The simulated fire is verified using a set of locations and timestamps compiled by 9News (Denver, KUSA-TV) from witnesses’ recorded footage, an After-Action Review compiled by Boulder County officials, and the official fire perimeter. We compare a control against twelve Fire-Spots simulations, and assess them in terms of arrival time and spatial metrics. All twelve Fire-Spots simulations outperform the control in all metrics. These experiments indicate spotting played a fundamental role in the rapid spread of the fire, consistent with records from the Marshall Fire and scientific literature stating that firebrands are an important mechanism to increase fire rate of spread in wind-driven fires.
These numerical experiments suggest that accounting for highly nonlinear processes, such as spot fires, can potentially improve a model ensemble and probability of outcomes, in that spotting can be a significant source of uncertainty to simulating fire spread.