Photograph from NASA Earth Observatory
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A rare, extremely powerful winter storm hit northwestern Alaska on November 8 and 9, 2011, bringing hurricane-force winds, high seas, and heavy snow.
Photograph from NASA Earth Observatory
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Weather Bombs

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The United States faces extreme cold due to Winter Storm Grayson, a bomb cyclone slated to hit the East Coast this January. The powerful low-pressure system could resemble a winter hurricane and bring near-blizzard conditions, coastal flooding, and even power outages.

ABOUT WEATHER BOMBS

A "bomb cyclone" is the unofficial yet increasingly popular name for when a storm strengthens quickly as a result of a drop in pressure. The lower the pressure, the stronger the storm, creating one massive bomb system.

It's caused by "explosive cyclogenesis," a process in which a low-pressure storm falls 24 millibars—a unit of pressure—over a 24-hour period. This can happen when cold and warm air masses collide. The central air in the system rises quickly and the pressure of the warm, wetter air plummets.

More air rushes to fill the space between the two masses, which speeds up winds and intensifies the storm. For comparison, think of how a spinning ice skater will draw her arms in toward her body to speed up on ice. The arms are the air getting sucked in and the skater's body is the low-pressure system.

This process, also called "bombogenesis," can be triggered by changes in jet streams, the narrow, fast-moving currents of air high in the atmosphere.

Despite the daunting name, weather bombs are actually fairly common. The U.K. experienced a bomb in February 2017 with the arrival of Storm Doris, which brought snow and strong winds. The U.S. has seen bombs in the form of winter storms Stella and Nemo, among others.

All this extreme weather might be spurred along by rising global temperatures, which, thanks to climate change, are likely to increase in the future.

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