Troughy pattern with a few small swell sources ahead

Steve Shearer picture
Steve Shearer (freeride76)

Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Mon 20th Nov)

Features of the Forecast (tl;dr)

  • Easing S swells Tues with some small NE windswell 
  • Workable NE windswell Wed with S’ly change
  • Small blend of S and SE swells Thurs with onshore winds
  • Small blend of S and SE swells continues into Fri with onshore winds
  • Small mixed bag of S/SE-SE swells Sat, continuing into Sun with some developing NE windswell
  • Another troughy, unstable week next week with potential for SE swell (onshore winds likely)


Workable waves over the weekend, if a little uninspiring. Sat saw a mix of S’ly quadrant swells to 2-3ft for the most part, a notch bigger on the Hunter with light morning winds providing clean conditions. A notch smaller on the Sunday, around 2ft across most of the region, with bigger surf on the Hunter. The S’ly quadrant swells were helped along by a small signal of E/NE swell. Long period S swells were showing on the southernmost MHL buoy (Eden) by close of play Sun and this morning is seeing some strong, long period S swells across the region with S facing beaches in the 6-8ft range and some bigger outliers. Lighter N’ly winds are now tending N/NE and freshening with some NE windswell expected through the a’noon. 

Strong S'ly groundswell making landfall on the Hunter

This week (Nov 20-24)

Weak high pressure is in the Tasman with an unstable troughy air mass in the interior and along the coast with a  N’ly flow across most of the Eastern seaboard as winds off the top of the high feed into the trough. Another high pressure system well below the continent approaches at Tasmanian longitudes late this week with a frontal intrusion prior to it’s entrance into the Tasman Sea offering up some modest S swell. The troughy pattern remains installed into the medium term so we’re still keeping an eye out for short range features which could supply local swell sources.

In the short run, todays long period S swell tails off through tomorrow with some sets early to 3-4ft at S facing beaches, a notch bigger on the Hunter easing off through the day. We’ll see some more NE windswell to 2-3ft in the a’noon. Tricky winds tomorrow as a potential trough moves off Jervis Bay and drifts north through the day. An early NW-N flow may trend more W or variable through the day with a light E’ly flow in the a’noon. This is far from set in stone though with small oscillations in the trough likely to cause wind changes across the region. Keep tabs on your local wind obs if you can.

We should see a S’ly flow Wed, potentially lighter SW inshore early before tending S/SE through the day. Not much quality is expected with some leftover NE windswell to 1-2ft in the morning and mostly short range, short period S swell trains building through the a’noon, not exceeding 2-3ft at open, S exposed beaches. 

A small trough of low pressure looks to linger off the NSW Central or Mid North Coast on Thurs, maintaining an onshore S/SE-SE flow and with a localised fetch generating small swell from the same direction. Not much size or quality expected but we’ll pencil in size into the 2ft range, possibly a notch bigger depending on how the local fetch aims up.

Similar conditions for Fri, although winds should clock around by degrees from E/SE to E during the day. That short range SE-E/SE swell should maintain at least 2 occ. 3ft surf. S swell from a passing low and frontal intrusion Wed/Thurs looks uncertain. GFS has a slightly stronger fetch but we’re only looking at a small S swell of similar magnitude and with an onshore flow it doesn’t look anything to get frothed about. 

This weekend (Nov 25-26)

Not a great deal to get excited about this weekend. High pressure slips into the Tasman and we’ll see a N-NE flow become established. Light NW Sat morning before winds kick up through the a’noon. 

We’re likely to see a small mixed bag with some S-S/SE swell from the remnants of the front tracking towards the South Island. A small blend of SE-E/SE and S swells to 2ft on the open beaches will be the size of it.

Not much more on Sunday with a similar small blend to 2ft and slight uptick in NE windswell through the a’noon, unlikely to exceed 2ft under current modelling.

Next week (Nov 27 onwards)

More of the same tricky, troughy outlook next week. 

The week should start small with a N’ly flow.

A trough forming off the South Coast is likely to bring a S’ly change Tues.

From then on, models are all over the shop. We may see the trough develop and move north with another round of localised SE-E/SE swell from winds between the trough and an advancing high. 

Low confidence in specifics due to the changeable mature of these short range features.

Check back Wed and we’ll see how it’s shaping up.


Skeggs_McFinn's picture
Skeggs_McFinn's picture
Skeggs_McFinn Monday, 20 Nov 2023 at 8:07pm

I find the forecaster notes are consistently good. Generally very accurate considering the changing nature of synoptics when calling things a few days out.
But whatever model is being used on the numerical surf forecast graph is sorely lacking. It had a 1.3m 7s NE windswell as the dominant train this morning over a 0.9m 19s South swell? It was (and still is) saying 2-3ft S swell when it was a pumping 6ft+? It did a similar thing not long ago with a long period S swell. Is it too much to ask for a model that can work it out?

thermalben's picture
thermalben's picture
thermalben Monday, 20 Nov 2023 at 8:26pm

Totally agree, however we didn't create the wave model, nor do we have the ability to make any fundamental changes to the underlying physics. As such, all wave model forecasts (read: websites) are in the same basket, consistently undercalling distant, long period south swells (in NSW), amongst other flaws.

Spudmelon's picture
Spudmelon's picture
Spudmelon Monday, 20 Nov 2023 at 10:51pm

Could you add a forecast wave height based on Swellnet's interpretation of the model/s?

thermalben's picture
thermalben's picture
thermalben Tuesday, 21 Nov 2023 at 5:48am

It's tricky to do so, because we have 2,500 forecast locations worldwide, that have 16 days forecast time-steps, and are updated four times per day.

Yes, we can pare this down - for example, we could choose a small number of locations to manually update, only provide (say) the first 5 forecast days, and only update three times per week.

But in what format? Written text, a secondary graph, etc... there are lots of options.

As you can imagine, this will add more work to the forecasting bench each day, so it's gotta be manageable. Because these south swells are not common events.. most swells are accurately predicted by our surf model.

But... we are working on a solution for this.

Nick Gee's picture
Nick Gee's picture
Nick Gee Tuesday, 21 Nov 2023 at 5:32pm

i'm good with those South swells being undercalled every now and again... after missing a few of them decades ago, i've been able to spot most of them over the last 20 years. remember one about 15-20 years ago that was generated waaaaay below NZ, almost to the East.. near dead flat ocean but every 15 minutes or so a couple of decent lumps would come through on South magnets. i bet a few fishos got swept off their local rocks.

sean killen's picture
sean killen's picture
sean killen Tuesday, 21 Nov 2023 at 4:38pm

Great peaky sess this arvo scored a few gems 3-4ft