LOS ANGELES (CNS) — Heavy rain pounded Southern California again Tuesday as yet another storm system thundered over the region, causing localized flooding and debris flows that forced closures of roads, freeway lanes and even some schools.

What You Need To Know

  • The powerful storm, which tapered off Tuesday afternoon over Los Angeles, Orange and other Southern California counties
  • It dumped more than 10 inches of rain in some areas overnight, with the bulk falling in Ventura County
  • Mud flows, sliding rocks and fallen tree limbs made driving treacherous on canyon roadways out of the San Fernando Valley
  • With driving rendered difficult to impossible, all schools in the Malibu area were closed for the day, with students reverting to remote learning

The powerful storm, which tapered off Tuesday afternoon over Los Angeles, Orange and other Southern California counties, dumped more than 10 inches of rain in some areas overnight, with the bulk falling in Ventura County.

Roughly 6 inches of rain fell in Porter Ranch and Woodland Hills, while about 5 inches fell in Bel Air and Beverly Hills. Pasadena got 5 inches, Burbank 2.9 inches and downtown Los Angeles got 2.7 inches, according to the National Weather Service.

Mountain areas received far more rain, with Warm Springs recording 8 inches of rain by 4 a.m. More than 7 inches fell in the Sepulveda Canyon. And amounts upward of 18 inches fell over the higher terrain of Ventura and Santa Barbara counties, the NWS reported.

The overnight downpours led to isolated flooding and debris flows, making for a sloppy morning commute and warnings from local authorities for residents to stay off the roads if at all possible.

Mud flows, sliding rocks and fallen tree limbs made driving treacherous on canyon roadways out of the San Fernando Valley, frustrating drivers on critical routes such as Laurel, Coldwater and Benedict canyons. Roads in the Malibu and Topanga areas were also impacted, including a large boulder that fell onto Malibu Canyon Road in the Santa Monica Mountains, forcing a closure. All roads in the Sepulveda Basin area were also closed due to flooding.

Residents in about 12 homes were ordered to shelter in place Tuesday morning due to mud and debris flow along Fredonia Drive at Lankershim Boulevard. The Los Angeles Fire Department said there was no structural damage to the homes.

Remaining road closures as of Tuesday evening were:

  • NB I-5/Templin Highway in northern LA County, two right lanes blocked;
  • SR 27 in Topanga, both directions from PCH to Viewridge Road;
  • SB I-5 to SB 110 Freeway connector, will remain closed overnight;
  • SB I-5 to NB SR 14 truck connector in Newhall, will remain closed until further notice;
  • SR 138, closed in both directions near Llano from Palmdale Road to LA/San Bernardino County line.

With driving rendered difficult to impossible, all schools in the Malibu area were closed for the day, with students reverting to remote learning. Campuses in Santa Monica remained open.

The Los Angeles Unified School District closed Topanga Elementary School for the day due to the storm conditions, with all students and staff moved to Canyon Charter Elementary School in Santa Monica.

The storm also sporadically knocked out power to thousands of residents.

The torrential rain led to flooding in the pedestrian walkway leading to train platforms on the main level of Union Station in downtown Los Angeles on Tuesday morning.

Due to the threat of flooding and debris flows in recent burn areas, Los Angeles County officials issued an evacuation warning Monday for residents in the Lake Hughes and Kings Canyon area. Residents were warned to prepare to evacuate by gathering important materials and being ready to leave quickly.

The city of Duarte issued a yellow alert for residents of roughly 25 homes near the Fish Fire burn area from 4 p.m. Monday through 6 p.m. Tuesday. The alert imposed restrictions on street parking on Mel Canyon Road between Brookridge and Fish Canyon roads, and on Deerlane Road between Mel Canyon and Greenbank Avenue. It was changed to a green alert at 6 p.m. Tuesday and the parking restrictions were lifted.

In San Marino, the Huntington Library, Art Museum, and Botanical Gardens announced that "due to saturated soils, the possibility of winds, and several fallen trees," the gardens will be closed on Wednesday, although the facility's galleries will remain open.

Late Monday night, as rain began pouring over the area, Los Angeles Fire Department and other first responders made a dramatic rescue as they pulled people from a large, water-filled sinkhole in Chatsworth that swallowed at least two vehicles — one on top of the other. There were also muddy debris flows on streets and a quarter-acre landslide on a hill in Hollywood Hills West.

A high surf advisory was in effect until 10 p.m. Wednesday at Orange County coastal areas, and until 10 p.m. Friday at Catalina Island.

Dry weather will return Wednesday and Thursday, but more rain is likely to arrive Friday through next Tuesday, according to the NWS.

In response to the seemingly relentless series of storms, President Joe Biden approved an emergency declaration for the entire state of California on Sunday and authorized the Federal Emergency Management Agency to coordinate disaster relief efforts and provide emergency resources.

Meanwhile, the Los Angeles City Council on Tuesday approved nearly $1 million in funding to repair two areas in the city hit hardest by the recent storm. The council appropriated $500,000 for the sinkhole repair in Chatsworth and $450,000 for repairs to Mulholland Drive.

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Mulholland Drive was temporarily closed between Summit Circle and Bowmont Drive and is in need of an "immediate permanent repair," according to a motion filed by Councilwoman Nithya Raman. The repairs are expected to take three weeks to complete.

The money, subject to approval by the mayor, will come from Measure M funding.

Also Tuesday, the Internal Revenue Service announced that due to the storms and a resulting federal emergency declaration, Southern California residents and business owners will have until May 15 to file federal individual and business tax returns and make tax payments.

The one-month filing grace period is being offered to residents in areas designated by the Federal Emergency Management Agency as qualifying for tax relief due to storms — including individuals and households that reside or have a business in Los Angeles, Orange, Riverside and San Diego counties.

Temperatures will stay cool through the rest of the week, with most highs in the 60s and lows in the 40s, though overnight temperatures will drop into the 30s in the mountains and high desert.

Health officials issued a cold weather alert for Lancaster and Mt. Wilson, where near-freezing or sub-freezing temperatures are expected. The alert will be in effect through Friday in Lancaster, and Wednesday in Mt. Wilson, according to the Los Angeles County Department of Public Health.