The weather service said the central U.S. was under threat of severe weather through Tuesday. Thunderstorms were expected in parts of Kansas, Missouri, Iowa and northwestern Illinois, potentially with large hail and damaging winds. Some isolated storms were also possible in the mid-South, the service said.

Tens of millions of Americans stretching from Lincoln, Nebraska, to Baltimore could face strong thunderstorms Monday night through Wednesday, with tornadoes possible in a few states. Southern Iowa, Northern Missouri and Central Illinois faces the largest threat of "significant hail and tornado potential,

Millions could face down severe thunderstorms packing damaging wind gusts, large hail and tornadoes early this week. The most widespread threat for these dangerous storms centers on the central US.