Series of strong south swells, with periods of good winds

Ben Matson picture
Ben Matson (thermalben)

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 17th August)

Best Days: Tues/Wed: solid S'ly swell, best early Wed. Later Thurs/Fri/Sat: solid long period south swell with N'ly thru' NW winds.

Recap: Conditions panned out much as expected over the weekend but wave heights came in a little bigger, generally 2-3ft all weekend across the Sydney region with larger sets reported in the Hunter and also at a few reliable south swell magnets on the South Coast. The same trend persisted into this morning, with the weekend’s southerly swell punching just above my expectations (which were itself higher than the model was estimating.. I didn’t go far enough!). A new SE swell seems to be filling into the coast (of a similar size, 2-3ft - see pic to right) but it hasn’t quite registered at the Sydney buoy yet - there was a faint spike at 1-2pm but otherwise the data is unconvincing. However the Crowdy head buoy (neat Port Macquarie) is detecting new long period energy from the SE on cue, so the observations from the Bondi surfcam seem to fit in with the expected new swell (we’re occasionally seeing some overlapping swell trains in the surf zone).  

This week (Aug 18 - 21)

The new SE swell I suspect is filling into the coast right now originated from a small cutoff low that formed off the West Coast of New Zealand’s South Island on Saturday. Unfortunately, we’re probably not going to see much more of it: with under half an hour until the sun goes down, it’s probably going to peak overnight, and Tuesday's surf will be overshadowed by a larger short range southerly swell.

This new south swell is being generated by a deep low and vigorous front that entered the southern Tasman Sea this morning. Strong S/SW winds pushing up into our south swell window have been well aligned for the last 24 hours, and we’re looking at a pretty solid swell event on Tuesday, probably somewhere in the 4-5ft range at south facing beaches with 6ft+ sets across the Hunter. This is a minor downgrade since Friday’s notes, owing to a slightly weaker fetch strength than previously modelled. Surf size will be much smaller at beaches not open to the south.

Tuesday’s winds look OK for the morning but we’re looking at a S/SW tending S’ly tendency from about late morning/lunchtime onwards. As such you’ll have aim for an early paddle when winds should be at least W/SW. Wave heights are expected to peak in the afternoon, so bear in mind that the morning’s cleaner conditions may be accompanied by slightly smaller surf. 

Wednesday’s looking really good overall, with light variable winds and a continuing south swell around 4-5ft at south facing beaches in the morning that’ll probably ease back slowly in size throughout the afternoon

The rest of the week looks pretty interesting too. A large high moving eastwards through the Tasman Sea will steer winds around to the north on Thursday and Friday (probably some periods of NW at times, but certainly not quite perfect) and a series of new southerly groundswells are expected to provide strong waves to finish the week.

Initially on Thursday morning we’ll be between south swells, with leftover 2-3ft waves at south facing beaches (bigger in the Hunter, smaller elsewhere) however new energy is expected to reach the South Coast by late morning and it should arrive across Sydney beaches mid-late afternoon before peaking in size early Friday morning

This swell will have originated from a broad, intense polar low moving slowly well below the continent (just off the ice shelf) and is expected to reach maturity on Wednesday morning directly south of the Tasman Sea. This should produce strong waves int he 4-5ft range at south facing beaches either late Thursday (if we’re lucky) or more likely Friday morning. The long periods associated with this swell should generate solid 6ft+ sets at some of the offshore bombies, and across the Hunter. However with winds out of the northern quadrant you’ll have to hunt down a northern corner for the best conditions. We may also see some small N’ly windswell in the mix too on Friday but I’ll have a  better idea of that in Wednesday’s update. 

This weekend (Aug 22 - 23)

It’s a reasonably simple formula for the weekend: persistent N’ly thru’ NW winds both days, a solid but slowly easing S’ly swell and some local N’ly windswell too.

At this stage Saturday morning should still offer set waves in and around the 4ft range at south facing beaches, with bigger bombs in the Hunter and smaller surf elsewhere. An easing trend should occur throughout the day. The N’ly windswell could be worthy of 2-3ft sets at reliable NE swell magnets, but I’ll have a better idea on that over the coming days.

Sunday should see a repeat of the N’ly thru' NW winds and windswell, but with easing S’ly swell around 2-3ft at south facing beaches, before becoming smaller into the afternoon.

Next week (Aug 24 onwards)

Nothing major on the cards for next week. Another cut-off low is expected to form west of Bass Strait over the weekend which suggests a continuation of NW winds early in the week across our region (with a small easing S’ly swell, and just some small local N'ly windswell).

As this system eventually clears to the east into the Tasman Sea early-mid week, we’ll probably see a return southerly swell build along the coast - but that’s still quite some time away and will require further evaluation over the coming days. 


Craig's picture
Craig's picture
Craig Tuesday, 18 Aug 2015 at 1:58pm

Tell you what, after a trip further afield over the weekend, water temps this morning on the Northern Beaches felt like a bath, 3 or so degrees warmer. Even compared to two weeks ago it has really warmed up.

Here's the reason and evidence, a fresh pulse of warm water from the EAC..

batfink's picture
batfink's picture
batfink Tuesday, 18 Aug 2015 at 9:32pm

Was fairly cool down where we were on the weekend Craig, but not too bad. Been in worse down south around this time of year.

That's an early arrival of warmer water isn't it? We only got the cold water 2 or 3 weeks ago in Sydney, and talking to one of the locals down there they said it got colder only in the past 3 weeks.

Fark it, I'm over winter. I enjoy the cooler months generally, as long as I can get away from Sydney, where the crowds are still ridiculous, but I've had enough.

And soon enough the doldrums of spring will hit us. Maybe we can get lucky and keep getting swell.

Was definitely bigger on the weekend than expected, with no real drop off in swell size over Saturday and Sunday.

Not sure how sydney fared though. Based on this I would say less than what we were getting.

geoffrey's picture
geoffrey's picture
geoffrey Wednesday, 19 Aug 2015 at 3:08pm

launched the boat at bellambi today and my observations were that the warm water wasnt anywhere to be seen to a depth of 50m (sounder only reads surface temp) although there is a little green sliver along the coast from around the national park south on that posted diagram.

Craig's picture
Craig's picture
Craig Wednesday, 19 Aug 2015 at 3:38pm

Yeah looks to be just further offshore down your way Geoff.

Sydney buoy has 19.4deg offshore, and Port Kembla 18deg.

thermalben's picture
thermalben's picture
thermalben Wednesday, 19 Aug 2015 at 5:00pm

Sorry guys, running late today as my internet connection(s) have slowed to a crawl (and I'm conveniently in a 3G blackspot too). Hopefully the Southern NSW forecast will be up by 6:30pm local time.

DeXtrus's picture
DeXtrus's picture
DeXtrus Wednesday, 19 Aug 2015 at 5:24pm

Thanks as always Ben. Always appreciated.

Craig's picture
Craig's picture
Craig Wednesday, 19 Aug 2015 at 5:33pm

Finally some swell with a bit of east in it on the way. Can't wait for the weekend's NE windswell and then follow up SE swell. Yew!