Western Australian Forecast by Craig Brokensha (issued Monday December 16th)

Best Days: Today, tomorrow morning, Perth and Mandurah dawn Wednesday, protected spots Thursday morning, Friday morning, South West magnets Sunday morning

Features of the Forecast (tl;dr)

• Large, W/SW groundswell easing tomorrow with fresh E-E/NE winds ahead of relatively weak sea breezes
• Smaller Wed with string S/SW winds (likely S-S/SE early to the north)
• Large W/SW groundswell Thu with strong S tending S/SW winds
• Slight drop in size Fri with E/SE-SE tending strong S-S/SW winds
• Smaller Sat with fresh S/SE-SE winds
• New, small, inconsistent W/SW groundswell Sun with E/NE tending S/SW winds

Recap

Light winds on Saturday morning offered a window of small, clean waves across the South West, tiny to the north while yesterday, strengthening onshore breezes created deteriorating conditions.

Today our large W/SW groundswell has filled in with poor conditions in the South West but surf in the easy 10-12ft range, 3-4ft Mandurah and 2-3ft Perth with workable cross-shore breezes.

This week and weekend (Dec 17 - 22)

Tomorrow is the pick of the period with the storm linked to today’s large swell clearing east allowing winds to swing offshore, fresh out of the E-E/NE ahead of relatively shallow sea breezes from about lunch time.

Size wise, there’s no real expected change to the outlook with the South West easing from 8-10ft with 3ft surf across Manduah and 2-3ft waves in Perth.

Wednesday will continue to ease and winds look to revert back to the S/SW as a trough clips the state, with early S-S/SE winds likely in Perth/Mandurah.

Our secondary, reinforcing pulse of W/SW groundswell for Thursday/Friday is on track, with the strong frontal progression linked to it, currently north of Heard Island generating various fetches of gales.

The progression will weaken on approach over the coming days but maintain some swell generating properties, extending the mid-period size into Friday.

The South West should see 8ft sets on Thursday, backing off to 6-8ft on Friday with 2-3ft waves in Mandurah Thursday, 2ft+ across Perth.

Local winds will remain poor Thursday and strong out of the S tending S/SW, cleaner Friday and more E/SE-SE as the swell drops a touch.

Looking at the weekend and less favourable S/SE-SE winds are likely Saturday with smaller surf, while come Sunday, an offshore wind and new, long-range groundswell should favour the South West. It looks only small to moderate in size, generated south of South Africa today and tomorrow, while a closer-range polar low should generate a good SW groundswell for Tuesday next week. More on this Wednesday.