Swell Alert: The Most Active Storm-Track In Years Lights Up Indonesia

17 Jul 2018 3 Share

Ben Macartney

Chief Surf Forecaster

Indonesia Surf Forecast 18 - 31 July, 2018

Forecast Issued Tuesday, July 17, 2018

Usually the appearance of a purple blob on the charts has many or us entertaining ideas of a strike mission. To just drop everything, book a flight and getting over to Indonesia ASAP. Then there’s another kind of blob. The one with weird colours representing the highest significant wave-height on the scale – or the one that sits at some indeterminate point beyond it. It’s one of the latter variety that’s lighting up Indonesia’s swell window this week under the influence of the most active storm-track seen in many years.

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These kind of swell-events just aren’t for everyone. The prospect of quadruple overhead sets at Outside Corner, freight training Speed-reef or the giant, crystal tubes of No-Kanduis just isn’t everyone’s up of tea. So if you’re suddenly feeling very comfortable being at home, tucked away under your doona, or suiting up for a few 2ft waves at your local, there is nothing wrong with that. On the other hand, if you’re packing an 8ft quad specifically designed for such occasions, it’s fair to say it’s looking like the opportunity of a lifetime.

There's a whole lot of this kind of surf in store across Indonesia this week. And the next. Photo: Kanduivillas.

There's a whole lot of this kind of surf in store across Indonesia this week. And the next. Photo: Kanduivillas.

Daily Summary


Wednesday 18
Strong SSW groundswell reinforced by long-period forerunners leading in heavy surf on Thursday. Consistent sets ranging from 5 to 6ft+ exposed breaks, rising to 5 to 8ft during the day and up to 6 to 8ft+ later. WIND: Early light and variable tending ESE around 10 to 15 knots.

Thursday 19
Heavy SSW groundswell arrives from 200 to 205 degrees. Heavy sets ranging from 10 to 12ft+ exposed breaks. Potential for bigger 15 to 20ft sets at deepwater breaks. Wrapping at lower, albeit still large levels elsewhere. WIND: Early light and variable tending ESE 10 to 15 knots.

Friday 20
Large SSW groundswell continues. Sets ranging from 8 to 10ft+ exposed breaks, grading smaller elsewhere depending on exposure. WIND: Early light and variable tending ESE around 10 to 12 knots.

Saturday 21
Easing SSW groundswell around 6 to 8ft+ across exposed breaks, settling into the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Light and variable tending ESE around 5 to 10 knots.

Sunday 22
Trailing SSW groundswell levels off around 3 to 5ft exposed breaks and drops into the 3 to 4ft range during the day. Solid 4 to 6ft sets across exposed breaks early, building into the 6 to 8ft+ range during the day. Grading smaller elsewhere depending on exposure. WIND: Early light and variable tending ESE 5 to 15 knots.

Monday 23
Renewed building trend in SW groundswell. Potential for 3 to 6ft surf throughout the morning, rising into the 4 to 8ft range during the afternoon. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE around 10 to 15 knots.

Tuesday 24
Potential for heavy SSW groundswell building into the afternoon. Sets ranging from 8 to 10ft+ exposed breaks, speculatively building to at 8 to 12ft+ in the afternoon/ evening. Grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE around 10 to 15 knots.

Wednesday 25
Powerful SSW groundswell speculatively 8 to 12ft exposed breaks, grading smaller elsewhere with size depending on exposure. WIND: Early light and variable tending ESE around 10 to 15 knots.

Overview
Over course of last weekend one of the larger sea-states seen in recent years peaked over the south-eastern Indian Ocean; spawning not only the largest SSW groundswell of the season – but the biggest in many years
. This event follows in the wake of a large, complex extratropical low that initially set up over the far southern Indian Ocean last weekend. The storm intensified southeast of Heard Island, achieving a central pressure of 955hPa and giving rise to phenomenal seas peaking in the 40 to 50ft plus range over the Southern Ocean on Sunday. This was the catalyst for an exceptionally large SSW groundswell not closing the distance on Indonesia.

It’s arrival is preceded by a more typical SSW pulse that’s expected to nudge set waves up into the 6ft plus range across exposed breaks on Wednesday through early Thursday. However, this will be eclipsed as the leading edge of the larger SSW groundswell begins to fill in early on Thursday at peak intervals of 18 to 20 seconds, leading in the bulk of a monstrous swell event that will rock the entire archipelago throughout the day. Given the rarity of such events and the long-peak periods and strong southerly bias in swell direction, it will invariably produce a wide range of large and powerful surf; showing peak size in the 10 to 12ft plus range on the Hawaiian scale across the more exposed reefs. That means quadruple overhead sets or bigger at the most exposed reefs, while wrapping at anything from double to triple overhead plus at usually sheltered regions inside the Bukit Peninsula.

The tail end of Thursday’s peak will continue to see large surf prevailing throughout Friday; probably still in the 8 to 10ft plus range across exposed regions before it finally settles into the 6 to 8ft realm on Saturday. With moderate ESE tradewinds in full effect, the west facing reefs will be the places to be – unless you’re aiming for a pre-tradewind dawn session along a more east-facing stretch.

By the morning of Sunday 22nd the surf should return to more accessible, 3 to 6ft levels across the region, with a further decline likely as the day progresses. However, by Monday 23rd it looks like it will be game on once more as a renewed building trend in SW groundswell sets in; probably marking the start of another phenomenal week of large surf enduring throughout the final week of July.

Another phenomenal low developing later this week holds good potential for another exceptionally large SSW swell-event over the course of next week. Source: Wave Tracker.

Another phenomenal low developing later this week holds good potential for another exceptionally large SSW swell-event over the course of next week. Source: Wave Tracker.

Long Range
A second, powerful surge in the long-wave trough is set to reignite the southern Indian Ocean storm-track later this week. This activity commences with a deep low developing over the mid-latitudes on Wednesday, forming a deep southerly fetch in conjunction with a high south of Madagascar.
While this is the likely source of a first, powerful SW pulse arriving on Monday 23rd, it’s only the beginning of a major phase in wave-growth over the region. The subsequent development of a deep polar low below the Kergulen Islands on Thursday and Friday is projected to culminate the evolution of a super-storm over the south-eastern Indian Ocean; manifesting a broascale extratropical low exhibiting a central pressure in the 920hPa to 930hPa range. This coincides with steady intensification and expansion of the aforementioned high to the west to give rise to a phenomenally broad, expansive SW/SSW fetch exhibiting speeds of 40 to 50 knots.

At this early stage the models vary somewhat on the forecast size, strength and positioning of the low (and associated fetch) – so the specifics on surf potential and arrival times may change somewhat from what’s currently projected. Either way, this looms as another monster SSW swell-event; building in steeply late Tuesday 24th and showing peak size on Wednesday 25th; somewhere in the vicinity of 10 to 15ft across exposed breaks. Like the previous event, this also looms as not only an extremely large, but also long-lived event; still holding major size as it begins to recede throughout Thursday 26th.

On top of that, there are further indications we’ll see another extra-large pulse arriving on Friday 27th/ Saturday 28th following the later stages in the storm’s lifecycle unfolding this weekend. Again the details on this will become clearer over the course of the week so stay tuned for more in next week’s update.

The largest swell-event in many years looms for Indonesia this week, with yet another one brewing for late July.

The largest swell-event in many years looms for Indonesia this week, with yet another one brewing for late July.


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

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