Will This South Pacific Swell be Bigger Than 2015?

Ben Freeston

by on

Updated 1215d ago

On May 3rd last year Mark Healey stroked into a Puerto Escondido beast that many considered the largest wave ever paddled. With charts lighting up for next week, headline numbers look similar or even bigger, so how does this one stack up?

Comparing last years historic swell with this next pulse

Comparing last years historic swell with this next pulse

© 2019 - MSW

The picture tells the story. This swell coming is powerful and well positioned to send energy north, but it's just not the beast that last year was. So why does it build numbers for Puerto Escondido that, at a latest 10ft@19 seconds, beat last year's forecast 8.5ft@19 seconds? It looks like it's that leading edge of the swell, marked on the chart above, and actually from the first of the two low pressure systems. As waves propagate away from the storm the longer period energy travels faster. It's this that means the long periods arrive first and the period decreases throughout the swell event. From our data it appears here that leading edge, from the first swell and slightly smaller and lower period, makes it to the beach at Puerto Escondido at about the same time as the bulk of the long period from the second pulse starts to fill in. While this does lead, legitimately, to a forecast of 10ft, at a peak period of 19, seconds the reality is that a large component of the overall size is from swell nearer 16 seconds in period.

Energy in this swell by period at peak on 24th June 2016

Energy in this swell by period at peak on 24th June 2016

© 2019 - MSW

The effect? To be brutally honest it's hard to know for sure. Without detailed nearshore modelling, which requires detailed nearshore bathymetry not currently available, we have to speculate from experience. Puerto Escondido responds well to long period energy and generally as we transition into the surf zone we find swells with a stronger peak of energy at a single period, tend to make larger surfable waves. As such this event looks likely to come in shy of last year for size despite those headline numbers. There are some further caveats anyway:

  • The swell has a more westerly direction which can be problematic at Puerto Escondido, regardless of size. Although expectation is that this swell is in a reasonable range
  • Last year's swell was mostly not ridden at peak, slightly smaller overall could still mean more giant ridable waves.
  • We're comparing forecast to forecast in the absence of local wave buoy readings and there might be some degree of error in the forecast numbers.
  • This swell has a much narrower directional spread compared to last year. Again it's hard to know exactly how this will manifest on the beach.

Whatever the detail the entire west coast of the Americas is due a significant swell event and Big Wave World Tour organisers are no doubt trying to work out how to make the most of this event given likely XXL conditions at several stops.

* Cover image Mark Healey 2015 © WSL / Nikki Brooks