Bali and Mentawais forecast​​​​​​ by Craig Brokensha (issued Tuesday 17th October)

Best Days: Bali - Thursday onwards until the swell gets small mid-next week, Ments - Wednesday through till mid-next week

This week and next (Oct 11 - 20)

Bali: We've got a good consistent and large pulse of S/SW groundswell due Thursday the 19th, generated by a very intense mid-latitude low that fired up off the WA coast.

Satellite observations confirmed a fetch of severe-gale to storm-force S/SW winds aimed through our southern swell window, with the swell due to arrive late Wednesday and peak Thursday morning to the 8ft range on the sets at exposed breaks, easing quickly through the day, down further from 5-6ft Friday.

Due to the close nature of the storm to Indonesia, this swell should be fairly consistent compared to normal swells.

Later in the day Friday a new longer-range S/SW groundswell is due, peaking Saturday morning the 21st. This swell was generated by a strong but weakening polar front projecting towards WA on the tail of the mid-latitude low and should provide inconsistent 6ft to possibly 8ft sets at swell magnets Saturday, easing back slowly Sunday with a reinforcing S/SW pulse due into the afternoon.

This reinforcing pulse will be generated by a small polar front firing up on the back of the initial weakening system keeping 6ft sets hitting the region through the afternoon, down from the 5ft+ range Monday morning.

Into next week there's no decent swell due at all with the surf bottoming out.

Looking at the winds over the coming period and a fresh S/SE breeze tomorrow (variable early) will become weaker into Thursday and then we'll see winds tend weak W from Friday through Sunday, though variable each morning.

Variable winds should develop from Monday with afternoon sea breezes.

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

Ments: The swell generated by the tight mid-latitude low will come in from the S'th across our region, with some mid-period energy for tomorrow building to 4-6ft at exposed breaks to the south, with the groundswell filling in Thursday afternoon the 19th, reaching a more consistent 6ft, easing back from 5-6ft Friday.

The secondary less consistent S/SW groundswell is due to build Saturday the 21st, reaching a good 6ft later in the day before easing very slowly from Sunday, small into next week.

Winds over the coming period look good with variable winds tending SE at times due through this week and next.

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