ACUS11 KWNS 152055
SWOMCD
SPC MCD 152055=20
IAZ000-MNZ000-NEZ000-SDZ000-152300-

Mesoscale Discussion 0725
NWS Storm Prediction Center Norman OK
0355 PM CDT Fri May 15 2026

Areas affected...portions of eastern NE into western/central
IA...and southern MN

Concerning...Severe potential...Watch likely=20

Valid 152055Z - 152300Z

Probability of Watch Issuance...80 percent

SUMMARY...Severe thunderstorm potential is increasing this
afternoon, and convective initiation is expected over the next
couple of hours. Large hail to 3 inches diameter, scattered damaging
wind gusts, and a tornado or two will be possible through evening.
Watch issuance is likely.

DISCUSSION...Boundary layer moisture continue to spread northward
this afternoon across the Mid-MO Valley, with dewpoints in the low
60s F now across southeast NE and southwest IA. Strong heating into
the mid 80s to low 90s amid steep midlevel lapse rates near 8.5 C/km
per 18z region RAOBs is contributing to weak to moderate
destabilization across the region. Deepening cumulus is noted ahead
of a surface front across northeast NE into northwest IA and
southern MN. Further south, midlevel cumulus atop a capping
inversion is also deepening. This suggests large-scale ascent is
increasing and beginning to overspread the area. Thunderstorm
initiation is expected within the next couple of hours.

Effective shear greater than 40 kt across the region and vertically
veering wind profiles suggests initial development will rapidly
organize and a few supercells are possible. Given very steep lapse
rates and moderate to strong instability, large to very large hail
is possible with this initial activity. Steep low-level lapse rates
and modest boundary layer moisture will also support damaging gusts.

With time, convection is expected to grow upscale into a more linear/forward-propagating storm mode as a low-level jet increases
this evening and the surface front begins to shift southeast. This
will support a swath of damaging gusts across portions of MN/IA this
evening. Given supercell wind profiles and potential for a bowing
MCS, a tornado or two also is possible later this evening as the
low-level jet increases.

..Leitman/Guyer.. 05/15/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4rG6fd9vl7-pT8wQAIo4FSEt24kD5U0o7a3AhXWqQ1hTBWS2VSJThvYic_pR8AtuygGga8FHh= YVcSAN15CnyPUsyYCY$ for graphic product...

ATTN...WFO...DVN...ARX...MPX...DMX...FSD...OAX...GID...

LAT...LON 41009767 42409735 43279621 44039380 43989321 43809261
43489195 43099173 42539206 41429333 40609548 40559648
40609771 41009767=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


=3D =3D =3D
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