A tornado warning is an alert issued by the National Weather Service indicating that a tornado has been seen on the ground or identified on radar. The warning is broadcast through television, radio and outdoor sirens.
Tornado warnings issued for one or more counties usually indicates those areas are in imminent danger from the storm. The warnings inform people to take immediate shelter in a basement or a room without windows, such as a bathroom.
A tornado warning is different from a tornado watch, which signals that conditions are ripe for the possible formation of tornadoes. Tornado warnings are usually accompanied by severe thunderstorm warnings.