273
ACUS11 KWNS 040840
SWOMCD
SPC MCD 040840
MIZ000-OHZ000-INZ000-041045-

Mesoscale Discussion 2231
NWS Storm Prediction Center Norman OK
0340 AM CDT Fri Sep 04 2026

Areas affected...Portions of southern lower Michigan

Concerning...Severe potential...Watch possible

Valid 040840Z - 041045Z

Probability of Watch Issuance...40 percent

SUMMARY...An organizing convective cluster/MCS may produce severe
wind gusts or some hail overnight and continuing into the morning. A
Watch is possible but uncertain.

DISCUSSION...Recent radar trends with a convective cluster over
eastern WI point toward organization into an MCS potentially capable
of severe gusts and hail in the coming hours. Continued low-level
warm air advection at the nose of a 30-40 kt low-level jet has
supported an increase in convective coverage across eastern WI where
cloud top cooling has been noted. This has likely strengthened a
preexisting cold pool with the lead elements of this convective
complex. These storms will cross the lake and move into lower MI in
the next 1-2 hours. The air mass downstream remains moderately
unstable and sheared aloft south of a warm front. Despite the
buoyancy likely being elevated above the immediate surface stable
layer, the environment is more than sufficient to maintain
intensity/organization of the ongoing storms. This suggests severe
wind gusts and some hail are possible as convection moves across the
lake, into lower MI and eventually OH/IN later this morning.

It remains unclear if the stronger gusts from this cluster will make
it to the surface. The strengthening cold pool, more organized
linear mode and recent CAM guidance suggest it`s possible. Given the
potential increase in severe threat, conditions are being closely
monitored for a Severe Thunderstorm Watch.

..Lyons/Mosier.. 09/04/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CLE...DTX...IWX...GRR...

LAT...LON   42038339 41908336 41758348 41708376 41678439 41688524
            41848593 42058645 42178672 42528707 42898733 43118731
            43338722 43608706 43688651 42258366 42038339

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN