As tornado season ramps up, more people are turning to private home shelters to survive

When a powerful EF-4 tornado ripped through Greenfield, Iowa, last week, TJ Oder, the chief of the town's volunteer fire department, said his house took a direct hit. Still, his family was saved by a private tornado shelter he had installed when he built his residence in 2014.

Oder said that when the twister struck, he was helping to prepare a triage center to treat injured neighbors and get them to hospitals while his family members were hunkered down in his personal shelter.

“My grandmother, my girlfriend and her son, and all my animals were in it, and they all survived when it directly hit my house," Oder told ABC News.

At least four people were killed and 35 were injured in the Greenfield twister, but throughout the area, many lives were saved due to people being close to a public shelter as the twister bore down or having one like Oder just steps away in their own home, officials said.

“A lot of people I've talked to since this happened said that they were going to rebuild and are thinking about putting one in," Oder said.

Craig Ceecee, a meteorologist in Mississippi, said he created the website findyourtornadoshelter.com, which maps out every public tornado shelter available in the nation, while he was a doctoral student at Mississippi State University. He said his dissertation was focused on the availability of public tornado shelters, how much they're used and how they are publicized.

"First, we need to be knowledgeable that they exist, which is basically where the map came from," Ceecee told ABC News. "It's something I feel is important in a lot of areas because many people live in mobile homes, or they don't have basements, or their buildings are a lot weaker than people realize."

Ceecee said his research found that most people didn't know the location of their closest public tornado shelter when a twister hit and were forced to use an interior room or bathroom of their residences to ride out the storm.

Over the past four decades, advances in radar technology and storm modeling have improved tornado warning lead times dramatically, according to the National Oceanic and Atmospheric Administration. In the 1970s and 1980s, the average tornado lead time to get to a shelter following a tornado warning was three minutes.

"Now the average lead time for a tornado warning is 13 minutes," Ceecee said. "That's still not a lot of time."

Ceecee said some tornado-prone areas in rural counties don't have public tornado shelters or are miles away from people's houses, making it too dangerous to attempt to get to during a rapidly approaching funnel cloud.

"You've got to make sure you get there in advance, and it's open because you don't want to be driving when there's a tornado coming your way. A car is extremely dangerous to be in," Ceecee said. "You're better off in the interior room of a home as opposed to a car."

Steve Strum, a meteorologist who lives in Broken Arrow, Oklahoma, in the heart of what's been dubbed "Tornado Alley," said he had a private in-ground tornado shelter installed in his garage about five years ago after his town applied for and received a FEMA block grant to help residents pay for them.

Strum said his prefab shelter, which seats eight people, cost about $3,500 to $4,000, not including installation. He said he received about $2,500 from the FEMA to help defer costs.

"My family is just three of us: My wife, my son and then we have two 90-pound labs. So we can all fit in here," said Strum, who fitted his shelter with battery-operated lights and a portable toilet and stocked it with water, food and other supplies to last more than a day.

But Strum said some smaller shelters cost as low as $2,000 and are available at some hardware stores.

"The biggest cost is actually the installation. The installation costs can be higher than the actual shelter in some cases," Strum told ABC News.

Strum said that while he and his family have had some close calls, they've yet had to use their shelter in a tornado. Before installing the shelter, he said he and his family would put on bicycle helmets and get into an interior room of their home, cushioning themselves with pillows, pads and blankets.

"We mainly got it for those events where you would have a storm in the middle of the night, and you had to take shelter right away," Strum said. "Having something that's easily accessible is kind of why we have it. So we can quickly open the door, and in a matter of seconds be safe from those tornadoes that might hit like 3:00 in the morning and you're sleeping."

ABC News' Jennifer Vilcarino contributed to this report.