A tornado (often referred to as a twister) is defined as a violent, dangerous, rotating column of air that is in contact with both the surface of the earth. Tornadoes come in many shapes and sizes, but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds less than 110 miles per hour), are approximately 250 feet across, and travel a few miles before dissipating. The most extreme can attain wind speeds of more than 300 mph, stretch more than two miles across, and stay on the ground for dozens of miles.
Know the difference between a Tornado Watch and a Tornado Warning
NOAA defines a Tornado Watch as tornadoes and other kinds of severe weather are possible in the next several hours. It does not mean tornadoes are imminent, just that you need to be alert, and to be prepared to go to safe shelter if tornadoes do happen or a warning is issued. This is the time to turn on local TV or radio, turn on and set the alarm switch on your weather radio, make sure you have ready access to safe shelter, and make your friends and family aware of the potential for tornadoes in the area.
A Tornado Warning means that a tornado has been spotted, or that Doppler radar indicates a thunderstorm circulation which can spawn a tornado. When a tornado warning is issued for your town or county, take immediate safety precautions.
Most people are injured or killed not by the tornado itself, but by flying debris.
Besides an obvious twisted funnel of wrath, National Oceanic and Atmospheric Administration (NOAA) lists the following signs and symptoms to look and listen for:
- Strong, persistent rotation in the cloud base.
- Whirling dust or debris on the ground under a cloud base—tornadoes sometimes have no funnel!
- Hail or heavy rain followed by either dead calm or a fast, intense wind shift. Many tornadoes are wrapped in heavy precipitation and can't be seen.
- Day or night: Loud, continuous roar or rumble which doesn't fade in a few seconds like thunder.
- Night: Small, bright, blue-green to white flashes at ground level near a thunderstorm (as opposed to silvery lightning up in the clouds). These mean power lines are being snapped by very strong wind, maybe a tornado.
- Night: Persistent lowering from the cloud base, illuminated or silhouetted by lightning, especially if it is on the ground or there is a blue-green-white power flash underneath.
If you are in your home (and do not have a basement):
- In a house with no basement, a dorm, or an apartment: Avoid windows. Go to the lowest floor, small center room (like a bathroom or closet), under a stairwell, or in an interior hallway with no windows.
- Crouch as low as possible to the floor, facing down; and cover your head with your hands. A bath tub may offer a shell of partial protection.
- Even in an interior room, you should cover yourself with some sort of thick padding (mattress, blankets, etc.), to protect against falling debris in case the roof and ceiling fail.
- Myth: according to NOAA, it is a myth that you should open two windows to avoid a negative-pressure build-up (and house implosion.) They advise that you keep windows closed to avoid debris. They also say that most “explosions” occur from large debris crashing into structures.
In an office building, hospital, nursing home or skyscraper:
- Go directly to an enclosed, windowless area in the center of the building away from glass. Then, crouch down and cover your head.
- Interior stairwells are usually good places to take shelter, and if not crowded, allow you to get to a lower level quickly.
- Stay off the elevators; you could be trapped in them if the power is lost.
If you are in your car:
- Vehicles are extremely dangerous in a tornado. If the tornado is visible, far away, and the traffic is light, you may be able to drive out of its path by moving at right angles to the tornado.
- Otherwise, park the car as quickly and safely as possible, out of the traffic lanes. Get out and seek shelter in a sturdy building.
- As difficult as it may seem, leave your car if you are in the open country. Run to low ground away from any cars (which may roll over on you). Lie flat and face down, protecting the back of your head with your arms.
Avoid seeking shelter under bridges which can create deadly traffic hazards while offering little protection from flying debris.
