Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Sep10)

Forecast Summary (tl;dr)

• Small S swell Sat, easing Sun with favourable winds both mornings
• Small, (low quality) local S swell Mon with winds turning fresh S’ly
• Stronger S swell Tues hampered by fresh S to SE winds
• SSE swell potential Wed/Thurs possibly sizey, revisions likely
• ESE swell potential Fri into the weekend depending on formation and movement of Tasman low, stay tuned for revisions

Recap

It’s been a dizzying array of swells over the last week but we are now on the backside of a long period S swell pulse that saw solid surf at S facing spots yesterday. Hunter coast saw a barrel fest with 5-6ft waves and offshore WNW winds, surf graded smaller in the Sydney basin with 3-5ft surf on offer, although some select deep water reefs had bigger surf. Today surf has eased back into the 2-3ft range across most of the region, with some bigger 3-4ft waves on the Hunter. Conditions were clean early with a shallow trough bringing a weak S/SE change around lunchtime. All in all a super fun wind down day after an intense week of surfing.

This weekend (Sep 11-12)

The weekend is tracking along similar lines as suggested in Wed’s notes with no major changes to the f/cast. Current ASCAT (satellite windspeed) passes show the passage of front through the lower Tasman, and models confirm this passage is rapid, which leads to a duration limited fetch, although the breadth and length of the fetch is substantial. So keep expectations in check, this is a bog standard S pulse, topping out around 4ft+ on the Hunter, 3ft at S facing beaches in the rest of the region. Winds look fine for the early, tending NW, with high-res wind models suggesting hot NW to N winds may continue through the day. A late, coastal NE seabreeze is possible so keep eyes on local wind obs.

With the next front pushing through on Sun, early NW winds should tend WNW, then W, before a SW change arrives with the front during the a’noon. Don’t expect much size on Sun, early will be biggest with S swell leftovers in the 2ft range and this will drop down during the day, bottoming out and giving us the smallest surf we’ve seen for a while under W’ly winds through the a’noon.

Next week (Sep 13) and beyond

Next week looks quite dynamic (again!) and even though there is still some model divergence which will require revision on Mon the basic pattern is now becoming clearer as we follow trends across the major weather models.

The activity will be in the Tasman Sea, for the most part.

Monday's outlook is pretty ordinary. The passage of the front leaves a lingering S’ly flow and this is quickly strengthened by high pressure ridging in from a strong high tracking south of Victoria. This high will become slow moving as it straddles Tasmania and a major synoptic feature next week. 

A deeper fetch from the front which passed on the weekend produces a pulse of S swell which arrives later Mon but by this stage fresh S’ly winds and local windswell will make for diminishing returns on open stretches despite size in the 3-4ft range by close of play. Sheltered corners will remain small  due to low swell periods.

The onshore flow from the S through SSE continues Tuesday as the strong high maintains and strengthens the ridge along the NSW coast. There’ll be a mix of swell trains from the S, with easing slightly longer period S and dominant short period S to SSE. Expect fresh S to SE winds so options will be limited.

Tuesday is where model divergence becomes apparent. A SE/NW angled trough in the Tasman is likely to deepen on Tuesday, possibly forming a surface low. GFS model has this low forming off the Central NSW coast, intensifying the onshore flow on the southern flank of the low and seeing rising levels of short range SE/ESE swell later Tuesday.

EC forms a low much further north in the Tasman, close to Norfolk Island, with a very different surf outlook from Tuesday onwards. 

Despite these different outcomes the common asset is the large high slowly drifting east from Tasmanian longitudes towards the South Island, with SE winds being directed through the Tasman Sea. 

This will give us SE swell through the second half of next week. 

Under the GFS scenario we’re likely to see a solid building trend Wed as the low winds up in a favourable position east of the Central NSW coast, depending on windspeeds and position, in the 4-5ft range during the day, larger 6ft+ at S facing beaches, with continuing S’ly winds. This swell slowly eases a notch through Thursday.

The EC scenario sees much smaller SE swell through Wed/Thurs, with a possible increase late Fri and into the weekend as the low fires up near the North Island and generates ESE swell for NSW. 

Despite the model uncertainty the end of next week and into the weekend looks active with SE/ESE swell and likely easing winds as an approaching high brings a weaker pressure gradient. 

There will be revision as models come into alignment so check in the comments for updates over the weekend and Mon for a fresh, full analysis.

Have a great weekend.