Intensifying thunderstorms across the southern and eastern U.S. threatened to unleash dangerous weather conditions.

A spring filled with heavy-hitting weather is ratcheting up once more, as forecasters are warning residents across parts of Texas of "a potentially significant severe threat" Sunday evening. The nasty weather was already moving across North Texas on Sunday morning.

A new workweek is ushering in a new severe weather threat for millions of Americans from the Gulf Coast in the Southeast northward into New York state in the Northeast.