Northern California faces possible record rainfall from atmospheric river as another bomb cyclone potentially looms

CNN
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A historically strong bomb cyclone, which unleashed winds that killed at least two people, is working with a powerful atmospheric river to bring heavy rain, potential flooding, gusty winds and mountain snow across northern California and the Pacific Northwest — and another system may be on. the road.

The combined effects of the weather systems triggered a rare, high risk of excessive precipitation, or a level 4 of 4, across northwestern California through Thursday, according to the Weather Prediction Center.

Widespread rainfall of 3 to 5 inches with isolated totals of more than eight inches are possible across the region. Combined with precipitation from Wednesday, a potentially record rainfall of 16 inches or more is possible through Thursday.

Mountain snowfall will also continue across the northern Sierra Nevada and Oregon Cascades through Thursday morning, with storms expected to bring one to two feet of snow.

Residents on California’s Pacific coast filled sandbags Wednesday in preparation for heavier downpours and potential flooding. The area was also hit by strong winds from the bomb cyclone that wreaked havoc in the Pacific Northwest this week, including a 98 mph gust near the Humboldt County coast.

About a dozen small landslides have already struck across Northern California in a 24-hour period, including one on Highway 281 Wednesday morning that caused a vehicle accident, according to Associated Press.

Authorities in the state also struggled to identify flooded roads overnight, Cal Fire warned, in a post on X. These interior roads, also coated with snow, have created slippery conditions that could make driving treacherous.

“Remember to slow down and drive carefully in these dangerous conditions,” Cal Fire said. “Make sure your windshield wiper blades are in good condition, use your headlights for better visibility, and increase the distance between your vehicle and others on the road.”

As the deadly bomb cyclone helping to fuel the atmospheric river moves away from the coast Thursday, the National Weather Service is monitoring another low pressure system that has the potential to strengthen on the heels of the first.

This new low pressure system is expected to move toward the northwest coast on Friday and undergo strengthening. This low is expected to “bomb out” or undergo “bombogenesis”, having dropped in pressure to 24 millibars in 24 hours.

However, forecasters remain skeptical that this storm will bring the same effects as the bomb cyclone moving away from the Pacific Northwest.

“Another deep surface low is expected to track toward our region offshore early in the morning,” the weather service office in Seattle warned. “Would like to reiterate to the public that impacts are not expected to be as widespread as with the low earlier this week (winds will be lighter out of the south and rainfall amounts will be lighter),” the office said.

Conditions are improving in Washington as the first storm moves away from the coast. All blizzard warnings have expired for the Cascades, while the rest of the winter weather warnings expire Thursday morning.

Power outages in the state have also improved, although nearly 350,000 customers in Washington were still without power as of late early Thursday, according to PowerOutage.us.

Even without making landfall, bomb cyclones can be deadly

Although the first storm never made landfall, historic bomb cyclones can still have devastating effects.

At least two people were killed in Washington state by strong winds that pushed down fallen trees. One, a woman in her 50s in Lynnwood, north of Seattle, and another – killed while showering in her King County homeaccording to the Bellevue Fire Department.

Video shows extensive damage to trees, power lines and homes across the state, as police and fire crews worked to remove wood debris scattered across roads, on top of cars and a leaking propane tank.

Some utility crews have also struggled to restore power but have limited access to hard-hit areas due to blocked roads and mudslides.

Southeast of Seattle, two people in Maple Valley were rescued and taken to a nearby hospital after a tree fell on their trailer. While one person was freed quickly, it took firefighters an hour to rescue the other, according to Puget Sound Fire.

The storm was “one of the worst windstorms we’ve had in recent memory,” Issaquah Mayor Mary Lou Pauly said Wednesday. “We’re seeing significant tree damage (and) most of our traffic signals are out.”

A tree crashed into Washington resident Rob Corcoran’s home Tuesday night, and when it did, he told CNN it sounded like a jet plane landing on his roof.

“I didn’t even go outside because I was afraid I might get hit by flying debris,” Corcoran said. “I had no idea it was as bad as it is.”

An Amtrak train headed from Vancouver collided with a fallen tree on tracks north of Seattle Tuesday night, according to a statement from Amtrak. No injuries were reported among the 48 passengers on board and they were able to complete their journeys via alternative transport. An engineer was hospitalized for evaluation and later released, according to Amtrak.

A waterspout was also seen off the coast of southern Washington Wednesday afternoon, according to the National Weather Service’s Portland officebut did not seem to reach land.

While the second storm is currently expected to be less severe than the first, the soil is becoming more saturated in the northwest.

With even more rainfall and flooding, the ground will become too saturated and rivers will begin to rise to more dangerous levels. The country’s natural defenses against excessive rainfall will begin to be unable to hold excess moisture, which could lead to more runoff and flooding in future events.

CNN’s Isaac Yee, Hanna Park, Sara Smart, Andy Rose, Mike Madrigal and Taylor Romine contributed to this report.