Bali, Indonesia Surf Forecast 15 - 30 August, 2018

14 Aug 2018 0 Share

Ben Macartney

Chief Surf Forecaster

Forecast Issued Tuesday, 14 August, 2018

While the height of this winter’s southern hemisphere storm-track appears to have come and gone, there’s still plenty of swell on-tap across Indonesia throughout mid to late August. Broadly speaking, this features a combination of overlapping SW and SSW groundswells arising from disparate sources; combining with mostly light tradewinds to produce many more days of classic Indonesian surf for the foreseeable future. If that all sounds a little ambiguous, then read on for more a more in-depth outlook below.

There's plenty more of these on Indonesia's forecast horizon throughout mid to late August. Photo: Any Potts/ The Perfect Wave.

There's plenty more of these on Indonesia's forecast horizon throughout mid to late August. Photo: Any Potts/ The Perfect Wave.

Daily Summary


Wednesday 15
New SW groundswell builds in. Inconsistent early at 2 to 3ft exposed breaks, building to 3 to 4ft during the afternoon with potential for larger 4 to 5ft sets late in the day. WIND: Early light and variable tending ESE around 10 to 15 knots.

Thursday 16
SW groundswell continues to build in at around 3 to 5ft+ exposed breaks, grading smaller elsewhere and fading into the afternoon. WIND: Early light and variable tending SE 10 to 15 knots.

Friday 17
SSW groundswell slowly eases. Initially solid 3 to 5ft+ sets exposed breaks, grading smaller elsewhere depending on exposure. WIND: Early light and variable tending E to SE 10 to 15 knots.

Saturday 18
Fading SSW groundswell initially holding around 2 to 4ft exposed breaks, dropping to 2 to 3ft during the day. Grading smaller elsewhere with size depending on exposure. WIND: Light and variable tending ESE to SE around 10 to 15 knots.

Sunday 19
SSW groundswell holds around 3 to 4ft on the sets across exposed breaks. Grading smaller elsewhere depending on exposure. WIND: Early light and variable tending SE at about 10 to 15 knots.

Monday 20
New SSW groundswell peaks around 4 to 6ft+ exposed breaks. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE to SE around 10 to 15 knots.

Tuesday 21
SSW groundswell slowly eases. Around 3 to 5ft across exposed breaks early and further easing throughout the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending SE around 10 to 15 knots.

Wednesday 22
Leftover SSW groundswell up to 2 to 3ft across exposed breaks, reinforced by new SW groundswell during the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending SE about 10 to 15 knots.

Latest virtual buoy data for Bali reflects a steady upward trend in wave energy over the next few days.

Latest virtual buoy data for Bali reflects a steady upward trend in wave energy over the next few days.

Overview
The onset of a renewed building trend in SW groundswell throughout the second half of this week follows the evolution of a large, complex area of low pressure over the south-western Indian Ocean last week. Regardless of its impressive scale, the absence of an substantial high pressure adjacent to the storm has inhibited potential for a major swell-event. Never the less, the system supported a broad, low-strength WSW fetch spanning latitudes bounded by 30S and 60S for several days; thereby setting up a sustained run of mid-period SW groundswell for the region over the next few days.

The leading edge is due to make landfall throughout Wednesday ahead of the bulk of swell arriving in the 3 to 6ft range on Thursday 16th and Friday 17th from 220 to 225 degrees. There will still be plenty of good sized leftovers on Saturday in the 2 to 4ft range, preceding a further drop in size by Sunday 19th. The good news is another substantial pulse in SSW groundswell is on course to pick up the slack throughout the day and should hold peak size in the 4 to 6ft realm across the most exposed breaks into Monday 20th.

This event follows the rapid development of a mid-latitude low directly south of the Archipelago early this week; setting up a compact 40kt SW fetch responsible for 20 to 30ft seas developing within close range of the Margaret River region early on Tuesday. This will be closely followed by another vigorous, albeit smaller scale mid-latitude low forecast to power-up below Indonesia on Wednesday through early Thursday before it moves inside Western Australia’s swell shadow during Thursday afternoon. The tail end of this combined event should gradually taper off throughout Tuesday 21st and Wednesday 22nd; producing good, mid to small surf on both days.

Long Range
Beyond that, the focus may shift back to the south-western Indian Ocean as a broadscale area of low-pressure develops well south of Madagascar this weekend. At this early stage the key GFS and ECMWF models show pronounced divergence on it’s projected development – in turn lending low-confidence to associated SW swell-potential. Never the less, both models maintain this heightened activity in various guises, indicating multiple low pressure systems will rotate across the south-central Indian Ocean throughout Sunday and early to mid next week.

It’s also worth noting the influence of a large, slow moving high pressure over the central Indian Ocean resulting in a more zonal (westerly) fetch areas; in turn setting up a series of refracted SSW groundswells for Indonesia into late August; speculatively overlapping in the 3 to 6ft range. The specifics on these will become clearer in next week’s update.

Tags: Indo surf forecast , Ben Macartney (create Alert from these tags)

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