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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0254 PM CDT Thu Aug 29 2024

Valid 292000Z - 301200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MINNESOTA AND WESTERN WISCONSIN...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE UPPER MIDWEST AS WELL AS THE MID ATLANTIC....

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening over
portions of the Upper Midwest, with a threat for tornadoes, damaging
winds, and sporadic large hail, especially across parts of Minnesota
into western Wisconsin. Other severe storms are expected across the
central Plains and Mid-Atlantic/Carolinas.

...20z Update...
Minimal changes were made to the prior outlook. Thunder
probabilities have been lowered across western parts of the central
Plains behind the cold front. An isolated severe storm will be
possible ahead of the front from the central Plains southward into
the southern High Plains. Moderate buoyancy is supporting a fair
amount of convection with some potential for damaging outflow winds
or marginally severe hail. However, weaker deep-layer shear and
modest large-scale ascent should keep the threat minimal prior to
frontal passage later tonight.

Across parts of the upper MS Valley and Midwest will maintain the
Level 2/3 Slight/Enhanced as is. Scattered storms are ongoing and
expected to increase in coverage through the afternoon and into this
evening. Increasing deep-layer shear and partial heating ahead of
the bands of storms near the cold front should allow for more
robust/organized storms to gradually develop through the remainder
of the afternoon. With the expected convective coverage, storm mode
is trending toward more linear solutions, though moderate deep-layer
shear and strong low-level turning with height may support a few
embedded or semi-discrete supercell structures. Damaging winds are
the primary threat, but occasional large hail and a couple of
tornadoes are possible, especially near the warm front with any of
the more persistent rotating features.

Across the central Appalachians and Mid Atlantic, no changes were
made to the severe risk area. The predominate hazard remains a few
multi-cell clusters capable of damaging wind gusts. Convection
ongoing over the higher terrain in western VA/PA and WV should
gradually expand eastward, with some potential for consolidating
outflow. See the prior outlook for more information.

..Lyons.. 08/29/2024

.PREV DISCUSSION... /ISSUED 1147 AM CDT Thu Aug 29 2024/

...Upper Midwest/Central Plains...
Have upgraded portions of central/eastern Minnesota into western
Wisconsin to Enhanced Risk for a perceived greater aggregate severe
risk, highlighted by a transition to an increased damaging wind
potential by evening.

An upper-level trough will continue generally east-northeastward
from southern Saskatchewan toward Manitoba and eventually far
northwest Ontario late tonight, with southern-peripheral height
falls and moderately strong southwesterly winds aloft as far south
as the far eastern Dakotas and Minnesota into Wisconsin. Scattered
thunderstorm development is expected by mid-afternoon along the
front from northern Minnesota south-southwestward into southwest
Minnesota and the central Plains including eastern/southern Nebraska
into northwest Kansas. 

The most severe-favorable ingredients are expected across
central/southern Minnesota, where 2500-3500 J/kg MLCAPE will
coincide with 30-40 kt effective shear. Some initial supercells can
be expected with large hail. Tornado potential should be maximized
across central Minnesota and possibly far western Wisconsin in
vicinity of a weak surface wave/warm front-related triple point,
where low-level moisture/SRH will be maximized, somewhat analogous
to the South Dakota/North Dakota border vicinity yesterday late
afternoon and early evening. Storms should otherwise steadily grow
upscale by early evening, with storm mergers leading to quasi-linear
segments and possible bows with an increased damaging wind potential
across Iowa, and especially eastern Minnesota into western
Wisconsin.

...Carolinas/Mid-Atlantic including parts Virginia/Pennsylvania...
Scattered multicell thunderstorms are expected to form this
afternoon, offering isolated damaging wind gusts and marginally
severe hail. This activity will develop in a plume of rich low-level
moisture, with lower-elevation surface dewpoints in the upper 60s to
low 70s F. That, along with diurnal heating offsetting modest
mid-level lapse rates, should support MLCAPE in the 2000-3000 J/kg
range.