Rainy week on tap for the Bay Area; Sierra snow to complicate holiday mountain travel

A one-two punch of storm systems is expected to drape the Bay Area in rainy weather for much of the upcoming week while potentially making holiday travel in the Sierra Nevada mountains “very challenging to impossible,” meteorologists say.

Sunny skies should give way to rain across the Bay Area on Monday evening as the first of two systems from the Gulf of Alaska move into the region. The storm is expected to kick off a week of soggy weather that could drop two or three inches of rain on the Bay Area’s three largest cities while further soaking the Santa Cruz mountains, National Weather Service meteorologist Brooke Bingaman said.

“It’s going to be a wet Christmas week, and through the holiday weekend,” she said.

To the east, the storms are expected to dump several feet of snow over the Sierra Nevada mountains over the next week, making travel for “very challenging to impossible at times” through the holiday weekend, Zach Tolby, a National Weather Service meteorologist, said.

Several feet of snow — including possibly five to eight feet along the highest reaches of the Sierra — are forecast to hit beginning Tuesday afternoon or Wednesday, and continue through Dec. 26, said Anna Wanless, another National Weather Service meteorologist.

“We know a lot of people are going to be on the roads, and we just want them to be aware that it’s going to be a difficult holiday travel situation,” Wanless said.

In the Bay Area, the highest rainfall totals through Dec. 26 are forecast to be concentrated along the Santa Cruz mountains and Big Sur, which could get 5 to 7 inches of rain, Bingaman said. The Sonoma County coastal mountains also could get 7-8 inches of rain.

More low-lying areas should expect less precipitation. San Jose is forecast to get 1.75 inches of rain over the next week, while Oakland and San Francisco could see 2 to 3 inches of rain, Bingaman said.

In a change from the recent atmospheric river deluges to hit the Bay Area, the upcoming systems are expected to bring slow, steady rain, meaning a potentially lower risk of flooding or dangerous runoff over burn scars, she said.

By Friday, snow levels may drop to 3,000 feet, carrying the outside potential that areas such as Mt. Hamilton or Mt. Diablo may see another dusting of snow in time for Christmas Eve, Bingaman said.

The upcoming storms come as much of the Bay Area and California remain mired in extreme and exceptional drought, despite multiple atmospheric river storms in recent months. And while there are encouraging signs of relief lately, experts say far more precipitation is needed over the next few months to make a dent in the state’s longstanding drought.

The most recent storm last week raised California’s statewide snowpack from 19 percent of average on Dec. 10 to 98% as of Friday, according to the National Weather Service’s California Nevada River Forecast Center.

Since the start of October, 4.85 inches of rain has fallen at the San Jose International Airport. That’s 153% of normal for that time period, Bingaman said.