Large swell to end the week, very active next week

Bali and Mentawais forecast​​​​​​ by Craig Brokensha (issued Thursday 6th September)

Best Days: Every day for experienced surfers

This week and next (Sep 7 - 14)

Bali: The surf has bottomed out today leaving small peaky leftovers across the region, still good for a morning grovel.

Later today we should start to see the long-period forerunners of tomorrow's large S/SW groundswell filling in, with the swell due to build all day and peak overnight before easing Saturday.

This swell was generated by a strong and slow moving polar frontal progression the developed late last week, with the final stages of the storm moving across WA yesterday.

Exposed south magnets should build strongly to 8-10ft on the sets by late afternoon and then ease from the 8ft+ range on Saturday, smaller into Sunday.

We'll see the swell continuing to drop through Monday ahead of a late pulse of new S/SW groundswell, peaking Tuesday morning.

This is being generated by a relatively weak polar front that formed around the Heard Island region yesterday, producing a fetch of W/SW gales. This front is now weakening while broadening and projecting north-east towards the south of WA, ideally through our southern swell window.

A moderate to large sized S/SW groundswell should result, kicking later Monday to 4-5ft+ later in the day and peaking Tuesday in the 6ft range, if not for the rare bigger one.

This is under the model expectations with Wave Watch incorrectly combining an existing mid-period swell with the new long-period swell.

Into Wednesday a better reinforcing long-period S/SW groundswell is due to fill in, produced by a much stronger storm developing west-southwest of WA, aiming a fetch of severe-gale to storm-force W'ly winds on the periphery of our swell window.

While not ideally aimed we should still see 6-8ft sets across magnets through the day, easing back into Thursday morning.

Two additional pulse of S/SW groundswell are due, the second being largest, produced by a good broad polar frontal progression projecting gales north-east across the Heard Island region, followed very closely behind by a stronger smaller fetch of severe-gales on top the active sea state.

Two close-spaced S/SW groundswell will be generated, the first arriving Thursday afternoon, with the secondary for Friday morning.

We'll see sets pushing towards the consistent 8ft range later Thursday with Friday offering 8ft+ waves across swell magnets.

The easing trend through next weekend and early the following week will likely be slowed by some reinforcing energy from continued though slightly weaker polar frontal activity, but more on this Tuesday.

Looking at the winds and moderate to fresh E/SE trades are due tomorrow and over the weekend, weaker and taking a slight SE bias through next week. Each morning will see periods of variable winds due to local land breezes.

16 day Bali Forecast Graph
16 day East Java Forecast Graph
16 day Sumbawa Forecast Graph

Ments: Some new inconsistent long-period SW groundswell should be on the build across the region today, reaching 4-5ft+ and holding a similar size tomorrow morning.

This will be ahead of the new long-period S/SW groundswell, building to at least 6ft+ by dark if not 6-8ft and peaking Saturday morning to 6-8ft.

We'll then see the S'ly swell easing through the afternoon, further Sunday and Monday.

The S/SW groundswells for Bali will be generated late in our swell window and not ideally aimed until the back to back polar storms push up across Heard Island.

So the initial increases in swell for Tuesday through Thursday look to come in around 4-5ft+ on the former, easing a touch into Wednesday morning ahead of a slightly stronger 4-6ft south swell later in the day and Thursday morning.

The better aligned fronts pushing north-east from the Heard Island region will produce the best swells for later next week, pushing to 6-8ft Friday before easing into next weekend.

Conditions will be great over the coming days and until Monday with generally variable winds, kicking back in from the SE from Tuesday, persisting through the end of the week.

16 day Mentawai forecast graph
16 day Nias forecast graph
16 day South Sumatra forecast graph


gekatmargs's picture
gekatmargs's picture
gekatmargs commented Saturday, 8 Sep 2018 at 12:26pm

That swell has not come to its forecasted potential.
The odd 6 footer late yesterday arvo at Ulus was about it. Bummed


gekatmargs's picture
gekatmargs's picture
gekatmargs commented Sunday, 9 Sep 2018 at 12:33pm

What a hoax swell here in Bali.
Subscribe to Swellnet pro
8-10ft they said
Book a flight to Bali, Friday 4-6ft not 6-10ft
Saturday 3-5 ft not 8-10ft
Sunday 3 ft not 6 ft
Not happy


goofyfoot's picture
goofyfoot's picture
goofyfoot commented Sunday, 9 Sep 2018 at 1:03pm

Ouch, that’s gotta hurt.

Craig's picture
Craig's picture
Craig commented Monday, 10 Sep 2018 at 10:36am

Ah that's a shame to hear, swell was looking really good and observations across Western Australia were in line with forecasts. 

BTW swell has south in it so always expect less size on the Bukit reefs.

ringmaster's picture
ringmaster's picture
ringmaster commented Sunday, 9 Sep 2018 at 1:11pm

Ya know it's 2018 when some bloke blames a surf forecasting website for his dud weekend in Bali.........

greyhound's picture
greyhound's picture
greyhound commented Sunday, 9 Sep 2018 at 9:19pm

Pathetic ain’t it. Geez, probably seeking legal advice to.

gekatmargs's picture
gekatmargs's picture
gekatmargs commented Sunday, 9 Sep 2018 at 11:23pm

Whatever knob jockeys
Just saying the forecast was a bit off
Still fun but should of packed shorter boards


Kellya's picture
Kellya's picture
Kellya commented Sunday, 9 Sep 2018 at 11:57pm

Better luck next year!