Notorious Santa Ana winds fan ferocious California fires
Blaze bursts into Los Angeles, igniting canyon into inferno
The winds from hell have returned. Santa Ana winds, one of the nation’s most notorious wind events, have fueled the destructive wildfires across Southern California that charred tens of thousands of acres.
This week’s windstorm is “the strongest and longest Santa Ana event so far this season,” the National Weather Service in Los Angeles said.
More than 1,700 personnel are tackling the Thomas Fire in Ventura County, which has burned at least 150 structures since Tuesday. Wednesday, the fires invaded Los Angeles, forcing mass evacuations in the canyon area and prompting the temporary closure of a freeway. The fire cut through the hills above UCLA and relatively close to the Getty Center, home to one of the nation’s top art museums.
“Nowhere else do such winds impact so many people with so much force and possess such extensive opportunity for damage and destruction.” National Weather Service
Santa Anas are an annual weather hazard in Southern California.
“Nowhere else do such winds impact so many people with so much force and possess such extensive opportunity for damage and destruction,” the weather service said.
The winds, which occur most often in the fall and winter, push dry air from over the inland deserts of California and the Southwest. Santa Anas blow over the mountains between coastal California and the deserts. As the wind comes down the mountains, it’s compressed and warms up.
As the air warms, its relative humidity drops, sometimes to less than 20% or even less than 10%. The extremely low humidity helps dry out vegetation, which makes it a better fuel for fires.
This year’s wildfire season in California has been much worse than usual. At least 1.1 million acres have burned, about twice the average, according to the California Department of Forestry and Fire Protection.
The threat of a catastrophic wildfire season was, ironically, exacerbated by the heavy, drought-ending rains that the state received last winter, said mete- orologist Mark Bove of insurance firm Munich Re.
“The rain caused a period of rapid vegetation growth, especially in brush and grasses that cover the state’s hillsides,” he said. “But the rain stopped by spring, and the new vegetation slowly dried out, becoming ample kindling and fuel for wildfires.”
La Niña conditions are present in the tropical Pacific, which typically leads to a drier California winter, meaning that prime wildfire conditions may continue into 2018, he said.
Over the past decade, the USA has seen an increase in the frequency of wildfires that have caused significant insured property losses, Bove said, noting that this is mostly the result of new development in areas highly vulnerable to wildfires.
Bove said, “California and the American Southwest have become drier over the past century as well due to Earth’s changing climate, increasing the probability of severe wildfires occurring.”
Wildfires in California have burned about twice as much land as the annual average this year.