Powerful waves for the west coast of New Zealand

May 3, 2016

Storm force winds south of Australia in the last week have generated exceptionally powerful waves which are heading to New Zealand. These large long period waves will arrive on the southwest of the South Island Wednesday evening and then will sweep up the to the west coast of the North Island on Thursday.

The swell will not be exceptionally high (4 metres), but the swell period will be unusually long at 20 to 22 seconds, producing very large breaking waves inshore. MetService Meteorologist Lisa Murray advises, “Sweeping onshore waves could be a danger to swimmers all along the west coast due to strong inshore currents, undertows and rips associated with this long period swell”.

The energy in these waves is indicated by the wave period, which in this case reaches in excess of 20 seconds, something we only experience once a year or less often. This could put boat moorings under a lot of stress or make harbour bars hazardous.

“Waves may look impressive but can be dangerous especially for those fishing on-shore or walking along coastal pathways”, explained Ms. Murray, “This is due to some waves being more powerful than normal and we advise the public to take care.”

These long period swells are expected to ease slowly over the next few days. MetService advises people to keep up to date with our latest marine forecasts on the MetService website metservice.com or on mobile devices at m.metservice.com. You can check out forecast wave period maps at http://metservice.com/maps-radar/marine-forecast-maps/peak-wave-period. You can also follow our updates on MetService TV, at MetService New Zealand on Facebook, @metservice and @MetServiceWARN on Twitter and at blog.metservice.com

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