SPC AC 040539
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Tue Aug 04 2020
Valid 051200Z - 061200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
NORTHEAST CO...WESTERN NE AND SOUTHEAST WY...
Strong to severe storms capable of strong wind gusts and large hail
are possible Wednesday afternoon and evening over portions of the
central High Plains.
...Central/Southern High Plains Vicinity...
Northwesterly flow aloft will continue over the Plains on Wednesday.
An upper ridge will remain oriented over the southern Rockies
north/northwest to the MT/ID border vicinity while an upper trough
along the Pacific Coast begins to dig southward as it moves inland
late in the period. A weak shortwave impulse is forecast to eject
across the central Rockies ahead of the upper trough during the
afternoon/evening, resulting in weak height falls and increasing
upper forcing. In lower levels, southeasterly upslope flow will
transport modest boundary layer moisture north and west along a
surface trough extending north-south along the central High Plains.
This should allow weak to moderate destabilization during peak
heating, and thunderstorms are first expected to develop over higher
terrain by mid-to-late afternoon. Effective shear greater than 30 kt
amid steep midlevel lapse rates and somewhat long/straight
hodographs will allow for organized convection to be maintained as
it moves eastward off the higher terrain and over the adjacent
Plains. High-based supercells and storm clusters will pose a threat
for locally damaging gusts and large hail through the evening hours.
Inhibition will increase with eastward extent and convection should
weaken during the early overnight hours.
...Portions of eastern ND/SD into southwest MN...
A weak surface boundary will extend from western NE into the eastern
Dakotas Wednesday afternoon/evening. Weak southerly low level flow
will result in some increase in boundary layer moisture, but
guidance varies on the degree of moisture return. Some guidance
suggests isolated storms could develop diurnally near the surface
boundary, but weak shear and modest forcing should limit overall
organization. While a strong storm is possible, the overall threat
appears too conditional/uncertain to include severe probabilities at
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z