Indian Ocean Basin analysis by Craig Brokensha (issued Tuesday 18th March)

This week through next (Mar 19 - 28)

Following a good pulse of S/SW groundswell yesterday and this morning, the trend will be down into tomorrow morning, with the easing trend slowed only slightly into the late afternoon and Thursday morning thanks to a smaller, less consistent reinforcing S/SW groundswell filling in.

Winds will shift more westerly over the coming week thanks to a monsoonal surge south of Sumatra, with fresher W/NW tending W/SW breezes due until Friday, when more variable N’ly winds should take over.

The westerly winds look to move in later Sunday, persisting all of next week and bringing with them some low period W’ly swell that looks to be in the mix until at least next weekend.

Swell wise, a small, inconsistent S/SW groundswell is due later Friday and into Saturday morning, but the polar low linked to it formed late in our swell window and was aimed mostly east.

Sunday afternoon should reveal a better mid-period S/SW swell in the water, produced by a healthy polar fetch of strong W/SW winds currently south-west of Western Australia.

It’ll be moderate in size before slowly easing into Monday.

Otherwise, another strong but late forming low to the south-west of Western Australia should produce an acute S’ly groundswell for Tuesday next week, with the best swell of the period due to arrive next Thursday ahead of a peak into the afternoon.

This will be generated by a strong polar low forming south-east of South Africa and west of the Heard Island region tomorrow, with a great fetch of severe-gale W’ly winds likely to generate a moderate + sized groundswell. We’ll confirm this on Thursday.

In the Mentawais, the main issue will be the tropical activity bringing poor, strong winds out of the north-western quadrant this week, with southern locations most affected and more variable winds due across northern regions.

Winds should start easing on the weekend while shifting more westerly, though persisting from the W/NW into next week, limiting the best waves to protected south-eastern corners.

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Maldives:

Last week’s SE trade-swell event is on the decline across the region thanks to the relaxation of swell generating E/SE-SE winds through the Indian Ocean.

This will continue to be the case throughout the period, though the tropical activity south of Sumatra later this week may produce a new pulse of SE energy for Sunday/Monday though to major size.

Otherwise a good S/SW groundswell in the water today will ease through the afternoon and tomorrow, ahead of a new, inconsistent S/SW groundswell Thursday afternoon/Friday.

Ex-tropical Cyclone Jude which is currently south-east of Madagascar should produce some new S’ly groundswell for later Sunday and Monday morning but only moderate in size.

The strong polar low forming south-east of South Africa should produce a small S/SW groundswell for the middle of next week, though we’ll confirm this next update.

Local winds look favourable for the southern atolls and light out of the N/NW for the most part with periods of E’ly breezes across central and northern regions (namely Thursday/Friday).

Eastern Indonesia:

Easing S/SW groundswell over the coming days, slowed by a smaller reinforcing pulse later tomorrow and Thursday morning.

Small to moderate sized, inconsistent S/SW swell for later Friday and Saturday morning to 4ft+.

Moderate sized mid-period S/SW swell building Sunday to 4-5ft across exposed breaks, easing slowly Monday.

Small inconsistent S’ly groundswell for next Tuesday to 3-5ft, easing Wednesday.

Moderate + sized, inconsistent S/SW groundswell building next Thursday reaching 6ft across exposed breaks, easing slowly Friday.

Moderate to fresh W/NW tending W/SW winds over the coming days, tending more variable N on Friday and Saturday.

Strengthening W/NW-W winds from later Sunday with some localised W swell also in the mix next week.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Mix of background S/SW-SW groundswells over the coming days to 4-5ft across exposed breaks, easing from Friday.

Small, inconsistent mid-period S/SW swell for Monday to 4-5ft across exposed breaks, with a similar sized, reinforcing swell Tuesday.

Moderate + sized, inconsistent S/SW groundswell building later next Wednesday, peaking Thursday and reaching 6ft across exposed breaks, easing slowly Friday.

Strong NW winds across southern locations this week, easing a little and tending more W on the weekend, persisting from the W/NW next week. More variable winds across northern locations.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Slowly easing SE trade-swell over the coming week ahead of small bumpy to 3ft across exposed breaks Sunday afternoon and Monday.

Moderate sized S/SW groundswell easing today, with a reinforcing pulse for Thursday afternoon and Friday to 4ft on the southern atolls.

Moderate sized, inconsistent S’ly groundswell building Sunday, reaching 4ft across the southern atolls late, easing from a similar size Monday.

Small to moderate sized, inconsistent S/SW groundswell building Wednesday to 3-4ft across the southern atolls, easing slowly Thursday.

Light N/NW winds this period across southern regions, more variable to the north and in central locations before tending E Thursday/Friday and E/NE next week but without much strength.