Sydney Hunter Illawarra Forecast by Steve Shearer (issued Mon August 11th)

Features of the Forecast (tl;dr)

• Small blend of E and S/SE swells Tues/Wed with light winds, tending light S’ly Wed
• E-E/NE swells perk up a notch Thurs with some building short range S swell and freshening S’ly winds
• Small bump in E-E/SE swell possible Fri 
• Small S swell pulse Sat, stronger Sun as fronts push into Tasman
• Chance of a much stronger S swell Mon into Tues as low develops in Tasman
• Low confidence next week as unstable Tasman may throw up low pressure or even black nor-easter set-up
• Expect revisions due to troughiness so check back Wed!

Recap

E’ly swells were basically rinse and repeat over the weekend with size in the 3ft range both days (just a tad down on Sun) and glassy, semi-clean conditions in the morning before winds kicked up onshore through the day. More of the same this morning with size just down a notch, a bit of S/SE swell also in the mix, and light morning land breezes trying to smooth out some residual lump and bump before S-SE winds kick back in. Definitely not what is expected in August.

Not great quality but a few fun waves over the weekend

This week (Aug 11-15)

As noted on Fridays forecast another unseasonal low pressure system formed off the QLD coast over the weekend and has now drifted over to a position roughly equidistant between New Caledonia and the North Island. A large high sits well down in latitude (south of the South Island) for this time of the year, with a moderate E’ly fetch through the South Pacific slot. Pressure gradients are easing short term as the New Zealand high drifts away but we have another strong high currently moving through the Bight expected to bring S’ly winds with a chance of a low pressure trough forming in the Tasman in advance of the ridge. Frontal activity looks to follow closely behind bringing S swells over the latter part of the weekend. Once again, we’re in a position of enhanced instability in the Tasman and Coral Seas with models really struggling to resolve the troughiness. It’s likely we’ll see more E’ly swells medium term although with model skill so impaired we’ll need to accept lots of short term revisions as we move through the week. 

In the short run, we’ll see the current ridge more fully relax through tomorrow with morning land breezes tending to light S/SE breezes before they fully lay down to weak, variable breezes in the a’noon. A small blend of E and S/SE swells, one from the top of NZ and the otrher from the borrow will supply fun beachies in the 2-3ft range. 

Lovely calm winds for Wed as we reach a slack point between the major high pressure systems. That should see light morning offshores persist right through the morning into lunch-time before a light S’ly flow kick in as a weak trough develops in advance of the next high pressure ridge. Not much surf expected- just a weak signal of S/SE and E swells to 2ft on the open beaches.

S’ly winds increase Thurs as a weak trough of low pressure and high pressure combine. Both systems now look to weaken quickly with the low dissipating and the high moving east and weakening through the day. Small E’ly swells from the low on top of New Zealand perk up into the  2-3ft range and we’ll see some  minor short range S swell likely build to similar dimensions through the a’noon as mod S’lies develop.

Winds should shift more offshore Fri as a frontal system approaches from the interior. Expect a W to W/NW flow, possibly tending NW or even N’ly through the a’noon. There is an expectation the trough which moved offshore Wed/Thurs will develop further in the Tasman Fri (see below), potentially offering a small kick in E’ly swell through the day. We’ll finetune that timing on Wed. Nothing major expected just a bump from 2ft to 3ft or so but we’ll see how it looks Wed.

This weekend (Aug 16-17)

Lot’s of action on the charts as we move into the weekend but most of it looks to only have minor impact on surf size. A front sweeping up the coast brings a fresh SW-S change Sat, with early NW tending W winds and small E/SE-E swells in the 2-3ft range building in the a’noon from the S. Just a bog standard short range S swell to 3ft expected at S exposed breaks at this stage. 

A reinforcing front and small low coming in behind Sat’s front looks to freshen winds from the W-W/SW Sun with another flush of S swell expected in the 3ft range. We should also see some E swell in the mix from the low pressure trough which developed in the Northern Tasman Fri before being whisked away to the E. That system looks good in snapshot so any slowing of eastward movement could see an upgrade. Presently, we’ll pencil in 3ft from the E. 

Next week (Aug 18 onwards)

The weekend’s fronts and lows look to consolidate early next week into a much stronger system, backed by a strong high in the Bight. Good odds we’ll see S’ly gales develop off the NSW southerly coastline Mon, with a strong response in the form of robust S’ly swells developing through the a’noon, provisionally up into the 4-6ft range at S facing beaches. 

Size then looks to hold into Tues before easing as the low moves away and winds lay down as high pressure moves over NSW. 

Plenty of uncertainty after that. 

GFS has suggested we may see a deep trough form off the NSW North Coast or SEQLD region with a strong E/NE-NE infeed into it - a version of a black nor-easter. Latest runs have gone off the idea but we’ll flag it for now just in case it does eventuate. 

EC has a more conventional, conservative outlook with the high lingering in the Tasman and low pressure slowly weakening as it drifts over New Zealand. We’d see fun, easing S through SE swells under this scenario. 

A very dynamic outlook for mid-August, so expect revisions and check back in Wed to see how it’s shaping up.

Seeya then!