Blizzard, snow, gusts of wind… A “cyclonic bomb” hit the eastern United States this weekend. This storm, characterized by the explosive power of rapid drops in atmospheric pressure, blanketed much of New England in snow.
the national weather service (NWS) recorded gusts of wind of 80 to 120 km/h, and predicted polar temperatures at night as well as power cuts, usual every winter when the power of the wind or the weight of the snow tears the power lines. Several cities in the region recorded all-time records, with more than 70 cm of snow.
The governors of New York, New Jersey and Massachusetts have declared states of emergency. “It will be a historic blizzard, Ruthzee Louijeune, Boston city councilor, told the American press agency. It is the strength of the wind and the amount of snow that make it particularly dangerous”. And the cold wave hits the whole coast. In usually tropical Florida, frost alerts have been issued. With the cold, the famous iguanas weighing up to nine kilograms, fall from their trees.
A not so rare phenomenon
Unlike cyclones which occur in the warm season, this “weather bomb” – another name for the “cyclonic bomb” – is a depression occurring in the cold season. It generally causes an explosive cocktail: extreme cold, heavy snowfall and strong wind. We speak of a “bomb” when the central pressure of a depression drops by 24 millibars or more in 24 hours.
As the sun ceases to shine above the Arctic at this season, the air there is particularly cold. Normally, eastward-flowing jet streams keep this cold air over the Arctic. But sometimes they move, allowing that air to descend to the south.
This is not a new phenomenon, it is even repeated regularly in the United States. This weekend’s storm hit nearly 44 years to the day after the monstrous blizzard that paralyzed New England in 1978. A storm that dumped more than 70 cm of snow on Boston, killed dozens people, trapped others in their homes and blocked major highways for a week. It also comes four years after winter storm Grayson hit the same region of the world in 2018.
Meteorologists even estimate that this type of storm breaks out in the northern hemisphere about ten times a year, explains Wired. They are not all at the level of the “cyclonic bomb”, which, it can occur on average once a year, according to Scientific American.
A controversial term
The term has been used since the 1980s. It was defined by professor of meteorology at McGill University in Montreal, John Gyakum, and meteorologist Fred Sanders. Nevertheless, John Gyakum decided not to use it anymore. “When I talk about these explosively developing storms, I take the trouble to pronounce the terms ‘explosively developing’ but I don’t use ‘bomb'”, he explained in January 2018 to the American version of the HuffPost.
The reason ? The security context of the world, and in particular the terrorist threat. At the time, the United States had just been hit by a terrorist attack in New York, in the borough of Manhattan, killing eight people, but also by the attack of a white supremacist during a demonstration in Charlottesville, Virginia. Two ram-truck attacks that visibly marked the scientist: “It’s somewhat inappropriate when you consider other aspects of the world at this time” to use a term that refers to “the deadly and incendiary weapon that is the bomb,” he said at the time.