Santa Ana winds, red flag fire warnings on Thanksgiving in Southern California

Downed trees and thousands of people without power. Thanksgiving in parts of Los Angeles and Ventura counties kicked off with a red flag warning and hot, dry gusts of Santa Ana winds that were expected to taper out by Friday morning.

A high-wind advisory was in effect for much of Thursday in the San Fernando Valley, Santa Clarita Valley, the Ventura valleys, as well as for the Santa Monica and Los Angeles County mountains. Winds gusted as high as 71 mph in more mountainous areas. One particularly windy hot spot between Santa Clarita and Burbank — known as the Magic Mountain Truck Trail — hit 99 mph Thursday, according to the National Weather Service.

With winds expected to remain fairly gusty until late Friday morning, weather officials advised fire-prone communities to remain alert.

"The fire danger will exist through tomorrow," said Ryan Kittell, a meteorologist at the National Weather Service in Oxnard. "The air will still be dry enough to cause that heightened fire risk."

A brush fire dubbed the Sandstone fire broke out Thursday afternoon in an unincorporated, mountainous part of Ventura County. It did not destroy any structures and caused no injuries before being quickly contained and extinguished. The county fire department tweeted that it ultimately mapped the fire at about half an acre.

The winds marked the third Santa Ana event in a week after powerful gusts toppled semi-trucks, damaged electrical equipment and ignited a blaze in a Fontana pallet yard.

As a precaution against a downed power line sparking a fire, Southern California Edison cut electricity to thousands of customers Thursday.

At 2:30 p.m. Thursday, more than 4,200 customers in Riverside County and 3,150 customers in Ventura County were subject to a temporary, proactive “public safety power shutoff," the company said.

Santa Ana winds, the infamous, often-devastating winds that mark a distinctly California season, tend to wreak havoc each fall when a dome of cold, high-pressure air develops over Nevada and the Great Basin area. This high pressure forces the air to spread in all directions — including over the mountains and toward Southern California.

Rather than a coastal breeze flowing in from the ocean toward land, the wind conditions in Los Angeles are flipped during these high-pressured events: Santa Anas blow in super-fast and superheated, descending down mountain slopes, kicking up the foothills and taking down trees as they gust their way toward the sea.

Because of this flip, temperatures typical of Southern California’s various microclimates are also flipped. Beach towns along the Los Angeles and Ventura coasts are expected on Thursday and Friday to experience warmer, more sunny weather, with temperatures in the mid-70s to lower 80s. The mountains and deserts, on the other hand, will remain cooler and in the mid-60s.

Temperatures are expected to cool across the region by Saturday, with temperatures in the mid-60s and lower 70s. There is also a chance for light rain Monday and Tuesday, but officials said the weather models were still too far out to determine a more precise forecast.

This story originally appeared in Los Angeles Times.