National Weather Service satellite images show a dramatic, churning cyclone approaching California's coast as parts of Northern California get battered by the atmospheric river.
The ferocious storm could be called a winter hurricane, bringing a slew of dangers. While the bomb cyclone moves away, prolonged heavy rain from an atmospheric river will get more than a foot of rain to Northern California and southwest Oregon through Friday, likely causing dangerous flash flooding, rock slides, and debris flow, the weather service said.
The California Department of Transportation closed Interstate 5 on the California-Oregon border as blizzard conditions slammed parts of Northern California.
The Northern Sacramento Valley, including Redding, was expected to get 8 to 10 inches of rain Tuesday through Saturday, according to the National Weather Service, with both rain and snow expected to fall, according to the weather service.
Power outages have been reported in both Shasta and Siskiyou counties.
The Mount Shasta Avalanche Center issued an avalanche warning for the Mt. Shasta area, effective through Thursday at noon.
While Mount Shasta city will get about a foot of snow, snowpack on the mountain could quickly rise by several feet, according to the forecast.
"Excessive amounts of rain and snowfall will give rise to dangerous avalanche conditions in mountainous terrain," increasing chances of natural and human-caused avalanches, Once they start, avalanches may move for long distances "into lower angle terrain," Sam Clairmont at the avalanche center said in a public statement, issued Tuesday morning.'
Related: What is a 'bomb cyclone,' the severe weather event predicted for Northern California
People should avoid slopes steeper than 30 degrees, Clairmont said, adding a cautionary finger wag at winter recreationists. This isn't the time to grab your skis for an early-season trip. Winter sports fans should "recognize when conditions are particularly dangerous" and avoid them, he said.
Early-season avalanches can be especially "nasty" because they tumble ground-level rocks and other debris, according to the avalanche center. Even a tiny slide can knock a person over, and that debris makes it more likely that person could get hurt.
For updates on avalanches at Mt. Shasta, visit the avalanche center's website at shastaavalanche.org.
According to Weather.com meteorologist Chris Dolce, the storm easily met the criteria for bombogenesis. "That means its pressure dropped by 24 or more millibars in 24 hours or less," he said in an online report. "This storm more than doubled that criteria."
In addition, Dolce reported that its estimated pressure dropped as low as 942 millibars, according to 10 p.m. EST analysis from NOAA's Weather Prediction Center. "That's pretty much on par with an October 2021 storm (942.5 millibars) for the lowest pressure in about 50 years of records for the northeast Pacific region."
USA TODAY and the Redding Record Searchlight contributed to this report.