Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model
Document Type: Book
Author(s): Patricia L. Andrews
Publication Year: 2012

Cataloging Information

  • crowns
  • fire danger rating
  • fire danger rating
  • fire management
  • fire spread
  • flame length
  • forest management
  • fuel accumulation
  • fuel models
  • overstory
  • rate of spread
  • statistical analysis
  • surface fires
  • surface fuels
  • wildfires
  • wildland fire
  • wind
Record Maintained By:
Record Last Modified: January 6, 2020
FRAMES Record Number: 51434
Tall Timbers Record Number: 28301
TTRS Location Status: In-file
TTRS Call Number: A13.88:RMRS-266
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.


Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling system is used to demonstrate WAF calculation and effect on modeled fire behavior. There are differences in implementation of the same basic wind adjustment models in various fire behavior applications, including the Fireline Handbook and FARSITE. Differences are due to assumptions such as tree shape and rules for transition from sheltered to unsheltered conditions. Specifics are given for differences among WAF tables and from calculation applications. This technical documentation is useful to analysts, system developers, fire weather meteorologists, and those who are interested in model background and foundation.

Andrews, P. L. 2012. Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model. General Technical Report RMRS-GTR-266. Fort Collins, CO, USDA Forest Service, Rocky Mountain Research Station.