The answer will be a storm-proof safe room built on top of this
concrete structure. It will probably be the size of a large bathroom
and made of steel or concrete for protection against flying debris or
tree falls. It should be capable of being buttoned down and float
upright like a boat should it be dislodged. At that level of storm
intensity there is no longer any consideration of living in it to
guard your property. All you want is to survive the perfect storm and
get the hell out, a stay of less than 48 hours.

Disagreement: If you're going to this length, you should use a more
reasonable figure for time-to-rescue of 7 days. 72 hours
is the figure used for people who are trying to do the best
they can with what's available. 72 hours is what you should
keep in the trunk of your car.