Tornadoes extend from severe thunderstorms and usually develop from the trailing end of a storm. The air may become very still before one hits. It is also not uncommon for the sun to be visible or skies to clear partially during a tornado. Some are easily seen and detected, while others strike quickly with little or no warning.
Some warning signs of a tornado include strong winds with cloud-base rotation, whirling dust and debris, hail and/or heavy rain and a loud rumble or roar that sounds similar to a moving train.
If it is nighttime, look for bright blue- or green-colored flashes near the ground. That is an indication of snapped power lines and an almost sure sign of intense wind or a tornado.
Two of the most fundamental precautions that you can take in the event of a tornado, no matter where you are, is staying low to or below the ground in an interior space away from windows and covering your head with your hands and arms.
It is a good idea for your family to select a place to meet following any tornado in case you are separated at the time of the incident. Phone lines or other modes of communication may be affected by the twister and are not always reliable.
Mobile homes and dwellings without basements or foundations are not a safe place to be in a tornado. If your community does not have a storm shelter, seek a sturdy building nearby. If there is no time, seek a closet or climb into the bathtub and cover yourself some sort of thick padding, such as a mattress or blankets.
For additional information: http://www.accuweather.com/en/weather-news/important-tornado-safety-tips-1/30770