The second in a series of storms expected to soak the Bay Area delivered on Friday, dumping as much as 8 inches of rain in some areas, causing widespread but mostly minor flooding and snarling traffic with spinouts, jackknifed trucks, landslides and more.

Thousands of PG&E customers lost power during the course of the storm, but crews stationed across the region were working quickly to restore service. By 2 p.m., about 3,400 customers were still without power, according to spokeswoman Fiona Chan.

The heaviest portion of the storm had mostly passed over the North and East Bay by noon, but the South Bay was still seeing strong rain, according to Diana Henderson, a forecaster with the National Weather Service. Medium and light showers will likely continue over the entire region into Friday, with the next major storm arriving Saturday night, she said.

The steady downpour delivered significant rainfall totals to the region during a span of 24 hours ending at 11 a.m. Friday. Central Contra Costa County got a strong soaking, with 3.34 inches reported in Moraga and 1.47 inches in Concord. Oakland recorded 1.35 inches and San Jose got 1.19 inches of rain.

Lexington Hills, just south of Los Gatos, reported nearly 7.5 inches of rain. The North Bay took the heaviest rainfall, with peak levels of 8 inches in Sonoma County and 6.4 inches in Napa County; Monterey County also reported 8 inches in the city of Greenfield.

The weather service issued an urban and small stream flood advisory for the nine Bay Area counties. The advisory, which extends through 2:30 p.m., notes that heavy rainfall is likely to lead to pooling in low-lying areas and locations with poor drainage.

The wet conditions were causing problems on most Bay Area roadways, with the California Highway Patrol reporting dozens of traffic collisions on Friday, including a spin out on Highway 4 in Antioch that left two people, including a child, with minor injuries.

Flooding was reported "all over" Bay Area roads, according to CHP officer James Evans.

Power outages temporarily knocked out lights on the Bay Bridge, the San Mateo Bridge and the Richmond-San Rafael Bridge, though no major crashes were reported. The Bay Bridge outage, which lasted from about 6 to 9:30 a.m., also took out the high-powered electronic billboards at the eastern anchorage in Oakland. A high-wind advisory was issued for bridge drivers as gusts peaked at 30 mph.

Flooding closed 42nd Avenue in Oakland from Interstate 880 to International Boulevard around noon, and later a westbound lane on Stanley Boulevard was closed by flooding; both roadways were expected to be closed until 6 p.m.

A big-rig driver lost control of his truck, flipping one of the trailers and blocking lanes on eastbound Interstate 580 near North Flynn Road just after 6 a.m. All lanes were reopened around 8:20 a.m. At least two other crashes had snarled traffic on I-580 earlier in the morning, one near the Interstate 680 interchange and another east of Livermore.

"580's been a mess," Evans said. "We've had a ton of things going with major slowdowns."

Highway 84 also took a beating, with heavy flooding in Newark, between Decoto Road and Newark Boulevard.

A landslide also forced the closure of both directions of Highway 84 between Mission Boulevard in Fremont and Main Street in Sunol around 7 a.m., but lanes were reopened around 8 a.m. On the other side of the bay, a falling tree pulled power lines down, blocking both lanes of the highway in Woodside, from Grandview Road and Highway 35; That closure was cleared around 7:45 a.m.

PG&E's map showed outages all over the Bay Area, with more than 2,500 customers without power in Richmond, Antioch, Danville, Dublin, Pleasanton, Fremont, San Jose, Saratoga, Woodside, Sunnyvale, Menlo Park, Burlingame and San Bruno.

As on Wednesday, the severe weather forced officials at San Francisco International Airport to institute a "traffic management program," limiting takeoffs and landings, forcing the cancellation of about 60 flights and causing arrival delays of up to three and a half hours. No major delays were reported at Oakland or San Jose airports.

The weather service also issued a flash flood watch for the North Bay, San Francisco, the peninsula, and the Santa Cruz Mountains scheduled to last through Monday morning. A flash flood warning -- meaning that flooding is imminent or already occurring -- was in effect for Sonoma County through 9:15 a.m.

In Marin County, scattered power outages were reported overnight, from Lucas Valley to Inverness affecting about 4,500 homes as winds toppled trees that took down utility lines.

Heavy rain and wind caused flooding in Watsonville and knocked out power for more than 14,000 Santa Cruz County residents Friday morning.

The rising level of the Pajaro River flooded Beach Road Friday morning, but a sandbar that blocked the river from the ocean was breached about 1:20 p.m., Santa Cruz County officials said.

When those roads flood, they can trap Pajaro Dunes residents in their neighborhood. Most but not all vehicles could pass Friday morning through 1 foot or more of standing water.

In Los Gatos, officials announced that they would delay Friday night's annual treelighting until next week because of the wet whether, though Saturday's annual Children's Parade will still take place.

The Bay Area can expect periods of heavy rain through the weekend. After Friday's storm moves on, the next system will move in Saturday night into Sunday morning, with showers trailing off Monday.

Santa Cruz Sentinel reporters Stephen Baxter and Jessica M. Pasko and Bay Area News Group reporter Judy Peterson contributed to this report. Bay City News Service contributed to this report. Contact Daniel M. Jimenez at 925-943-8013. Follow him on Twitter @DMJreports. Contact Mark Gomez at 408-920-5869. Follow him on Twitter @MarkMgomez.