Western Australian Forecast by Craig Brokensha (issued Wednesday May 21st)

Best Days: Today, early tomorrow Perth and Mandurah, Perth and Mandurah protected spots Friday morning, Perth and Mandurah Saturday morning, Monday in the South West

Features of the Forecast (tl;dr)

• Oversized SW groundswell peaking overnight if not early tomorrow AM, easing
• Strong W/NW winds from about dawn in the South West, NE-N/NE in the AM to the north
• Large SW swell Fri with strong SW winds, S/SE early to the north
• Easing swell Sat with fresh SW tending stronger W/SW winds (E/NE early to the north)
• Smaller Sun with strong S/SW winds, lighter and more variable to the north
• Large S/SW groundswell Mon AM, easing with mod-fresh E/NE tending variable winds
• Fading S/SW swell Tue with strong E/NE tending NE winds

Recap

Yesterday’s SW groundswell came in a little over expectations across the South West with clean, improving 10-12ft sets on the magnets while Mandurah offered clean 3ft waves with building surf to 2-3ft across Perth.

Today the swell has eased back but with great conditions and surf to 8ft in the South West, 2-3ft Mandurah and 2ft+ Perth. Winds are due to shift N/NE and then variable through the afternoon along with a mix of new building SW groundswell and the forerunners of an even stronger long-period SW groundswell later in the day.

This week and next (May 22 - 30)

The mix of SW groundswells due into this afternoon originate from the same ‘bombing’ low that fired up to the east of the Heard Island region through Monday, with the long-period SW groundswell component due to peak overnight if not early tomorrow across most regions.

A tight fetch of storm to hurricane-force W’ly winds expanded while slowly weakening through yesterday and with this, an oversized, powerful SW groundswell should be seen, coming in around the 12ft+ range across the South West, 4ft on the sets in Mandurah and 2-3ft across Perth.

The only issue will be the local winds, with an approaching frontal system due to bring strengthening W/NW winds, with a very short-lived period of variable winds possible at dawn across the South West, with more reliable, early NE-N/NE winds in Perth/Mandurah before shifting W’ly.

This frontal system will generate a fresh pulse of close-range SW swell for Friday, with a broad fetch of strong SW winds due to maintain 8-10ft surf in the South West, 3ft Mandurah and 2-3ft Perth.

Local winds will remain poor in the South West Friday and strong from the S/SW with better S/SE breezes likely across Perth/Mandurah during the morning.

Saturday still looks onshore in the South West with fresh SW tending stronger W/SW winds as the next polar frontal system projects up from the south, while Perth and Mandurah should offer early E/NE winds and easing 2-3ft and 3ft waves respectively.

Unfortunately there looks to be no respite for the South West into Sunday with smaller surf and persistent, strong S/SW winds, cleaner to the north but small to tiny.

Into next week, the swing to offshore breezes is still expected and the South West should see a good pulse of new, large S/SW groundswell generated by the polar frontal system projecting up from the south.

A great fetch of S/SW gales on the edge of our swell window should produce some sizey 8-10ft sets on the regional south magnets in the morning Monday, easing through the day, much smaller inside protected spots with Mandurah unlikely to top 2-3ft, 1-2ft in Perth.

An E/NE tending variable breeze will create good conditions all day in the South West, with stronger E/NE tending NE winds due Tuesday as the size fades.

Longer term, some good, distant W/SW groundswell is on the cards for later in the week, generated by a strong, north riding mid-latitude low through the Indian Ocean, but we’ll have another look at this on Friday.