Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Sep 24)

Forecast Summary (tl;dr)

• Small long period S swell Sat with a brief window of good winds early before fresh S'ly winds
• Stronger mid period pulse Sun, hampered by S to SE winds.
• Residual S swell Mon, with light morning winds
• Small S swell pulse Wed and Thurs with fresh N’ly winds
• NE windswell event from Tues PM, likely peaking Thurs
• Possible E’ly swell later next weekend into following week, depending on tradewind flow in South Pacific. Stay tuned for details

Recap

Yesterday saw easing surf across the region, with clean conditions offering up good surf in the 3ft range, bigger 3-5ft on the Hunter and a few select S swell magnets. As local Tasman sea generated S swell eases longer period S swell has filled in today. That’s led to a regime of 15-17 second period S swell with a wide range of wave heights across the region. S exposed beaches are offering up some chunky 3-4ft surf, with the odd larger set. The longer swell periods are seeing good refraction into more sheltered spots with plenty of 3ft+ sets. Conditions are clean with light morning W/NW breezes tending to NW winds through the day. 

This weekend (Sep 25-26)

Not much change expected for the weekend forecast. Weak high pressure is now drifting off sub-tropical NSW, with a light northerly flow across most of the state. A strong front and deep 965hPa low SW of Tasmania is poised to enter the Tasman sea, bringing a S’ly change tomorrow, with a high pressure ridge building in rapidly behind the change. 

Another long period S swell pulse is expected in tomorrow morning, albeit a notch smaller than today, but you’ll have to get your skates on before the S’ly change hits. Current modelling shows the wind change on the South Coast before dawn, with a window of offshore winds on the Illawarra and northwards before a mid morning change. There’ll be some 3ft sets on the exposed coasts, bigger 3-4ft on the Hunter, but once that change hits you’ll need to duck for cover.

Stronger mid period S swell does fill in behind the change, likely arriving later in the a’noon, so if you miss the morning there’ll be enough juice to warrant heading to a sheltered corner Sat PM. Size should rebuild into the 3-5ft range later in the day at exposed breaks, smaller in more sheltered corners. Expect plenty of S’ly wind in the strong wind range.

S’ly winds continue into Sun, although at a reduced level. A brief window of SW winds is possible, especially in the northern part of the Sydney basin but S’ly winds will be the order of the morning for most of the region. There’ll be plenty of S swell on offer though. The initial burst of short/mid period S swell should hold 3-4ft surf, before a stronger pulse rebuilds wave heights into the 4-5ft range through the late morning, lunch-time. Again, you’ll have to sacrifice size to find quality at more sheltered corners. The high pressure ridge does weaken as it moves north during Sun so expect an abatement of S’ly winds during the a’noon as they tend more SE then ESE which will open up a few more options for those who can handle some rough and tumble, but improving, surface conditions. 

Next week (Sep 27) and beyond

High pressure sits off the Central NSW coast during the early part of next week, with a following high located even further south, essentially suppressing the Southern Ocean storm track. The high then drifts East, with a dominant N’ly wind pattern becoming established until late in the working week.

Plenty of leftover S swell on Mon with residual swell trains likely to see 3-4ft surf at S facing beaches, bigger 4-5ft on the Hunter and easing through the day.

A light N’ly flow, possibly NW early, is expected to freshen during the day and this will herald the beginning of an extended N’ly episode.

Freshening N’ly winds Tuesday see the last of the Tasman Sea S swell bottoming out with NE windswell building through the a’noon. Models show this fetch “breathing” - contracting and expanding up and down the coast several times during the period Tues-Thurs next week and with the fetch so close to the coast this is likely to see several peaks and troughs in wave heights. The normal pattern is for a diurnal peak in windspeeds during the a’noon, which would put a peak Tues a’noon in the 2ft+ range, bigger 3-4ft on Wed and likely 3ft+ Thurs. We'll finesse these wave heights as needed on Mon but they won't be signifcantly different if you are organsing the week ahead.

Some small S swell is in the mix Wed, generated by a zonal, but strong front passing well to the south of Tasmania, probably not amounting to much more than some stray 2-3ft sets at S facing beaches. Another slight pulse is on offer Thursday, a notch smaller. 

Into the end of the working week and the end of the N’ly pattern is in sight as a mid-latitude cut-off low approaches Tasmania. There is some model disagreement but a wind change is likely next Sat, with potential for a small increase in swell from the low on Sunday. NE windswell Friday is likely to back down over next weekend. Expect revision on details.

Longer term and high pressure which drifted from the Tasman sea to straddle New Zealand will have set up a tradewind flow in the South Pacific next week. While this flow mostly benefits NENSW and SEQLD, the European Model strengthens the flow as a trough deepens through the far eastern Tasman Sea, suggesting some E swell later next weekend or into the early week beginning 3/10. 

With the long lead time we’ll expect major revision on that scenario. 

The south swell window looks to remain suppressed compared to recent activity into the end of next week. 

Check back Monday for a fresh, full analysis and have a great weekend.