Storms on Tuesday could bring powerful tornadoes to Plains

This is the Weather Underground forecast for Tuesday, April 26, 2016, for the United States. Showers and thunderstorms are expected over most of the Plains, with severe storms and flash flooding possible. The Northeast and Ohio Valley will also have a chance of rain and storms. Much of the Rockies will have a chance of showers. (Weather Underground via AP) (The Associated Press)

The Kansas University rowing team practices on the Kansas River under threatening clouds as a storm front moves over Lawrence, Kan. early Tuesday morning, April 26, 2016. (Mike Yoder/Lawrence Journal-World via AP) (The Associated Press)

Storm clouds appear over a home near Meers, Okla., Tuesday, April 26, 2016. Strong thunderstorms capable of dropping grapefruit-sized hail and producing a few intense tornadoes popped up across the central U.S. on Tuesday after forecasters warned that millions of people faced a significant danger. (Robert MacDonald via AP) MANDATORY CREDIT (The Associated Press)

School districts and authorities are bracing for the possibility of a severe weather outbreak that could bring powerful, long-track tornadoes and large hail to the Great Plains.

The weather on Tuesday could include heavy winds, tornadoes and hail as large as baseballs or softballs. The Storm Prediction Center in Norman, Oklahoma, says the most dangerous weather will likely take aim at an approximately 70,000-square-mile area stretching from southern Oklahoma to southern Nebraska.

In all, nearly 37 million people from the Rio Grande River in South Texas to Omaha, Nebraska, and the western regions of Missouri, Arkansas and Iowa are at a slight risk or higher of experiencing severe weather Tuesday.

In the east, a separate storm system could bring thunderstorms, strong winds and hail to Philadelphia, Baltimore and Washington, D.C., but the risk of severe outbreaks is low.