Sky Diary 26 May 2013 Nebraska supercell - 2013-05-26 at 20-59-40

Caption: At this point, it was rotating hard. Photo by Chris Kridler, ChrisKridler.com, SkyDiary.com
Aperture: ƒ/4
Shutter Speed: 1/30
Date: 5/26/13 8:59:40 PM CDT