I was watching the network newscasts last night, and the Today show this morning. The buzz word in the weather segments was “Bomb Cyclone.” My wife asked me what’s a bomb cyclone. Here’s what that means.

A bomb cyclone is a storm system that rapidly strengthens. As meteorologists, we actually have numbers to quantify if a storm system is “bombing out.”

First let’s get the second word out of the way - cyclone. You may have heard that word used in several different ways over the years. In weather, cyclone has been used as a mid-America way to describe a tornado. In the south Pacific, cyclone is also the term for a hurricane. But for most of meteorology, cyclone refers to a large-scale storm system. The dangerous snowstorm forming today over the Southeast and Mid-Atlantic is a cyclone.

Now to figure out if a storm is “bombing out” or will just be a strong storm system, we have to look at the lowest air pressure in the center of the storm system. To reach the criteria of becoming a bomb cyclone, a storm system’s lowest air pressure has to go lower by 24 millibars(mb) in 24 hours. Millibars are one type of unit of measure for air pressure. Often in a weathercast you hear air pressure quoted in inches of mercury. Millibars is the metric version of reporting the air pressure. Remember- most of the world uses metric. Since meteorology is a global science, we often use metric.

The storm intensifying now over the East Coast will have a central pressure dropping from 980 mb Saturday afternoon to 933 mb Sunday afternoon. This storm will have an air pressure drop of 47 mb in 24 hours. This air pressure drop is much more than is needed to reach the official criteria for a bomb cyclone.

Forecast map shows the storm forming off the northeast U.S. coast.

Surface pressure forecast at 2 p.m. Sunday, with the bomb cyclone fully developed in the north Atlantic.

Rapidly lowering air pressure creates very high winds. Just think of the weather broadcasts you see as an intensifying hurricane approaches the Gulf Coast. The expected wind gusts go up.

Below is a forecast that shows you how the winds will gust to over 90 mph off the northeast U.S. coast.

Wind gust forecast shows 90 mph gusts in the north Atlantic around the bomb cyclone.

We have had bomb cyclones over the Great Lakes. We usually have one storm that “bombs out” every few years. The intensity of our bomb cyclones tend to just meet the criteria for bombing out.

The current storm forming into a bomb cyclone will bring nasty weather to New England, but not reach peak strength until it’s over the north Atlantic.

Now you know about bomb cyclones. My wife also knows.

Note to readers: if you purchase something through one of our affiliate links we may earn a commission.

Registration on or use of this site constitutes acceptance of our User Agreement, Privacy Policy and Cookie Statement, and Your California Privacy Rights (User Agreement updated 1/1/21. Privacy Policy and Cookie Statement updated 7/1/2022).

© 2022 Advance Local Media LLC. All rights reserved (About Us). The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Advance Local.

Community Rules apply to all content you upload or otherwise submit to this site.