North Island to feel brunt of front ramping up on the West Coast

Monday, 27 May 2019

Drone footage shows full extent of the damage to the Waiho Bridge, near Franz Josef on the West Coast, in March 2019.

Torrential rain is working its way up the West Coast, moving towards settlements still recovering from a severe storm in March.

Westland Civil Defence has already met to discuss the possibility of flooding in the region.

MetService duty meteorologist Larissa Marintchenko said more than 50 millimetres fell in Milford Sound overnight Sunday as a front worked its way up the country.

Flooding around Franz Josef in South Westland following March's storm.

A heavy rain warning was in place for Westland, with between 280mm and 320mm forecast between Sunday night and Tuesday at 10pm. More than 500mm is expected in some places over four to five days.

* West Coast deluge nears Christchurch's annual rainfall, half of Auckland's**

The heavy rain was expected to lash Franz Josef, which lost the State Highway 6 bridge over the Waiho River and a flood bank on its southern edge when more than 500mm dropped in the region in late March.

Marintchenko said heavy rain and thunderstorms were over Fiordland on Monday morning, with up to 220mm of rain possible in the 24 hours to 4pm Monday. The volume of rainfall was not unusual for the region though, she said.

Heavy rain was expected in Westland, south of Harihari, until 10pm on Tuesday, with more rain forecast from Wednesday to Friday, Marintchenko said.

There was the possibility of rising rivers, slips, and difficult driving conditions, she said.

The bad weather was caused by a trough or system front that was moving up the country, Marintchenko said.

'Because the system is moving north, overnight it will reach the North Island as well, so [on Tuesday] we are expecting rain for pretty much all parts of the North Island.'

On Tuesday we see the first of two significant fronts this week which will bring rain to most, as well as snow to around 1200m for the southern South Island. In the video we can see the passage of the front crossing the country on Tuesday. Latest at https://t.co/Yjbq0jxdqz ^KL pic.twitter.com/pKwTJPH0X8

— MetService (@MetService) May 26, 2019

She said the rain would ease there on Wednesday, but there would still be showers.

Westland mayor Bruce Smith said the region's Civil Defence team had a meeting to discuss the possibility of flooding.

He had no concerns about the newly replaced Waiho Bridge because it had 'been well put together and there were a lot of circumstances that contributed to the last wash-away'.

However, there was a risk that the rubbish exposed from an old dump during the March storm would be more widely dispersed by the new rain. Increased water flows could wash out rubbish trapped in sections of the Fox River, he said.

As we say goodbye to the weekend we also bid farewell to the settled weather. A more turbulent weather pattern forecast for the last week of Autumn. Many regions are expected to see a period of severe weather in the next 7 days so keep up to date at https://t.co/hnwmGxU1gR^AC pic.twitter.com/UXKKVcreDA

— MetService (@MetService) May 26, 2019

The dump site itself had been sealed and Smith was not concerned about more rubbish being washed out.

The Milton Wall – a flood bank that protects about 80 people who live south of the Waiho River – was about 80 per cent washed away in the March flooding. The West Coast Regional Council is rebuilding the flood bank but that work has not yet been completed.

NZ Transport Agency senior network manager Colin Hey said the agency was 'as prepared as we possibly can be for the rain forecast'.

Contractors would be on patrol across the West Coast, and on state highways 6 and 73 in particular. Equipment and crews were at the expected trouble spots, including those where there were issues during the March storm.

A digger is at Kelly's Creek, on SH73 in the Otira Gorge, where it had been working for several weeks to keep the river bed below the bridge deck to avoid flooding.

Crews would also be at the crucial Waiho Bridge, which provides the only link to the south of Franz Josef.

A state of emergency was called in Westland in late March, but during that storm as much as 30mm to 40mm of rain fell in an hour in some places, compared to 15mm to 25mm expected to fall per hour this week.