Extremely dangerous wildfires are threatening Southern California, including Los Angeles and Ventura counties. Overnight, the National Weather Service issued a statement warning about extreme fire weather and widespread damaging winds. Here’s what we know right now about the meteorological factors driving these fires in Pacific Palisades and surrounding coastal communities, Eaton Canyon and Sylmar.
What’s Happening?
The NWS Oxnard office posted just after midnight on the platform X that damaging winds and extreme fire were expected for most of Los Angeles and Ventura counties through Wednesday afternoon. “Time period of greatest concern: Tonight – Wednesday afternoon,” they wrote. “Widespread N/NE gusts 50-80 mph, Isolated 80-100 mph mountains/foothills with scattered downed trees and power outages likely.” So what is happening?
A series of fires fueled by the Santa Ana winds are ravaging Southern California. The Palisades fire has garnered headlines, but the Hurst and Eaton fires have also been threatening very populated areas. The fires are so large that they are clearly visible from weather satellites and even Doppler radars.
Noted scholar and Los Angeles area resident Lawrence Ross wrote on Facebook, “Pacific Palisades is one of the most expensive neighborhoods in the world and is connected to places like Brentwood (O.J. Simpson’s former neighborhood) and Malibu.”
According to NBC News, the fires have caused nearly 50,000 mandatory evacuations in the Los Angeles area, and that is likely to rise. Smoke advisories have been issued from Malibu to Beverley Hills. Fast-moving fires are engulfing the Los Angeles area, prompting mandatory evacuations for at least 49,000 people. At the time of writing, the combined acreage burned by the Palisades, Eaton and Hurst fires is approaching 5,000, and there is very little containment.
What Are Santa Ana Winds?
Ross also gave an insightful geography lesson in his post. “Los Angeles is a desert next to the ocean and next to mountains,” he wrote. This layout leads to all types of atmospheric sciences challenges, including poor air quality and the presence of the marine layer. It also makes the region vulnerable to a local wind system called the Santa Ana Winds. What are those?
Santa Ana Winds are common to this region. In fact, I will cover them later this semester in my mesoscale meteorology class at the University of Georgia. NOAA’s website explained, “Santa Ana Winds occur when air from a region of high pressure over the dry, desert region of the southwestern U.S. flows westward towards low pressure located off the California coast.” As that dry wind moves from east to west and down mountain slopes, it is compressed. That process causes something called adiabatic warming, so the winds feel warm or hot. The combination of winds exceeding hurricane levels and dryness fuels rapidly spreading fires in Southern California.
Red flag warnings have been issued by the NWS, and that means dry conditions, warm temperatures and strong winds are expected, which increases fire risks. A red flag warning means warm temperatures, very low humidity and stronger winds are expected to combine to produce an increased risk of fire danger. Residents should be aware of or executing plans in affected areas.
