Powerful winds will whip across the Southland Tuesday, forecasters said.

L.A. County’s strongest winds will blow across the San Gabriel Mountains, according to National Weather Service meteorologists, who forecast northwest winds of 20 to 30 miles per hour with gusts of between 40 and 50 mph through Tuesday afternoon, increasing to between 25 and 40 mph with gusts of up to 70 mph later Tuesday into Wednesday morning. The strongest of the mountain winds will blow through the Interstate 5 corridor, they said.

A high wind warning, denoting an expectation of 58-mph winds or gusts, will be in effect in the San Gabriels from 11 Tuesday morning until 3 a.m. Wednesday.

“A High Wind Warning means that damaging high winds of 58 mph or greater are likely or imminent. Secure all loose outdoor furniture in advance of the onset of strong winds,” warned an NWS statement. “Winds this strong may down trees and power lines, causing property damage or power outages. Cross winds can make driving difficult, especially for drivers of high profile vehicles and vehicles towing trailers.”

A less serious wind advisory, signifying winds or gusts of 35 mph, will be in force in much of the remainder of L.A. County, also from 11 a.m. Tuesday to 3 a.m. Wednesday.

The advisory will be in effect in L.A. County beach cities, metropolitan L.A. including the Downtown area, the Hollywood Hills, the San Fernando, San Gabriel, Santa Clarita and Antelope valleys, The Santa Monica Mountains Recreational area, and Catalina.

West-to-northwest winds of 20 to 30 mph with gusts of up to 55 mph are forecast in those areas.

Along the L.A. County coast, where surf of 4 to 7 feet is expected, a high surf advisory will be in force until 7 a.m. Wednesday.

“There is an increased risk for ocean drowning. Rip currents can pull swimmers and surfers out to sea. Large breaking waves can cause injury, wash people off beaches and rocks, and capsize small boats near shore,” the NWS warned in a statement. “Swim near a lifeguard. If caught in a rip current, relax and float. Don’t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.”

The NWS forecast mostly partly cloudy skies in L.A. County Tuesday and highs of 57 on Mount Wilson; 65 in Lancaster; 66 in Palmdale; 67 in Avalon; 71 in Saugus; 72 at LAX; 75 in Downtown L.A.; 76 in Long Beach; 76 in Long Beach; 77 in Pasadena, San Gabriel; Burbank, and Woodland Hills.

Sunny skies were forecast in Orange County, along with highs of 59 on Santiago Peak; 65 in San Clemente; 66 in Laguna Beach and on Ortega Highway at 2,600 feet; 71 in Trabuco Canyon; 72 in Fremont Canyon; 73 in Mission Viejo; 76 in Irvine; 77 in Yorba Linda; 78 in Anaheim; and 79 in Fullerton.

Similar temperatures are expected Wednesday, although sunny skies are expected in L.A. County.

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