A major storm that began moving into Southern California overnight is set to deliver months' worth of rain and powerful winds — the most potent in a slew ofatmospheric river-fueled storms aiming for the region this week.
It's coming hot on the heels of a storm thatkilled at least one personand brought intense flooding to Northern California over the weekend.
The new storm was starting to slam the entire California coast from north to south with rain and wind Tuesday night.
Torrential rain will get underway in Southern California very early Wednesday morning and continue through the evening.
A Level 4 of 4 "high" risk of flooding rain is in place for the region Wednesday, including more than 6 million people in portions of Los Angeles, San Bernardino, Ventura and Santa Barbara counties, according to the Weather Prediction Center.
These high risk flooding events are incredibly significant: High risks are issued on fewer than 4% of days per year on average, but are responsible for more than 80% of all flood-related damage and36% of all flood-related deaths, WPC research shows.
Wednesday's high risk is Southern California's first since February 5, 2024, whendisastrous floodingkilled at least two people and triggered more than 100 mudslides.
"Widespread and significant urban flooding will be likely along with rock/mudslides and debris flows," the National Weather Service in Los Angeles warned early Tuesday morning, noting these threats are not just confined to burned areas.
"THIS IS A VERY DANGEROUS HOLIDAY STORM," the NWS continued. "ANYONE TRAVELING ON CHRISTMAS EVE OR CHRISTMAS DAY WILL NEED TO EXERCISE EXTREME CAUTION."
California Gov. Gavin Newsom mobilized state resources ahead of the holiday week storm, with agencies pre-positioning crews and equipment, the governor's press officesaid.
Rainfall rates could exceed 1 inch per hour at times in the earliest hours of Wednesday morning, especially in the Santa Barbara and Los Angeles county mountains. That's more than enough to trigger dangerous flash flooding and potentially mudslides.
Life-threatening debris flows are possible on recent burn scars, including from January'sEaton and Palisades fires, that could be pounded with those torrential rainfall rates. The scorched ground of these scars repels water instead of absorbing it, quickly turning rain into a surge of floodwater that pulls mud and debris with it.
Los Angeles County on Monday announced evacuation orders and warnings for areas in and around burn scars in the greater Los Angeles area, including the Eaton and Palisades fire zones. The deadly blazes were two of California'smost destructive fires in historyand burned a combined 16,246 structures, according to CalFire.
The orders are for 383 properties that sheriff's deputies are directly reaching out to, including going door-to-door, the county Office of Emergency Management said Monday. These evacuation alerts went into effect at 11 a.m. PT Tuesday morning.
Evacuation warnings were also issued in parts ofVentura County, with an evacuation order for the Ventura Beach RV Resort going into effect at 6 p.m. Tuesday. Evacuation orders go into effect 8 a.m. PT Wednesday for some areas near the Airport Fire burn scar inOrange County. Parts ofSanta Barbara Countyare under evacuation warnings, including some areas within the Lake Fire burn scar.
Strong winds will add to the danger by potentially bringing down trees and power lines. Winds will be most ferocious in the region's mountains, where sustained winds from the south of 30 to 50 mph are possible with gusts to 80 mph.
The holiday danger doesn't end there: Another atmospheric river-fueled storm will follow Thursday and continue into Friday. It's raising a Level 3 of 4 flooding rain risk for more than 15 million people, including many in Wednesday's high risk.
Steve Schklair and his family, who live in a warning area for debris flow and mudslides, recently moved back into their home in Altadena, which they spent almost a year rebuilding following the fires, he told CNN affiliate KCBS.
But the family will not be evacuating because they live in a "lucky spot" and will instead spend Christmas hunkered down at home, Schklair said.
"All the mud flows — and it does flow — (go) around the house and down the street, never comes up here," he told KCBS.
All told, rainfall totals in Southern California through the end of the week could be as much as 4 to 8 inches in coastal and valley locations, while foothills and mountains see 8 to 12 inches.
To put those totals into perspective, a city like Los Angeles could see anywhere from two months' worth of rain to nearly half a year's worth in just a week.
The same abundant moisture set to slam Southern California will also fuel feet of snow farther north in the Sierra Nevada and make travel there difficult or impossible at times.
The heavy snow will be a big change for the region, which has had much less snow than usual to start the season.
Some relief from this nonstop stormy pattern looks to finally arrive for the upcoming weekend.
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