A rare tornado swept through Salt Lake City August 11, 1999, killing one person and injuring more than 70 others. Winds were in the 110150 miles per hour range, and damaged several large buildings in the city's downtown.
Images like these from the Geostationary Operational Environmental Satellites
(GOES) help meteorologists track violent storms.
Animation by Robert Simmon and Craig Mayhew (NASA GSFC)