Small windows for Perth and Mandurah, large and windy from Sunday
Western Australia Surf Forecast by Craig Brokensha (issued Monday 11th June)
Best Days: Perth and Mandurah Wednesday and Thursday mornings, Friday across the South West, early Saturday all locations
Poor onshore waves all weekend with a building NW windswell Saturday and larger W/SW swell on Sunday (workable for a period Saturday morning around Mandurah and Perth though small).
The swell eased back into this morning but with lingering onshore winds across the South West and better light offshore winds around Mandurah and Perth, easing from 3-4ft and 2-3ft in Perth.
This week and weekend (Jun 12 - 17)
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We'll see onshore winds across all locations tomorrow as the remnants of a strong low that formed over the weekend clipping the state.
Fresh W/SW tending SW winds will create average conditions as the swell continues to ease, building again into the afternoon as mid-period energy from the low starts to fill in.
This will be ahead of the long-period groundswell proper on Wednesday which should build to a good 6-8ft late in the day across the South West from 6ft early, 2ft+ to 2-3ft around Mandurah and Perth.
Winds look favourable and light offshore for Perth and Mandurah, while Margs unfortunately looks to linger onshore from the W/SW on Wednesday and now Thursday as well as the swell eases, which is a shame. Variable winds should again be seen in Perth and Mandurah as the swell eases from 2ft+ in Perth and 2-3ft Mandurah.
Cleaner conditions will be seen Friday across the South West as winds tend E/NE (possibly light N arvo) but the swell will be smallish and back to 4ft or so. Into the afternoon a new long-period SW groundswell is due, produced by a strong polar low that's currently around the Heard Island region.
The low won't last especially long, putting a cap on the expected size, and also making the swell inconsistent but a pulse to 4-6ft across the South West, but only 1-2ft in Mandurah and tiny in Perth.
A secondary stronger but smaller low will project a fetch of severe-gale to storm-force W'ly winds closer to us, producing another long-period groundswell for Saturday morning. Margs should see better 5-6ft+ sets with 2ft waves in Mandurah and 1-2ft sets in Perth Saturday morning with an early NE breeze that will freshen from the N/NE through the morning with an approaching mid-latitude trough.
From Sunday we're due to see large levels of W/SW groundswell developing across the state as a strong node of the Long Wave Trough in the southern Indian Ocean feeds a series of vigorous storms.
The tight intense low linked to Saturday morning's swell will be the first system developing under the LWT with a secondary broader system firing up south-east of Madagascar.
This should generate a large long-period W/SW groundswell for Sunday afternoon, with a broad W/SW fetch maintaining large surf into Monday before a sling-shot fetch of gale to severe-gale W/SW winds are projected towards us through the weekend, producing an XL W/SW swell Monday/Tuesday.
Unfortunately the storm itself will approach us bringing onshore winds from Sunday out of the NW, persisting Monday and swinging more W'ly into Tuesday. We'll have a closer look at this on Wednesday though.