At about 1 p.m. on June 26, 2011, a wind-downed power line sparked a blaze in the Las Conchas area of Santa Fe National Forest. It would become the largest fire in New Mexico’s history at the time. Within hours, the flames spread to cover more than 160 square kilometers, threatening the town of Los Alamos, home of Los Alamos National Laboratory (LANL), which develops nuclear fuels and safeguards nuclear weapons, among other activities. Now, a new study identifies why the fire spread so far so fast, and the results may have implications for fire management practices in other mountainous regions.