Western Australian Forecast by Ben Matson (issued Friday May 9th)

Features of the Forecast (tl;dr)

• New swell Sat PM, but likely spoiled by onshore winds (all coasts)
• Smaller, easing surf with offshore winds Sun AM
• Patchy outlook early next week
• Nice groundswell building late Wd, peaking Thurs/Fri, easing Sat, clean with offshore winds

Recap

Metro beaches have been tiny for the last few days but the lower SW has seen fun waves, easing from 4ft Thursday to 2-3ft today, clean with generally offshore winds. 

Fun waves in Margs early Thurs

This weekend (May 10 - 11)

No changes to the weekend forecast.

A trough is expected to cross the coast overnight though the associated onshore winds won’t be terribly strong. By the morning, we should be back to moderate levels across the Margs region - however, high res models are expecting a secondary change to push through early-mid morning, which will freshen the onshore breeze (15-20kts) and this will likely bump things up again.

The change is only expected to clip the southern part of the coast so it may not affect Mandurah and Perth. In any case we should see the wind swing SE across metro locations by the morning, once it passes through.

As for surf, a new swell is expected to arrive during the day - likely after lunch - generated by a small cut off low in the central/southern Indian Ocean this week. 

I’m still concerned that metro beaches may only see the new swell kick in once the afternoon breeze swings to the S/SW and freshens, rendering open beaches bumpy. We’ll just have to wait and see how that plays out. But size should increase to a slow 1-2ft by the end of the day. 

Margs will see a bigger increase through the afternoon into the 4-5ft range but conditions will likely remain bumpy under the onshore. Keep your expectations low.

Sunday is a better choice with winds veering back light offshore across all coasts, and conditions cleaning up as the swell slowly fades. Expect inconsistent 1-2ft sets across metro beaches and inconsistent 4ft surf easing to 2-3ft in Margs. Winds will veer cross-shore into the afternoon (across all coasts) so aim for an early session for the best options. 

Next week (May 12 onwards)

A new swell is expected to arrive on Monday, generated by a small but tight cut-off low tracking below Heard Island yesterday and today. Sets will be inconsistent but should rebuild into the 4-5ft, maybe 4-6ft range across the Margs coast on Monday afternoon (smaller through the morning). Metro beaches should pulse back up into the 1-2ft range after lunch. 

Unfortunately, local conditions look poor. Early morning is expected to be clean with light offshore winds (with smaller leftover swell from the weekend) but a new ridge of high pressure will concurrently arrive in the afternoon, driving fresh and gusty S/SW winds across the region (metro beaches will fare the same, though with much smaller wave heights). There's a slim chance we'll see the new swell arrive before the ridge pushes through, but I woudn't get your hopes up.

As such I’m not expecting any quality surf to eventuate from this new swell.

Easing size and a swing in the wind to the SE should offer improving conditions on Tuesday morning though it’ll probably remain a little scrappy in Margs give the overnight southerly flow, and metro beaches will be on the small side. 

The longer term has been downgraded - the storm track from Africa through the southern Indian Ocean is still looking very active however the fetch alignment has been tilted away from our swell window, meaning the WA coast will be less in the direct line of fire, and will receive mainly sideband energy.

Nevertheless, we’re still looking at a quality increase in new groundswell arriving Wednesday afternoon and peaking through Thursday and Friday before easing on Saturday. At this stage the height of the swell (Thurs PM, Fri AM) should pick up 6ft+ sets throughout Margs (2ft across metro beaches), and the current outlook is for favourable winds too. 

Beyond this, the outlook remains active with a series of storms below Africa lining up to deliver plenty of waves through the following week - just in time for the WSL! More on that in Monday’s update!.