"One of the most common injuries that people may sustain during tornadoes, storms or straight-line winds are injuries from falling or flying debris, so it's important to take shelter," said Keli Cain, spokeswoman for the Oklahoma Department of Emergency Management.
But while the number of in-home shelters is growing, most people in small towns and of modest incomes depend on sturdy public buildings like schools, hospitals and courthouses. And more than 60 percent of households have pets.
At city council and campus administration meetings this spring, officials reviewing local emergency plans are again debating the implications of turning animals away.
"People are so attached to their pets, I don't think it's even possible to ban them," said Byron Boshell, director of Security at Oklahoma City's Integris Baptist Medical Center, where people from surrounding neighborhoods come when funnel clouds approach.
Staff members try to herd the pets to the basement garage, away from the patients. But at some shelters, 60 to 70 dogs may be packed in with the people.
Southwestern Oklahoma State University, in Weatherford, used to allow pets into the campus buildings until several bad scenes involving dozens of barking, lunging dogs and other panicked animals.
The animals "were kind of terrified from the storm and also strange people," said Rick Bolar, chief of the campus police.
One of the final straws in Norman's decision to close its shelters came when one family was asked to put its dogs outside to make room for another family that had arrived.
"The adults actually got into fights over that decision and trying to boil down the priority of who should be inside a facility during a storm: a pet or a person. It's a constant fight," Grizzle said.
But holding to the no-pets policy isn't easy because of the chilling consequence — rebuffed people sitting outside in their flimsy cars as the twisters move in.