There are few documented cases of a tornado lasting more than an hour. Understand that tornadoes normally, but not always, rotate counterclockwise. Learn that the power of a tornado is measured by the F-scale, a rating system established by Dr. T. T. Fujita. Know that the F-scale is an attempt to relate visible damage to the strength of wind. Be aware that damage to structures can occur at any F-scale level from a tornado of any size or shape.
Folk wisdom says tornadoes produce the deep, rumbling sound of a large train moving close by.
But if the storm is moving through a developed area, there will be a cacophony of noise. Tornadoes can carry and scatter lightweight debris for miles. The USA's deadliest tornado outbreak occurred in the spring of 1925 when a tremendous storm raged across Missouri, Illinois and Indiana, spawning tornadoes that killed more than 600 people. Tornadoes have been measured at a width of over 2 miles. A waterspout is a tornado over water.