tornado is a violently rotating column of air extending from the base of a
thunderstorm to the ground. Tornado intensities are classified on the Fujita
Scale with ratings between 0 and 5 using actual damage to determine a tornado’s
wind speed. A storm of F0 is the weakest and F5 is the strongest. Different
winds may be needed to cause the same damage depending on how wellbuilt a
structure is, wind direction, wind duration, battering by flying debris and
other factors. The most violent tornadoes have rotating winds of 250 miles (402
kilometers) per hour or more. They are capable of completely destroying
well-made structures, uprooting trees, and hurling normally harmless objects
through the air like deadly missiles. Most tornadoes are rated F0 and F1, and
these usually span just a few dozen yards and touch down only briefly. Highly
destructive violent tornadoes—F4 and F5—can carve out paths more than a mile
(1.6 kilometers) wide and 50 miles (80 kilometers) long. Although these violent
tornadoes comprise only two percent of all tornadoes, they are responsible for
nearly 70 percent of tornado-related fatalities.
Tornadoes usually develop from severe thunderstorms in warm, moist, unstable air along and ahead of cold fronts. Such thunderstorms also may generate large hail and damaging winds. When intense springtime storm systems produce large, persistent areas that support tornado development, major outbreaks can occur. In the United States during the late spring, tornadic thunderstorms can develop in the southern High Plains along a "dry line," the interface between warm, moist air to the east and hot, dry air to the west. From the front range of the Rocky Mountains southward into the Texas Panhandle, a down-slope flow of unstable air can cause tornadic thunderstorms to develop. While generally smaller and less frequent, tornadoes occurring west of the Rocky Mountains also cause damage and threaten lives annually.
Tropical storms and hurricanes that come ashore can
also generate tornadoes. In 1967, Hurricane Beulah produced 141 tornadoes as it
made landfall. In 1992, Hurricane Andrew produced 62
Each year, many people are killed or seriously injured by tornadoes despite advance warning. Some did not hear the warning, while others heard the warning but did not believe they were personally threatened. Timely tornado watches and warnings, combined with household preparedness, could save your life. Once you receive a warning or observe threatening skies, YOU must make the decision to take shelter before the tornado arrives. It could be the most important decision you will ever make.
What is the best source of information in a tornado situation?
radio or television stations or a NOAA Weather Radio are the best sources of
information in a tornado situation for official weather and weather-related
• Pick a safe place in your home where family members, including pets, could gather during a tornado. The safest place to be is underground, or as low to the ground as possible, and away from all windows. If you have a basement or storm cellar, make it your safe place. If you do not have a basement or storm cellar, consider an interior bathroom, closet, or hallway on the lowest floor. Putting as many walls as you can between you and the outside will provide additional protection. Less than two percent of all tornadoes have winds over 205 miles (330 kilometers) per hour and are powerful enough to completely destroy a sturdy building. Make sure there are no windows or glass doors in your safe place and keep this place uncluttered.
• Consider having your tornado safe place reinforced. (See “Wind Safe Room”) Additional reinforcement will add more protection from the damaging effects of tornado winds. Get more information from the Federal Emergency Management Agency (FEMA) about building a “wind safe” room. Also, for more information, check out the Institute for Business and Home Safety at www.ibhs.org.
• If you are in a high-rise building, pick a place in a hallway in the center of the building. You may not have enough time to go to the lowest floor. Center hallways are often the most structurally reinforced part of a building.
• If you live in a mobile home, choose a safe place in a nearby sturdy building. A sturdy building provides greater protection. If your mobile home park has a designated shelter, make it your safe place. Mobile homes are much more vulnerable to strong winds than site-built structures. Prior to 1994, most mobile homes were not designed to withstand even moderate winds.
• Learn about your community's warning system. Different communities have different ways of providing warnings. Many communities have sirens intended for outdoor warning purposes. Use a NOAA Weather Radio to keep aware of watches and warnings while you are indoors. Make sure all family members know the name of the county or parish where you live or are traveling, because tornado watches and warnings are issued for a county or parish by name.
• Conduct periodic tornado drills, so everyone remembers what to do if a tornado approaches. Practice having everyone in the household go to your designated safe place. Have everyone get under a sturdy piece of furniture, hold on with one hand, and protect his or her head and neck with the other. Practicing your plan makes the appropriate response more of a reaction, requiring less thinking time during an actual emergency situation.
• Check at your workplace and your children's schools and day care centers to learn about their tornado emergency plans. Every building has different safe places. It is important to know where they are and how to get there in an emergency.
