While it stands in the record books for its size, it's also there for it's deaths. Four storm chasers killed, the first known deaths associated with chasing.
"There's a huge personal element to this," said Dr. Anton Seimon, who is heading up the El Reno survey project.
Now Dr. Seimon and his team of scientists are collecting data from anyone who was there to get a better picture of what happened.
"If you consider the number of people out chasing it and the number of resources, the advanced mobile radars, lightning detection networks, all these different resources pointed at the same storm," Seimon said.
Seimon says this storm is perhaps the best documented storm in history. Hundreds of videos are available, along with still pictures from an incredible number of angles. Observations from chasers like Chris Novy.
"This storm had so many chasers on it, so much video, so many types of observations that it made a unique opportunity to collect everything that was out there through crowdsourcing," Novy said.
Novy is participating in the study, providing his data to help paint a picture of what happened.
"The lessons we're interested in learning here are what were people thinking, why did it right, and why did things go wrong," Novy said.
Seimon's crew has collected neary 70 chaser's data and is processing it now. Their goal: solve mysteries of that day and reveal things about mother nature's fury they never knew.
"How many people were aware they were being engulfed by a huge tornado? As it happened, the answer is actually very few," Seimon said.
If you have pictures or data to contribute, you can submit it here.