How about a tornado? A couple of FedEx ATR's went for an unauthorized flight into a ditch at Greensboro, North Carolina.
http://news.bbc.co.uk/2/hi/in_depth/7393030.stm
Interesting question about earthquakes. While infrequent, there is a possibility of severe ones as they are near the New Madrid seismic zone.
I am confident they would have enough warning in the event of a hurricane as the predication capabilities in the U.S. are pretty good. (Katrina wasn't a failure of prediction. It was a failure of ensuring protective measures were adequate, and then ensuring that the emergency response was adequate.)