Severe winds, thunderstorms and hail possible for parts of NZ tomorrow

Spring is off to a typically messy start, with more blustery westerlies in store for the week – and a risk of thunderstorms in the south.
MetService has issued heavy rain watches for parts of the South Island’s West Coast throughout Monday, including Westland’s ranges, the headwaters of the Canterbury lakes and rivers south of Arthur’s Pass, and Fiordland north of George Sound.
For areas such as southern Fiordland, coastal Southland and Stewart Island, MetService also warned of a “moderate” chance of thunderstorms on Monday afternoon and into the night.
“These thunderstorms are expected to bring heavy rain of 5-15mm/h and hail 5-15mm in diameter.”
Elsewhere, in exposed parts of the Canterbury foothills and High Country, along with inland Marlborough and about the Kaikōura Ranges, there was a risk that strong northwest winds could hit gale strength during Monday afternoon and night.
Severe northwest gales were also possible in Wellington and Wairarapa throughout Monday afternoon and night, MetService reported.
Beyond that, the westerly pattern was expected to bring a mixed bag of weather for the week, with both islands experiencing a combination of showers and fine weather.
On Tuesday, the North Island was forecast to receive scattered showers – particularly in the west – while the South Island could see rain developing in the west and far south, with fine weather elsewhere until later showers hit Otago and Canterbury.
By Wednesday, skies over the North Island were due to clear, with more sunny weather in store for Thursday.
The pattern has been making for hot, dry days in eastern regions, with Christchurch Airport registering a balmy 25C on Saturday.
Napier, which recorded Sunday’s maximum of 17.1C, was forecast along with Hastings to hit 22C on Tuesday.
The flows have also been causing headaches for fire crews.
In rural Central Otago’s Tokarahi, it took six helicopters, two planes and ground teams to contain an out-of-control burn-off that tore through 400ha of farmland, amid 100km/h winds.
Earlier, in Waipara in northern Canterbury, crews spent 10 days battling a fire that scorched more than 100ha of forestry.
WeatherWatch said the windy set-up partly owed to high pressure parked just to the north of the country.
“That high acts like a lid and stops the low pressure from moving up New Zealand, and that process puts the ‘squeeze’ on the air pressure, making for windier weather.”
The good news, it added, was the westerlies were likely to die down over the second half of the week.
Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.
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