A dangerous, intense storm will move into Southern California this weekend, bringing the potential for widespread flooding, mudslides and debris flows.
Officials are urging caution during the most treacherous periods of the storm Sunday and Monday.
The National Weather Service says flooding from the atmospheric river could be “life-threatening.”
“This will probably be categorized as our biggest storm this winter so far,” said Emily Montanez, associate director with the L.A. County Office of Emergency Management. “Take your individual precautions, but also if people are able to telework and get those plans in place so that we’ve got an easier commute Monday morning, that’s what we’re really encouraging.”
Weather officials are expecting 3 to 6 inches of rain across Southern California, particularly in Santa Barbara, Ventura and Los Angeles counties, which are expected to see some of the worst flooding.
“L.A. could see somewhere from a third to half of the average annual precipitation from this single storm coming up,” said Daniel Swain, a climate scientist with UCLA. “It looks like it may rain continuously in L.A. County from around Sunday afternoon to Wednesday morning. … It may not be extremely intense the whole time, but it will be a pretty long-duration rain event.”
In addition to rain, “high surf, large battering waves” could contribute to coastal flooding, according to Ryan Kittell, a National Weather Service meteorologist in Oxnard. And if the pounding waves aren’t enough, “potentially deadly rip currents” should keep everyone out of the water.
The storm’s effects will be felt statewide, with forecasts showing more than 3 inches of rain possible from the Mexico border to the Bay Area from Sunday through Tuesday — well over the average for the entire month in many areas.
Saturday: Rain will begin in the evening in Northern California, primarily along the coastal Bay Area, before heading south.
Sunday: Heavy rainfall is expected to begin in San Luis Obispo and Santa Barbara counties, moving into Ventura and Los Angeles counties by late in the day. Strong bands of sustained rainfall will create widespread flood threats.
Monday: The storm is expected to continue, bringing added danger from sustained rainfall on already saturated ground. The highest risk of flooding will be Sunday night through Monday evening.
The heaviest rain will come in areas east and south of Los Angeles County, with up to 4 inches predicted in the Inland Empire and Orange County, and closer to 2 or 4 in San Diego County, according to Adam Roser, a National Weather Service meteorologist in San Diego.
Tuesday to Wednesday: Lighter rain is in the forecast.
Officials say residents should expect street flooding and mudslides in vulnerable areas.
Some evacuations and road closures are expected.
Thunderstorms and heavy rain bands could bring flash flooding.
The California Governor’s Office of Emergency Services has deployed personnel and resources to many areas in the path of the storm, including more than 550 firefighters and 19 swift-water rescue teams in 19 counties, officials said. Two million sandbags have been pre-positioned across the state.
“As we look ahead to the next few days, we encourage all Californians to take steps now to prepare for incoming weather,” agency spokeswoman Alicia de la Garza said in a video posted on X.
Gov. Gavin Newsom said Friday that “California has more than 8,300 boots on the ground as we prepare for this next set of serious storms.” He cautioned all in the storm’s path — especially those in Southern California — to prepare now and follow the guidance of local government officials and first responders.
Santa Barbara County: Officials are urging residents to stay away from rivers, creeks, flood-prone low-lying areas and wildfire burn scars, which can turn into dangerous mud and debris flows during heavy rains. Beaches, bluffs and harbor areas may see coastal flooding and erosion, and residents and visitors are being advised to stay away.
Los Angeles County: Officials are keeping a close eye on the Palos Verdes peninsula, which saw devastating land movement last summer and a mudslide Thursday, as well as Long Beach and areas along the San Gabriel Mountains, Montanez said.
“We’re always keeping an eye on that area, especially with recent burn scars like in Duarte, with the Fish fire,” Montanez said. “In burn scar areas, within three years post-fire, there’s always a chance for mud and debris flow.”
The county’s Public Works Department is working to clear storm drains and flood control channels in preparation for an influx of water, she said. The agency is expected to issue phased warnings for areas in the path of the storm. That may include potential evacuation notices in Duarte, Azusa, the Santa Clarita Valley and other at-risk areas.
She added that the county is positioning Sheriff’s Department officials in case door-to-door evacuation notices are warranted, as well as fire and emergency response personnel. The county is also readying an outreach team for unhoused populations, she said.
L.A. Mayor Karen Bass urged residents to monitor the storm and be mindful of extreme weather warnings.
“We know the severe impact that weather can have on our communities, and we are making sure Los Angeles is prepared on behalf of our residents, including the unhoused Angelenos living on our streets, to get through this storm,” she said.