Indian Ocean Basin analysis by Craig Brokensha (issued Thursday 29th May)

This week through next (May 30 - Jun 6)

Locations west of Bali should be seeing some inconsistent, flukey S/SE groundswell today, but this will be overridden tomorrow by a better, inconsistent SW groundswell that was generated by a strong and tight mid-latitude low that formed south-east of Madagascar late last week.

I feel it will come in better than the models indicate (satellite pass below is great), kicking strongly this afternoon across the Mentawais and western Indonesia, later and more so tomorrow in eastern Indonesia.

A peak is due through the day across eastern Indonesia, with some reinforcing mid-period S/SW swell energy from the secondary intensification of the low due through Saturday/Sunday morning, easing thereafter.

This reinforcing mid-period swell should be of similar size to the less consistent but stronger groundswell and more south in direction.

Monday’s long-range inconsistent SW groundswell is still on track with no expected change to the size, while of greater importance is a more consistent, larger SW groundswell due mid-week.

As touched on in Tuesday’s notes, the source will be a strong, tight mid-latitude low forming west of Western Australia Friday evening, with it being slow moving while generating a fetch of severe-gale S/SW winds towards us, possibly storm-force briefly at its core.

What I like about the low is the strength and slow movement but the tight nature may limit the size reaching a true 8-10ft, with it instead coming more around the consistent 8ft range Wednesday.

With the low only slowly weakening while slowly shifting east, the size should hold into Thursday morning as the swell drops in period, and shifts more S/SW in direction, steadily dropping from Friday.

Longer term, a flurry of strong but distant frontal activity to the south of South Africa, slowly moving east through the weekend will generate some good, long-range SW groundswell energy but it looks to only be moderate + in size at this stage. 

The best pulse of energy looks to build through Sunday week, peaking the following Monday but check back Tuesday for more details.

The current variable winds are expected to remain so tomorrow morning ahead of slowly increasing SE trades, fresher E/SE from the weekend, tending variable again from Tuesday next week. With this more N’ly morning breezes are due ahead of weak sea breezes from Tuesday.

For the Mentawais, the SW energy on the build today should get large late, holding tomorrow morning before easing slowly into the weekend.

The mid-latitude low generating the large SW groundswell for eastern Indonesia will come in a bit more south and a touch smaller across the Mentawais though 8ft sets are still expected, easing into the end of the week/weekend.

The SW groundswell though for next weekend should come in larger across the region with Sunday being the largest at this stage.

Our variable winds are expected to shift slightly SE across southern regions tomorrow but more so the weekend, easing off again into next week and going variable.

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Maldives:

We’ve got easing levels of strong S’ly groundswell from yesterday and smaller background SE trade energy, with the next pulse of energy for both regions arriving tomorrow afternoon out of the S’th.

This will be a moderate sized mid-period S’ly trade-swell from an intensification of strong SE winds, south of us earlier this week, building tomorrow afternoon, peaking Saturday morning.

A slight relaxing of the trade fetch today will see the swell ease through Saturday afternoon and Sunday, but from Monday, the next pulse of S/SE energy is due as winds strengthen south of us through the weekend.

This will be actually attached to the mid-latitude low forming west of Western Australia, with moderate levels of S/SE trade-swell due to swing more SE through next week as the fetch slowly expands east, while the low itself may generate an additional, larger pulse of S/SE groundswell for Wednesday afternoon and Thursday morning.

Otherwise, the strong activity south of South Africa on the weekend looks to generate some moderate + sized S/SW groundswell for late next week/weekend, but more on this Tuesday.

Our strong W/SW-SW winds (weaker S’ly across southern regions) are expected to persist tomorrow, easing slowly Saturday but more so Sunday. They look to remain fresh early-mid next week from the W/SW-SW across all locations before possibly easing and tending more W/NW late week.

Eastern Indonesia:

Flukey, moderate sized S’ly groundswell for Java today.

Moderate + sized, inconsistent SW groundswell building later today, peaking tomorrow to an inconsistent 6ft across exposed breaks during the day.

Reinforcing S/SW swell to a similar size on Saturday, and early Sunday, then easing.

Inconsistent, moderate sized SW groundswell Monday to 4-6ft across exposed breaks, easing Tuesday.

Larger SW groundswell Wednesday to 8ft across exposed breaks, easing slowly from 8ft Thursday morning while tending more S/SW in direction.

Moderate + sized, inconsistent SW groundswell building slowly Saturday week but more so Sunday afternoon and into Monday morning to 5-6ft across exposed breaks.

Variable winds tomorrow morning, SE into the afternoon with freshening E/SE winds on the weekend (variable each morning). Variable N winds developing from Tuesday through Thursday with weak afternoon sea breezes.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Large SW groundswell building today, possibly reaching 6-8ft later, peaking tomorrow to 6-8ft across exposed breaks, easing slowly into the weekend.

Moderate + sized, inconsistent SW groundswell for Monday to the 6ft range across exposed breaks.

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

Moderate to large, inconsistent SW groundswell building next Saturday, peaking Sunday to 6ft+ across exposed breaks.

Variable winds, with weak SE breezes developing across southern locations tomorrow, holding through the weekend, variable into next week.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Moderate sized, mid-period S’ly swell building tomorrow afternoon, peaking Saturday morning to 4-5ft+ across the southern atolls (smaller Male), easing into the afternoon. 

Moderate + sized mid-period S/SE swell for most of next week, tending SE later week. Size peaking from Tuesday to 4-5ft across the southern atolls, 4ft to the north.

Stronger S/SE groundswell for later Wednesday and Thursday morning to 6ft+ across the southern atolls, 4-5ft+ to the north.

Good S/SW groundswell from later next week through the following weekend.

Strong W/SW-SW winds persisting tomorrow (weaker S’ly across southern regions) abating slowly Saturday but more so Sunday. Fresh W/SW-SW winds across all locations early-mid week before possibly easing and tending more W/NW late week.