Nias, Mentawai, South Sumatra forecast by Craig Brokensha (issued Tuesday 30th Jun)

Best Days: Every day over the coming period (smaller and limited options Friday and Saturday morning)

This week and next week (Jul 1 – Jul 10)

What an incredible run of very large, pumping surf across the region. This morning the surf was still solid at exposed spots but on the ease.

Over the coming days we'll see the swell continue to ease, dropping back from an inconsistent 5-6ft at exposed breaks around the Ments tomorrow and further down from 4-5ft Thursday morning. Smaller surf again is then due into Friday.

S/SE winds are due to increase slightly tomorrow and freshen more into Thursday and Friday before easing back into Saturday afternoon and becoming more variable next week. South Sumatra will see fresher SE winds, easing back from the E/SE into next week.

Our next increase in noticeable swell is due over the weekend, that being an inconsistent pulse of S/SW groundswell generated the last couple of days by a small fetch of severe-gale W/SW winds just east of Heard Island, pushing towards WA.

This is on the edge of our swell window and only due to pulse later Saturday and peak Sunday to an infrequent but good 4-5ft+ across exposed south facing breaks around the Ments. Larger and more frequent 6ft sets are due in Southern Sumatra.

This swell should ease back into Monday afternoon, with a secondary similar sized pulse due Tuesday morning.

Of greater importance is a new strong node (peak) of the Long Wave Trough moving in through the Indian Ocean later this week and through the weekend.

This will direct a strong polar frontal progression up from south-east of South Africa, into the middle of the Indian Ocean and then across to WA.

With this we should see a large S/SW groundswell generated for Thursday next week that looks at this stage to be in the 10ft range. We'll have a closer look at this in Thursday's update though.

16 day Mentawai forecast graph
16 day Nias forecast graph
16 day South Sumatra forecast graph