Cyclone Gabrielle: Tairāwhiti Gisborne thunderstorms ‘could have exacerbated issues’

Thunderstorm-related rainfall on Thursday afternoon could have exacerbated issues in the cyclone-hit Tairāwhiti Gisborne area, according to MetService.

Severe thunderstorm watches had been issued by the agency from 3pm until 10pm on Thursday, covering Tairāwhiti Gisborne, Hawke’s Bay, Rotorua, Taupo, and Bay of Plenty.

By about 7pm, MetService had already registered 4400 lightning strikes throughout the afternoon and evening.

However, as of Friday morning there are no severe weather watches in place.

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Just after 4pm on Thursday, Metservice’s weather radar detected severe thunderstorms near Waiptapu, Waikite Valley, Waireka and Guthrie.

These thunderstorms were expected to be accompanied by torrential rain.

James said the weather event was “going to be very localised – and will be very different to the widespread rain from the last few days – but with ground already sodden and rivers still high, even localised rain will be problematic”.

“A few showers” were set to hang around into Friday morning, but the weekend would see more settled weather across the country, he said.

When the severe thunderstorms watches were alerted on Thursday morning, MetService said “very unstable conditions” could be generated over northern and central parts of the North Island with scattered thunderstorms bringing localised heavy rain and hail”.

Rainfall rates were expected to get up to 40mm an hour during localised downpours.

“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,” MetService said.

“Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.”

MetService meteorologist Ashlee Parkes added that the heavy rainfall forecasted in central New Zealand was the “tail end of Cyclone Gabrielle”.

MetService reiterated the National Emergency Management Agency’s advice that, as storms approach, people should:

• Take shelter, preferably indoors away from windows
• Avoid sheltering under trees, if outside
• Get back to land, if outdoors on the water
• Move cars under cover or away from trees
• Secure any loose objects around your property
• Check that drains and gutters are clear
• Be ready to slow down or stop, if driving.

During and after the storm, you should also:

• Beware of fallen trees and power lines
• Avoid streams and drains, as you may be swept away in flash flooding.