The Tale Of The Endless Swell
The Tale Of The Endless Swell
The comments from disgruntled new arrivals to the Gold Coast during the horrendous El Niño / Black Summer period of 2018 - 2020 still resonate for me. I'm paraphrasing, but after months of barely a wave over two feet approaching the coast it went something like, “how the fuck does anyone ever get good at surfing around here?”
Those comments seem almost perverse now after a three week run of swell coming at the tail end of a triple dip La Niña. Surf has been abundant and while crowds have been almost apocalyptic at times it's still justified Rabbit Bartholomew's description of legendary surf episodes as a “war of attrition”. Eventually the body can't take another day of paddling against the current at one of the points.
Why is this so? How does this mild-mannered lee shore transform at times into a surf machine of unparalleled duration?
Other east facing-coastlines: Brazil, the US from Florida north to Maine, South Africa, New Zealand, don't get the same payload. Their swell events are much more discreet and sporadic; sometimes dynamic yet equally fleeting and short-llived.
The short answer is that you need a few things need to come together; you need an anvil and you need a hammer.
The longer answer? Well, here goes...
Our anvil comes in the form of the high pressure belt which helps to equalise the movement of warm air towards the poles. Individual high pressure cells can become extremely slow moving as they enter the Tasman Sea and become almost stationary as they straddle New Zealand. Sydney surfers may fantasise about removing New Zealand so they receive more east swell, yet under these atmospheric conditions the very presence of the Land of the Long White Cloud benefits surfers from the Mid North Coast to Noosa.
The pressure force along the top of the high is often enhanced by areas of low pressure which form along the western edge of the West Pacific Warm Pool. This is our hammer. The West Pacific Warm Pool bleeds into the South Pacific Convergence Zone (SPCZ), creating a vast area of warm water, unstable air, and enhanced low pressure development focussed around our near island neighbours in New Caledonia, Vanautu, Fiji, and Tonga.
We know that during La Niña years stronger than usual tradewinds pile up warm water in the western Pacific. Another effect is that the SPCZ is pushed south-westwards, towards the East Coast swell window. From there, the warm water further enhances instability as it rises, carrying water vapour aloft.
In layman's terms: During La Niña years, there's more low pressure development, from simple easterly dips, to troughs, to low pressure depressions and tropical cyclones. And best of all, it's happening deeper into our swell window.
When the hammer of warm water and unstable air, meets the anvil of a large, creeping high pressure system, the result is a slowly building pressure gradient and a deep easterly fetch aimed directly at the coastline from Noosa to Nambucca. Such a system can last for days, weeks even, as reinforcing high pressure cells can move in without the overall pattern breaking down.
With our current knowledge and access to data we can see the resulting swell cycles aren't one single swell, as is sometimes reported, but instead a series of overlapping swells.
In our recent case, which started back on the Easter long weekend, a pair of lows in the Northern Tasman drifted between Lord Howe and Norfolk Islands, followed by a strong blast from the south. Those were the tasty entrees. If that's all it was, then we would've had a few days of great waves and called it another good Easter. However, before it dropped a classic blocking pattern established itself with a long trough, that extended from up near Vanuatu, positioned in place as, underneath it, a succession of monster highs moved in from the Bight.
The cherry on the pie was a broad tropical low which formed near New Caledonia and took the inside track to break the blocking pattern while spraying the entire East Coast with quality groundswell.
Modern technology greatly assists our understanding of these systems. You see, each individual snapshot - think of the old black and white weather map in the newspaper - of the blocking pattern looks underwhelming. It betrays one of the key features of how these events generate such quality surf.
Unlike so many other ocean basins, it's not the windspeeds which are the key ingredient, but the duration. The continuing wind, blowing in the same direction, at the same strength, even if not particularly strong, leads to a 'fully developed sea state'. That is, the windfield reaches its theoretical maximum amount of wave energy.
So, looked at in snapshot these fetches reveal nothing amazing in terms of size and quality. Yet when viewed in an animated wave model, keen-eyed weather watchers will note the sheer persistence of the weather system; how it stays in place as systems around it come and go.
