent, or higher, will be
needed across parts of the Great Lakes region in later outlooks for
this period.

..Kerr.. 08/10/2025

$$