Heavy rain and snow fell across swaths of California on Tuesday, unleashing a new round of flooding and power outages in areas where successive storms have disrupted life over the past few weeks.
Snow on Tuesday covered portions of Interstate 80 in Northern California and flooding prompted the temporary closure of other roadways, including several in Santa Cruz County and a portion of the Pacific Coast Highway, south of Los Angeles.
By the evening, some communities had recorded an inch or more of rain over the previous 24 hours, and more than 200,000 utility customers statewide were without power, mainly in the San Francisco Bay Area. Millions of residents were under flood advisories or warnings about high winds and winter weather.
The storm system is forecast to bring several inches of rain to parts of Southern California by Wednesday morning, creating the potential for more flooding in areas where soils are already saturated from weeks of precipitation, according to a National Weather Service forecast.
High winds were also expected overnight, along with more downed trees and power lines. And at higher elevations, residents were bracing for several feet of snow and the threat of avalanches, the agency said.
The system was forecast to move across the Southwest and into the Rocky Mountains by early Thursday, though not before causing trouble in several California counties.
On Tuesday night in Northern California, rain showers were falling in a north-south band from Redding down to San Francisco, as forecasters warned of hail, lightning and gusty winds in some areas. The showers were expected to taper overnight.
Earlier on Tuesday in the San Francisco Bay Area, Stanford University canceled final exams because of a widespread power outage, the school’s emergency information center said. One of the main transmission lines that feeds the campus was impacted by the storm.
In Central California, where a flood watch was in effect until 11 p.m. local time on Tuesday, Weather Service meteorologists were keeping an eye on extremely high water levels in rivers, creeks and steams. They said heavy rain below 4,000 feet could cause flooding into Wednesday night.
Officials were also tracking heavy thunderstorms moving across Tulare County, which has been flooded during previous storms this year. Officials had started going door to door there on Sunday to urge residents in portions of that county to evacuate.
As the storm approached earlier in the week, the California Governor’s Office of Emergency Services had said that residents should be prepared to evacuate if needed. It also urged them to have emergency kits ready at home and vehicles full of fuel.
But the system was expected to have less moisture than the recent back-to-back storm systems called atmospheric rivers that brought heavy rain and flooding to Central California, said Ashton Robinson Cook, a meteorologist with the Weather Service’s Storm Prediction Center.
“We don’t think the rain totals will be as extreme,” Mr. Cook said on Monday. “We’re not expecting the impacts to be nearly anything like what we experienced, especially in Central California, last week.”
The state is trying to recover from a series of storms that have brought heavy rain and snow, causing flooding in portions of the state. It is the second snowiest season in the Central Sierras since researchers at the University of California, Berkeley, began keeping records in 1946. This season, 677 inches of snow have fallen there, the researchers said, compared to a record 812 inches in 1952.
In January, an atmospheric river prompted evacuation orders for more than 40,000 Californians and left more than 220,000 utility customers without power. That storm was part of a three-week series of atmospheric rivers that inundated much of the state, damaging infrastructure and setting off flooding.
The severe weather events in California continued into February, when storms brought heavy flooding to Los Angeles County and whiteouts at higher elevations, and into March, when Gov. Gavin Newsom declared a state of emergency in several counties affected by winter storms that dumped as much as 10 feet of snow in parts of Southern California, leaving some tourists and residents stranded for days.
After that storm, yet another atmospheric river hit California. It washed out portions of roadways, prompted evacuations, caused power outages — particularly in the central region — and contributed to at least one death.
Mike Ives, Livia Albeck-Ripka and April Rubin contributed reporting.