We all know of the violent tornado that hit near Moore, OK on Monday. That was actually the third straight day that region had seen at least an EF-4 Tornado.
That's the first time since June 7, 8 & 9 in 1953 the U.S. has had 3 consecutive days with an F4 or F-5 tornado.
As I write this, there have been 43 tornadoes confirmed during May 18-20, 2013.
17 were EF-0; 12 were EF-1, 2 were EF-2. No EF-3 tornadoes as of now, and 9 aren't rated at the moment.