Bali, Indonesia Surf Forecast 1 - 15 August, 2018

31 Jul 2018 0 Share

Ben Macartney

Chief Surf Forecaster

Forecast Issued Tuesday, July 31, 2018

In the wake of last week’s mega SSW groundswell the southern Indian Ocean has started settle down – but that’s only relative to what, by all reports the largest swell-event to impact Indonesia in decades.  The fact is, Indonesia’s swell window is – and will remain highly active over the next week or more – and that means a continuation of solid, long-period SSW groundswell inbound across the Archipelago – at the bare minimum lasting throughout the first week of August and perhaps continuing into the second as well.

The surf has been maxing across Indonesia throughout late July and there's more to come into the first week of August. Photo: Kanduivillas.

The surf has been maxing across Indonesia throughout late July and there's more to come into the first week of August. Photo: Kanduivillas.

Daily Summary

Wednesday 1
Mid range SSW groundswell levels off around 3 to 5ft exposed breaks, grading smaller elsewhere depending on exposure. WIND: Early light and variable tending SE to SSE around 10 to 15 knots.

Thursday 2
SSW groundswell slowly eases. Initially still ranging from 3 to 5ft exposed breaks, wrapping at lower levels elsewhere. WIND: Early light and variable tending SSE 10 to 15 knots.

Friday 3
Smaller SSW groundswell reinforced by rising S swell during the afternoon. Initially 2 to 4ft exposed breaks, building to 3 to 5ft during the afternoon. Grading smaller elsewhere depending on exposure. WIND: Early light and variable tending E to SE around 5 to 15 knots.

Saturday 4
Large SSW groundswell arrives from 200 degrees, peaking around 8 to 10ft across exposed breaks, settling into the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Light and variable tending SE around 5 to 15 knots.

Sunday 5
Easing SSW groundswell holds around 5 to 8ft exposed breaks and drops into the 4 to 6ft+ range during the afternoon. Grading smaller elsewhere depending on exposure. WIND: Early light and variable tending SE 10 to 15 knots.

Monday 6
Renewed spike in large, long-period SSW groundswell. Potential for 4 to 6ft+ sets exposed breaks, grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending SE 5 to 15 knots.

Tuesday 7
Potential for solid SSW groundswell ranging from 4 to 6ft+ exposed breaks, gradually easing throughout the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending SE around 5 to 15 knots.

Wednesday 8
Leftover SSW groundswell speculatively 3 to 5ft exposed breaks, grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE about 10 knots.

Overview
Indonesia’s swell window remains in the midst of a heightened phase in winter-storm activity; strong enough to deliver many more days of overhead to well overhead surf to The Archipelago throughout the first and second weeks of August. Monday saw another sizeable peak in long-period SSW groundswell gradually tapering off throughout Tuesday; still ranging anywhere from 4 to 6ft plus across the more exposed reefs early in the day.

As the tail end of this event continues to scale down we can look forward to a series of more accessible days of surf; still ranging anywhere from 3 to 6ft along the more exposed reefs under light to moderate south-easterly tradewinds.  This energy is comprised of overlapping pulses arriving out of the same 210 to 215 degree band that’s been the primary directional range throughout July – in turn arising from successive, winter scale lows reaching maximum strength over the south-central to south-eastern Indian Ocean.

This activity has continued unabated into the final days of July, following the lifecycle of several large and intense broadscale lows over the region. This sustained activity sees multiple wave-trains combining as they arrive across The Archipelago in tandem over the coming week. Indeed it appears the addition of several swells is exaggerating virtual buoy readings for an upcoming peak in size slated for this Saturday.

A first, intense low that swept rapidly through Indonesian and Western Australian longitudes last weekend set up a first, long-period pulse of S groundswell (195 degrees) that’s projected to start building in on Thursday and Friday. This overlaps with a second, larger groundswell (arriving from 200 to 205 degrees) building in over the top of this first pulse this weekend.

This second, larger storm achieved a central pressure of 946hPa southeast of Heard Island on Monday; giving rise to another expansive SW fetch throughout the south-eastern Indian Ocean. However, this time around we’re not seeing the same 40 to 60kt calibre winds associated with the monumental event that peaked on July 25. In this case the pressure differential between a 1026hPa high located southeast of Madagascar is substantially smaller – and based on latest ASCAT passes this has translated into comparatively modest wind-speeds in the order of 30 to 40 knots – in turn generating maximum significant wave-heights of 25 to 30ft. The upshot is a still large, but far more accessible pulse of SSW groundswell emanating from this source; the leading edge filling in throughout Friday ahead of the bulk of swell peaking on Saturday 4th in the vicinity of 6 to 10ft across exposed breaks on Saturday before gradually scaling down in size throughout Sunday.

Just as this event settles to more manageable levels on Monday it’s reinforced by yet another long-period pulse; again arriving from a fairly acute directional band of 200 degrees on Monday 6th and Tuesday 7th.  This arises from another vigorous low intensifying as it moves east and clear of the Kerguelen Islands over the next 48 hours; giving rise to a compact severe gale fetch area directly below Indonesia on Thursday through early Friday. Although this system is currently spawning some impressive deepwater SSW groundswell, there are some leading indications we’ll see some downgrading to surf-potential as it develops – and this is reflected in fairly conservative projected surf for Monday and Tuesday of 4 to 6ft plus. This may be upgraded in light of corresponding ECMWF runs that look strong on this system; suggesting a broad SSW fetch area of 40kts will develop over this time frame. Stay tuned for more on this in next week’s update.

Bali virtual buoy: Another series of strong, overlapping SSW groundswells culminate in another large episode peaking across Indonesia this weekend. Source: Wave Tracker.

Bali virtual buoy: Another series of strong, overlapping SSW groundswells culminate in another large episode peaking across Indonesia this weekend. Source: Wave Tracker.

Long Range
Following that, the major computer models are loosely picking up a shift in the storm-track; suggesting we’ll see the focus of cyclogenesis shifting further west, below Madagascar and across the broader south-western Indian Ocean mid to late next week. F of another large, intense winter-scale low – this time forming over the far eastern periphery of Indonesia’s swell window, just below Western Australia through the middle of next week. For now this model guidance points to a lower strength and more zonal pattern; thereby pointing to a return to moderate, mid-period SW swells leading into the middle of August. The particulars on this will become clearer over the course of next week.

Another deep low setting up below WA later this week holds strong S swell-potential for the region over the weekend of Saturday 11th. Source: Wave Tracker.

Another deep low setting up below WA later this week holds strong S swell-potential for the region over the weekend of Saturday 11th. Source: Wave Tracker.


Tags: Indo Surf Forecast , Ben Macartney (create Alert from these tags)

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