National Weather Service United States Department of Commerce

Severe Weather Awareness - Tornadoes

Nature's most violent storms


No other country in the world has more tornadoes than the United States.
In an average year, 800 tornadoes are reported in the United States,
resulting in 80 deaths and over 1,500 injuries

Tornadoes are found most frequently in the United States
east of the Rocky Mountains.

Oklahoma has the highest average number of tornadoes
with 47 each year

South Carolina has an average of
10 tornadoes each year

Georgia has an average of 21 each year

Tornado deaths by state
Click Map for Larger Image

Tornadoes are defined as violently rotating columns of air extending from a thunderstorms to the ground.

What's the difference between a tornado and
a funnel cloud?

Funnel clouds are rotating columns of air not in contact with the ground. However, the violently rotating column of air may reach the ground very quickly - becoming a tornado! If there is debris being picked up or blown around by the "funnel cloud" - the rotating column of air has already reached the ground and it's a tornado!

How are tornadoes and waterspouts different?

Waterspouts are weak tornadoes that form over warm water. Waterspouts are most common along the Gulf Coast and southeastern U.S. coastline. Waterspouts occasionally move inland - as soon as the base of the rotating column of air moves over land the waterspout becomes a tornado!

Large Tornado funnel

 

How strong are tornadoes?

While most tornadoes (69%) have winds of less than 100 miles an hour, they can be much much stronger. Violent tornadoes (winds greater than 205 miles an hour) account for only 2% of all tornadoes, they cause 70% of all tornado deaths. In 1931, a tornado in Minnesota lifted an 83-ton railroad train with 117 passengers and carried it more than 80 feet! Once a tornado in Oklahoma carried a motel sign 30 miles and dropped it in Arkansas! In 1975 a Mississippi tornado carried a home freezer more than one mile!

Tornado Wind and Damage Scale

Tornado Scale Wind Speeds Damage Frequency of Occurrence
F0 40 to 72 MPH Some damage to chimneys, TV antennas, roof shingles, trees, and windows. 29%
F1 73 to 112 MPH Automobiles overturned, carports destroyed, trees uprooted 40%
F2 113 to 157 MPH Roofs blown off homes, sheds and outbuildings demolished, mobile homes overturned. 24%
F3 158 to 206 MPH Exterior walls and roofs blown off homes. Metal buildings collapsed or are severely damaged. Forests and farmland flattened. 6%
F4 207 to 260 MPH Few walls, if any, standing in well-built homes. Large steel and concrete missiles thrown far distances. 2%
F5 261 to 318 MPH Homes leveled with all debris removed. Schools, motels, and other larger structures have considerable damage with exterior walls and roofs gone. Top stories demolished Less than 1%

How big are tornadoes?

  • Most tornadoes are less than 1/4 of a mile wide on the ground - but they can also can exceed 1 mile in width! The McColl tornado in March 1984 (moving from the McColl S.C. area into North
    Carolina) was over 1 1/2 miles on the ground!

  • Most tornadoes are on the ground 10 minutes or less - but in 1925 a tornado traveled 219 miles across Missouri, Illinois, and Indiana in 4 hours!

  • In 1924, a tornado that started in Aiken County South Carolina traveled 135 miles into Florence County!

Tornado with dark thunderstorms in background

How fast can tornadoes move?

  • The average speed of a tornado is around 35 miles an hour - but they can remain almost stationary or move as fast as 70 miles an hour!

 

  • The average tornado moves from southwest to northeast - but they can move in any direction and even change direction!.

Tornado in the "rope" stage
When are tornadoes most likely?

In the southern
United States the
peak occurrence
of tornadoes is March through May - but tornadoes can occur any time of year!

Most tornadoes
occur between 3
and 9 PM - but
tornadoes can occur at any time of day or night!
Peak months for tornado occurrence

Click to Enlarge Map

Where is the safest place to take shelter from a tornado...
  • In my home?
    • Get away from windows
      - they may shatter and
      glass may go flying
    • Go to the basement and
      get under a heavy workbench or the stairs
    • If you don't have a basement, go to an inside closet, bathroom, or a hall on the lowest level of the house
    • Get under a mattress.
    • Protect your head
  • In my car?
    • Get out of a car and inside a sturdy house or building!
    • Don't try to outrun a tornado in a car.
    • Tornadoes can pick up a car and throw it through the air
  • At school?
    • Follow directions of your
      teacher
    • Go to an inside hall on the lowest floor
    • Crouch near the wall. Bend over with your hands on the back of
      your head 
    • Keep away from glass and stay out of large rooms like the gym, cafeteria, or auditorium
    • Keep a battery radio on and listen for news about the tornado
  • In a mobile home?
    • If you live in a mobile home - get out!
    • Even it's it tied down a mobile home can be shattered by a tornado The entire mobile home can be lifted off the ground and dropped
    • Get out and into a safe place. If you can't get to a tornado shelter, lie in a ditch and cover your head with your hands. 
  • Downtown or shopping?
    • Get off the streets
    • Go into a building and stay away from windows and doors
  • If I'm caught outside?
    • Take shelter in a ditch, culvert, or ravine 
    • Cover your head with
      your hands.

 

Most tornado deaths are the result of flying debris

Tornado embedded in heavy rain

Tornado leaves a path of damage to treetops and windswept homes. Here windswept debris is

Tornado crushes and rolls farm vehicle, pinning it against a post.

 

Tornado position - Bend over with your hands on the back of your head

 

Tornado Myths

1. Areas near rivers, lakes, and mountains are
safe from tornadoes

 

2. The low pressure with a tornado causes building to "explode" as the tornado passes overhead.

3.  Windows should be opened before a tornado approaches to equalize pressure and
minimize damage 

Tornado Facts

1. No place is safe from tornadoes. In the late
1980's, a tornado swept through Yellowstone
National Park leaving a path of destruction up
and down a 10,000 ft mountain.

2. Violent winds and debris slamming into a
building cause most structural damage.

3.Opening windows allows damaging winds to enter the structure. Leave windows alone;
instead, go immediately to a safe place.

The National Weather Service issues watches and warnings for tornadoes

A TORNADO WATCH means conditions are favorable for tornadoes to develop or move into the watch area. Watches are intended to heighten public awareness of the possible severe weather threat. Keep an eye on the sky and stay tuned to NOAA Weather Radio or local radio, television, or cable to know when severe weather warnings are issued for your area.

A TORNADO WARNING means a tornado poses an imminent danger to life and property to those in the path of the storm. When a tornado is indicated by weather radar, or is reported by trained SKYWARN Severe Weather Spotters or law enforcement officials a warning is issued immediately.
Stay tuned to NOAA WEather Radio or local tv and radio

Tornado Watches and Warnings are sent to local radio and television stations and are broadcast over your local NOAA Weather Radio serving the warning area. These warnings are also relayed to local emergency management and public safety officials who can activate local warning systems to alert communities to the danger.


Contact us if you'd like a free copy of Thunderstorms...Tornadoes...Lightning...Nature's Most Violent Storms - a preparedness brochure produced by the National Weather Service, Federal Emergency Management Agency, and the American Red Cross.

Related Web Sites on Tornado Safety: