Bootheel tornado (Courtesy: Max Olson Chasing)

The National Weather Service has updated the survey information on the deadly tornado that hit Missouri’s Bootheel on December 10th.

The strong storm system moved across the central and southern U.S. involved 66 confirmed tornadoes on December 10th and 11th.

In all, the quad-state supercell thunderstorm lasted nearly eight hours on a 350-mile path.

Max Olson has been chasing storms for 15 years and says it’s the worst one he’s seen.