Tornadoes, a definition and introduction

A tornado is defined as a violently rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Damage paths can be in excess of one mile wide and 50 miles long.
Tornado varieties
Inland Tornadoes
Some tornadoes may form during the early stages of rapidly developing thunderstorms. This type of tornado is most common along the front range of the Rocky Mountains, the Plains, and the Western States. 

Tornadoes may appear nearly transparent until dust and debris are picked up. 

Occasionally, two or more tornadoes may occur at the same time. 

Tornadoes over water: Waterspouts
Waterspouts are weak tornadoes that form over warm water. 
Waterspouts are most common along the Gulf Coast and southeastern states. In the western United States, they occur with cold late fall or late winter storms, during a time when you least expect tornado development. 
Waterspouts occasionally move inland becoming tornadoes causing damage and injuries. 


Tornado Statistics 
Weak Tornadoes
69% of all tornadoes 
Less than 5% of tornado deaths 
Lifetime 1-10+ minutes 
Winds less than 110 mph 
Strong Tornadoes
29% of all tornadoes 
Nearly 30% of all tornado deaths 
May last 20 minutes or longer 
Winds 110-205 mph 
Violent Tornadoes
Only 2% of all tornadoes 
70% of all tornado deaths 
Lifetime can exceed 1 hour 
Winds greater than 205 mph