390
ACUS01 KWNS 170051
SWODY1
SPC AC 170050

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 PM CDT Sat Aug 16 2025

Valid 170100Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN AND CENTRAL SOUTH DAKOTA AND SOUTHERN NORTH DAKOTA...

...SUMMARY...
A small organized cluster of thunderstorms with potential to produce
a swath of strong to severe wind gusts still appears possible across
parts of the central Dakotas later this evening into the overnight
hours.  More sporadic strong thunderstorms with potential to produce
severe wind and hail are possible in a corridor across the Midwest
into Great Lakes vicinity.

...01Z Update...
In the wake of a weakening convective perturbation shifting
east-southeastward through the Great Lakes region, modest mid-level
height rises across eastern portions of the northern Great Plains
will gradually overspread the Upper Midwest and adjacent Great Lakes
region overnight.  In the presence of weak and/or weakening
deep-layer shear, and weak mid/upper support for convective
development, the probabilities for the evolution of a sustained
organized severe storm cluster appear to be lowering.  However, weak
low-level warm advection to the immediate cool side of convective
outflow, and a quasi-stationary frontal zone extending roughly from
west-northwest of the Dubuque IA vicinity into the middle Missouri
Valley, is forecast to contribute to a corridor of increasing
thunderstorm development overnight.  Although mid-level profiles
appear relatively warm, a plume of dry lower/mid-tropospheric air
with steep lapse rates may contribute to a risk for localized strong
wind gusts and some hail in sporadic stronger storms.

Upstream, across the middle Missouri Valley, as a weak mid-level
short wave trough slowly shifts eastward into the western Dakotas,
models continue to suggest that associated scattered thunderstorm
development may gradually consolidate into an organizing cluster,
perhaps aided by lift associated with warm advection on the nose of
a strengthening southerly low-level jet.  As this occurs, although
deep-layer mean wind fields will remain generally weak, modest shear
and thermodynamic profiles with steep lower/mid-tropospheric lapse
rates and sizable CAPE may contribute to potential for the
development of strong to severe wind gusts overnight.

..Kerr.. 08/17/2025

$$