‘Bomb cyclone’ is ready to explode off the US west coast

A powerful bomb cyclone powered by a Category 5 atmospheric river is expected to blast across the US West Coast this week, threatening to unleash hurricane-force winds, catastrophic flooding and massive mountain snowfall.

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 are in the “extreme” category.

More from the Newsweek Vault: 5 Steps to Building an Emergency Fund Today

As reported by Newsweekup 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 and affected the Pacific Northwest. Rivers and flash floods are likely in these areas.

“This intense storm system is expected to bring major impacts to areas of northwestern and northern California with heavy rain, strong winds and large swells,” Weather Nation TV reported.

“The storm system will have the potential to more than double this pressure drop, with forecast models showing a drop of 50-60 mb (millibars) in less than 24 hours, starting at over 1,000 mb on Monday evening, possibly dropping to below 950 mb on Tuesday night.”

More from the Newsweek Vault: Online banks vs. Traditional Banks: Learn the Differences

Meteorologist Ryan Maue, former chief scientist at the National Oceanic and Atmospheric Administration, advised on X, formerly Twitter, Sunday that the central pressure will drop nearly 70 mb in 24 hours and reach 942 mb, equivalent to a Category 4 hurricane.

The Category 5 atmospheric river – a designation reserved for the most extreme rain events – will channel huge amounts of water vapor into the region, potentially triggering widespread flooding and landslides.

More from the Newsweek Vault: What is an emergency fund?

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 and cools it into heavy precipitation.

A so-called “bomb cyclone” is when a cold air mass collides with a warm mass, intensifying a cyclone, causing 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 thought to intensify atmospheric rivers, making such events more frequent and more severe.

Experts have linked severe storms like 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 falling out of it,” Chris Brierley, a professor of climate science at University College London who specializes in climate modelling, previously said. Newsweek.

“The (increased) severity is something we’ve been anticipating for a while, and it’s something we see 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 vapor pressure,” he added.

Newsweek reached out to additional climate experts for comment Monday via email.

As the West Coast braces for the storm, residents in low-lying areas are advised to prepare to leave if flash floods are issued. Weather Nation said areas along the coast could also see strong enough winds to down trees and power lines, primarily from Tuesday into Wednesday.

Residents of affected states should continue to monitor updates from the National Weather Service (NWS), weather stations and local authorities as the situation develops.