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Explosive Cyclogenesis, Or “Bombogenesis:” What Is It?

24 Mar 2014, 10:59 am

Bombogenesis: it’s always been one of my favorite meteorological terms.

If you’re wondering what, exactly, bombogenesis means, let’s first say the more typically used term (or the more “official” term, if you will…): Explosive cyclogenesis.  What bombogenesis, and also explosive cyclogenesis, refers to is a rapidly strengthening low pressure system.  If you go by millibars, which most of us in the meteorological community do, it requires a 24 millibar drop in sea level pressure over a 24 hour period.  For a little more on cyclogenesis you can visit the American Meteorological Society’s website and also Wikipedia.

I’m reminded whenever this term comes up of a research paper I did in college on explosive cyclogenesis/bombogenesis.  Being kind of a nerd (OK, a big one), I felt the need to start my PowerPoint presentation on the March superstorm of 1993 (sometimes called the Storm of the Century) with a cannon shot sound effect.  It ended up being one of my favorite moments of academic fun in college, and got a good reaction from my classmates.

That cannon sound might be appropriate for folks dealing with these types of storms… the type that models can’t usually get a grasp on until it’s almost upon you.

Let’s talk about how this term relates to what’s happening in the western Atlantic as we start out this week…

ATLANTIC COAST STORM: How It Fits The Definition Of Bombogenesis

Now that you know a storm has to deepen by 24 millibars in a 24 hour period, let’s take a look at our current storm system moving up the Atlantic coast and see how/if it fits the definition.

The following model images are from TwisterData.com, and show the story pretty well… starting with a sea level pressure forecasted at 1012mb (1012 millibars) early Tuesday morning.

Early Tuesday Morning

GFS Computer Model Forecast:

Early Wednesday Morning: 24-hours later

GFS Computer Model Forecast:

 

That ends up being a 24 millibar pressure drop in 24 hours, should it pan out.  Pretty impressive.

The thing to keep in mind is that a 24mb drop in 24 hours sounds impressive, but it also has large impacts.  Quite often with rapidly growing storms like this you’ll see impressive winds (as of this writing, gusts near 60mph are expected near/over Cape Cod) and impressive levels of precipitation.

In the 1993 superstorm there were surface winds recorded in the Carolinas at 70mph!  In higher elevations where nobody lives, but sensors record winds, there were 100+mph winds!  Add in rain/thunder, and heavy snow, and you can see how quickly a storm like this can add up the damage tallies.  You can learn more by going to the National Weather Service’s summary page.

Luckily, this current late-March system seems like it will only graze the eastern sections of the nation.

WeatherNation Meteorologist Aaron Shaffer @ashafferWNTV

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