My oldest daughter has a HUGE house, over 8k sq. ft. with a tornado shelter in a remote corner of the basement that is protected by THREE I-beams and 2 ft of concrete all the way around. Except, the entrance door is wood and opens OUT. I told her she needs a steel door that opens in with some type of comm device to communicate to the outside world. Don’t know what she’s done about it.
We have friends in Ardmore OK and most of them have storm cellars.
Our part of Texas has a tornado occasionally but not like other areas do and ours are small and rarely do much damage.