South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Monday 21st December)

Features of the Forecast (tl;dr)

• Northerly-wind affected surf on Tuesday, though improving in the a'noon on the Mid North Coast
• Light winds early Wed ahead of a developing S'ly change
• Underlying E/NE swell from TC Yasa all week, biggest late Wed/early Thurs (though a size downgrade from Friday's notes)
• Local (and then diffracted) S'ly swells for Northern NSW later Wed thru' the weekend
• Sand pending, should be good options on the points from Wed PM onwards - though inconsistent
• Average weekend ahead, aim for Saturday

Recap: E’ly swells maintained 3-4ft sets over the weekend, easing into Sunday afternoon but then rebuilding a little today with what appears to be the early stages of cyclone swell from TC Yasa. The weekend’s winds were a little funky with freshening northerlies ahead of a southerly change that pushed into the Mid North Coast Saturday morning, reaching the Northern Rivers by lunchtime (not quite getting past Evans Head) but then retreating into the afternoon, allowing for an arvo glass-off across some coasts. Sunday saw the northerly resume in a few locations, creating bumpy conditions. Today’s seen much lighter winds across most of Northern NSW, though northerlies did develop across the Northern Rivers after lunch (SE Qld saw these winds come up a little earlier and a little fresher, from the NE). The E’ly swell doesn’t seem to have pushed much higher than about 3ft+ today but it is noticeably more defined. 

A little more definition in the E'ly lines across the Tweed River today

This week (Dec 22 - 25)

Before we get into the cyclone swell outlook, there’s been some local synoptic developments in the models since Friday that have our short term focus. As such it’s looking like a half-day of gusty northerlies on Tuesday (almost a full day north from Byron) which will spoil local conditions. These winds should generate 2ft+ of peaky windswell for exposed north facing beaches along the southern Gold Coast and parts of Far Northern NSW though don't expect any quality. 

A complex coastal trough off Southern NSW is expected to be a more dynamic event than expected a few days ago, and it’ll mainly favour Southern NSW from a surf perspective. The main effect on our region will be to stall an expected southerly change until Wednesday afternoon, so prior to then Wednesday morning - and even Tuesday afternoon south from Yamba - should see favourable conditions as the winds relax to become light offshore, then fresh S’ly by Wednesday early afternoon (earlier throughout the Mid North Coast). 

In fact, gale force S/SW winds stretching out from the Southern NSW coast (see below) should generate some useful though very acute southerly swell for our region, along with S’ly swell from a brief Tasman low forming mid-way between Tasmania and New Zealand later Tuesday and into Wednesday. This low looks impressive in single synoptic snapshots but it ultimately rotates too quickly through our swell window to be of any major size benefit.


Anyway, the combined southerly swell episode - building Wednesday, easing Thursday - should nudge 4ft at south facing beaches south of Byron but it’ll be generally accompanied with fresh winds from the same quadrant, so conditions won’t be great at those locations picking up the swell. We will see winds abate rapidly south from Yamba on Thursday though so the afternoon session could actually be reasonably clean along the Mid North Coast. Easing S’ly swells are then expected into Friday.

Anyway, that’s enough waffle about peripheral systems. How about the cyclone swell?

Well, all the while this is going on, we’ll also have an undercurrent of (relatively) long period swell originating from TC Yasa, which pushed south of Fiji overnight Friday and is still active way out north of New Zealand right now (see below).

In Friday’s Forecaster Notes I detailed a few things I liked about Severe TC Yasa, and a few things I didn’t like - and it turns out that the weekend’s ASCAT (satellite) confirmation of the surface wind field wasn’t as favourable as I’d hoped for. Winds were very strong around the cyclone but the best quadrant was the SW, which was aimed up into the Coral Sea. The SE quadrant - which typically has the E’ly thru’ E/NE fetch - didn’t have a lot of support from the ridge to the south, so it wasn’t particularly long. And, it's a long way from the mainland.

As such I’m slightly tempering my forecast from this cyclone though I’m still holding steady with the timing on the swell - which is for a long lived event from today through Friday, but with a peak in size sometime later Wednesday or early Thursday, which should push 4-5ft at exposed beaches, smaller on the points. Otherwise, expect occasional 3-4ft sets at exposed beaches on the surrounding days.

Tying this in with the wind outlook and with fresh S/SE winds across SE Qld and Far Northern NSW at the peak of the swell (late Wed/early Thurs) means the points will be your best option - and the jury is still out on the state of the sand at many locations. Bearing in mind though that a good blow from the south-east should improve the situation, so expect wave quality to evolve from day to day.  

Also! Sets will be rather inconsistent owing to the large travel distance - and this is NOT a favourable characteristic for the regional points, which are crowded at the best of times - but even more so in and around the Christmas holiday season. So, don't paddle out expecting to rack up a high wave count, eh?

A smaller mix of swells are then expected on Friday (inconsistent 3-4ft open beaches, smaller on the points) with early SW winds across many regions tending moderate S/SE north from Byron throughout the day, but not gathering too much strength along the Mid North Coast. So, there’ll be stacks of waves around for a Xmas surf.

This weekend (Dec 26 - 27)

An inland trough is expected to swing winds to the east on Saturday and then north-northeast on Sunday, ahead of a brief spell of poor northerly-affected conditions from Sunday afternoon thru' Monday. 

As for surf, Saturday looks the pick as we’ll see easing E’ly swells across all coasts (2-3ft open beaches Saturday, 1-2ft Sunday) plus a small level of S’ly swell at south facing beaches south from Byron. This will have originated from a reasonable front/low south of Tasmania mid-late week; core winds never really get much above 30kts so there won’t be a lot of strength or consistency in the swell, but the entire Southern Ocean from Tasmania to the Antarctic Ice Shelf will be under its influence by late Wednesday through Thursday (see below) and this should maintain 2-3ft sets both days.

Anyway, make the most of Saturday as Sunday’s looking a bit craptacular right now. 


Next week (Dec 28 onwards)

More coastal troughiness for early next week suggesting local NE windswells and fleeting south swells. Nothing significant on the radar though, especially from our much-loved eastern swell window.