Developing Tasman Low to dominate Thursday onwards
Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 8th December)
Best Days: Tues: fun leftover NE swell in southern corners (winds will be out of the south). Thurs: tricky winds but there should be a small NE swell in the water, with the possibility of a late increase in new swell from a Tasman Low. Fri/Sat/Sun: solid SE swells but dicey winds at this stage. Next week: some great potential on the cards.
Recap: What a tidy run of waves! Small building NE swell Saturday that increased further through Sunday and peaked this morning with solid 4ft sets at exposed beaches. Winds were generally light north of Wollongong for much of the period, although Saturday saw strengthening E/SE winds on the South Coast as a low briefly developed offshore (this also added a small SE swell to the mix). Sydney buoy data is showing a steady easing trend although the Manly cam still has easy 3ft sets.
This week (Dec 9th - 12th)
The fetch responsible for today’s NE swell is weakening across the western Tasman Sea, so we’re looking at easing NE swells through Tuesday.
Early morning should still have 2-3ft sets at NE facing beaches (smaller at south facing beaches, and in the northern Hunter) and although a gusty overnight S’ly change is expected to ease rapidly in the few hours before dawn, we may see a lingering southerly flow across open beaches for a few hours around dawn (changes for a light SW flow are minimal, and likely to occur at only a handful of spots).
As such, southern ends will offer the best waves as they’ll pick up the most size and offer some protection from any lingering strength in the wind. By mid-late morning winds should be light and variable at most locations. However, the overnight southerly change won’t kick up much in the way of new swell, just a weak foot or so of low quality windswell. Expect smaller, less consistent surf from the NE through lunchtime and into the afternoon.
A weak secondary front traversing the southern Tasman Sea behind Monday’s change (into Tuesday) will then maintain small levels of south swell for Wednesday, whilst residual E/NE swell from the weekend’s trade flow across the northern Tasman Sea should keep remaining open beaches with a foot or two of inconsistent surf. Early light N/NW winds are expected to tend NE and freshen considerably through the afternoon as another trough envelops the coastal strip.
This developing trough looks like it will finally break the recent pattern of persistent NE winds and swells. A small low (low chance of an ECL, but let’s wait and see) is expected to form somewhere within the trough in the early hours of Thursday morning, but the timing is not agreed upon across the model runs right now so we need a high degree of elasticity in the forecast.
Thursday’s surf will therefore mainly consist of peaky short range NE swell (2ft, maybe 2-3ft NE facing beaches, smaller elsewhere) but as the low winds up we’ll see a building short ranger E/SE swell.
Local winds are also tricky for Thursday because we’ll see a wide range of strength and direction - south of the developing low’s axis it’ll be gusty E/SE, but north of the axis - at least temporarily, until the low slides away from the mainland - there’s likely to be an outflow from the W/SW (and maybe even NE prior to this). Current model guidance has this happening around Sydney/Hunter beaches but let’s wait for Wednesday’s updated data.
This E/SE swell is expected to become the dominant factor through the end of the week as the low broadens and moves north-east, taking shape in the central Tasman Sea. Regardless of the divergent model guidance, Friday is like to finish with sizeable short range SE swells and gusty SE winds (lighter on the South Coast).
Also worth mentioning is a small SE groundswell due in the mix on Friday, originating from a small low modelled to form off the SW tip of New Zealand’s South Island. It’ll be buried under the short range noise but at locations such as the Far South Coast - where local winds will be much lighter - could provide some reasonable lines of groundswell in the 2-3ft range.
This weekend (Dec 13th - 14th)
We’re assured of surf this weekend, that’s for sure. But quality is another question altogether. The Tasman Low looks like it’ll remain a firm synoptic feature through this period, with a broad SE fetch stretching north-west from New Zealand’s West Coast up into the southern Coral Sea.
This will generate strong SE swells for Saturday at least - easing through Sunday - but local conditions look like they’ll be bumpy with moderate onshore winds. By Sunday we should see a rapid improvement however surf size will probably be dropping (some other models focus the low as a strong cut-off system, generating strong swells for the entire weekend, but I’lm less confident that this will occur).
Let’s give it a few more days to firm up the specifics but right now it won’t be too hard to find something fun and punchy, even if you have to sneak into a southern corner on Saturday to escape the initial bumpiness.
Longer term (Dec 15th onwards)
Next week has some really interesting possibilities. The latest model guidance is showing a deepening E/SE fetch off the West Coast of New Zealand’s North Island over the weekend, one of my favourite swell windows (see below).
It’s still quite a long shot but right now there’s a reasonable chance that we’ll see a solid long period E/SE groundswell pushing through early next week (say late Monday, or early Tuesday) in the 4-6ft range at most open beaches. I’ll take another pass at this in Wednesday’s update, but for now the long term period through the weekend and early next week looks very active for all East Coast surfers.