Devastating wildfires continued to burn across metro Los Angeles on Friday, prompting mandatory evacuations and school closures across the region. Next week promises little chance of relief; conditions will remain favorable for both the growth of existing wildfires and the outbreak of new fires, as gale-force winds continue to blow in unusually dry conditions.
Officials reported five big fires throughout the Los Angeles area as of Friday morning. The Palisades Fire in the Pacific Palisades and Malibu has consumed more than 20,000 hectares, while Eaton Fire in Altadena it has grown to more than 10,000 hectares. At least 10,000 structures are thought to have been destroyed across Los Angeles and 10 people were killed.
Favorable weather for wildfires requires dry vegetation, low humidity and strong winds. The combination of these ingredients allows fires to ignite easily and spread quickly; it was that dangerous mix that allowed the Palisades Fire and Eaton Fire to spread beyond the ability of any crew to control them earlier in the week.
Fire crews have since succeeded start fire controlwith the help of reinforcements from outside the state, because the water is in the hydrants supplementedand the wind speed decreases. (In addition to helping the fire spread quickly, high seasonal Santa Ana winds early in the week it occasionally prevented firefighting aircraft from working to fight the fire with water and fire-retardant chemicals.) The bad news is that those winds may now pick up again — and that on all other fronts, conditions are unlikely to be in firefighters’ favor anytime soon.
What happens next with time
The Storm Prediction CenterThe National Weather Service agency responsible for issuing wildfire weather forecasts says the fire risk will remain high in Los Angeles through this weekend.
We could see two more moderate Santa Ana winds in the coming days — one early Sunday and another likely Tuesday. These wind gusts can encourage existing fires to spread and ignite additional fires.
The Santa Ana wind occurs when there is a difference in pressure between the Great Basin—a vast swath of land in Nevada and Utah—and the coastal communities around Los Angeles.
Meteorologists often use the air pressure difference between Las Vegas and Los Angeles to predict these winds. The stronger pressure difference creates stronger winds that rush towards the coast, which feeds existing wildfires. This is what they predict we may see again in the coming days.
Vegetation will also continue to be extremely dry across the region. It’s the middle of the rainy season in Southern California right now — and there’s no rain anywhere. After last year’s third-wettest February on record, Los Angeles International Airport reported just 0.03 inches of rain since the start of last summer.
Despite mid-January being prime time for the rainy season in Los Angeles, there is very little hope for significant rain over the next week and a half. NOAA’s Climate Prediction Center announced Thursday that we have officially entered La Niña, a pattern of cooler-than-normal water temperatures in the Pacific Ocean around the equator. Changes in the atmosphere that respond to La Niña can force the jet stream to move northward over the eastern Pacific Ocean, which directs storms toward the west coast of Canada instead of the western U.S., starving states like California of rain.
Right now, the prevailing storm track across the Pacific Ocean will remain near the Gulf of Alaska until mid-January, providing little opportunity for rain to reach as far south as Southern California.
Forecasters expect a weak La Niña to persist through the end of winter, with a good chance the pattern will dissipate in time for spring. Unfortunately, that time could coincide with the start of the dry season in Southern California.
That doesn’t mean we might not see rain opportunities in the coming months. However, little or no rain until at least mid-January will keep vegetation extremely dry across the region. The continued risk of new fires and additional fire growth will depend on bursts of low humidity with storm-force winds—and any additional Santa Ana winds could prove dangerous in the coming weeks.