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In California fires, a starring role for the wicked wind of the West

REUTERS/David McNew

Originally published by E&E News

Powerful winds are spreading Southern California fires that have destroyed at least 175 structures and forced more than 27,000 evacuations.

The wind is expected to bedevil firefighters for several more days, with large blazes raging in Ventura, Los Angeles and San Bernardino counties. And while the fires’ causes are under investigation, it’s clear that high winds made the conflagrations so destructive.

Called the Santa Anas, the dry winds typically hit in late fall and are infamous in the Golden State.

California’s biggest and deadliest fires have been propelled by Santa Ana winds, which can gust to 100 mph (161 km/h). That wind speed makes smothering fires nearly impossible, said Chief Daniel Berlant, assistant deputy director the California Department of Forestry and Fire Protection, which is best known as Cal Fire.

“In many cases, it’s all we can do just to try to control the path of the fire, trying to keep it away from people and homes,” Berlant said. “Stopping a fire when wind is 50, 60, 70 miles per hour is almost not possible.”

He added, “These fires burn into anything that’s in their path. A wind-driven fire is like a freight train, and stopping a freight train on a dime doesn’t happen.”

Helicopters can’t drop water or flame retardants in high winds, he said, because the gusts blow the liquids away.

Santa Anas also dry out trees, shrubs and grasses, turning them into tinder and spreading the blaze, he said.

“It’s the winds that spread the embers and fan the fire,” Berlant said. “That makes the fire burn fast and jump ahead, as embers fly in the high wind.”

Climate change factors also play a role.

Rain hasn’t fallen in Southern California since spring, leaving vegetation as dry as in summer. Then, during the week of Thanksgiving, Los Angeles temperatures hit 95 degrees Fahrenheit. That set the stage to make the Santa Anas even more dangerous, UCLA climate scientist Daniel Swain said.

“It’s sort of the worst of both worlds,” Swain said.

It’s a sort of double whammy wind event that we’re getting,

Daniel Swain, University of California, Los Angeles

Santa Anas occur when high pressure over the Great Basin — a vast swath of Nevada, Utah and California — compresses air, cooking it, Cal Fire Captain Mike Mohler said.

That hot air then pushes southwest toward the coast.

“Our temperatures skyrocket,” Mohler said. “Humidity decreases down to single digits.”

The current Santa Anas also came as a result of cold, dense air forming in the region near Joshua Tree. That wind starts at a higher elevation, falls lower, then accelerates as it whips through canyon passes, heading for the coast, Swain said.

“It’s a sort of double whammy wind event that we’re getting,” Swain said, with both the Great Basin region and California deserts contributing.

Wind-driven catastrophes

When Santa Anas arrive, arson, downed power lines, small plane crashes and other events have sparked catastrophic fires.

The Cedar Fire, the largest conflagration in state history, burned 273,246 acres in San Diego County in October 2003. It destroyed 2,820 structures and killed 15 people. Powered by winds, the blaze jumped a major highway. And it temporarily stopped incoming flights to San Diego International Airport and Los Angeles International Airport.

Santa Ana winds also drove the Witch Fire in San Diego County, which in October 2007 charred 197,990 acres, destroyed 1,650 buildings and killed two. That same month, there were seven other blazes pushed by Santa Ana winds. Cal Fire dubbed it the 2007 Fire Siege.

The Northern California version of the Santa Anas is called Diablo, or devil, winds, which are also east-to-west gusts.

Blowing at speeds of up to 79 mph (127 km/h), they pushed fires in October that charred parts of Napa and the surrounding areas. The Tubbs Fire in Napa alone destroyed 5,643 structures.

That group of Northern California blazes is expected to be the most destructive firestorm in state history, with insurance claims at more than $3 billion and growing. State Insurance Commissioner Dave Jones is scheduled to announce undated figures today.

Max Moritz, a fire specialist with the University of California’s Cooperative Extension, said the state needs to incorporate wind corridors into its fire hazard severity zone maps. Stricter building codes apply in places designated as high-risk (Climatewire, Nov. 29).

Cal Fire’s wildland fire scientist, David Sapsis, said the state is working to develop “area-specific wind and dryness regimes” to incorporate into revised maps of areas slated for development.

The fire threat is likely to be even greater in the future, according to a study out of UCLA, the University of California, Davis, and UC Irvine that says climate change will make the destruction from all blazes worse.

Southern California fires are very, very weather-driven. If you change the weather, you would imagine that fires might change, too, and that’s exactly what we found.

Alex Hall, University of California, Los Angeles

The researchers examined five decades of fires and found that the Santa Anas were responsible for 80 percent of the cumulative $3.1 billion in economic losses from 1990 to 2009.

Santa Ana fires spread three times faster, occurred closer to urban areas and burned into areas with greater housing values, the study said.

“Southern California fires are very, very weather-driven,” said Alex Hall, one of the study researchers and a climate expert with UCLA’s Institute of the Environment and Sustainability.

“If you change the weather, you would imagine that fires might change, too, and that’s exactly what we found,” Hall said.

The study applied climate modeling to fire patterns and projected that fires in Southern California will become more destructive. Because of drier conditions, by midcentury, the area burned in Santa Ana fires is projected to increase 64 percent. Hotter temperatures will make non-Santa-Ana fires worse, as well. By 2050, the area destroyed by non-Santa-Ana fires is expected to grow 77 percent, the study said.

‘Close to the edge’

That destructive force has made Santa Ana winds part of the Southern California culture.

They haunt books, movies and songs.

Joan Didion famously wrote in “Slouching Towards Bethlehem” that the “violence and the unpredictability of the Santa Ana affect the entire quality of life in Los Angeles, accentuate its impermanence, its unreliability. The wind shows us how close to the edge we are.”

T.C. Boyle’s novel “The Tortilla Curtain” makes drought, the Santa Anas and a forest fire central to his story of race, class and labor in Los Angeles in the 1980s and ’90s, said Allison Carruth, an associate professor of English at UCLA.

Novel-turned-movie “White Oleander,” from Janet Fitch, casts Santa Anas as an omen of destructive behavior.

“The Santa Anas blew in hot from the desert that fall,” it says early on. “Only the oleanders thrived. Maybe the wind was the reason my mother did what she did.”

They even appear in children’s fare. The short movie “Halloween Is Grinch Night,” written by Dr. Seuss, mentions the howling “sour, sweet winds.” Dr. Seuss, aka Theodor Seuss Geisel, retired in San Diego.

Santa Anas star in music, too. The song “Los Angeles Is Burning,” by Bad Religion, warns, “When the hills of Los Angeles are burning, palm trees are candles in the murder wind. So many lives are on the breeze, even the stars are ill at ease. And Los Angeles is burning.”

Reprinted from Greenwire with permission from E&E News. Copyright 2017. E&E provides essential news for energy and environment professionals at www.eenews.net

News credit : Sciencemag

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