MetService is forecasting an unsettled west to southwest flow will turn northwest over central and southern New Zealand ahead of a front approaching from the Tasman Sea on Tuesday.

“There is moderate confidence that westerly winds will reach severe gale in exposed parts of Hawke’s Bay south of Napier and the Tararua District during the morning,” MetService said.

“Later in the day, there is low confidence that northwest winds will reach severe gale [force] in exposed parts of Fiordland and Southland.”

On Wednesday, September 17, a front preceded by a strong northwest flow is forecast to move over the South Island, followed by disturbed westerlies.

“There is high confidence rainfall amounts will reach warning criteria about the ranges of the Westland District, with significant spillover into the Otago and Canterbury headwaters likely.

“There is moderate confidence warnable amounts of rain will fall in Fiordland and about the ranges of the Buller District.

“In addition, there is moderate confidence northwest winds will reach severe gale [force] in exposed parts of the Canterbury High Country, [the] Canterbury Plains near the foothills, Wellington, Wairarapa and the Tararua District. There is low confidence northwest winds will reach severe gale in exposed parts of Fiordland, Stewart Island, Southland, Otago, Canterbury east of the foothills and Marlborough for a time.”

On Thursday, the front, which is preceded by a strong northwest flow, should move northeastwards over the North Island, while weakening, MetService said.

The disturbed west to southwest flow in the wake of the front is then expected to ease as a ridge of high pressure builds over the country from the Tasman Sea.

“There is moderate confidence west to northwest winds will reach severe gale in exposed parts of Hawke’s Bay south of Hastings, the Tararua District, Wairarapa and Wellington.

“There is low confidence west to northwest winds will reach severe gale in exposed parts of Gisborne/Tairāwhiti, Hawke’s Bay about and north of Hastings, Stewart Island and coastal parts of Southland, Clutha and Dunedin.

“Snow may also affect some of the higher South Island roads for a time.”

During Friday, a ridge of high pressure is expected to move onto northern New Zealand from the Tasman Sea, with north westerlies strengthening over the remainder of the country ahead of another front.

“There is low confidence northwest winds will reach severe gale in exposed parts of Fiordland, Southland and Stewart Island.”