Once a fully developed sea state is achieved double-overhead vortexes behind the rock at Snapper become a reality. These fully developed sea state swells also have an incredible consistency which marks them out from longer range groundswells. The contrast between the sub-tropical East Coast and Australia's southern states is stark. Rather than delivering high period yet inconsistent sets, we see an endless conveyor belt of waves pinwheeling down the points with no relent.
Even so, swells of such unremarkable periods - 8-10 seconds is typical, 11-12 is substantial - still seem to over-perform across the sub-tropical points.
That mystery is solved below the surface. Bathymetry is altered on a seasonal basis by the arrival of vast quantities of sand carried by longshore transport mostly in the near-shore zone. This sand - mostly fine-grained quartz - moves in slugs, and its most mobile during swell events.
No-one yet, neither man nor Mother Nature, has developed a superior base material for generating perfect waves. The sand moves north along the coast then rounds the many protruding headlands, filling the lee side bays. Once the rocky irregularities are filled in, excess sand is groomed by prevailing currents and the resulting hard-packed substrate creates an incredible inducement for incoming swells to break in a hollow and perfect fashion. It forms, even in lower period swells, what George Greenough calls “bottom tension”, an intangible but importance characteristic of the way these sand bottom points create quality surf.
Data from the Tweed River Entrance Sand Bypassing Project (TRESBP) estimates the average sand transport to be around 500,000 cubic metres/year and the most active months for sand slugs is April and May. Which is just what we saw in the recent run of swells. Sand slugs being transported and laid down, from behind the rock at Snapper then all the way down the Superbank.
Comparisons with the last triple dip La Niña, back in '74-'76, are inevitable but likely now lost in the mists of time and myth-making from the pre-digital era. The famous 28 day swell of 1975 is impossible to find hard data on. In fact, the most tuned in map watcher I know, Thornton Fallander, swore blind to me it was in 1974.
1978 World Champion Wayne 'Rabbit' Bartholomew, in his youthful prime at the time, places the event at April 1975 and ascribes the 28 day swell to, "a very slow moving low pressure system crawling along about 1,500 kms out in the South Pacific between Noumea and the North Island."
"It was stationary for days at a time," says Rabbit, "most likely held in place by a series of high pressure systems ridging from the Great Australian Bight”.
Which sounds fair enough, even if experience tells us the single swell was most likely a series of over-lapping pulses.
We know when the ENSO cycle tilts towards La Niña and the sand stacks up on the points, the swell can seem endless. We also know that what goes up must come down, and that periods of wave drought will inevitably follow the good times.
// STEVE SHEARER
Cheers Steve. Your words are, as ever, a gift
Was it an old Chris Bystrom film that stated Kirra broke for 7 weeks straight in I think 1986? Any records or comments on that from the old crew? I was a 14 yo grom and recall the summer into Easter was the best I can remember.
Mates and i from Broken back in the day often use "...was it '86 good?" as a benchmark.
Never went up the Goldie, didn't have to, but i imagine it applied up there.
A few will remember the SW Byron/Lenno spread.
Yeah rooney the banks at lennox were all time all winter in 86........it couldnt get any better
Surf into summer , billabong video mentioned it , circa86
"Boys in Barrels" 1986 Lennox surf video was a good record by Mr Curtis
fabulous and educational wrap of a very special recent weather event. thank you!
You lucky, lucky barstards.
Those photos of Mick / Dylan Graves have me dreaming, wishing, wanting....
Great reading. Numbers (swell period, etc.) never tell the full story of a swell...and I don't think it's just bathymetry... although I guess that does get primed by the duration/consistency of the swell? Had plenty of days with similar numbers be un-noteworthy.
Great article. As an old gold coast surfer I don't miss it, generally due to the crowds. I do miss that water colour though! I definately didn't appreciate it when I was there.
Interesting to learn how the low period swells over perform at the point breaks. Where I live now 10 seconds is dogshit. 12 is the bare minimum and 13 to 20 seconds is the happy zone, with the longer period better than lower. Although long period swells often overwhelm the beach breaks, another big plus for the east coast of Oz. It has it all! Good and bad!
Sure was a fun run of swell. Been a couple of years where there has always seemed to be something to look forward to in the forecast model runs. Always something brewing in that 10 window. Sure, sometimes the forecast has been pushed out but it's generally eventuated. You know that worm is going to turn eventually, and we'll be poring over the model runs looking for any glimmer of hope. With a potential el Nino being forecast, that will probably be our future come late winter.
