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Strong winds start to pick up across Southern Calif.

With a forecast of winds up to 70 mph on Thursday and Friday, drivers and residents across Southern California were on their guard.

Winds knocked over a big rig early Thursday in San Bernardino County below the Cajon Pass, NBCLosAngeles.com reported. No injuries were reported.

While this week's winds could be a serious hazard, they weren't forecast to approach the magnitude of a storm on Nov. 30 that spawned gusts approaching 100 mph. In that storm, trees were toppled, power poles snapped, homes were damaged and electricity was cut to nearly 650,000 homes and businesses.

This time around, northeast winds could reach 65 mph in many mountain areas and 40 mph in the valleys, the National Weather Service warned.

Coverage by NBCLosAngeles.com

High-wind warnings were in effect from 1 a.m. PT Thursday to 1 p.m. PT Friday in Orange, Riverside and San Bernardino counties, it said.

Isolated gusts greater than 70 mph were possible below the Cajon and Banning passes in the Santa Ana Mountains, the weather service added.

"The winds will make driving difficult, especially for motorists with high profile vehicles. ... Watch for broken tree limbs and downed power lines," it said.

Southern California Edison on Wednesday night alerted customers to take precautions because of powerful winds that are expected to blow across Southern California, the LA Times reported.

In the Pasadena area, one of the hardest hit by the November storm, crews are still clearing debris. "Work crews are working in 12-hour shifts," said city spokeswoman Ann Erdman. "They continue, night and day, to get the debris picked up. ... We have a ways to go."

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