MALIBU (CBSLA) — The first in what is expected to be a series of storms rolled through the Southland Monday, dumping rain across the region and raising fears of mudslides in recent burn areas, while dropping enough snow to close the 5 Freeway through the Grapevine.

The Pacific Coast Highway. Jan. 14, 2018. (Caltrans)

By late afternoon, Caltrans reopened the Pacific Coast Highway from West Broad Beach and Trancas Canyon roads in Malibu after the coastal road had been closed because of mud and debris in lanes.

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Meanwhile, the 5 Freeway through the Grapevine in the Tejon Pass in the Lebec area was slowly reopened after both directions were shut down due to snow and ice, according to California Highway Patrol.

By 4:30 p.m., officers began releasing vehicles that were stuck in the closure zone on northbound Interstate 5 in the Grapevine in six- to seven-vehicle increments, Caltrans reports. Only vehicles that were stuck are being released. Northbound 5 remains closed at Parker Road in Castaic.

Snow on the 5 Freeway in the Grapevine near Lebec, Calif. Jan. 14, 2018. (Caltrans)

Patrol officers began escorting small groups of vehicles that got stuck in the closure on the northbound side out of the area. The freeway, however, remained closed.

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A voluntary evacuation order issued Sunday night for the Holy Fire burn area of Riverside County became a mandatory order Monday morning. The mandatory order applies to residents in Amorose, Alberhill, Glen Ivy A, Glen Ivy B, Glen Eden, Grace, Horsethief A, Laguna A, Maitri, McVicker A, Rice and the Withrow A neighborhoods, according to CAL Fire Riverside. Residents in those areas must leave immediately due to the possibility of dangerous mudslides and debris flows.

Another voluntary evacuation order remained in effect on the Orange County side of the Holy Fire burn area, including Trabuco Creek and Mystic Oaks.

Officials issued an evacuation order for burn areas of the Sherpa, Whittier and Thomas fires in Santa Barbara County beginning Tuesday at 10 a.m.

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County officials issued the following statement, in part:

“Prepare NOW for tomorrow’s evacuation order. Gather family members, pets, and essential items so that you can evacuate no later than 10 a.m. In the event of a significant debris flow, people living adjacent to the evacuation order areas, particularly in Montecito, Summerland and Carpinteria, could become stranded if roads become damaged or impassible. Residents in these adjacent areas should be prepared for this possibility and consider leaving the area during the evacuation.”

A Red Cross shelter will be open at 10 a.m. at Goleta Valley Community Center, located at 5679 Hollister Ave. in Goleta. Those who need assistance evacuating animals can call the Santa Barbara County Animal Services helpline at 805-681-4332.

RELATED: Storm Soaks Southland, Prompts Mudslide Concerns And Evacuation Warnings

A flash flood watch is in effect through midnight Monday for parts of Orange County, Riverside and San Bernardino counties, including the Holy Fire burn area.

The Sepulveda Basin was closed Monday afternoon due to flooding, according to an announcement from the office of City Councilman Paul Krekorian.

Heavy rain fell in Malibu, Thousand Oaks, Agoura Hills and Calabasas Monday morning.

“The threat for flooding in the burn areas, debris flow going to continue throughout your Monday even into tomorrow,” Gersh said.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)