The current bout of heavy showers and gale-force winds swept into the northwestern corner of California late on Friday and spread southward into the San Francisco Bay Area and central coast yesterday afternoon and will linger today, said David Roth a meteorologist from the National Weather Service’s weather prediction centre.
“But, oh no this is not over,” Roth added.
Another of the back-to-back parade of storm systems will hit tomorrow and last through the middle of next week at least, affecting Los Angeles, Sacramento, up through the San Francisco Bay Area and toward Oregon.
“It’s going to get worse tomorrow,” Roth said.
“We’re talking 7.5cm to 15cm of rain, several feet of snow in the mountains … because the area is so saturated we could see flash floods, mudslides, rockslides and avalanches.”
Hillsides and canyons already stripped bare of vegetation by past wildfires are especially vulnerable to rock and mudslides according to forecasters.
In addition to heavy rains, up to 60cm of snow was expected to fall by the end of today in higher elevations of the Sierras, where accumulations of 30cm to 46cm or more were measured earlier this week.
Tens of thousands of homes and businesses have lost power in recent days and more than 34,000 remained without electricity yesterday afternoon, largely in Mendocino County in northern California, according to tracking site Poweroutages.us.
It marked the third and strongest atmospheric river to strike California since early last week.
Howling winds uprooted trees already weakened by prolonged drought and poorly anchored in rain-soaked soil, taking down power lines with them and blocking roadways across the region.
An NWS weather alert yesterday warned that the cumulative effect of successive heavy rain storms since late December could bring rivers to record high levels and cause flooding across much of Central California.
At least six people have died in the severe weather since New Year’s weekend, including a toddler killed by a fallen redwood tree crushing a mobile home in northern California.
The rapid succession of storms left downtown San Francisco drenched in 26cm of rain from Dec 26 through Jan 4, the wettest 10-day stretch recorded there in more than 150 years, since 1871, according to the NWS.
Roth said “This isn’t close to being over,” and that the storm patterns will persist until the middle of January.