Heavy snow for parts of South Island this weekend, while round two could hit next week

Friday, 31 May 2019

MetService has issued a severe weather warning.

'Significant snow', rain and gales are about to batter parts of the South Island on Saturday and Sunday, causing havoc with people's Queen's Birthday holiday plans.

Skip ahead a few more days and a second big wintry troublemaker may also be coming our way.

Some forecasters are already anticipating round two of heavy snow and rain on Wednesday - if all the ingredients combine in the right way.

Heavy snow is expected across Porters Pass on Friday night and Saturday, with up to half a metre likely towards the summit and smaller amounts down to 400m. In this 2018 photo, a snow plough clears the western side of the pass.

Saturday's snow looks likely to disrupt the travel plans of many South Islanders, particularly those planning to drive across the alpine passes. But forecasters say it will be great news for the skifields.

**READ MORE:

Snow coats the Remarkables near Queenstown on Friday afternoon as the cold snap starts to move on to the south of the South Island.

* West Coast highway closes after Buller River reaches flood level

* Rain, snow and southerlies due to arrive for start of Queen's Birthday weekend

Some big falls of snow are coming for South Island skifields on Saturday and in the North Island on Sunday. In this file photo, Wanaka free-skier Beau James Wells competes in the FIS Continental Cup slope-style free-ski event at Cardrona Alpine Resort.

* A slow slide into winter for most Kiwis during the next few weeks**

The wintry blast is the result of a low-pressure system forming over Canterbury on Friday afternoon and evening and deepening overnight. Behind it, strong, very cold southerlies will develop, with heavy snow expected across parts of Canterbury and Marlborough down to about 300 metres from the early hours of Saturday.

The MetVUW forecast chart for 6am next Wednesday shows another wintry troublemaker socking it to New Zealand.

Heavy rain could also be an issue below that level.

The Christchurch City Council says its advice from MetService is there could be 35-50mm of rain in the city from midnight Friday to about 8am, with more on the Port Hills and Banks Peninsula.

Heavy snow is on the way for parts of Canterbury and Marlborough above about 300-400 metres on Saturday (file photo).

Council land drainage manager Keith Davison said that amount would cause some streets to flood, particularly if there were blocked drains.

'We're also likely to get some tidal flooding on the low-lying streets around the Avon and Heathcote rivers as the tide will be higher than usual.'

MetService said South Islanders needed to prepare for 'significant' and low snow across some parts of the island.

It has issued a severe weather watch for heavy snow about the Canterbury foothills and ranges, and the Kaikōura ranges, down to 300-400 metres early on Saturday, with 'significant' amounts above about 400m and more than half a metre of snow above 800m.

Inangahua Junction in the Buller District has reopened after fears of flooding closed it overnight.

The snow is predicted to be worst in Canterbury between 1am and 2pm on Saturday, and between 8am and 9pm further north.

Travel is likely to be disrupted and power lines may also be damaged by the weight of snow, MetService said.

In addition, south to southwest winds may reach severe-gale force in exposed parts of Banks Peninsula and the Kaikōura coast between 3am and 3pm on Saturday.

Warnings have also been issued for the alpine passes for Friday night and Saturday.

Up to half a metre of snow could accumulate towards the summit of Porters Pass between 10pm on Friday and 2pm on Saturday, with lesser amounts down to 400m.

Twenty centimetres could settle on the Lewis Pass highway above 600m from 1am Saturday to 4pm, and up to 15cm was forecast on Arthur's Pass above 700m between 10pm and 11am Saturday.

Road warnings are also out for the Lindis Pass, the Crown Range road and the Milford Road.

Wild weather on the West Coast was easing on Friday, with flooded rivers receding and power back on for those people in the Buller region who experienced power cuts as a result of lightning strikes on Thursday.

Blue Skies Weather forecaster Tony Trewinnard told Stuff this weekend's cold snap and low snow had been 'well telegraphed now for several days'.

'The basic pattern of a cold southwesterly flow will continue through the week. But it looks like on Tuesday-Wednesday we'll get another low-pressure system forming in the same way as this one is today.

'It has the potential to bring some significant rain and snowfalls too, but it doesn't mean it definitely will. We're keeping an eye on it.'

WeatherWatch head forecaster Philip Duncan told Stuff that, after a cold weekend, temperatures would rise a few degrees on Monday before dropping again mid-week.

'Wednesday there's another storm moving in. There should be severe warnings issued with that for the gales and rain coming.

'There's a chance of low snow in Canterbury with that set-up, but it depends on how far that cold air moves north, as it may not get quite cold enough for snow to low levels.'

Southern skifields are keenly anticipating snow over the next 24 hours.

Saturday is opening day for Cardrona Alpine Resort near Wanaka.

Spokeswoman Jen Houltham said on Friday afternoon there had been 15-20cm of snow on Thursday night, 'and we're snowmaking at full blast in the main basin'.

The New Zealand Transport Agency reminded motorists to check travel conditions before starting out on www.journeys.nzta.govt.nz or by calling 0800 4 HIGHWAYS (0800 44 44 49).