CNN
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A historically strong bomb cyclone, which produced winds that killed at least two people, is teaming up with a powerful atmospheric river to bring heavy rain, potential flooding, gusty winds and mountain snow across Northern California and the Pacific Northwest — and there may be another system underway down the road.

The combined effects of the weather systems caused a rare, high risk of excessive rainfall, or a level 4 of 4, in 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 is possible across the region. Combined with Wednesday’s rainfall, potentially record-breaking rainfall of 6 inches or more is possible through Thursday.

Mountain snowfall will also continue through Thursday morning in the northern Sierra Nevada and Oregon Cascades, where storms are expected to bring one to six feet of snow.

Residents along California’s Pacific coast filled sandbags Wednesday in preparation for heavier showers and possible flooding. The area was also buffeted by high winds from the bomb cyclone that wreaked havoc across the Pacific Northwest this week, including a 90-mph gust near the coast in Humboldt County.

About a dozen small landslides have already occurred in Northern California in a 24-hour period, including one on Highway 281 Wednesday morning that caused a car crash, according to the Associated Press.

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

“Remember to slow down and drive cautiously 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 fueling 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 in the wake of the first.

This new low-pressure system is expected to move towards the northwest coast on Friday and undergo strengthening. This low is expected to ‘bombard’ or undergo ‘bombogenesis’, which is a pressure drop of 24 millibars in 24 hours.

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

“Another deep surface low is expected to move toward our region offshore early this morning,” the Seattle weather bureau warned. “I want to make it clear to the public that impacts are not expected to be as widespread as at the low point earlier this week (winds will be lighter from the south and precipitation amounts will be lighter),” the office said.

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

Power outages in the state have also improved, although nearly 350,000 customers in Washington are still without power as of late 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 after high winds pushed down fallen trees. One, a woman in her 50s in Lynnwood, north of Seattle, and another – killed while showering in her King County home, according to the Bellevue Fire Department.

Video shows extensive damage to trees, power lines and homes across the state, where police and firefighters have worked to remove tree debris scattered across roadways, on top of cars and a leaking propane tank.

Some utilities are also struggling 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 quickly freed, it took an hour to free the second, according to Puget Sound Fire.

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

On Tuesday night, a tree struck the home of Washington resident Rob Corcoran, and when it did, he told CNN it sounded like a plane landed on his roof.

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

An Amtrak train en route from Vancouver collided with a fallen tree on tracks north of Seattle on Tuesday evening, an Amtrak statement said. There were no injuries among the 48 passengers on board and they were able to complete their journey via alternative transportation. One engineer was hospitalized for evaluation and later released, Amtrak said.

A waterspout was also spotted off the coast of southern Washington on Wednesday afternoon, but did not appear to make landfall, according to the National Weather Service office in Portland.

Although the second storm is currently forecast to be less severe than the first, soils in the northwest are becoming increasingly saturated.

With more rainfall and flooding, the soil will become too saturated and rivers will begin to rise to more dangerous levels. The land’s natural defenses against excessive rainfall will no longer be able to retain excess moisture, which could lead to increased 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.