A new study led by the National Center for Atmospheric Research (NCAR) finds that different types of highly localized winds may sometimes play a much larger role in creating large, destructive wildfires—even when winds across the region are generally weak. The study was based off of computer animations and observations of the King Fire, a fire which affected California’s Sierra Nevada mountains in 2014 and burned over 97-thousand acres.
There’s only so many weather stations in the world that can measure wind, and many winds often go undetected. This is likely the case with some of these megafires in the western US. During the King Fire, flames ran 15 miles up a canyon one afternoon because of greater, localized, untracked winds related to the topography as well as those created by the blistering heat from the blaze. Given how scattered weather stations are, these localized winds are nearly impossible to catch.
NCAR also found that these localized winds played an even more significant role in the fire’s fast and destructive growth than the intense drought conditions or the amount of fuel that had already been present in the forest did.
“This brings into question several widely held and largely unquestioned assumptions, such as very large fires being caused by the accumulation of vegetation or persistent dry conditions, or requiring extreme conditions,” said NCAR scientist Janice Coen, the lead author of the study. “Even though the winds measured by nearby weather stations were weak, smaller scale localized winds and winds generated by the fire that we and fire management couldn’t detect in real-time turned out to have a much greater impact on this fire, and potentially others like it, than any of the other factors.”
The point of this study was to recognize the role of these winds to better understand the behavior of the wildfires. These winds are hard to forecast, so it can lessen warning time for people to evacuate and can make it more difficult for firefighters to contain the flames.
The authors of this research discussed at length how there is the need for computer modeling to better predict these small-scale winds in order to better predict where and when these fires will occur, as well as how they spread. “This modeling might be used to rethink and reprioritize mitigation strategies, because actions might have less or more impact than believed,” Coen said. “For example, maybe fuel reduction should focus on slopes, because the fuel has the biggest impact on fire behavior there.”
Image credit: Copyright University Corporation for Atmospheric Research (UCAR). By Patrick Cullis, licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, via OpenSky.