What is the difference between a Watch and a Warning?
A Severe Thunderstorm Watch means that severe weather is possible. A Severe Thunderstorm Warning means that severe weather is in the immediate area.
A Tornado Watch means that conditions are present that could produce a tornado. A Tornado Warning means that a tornado has been sighted, and that you should prepare to seek shelter. The sirens will only be activated for a tornado warning or if a trained spotter reports a funnel cloud or an actual tornado.
In either case, listen to the radio or television for updates!