On the 20th of August the waiting period to the most eagerly awaited event on the World Tour begins - the Billabong Pro Teahupoo.

For competitors, Teahupoo represents a final chance for the shallow-water tube junkies such as Kieren Perrow and Cory Lopez to excel before the midyear cut. It's also a chance for the current Top 5 of Jordy, Parko, Adriano, Mick and Taj to make a break from the man who sits menacingly in sixth place – Kelly Slater.

As for Slater, he recently admitted that he blew it by not going to J'Bay, thinking there were three throwaway events this year when there are actually only two. With a poor result already registered at Rio and a no show at J'Bay he now has to make every result count. Tellingly he's won Teahupoo three times, while none of the five above him have ever won there.

Of course Teahupoo, with its late drops and heaving shallow-water barrels, is also a favourite in webcast world. For the last six years however, the main event has been held in underwhelming conditions, sometimes being forced to run in small, windlblown surf. Even a move from its original May timeslot to August in order to increase the chances of good swell didn't work.

The large swells have come, however for a few years now it's been the trials – usually held two to three days before the main event - that have received the size and provided the spectacle.

So, with the dates fast approaching what does the current Tahitian swell forecast look like? Will this be the year that the main event finally gets a huge swell? Let's see...

Significant Tahitian swells almost always run in synch with the Long Wave Trough (LWT). A large Teahupoo swell will begin it's life as a deep low below New Zealand before travelling up the east coast of NZ toward Tahiti. That happens when the positioning of the LWT also runs up the east coast of NZ providing a pathway for the low pressure systems to follow.

(To learn more about the LWT and the influence it has on swells click here)

Present forecasts show the LWT moving into a favourable position for Tahitian swell by the 9th of this month (see Figure 1). The Air Tahiti Nui Von Zipper Trials begin on the 14th so this would indicate an above average chance of them receiving a good swell, given that it takes approximately four days for a swell to travel from below NZ to Tahiti.

Unfortunately, this news doesn't bode well for the main event which begins six days later on the 20th. Unless the LWT stalls and keeps directing storms up toward Tahiti it will continue its eastward rotation and also direct swell-producing storms east of Tahiti. This is the likeliest scenario.

If this occurs – that is, the LWT doesn't stall and continues its eastward rotation - the only other likelihood for a significant swell is toward the end of the waiting period when a new node of the LWT moves into position.

It's too far out to predict that yet but keep checking back as we'll provide regular updates. //STU NETTLE & CRAIG BROKENSHA