Anatomy of a Meteorological Bomb


There are two FPB 64s cruising in New Zealand at present, and both made comments to us about a weather “bomb” a few days ago. Mike Parker (Avatar) sent in a link to a New Zealand Met Service post on the genesis of this weather feature, and Carol Parker sent in the photos taken at Cape Reinga. Pete Rossin (Iron Lady) discussed the bomb on his blog. We’ll add links to both at the end of this post. Now for a few comments.


There are various weather scenarios which can create bombs, or rapidly intensifying weather events. The key to unlocking risk factors lies in understanding the 500mb level weather models, which is why we urge everyone to learn how to read these (not that big of a deal). And while you might be tempted to let the professionals call the risks for you, they sometimes miss, or don’t call them early enough for you to be aware of the risk profile before heading off on a long passage.

Beyond this there are several points to keep in mind. Although rare, bombs do occur, so we think the thing to do in terms of the boat is simply assume the worst, and have the right tools on-hand in case we are caught. This starts with massive anchoring gear relative to the boat’s windage. It includes a design oriented towards heavy weather events, with steering control and stability profile appropriate thereto. And it means a periodic look at the 500mb charts to see what might be developing. Finally, this is one of those areas where boat speed pays dividends by reducing exposure time to weather.

We should also add that, although we have investigated a number of weather bombs over the years, we have never been caught out in one ourselves.

Pete Rossin’s (Iron Lady) post on this will be found here. The New Zealand Met Service report is here.

Posted by Steve Dashew  (March 5, 2012)

One Response to “Anatomy of a Meteorological Bomb”

  1. Mike Parker Says:

    Hi Steve,
    Carol’s photo is of a shallow area looking west of the cape into the wind. It was taken from the top of a high cliff. Wind gusts at the top of the cliff were strong enough to make standing (or holding a camera) difficult. We started down the cliff to see how high the waves really were, but then though better of it.

    The interesting thing to me in the photo is that you can see two swells, one coming from the upper left of the picture and another from the upper right. Apparently the underwater topography, maybe aided by current, bent the main swell into the two swells almost 90 degrees apart. The breaking waves were mostly where the two swells crossed.

    The New Zealand met service was really on top of this. We saw a front page article in the national newspaper perhaps 2 days in advance. The worst of the wind was forecast to be well to the south of us, and we were protected by a high hill. So we left Avatar securely tied in a slip at Opua and took this road trip north to go exploring.

    Mike Parker