The storms could be accompanied by hail or damaging winds and have the highest chance of forming on Tuesday evening.

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.

A fierce and long-lasting line of severe thunderstorms called a derecho is likely to tear across the Northern Plains on Monday, causing damage to trees, structures and knocking out power. Storms tracking with the clockwise flow on the northern rim of a heat dome that's bringing another bout of sweltering temperatures to the central U.