Action Weather

The sunny afternoon in Wellington is a welcome change from yesterday with its chill and gloomy skies and vivid thunderstorms. In Auckland, large hailstones and cellphones have fallen from the sky, while the deep south shivers under snow and a polar blast.

Last night’s vivid thunderstorms that soaked evening commuters in Wellington were just one aspect of the unusual weather patterns affecting the country. The passage of a very deep low through the centre of the country brought abrupt pressure changes and dragged the belt of thunderstorms with it. The thunderstorms really fired up between 5 pm and about 5:25, just in time to douse happy commuters. Here at Tawa, the weather station showed a nice blip in air pressure from 970 to 972 hPa at the height of the storm, before setting a new record low reading in the station’s life (since Jan 2005) at 969 hPa.

Although only 4 mm rain fell at the time, it was delivered with a terrific squall that allowed the rain rate to reach the equivalent of 72 mm/hr briefly.

Meanwhile, central Otago was treated to an abrupt dumping of snow that closed many roads and trapped people in their cars briefly yesterday. Schools were closed, Queenstown airport closed, and both Queenstown and Arrowtown were isolated by road within a few hours.

With the passage of the low pressure system to the east of the country, the steep pressure gradients to the west have brought a polar blast to southern parts of the country and further snow. Central Otago continues to shiver, and Southland is now receiving snowfalls.

Mid-morning, Auckland experienced an impressive thunderstorm complete with rain and large hail. Fork lightning was reported from Papakura, and hail the size of the old 50 cent pieces was reported at New Lynn and Henderson. When a member of the NZ Weather Forum posted a photograph of the agglomerated hail, which does indeed seem to be 50c-sized, he left a cellphone in the frame to illustrate the size of the hailstones. This immediately drew the comment “Wow! How many cellphones fell??” from the deep south.

In the midst of regular weather reports being posted to the forum, there was still time for north-south banter. With snow closing roads, the electricity repair crews need to get through to maintain service. But skiers are a determined bunch, even if they don’t have much experience with driving their 4x4s on snow-covered roads. With the Omarama-Twizel road officially closed, service vehicles still had to swerve out of the path of ski groups tentatively driving their vehicles along the centre of the highway.

This posed the question: “What’s the difference between those vehicles and a hedgehog?” Runner-up answer was “You swerve for hedgehogs.” But the winner was: “A hedgehog has all its pricks on the OUTSIDE.”

The chilly conditions of recent days have driven electricity demand to new records, with a peak national load of 7 GW having been reported by Radio New Zealand National. With the North Island shivering on Wednesday night, it drove the demand peak that night, while the South Island contributed the greatest load last night.

Latest reports are of steady snow falling in Invercargill, Gore and Omarama and, as it’s sticky snow, it is likely to cling to power lines and bring them down if it builds up too much. Queenstown airport is unlikely to open before 4 this afternoon, and tourists are advised to stay put and off the roads in the area.

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