SAN FRANCISCO (AP) -- A storm moving into California on Thursday brought rain that threatened to unleash debris flows in wildfire burn areas and snow that could cause travel problems in the Sierra Nevada.
A watershed emergency response team worked in the area of Paradise to identify spots that could be prone to flash floods and mudslides. Crews cleared drainage ways and removed burned trees that could topple, said Butte County spokeswoman Callie Lutz.
The town of 27,000 has been under mandatory evacuation orders for nearly three weeks since a wildfire swept through, destroying thousands of homes and killing at least 88 people.
Residents could begin returning early next week, but only if the storm doesn't hinder efforts to clear roads and restore power, said Sheriff Kory Honea.
Up to an inch of rain could fall Thursday in the burn zone about 140 miles (225 kilometers) northeast of San Francisco, said National Weather Service spokeswoman Cindy Matthews.
The weather service issued a watch for possible flash flooding and debris flows from areas scarred by major fires throughout the state.
On the coast near Big Sur, the California Department of Transportation closed a 12-mile (19-kilometer) stretch of Highway 1 because of potential instability.
The scenic route perched between towering mountainsides and the ocean has been dogged by slides since 2016. But the one that hit in May 2017 was monumental, requiring extensive work to rebuild the highway.
In Southern California, residents were urged to voluntarily evacuate a string of neighborhoods about 45 miles (70 kilometers) southeast of Los Angeles along a flank of the Santa Ana Mountains where a fire burned thousands of acres last summer. Mandatory evacuations were ordered for a small section of the city of Lake Elsinore beneath a burn zone.
West of Los Angeles, residents were urged to be prepared for rain in the vast area where the Woolsey Fire burned through nearly a dozen communities this month.
Sandbags were offered in numerous locations in Los Angeles and Ventura counties. The city of Malibu urged residents to look for their locations in an interactive online map created by the U.S. Geological Survey that depicts the likelihood of debris flows given certain amounts of rainfall.
Last January, the Santa Barbara-adjacent community of Montecito was savaged by massive, deadly debris flows when a downpour hit mountains denuded by a devastating fire.