The National Weather Service says the tornado that hit Oklahoma yesterday was a top-of-the-scale EF-5 twister with winds between 200 and 210mph. The agency upgraded the tornado from an EF-4 based on what a damage-assessment team saw on the ground. Less than 1% of US tornadoes are this violent. Yesterday's was 17 miles long and 1.3 miles wide, and it lasted about 40 minutes. (One bright spot today is this amazing video showing a homeowner finding her dog on live TV.)
Several meteorologists contacted by the Associated Press used real-time measurements to calculate the energy released during the storm's life span of almost an hour. Their estimates ranged from 8 times to more than 600 times the power of the Hiroshima bomb, with more experts at the high end. As the cleanup continues, the death toll stood at 24 this afternoon.