Orange heavy rain warnings have been issued for the already saturated top of the South Island as well as for the Bay of Plenty.
Northland and Auckland were also under heavy rain and strong wind watches for Thursday.
MetService said a large low over the Tasman Sea and its associated fronts would bring heavy rain and strong winds to central and northern parts of the country from Thursday.
Up to 220mm of rainfall would be possible in localised areas of the Tasman District west of Motueka between 3am and 9pm on Thursday.
The forecaster said peak rates of up to 25mm an hour were possible.
“Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.”
The rest of the Tasman District, as well as Nelson, the Richmond and Bryant Ranges, and the Marlborough Sounds also were forecast to receive up to 80mm of rain between 6am and 9pm on Thursday.
The Bay of Plenty was also in the firing line with orange heavy rain warnings issued there.
West of Whakatāne, rain was forecast to fall from 8am Thursday to 3am Friday, with 90-120mm expected inland and peak rates of 15-25mm/h, possibly up to 40mm/h in localised downpours.
Rain was forecast about and east of Whakatāne from noon Thursday to noon Friday, with 100-130mm likely and 150-180mm possible near the ranges.
The upper North Island was under heavy rain watches and strong wind watches for Thursday, with Northland, Auckland, Great Barrier Island and the Coromandel Peninsula all forecast to have localised downpours and northeast winds that could approach severe gale in exposed places.
Widespread flooding is threatening homes, triggering slips and shutting major highways. (Source: 1News)
Clean-up continues in sodden Nelson-Tasman
More than 300mm of rain fell in some areas late last week, leading to widespread flooding, slips and road closures across the region.
A man was killed while clearing some of the flooding damage.
Two localised states of emergency remain in place as the clean-up across the region continues.
Tasman District Council said the rain warnings were “not the news we wanted right now”. The council provided an update from its hydrology team on what to expect.
“While under normal antecedent conditions, these totals combined with a short duration event would produce low to moderate floods. However, we are far from normal, with very saturated ground and compromised infrastructures.”
The council said Golden Bay’s larger rivers should hold the forecast rainfall but smaller catchments would “react quicker”.
“We can expect further surface flooding, landslipping and road closures to already compromised roads and associated structures.”
Nelson Mayor Nick Smith said there had been millions of dollars worth of damage to roads, bridges, fences, farm buildings, hop gardens, orchards, and the Great Taste cycleway.
“The worst areas are Wai-iti, Tapawera, Motueka Valley, Kohatu, Motupiko, Pretty Bridge Valley and Tadmor.”
Marlborough District Council said a large slip on the northern bank of the Wairau River, had closed a section of Northbank Rd and cut off access to residents.
The rock fall came down overnight , closing the road before the Onamalutu Rd turn-off.
Marlborough Roads system manager Wayne Oldfield said the slip was still moving and public safety was of “paramount importance”.
“Geotechnical assessments carried out today have shown that the site is unstable.
“It is unfortunately very unlikely that the road will open today as it is a very large slip with the added dynamic of it being unstable as well. Crews are on site and clearance works will start as soon as it is safe to do so.”
Full list of weather warnings and watches
Heavy Rain Warnings – Orange
Bay of Plenty west of Whakatāne – 19 hours from 8am Thursday to 3am Friday.
Bay of Plenty about and east of Whakatāne – 24 hours from noon Thursday to noon Friday.
Tasman District west of Motueka – 18 hours from 3am to 9pm Thursday.
Remainder of the Tasman District, Nelson District, the Richmond and Bryant Ranges including the Rai Valley, and the Marlborough Sounds – 15 hours from 6am to 9pm Thursday.
Heavy Rain Watches
Northland – 15 hours from 3am to 6pm Thursday.
Auckland, Great Barrier Island and Coromandel Peninsula – 6 hours from 9am to 3pm Thursday.
Tairāwhiti/Gisborne north of Ruatoria – 21 hours from 3pm Thursday to noon Friday.
Taranaki Maunga – 9 hours from 6am to 3pm Thursday.
Strong Wind Watches
Northland – 12 hours from 6am to 6pm Thursday.
Auckland, Great Barrier Island and Coromandel Peninsula – 9 hours from 9am to 6pm Thursday.
