A powerful bomb cyclone fueled by a Category 5 atmospheric river is expected to explode across the West Coast of the U.S. this week, threatening to unleash hurricane-force winds, catastrophic flooding, and massive snowfall in the mountains.
The intense mid-latitude storm is expected to hit Tuesday through Thursday, potentially affecting millions of Americans from Washington State down to Oregon and Northern California.
Some areas along the California coast could see level 4 impacts, which is in the “extreme” category.
As reported by Newsweek, up to 21 inches of rainfall is expected in parts of Northern California this week, following a round of heavy rain and snow that arrived last week affecting the Pacific Northwest. River and flash flooding is likely in these areas.
“This intense storm system is expected to bring major impacts to areas of the Northwest and northern California with heavy rain, strong winds, and big swells,” reported Weather Nation TV.
“The storm system will have potential to more than double that pressure drop, with forecast models showing a drop of 50-60 mb (millibars) in less than a day, starting at over 1,000 mb Monday night, possibly dropping below 950 mb by Tuesday night.”
Meteorologist Ryan Maue, former chief scientist at the National Oceanic and Atmospheric Administration, advised on X, formerly Twitter, on Sunday, that central pressure will fall almost 70 mb in 24 hours reaching 942 mb, similar to a Category 4 hurricane.
The Category 5 atmospheric river—a designation reserved for the most extreme rain events—will funnel vast amounts of water vapor into the region, which could trigger widespread flooding and landslides.
Atmospheric rivers are narrow channels in the atmosphere that can carry a large amount of moisture with them. They form when cold air from the Arctic meets warm, moist air from the tropics, cooling it to form heavy precipitation.
A so-called “bomb cyclone” is when a cold mass of air collides with a warm mass, intensifying a cyclone, bringing more violent winds and a greater likelihood of coastal flooding.
Bombogenesis, or “bomb out,” is the term reserved for low-pressure systems that intensify rapidly, typically with a pressure drop of at least 24 mb in 24 hours, as reported by Weather Nation TV, confirming that this definition changes based on latitude.
A map shows areas on the West Coast that will be affected by the bomb cyclone and atmospheric river weather systems.
The extreme nature of this storm raises questions about the influence of climate change on weather patterns. Warmer ocean temperatures are believed to intensify atmospheric rivers, making such events more frequent and severe.
Experts have linked severe storms such as these to climate change pushing more moisture into the atmosphere and energizing weather systems, as reported by Newsweek.
“There’s more moisture in the atmosphere, so there’s more moisture that falls out of it,” Chris Brierley, a professor of climate science at University College London, who specializes in climate modeling, previously told Newsweek.
“The [increased] severity is something we have projected for quite a while, and is something that we’re seeing across the board with storms—that when it rains, it rains more, just purely from a thermodynamic response of a warmer atmosphere and a higher saturation of vapor pressure,” he added.
Newsweek contacted additional climate experts for comment on Monday via email.
As the West Coast braces for the storm, residents in low-lying areas are advised to prepare to leave if flash flood warnings are issued. Weather Nation advised that areas along the coast could also see strong enough winds to down trees and power lines, primarily from Tuesday into Wednesday.
Residents in affected states should continue to monitor updates from the National Weather Service (NWS), weather stations, and local authorities as the situation develops.
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