Severe storms and possible tornadoes are forecast to affect millions of people across the U.S. Midwest this week.
The National Weather Service's Storm Prediction Center said Monday thunderstorms could start in Kansas and Nebraska, which could see hail and flash floods and the possibility of strong tornadoes.
Conditions are right to "favor very large hail, damaging winds, and tornadoes," the agency said in its Monday evening report.
Supercells are expected over the plains states, which the Storm Prediction Center says will increase the risk of tornadoes and hail.
Tornado watches were in effect until 3 a.m. Central Time for portions of Western and central Kansas, South central Nebraska, Northwest Oklahoma and the eastern Oklahoma Panhandle and the northeast Texas Panhandle.
By Tuesday the storms will have reached the Mississippi Valley, Great Lakes and Ohio Valley, where forecasters warn significant hail could fall. Tornadoes may also be a risk. The regions at greatest risk will be Southern Iowa, Northern Missouri and Central Illinois.
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