The science of the incessant wind
Two months of incessant wind is “getting a bit unusual, even for Wellington”, weather and climate scientist Professor James Renwick of Te Herenga Waka—Victoria University of Wellington says.
3 December 2019
With more gales or severe gales predicted for the capital today, Professor Renwick, Head of the School of Geography, Environment and Earth Sciences, says the outlook for the next couple of weeks is not that encouraging either.
“But I’ve got my fingers crossed that the winds might finally drop towards Christmas.”
That, however, is as much a thought driven by optimism and past experience of windy Wellington springs as one borne out of science.
Professor Renwick says it is not just Wellington that is suffering from the constant blustery winds, but many other parts of the country too.
“It’s the negative value of the Southern Annular Mode, or SAM, that has been bringing the storm tracks further north and closer to New Zealand over the past two months, and keeping the high pressures further north than usual as well.
“It’s not rare, of course, for Wellington to have windy springs. We’ve had some nice days too, but getting on for two straight months of wind seems unusually long.”
The value of SAM is expected to stay negative for at least another 10 days or so, possibly longer, he says.
It would be an interesting study to see how out of the ordinary the current wind pattern is.
“I keep meaning to re-look at the wind stats for Wellington, something I did about 20 years ago and would be interested to update.
“Are there trends in the frequency of northerly winds? Or southerlies? Of wind strength? Or runs of windy days?
“While we’ve got this weather pattern, the winds are going to keep whipping through. But SAM has to eventually flip positive, and then we can look forward to some much better, calmer weather,” Professor Renwick says.