The April 2011 tornado Superoutbreak was made even worse by the lay of the land, according to a recently published report.
Conditions for a long outbreak over hundreds of miles were nearly perfect from April 25-28, 2011, and when the storms finally cleared, more than 350 tornadoes were spawned, according to a press release on the study from the University of Alabama in Huntsville. However, features across the land ravaged by the twisters might have made strong tornadoes even more violent.
"The indications are that gravity waves, topography and surface roughness each played at least some role that day in creating tornadoes or making them more powerful," said Dr. Kevin Knupp, director of the Severe Weather Institute — Radar and Lightning Laboratories (SWIRLL) at The University of Alabama in Huntsville (UAH), in the press release.
Knupp has studied the effects of topography on tornadoes in the Deep South for decades and found surface roughness can make twisters stronger in the region slammed by the 2011 Superoutbreak, AL.com reports. Additionally, surface roughness is non-existent in the Plains, so a similar event in that region wouldn't be made worse by that trait.
The study has been accepted to be published in the Bulletin of the American Meteorological Society, according to the UAH press release.
There are other ways tornadoes can be worsened by the areas they hit, said Dr. Greg Forbes, severe weather expert at The Weather Channel.
"Terrain can affect the tornado frequency in the Southeast in at least two ways," said Forbes. "Sometimes, a shallow layer of cool air gets trapped east of the southern end of the Appalachians and can result in a stationary front across northern Georgia and northern Alabama that can focus the tornado threat. There can also be localized strengthening of winds and rising motion along the edges of the mountain region."
In the four-day event, more than 360 lives were lost, 2,700 were injured and $4 billion in damage was left behind, according to a Claims Journal report.
MORE: A Look Back at the 2011 Superoutbreak
A soda machine is seen in debris in the Holt neighborhood of Tuscaloosa, Alabama May 1, 2011. (MANDEL NGAN/AFP/Getty Images)