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

This week through next week (Jul 19 - 28)

We've got easing surf across the regions today (besides the Maldvies), but a strong frontal progression that pushed through the southern Indian Ocean last week has generated a mix of groundswells and for this coming week.

An initial fetch of pre-frontal, gale to severe-gale W-W/NW tending W/SW winds has generated a moderate to large SW groundswell that should fill in tomorrow, peaking through the day ahead of a secondary slightly bigger pulse Thursday.

This will then be superseded by a large SW groundswell on Friday, generated by a strong, high-riding low that formed on the tail of the frontal progression.

A fetch of gale to severe-gale W/SW-SW winds were generated yesterday, with this low now weakening while approaching Western Australia.

A peak is expected on Friday, with a general, steady easing trend due through the weekend, slowed Monday by a small to moderate sized, reinforcing S/SW swell.

Across western Indonesia this swell is due to come in more from the south, offering similar sized sets to eastern Indonesia at its peak on Friday, easing through the weekend.

Looking further west to the Maldives and the first pulse of S'ly groundswell should be in the water today, offering large sets, with the secondary pulse of groundswell due to build later Wednesday, peaking Thursday morning, though not to the size of today's.

We're also due to see a moderate sized + SE trade-swell overriding the S'ly groundswells during Thursday, building further Friday and peaking on the weekend. This is being generated by a broad and elongated fetch of strong E/SE-SE trade-winds, which will ease temporarily on the weekend before re-strengthening.

This will result in a drop in size during early next week out of the SE before muscling back up again mid-late week.

Looking back at the westerly storm track, and a strong low that moved under South Africa but is now weakening, generating today's good swell in Jeffreys Bay, is expected to produce a small to moderate sized, inconsistent SW groundswell for next Tuesday, building through the afternoon.

Of greater importance is a much stronger flurry of activity developing south-east of Madagascar later this week and into the weekend.

Various fetches of gale to severe-gale W/NW followed by SW winds should generate various pulses of large SW groundswell for the middle of next week. At this stage the swell looks to have a couple of pulses, easing into the late week and weekend.

Eastern Indonesia:

Large, inconsistent SW groundswell filling in tomorrow, peaking to an inconsistent 6ft+ into the afternoon across exposed breaks.

Secondary pulse of swell Thursday to 6ft to occasionally 8ft.

Larger groundswell for Friday to the 8ft+ range across exposed breaks (10ft cleanups likely).

Small to moderate sized reinforcing swell Monday (24th) ahead of an inconsistent SW groundswell Tuesday afternoon (25th) to 4-5ft. Large SW groundswell for Wednesday (26th) to the 8ft+ range.

Moderate to fresh SE trades over the coming days, lighter into Friday. Variable winds each morning.

Moderate to fresh E/SE trades on the weekend and into the middle of next week, tending SE later week. Variable winds each morning.

Uluwatu 16-day Forecast Graph/WAMs

Western Indonesia/Mentawais/South Sumatra:

Moderate to large S/SW groundswell building Wednesday, reaching 5-6ft+ across exposed breaks, with a larger mid-period swell for Thursday to 6ft to possibly 8ft. Large S'ly groundswell for late Thursday, peaking Friday to 8ft+ across exposed breaks.

Easing swell through the weekend, further into early next week.

Inconsistent SW groundswell building Tuesday, reaching 6ft late with a larger S/SW groundswell Wednesday to 8ft+ across exposed breaks. Easing swell through the end of the week and weekend.

Fresh to strong SE-S/SE winds across southern locations this week (lighter and more variable across more northern regions), with S/SE winds kicking in to the north on Friday.

SE-S/SE winds persisting on the weekend (stronger to the south), tending variable to the north on Sunday.

Persistent S/SE-SE winds next week, moderate to fresh to the north and more gusty to the south.

Mentawai 16-day Forecast Graph/WAMs

Maldives:

Moderate to large sized S'ly groundswell peaking today to 5-6ft across the southern atolls (smaller Male).

Secondary pulse of moderate to large sized S'ly groundswell for later Wednesday, peaking Thursday to 4-5ft across the southern atolls (smaller Male).

Moderate sized + SE trade-swell building Thursday and further Friday, peaking Saturday to 6ft+ across the southern atolls (smaller Male).

Swell easing slowly Sunday and further into early next week ahead of the next pulse mid-late week.

Inconsistent moderate sized S/SW groundswell building Monday (24th) with a larger pulse Tuesday (25th) to 6-8ft across the southern atolls (smaller Male).

Moderate to fresh W/SW-SW winds across central and northern locations this week, S-S/SE to the south (variable Friday).

Weaker W/SW-SW winds on the weekend (variable to the south), with SW winds next week, fresh to strong S/SE-SE to the south.