Weather: Snow returns to mountain passes, with rain for rest of country

A trough of low pressure is bringing rain and snow to the country, with the mountain passes expecting a light dusting. Photo / Niwa

MetService has issued road snowfall warnings for several mountain passes in the South Island, Te Waipounamu, and across the central plateau of the North Island, Te Ika a Maui.

Waka Kotahi said snow chains are essential for vehicles using Arthur's Pass SH73 to Otira. The transport agency said towing wasn't allowed, and that motorists should allow extra time.

Scattered rain could fall around the country tomorrow, but it should clear for most centres by the afternoon.

While Tāmaki Makaurau Auckland should expect a mostly cloudy day with isolated showers until the afternoon, the central North Island may see snow throughout Wednesday.

Napier-Taupō Rd SH5 and Desert Rd SH1 can expect snow flurries that could leave up to 1cm of snow.

Road Snowfall Warnings issued for Aotearoa/New Zealand.

Full details at https://t.co/aIkbAI2pg0 pic.twitter.com/3Hpvj4N0R6

— MetService (@MetService) September 12, 2022

Metservice meteorologist Alwyn Bakker said the rain and snow were caused by a trough of low pressure moving eastward across Aotearoa.

"At higher levels of the atmosphere, particularly cold air will be making its way over Te Waipounamu.

"The cooling effect will be less noticeable at ground level, but the resulting atmospheric instability makes thunderstorms more likely, and snow is expected to three or four hundred metres in the south," he said.

About the Southern Alps, Kā Tiritiri o te Moana, the Lewis Pass SH7, Arthurs Pass SH73, Porters Pass SH73, and Lindis Pass SH8 as much as 6cm of snow was forecast to fall and settle at higher elevations.

Given the ❄❄❄ in Te Waipounamu/South Island, how would you say it's snowing?

Kei te pūhuka!

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— MetService (@MetService) September 13, 2022

Further south, the Haast Pass SH6, Crown Range Rd and Dunedin to Waitai Highway SH1 were also expected to see snow settle as low as 200m.

Unsettled weather is forecast across the country this week, with a strong and unstable westerly flow bringing snow and bands of rain to many regions.

"At this stage, the exact position of the low centre is uncertain, so as we progress through the week MetService advises keeping up to date with the latest forecasts," states Bakker.

Frosty conditions will continue to put a damper on spring for southern and central parts of the North Island this week, dusting Mt Taranaki with a layer of snow.