OKLAHOMA CITY - Last year's tornado season wasn't the worst in Oklahoma history, either in the number of twisters or the number of lives taken.
But the deadly barrage that killed more than 30 people scared Oklahomans in a way that previous storms had not, moving them to add tornado shelters or reinforced safe rooms to their homes.
There's just one problem: The surge of interest in tornado safety has overwhelmed companies that build the shelters, creating long waiting lists and forcing many people to endure the most dangerous part of this season without any added protection.
"Pretty much anywhere you go right now, the soonest anyone can install is about mid-June," said Kayli Phillips, who works in sales and accounting at Norman-based Thunderground Storm Shelters. "We're booked solid until then."
Thunderground, which opened about two years ago, is part of a booming new industry that has taken shape as more Americans seek to shield their families from severe weather. The demand intensified last year following the series of deadly twisters in central Oklahoma, where a single tornado on May 20 killed 24 people and destroyed 1,100 homes in Moore.
Since then, Moore residents have added about 1,100 basements or shelters, according to city spokeswoman Deidre Ebrey. In all, the city has an estimated 6,000 shelters or basements.
In nearby Oklahoma City, more than 8,000 storm shelter permits have been issued since May 2013, according to Kristy Yager, a spokeswoman for Oklahoma City. In 2009, just 322 permits were issued.
The 2013 tornadoes "pretty much kept us booked up the entire year," Phillips said.
Abby Brown, a sales manager for Edmond, Oklahoma-based GFS Storm Shelters, said there's always a waiting list for installations, but it generally peaks starting in March, when people begin thinking about the storm season. The company, which has been in business for four years, installs about 175 shelters a month.
"People are thinking about it more. People who have lived in Oklahoma all their lives sometimes may not have ever thought that they needed a storm shelter until last year," she said.
Oklahoma is not the only state where families are confronting their twister fears. After a half-mile-wide tornado hit the Little Rock suburb of Vilonia last month, officials said the death toll of 15 could have been worse if residents had not piled into underground shelters and fortified safe rooms.
Alisa Smith, sales manager for Austin, Arkansas-based Tornado Shelters Systems, said the company is working around the clock to keep up with demand. Sales have doubled since last year, to about 300 shelters. New customers have to wait six to eight weeks for installation, she said.
"I think this tornado scared a lot of mothers," she said. "There were two little boys lost in the Vilonia storm, so I think a lot of mothers are saying, 'Forget those granite counter tops or sunroom, let's put in a shelter.' "
It's not unusual for an episode of severe weather to send demand soaring, said Ernst Kiesling, executive director of the National Storm Shelter Association.
Just as parts of the central United States are seeing an increase now, the South experienced a similar trend in 2011, after twisters killed more than 300, he said.