ACUS11 KWNS 171905
SWOMCD
SPC MCD 171905=20
ILZ000-WIZ000-IAZ000-172000-

Mesoscale Discussion 0475
NWS Storm Prediction Center Norman OK
0205 PM CDT Fri Apr 17 2026

Areas affected...eastern Iowa into far northwest Illinois and
southwestern Wisconsin

Concerning...Tornado Watch 129...

Valid 171905Z - 172000Z

The severe weather threat for Tornado Watch 129 continues.

SUMMARY...Tornado threat is increasing, with potential for a strong
tornado.

DISCUSSION...A pair of supercells have become more well defined with
the confluence zone across eastern Iowa. The environment near these
cells is within a zone of favorable low-level shear, with easterly
back surface flow and 100-200 m2/s2 0-1 km SRH. Given the equally
favorable thermodynamic environment, potential for tornadoes,
perhaps a strong tornado, is increasing.

..Thornton.. 04/17/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8UB9rybYizSs7gyAEgkAc5VugJELNRa3VTTWeVmVlUCTGqvOv2W18wyapMUbJSNgnDEz3IAct= WVWsT-jwm563bZwCow$ for graphic product...

ATTN...WFO...MKX...DVN...ARX...

LAT...LON 42679069 42269111 41429198 41449142 41928999 42228989
42388980 42778999 42829041 42679069=20

MOST PROBABLE PEAK TORNADO INTENSITY...140-170 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.75-4.25 IN


=3D =3D =3D
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