My way of thinking, I’d classify rock or reef as a superior base for creating perfect waves. Just a thought.
Too often irregular and takes far too long for erosion to fashion it into good shaped waves.
Sure, there are stretches of coast where the bedrock is ideally angled to create good waves - think Jervis Bay to Bawley Point - but taking a worldwide perspective it just doesn't happen often enough.
However, if sand is available then it can fill all the irregularities and turn a sectiony sometime wave into something special.
Ah yeh, thanks Stu, can see where you’re coming from. Great write up Free.
"No-one yet, neither man nor Mother Nature, has developed a superior base material for generating perfect waves. The sand moves north along the coast then rounds the many protruding headlands, filling the lee side bays. Once the rocky irregularities are filled in, excess sand is groomed by prevailing currents and the resulting hard-packed substrate creates an incredible inducement for incoming swells to break in a hollow and perfect fashion. It forms, even in lower period swells, what George Greenough calls “bottom tension”, an intangible but importance characteristic of the way these sand bottom points create quality surf."
can you guys see this link?
North of brissy,
Keep it to yourself Carvin!!!!!
Haha! It's packed whenever it's on these days...Hasn't been a secret for decades
Awesome work FR. Thanks for the research you put in and your shared personal knowledge.
Just on bathymetry and period. I've often thought in comparing swell periods between Southern Ocean and Tasman/Pacific that the same period swells carry more power on the East Coast.
Anyone know if the bathymetry on the East Coast, particularly the Sydney coast, and nearshore further up the coast is generally deeper overall than the average depth of the ocean dropoffs along the southern coasts and if this would affect the power of the waves?
just to clarify: not the immediate nearshore dropoff but the zone 1to 5kms offshore as the swells approach.
Great article, far better than anything I’ve read about the 75 event.
Snapper is the aquatic equivalent to an LA Freeway. Literally unsurfable for most.
What happens if you get a longer period swell say 15 sec does it break even better?
Very rarely ever happens.
Nice write up Steve.
In 03 I was completing my last year of Uni in Dunedin. Smack in the middle of winter we had a high pressure system that was very thin (latitude wise) which extended most of the way to Chile and provided a trade wind swell that lasted a month. 2-5ft if E swell at the same 8-11sec period.
The swell that sticks out for me is the Pascha Bulker swell. I was living in the back hills of Lennox at the time and attending uni at Lismore. Each day I drove to uni the long way through east Ballina and for nearly a month straight I didn't make it to campus.
Maybe it's the rosy glow of nostalgia but I remember surfing so much that we wished for a break to recuperate. I failed every subject that semester but it was worth it. Truly excellent times
But that was a succession of ECL’s spinning of the east coast rather than this event.
I remember that year Sam it was pretty special 2020 was good too for the Ballina shire! Last couple of years have been a dud sth of broken, this autumn has started nicely!
2020 was sick, I seem to recall March through July pumped every day, 2-6ft, clean and good quality.
I think I pay 5 bucks a month for this. What a bargain.
why was no one surfing with jack free ??
With sand always moving North with longshore drift. Where does first stop of the train start and what keeps bring the sand passengers to that stop to begin their journery?
Conveyer belt swells only ever seem to hit Vicco beaches when your trying to surf a reform and it’s just too big. Wouldn’t get that at 3-4ft
Nice write up Steve. Over the last few years I've often said the weather has gone back to what it was like in the 70's!
If I may, I would have to add in my three and a half cents, that during La Nina there are less actual, purely tropical systems (as in barotropic, tropical cyclone) - and more baroclinic or hybrid lows that have a tropical origin.
La Nina does indeed move the ITCZ SW towards Australia partially due to enhanced easterly winds at the surface - but also splits the jet stream resulting in a stronger sub-tropical jet and a weaker polar/mid-latitude jet, making for less than favorable upper-level conditions (namely wind shear, though in some cases, can help to vent a storm via an outflow channel resulting in a stronger cyclone).
This split-jet also contributes to the incidence of blocking highs over NZ, as the split often happens over Australia, inland from the eastern seaboard, creating a 'hole' downstream - which favors upper and lower level ridging in the vicinity of New Zealand.
