Update on El Niño

An abnormal El Niño weather event is looking likely for New Zealand over summer, according to NIWA meteorologist Ben Noll.

In the latest update about the potential for an El Niño system which NIWA has been keeping a watch on for several months, Mr Noll said there was now an 80 per cent chance it will happen.

“El Niño conditions have still yet to officially arrive, but the Pacific Ocean continues to make strides towards it,” he said.

This particular El Niño is likely to start late and is exhibiting some non-traditional characteristics in the ocean.

“The most unusually warm sea surface temperatures are in the central equatorial Pacific – typically they are found further east, closer to South America.”

Mr Noll said this was known as a central-based El Niño, or El Niño Modoki. Modoki is a Japanese word that means “same, but different”.

Impacts from this El Niño are likely to deviate from those experienced during a conventional event.

During summer in a typical El Niño, New Zealand has stronger and/or more frequent winds from the west, leading to an elevated risk of drier-than-normal conditions in the east of both islands and above normal rainfall in the west.

This year and into next year, while westerly air flow patterns are favoured, the summer season may come with a bit more variability. El Niño Modoki may be associated with periodic easterly-quarter wind flows that bring some beneficial rainfall to eastern areas.

The next three months is equally likely to have above average or average temperatures for all regions of New Zealand with rainfall below normal or near normal for most areas, Mr Noll said.

There are several regions identified by NIWA that should be monitored closely for developing dry conditions this summer season, including: the lower/western South Island, Gisborne/East Cape, Bay of Plenty, Coromandel/Waikato, Auckland, and Northland.

While El Niño can be confined to summer, the chance for this to carry on into autumn is elevated and stands at 55 to 60 per cent.