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Minnesota State University, Mankato

Minnesota State University, Mankato

Tornado Information

Page address: http://www.mnsu.edu/facilities/departments/ehs/tornado.html

Tornado Information

Tornado:

Tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is spawned by a thunderstorm (or sometimes as a result of a hurricane) and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly. The damage from a tornado is a result of the high wind velocity and wind-blown debris. Tornado season is generally March through August, although tornadoes can occur at any time of year. They tend to occur in the afternoons and evenings: over 80 percent of all tornadoes strike between noon and midnight.

Fujita - Pearson Tornado Scale

Photo of the Fujita - Pearson Tornado Scale

F-0: 40-72 mph, chimney damage, tree branches broken
F-1: 73-112 mph, mobile homes pushed off foundation or overturned
F-2: 113-157 mph, considerable damage, mobile homes demolished, trees uprooted
F-3: 158-205 mph, roofs and walls torn down, trains overturned, cars thrown
F-4: 207-260 mph, well-constructed walls leveled
F-5: 261-318 mph, homes lifted off foundation and carried considerable distances, autos thrown as far as 100 meters

Tornado Danger Signs

  • An approaching cloud of debris can mark the location of a tornado even if a funnel is not visible.
  • Before a tornado hits, the wind may die down and the air may become very still.
  • Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

What to Do During a Tornado

If at home:

  • If you have a tornado safe room or engineered shelter, go there immediately.
  • Go at once to a windowless, interior room; storm cellar; basement; or lowest level of the building.
  • If there is no basement, go to an inner hallway or a smaller inner room without windows, such as a bathroom or closet.
  • Get away from the windows.
  • Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it.
  • Use arms to protect head and neck.
  • If in a mobile home, get out and find shelter elsewhere.

If at work or school:

  • Go to the area designated in your tornado plan.
  • Avoid places with wide-span roofs such as auditoriums, cafeterias, large hallways, or shopping malls.
  • Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it.
  • Use arms to protect head and neck.

If outdoors:

  • If possible, get inside a building.
  • If shelter is not available or there is no time to get indoors, lie in a ditch or low-lying area or crouch near a strong building. Be aware of the potential for flooding.
  • Use arms to protect head and neck.

If in a car:

  • Never try to out-drive a tornado in a car or truck.
  • Get out of the car immediately and take shelter in a nearby building.
  • If there is no time to get indoors, get out of the car and lie in a ditch or low-lying area away from the vehicle. Be aware of the potential for flooding.

 

General Safety Precautions that could help you avoid injury after a tornado:

  • Continue to monitor your battery-powered radio or television for emergency information.
  • Be careful when entering any structure that has been damaged.
  • Wear sturdy shoes or boots, long sleeves, and gloves when handling or walking on or near debris.
  • Be aware of hazards from exposed nails and broken glass.
  • Do not touch downed power lines or objects in contact with downed lines. Report electrical hazards to the police and the utility company.
  • Use battery-powered lanterns, if possible, rather than candles to light homes without electrical power. If you use candles, make sure they are in safe holders away from curtains, paper, wood, or other flammable items. Never leave a candle burning when you are out of the room.
  • Hang up displaced telephone receivers that may have been knocked off by the tornado, but stay off the telephone, except to report an emergency.
  • Cooperate fully with public safety officials.
  • Respond to requests for volunteer assistance by police, fire fighters, emergency management, and relief organizations, but do not go into damaged areas unless assistance has been requested. Your presence could hamper relief efforts, and you could endanger yourself.

If a tornado "watch" is issued for your area, it means that a tornado is "possible."
If a tornado "warning" is issued, it means that a tornado has actually been spotted, or is strongly indicated on radar, and it is time to go to a safe shelter immediately

Tornado Watch

A Tornado Watch simply means that conditions are favorable for tornadoes to develop. In this case you should take precautions to protect you and your property, and listen to the radio to keep informed.
Tornadoes are most likely to occur in the late afternoon on a hot spring day. However, tornadoes have occurred in every month at all times of the day or night. When a tornado watch is issued, be alert for changes in the weather. And be prepared to act quickly. On average, 770 tornadoes are reported annually in the United States.
When a tornado WATCH is in effect you can take certain precautions to lessen danger.
Move cars inside a garage or carport, if possible, to avoid damage from hail that often accompanies severe storms. Keep your car keys and house keys with you.
Move lawn furniture and yard equipment such as lawnmowers inside if time permits. Otherwise they could become damaged or act as dangerous projectiles, causing serious injury or damage.
Account for family members at home. Have your emergency kit ready.
Keep your radio or TV tuned into the weather reports.

Tornado Warning

Tornado Warning means that a tornado has actually been sighted. Realize that tornadoes can be deadly and devastating storms, with winds up to 260 miles per hour. If one is issued for your area, seek shelter immediately! There is little time for closing windows or hunting for flashlights. It's a good idea to know where things are, and to have an emergency storm kit already prepared.
When a tornado WARNING has been issued on the radio or by siren, seek shelter immediately!