Bomb Cyclone Could Bring Damaging Winds, Rain and Blizzards to the West

A powerful storm system with the strength of a hurricane is likely to whip damaging winds through the Northwest, create large ocean waves and usher in a drenching atmospheric river over Northern California this week.

Heavy rain and strong winds will begin moving through the Bay Area Tuesday night as the first major atmospheric river — a band of moisture that flows from the Pacific Ocean — begins a deluge extending into the weekend. The bulk of this week’s rainfall is expected to fall north of San Francisco, where more than a month’s worth of precipitation could fall over the next three to four days.

Marty Ralph, the director of the Center for Western Weather and Water Extremes, said this storm was predicted to produce as much as 20 percent of the rainfall the region would expect in a year. He said this one storm will help get the wet season in Northern California off to a strong start.

Forecasters have issued a rare “high risk” of excessive rainfall on Thursday for parts of northwest California, where more than 16 inches of rain could fall. Over the past decade, some of the deadliest and most destructive floods have occurred in areas that forecasters said were at this level of risk.