Swell Alert: WA, Victoria and South Australia receive heavy SW groundswell this weekend and early next week

26 Oct 2017 0 Share

Ben Macartney

Chief Surf Forecaster

COASTALWATCH PLUS EXCLUSIVE | SWELL ALERT

Issued Thursday, October 26, 2017

The southern hemisphere’s relative absence of landmass compared to the northern half of the globe has major implications when it comes to swell formation and propagation around Australia. The virtually uninterrupted expanse of the Southern Ocean encompasses over 20 million square kilometres of open ocean, allowing for polar storm-genesis in perpetuity; a never-ending succession of fronts and lows marching west to east, regularly extending vigorous cold fronts across the southern Australian states as they extend north into the mid-latitudes. The point is, Australia gets solid surf year-round – admittedly nowhere near as consistent in the warmer months – but it means a major swell-event is a possibility at anytime of year.

Victoria's Surf Coast looks like the best place to capitalise on the swell's arrival early next week. Photo: Sloane.

Victoria's Surf Coast looks like the best place to capitalise on the swell's arrival early next week. Photo: Sloane.

And that’s exactly what’s about to happen across the Southern States. The evolution of a deep mid-latitude low below the mainland this weekend brings a vast area of WSW/ SW gales up into the Great Australian Bight; initially whipping up heavy SSW groundswell for Western Australia on Sunday before generating a similarly large WSW pulse for South Australian and Victorian coasts on Monday and Tuesday.

Latest Wave Tracker model runs show peak wave growth exceeding 40ft below the mainland on Sunday spawning heavy WSW groundswell for SA and Victoria on Monday and Tuesday.

Latest Wave Tracker model runs show peak wave growth exceeding 40ft below the mainland on Sunday spawning heavy WSW groundswell for SA and Victoria on Monday and Tuesday.

Western Australia
A heavy rise in extra-large SSW groundswell is expected to show building wave heights into Sunday, peaking within the 12-15ft+ range across exposed south-west coasts. A fresh ridge of high pressure sets up behind the system bringing with it easing SSW tending S’ly winds. With this combo we should see some pumping surf within sheltered bays and points, improving into the day. On Monday the large high pressure system sets up favourably across the state. Light, variable winds are currently expected across the South West, grading straighter offshore Perth, Mandurah. Easing levels of large SSW groundswell show throughout the day. We may see some unsettled wonk across exposed beaches down south making semi protected and sheltered bays your better options.

This Wave Tracker image depicts signficant wave height, showing large, refracted SSW swell spreading north along the West Coast as the main body of seas and swell propagates eastward below the Bight on Sunday.

This Wave Tracker image depicts signficant wave height, showing large, refracted SSW swell spreading north along the West Coast as the main body of seas and swell propagates eastward below the Bight on Sunday.

Victoria
A leading pulse of mid-period WSW groundswell showing across exposed beaches on Sunday offers up a good window of opportunity for some clean, solid surf before the swell arrives on Monday morning. Expect already heavy and out of control 6 to 8ft plus surf along the exposed beaches, rising into the 8 to 10ft realm as the day progresses. That leaves the Surf Coast as probably the best region for capitalising on this event. Although the westerly angle will inhibit wave refraction, resulting in less size and consistency, expect set waves to build into the 6 to 8ft range during Monday, with larger freak sets likely across the premier breaks throughout the afternoon. Conditions are likely to be excellent throughout Monday morning under fresh WNW winds – and they should still stay rideable, albeit more challenging as winds swing WSW as the swell peaks into the afternoon. Tuesday morning may prove the best window for still large and better quality sets in the 5 to 8ft range, with lighter WNW winds giving way to seabreezes as the swell begins to ease into the afternoon.

The same 30ft deepwater WSW groundswell arrives at similarly long intervals across Victoria during Monday, showing peak size throughout the afternoon.

The same 30ft deepwater WSW groundswell arrives at similarly long intervals across Victoria during Monday, showing peak size throughout the afternoon.

South Australia
Size will be slightly hindered on the south coast due to the westerly bias in swell direction. Although due to the pure size and power of this potential swell event, there remains scope for refracted energy to show within the 6-8ft+ range, largest at focal magnets. Due to the west angle there will be no shortage of swell pushing into The Gulf with large and semi stormy surf expected. Expect a variety of options from some maxing conditions across the Mid Coast to some novelty surf at select locations. Surface conditions show messy early under strong onshore west tending WSW winds, easing into the afternoon. Wave heights slowly ease overnight and into Tuesday morning. As the low shifts further east a developing ridge of high pressure sets up across the region. A second weaker low pushes up from the south. With this combo we expect to see a lighter W’ly airflow, thus making for potentially cleaner conditions across semi sheltered South Coast breaks.

This Wave Tracker image depicts peak wave period, showing the leading edge of the groundswell arriving at peak intervals of 16 seconds on Monday morning, leading in the bulk of a deepwater WSW groundswell in the 30ft range offshore.

This Wave Tracker image depicts peak wave period, showing the leading edge of the groundswell arriving at peak intervals of 16 seconds on Monday morning, leading in the bulk of a deepwater WSW groundswell in the 30ft range offshore.


Tags: Ben , Macartney , Swell , Alert , Victoria , WA , SA (create Alert from these tags)

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