Emergency officials and residents in Southern California foothill communities braced Monday for the first of three back-to-back storms that could trigger mudslides and flash floods in areas scarred by last summer's wildfires.
No damage was reported from showers that increased in intensity overnight, but a large storm later in the day was expected to drop from 3 to 6 inches of rain in Southern California and 8 inches in the San Francisco area. Forecasters also predicted several feet of snow in the Sierra Nevada.
The National Weather Service also issued a wind advisory for gusts up to 35 mph in Northern California and up to 70 mph in the high desert area east of Los Angeles.
In preparation for possible mudslides, crews have handed out 30,000 sandbags and built 10,000 feet of concrete barriers in foothill communities near burn areas, said Bob Spencer, spokesman for the Los Angeles County Department of Public Works.
"So far so good, we've got no problems," he said. "Everything is set up and we're ready to rock and roll."
Several dozen homeowners in deep canyon areas have been warned to leave if the rains arrive as expected, and more widespread evacuations are possible, Spencer said.
Authorities also blocked roadways through Angeles National Forest as a precaution in case of mudslides in areas burned by last summer's massive Station Fire.
Forecasters said storms lasting through at least Friday could drop 20 inches of rain inland and 8 inches along the coast and in the valleys of Southern California.
Wet weather was expected in most of the state this week, with up to 10 inches of rain predicted for the San Francisco Bay area.
"If it progresses as anticipated, at the end, we will probably have to go back 10 years or more to find a system of equal rainfall and intensity," NWS forecaster Bob Benjamin said.
Snow could fall in the Sierra foothills as low as 3,000 feet, boosting a depleted snowpack but making travel hazardous.
The U.S. Coast Guard urged boaters and swimmers to avoid taking to the water over the next several days, as forecasters predicted ocean swells could reach 25 feet.
Boaters were being encouraged to check their mooring and anchor lines to prevent their vessels from coming loose during the storms.
If it is necessary to travel offshore, the Coast Guard said mariners should check their safety equipment and leave their plans with a friend or family member.