The Bay Area is in for another atmospheric river storm this week, and forecasters expect the North Bay to receive the bulk of the wet weather.
The National Weather Service forecasts that the atmospheric river, moving down the West Coast from the Gulf of Alaska, is likely to bring strong winds and a slight chance of thunderstorms across the region.
A wind advisory will be in effect for the entire area from 10 p.m. Tuesday to 4 p.m. Wednesday, with wind gusts expected up to 45 mph.
During a small window on Wednesday morning, meteorologists said, isolated gusts could reach above 55 mph at the highest peaks.
While the rain will mostly be beneficial, localized nuisance flooding is possible. Minor coastal flooding could also occur Tuesday through Saturday due to spring tides.
Forecasters expect the North Bay to receive up to 2.5 inches of rain starting Tuesday. Places including Venado and Mount Tamalpais could see higher-end rain totals.
As the storm moves south, so do potential rain totals. The weather service forecasts the storm reaching San Francisco by early Wednesday morning, with up to an inch of rain in the city by the end of the day.
Places farther south, including San José, are expected to receive less than half an inch of rain.
“Treat this as a winter storm and make sure you clean out your gutters and make sure your drains are cleared out,” said Roger Gass, a meteorologist with the weather service’s Bay Area office.
The warm storm will push snow levels in the Sierra Nevada to above 7,500 feet, resulting in the bulk of the snowfall at higher elevations. Lassen National Park and the highest peaks of the Sierra could see some snowfall, and snow levels could dip below 7,000 feet on Wednesday night if temperatures fall.
Wet and slick roads will be the main concerns for the mountains, Sacramento-based forecasters wrote in the weather service’s daily forecast discussion for inland Northern California.
Weather experts measure the intensity of atmospheric rivers on a scale from 0 to 5. This week’s storm could reach as high as a 5 in the Guerneville area before decreasing to a 4 over Marin County and then to a 3 for the San Francisco area, according to the atmospheric river scale modeling by the Center for Western Weather and Water Extremes at UC San Diego’s Scripps Institution of Oceanography.
When atmospheric rivers stall over an area, they can cause rivers to rise and create dangerous flooding.
In 2022, a family of atmospheric rivers dumped so much rain over California that multiple levees crumbled from the weight and intensity of the water, destroying hundreds of homes and disrupting life for thousands of people.
Other strong atmospheric rivers have caused flooding in parts of cities like San Francisco.
Gass said the good news, as of now, is that while this week’s atmospheric river “is expected to be a little bit stronger,” it does not look like it will park anywhere over the region.
“That’s the reason that we don’t have any flood watches out,” Gass said. “We would, if it were to show signs of stalling, but we’re not seeing any of that.”
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