Significant heavy rain for the northwest of the South Island
Multiple fronts embedded within a strong moist north to northeast flow affect the country from Tuesday through into early Friday, bringing heavy rain and gales to the north and west of both islands. This flow should ease during Friday as a ridge of high pressure builds over the upper North Island. Meanwhile, a slow-moving ridge builds over the lower South Island from early Wednesday. See latest Severe Weather Warnings and Watches at www.metservice.com.
There is high confidence of rainfall reaching warning amounts over Buller, Tasman and Nelson, and northern Marlborough from Tuesday through into Thursday, with confidence reducing to low early Friday. There is also high confidence a heavy rain warning will be required for Westland on Tuesday and Wednesday, with confidence reducing to moderate on Thursday. On Wednesday and Thursday, there is moderate confidence of heavy rain about western parts of Marlborough and the headwaters of the Canterbury lakes and rivers as indicated on the chart.
For Mount Taranaki, there is high confidence of rainfall reaching warning amounts from Wednesday into Friday, while for the remainder of Taranaki, the Whanganui headwaters and Taihape, there is moderate confidence of heavy rain on Thursday and Friday. There is low confidence that a heavy rain warning will be required for southern parts of Northland, Auckland, Coromandel Peninsula and Bay of Plenty on Thursday, while for the Tararua Range there is low confidence on Thursday and Friday.
Additionally, there is moderate confidence of severe gale north to northeasterlies for much of Northland late Wednesday and Thursday, with low confidence for southern Northland, Auckland, Coromandel Peninsula, Taranaki, Central North Island High Country, Wellington, Marlborough Sounds, Nelson and Tasman, and northern Buller on Thursday.