In the Bay Area, residents on Sunday assessed damage from the widespread flooding, wind and landslides that submerged roadways and felled trees — leaving at least one dead, a woman found beneath a tree branch in Golden Gate Park, according to officials. A National Weather Service flood advisory was in effect until 9 a.m. Monday for Bay Area shoreline and North Bay interior areas.

The storms showed signs of tapering off in the Bay Area, but not before another round of moderate rain showers was expected to blow through already waterlogged areas Monday.More than 2,000 Pacific Gas and Electric Co. customers around the region were without power Sunday afternoon, according to the company. Most of the outages were in San Francisco, the Peninsula and the South Bay.

As the rain picked up Sunday, officials in San Benito County issued a new evacuation order for a swath of the northern section of the county outside Hollister. Citing “severe flooding,” county officials told everyone on San Felipe Road north of Highway 156 as well as people in the Lovers Lane, Lake Road, Dunneville Estates and Shore Road areas to leave.

Just across the county border in Santa Clara County, officials expanded an evacuation warning there to include the Bloomfield Avenue area south of Gilroy. The county said two levee breaches in San Benito County may cause water to encroach into Santa Clara County.

Coastal rivers continued to see heightened risk of flooding that threatened to swamp more homes and overtake roadways already buckling on sodden earth. In Sonoma County, the banks of the Russian River were swelled to capacity Sunday, with water levels expected to recede slowly throughout the day Monday. In Monterey County, the Salinas River remained below flood stage over the weekend after peaking Friday at 24.6 feet — about 1½ feet above flood stage. The river is expected to rise again this week, but Sunday’s forecast showed it remaining just below minor flood level.

For people heading south, a new landslide toppled onto Highway 1 south of Mill Creek on the Big Sur Coast, Caltrans reported Sunday, as crews continued to address “significant instability” in several locations on the coastal road.

Forecasters warned of strong winds in San Luis Obispo and Santa Barbara counties, where gusts were expected to blow unsecured objects and tree limbs into drivers’ paths.

High tides and flooding kept a portion of Highway 37 in Novato closed Sunday with no estimated time of reopening the section between Highway 101 and Atherton Avenue that was closed after Novato Creek overflowed a levee, according to Caltrans.

A winter storm warning was issued Sunday in the Sierra Nevada until at least 10 p.m. Monday, with the National Weather Service cautioning that driving could be “very difficult to impossible” because of expected heavy snowfall at high elevations. Between 3 and 5 inches of snow was forecast for lower elevations from Yosemite to Tulare counties, with hazardous driving conditions expected to prevail into Monday.

Eastbound traffic on Interstate 80 heading to Tahoe was being turned around at Nyack Road, Caltrans said Sunday night, “due multiple vehicle spinouts over the Donner Summit.” The agency tweeted, “It’s unknown when the highway will reopen.”

Traffic snaked along Interstate 50, which remained open Sunday from South Tahoe to Sacramento, with chains required for a short section south of the Lake Tahoe basin.

Forecasters encouraged motorists heading down from the Sierra to wait until Tuesday at the earliest for safety on mountain roads.

Those returning should expect delays and plan for the worst by traveling with an emergency kit of extra food, water and clothing, weather service meteorologist Hannah Chandler-Cooley said.

Travel conditions in the Sierra, already poor, were likely “to deteriorate rapidly” as heavy snow covered the ridges overnight Sunday, Chandler-Cooley said, adding that the weather service was “highly discouraging mountain travel“ throughout the holiday weekend.

Snowy sheets were expected to blanket areas south of Tahoe throughout Monday, complicating travel for Bay Area drivers heading down. Road conditions could “remain poor for a while” as Caltrans crews clear roadways, Chandler-Cooley said.

East of Tahoe from Truckee to Baxter (Placer County), chains or snow tires were required on all cars over the roughly 40-mile stretch.

Just south of the Caltrans chain control area, at Ikeda’s California Country Market in Auburn, Derek Ikeda was busy Sunday preparing homemade Dutch apple and chicken pot pies for weekend travelers. But he expected fewer than usual, with storms keeping some of his usual holiday weekend customers at home.

But the forecasts did not dissuade all skiers, he said. “They say, ‘We found a gap in the weather, we are going to shoot for it,’” Ikeda said Sunday afternoon. “They keep coming through the rain and the snow.” Heavenly Valley said it was trying to dig out from the heavy snows but tweeted Saturday that conditions were “well beyond operating parameters all day” as it was “hit with another heavy round of high winds and snow” still piling up.

With wet weather and slippery roadways threatening drivers throughout the Bay Area, improvement was not expected until midweek, said National Weather Service meteorologist Colby Goatley. Highway 84 remained closed between Fremont and Sunol because of a landslide, with Caltrans anticipating road repairs to be completed by Monday evening.

The good news, Goatley said, is that the coming days are predicted to bring a reprieve, with improved road conditions by the week’s end.

“Everyone is tired of the rain,” he said, “but after one more round, we should get some sunny skies in the forecast.”

Nora Mishanec and J.D. Morris are San Francisco Chronicle staff writers. Email: nora.mishanec@sfchronicle.com jd.morris@sfchronicle.com