New England Braces for a Weather Bomb, or 'Bombogenesis'

Dec 29, 2016

Parts of New England, including New Hampshire, are expected to receive at least a foot of snow thanks in part to something known as a weather bomb, or, for the logophiles out there, “bombogenesis.” Why is this storm considered “bombogenesis”? For that answer, we turn to Mark Breen. He’s a meteorologist at the Fairbanks Museum in St. Johnsbury, Vermont. He spoke with NHPR’s Peter Biello.

What is bombogenesis?

I think that’s a really cool catchphrase what is probably a more boring title. It’s known as “explosive cyclogenesis.”

I don’t know. The “explosive” still sounds kind of exciting. Tell us why it’s so “explosive.”

What happens, especially enar the east coast of the US, one of the favorite spots across the globe where you have a great contrast in the relatively warm waters and cold air that often takes a fairly quick shortcut out of Canada. So we have this contrast between very cold and very warm air that meet, often near the coastline of New England.

This is a place where storms take advantage of that. The heat causes the air to rise rapidly. The cold air fills it in rapidly. So you have a quick transfer of that air and what happens is if that the air goes up quicker than the air can fill in, the storm gets stronger and stronger, which means it has stronger winds, which means it pulls more moisture off the ocean and into the storm circulation, and you end up with a storm that gets very strong very quickly.

Is that why it’s hard to predict, because it happens so quickly, and those conditions could easily not turn into something like bombogenesis?

I would say that one of the trickier things is not so much whether it’s going to happen, but how quickly is it going to happen?

What ends up happening is, if it happens more quickly than we forecast, then another thing, another aspect to this is the storm tends to turn a little bit more to the left, or to the west. If it happens a little more slowly, the storm track tends to be a little bit more to the east. And that difference can shift the heavier snow or rain bands, westward or eastward by 50-100 miles.

How often do these tend to happen?

During the course of the winter, we see from one to four of these. There are some of these that take place well off to our east, so another place—and not a place that would affect us—you may not hear about such things taking place to the west of Iceland, for example. But the North Atlantic is often a rich place for storms.

How do you see this one playing out compared to past storms?

It appears it’s not going to strengthen quite as rapidly as we earlier thought. And that means its track is going to be a little bit more to the east. And that’s probably going to lessen some of the snowfall on its western flank. So portions of eastern Vermont and western New Hampshire may end up still with a significant snowfall, perhaps a foot or even 14-15 inches, but probably not the potential that was seen earlier, which was closer to about 18 inches.

Western Maine, on the other hand, [is] still in that zone of very heavy snow. There, that snowfall may be realized in terms of perhaps 18 inches or more.