Indian Ocean Basin analysis by Craig Brokensha (issued Thursday 10th August)

This week through next week (Aug 11 - 18)

Following a good pulse of moderate-large SW swell yesterday, a slow easing trend is expected across the Indonesian archipelago over the coming days and weekend.

Some reinforcing mid-period S/SW energy will slow this trend late tomorrow and Saturday morning, similar later Sunday and into Monday.

We then look at the coming pulses of groundswell into next week, and an initial inconsistent S/SW groundswell for Tuesday is being over-forecast on the charts, with the wave models incorrectly combining this new energy with exisiting mid-period swell.

The source is a patchy polar frontal progression to the south-southwest of Western Australia yesterday and today, right on the edge of Indonesia's southern swell window.

It'll therefore be inconsistent and south in nature, with moderate sized + sets due Tuesday, up a little on the size seen through the weekend and Monday.

In the Ments expect moderate sized surf, with no real impact for the Maldives.

Of greater importance is the stronger progression linked to the larger swell into Thursday/Friday.

This has formed to the south of South Africa, with a great fetch of gale to severe-gale W/NW winds now tracking east-southeast towards the Heard Island region while weakening.

A broad, persistent fetch of strong to gale-force W/SW winds will continue travelling along with the swell it's generating, producing a captured fetch scenario which results in quicker and larger than normal wave growth.

This should produce a large, healthy SW-S/SW groundswell for later next week, with the long-period forerunners likely to arrive late Wednesday ahead of peak in size Thursday.

The easing trend into Friday and next weekend looks to be slowed by persistent, weaker frontal activity firing up towards Western Australia on the weekend and early next week.

For the Maldives, they'll receive the S'ly groundswell energy from the early stages of the progression, with an initial unrelated pulse of small swell due Saturday afternoon/Sunday ahead of the stronger groundswell later Monday but more so Tuesday/Wednesday.

The easing SE trade-swell across the Maldives should start to pick back up again into the weekend as south-east trades expand and project north-west towards the islands from today.

Moderate levels are expected, while a slight strengthening of the fetch during next week should provide moderate-large sized surf later next week and more so into the following weekend.

Eastern Indonesia:

Slowly easing levels of S/SW swell with some small-moderate sized pulses of background, reinforcing swell later tomorrow, Saturday morning and later Sunday, Monday morning.

Moderate sized + S/SW swell for Tuesday (15th), building to an inconsistent 4-6ft across the exposed breaks, easing Wednesday.

Large, inconsistent S/SW groundswell building later Wednesday, peaking Thursday afternoon to 8ft to occasionally 10ft across exposed breaks, easing slowly into Friday and the following weekend.

Moderate to fresh E/SE-SE trades, light and variable each morning.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Easing surf into Friday and Saturday, smaller Sunday/Monday.

Moderate sized S/SW swell for Tuesday (15th) to 4-5ft across exposed breaks (rare bigger one), easing Wednesday.

Large, inconsistent S/SW groundswell building Wednesday (16th) afternoon, peaking Thursday (17th) reaching 8ft+ across exposed breaks.

Fresh to strong S/SE-SE trades tomorrow and Saturday, lighter to the north and more variable Saturday.

Stronger S/SE-SE winds Monday, weaker S/SE-S to the north, persisting most of the week.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Easing SE trade-swell into tomorrow back to the 3ft range across the southern atolls (smaller Male).

New SE trade-swell pulse building Saturday, holding through Sunday and early next week to 4-5ft across the southern atolls (smaller Male).

Small levels of background S'ly groundswell from Saturday afternoon through all of next week, though peaking Tuesday afternoon, Wednesday morning to 4ft+ across the southern atolls (smaller Male).

Stronger SE trade-swell for later in the week, next weekend to 6ft range.

Persistent, fresh W/NW winds across northern and central locations, lighter to the south (likely tending SW on Saturday).