The threat of flash flooding on Sunday afternoon was focused over parts of the Midwest, where flood watches have been posted from Missouri to West Virginia, including the cities of Indianapolis and Cincinnati. Rounds of heavy rain and thunderstorms are forecast to sweep across the Midwest region over the next 24 hours.

Millions of Americans are under weather advisories this week. See which major cities have heat, flood or storm advisories.

Slow-moving storms could bring up to 11 inches of rain, raising the risk of flash floods on Sunday, particularly in Illinois and Indiana, forecasters said.