Tahiti's on target for a prolonged series of large swells over the next week, and once again we owe our thanks to the Long Wave Trough.

Regular readers will be familiar with the term 'Long Wave Trough' (LWT) and its influence on steering weather systems into particular parts of the country. To recap, the LWT is a large, slow moving trough of low pressure in the upper atmosphere which influences regional weather patterns.

The position of the LWT can bring about sustained periods of swell for different parts of the coast, depending on its position and alignment. For example, when the LWT amplifies across the Great Australian Bight, South Australia and Victoria experience strong, sizeable swells. If the LWT parks itself across the southern Tasman Sea, then Australia's eastern seaboard, Fiji and New Zealand will usually see an extended period of southerly swell activity.

When the LWT stalls and amplifies east of New Zealand, Southern Ocean storms are supercharged and steered deep into the South Pacific on a course towards Tahiti.

And this is exactly what's expected to develop over the coming week with the LWT amplifying just east of New Zealand before moving slowly eastwards. The first frontal system associated with the LWT will project up from polar latitudes into the South Pacific this Friday and Saturday, generating a long-period S/SW groundswell in the 15ft+ range for Monday afternoon and Tuesday morning.

A series of secondary frontal systems being steered along a similar path will prevent the swell dropping below 10ft mid-next week, ahead of another 15ft swell due sometime around Thursday. Swell activity should start to settle down from here on as a result of the LWT moving off to the east and weakening, focusing Southern Ocean fronts along a more zonal (west-east) track away from Tahiti.

With almost a week of sizeable back-to-back swells in the forecast period, we can expect a strong contingent of big wave surfers to make the pilgrimage over to Tahiti. Keep an eye on Swellnet for the latest news.

Click here for the latest Tahiti weather charts. //CRAIG BROKENSHA