Indian Ocean Basin analysis by Craig Brokensha (issued Tuesday 11th July)

This week through next week (Jul 12 - 21)

Following the regions recent run of large groundswells, we've got plenty more to come this period but with a bit of spacing between events.

Monday afternoon's pulse of inconsistent SW groundswell is now on the ease across all locations and we'll see wave heights steady in the moderate + size range through tomorrow ahead of a new pulse of large S/SW groundswell Thursday, peaking late in the day.

The source of this swell was a great fetch of severe-gale W/NW winds traversing the southern Indian Ocean on the weekend, with it favouring eastern Indonesia, coming in a little smaller though still strong across Western Indonesia.

The Maldives will see even smaller levels of swell spreading out, arriving Wednesday and peaking through the afternoon. There'll be more consistent, localised levels of SE trade-swell in the mix to a similar size that will be the main signal in that region.

Back to Indonesia, and the easing trend through the weekend and Monday looks to be slowed by some moderate sized, background swell energy.

The next noticeable increase is size is due next Wednesday/Thursday (19/20th), originating from a healthy frontal progression forming under South Africa this evening. A good fetch of pre-frontal gale to at times, severe-gale W/NW winds should move right across the Indian Ocean, helping generate a large groundswell that's due to peak later Wednesday before easing slowly Thursday across Indonesia. The Maldives should see this swell building through Monday but peaking Tuesday.

There's the chance for a reinforcing groundswell for Friday but the models diverge regarding this.

The Maldives may see a super-charged SE trade-swell event developing for late next week/weekend but we'll look at this next update.

Eastern Indonesia:

Slight drop in size tomorrow ahead of strong new S/SW groundswell building Thursday, peaking later to 8ft+ across exposed breaks, easing from the 8ft range Friday morning.

Slow easing trend into Saturday and Sunday, with a moderate sized, reinforcing mid-period SW swell for Monday to 4-5ft+ across exposed breaks. Large SW groundswell building Wednesday (19th), peaking later to 6-8ft across exposed breaks, with a possible secondary pulse of lesser period swell Friday (21st).

Moderate to fresh SE trades this week with periods of variable winds each morning. Weaker SE trades on the weekend, possibly increasing a little early next week.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Smaller surf tomorrow morning ahead of a large, new S/SW groundswell building later in the day, peaking through Thursday afternoon to 6ft to occasionally 8ft across exposed breaks.

Swell easing slowly through Friday and into the weekend, smaller through Monday/Tuesday next week.

Moderate to large S/SW groundswell building Wednesday, peaking later to 6ft+ across exposed breaks, holding Thursday.

N/NW winds Tuesday (today), becoming variable tomorrow, remaining so through until Thursday. Fresher S/SE-SE winds developing across southern locations Thursday, all locations Friday. Variable tending S/SE winds Saturday/Sunday with stronger SE-S/SE winds likely to develop through next week.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Persistent SE trade-swell to the 4ft range most of this week across the southern atolls (3ft to occasionally 4ft Male), easing Friday.

Moderate sized S'ly groundswell building later today, peaking tomorrow to 4ft across the southern atolls (smaller in Male), easing Thursday.

New pulse of moderate sized SE trade-swell for Saturday afternoon to 4ft, easing Sunday (smaller and later Male).

Moderate to large S'ly groundswell building Monday afternoon, peaking Tuesday to 4-6ft across the southern atolls (smaller Male).

Possible super-charged SE trade-swell building Friday, peaking next weekend.

Moderate W/NW winds across the central and northern atolls today, variable to the south, W/SW tomorrow (W/SW tending S/SW to the south).

W/SW winds Thursday across the central and northern atolls (S'ly to the south), variable Friday with weak S/SE-SE winds to the south.

Variable winds for the weekend with possible W/SW-SW winds early-mid next week.