Flooding affecting SH6, rain and wind for Canterbury

Flooding has forced the closure of a major highway straddling Otago and the West Coast, as large areas of the South Island are hit by heavy rain and strong winds.

MetService updated its forecast this morning to pull back times for when it expects the wind and rain to abate, with the South Island all clear by 1am and the lower North Island by 5am on Sunday.

The forecaster said heavy rain warnings remain in place for much of the West Coast region, with rain bringing an increased risk of slips, surface flooding and difficult driving conditions.

A heavy rain warning has also been issued for the headwaters of the headwaters of Otago and Canterbury lakes and rivers, while strong wind warnings are in effect for the east coast of the top of the South Island down to the Canterbury High Country, bringing severe gales today.

A spokesman for the New Zealand Transport Agency advised about 9.30am today that State Highway 6/Haast Pass Highway, between Haast and Makarora, has been shut.

An update was expected later in the day. 

Meanwhile, SH6/Coast Rd, between Rapahoe and Nine Mile in the Grey District, has opened to a single lane under stop/go traffic management after a slip forced the full road closure earlier this morning.

Road users on this route are asked to travel with caution and to stop on request at the slip site, NZTA advised.

Heavy rain for large part of South Is

A heavy rain warning is in place for the ranges of Westland from 9am until 7pm today. MetService says on top of what has already fallen, expect 200 to 250mm of rain. Peak rates of 20 to 30mm/h. Thunderstorms possible.

Further north, a heavy rain warning has also been issued for coastal ranges of the districts of Buller and Grey from 11am on Saturday until 1am on Sunday. Expect 80 to 130mm of rain. Peak rates of 15 to 25mm/h from this afternoon. 

A heavy rain watch is in place for the inland ranges of the Buller District and the Nelson Lakes from 11am on Saturday until 1am on Sunday.

Heavy rain is also forecast for the headwaters of the Otago lakes and rivers until 2pm today. On top of what has already fallen, MetService said to expect 50 to 100mm of rain about the main divide, and 30 to 50mm within 15km farther east, mostly about the headwaters of Lakes Wanaka and Hawea. 

For the headwaters of the Canterbury lakes and rivers south of the Hurunui River from 9am until 7pm: On top of what has already fallen, expect 200 to 250mm of rain about the main divide, and 100 to 140mm within 15 km farther east, with thunderstorms possible. 

Streams and rivers may rise rapidly. Surface flooding, slips and difficult driving conditions possible.

Severe gales 

Strong winds are set to buffet east coast parts of the South Island and inland today. 

Warnings are in place for Canterbury High Country from 9am until 5pm, with severe gale northwest winds gusting 130km/h in exposed places. These will gradually ease from the south from mid-afternoon.

For the Canterbury Plains about and north of Rakaia, including Christchurch and Banks Peninsula:  Severe gale northwest winds gusting 120km/h in exposed places between 1pm and 5pm.

For Marlborough about south of Clarence: Severe gale northwest winds gusting 130km/h in exposed places from 11am until 10pm.

From Marlborough north of Clarence: Severe gale northwest winds gusting 120km/h in exposed places from 1pm until midnight. 

MetService warns damage to trees, powerlines and unsecured structures were possible. Driving may be difficult, especially for high-sided vehicles and motorcycles.

- Allied Media