Multiple Rounds of Damaging Winds, Large Hail & Isolated Tornado; Upper Midwest; July 31st, 2024

Photo byNational Weather Force

Brief Outlook:

Severe thunderstorms are expected across parts of the Northern Plains, particularly in South Dakota, Nebraska, and Minnesota, from the afternoon into the evening. The main risk with these storms will be damaging winds, large hail, and isolated tornadoes if ingredients align. Please check below for further details.

Region Impacted: Northern Plains and Upper Midwest

States and Cities Impacted: South Dakota (Sioux Falls, Rapid City), Minnesota (Minneapolis, Duluth).

Upper-Level Dynamics:

A broad upper trough with multiple embedded shortwaves will remain in place across parts of the northern Rockies into the central/northern Plains. Enhanced mid-level flow will result in strong vertical wind shear, with values around 40-50 knots in the 0-6 km layer. This setup will support the development of organized storm structures, including supercells capable of producing all hazard types.

Surface Conditions:

At the surface, instability values are expected to reach 2000-3000 J/kg across the region. Low-level moisture, with surface dewpoints in the mid to upper 60s, will contribute to the instability. Effective shear will be sufficient to support supercell development, while steep mid-level lapse rates will promote strong updrafts. Storms are expected to initially be discrete before potentially forming clusters or lines capable of producing large hail and damaging winds. Given the ingredients present, along with cold pools being imminent, more damaging wind gusts in excess of 75 mph, possibly locally stronger, will be possible. There is also a likelihood of an MCS forming and sweeping across the impacted regions. Some cells will also bring the risk of isolated tornadoes due to the favorable shear profiles.

Timing:

There will be initial storms in the morning hours sweeping across South Dakota, with more storms potentially forming ahead of them. Additional storms are expected to initiate by late afternoon in South Dakota and move into Nebraska and Minnesota by early evening, continuing through the late evening. Peak activity will likely occur from late afternoon through the evening in multiple rounds, with the most severe storms occurring during this period. The storms are expected to weaken by late evening as they move into less favorable conditions.

Future Radar Scenario:

Photo byNational Weather Force

Main Impact: damaging winds, large hail, isolated tornadoes and lightning.

Stay tuned for more updates.

Sina⚡⚡

Managing Partner and Lead Forecaster of NWF Innovations & NWF Networks

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