284:– An NFDRS index relating to the flame length at the head of the fire, it is an estimate of the potential difficulty of fire control as a function of how fast and how hot a fire could burn. It has been scaled so that the value, divided by 10, predicts the flame length at the head of a fire. For example, an index of 75 would predict a flame length of 7.5 feet (2.3 m). It is a function of the
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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 to IV), or adjective (Low to
Extreme).
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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
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Work on a national rating system began in 1959. By 1961, the basic structure for a four-phase rating system had been outlined and the fire phase (spread phase) was ready for field testing. However, since the remaining phases of the rating system – ignition, risk, and fuel energy – were not available,
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In 1970, a preliminary version of the system was tested at field sites in
Arizona and New Mexico. In 1971, an improved version of the system was used operationally in the Southwest. Field trials were also conducted elsewhere across the country at stations from Maine to California and from Florida to
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More research followed and in 1965 a research project headquartered in
Seattle was established to provide a fresh look at the needs and requirements for a national, fire danger, rating system. After canvassing many fire control agencies across the country, the Seattle research group recommended new
52:, a fire researcher in the southeast, wrote that "One of the prime objectives of the National Fire Danger Rating System (NFDRS) is to provide as accurate a measure as possible of the relative seriousness of burning conditions and thereby, NFDRS can serve as an aid to fire control programs."
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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
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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. Both state and federal land management agencies in
Washington use the
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components of the
National Fire Danger Rating System are produced by the Wildland Fire Assessment System (WFAS-MAPS), located at the USDA Forest Service Rocky Mountain Research Station in Missoula, Montana. Current fire danger and forecast fire danger maps are available.
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a number of fire control agencies preferred to remain with the systems then in use. Adaptations, interpretations, and additions to the spread phase quickly followed, making it obvious that the spread phase was not uniformly applicable across the country.
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When work started in 1968 on the NFDRS a framework was constructed. A philosophy had to be adopted in order to allow the development of the system to proceed. NFDRS provides a uniform consistent system that possesses standards which agencies with
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rating systems in use across the United States. Better communication and better transportation were beginning to make mutual assistance agreements between fire control agencies more practical than in the past. State compacts, and in the case of the
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directions for research that would lead to the development of a complete, comprehensive, National Fire Danger Rating System. A target date of 1972 was established for getting a complete system ready for operational use.
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Burgan, Robert E. 1988. 1988 revisions to the 1978 National Fire-Danger Rating System. Res. Pap. SE-273. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southeastern Forest Experiment Station. 39 pp.
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Keetch, John J; Byram, George. 1968. A drought index for forest fire control. Res. Paper SE-38. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southeastern Forest Experiment Station. 32 pp. (Revised
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can be produced by crown fires as well as wind and topography conditions. Large burning embers are thrown ahead of the main fire. Once spotting begins, the fire will be very difficult to control.
64:, interagency and interregional agreements were bringing fire control teams together from widely separated areas of the county. It became necessary to establish a national system for estimating
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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.
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burn in grasses and low shrubs (up to 4.ft tall) or in the lower branches of trees. Surface fires may move rapidly. Ease of control depends upon the fuel involved.
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MODERATE – Fires can start from most accidental causes, but with the exception of lightning fires in some areas, the number of starts is generally low.
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LOW – Fuels do not ignite readily from small firebrands although a more intense heat source, such as lightning, may start fires in duff or light fuels.
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is sometimes referred to as the action class, adjective class, precaution class, preparedness class, or the
Industrial Fire Precaution Level (IFPL).
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is the components or simply the outputs that are based in fire behavior description but expressed in the broader context of fire danger rating.
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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
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NFDRS characterizes expected burning conditions for areas of 10,000 to 100,000 ac (4000 to 40,000 ha). The system has a low resolution.
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with user-defined constants and measured variables to calculate the daily index and components that can be used for decision support.
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VERY HIGH – Fires start easily from all causes and, immediately after ignition, spread rapidly and increase quickly in intensity.
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burn in natural litter, duff, roots or sometimes high organic soils. Once started they are very difficult to detect and control.
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burn in the tops of trees. Once started, they are very difficult to control since wind plays an important role in crown fires.
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A Fire Danger Rating level takes into account current and antecedent weather, fuel types, and live and dead fuel moisture.
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EXTREME – Fires start quickly, spread furiously, and burn intensely. All fires are potentially serious.
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Gaining and Understanding of the National Fire Danger Rating System. NWCG PMS 932 July 2002
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of a head fire in feet per minute. It is a function of fuel model characteristics,
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HIGH – All fine dead fuels ignite readily and fires start easily from most causes.
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Each day during the fire season, national maps of selected fire weather and
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Inventory of the National Fire Danger Rating System Collection, 1911–2004
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National Fire Danger Rating System (NFDRS) / John Wiley & Sons, Inc.
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to improve and simplify communications among all people concerned with
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https://gacc.nifc.gov/rmcc/predictive/nfdrs_gaining_understanding.pdf
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231:– Displays a value numerically equivalent to the predicted forward
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Alaska. The system then became operational nationwide in 1972.
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Ratings are for the worst case in the Fire Danger Rating Area.
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https://www.nwcg.gov/sites/default/files/products/pms932.pdf
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Current fire weather map from the National Weather Service
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418:(Deeming and others 1977, Bradshaw and others 1984)
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causing an ignition requiring a suppression action.
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The ratings are to be interpretable and meaningful.
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Considers containment as opposed to extinguishment.
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243:(heavily weighted to the 1-hour timelag fuels),
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121:Ratings between fuel models are comparable.
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109:Relates containment job to flame length.
96:responsibility can apply and interpret.
445:"Fire Danger System Inputs and Outputs"
431:"Fire Danger System Inputs and Outputs"
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470:WFAS – Wildland Fire Assessment System
118:Ratings are to be linear and relative.
115:Ratings are to be used in combination.
139:NFDRS recognizes four types of fire:
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55:In 1954 there were eight different
31:National Fire Danger Rating System
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518:Firefighting in the United States
269:– Displays the probability of a
220:The output section of the NFDRS
103:Considers initiating fires only.
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380:10.1002/0471743984.vse8649
277:Keetch-Byram drought index
173:NFDRS is a complex set of
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290:Energy Release Component
206:Energy Release Component
538:Meteorological indices
498:Durham, North Carolina
496:Library and Archives,
494:Forest History Society
309:Adjective Class Levels
135:Wildfire § Spread
133:Further information:
27:Wildfire hazard scale
184:Preparedness Classes
94:wildfire suppression
237:live fuel moistures
267:Ignition Component
261:live fuel moisture
241:dead fuel moisture
62:federal government
302:relative humidity
253:relative humidity
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507:Categories
347:References
245:wind speed
45:Background
271:firebrand
175:equations
169:Structure
39:wildfires
288:and the
216:Outputs
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