Western Australia Surf Forecast by Steve Shearer (issued Monday October 18th)

Best Days: No great days as approaching low brings poor conditions and storm surf, Sat morning first window of good winds

Features of the Forecast (tl;dr)

• N’ly winds freshen Tuesday with increasing N/NW windswell, storm surf building o/night Tues
• Large, stormy W'ly swell Wed with strong to gale-force W winds, easing Thu with abating winds, possibly variable Fri AM
• Large SW groundswell building Fri PM, easing Sat window of good winds Sat morning
• Small leftover Sun morning with good winds AM
• Another round of stormy, onshore surf likely from Tues next week as mid-latitude low approaches region

Recap

Ordinary surf across the weekend in the South West with the best conditions on Sat, with 5-6ft sets, slowly easing during the day. Sunday saw smaller 3-4ft surf in the exposed coasts smaller 1-2 in Mandurah and less than a foot in Perth, with mod SSW winds. Today has seen surf ease further and conditions deteriorate as N’ly winds, heralding the arrival of a mid-latitude low start to establish. This weather feature will be the dominant player in the synoptic set-up this week. Good week to batten down the hatches and forget about surfing.

This week and weekend (Oct 18 - 24)

As Craig mentioned in his notes on Fri, the South-West is about to be smashed by a northwards located trough which is currently forming into a complex, slow moving low. That system is currently located just to the West of the Cape to Cape Peninsula, with a rotating system expected to bring several blasts of onshore wind and storm surf to the region.

The first blast tomorrow will be increasing N/NW windswell, with increasing N’ly winds tending NW through the a’noon and potentially becoming gale force, especially on the Bunbury to Perth stretch. 

No where to really hide from that wind as stormy swell builds into the 4-6ft range in Perth, and 8-10ft in Margarets. This size may build overnight Tuesday into Wed, depending on how quickly the low approaches during Tuesday.

Things escalate on Wed as the low proper slams the coast, bringing strong to gale force W’lies, first to the Perth area, then to the  Margaret’s area. 

That spells a victory at sea day with no great options unless you take on straight onshore storm surf on the Perth groynes.

The W’ly flow  behind the low the continues through Thursday maintaining poor conditions across the South-West as W to WSW swells ease.

Friday sees another moderate/strong pulse of SW swell generated by a low which tracks NE from Heard Is Tues, with 30 ft seas being generated before the low eases as it passes 100E. Winds look crappy in the Margaret River area with a light NW to W flow, that may tend SW in the a’noon. With size in the 6-8ft range, there may be some rideable options at the most protected breaks.

Further north a light S to SSE flow in the Mandurah/Perth stretch offers up rideable 2ft surf in Perth, 3ft in Mandurah.

Windows of clean conditions present through Sat and Sun morning with a light ESE to SE flow, possibly finally cleaning up the surface conditions down at Margarets. Size will have dipped  though as we will be on the backside of Friday’s pulse. There should be some 4-5ft sets on offer, 2-3ft in Mandurah and 2ft in Perth.

This size will drop further into the 3-4ft range at Margarets on Sun, becoming 2ft in Mandurah and 1-2ft in Perth. Early light E’ly breezes are the last window of clean conditions on offer before another extended period of onshore winds becomes established.

Models are still offering divergent outcomes but the general pattern of another high riding mid-latitude low slamming into the South-West looks likely. This sees increasing onshore winds and swell, with W’ly winds becoming established Mon, and size increasing Tues and Wed.

Current model runs suggest size in the 8-10ft range at Margarets, with smaller 4-6ft in Perth. This is likely to be revised so check back Wed and batten down the hatches for this week’s blow.