This is staggering.
While it is too soon to be sure, based on the meteorological parameters, I think we are going to find that this is the largest number of "path miles" of F-3, F-4, and F-5 tornadoes since the "Superoutbreak" of April 3-4, 1974.
I base that on the fact that the "significant tornado index," which is designed to indicate when tornadoes of F-2 or greater intensity will occur, had the highest numbers I have ever seen yesterday. For comparison, during the recent North Carolina outbreak, the index was running around six. The Good Friday St. Louis today was also around 6. Much of yesterday in Mississippi and Alabama the index was running around 12-14.
Here is a map that shows the geographic extent of the outbreak,
and, here is a map showing the concentration of tornadoes in the South:
I'll have more on this as we learn more through the day today.