The first major storm system of the new year lashed the Bay Area with heavy rain at times and gusty winds Monday, leading to toppled trees and numerous wrecks.
The latest wet weather system triggered a flash flood watch in the North Bay regions scorched by the October wildfires and also prompted a wind advisory for every Bay Area county excluding Solano County, according to the National Weather Service.
The flash flood watch in Marin, Napa and Sonoma counties went into effect at noon Monday and is slated to expire at 6 a.m. Tuesday, according to the NWS. Deluges of rain could trigger debris flows, mudslides and flash flooding, especially in the areas surrounding wildfire burn scars.
The October 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.
The wind advisory, also in effect from noon Monday to 6 a.m. Tuesday, was issued because sustained winds could settle between 20 to 30 mph while gusts could reach 40 to 50 mph, according to the NWS. Officials warn that the blustery conditions can topple trees and power lines as well as make driving difficult in some areas.
Once the wet weather passes through by early Wednesday, rainfall totals could hover anywhere from about 1 inch to more than 3 inches in some Bay Area spots.
Areas in the Santa Cruz Mountains are forecasted to collect more than 3 inches of rain, Santa Rosa and Napa could accumulate anywhere from 1.5 to about 2 inches, and San Francisco is slated to receive roughly 2 inches, according to forecasters. Oakland and San Jose are expected to collect anywhere from 1.5 to 2 inches of rainfall.
In the North Bay burn areas under flash flood watches, crews have lined neighborhoods with straw wattles in the hopes of collecting any excess debris left over from the fires and preventing toxic material from running off into streams, creeks and rivers.
Major Vince Lee with the Army Corps of Engineers said contractors are being advised not to remove the foundation or a wall from a home during the storm because it might loosen the soil below, causing a slide.
"The contractors are out there ensuring certain pieces are not taken out," Lee said. "Certain key concrete pieces or structural pieces that might cause erosion, that those are maintained in place to prevent erosion."
As for what could cause a potential mudslide in the scorched areas, Lowenthal said rain rates in the range of a half an inch to an inch of rain per hour are cause for concern.
"That's where we start really having to focus our efforts on watching our hillsides and encouraging our residents that [if] they do see anything, whether it's a mudslide, debris flows, or any significant flooding, to please call 911," he said.
Aside from the North Bay, concern is also high in parts of San Jose ravaged by flooding last winter.
The South Bay city is handing out free sand bags to help in the fight against potential flooding in low-lying areas, such as those neighborhoods along Coyote Creek that were overwhelmed by high water less than one year ago.
Resident Jim Sarge, who spent time Monday trying to clear a storm drain, says he could have saved hundreds of thousands of dollars in rebuilding if he had a tool as simple as a sand bag to push back against rising water.
"Last time we couldn't get sand bags in because the street had already flooded before anyone had enough time to get the bags here," he said.
In downtown San Jose, a large tree came crashing down near the Guadalupe River Trail, and there were similar incidents caused by the wind and rain on parts of the Los Gatos Creek Trail.
Accidents on Highway 17 snarled traffic during the morning rush hour, and the roads through the Santa Cruz Mountains were expected to remain slick and hazardous through the Monday evening commute.
The CHP said there were 26 accidents on the busy highway.
On the Peninsula, wet roads and gusty winds may have been the cause of a deadly solo crash in Palo Alto, where a car drifted off Page Mill Road and slammed into a tree.
The CHP said an overturned pickup on Interstate 280 in Belmont early Monday likely was caused by driving too fast in the rain.
The weather service also issued a winter weather advisory for portions of the Sierra Nevada above 7,000 feet, forecasting about 4 to 7 inches of snow and up to 1 to 2 feet on higher peaks Tuesday. It said travelers should prepare for difficult travel conditions, including gusty winds, low visibility and slick and snow-covered roads.
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The Associated Press contributed to this report.