New heavy rain warnings for flood-hit regions including Auckland

MetService has issued new heavy rain warnings for the already saturated regions of Northland and Auckland.

It also warned some heavy rain could fall in northwest Tasman, and in the Richmond and Bryant ranges, the Rai Valley area and the Marlborough Sounds, on Monday morning and into the afternoon.

Other areas considered at risk of heavy rain in the next few days are Coromandel Peninsula and the Bay of Plenty, including Rotorua.

There’s also a risk of intense downpours in Northland during severe thunderstorms on Monday morning, with the risk moving to many central areas of the country during the afternoon and evening.

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Four people have died and thousands of homes have been damaged after heavy rain, flooding and slips hit Auckland, Waikato and the Bay of Plenty.

The new heavy rain warning for Northland, issued by MetService on Monday morning, covers the 24 hours from 4am Tuesday. During that time up to 140mm could fall in the north and east of the region, with a possibility of as much as 220mm falling in some localised areas.

For Auckland, the new warning covers 12 hours from 6pm Tuesday. During that time, up to 80mm could fall in some areas of the region north of Auckland city, with a possibility of up to 120mm in some places.

MetService meteorologist John Law said the threshold for a heavy rain warning – compared to a less severe watch – had been lowered temporarily for Auckland and Northland because the ground in the regions was already saturated.

The criteria for a warning was normally 100mm of rain in 24 hours, but had been lowered to 70mm for Auckland, Law said.

There’s also a chance that northeast winds could approach severe gale strength in Northland from 10am Tuesday, and in Auckland from 1pm Tuesday.

A heavy rain watch for Coromandel Peninsula covers the 18 hours to 6pm Wednesday, while for the Bay of Plenty, including Rotorua, it covers the 21 hours from 6am Wednesday.

After being deluged by massive amounts of water on Friday, the rainfall eased up in the north of the country over the weekend, but returned more heavily overnight to some areas.

In the Auckland region, the heaviest rain overnight was in the area around Warkworth and Wellsford, with 70-100mm falling between 6pm Sunday and 6am Monday, Law said. Some other parts of the region had 40-50mm in the 12-hour period.

Some parts of Northland also had heavy rain, with 74mm in Kaitaia in the 24 hours to 8am Monday, most of that in the early hours of Monday, including 35mm in the hour to 5am.

About 100mm of rain also feel overnight in parts of the ranges of the Coromandel Peninsula, Law said.

The rain was pulling away from Auckland towards the north on Monday, but wasn’t going far and would then return. “So it’s a brief break.”

The risk of severe thunderstorms for central parts of the country on Monday are for the period from 1pm to 9pm, and cover the areas of Taihape, Whanganui, Manawatū, Tararua, Wairarapa, Marlborough, Nelson, Buller, Canterbury Plains, and the Canterbury High Country.