SEVERE GALE

The definition of a 'Severe Gale/Force 9' is strict for operational (UK) forecasting for maritime purposes. Either the mean (10 minute) wind must be 41 knots or more, up to 47 knots; or the gusts must be 52 knots or more, up to 60 knots. The term will also be heard on broadcast weather forecasts, although it's arguable that the general population cannot be expected to know what this definition is, and the practice now is to explicitly forecast gust values rather than just relying on the adjective 'severe' to imply possible problems. (See also Gale, Storm.)