FOCUS – Two fires broke out in California, United States, on Tuesday January 7. These fires are fueled by the “Santa Ana wind”, frequent in the south of this state from October to March.
Flames are once again ravaging California, United States. Late in the morning, Tuesday, January 7, a spectacular fire broke out in Pacific Palisades, an affluent neighborhood in the mountains northwest of Los Angeles, forcing thousands of people to flee their homes. 1,200 hectares of vegetation have already gone up in smoke. In the evening, another fire broke out near Pasadena, north of the City of Angels and ravaged more than 400 hectares.
These fires are fanned by the Santa Ana winds. Gusts of 160 km/h are expected this Wednesday, the US Weather Service (NWS) warned. Enough to spread the flames very quickly and create a “mortal danger”. “This is expected to be the strongest wind event in this region since 2011”warned Daniel Swain, specialist in extreme events at the University of California (UCLA), to AFP.
A violent, dry and hot wind
Characteristic of the Californian winter, Santa Ana winds are common in the south of this state during the coldest months of the year, from October to March. “Named after the Santa Ana Canyon in southern California and a staple of local legends and literature, this desert wind is violent, dry and hot – often scorching”explains the Department of Atmospheric and Oceanic Sciences at UCLA.
Contrary to what newbies might think, Santa Ana winds are not hot due to their desert origin. «[Ils] form when the desert is relatively cold. High pressure builds over the Great Basin (Nevada and part of Utah) and the cold air there begins to descend.explains UCLA. “However, this air is forced downward, compressing it and warming it at a rate of about 10°C per kilometer of descent. As its temperature increases, the relative humidity decreases. The air dries as it reaches sea level and gains speed as it is channeled through passes and canyons.”
Disrupt relief operations
Santa Ana winds are therefore very dangerous and can cause a lot of damage. “Fast, hot winds dry out vegetation, increasing the risk of wildfires. Once fires start, winds fan the flames and accelerate their spread.continues the study department. Still according to UCLA, “Santa Ana episodes tend to last only a few days, although very prolonged events occasionally occur”.
Likewise, these winds can, due to their dangerousness, disrupt rescue operations by immobilizing planes and emergency services. “Even though the plane can fly, strong winds affect retardant and water drops” and therefore their ability to directly reach the fire, declared to the New York Times Jesse Torres, battalion chief with the California Department of Forestry and Fire Protection. Santa Ana winds can also “toppling trees, which endangers people and can interfere with emergency vehicles and evacuations from danger areas”he added. More than 250 firefighters are currently mobilized in California.
These winds, sometimes nicknamed “devil winds” or “red winds,” have entered American mythology. In his short story Red Wind Raymond Chandler spoke about it like this: “There was a desert wind blowing that night. It was one of those hot, dry Santa Ana winds that come down through the mountain passes and make your hair frizz, make you jump, and make your skin itch.” The novelist Joan Didion and the writer Michael Connelly also refer to it in their works.
