Todd Heitkamp, a National Weather Service meteorologist, said the line of storms appeared to coalesce into a derecho around Sioux Falls.

A dangerous derecho is expected to form in parts of the Northern Plains and Upper Midwest on Monday, with wind gusts over 75 mph likely. A moderate threat for severe storms is in place for parts of South Dakota and Minnesota on Monday afternoon into the evening due to the threat of a derecho, a wind storm that can cause significant damage.

The most intense storms, with wind gusts potentially exceeding 75 m.p.h., were forecast for central and eastern South Dakota, southwestern Minnesota and northern Iowa.