The Intersection

Yikes. Australia got slammed today, or yesterday–not sure as to the timing, but it was apparently a Category 5 storm, perhaps even up to the time of landfall. Australia’s last really big one was Tropical Cyclone Tracy, which devastated the city of Darwin in 1974, and which had the distinction of being very tiny, yet nevertheless very deadly. In fact, if you go the Wikipedia link for Tracy, there’s a fascinating image comparing this storm with the biggest typhoon ever recorded, 1979’s Super Typhoon Tip. Tip was the size of the entire Western half of the United States. By comparison, Tracy was about the size of a big city. Just goes to show you that when it comes to hurricanes, size doesn’t always matter.

The landfall of the most recent storm–Larry–also serves to remind us that we aren’t the only part of the world that has to deal with hurricanes. Not even close. There are some 80-85 tropical cyclones per year globally, in seven different ocean basins. And the planet may be making a run for an eighth basin. Two years ago around this time, the first hurricane ever recorded in the South Atlantic ocean hit Brazil. At least one scientific paper links this development to climate change–not in the sense that global warming caused this individual storm (named Catarina), but in the sense that global warming may change the South Atlantic in such a way as to make it more hospitable to similar hurricanes in the future.

In any case, when it comes to Larry, I will try to follow the aftermath of this storm to the extent that I can, even though I was supposed to be taking a break from blogging. The American media seems very interested in the story. So far, though, none of the early news reports seem to contain any detailed mention of the effect of the storm surge–which, with a Category 5 storm, could have been massive….

CORRECTION: I, and many in the media, were confused because we did not realize that Australia uses a different tropical cyclone categorization scale than the Saffir-Simpson scale used in the U.S. So this storm was almost certainly not a Category 5 by our standards–probably was closer to a Category 3….


  1. #1 Stephen Gloor
    March 20, 2006

    We have had a few since then. One of the worst was Vance that his Western Australia in 1999:
    However here in WA it is so sparsely populated that a Cat 5 can hit and miss most population centres.

  2. #2 Zarquon
    March 20, 2006

    I don’t think you get a big storm surge off North Queensland because the Great Barrier Reef protects the coast from the open ocean.

  3. #4 Chris Mooney
    March 20, 2006

    Well, now that I realize this wasn’t as strong a storm as I had originally thought, I don’t expect as big of a storm surge problem anyway….

  4. #5 Blair Trewin
    March 20, 2006

    There seems to be a bit of confusion about this one. Category 5 on the Australian scale is pretty close to Category 5 on the Saffir-Simpson (the scales diverge lower down – an Australian Category 1 would be a tropical storm on the S-S scale). The S-S Category 3 reports are based on the highest observed winds (themselves an estimate of questionable quality), not the highest estimated sustained winds in the cyclone, which were probably somewhat stronger.

    It’s also debatable whether or not Larry was a genuine Category 5 at landfall (on either scale). Current discussion suggests it was more probably a Category 4 on both scales, but we’ll need post-event surveys to be more confident.

    Larry is certainly the strongest cyclone at landfall in Queensland since 1971, and probably since 1918. However, as Stephen Gloor says above, there have been numerous category 5 landfalls in Western Australia in recent decades. This is a very sparsely populated coastline and the only one to hit a population centre of any size was Vance, which hit Exmouth in 1999. Fortunately Exmouth is a relatively new town purpose-built for severe cyclones (it largely exists to support a US military communications facility nearby) and suffered only minor damage.

    Whilst damage reports are still sketchy, it seems likely that economic losses will be in the order of several hundred million dollars, which would make it the most damaging tropical cyclone to hit Australia since Tracy in economic terms. Much of this is the apparent loss of 80-90% of the Australian banana crop.

    Finally, storm surge certainly can be a significant issue on the east coast (indeed the highest storm surge ever recorded occurred on the Queensland coast in 1899). I haven’t seen much in the way of storm surge reports yet from Larry. My understanding is that it hit at relatively low tide which reduced the impact.

  5. #6 Chris Mooney
    March 21, 2006

    Thanks, Blair, that’s very helpful.

  6. #7 Spotted Quoll
    March 21, 2006

    “there have been numerous category 5 landfalls in Western Australia in recent decades”

    And last year there was a cat 4-5, cyclone Ingrid, that hit Queensland, the Northern Territory, and Western Australia!

    And this page has a map (scroll down to near the bottom of the page) showing cyclone frequency across tropical Australia:

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