A severe thunderstorm watch (SAME code: SVA) is a severe weather watch product issued by regional offices of weather forecasting agencies throughout the world when meteorological conditions are favorable for the development of severe thunderstorms as defined by regional criteria that may contain large hail, straight-line winds, lightning, intense hydrological phenomena and/or tornadoes. A severe thunderstorm watch does not necessarily mean that severe weather is actually occurring, only that conditions present a credible risk for thunderstorms producing severe weather phenomena to affect portions of the watch area. A watch must not be confused with a severe thunderstorm warning.