ACUS01 KWNS 081250
SWODY1
SPC AC 081248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Fri Aug 08 2025

Valid 081300Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE EASTERN DAKOTAS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms are possible later today and tonight
across parts of the northern Plains and Upper Midwest. Scattered
damaging winds, large hail, and a couple tornadoes are possible.

...Northern Plains into the Upper Mississippi Valley...
An extensive MCS which produced numerous severe wind gusts across ND
earlier this morning has recently weakened across northern MN. While
occasional strong to locally damaging gusts may still occur in the
short term, this convection should continue weakening through the
rest of the morning as it moves into a less favorable thermodynamic
environment. In the wake of this activity, an upper trough/low will
continue advancing eastward across the northern Rockies/Plains
towards the Upper Midwest through the period. At the surface, a weak
low over central SD this morning should develop northeastward to
northern MN by this evening, while a trailing cold front advances
southward across the northern/central High Plains.

Outflow from the morning convection may act as a pseudo warm front
and focus for renewed intense thunderstorm development later today
across parts of central/northern MN. The southern extent and
location of this boundary by this evening remains somewhat
uncertain. Even so, a rather moist and strongly to extremely
unstable airmass will be present east of the cold front and south of
the outflow boundary by late this afternoon across the upper MS
Valley. It still appears probable that additional surface-based
convection may develop by late afternoon/early evening across
eastern ND/northwest MN and vicinity as large-scale ascent preceding
the upper trough/low overspreads the warm sector.

While stronger flow aloft may tend to lag the surface cold front to
some extent, there should still be sufficient deep-layer shear to
support organized updrafts, including supercells with some large
hail threat. Given a large degree of boundary-parallel flow aloft, a
quick linear transition should occur this evening, with a greater
threat for severe/damaging winds. A narrow window for a couple of
tornadoes may exist across parts of MN, mainly this evening
along/near the residual outflow boundary where effective SRH may
become locally enhanced with a gradual strengthening of a southerly
low-level jet. Otherwise, the threat for damaging winds may continue
through tonight across parts of the upper MS Valley so long as any
MCS that develops can remain surface based. Given the potential
effects of the ongoing morning convection, confidence in a corridor
of more concentrated wind potential remains too low to include
greater severe probabilities with this update.

...High Plains...
Thunderstorms are ongoing this morning along/north of a cold front
in the western Dakotas. This activity may pose an isolated hail
threat given ample MUCAPE and strong deep-layer shear. The potential
for additional thunderstorms this afternoon/evening across the
central High Plains either along or behind the front in a low-level
upslope flow regime remains unclear. A conditional risk for
supercells with associated large hail threat is still apparent, but
overall coverage of intense convection may remain quite isolated.
Farther south across the southern High Plains, high-based convection
is expected to develop this afternoon within a hot and well-mixed
boundary layer. Deep-layer flow and related shear will generally
remain weak, but outflow-driven clusters may still be capable of
localized severe gusts.

...Northern Lower Michigan...
Similar to yesterday, isolated strong to severe thunderstorms may
develop this afternoon and evening across parts of northern Lower MI
and vicinity, along the northeast periphery of the substantial
reservoir of instability over the central Plains and Midwest. Modest
northwesterly flow aloft will provide sufficient shear for some
updraft organization, with a threat for occasional hail and damaging winds.

..Gleason/Leitman.. 08/08/2025

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