Los Angeles will remain at high fire risk until next week

Devastating wildfires continued to burn across the Los Angeles metropolitan area on Friday, extending 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 emergence of new fires, as gusty winds persist amid unusually dry conditions.

The officials reported five big fires in the Los Angeles area starting Friday morning. He Palisade fire in Pacific Palisades and Malibu has consumed more than 20,000 acres, while the Fire Eaton in Altadena has grown to more than 10,000 acres. At least 10,000 structures are believed to have been destroyed across Los Angeles and 10 people have been killed.

A favorable fire climate requires dry vegetation, low humidity and strong winds. The combination of these ingredients allows fires to start easily and spread quickly; It was this dangerous mix that allowed the Palisades Fire and Eaton Fire to expand beyond any crew’s ability to control them earlier in the week.

Since then, firefighters have managed begin controlling firesaided by reinforcements from out of state, the water from the hydrants being replenishedand the wind speed decreasing. (In addition to helping the fires spread quickly, the strong seasonal Santa Ana winds early in the week (at times prevented firefighting aircraft from working to control fires with water and fire retardant chemicals). The bad news is that those winds could be about to pick up again, and that on all other fronts, conditions are not likely. in favor of firefighters in the short term.

What happens next with the weather?

He Storm Prediction CenterThe National Weather Service agency charged with issuing fire weather forecasts says the risk of fire conditions will remain elevated throughout Los Angeles through this weekend.

We could see two more moderate Santa Ana wind events in the coming days: one early in the day on Sunday and another possibly on Tuesday. These gusts could favor the spread of existing fires and the start of additional fires.

A Santa Ana wind event occurs when there is a pressure difference between the Great Basin (the vast expanse 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. A stronger pressure difference creates stronger winds that rush toward the coast, fueling existing wildfires. This is what they predict we could see again in the coming days.

Vegetation will also remain exceptionally dry across the region. We’re in the middle of the rainy season in Southern California, but there’s no rain anywhere. After recording the third-wettest February on record last year, Los Angeles International Airport has reported just 0.03 inches of rain since early last summer.

Even though mid-January is the prime time for 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 colder-than-normal water temperatures in the Pacific Ocean around the equator. Changes in the atmosphere in response to La Niña may force the jet stream to move northward over the eastern Pacific Ocean, diverting storms toward the west coast of Canada instead of the western United States, depriving of rain to states like California.

Just then, the predominant 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 fade in time for spring. Unfortunately, this timing could coincide with the start of the dry season in Southern California.

That’s not to say we won’t see opportunities for rain in the coming months. However, little to no rain until at least mid-January will keep vegetation exceptionally dry across the region. The current risk of new fires and additional fire growth will depend on episodes of low humidity with gusty winds, and any additional Santa Ana wind events could prove dangerous in the coming weeks.