A couple of weeks ago we discussed the minor Stratospheric Warming Events that were occurring in the upper atmosphere and how this would play out at the surface.

As we saw during the 2002 and 2019 major events, the filter down effect of this warming is a weakening of the polar vortex and a northwards shift in the westerly storm track as cold air trapped by the strong polar vortex reaches further north.

This is otherwise known as a negative Southern Annular Mode (SAM) event.

SAM, you may recall, refers to the north-south movement of the westerly storm track. When SAM is positive the westerlies shift further south away from us, the opposite for negative.

We're currently experiencing a negative SAM - a northwards shift in storm track - and due to the warming event it's one of the strongest since 2011 with SAM values touching -4.5.

Indonesia has a had a great run of swell (Andrew Shield)

Negative SAM events in Australia conjures thoughts of consistent southwest swell, particularly for the Surf Coast. Yet as was discussed in the earlier article, in this context it all depends on where in our region the westerly storm tracks shifts

If it happens in the vicinity of the Indian Ocean, the swells come in more from the west, inconsistent and smaller - albeit with favourable winds. Conversely, if the storm track shifts over the southeast of the country, that’s when we get swell, snow, and freezing temperatures.

We've now got a clearer idea of where the warming event is playing out and who stands to benefit.

During the past week we’ve seen the negative SAM event manifest across the Indian Ocean, with frontal activity pushing up very north in latitude. This can be seen in the Long Wave Trough chart for today (8th August) - see chart below. A strong node sits west of Western Australia, steering frontal systems up on a similar track, with them then dipping away to the east-southeast and under the country.

It’s expected to remain in that region for the coming fortnight or so before slowly moving east towards the end of the month and hopefully more towards the southeast of the country into September.

The current setup is providing a great run of swell for Indonesia, with large, back to back groundswells impacting the region, while SW Western Australia is copping all the swell but also all the wind - though it's a different story up north.

For South Australia and Victoria it’s bringing consecutive west swells along with generally favourable winds, though those sitting in the lee of Cape Otway are begging for more size.

Node of the Long Wave Trough parked west of Western Australia this week

Now we know where the eagle has landed, so to speak, it’ll be a wait and see scenario for the southern states as things start to move east later in the month.

Downwind of all this activity sits Cloudbreak, and more importantly the Corona Fiji Pro. The waiting period kicks off on the 20th of August and runs through until the 29th.

As mentioned, the current setup is focussed towards the Indian Ocean with storms then weakening while dipping south-east under Australia and towards the polar shelf.

The ideal swell window for Cloudbreak are storms tracking further south in the Southern Ocean, and rising north-east towards the Tasman Sea.

Though it doesn't bode well for the immediate future, the event is still two weeks away, plus Cloudbreak is an incredible magnet for any swell that is out there. If one of these south-east tracking storms makes a slight adjustment or intensifcation, it could be a different story.

With that in mind, keep an eye on the site for an early forecast next week.