Forecast: Thundering Cloudbreak
It’s not just Hawaii’s position in the middle of the North Pacific that guarantees it big swell all winter. It’s also assisted by a conveyor belt of cold air coming off the Siberian Shield mixing with the warm water of the Japan Current that establishes a constant supply of storms that stall in the northwest Pacific, deepen, and then aim long-period swell towards Hawaii.
There’s much more ocean in the southern hemisphere, more room for storms to develop, however without land masses to influence the low pressure systems, the storms tend to be more diffuse; they can form anywhere within the band called the Roaring Forties - and that’s a lot of ocean.
It’s why surf forecasters look for other features that influence low pressure systems. It helps them anticipate how they’ll behave.
Most recently, the Long Wave Trough (LWT) has been the key to predicting storms in the southern hemisphere. When the LWT is in position it can direct swell towards a coastline much the same way that Hawaiian storms are cultivated.
Of course, unlike land masses, the LWT is always moving so it’s only periodical, however it explains why swells often happen in ‘clusters’ in the southern hemisphere. If one storm follows the LWT then the subsequent storms will too.
One of those clusters is happening right now below Australia and the swells being created will be of Hawaiian proportions.
Kohl Christenson, Hawaiian size, South Pacific perfection (Stu Gibson)
For the last week a node of the LWT has been aimed up the Tasman Sea, meaning any available low pressure systems have followed that trajectory. And, as it happens, there’s been many available lows so every exposed coastline from eastern Australia, to New Caledonia, Fiji, and the west coast of NZ has been fixed to a south swell regime.
The last week saw three separate spikes of swell move up the Tasman Sea hitting Cloudbreak between 6-10 feet. Although each swell was relatively strong they were hampered for various reasons, either forming too far west and being shadowed by Tasmania, or too far east and partially blocked by NZ, or the storm weakened as it moved up the Tasman.
Andrew Jacobson at Cloudbreak yesterday
At any rate, it’s all so many lemons against the pie that will be Cloudbreak this weekend.
Over the last two days, two very large storms have been skirting the polar ice shelf below Australia and the first has now begun tracing the LWT path which currently lies dead centre of the Tasman Sea, meaning the storm won’t be obstructed by Tassie or NZ (see following image).
At present, surface winds of 40knts are blowing over 2,000 kms of ocean with the intensity expected to last another 24 hours as the front projects high into the Tasman. It’s then due to hit Fiji Friday afternoon, pushing towards 12 feet+ by dark and easing from 10-12 feet Saturday morning. Winds will be light SE trades as Fiji enjoys a low ebb in the tradewind cycle.
Yet there’s more pie to come…
Late tomorrow the second low pressure system skirting the ice shelf will begin following the LWT corridor up the Tasman. It’s a similar size as the previous storm, similar position too, though it's of greater intensity. By Wednesday morning, surface winds of 50knts will be blowing over 2,000 kms of ocean with smaller tracts of 55knts - all aimed northeast towards Fiji.
Much like the previous system, these winds will endure as the storm moves up the Tasman creating a captured fetch scenario compounding swell height. The second system will also be assisted by an active sea state created by the passing of the preceding storm.
So then, size? Whew...thought you’d never ask.
All the elements are in place for a very memorable swell: a broad system of high intensity and long duration taking true aim at Fiji. There’s nothing to warrant being overly cautious (natural caution always being assumed) so I’d expect sets either side of 15 feet to begin hitting Cloudbreak late on Sunday, with a levelling out around 12-15 feet on Monday morning.
The early approach of this swell matches other significant Fijian swells of recent times: the Scardy swell of 2010, Kohl Christenson swell 2011, Volcom Pro 2012, and Aaron Gold’s flatline swell of 2016. In fact, the latter was beset by strong trades while on Sunday afternoon the trades should lay right down due to a passing trough. By Monday morning light SE trades will again blow.
By next week the LWT will shift east meaning low pressure systems wont be steered up the Tasman, thus ending the cluster of Hawaiian-like swells for the Fijian reefs.