This visualization shows one of the largest simulations ever computed for Hurricane Katrina. The National Center for Atmospheric Research computed a complex numerical model that evolves the conditions of the storm resulting in a simulation that closely matches the actual event. The visualization was created by the Advanced Visualization Laboratory at the National Center for Supercomputing Applications, University of Illinois. The visualization shows the storm’s evolution over a 1.5 day portion of the simulation, as the storm gains energy over the warm ocean. Volume-rendered clouds show abundant moisture. Trajectories follow moist air rising into intense “hot tower” thunderstorms, and trace strong winds around the eye wall; rapidly rising air is yellow, sinking air blue. The sun, moon, and stars show the passing of time. The visualization highlights Katrina’s awesome power and fierce beauty.