Horrific EF-5 tornado in Moore, Oklahoma: May 20, 2013

Coming on the heels of the highly destructive May 19, 2013 severe weather event in central Oklahoma—which included strong to violent tornadoes in the Edmond, Carney, Wellston, east Norman, Bethel Acres, and Shawnee areas—May 20 began as yet another day with an atmosphere primed for explosive severe thunderstorms in the southern Great Plains. Still, despite everything we understood about the potential that day, what we ultimately experienced was hard to accept. It still is. Early in the afternoon, a supercell thunderstorm erupted in a region of extreme instability, along an outflow boundary leftover from the previous day’s storms. This storm very quickly became tornadic, with an initial tall, sharp-edged, cone-shaped tornado forming over the town of Newcastle—another central Oklahoma town with its own history of damaging tornadoes. As experienced storm chasers, we instantly recognized that the tornado was likely very strong, even while initially observing its slender, early stages from several miles to