A spatial framework to assess spot fire transmission potential

Spotting is known to be an important fire spread mechanism and cause of fireline breaches during windy conditions, yet current fire modeling systems provide only coarse metrics of spotting behavior that are underutilized in fire operations. We developed a spatial framework to quantify and map potential sources and sinks of spot fire transmission across linear control features based on models of ember production, ember transport, and receiving fuel bed ignition probability. The framework provides several spatially explicit measures of spotting potential conditional on fire extent and weather that are designed to support fire management decisions related to control line selection and resource allocation to tasks such as line prep, retardant application, and holding operations. We evaluate the utility of the framework using two wildfire case studies with growth episodes attributed to spotting. In its current form, the model is most appropriate for relative evaluation of spot fire transmission potential from wind-driven fires. The spotting source and sink metrics may also help managers begin to think prescriptively about the control tactics necessary on both the source and receiving sides of firelines to avoid spotting breaches. Improvements to the input data and component models are needed to progress towards desired estimates of conditional breach probabilities.