A surge in wildfires swept swiftly across Los Angeles, driven by strong Santa Ana winds, arid conditions, and dry vegetation resulting from scant rainfall. The region grappled with at least five active fires in Los Angeles County, including the Palisades Fire, which ballooned from 10 acres to over 17,000 acres in just three days, and the Eaton Fire, which expanded to more than 10,600 acres in the foothills of the San Gabriel Mountains, as per Cal Fire reports. The causes behind these massive blazes are presently under investigation by Cal Fire officials. The environment was ripe for ignition, heightened by a dire combination of low humidity and destructive winds reaching speeds of up to 100 mph in select areas, creating conditions conducive to significant fire activity.
The National Weather Service office in Los Angeles issued warnings about the perilous blend of low humidity and potent winds, foretelling the eruption of massive fires with extreme fire behavior. Luca Carmignani, an assistant professor at San Diego State University and former fire advisor for the Wildland Urban Interface in Southern California, emphasized the heightened fire risk due to the exceptionally dry vegetation combined with the dry and gusty Santa Ana winds. Carmignani noted that the rapid spread of the fires once ignited was not unexpected given these perilous conditions.
Fueling the destructive wildfires were the notorious Santa Ana winds, prevalent during the fall and winter months. These winds propel dry air from California’s inland deserts and the Southwest towards the coast, as elucidated by the National Weather Service. High-pressure systems moving eastward over the Santa Ana Mountain range force the wind downward, leading to compression and warming. A conjunction of high-pressure in the Great Basin and a storm in northwestern Mexico engendered strong winds over Southern California, as analyzed by AccuWeather meteorologist Gwen Fieweger. The Santa Monica and San Gabriel Mountains, characterized by canyons and valleys, act as wind channels, expediting the spread of wildfires in these mountainous terrains.
Janice Coen, a project scientist at the National Center for Atmospheric Research in Boulder, Colorado, highlighted how the Santa Ana winds desiccate vegetation on mountain ridges and can transport embers over vast distances, accelerating the pace of wildfires. The rapid proliferation of the fires was further exacerbated by the preceding prolonged dry spell, with over 83% of Los Angeles County in a state of drought according to the latest U.S. Drought Monitor. Los Angeles had not experienced measurable rainfall since April, as per AccuWeather. The absence of rain, coupled with low humidity levels, contributed to the arid conditions conducive to rapid fire spread.
AccuWeather meteorologist Heather Zehr attributed the abundance of dry fuel to several wet winters preceding the current drought, which led to flourishing vegetation now transformed into tinder by the prevailing dry spell.
