Fun from Saturday onwards
Nias, Mentawai, South Sumatra forecast by Craig Brokensha (issued Thu 3rd Sept)
Best Days: Every day over the coming period
This week and weekend (Sep 5 - 7)
The swell is very small across the Ments but will become even slower into tomorrow as it bottoms out. Super exposed breaks should still offer very inconsistent 2-3ft sets and conditions will be favourable through the morning with generally variable breezes.
The small to moderate long-range S/SW groundswell due Saturday is still on track with a kick in size to a very inconsistent 3-5ft due across exposed breaks through the day Saturday around the Ments. This will then throttle back from 3-4ft+ Sunday with S/SE winds increasing a touch. Nias will see less size with this south swell, while South Sumatra should offer the odd bigger set to 6ft Saturday.
Next week onwards (Sep 8 onwards)
Next week is more than active with a strong node of the Long Wave Trough moving through the South-eastern Indian Ocean over the coming days.
This is steering a series of vigorous polar fronts up through our swell window, with the strongest system due to project up towards WA from a position west of Heard Island this evening and through tomorrow and into the weekend.
An initial couple of pulses of S/SW groundswell are due Monday and Tuesday, reaching 4-6ft at exposed breaks before easing a touch into Wednesday morning.
The largest increase is due to arrive late Wednesday and peak Thursday morning with bigger 6ft to occasionally 8ft sets around the Ments, with 6ft+ waves in Nias and 6-8ft+ surf around South Sumatra.
Winds should co-operate with moderate SE trades in the Ments, while South Sumatra will see stronger E/SE winds from Tuesday, limiting options to more protected breaks.
The swell should ease through Thursday afternoon and further through Friday and Saturday morning ahead of a late kick in new long-range S/SW groundswell. This swell will be mixed in with a medium-range S/SW groundswell and the models look to be overcooking the size a little, combining the two swells while maintaining the period.
Exposed spots in the Ments are likely to come in at an inconsistent 6ft later Sunday before tailing off slowly through Monday and Tuesday.
Longer there's plenty more swell on the cards and we'll review this Tuesday.
16 day Mentawai forecast graph
16 day Nias forecast graph
16 day South Sumatra forecast graph
Comments
What no LWT plots!!! :(
Not happy Jan!
Sorry Don, was pretty busy, next update.
Boohoo!!
Are your long range models progging some serious swell period around 16th-18th Sept (aka 20 sec!!!).
That they are Don..
The jump in swell from 1.3m @ 18s to 2.6m @17.6 isn't correct as it's combinging the mid-period 14.6s swell with the new groundswell, so sizes for Tuesday midday and afternoon are overcooked, but Wednesday looks more on the money with well over 2m of swell in the 16s range.
Let's just say some other forecasts are way over those numbers above. But I couldn't see it myself on the WAMS hence wanted to see what your models were saying.
What model run Don, this is 18z, are they using old data, or another weather model??
Surfline, so I'm assuming it's their 18z run. And they use GFS for input into Lola yeah?
But I just checked it again and it's changed since this morning and more aligned with your numbers above now. They previously had 10ft @ 20 sec!!!! But as I said above, I couldn't see it on the charts, so figured it was an error
Wow, that's a really late update for 18z, we've just got 00z through and here it is..
Surfline only does two updates a day I believe. 18z and 06z.
That's unusual, as you know 18z and 06z have the least amount of observational input data and are generally the least reliable.
I've had this discussion with Surfline and they beg to differ.....anyway, no point discussing this as Surfline won't change.
So do your WAMS update the same time your model output forecasts (screen shot above) update? So if you're 00z run has just updated on your model output forecast can I then also assume that your WAM is also the 00z GFS run?
When are you guys going to plot which model run your models/WAMS are running too? And lat and long grids!!! Great circles too much to ask for also!!! ;)
Actually WAM output still shows 6pm (18z run) so I assume it has updated to the 00z run yet?
Ah, no. The model updates first with the forecast data, and then the charts take a couple more hours to come through after due to all the global domains we have pumping out.
So current WAMs are 18z but should switch over around 6:30 or 7pm.
All those little tweaks are in the works, as well as GC charts at some stage.