862
ACUS02 KWNS 290601
SWODY2
SPC AC 290559

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sat Aug 29 2026

Valid 301200Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL AND NORTHERN HIGH PLAINS INTO THE UPPER MISSISSIPPI
VALLEY...

...SUMMARY...
At least isolated severe storms, accompanied by mainly a severe wind
and hail threat, are possible across portions of the central and
northern Plains into the Upper Mississippi Valley on Sunday.

...Synopsis...
Multiple mid-level impulses will pivot around an upper ridge that
will gradually progress across the central and eastern CONUS
tomorrow (Sunday). A mid-level shortwave trough will crest the upper
ridge and impinge on the northern Plains while a smaller mid-level
impulse traverses the Great Lakes and a another shortwave trough
ejects into the Atlantic from the Northeast. This upper air pattern
will encourage surface lee troughing over the Plains, accompanied by
appreciable low-level moisture advection. Through the day, colder
temperatures aloft will overspread this low-level moisture,
resulting in increased buoyancy coinciding with an increase in
deep-layer shear and ascent to support at least isolated severe
thunderstorm development. The best chance for any severe storms will
be ahead of a cold front and along the warm front over the
central/northern Plains to the Upper MS Valley.

...Parts of the Upper MS Valley...
Thunderstorms are expected to develop along a diffuse warm front by
late afternoon across far eastern ND into far northeast SD and
western MN. Mid-level lapse rates are not expected to be
particularly steep (e.g. 6.5-7 C/km). However, surface dewpoints
approaching 70 F will contribute to 1500-2500 J/kg of tall and thin
MLCAPE. Coinciding this buoyancy will be a strengthening
southwesterly low-level jet beneath an impinging 500 mb wind
maximum, yielding sizeable curved and elongated hodographs (e.g. 50
kts of effective bulk shear and over 200 m2/s2 ESRH), especially by
sunset. If a couple of supercells manage to develop along the warm
front, isolated severe wind/hail and perhaps a tornado or two could
occur. The potential for poor lapse rates and westward displacement
of the stronger forcing for ascent to the west precludes higher
severe probabilities this outlook.

...Central to northern Plains...
Scattered high-based thunderstorms are expected to develop by mid to
late afternoon as the upper trough impinges on the region. Strong
flow aloft will overspread a dry boundary layer, which will support
relatively fast moving, high-based thunderstorms. Forecast soundings
depict a few hundred J/kg MLCAPE amid elongated, straight
hodographs, so multicellular storms are expected, accompanied by a
sparse severe gust threat.

..Squitieri.. 08/29/2026

$$