Oh... and in case you're wondering why I didn't mention basements, it because homes with basements are extremely rare in Texas (I have only see one in 30 years). I gave it some though and realized that it's still worth mentioning since many non-residential building do have basements. If you have a basement, it's not as good as a proper tornado shelter but it is better than anything on the ground floor.

One more thing... If you're outside when a tornado comes, lay flat in a ditch. If you're in your car, get out of the car and lay in a ditch.