What Is 'Bombogenesis'? East Coast Hunkers Down Ahead of Nor'easter Winds

The Northeast United States is awaiting intense winds and heavy rains. As residents of the area brace for the nor'easter, many also await the likely drop of a bomb cyclone to accompany it. What is this anyway? While the term may sound like an impending meteorological disaster, the sensation of "bombogenesis" is actually relatively common among many intense storms.

The term bomb cyclone was first popularized in January 2018, with many reports using to to describe a winter storm. The National Weather Service (NWS) defines it as the "rapid intensification of a cyclone (low pressure) with surface pressure expected to fall by at least 24 millibars in 24 hours." As the pressure drops, bombogenesis—the formation of the bomb cyclone—begins.

Once a bomb cyclone has begun, intense winds and heavy rain can be expected. A meteorologist from the NWS told Newsweek in 2018, "The lower the atmospheric pressure is, the more intense the storm is." When bomb cyclones occur around cold temperatures, especially in the winter, snow may be anticipated as the pressure drops. The winds and precipitation can often cause flooding, transportation delays and power outages.

Michael Ventrice, a meteorologist for the Weather Company, told Newsweek that bomb cyclones are relatively common. "You'll usually have at least one year, but there's some variability. You might have a couple one year and none the next year." He also told us that he doesn't believe that climate change is affecting the frequency of these storms.

Cyclone Bomb Boston
Bomb cyclones can often bring intense and heavy precipitation in the form of snow as one did in January 2018 in Boston. Scott Eisen/Getty

In the past two years, they have been a powerful and disruptive force. In January 2018, Winter Storm Grayson underwent bombogenesis, which led to school closures, flight cancellations and flooding. In addition, 21 died from the storm or accidents related to the storm, including a 9-year-old girl who was hit by a truck after sledding into the street. In addition to car accidents, lack of heat and hypothermia caused many other deaths during the storm.

This past March, NPR reported intense flooding in the Midwest after a bomb cyclone brought high winds, heavy snow and rain. Two deaths were reported, one from a man whose car was swept away in flood waters. Another man died trying to help another driver stuck in the flooding. CNN reported evacuations in Hornick, Iowa, following a levee's break. Many Colorado cities faced power outages, which led to school closures and flight cancellations.

Flooding and slick roads make car accidents a common occurrence during bomb cyclones, as happened in Minnesota in April 2019, when AP reported more than 500 crashes.