Image: Earth Wind Map

Bombs. They’re on the nation’s collective mind.

Earther can’t really give you any insights into our big button boy’s mindset on the nuclear front, but we’ve got you covered when it comes to this bomb cyclone thing that’s about to “blast the East Coast.”

Advertisement

Snow is falling in northern Florida thanks to moist air from the Gulf of Mexico intersecting with the frigid cold hanging over the eastern U.S. The impending storm will get really organized and march up toward the Mid-Atlantic this evening, where there are rare blizzard watches already in effect. By late tonight or early tomorrow, snow, storm surge, and powerful winds will smack the Northeast.

Along the way, this extratropical cyclone will undergo “explosive bombogenesis.” Or, in less nerdy terms, it will bomb out. And that has got people on edge.

Advertisement

You’ve probably seen the Washington Post tweet that sparked the whole bomb cyclone freakout (it is a Very Good Tweet):

In some ways, the freakout is warranted. This is shaping up to be a massive, dangerous storm that could fell records and cause widespread power outages. Snow in Florida is really, deeply weird and wrong. The cold air rushing in after the storm passes could be deadly. But let’s step back for a sec and talk about what’s actually going on.

Advertisement

In simple terms, bombogenesis describes what happens when a storm’s central pressure drops 24 millibars in 24 hours. The lower the pressure, the more intense the storm.

Those types of rapid drops can happen in hurricanes, but only extratropical cyclones—storms that have cold air at their core—technically qualify as bomb cyclones. That means you generally only get weather bombs in winter, and often in coastal areas where cold land meets relatively warm ocean water. The bigger the difference between warm and cold air masses, the bigger the potential for bombogenesis.

“The contrast between the warm and cold air gives you an indication of the energy available to intensify an extratropical cyclone,” Andrea Lang, a meteorologist at the University of Albany, told Earther. “In this case, large contrasts in temperature between Arctic air currently over the Northeast and warm Atlantic waters suggest the potential for an intense cyclone.”

Advertisement

This week’s bomb storm could see pressure drop an unbelievable 45 millibars in 24 hours, according to the National Oceanic and Atmospheric Administration model ensemble. It’s forecast to bottom out around 950 millibars, a central pressure typically associated with Category 3 hurricanes (though this storm will not bring Category 3 winds).

While this storm could be one for the record books, storms bombing out isn’t that rare. Jonathan Martin, a meteorology professor at the University of Wisconsin-Madison, told BuzzFeed that you can expect about 10 of these types of storms across the northern hemisphere in any given winter. In the Northeast, many storms that bomb out take the form of nor’easters, winter storms that have their strongest winds out of the northeast. In Europe, they’re usually wind storms. Elsewhere like the Bering Sea, they’re just really nasty storms.

Advertisement

Scientists have been throwing around some combination of the terms “bomb,” “bombogenesis,” “weather” ,and “climatological” since the 1940s. They somewhat entered the mainstream lexicon in 1980. That year, MIT professors Fred Sanders and John Gyakumpublished the amazingly-titled study “Synoptic-Dynamic Climatology of the ‘Bomb.’”

It’s one of the first papers to deconstruct the process of bombogenesis. Sanders attributes the focus on rapidly dropping pressure in storms to Tor Bergeron, a Swedish meteorologist who also gave us our working theory of how precipitation forms in the 1930s.

Advertisement

Of course popular lexicon is relative. We’re talking about an academic journal after all. The term “weather bomb” was batted around here and there but really got traction in 1993 according to Google Books search results that Barbara Mayes Boustead, a National Weather Service meteorologist in the Omaha/Valley office and history buff, sent to Earther.

“[It] makes me think that maybe the March Superstorm led to some significant increase in usage of the phrase,” she said.

That 1993 storm was dubbed the “Storm of the Century,” though it’s since been eclipsed by other winter storms in terms of intensity, including a potent 1996 storm (which may also be why references to weather bombs increased throughout the 1990s, though it’s unclear what happened in the 2000s).

Advertisement

Image: Google Ngrams

So yeah, this whole cyclone bomb thing has been a known quantity for a while in the meteorological world.

That doesn’t mean this storm won’t be bad, or that you shouldn’t be prepared for power outages, especially considering the bone-rattling cold that will follow. But make sure to allocate your freakout between meteorological and existential threats accordingly.

Advertisement

This post has been updated with comments from Barbara Mayes Boustead.