A severe weather warning has been issued for inland Otago,
Canterbury, Fiordland and Westland ahead of expected heavy rain and
MetService said the large anticyclone that has dominated skies over the last week moves away to the east, allowing a deepening low pressure system to cross the Tasman Sea - bringing with it strengthening winds and a spell of heavy rain.
"This high will edge away during the weekend, allowing the developing system in the Tasman Sea to move towards the country," MetService forecaster John Law said.
MetService said this will bring heavy and thundery rain for western areas of the South Island, and potentially gale-force northwesterlies across much of the rest of the island.
A strong wind warning has been issued for inland parts of Canterbury and Otago. MetService said northwest winds will strengthen to gale force from Saturday night through to Sunday afternoon, with gusts of up to 140 kilometres an hour expected.
On Sunday gales are likely to develop in inland Southland, Marlborough and Wellington, which are under a Severe Gale Watch.
The heaviest rain is expected over the ranges of Westland south of Otira where 250mm may fall from Saturday night through to Sunday night, with up to 150mm about Fiordland.
Significant spillover rain is also expected for Canterbury and Otago headwaters.
The forecaster said winds of this strength can damage trees, powerlines, insecure structures and make driving conditions hazardous.
People in these areas are being warned streams may rise rapidly, slips and surface flooding are possible.
"By Sunday afternoon the heaviest rain should have cleared the south of the country. However, as this feature continues to move northwards, it does look to be a wet start to the week for the North Island," Law said.
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