Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wednesday 4th August)

Forecast Summary (tl;dr)

• Minor long range E/NE swell Tues, increasing fractionally Wed/Thurs (not significant with major S swell in the water).
• Building S'ly swell Wed PM (after dark), peaking Thurs with chance for some strong sets, size holding Fri morning before easing.
• Fun residual S swell Sat with light winds, easing through the day.
• New mid period S/SSE swell pulse Sun PM/Mon with some wind to work around.
• SSE swell slowly eases Tues next week with N’ly winds developing.

Recap

Tuesdays N'ly windswell supplied fun sidewinders with running lefts at open beaches with a NW tending W'ly wind keeping things clean. Newcastle’s open beaches seemed to make the best of it. In addition there was a small trace of longer range E'ly swell and some stray S swell late arriving from an expected swell Mon. It all added up to some small fun clean waves across the region before the afternoon tide killed it.

Today the energy has dropped back as the N'ly windswell and S'ly swell drop out of the mix. Long range E swell is offering a few sub 2ft waves, just rideable at open beaches. Our expected S swell looks to be running a bit behind schedule with an arrival now well after nightfall, so cool your jets for the late thought it wouldn't hurt to put a weather eye on your local S magnet on dark.

This week (Aug 5 - 6)

We’re in the starting blocks now for the imminent S swell event. Looks like we’re running around 6-10 hrs later in terms of timing compared to Mon’s forecast. Gabo Island - a good proxy for fronts pushing through Bass Strait- didn’t see W’ly gales until the wee hours this morning, with winds tilting WSW from 7am and maintaining gale force strength up to time of writing.  

Otherwise we are on track for a solid S swell event with a  complex double-headed low forming E of Tasmania through today, with an impressive pressure gradient squeeze from a large elongated high moving into the SW of the continent.

The delayed start works to our advantage really with the swell filling in during nighttime hours and the first pulse fully developed by daylight tomorrow. No change to the size prediction, a good chunky 4-5ft at places with S swell exposure, with Hunter Coast seeing a more solid 4-6ft with the better alignment for a straight S swell generated close to the NSW coast. Classic SW winds being generated by the outflow of the low along the Northern flank should maintain clean conditions though the Hunter might see a little surface noise from the southerly component in the wind.

Friday still looks good to great too. As mentioned on Wednesday a series of SW fetches slingshot up around the complex low and a secondary fetch which extends further south from Tasmania overnight Wed/early Thurs is expected to provide another strong pulse, probably filling in later Thursday over the initial pulse. This pulse should hold well into Friday morning and with slightly more fetch length and a tiny bump in period it could well provide some sets in excess of 6ft where the appropriate bathymetry can make the most of the size despite the acute S'ly angle. S facing beaches and deep reefs are likely to see even bigger sets Fri morning. Expect smaller surf away from southerly exposures. Offshore winds keep it clean and they are expected to lay down in strength during the day as the low moves away. The trend will be down during Fri and the easing trend sets in during the late morning so if you’ve got aspirations to get the biggest of the swell, keep the early Fri well and truly on the radar. Light seabreezes are possible to close out the working week as pressure gradients in the Tasman sea ease adjacent to the NSW coast.

This weekend (Aug 7-8).

Quite a substantial upgrade in size later this weekend, with some caveats for tricky winds. Read on for details.

Saturday will have some fun waves on offer, with leftover S swell and some small refracted S swell from continuing WSW to SW winds out of Bass Strait on Friday. Models aren’t much interested in the flukey Bass Strait source fetch but I reckon it will keep S exposed beaches ticking over with fun surf. 3ft+ surf in the morning should be whisper clean under a light/mod W’ly flow with a light N’ly to NE Seabreeze offering up some options in the a’noon for magnets up and down the coast. Expect that size to drop back into the 2-3ft range during the a'noon.

Sunday now looks a different beast compared to Wednesdays forecast. A small trough Sat east of Tasmania separated from the polar flow forms a compact low that super-charges another SW fetch of severe gales that tracks aggressively NE into the central Tasman overnight Sat into Sun. While the winds are still not perfectly aligned the NE movement into the Tasman into an already active sea state is expected to generate another strong pulse of S swell later Sun, tending more SSE through Mon.  Size is expected in the 4-6ft range at S’ly exposed breaks, grading smaller into more protected spots.

Winds look to be an issue with the low and front generating a S’ly change up the NSW coast and mod/fresh S’ly winds during Sun. That will likely force a trade-off between size and quality during with both wind and swell from the same quadrant.  Southerly winds should back down during the day as a new high pressure ridge builds in behind the change but winds are likely to stay from the SE through E later Sun. 

Next week (Aug 9 onwards)

We start next week with plenty of SSE swell from the just mentioned low which becomes slow moving as it drifts towards New Zealands west coast. That sets up a much “longer tail” for the swell event as sideband energy from this slow moving system tracks back to the East Coast. That suggests a very slow easing trend with 3-5ft by close of play Mon, easing further into the 3ft range during Tuesday. Northerly winds will start to freshen as a high moves into the Tasman off the Central NSW coast and an approaching frontal system tightens the gradient. That could lead to potential NE windswell Wed, although we’ll have to keep eyes on that in the next few days.

Longer term and a series of complex polar lows and cold fronts marshall their forces in the southern Ocean next week- it's a very active looking pattern- with a series of fronts expected to arrive Thurs 12/8, accompanied by a deep polar low. At the moment fetches look quite zonal (W-E oriented) but the polar low has a chance of a rare deep southern Ocean SE fetch aimed back at the Tasman sea if it remains on track to become slow moving between Tasmanian and New Zealand longitudes.. All this suggests more S swell by next weekend. More on this in Fridays forecast, hope you get a few from this S swell.