A tornado is a narrow, violently rotating column of air that extends from the base of a thunderstorm to the ground. Because wind is invisible, it is hard to see a tornado unless it forms a condensation funnel made up of water droplets, dust and debris. Tornadoes are the most violent of all atmospheric storms.
The intense spinning of a tornado is partly the result of the updrafts and downdrafts in the thunderstorm (caused by the unstable air) interacting with the wind shear, resulting in a tilting of the wind shear to form an upright tornado vortex.
It occurs mostly in an area we call Tornado Alley. The land is relatively flat, which allows cold dry polar air from Canada to meet warm moist tropical air from the Gulf of Mexico. It's along the front between the two airmasses that most tornadoes form.
Tornado Season. Tornadoes can occur at any time of the year. In the southern states, peak tornado occurrence is in March through May, while peak months in northern states are during the summer.
Act quickly after a tornado warning.
In a public building such as a store or office, go to a designated shelter area such as a safe room, basement, storm cellar, or the lowest building level.
A watch does not mean that the severe weather is actually occurring, only that atmospheric conditions have created a significant risk for it
A tornado warning is an alert issued by national weather forecasting agencies to warn the public that severe thunderstorms with tornadoes are imminent or occurring. The issuance of a tornado warning indicates that residents should take immediate safety precautions.
The Fujita scale is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation.
The Tri-State Tornado of Wednesday, March 18, 1925 was the deadliest tornado in U.S. history. It was also the most exceptional tornado of a major outbreak of at least twelve known significant tornadoes ... Wikipedia
Areas affected: Midwestern and Southeastern US
Max rating1: F5 tornado
Damage: >$1.4 billion (1997 USD) (Tri-State Tornado only)
Largest hail: 4.5 inches (11 cm) at Lexington, KY at 7:15 pm CST
Start date: March 18, 1925
Number of deaths: 695