A tornado watch is issued by the Storm Prediction Center for an area where tornadoes are possible in the ensuing several hours.
It does not mean tornadoes are imminent — just that you need to be alert and prepared to take shelter.
A tornado warning is issued by local National Weather Service offices for an area where a tornado has been spotted, or where Doppler radar indicates a thunderstorm circulation can spawn a tornado.
When a tornado warning is issued for your town or county, take immediate safety precautions.
Signs of a tornado:
A dark, greenish sky.
A wall cloud, a low-hanging, rotating feature below the base of the thunderstorm. "Wall" is not a good descriptive word for it.
Whirling dust or debris on the ground below a cloud base. Tornadoes sometimes do not have a funnel.
Hail or heavy rain followed by either dead calm or a fast and intense wind shift. Tornadoes can be hidden by heavy rainfall.
Loud, continuous roar or rumble that sounds like thunder or a freight train but doesn't fade in a few seconds.
At night, flashes of bright, blue-green to white light at ground level near a thunderstorm. The flashes are power lines snapped by strong winds or a tornado.
Sources: Federal Emergency Management Agency, National Oceanic and Atmospheric Administration
If a tornado is coming:
KWTV NEWS 9 chief meteorologist Gary England and the National Oceanic and Atmospheric Administration offer these tips to help keep you safe during a tornado:
Go to the lowest level, smallest room in the center part of your house. If you do not have a cellar, basement or safe room, take shelter in a small room in the center of your home on the lowest level. Get in the bathtub. Wrap yourself in a blanket or mattress and protect your face and eyes. If a center room is not available, use a small room on an east wall.
If you feel your home is unsafe, find a shelter in your community and go there before the storm hits. Residents in mobile homes should move to a preselected shelter.
At an office or factory:
Proceed with advance plans or go to an interior hallway on the lowest level and drop to the floor, protecting your eyes and face. Don't take shelter in halls that open to the south or west. Central stairwells are good shelter.
In a 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 elevators; you could be trapped if the power is lost.
In a mobile home:
Get out. Even if your home is tied down, you are probably safer outside, even if the only alternative is to seek shelter out in the open. Most tornadoes can destroy even tied-down mobile homes; and it is best not to play the low odds that yours will make it. If your community has a tornado shelter, go there fast. If there is a sturdy permanent building within easy running distance, seek shelter there. Otherwise, lie flat on low ground away from your home, protecting your head. If possible, use open ground away from trees and cars, which can be blown onto you.
Follow the drill. Go to the interior hall or room in an orderly way as you are told. Crouch low, head down, and protect the back of your head with your arms. Stay away from windows and large open rooms like gyms and auditoriums. In a car or truck:
Don't use your vehicle to escape; cars and trucks can be fatal shelters. If you are in the storm's path, move perpendicular (right angle) to the tornado and find safe shelter. Do not seek shelter beneath an overpass. If the tornado is visible far away and 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. If in the open country, run to low ground away from any cars. Lie flat and face-down, protecting the back of your head with your arms.
In the open outdoors:
If possible, seek shelter in a sturdy building. If not, lie flat and face-down on low ground, protecting the back of your head with your arms.