A rare storm for region

摘要

It's a hurrican. It's a tornado.rnNo, it's a derecho!rnDerechos are most commonrnin the Midwest and GreatrnLakes between May and July.rnThe National Weather Servicernindicates they occur about once every four years in the D.C. area. They often form along the northern boundary of a hot air mass, right along or just south of the jet stream, where upper level winds zip along at high speeds.