Just what is a “normal winter” in New Zealand? It’s something I’ve been thinking about a lot since a government agency recently started to talk of stratospheric warming over Antarctica.
While that is a very real thing and is so significant scientists around the planet are talking about it, what does it REALLY mean for New Zealand’s weather? The last time it happened, a few years ago, no one noticed it weatherwise in NZ.
This time around we may do. When there is warming occurring high up in the stratosphere it can make the storms that circle Antarctica more “loose”. Rather than fitting tightly around Antarctica, this year it’s like someone stretched the elastic and it means the Southern Ocean weather has a greater chance of sending out lows, fronts, southerlies and even large highs.
But whether they hit NZ, Tasmania or the land-free Pacific Ocean to our east is the million-dollar question.
When someone says this August may be stormier in NZ – in the depths of winter – my first thought is “What do we expect?” What is “normal” weather for two large mountainous islands all alone at sea, smack-bang halfway between the equator and Antarctica with more than half of our nation in the Roaring Forties belt of windy westerlies circling latitude 40?
As Jamie MacKay from Newstalk ZB’s The Country always says, “Forewarned is forearmed” – but because NZ is so small, we can sometimes buck the international trends. We recently had an El Niño event that, despite the hype, turned out to be no where near as dry as two of the three previous La Niña events that were headlined as being “wet” but instead brought major widespread drought.
My point is, chaos IS New Zealand’s normal. The Southern Ocean, which brushes the South Island, is the stormiest body of sea BY FAR on the planet. The gales that roar south of NZ can blow right around the entire globe and never touch land once. That’s impossible to do in the northern hemisphere.
All that wild energy – with polar blasts of air that are from places -50degC heading our way, at the same time as a tropical cyclone from near Fiji might be too, or a calm and settled high pressure zone exiting Australia that acts like Superman holding these frigid and tropical air masses from colliding over us, giving NZ those frosty blue dome days so many of us love in winter …
NZ is the “Goldilocks” belt between the freezing airmass and the tropical airmass with anticyclones that sometimes protect us from both – or encourage more from both.
This warming up high in the skies over Antarctica may very well unleash us more storms, so it’s good knowing there’s an increased chance of severe winter weather and simply having that in the back of your mind to be on the look out for them.
But also, hearing winter may be stormy feels like someone also saying “the sea may be a bit wet”. Perspective is always key.
