Outlook: September surge in the Indian/Southern Ocean

  • South Indian Ocean storm track active, despite spring
  • Successive mid-latitude troughs have deepened over southeast India this week
  • Long SSW / SW / WSW lights up the coasts from India to New Zealand
  • Intervention runs until late September and early October

Outlook associated with this Outlook: Bali | Mentawi | southwest | SPA North Coast | south coast | surf coast


May our minds be in the spring now, But if you look to the southwest of the continent, you will definitely think that it was in the depths of winter. The Southern Indian Ocean is coming back to life. Over the next week, a series of Southern Ocean storms will unfurl from under a stubborn high pressure system docked over the central Indian Ocean.

As each storm moves east from the Kerguelen Islands, high bombers blast them from east to northeast along its eastern side, guiding them down Indonesia and Western Australia. Large SW swell development is aimed primarily at Western Australia and Indonesia, but swollen coverage will be extensive, and include the southern states of South Australia, Victoria, Tasmania – and eventually New Zealand.

Above: Animation of the 168-hour swelling period from Lotus. Rather than showing raw volume, this graph shows the longer period swelling before the main bulge body as storms cross the eastern half of the southern Indian Ocean and move south of Australia, swelling fans across the southern Indian coasts.

Wind chart for Tuesday, September 20. The energy in this storm runs roughly along latitudes, from west to east, but is getting closer to the southwest as it approaches Australia.

Indonesia: Peak endo surf season statistically occurs in the southern hemi winter, but high season surf often spills over into the transition months – and that’s what happens now. The first round of a long-term SSW wave hit the bottom on Thursday, closely followed by a series of consolidating impulses that will gradually taper off again this weekend, with more to come next week. A pattern of calm early winds tending to light moderate E/SE trades supports excellent late season surfing throughout.

Western Australia: The Southwest is feeling the full brunt of the stormy WSW, SW and WSW and fresh onshore winds. A brief respite in the wild system opens a short window of opportunity on Thursday, before closing in as the Northwest rebounds on Friday. To the north, conditions will vary but winds in general will remain from southeast to east, with a lot of swell.

South Australia: A series of cut-bottoms developing below Bight brings bouts of strong onshore winds and a large, locally generated SW bulge above the underlying WSW crest. A window of good to great conditions may open as high pressure regulations change over the state this weekend.

Victoria: The southeast low slip, past Tasmania, may bring favorable winds to the state as the first round of the WSW long wave arrives on Thursday and early Friday. With the second and third pulses overlapping into the weekend, fresh onshore winds are set to hamper quality on Friday afternoon and most Saturdays, shortly before northern regions open up good potential on Sunday.

Above and Below: A Little Victoria Moment Coming Here. Wind chart and swell chart for next Friday, September 23 at 10am – sea light along the surf coast before the introduction…

…and amplified enough to beat the not-to-perfect WSW long span angle. Big long weekend ahead.

Keep an eye on this Outlook for updates as these storms and local conditions evolve.

Leave a Comment

Your email address will not be published.