What Is This ‘Bomb Cyclone’ Thing About to ‘Blast’ the East Coast?

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
.”

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.

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.

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.”

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.

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.

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).

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.

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

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