There are lots of terms meteorologists use to describe storm systems, some of them more colorful than others. Perhaps the most-used and exotic-sounding one that is floating around in reference to the blizzard just beginning to bear down on the East Coast is “bombogenesis.”
While it sounds like a band name or a game console, it’s really just a fancy way of saying that an area of low pressure is rapidly intensifying. Specifically, to qualify as a “weather bomb,” the minimum central pressure of the storm must drop by at least 24 millibars within 24 hours.
Some storms meet or exceed this threshold, as the blizzard is in the process of doing. A low pressure area with a minimum pressure of about 1,000 millibars around 11 p.m. is anticipated to intensify to sub-980 millibars by the same time Tuesday night.
Bombogenesis is a fairly rare occurrence, happening in a particular region in the northern midlatitude, such as the Northeast, a few times a season. Such intense, large-scale storms are more common in the U.S. during fall, winter and spring.
Storms that bomb out like this are typically accompanied by strong winds, since air rushes from higher to lower pressure, as well as heavy precipitation.
Storms that go through this process are fueled by intense air and moisture contrasts, such as the presence of a polar air mass across the northeastern U.S., and a warm and moist air mass sitting over the Gulf Stream waters.
Aided by jet stream winds and areas of atmospheric spin, these storms can generate a lot of lift, which is a trigger for heavy rain and snow.
East Coast blizzards tend to be weather bombs, as are some of the more intense North Atlantic and North Pacific winter storms. Such a storm recently caused damage in Newfoundland, where winds exceeded 100 miles per hour. That storm saw a staggering 42 millibar pressure drop in 24 hours, which helps explain the strong winds.
And in the UK, winter storm Doris rapidly intensified, too, causing damage as well.
Because bombogenesis often occurs over the oceans, the National Weather Service’s Ocean Prediction Center maintains one of the best catalogs of weather bomb animations. They reveal how these storms are shape shifters, going from relatively innocuous-looking spins to full-fledged, backwards shaped commas.
time series of HF low that battered Newfoundland; seas up to 46ft this morn over the Labrador Sea! images 24hr apart (March 10/11/12 at 15Z) pic.twitter.com/jiJ41sSEGt
— NWS OPC (@NWSOPC) March 12, 2017
Here’s what such storms look like in the Pacific, via a satellite loop.
So remember, the next time you hear the word “bombogenesis,” or a storm referred to as a weather ‘bomb’: It means you should take that storm seriously.