No­to­ri­ous Santa Ana winds fan fe­ro­cious Cal­i­for­nia fires

Blaze bursts into Los An­ge­les, igniting canyon into in­ferno

USA TODAY US Edition - - FRONT PAGE - Doyle Rice

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.

DAN MACMEDAN/USA TO­DAY

A wild­fire in L.A. on Wed­nes­day prompted mass evac­u­a­tions and the clo­sure of a free­way.

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