Western Australia Surf Forecast by Craig Brokensha (issued Wednesday 16th December)

Best Days: Thursday morning, dawn Friday in the South West and morning in Perth, exposed swell magnets in the South West Sunday morning, later next week

Recap

Clean small surf in the 3ft range across the South West yesterday morning with tiny waves to the north up in Perth.

Today a new SW swell is building across the South West, coming at a bumpy 3-5ft this morning with onshore S/SW winds, while Perth wasn't expected to see much in the way of size with average 1ft sets.

This week and weekend (Dec 17 - 20)

Today's pulse of SW groundswell should peak around 4-5ft in the South West and 1ft+ in Perth, but a better W/SW groundswell is due to fill in tomorrow, peaking Friday morning.

Exposed breaks in the South West should reach 4-6ft through the day with Perth building to 1-2ft through the afternoon, holding a similar size Friday while Margs offers better 5-6ft sets.

Fresh SE winds are due across the majority of locations tomorrow morning ahead of S/SW sea breezes in Perth and S'ly winds across the South West.

Friday should be clean with E'ly offshores around Perth, with light early SE winds around Margs (possibly E/SE) but an onshore SW'ly is due to develop mid-late morning so don't dawdle.

We should see the surf easing back further through Saturday from 4-5ft around Margs and 1-1.5ft up in Perth but with unfavourable and fresh to strong S/SE tending S/SW winds.

Late in the day across the South West we may see some short-period SW swell on the build, ahead of a better S/SW groundswell Sunday morning.

This will be related to a deepening mid-latitude low right off the south-west tip of the state during Friday and Saturday morning, aiming a tight fetch of gale to severe-gale SW winds through our swell window before tracking east through the Bight.

Exposed breaks to the south swell should see good surf in the 5-6ft range early Sunday before easing rapidly through the day and further Monday. More protected breaks will fail to see much size due to the acute southerly direction of the swell. Perth isn't due to any real size either with 1ft+ waves due through Sunday.

Conditions are looking great in the South West as a ridge of high pressure quickly slides in overnight Saturday resulting in fresh E/SE tending E'ly winds ahead of afternoon sea breezes.

Next week onwards (Dec 21 onwards)

Early light winds are expected on Monday, most likely offshore but with no real swell in Perth and a fading S/SW swell from 2-3ft max around Margs.

I've finally got some promising news on the swell front.

A strengthening node of the Long Wave Trough is forecast to move in slowly from the west during the weekend and across us during early next week.

With this we should see a series of strengthening polar fronts directed through our swell window one after the other, producing some decent groundswell pulses from mid-late next week.

The largest pulse at this stage is due later Thursday and Friday in the 6-8ft+ range across the South West, but let's have a closer look at this on Friday.