Tornado Aftermath: Questioning the Tools (Available Structural Engineering Special Issue Only)

In May 1997, several tornadoes hit central Texas. The strongest of these killed 27 people and destroyed about 40 single-family houses on the outskirts of Jarrell, north of Austin. A post-storm damage survey was conducted by the Office of the Federal Coordinator for Meteorological Services and Supporting Research. The results are described and the investigators conclude that the damage can be explained by wind speeds corresponding to an F3 tornado classification rather than the F5 classification assigned to the event by the National Weather Service. The authors believe the classification was due to the failure of the Fukita intensity scale to account explicitly for the dependence of wind speeds causing specified types of damage depending on quality of construction and the basic wind speed at the geographic area. The authors call for a rethinking of the Fujita intensity scale.