Indian Ocean basin analysis by Craig Brokensha (issued Tuesday 22nd June)

This week through the coming fornight (Jun 23 – Jul 7)

The current storm track is focussed either side of the Indian Ocean Basin, that being a strong frontal progression sliding under South Africa and Madagascar, along with a weaker, more north-south aligned progression pushing up and into Western Australia.

These will be the main sources of swell for the Indonesian archipelago through the coming week, while a low sitting plum in the middle of the Indian Ocean has produced a fetch of strong to gale-force S/SE winds, generating a moderate sized mid-period S/SE swell.

While the progression off South Africa is strongest, it is coming from the furthest away, resulting in a greater loss in swell energy and consistency, though coming in from a south-west direction. The storm off Western Australia will be lower in period but more consistent and also bigger across Java and eastern Indonesia, though coming more from the south.

The mid-period S'ly swell should peak through Monday, with the long-range SW groundswell arriving later Tuesday but peaking through Wednesday/Thursday.

The S/SE swell aimed at the Maldives is expected to arrive later Saturday across the southern atolls and peak Sunday.

The southern Maldives will see S'ly groundswell spreading up radially off the fetch under South Africa and Madagascar, arriving later Monday and peaking through Tuesday/Wednesday. A reinforcing pulse of better aligned mid-period S'ly swell is due Thursday generated by a fetch of S/SW gales wrapping up behind the initial progression and this looks to provide the most size across the southern atolls.

Following the frontal activity on either side of the Indian Ocean basin, a trough squeezing against a strong high off the Western Australian coast is expected to produce a small to moderate sized S/SE swell that will come in more S'th across eastern Indonesian locations, arriving later next weeke but persisting into the following weekend.

Longer term the next swell episode looks to arrive later next week, but we'll look at this in the following update.

Eastern Indonesia (Bali/East Java):

Small mid-period S/SW swell building Saturday, easing Sunday from 4ft on the exposed breaks. Moderate sized + mid-period S'ly swell for Monday to 5-6ft across exposed breaks, easing into Tuesday, further Wednesday.

Weak trade-winds on the weekend, with variable breezes with a trough Monday, ahead of stronger SE trades mid-late week onwards.

Inconsistent SW groundswell signal building later Tuesday afternoon, peaking Wednesday/Thursday to 3ft to occasionally 4ft across exposed breaks.

Mid-period S/SE-S swell for next Friday/Saturday/Sunday to the 4ft range.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia (Mentawais/South Sumatra):

Small mix of swells for the end of the week with variable winds.

Inconsistent background SW groundswell for later Sunday, peaking Monday in the 4ft range. Mid-period S'ly swell building Monday afternoon, peaking Tuesday to 3ft.

Inconsistent SW groundswell building Tuesday afternoon, peaking Wednesday/Thursday to 4-6ft across exposed breaks, easing Friday.

Moderate sized mid-period S/SE swell for Thursday/Friday to 4-5ft.

Variable winds over the coming days, freshening from the SE-S/SE across southern locations from Tuesday.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Moderate sized S/SE swell for Sunday (arriving later Saturday southern atolls), peaking to 4-5ft in the south, 3ft to the north.

Inconsistent S'ly groundswell building later Monday, peaking Tuesday with a reinforcing pulse Thursday.

Sets in the 4ft range across the southern atolls, a touch stronger Thursday and to 4-5ft.

Winds will be gusty out of the western quadrant, shifting more south-west through Sunday/early next week and persisting thanks to the strengthening Indian monsoon which has been delayed this year. Winds might shift south-east across the southern atolls later next week but we'll keep an eye on this.