Tuesday, 19 August 2008

Three unusual weather events have combined to create a "polar outbreak" bringing some of New Zealand's heaviest snow in years.

Snow fell in areas of the Wellington region and on the Desert Road last night, while the South Island continues to shiver in the cold snap.

Snow was reported to have fallen on the Rimutaka Hill Road between Wellington and Wairarapa and in the Kapiti Coast township of Paekakariki.

However, MetService forecaster Ian Miller said reports of snow in the seaside town were likely false, although temperatures dropped to 4 degrees overnight and 1 degree briefly this morning.

"It was just hail. It's probably quite low in the hills but you can't get snow (beyond) a few wet flakes at that temperature. Nothing that would settle."

Meanwhile residents in the hilly suburbs of Christchurch were struggling to get to work this morning after snow overnight left some streets accessible by four-wheel-drive only.

At 9am it was snowing steadily in central Christchurch and children at Cashmere Primary School in the hill suburb were told to stay at home for the day because of the snow.

Many roads around Banks Peninsula and Port Hills had been closed by snow and ice.

A severe weather warning was renewed yesterday for snow until around noon today, with snow showers about Otago Peninsula and Banks Peninsula and a burst of heavy snow on the central North Island plateau.

To add to the wintry feel, a cold southerly wind is expected and may rise to gale force from late in the day through to Wednesday between Kaikoura and Hawke's Bay and through Cook Strait, bringing "enhanced rain" that may fall as snow on mountain ranges, the MetService said.

The mountain forecast to midnight Tuesday has southwesterly winds and snow showers in both the North and South Islands, with snow down to altitudes as low as 600m.

Snow was forecast tonight for the Lindis Pass and Porters Pass in the central South Island.

MetService spokesman Bob McDavitt said snowfalls had been heavy for three reasons:

The Tasman Sea had become a "breeding ground" for low-pressure systems since mid July.

The lows had often moved slowly, allowing more time for snow or rain to fall.

Cold air from the Southern Ocean had been drawn north and then over New Zealand, tipping the balance toward snow and away from rain.

The Department of Conservation's Turangi-Taupo area manager Dave Lumley said only experienced people able to evaluate avalanche hazards should be carrying out backcountry skiing, and alpine trampers should be particularly cautious and make sure they get up-to-date avalanche information.

"Travel in the back country should be limited to low angle terrain well away from any avalanche terrain," he said. A website (www.avalanche.net.nz) which posts up-to-date details on avalanche risks around the country has many regions rated as high risk.

The MetService said that since last Thursday there had been around 800mm of fresh snow on the central North Island mountains and a metre or more on the western slopes of the Southern Alps from Mount Cook northwards.

DOC's warning followed a rough weekend in the South Island where nine people were rescued from mountain areas which were hazardous, and alpine safety experts have spoken out about foolhardy expeditions into the backcountry.

Mt Ruapehu in the Central Plateau received the biggest snowfall in more than 20 years, staff said.

They had to shovel off more than two metres of snow that had gathered on service building roofs, threatening to collapse them.

The dump was so heavy, it buried the snow stake used to measure snowfall.

The mountain was open yesterday - some snow-buried lifts were closed - but both its ski-fields now boast snow bases of almost four metres.

Staff at Whakapapa and Turoa ski-fields have reported on their website that they are "snowed under" with work, with patrollers on "the immense task of avalanche control whilst everyone else will be digging".

(Source Greer McDonald - The Dominion Post with The Press and NZPA)