How 'hellish' Santa Ana winds are fueling destructive fires around Los Angeles
The winds from hell have returned.
Santa Ana winds, one of the nation's most notorious wind events and an ongoing weather hazard in Southern California, have helped fuel the destructive wildfires in Los Angeles this week.
The winds, which occur most often in the fall and winter, push dry air from over the inland deserts of California and the Southwest toward the coast, the National Weather Service said.
This is the second time this winter that Santa Anas have fueled fires in California. Just a few weeks ago, in mid-December, Malibu's Franklin Fire was fanned by these winds.
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They typically blow when high pressure builds over the Great Basin (the high plateau east of the Sierra Nevada), according to meteorologist Jan Null of Golden Gate Weather Services. Santa Anas then blow over the mountains between the deserts and coastal California. As the wind comes down the mountains, it's compressed and warms up.
This time, an area of high pressure over the Great Basin combined with a storm in northwestern Mexico to create the conditions for strong winds over Southern California starting on Tuesday, said AccuWeather meteorologist Gwen Fieweger.
Dryness provides better fuel for fires
As the air warms, its relative humidity also drops, sometimes to less than 20% or even less than 10%. The extremely low humidity helps dry out vegetation, making it a better fuel for fires.
Adding to the dryness, over 83% of Los Angeles County was in a drought, according to the most recent U.S. Drought Monitor.
"Nowhere else do such winds impact so many people with so much force and possess such extensive opportunity for damage and destruction," the National Weather Service said.
Long fire season in California
Although Santa-Ana driven wildfires are a natural part of California’s landscape, the fire season in the state and across the West is starting earlier and ending later, according to CalFire.
Climate change is a key driver of the trend, CalFire said. Warmer spring and summer temperatures, reduced snowpack and earlier spring snowmelt create longer and more intense dry seasons that increase moisture stress on vegetation and make forests more susceptible to severe wildfires.
"November, December, now January — there’s no fire season, it’s fire year," California Gov. Gavin Newsom said during a news conference on Tuesday. "It’s year-round."
Contributing: Terry Collins
This article originally appeared on USA TODAY: How Santa Ana winds are fuel for destructive fires in California