The term "tornado preparedness" refers to safety precautions made before the arrival of a tornado. It involves long-term plans as well as steps taken minutes beforehand (see below: Actions taken during tornadoes). Historically, the steps taken have varied greatly, depending on location, or time remaining before a tornado was expected. For example, in rural areas, people might prepare to enter an external storm cellar, in case the main building collapses, and thereby allow exit without needing rescue from the main building as in urban areas. Because tropical storms have spawned many tornadoes, hurricane preparations also involve tornadoes. The term "tornado preparedness" has been used by government agencies, emergency response groups, schools,[1] insurance companies, and others.
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Preparedness involves knowing the major dangers to avoid. Some tornadoes are the most violent storms in nature.[2] Tornadoes have varied in strength, and some tornadoes have been mostly invisible due to a lack of loose dirt or debris in the funnel cloud.[2] Spawned from strong thunderstorms, tornadoes have caused fatalities and devastated neighborhoods within seconds of arrival.
A tornado operates as a rotating, funnel-shaped cloud that extends downward from a thunderstorm, to the ground, with swirling winds which have reached 300 miles per hour (480 km/h).[2] The wind speed might be difficult to imagine: traveling the length of a U.S. football field within 1 second[3] (over 130 meters or 430 feet per second). Damage paths have been in excess of one-mile wide (1.6 km) and 50 miles long (80 km).[2]
Not all tornadoes are easily seen. A tornado funnel can be transparent until reaching an area with loose dirt and debris.[2] Also, some tornadoes have been seen against sunlit areas, but rain or nearby low-hanging clouds has obscured other tornadoes. Occasionally, tornadoes have developed so suddenly, so rapidly, that little, if any, advance warning was possible.[2]
Before a tornado strikes an area, the wind has been known to die down and the air to become very still.[2] A cloud of debris has sometimes marked the bottom of a tornado even when the funnel was not visible. Tornadoes typically occur along the trailing edge of a thunderstorm.
The following is a summary of typical tornadoes: [2]
The U.S. Federal Emergency Management Agency (FEMA) has advised the following precautions before a storm reaches an area: [4]
Upon seeing an approaching storm or noticing any of the danger signs, people should be prepared to take shelter immediately,[2] such as moving to a safe room, internal stairway, or other safe-haven area.
During August 2010, FEMA advised people to perform the following actions when a tornado struck.[5]
| Location | Action taken |
|---|---|
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In a structure (e.g. residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building) |
Go to a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level.[5] If there is no basement, go to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls. The goal has been to put as many walls as possible between there and the outside. Get under a sturdy table and use your arms to protect your head and neck. Do not open windows.[5] |
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In a vehicle, trailer, or mobile home |
Get out immediately and go to the lowest floor of a sturdy, nearby building or a storm shelter.[5] Mobile homes, even if tied down, offer little protection from tornadoes.[5] If a car is flipped by high winds, there is also the danger of broken glass. |
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On the outside with no shelter |
Lie flat in a nearby ditch or depression and cover your head with your hands.[5] Be aware of the potential for flooding there. Do not get under an overpass or bridge (where winds or debris might be funneled). It is safer to be in a low, flat location.[5] Never try to outrun a tornado in urban or congested areas in a car or truck. Instead, leave the vehicle immediately for safe shelter. Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries.[5] |
Because some preparations vary, depending on location, people have been advised to consult their local area preparedness plans.
Depending on location, various safe-havens areas have been prepared. The goal has been to avoid outer walls which might collapse when a roof section becomes airborne and the walls below lose their upper support: many interior rooms resist collapse longer, due to smaller walls interconnected to each other, while outer walls deflect the force of the winds. Because mobile homes typically lack foundation anchors and present a large surface-area sail (to catch wind), a safe haven should be sought elsewhere, such as in a stronger nearby building.[5] When a mobile home begins to roll, people have been injured by hitting objects inside, or being crushed when a trailer suddenly hits the ground and begins to collapse around them.
In a multi-story building, an internal stairway (away from broken windows) often acts as a safe haven, due to the stairs reinforcing the walls and blocking any major debris falling from above. If a stairway is lined with windows, then there would be the danger of flying glass, so an interior stairway, or small inner room, would be preferable.
In private homes, some similar stairway rooms have been used, or an interior room/closet kept clear to quickly allow entry when a storm is seen or heard approaching (the wind roar intensifies, sounding like a swift "freight train" coming nearer, louder).[2] With weeks or months to prepare, an interior safe room can be constructed, with space for emergency water, food and flashlights, and a telephone to call for rescue if the exit becomes blocked by falling debris. Some above-ground safe rooms have been built with steel-rebar rods in cement-filled cinder blocks, to withstand winds of 250 miles per hour (400 km/h). Rural homes might have an outside storm cellar, or other external bunker, to avoid being trapped within a collapsing house.
Having a first aid kit in the safe haven is advised to help victims recover from minor injuries. People needing prescription medications could have a medicine bag ready to take to shelter. Some people have reported their "ears popping" due to the change in air pressure, but those effects seem to be temporary. Covering people with mattresses or cushions has helped avoid injury from flying debris,[5] as walls collapsed nearby.