The tornado that hit Joplin, Missouri, last night was the deadliest single tornado since 1953—the only one since that year to make a list of the 20 deadliest single tornadoes (not outbreaks) in U.S. history. News reports are calling it an EF-4 (for the fascinating backstory behind Ted Fujita and the Fujita scale, see here), the second-highest category on the Enhanced Fujita scale, though meteorologist Jeff Masters sees evidence, specifically torn-up pavement, that suggests the tornado may have been an EF-5.
Dr. Masters also found what he calls "the most remarkable audio I’ve ever heard of people surviving a direct hit by a violent tornado." It is remarkable, though you should be warned that it’s harrowing, more so than any storm chaser footage I’ve ever seen. In fact, the near-complete lack of visuals is part of what makes the recording so terrifying.
Here’s a NOAA satellite image showing what the storm system looked like from above as the tornado was forming: