Torrential rain warnings for West Coast and the Alps

Sunday, 24 March 2019

Torrential rain is predicted for parts of the West Coast and the ranges from Monday until Wednesday. Some places may have more than half a metre of rain (file pic).

More than half a metre of rain is likely to fall on parts of the West Coast and in the Southern Alps from early Monday until Wednesday.

While only a fraction of that amount of rain is expected to make it across the main divide to the Canterbury Plains, people in eastern parts of the South Island are being advised to prepare for northwesterly winds up to severe-gale force in exposed places.

The weather during the last few days of March looks a mixed bag and very windy at times, but no significant cold spells are on the cards.

Severe Weather Warnings are now in place as NW winds bring heavy rain to parts of the South Island over the next few days. Details at https://t.co/5g5AYiYBwb ^RK pic.twitter.com/MiF7Bd7k2y

— MetService (@MetService) March 23, 2019

MetService has issued a severe weather warning for 'significant heavy rain' in Fiordland, Westland and along the headwaters of the Canterbury and Otago rivers and lakes.

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Westland south of Otira could have as much as 600mm of rain about the ranges between 1am Monday and 11pm Tuesday, with 150mm to 300mm closer to the coast. Between 30mm and 40mm of rain an hour could fall on Tuesday.

The headwaters could have 300mm to 500mm from 3am Monday to 11pm Tuesday.

A severe weather watch has been issued for northwesterlies up to severe-gale force for Canterbury, including Christchurch, between 3am and 11pm on Tuesday, and from 1am to 5pm in Otago.

MetService meteorologist Josh Griffin urged residents to be aware of the possibility of flooding and slips.

'Even though these areas do see a good amount of rain, this is pretty exceptional amounts. There is risk of surface flooding and possible road closures,' Griffin said. 'Slips are always a potential with rainfall like this.'

The rainy weather is being caused by a moist north-to-northwest flow, spreading onto Fiordland on Sunday ahead of an active front, which is then expected to move northwards over the South Island on Tuesday.

The front would be preceded by strong or gale force northwesterly winds, Griffin warned.