Though it is frequently rumored that the only place to survive a tornado as large as an EF-4 or EF-5 is underground, Kiesling said that is not necessarily true.
“Storm shelters above and below ground can be designed for a high degree of safety for the worse-case scenarios,” he said.
All storms certified with the National Storm Shelter Association are tested to be able to withstand winds up to 250 mph. Though tornado winds have been measured at greater than 300 mph, Kiesling said these speeds are only found at the top of a tornado and don’t pose a threat to anyone on ground level. Maximum ground-level winds average around 200 mph, leaving a reasonable margin of safety for shelter occupants.
Shelters are available in a variety of sizes and costs, from a four-person shelter starting around $3,000 to a family-sized shelter for $8,000 to $10,000. Kiesling said the price depends on the kind of shelter, size and quality of finish.
Grizzle said good deals on shelters can frequently be found at home and garden shows. Registering shelters with the city is a way to provide a database of Norman shelters to emergency agencies. In the event of a tornado, emergency crews can locate residents who may be trapped in shelters.
As of June 17, 2,490 shelters were registered in Norman. Grizzle said residents in shelters should be prepared to stay in shelters for 24 hours.
To register a safe room, storm cellar, in-ground shelter or basement, visit ci.norman.ok.us/content/storm-shelter-information.