Most read story of the week —- The Indian Ocean Dipole is currently underway. Never heard of it before? Don’t worry, you’re not alone. It’s basically the Indian Ocean’s version of “El Nino”. El Nino is a Pacific Ocean event where warmer sea surface temperatures near the equator spread east towards the Americas – meaning the sea temperatures around New Zealand and Australia are cooler than normal.  The Indian Ocean Dipole (IOD) operates in the same way – warmer waters move east towards Australia and south eastern Asia while sea conditions cool further west towards Africa.

This means more rain clouds over Australia – and explains why Alice Springs has had more wet days than Canterbury has had lately, as WeatherWatch.co.nz reported last week.

This week CNN has been explaining to viewers just what is happening in Australia as the IOD gets underway – and it seems that there is some “spillover” into the Tasman Sea area and that is feeding into the North Island of New Zealand.

North Islanders are now increasingly aware of a change in pattern – this month WeatherWatch.co.nz has reported on a number of lows and rain events coming from Australia’s interior to the North Island, bringing slow moving rain events and more are coming before the month is over.

Australians are preparing for a wet, humid summer.

Meanwhile, there’s chatter about La Nina returning to the Pacific Ocean (El Nino’s opposite so warmer waters move west). Certainly we have La Nina-like weather around northern New Zealand at the moment.

If La Nina does get underway this spring or summer then Australia will be surounded by warmer than usual sea surface temperatures with La Nina bringing warmer than usual waters to eastern Australia and the IOD bringing warmer than usual waters to western Australia – both producing much more rain over the normally mostly dry continent and that means New Zealand may be wetter too – well, some parts.

WeatherWatch.co.nz believes the North Island of New Zealand may be exposed to more lows, more rain makers and possibly more tropical storms/ex-cyclones if this set up peaks in late summer/early autumn and our weather pattern continues to feed from the Australia direction.

In Australia forecasters at Weatherzone based in Sydney are also predicting their flood threat to worsen – and they are making this forecast based on the same data WeatherWatch.co.nz is using: The combination of IOD in the west plus “La Nina like” weather in the east. It’s already hitting Australia hard and the hottest most intense months are a long five months away.  

Weatherzone has written what is happening in Australia – with great info-graphics – take a look and read by clicking here.

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Above: Indian Ocean Dipole / Weatherzone

– 3 Images above / CNN Weather

*Our thanks to both CNN International and our friends at Weatherzone in Australia who both keenly contributed to this article.

– WeatherWatch.co.nz