I suggest a “new” house design to withstand tornadoes. If builders make a domed house like a very large igloo, with one floor above and one or two stories below, it should survive. It may not be beautiful, but its inside could be. At least homeowners won’t have the heartbreak of personal losses and repeated costs with each tornado. The houses should not cost more than a standard one and should save fuel costs in winter. And the house will be there year after year. Best of luck.