Equations are presented by which to calculate the maximum firebrand particle lofting height from wind-driven line fires in surface fuels. Variables used are the fuel type, described as one of twelve stylized models used for fire behavior prediction, the fire intensity, and the mean windspeed at 10 m height. Using the maximum particle lofting height, downwind drift of the firebrand particle during lofting and maximum spot fire distance are calculable from equations presented here and published elsewhere. The model upon which the equations are based assumes that the particle is transported upward by a two-dimensional thermal. Such thermals are assumed to be generated by variations of fire intensity with time. Both assumptions are speculative and probably not subject to direct test, so the model is considered tentative. Field test of the model predictions will reveal whether or not it provides useful estimates of spot fire distance.
[This publication is referenced in the "Synthesis of knowledge of extreme fire behavior: volume I for fire managers" (Werth et al 2011).]