A tornado watch is a severe weather watch product of the National Weather Service that is issued when meteorological conditions are favorable for the development of severe thunderstorms capable of producing tornadoes. A tornado watch does not mean a tornado is active or will appear, just that favorable conditions increase the likelihood of such happening. Thunderstorms that develop within the watch area may contain large hail, straight-line winds, intense rainfall, and/or flooding that pose a similar damage risk as the attendant tornado threat.
A tornado watch is issued by the Storm Prediction Center for counties where tornadoes may occur. The watch area is typically large, covering numerous counties or even states. During a tornado watch, people should review and discuss their emergency plans, check supplies, and identify a safe room. If there is a watch in your area, you should keep an eye on weather alerts and be prepared to act. Make sure you know ahead of time what to do if a tornado hits.
A tornado warning, on the other hand, means that either a tornado has been spotted or a radar has picked one up. A warning is issued by your local forecast office and typically encompasses a much smaller area (around the size of a city or small county) that may be impacted by a tornado identified by a forecaster on radar or by a trained spotter/law enforcement who is watching the storm. If you are in an area with a tornado warning, its time to act immediately. Get to a safe space such as a storm shelter. If you dont have one, the best option is usually in the basement or the middle of a building, away from windows, preferably in an area with reinforced walls.
In summary, a tornado watch means that conditions are favorable for tornadoes to develop, while a tornado warning means that a tornado has been spotted or there is a strong indication on radar that a tornado is in progress. During a watch, people should review their emergency plans and be prepared to act if a warning is issued or they suspect a tornado is approaching. During a warning, people should take immediate action to protect themselves.
