Terrifying but NZ twisters are minor
Global warming is likely to bring more tornadoes to New Zealand’s shores but they will never be as big as the twisters that ravage the US, a Metservice forecaster says.
Two tornadoes tore into North Island towns on Monday night within minutes of each other. At 5.30pm more than 30 homes were damaged when a twister blasted ashore in New Plymouth for a terrifying minute before dissipating.
Less than 30 minutes later another tornado came ashore in Whakata¯ ne, damaging houses there.
MetService severe weather forecaster John Crouch said more thunderstorms were forecast for the country and there was a low tornado risk for coastal parts of Northern Taranaki.
‘‘But at this stage it’s more of a thunderstorm watch than a tornado watch,’’ he said.
Despite the terror of two twisters in minutes Crouch didn’t believe there was any reason for people to build tornado-proof bunkers just yet.
He said only minor tornadoes occurred in New Zealand and it was unlikely the country would ever experience a twister comparable to those in
the US which destroy whole towns.
Tornadoes in the Midwest of the USA usually reached 4 to 5 on the damage measuring Enhanced Fujita (EF) scale. In New Zealand tornadoes usually rate either 0 or 1 and would only rarely get to 3.
Despite there being multiple homes damaged in Monday’s tornado, Crouch said it still sat on the lesser end of the EF scale with a lifespan of about five to 10 minutes. ‘‘Our thunderstorms just aren’t strong enough. But as the climate warms we will probably start to see more of a similar scale as Monday’s tornado.’’
‘‘I think the general trend is climate change can lead to more frequent and severe thunderstorms.’’
Most tornadoes form from thunderstorms, he said. Intense thunderstorms often have a strong updraft, meaning it draws in air from beneath the storm quite rapidly. ‘‘If there was any natural spin it sort of stretches it out and forms a tornado.