Nias, Mentawai, South Sumatra forecast by Craig Brokensha (issued Sunday 17th April)

Best Days: Monday, Tuesday, Thursday, spots out of the W/NW wind from Friday

This week and weekend (Apr 18 - 24)

Yesterday afternoon a good long-period S/SW groundswell started filling in across the islands, and this has peaked this morning in the good but inconsistent 6ft range across exposed breaks. Variable winds have created good clean conditions.

We'll see this swell start to ease back through this afternoon, further down through tomorrow and Tuesday (softened slightly by a new inconsistent S/SW swell) bottoming out Wednesday.

Variable winds should persist tomorrow and Tuesday before a weak S/SE'ly kicks in Wednesday.

From Thursday some good pulses of S/SW groundswell are due, produced by a series of strong polar frontal systems firing up west of Heard Island.

The first front produced a good fetch of gale to severe-gale W/SW winds, but the second system is a touch stronger and broader, producing a slightly larger swell. The final front will be smaller in scope but a bit more north in latitude helping produce a final similar sized S/SW pulse.

The first swell is due to fill in Thursday, offering good 4-5ft+ waves across exposed south facing breaks in the Ments, easing back into Friday.

The secondary stronger pulse should be seen late Saturday, peaking Sunday morning to 5-6ft, with the third pulse due later Monday and Tuesday morning to a similar size.

Winds are due to become variable again through Thursday, but less than ideal NW tending W/NW winds are then expected from Friday through until Monday next week as a small surface trough lingers off the region.

This trough should weaken into the middle of next week as the swell eases, resulting in more variable breezes.

Longer term there's still nothing major on the cards for the Mentawai region, but we'll have another look at this Tuesday.

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