Tornado watch

A tornado watch (SAME code: TOA) is a severe weather watch product of the National Weather Service that is issued by national weather forecasting agencies when meteorological conditions are favorable for the development of severe thunderstorms capable of producing tornadoes. In addition to the potential for tornado development, 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 does not mean a tornado is active or will appear, just that favorable conditions increases the likelihood of such happening. A watch must not be confused with a tornado warning. Definition A tornado watch indicates that atmospheric conditions observed in and close to the watch area have created a significant risk for the development and intensification of severe convective thunderstorms capable of producing tornadoes, and are normally issued in advance of the onset of severe weather. If severe weather actually does occur, a severe thunderstorm warning or tornado warning would then be issued. Residents and travelers in the watch area are advised to immediately undertake safety preparations ahead of the arrival of severe weather. A tornado watch is not required for a warning to be issued; tornado warnings are occasionally issued when a tornado watch is not active (i.e., when a severe thunderstorm watch is active or if conditions for tornadic development are not expected to be substantive enough to require a watch), if a severe thunderstorm has a confirmed tornado or developed strong rotation. A tornado watch can replace an existing severe thunderstorm watch, if not merely a portion of it, if conditions that were originally considered marginally conducive if at all for tornadic development have evolved to permit a greater risk of tornado formation. Although the risk of tornadoes is emphasized as the primary hazard, depending on storm cell intensity, the probability exists for other hazardous phenomena exceeding regional severe criterion to occur: severe thunderstorms that develop within the watch area will also pose a likelihood of producing large hailstones, intense straight-line winds that can produce serious structural damage equivalent to a lower-category tornado over a comparatively broader areal swath, intense lightning, torrential rainfall and/or flash flooding caused by high rainfall accumulations.