Thunderstorm, tornado risk for Auckland and Northland as wet weather eases in East Coast

Though unwelcome heavy rain is set to ease for cyclone-hit Tairāwhiti and Hawke’s Bay on Sunday, those in Northland and Auckland could be due for some with a risk of thunderstorms.

MetService-issued heavy rain warnings in place since Friday morning are set to end early on Sunday morning, for Gisborne at 3am and for parts of Hawke’s Bay north of Napier at 8am. An earlier warning for areas south of Napier was lifted on Saturday morning.

The regions appear to have escaped the worst of the weather with previous rainfall predictions of between 150mm to 200mm halved, to between 40mm to 70mm.

While rainfall accumulations were forecast to be lower than previously expected, MetService warned impacts could still occur.

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However, an active trough moving southeast onto the North Island on Sunday afternoon was expected to bring further rain and the possible risk of thunderstorms.

MetService warned there is a moderate risk of thunderstorms for Auckland, Northland and Great Barrier Island from Sunday evening, bringing heavy rain of between 10mm and 25mm an hour, small hail and up to 100kmh wind gusts.

There is also a chance of localised tornados, including a low risk of one or two severe damaging tornados.

Later that night there is a moderate risk of thunderstorms for the north of Taranaki, Waikato, the south of the Coromandel Peninsula and the coastal Bay of Plenty and a low risk of thunderstorms in the far west of Tasman, the remainder of Taranaki, Waitomo, Rotorua and the north of Gisborne.

Tairāwhiti Civil Defence said while rain had been steady on Saturday, no issues had been reported and the rainfall totals and river levels were “not raising any concerns” with the system appearing to be moving further east.

It warned heavy rain could still cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

A wave warning remains in place from Mahia to Hicks Bay until 2am, with the highest risk at high tide just before 8pm on Saturday.

Further south, Hawke’s Bay Civil Defence was also optimistic, describing river levels and rainfall as “relatively low”.

“The forecast for Napier is looking better than was forecast yesterday, but we still expect some scattered showers during the day, with slightly heavier rainfall after midnight,” a post on its Facebook page read.