Tornado: Auckland residents recall their narrow escapes, report.
The tornado that ripped through a South Auckland shopping centre this morning is a less than once-a-year occurrence for the city, and by New Zealand standards was of a moderate scale.
An East Tamaki twister has torn the roofs off houses and dismantled a double story shop front after a night of heavy storms and strong winds.
And while New Zealand only experiences seven to 10 genuine tornadoes each year, today’s example is an even more surprising occurrence says, one meteorologist.
Metservice duty forecaster Heath Gullery said the drought conditions Auckland has experienced this year are not conducive for tornadoes to form.
“Auckland’s been through quite a large drought so that implicitly means there hasn’t been a lot of rain or thunderstorms to produce a tornado,” Gullery said.
“But the last couple of days there’s been quite an unstable air mass across the upper North Island that has been conducive to tornadoes. That’s what we’ve seen in the last few days.”
New Zealand’s tornadoes are typically 20-100m in diameter, track for just a couple of kilometres, and last only a few minutes.
On the tornado-measuring Enhanced Fujita (EF) scale, New Zealand’s tornadoes are almost always either EF0 and EF1 – that’s wind speeds of 105-137km/h and 138-177km/h respectively – and far from the likes of EF5 tornadoes that rage harder than 322km/h.
Gullery estimated this morning’s twister would be in that EF0 to EF1 range, but they didn’t have the measuring tools to say for sure.
“It’s kind of hard to say from footage because it’s difficult to get perspective of how large it is,” Gullery said.
“Most tornadoes in New Zealand are usually F0 with a bit of a rare F1. It’s more than likely it was an F0 or a very weak F1 tornado.