Wide range of swell sources for the next week and beyond

Ben Matson picture
Ben Matson (thermalben)

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 20th August)

Best Days: Thurs/Fri/Sat/Sun: early window of OK conditions each day, with a fun combo of swells from the SE. Mon onwards: slowly building E/NE swell.

Recap: Lots of swell from the south, tending southeast but windy at times, also from the south. Winds did briefly swing W/SW early this morning across the Sydney basin but have otherwise been fresh S’ly.

This week (Aug 19-22)

We should see a steady improvement in surf conditions over the next couple of days, but also a slow drop in wave heights.

Today’s S’ly tending SE swell will throttle back to around 3-4ft at south facing beaches on Thursday (a little smaller at remaining beaches, but slightly larger in the Hunter) and winds should tend light and variable early morning. 

There’ll still be plenty of leftover lumpiness on the surface but we should see an improvement, ahead of a freshening S’ly tending SE breeze throughout the day. So aim for an early session.

In Monday’s notes I mentioned a new pulse of SE swell due around the middle of the day. This pulse has been delayed until very late afternoon, in fact I’m not expecting to see it arrive before close of business - so we’re likely to see a slowly easing trend for much of Thursday. 

Therefore, Friday morning will be the best time to capitalise on this new energy from the south-east. Wave heights should hold steady around 3ft+ at most open beaches, with bigger waves in the Hunter, and the wind regime is likely to be quite similar to Thursday - mainly moderate from the SE but with a reasonable period of light variable winds early (probably offshore, but perhaps too light to create a massive improvement on the surface). Early birds and their worms, and all that.

This weekend (Aug 23-24)

No major changes to the weekend forecast at this stage. A small but strong southerly fetch off the west coast of New Zealand’s South Island will generate a small refracted SE swell, and a polar low and front skirting the waters well south of the Tasman Sea over the coming days may provide some small long range southerly swell in the mix.

Otherwise the main source of new energy for the weekend is a broad but only moderate-strength easterly fetch occupying the northern half of the Tasman Sea, across the top of a high pressure system that’s modelled to develop in the southern Tasman Sea on Friday.

No major size is expected from either source but most open beaches should see peaky sets in the 2-3ft+ range both days. Light variable winds are expected all weekend under the influence of this high; probably light offshore in the morning and onshore in the afternoon but without any great strength.

Longer term (Aug 25 onwards)

All eyes are to the north for the long term period. The Tasman high is expected to remain slow moving, whilst a broad area of low pressure across the southern Coral Sea and Far SW Pacific squeezes a broad easterly fetch across the northern half of the Tasman Sea.

There’s even a suggestion that we may see the development of an easterly dip that - if it develops - could retrograde towards the East Coast (obviously aimed much better towards the Northern NSW and Southern Qld coasts). This could have the potential to supercharge the ocean state and deliver some sizeable surf to some regions.

This is quite an unseasonal synoptic pattern but nevertheless its slow moving nature is likely to be a good thing for East Coast swell production. As such all indications are that the southern NSW coast is on target for a full week of slowly building E/NE swell, with possibly a chance of an embedded pulse of solid NE swell mid-late week. I’ll have more on that in Friday’s update.