Another round of storms expected to pack a punch for California

SAN DIEGO — Thirty-six million Californians from Sonoma County to the U.S.-Mexico border are under weekend flood watches as the state faces the more potent of two early-February storms.

The front’s rain and snow will be boosted by an atmospheric river, a firehose of precipitation, forecasters say. This atmospheric river is drawing from tropical climes, making it a “Pineapple Express.”

“All Californians in the storm’s path — especially those in Southern California — should prepare now,” Gov. Gavin Newsom said in a statement Friday.

Dangerous flooding across the state was possible through Tuesday, forecasters said, with 6 inches likely and 12 inches of rain or more possible from the lower reaches of the Central Coast to the Los Angeles County coast.

If the upper ends of those estimates are reached, they could break rainfall records for the date and even monthly precipitation records, according to NBC News forecasters.

The National Weather Service on Saturday boosted its warnings for Santa Barbara and Ventura Counties north of L.A., saying there is "a high risk of excessive rainfall," a proclamation issued only a few times a year, Ariel Cohen, the meteorologist-in-charge of the L.A. regional office, said at a Santa Barbara County news conference.

The storm was expected to hit the Bay Area as early as Saturday, then work its way down the coast, affecting San Diego last.

The Bay Area and Central Coast could also be affected by damaging winds and waves higher than 20 feet. The National Weather Service office in Monterey said gusts of nearly 70 mph could whip the Central Coast community of Big Sur.

Flooding possible

The upper-level low pressure system could stall over California once it gets to the coast late Saturday, forecasters say, making its flood potential more perilous.

Officials in Madera County, south of Yosemite National Park, issued an evacuation warning for a community affected by debris flow during heavy rains last year.

Santa Barbara County Sheriff Bill Brown converted Friday night's evacuation warnings for two areas to mandatory evacuations effective early Saturday afternoon. The areas include one affected by brush fires and another within the city of Santa Barbara.

State beaches within the county were closed as a precaution, Brown said at Saturday's news conference. Residents throughout the region should be prepared to get out at a moment’s notice, he said.

"We're anticipating flooding," he said.

Ventura County issued evacuation orders Saturday to an unincorporated region in Ojai. Officials say possible flooding, debris and mud flows could make roads in the area impassable. Evacuation warnings are in effect for four other communities in the county.

Flood watches, issued when conditions are favorable for flooding, will cover the coast in Sonoma, Marin, San Francisco, Monterey and San Luis Obispo counties, and all of Southern California’s coast. Some of the watches start late Saturday afternoon and last at least through the end of the weekend.

The same stretch, including nearly 600 miles of coastal terrain by vehicle, was covered by high wind warnings, watches or advisories, with warnings giving notice of gusts of 58 mph or stronger and watches and warnings giving residents time to batten down the hatches, according to the weather service.

The University of California, San Diego’s Center for Western Weather and Water Extremes predicts the atmospheric river will rate as a 3 — described as “strong” — on its scale of 1-5, which mimics the one used for hurricanes.

It said there’s a 40% chance of flash flooding along the central coast.

Newsom’s office said 8,300 state workers were prepared to respond to storm-related emergencies and damage. Twenty teams of swift-water and urban search-and-rescue personnel were staged up and down the state.

‘When in doubt, stay home’

The forecast for the Los Angeles area included life-threatening flooding, damaging winds and heavy mountain snow, the National Weather Service office in Oxnard said.

“Many roads/freeways will be completely flooded. Many trees will be down. Power outages likely. There is still time to prepare,” the office said in a post on X.

The city of Los Angeles is prepared for serious flooding, Mayor Karen Bass said at a Friday evening news conference. “This is an all-hands-on-deck effort,” she said.

Police, fire and rescue personnel will be on standby, extra emergency and homeless shelters will open Saturday evening, street crews were preparing for rapid clearing of trees and branches, and water and power crews were ready to respond to outages, Bass said.

Perhaps the most impactful preparation was in the hands of residents, she said: “When in doubt, stay home.”

In the central Sierra Nevada mountain range, 2 to 3 inches of snowfall per hour was expected by Sunday, according to the National Weather Service, which issued an avalanche watch.

“Avoid all travel on Sunday,” the weather service office that covers the Lake Tahoe area said.

Another system could hit Southern California on Thursday, National Weather Service senior meteorologist Alex Tardy said in a video briefing Friday.

Classes canceled

Nine school districts in Santa Barbara County have already canceled classes Monday ahead of the severe storm.

School officials made the decision after county Sheriff Bill Brown recommended that all schools in Santa Barbara close on Monday due to the expected safety concerns.

The largest school district in the county, Santa Barbara Unified, will determine the status of Tuesday classes after checking the conditions at each school on Monday.

Other counties in California have no planned school closures.

Wet start to the year

The state has barely had time to dry out, after storms in January and this week brought strong rain and some flooding to Southern California.

The hammering began in earnest Jan. 22 with the wettest January day on record for San Diego, which experienced rare and damaging flooding in urban neighborhoods away from the coastline. The county’s medical examiner reported that three January deaths were being investigated as possibly storm-related.

A front late this week brought 6 to 9 inches of snow to Southern California mountains, federal forecasters said, and it flooded a street in Long Beach, stranding at least four motorists who were rescued, authorities said.

A stretch of Pacific Coast Highway in Huntington Beach was closed by flooding Thursday and reopened Friday morning, according to the California Department of Transportation. To the south, parts of the community of Leucadia in the city of Encinitas were flooded by the first of the two fronts.

Nearly 3 inches of rain fell in some parts of San Diego County, a rare amount for the relatively dry southwestern corner of the state.

San Diego surpassed the normal rainfall amount for this time of year when nearly an inch was recorded Thursday, Tardy said, with most of two of the rainiest months of the year — February and March — still ahead.

This article was originally published on NBCNews.com