By Rich McKay
(Reuters) - Yet another "atmospheric river" of dense, moist tropical air will clobber California on Monday with rain and mountain snow - the fifth of the weather phenomenon since Christmas - even as the state was being pummeled by storms this weekend, forecasters said.
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 centralcoast on Saturday afternoon and will linger on Sunday, said David Roth a meteorologist from the National Weather Service's Weather Prediction Center.
"But, oh no this is not over," Roth added.
Another in the back-to-back parade of storm systems will hit on Monday 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 Monday," Roth said, "We're talking 3-to-6 inches (7.5 cm-15 cm) 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 mudslidesaccording to forecasters.
In addition to heavy rains, up to 2 feet (60 cm) of snow wasexpected to fall by the end of Sunday in higher elevations of the Sierras, where accumulations of a foot to 18 inches (30 cm to 46 cm) 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 on Saturday 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 prolongeddrought and poorly anchored in rain-soaked soil, taking downpower lines with them and blocking roadways across the region.
An NWS weather alert on Saturday 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 sinceNew Year's weekend, including a toddler killed by a fallenredwood tree crushing a mobile home in northern California.
The rapid succession of storms left downtown San Franciscodrenched in 10.3 inches (26 cm) of rain from Dec. 26 throughJan. 4, the wettest 10-day stretch recorded there in more than150 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.
(Reporting by Rich McKay in Atlanta; Editing by Sandra Maler)