A tornado touches down near Alpena, S.D., June 18, 2014.
A tornado is spotted near Alpena, S.D., about 15 miles southwest of Wessignton Springs, June 18, 2014.
Connor McCrorey/TVNweather.com/AP Photo
Two tornados approach Pilger, Neb., June 16, 2014. The National Weather Service said at least two twisters touched down within roughly a mile of each other June 16, 2014, in northeast Nebraska.
Eric Anderson/AP Photo
A tornado touches down in Nebraska, June 17, 2014.
A tornado touches down near the border of Wilcox and Hildreth, Neb., June 14, 2014.
A tornado touches down on a reach before heading towards Watford City, N.D. in this photo provided by Jill Helmuth, May 26, 2014.
Jill Helmuth/AP Photo
Storm clouds can be seen forming just south of McPherson, Kan., May 11, 2014.
Travis Heying/The Wichita Eagle/AP Photo
An image of a "firenado" in Chillicothe, Mo., May 7, 2014.
A tornado touches down in a field in Akron, Colo. during a severe weather outbreak, May 7, 2014.
Matt Detrich/The Indianapolis Star/AP Photo
A scene from the tornado in Decatur Ala., April 28, 2014.
Courtesy Allan Detrich
Katie McCoy posted this image on Twitter with this caption: "@mikebettes tornado that touched down here in Southeast KS!," April 27, 2014.
Bryce Matthews, bmatthews94, posted to Instagram, this photo of a tornado happening in Knox County, Ind. The photo was taken from Gibson County, Ind., Nov. 17, 2013.
A funnel cloud is pictured from the city of Kasukabe over the city of Koshigaya in Saitama prefecture, north of Tokyo, Sept. 2, 2013.
Ayame Tajima/AFP/Getty Images
A tornado over Songhua river in Daqing, northeast China's Heilongjiang province, Aug. 19, 2013. The tornado was followed by a hail storm, local media reported.
A tornado on the ground in the Belmond, IA area. Severe weather updates as Midwest tornado warnings remain in effect for June 12, 2013.
A tornado is seen above Marina Baie des Anges in Nice, France, June 9, 2013.
Valery Hache/AFP/Getty Images
A tornado touches down near El Reno, Okla., May 31, 2013, causing damage to structures and injuring travelers on Interstate 40.
Chris Machian/The Omaha World-Herald/AP Photo
The funnel of a tornadic thunderstorm almost touches the ground near South Haven, in Kansas on May 19, 2013.