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Bombo-what? Here’s the weather term people are talking about with this week’s storm

James Abundis/Globe Staff

The storm approaching New England is forecast to undergo bombogenesis as it rolls up the coast and becomes a weather “bomb.” But you won’t be seeing any fireworks in the sky. Just snow and wind — and possibly plenty of it.

The ominous-sounding term, coined by a pioneering MIT professor, has long been used by meteorologists. It refers to the rapid intensification of a cyclone, which is a system of winds spinning around the center of a low-pressure area.

The technical definition of bombogenesis is when the atmospheric pressure drops at least 24 millibars over 24 hours. It can happen when a cold air mass encounters warm air, such as that over ocean waters, the National Oceanic and Atmospheric Administration says. The arctic cold air mass we are currently enduring in Massachusetts is expected to meet a low-pressure system moving up the coast with relatively warmer air.


Forecasts call for a 35-millibar drop from 7 p.m. Wednesday to 7 p.m. Thursday, and the pressure could dip even lower after that, said Dave Dombek, senior meteorologist at Accuweather.com.

“A bomb goes off and it explodes. That’s essentially what’s happening. It’s not a gradual slow process that takes days to unfold. It goes from almost nothing to a very powerful storm in almost no time,” he said.

Dombek said the storm is expected to “bomb out” offshore. “This storm is not going to be bombing out over Cape Cod or Boston. It’s going to be out in the ocean,” he said.

“I would not want to be a mariner Wednesday night and especially Thursday and Thursday night as the thing goes crazy,” he said.

But he also said the storm is going to have a “pretty wide area of influence” and will hit the mainland with wind and snow, causing drifts and hampering visibility. (The National Weather Service on Tuesday warned of 4 to 7 inches of snow in parts of Eastern Massachusetts.)


The term bombogenesis was coined by the late meteorology professor Frederick Sanders. Sanders, who died in 2006, is credited with using the word “bomb” to describe explosively intensifying winter storms, MIT says.

Bombogenesis is a rapid type of “cyclogenesis,” the birth and intensification of a cyclone. Another term for “bombogenesis” is “explosive cyclogenesis.”

“During winter, such cyclone bombs can cause intense cyclones just off the east coast of the USA with storm-force winds, high waves, and blizzards or freezing rain,” according to the textbook “Practical Meteorology” by Roland Stull.

So get ready, Massachusetts.

Jeremiah Manion of the Globe staff contributed to this report.