MetService has issued a severe weather outlook for the week ahead.

On Tuesday a front is expected to move north over the west of the South Island and this may move slowly north over central New Zealand on Wednesday.

There is a moderate confidence that rainfall accumulations will reach warning amounts in Fiordland, Westland, Buller and the far west of Nelson. A watch for heavy rain has already been issued for Fiordland.

On Wednesday the front may move slowly north over central New Zealand.

There is still considerable uncertainty with respect to the distribution and amount of rain expected. There is a moderate confidence that rainfall accumulations will reach warning amounts in Buller and Nelson and a low confidence in a broader area including the north of Westland, the north and west of Marlborough, the south of Wairarapa, Wellington, Kapiti and Taranaki.

On Thursday and Friday a moist northerly flow is expected to affect the west of the South Island and at this stage there is a low confidence that rainfall accumulations will reach warning amounts in Fiordland, Westland, Buller and the far west of Nelson.