Mesoscale Discussion 1751
NWS Storm Prediction Center Norman OK
0828 PM CDT Sun Jul 26 2026
Areas affected...portions of central and northern Wisconsin into
western parts of Upper Michigan
Concerning...Severe potential...Watch possible
Valid 270128Z - 270300Z
Probability of Watch Issuance...60 percent
SUMMARY...The severe threat may be increasing across portions of
northern WI. If storms can mature and develop into an MCS, a severe
wind swath may occur. A WW issuance may be needed, but this depends
on further development and intensification of storms.
DISCUSSION...A complex mesoscale scenario exists across northern
portions of WI, where there is a conditional risk for supercells
growing upscale into an MCS over the next couple of hours. Storms
within a low-level warm-air advection regime have begun to rapidly
track towards an elongated corridor of strong instability (up to
4000 J/kg MLCAPE driven by 7-8 C/km mid-level lapse rates atop mid
70s F dewpoints), and up to 50 kts of effective bulk shear (shown by
the GRB 00z observed sounding and 01Z mesoanalysis).
Nonetheless, appreciable MLCINH and multiple outflow boundaries
and/or stabilizing lake-breezes also exist across the warm sector in
northern WI, which is also being grazed by a plume of smoke
originating from Canada. All of these factors have the capability of
limiting further convective development. Therefore, it is unclear if
the ongoing storms will intensify and impose a more immediate severe
threat, or if a greater severe threat will manifest from storms that
develop later this evening. Some of the latest CAM guidance,
including WoFs, suggests that the main severe threat will
materialize after 06Z. As such, the short-term severe threat is
highly uncertain, but given the volatility of the ambient
environment, convective trends will be closely monitored for the
need of a WW issuance.
..Squitieri/Smith.. 07/27/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MQT...GRB...DLH...ARX...MPX...
LAT...LON 46469285 46819261 47149215 46969027 46258833 45648785
44898778 44178791 44048820 44118939 44739122 45759260
46469285
MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
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