Weather: Severe thunderstorm, torrential rain warning for Auckland

Thunderstorm clouds are sweeping across Auckland, bringing torrential rain and the risk of flooding.

The MetService issued a severe thunderstorm warning for Auckland, Rodney, and Albany from 6pm to 7.45pm on Monday as the storm moved south through the city.

Showery weather and thunderstorms are expected across much of the country in the lead up to Christmas thanks to a low sitting off to the west.

“At the moment we’ve got a low pressure system out in the Tasman Sea, which is just hanging around for the next few days. What that means is New Zealand is sandwiched in between higher pressure and lower pressure,” said MetService metrologist Dan Corrigan.“

There are warm temperatures at the surface during the afternoon, and slightly cooler temperatures higher up in the atmosphere. Those give us some of the ingredients for thunderstorm development.”

Differing air temperatures cause the atmosphere to become unstable and can result in stormy, thundery weather.

MetService earlier issued a severe thunderstorm watch for Taranaki, Taihape, Whanganui, Manawatū, Tararua until 8pm on Monday. A slow moving line of thunderstorms are set to bring heavy downpours in affected areas.

There is a moderate risk of thunderstorms across the central North Island and inland Northland on Monday, according to MetService.

Storms may produce hail up to 15mm in diameter, and there is also low risk of small localised tornadoes.

Further south, there is also a moderate risk of thunder across the West Coast. Some thunderstorms had been detected around Westport and Buller on Monday morning as a small band of rain moved in from the west, Corrigan said.

Widespread heavy showers and thunderstorms are possible across the country on Tuesday, and rain is forecast to stick around until the weekend.

A heavy rain watch is in place for the Hawke’s Bay and Wairarapa until early Wednesday morning, and may be upgraded to a warning as the situation progresses. Downpours up to 40mm are expected on Tuesday afternoon.

Auckland will see showers right through to Christmas Day, with highs of 24-25C forecast for the rest of the week.

Wellington is a similar story, with showers lingering until Saturday but clearing for a fine day on Christmas. High temperatures will sit between the high teens and low twenties.

Isolated showers will stick around in Christchurch, easing slightly for a partly cloudy Christmas Day on Sunday. Maximum temperatures will range from 17-23C.