South Australian Surf Forecast by Ben Matson (issued Wednesday 19th November)

Best Days: Thurs AM: small clean waves down south. Fri: small arvo lines on the Mid. Sat AM: good clean waves down south. Sun: building groundswell with very good waves expected on the Mid after lunch. Should also be fun down south too. Mon AM: may see light winds and the Sun's swell hanging around.

This week (Nov 18-22)

*Forecaster notes will be very brief this week as Craig’s away. Sorry for any inconvenience*

Some really nice waves along the South Coast today, and even yesterday morning offered some OK options (note: winds managed to veer N/NW in Victor Tuesday morning as per BOM obs, and Parawa was calm for a few hours at dawn, and under 10kts for the rest of the day, but Hindmarsh Island sees less influence from the regional topography and saw light S’ly winds that became moderate to fresh during the afternoon).

There’s also been some small lines along the Mid although at that frustratingly small size that looks workable from the carpark but terrible once you're in the lineup.

Anyway, we’ve got a good forecast period ahead. A small long period groundswell is due to hit the CdC buoy overnight (16-18 seconds), but the source of this energy was a long way away in our far swell window, so Thursday's surf size probably won’t really be much higher than the pre-existing, easing energy from today. Conditions should be OK down south in the morning with W/NW winds but a SW change is expected later. 

We may also see some small lines in the gulf on Thursday but winds are expected to tend onshore  - not too strong, mind - and I’m not confident for much more than an inconsistent 1-1.5ft on the turn of the tide. Might be worthwhile for a grommet though.

A secondary phase of the same weather system (responsible for the long period swell) has generated a small secondary groundswell that’s due to push through Friday. Winds should also tend light and variable under the influence of a slow moving high pressure system. We’ll see a small rise in average quality swell across both coasts, and I’m hopeful that the Mid Coast will push towards 1-2ft on the turn of the afternoon tide. Otherwise, there’ll be fun options down south.

Saturday looks good down south, especially in the morning. We’ll see an easing swell but a swing in the wind direction to the north, so conditions should be quite good. Surf size will probably be too small for anything noteworthy on the Mid but as always there’s likely to be consistent teaser lines. A trough is expected to cross the coast during the day and may bring about an onshore wind change but at this stage no great strength is expected.

Sunday’s where things start to get very interesting. The leading edge of a long period SW groundswell (18-20 seconds) is expected to arrive overnight Saturday, and build slowly through Sunday, having been generated by an intense low that formed east of Heard Island yesterday, and is expected to power through the swell window over the coming days. 

At this stage we probably won’t see the bulk of the swell early morning - more so from lunchtime onwards - but the storm track is modelled to hold steady through our prime SW swell window and I’m confident we’ll see a good kick along the Mid Coast to 2-3ft on the afternoon’s incoming tide. Furthermore, winds are looking pretty good at this stage, with light variable winds for the most part (we may see a sea breeze but at this stage I don’t think it’ll be very strong). 

This swell should also provide very good waves down south (and elsewhere across the state) but the westerly component in the swell direction will somewhat cap size at Victor. In any case it’ll be nice and clean in the morning before the sea breeze.

Sunday’s swell will persist nicely through Monday although it'll ease slowly during the day, and early indications are than winds will be favourable in the morning ahead of a possible cold front in the afternoon. 

Beyond this, there are even more fronts lining up for the South Australian coast for next week which suggests plenty of waves in most areas through the rest of the week. More on this in Friday’s notes.