Major wintry storm looms with snow likely
A severe southerly storm that would be considered significant even in the depths of winter looks to have New Zealand in its sights early next week.
Forecasters say the event, due to arrive on Sunday and possibly linger until Wednesday, could bring heavy rain, very low snow, biting southerly gales and pounding seas to parts of the country. Latest computer guidance suggests the South Island’s east coast will be hit hardest, although North Island locations will also be affected at some stage over the three-day period.
It comes as a measure of southern ocean storminess shows the westerly winds encircling the Antarctic are weakening, allowing cold air to escape and move further north.
Blue Skies Weather forecaster Tony Trewinnard said the nuances of the system could still change, given it was still a few days away. However, it was an extended spell of weather that needed to be taken seriously and could affect roads and jeopardise travel plans.
‘‘There is the potential for a major storm. There will be heavy rain, significant snowfalls, strong winds. We’re looking at a storm system which, it would be fair to say, is more significant than any we saw during the winter months.’’
Snow could fall as low as 200 metres above sea-level on Monday night, he said.
That level was ‘‘pretty much unheard of ’’ for mid-November.
‘‘There’s also the potential for much snowfall accumulation above about 300m to 400m, with perhaps 10cm to 20cm of snow.’’
Rain could be heavy enough to bring flooding to parts of the South Island’s east coast, including surface flooding in Christchurch. Maximum temperatures on Monday and Tuesday were unlikely to reach double figures.
MetService forecaster Georgina Griffiths said the cold outbreak next week marked yet another ‘‘flip-flop’’ in the Southern Annular Mode (Sam) weather pattern.
In its severe weather outlook issued yesterday afternoon, MetService said that at this stage it had low confidence of significant heavy rain in Southland and Otago, lasting into Monday.