• Discuss tornadoes with your family. Everyone should know what to do in case all family members are not together. Discussing disaster preparedness ahead of time helps reduce fear and lets everyone know what to do in a tornado situation.
• Make a list of items to bring inside in the event of a storm. Having a list will help you remember things that may be broken or blown away in strong winds.
• Keep trees and shrubbery trimmed. Make trees more wind resistant by removing diseased or damaged limbs, then strategically remove branches so that wind can blow through. Strong winds frequently break weak limbs and hurl them at great speed, causing damage or injury when they hit. Debris collection services may not be operating just before a storm, so it is best to do this well in advance of approaching storms.
• Remove any debris or loose items in your yard. Branches and firewood may become missiles in strong winds.
• Consider installing permanent shutters to cover windows. Shutters can be closed quickly and provide the safest protection for windows.
• Strengthen garage doors. Garage doors are often damaged or destroyed by flying debris, allowing strong winds to enter. As winds apply pressure to the walls, the roof can be lifted off, and the rest of the house can easily follow.
• Use a NOAA Weather Radio to keep informed of watches and warnings issued in your area. If you do not have a NOAA Weather Radio, keep up with local forecasts and conditions via a local radio or television station.
• If planning a trip or extended period of time outdoors, listen to the latest forecasts and take necessary action if threatening weather is possible. Knowing what the weather could be helps you to be prepared. Have a raincoat, umbrella, and Disaster Supplies Kit handy so you can deal with severe weather if it occurs.
• Watch for tornado danger signs. Tornadoes may strike so quickly that warnings cannot be issued long in advance. Pay attention to weather clues around you that warn of imminent danger:
-Dark, often greenish clouds. Sometimes one or more of the clouds turns greenish (a phenomenon caused by hail) indicating a tornado may develop.
-Wall cloud, an isolated lowering of the base of a thunderstorm. The wall cloud is particularly threatening if it is rotating.
-Large hail. Tornadoes are spawned from powerful thunderstorms, which are capable of producing large hail. Tornadoes frequently emerge from near the hail-producing portion of the storm.
-Cloud of debris. An approaching cloud of debris can mark the location of a tornado, even if a funnel is not visible.
-Funnel cloud. A visible rotating extension of the cloud base is a sign that a tornado may develop.
-Roaring noise. The high winds of a tornado can cause a roar that is often compared with the sound of a freight train.
If you live in
a single-family home in a tornado-prone area, find
out how to reinforce an interior room on the lowest level of your home (such as
the basement, the storm cellar, a bathroom, a closet, or a hallway) to use as a
shelter. (See “Wind
Plans for reinforcing an interior room to provide better tornado protection in
your home are available from your local emergency management office or from the
Federal Emergency Management Agency’s Web site at www.fema.gov/mit/saferoom/.
• Listen to NOAA Weather Radio or local radio or television stations for updated information. Tornadoes can change direction, intensity, and speed very quickly.
• Be alert to changing weather conditions. Tornadoes accompany severe thunderstorms, and weather conditions can change rapidly. Large hail, blowing debris, or the sound of an approaching tornado may alert you. Many people say approaching tornadoes sound like a freight train.
• Bring your companion animals indoors and maintain direct control of them.
• Be prepared to go to your tornado safe place.
If a tornado warning is issued:
• Listen to a battery-powered NOAA Weather Radio or a local radio or television station for updated information. If the electricity goes out, you will still be able to receive emergency information.
• If you are inside, you should:
-Go to your safe place to protect yourself from glass and other flying objects. Take your pets with you, provided you can do so without endangering yourself. Tornadoes can change direction, intensity, and speed very quickly. The tornado may be approaching your area.• If you are outside in a vehicle or mobile home, you should:
-Get under a sturdy piece of furniture, such as a workbench or heavy table, and hold on to it with one hand. Sturdy furniture will help protect you from falling debris. If tornado wind enters the room and the object moves, holding on with one hand will help you move with it, keeping you protected.
-Use your other arm and hand to protect your head and neck from falling or flying objects. Your head and neck are more easily injured than other parts of your body. Protect them as well as you can.
-Stay away from windows. Opening windows allows damaging winds to enter the structure. Leave the windows alone; instead, immediately go to your safe place. It is a myth that tornadoes cause houses to explode due to changes in air pressure. Flying debris can shatter glass. Violent winds and debris slamming into buildings cause the most structural damage.
