Fires in the Los Angeles metropolitan area are fueled by Santa Ana winds, a weather phenomenon known to dry hillsides to the point of flammability.
These strong winds occur when cold air accumulates in Nevada and Utah, states neighboring California. As this air mass moves west and down the California mountains, it warms and dries.
Dried up vegetation, spreading embers
Santa Ana winds can create favorable conditions for deadly wildfires, or fuel them once they rage, by drying out vegetation.
Thus, these strong winds aggravated the ongoing fires in Palisades (23,700 hectares burned) and Eaton (14,000 ha) by blowing hot embers towards areas of vegetation, dry, but still unharmed.
As firefighters continue to battle the flames, the U.S. Weather Service is forecasting “extreme fire behavior,” which will peak with winds of 70 mph in a “particularly hazardous situation (PDS)” beginning Tuesday morning.
Warmer, drier air
Santa Ana winds usually blow between September and May, usually in series of a few days.
When an anticyclone forms over the eastern California deserts, it pushes air towards the Pacific coast.
-As it descends the Santa Ana Mountains and the Sierra Nevada massif and blows through the valleys, this air compresses, warms and dries.
Southern California has long suffered from hot, dry winds that knock down trees and create clouds of dust. In 2017, the Thomas Fire was fueled by Santa Ana winds. It had destroyed more than 1000 structures.
Last week they reached an intensity not seen since 2011, according to meteorologists, with gusts of up to 160 km/h.
“Giant hair dryer”
The American daily Washington Post compares this meteorological phenomenon to a “giant hair dryer”.
Writers describe the effects of these winds on the mental health of residents. American author Raymond Chandler once wrote that the Santa Ana winds, so hot, “frizz the hair, irritate and cause itchy skin.”
Joan Didion, for her part, said that they blew “sandstorms along Route 66, drying out the hills and sinews to the point of flammability.”
