Sky Diary 20 May 2013 Duncan, Oklahoma tornado - 2013-05-20 at 14-55-16

Caption: As we approached, the storm at Duncan was attaining significant rotation. Photo by Chris Kridler, SkyDiary.com, ChrisKridler.com
Aperture: ƒ/4
Shutter Speed: 1/60
Date: 5/20/13 2:55:16 PM CDT