Just prepare like you expect to get hit:

My parents have lived in the same house in West Tennessee for nearly 30 years. In March of this year, a tornado took their back yard out leaving the house with minor damage. Parents were unharmed. Destroyed alot of other property though on the 11 acres the house sits on. They were in the basement when the typical description of what sounded like a "freight train" went by. People never think it will happen to them, but it can.

Simon