I'm very familiar with northern Alabama, as I have visited there often. On April 27, 2011, the northern third of Alabama was ground zero for the worst tornado outbreak since the Super Outbreak of 1974 (which, incidentally, also affected this area). Which brings me to my point:
That area reminds me a lot of the Ozark Mountain region of AR, MO, and extreme eastern OK.
Very hilly, almost mountainous, yet quite prone to tornadoes. I know, I know - tornadoes do in fact strike mountainous areas. That's no secret. But I've never really understood why, as there is just something about being in the mountains that makes me feel safe from it all.
The Huntsville/Decatur area has to be one of the most tornado prone areas in the U.S. Particularly the areas directly north of Huntsville, like Tanner, Athens, and Harvest. A bit further south, the corridor from Jasper to Cullman to Arab is also pretty active. And the area in Georgia, north of Atlanta but south of Hiawassee/Helen is also a notorious tornado belt.