Among those in storm observing community, the May 31, 2013 El Reno tornado will long be remembered as one of the most dangerous storms we've dealt with. Tragically, eight people died in this tornado, including four storm chasers. This video is an effort to make sure that we don't see a repeat of this tragic situation. It's intended for storm spotters/chasers who have some storm observation experience, but the information is important for anyone.
More information: 2013 El Reno Tornado - Wikipedia