A potent storm is expected to deliver significant precipitation across California on Wednesday and Thursday, soaking coastal areas and bringing up to an inch and a half of rain to urban areas including San Francisco and Los Angeles. Several feet of snow is forecast to fall in the Sierra Nevada and cause travel delays.
There is a heightened risk for urban flooding and landslides, including debris flows in areas of Los Angeles that were burned by wildfires earlier this year. A series of evacuation warnings and orders were in effect on Wednesday in areas that had been affected by the Palisades and Eaton fires, and others, including in parts of Malibu, Pacific Palisades and Sierra Madre.The county posted a map with the evacuations.
(An evacuation warning means there’s impending danger and residents should prepare to leave, while an order means there’s an immediate threat and residents should leave immediately.)
“As we know, rain is forecast for the next few days, which mean our fire impacted communities need to be on alert,” Los Angeles County Supervisor Kathryn Barger said at a Wednesday morning news conference. “The risk of mudflow and landslides is real.”
A big snow dump is expected in the Sierra.
The storm is also expected to bring heavy rain to Northern California and significant snow to some of the state’s mountain regions.
“This is a widespread system that’s going to affect much of the state, which has not been the case with many storms this year,” said Brian Hurley, a meteorologist with the Weather Prediction Center.
The storm is poised to unleash moisture, whether rain or snow, as it moves up and over mountains near the coast. The California Coastal Ranges, stretching between Del Norte and Humboldt Counties to the north and Santa Barbara County to the south, are forecast to receive up to four inches of precipitation. Mountains around Los Angeles County are expected to see similar amounts.
This storm is predicted to be a big snow maker for the Sierra Nevada, with up to four feet of snow possible on Donner Summit, which many people drive over on Highway 80 as they travel between the Sacramento Valley and the Tahoe Basin. To the south in Yosemite National Park, the highest elevations could receive up to three feet of snow and the valley close to one foot.
“This is definitely a colder system than we’re accustomed to in March, not too unusual but colder than we’ve seen in a while for March,” said Brian Ochs, a meteorologist with the Weather Service office in Hanford, Calif.
Snow could fall at elevations as low as 3,000 to 4,000 feet on Wednesday, and could even get down to 2,500 feet on Thursday, Mr. Hurley said. In the San Francisco Bay Area, Mount Diablo in the East Bay and Mount Hamilton in the South Bay are expected to receive dustings.
The storm is likely to be the state’s last big shot at significant amounts of rain and snow before the end of winter, when the state receives most of its annual precipitation.
“In the last couple of years, we’ve had storms in April, but they tend to be less frequent,” said Mr. Hurley.
The snowpack in the Sierra Nevada, a crucial water source for the state, was 81 percent of the historic average as of Tuesday, and any storms that arrive in March could help offset the deficit. While the northern Sierra has received an onslaught of storms that built up a big snowpack, the southern half has seen much less precipitation.
The storm is expected to whip up winds across the state and forecasters warned of downed trees, power outages and delays at airports.