This information is commonly used by local National Weather Service offices, emergency managers, TV and radio meteorologists, private weather forecasting companies, the aviation industry, storm spotters, agriculture, educational institutions and many other groups. When the SPC feels that weather conditions are favorable for the development of severe weather they will issue a Weather Watch . A watch means only that the weather conditions could produce severe weather. A thunderstorm watch means that conditions may permit thunderstorms to develop. A tornado watch does not mean tornadoes are imminent - just that conditions might favor their development.
Watches mean just that- 'watch' and be alert.
Weather Warnings are issued by the local offices of the National Weather Service. Warnings are only issued when severe weather is imminent. A Tornado Warning means that a tornado has been spotted, or that Doppler radar indicates a thunderstorm circulation which can spawn a tornado . Any tornado sighting causes a tornado warning to be issued. If the weather looks bad, turn on a radio or television.