Bomb cyclone? Bombogenesis? Scary-sounding weather terms explained

Don’t be alarmed if your social media feeds explode with scary-sounding weather terms like “bomb cyclone,” “bombogenesis” or “bombing out” for a potentially strong winter storm in the forecast for the U.S. Northeast this weekend.

Those are actual terms used by meteorologists when storm systems rapidly intensify as cold air collides with warm air.

And the coastal storm that’s expected to form in the southeastern United States this Friday, potentially bringing heavy snow and fierce winds to East Coast states, might become strong enough to qualify as a bomb cyclone, according to forecasters from AccuWeather and the National Weather Service.

“It actually does look likely that it will be a bomb cyclone,” Paul Fitzsimmons, a meteorologist at the National Weather Service’s forecast office in New Jersey, said Wednesday morning. “The confidence is pretty high that this storm is going to develop and is going to be significant and is likely to become a bomb cyclone.”

<p>A snow truck puts salt on a street Monday in Ben Avon, Pa.</p>

Emily Matthews/Pittsburgh Post-Gazette via AP

A snow truck puts salt on a street Monday in Ben Avon, Pa.

Bombogenesis and bomb cyclones

This is how the National Weather Service describes bombogenesis and bomb cyclones:

“Bombogenesis, a popular term used by meteorologists, occurs when a mid-latitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours. A millibar measures atmospheric pressure. This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengthening weather system is a process called bombogenesis, which creates what is known as a bomb cyclone.”

Although a bomb cyclone can occur in the spring or autumn, it is more common during the winter season, when nor’easters tend to develop along the Atlantic coast and quickly intensify into a major snowstorm or a blizzard.

Bomb cyclones rarely form in the summer, according to the National Weather Service, which notes this weather term is not used for hurricanes and other storm systems that originate in the tropics. When hurricanes strengthen — when their central pressure drops and their wind speeds get stronger — the process is typically known as “rapid intensification.”

What is cyclogenesis?

Another weather term that often pops up on social media is cyclogenesis, which is defined as “the formation or intensification of a cyclone or low-pressure storm system.”

Cyclogenesis is a more general term than bombogenesis because it does not require a specific threshold of a storm’s pressure dropping over a certain time frame.

In short, bombogenesis is a specific type of cyclogenesis, and it has to meet the threshold of having its atmospheric pressure drop 24 millibars in 24 hours. As one weather website explains it, “Bombogenesis is cyclogenesis taken to the extreme.”

What is the origin of these strange-sounding words?

“The term bombogenesis comes from the merging of two words: bomb and cyclogenesis,” AccuWeather explains. “All storms are cyclones, and genesis means the creation or beginning. In this case, bomb refers to explosive development. Altogether the term means explosive storm strengthening.”

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