Baseball-sized hail pelted parts of Nebraska Tuesday as forecasters warned that severe thunderstorms and tornadoes were heading for the region.
In Omaha, cars jammed streets with residents rushing home as the storm moved in, darkening afternoon skies over the city with ominous clouds, CNN affiliate KETV reported.
The National Weather Service's Storm Prediction Center warned that winds of more than 80 mph could tear through parts of the Midwest in what's known as a "derecho," fast-moving storms that last for hours.
"The derecho is a big wad of storms...that charges ahead very quickly and pushes out a tremendous amount of wind," CNN meteorologist Chad Myers said.
Storms were just gearing up Tuesday evening, Myers said, advising residents to stay indoors. Even if tornadoes don't develop, he said, damage from a derecho can be widespread and severe.
"If you're in Nebraska, Iowa, or Missouri, this is going to be a very long night," Myers said.