Mesoscale Discussion 2196
NWS Storm Prediction Center Norman OK
0537 AM CDT Wed Sep 02 2026

Areas affected...East-central WI into parts of Lower MI

Concerning...Severe potential...Watch unlikely 

Valid 021037Z - 021230Z

Probability of Watch Issuance...20 percent

SUMMARY...Strong to locally severe storms are possible through dawn.

DISCUSSION...A long-lived MCS is moving across east-central WI early
this morning. While there has been some tendency for warming cloud
tops with this MCS, a 51 kt gust was recently noted from Appleton,
WI (KATW), and low-level velocities remain vigorous from the KGRB
radar. If this MCS can persist as it crosses Lake Michigan, it will
begin to encounter somewhat richer low-level moisture and stronger
buoyancy over lower MI, which may help to sustain at least an
isolated wind-damage threat with this MCS through dawn. 

Farther east, discrete cells to the north and northwest of Detroit
have occasionally shown some signs of organization, within a
favorable environment (MUCAPE of 1000-2000 J/kg and effective shear
of 30-40 kt). The longevity of these cells may tend to be limited,
though localized wind-damage and hail cannot be ruled out for as
long as they persist. Later this morning, the favorable environment
across central/eastern lower MI may allow for intensification of the
upstream MCS, or else redevelopment of organized convection with the
attendant MCV.

..Dean/Hart.. 09/02/2026

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

ATTN...WFO...DTX...APX...GRR...GRB...MKX...

LAT...LON   44738761 44718500 44588301 43058234 42668230 42678285
            43118462 43578631 43888823 44738761 

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

Mesoscale Discussion 2195
NWS Storm Prediction Center Norman OK
0504 AM CDT Wed Sep 02 2026

Areas affected...Lower Great Lakes vicinity

Concerning...Severe potential...Watch unlikely 

Valid 021004Z - 021200Z

Probability of Watch Issuance...20 percent

SUMMARY...Some increase in storm coverage and severe potential is
possible with time this morning.

DISCUSSION...Multiple storm clusters are approaching the Lower Great
Lakes vicinity early this morning. The downstream environment
remains generally favorable for organized convection, with MUCAPE of
1000-2000 J/kg and effective shear of 35-45 kt. Large-scale ascent
is generally rather modest, though low-level warm advection may help
to sustain the ongoing storm clusters through dawn. 

Short-term severe potential remains uncertain with the ongoing
storms. The cluster mode and generally modest midlevel lapse rates
are not particularly favorable for hail, while low-level stability
may temper severe-wind potential downstream of the lakes. As a
result, the wind-damage and hail potential may tend to remain rather
isolated. If any of these clusters are able to persist into mid
morning and beyond, then diurnal heating/destabilization may allow
for intensification and an increasing downstream severe threat.

..Dean/Hart.. 09/02/2026

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

ATTN...WFO...BGM...BUF...CTP...PBZ...CLE...

LAT...LON   42417755 41917842 41287970 41088060 41568135 41738154
            41918155 42008147 42088121 42497988 43387910 43957794
            43927743 43667679 43267666 42417755 

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

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0228 AM CDT Wed Sep 02 2026

Valid 041200Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MID ATLANTIC...

...SUMMARY...
Scattered severe thunderstorms, mainly producing damaging gusts, are
expected across portions of the southern Mid-Atlantic on Friday.
More isolated severe storms (with wind and hail) may occur over
parts of the Midwest.

...Synopsis...
Upper ridging will continue over the central and eastern U.S., with
upper troughs meandering over the Interior West and the Northeast. A
broad warm frontal boundary will be draped from parts of the Midwest
to the Atlantic coastline, overspread by deep-layer northwesterly
flow. Multiple embedded impulses will traverse this northwest flow
regime, promoting the development of thunderstorm clusters in the
process.

...Southern portions of the Mid-Atlantic...
The best chance for scattered severe thunderstorms will be across
portions of southern WV to the NC shoreline on Friday. By afternoon,
boundary-layer destabilization along a differential heating zone,
left behind by storms in preceding days, will promote renewed
thunderstorm development. Despite meager mid-level lapse rates, 70+
F surface dewpoints and warm temperatures exceeding 90 F will yield
widespread 2000-3000 J/kg MLCAPE. Given stronger northwesterly flow
aloft, 30+ kts of effective bulk (speed) shear will support
multicells and supercells capable of damaging gusts.

...Portions of the Midwest and OH Valley...
Rich low-level moisture along the warm front (i.e. 70s F dewpoints),
beneath 7-8 C/km mid-level lapse rates, will support 3000+ J/kg
MLCAPE and minimal convective inhibition. While upper support will
be quite subtle at best, strong heating and minimal capping may
support isolated thunderstorm development along the front. Only
Marginal Risk probabilities were introduced given the expected
sparse and brief nature of the severe threat. However, any storms
that mature and become sustained will be capable of producing severe
wind or hail.

..Squitieri.. 09/02/2026

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0344 AM CDT Wed Sep 02 2026

Valid 051200Z - 101200Z

...DISCUSSION...
Upper ridging will prevail over much of the central and eastern
CONUS into the middle of next week. The upper trough meandering over
the Interior West will eventually eject into the northern Plains and
pivot around the upper ridge while another upper trough (currently
along the East Coast) slowly drifts out to sea. As this occurs,
surface high pressure and cooler air will overspread the
northeastern quadrant of the U.S.

In the extended period, the best chance for some severe storms will
be in and around the Carolinas on Day 4/Saturday. A diffuse
differential heating zone will continue to drift south while being
reinforced from storms on previous days. By Saturday afternoon,
heating along this boundary, amid a very moist environment, will
promote damaging gust potential, hence the introduction of 15
percent severe probabilities. 

There is also some hint at an MCS propagating southward across
eastern ND into northern and central MN along a moist and unstable
surface warm front on Saturday as well. While ML/AI calibrated
guidance consensus is beginning to elevate severe probabilities in
this area, upper support for this feature is quite weak at best,
limiting confidence for the introduction of severe probabilities
this outlook. 

Lastly, the ejection of an upper trough into the northern Plains
early next week (i.e. next Monday or Tuesday) will support surface
lee troughing and the northward advection of rich low-level moisture
beneath cooler temperatures and stronger flow aloft. At least an
isolated severe thunderstorm risk may materialize from this
scenario, but details on timing and placement of key features are
too nebulous for the confident introduction of severe probabilities
this outlook.