Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 16th December)

Features of the Forecast (tl;dr)

• Plenty of fun beachies Thurs/Fri, a little wobbly at times but quite workable
• Weekend outlook: average conditions Sat AM though with plenty of E/NE swell, better Sun with light winds
• Long period NE cyclone swell should start arriving as early as Sun but will be a slow grower through early next week
• Strong round of cyclone groundswell still on the cards from Wed thru' Fri

Recap: Building E/NE swells pushed a solid 6ft or more on Tuesday afternoon, and onshore winds were only light to moderate for most of the day so conditions were quite workable. Wave heights have eased back today from 5-6ft down to 3-5ft, and the onshore breeze watched up a little more this morning, averaging 15kst at most coasts and gusting 20kts at times. 

This week (Dec 17 - 18)

No major changes to the outlook for the rest of the week.

There won’t be any shortage of swell, with a peaky combo of E/NE trade swell (from a broad ridge across the Northern Tasman and South Pacific) and short range NE swell (from a local fetch off the Mid North Coast) maintaining 3-4ft sets at most open beaches. 

A trough will move in from the south on Friday ahead of a late gusty S’ly change, though Thursday will see a continuation of N/NE winds as per today. We should see a slow easing through the day, but there’s likely to be some leftover lumps and bumps through the morning, so keep your expectations low.

Friday morning looks rather OK actually, as winds should tend light NW (or variable), allowing conditions to clean up. The S’ly change is due into Wollongong between 4-6pm (give or take) so at this stage it’s looking like almost a full day of reasonable waves across Sydney and Hunter coasts.

This weekend (Dec 19 - 20)

S’ly winds trailing Friday’s late change will dominate Saturday morning, but it won’t be terribly strong and will ease through the day. So expect the first half to be wind affected at exposed beaches - generally north from Sydney - and then a lumpy, improving afternoon. Sunday should see better conditions with light variable winds and sea breezes. 

As for surf, we’ll see a slow but steady round of E/NE trade swell over the weekend, generally 3ft or so at most open beaches but with long breaks between the sets. 

A small S’ly swell will fill in behind Friday north’s change (i.e. or Saturday morning) but I don’t think there’ll be much size in it. 

Also over the weekend - but of very low confidence - is the chance for the leading edge of NE swell from TC Yasa. It’ll just be faint forerunners with swell periods of 18-19 seconds, but this has the potential to throw up a few rare 2-3ft sets - possibly very late Saturday, slightly better chance at times throughout Sunday - but I really wouldn’t bank on there being too much size, as the enormous travel distance coupled in with the short fetch length and only partial gap in the swell shadow between Fiji and New Caledonia, means it’s more likely to be hit than miss. 

Still, if you see Tp values shoot up at the buoys, this will be the source. 

Next week (Dec 21 onwards)

A weak trough off the coast on Sunday may evolve into a small Tasman Low Monday, but I’m still not expecting much, if anything from it.

And anyway, all eyes are on TC Yasa.

At this point in time, with this kind of timeline forecast, we can start to become more confident in the model guidance as it irons out long range aberrations and starts to consolidate across the other solutions. 

And… it’s a little nerve-racking to watch this play out from day to day, but right now there’s no need for a downgrade, if anything we’re looking at an upgrade (as tipped in Monday’s notes). TC Yasa is expected to properly exit the swell shadow on Friday, pushing slowly south towards New Zealand, then recurve back to the west. It’s an incredible storm track, which, if it eventuates, will generate an exceptional long period cyclone swell event for the entire East Coast. 

I’m still not confident on size and timing, but right now, Monday should see a prominent increase in long period energy with size likely to build from 2-3ft up to 4ft+ through the day, and we’ll then see overlapping swell trains through Tuesday, peaking from Wednesday thru’ Friday in the 6ft+ range at exposed beaches. I really can’t rule out the chance for much bigger  surf - it’s simply to early to be floating numbers north of 8ft, even though gut feel says it could very well happen.

So, let’s see what Friday’s model updates have in store, eh? Certainly shaping up to be a tasty period of Xmas swells. 

See you then!