South Australian Forecast by Craig Brokensha (issued Wednesday April 10th)

Best Days: South Coast tomorrow, Friday, Saturday, Sunday and Monday morning, Mid Coast Tuesday

Features of the Forecast (tl;dr)

• Large S/SW groundswell for tomorrow with light local offshore winds ahead of weak sea breezes
• Easing swell Fri, slowed Sat by a reinforcing S'ly swell
• Similar, light local offshore winds ahead of weak sea breezes Fri and Sat
• Moderate sized, mid-period S/SW swell for Sun with N/NE winds ahead of weak sea breezes
• Easing swell Mon with variable tending S/SE winds
• Large S/SW groundswell Tue with SE tending S/SE winds

Recap

Freshening onshore winds made a mess of the South Coast yesterday with a bump in new swell to 4ft or so, while this morning conditions were cleaner with a weaker onshore breeze and sets still to 3-4ft. The Mid Coast was full yesterday morning though 1-2ft as the tide dropped out with wind affected waves for the keen, back to 1-1.5ft today.

This week and next (Apr 11 - 19)

Looking at the week ahead, and we've got a ton of swell due across the South Coast, thanks to a strong node of the Long Wave Trough setting up east of us while remaining near stationary. This will steer and strengthen polar storms up through our southern swell window over the coming week.

The first and at this stage, most significant of these formed yesterday, with it being a polar low. A great fetch of severe-gale to storm-force W/SW winds were generated through our southern swell window, with a large, long-period S/SW groundswell generated for tomorrow morning.

Middleton should come in around 6ft on the sets with bigger waves on the deepwater reefs, with the Mid Coast coming in at 1ft.

The swell will then ease into Friday from the 4-5ft range across Middleton, slowed into Saturday thanks to some reinforcing mid-period S'ly swell arriving late in the day Friday.

This will be generated by gale-force SW winds on the backside of the polar low generating the large swell and should maintain 3-4ft sets across Middleton Saturday morning, fading through the day. The Mid Coast will be tiny.

Looking at the winds and we should see light, local offshore breezes tomorrow morning across both regions, with weak sea breezes, keeping conditions decent most of the day down South.

Friday looks similar with variable tending light, local offshore winds ahead of relatively weak sea breezes, similar again Saturday. With this the South Coast looks great fun for the coming days.

Now, into later Saturday but more so Sunday, a reinforcing pulse of mid-period S/SW swell is due, generated by patchy fetches of strong to gale-force winds moving along the polar shelf over the coming days.

Middleton should pulse back to 3-4ft on Sunday morning, though less consistent, easing into Monday from 2-3ft.

N/NE winds will create great conditions Sunday morning ahead of weak sea breezes, variable Monday morning before winds tend S/SE as a trough moves through and a high follows.

We then look to our next pulse of sizey SW swell, with a strong, broad polar low due to fire up under the country on the weekend.

This will generate a great fetch of W/SW gales while slowly moving east, with a couple of favourable intensifications projecting up through our south-western swell window.

A large S/SW groundswell is due Tuesday, pushing to 6ft+ across Middleton and 1ft to possibly 2ft on the Mid Coast along with what looks to be SE tending S/SE winds. Unfortunately from Wednesday through the end of the week, winds from the southern quadrant looks to create average surf for the South Coast while favouring the Mid but with tiny, fading levels of swell. More on this Friday.