Weather Academy: What is a bomb cyclone?

MONROE, La. (KNOE) - During January, we’ve been talking about different winter terms. And last week, we did an experiment demonstrating pressure. That was just a refresher to show you how strong pressure can be. It was leading us up to this topic, bomb cyclones.

The term bomb cyclone is something you typically probably hear on national news or even see on social media. But what exactly is a bomb cyclone? Well, a cyclone is just another name for a storm system. In particular, a bomb cyclone is a storm system with an intensifying area of low pressure. What’s happening here is a vacuum effect is lowering that pressure. Now we talked about highs and lows. And to refresh on that, for low pressure, our air is converging into the center. Remember that the atmosphere wants to equal itself out. The area of high pressure wants to move to the area of low pressure as that air is converging into the center has nowhere to go but up. So it’s rising. What’s happening is it’s converging and rising so quickly that it creates that vacuum effect and therefore lowers the pressure. As the pressure drops, we start to see increasing lines of pressure around the low. Before, we only had a couple of lines, and now we have four. The closer the lines, the more intense the storm could become.

We don’t typically see this with storms overland. We see it with storms over the ocean, similar to tropical storms or hurricanes. But for it to be a bomb cyclone, it has to go through a process called Bombogenesis. Bombogenesis is a term used to describe a rapidly shrinking cyclone. We see an increase in these pressure lines. It has to drop at least 24 millibars of pressure in at least 24 hours to strengthen rapidly over a short amount of time. Now when this happens, it causes intense, active weather. We typically see severe storms that produce very heavy rain on the leading edge of bomb cyclones. And these are also the storms that can lead to catastrophic tornado outbreaks.

Another thing that these can produce is strong, damaging winds, and we’re talking about so strong of winds that they lift those high-profile vehicles as they’re driving down the road. Now another thing that these low-pressure systems can do is cause intense snowstorms and blizzards. The reason for that is it’s pulling down the cold northern winter air, and it’s colliding it with the warmer tropical air down towards the south. So next time you hear or see something about a bomb cyclone. I hope this explainer helped you learn that coming up next week, we’re going to be diving into the topic of snow.

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