414
ACUS02 KWNS 111730
SWODY2
SPC AC 111729

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Tue Jun 11 2024

Valid 121200Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE UPPER
MIDWEST...

...SUMMARY...
Scattered severe thunderstorms capable of very large hail, damaging
wind gusts, and a few tornadoes will be possible across parts of the
Upper Midwest on Wednesday. The probable time frame for the most
intense storms should be centered on late afternoon to early
evening.

...Upper Midwest...
A relatively complex convective scenario should unfold Wednesday
with multiple rounds of severe potential anticipated. A mesoscale
corridor of level 3-ENH risk may be warranted in later cycles,
likely driven by greater hail probabilities, if spatial confidence
increases.

A fast largely zonal upper jet, initially along the international
border over the Northwest, will spread into ND and northern MN by
early Thursday. This will be coincident with a shortwave trough
moving from the Canadian Rockies to the southern Prairie Provinces.
A surface cyclone should track from southeast SK to along the MN/ON
border by Wednesday evening. In advance of this wave, pronounced
low-level warm theta-e advection will occur from the Great Plains
amid an elevated mixed layer shifting east from the Dakotas and
central High Plains.

At least isolated elevated convection should be ongoing at 12Z along
the periphery of the EML, centered on eastern SD into southwest MN.
Consensus of guidance suggests this activity should persist into the
diurnal heating cycle, centered on southern MN with a threat for
isolated severe hail. Some of this activity may transition to
surface-based character by midday to early afternoon with potential
for an isolated strong wind threat as well. The spatial evolution of
this early-day activity will likely modulate the overall threat,
especially with northeast extent into western WI, where
surface-based destabilization may be limited.

The primary mid to late afternoon scenario should be focused ahead
of the impinging cold front/surface trough in northwest MN to
eastern SD. A confined plume of moderately large buoyancy should
develop by peak heating with MLCAPE reaching 2000-3000 J/kg. The
southwesterly low-level wind profile coupled with gradual veering to
west-northwesterly (and strengthening) upper-level winds will favor
hodograph elongation. Discrete supercells may tend to be more
favored across northern MN initially before clustering into the
evening. A messier convective mode is anticipated with southern
extent, where residual outflow from early-day storms will likely
focus regenerative convection. Tornado potential should be
mesoscale-focused in this regime with enhanced low-level SRH near
the trailing outflow, amid a more deeply mixed boundary layer to the
west/south. This scenario should include embedded supercells within
a southeast-sagging cluster into the evening as low-level winds
become increasingly veered over IA. With greater
buoyancy/instability to the west, the western portion of an evening
cluster/MCS should contain the primary large hail/severe wind threat
before convection wanes overnight.

..Grams.. 06/11/2024

$$