Rain fell steadily in some Bay Area cities on Wednesday morning. In still others, it dumped buckets.

The brief but powerful storm brought pea-sized hail to San Francisco, nearly an inch of rain to some areas of the North Bay and the mountains of Santa Clara County, and amped up the sky near San Francisco International Airport with thunder, according to the National Weather Service.

What it didn't do is make an imprint on California's worst drought in memory.

"It would have to rain five times the normal monthly totals through June to even catch up," forecaster Steve Anderson said. "Going back into the record books, back to the 1800s, no month has ever received the totals we would need. It's going to take a lot of rain over a lot of time."

By noon, the storm had rolled out of most of the Bay Area. A second, stronger system is expected to arrive in the region on Friday and bring its heaviest rainfall on Saturday, Anderson said.

By Wednesday afternoon, 2.06 inches had fallen at high elevations near Woodside in San Mateo County. Rainfall totals in Danville (.93 inches), San Lorenzo (.79) and the San Bruno Mountains (.70) paced Contra Costa, Alameda and San Mateo counties, respectively.

Storm cells varied in the amount of rain and were spread apart, leading to large variations across the region, Anderson said. Only .29 inches fell at San Francisco International Airport and only .09 inches at Mineta San Jose International Airport as of 11 a.m.


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On the roads, the rain caused some spinouts and flooding but no serious accidents. A vehicle turned over on Marsh Creek and Morgan Territory roads in Contra Costa County near Mount Diablo, but a man was able to get out of the car without help and suffered only minor injuries, authorities said.

In Orinda, a basketball-sized boulder rolled onto the freeway and broke into several pieces, forcing a some cars to spin off the road, according to the California Highway Patrol. No injuries were reported.

Flooding also blocked a lane on Highway 84 near Hayward on Wednesday morning.

The heaviest of the storm was en route to the Sierra Nevada, but forecasters were unsure about how much snow it might dump. The weather service said snow was more likely to fall near Yosemite.

Contact Rick Hurd at 925-945-4789, and follow him at Twitter.com/3rderh.