mud flow block highway
© California Dept. of Transportation
Mud flows obstructed parts of the Pacific Coast Highway (above) near Malibu on Monday
Residents of hundreds of homes in three California counties have been ordered to to pack up and leave as a Pacific storm threatens potential mudslide catastrophe.

Mandatory evacuation orders went into effect on Tuesday at 8am in parts of Los Angeles County and 10am in parts of Santa Barbara County that were devastated by the Woolsey Fire.

In Riverside County, mandatory evacuation orders for dozens of areas around the Holy Fire were downgraded to voluntary early on Tuesday, but authorities urged people to stay alert because of continuing rain forecasts.

It come a year after a mudslide swept through a fire-devastated California town, killing 23 people.

After a devastating fire that burned and destabilized foothills, Montecito was hit by a powerful storm on January 9, 2018, that sent water, mud and boulders sluicing down creeks and canyons. Twenty-three people died and over 100 homes were destroyed.

Residents of the plush neighborhood of Montecito were suffering 'evacuation fatigue' from last month's deadly wildfires when they chose to ignore orders to leave their homes as deadly mudslides threatened them, officials said.
mud flow predictions california
© USGS
The map above displays estimates of the likelihood of debris flow (in %), potential volume of debris flow (in m3), and combined relative debris flow hazard
On Tuesday in Santa Barbara County on the central coast, evacuation orders were set to take effect for areas hit by the Sherpa, Whittier and Thomas fires.

'Gather family members, pets, and essential items,' a county statement said. A debris flow could also make roads impassable and strand people near the evacuation areas, especially in Montecito, Summerland and Carpinteria, the county warned.

Weather forecasters have predicted a series of storms that could continue to bring rain and snow into the middle of the week.
storms california mud slides
© The Weather Channel
A line of storms is seen approaching Los Angeles and Santa Barbara on Tuesday morning
Flash flood watches were issued by the National Weather Service for burn areas in Los Angeles, Ventura and Santa Barbara counties, which could see as much as an inch of rain per hour from Tuesday afternoon into the evening.

All schools in Malibu were closed Tuesday.

Flooding and debris flows were a threat to hundreds of homes in areas below foothills and canyons that were swept by flames in recent years.

A mudslide closed a 4.4-mile section of section of Pacific Coast Highway just north of Malibu on Monday for several hours. Los Angeles County authorities issued evacuation orders beginning Tuesday morning for some areas of the Woolsey Fire. The blaze that broke out in November destroyed more than 1,500 homes and other buildings from Ventura County to Malibu and killed four people.

On Monday, the first in the series of storms dumped an inch of rain in Los Angeles and snow in the mountains.

Rain closed the Knott's Berry Farm and Six Flags Magic Mountain amusement parks.
sinkhole malibu
© California Dept. of Transportation
In San Diego County, a 20-foot-long, 20-foot-deep sinkhole on an Interstate 805 off-ramp near Serra Mesa.

In Encino, in the San Fernando Valley of Los Angeles, a guest house was pushed off its foundation by a 250-foot-long debris flow from a hillside. No one was hurt but the Fire Department said up to a dozen other homes were in the slide zone.

Ice and blowing snow shut down the Grapevine, a high pass on Interstate 5, a major route connecting Los Angeles with San Francisco. Dozens of cars and trucks were stranded before the road reopened after nightfall.

Demetrius Moore, a 35-year-old producer for a court TV show in Chicago, was in California for a warm-weather winter vacation. Instead, he found himself huddling in his rental car in the mountain town of Gorman.

'I have just over a quarter of a tank,' Moore said from his car, where he had been sitting waiting for traffic to clear for more than an hour.

'I'm growing concerned. I have water and a little bit of a latte left, no food. I'm just kind of hanging out, hoping for the best and wondering if I'll get out.'