Western Australia Surf Forecast by Craig Brokensha (issued Friday April 21st)

Best Days: Today, tomorrow, dawn Sunday for the keen in the South West (Perth and Mandurah), Tuesday morning Perth and Mandurah, Friday, Saturday morning in the South West next weekend

Features of the Forecast (tl;dr)

• Mod-large building W/SW groundswell Sat, peaking in the PM with mod-fresh E/SE winds ahead of weak sea breezes
• Easing swell Sun with light winds at dawn, slowly increasing from the S/SW during the morning, then tending W/SW. Longer window of light winds to the north
• Mod-large mid-period SW swell building Mon with strong S/SW tending SW winds
• Easing swell across metro locations Tue, with a large acute S'ly swell with gusty S/SE tending S/SW winds
• Easing mix of swells Wed with strong S/SW winds
• Smaller Thu ahead of a large new mix of swells building into the PM, peaking Fri AM
• Gusty but easing S winds Thu, E'ly Fri ahead of sea breezes

Recap

Great conditions but with smaller, easing 4-5ft+ surf across the South West yesterday, 1-2ft in Perth and Mandurah and best before lunch.

Today the swell reached a temporary low point early, but some new mid-period swell is now on the build with clean conditions and 4-5ft sets across the South West, tiny to the north. We should see the surf pushing to 5-6ft on the sets in the South West and 1-2ft across Perth and Mandurah with weak sea breezes.

Swell on the build today

This weekend and next week (Apr 22 - 28)

Following today's building mid-period swell, we've got a stronger mix of groundswell due to fill in tomorrow, generated last weekend by a strong frontal progression to the south-east of Madagascar.

This will be mixed in with some more localised mid-period energy with the South West due to build to 6-8ft on the magnets, 2ft in Perth and Mandurah. The swell will be most consistent into the afternoon, easing back Sunday from 6ft+ and 2ft respectively on the sets further north.

Local winds will be great and offshore out of the E/SE tomorrow morning, giving into weak afternoon sea breezes. Sunday will then see early variable winds, quickly shifting S/SW but light and then slowly increasing into the afternoon from the SW. Perth and Mandurah should see winds remaining light until late morning.

This will be linked to an approaching frontal system that now looks to spawn into a mid-latitude low directly south of us on Monday.

The low is expected to be slow moving, creating poor conditions and surf through early-mid next week with strong S/SW tending SW on Monday and then S/SE tending S/SW on Tuesday.

Due to the formation of the low, we've got a downgrade in the expected swell on Monday/Tuesday, with the initial stages still being healthy, though weakening on approach to us.

Size wise we should see a mix of mid-period swell and windswell building Monday, reaching 8ft or so in the South West, 2-3ft late in the day across Perth/Mandurah, then easing from 2ft+ Tuesday morning. Margs will see a large S'ly swell pushing up past the coast on Tuesday, generated by the low but likely only getting in at 8-10ft across exposed breaks and with those tricky winds.

Easing surf along with persistent onshore S/SW winds is due on Wednesday, still 6-8ft in the South West and 2ft to the north, still average Thursday with smaller surf and gusty S winds. Into the afternoon and Friday, a new large S/SW swell is expected as winds ease and improve.

We're looking at another mix of mid-period energy and groundswell, generated by a strong polar frontal progression developing around the Heard Island region on Sunday evening. We may see a front spawning of this progression, pushing up and generating some additional mid-period swell, but regardless we should see the South West kick to at least 8ft+ with 2-3ft sets across Mandurah, 2ft in Perth along with a light, morning offshore breeze.

Following this we've got smaller but fun swells with lighter winds, but more on this Friday. Have a great weekend!