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.
This is a very rare occurrence to have 3 consecutive days with an F-4 or F-5 tornado. The first time was June 7-9, 1953 and then April 17-19, 1970.
As I write this, there have been 48 tornadoes confirmed during May 18-20, 2013.
Here's a break down on the Enhanced Fujita Scale: