'Tornado alley' claims average 80 lives every year
The plains of the central United States are no strangers to tornadoes. About a thousand occur every year in 'Tornado Alley', killing on average 80 people and leaving a trail of devastation in their wake at a cost of 300 million dollars.
'Tornado Alley' stretches across the states of Texas, Oklahoma, Arkansas, Kansas, Missouri, South Dakota, Tennessee, Iowa, Illinois and Indiana. On these vast plains east of the Rocky Mountains, hot and humid air from the Gulf of Mexico hits dryer, fresh air from California and Canada.
April to June is high season as the clash of air types results in violent storms that produce lightning, hail and hundreds of tornadoes. While the vast majority - around 79 percent - are insignificant, the strongest can produce twisters with wind speeds up to 400 kilometers an hour (244 mph), which travel at more than 100 kilometers an hour (62 mph) and can stay on the ground from 20 minutes to several hours.
When they hit built-up areas, the results are often devastating -- buildings smashed; cars, trains and livestock all hurled up into the air like wisps of straw.
Stories abound of roofs recovered dozens of kilometres away from their houses, and less sturdy domestic items like photographs, checkbooks and even wedding dresses have turned up some 150 kilometers (93 miles) away after a tornado has struck.
Fortunately only 2 percent of tornadoes result in deaths, as most of them hit the sparsely populated Midwestern plains. The highest toll ever recorded in the US was from the so-called "Three States" tornado of 1925, which swept from Louisiana through Missouri, Illinois and Indiana killing 689 people, with 11,000 made homeless.