Violent winds and debris slamming into buildings cause most damage. Windows should be opened before a tornado to equalize pressure and minimize damage. Opening windows allows damaging winds to enter the structure. They are composed of violently rotating columns of air that descend in the familiar funnel shape from thunderstorm cloud systems. The weather conditions that tend to generate Tornadoes are unseasonably warm and humid earth surface air, cold air at middle atmospheric levels, and strong upper-level jet stream winds.
Tornadoes can occur anywhere in the United States during any month of the year.
However, the Great Plains and Gulf Coast States experience the largest number of Tornadoes. The greatest frequency of Tornadoes occur in April, May and June. The destructive path of a tornado averages about 250 yards in width and 15 miles in length. In extreme conditions, a tornado may travel more than 300 miles and leave a path of total destruction more than a mile wide. Tornadoes will travel up to 70 mph, with wind speeds approaching 400 mhp within the tornado's center.