Heavy rain warnings for South Island, while North expected to be 'generally settled'

 

A significant rain event is expected to hit western parts of the South Island over the next few days.

MetService has issued an orange heavy rain warning for parts of Westland and Fiordland, and heavy rain watches for Southland and the headwaters of the Canterbury rivers and lakes.

The orange warning means people need to be “prepared and take action as appropriate as there could be some disruption to their day and potential risk to people, animals and property”, the MetService website states. 

An active front was expected to approach the South Island from the Tasman Sea on Thursday, moving slowly northwards across the lower South Island on Friday, MetService said in a statement.

The front was expected to slow over central and northern parts of the South Island on Saturday and Sunday, potentially delivering heavy rain to western and southern parts of the South Island.

The national forecaster urged residents to keep an eye on its website for any updates as the risk of significant heavy rainfall could potentially have “large impacts for Westland”.

“Be aware that heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous. These are particularly important for people travelling around the impacted areas.”

On Saturday, as the front moved up the South Island, a burst of cold air was expected over the southern half of the island east of the Southern Alps, and those between Ashburton and Wānaka would have a noticeably cooler day, MetService said.

Ashburton was expected to reach a high of 24 degrees Celsius on Friday but only 14C on Saturday – about 6C below the maximum temperature average for November.

The cold snap was expected to be brief though, with daytime temperatures expected to be closer to the high teens to low 20s on Sunday.

Westland from Bruce Bay northwards, particularly between Otira and Bruce Bay, were under the heavy rain warning from midnight Friday until noon Sunday.

MetService said between 200 and 250 millimetres of rain could fall with potentially larger accumulations of up to 350mm about the ranges during this time, with peak rates of between 20 and 35mm an hour.

The Westland area south of Bruce Bay could get 100 to 140mm of rain between 6pm Friday and 6pm on Saturday. Peak rates of between 10 and 25mm an hour are expected on Saturday.

About 150 to 200mm of rain was also expected in Fiordland between 1am on Friday and 1am Saturday, with peak rates of 15 to 20mm an hour.

The headwaters of the Canterbury rivers and lakes were under a heavy rain watch between noon and midnight Saturday.

“Rainfall amounts may approach warning criteria within 15 kilometres east of the main divide,” MetService said.

Southland was also under a heavy rain watch, with periods of heavy rain that may approach warning criteria expected between 9am Friday and 3am Saturday.

Meanwhile, the North Island was expected to have a cloudy but “generally settled weekend”. 

Relatively warm temperatures were expected on Sunday night as air originating from the tropics was pulled southwards between Gisborne and Blenheim, MetService said.

The warm nights were expected to persist through until at least Tuesday.