Another ‘atmospheric river’ pummeling California threatens more flooding

A powerful "atmospheric river" pummeling California could cause even more flooding and mudslides in regions already waterlogged after weeks of back-to-back storms.

The National Weather Service declared a "high risk" of excessive rainfall across the state, in both coastal and mountainous communities. "Lives and property are in great danger from Tuesday into Wednesday," the agency warned.

Already, major rivers were overflowing in 16 locations across the state, including in central California where a levee on the Pajaro River failed over the weekend. At least 70 flood watches and warnings were in effect across the state.

Meanwhile, the north-east US braced itself against a powerful late winter storm caused power outages and flight delays. Forecasters expect as much as 2ft of snow to fall on Tuesday. North-western Massachusetts has already recorded 28in of snow, and New Hampshire has recorded 11in.

The weather services called the bicoastal storms a "double whammy".

In California, which has endured a slew of storms since December after a long stretch of drought, the precipitation is falling on drenched ground, heightening the threat of flooding. "Given our saturated soils and strong wind gusts, it will not take much to bring down trees today," the Bay Area office of the weather service warned.

The San Francisco Bay region could see 1.5in of rain, as well as strong winds. Coastal regions south of the Bay Area could see 3in to 6in of rain.

Meanwhile, in the Sierra Nevadas, more than 2ft of snow is expected to fall on areas that were already buried during storms last month. In northern California, Lake Tahoe's iconic Emerald Bay completely froze over for the first time since the early 1990s, state park officials said. The lake's only inlet is estimated to be between 150ft and 230ft deep, and a thin, 4in crust of white ice has developed atop its crystalline depths.

Officials have warned tourists against travelling to the area, which is expecting floods and dire road conditions. The US forest service has issued an avalanche warning for the region, as the atmospheric river threatens to bring more rain and snow to communities still digging themselves out of the previous storms.

More frequent, intense storms are expected as the climate crisis deepens, experts warn. Extreme swings between drought, fire, snow and rain could complicate flood risks, and make such threats harder to forecast.

Rain and snow are expected to hit the San Bernardino Mountains, east of Los Angeles, where some remain snowed in after previous snow storms buried communities. At least a dozen people were found dead as rescuers rushed to dig out residents, including the elderly and others who needed access to medical services.

The weather service's designation of "high risk" for flooding is rare, and about 40% of all flood related fatalities and 80% of flood related damages occur in areas that the center has proclaimed as such.

Officials in California's Santa Barbara county also issued evacuation warnings for areas scarred by recent wildfires, as burned soil can repel water and increase the risk of flash flooding. In Monterey county, officials said water from the storms today will likely go over the breached Pajaro River levee on as crews work to prevent the rupture from growing larger. In the surrounding agricultural region, a community of largely Latino farmworkers remain evacuated.

The county also warned that overflows from the Salinas River could innundate roads and nearby farms.

Undersheriff Keith Boyd said first responders have rescued about 170 people who were stranded within the county's evacuation areas since Friday, including a woman and her baby who got stuck trying to drive through high waters.

The undersheriff said 20 to 40 people remained trapped Monday near the Salinas River because the roads were impassible for rescuers.

Winery and agricultural experts from the region said they are concerned about the storms' impact on crops - both ones in the ground that are currently submerged, and ones that should be planted for the upcoming growing season.

Karla Loreto, who works at a Pajaro gas station, said she is worried about the toll the flooding will take on the area's farmworkers.

"The fields are flooded right now," she said on Monday. "Probably no jobs there right now. For this year, probably no strawberries, no blackberries, no blueberries."