Small weekend coming up, ahead of a three-day long period swell

Western Australia Surf Forecast by Ben Matson (issued Wednesday 14th October)

Best Days: Fri AM: clean early, easing swell across the lower SW (too small across metro beaches). Mon/Tues/Wed: pulsey long period swell with morning offshores. 

Recap: Offshore winds provided clean conditions across the lower SW on Tuesday as wave heights gradually eased from a very inconsistent 4-6ft. By this morning it was barely 2ft+ at exposed beaches and gusty southerly winds were dominating the region. It’s been very small across the Perth and Mandurah coasts. 

Tuesday morning in Margs

This week (Oct 15 - 16)

*This week’s Forecaster Notes will be a little erratic as Craig’s on annual leave*

A new swell will push across the region on Thursday, generated by a polar low traversing the ice shelf earlier this week. However, as it developed towards the eastern periphery of our swell window, the resulting swell direction will be more S/SW, which will create a slightly broader range in wave heights from beach to beach throughout the Margs region. 

Exposed locations will start off a little undersized but should reach 4-5ft+ by late in the day. Early light SW winds will be around to a moderate southerly by the time the swell peaks, so Friday morning may be a better time to catch the tail end of this swell before it properly eases back, as conditions will be much cleaner with early light E/SE winds. 

Unfortunately I fear the swell direction to be too south for the Perth and Mandurah coasts, so tiny waves on Thursday morning will boost only by a small amount into the afternoon (accompanied by fresh sea breezes). Friday morning will be clean with offshore winds but only the grommets are likely to find anything of value at the swell magnets. 

This weekend (Oct 17 - 18)

No change to the weekend forecast, with Friday’s easing trend expected to bottom out with slow 2-3ft sets at exposed beaches in the lower SW, and very little surf across metro beaches to the north. Similar wind patterns as Friday (early offshores, afternoon sea breezes) will favour the morning session for a quick paddle, but there won’t be much energy around. 

Next week (Oct 19 onwards)

Our long period groundswell for Monday is still on track. In fact the leading edge should appear at the coast very late Sunday though an appreciable increase won’t occur until Monday.

As discussed on Monday, the enormous travel distance will shave off a significant percentage of the swell’s size and consistency, but the latest model guidance has maintained the strength of the responsible low as it tracks through the southern Indian Ocean, so I’ve bumped up wave height estimations a little. 

In fact, a strong secondary low travelling behind will generate another swell that’s due to arrive on Wednesday, so we’re looking at three days of intermittent long period groundswell for the region. Although the second low doesn’t look quite as impressive as the first, it’ll be working on the active sea state generated ahead of it and this may boost surf size slightly higher than that of the first round(s) of energy through Monday and Tuesday.

A key feature of each day will however be the sheer inconsistency of the set waves, thanks to the large distance between the swell source and the mainland - and (at least for Mon/Tues) with no other swells in the water to fill in the gaps, there could be fifteen to twenty minute flat spells from time to time. 

As for size, I am expecting most days to deliver occasional 5-6ft+ sets to exposed locations throughout the Margs region. Early Monday may start off a little undersized, but conversely, later Monday and then Wednesday have the potential for slightly larger waves, mainly at offshore bombies and other swell magnets that can efficiently focus long period swells. Not all breaks have these characteristics - the offshore bathymetry will probably steer the swell in towards some spots, but also away from others, so don’t expect a consistent result from beach to beach.

Anyway, local conditions are looking favourable for the mornings with light winds, ahead of typical afternoon sea breezes. So it’ll be worth scheduling a paddle each morning. 

As for Perth and Mandurah, we'll see small waves each day, perhaps 1-2ft at the former and 2ft+ at the latter, with the same inconsistency traits.

More on this in Friday’s update.


thermalben's picture
thermalben's picture
thermalben Thursday, 15 Oct 2020 at 11:00am

New swell starting to show now.

Wombat86's picture
Wombat86's picture
Wombat86 Friday, 16 Oct 2020 at 10:48pm

What’s happening with the Friday update?

nicko74's picture
nicko74's picture
nicko74 Saturday, 17 Oct 2020 at 8:28am

Craig’s out on RnR

thermalben's picture
thermalben's picture
thermalben Saturday, 17 Oct 2020 at 8:44am

New notes up now (got snowed under with things y'day). Apologies for the delay - Craig's on leave so I'm covering this week.