Remembering Australia's Biggest East Coast Swell of a Generation

Tony Butt

by on

Updated 52d ago

Remembering is a series looking back at the best and biggest swells to rumble the planet. We've covered Hercules, Thundercloud, Hawaii 1969 , Indo 2018 and Braer.

On Monday June 6 2016, the northern beaches of Sydney looked more like Hawaii than the east coast of Australia. A massive northeast swell with moderate offshore winds produced the kind of surf that hadn’t been seen here for decades. Wave heights at some spots, such as the legendary Queenscliff Bommie, hit the 20-foot mark. The extreme size, unusual direction and clean conditions made it a particularly rare event, with some people calling it a once-in-a-generation swell.

With more than a few people willing to paddle out and give it a go, this became one of the most highly-documented swells in surfing history. We covered this incredible run, HERE. So here I’m going to dig a bit deeper into the swell, where it came from and why it was so unusual.

Our Tasman Sea swell chart for late Sunday June 5.

Our Tasman Sea swell chart for late Sunday June 5.

From its initial spawning off Queensland, the storm and the swell it produced travelled down the east coast until it got to southern NSW. Strong onshore winds and stormy conditions first hit Queensland and northern NSW on Saturday 4th. The next day, Sunday 5th, conditions cleaned up in the north while onshore winds and a rising swell started to affect the south. The swell peaked late Sunday, and was still very large on Monday morning. But now the storm centre had passed and the wind had turned offshore. The surf kept pumping all day on the Monday and for the next four or five days, staying clean and gradually ramping down in size.

This swell was very different from most big swells that hit NSW. Normally, they come from lows that track from west to east across the Tasman Sea between Tasmania and New Zealand. A strong fetch on the southwest flank of one of these systems will generate a big, long-period southeast swell, perfect for the right-hand pointbreaks. But the swell that hit in June 2016 came from a low that started off in the north and tracked south from Queensland to southern NSW. The swell direction started off from the northeast and then swung east, which meant that some rare spots were able to be surfed, like the Queenscliff Bommie, and a huge left at North Avalon. The more ‘square-on’ direction wasn’t too good for most of the right points, but did produce some crazy surf at places like Cape Solander and Shark Island.

Forecast for Manly Beach, Sydney: check how the swell persists and the wind turns offshore from Monday onwards.

Forecast for Manly Beach, Sydney: check how the swell persists and the wind turns offshore from Monday onwards.

After reaching south NSW on Monday 6th, the low moved east, away from the coast. A large, slack area on its northern flank persisted, keeping conditions clean with moderate westerly winds. At the same time, the system pushed up against a big, stable high sitting over New Zealand, which maintained and area of gale force north-easterlies and kept the swell pumping.

But how did such a rare system like this develop in the first place? As is often the case, it was a combination of circumstances. Firstly, in the days preceding the storm, there was a very strong westerly airstream in the upper atmosphere across northern Australia and an easterly airstream on the surface. In other words, a large variation in wind direction with height. This is called shear and it is very important for encouraging the formation of cyclonic storms.

Secondly, the sea-surface temperature (SST) happened to be unusually high off the east coast. The extra heat in the ocean causes more evaporation and uplift, and pumps enormous amounts of energy into the atmosphere from below, increasing the likelihood and strength of storms.

Sea-surface temperature (SST) anomaly for June 2016, i.e. the difference between the June 2016 SST and the June SST averaged over many years.  Off the East Coast the water was several degrees warmer than average.

Sea-surface temperature (SST) anomaly for June 2016, i.e. the difference between the June 2016 SST and the June SST averaged over many years. Off the East Coast the water was several degrees warmer than average.

Thirdly, there was a large area of high pressure over New Zealand which persisted for several days. This helped to steer the trajectory of the low and to maintain the north-easterly fetch, as I mentioned above. As that windfield moved down the coast and strengthened – steered around the western flank of the high – there was also a certain amount of dynamic fetch (see HERE) which would have further contributed to the extreme wave heights late Sunday and early Monday.

Large east or northeast swells like this tend to cause a lot of damage to shoreline properties, particularly in highly populated areas like Sydney. Professor Andrew Short is one of the world’s experts in coastal science, and has spent a lifetime studying the Australian coastline. He points out that waves this big and from this direction have reached Sydney several times in the recent past, and, although not necessarily clean enough to surf, have caused extensive damage to coastal properties. The real problem, he explains, is not the waves themselves, but the fact that people keep building stuff too close to the shore. As long as they keep doing it, the problems will continue.

Animated wind and pressure chart for Friday 3 to Monday June 6 2016, showing the low as it develops and runs down the East Coast.

Animated wind and pressure chart for Friday 3 to Monday June 6 2016, showing the low as it develops and runs down the East Coast.

In other words, the ocean will always do its thing. But the problems start when people are around to be affected by it. In a similar way, the big swell of June 2016 went down in surfing history not because it had never happened before, but because there were so many people around to ride it and document it. Midget Farrelly (who passed away about two months after that swell) was the first official world champion in 1964 and surfed the Australian east coast since the early 1950s. He explained that there have been several similar swells over the last 50 years or so, most notably in 1974. However, there were a lot less surfers back then, and there was not the interest in big waves that exists nowadays. Therefore, those swells went practically unnoticed; while this one – observed and participated in by hundreds if not thousands of people – was big news.

What I’ve just been talking about is another good example of the weak anthropic principle, whereby a phenomenon becomes much more important if there is somebody around to make use of it or to see it happening. Strangely, this seems to have popped up again, even though in a previous article (HERE) I swore I was never going to mention it again.

Cover shot by Juan Medina.