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.