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Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0229 AM CDT Thu Aug 25 2022

Valid 271200Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MISSISSIPPI VALLEY SATURDAY AFTERNOON AND EVENING...

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

...Upper MS Valley...
A shortwave trough is forecast to extend from southern Saskatchewan
southward through the northern Plains early Saturday morning. This
shortwave is then expected to progress northeastward, moving through
southern Manitoba and MN and into far northwestern Ontario. A subtle
surface low will likely move northeastward just ahead of the
shortwave, progressing from west-central MN northeastward into far
northwest Ontario throughout the day. 

Ample low-level moisture is expected within the airmass over the
region, with afternoon dewpoints in the mid to upper 60s likely.
Strong heating is also anticipated, with afternoon temperatures in
the mid to upper 80s. These warm and moist conditions will occur
beneath steep mid-level lapse rates, resulting in a moderate to
strongly unstable airmass. The co*bination of modest large-scale
forcing for ascent and low-level convergence along a weak surface
trough amid the favorable thermodynamic conditions is expected to
result in afternoon thunderstorm initiation. 

Warm temperatures at the base of the EML result in some uncertainty
regarding convective initiation, with the potential for some storms
to be elevated north of the surface trough as well. These
uncertainties merit low severe probabilities at this forecast range.
Even so, any surface-based storms that do mature would likely pose a
severe risk. All severe hazards are possible, including tornadoes,
but hail appears to be the primary risk.

...Elsewhere...
Scattered to numerous thunderstorms within the monsoonal moisture
still in place over the Southwest. Isolated thunderstorms are also
expected from north CA/southeast OR into the northern Great Basin as
a co*pact upper low moves across the region. A few storms are also
possible across the central Plains as a convectively augmented
shortwave trough gradually shifts east. In each of these areas,
limited vertical shear and modest buoyancy should keep the severe
potential low.

..Mosier.. 08/25/2022