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

Monday, 27 May 2019

Good news for skiers and skifield operators with the expected arrival of a snow-bearing southerly right on cue on June 1, the first day of official winter (file photo).

Winter is due to arrive right on cue on Saturday, with a chilling southerly taking the edge off the Queen's Birthday holiday weekend but putting smiles on the faces of skiers.

Forecasters say the blast will be particularly unpleasant coming after a warm week and a generally mild and settled May.

A cold southerly airstream coming from close to Antarctica is shown washing over the country on Saturday (June 1) in this European Centre for Medium-Range Forecasting prediction on the Windy.com website.

A surge of cold air from close to the Antarctic will slowly make its way north up the South Island on Friday afternoon and on to the North Island on Saturday.

Rain or icy showers are likely to follow, with falling freezing levels allowing snow to settle on the ranges, possibly as low as 300-400 metres above sea-level in Otago and Southland, and down to 500m in Canterbury.

It will be a wet and cold start to the long Queen's Birthday weekend as a southerly grips much of the country (file photo).

MetService meteorologist Georgina Griffiths talking about 'SAM' - the Southern Annular Mode or polar vortex, which plays an increasingly important role in determining our weather.

* Polar vortex helping forecasters predict New Zealand weather

* Weather forecasters challenged by recent bad weather

* Trouble-making jetstream eases but more gales to hit southerners this weekend**

Snow is expected to relatively low levels at times from Saturday into next week, as pulses of cold southwesterly air follow the first major southerly outbreak of the winter on Saturday (file photo of Southern Alps).

The worst weather is expected to come and go in spells throughout the long weekend. But the cold temperatures are forecast to last into next week, with fine days and frosty nights in sheltered eastern regions but more squally showers and raw southwesterly winds for those in the west of both islands and in South Island's far south.

Both MetService and Blue Skies Weather predicted about three weeks ago there would be a sudden start to winter with a significant southerly outbreak.

MetService meteorologist Georgina Griffiths told Stuffon Monday the timing of the abrupt change on June 1 was 'quite a coincidence'.

'The models had been quite consistent on a snotty end to May.

'So this week is wild and windy. Then we have the cold southerly with the low snow, and more of a critical southwesterly flow for most of the next week.'

However, just how low the snow would fall was 'the $1 million question'.

'The weather has been so unusual - the skifield operators must have been sitting there sweating, wondering if winter is coming.

'This will be a really big shock to the system for New Zealanders.'

Blue Skies forecaster Tony Trewinnard said the southerly would be the start of a much colder period of weather going well into next month.

It was possible there would be similar outbreaks in the third week of June and the first week of July, with anticyclonic conditions and frosty nights in the spells between.

'From Friday through to Tuesday-Wednesday next week will be a much more unsettled period. There'll be good snowfalls on the South Island ranges, which will be a big help to the ski fields.

'Some parts of the country may get some quite decent rainfalls that are much needed, like the Waikato.

'Auckland will get some miserable days like everyone else.

'The timing of this is just what it is. It's going to flush out the warmer air we've had and be exactly the kind of thing we'd expect to be seeing at this time of year,' Trewinnard said.

Coronet Peak manager Nigel Kerr said Thursday was looking like the day it would go 'white and cold'. Over the weekend it was less clear what might happen.

'As long as it drops the temperatures we'll be pretty happy.'

The field opens on June 15.

Mount Hutt Ski Area manager James McKenzie said the forecasts were 'still flicking all over the place'.

'The south-west cold looks there right through to opening day and that's ideal. Get a bit of natural snow and with cold temperatures and favourable weather, we can climb back into [making] it again.'

Mount Hutt's opening day is June 7.

The National Institute of Water and Atmospheric Research says the long spell of fine, dry weather in recent months means Milford Sound, Mt Cook village, Tekapo, Dunedin and Invercargill are on track for their warmest autumns on record.