Above is the derecho criteria found in the definition of a family of downburst clusters, by Fujita & Wakimoto (1981). While a weaker derecho, 2/24/11 falls into Fujita & Wakimoto's criteria. I would also argue it was a fairly progressive derecho, while not the strongest ever. If I wanted to rate it, I would say this derecho was a solid Cat-1, if I tried to rate derechos like the Saffir-Simpson hurricane wind scale rates hurricanes. So just for fun, here is my quick derecho wind scale. This is based off convective gusts, assuming all other criteria are met!
Category - 1: 75 - 95 mph
Category - 2: 96 - 110 mph
Category - 3: 111 - 125 mph
Category - 4: 126-150 mph
Category - 5: 151 mph or greater
150 mph is pushing the top of the possibilities for straight line wind events, so anything over 150mph is considered a Cat-5 in my book of derechos. Again, this was just for fun!
2/24/11 - 258 wind reports