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 last time a derecho hit eastern South Dakota, the sky above Sioux Falls turned green, prompting Reddit users to create images of everything from Cthulhu to the Stay-Puft Marshmallow Man rampaging through the city. Here's what happened the last few times derechos have occurred in South Dakota.

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.