Steady rain doused the Southland Thursday amid strong winds and mandatory evacuation orders in parts of Orange and Riverside counties prompted by fears of shallow mudslides, minor debris flows and flash-flooding in recent wildfire burn areas.
The National Weather Service warned residents of the major burn areas of intense rain and possible flooding that could take place through about 6 p.m.
Driving was also expected to be difficult through the evening rush hour due to occasional downpours throughout Southern California.
The brunt of the storm lashed the area — particularly in Orange County and in southwestern Los Angeles County — from mid to late morning. The downpours prompted the National Weather Service to issue a flash flood warning for the recent 23,000-acre Holy Fire burn area in Orange and Riverside counties at 10 a.m. The warning, however, was allowed to expire at noon as rainfall lightened.
“Light rainfall continues but the threat for debris flows and flash flooding has decreased,” according to a midday statement from the NWS. “Additional showers will again pose the threat for flash flooding or debris flows later this afternoon and evening. Water will continue to flow in the dry creeks and debris is reported on roadways in Trabuco and Temescal canyons.”
Rain was expected to continue off and on throughout the day.
A voluntary evacuation order that had been in place in the Trabuco Creek area of Orange County was upgraded to a mandatory order around mid-morning Thursday. Residents of Rose Canyon, Mystic Oaks and El Cariso remained under a voluntary evacuation order.
“Hard road closures” were in place on Trabuco Canyon Road at Rose Canyon and Robinson Ranch Road, according to the Orange County Sheriff’s Department.
Despite the flood warning being lifted, sheriff’s officials warned that rain was still possible throughout the day, and the evacuation orders and road closures would remain in place until further notice. A flash flood watch will remain in effect for the burn area until 3 a.m. Friday.
“Locally heavy showers will continue with isolated thunderstorms possible,” according to the NWS. “Hourly rainfall rates in stronger showers and isolated thunderstorms could approach one-half to one inch in an hour. This could lead to mudslides and debris flows at recent burn scars.”
Meanwhile, in Malibu, where the recent Woolsey Fire scarred nearly 100,000 acres across two counties, there were reports of rocks falling on some mountain and canyon roads, but there had not been any major reports of mud or debris flows as of mid-afternoon. But forecasters warned that strong showers were still possible.
The Weather Service reported that around 2:30 p.m., a downpour in the Malibu area dropped about one-fifth of an inch of rain in just five minutes.
A flood advisory issued for the area will remain in effect until at least 5:45 p.m. Forecasters warned that flooding is possible in Malibu, Topanga State Park, Point Dume, Malibu Creek State Park, Pacific Palisades and areas along Malibu Canyon and Las Virgenes roads, Kanan Dume Road and Topanga Canyon Road.
The heavy rains created hazardous conditions across the area, prompting several big rigs to jackknife on Southland freeways and leading to a torturous morning commute.
The storm also proved dangerous for people venturing too close to flowing water. Around 10:30 a.m., Los Angeles Fire Department crews used a helicopter to hoist a man out of the Los Angeles River. The 50-year-old man had been clinging to a tree in the river south of Colorado Boulevard in the Atwater Village area. Fire officials said the water in the river was flowing quickly, leaving the man stranded.
A short time later in Anaheim, a man was spotted clinging to debris in a flood-control channel near the 1900 block of West Greenleaf Avenue. A swift-water rescue team was dispatched to the scene and pulled the man to safety.
The storm originating in the Gulf of Alaska began moving across California’s Central Coast Wednesday afternoon and into Ventura County, reaching Los Angeles County in the evening strengthened by moisture from the Eastern Pacific.
The storm generated strong, gusty winds, prompting the NWS to issue a wind advisory on Santa Catalina Island; the San Gabriel and Santa Monica mountains; the Antelope, San Fernando, Santa Clarita, Pomona and San Gabriel valleys; L.A. County Beach cities, metropolitan Los Angeles, including Downtown L.A., and the Hollywood Hills.
In the mountains and the Antelope Valley, the wind was forecast to blow at 20-30 mph, with 50-mph gusts. In the other L.A County areas subject to a wind advisory, winds of 15-30 mph with 40-mph gusts were expected. The advisory, indicating winds or gusts of at least 35 mph, was scheduled to be in effect until midnight.
“Gusty winds will make driving difficult, especially for high profile vehicles,” warned the NWS in a statement.
Ahead of the storm, residents made preparations for possible mud and debris flows in Malibu, while in Orange and Riverside counties, residents near the Holy Fire burn area were urged to evacuate before the rain even began falling. Mandatory evacuation orders were issued late Wednesday afternoon for some areas of Lake Elsinore in Riverside County.
“All Malibu residents are urged to prepare for potential flooding, mudslides, power outages and evacuations,” the city said in a statement Tuesday. But those preparations must not involve removing debris, which contains hazardous materials. No debris removal from burned properties is allowed until inspections by state and county health officials have been completed.
The Los Angeles County fire and sheriff’s departments both deployed additional staffing into the Woolsey Fire burn area in light of the threat of potentially damaging flooding. Officials with both agencies stressed the need for residents to adhere to whatever evacuation orders are issued.
“Evacuation orders should not be taken lightly and are ordered because there is a threat to life and property,” according to a joint statement from the agencies.
Along the coast, a high surf warning is scheduled to be in force until 10 a.m. Friday. The NWS said surf of 10 to 18 feet with sets of up to 20 feet would batter the shore, and a second, larger swell would generate surf of 20-24 feet later Thursday morning through Friday morning. The surf will lower to 10-15 feet Friday afternoon and evening.
In Orange County, where surf of 5-10 feet was pounding the shore Thursday morning, a high surf advisory will be in effect until 10 p.m. Friday, after which the surf will gradually subside, forecasters said.