Powerful winds knocked out power to thousands of Southern California homes Thursday, closed the state's main north-south artery and forced firefighters trying to save a church to balance on ladders while holding chain saws.
The winds swept through already parched foothills and mountains, causing humidity levels to dip and prompting the National Weather Service to issue a "red flag" fire danger warning.
The conditions are expected to continue until at least midday today, said Stuart Seto, a weather specialist for the National Weather Service in Oxnard.
Though winds typically averaged about 30 mph, some gusts approached hurricane speeds, including some that reached 80 mph, Seto said.
"If you're driving down the freeway and the wind is 30 to 40 mph, you can adjust your steering wheel," Seto said. "But then all of a sudden a really strong gust will come and catch you off guard."
That happened numerous times Thursday, including one in which a big rig overturned about 10:35 a.m. on southbound Interstate 15 along the Fontana foothills.
California Highway Patrol Officer Sean Cooper said the truck was smacked by gusts of more than 55 mph. Two hours earlier, Cooper said, another big rig had been knocked over in Rancho Cucamonga.
In Tujunga, a downed call box pole fell across westbound lanes of the 210 Freeway, and truck drivers pulled over to tie down cargo.
Brian Humphrey, a spokesman for the Los Angeles Fire Department, said firefighters responded to several precarious, wind-driven events.
Shortly after 8 a.m., they went to the 15000 block of Ventura Boulevard in Sherman Oaks after a large steel sign above a storage facility was nearly toppled and left hanging precariously.
"The winds were gusting at about 40 mph, threatening to move the sign in a kite-like fashion," Humphrey said. "We couldn't predict the trajectory of the sign, how it was going to behave. So, regrettably, we had to close Ventura in both directions for at least 90 minutes."
Firefighters, buffeted by the winds, used cables and chains to hold the sign in place while the business owner brought in someone to repair it.
About 9:50 a.m., power lines blown loose by the winds landed on the roof of a church in the 2000 block of 5th Street in San Fernando, Humphrey said, starting a fire. To prevent the wind-whipped blaze from spreading, firefighters atop a truck ladder cut holes in the roof with chain saws. The 40 mph gusts made that job extra dangerous, Humphrey said.
"With chain saws in hand ... they balanced on the balls of their feet," he said. "Imagine a firefighter balancing on a ladder with wind gusts, holding a chain saw."
Firefighters were able to save the Ancient Church of the East Mar-Shaleeta Parish, which sustained $70,000 in damage, Humphrey said.
The winds knocked out power to thousands of homes and businesses. Joe Ramallo, a spokesman for the Department of Water and Power, said that a day before he had been gratified that so few utility DWP customers in Los Angeles had lost power in routine outages.
"There were only 12 customers citywide out of 1.2 million before the winds picked up. That's as good as it gets," Ramallo said. "As soon as the winds picked up, I saw the numbers go up."
More than 15,000 DWP customers lost power in Los Angeles on Thursday, though most for relatively short periods. Southern California Edison officials reported that about 210,500 customers experienced some kind of service interruption as a result of the winds. Additionally, the Orange County cities of Irvine, Costa Mesa and Newport Beach were hit with major outages Wednesday and Thursday.
"We have a jet stream on steroids screaming out of the north down the spine of the Sierras all the way to San Diego," said William Patzert, a meteorologist for the Jet Propulsion Laboratory in La Canada Flintridge.
Patzert said the winds were being steered by a counterclockwise rotating low pressure system to the east, making them Santa Anas. They were causing humidity levels to plummet.
"Right now at JPL, we're down to 11% and dropping," he said. "By 3 o'clock this afternoon, I expect humidity levels to be down to 8%."
That's bad news, because since July 1, Los Angeles has recorded only 1.31 inches of rain.
"For this day, we should normally be at 3.47 inches," Patzert said Thursday. "We haven't had any real rains. We need a good weeklong soaker and good jump start here on our snowpack."
Snow and ice on the Grapevine closed the 4,000-foot-high stretch of Interstate 5 in the Tejon Pass north of Los Angeles for about 11 hours. By late morning Thursday, it was reopened.
In Orange County, Steve Reuter, Huntington Beach marine safety officer, said the heavy winds meant sand was blowing everywhere.
"Everything is pretty dirty and dusty," he said. "The sand is everywhere."
Although beach crews were able to clear accumulated sand off bike paths early Thursday, getting sand out of grassy beach areas "will be a multiday project," he said.
Patzert said conditions were not ideal for surfing.
"The best surf conditions are before storms, because that's when you get the long wavelengths," said Patzert, an occasional surfer. "Right now, the surf is mixed. You got short wave lengths and long wave lengths. It's what I call garbage surf. Instead of a nice, clean ride, you're really knocked around."
Seto of the National Weather Service said strong and repeated wind episodes are common in December. "Santa Anas typically occur between October and April," Seto said. "But the highest occurrence is in December and parts of January."
But he said that by this afternoon, the winds should begin to subside and continue to do so over the weekend.
"By Saturday, they should pretty much be 10 to 15 mph," he said.
Times staff writers Maeve Reston, Jennifer Delson and Jessica Garrison contributed to this report.