Swellnet readers would be well aware how what happens in one ocean basin can have a flow-on effect in another, sometimes tens of thousands of kilometres away.

This is usually the result of a very large swell following a Great Circle path on an unlikely route, taking it far away from where it was formed.

However, there’s also the scenario where the remnants of a significant storm can then traverse a continent and re-strengthen on the opposite coast - and the coming Tasman Low is one such system.

It originated in the Indian Ocean late last week, with it generating the current pumping swell across Indonesia (which is now on the ease).

Riding swell created by the first iteration of the low pressure system, Sierra Kerr scored a 10-point wave at the Nias Pro

After projecting high up through the Indian Ocean, the remnants of this storm moved across Western Australia on Sunday and then onwards across the southeast of the country Tuesday before moving back over water - the Tasman Sea this time - yesterday. It created today’s short-range southerly swell.

The system has lost a bit of steam - today's swell is little more than jumped-up windswell - however the low is currently combining with local features for what should be an impressive second act...or maybe that's a third act?

As I type, it’s drawing in warm, tropical moisture from the east, while at the same time an injection of polar air is due to be added to the mix this evening and tomorrow. Using the internal combustion engine as a metaphor, the mix of hot and cold elements is akin to petrol and a spark plug.

What will result is the rapid intensification of the broad low pressure system over New Zealand. Specifically, it will create a fetch of gale-force winds forecast to slingshot around its southwestern flank, aimed towards the Tasmanian and southern NSW coastline.

Running through the forecast projection - and noting it's been fairly consistent the last few days - the fetch will produce a swinging uppercut on top of an active sea state, generating an oversized pulse of south-southeast groundswell set to arrive Sunday evening and peaking through Monday.

Recently on Swellnet we've been discussing the fleeting nature of East Coast swells, and this point is true, however in this instance an upper level ridge will help cradle the low until next Wednesday. This will result in a prolonged swell event, starting south-southeast and tending more east of south as it eases through the rest of next week.

While the charts look impressive, it’s worth remembering that during the swell's peak surfable options will be limited, with only a handful of quality waves showing consistent quality - most locations will be large and straight.

As is typical, the backside of the event looks much better as it eases in size, the direction comes around, while the wind should tend westerly opening up more options for the general surfing population.

On the upside of this coming swell event, the Shark Island Challenge has been given the green light for Sunday, though viewers should keep their expectations in check as the swell looks to be more southerly than is ideal and wind-affected too.

Being such a fickle wave, scoring a large south-east swell with favourable tides during the waiting period requires a large degree of luck. Organisers are committed to running it so that's what we wish them, a large slab of good luck, for Sunday's contest.

At the least, the final will be held late in the day when the swell is rising and the tide is highest.