Bali, Indonesia Surf Forecast 4 - 15 July, 2017

3 Jul 2018 0

Ben Macartney

Chief Surf Forecaster

Forecast Issued Tuesday, July 3, 2018

At long last, Indonesia’s swell window is finally starting to reflect a more typical winter synoptic pattern. While the month of June clearly underwhelmed in the swell-department, it’s starting to look like July will make up for it. Already we’re seeing a deep low aiming 40kt gales at Indonesia – and this may well be a precursor to something far more significant occurring into the middle of the month. If the prospect of some quality time in Indo gets your froth on, don't forget to sign up to the Golden Passport comp before it's too late!

The surf has only been small of late, but that's all about to change into the second week of July. Photo: Ratu Motu.

Daily Summary

Wednesday 4
Mix of new SSW and SW swells bump up to 2 to 3ft exposed breaks, with scope for slightly bigger sets into the afternoon. Grading smaller at 1 to 2ft+ elsewhere with size depending on exposure. WIND: Early light and variable tending ESE 15 to 20 knots.

Thursday 5
Slight SW swell reinforced by rising SSW groundswell during the afternoon. Sets around 2ft+ exposed breaks, bumping up to 2 to 4ft during the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE 10 to 20 knots.

Friday 6
Mid period SSW groundswell peaks during the day. Sets ranging from 3 to 5ft at exposed breaks, grading smaller elsewhere depending on exposure. WIND: Early light and variable tending ESE around 10 to 15 knots.

Saturday 7
Powerful SSW groundswell builds throughout the day. Sets initially ranging from 3 to 5ft across exposed breaks, building to 4 to 6ft during the morning and peaking at 6 to 8ft+ throughout the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Light and variable tending ESE around 10 to 15 knots.

Sunday 8
Large SSW groundswell maintains peak size early in the 5 to 8ft range exposed breaks, settling to 4 to 6ft during the afternoon. Grading smaller elsewhere depending on exposure. WIND: Early light and variable tending ESE 10 to 20 knots.

Monday 9
Fading SSW groundswell. Sets to 4 to 5ft+ exposed breaks early, easing to 3 to 4ft+ during the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE and freshening 15 to 20 knots during afternoon.

Tuesday 10
Leftover SSW swell reinforced by new SSW groundswell during the afternoon. Sets ranging from 2 to 3ft+ exposed breaks, grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE around 15 knots.

Wednesday 11
SSW groundswell peaks around 3 to 4ft+ exposed breaks, grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE around 10 to 15 knots.

Overview
Tuesday morning revealed one of the smaller winter surf-days you’re likely to see across Indonesia as residual SSW swell bottomed out at a slow 1 to 2ft along exposed breaks. However, from this point onwards the news gets better, with a building trend in SW and SSW swells expected to culminate in the first proper winter swell-event seen in some time. This originates from a deep Southern Ocean low that rapidly intensified southeast of Heard Island on Monday; giving rise to an expanding SSW fetch in conjunction with an adjacent 1037 hPa high pressure situated over the central Indian Ocean. The meridional (south to north) character of this fetch aligns more or less directly with Indonesia – and hence this also applies to the associated 30 to 35ft sea-state.

The leading edge of a resulting, long period SSW groundswell begins to show at low-levels on Friday ahead of the bulk of energy building in throughout Saturday. This may see wave heights a little undersized at first light (ranging anywhere from 3 to 6ft), preceding a strong kick in size throughout the morning. This is shaping up as a 6 to 10ft peak unfolding later Saturday – although there’s still some model divergence lending uncertainty to the precise timing of this event. However it pans out, there’s still likely to be plenty of size leftover on Sunday in the 5 to 8ft range, with a slow easing trend to follow early to mid next week.

Latest virtual buoy data for Bali reflects a steady upward trend in wave energy into the back half of the week.

Long Range
In the wake of this weekend’s SSW event we once again see the re-emergence of the aforementioned high pressure system exerting a suppressing influence on swell-potential. The models are in tight agreement on this; indicating a large high will remain slow moving over the central Indian Ocean from Wednesday to Friday, before rapidly weakening and shifting across WA this weekend. In its wake, we may see a favourable pattern developing as an intensifying polar low developing below South Africa begins to interact with a stationary high just south of Madagascar. As the low slides eastward we should see a long SW fetch developing across the south-western Indian Ocean this weekend; spawning a new, round of SW groundswell for the region arriving sometime around Friday 13^th and holding peak size over the weekend of Saturday 14^th July. For now the models show clear divergence on the storm’s characteristics, so confidence on the specifics is still low. Having said that, ECMWF runs are extremely bullish no this pattern; indicating this first low will be backed up by a deeper mid-latitude low forming west of Heard Island early next week; carrying a broad belt of severe gales over the south-eastern Indian Ocean on Tuesday 10^th/ Wednesday 11^th. For now this holds speculative potential for an even larger SW groundswell; inbound across the Archipelago early in the week of Monday 16^th July. Having said all that, corresponding GFS runs are not reflecting these long-term developments, so we’ll have to wait and see which direction the models swing as the week progresses for clarity on this possibility.