Northern California Storms Cause Floods, 1 Death, Ahead of This Week’s Potential ‘Bomb Cyclone’

After a weekend of rainfall, the Bay Area is bracing for days of dangerous stormy conditions expected to begin Tuesday night and extend through the rest of the week.

Two wind-fueled systems will hit the region throughout the Christmas holiday week, bringing a possibility of up to 80-mile-per-hour gusts, flood conditions and widespread power outages.

“We really have several waves of potentially strong to moderate showers and thunderstorms, and along with that, we’re going to have very strong winds at the highest peaks,” said Joe Merchant, a meteorologist with the National Weather Service’s Bay Area office.

Showers are expected to continue across the area Monday, adding to the inches of rain that’s fallen sporadically since Friday. Over the last 24 hours, San Francisco has seen more than two inches, while parts of Napa and Sonoma counties have collected almost four.

The first strong storm system is expected to hit Tuesday night, and could meet conditions for a rare bomb cyclone — the meteorological term for a rapidly intensifying storm brought on by a low-pressure system — in the Bay Area.

The rainfall is expected to start in the North Bay, and spread south through the Bay Area through the night, bringing up to 3.5 inches of rain in Sonoma and Napa counties, and up to 1.5 inches to the interior Bay Area and Monterey Bay. The Santa Lucia and Santa Cruz Mountains could also be especially hard hit, with up to three inches of rain predicted in both areas.

Merchant said the system will mean significant flooding risk for much of the Bay, especially as days of rainfall saturate the ground.

Already, the Russian River at Geyserville has reached minor flood conditions, and in Sonoma County, the fire department reported Sunday that it had made its first flood rescue of the season after a driver in Santa Rosa was forced onto the roof of their car amid rising waters.

Further north, Redding experienced major flooding after Sunday’s rainfall. City officials issued warnings to avoid multiple major roadways, and urged people to stay home and avoid driving when possible.

According to Redding Mayor Mike Littau, a person who was stuck as water entered their vehicle died after calling 9-1-1 Sunday night. Littau said the person’s phone died while they were making the emergency call.

A “Redding Police Officer swam out into the water, broke the windows and pulled the victim to shore,” he wrote on Facebook Monday, adding that first responders performed CPR but the person did not survive. Their cause of death is under investigation, according to Littau.

Fire crews near Placer County also had to make a storm-related rescue Sunday, after residents in a home along the South Yuba River were unable to leave due to river swelling. No injuries from that incident have been reported.

Meanwhile, the East Bay is under a flood watch through Monday evening, and water has pooled on streets throughout San Francisco.

The National Weather Service and local fire departments are warning that in the coming days, flood conditions will intensify, potentially forcing evacuations and blocking road access as people likely gear up for Christmas travel. Scott Corn, the assistant chief for CalFire’s Shasta Trinity Unit said people should use caution when they see pooling rainfall, which could be deeper and stronger than expected.

“It’s really important for people to know that six inches of flowing water can knock you off your feet and a foot of that flowing water can float most of our vehicles that we have,” he told KQED. “Two feet of rushing water over a roadway, that’s almost a guarantee that you’re going to get swept off that roadway.”

Along with the threat of flooding, Merchant said the back-to-back storms will also feature intense winds, which could down trees and power lines, likely causing travel delays and power outages.

The strongest winds will blow through the Bay Tuesday night. Gusts along the coast could hit up to 80 miles per hour. Further inland, wind speeds will be around 40 miles per hour, though Merchant said some of the highest peaks in San Francisco could see 70 mile gusts.

As of midday Monday, the National Weather Service has issued a high wind watch for much of Northern California and the Central Coast, meaning sustained, high winds are possible. To prepare, people should secure loose items outdoors and adjust plans in order to avoid getting caught outside.

Merchant said that watch could be upgraded to a warning, depending on how the storm system evolves throughout Monday. During a warning — which means sustained, strong winds with even stronger gusts are happening — the NWS recommends that people seek shelter, and if driving, slow down and keep both hands on the wheel.

Merchant warned people to avoid the coast, where gusts will be strongest and most dangerous, during both Tuesday’s and Wednesday’s wind events.

While the second storm coming through on Christmas Eve likely won’t bring quite as high wind speeds, it will bring a higher possibility of thunderstorms.

With just between a 15 and 25% chance we’ll hear rumbles of thunder or see flashes of lightning, the weather service said the likelihood of “potentially severe” storms is increasing as the forecast becomes clearer. Most likely, any that do occur would be embedded in the main rain bands coming through Wednesday night, though conditions could allow for some thunder.

All together, the conditions could make for a dangerous holiday week, and officials are warning those traveling throughout the area to expect delays and prepare for hazardous conditions.

“It’s going to be tough, these are going to be some really difficult times to be traveling,” said Merchant. “People need to give themselves plenty of time.”

Calfire assistant chief Corn said people should get to know their travel route before embarking, and continue checking for updates on flooding and road conditions.

“Don’t drive into the areas that are flooded … don’t take the chance,” he said. “As a minimum, you may incur damage to your vehicle. At the extreme of this, you may lose your life.”

KQED’s Kevin Stark contributed to this report.