South Australian Surf Forecast by Ben Matson (issued Friday April 19th)

Features of the Forecast (tl;dr)

• Tiny to flat on the Mid this weekend
• Average waves down south this weekend with easing swells and abating onshore winds
• Good surf both coasts Mon and early Tues (tho' only small on the Mid) with new, building swells and light winds tending N'ly
• Tricky winds rest of the week but with solid swells Wed, Thurs and esp Fri
• Onshore winds (post-frontal) expected late Tues/Wed, easing by Thurs

Recap

Onshore winds have maintained poor surf across the South Coast, whilst it’s been too small to ride on the Mid Coast.

(Please note: FC Notes will be variable in delivery this week as Craig is on paternity leave and Steve is covering Margs)

This weekend (Apr 20 - 21)

No major change to the weekend outlook.

No new swell for the Mid means the only surfable options will be at Victor, and onshore winds - albeit easing - will persist here both days rendering surface conditions quite bumpy. Wave heights should ease from about 3ft at Middleton tomorrow down to 2ft on Sunday. 

We may see periods of only light wind strength at times (especially into Sunday afternoon), however we really need a stiff synoptic offshore for a few hours, to iron out the wobbles. This isn’t likely so expect lumpy leftovers at best, likely bumpy for the most part.

Next week (April 22 onwards)

We've got plenty of surf lining up for next week though we have a few days of tricky winds to contend with. 

First of all, a strong frontal sequence through the Southern Ocean right now will generate a sequence of new long period swells for Monday and Tuesday (favouring both coasts), before a better long period SW swell then arrives very late Tuesday and peaks Wednesday - generated by a polar low intensifying south of WA on Sunday. Again, this will favour both coasts for waves.

Finally, the last swell in this next pattern will arrive on Friday, generated by an intensifying polar low south of WA on Tuesday (see below) that will project nicely to the NE through the South Coast’s S/SW swell window into Wednesday, with the swell arriving overnight Thursday and showing best through Friday. However it’ll develop a little too far east of the Mid’s swell window to favour activity in the gulf.

The fly in the ointment this week is a small cut-off low that’s expected to shear off the frontal boundary early in the week and push into the SA coast around Tuesday, however the models are divergent on how it will evolve - the US solution has it tracking quickly through to the east, whilst the European solution has it moving more slowly, with a different alignment. 

Either way, Monday’s looking clean everywhere with light winds tending N’ly into the afternoon, and we should see small new groundswell lines filter into the Mid Coast, around 1-2ft on the afternoon’s incoming tide. Expect bigger waves to 2-3ft along the Middleton to Day Street stretch (note: confidence is low on size and timing from this swell, thanks to the unexpected unavailability of our model data today - I'll update over the weekend as new data comes to hand).

Tuesday should maintain Monday's pattern but I’m not totally confident on local winds right now so we’ll need to reassess on Monday. At this stage early northerlies are likely ahead of a gusty W’ly change late in the day.

The outlook for the rest of the week is also unclear - mainly due to local winds - but I feel that the Wednesday swell should produce 2-3ft surf in the Gulf, however conditions look like they’ll be wind affected with gusty SW breezes adding a little more windswell on top.

Otherwise, the South Coast should pick up plenty of swell from the Wednesday and especially Friday swell, probably somewhere around the 5-6ft+ across the South Coast. 

We still need a few days to iron out the local wind forecast though.

Let’s take a closer look on Monday. Have a great weekend!