THE people want large unruly Cloudbreak but the stage will probably be refined Restaurants as we move towards the long talked about peak of the swell at the Volcom Fiji Pro.
It’s hardly our call to make, but quite aside issues with competitors’ equipment there are more specific mathematical issues within the current format in large swells. Coming back to that distribution of waves in a swell, we know that the outcome at a break like Cloudbreak is affected, of course, by skill and ability but also (as perhaps a more significant factor than beach break locations) by the occurrence of waves with the highest scoring potential, in this case typically the larger waves. As the swell size increases the gap in size between the largest waves and the average sets increases too, further differentiating the best scoring waves from the mid range possibilities, or the paddlable waves from the clean-up sets.
For example in a 4ft swell one wave in a thousand will be in the 8ft range with one wave in ten nearer 4-6ft – a small difference between the best of the swell and the bulk of scoring waves. Competitors can comfortably opt to sit for the more prevalent 4 footers or gamble on the larger sets. With swell in the 10ft range the largest waves can hit the 20ft mark, with the bulk of the swell at a significantly more modest 10-15ft. This more significant difference between the largest waves and the average sets causes two issues: one around positioning and the obvious consequences of getting it wrong in such critical conditions and the other around the current 30 minute heat structure. The more important those largest waves become, and the more important positioning for them becomes, the longer the wait between waves. For this reason big wave events normally run on longer heats. Although as surf fans in this sort of scenario most of us are probably more interested in seeing the worlds best surfers surf the worlds most challenging waves it’s not unreasonable that professional athletes with their careers on the line want a level playing field for competition, something 30 minute heats can curtail in this sort of condition and a consideration not lost on the ‘CT surfers or event organisers. Of course ultimately only the day and the team on the ground can make that call but as we understand it preparations are already underway for a still epic day of competition at Restaurants tomorrow.
June 2012 vs July 2011
Not since the Teahupoo Red Alert swell of 2011 has a contest window seen this kind of anticipation around a serious swell. Coming off the back of a couple of epic Cloudbreak sessions in 2011 – the obvious questions are ‘how big will it be’ and ‘will it beat the July 2011 session’. Interesting to put them side by side, but first a bit of back story to the swell:
We’ve got a fairly typical scenario for good fetch for Fiji, with the subtropical ridge sitting further south than perhaps usual in the Southern Hemisphere winter, a large high pressure system south of Australia ‘squeezes’ a deep (964mb) passing low generating not only an area of high winds, but also a long fetch travelling in the same direction as the swell it’s creating over the course of a couple of days. The result is swell of around 40ft located in the perfect window for Fiji.
A minor complication to easy analysis of this event was a solid East Coast low pressure system forming further north in the Tasman sea immediately afterwards. Itself responsible for a 20ft swell in NSW it meant any attempt at easily decoding the scale of the Fiji swell from satellite or Australian buoy data was confused by both swells running at the same time.
So how big might it be? Here are the model numbers from the swell in July last year:
Now you need to bear in mind these are model forecast numbers. They’re not based directly on observation (eg. from a wave buoy or Satellite) however they are from the ‘analysis’ run of the model. The way any model works is to look at what’s actually happening now and extrapolate for the future. The way our swell model works is to look at the atmospheric conditions now, calculate the resulting swell and propagate it to it’s destination (in this case the reef at Tavarua). The current atmospheric conditions are themselves derived from a variety of sources, including satellite observations of the actual wind speeds in the original storm. This means the numbers above aren’t completely verifiable at their destination, but have been produced in a robust and replicable way at their source. So lets compare them to this Friday’s swell:
You’ll see immediately that at it’s peak the 2011 swell at peak is 3ft (or almost 30%) larger on the model forecast. You’ll also see this year that the models discerning a secondary, smaller, swell running alongside the main swell on Friday morning from that East Coast Low, where this appears to disappear by the afternoon what’s actually happened is the model sees both swells as so similar it considers them a single event. Our experience suggests that in scenarios like this (although overall wave heights are increase in combination from multiple swell sources) the resulting swell does tend to have a different character to ‘pure’ swells – normally in a negative sense for big wave surfing.
Bear in mind also that that 3ft / 30% difference is the ‘significant wave height’ – that’s the average of the largest third of waves. As we’re always keen to point out the distribution of wave heights in a typical swell makes waves up to twice this size relatively likely over the course of the day. Given that our recollections of any swell tend to be around the largest waves ridden (that stand out set in a session) it means that the gap potentially increases to around the 6ft mark at peak. Overall, with the data we have to hand we’re looking at an even of slightly reduced size by comparison. The caveat is that the largest error we see in the model derived analysis is typically around the peak of a swell when compared to local wave buoys and that margin of error can exceed the 30% we’re talking about here as a difference (a wordy way of saying we could still be wrong!).