Photo: Paul Chinn Paul Chinn, The Chronicle
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Gregg Solem and Leah Friedman (upper right) eat lunch under an umbrella at Hallidie Plaza in the rain in San Francisco March 9, 2016. A new storm soaking the region should bring up to 1.5 inches of rain to the ... more
The first of two storms expected to pound Northern California in coming days dumped close to two inches of inch of rain in many North Bay spots Thursday morning, causing minor flooding and mudslides and prompting fears that the Russian River would spill its banks.
The National Weather Service projected that continued rainfall would swell the Russian River to flood stage in the Sonoma County community of Guerneville by 11 p.m Friday, with water levels peaking Saturday morning.
Fortunately, said forecaster Bob Benjamin, river levels are expected to top out in low-lying Guerneville at just two feet above its 32-foot flood point, potentially causing minimal problems.
“If you’re in that area, it’s a concern,” he said, “but it doesn’t look like it’s going to be expansive flooding.”
Water managers released supplies at Lake Sonoma earlier this week — for the first time in five years — to prevent the reservoir from filling up and having to discharge water downstream during the storms.

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The Napa River in St. Helena was also projected to run slightly above flood stage at around 3 p.m. Friday, according to the weather service.
Navarro Creek in Mendocino County was expected to run even higher above its banks, between Friday morning and Sunday morning, but the rural waterway is likely to cause minimal problems.
Santa Rosa recorded 1.6 inches of rain in the morning hours Thursday and the hilly Sonoma County community of Venado logged more than 3 inches, according to the National Weather Service. Some places in the Bay Area were forecast to see more than four inches through Friday afternoon.
The storm arrived later in San Francisco, dropping less than a tenth of an inch of rain before noon Thursday. The city was expected to pick up 1.5 inches through Friday.
Highway 1 along the coast was seeing the brunt of the problems. The road was closed in Sonoma County at the community of Valley Ford and at Freestone Valley Ford Road because of flooding, according to the California Highway Patrol. There was also tricky passage just south of the community of Tomales in Marin County because of a slide.
Another small mudslide was blocking part of Highway 29 north of Calistoga, the CHP reported.
A flood advisory was in effect for Marin, Napa and Sonoma counties, and much of the Bay Area remained under a flash flood watch through the weekend.
“We’ve had some minor flooding and standing water on Highway 101, but what we’re mostly focused on is flooding in creeks in West Sonoma,” said CHP Officer Jon Sloat.
The CHP advised commuters not to drive through standing water and to note alternate routes in case of road closures.
Conditions were expected to mostly dry out by Saturday morning, according to the weather service, with a slight chance of showers on Saturday before another storm moves in Sunday.
Hamed Aleaziz is a San Francisco Chronicle staff writer. Email: haleaziz@sfchronicle.com Twitter: @haleaziz