MetService warns of thunderstorms possible tornadoes for Auckland, upper North Island

MetService has issued a severe thunderstorm watch for much of the upper North Island.

Northland, Auckland, Great Barrier Island, Coromandel Peninsula, Waikato, and  Bay of Plenty are all under the watch, which lasts from 7pm tonight until tomorrow morning at 8am.

"An unstable airmass with embedded troughs is expected to affect the upper North Island this evening, overnight and into Saturday morning," Met Service says.

"In much of Northland, Auckland, Coromandel, the north of Waikato and the far west of the Bay of Plenty, thunderstorms are likely and there is a risk that some of these could be accompanied by downpours with rainfall intensities of 25 to 35mm per hour and tornadoes with strong wind gusts.

"Wind gusts of this strength can cause some structural damage, including trees and power lines, and may make driving hazardous. If any tornadoes occur, they will only affect very localised areas.

"Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

"Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain," the weather warning states.

It comes as a tornado caused damage in Mangawhai, Northland when it touched down around 4pm this afternoon.

Footage sent to 1 NEWS shows a well formed tornado making its way across paddocks in the distance.

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1 NEWS reporter Andrew Macfarlane has this update. Source: 1 NEWS

Maggie Deena was a few houses away when she saw the tornado.

Speaking to 1 NEWS, she said she initially thought it was a house fire.

“There was loads of debris with it," she said.

Alison Bain, who works at Mangawhai Landscape Supplies told 1 NEWS the tornado sounded like a train.

“It was raining really heavily and there as really loud noise”.

She said it was all over in a couple of minutes.

“We were quite worried it was coming towards us.”

According to St John New Zealand, there were no injuries from the tornado reported to them.