Indicates that conditions are favourable for lightning, damaging winds greater than 90 kilometres per hour and hail and/or heavy rainfall.

Indicates that conditions are favorable for lightning, damaging winds greater than 58 miles an hour and hail and/or heavy rainfall.

A bulletin issued by the National Severe Storms Forecast Center in Kansas City, Missouri, for regions, watch boxes when conditions are favorable for development of severe thunderstorms in or close to a designated area.

An outlined area where severe thunderstorms are more likely to occur within a certain time frame. Sometimes will be referred to as a "watch box". During a watch you should keep informed and watch the weather situation closely.

Issued when conditions are favorable for the development of severe thunderstorms in and close to a defined area.