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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1236 AM CDT Sat Aug 13 2022

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS REGION AND OVER THE MIDWEST...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
northern High Plains region Saturday afternoon and evening. A few
strong/severe thunderstorms may also develop across the Midwest
during the late afternoon/early evening.

...Northern High Plains Region...

Dominant upper ridge will remain anchored across the High Plains
through the day1 period. This feature will force more meaningful
short-wave troughs to eject across the Pacific Northwest into BC/AB
before turning southeast and approaching the upper Red River Valley.
One of these short waves will glance western MT early in the period
which will ensure a well-defined lee trough holds across eastern MT
into southern SK. Latest model guidance suggests strong
boundary-layer heating across MT into western ND will effectively
remove inhibition, and convective temperatures should be breached by
21-22z. Isolated thunderstorms are expected to develop near the lee
trough where low-level convergence should be maximized at peak
heating. With a southeasterly low-level co*ponent expected to hold
near the MT/ND border, moisture/buoyancy will be maximized across
this portion of the High Plains. Forecast sounding for ISN at 21z
exhibits substantial instability (3100 J/kg SBCAPE) with strong
directional turning and surface-6km bulk shear that would support
organized rotating updrafts. There is some concern for a few
slow-moving supercells across western ND into northeast MT. If these
develop large hail and damaging winds would be a concern.

Otherwise, scattered high-based convection will once again develop
across the higher elevations of eastern ID into southwest MT. This
activity should spread northeast with an attendant threat for mostly
wind.

...Midwest...

Early-morning water-vapor imagery suggests a weak short-wave trough
has topped the Plains ridge and is digging southeast toward the
upper Midwest. This feature will suppress heights a bit during the
day while encouraging a pronounced surface front to advance into
southwest WI-southeast IA during the afternoon. Low-level warm
advection will likely be responsible for early-day elevated
convection along the nose of the LLJ farther northeast but this
activity should not be too robust and likely non severe through the
period. However, a narrow corridor of strong surface heating is
expected ahead of the front and models suggest steep low-level lapse
rates and minimal inhibition along the wind shift by late afternoon.
Given the weak short wave and surface boundary, it appears isolated
thunderstorms could develop shortly after peak heating. Forecast
soundings suggest ample shear/buoyancy for slow-moving supercells.
Have introduced a MRGL Risk across to account for a surface-based
convection along the cold front. Hail/wind are the main hazards but
a brief tornado can not be ruled out.

..Darrow/Squitieri.. 08/13/2022