Clearpost.online It's your post, so post it!

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1224 AM CDT Fri Aug 26 2022

Valid 271200Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Isolated severe thunderstorms are possible across the Upper
Mississippi Valley Saturday afternoon and evening.

...Upper MS Valley vicinity...

A mid/upper shortwave trough will be located over SK/MB and ND/MN
early Saturday morning. This feature should lift northeast through
the day. Meanwhile, another mid/upper shortwave trough over the
central High Plains will develop northeast toward eastern NE/SD and
western MN/IA by Saturday evening. The initial shortwave trough will
result in areas of showers/thunderstorms that are expected to be
ongoing at the beginning of the period near the MN/WI border. Cloud
cover is expected to linger over the Upper Midwest into parts of the
central Plains. Nevertheless, temperatures are expected to warm into
the 80s, with surface dewpoints in the 60s. A plume of steep
midlevel lapse rates will reside across the region initially, though
forecast soundings indicate capping through mid/late afternoon. As
large-scale ascent increases, capping may sufficiently erode such
that a few surface-based storms could be possible. However, this
remains uncertain. Regardless of storms being elevated or
surface-based, forecast hodographs and effective-shear magnitudes
greater than 30 kt indicate at least marginal supercells will be
possible. Moderate to strong instability also will support vigorous
updrafts, with hail and strong gusts being the main hazards. If
surface-based convection can develop, favorably curved, enlarged
low-level hodographs and moderate low-level instability suggest some
tornado potential also is possible. 

Given uncertainty due to early day convection, persistent cloud
cover, potential for capping/elevated convection, and storm
coverage, will maintain the Marginal risk for now, though an upgrade
to Slight risk may be needed in subsequent outlooks.

...Central Plains/Lower MO Valley Vicinity...

Scattered thunderstorms are expected to develop as the central High
Plains mid/upper shortwave trough progresses northeast through the
afternoon. Areas of strong heating and surface dewpoints in the
low/mid 60s will contribute to modest instability. Weak vertical
shear will limit storm organization, though steep low-level lapse
rates and inverted-v sub-cloud thermodynamic profiles suggest some
strong outflow gusts will be possible. The overall severe threat
should remain limited from thunderstorm clusters, precluding a
Marginal risk at this time.

...Central MT...

A co*pact and intense mid/upper shortwave trough will develop
east/southeast across the northern Rockies on Saturday. Steepening
midlevel lapse rates atop poor boundary-layer moisture will support
at least weak destabilization during the afternoon/evening. Strong
heating will aid in deep boundary-layer mixing, and inverted-v
sub-cloud thermodynamic profiles are evident in forecast soundings.
Increasing midlevel moisture on strengthening southwesterly flow
ahead of the trough will be sufficient for thunderstorm development
over the higher terrain of central MT. As this activity spreads
eastward, occasional strong outflow winds will be possible. Given a
lack of better-quality boundary-layer moisture (limiting
instability), and very high-based and shallow convection, overall
severe potential appears limited/transient.

..Leitman.. 08/26/2022