ACUS11 KWNS 090727
SWOMCD
SPC MCD 090727
MNZ000-SDZ000-090930-

Mesoscale Discussion 1875
NWS Storm Prediction Center Norman OK
0227 AM CDT Sun Aug 09 2026

Areas affected...northeastern South Dakota and adjacent portions of
Minnesota

Concerning...Severe Thunderstorm Watch 545...

Valid 090727Z - 090930Z

The severe weather threat for Severe Thunderstorm Watch 545
continues.

SUMMARY...Storms could gradually evolve into an organizing cluster,
with some continuing risk for severe hail and, perhaps, increasing
potential to produce strong to severe wind gusts through 3-5 AM CDT.

DISCUSSION...Strong thunderstorm development has been focused within
a narrow corridor east of Mobridge, aided by lift associated with
low-level warm advection/frontogenesis, to the north/northeast of a
weak surface low over central South Dakota. Forcing associated with
a subtle short wave impulse digging within seasonably strong
west-northwesterly mid/upper flow may also be providing support. As
this perturbation progresses southeastward during the next few
hours, the surface low is forecast to weaken with a gradual
southward advancement of the near-surface frontal zone.

Although storms are likely elevated above at least a shallow stable surface-based layer, they have been maintained by inflow of
seasonably high moisture content supportive of large CAPE, beneath
steep mid-level lapse rates associated with a plume of warm elevated mixed-layer air. This moisture, still largely concentrated over central/eastern South Dakota and Nebraska, is forecast to advect
eastward in an evolving plume along the frontal zone across southern Minnesota/northern Iowa through 9-11Z.

As it does, as least some convection allowing-guidance suggests
potential for continuing upscale growth into an organizing cluster,
which may eventually pose increasing potential to produce strong to
severe surface gusts.

..Kerr.. 08/09/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!7w6cR6OxcZ2CAE59szjs3jBwJNk1R6JgZ7YhVct-8mvr-C5ThzbU8wa9FHl0N8mJu10XnKju7FsNKOs3YtzHObAT6Wg$ for graphic product...

ATTN...WFO...MPX...FSD...ABR...

LAT...LON 45709909 45509774 44779624 44039656 43909765 44649925
45150006 45590027 45709909

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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