Description
The Canadian Forest Fire Weather Index (FWI) was issued in 1970 after several years' work by a number of fire researchers in the Canadian Forestry Service. The best features of the former fire danger index were incorporated in the FWI, and a link was preserved between old and new. The FWI is based on the moisture content of three classes of forest fuel plus the effect of wind on fire behavior. It consists of six components: three primary subindexes representing fuel moisture, two intermediate subindexes reprsenting rate of spread and fuel consumption, and a finl index representing fire intensity as energy output rate per unit length of fire front. The FWI refers primarily to a standard pine fuel but is useful as a general index of forest fire danger in Canada. It is determined every day from noon weather readings only: temperture, relative humidity, wind speed, and rain (if any). This paper describes the developement of the Fire Weather Index, the concepts behind it, and its mathmatical structure