WELLINGTON, 19 FEBRUARY 2018 (STUFF NZ) — Cyclone Gita could bring gales with gusts of over 150kmh, waves of over 6 metres, and heavy rain to a vast swathe of the country when it hits on Tuesday evening, according to predictions.

Civil Defence was urging people to plan ahead for the storm, with a state of emergency could be declared on the West Coast as early as Monday evening if predictions about the intensity of the storm hold true.

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Gita, which caused havoc in Tonga last week, has the South Island in its “firing line”. Its centre is predicted to make landfall in the northwest tip of the island late Tuesday.

The storm’s passage was “expected to bring a period of high-impact severe weather to many parts of central New Zealand,” MetService said in a severe weather warning issued midday Monday.

“Heavy rain will cause slips, rapidly rising streams and rivers, and flooding. Severe gales with damaging gusts are expected, so people are advised to secure property and items that may be blown away by strong winds.

MetService warned there was also the potential for coastal inundation with high tide overnight Tuesday and before dawn on Wednesday, “due to the combination of tides, low air-pressure, strong onshore winds and large waves in excess of 6 metres in some places”.

For the South Island, the risk of coastal inundation was greatest for areas from Buller and North Canterbury northwards, while on the North Island it would be coastal areas from Raglan southwards to southern Wairarapa, the forecaster said.

Early on Monday MetService meteorologist Nick Zacher said the latest forecast track continued to show Gita crossing northern portions of the South Island from about Tuesday evening to about Wednesday morning.

“It’s moving quite fast, it’s going to accelerate further through the next 24 – 48 hours,” Zacher said.

“Once it does move through it’s going to start clearing off the country just as fast.”

Gita was expected to be reclassified as an ex-tropical cyclone sometime on Monday evening.

WeatherWatch head forecaster Phillip Duncan said Gita was “bigger” and “more powerful” than ex-tropical cyclone Fehi, which caused extensive damage when it hit the West Coast early February.

The storm was forecast to bring sustained gale-force winds in places of 60 – 80kmh from Taranaki to Westport, Duncan said.

“Localised gusts could climb over 150kmh in exposed rural areas, possibly higher. Damaging and destructive gusts are possible in all those main West Coast towns,” he said.

More than 100 millimetres of rain could fall within 24 hours in regions where MetService had heavy rain watches in place, including Canterbury, Marlborough, Nelson, parts of the West Coast, Wellington and Horowhenua.

The heavy rain could start in central areas of the country from 1am on Tuesday, and a few hours later in Canterbury and Westland, MetService said. North Otago could be affected from 4pm Tuesday.

“Most of the rain is going to hit the South Island. There’s some heavy rain ahead of the storm today and Tuesday morning for the Wellington area, but the rest of the North Island really doesn’t see anything too major.” Duncan said.

“It’s a South Island rain event that starts in the upper South Island Tuesday morning, and spreads across the rest of the upper and eastern South Island in the afternoon.”

Persistent rain was likely to continue to the end of Wednesday in the upper and eastern South Island, especially Canterbury.

The West Coast would see rain from Tuesday afternoon, which “gets very intense into the evening”.

Severe gales could start in Nelson from 1pm Tuesday and from mid-afternoon Tuesday in other central areas of the country, as well as Westland and the Canterbury High Country north of Tekapo.

The weather situation was quite complex, Zacher said.

A cold front moving up the South Island, stretching from northern Fiordland to about Dunedin was bringing southeast winds. On Monday, it would start to develop rain and showers for parts of Otago, and a bit more persistent showers and rain for Canterbury.

Another frontal boundary was stretching west from Taranaki, and would start interacting with Gita as it approached.

The result was expected to be a steady band of rain from Taranaki southwards through to Buller and Marlborough.

“That rain is going to start developing later this evening and become quite heavy and persistent across some of those areas.”

Civil Defence said Gita had the potential to pack a punch and cause a lot of disruption.

“Now is the perfect time to plan ahead,” Director Sarah Stuart-Black said.

“This means preparing for the possibility of power cuts, water outages and road closures that could leave you or your loved ones stranded.

“It’s also a good idea to have a grab bag ready in case you need to evacuate. If you don’t have a household emergency plan, now’s the time to sit down with your family or flatmates and get it done.”

“Stay safe by staying out of harm’s way. Try and run any important errands before the weather hits so you won’t need to do any non-essential travel in treacherous conditions, and make sure you secure outdoor furniture well in advance.”….PACNEWS [/restrict]