Santa Ana winds, fog may affect Southland

Thanksgiving travelers beware: this week’s forecast for Southern California includes fog, Santa Ana winds and fire warnings.

The National Weather Service issued a fire weather watch for Los Angeles and Ventura counties, excluding the Antelope Valley, for Friday afternoon to Sunday morning as cool winds pick up and the humidity drops into the single digits from Malibu to the Hollywood Hills.

The weather service issued a similar fire warning for Orange and San Diego counties for Friday and Saturday.

As temperatures dip into the low 50s tonight and low 40s Friday evening, patchy fog is expected to linger, particularly in the mountains, said Weather Specialist Stuart Seto. Fog won’t be thick enough to ground flights the way it did at airports in L.A., Long Beach and Burbank on Monday, but Seto said winds could still snarl traffic.

Winds of 15 mph to 25 mph are expected Friday, with gusts of up to 65 mph in the mountains, including stretches of the 5 Freeway and the 15 Freeway.

“Traveling Friday night into Saturday is going to be tough in the mountain areas,” Seto said. “You don’t want high-profile vehicles or motorcycles that have problems in the gusting winds up there. Otherwise, visibility will be good at the airports and for driving.”

Winds are expected to die down Sunday, then pick up again late Tuesday, Seto said.

While fog reduced visibility to a quarter mile in places earlier this week, the lowest visibility expected overnight Wednesday was three miles at Los Angeles International Airport and Long Beach Airport, and five miles at Bob Hope Airport in Burbank -- not enough to ground flights.

Even if the fog thickens, only small propeller planes and commuter jets are likely to be grounded at LAX this week, according to spokeswoman Nancy Castles. But she said travelers should watch for fog-related delays on connecting flights through San Francisco, where reduced visibility could prompt a runway closure

Castles said airport managers were more concerned about snowstorms in the Midwest and Northeast than fog here. She said the stormy weather was already causing departure delays at LAX on Wednesday night.

She advised travelers to check the Federal Aviation Administration’s website for information about airport delays and to contact their airline before heading to the airport, even if the skies appear clear.

molly.hennessy-fiske@ latimes.com