California lashed with 9th storm in third week of major winter weather events

The ninth atmospheric river in a three-week series of major winter storms was churning through California on Monday, leaving mountain driving dangerous and the flooding risk high near swollen rivers even as the sun came out in some areas.

Relentless atmospheric rivers have caused flooding, mudslides and brought heavy snow to areas of the state

A car driving through a flooded street splashes water against parked cars.
Motorists drive through a flooded street in San Diego, Calif., on Monday. A three-week series of major winter storms bringing heavy snow and rain to the state saw officials discouraging travel. (Mike Blake/Reuters)

The ninth atmospheric river in a three-week series of major winter storms was churning through California on Monday, leaving mountain driving dangerous and the flooding risk high near swollen rivers even as the sun came out in some areas.

Heavy snow fell across the Sierra Nevada and the National Weather Service discouraged travel. Interstate 80, a key highway from the San Francisco Bay Area to Lake Tahoe ski resorts, reopened with chain requirements after periodic weekend closures because of whiteout conditions.

"If you must travel, be prepared for dangerous travel conditions, significant travel delays and road closures," the weather service office in Sacramento said on Twitter.

The University of California Berkeley Central Sierra Snow Lab tweeted Monday morning that it had recorded 126 centimetres of new snow since Friday.

A back country avalanche warning was issued for the central Sierra, including the greater Tahoe area.

WATCH | Persistent rain leads to mudslides, sinkholes: 

Flash flooding and mudslides continue to threaten Californians

5 months ago
Duration 0:39
With so much precipitation since Dec. 26, the soil in parts of California has been unable to absorb all the excess moisture, leading to mudslides and sinkholes.

San Francisco rainfall surpasses yearly total

A barrage of atmospheric river storms has dumped rain and snow on California since late December, cutting power to thousands, swamping roads, toppling trees, unleashing debris flows and triggering landslides.

Monday's system was relatively weak compared with earlier storms, but flooding and mudslide risks remained because the state was so saturated, forecasters said.

Mostly dry days were in the week's forecast, though some parts of Northern California could see more rain at midweek.

The sun came out Monday in San Francisco, where 51.5 cm of rain has fallen at the city's airport since Oct. 1, when California typically begins recording rainfall for the year. The average for the "water year" is 49.8 cm, "so we've surpassed the yearly total with 8 more months to go," the San Francisco weather service office tweeted.

An aerial image of a river overflowing its banks on to the property near a house.
An aerial view of Carmel River in Carmel Valley where several homes were damaged due to flooding in a region saturated after three weeks of storms. (Daniel Dreifuss/Reuters)

Across the bay in Berkeley, 10 homes were evacuated Monday when a sodden hillside collapsed, sending mud onto properties. No injuries were reported.

Up to five centimetres of rain fell Sunday in the soaked Sacramento Valley, where residents of Wilton and surrounding communities were warned to prepare to leave if the Cosumnes River rose further.

In Monterey County, the swollen Salinas River swamped farmland over the weekend and officials said Monday that it was still rising. To the east, flood warnings were still in effect for Merced County in the agricultural Central Valley, where Gov. Gavin Newsom visited Saturday.

WATCH | Little relief for storm-battered state: 

Rain, flooding won’t end California’s drought

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Duration 3:16
California has been inundated with rain since late December, but the state’s water shortages are not over.

Government response to deadly storms

Newsom on Monday signed an executive order to further bolster the state's emergency storm response and help communities that suffered damage. U.S. President Joe Biden declared a major disaster in the state and ordered federal aid to supplement local recovery efforts.

In Southern California, the sun shone in Los Angeles, but winter storm warnings and advisories were still in place for mountain areas, where many roads remained impassable because of mud and rock slides. Two northbound lanes of Interstate 5 near Castaic in northern L.A. County were closed indefinitely after a hillside collapsed.

Downtown Los Angeles set a rainfall record Saturday with 4.6 centimetres, the weather service said.

At least 20 storm-related deaths have occurred, and a five-year-old boy remained missing after being swept out of his mother's car by floodwaters in San Luis Obispo County.

Forecasters were keeping their eyes on a storm forming in the Pacific to see if it gains enough strength to become the state's 10th atmospheric river of the season.

Either way it is likely to only bring light rain and will be confined mostly to Northern California when it makes landfall Wednesday, state climatologist Dr. Mike Anderson said Monday during a state weather briefing.

WATCH | Meteorologist Johanna Wagstaffe explains atmospheric rivers: 

What is an atmospheric river?

7 months ago
Duration 1:23
It's a term that became more widely known after record-setting flooding hit B.C. in November 2021, but as meteorologist Johanna Wagstaffe explains, atmospheric rivers are not new to the province.