The threat of mudslides caused by heavy rain forced thousands of southern California residents to flee their homes on Monday.
Heavy rain brought by a powerful storm could also cause flash floods where a series of intense wildfires burned off vegetation last month.
“Recent burn areas will be especially vulnerable where dangerous mud and debris flows are possible,” the National Weather Service said in a statement.
Heavy downpours that could produce more than 1 inch (2.5 cm) of rain per hour were expected through Tuesday evening, forcing officials to order or advise Ventura, Santa Barbara and Los Angeles county residents who live near where wildfires burned to evacuated their homes.
The storm system was expected to produce 4 inches to 7 inches (10 to 18 cm) in the foothills and mountains with 9 inches (23 cm) in isolated areas. Three inches (7 cm) to two feet (61 cm) of snow was also forecast for higher elevations, the National Weather Service said.
Forecasters issued a flash flood watch for parts for Sonoma and Mendocino counties north of San Francisco.
Robert Lewin, director of the Santa Barbara County Office of Emergency Management, urged residents in parts of Summerland, Carpinteria and Montecito to leave by midday.
"Creeks that normally would be dry would turn into raging rivers of mud and debris and large rocks and trees," Lewin said. "These can be quite damaging. They'll destroy roads, they'll take out homes."
About 30,000 residents were under evacuation orders or advisories on Monday, ABC news reported.
Several December wildfires, included a blaze known as the Thomas Fire, which was the largest in the US state’s history, burned away vegetation that holds the soil in place and baked a waxy layer into the earth that prevents water from sinking deeply into the ground.
The blazes leveled entire neighborhoods, killing 44 people and destroying more than 8,900 homes and other buildings.
“City crews are actively driving around looking for signs of any flooding, mudslides, things of that nature. They are making sure water is flowing, making sure debris clogging storm drains or gutters is cleared up,” said Santa Rosa Assistant Fire Marshal Paul Lowenthal, who encouraged residents near burned areas to have evacuation plans in case they need to flee.
“The fire damaged a significant amount of trees and although a lot of the trees have been cut down and removed, there are still a lot of trees that could be a concern,” he said.
“I’m just tired. I can’t seem to get my life kick-started,” Teri Lebow, whose Montecito, California was damaged by the wildfires, told the Los Angeles Times.