I live in Oklahoma...tornado alley...tornadoes don't hang around very long...storms last for hours for sure..but it ain't like a hurricane or typhoon where you could conceivably have to hole-up for days.

At the most..a family may have to 'enjoy' the shelter for a period of several hours..possibly multiple times in a day.

In a worst case scenerio..a tornado wipes out the house and piles debris on the shelter sticking us inside(hence a 10-ton bottle jack with some sort of fabricated extension..maybe some blocks to jam the door open and a nail bar or two to pry out)....then we see if any running vehicles are left..or borrow a buddies vehicle and go to motel.

Looters?...Possibly..it ain't unheard of..however the average person around here will most likely be quite helpful in debris cleanup etc.

A gun ain't a bad idea to take down-hole..but I am not leaving one down there as part of the gear(it's unlocked and unsecured).

One possibly needed item I just thought of might be toilet paper!

I do see some really good suggestions..keep them coming so I can sort through it all(the air quality suggestion above needs thinking on)