No shortage of swell on target

Ben Matson picture
Ben Matson (thermalben)

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 29th August)

Best Days: Sat: best options in southern corners. Sun/Mon: solid, pulsey swell with great conditions. 

Recap: Large windy waves on Thursday with gusty S’ly winds and up to 6-8ft at exposed spots through the afternoon. Wave heights settled back to 4-6ft today and conditions were clean across the Sydney basin early under a light W/SW breeze, which have since swung to a fresh and gusty S/SW.

This weekend (Aug 30-31)

A few minor tweaks to make to the weekend forecast but the bigger picture remains much the same as we’ve been discussing side Monday.

A retrograding low in the central Tasman Sea is generating a strong renewal of SE swell that’s going to provide some large waves through Saturday. Model data has marginally upgraded and downgraded the strength of the fetch - and consequently, the resulting surf size - a couple of times since Wednesday, but it seems pretty well locked in on a peak somewhere between 6ft and possibly 8ft at exposed beaches. Protected spots (southern ends) will obviously be a lot smaller.

However the main concern for Saturday are the local winds. As the low tracks close to the mainland tonight, it’ll strengthen the pressure gradient across the coast which will ratchet up wind speeds from the S/SW. It’s likely that we’ll see a period of early SW winds at many beaches - possibly even W/SW on the Northern Beaches - however it won’t last long and the gusty winds will confine the best waves to sheltered southern corners (where it’ll be smaller).

By comparison, Sunday looks far better. Wave heights are expected to reach a peak on Saturday afternoon and will begin trending downwards overnight into Sunday morning. There’s still a chance for a few rogue 6ft+ sets early Sunday but for the most part we’re looking at clean 4-6ft surf easing to 3-5ft throughout the day, and moderate W/SW winds tending variable in the afternoon as the pressure gradient relaxes across the coastal margin.

In fact, there’s actually a chance for a new pulse of E/SE swell arriving sometime mid-afternoon, thanks to the development of a secondary E’ly fetch around the bottom of the broad parent system in the Tasman Sea on Saturday. Model guidance has really only just picked up this embedded feature in the last few runs, and as it’ll be working on an active pre-existing sea state, it shouldn’t take too much effort to generate some solid sets in the few hours before dark - don’t be surprised if we see a late pulse back up into the 4-6ft range at exposed beaches.

Next week (Sep 1-5)

Sunday’s late pulse of new E/SE swell is expected to persist into Monday morning before easing slowly during the day. Early morning should have some occasional bombs between 4ft and possibly 6ft at exposed beaches before we see an easing trend into the 3-4ft range throughout the day. Winds are looking excellent on Monday too - light to moderate NW - so all open beaches should have excellent surf on offer to kick start the working week.

From Tuesday onwards, the rest of next week returns southern NSW back to a typical pattern of frontal systems through the lower Tasman Sea. The biggest waves through this period are expected around Wednesday and possibly again on Friday with another burst of activity - but the models are a little divergent on how strong the fronts will be so I’m not confident to pin down size prospects yet. South facing beaches could see 4-6ft sets at the height of each pulse, however winds are likely to be fresh and gusty from the southern quadrant. Let’s take a closer look on Monday.

Longer term (Sep 6 onwards)

Similar frontal passages are expected through next weekend and beyond so the long term trend forward from next Saturday maintains a healthy period of southerly swell for the southern NSW coast. More on this next week.


Tim Bonython's picture
Tim Bonython's picture
Tim Bonython Friday, 29 Aug 2014 at 10:38pm