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.

Potent storms were hitting the northern U.S. on Monday with a potential to turn into a derecho with hurricane-force winds. Tornados and large hail could also be a threat.

A fierce and long-lasting line of severe thunderstorms called a derecho is likely to tear across the Northern Plains to kick off the week, causing damage to trees, structures and