-Go immediately to the basement of a nearby sturdy building. A sturdy building is the safest place to be. Tornado winds can blow large objects, including cars and mobile homes, hundreds of feet away. Tornadoes can change direction quickly and can lift up a car or truck and toss it through the air; never try to out-drive a tornado. Mobile homes are particularly vulnerable. A mobile home can overturn very easily even if precautions have been taken to tie it down.
-If there is no building nearby, lie flat in a low spot and use your arms and hands to protect your head and neck. Tornadoes cause a lot of debris to be blown at very high speeds. Dangerous flying debris can be blown under overpasses and bridges, and the structures themselves could be destroyed. You will be safer lying flat in a low-lying area where the wind and debris will blow above you. Tornadoes come from severe thunderstorms, which can produce a lot of rain. If you see quickly rising water or floodwater coming toward you, move to another spot.
-Avoid places with wide-span roofs, such as auditoriums, cafeterias, large hallways, or shopping malls. Wide-span roofs are frequently damaged or destroyed in tornado winds; they provide less protection and more risk of injury than roofs over smaller rooms.
• Continue listening to local radio or television stations or a NOAA Weather Radio for updated information and instructions. Access may be limited to some parts of the community or roads may be blocked.
• Check for injuries. Give first aid and get help for injured or trapped persons. Taking care of yourself first will allow you to help others safely until emergency responders arrive.
• Help people who require special assistance—infants, elderly people, those without transportation, large families who may need additional help in an emergency situation, people with disabilities, and the people who care for them.
• Watch out for fallen power lines or broken gas lines and report them to the utility company immediately. Reporting potential hazards will get the utilities turned off as quickly as possible, preventing further hazard and injury.
• Avoid damaged areas. Your presence might hamper rescue and other emergency operations and put you at further risk from the residual effects of tornadoes.
• Stay out of damaged buildings.
• If you are away from home, return only when authorities say it is safe.
• Wear long pants, a long-sleeved shirt, and sturdy shoes.
• Use battery-powered lanterns or flashlights when examining buildings. DO NOT USE CANDLES.
• Examine walls, floors, doors, staircases, and windows to make sure that the building is not in danger of collapsing.
• Look for fire hazards. There may be broken or leaking gas lines, or damage to electrical systems. Clean up spilled medications, bleaches, gasoline, or other flammable liquids immediately.
• Check for gas leaks. If you smell gas or hear a blowing or hissing noise, open a window and get everyone out quickly. Turn off the gas using the outside main valve if you can, and call the gas company from a neighbor's home. If you turn off the gas for any reason, it must be turned back on by a professional.
• Look for electrical system damage. If you see sparks or broken or frayed wires, or if you smell burning insulation, turn off the electricity at the main fuse box or circuit breaker. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice. Electrical equipment should be checked and dried before being returned to service.
• Watch for loose plaster, drywall, and ceilings that could fall.
• Take pictures of the damage, both of the building and its contents, for insurance claims.
• Use the telephone only for emergency calls. Telephone lines are frequently overwhelmed in disaster situations. They need to be clear for emergency calls to get through.
• Watch your animals closely. Keep all your animals under your direct control. Your pets may be able to escape from your home or through a broken fence. Pets may become disoriented, particularly because tornadoes and the heavy rains that accompany them will usually affect scent markers that normally allow animals to find their homes. The behavior of pets may change dramatically after any disruption, becoming aggressive or defensive, so be aware of their well-being and take measures to protect them from hazards, including displaced wild animals, and to ensure the safety of other people and animals.
• Ask your local newspaper or radio or television station to:
-Do a series on the dangers of tornadoes and the importance of heeding tornado watches and warnings.• Periodically inform the community of the local public warning systems.
-Highlight the importance of staying informed about local weather conditions.
-Run public service ads about how to protect lives in a tornado and how to pick and set up a tornado safe room. Help the reporters to localize the information by providing them with the local emergency telephone number for the fire, police, and emergency medical services departments (usually 9- 1-1) and emergency numbers for the local utilities and hospitals. Also provide the business telephone numbers for the local emergency management office and local American Red Cross chapter.
• Work with officials of the local fire, police, and emergency medical services departments; utilities; hospitals; emergency management office; and American Red Cross chapter to prepare and disseminate guidelines for people with mobility impairments about what to do in a tornado situation.
• Sponsor a "Helping Your Neighbors" program at your local schools to encourage students to think about how to help people who require special assistance, such as elderly people, infants, or people with disabilities, and the people who care for them.
• Conduct a series of programs on how to protect yourself during a tornado if you are at home, if you are in a vehicle, if you are at the office, or if you are outdoors.
• Interview local officials about what people living in mobile home parks should do if a tornado warning is issued.