048
ACUS01 KWNS 090101
SWODY1
SPC AC 090059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Fri Aug 08 2025

Valid 090100Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN SD
INTO MN AND NORTHWEST WI...AND ALSO ACROSS SOUTHWEST SD AND WESTERN
NE...

...SUMMARY...
Scattered severe thunderstorms with damaging winds, large hail, and
possibly a tornado are expected to develop this evening and tonight
across parts of the Upper Midwest and the central High Plains.

...Eastern Dakotas into MN/northwest WI...
Scattered to widespread storm development is still expected later
this evening from the far eastern Dakotas into MN, as a seasonably
deep mid/upper-level shortwave trough and attendant cold front
impinge upon a strongly unstable environment. A few supercells could
evolve initially within a moderately sheared environment, with a
threat of hail and possibly a tornado. Deep-layer flow/shear
generally parallel to the front will likely result in a quick
transition to a cluster or linear mode. This could lead to an
increasing threat for damaging wind, though there may be some
tendency for convection to become slightly anafrontal with time.

Guidance suggests the greatest relative threat for more organized
upscale growth will be from central into northeast MN, along a
diffuse surface boundary. The late timing and the effects of
nocturnal low-level stabilization results in some uncertainty
regarding the magnitude of the severe-wind threat, but a swath of
damaging wind remains possible into the overnight hours.

...Central Plains vicinity...
Development of a supercell or two remains possible this evening
within a post-frontal regime from southwest SD into western NE,
though coverage remains uncertain. Elongated hodographs would
support a hail threat with any sustained cells, with localized
severe gusts also possible.

Some recent runs of the HRRR suggest post-frontal development
overnight across parts of southeast WY and northeast CO. While this
scenario is uncertain, the environment will be favorable for
isolated hail and strong gusts if storms develop.

A nebulous but potentially organized severe threat also remains
evident overnight across parts of NE into northern IA, within a
favorably unstable and modestly sheared environment. Strong elevated
storms will be possible as the front moves into the region, with
some threat for hail and localized damaging winds. Any organized
clustering could result in a locally greater damaging-wind threat.

...Northern Lower MI...
A strong storm or two remains possible this evening across northern
Lower MI, before convection wanes later tonight as CINH increases.
Steep lapse rates, moderate buoyancy, and around 30 kt of effective
shear (as noted on the 00Z APX sounding) could continue to support a
threat of isolated hail and strong gusts before storms diminish with
time.

..Dean.. 08/09/2025

$$