The upper level, northward-displaced jet will often feature jet-level troughs downstream of the Australian continent around the latitudes of central Queensland.
That, coupled with the moisture and instability of the SW placed ITCZ, results in the east coast low systems that are common during La Nina.
These, for the most part, aren't true tropical cyclones as they generally aren't purely convection driven and lean more towards being extra tropical systems, even from conception in the deeper tropics, mainly due to the presence of the Jet and any upper-level troughs.
Often they can be hybrid type systems with some central convective features, but also baroclinic (frontal) features too.
They seem to also be better swell producers when compared to true TC storms.
Another thing lacking for Tropical cyclone development in the SW basin during La Nina, events are westerly wind bursts coming off the Maritime Continent down into PNG and the northern Solomons, which truly ignite the ITCZ by inducing low-level vorticity (rotation) into the convergence zone which is a great kick starter for cyclone genesis.
For some reason the SW Pac is in a decades long Cyclone drought, perhaps some long-term cycle acting out to suppress formation.
We will see what next summer brings - but in the meantime, Viva La Nina, you will be missed!
Love your input.. thanks mate.
Rather than a decade of cyclone drought in the SW Pacific, isn’t the lack of cyclones related to Greenhouse Effect, in which case the “drought” may not change?
Great comments (esp Tane above), cheers all.
Winter 2007 was a benchmark for ECL's, starting with the Pasha Bulker swell.
Period is funny around here, you'll get long period energy from the S that doesn't often hit the Points well or suffers from period drag due to oblique angles of attack across the continental shelf.
It's rare to get a long period swell (15+) from the E-E/NE and if we get an event with size it's only a few spots will handle it.
So longer period is not automatically associated with better surf.
Don't those long period south swells feel the bottom earlier and refract in better?
There was a semi-legendary one a few years ago that snuck under the radar, ruler edge perfection - I think that one came from way down south of Tassie.
The swell you mentioned was April '75. It went down in history as 'the 23 day swell', because Tracks Magazine wrote it up as that plus pasted it on the front page in big letters. They stated that the swell stayed up and pumped for the first 23 days of April - the 23 days prior to them going to press on the 23rd. Fact is - when you look at the Sunshine Coast Wave Recorder Buoy Data for that period (1975 - 1977 data), it shows ANOTHER 2 WEEKS OF BIGGER SWELL carrying on afterwards from the 23rd.
For that data and decades of other Queensland swell height recordings, see.... https://www.publications.qld.gov.au/dataset/wave-data-recording-program/...
Note Figure 7, page 1 and 2 ... all of those wave height recordings.
I actually have all the Met Bureau weather charts for that period at home on the Sunny Coast. 10 years of Australian synoptic charts from September '72 to Sept '82. Interesting piecing together the swells with the synoptics.
Incidentally too - and with reference to those '70's cyclones and that period, we have super 8 footage of a 1975 Schoolboys contest in big surf at Alexandra Headlands. When it pans back along Maroochydore Beach, the entire beach is black coffee rock, almost no sand. Massive erosion. Many of those cyclones used to track close to the coast back then.
Thornton Fallander mentioned a 1974 swell. There was a massive one in May '74. A deep low pressure (maybe 976hp from memory) coming back in WEST towards Sydney from out at sea, and creating a massive 'squeeze' of wind off Sydney as it 'collided with a huge high pressure system moving in the opposite drection. Wave recorder buoys measured 40' off Sydney, and 15' inside Botany Bay. The SC Wave recorder buoy was knocked out of commision - as happened several times during huge swells and heavy seas.
If anyone has a subscription to TRACKS MAGAZINE, they are digitising and making available all of their old issues. Captivating reading. Captain Ron Ware used to write these phenomenally educational but fascinating ocean and wave science and maritime stories for Tracks back then. He wrote one up immediately after that May '74 storm. A wild story. See also the April or May '75 Tracks mag for that '23 day Burleigh swell story too.
Fascinating Jody re the 1975 footage and erosion shown. Will have to check out the data.
Hahaha, classic, the 23 day until deadline swell.
Jeff Callaghan has a treasure trove of knowledge about severe weather in the 70's as well.
That first photo of Mick by Andrew Shield says it all - fantastic photo! What is it, 2 feet deep just under the nose of his board, the rock in the background and it all has Micks full attention!