Visualization of a simulated long-track EF5 tornado embedded within a supercell thunderstorm

• A breakthrough thunderstorm simulation is rendered with high fidelity.
• Cloud model I/O is improved by utilizing buffered HDF5 I/O.
• VisIt and Vapor software tools are used to create high-quality imagery.
• Visualization techniques reveal new flow structures never seen before.

Tornadoes are one of nature’s most destructive forces, creating winds that can exceed 300 miles per hour. The strongest tornadoes are produced by supercells, long-lived thunderstorms characterized by a persistent rotating updraft. The sheer destructive power of the strongest class of tornado (EF5) makes these tornadoes the subject of active research. However, very little is currently known about why some supercells produce long-track (a long damage path) EF5 tornadoes, while other storms in similar environments produce short-lived, weak tornadoes, or produce no tornado at all.Recently, a breakthrough simulation was conducted on the Blue Waters supercomputer in which a simulated supercell produces an EF5 tornado that is on the ground for almost two hours. In this paper we report on the visualizations illuminating the simulation, which elucidate three-dimensional features thought to play an important role in creating and maintaining the tornado. Several obstacles needed to be overcome in order to produce the visualization of this simulation, including managing nearly 100 TB of model output, interfacing the model output format to high-quality visualization tools, and choosing effective visualization parameters.