Unprecedented

More rain is headed for the Bay Area in the aftermath of 'unprecedented' storm

By Amanda Bartlett

Record-breaking rainfall propelled by a powerful atmospheric river drenched the Bay Area over the weekend, and though more is on the way, forecasters are expecting the upcoming system to pale in comparison to the historic storm. 

All told, over 20 inches of rain soaked the North Bay in the last round, Dylan Flynn, a meteorologist for the National Weather Service’s Bay Area office, said Sunday, calling it the “most impactful rain we’ve seen all year” for that part of the region. Notably, the Santa Rosa Airport recorded 13.91 inches of rain, which is 41% of what that location typically observes in an entire year, according to the weather service. Meanwhile, downtown Santa Rosa received 12.47 inches of rain in a three-day period, marking a thousand-year event, the weather service said on social media. Widespread flash flooding, power outages and road closures impacted the rest of the Bay Area on Friday, which Flynn also described as on par with some of the wettest days recorded so far this year. 

“In some cases, I’d call it unprecedented,” he said. “We haven’t seen this much rain in over 100 years. It was a really, really impressive event.” 

Flynn added that the Russian River near Guerneville went into a flood stage, which in and of itself isn’t uncommon. However, “it’s the earliest we’ve ever seen it flood,” he said. “Typically it happens in February or March after a full season of winter rains. We’ve never seen this happen in November.”

Meteorologists are continuing to keep a close eye on the southward-flowing river, which has receded as of 4 a.m. Sunday with water levels continuing to go down. Flooding likely won’t be as much of a concern when the deep low pressure system that’s been lingering off the coast of the Pacific Northwest for the past week spins up another storm, delivering scattered showers as early as Sunday night, Flynn said. 

Monday and Tuesday are forecast to be the peak of the next storm, which is slated to be “fairly run of the mill” with ponding in roadways and some minor flooding possible in flood-prone areas. Gusty conditions are expected on Monday, with wind speeds reaching up to 30 mph that may result in tree damage and fallen branches. 

The system is also expected to be more spread out than last weekend’s rain: by comparison, downtown San Francisco saw three inches of rain in six hours on Friday, and is now expected to get another inch and a half of rain, but over a two-day period, Flynn said. Most parts of the Bay Area will see about an inch of rain on average, with higher elevation areas seeing as much as two inches of rain, but Flynn pointed out this storm has “really shifted south,” and the Central Coast will likely get the brunt of it as the heavier band of rain moves south of San Francisco. As much as four inches of rain could soak high elevation areas like the Santa Lucia Mountains.

“Our biggest concern is water on the road with Thanksgiving coming up,” Flynn said.

He encouraged people traveling for the holiday to wait until Wednesday or Thursday morning if they’re not going too far — that’s when conditions are likely to clear up. Allow extra time for the commute, don’t use cruise control while driving, and leave plenty of space between cars. For those traveling over the mountains, Flynn warned that the weather service has issued winter storm advisories for the Cascade Range to the north and the Sierras to the east, where as much as seven feet of snow is expected to accumulate. Wind gusts of up to 50 mph are also anticipated.

“Roads, and especially bridges and overpasses, will likely become slick and hazardous,” the weather service said in an urgent message Sunday morning. “Travel could be very difficult to impossible."

A high pressure system is expected to move back in by mid-week, putting an end to the rain and even encouraging the sun to briefly peek out. That said, more showers could make a comeback by Friday and Saturday. 

“It’s going to be nothing like what we went through last week, but people should still be prepared for moderate impacts,” Flynn said.