Wednesday, 26 June 2002: 3:30 PM
Urban tornadoes: are the risks growing?
Bob Henson, UCAR, Boulder, CO; and A. Freedman and H. Brooks
During the 1990s, a number of U.S. tornadoes struck in or near downtown areas, causing significant damage and, in some cases, injuries or fatalities. These cases include Fort Worth, TX (March 28, 2000), Nashville, TN (April 16, 1998), Salt Lake City, UT (August 11, 1999), and Miami, FL (May 12, 1997). In addition, the nation's most costly tornado to date struck the suburbs of Oklahoma City, OK (May 3, 1999), and a mesocyclone that passed directly over downtown Washington, DC, produced a killer tornado in College Park, MD, only a few minutes later (September 24, 2001). While there is no evidence that tornadoes are striking urban areas at an increasing rate per square mile as compared to rural areas, the steady expansion of metropolitan areas has produced increasingly larger zones of dense urban/suburban settlement, along with associated highways and office/retail complexes. In addition, many thousands of people assemble in stadiums, outdoor festivals, and the like, most of which have few or no plans for evacuation or shelter in severe weather. The Salt Lake City tornado struck the fringes of a downtown festival, killing one person, and the Nashville tornado struck the 67,000-seat Adelphia Coliseum while it was under construction. In 1987 a tornado passed only a few blocks from a dog-racing track filled with thousands of people in West Memphis, Arkansas.
Broadcast meteorologists have long played a vital role in raising tornado awareness and in broadcasting warnings as quickly as possible. That role is now being challenged by the proliferation of technologies and media types now available. Weather information can be obtained through the Internet, pagers, and cell phones, as well as through radio and TV. At the same time, videotapes, DVD, and cable channels are reducing the percentage of TV viewers who can be reached in a tornado emergency. Not all radio stations broadcast tornado warnings, and the Internet is still a "pull" technology, so few people will be notified of tornado warnings through their online connections. As TV broadcasters take these challenges into account, they must also take maximum advantage of new tools available through the National Weather Service and the NOAA Storm Prediction Center, including probabilistic forecasts of tornadoes.
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