The tornado , which struck downtown Salt Lake City, killed one person and injured about 100. They touch down every year around Los Angeles. The swirling columns of air and debris can form anywhere if the right atmospheric conditions exist. Some regions of the United States are more vulnerable, such as in tornado alley . This area of the central USA is in an area where warm, humid air from the Gulf of Mexico collides with the fast-moving and cooler winds from the Rocky Mountains or Canada.
Twisters are most likely to occur there in the spring and summer.
But, on Wednesday, Aug. 11, 1999l, meteorologists in Salt Lake City watched the same conditions develop over their state. It remained on the ground for about five minutes, doing considerable damage to downtown buildings. Wind speeds were estimated to be between 113 and 157 mph, a rather mild tornado, considering that winds in these whirling monsters can reach 300 mph and turn a truck into unrecognizable scarp metal. Only thirty-two have been reported in the last 25 years. Oklahoma recorded 1,326 over the same period.