MetService upgrades heavy rain warnings for parts of North Island north and east, Tairāwhiti highway closed

MetService upgraded its heavy rain warnings for parts of the north and east of the North Island on Wednesday evening, while in Tairāwhiti a lengthy section of SH35 remained closed by flooding.

The new warnings issued about 8pm Wednesday show rainfall is expected to be heavier than earlier anticipated in Northland, Coromandel Peninsula and western Bay of Plenty.

Heavy rain started falling around the middle of the day in Northland and Tairāwhiti, and was forecast for northern parts of Auckland from 9pm, and for Coromandel and western Bay of Plenty from 1am Thursday.

From 8pm Wednesday to 5am Thursday, Northland was expected to get another 50-70mm of rain, the new warning said.

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Coromandel and Bay of Plenty west of Te Puke were forecast to get 140-180mm through to noon Friday, with the heaviest rain on the peninsula.

Tairāwhiti from Tolaga Bay north was expected to get another 90-140mm between 8pm Wednesday and 6pm Thursday.

While that area might get a brief respite overnight Thursday, MetService said it expected periods of heavy rain to return early Friday, and to spread throughout Tairāwhiti as winds turned more easterly. Heavy rain was expected to continue in the region through the weekend.

Gisborne District Council warned that with the ground in the area already saturated, surface flooding and more road slips and dropouts were expected.

The district still has 18 roads and 17 bridges closed, with another 10 roads closed to heavy vehicles as a result of damage caused by Cyclone Gabrielle in February.

Waka Kotahi said heavy rain and flooding closed SH35 between Okitu, near Gisborne, and Ruatoria about 4pm.

MetService reported that in the Raukūmara Range in northern Tairāwhiti, 55mm of rain was recorded by 4pm, most of it since noon.

Kaitaia recorded about 50mm of rain between 9am and 5pm, with about 20mm in the hour from 11am to noon.

“There was a cluster of lightning strikes and thunderstorms embedded in a band as it went over at the time,” MetService forecaster Aidan Pyselman said.

A little further south, 19mm of rain fell from the same rain band as it passed over Kaikohe between 2pm and 3pm.

The rain is linked to a low pressure system just to the west of Northland on Wednesday afternoon, and expected to slowly cross the north of the country through until Saturday.

It would direct moist northeast winds with several embedded fronts across northern and central regions, MetService said.

Periods of heavy rain were also expected in eastern Marlborough south of Ward from mid-afternoon Thursday through to Saturday evening.

And there was “moderate” confidence of heavy rain in Hawke’s Bay and the Kaikōura Coast and ranges on Friday and Saturday, MetService said.

The winter solstice – the moment the Sun appears to be at its most northern point when viewed from Earth – will be at 2.57am Thursday.

While Thursday has the least daylight hours of the year, the difference from Wednesday is less than a second, according to Time and Date.

It calculated Auckland would have a day length of 9h 37m 54s on Thursday, Wellington would have 9h 11m 23s, and Christchurch 8h 56m 21s.

It may be the darkest time of year, but Pyselman said temperatures were forecast to have a “mild run” through into next week.

For many places temperatures would be well above average, particularly at night, for the time of year. Exceptions were Northland, where temperatures would be around average, and Southland, where temperatures were expected to drop to the low single digits during the night.