Watch: Big tornado in mid Canterbury

A tornado has rolled through Canterbury this afternoon.

The twister was captured by local resident Alesha Plew as she and her husband Richard were driving along State Highway 1 north of Ashburton.

"My husband looked up and just said… what is that? It was just a massive tornado, a big brown twister."

The couple came within metres of the tornado as debris flew about the road, but their vehicle wasn't damaged.

Plew said they'd driven through a severe hailstorm in Ashburton, before the skies cleared.
And then the twister appeared in a paddock beside them.

"We kind of kept driving straight past it – it was a couple of fields away from us at the time," she said.

"It ended up coming about 10m from the car, and there was debris and dirt flying around."

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While other motorists stopped to witness the spectacle, she and her husband kept driving.

"While it looked dangerous, it didn't feel that way – it didn't feel like it was sucking us in, anyway."

For Plew, who hadn't seen a tornado before, the event was a once-in-a-lifetime experience.

"It was quite amazing… just to be looking up at it from so close… it was incredible."

This afternoon, hailstones the size of marbles and whirling winds pelted properties in Mid and South Canterbury and a thunderstorm lashed the region.

MetService meteorologist Tui McInnes said "substantial" hail between 20 and 30 millimetres started to pour down over Ashburton around 3pm Sunday.

MetService earlier issued a severe thunderstorm warning and said the storms were expected to move northwards through Mid Canterbury during the afternoon and evening.

"These thunderstorms are expected to be accompanied by large hail, damaging wind gusts and possible tornadoes," MetService warned.

There was a moderate risk the storms could produce localised damaging tornados and strong winds gusting more than 120kmh.

McInnes said small tornados, or vortexes, were possible of the updraft caused by the thunderstorm.

A "broad set of ingredients", including cold air high in the atmosphere, coupled with warm surface heating and north-east sea breezes bringing high moisture levels, combined to create the perfect conditions for the storm.

"Thunderstorms usually don't last more than an hour before collapsing so it's passed its peak and moving offshore but they can trigger others further up the line." He anticipated further storms would continue in the surrounding areas overnight.

Netherby resident Matt Banks said hailstones "about the size of a ten cent piece" pounded his property and thunder and lightning could be heard in the distance on Sunday afternoon. The storm passed quickly but there were some "pretty ominous clouds heading our way", he said.

MetService warned that "large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, and make driving conditions hazardous."

"Very strong wind gusts can break branches from trees, damage roofing, and make driving hazardous especially for high-sided vehicles and motorcycles.

Just as we were all getting set for jandal weather, forecasters are some predicting some pre-summer snow.

Over coming days, MetService was forecasting a complex weather system to move over the country, bringing an extended period of wet and cold weather.

"Most people can expect to see some rain over the next few days - however, snow is surprisingly the main focus of this event," forecaster Tui McInnes said.
Considering we were at the end of spring and on the cusp of the summer months, snow was not something typically thought of at this point, she said.

"While not unheard of, snow is uncommon this late into the year."
Snow levels were set to lower significantly for the South Island, with a dusting even possible for Central Plateau.

"Cold temperatures associated with this weather system means we could see snow to 400m in Southland and 500m in Otago and Canterbury - and there are a handful of severe weather warnings and watches in place, so this is certainly an event to stay up to date with."

MetService was forecasting a risk of hail also, which could impact horticultural regions.

"This weather brings unstable air with it, prime conditions for hail showers."
In Auckland, showery weather was forecast for the first three days of the week, with Monday's overnight low falling to 9C.

Wellington would be colder and wetter still, with Tuesday's maximum reaching just 13C.