Atmospheric Rivers to Deliver ‘One-Two Punch’ of Strong Bay Area Rain, Sierra Snow

Updated 1:25 p.m. Monday

After days of wet weather, two more atmospheric rivers are forecast to drop heavy rain on Northern California this week, increasing flood potential in the Bay Area starting Monday and blanketing the Sierra Nevada with several feet of snow.

Meteorologists expect the first storm to deliver two rounds of rain starting Monday afternoon and potentially stalling over the Bay Area on Tuesday morning. The National Weather Service has issued a flood watch from 4 p.m. Monday to 4 a.m. Wednesday and a flood advisory is also in effect until 8:45 p.m. Monday for the area west of Santa Rosa.

There’s a 15% chance that excessive rainfall could cause flash flooding in the North Bay and a 5% chance for the rest of the Bay Area.

“Now that the soils are saturated from this weekend’s rain event, we will probably get some flooding on roadway systems,” said Ryan Walbrun, a meteorologist with the weather service’s Bay Area office.

The storm could bring gusts up to 50 mph at higher elevations and along the coast, especially around Marin and the San Francisco peninsula. The weather service’s morning memo suggests the winds will “be more isolated in nature” and “short-lived.”

“It looks like the winds are going to be strongest in [locations like] Ocean Beach in San Francisco along the Great Highway all the way down south through Santa Cruz and Monterey,” Walbrun said. “Those places would be most prone to power outages.”

The next atmospheric river is expected to bring a weaker storm by Thursday and Friday before drier conditions return this weekend.

Forecasters said the North Bay could receive as much as 6 inches of rain by the end of the week, and the rest of the Bay Area could expect up to 4 inches. The highest elevations in Sonoma County and Santa Cruz mountain areas could see up to 10 inches of rain in locations like Venado north of Guerneville.

“The biggest risk right now would probably be in the North Bay in places that are typically pretty flood-prone,” Walbrun said. “The atmospheric river will spend more time over the North Bay, but the system is not nearly as wet or strong as the November event,” which caused record-breaking flooding in parts of Sonoma County.

Will Powers, fire inspector for the city of Santa Rosa, said the city is prepared with sandbags for residents in low-lying areas, but the larger concern is downed trees.

“With the soil saturation that we’ve had, the big worry is with the wind coming in and downed trees,” Powers said. “As of right now, we’re not worried about major flooding, but more nuisance flooding and stuff like that.”

Anyone who lives in a flood-prone area should prepare to take action in case flooding occurs, Walbrun said. The weather service is monitoring several waterways that could reach flood thresholds this week: the Russian River, the Napa River, the San Lorenzo River, the Laguna de Santa Rosa, and Mark West Creek.

“Right now, they aren’t forecast to go into flood stages because I don’t think the rain rates are there,” Walbrun said.

‘A one-two punch of winter weather’

Forecasters say the cold systems will also bring rain and moderate to heavy snow across the Sierra Nevada.

“We’re expecting a one-two punch of winter weather,” said Matthew Chyba, a meteorologist with the weather service’s Reno office. “If you’re traveling to the Tahoe area, Wednesday might be your best bet, or wait until the weekend.”

The highest peaks in the Sierra Nevada could see up to 5 feet of snow by the end of the week. The National Weather Service has issued winter storm warnings for the Sierra Nevada from Shasta County to Tahoe. The warnings vary slightly, but most start Monday at 10 a.m. and last through Wednesday at 10 p.m.

“We are expecting near whiteout conditions, and we are highly discouraging travel during the time of the warning,” said Sara Purdue, a meteorologist at the weather service’s Sacramento office.

After around a month without snow, ski resorts like Palisades Tahoe are ecstatic about the back-to-back storms. Maddy Condon, senior communications specialist at Palisades Tahoe, said nearly 4 feet of snow could fall on the resort west of Lake Tahoe.

“It was a bit like Groundhog Day here in January,” Condon said. “It’s a playground out there. So when fresh snow comes, all the features and everything you can usually ride changes, creating a different experience every time. That’s why it’s always so fun to have dynamic weather come in.”

Forecasters expect a drying-out period this weekend but said there are signals that the second half of February could return to wet weather.

“Towards the end of the month, we could get more storms, which is what we expect in February, especially after a very dry January,” Walbrun said. “We’re at the point where we want to get a little bit of rain here, too.”