Stormy weather to linger — and it’s not normal

Violent thunderstorms are set to lash the country with torrential rain and flash flooding for the fifth day in a row.

The MetService had issued a severe thunderstorm warning for inland areas of the mid and bottom of the North Island and the upper South Island yesterday. A similar weather pattern is predicted to run today.

Thunderstorms yesterday dished out heavy localised deluges, with large hailstones. Some storms today may bring up to 40mm of rain in an hour, sparking flash floods and slips.

The Ministry of Civil Defence warned driving could be hazardous.

The extreme weather yesterday bombarded the country from lunchtime until late evening.

On Tuesday more than 10,000 lightning strikes were recorded over the country and severe thunderstorm cells sparked warnings for the Mackenzie Basin and Marlborough.

WeatherWatch.co.nz head analyst Philip Duncan said the daily thunderstorm pattern was more typical for the peak of summer, not spring.

He explained that the thunderstorms occurred as easterly and westerly winds converged in the middle of the country. They typically started around lunchtime, then peaked from 3pm to 6pm in the North Island and 4pm to 7pm in the South Island, due to their later sunset. The storms subside in the late evening.

“Then they’ll pop back up again tomorrow morning like Groundhog Day.

“It’s very unusual, this pattern. It’s not normal in spring to have long spells of warmer than average calm weather. This is very much like the peak of summer.

“The word ‘normal’ shouldn’t be used. This isn’t normal weather, I think it’ll break quite a few records.”

Duncan said some areas of the central plateau would see a month’s worth of rain this week.

The thunderstorms will continue through until Saturday when a strong westerly takes over the country. The South Island will clear up on Saturday and the whole country will be clear on Sunday.

Fine weather would bring some relief next week except for a small sub-tropical low potentially brushing northern New Zealand, Duncan said.

But mid to late December looked more like spring, with downpours expected to be brought in by a front currently traversing Australia.