ACUS01 KWNS 281227
SWODY1
SPC AC 281225

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0725 AM CDT Mon Jul 28 2025

Valid 281300Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND TONIGHT OVER PORTIONS OF EASTERN SOUTH DAKOTA AND SOUTHWESTERN
MINNESOTA....

...SUMMARY...
Numerous severe thunderstorms capable of widespread damaging winds
are likely across portions of the northern Plains, with several
gusts expected to exceed 75 mph. A few line-embedded tornadoes and
instances of severe hail may also occur. Widely scattered storms may
produce severe wind and hail over portions of Montana.

...Northern Plains...
A convectively active afternoon and evening is expected across parts
of the Dakotas/MN/IA/WI, where numerous intense thunderstorms are
expected.  An overnight MCS has temporarily stabilized/modified the
air mass across much of MN/IA.  A consensus of model guidance
appears to have handled this scenario well, and depicts rapid return
of low-level moisture and heating across this region by
mid-afternoon.  Meanwhile upstream in eastern MT and western ND/SD,
a subtle shortwave trough will top the ridge and spread large scale
forcing into the region, leading to scattered thunderstorm
development.  Very steep mid-level lapse rates are in place across
ND/SD, where easterly low-level winds and evapo-transpiration will
help surface dewpoints to rise to near 70F.  Forecast soundings show
extreme instability will develop (MLCAPE values over 6000 J/kg)
aiding in rapid intensification of supercells across central SD.
Large hail, damaging winds, and a few tornadoes may occur with this
early activity.

The most likely scenario for evening convective activity continues
to be for an organized and fast-moving linear MCS to develop and
race eastward across eastern SD into parts of MN/IA.  One or more
corridors of widespread/significant wind damage are expected,
possibly achieving derecho criteria.  Have extended the ENH/SLGT
risk areas a little farther east into parts of MN/IA/WI, where a few
overnight CAM solutions suggest the bowing complex persists before
weakening late tonight.

...Central MT...
Easterly low-level winds across MT will advect moisture westward
into the mountains, where scattered thunderstorm development is
expected by late afternoon.  These storms will spread into central
MT during the evening, with sufficient CAPE and vertical shear for a
risk of large hail and damaging wind gusts.

..Hart/Grams.. 07/28/2025

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