Indian Ocean Basin analysis by Craig Brokensha (issued Tuesday 3rd June)

This week through next (Jun 4 - 13)

Our large swell seen through late last week started to ease into the weekend, with a new, long-range SW groundswell halting this trend yesterday.

We’re now seeing the surf ease ahead of our large, consistent SW groundswell due tomorrow.

Looking at the source of this groundswell, a strong mid-latitude formed west of Western Australia over the weekend, directing fetches of severe-gale to storm-force S/SW-SW winds towards Indonesia and the Maldives.

Satellite observations picked up the fetch well but the timing has been delayed a little, with the swell due to build through tomorrow, peaking later in the day before easing slowly Thursday.

The slow movement and longevity of the low will result in Thursday likely coming in a similar size to later tomorrow, though with more south in the direction and with less period.

The next increase in swell will be inconsistent, long-range SW energy, generated by a strong but distant frontal progression that took place under South Africa late last week and over the weekend.

An initial, moderate sized SW groundswell for Saturday afternoon and Sunday morning was generated by a tight, intense but short-lived low that fired up late last week, while a broader and more substantial frontal progression moving in behind it should generate a slightly larger SW groundswell for Sunday afternoon and Monday morning.

Sets should reach the large range, though be inconsistent, easing into early next week, though slowed by one final pulse of reinforcing energy Tuesday (under Sunday/Monday’s size)

The next increase in size is due Wednesday afternoon and Thursday morning, produced by a northward located but at this stage, not overly well structured mid-latitude frontal progression moving through this Thursday/Friday.

ECMWF has this system being much more substantial than GFS, bringing larger surf so we’ll have to review the outlook again on Thursday when we have more agreement.

Looking at the local winds and relatively weak E/SE-SE trades are expected to start freshening more into the weekend, becoming stronger next week.

In the Mentawais, the coming swell for tomorrow/Thursday will come in a bit more south while the SW groundswells for the weekend and early next week should have a bit more size compared to Bali.

Variable winds are expected this period, possibly freshening across southern locations from the SE later week. Check back Thursday regarding this.

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Maldives:

We should see moderate levels of S/SE trade-swell filling across the regions today, generated by a strengthening and expanding fetch of SE winds south of us.

This fetch is still south of us, maintaining similar sized surf through the rest of the week as the fetch holds until starting to weaken while tracking more east Thursday/Friday.

There’ll also be an inconsistent S/SE groundswell from the stronger low that formed west of Western Australia on the weekend, with this due to arrive later Wednesday but peak Thursday.

Thanks to the weakening trade winds later week, slowly easing levels of trade-swell are due through the weekend and into next week before possibly kicking again mid-late week.

Southerly groundswell wise, the activity south of South Africa should generate good pulses of moderate + sized swell from Friday through the weekend and early next week.

Our current lightish local winds will tip more W/NW through this week while remaining moderate in strength across northern and central locations, freshening over the weekend before strengthening further from the W/SW-SW next week, feeding into an active monsoon trough to our north-east.

Eastern Indonesia:

Large, consistent SW groundswell building tomorrow to 8ft across exposed breaks later, easing slowly from a similar size Thursday morning while tending more S/SW in direction.

Moderate sized, inconsistent SW groundswell building Saturday, peaking into the afternoon and Sunday morning to 4-5ft+.

Larger, inconsistent SW groundswell for Sunday afternoon more to 6ft across exposed breaks, similar Monday morning.

Easing trend slowed by a reinforcing SW groundswell Tuesday.

Large SW groundswell likely Wednesday afternoon/Thursday morning to 6-8ft.

Weak E/SE-SE trades for the coming days, freshening on the weekend and stronger next week (variable offshore each morning).

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Large S/SW peaking tomorrow to 8ft across exposed breaks, easing while tending more S’ly later week.

Moderate to large, inconsistent SW groundswell for later Friday but more so Saturday to 4-6ft.

Larger, SW groundswell, peaking Sunday to 6ft to occasionally 8ft across exposed breaks, easing slowly Monday, slowed by a reinforcing pulse into the afternoon.

Large SW groundswell likely next Wednesday to 6-8ft.

Variable winds this period, possibly freshening from the SE across southern locations late next week.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Moderate sized mid-period S/SE swell for most of this week to 3-5ft across central locations, bigger and to 4-5ft+ across the southern atolls.

Inconsistent S/SE groundswell Thursday morning to 5-6ft across southern atolls, smaller to the north.

Slowly easing S/SE trade-swell on the weekend and early next week.

Inconsistent moderate sized S/SW groundswell from Friday through early next week to 5ft on the southern atolls.

Moderate W/NW winds this week, freshening from the W through the weekend and stronger W/SW-SW next week (weaker to the south).