### Devastating Bomb Cyclone and Atmospheric River to Drench Pacific Northwest

A massive storm system is set to bring unprecedented weather conditions to the Pacific Northwest and Northern California this week. Dubbed a “bomb cyclone,” this system will combine with an atmospheric river to deliver an extraordinary deluge, packing over a month's worth of rainfall, hurricane-force winds, and feet of mountain snow.

Expected to rapidly intensify on Tuesday through a process called "bombogenesis," this storm is anticipated to reach a rare "triple-bomb" status, according to the National Weather Service (NWS) in San Francisco. Bomb cyclones typically result in heavy snowfall and severe winds, but this one could be among the most intense ever recorded in the region, occurring roughly "once every ten years," as per the NWS in Medford, Oregon. The conditions are expected to conjure perilous mountainous seas reaching 30 to 35 feet.

This bomb cyclone will synergize with an atmospheric river, a vast corridor of water vapor in the sky, to unleash heavy rains and significant snowfall starting Tuesday. The storm front is predicted to linger along the coast, inflicting hazardous weather throughout the week and into the weekend.

Northwestern California could see rainfall amounts soar to 16 inches or more over a 48-hour period. In the northern San Francisco Bay area, north of the Golden Gate Bridge, more than a month’s worth of rain is anticipated, heightening risks of urban and river flooding and debris flows. The Weather Prediction Center (WPC) has issued a level 2 of 4 flooding rainfall threat for parts of northwestern California and southwestern Oregon, expecting 2 to 5 inches of rain.

The heaviest precipitation is set to begin Wednesday, peaking on Thursday in northwestern California. A level 3 of 4 flooding risk is projected for Wednesday, with a rare level 4 of 4 high risk on Thursday, highlighting the severity. High-risk days, seldom occurring, account for over 80% of flood-related damage and 40% of flood-related fatalities, according to WPC research.

Rainfall rates on Wednesday could range from 3 to 6 inches, with some areas potentially getting up to 8 inches. Thursday’s rainfall may be even more substantial, especially in high-risk zones. Mountain regions are bracing for heavy snowfall, with blizzard warnings in effect for parts of the Washington Cascades, where snowfall could exceed a foot and winds could gust up to 60 mph.

Travel will become extremely challenging or impossible, with possible extensive damage to trees and power lines, warned the NWS office in Seattle. Snow accumulations of 1 to 4 feet are expected from Tuesday through Wednesday in the Cascades and northern Sierra Nevada, severely impacting travel on key highways including Interstate 5 and Highways 31, 36, 66, 89, 97, and 140.

The storm will also bring powerful winds, anticipated to escalate on Tuesday and peak by Tuesday night. Coastal areas could experience hurricane-force winds, with widespread inland gusts ranging from 35 to 50 mph, potentially reaching up to 85 mph in higher elevations and exposed regions. These conditions are likely to cause significant power outages, structural damage, and hazardous travel.

Though conditions are expected to improve by the weekend, lighter rain could persist into the following week, prolonging the region's ordeal.