South Australian Forecast (issued Friday 21st January)
Best Days: Sunday morning, Tuesday morning for keen surfers
Wednesday's semi-stormy waves on the Mid Coast eased back from a tiny 1-1.5ft across yesterday with lighter and more variable winds creating clean conditions, but there wasn't much push in the swell.
The South Coast saw much larger waves out of the S/SW, coming in at 4ft across most locations but again fresh to strong S/SW winds created poor conditions.
Today the Mid Coast was even tinier but a stronger pulse of windswell and building S/SE groundswell is filling in across the South Coast, generated by a stalling mid-latitude low across Tassie yesterday (satellite wind observations shown below).
A fetch of 35-50kt S/SE winds were aimed towards us, generating a rare S/SE groundswell across the South Coast that should arrive this afternoon, peak overnight and ease tomorrow. Unfortunately winds have remained poor and fresh to strong from the S'th.
This weekend (Feb 22 - 23)
The satellite observations above show a peak in wind speed around the mid-latitude low sitting over Tassie occurring yesterday afternoon.
This will result in a peak in S/SE groundswell overnight across the South Coast, but the morning should still offer strong but inconsistent 3-4ft sets before tailing off steadily into the afternoon.
The Mid Coast won't see any of this swell due to its S/SE direction being more aimed towards the heel of the Yorke Peninsula if anything.
Winds will unfortunately remain poor and fresh from the SE, but again savvy surfers may be able to hunt out a wave or two.
Sunday should offer cleaner conditions with a mix of fading S/SE swell and new S/SW groundswell under an E'ly wind, but don't expect anything special above a peaky/lumpy 2-3ft wave at exposed spots.
Next week onwards (Feb 24 onwards)
There's plenty of S/SW groundswell expected next week across the South Coast as an amplification of the Long Wave Trough moves in from the west and intensifies over Tassie.
The Long Wave Trough is basically an upper atmospheric wave that focusses storm activity into a certain region, and can have up to five regions of amplification. The one focussing over Tassie will direct a succession of polar fronts up towards that state, one after the other creating back to back pulses of S/SW groundswell.
The first should arrive through Sunday afternoon and peak Monday morning ahead of a secondary pulse Tuesday and then third large increase Thursday/Friday (right), peaking probably just under model forecasts to 4-5ft across most locations on the South Coast.
Unfortunately a strong blocking high will move oh so slowly in from the west during next week bringing poor onshore S/SE winds from Wednesday through until next Saturday morning.
The Mid Coast will remain clean through the period but no size above 0.5-1ft is really expected.
Longer term we may see a strong but inconsistent long-range SW groundswell arriving next weekend, generated by a vigorous polar low moving in from the Heard Island region (pictured above). More on this on Monday though.