Lucky Jim, the tornado that hit OKC tore down trees, a school made of brick, most of the houses in it's path, where all you see are splinters of houses. The few trees that are still standing are litterally shredded. The houses are in small pieces spread all over. An EF-5 will tear the tar off roads. This was an EF-4. The box you show would be thrown across a county or two, and if you found the people that used to be in it, they would be smashed like a tomatoe under a heel.
Here in MN, we had a tornado rip through a town just about 30 miles southwest of here. The whole town was gone. Just wood planks here and there. house pieces scattered across miles of farm land. The destruction is unbelievable. Watch youtube. I'm sure people will be putting up videos of the aftermath. It's so dang scary.
Not only does the National Weather Service watch the action on radar, but most communities have weather spotters - Police and citizens that volunteer to watch the clouds. I took the course this last winter and know what to look for, as far as tornadic activity, and the possible build up of it. Then we call in w/ our cell phones to report rotation in clouds, down drafts and up drafts, etc.