Southern California Faces Extreme Fire Risk From Dry Winds

(Bloomberg) -- Dry and warm gusts blowing in from the desert have elevated the wildfire risk in Southern California to critical, several weeks after deadly flames tore through wine country to the north.

The strongest Santa Ana winds of the season threaten more than 14,000 square miles (36,260 square kilometers) covering a population in excess of 19.9 million, according to the U.S. Storm Prediction Center in Norman, Oklahoma. That includes Los Angeles, San Diego and San Bernardino. They're expected to last through Thursday.

“Fire does very well in those conditions,” said Richard Bann, a forecaster at the U.S. Weather Prediction Center in College Park, Maryland. “The fuels, the grasses, anything that might have been growing, they are cured and ready to burn. You get any of these conditions and a fire starts.”

Winds could pick up to 40 to 60 miles (64 to 97 kilometers) per hour, with very low humidity bringing on the “potential for the strongest, longest duration Santa Ana event of the season,” the National Weather Service said. Dust storms could kick up and power disruptions are possible as winds knock down lines and trees. At least 43 people were killed when deadly fires swept through the wine growing regions north of San Francisco in October.

Parts of Ventura, Orange, San Bernardino and Riverside counties face the greatest risk, the Storm Prediction Center said. The danger won't be as severe in downtown Los Angeles.

A total of 8,691 fires consumed more than 1 million acres in California this year through Nov. 26, according to the state Department of Forestry and Fire Protection. 

A difference in barometric pressure from north to south is the root cause of the latest weather event, Bann said. “That funnels the winds through the gaps in the mountains and foothills of Southern California.”

Because the winds cross land on their way south, they tend to be very dry. The worst will be seen through Tuesday, though California can't count on any relief until the weekend at the earliest.

“If we look into Wednesday and Thursday, there might be improvement but the improvement isn't really great,” Bann said.

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net.

To contact the editors responsible for this story: Lynn Doan at ldoan6@bloomberg.net, Stephen Cunningham

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