Storm bringing heavy rain, coastal flooding, gales moving south

Thursday, 4 January 2018

Areas expected to get the heaviest rain on Friday include Tongariro, Mt Taranaki, Marlborough and the Tararua Range.

Stormy weather from a rapidly deepening low is moving quickly down the country bringing heavy rain, strong winds and surging tides.

About 10.15am, Auckland Transport reported storm surges around the time of the high tide had temporarily closed part of harbourside road Tamaki Drive. Police said the route was reopened by 11.15am but warned conditions were expected to deteriorate during the day.

The leading edge of the rain associated with the low moved onto Northland in the early hours of Thursday morning.

A king tide laps at the Okahu Bay boat sheds

'It will move pretty fast … by the end of the day it will engulf all the North Island and the top of the South Island… Just a rain blanket, MetService duty forecaster Micky Malivuk said.

**READ MORE:

A storm passes over Martinborough on Wednesday evening. There's much more to come for northern and central areas of the country on Thursday.

* Flash floods hit North Island, as storm brews across the country

National forecast, January 3.

* Storm could 'cut-off' holidaymakers, Thames-Coromandel Council says

* Piha beach camp evacuated and Tamaki Drive closed**

Canterbury could start getting heavy rain overnight, and it could start falling in Wellington from 9am Friday.

For inland areas of much of the middle and lower South Island, severe thunderstorms will be the main risk on Thursday. The thunderstorms will develop as a result of another warm, humid day with light winds. Affected areas include the Canterbury high country, Otago and inland Southland.

Around 8.15am MetService tweeted heavy rain had started falling in the Far North, with 7.6mm recorded in Kerikeri in the previous hour. From 8-10am nearly 25mm fell on the town.

The low will spread a moist and strong northeast flow over affected areas as it moves south. It is expected to lie west of the North Island on Thursday night, moving southeast across the centre of New Zealand on Friday.

Niwa Weather said the length of time the low is spending over the Tasman Sea will mean a stronger system, amplifying rain, wind and wave impacts across the country in combination with king tides.

The low would be bringing more humid air, Malivuk said. 'It's coming from the tropics so it can bring quite a lot more moisture. It has quite a bit more energy.'

While temperatures had been warm during the past few days, that was more a result of sunshine and light winds. Once the rain started falling the temperature would actually drop as the rain brought colder air from the upper atmosphere.

Heavy rain was expected to get into the north of the Auckland region from late morning, then into Bay of Plenty and northern Gisborne from 4pm, Mt Taranaki from 3pm, and Nelson from 9pm

Areas expected to get the heaviest rain are Northland, Auckland, Coromandel Peninsula, Bay of Plenty, northern Gisborne, Tongariro National Park, Mt Taranaki, Nelson and Marlborough including the Kaikōura Coast, and on Friday morning the Tararua Range.

MetService is warning areas most at risk from severe gales, with gusts to 120kmh, are Northland from 3pm, Auckland from 5pm, then from 8pm gusts could hit 120kmh in Coromandel Peninsula, Waikato, Waitomo, Taumarunui, Bay of Plenty, Rotorua, Taupō, Taranaki and Taihape.

The rest of the North Island is also at risk of severe gales from midnight.

There is a risk eastern areas will be hit by coastal flooding, as a result of a combination of strong winds and king tides.

There are concerns holidaymakers on the Coromandel Peninsula could be cut off by the storm on Thursday and Thames-Coromandel District Council has suggested campers consider moving to higher ground.

On Wednesday, thunderstorms caused flash flooding in several areas. MetService recorded around 42mm of rain at Palmerston North airport in the hour to 5.15pm, while about 10mm fell in the centre of the town.

Masterton had a downpour around 6.30pm, with resident Chayla Beaver saying it lasted about 20 minutes. 'It was quite gnarly,' Beaver said. 'It was the eye of the storm, with thunder and lightning and just a lot of rain all at once.'

By 10pm Wednesday, MetService had counted 5344 lightning strikes across the country. Manawatū had the most with 881, followed by Marlborough with 729 and Central Otago with 721.