Just check the weather records from the 1880s and see if there were any tornados in the area. If so, don't go. It's that simple.
Seriously, after reviewing the thread in PT's link, I think the policy of leaving it to the guest - putting the responsibility onto the visitor - is a good one. Have a plan for those who want to hunker down, but don't force anyone to. In fact, I might even have a policy of places that I would not allow someone to shelter, just because I wouldn't want the (dare I say) "haunting" legacy that would forever loom over the park from someone having to be dug out of a particular ride area.
That might have saved people in WalMart here in Joplin, and it may not have. My friend was in WalMart before the 2011 tornado, and he almost had to use force to get past employees who were shoving people deeper into the store. His reply to them was, "If I'm gonna die, I'm not gonna die in WalMart!" and he went home before the storm struck. In that case, he may have saved his own life, but for others this strategy would not have worked. Again, it really needs to be the responsibility of the individual and the family, and no business should be held liable for injuries or lives lost, unless they blatantly misinform people. If you force people to comply with your policy, and then tragedy occurs, you will (and perhaps should) be held accountable for their injuries or death.
I used my friend's WalMart story in my novel about the Joplin tornado,
Out of the Wind, which I present in this thread:
