'Bomb cyclone' set to hit West Coast with 8 inches of rain, foot of snow

Northern California and the Pacific Northwest are bracing for what is expected to be a "bomb cyclone," with heavy rain and winds set to pummel the region and potentially cause power outages and flash floods.

The Weather Prediction Center issued excessive rainfall risks lasting through Friday as the strongest atmospheric river — long plumes of moisture stretching far over the Pacific Ocean — that California and the Pacific Northwest has seen this season bears down on the region. The storm system has intensified so quickly that it has been given the bomb cyclone designation.

Areas that could see particularly severe rainfall as the large plume of moisture heads toward land will likely stretch from the south of Portland, Oregon, to the north of the San Francisco area.

In northern California, flood and high wind watches went into effect Tuesday, with up to 8 inches of rain predicted for parts of the San Francisco Bay Area, North Coast and Sacramento Valley.

A winter storm watch was issued for the northern Sierra Nevada above 3,500 feet, where 15 inches of snow was possible over two days. Wind gusts could top 75 mph in mountain areas.

“Numerous flash floods, hazardous travel, power outages and tree damage can be expected as the storm reaches max intensity” on Wednesday, the Weather Prediction Center warned.

Washington could also see strong rainfall, but likely not as bad as Oregon and California. 

Meanwhile, Southern California this week will see dry conditions amid gusty Santa Ana winds that could raise the risk of wildfires in areas where crews are still mopping up a major blaze that destroyed 240 structures. The Mountain Fire, which erupted Nov. 6 in Ventura County northwest of Los Angeles, was about 98% contained on Monday.


A 2021 bomb cyclone trapped this semi in a foot of snow in California (Photo: CALTRANS via AP)