National Fire Danger Rating System - Preparedness Classes (or Adjective Rating)

Preparedness Classes (or Adjective Rating)

The bottom line of the National Fire Danger Rating System in the day-to-day operation of a fire prevention and suppression program is the staffing class. The staffing class is sometimes referred to as the action class, adjective class, precaution class, preparedness class, or the Industrial Fire Precaution Level (IFPL).

The assumption behind staffing levels is that the continuum of fire danger can be divided into discrete intervals to which preplanned management actions are keyed. In other words, for each staffing level or adjective class, there should be a management action that addresses the dispatch of suppression resources that constitutes an appropriate level of response. Staffing levels, or adjective class ratings, are ways of linking fire danger information to fire management decisions. The designations for the various class or staffing levels are numerical (I through IV), or adjective (Low to Extreme).

The first step in establishing Staffing Levels is the selection by the state or federal land management agency of an NFDRS component or index that best describes the total fire problems in their protection area. State and Federal land management agencies in Washington use the Energy Release Component (ERC) to determine staffing levels, or adjective class ratings for the general public.

From statistical analysis of historical fire weather data, agencies were able to determine various percentiles in the distribution of historical ERC data that serve as breakpoints for various fire management decisions. Land management agencies in Washington use the 90th and 97th percentile of the ERC as a basis for determining staffing levels. In western Washington, the 90th and 97th percentiles in the ERC frequency distribution are 44 BTUs per square foot and 55 BTUs per square foot.