Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Mon Jan 13)

Features of the Forecast (tl;dr)

• Small average NE swells Tues/Wed with winds from the same direction
• Large S'ly swell building Thurs/Fri but very windy
• Secondary E/NE swell building Fri
• Large combo of S'ly and E'ly swell for the weekend, though likely to be windy
• Large though easing SE swell during the first half of next week with rapidly improving conditions

Recap

Small E/NE swells padded out most open beaches with peaky 2ft sets over the weekend, whilst light winds maintained clean conditions. Surf size has built a little more from the NE overnight, with this morning offering 2-3ft sets under early light winds. 

This week (Jan 14 - 17)

Main features on the synoptics this week are an approaching front from the west, a strong high just west of New Zealand and and a deepening surface trough in the northern Tasman Sea - the latter of which will feed additional moisture into an already-evolving dynamic setup.

The short term outlook isn’t very inspiring though we will see waves as NE winds freshen along the high’s western flank, adjacent to the Mid North and Hunter coasts, maintaining short-mid period NE swell across exposed beaches in Southern NSW.

Winds won’t be terribly strong so we won’t see a lot of size, but swell magnets should ebb and flow between 2ft and almost 3ft at times on Tuesday and Wednesday. 

Local winds will be up from the same quadrant (N/NE) so surface quality won’t be great, and we may see water temps cooling a few degrees in response to localised upwelling.

Thursday is where things really become juicy.

The approaching front will push into the Tasman Sea overnight Wednesday, driving gale force southerly winds the length of the East Coast - eventually stretching from Tasmania up into Queensland’s Capricorn Coast.

The southerly change is due into Sydney around dawn, so there’s a chance for a brief window of early offshore winds north from the Central Coast (though we’ll revise this thinking in Wednesday’s notes). Either way, Thursday will be mainly dominated with gusty winds from the south and rapidly building surf size from the same direction. 

South facing beaches should push into the 6-8ft range by the afternoon though quality will be poor, however we’ll also see the swell period draw out during the day so protected southern corners and regional points should have smaller, cleaner options after lunch.

Similar conditions will then persist through Friday, if anything a little more size and certainly quite a bit more strength is likely as a Tasman Low starts to take shape to our east. Local winds are unlikely to improve very much so the only rideable options will once again be at very sheltered locations. 

Note: late Friday we’ll also see an underlying secondary E/NE swell from a fetch developing in the northern Tasman Sea mid-week. Ordinarily, a fetch of this nature would produce fun 3-5ft sets across the region but it’ll probably be hard to notice beneath the large, short range energy from the south.

This weekend (Jan 18 - 19)

A developing Tasman Low on Friday will mature into a multi-centered system over the weekend, maintaining large waves and windy conditions across exposed coasts.

There are a couple of interesting features to examine, that are highly relevant for surfers. 

First up, we may see the low retrograde to the west, which could eventually allow gale force southerly winds to ease in strength, and steer around to the SW or even W/SW.

The timing on this scenario is not yet clear - earlier model runs suggests this might happen on Sunday, but the latest runs have pushed it back to Monday or maybe even Tuesday - but given the windy conditions expected later this week, it’ll be worth eyeing upcoming windows of improvement as the sea state will otherwise be a terrible mess for a while. 

Secondly, whilst most Tasman Lows often display a single, broad wind field on its south-western flank (with direction often covering every degree from the S/SW through to the E/NE), in this instance it looks like the early stages of this developing Tasman Low may have two singular swell trains - one from the east and one from the south.

Given the expected windswell noise (from the local southerly gales) this may be a moot point, but there could be benefits for surfers from two distinct, narrower swell energies, rather than a singular event from an overly broad range of size, period and direction. Truth be told, I’m not really sure either way - but it’s a discussion worth having in advance.

As for size, expect 8ft+ surf at south facing beaches Saturday easing to 6ft+ on Sunday, with a solid E’ly swell in the mix (maybe 4-6ft), likely to be wind affected for the most part under gusty southerlies.

This is a complex scenario, so expect some revisions in Wednesday's update.

Next week (Jan 20 onwards)

Current expectations that the Tasman Low will remain active in our swell window until at least next Wednesday, though it should weaken through the first half of the week. Also, we’ll see the aforementioned fetches consolidate into a more typically broad SE flow too, which will result in a smaller southerly component (in the swell direction). 

More importantly, winds should ease and swing offshore early in the week so this time frame is currently earmarked for the best waves from this expected lengthy swell event.

In short - don't get too hung up about later this week, or even the weekend. Yeah, there'll be plenty of waves around but you'll have to do some legwork - but I much prefer the look of next week for Southern NSW.

I’ll have more details over the updates later this week.