Tornadoes strike a small area compared to other violent storms, but they can destroy ev-
erything in their path. Tornadoes uproot trees, rip boards from buildings, and fling cars up
into the sky. The most violent two percent of tornadoes last more than three hours. These
monster storms have winds up to 480 kph (300 mph). They cut paths more than 150 km
(95 miles) long and 1 km (one-half mile) wide (Figure16.27).
Figure 16.27: This tornado struck Seymour, Texas in 1979. ( 31 )Most injuries and deaths from tornadoes are caused by flying debris. In the United States, an
average of 90 people are killed by tornadoes each year, according to data from the National
Weather Service. The most violent two percent of tornadoes account for 70% of the deaths
by tornadoes (Figure16.28).
Figure 16.28: Tornado damage at Stoughton, Wisconsin in 2005. ( 41 )Tornadoes form at the front of severe thunderstorms, so these two dangerous weather events
commonly occur together. In the United States, tornadoes form along the front where the
maritime tropical (mT) and continental polar (cP) air masses meet. In a typical year, the
location of tornadoes moves along with the front, from the central Gulf States in February,
to the southeastern Atlantic states in March and April, and on to the northern Plains and
Great Lakes in May and June. Although there is an average of 770 tornadoes annually, the
number of tornadoes each year varies greatly (Figure16.29).
Meteorologists can only predict tornado danger over a very wide region, a few hours in
advance of the possible storm. Once a tornado is sighted on radar, its path is predicted