Beyond wind, rain and snow, the storm could also bring flash flooding, rock slides and debris flows as well as heavy mountain snow and blizzard conditions in areas of high elevation. The "bomb cyclone" - as forecasters call it - is caused by air pressure quickly dropping off the coast, which has rapidly intensified the weather system.

Northern California and the Pacific Northwest residents on Tuesday were bracing for the strongest atmospheric river storm system, bringing a lot of rain to some areas and creating the potential for a “bomb cyclone” that can intensify wind overnight.

A powerful winter storm brewing near the Pacific Northwest known as a bomb cyclone is dragging an atmospheric river.

Higher elevation communities in the North Bay will likely see the most rain. Up to 10 inches could fall at higher elevation between now and Friday, according to the National Weather Service. As that water makes its way down the mountains, creeks and streams may break their banks.

The point of impact for the "atmospheric river" over the Pacific Ocean has moved southward, meaning inland flooding concerns for Oregon have decreased over the past day.

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

A powerful storm is bearing down on the West Coast and bringing with it a scary-sounding weather term. That term is bomb cyclone.

Starting Tuesday, the Pacific Northwest could get at least 6 inches of rain, with 20-plus inches possible in the mountains. Strong winds could cause power outages.