“A multiday severe weather episode,” the National Weather Service’s Storm Prediction Center called a powerful cross-country storm system in their key message this week.

Bringing with it a threat of damaging wind gusts from 60 to 100 miles per hour, hail the size of baseballs, tornadoes and strong thunderstorms, the system is expected to unleash widespread severe weather across the Midwest on Friday before heading into the South on Saturday and passing through the East Coast on Sunday.

While the effects are expected to be significant, Scott Kleebauer, a meteorologist with the Weather Prediction Center, said a storm of this strength is not unusual for this time of year.

“It is a very textbook early spring disturbance,” Mr. Kleebauer said. Winds high in the atmosphere are pulling warm, humid air from the Gulf of Mexico northward, where it will collide with colder air to the north. “That’s going to cause heavy rain and a severe outbreak across the South,” he added.

The initial severe storms are likely to happen Friday afternoon and Friday night, especially across parts of Arkansas, Tennessee, Kentucky, Missouri, Illinois, Mississippi and Alabama.

Forecasters in St. Louis said a dangerous severe weather outbreak is possible, and that these storms will likely move very fast — sometimes reaching the speeds of cars on the interstate highways — potentially catching people off guard and leaving long trails of damage.

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