987
ACUS02 KWNS 151736
SWODY2
SPC AC 151735

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 PM CDT Fri Aug 15 2025

Valid 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR MUCH OF SOUTH
DAKOTA...

...SUMMARY...
Scattered severe thunderstorms are possible Saturday over South
Dakota primarily during the late afternoon through the late evening
period.  Large hail and severe gusts appear to be the primary
hazards with the stronger storms.

...Northern Great Plains...
A mid-level ridge centered over the lower MS Valley/Mid South will
feature a weak disturbance moving from the WY/CO vicinity into the
Dakotas Saturday night.  A residual composite front will remain
draped east-west from the Upper Midwest into western SD, where it
will intersect a lee trough from the central High Plains
north-northwestward into eastern MT.  Although large-scale ascent
will remain fairly weak across the region, isolated thunderstorms
will likely develop in the vicinity of the lee trough and Black
Hills by the late afternoon as convective inhibition erodes.  To the
north of the front, a moist and unstable airmass featuring a
moderate to very unstable boundary layer will develop by mid-late
afternoon.  Model guidance shows a gradual increase in storm
coverage during the early evening over western/central SD.  Ample
directional shear will support effective shear magnitudes 30-40 kt
and storm organization with the stronger storms.  Large hail and
severe gusts appear to be the primary threats.

...Midwest...
A linear cluster of thunderstorms is expected to be ongoing Saturday
morning across parts of the Upper MS Valley/western Great Lakes.
Model guidance differs on the evolution of this potentia
shower/thunderstorm activity, but west-northwesterly mid-level flow
poleward of a mid-level anticyclone centered over the lower MS
Valley, will potentially favor some continuation of storms
downstream across the southwestern Great Lakes.  Models continue to
show a moist/unstable airmass across southern portions of the Great
Lakes.  Although large-scale ascent will remain weak across the
region, regenerative storm development on remnant outflow may yield
a subsequent evolution of a storm cluster but uncertainty remains
high.  Isolated damaging gusts/hail are the main threats with these
storms.

..Smith.. 08/15/2025

$$