The huge East Coast snow and windstorm that delivered an icy mix of snow and rain to the Deep South on Wednesday, before turning up the Atlantic coast Thursday bringing hurricane-force wind gusts, s termed a “bomb cyclone” – which had not been part of the popular lexicon, until now.
Like the polar vortex, which became all the rage four years ago today, when exceptionally cold polar air invaded the northeastern portion of the county on January 6-7, 2014, the expression bomb cyclone is actually a shorthand version of “bombogenesis” merged with the generic term for low pressure – “cyclone.”
The usage appeared in a meteorological paper in 1980, and had been noted in prior decades among a handful of scientists to describe an extraordinary drop in atmospheric pressure, defined as at least 24 millibars in 24 hours, which requires a very dynamic– polar air collided with a subtropical stream, usually over the warm water of the Gulf Stream off the mid-Atlantic coast.
The explosive end result resembles a winter hurricane, fed by polar air instead of tropical seawater and a ring of thunderstorms in the eyewall of a tropical system. The pressure drop on the order of a Category 3 hurricane is capable of bringing winds in excess of 70 mph, battering waves and a dangerous storm surge with major flooding, which happened in southeastern New England Thursday afternoon, January 4.
The closest experience we’ve had to this kind of event was the Blizzard of January 1978, when the pressure plummeted to 28.47 inches Columbus, and a wind gust peaked at 69 mph, as the temperature plunged to near zero and the snow piled up in historic 10- to 25-foot drifts.