SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Thu Jul 21 2022
Valid 231200Z - 241200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER MIDWEST...
...SUMMARY...
Scattered severe thunderstorms should occur Saturday across parts of
the Upper Midwest. A few tornadoes, large to very large hail, and
significant damaging winds all appear possible.
...Upper Midwest into the Great Lakes...
A notable shortwave trough is forecast to progress from the northern
Plains east-southeastward across the Upper Midwest and Great Lakes
on Saturday. A belt of enhanced mid/upper-level flow will likely
accompany this shortwave trough and act to organize thunderstorms
that develop ahead of it through the day. There is reasonably good
agreement in model guidance that a very moist low-level airmass will
be in place ahead of a front across the Upper Midwest Saturday
morning. Steepening mid-level lapse rates and robust heating of this
airmass through the early afternoon should foster moderate to strong
instability. Deep-layer shear will be more than sufficient for
organized updrafts, and supercells with a threat for very large hail
appear possible with initial convective development across MN.
Most guidance also suggests that quick upscale growth into a MCS
will occur Saturday afternoon/evening with eastward extent into
western/central WI and northeastern IA. Given the degree of buoyancy
available, at least scattered damaging/severe winds appear probable
as this mode transition occurs. Some of these winds may be
significant. Have included an Enhanced Risk where MCS development
and propagation appear most likely. Enough low-level shear
associated with a southwesterly low-level jet is also forecast to
support a threat for a few tornadoes. This severe threat should
continue into the Great Lakes region Saturday night, but lesser
instability forecast with eastward extent should keep the overall
severe threat fairly isolated.
..Gleason.. 07/21/2022
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