Minor Tornadoes

• The Enhanced Fujita (EF) scale measures the damage a tornado can cause. EF scale 0 tornadoes are capable of three-second wind gusts of up to 65 to 85 miles per hour. These tornadoes have gale force winds and do little damage -- they have only enough power to destroy weak outbuildings. Tornadoes in the EF1 range can produce winds of 86 to 110 miles per hour. These tornadoes cause minor damage and can destroy a strong outbuilding.
  
  

Strong Tornadoes

• Tornadoes that produce wind speeds of 111 to 135 miles per hour are classified as EF2 tornadoes. These twisters are capable of removing a roof from a house and causing more damage than EF0 or EF1 tornadoes. If tornado winds reach speeds of 136 to 165 miles per hour, you have a EF3 tornado. These tornadoes are capable of knocking down walls and taking off roofs. Tornadoes this size (and up) can do major damage to metropolitan areas.
  
  

Major Tornadoes

• Tornadoes producing winds of 166 to 200 miles per hour are classified as EF4 tornadoes. These tornadoes will leave a path of destruction in their wake by knocking down almost anything in their path. Any tornado that produces winds that are greater than 200 miles per hour is classified as a EF5. EF5 tornadoes are capable of throwing vehicles, barns and houses great distances.
  
  

Conditions

• There is still much to be learned when it comes to how a devastating tornado forms. Although temperature variations from the cold storm in the sky to the warmth of the ground and lower air can cause a tornado, it does not always happen. Some of the most devastating tornadoes produced have had very little temperature variation, according to the National Oceanic and Atmospheric Administration.