Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Wednesday 7th July)

Forecast Summary (tl;dr)

• Light winds and a couple of south swells Thurs/Fri, easing Sat
• Complex low off the coast Fri, building E/SE swells throughout Sat, but with tricky winds
• Sunday looks best with light winds and punchy though easing E/SE swell, smaller Monday
• Spell of small surf Tues-Fri
• Decent S'ly swell prospects next weekend onwards under a LWT pattern

Recap

Easing E/NE swell from the trough block maintained 4-5ft sets on Tuesday, easing to 3-4ft this morning and 3ft this afternoon. Conditions have been clean with light winds. A small south swell has also been present through the day, though an expected pulse of bigger south swell appears to be running a little behind schedule.

Manly this morning

This week (July 8 - 9)

No real synoptic wind is expected for the next couple of days, so anticipate light variable conditions for Thursday and most of Friday. Note: 'variable' means 'from any direction', which could be onshore - though it's unlikely (and won't have much strength if it crops up).

As for surf, we'll see a continuation of slow easing E/NE swell from the Trough Block, becoming very inconsisent too - rare 2-3ft sets Thursday, barely 2ft Friday. We're at the point where this energy will be more of a bonus than a priority, so don't work around it and keep your expectations low.

However, we do have some new south swell building across the coast from a series of fronts that pushed underneath Tasmania over the last few days. Yesterday's small S'ly was from a related front pushing through eastern Bass Strait (though, a different swell source); but I'm waiting for swell periods to kick up to 14-15+ seconds to herald the main swell from the primary low, of which we should see 3-4ft+ sets at south swell magnets early Thursday, pushing 4-5ft+ across the Hunter. Wave heights will then ease through the day.

Expect long breaks between the bigger sets, and much smaller surf at beaches not directly exposed to the south.

Another south swell is expected on Friday from a trailing polar low well to the south; we should see size boost back into the 3ft+ range at south facing beaches, smaller elsewhere though pushing 4-5ft across the Hunter region. Again, beaches not open to the south will be much smaller.

This weekend (July 10-11)

Friday's south swell is expected to ease into Saturday. 

As mentioned on Monday, we have a complex setup approaching on Friday night, with a coastal trough expected to develop a small Tasman Low before dawn Saturday. 

This low will be cut off from the westerly flow, and won't have much of a southerly fetch on its western flank - its strongest flanks are expected to be its northern (i.e. W'ly winds) and south-eastern (i.e. E'ly winds), though the latest model guidance has swung in our favour - shifting the track of this low over the weekend, now more to the E/NE and at a slower speed, allowing an E/SE fetch on its southern flank to become a decent swell producer. 

However, retreating lows are not as advantageous for size prospects (compared to stationary lows of a comparable strength), though there will be benefits: the threat of poor winds will be brief at best (most likely Saturday, probably the middle of the day).

So! Current expectations are for small residual swells at dawn on Saturday, but building rapidly from the E/SE into the afternoon as early W/SW winds swing fresh to strong S'ly but then ease into the afternoon. Wave heights should reach 4-6ft by late afternoon.

Sunday looks much better with slowly easing E/SE swell from 4-6ft to 3-5ft, and light variable winds. 

I'll fine tune the details in Friday's outlook.

Next week (July 12 onwards)

The long range guidance is still suggesting a broad zonal flow across the mid-latitudes next week, so the outlook remains subdued for swell prospects with no major swell generating systems expected in the Tasman Sea (for now). 

Passing frontal systems well to the south should maintain background energy at south swell magnets but for the time being, it looks like much of next week - apart from Monday, which will see slowly easing E/SE swell from the weekend - will deliver a quiet period of surf. 

Looking further ahead and the Long Wave Trough is expected to amplify across the Tasman Sea later next week, so next weekend is on target for a strong south swell.

More on that on Friday. See you then!