I just saw on a Reuters article that it was categorized as a T04 - I'm not familiar with that scale but it's 0-10, so 4 is pretty decent. I went through this (http://en.wikipedia.org/wiki/Andover,_Kansas_Tornado_Outbreak) when I was 12. I've been in countless smaller ones, huddled in basements and crawlspaces. They're scary but they seriously indoctrinate the people there on disaster preparedness starting in grade school.

I was always more scared of the sounds of the sirens - in Kansas they just reassigned the old air raid sirens for the tornadoes. They go off when one has been sighted on the ground.