Analysis: Autumn retrospective

Craig Brokensha
Swellnet Analysis

Year on year the seasons seem to be shifting later and later. Longer lasting warmth from summer into autumn and then autumnal weather into early winter.

The autumn just gone has followed the trend with it being the fourth warmest on record Australia wide (with maximums coming almost 1.75 degrees above the 1961-90 average), and the warmest ever in Sydney. Sydney saw more than double the normal number of days above 25 degrees through autumn.

It seemed like the endless summer until the recent spate of cold wind and weather bought that to a slightly shocking end.

Surf wise, considering it is usually one of the more active times to chase swells, it was a fairly sporadic and lacklustre season across most of the country.

The reason for this, especially into the last month of autumn (May) can be represented in the figure just below.

This shows a large high pressure anomaly sitting across southern Australia, which effectively means we saw considerably more high pressure in this region compared to the long running climate average for this time of year. With high pressure dominating the landscape, cold fronts were deflected away from the Australian mainland resulting in lower than average rainfall but also clearer weather and lighter winds.

The lack of true westerly winds on the East Coast (discussed below) for much of autumn can also be put down to this, with gradient winds taking a more longitudinal south to north approach rather than zonal west to east.

Running through each region, and the East Coast was a bit of a mixed bag. It hardly went flat across the Sydney region with small persistent easterly energy early in the piece, swinging more south in direction through the second half of autumn with variable winds making for variable conditions.

If you could get out of town on the weekends and maximise the available swell energy, you'd have done well.

Joey Abbott locked and loaded. Photo //  Craig Brokensha

Further north, the Mid North Coast faired better than the northern NSW coast with slightly more favourable winds in general. Around the Ballina/Byron region, variable tending northerly winds brought spring like conditions and spoilt a few fun swells with no true offshore breeze.

Large pumping surf developed along the Qld points mid-March just in time for the Quiksilver Pro with Kirra firing for finals day, followed by persistent levels of fun easterly trade-swell until around mid-April when things started to settle down. During this period the Sunshine Coast suffered problematic winds limiting the best conditions to protected spots which were generally small to tiny.

Lakey Peterson flies out of a Kirra barrel. Photo // WSL

Victoria was neither here nor there. Bells pumped for the Rip Curl Pro at the end of April and into early April, but things settled down into the end of the month with May seeing varied winds and swells as funky mid-latitude lows and cut-off systems pushed in from the west. Mid-late May ended a little more favourably with clean fun groundswells from a more southerly angle as a strong slow moving node of the Long Wave Trough focussed east of Tassie.

The great thing about this position of the Long Wave Trough is that between solid consistent days across the South Arm's exposed beaches, the Tassie points lit up multiple times through autumn, providing great waves before temperatures dipped too aversely.

Tassie dreaming. Photo // Stu Gibson

The Tassie east coast fluctuated between prolonged flatness to large victory at sea swells (namely the start of May) and pumping days in between.

South Australia offered favourable winds and strong swells through March and April before becoming a little more subdued into May as cut-off systems meandered in from Western Australia.

Moving to the west and between runs of small clean surf with persistent offshore winds and fine weather, a large rare north-west cyclone swell from Severe Tropical Cyclone Marcus provided a one-day wonder Sunday the 25th of March.

One XXL swell provided pumping challenging surf on the weekend of the Saturday 28th of April with the deep water reefs scattered around the south-west corner of the state firing off under all day offshores and clear sunny skies.

Jake Osman entombed. Photo // Tim Bonython

May provided good large clean days across the South West before the weather patterns started to shift and storms projected up closer to the state bringing large stormy swells but with windows of cleaner conditions with swell around Perth and Mandurah.

Here's hoping winter brings a few larger cleaner groundswells to all parts of the country.

Comments

Tim Bonython's picture
Tim Bonython's picture
Tim Bonython commented Wednesday, 13 Jun 2018 at 10:25am

I wonder if these kind of changing similar conditions apply in the northern hemisphere too??

blindboy's picture
blindboy's picture
blindboy commented Wednesday, 13 Jun 2018 at 7:10pm

I think events in the northern hemisphere are more complex Tim. The Arctic is experiencing the most dramatic climate shifts of anywhere and that is having major impacts across the whole region including the deflection at times of cold air further south over the continents.

crg's picture
crg's picture
crg commented Wednesday, 13 Jun 2018 at 7:51pm

Well today was warm, 1ft and northerly...is that Spring already?

blindboy's picture
blindboy's picture
blindboy commented Thursday, 14 Jun 2018 at 6:11pm

Maybe not crg but the gap between autumn and spring gets shorter every year!

GM's picture
GM's picture
GM commented Friday, 15 Jun 2018 at 1:44pm

Simple. The Earth has tilted on its axis and Sydney is now where Newcastle was, Newcastle is now where Port Macquarie was, and Port Macquarie is now where Coffs Harbour was.
Melbourne hasn't moved because shit is always shit no matter where it lands.

morg's picture
morg's picture
morg commented Saturday, 16 Jun 2018 at 10:56pm

Craig I recall reading an article in the early 80’s about climatic changes over time and how in 15 to 25 years it was anticipated that the weather patterns and average temperature in Newcastle would become similar to those of Coffs Harbour at that time. (I recall because I was excited about having warmer winters). This was well before global warming was ever discussed. I also recall something about south east NSW coming to the end of a 400 year dry spell at some stage after which it is going to start to rain a lot. Would be interesting to know any of those old hypothesis have become reality.

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