Weather: Forecasters warn of heavy rain, possible thunderstorms and tornadoes in leadup to Christmas

Auckland faces a moderate risk of thunderstorms tonight, with heavy rain and possible tornadoes to follow. Photo / Sylvie Whinray

• Forecasters have warned heavy rain and possible thunderstorms are tipped for much of the country ahead of Christmas next week.
• Parts of the upper North Island – including Auckland – face a moderate risk of thunderstorms tonight, with a chance of small tornadoes.
• Niwa said New Zealand would likely see heavy rainfall, thunderstorms and elevated humidity levels over the next week.

Forecasters warn festive spirits may be dampened in the lead-up to Christmas next week, with heavy downpours and thunderstorms possible for parts of New Zealand.

A trough will lie across the central North Island this morning, bringing a low risk of thunderstorms from Waikato and Bay of Plenty southwards to Manawatū and Wairarapa – but the risk of thunderstorms increases as the day goes on.

Auckland, Waikato, Waitomo and Taranaki will be in the firing line this evening, with a moderate risk of thunderstorms, heavy rain of 10 to 25mm/h and a possibility of small tornadoes.

MetService meteorologist Clare O’Connor said the last working day of the year for many today brings a shift in the weather.

🎄The countdown to Christmas Day is well and truly on!
However, with a wet start to the holiday break the festive spirit may be dampened a little over the next few days... pic.twitter.com/5pqgOMd7A8

— MetService (@MetService) December 18, 2024

“Cold southeasterly winds and wet conditions set in over the eastern South Island as the low pressure sinks southwards. The dry and sunnier spell of weather in the western and northern parts of the country comes to an end with the arrival of a broad band of rain and northerly winds from the Tasman Sea,” O’Connor said.

“For anyone setting out for their Christmas break and travelling through the central and upper North Island this afternoon and evening, adverse conditions may cause delays and disruptions to travel plans.”

She said where northwesterly and southeasterly winds meet over the North Island was an area “to approach with caution” on Friday.

“The converging air enhances the risk of downpours of rain – and possibly even thunderstorms in these areas.”

Meanwhile, forecaster Niwa says over the next week, New Zealand is likely to see slow-moving areas of low pressure periodically moving through, with moderate to heavy rainfall, thunderstorms and elevated humidity levels.

This chaotic-looking animation shows vorticity (a fancy nerd term for spin 🤓) in the upper atmosphere. This often corresponds to low pressure at the earth's surface.

This shows us that over the next 7-10 days NZ is likely to see slow-moving areas of low pressure with rain. 🌧️ pic.twitter.com/iiqThD4tng

— NIWA Weather (@NiwaWeather) December 18, 2024

O’Connor said rain or showers are expected “right across the country” at various points of the weekend – warning those waiting for a window of ideal travelling weather to summer hotspots would likely be waiting until at least Monday.

She said the best weather in the lead-up to Christmas Day looked to be the two days preceding the holiday, with sunny blue skies and dry days set for most parts of the country on Monday and Tuesday.

“While there is still almost a week to go to the big day itself, Santa has been advised to pack his wet weather suit for the big journey south, with the outlook indicating a wet Christmas Day for the west of the South Island and potentially the western North Island also.”

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