Today marks the 5 year anniversary of the incredibly deadly Joplin MO tornado. Over 150 people died in that storm alone, and in the outbreak that included it, an unprecedented 1,691 tornadoes claimed 553 lives in all. NOAA has published two documents describing the storm outbreaks.
NOAA has put together a photo book of the outbreaks at https://www.noaa.gov/photo-story-americas-deadliest-year-for-tornadoes-2011. It describes how NOAA predicts and deals with severe weather impacts and has several good images of the tornadoes through satellite and radar.
A second web article by Dr. Kathryn Sullivan, NOAA administrator, describes the string of outbreaks in more detail and with some additional spectacular images here.