Trenton seems to fit the model. Two people died there about a block from each other. Ringgold does, too. Death toll there: 8.

In both cases, National Weather Service maps that tracked the April 27, 2011, tornadoes that struck the communities show them reaching peak strength adjacent to higher terrain.

Now, University of Alabama at Huntsville researchers have found that topography is among factors that can influence tornadoes' power.

Read more from mour partners at the Times Free Press.