Deep low pressure system makes its presence known - Thursday 4 January 2018

MetService News Release
Thursday 4 January 2018

A rapidly-deepening low pressure system in the Tasman Sea northwest of the country is set to move towards the North Island today, before moving over central New Zealand during Friday. This system – the first significant system to affect the country since mid-September 2017 – is already bringing rain and wind to central and northern areas of the North Island. There are Severe Weather Warnings and Watches in place for heavy rain and strong wind for a number of areas in the North and South Island, with rainfall accumulations in excess of 100mm in some places and severe northeasterly gales gusting 120km/h in exposed places.

Persistent rain will spread south over the North Island this morning, reaching as far south as Christchurch by Thursday evening. Rain will then spread further south over the South Island on Friday, and become patchy in Northland, Gisborne, Hawke’s Bay and Wairarapa.

“Significant accumulations are expected on Thursday over the upper North Island where areas like the Bay of Plenty could see up to 150mm of rain accumulate about the ranges. Auckland could see as much as 90mm, especially about the Hibiscus Coast and the Waitakere and Hunua Ranges. The upper South Island will see its heaviest rain from tonight, where up to 180mm may accumulate about the ranges of Nelson and Marlborough,” explained MetService Meteorologist Ciaran Doolin.

“The strongest winds associated with the system will be across the upper North Island with severe gale northeasterlies forecast in exposed places during Thursday. When the low crosses the country on Friday, a period of severe west to northwest gales will affect central parts of New Zealand.

“With the strong winds come large swells about the east coast of the upper North Island, from Northland to the Bay of Plenty. In combination with king tides, this may lead to coastal inundation in low lying areas, where waves could push further inland than normal and cover coastal roads, tracks and campsites. This risk is most elevated on Thursday evening and Friday morning but should ease by Friday evening.”

“People need to take extra care this holiday period as heavy rain and severe gales have the potential to have a major impact on people’s plans. Make sure to stay up to date with the latest forecasts and Severe Weather Warnings and Watches,” said Mr Doolin.

Rain and gale southwesterlies will gradually ease Saturday as the low moves away southeast of the country. A ridge spreads onto the country on Sunday, making for a mostly fine day across the country, although a short-lived front makes landfall in the far south bringing rainy spells.

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