Western Australian Forecast by Craig Brokensha (issued Wednesday October 9th)

Best Days: Tomorrow all locations, Friday morning all locations, Sunday morning all locations

Features of the Forecast (tl;dr)

• Large, reinforcing SW groundswell tomorrow AM, easing later and further Fri
• Gusty E/SE winds tomorrow, tending variable
• Strengthening E/NE tending NE winds Fri, easing from the N into the PM (shifting more W later in metro locations)
• Moderate + sized reinforcing SW groundswell Fri PM, easing Sat
• Strong S/SW tending S/SE-S winds Sat
• Moderate sized, reinforcing groundswell Sun with E/SE tending S/SW winds
• XL, long-period W/SW groundswell building Mon PM, with strengthening W/NW winds, peaking Tue with strong W/SW-W winds

Recap

The surf backed off more in size yesterday with a window of lumpy conditions at dawn across the South West before onshore winds kicked in.

Today a trough has brought a shift in the winds around to the S/SE (early S/SW across Margs) along with a large, building W/SW groundswell that’s now 8ft in the South West, 2-3ft across Mandurah and 2ft in Perth.

We should see this swell continuing to build towards 10ft on the sets across Margs, 3ft+ Mandurah and 2-3ft in Perth.

This week and next (Oct 10 - 18)

Today’s large W/SW groundswell will be reinforced by a secondary pulse of SW groundswell tomorrow morning, generated by a great, secondary fetch of W/SW-SW gales to our south-west last night and this morning.

This should maintain 8-10ft surf in the South West tomorrow morning, 3ft+ across Mandurah and 2-3ft in Perth, easing through the day and then smaller into Friday morning. Friday afternoon should see a good, reinforcing pulse of SW groundswell produce by a small, tight and fast moving low in behind the current frontal progression.

This should keep the South West around 6ft, with 2ft sets across Mandurah and 1-2ft waves in Perth, easing Saturday.

Looking at the local winds and tomorrow is the pick with a fresh E/SE offshore, easing into the afternoon and tending variable.

Friday will be best at dawn with early, fresh E/NE winds due to shift NE during the morning while strengthening, then more N’ly while easing and then W’ly across Perth/Mandurah, N/NW in the South West.

Saturday looks to be a lay day as a trough brings a strong S/SW-S change as the swell eases, with winds tending S/SE into the afternoon across the South West while kicking up some localised windswell in the metro regions.

Sunday will clean up rapidly again as winds shift back offshore from the E/SE and another good pulse of moderate sized SW groundswell is due, generated by another smaller, tighter low moving through our swell window tomorrow night and Friday.

4-6ft surf should continue in the South West, 1-2ft across Mandurah/Perth.

Of greater significance is a severe low forming south-east of South Africa this evening.

This looks to be quite the system with a great fetch of storm-force W/SW-SW winds due to project through our western swell window from tomorrow through Friday, only weakening slightly on Saturday while tracking closer towards us, stalling a little through Sunday.

What will result in an XL, long-period, W/SW groundswell that’s due to arrive Monday afternoon but peak through Tuesday. The South West looks to peak in the 15-20ft range with 4-5ft surf in Mandurah and 3-4ft sets across Perth.

Unfortunately the remnants of the storm moving in from the west will bring strengthening W/NW winds on Monday, then strong W/SW-W on Tuesday, creating poor conditions. Wednesday also looks onshore with strengthening W/NW winds as the next swell producing front approaches, so all in all it looks to go to waste.