Hype was building, especially with what happened 11 days before - the massive EF5 tornado in Moore, Oklahoma.
Storm chasers from all around flocked to Oklahoma in the hopes of seeing a tornado, and when storms popped that afternoon, they zeroed in on El Reno, Oklahoma.
What happened as the evening progressed was a stark reminder of how unpredictable the behavior of tornadoes could be.
The tornado that formed grew into a 2.6 mile wide monster - the widest tornado ever observed. 8 people were killed, including three experienced storm chasers.
But what made the El Reno tornado so deadly?
Gabe Garfield is a meteorologist and experienced storm chaser who has done extensive research on this tornado.
He says one of the factors was the tornado's erratic motion.
"The El Reno tornado, last year, it was changing motion over a wide area varying speeds from nearly stationary to over 50 mph and varying direction over 360 degrees," Garfield said.
Another factor was the tornado's incredibly large wind field that made it impossible for those caught in the middle of it to drive away.
"It actually kept them from escaping," Garfield said. "In which case the larger winds, the bigger winds, and the sub-vortices swept over them, and unfortunately resulted in tragedy."
Another possible factor was the high number of chasers following the storm too closely.
The National Weather Service recently released the video El Reno: Lessons Learned from the Most Dangerous Tornado in Storm Observing History, which Garfield helped create, educating people about the dangers of storm chasing and lessons learned in El Reno.
In the video, he discusses how sometimes chasers have a false sense of security when it comes to chasing storms.
"Sometimes people might have a sense of, 'I can do this. I've done this before, no big deal,' and then they get caught off-guard," Garfield said. "And if you don't have a margin of safety large enough to account for the things that you don't know, then it's possible that they can potentially catch you off guard and potentially kill you."
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