In the worst tornado outbreak in over half a century, Mississippi and Alabama are ravaged by hundreds of twisters. Towns are wiped clean off the map, and hundreds of people lose their lives.

On the first chase of the year, there's a storm headed toward downtown St. Louis. While Tim Samaras and his team chase too close to the beast, Reed Timmer's team is on the verge of falling apart.

Reed Timmer and his team take the day off, but when Sean Casey's team scores a victory in Reed's own backyard, the meteorologist vows to chase with a vengeance. Meanwhile, Tim Samaras grows more cautious chasing storms in Kansas.

A tornado outbreak threatens to wreak havoc in Reed Timmer's backyard. Sean Casey's team follows their navigator's bold prediction, and tension threatens to derail Tim Samaras' chase on a huge day.

On the last chase of the season, Reed Timmer's team chases a monster tornado for a radar intercept, and Tim Samaras' team has one last chance to deploy their probe in its path.