Major storm brings rain, gusty winds, hail and snow

Beneficial moisture will ease, but not eliminate, area’s drought condition

An atmospheric river storm and a rush of cold air bore down on the Bay Area on Sunday, possibly setting the stage for drenching rain, strong winds and hail over the next couple days, and a dumping of powder several feet deep in the Sierra Nevada mountains.

San Jose and the Santa Cruz mountains were expected to encounter the brunt of the storm in the Bay Area, which was forecast to intensify late Sunday into today while providing the area’s first real drenching in about a month. A dusting of snow also was possible over some Bay Area peaks by this morning, including Mt. Tamalpais, Mt. Hamilton and parts of the Santa Cruz mountains.

To the east, the Sierra Nevada mountains were predicted to receive up to 100 inches of snow over the next couple days — a wallop that prompted travel warnings for motorists visiting in the high country.

While no drought buster, the storm promised to act as a salve for parched and quickly drying communities across the Bay Area after a month of dry, arid conditions.

“Overall, there’s a lot to like about this storm — a lot of beneficial rainfall that we desperately need,” Drew Peterson, a National Weather Service meteorologist, said. “But it’s not going to solve all of our multiyear drought woes in a single stroke.”

The weather system’s early hours carried a familiar look to past atmospheric river storms, soaking the North Bay with 1-3 inches of rain by 2:30 p.m. Sunday while sparing most of the rest of the Bay Area with less than a tenth of an inch, according to the National Weather Service.

But the South Bay appeared to be in the storm’s crosshairs heading into Sunday evening.

Most of the rain was forecast to fall on the Santa Cruz mountains, which could receive 6-8 inches of rain by Tuesday morning. About 2-3 inches of

rain were expected to fall in San Jose, San Francisco and Oakland, said Jeff Lorber, a National Weather Service meteorologist.

If the forecast holds, it would flip the script of typical atmospheric river storms, which normally soak the North Bay while sparing the South Bay. But much depended on whether a “rain shadow” cast by the Santa Cruz mountains would leave San Jose with less precipitation.

“San Jose will be in that path of the heavier rain bands,” Lorber said. “So it’s going to be a balance between that and the ‘rain shadow’ effect being on the eastern side of the slopes that normally see less rainfall.”

It’s all part of a multipronged system that could include rain, lightning, damaging winds and even “copious” amounts of small hail — particularly as a storm system moving from the Gulf of Alaska to California reorganizes over the Bay Area on Sunday night in a process known as “frontogenesis.”

“That’s going to be like giving it steroids, essentially,” Peterson said.

A rush of cold air overnight Sunday also was expected to bring with it the chance for pea-sized hail and lightning late this morning through the evening.

The National Weather Service issued a wind advisory for the San Francisco Peninsula, East Bay, South Bay and Santa Cruz County from 4 p.m. Sunday until 10 a.m. today. Winds could gust up to 50 or 60 mph near Fremont Peak and other high peaks in the Bay Area, Peterson said. In San Jose, forecasts are calling for sustained winds of 10-20 mph, with gusts of up to 40 mph, he said.

Mudslides and debris flows are possible across the CZU Lightning Complex burn scar in the Santa Cruz mountains.

Ahead of the storm, utility provider PG&E said the volatile weather system has the potential to cause power outages due to significant rain, gusty winds and heavy snow in the mountains. City services across the Bay Area are also offering sandbags to residents in affected areas.

While the Bay Area girded for rain and high winds, the Sierra Nevada mountains were on tap for what could be their most potent storm in nearly three years, said Anna Wanless, another National Weather Service meteorologist.

Five to 6 feet of snow could fall around Donner Pass and Lassen Volcano National Park by late Tuesday. And 7 to 8 feet could fall on Carson, Ebbetts and Sonora passes. A second storm is expected to dump another 2 to 3 feet of snow on those areas Wednesday and Thursday.

Chain controls were in effect for Interstate 80 over Donner Pass and for Highway 50 near Lake Tahoe as snow began blanketing the region. Caltrans officials pleaded with motorists to hunker down and stay off the roads.

“My biggest piece of advice would be to stay home or stay out of it if you can,” said Haleigh Pike, a Caltrans spokeswoman. “But if you have travel in it, just make sure you’re that you’re preparing.”

The storm came as a welcome salve for parts of the Bay Area that had dried out since twin atmospheric rivers in October and early November.

For example, before the storm, San Jose had received only 2.42 inches of rain since October. Normally, it has 2.64 inches by this time.

This week’s storm — as well as a smaller, less powerful system moving through the area midweek — carried the potential to leave the city well ahead of its seasonal averages, meteorologists said.

“If we get another really wet storm system, we’re going to be looking pretty good for the water year,” Peterson said. “So far this year, we’re looking much better than the last two years.”