South Australian Forecast by Craig Brokensha (issued Wednesday 12th December)

Best Days: Mid Coast late Friday, keen surfers South Coast early Sunday

Recap

Lumpy and wobbly though slightly improving surf through yesterday morning on the South Coast, tiny and clean on the Mid Coast. Today the Mid is flat, while the South Coast has cleaned up further with Waits and Parsons offering the best waves.

Winds are due to swing more W/NW ahead of a shallow W/SW change late afternoon, strengthening into the evening as a new pulse of SW groundswell starts to show. If all goes to plan the Mid Coast should see 2ft sets by dark, with 3ft waves off Middleton but with bumpy conditions.

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This week and weekend (Dec 13 - 16)

Later today's SW groundswell is expected to hold into tomorrow morning around a similar size to this evening. That being 2ft on the sets across the Mid Coast and 3ft off Middleton, but this will be hidden under a developing S/SW windswell.

A deepening surface trough that's currently moving in from the west (bringing later today's change) will deepen into a broad and powerful low, stalling across Victoria and NSW through the end of the week and start of the weekend.

We're due to cop the full brunt off the lows western flank, with strong to gale-force S/SW winds moving in tomorrow and being projected up and into us through early Friday morning.

This will produce victory at sea conditions into Friday, developing from tomorrow afternoon. The Mid Coast will see stormy waves out of the S/SW building through tomorrow and reaching 3ft+ into the afternoon, 3-4ft Friday morning.

Strong to gale-force winds will create very poor conditions, but later in the day we're likely to see the lows axis shift slightly westward, bringing S/SE winds to the Mid Coast. This will create improving and easing surf for the late session, likely back to 2-3ft on dark.

Into the weekend the low will slowly weaken but remain to our east, with lingering onshore S/SE tending S/SW winds across the South Coast and moderate levels of easing S'ly windswell.

The Mid Coast will be cleaner tiny and easing from 1ft+.

We may see a period of early W/NW winds around Victor Sunday morning, but swell wise, we're only looking at a leftover S'ly windswell to a weak 2ft to maybe 3ft.

Into the afternoon a new long-period SW groundswell should start building, peaking through Monday.

The storm has already formed around the Heard Island region, with a fetch of severe-gale to storm-force W/SW winds being generated. The low is expected to broaden slightly while weakening a touch to the south-west of WA, breaking down once south of that state Friday.

We should see Middleton building to an easy 3ft later in the day, 1ft+ on the Mid Coast ahead of a peak Monday morning to 3-4ft and 1-1.5ft respectively. Winds look average and out of the S/SE, but we'll confirm this Friday.