A powerful storm system, labeled a "bomb cyclone," is unleashing dangerous weather conditions across the U.S. Pacific Northwest, affecting over seven million residents. The National Oceanic and Atmospheric Administration (NOAA) has warned of heavy rain, snow, and damaging winds through the week, potentially resulting in flash floods, power outages, and hazardous travel.

The storm, already impacting parts of the region, has brought strong wind gusts to Seattle and surrounding areas. NOAA predicts heavy, wet snow in mountain ranges, with accumulation rates of 2–3 inches per hour and wind gusts reaching 65 mph (105 kph). Mountain areas may see total snow accumulations of 10–20 inches, creating whiteout conditions and dangerous travel.

Northern California and southwest Oregon are expected to bear the brunt of the heaviest rainfall, which could trigger flash floods, rockslides, and debris flows. A “high-risk excessive rainfall outlook” has been issued for northwest California.

The National Weather Service has issued winter storm warnings and winter weather alerts for several Pacific Coast areas, warning of hazardous travel conditions, downed trees, and power outages. Coastal regions face the risk of high surf and erosion.

A bomb cyclone is a rapidly intensifying storm characterized by a sharp drop in atmospheric pressure—at least 24 millibars within 24 hours. This rapid intensification leads to explosive weather conditions, including blizzards, thunderstorms, and heavy precipitation.

Helen Rossington, a BBC Weather forecaster, explained that the storm combines the effects of a bomb cyclone and an atmospheric river—narrow corridors of concentrated moisture originating from tropical regions—creating a particularly potent weather event.

While such storms are not uncommon during this time of year, the combination of heavy rain, snow, and flood risks makes this event especially concerning. Residents in affected areas are urged to prepare for potential disruptions and stay updated with local weather alerts.