Everything had to come together just perfectly to create the killer tornado in Moore, Okla.: wind speed, moisture in the air, temperature and timing. And when they did, the awesome energy released over that city dwarfed the power of the atomic bomb that leveled Hiroshima. On Tuesday, the National Weather Service gave it the top-of-the-scale rating of EF5 for wind speed and breadth, and severity of damage. Wind speeds were estimated at between 200 and 210 mph. The death count is 24 so far, including at least nine children. The United States averages about one EF5 a year, but this...