(CNN) - Thousands of people in fire devastated areas of California are under evacuation orders as a series of storms is expected to bring heavy rain, extreme winds and deep snow through the week.
The rain could lead to mudflows and flooding in areas burned by wildfires last year.
A mudslide forced the temporary closure of a section of the Pacific Coast Highway Monday, while some schools will be closed Tuesday in anticipation of heavy rain.
A rough week in store
- Up to 6 inches of rain is likely to fall on the coast and in the valleys and one or more feet of snow will pile up in the mountains.
- A foot of snow is expected in the Southern California mountains with several feet in the Sierras.
- Flash flooding will become a concern, especially in urban areas.
- There is a threat of mudslides and mudflows, especially downhill from burn-scarred areas in all parts of California.
- Winds could gust more than 40 mph across the valleys and could reach more than 60 mph in the mountains.
- Significant travel delays at major airports and on the roadways are likely throughout the week.
- The strongest of the storms will be Wednesday and Thursday.
Residents 'should go now'
Los Angeles County said mandatory evacuation orders have been issued for some properties impacted by the Woolsey Fire.
LA County Sheriff's Department personnel will continue going door-to-door Tuesday morning to notify residents at properties identified as being at high risk for potential mud and debris flow, the county said in a statement.
However it said all properties in the Woolsey Fire burn area were subject to possible evacuations and should take precautions.
A mandatory evacuation order for residents in the Holy Fire burn area was downgraded to a voluntary evacuation Monday evening.
The order covers about 2,600 residents, or 1,035 homes, the Riverside County Fire Department told CNN.
Cal Fire warned that residents in the evacuation zone "should go now." "Rainstorms carry the potential for dangerous debris flows that can send mud, boulders and trees crashing down hillsides," it said in a statement posted to Twitter.
The Santa Barbara County Sheriff's Office issued an evacuation order to areas at risk from debris flow below the Sherpa, Whittier and Thomas fires burn areas starting at 10 a.m. Tuesday.
"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," the sheriff's office said.
The evacuation order affects about 3,600 people, a county spokeswoman told CNN.
Storms have begun impacting California
It rained much of Monday across Southern California, with locations in and around Los Angeles already seeing about one inch of rain.
A mudslide closed a portion of the Pacific Coast Highway between Malibu and Ventura but it reopened late Monday, Caltrans said.
Rainfall into Tuesday will generally be light and scattered before it begins to increase in coverage and intensity later in the morning.
Flash-flood watches are in place for parts of Orange, San Bernardino, Riverside and San Diego counties, with more than an inch of rain expected. Even higher amounts are expected on the south-facing mountain slopes.
One to two inches of rain fell across Southern California from San Bernardino to San Diego on Friday with more rain on the way.
CNN meteorologist Michael Guy says heavier precipitation is expected from Ventura through Los Angeles.
Flash-flood watches remain in effect for more than four million people in Los Angeles and San Bernardino counties where heavy rain and mudslides are still expected, he said. The watches from Orange County south through San Diego County have been canceled with the heavy rain threat diminishing for extreme southern California.
The Ventura County Sheriff's Office said Tuesday's storm is expected to bring heavier rainfall intensity and totals in Ventura County beginning around noon and extending into the evening hours. Residents living in and around the Woolsey, Hill, and Thomas burn areas should be ready for potential storm impacts in those areas, it said.
Malibu public schools will be closed Tuesday due the expected heavy rain, the Santa Monica Malibu Unified School District announced.
The coastal ranges across Central California could get as much as an inch and a half with this first storm.
Light precipitation will move through Northern California overnight Monday into Tuesday.
As if the rain wasn't enough of a concern, Interstate 5 was closed at Tejon Pass -- roughly 70 miles northwest of downtown Los Angeles -- "due to snow, accidents and vehicles stopped," Caltrans said, but the highway later reopened.
The worst of the weather will be Wednesday
The second and third rounds of heavy rain will begin late Tuesday and last through Thursday.
The National Weather Service in Los Angeles is expecting a steady rain with heavier downpours during this period. An additional few inches of rain could fall across the region.
During this time the Sierras will get the most snow, with the heavier snow piling up on Wednesday and moderate snow continuing to fall on Thursday.
The strongest winds across the state will peak on Wednesday and begin to decrease Thursday.
The region will begin to dry out again on Friday. The storm system then moves east into the Central and Eastern United States over the weekend.
The-CNN-Wire ™ & © 2019 Cable News Network, Inc., a Time Warner Company. All rights reserved.