(Effective July 1, 2023)

PDFWAC 51-55-0900

Chapter 9Fire danger rating system.

User note:About this chapter: The fuel models included in Chapter 9 are only general descriptions because they represent all wildfire fuels from Florida to Alaska and from the East Coast to California.
The National Fire Danger Rating System (NFDRS) is a set of computer programs and algorithms that allows land management agencies to estimate today's or tomorrow's fire danger for a given rating area. NFDRS characterizes fire danger by evaluating the approximate upper limit of fire behavior in a fire danger rating area during a 24-hour period based on fuels, topography and weather, or what is commonly called the fire triangle. Fire danger ratings are guides for initiating presuppression activities and selecting the appropriate level of initial response to a reported wildfire in lieu of detailed, site- and time-specific information.
Predicting the potential behavior and effects of wildland fire are essential tasks in fire management. Surface fire behavior and fire effects models and prediction systems are driven in part by fuelbed inputs such as load, bulk density, fuel particle size, heat content and moisture content. To facilitate use in models and systems, fuelbed inputs have been formulated into fuel models. A fuel model is a set of fuelbed inputs needed by a particular fire behavior or fire effects model. Different kinds of fuel models are used in fire spread models in a variety of fire behavior modeling systems. The fuel models in this appendix correlate with the light, medium, and heavy fuel definitions found in Chapter 2 of the code.
901 Fuel models.
901.1 General. The Fuel Model Key is provided in Table 901.1. Fuel Models are described in Sections 901.1.1 through 901.1.20.
TABLE 901.1
(No change to the table)
901.1.1 FUEL MODEL A. (No change to the text)
901.1.2 FUEL MODEL B. (No change to the text)
901.1.3 FUEL MODEL C. (No change to the text)
901.1.4 FUEL MODEL D. (No change to the text)
901.1.5 FUEL MODEL E. (No change to the text)
901.1.6 FUEL MODEL F. (No change to the text)
901.1.7 FUEL MODEL G. (No change to the text)
901.1.8 FUEL MODEL H. (No change to the text)
901.1.9 FUEL MODEL I. (No change to the text)
901.1.10 FUEL MODEL J. (No change to the text)
901.1.11 FUEL MODEL K. (No change to the text)
901.1.12 FUEL MODEL L. (No change to the text)
901.1.13 FUEL MODEL N. (No change to the text)
901.1.14 FUEL MODEL O. (No change to the text)
901.1.15 FUEL MODEL P. (No change to the text)
901.1.16 FUEL MODEL Q. (No change to the text)
901.1.17 FUEL MODEL R. (No change to the text)
901.1.18 FUEL MODEL S. (No change to the text)
901.1.19 FUEL MODEL T. (No change to the text)
901.1.20 FUEL MODEL U. (No change to the text)
[Statutory Authority: RCW 19.27.031, 19.27.074, and 19.27.560. WSR 23-02-056, § 51-55-0900, filed 1/3/23, effective 7/1/23.]