Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Sep3)

Forecast Summary (tl;dr)

• Chunky NE windswell Fri , holds Sat, easing rapidly Sun AM.
• ENE tradewind swell builds into Sat, pulses at low levels through next week though overshadowed by stronger S’ly swells
• Large S swell builds (late) Sun PM, strong Mon, easing Tues with fresh S'ly winds
• Longer period S swell fills in Wed, eases Thurs
• Easing surf Fri
• More S swell next weekend, stay tuned

Recap

Mixed bag since Wed with small levels of E/ESE swell from the Cook Strait source providing some 2-3ft surf yesterday, with increasing NE winds during the a’noon scuffing up open stretches. Today has seen a mix of easing E swell and building NE windswell as pre-frontal N’ly winds freshen across Central and Southern NSW. All up providing some scrappy, but surfable 2-3ft surf, becoming predominately NE windswell. 

This weekend (Sep 4-5)

Still a very dynamic cocktail of wind and swell events ahead for the weekend with lots of moving parts so lets dive in and try and make some sense of it. 

An incredibly strong high pressure cell (1043 hPa) near New Zealand is driving a dominant N’ly flow through the western Tasman sea adjacent to the NSW Central and South Coast, and this flow is being enhanced by an approaching front and trough which extends from the Southern Ocean into the Pilbara. 

This freshening N’ly flow is building NE windswell in the inshore waters and the duration and strength of these winds is producing quite a strong NE windswell. Models show this flow extending through tonight and into tomorrow, possibly even extending N’wards along the coast later Saturday. That gives good confidence of chunky NE windswell building into the 3-4ft range overnight Fri and extending into Sat, with leftovers on Sun morning. It’ll be short period, short range energy, but plenty of it.

Fresh N’ly winds will be on offer right through Sat, before easing into Sun morning and tending more NW to W, with a period of lighter NW winds inshore early on Sat. 

Also in the water Saturday we’ll start to see better quality ENE swell from the broad E’ly fetch coming off the top of the huge New Zealand high pressure cell. To be honest this fetch looks better on models than it does on the latest ASCAT (satellite windspeed) passes and with dominant NE windswell being replaced by strong, local S swell later Sun, if may not be as strong a signal as we’d expect. 

Nonetheless, 2-3ft sets from this source, are expected to fill in Sat PM, and boost a notch during Sun as period bumps up. 

This is complicated by the trough moving offshore Sat, and forming a closed surface low early Sun morning. Initially, this should see winds tend W, then SW as the low winds up. S’ly winds are more likely on the South Coast, extending up to the Illawarra during Sun morning. As always with these close range coastal systems, slight differences in timing and positioning can make big differences in local wind conditions. Be ready to rumble Sun morning as the low begins to wind up. By Sun PM, expect wind speeds to really start to ramp up from the SW. A late kick in new S swell is possible, but more likely after dark. We’ll update in comments below as the situation unfolds over the weekend.

Next week (Sep6) and beyond

OK, another incredibly dynamic week ahead next week.

By Mon morning the Tasman sea will be inflamed with severe gale to potentially storm force winds, as a robust low and reinforcing cold front push into the lower Tasman. Essentially this system looks like a little brother to the last slow moving Tasman low. The localised, proximate fetch of severe gales late Sun will whip up a large, stormy S swell Mon, with the reinforcing cold front fetch boosting wave heights during the PM hours. Size should be a couple of notches below what we saw close to a fortnight ago- this fetch is more compact and mobile,  but we’re still expecting S swell to push up into the 6-8ft range during the day, bigger 8ft+ on the Hunter and more exposed spots. Expect much smaller surf away from those very exposed spots. This will be another directional, close range S swell with a big range in wave heights. Fresh SW winds will tend SSW to S through the day, so you’ll need to find some shelter and lose size to get any quality on Mon. Tradewind swell will pad out the protected spots with inconsistent but good quality 3ft+ surf on the sets.

Tuesday sees tons of strong surf from the S, though down on Mon’s peak. With the low moving away towards New Zealand and another cold front pushing out of Bass Strait, there’s good odds of a morning offshore flow , cleaning up stormy 6ft S swell  and producing a good to great morning of surf before winds clock around to the S through SSE through the day. In addition, there’ll be some slow easing and inconsistent ENE tradewind swell in the mix, with sets in the 2-3ft range. 

By Wed another strong high starts to nose into the region, bringing light offshore breezes and a’noon seabreezes, conditions should be primo. A complex mix of swell trains is in the water Wed. S/SSE swell from the weekends low and longer period S swell generated by a deep polar low passing under Tasmania late Mon/Tues morning, with seas in excess of 30ft being generated. While the fetch isn’t aimed directly into the Tasman Sea pipe, long period swell trains with plenty of deepwater energy are expected to push wave heights back into the 4-5ft range Wed PM. Easing E swells will also be in the mix (is there anything that isn’t!).

The end of next working week looks to settle down, but there will be lots of residual leftover swell trains in the water, courtesy of both the active fetch in the South Pacific, which will have been contracting E’wards from the start of the week and the Southern Tasman, which maintains a very active pattern of fronts and lows passing through next week. 

Given that caveat, and the revisions that could flow from it on Mon, Thurs and Fri look to have lots of small, fun waves with good winds on offer. Thursday should have a mix of inconsistent E swell in the 2-3ft range, with reinforcing S swell in the 3ft range. Light WNW to NW winds look likely, with a’noon seabreezes. 

Friday eases further and looks the smallest day out of the current f/cast period with a mix of E and S swells topping out around 2ft and a general light offshore synoptic flow expected as a cold front sweeps across Bass Strait and the state. 

All in all, a very surf filled week with tons of options on offer. 

Longer Term and more S swell is on the radar for next weekend (10/11 Sep)  as a persistent node of the long wave trough steers low pressure into the Tasman. Models are offering divergent outcomes for next weekend but it looks likely a small feature pushing into the Tasman Fri generates S swell Sat, with a larger pulse due either Sun or Mon. 

Our very active start to Spring looks set to continue.

Check back Mon for the latest and have a great weekend.