Antarctic blast set for South Island as September ends: 'Significant weather event' on the way

MetService warns "significant severe weather" is expected this weekend, as an Antarctic blast hits the South Island to end the month. Severe weather warnings are likely to be issued today as wild conditions approach. MetService urges people to keep an eye on the forecast, especially if they are travelling this weekend.

"An active front is forecast to move eastwards across New Zealand over the weekend, preceded by a strong and moist north-to-northwest flow and followed by a strong and cold west-to-southwest flow into early next week," MetService says.

"This front delivers a period of heavy rain to some western areas, severe gales for many places, and snow to low levels across western and southern parts of the South Island."

#MiseryIndex: The biggest pool of Antarctic air to move into #NewZealand for 2020 is forecast this Monday.

Here's the wind map with areas in white/blue shading indicating sub-zero wind chill.#Southland Farmers - prepare now.

More details in our weather video this morning pic.twitter.com/fkathKG9e2

— WeatherWatch.co.nz (@WeatherWatchNZ) September 23, 2020

Severe gales are on the cards for many across the country and could make driving hazardous, especially for high-sided vehicles and bicycles.

Heavy rainfall will likely approach warning levels in Fiordland, southern Westland and the Canterbury and Otago headwaters, coupled with north-to-northwesterly winds becoming severe at times.

Northern Westland, Buller, Nelson and the Marlborough Sounds, including the Richmond Ranges, have a 40 per cent chance for wind and rain, MetService said.

In the east of the South Island, there is a 60 per cent likelihood - of severe gale northwesterlies for the remainder of Marlborough and Canterbury on Saturday and Sunday.

A significant severe weather event is expected to hit much of the country this weekend. Photo / Metservice

Across the North Island, severe gale northwesterlies are very likely to hit south Taranaki, across to Wairarapa and down to Wellington from late Saturday through to Sunday.

The remainder of the North Island has a two-in-five chance of getting lashed by severe gales, the forecaster said.

Sunday will bring rain and a small possibility it will reach warning amounts in Taranaki, the King Country, the Central Plateau, the eastern Bay of Plenty Ranges and the Tararua Range.

Next week will bring snow to low levels, which forecasters predict will be challenging for livestock in the South Island.

"On Monday and Tuesday, snow is forecast to reach low levels in the far south, possibly down to sea level, with low confidence of heavy snow above 200m in Fiordland, Southland and Clutha," MetService said.

👀This isn't something you see every day👀
How many isobars?!? Look at the gales in this loop, forecast to lash much of the country this weekend, and also how much snow in the Alps there is behind it. Expect significant transport disruptions to start the school holidays ^TA pic.twitter.com/RVb69OxzZu

— MetService (@MetService) September 24, 2020

MetService has a moderate confidence of severe gale southwesterlies across Fiordland, Southland and Clutha.

The snow and strong southwesterly winds are expected to be challenging for livestock in the South Island early next week.

A number of passes and high roads across the South Island may be compromised by the snowfall on Monday and Tuesday.

The Desert Rd is likely to receive a dusting of snow at the same time, making conditions hazardous.

#SeptemberStorm - unusually widespread hazards

Widespread Severe Weather forecast with deep low and front this weekend and Monday. Chart compares pressure difference-an indicator of severe gales-with impacts from previous years. Warnings issued soon https://t.co/qHyE5zhh6X ^TA pic.twitter.com/VpPhdco5H7

— MetService (@MetService) September 24, 2020

MetService's short forecast:

Northland, Auckland, Coromandel Peninsula and Bay of Plenty

Showers easing overnight,then becoming confined to Northland this morning with long fine spells elsewhere.

Waikato to the Kapiti Coast, including the central high country

Showers overnight, becoming isolated thismorning.

Gisborne and Hawke's Bay

Showers spreading off the ranges until late last eveningcleared and mainly fine today.

Wairarapa, Wellington, also Nelson, Marlborough and Canterbury

Mainly fine,with isolated showers in Canterbury thisafternoon and evening.

Otago and Southland

A few showers, turning to rain thismorning. Rain clearing this afternoon, but showers lingering about eastern Otago.

Buller, Westland, Fiordland

Showers overnight, some heavy, with isolated thunderstorms possible, easing today.

Chatham Islands

Fine spells and a possible shower.

MetService's extended forecast:

Saturday

North Island: Cloudy with isolated showers northwest of Taihape, turning to rain about Taranaki at night. Fine elsewhere.

South Island: Showers in the west, turning to rain, possibly heavy. Rain developing about Nelson, Marlborough, Canterbury High Country and Southern Lakes later. Partly cloudy elsewhere.

Sunday

Rain, with heavy falls, turning to showers but clearing eastern regions north of Otago. Snow lowering to 600m about Buller, sloping to 400m in the Far South.

Monday

North Island: A few showers in the west, snow to 1000m. Fine in the east and Wellington.

South Island: Showers in the west and south, spreading elsewhere for a time. Snow to 500m about Buller, sloping to low levels in the far south.

Chatham Islands

Fine spells and light winds. Rain and gale northerlies developing Sunday, turning to showers on Monday with a strong westerly change.