Remaining strong from the S/SE, though easing
Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 20th January)
Features of the Forecast (tl;dr)
- Large, easing swells Thurs onwards
- Light winds before lunch Thurs, briefly Fri AM
- Fun weekend of waves though a little wind affected Sun
- Lots of tropical potential long term
Recap: Well, it’s been an interesting couple of days to say the least. On the whole, a major under-performance from the expected south swell, both in arrival (not reaching the South Coast until late Tuesday, overnight in Sydney) and also in size, with many coasts coming in significantly smaller than forecast. However we’ve had intermittent reports throughout the day - seemingly without any kind of obvious pattern or geographical trend - of bigger surf reaching 6-8ft at some locations (and bigger surf at offshore bombies), but it’s fair to say that broadly speaking, we haven’t seen anything near what was expected. Of course, the big question is why? Ususally, when hindcasting major non-events, it’s possible to see gaps in the forecast methodology, and areas where (perhaps) general assumptions glossed over important characteristics that - with 20/20 vision - resulted in an erroneous forecast. However this event is unusual, in that given the opportunity to forecast again, I probably wouldn't deviate much from the previous script. This swell was first noted in these notes nine days ago, and the models held very consistently throughout, so confidence was high - finally validated in the ASCAT satellite pass that confirmed the size and strength of the storm. However, we have a few ideas as to what went wrong - but, such analysis is better left to an individual report, which we’ll try to prepare in the coming week.
This week (Jan 21 - 22)
One of the difficulties in preparing a forecast at a time like this, is trying to seperate the events of the last 24 hours from what’s expected over the coming days.
Although we’re in the midst of a tricky, week-long cycle of solid, overlapping southerly swells, today’s under performance doesn’t necessarily have a bearing on the swell potential from the latter stages of the same parent low, as it maintains strength off the SW tip of New Zealand’s South Island. Of course, confidence may be somewhat diminished - but we shouldn’t necessarily downgrade the next two days proportionate to what occurred (or more accurately, didn’t occur) today.
And, as it were, Thursday and Friday were both meant to offer the better waves of this event anyway (the exact phrase in Monday’s notes was “The backside of this swell looks the pick anyway”, and last Friday’s notes said “In many ways, despite the easing trend, Thursday and Friday may end up offering the best quality swell energy of the whole period”).
So, what can we expect?
Firstly, surface conditions will be a heck of a lot better. A high pressure system will move across the region, bringing light variable winds for most of Thursday ahead of afternoon sea breezes from the NE. Friday will see persistent moderate to fresh N’ly tending N/NE winds as a Tasman high strengthens a little, but there’ll be a window of light N/NW winds early morning, offering the best conditions of the day (get in as early as you can).
As for surf, we’ll see the swell direction slowly swing to the S/SE. Model guidance has an easing trend from today into tomorrow, but I'm ignoring the initial trend because the energy from the next few days will be sourced from two new regions - the migratory path of the low across the Southern Tasman Sea, as well as some sideband S/SE groundswell from the core of the low off the NZ coast today (see below).
Although the low is now not aimed ideally within our swell window, the sheer length and breadth of the fetch - plus the strength of the core winds - should allow for 5-6ft sets throughout Thursday (bigger at offshore bombies and across the Hunter region, near 6-8ft), though as per usual surf size will be a lot smaller at beaches not open to the south.
We usually allow 36-48 hours travel time from these kinds of systems in this neck of the woods, so given the current fetch was active as of this morning, strong sideband S/SE energy should persist into the early hours of Friday morning. A brief window of light N/NW winds on Friday should be accompanied with occasional 4-6ft sets at south facing beaches (bigger across the Hunter around 5-6ft+), easing steadily to 3-4ft through the day, but with much smaller options elsewhere as per the usual directional caveats.
Yes, this is bigger than the model is estimating, but it's a common occurence with cut-off lows in the south-east Tasman, so I'm reasonably confident we'll see strong - though increasingly inconsistent - surf for the enxt two days.
Expect conditions to become bumpy through Friday afternoon at beaches without protection from the north. There’ll also be some building NE windswell through the day too, though no major size is expected.
This weekend (Jan 23 - 24)
There’s no change to the weekend outlook.
Though, I gotta say - an acute source of long period south swell for Sunday - from a poorly aligned low southwest of Tasmania from tomorrow onwards - is way more flukier than the source that generated today’s energy. So, let’s just say this won’t be a high confidence event.
Nevertheless, Saturday’s on track for easing S/SE energy from today, with inconsistent 2-3ft+ sets at south facing beaches, smaller elsewhere, and easing through the day. A small NE windswell should maintain peaky 2-3ft sets at exposed north-facing beaches.
Local conditions look pretty good with a weak trough disrupting Friday’s synoptic northerly flow, in fact there’s a risk of a brief S’ly airstream on the South Coast - and then a late redeveloping NE breeze north from the Illawarra. But for the most part winds should be light and variable.
Sunday’s looking windy with the N/NE breeze restrengthening as the trough moves south, and this should build peaky NE windswell into the 3ft range. Additionally, the aforementioned long period S’ly swell is expected to make landfall, and south facing beaches should see inconsistent 3ft sets, with an outside chance for a handful of reliable south swell magnets (such as the Hunter) picking up bigger waves in the 3-5ft range.
The blend of swells should create some nice A-frame up and down the coast but local conditions are looking a little average at this stage. I’ll take a closer look on Friday.
Next week (Jan 25 onwards)
The deep Southern Ocean low responsible for Sunday’s swell will migrate very slowly eastwards through our south swell window, so it’s looking like we’ll pick up fluctuating levels of small long period S’ly tending S/SE swell through the first half of next week. At this stage Monday and Tuesday could both see intermittent 3ft sets at south facing beaches.
Additionally, the N/NE fetch immediately off the coast on Sunday will remain in place for a few days so we’ll concurrently see small levels of local NE windswell too (2ft, maybe 3ft). Though, conditions will be at risk of the associated N/NE winds.
Otherwise, the long term outlook is still looking very positive from a tropical point of view, with broadening trades through the weekend and into next week (generating small though building E/NE swells), and the evolution of a a tropical low in the central/northern Tasman Sea during the first half of next week that has the potential for a significant E/NE groundswell during the middle to latter part of next week.
Quite a dynamic summer, eh?
See you Friday!