Exploding Weather Myths: ‘Bomb Cyclone’ Explained

Forecasters anticipate a “bomb cyclone” could smash the Northeast this week, but the term isn’t a ratings-driven hyperbole; it’s a name rooted in the science of meteorology.

For a storm to be classified a “bomb,” it must meet a set of strict criteria, led by a rapid decline in surface-air pressure, which is the weight of the atmosphere.

Typical pressure rests around 1010 millibars, and most major rain and snow storms in the United States land around 995 or 990, the Washington Post reports. A bomb,though, must boast a 24-millibar drop in 24 hours.

A cyclone’s strength largely depends on its air pressure. The lower the pressure, the stronger the storm — which means that bomb-ranked storms can conjure up devastating wintry conditions.

“Explosive bombogenisis” occurs most often in the winter, and it nearly always exists as an East Coast weather event, where temperatures are traditionally lower.

This week’s storm is expected to strike New England as a classic bomb cyclone with a dramatic 50-millibar dip in a 24-hour period. A pressure drop of this magnitude shows how much air is being drawn into the storm’s circulation, allowing it to gain strength at a quicker, more intensified rate.

As the air spirals in toward the center of the storm, rises and leaves through the top, the storm could continue to grow if more air leaves the storm than is taken in.

While bomb cyclones are merely a meteorological description of a storm and are not named to describe their impacts, they are often heavy storms that are accompanied by hurricane-force winds, dumps of heavy rain or snowfall and flooding along coasts.

The Northeast and Mid-Atlantic regions will experience locally heavy snow as a result of the bomb cyclone this week, the National Weather Service reports. But in the Southeast, mixed precipitation, which has already fallen in some areas Wednesday, could have a dramatic effect on roadways, schools, businesses and utility services.