A new bomb cyclone storm system is headed for the U.S. this weekend, following a previous weekend of severe weather and another bomb cyclone just this month.
Which made us wonder – what are bomb cyclones exactly, and just how common are they?
Starting off with the definition, “bomb cyclone” refers to the phenomenon of bombogenesis, when a midlatitude cyclone rapidly intensifies over a 24-hour period. That means the cyclone is between the tropics and polar regions and that its intensification is measured by its latitude, according to the National Oceanic and Atmospheric Administration.
“At 60 degrees latitude, it is a drop of at least 24 millibars… over 24 hours,” NOAA explained. “At the latitude of New York City, the required pressure drop is about 17.8 millibars… over 24 hours.”
According to the University of Miami, the expression “bomb cyclone” was a slang term for bombogenesis and it has been in use for about 80 years. However, it really took off after “Synoptic-Dynamic Climatology of the ‘Bomb,” published in the October 1980 issue of the American Meteorological Society’s Monthly Weather Review.
Brian McNoldy, a senior research associate at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, explained that the authors called it a “bomb” because it develops with a “ferocity” rarely seen over land.
As for what causes bombogenesis, NOAA said it can occur when a cold air mass collides with a warm air mass. Cold air over warm ocean waters would be such a case.
“Bomb cyclone” is a catchy name, and Scientific American noted this week that it helps the storms get a lot of media coverage. It also said that the storms “really aren’t all that rare,” with at least one usually hitting the continental U.S. every winter.
Per the outlet, atmospheric scientist Ryan Torn of the University at Albany, State University of New York said that the storms often hit off the coast of New York, N.Y., and Boston, Mass. There, they happen when cold air from the north collides with warm air from the south along the Atlantic coastline.
Data shows that the media’s affinity for the bomb cyclone moniker isn’t the only reason why we’ve been hearing more about these storms.
“According to data from the National Weather Service, such weather systems are becoming more common, especially along the East Coast,” said the University of Miami in 2024. “Between 1980 and 2020, the number of bomb cyclones in the Atlantic basin increased by approximately 40%, the data reveals.
In 2018, NASA captured an image of a mid-latitude cyclone undergoing bomb cyclogenesis in the Northwest Atlantic region. In 2019, NOAA meteorologists said a storm that hit the Central U.S. from the Rockies across all of the Plains into the Upper Mississippi Valley “rapidly intensified and has reached a scientific classification called bombogenesis.” It said a bomb cyclone over a landlocked region was “rare” and that it brought blizzard conditions and snow to Colorado and Kansas.
Audacy reported on a West Coast bomb cyclone in November 2024 that hit the Pacific Northwest. That cyclone collided with another phenomenon called an “atmospheric river” to catastrophic impacts, including two deaths. Last month, the Midwest, Great Lakes and East Coast felt the impacts of bomb cyclone conditions over the U.S.
This weekend, predictions indicate the bomb cyclone to hit the Atlantic will strike lower than normal. Torn said “this one is right off the southeast coast of the U.S., which is a very low latitude place for that to happen.”
A Facebook post from the U.S. National Weather Service in Wilmington, N.C., warned local residents to brace for significant snow and cold. Some areas are also expected to see more snow accumulating in the area than it has in 30 years.
Going forward, atmospheric scientist Richard Rood from the University of Michigan, another expert cited by Scientific American this week, said that more bomb cyclones are in the forecast for the Carolinas. Rood said that this expected uptick would be the result of global warming increasing the temperature of both the atmosphere and the Gulf Stream, making the contrast between cold air and the water underneath more pronounced.
“That’s what contributes to this rapid development,” he said.