The results of the fires ravaging the Los Angeles metropolitan area and Southern California are catastrophic: 25 dead and more than 12,000 homes destroyed by the passage of these extreme fires. The first flames were spotted on January 7 by hikers in Joshua Tree National Park, and the state has seen no respite since.
The blazes grew larger, and faced with this inexorable progression of the flames, the authorities ordered the evacuation of 88,000 residentswhile 84,000 other people remain on alert, according to Sheriff Robert Luna.
The role of altitude winds
In the heights of the Sierra Nevada and White Mountains, at 1,200 meters above sea level, an invisible but devastating spectacle plays out. The cold, denser air plunges towards coastal areas like an aerial torrent. Alexander Gershunov, a meteorologist at the Scripps Institute of Oceanography in San Francisco, depicts this phenomenon, called Santa Ana Winds : “ These downdraft winds act like water in a blocked stream – they pool against the landform, then accelerate into aerial cascades as they cross the crests “.
Result: the humidity of the air is reduced, the flames are constantly fanned and these violent air currents project embers over long distances, triggering new outbreaks quickly. Isolated gusts reached 100 mph in the Santa Monica Mountains last week. For January 15 and 16, the National Weather Service is maintaining “red flag” alerts from central California to the Mexican border, anticipating particularly critical conditions through today.
In all, five main outbreaks have been identified : the largest, the Palisades Fire (east of Malibu), the Eaton Fire (near the town of Altadena), the Kenneth Fire (towards Calabasas) and the Auto Fire (Ventura County). Joe Biden called them the “fires” more devastating » of the entire history of California.
The fatal equation: historic drought and atmospheric turbulence
Winter 2024-2025 marked a historic record for the city of angels: the longest period without winter precipitation in 150 years ; the drought is therefore extreme. The Los Angeles region, which usually experienced five Santa Ana episodes in December and four to five in January, finds itself this year in an unprecedented situation where these winds occur without the usual counterbalance of winter rains. One of the perverse effects of global warming.
The current atmospheric pattern presents an additional anomaly: the jet stream makes an unusual loop in the upper troposphere, pointing directly toward the Los Angeles Basin. This disturbance amplifies the effect of descending windstransforming each patch of vegetation into a potential flame accelerator.
Faced with this confluence of extreme climatic events, only the absence of storms offers little respite by avoiding the risk of ignition by lightning. The massive mobilization of emergency services continues, while the Californian metropolis anxiously awaits the first saving rains of winter.
Investigations into the origin of the first fires are currently continuing. The preferred hypothesis, for the moment, seems to be fireworks that were set off to celebrate the new year. The violent winds would have restarted a slow combustion which had persisted for six days. This explanation is put forward by specialists, but the American authorities have not yet confirmed this thesis. The Santa Ana Winds show no signs of calming down, which could unfortunately further increase the human and material toll.
- The fires in California have caused 25 deaths, destroyed more than 12,000 homes, and caused the mass evacuation of tens of thousands of people.
- Strong, dry winds, combined with record drought, are fueling the rapid spread of flames on several fronts.
- The likely origin of the fires is believed to be linked to human activities, while extreme weather conditions continue to complicate rescue efforts.
By: Opera
