Each year US Tornadoes keeps a web list of all of the large tornado outbreaks that have occurred. They use a baseline of 20 tornadoes in one event to define what an outbreak is. So far 2017 has had two outbreaks, including the one on January 2 and the one January 21-23. You can come back to this site over the year to see what other outbreaks may qualify for the list. The site is at https://www.ustornadoes.com/2017/01/05/the-largest-tornado-outbreaks-of-2017/.