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South can expect more strong gusts in coming months - NIWA

Nov 07, 2023

For anyone feeling particularly wind-blown recently, NIWA agrees with you.

The National Institute of Water and Atmospheric Research has released its October climate summary.

It reported large temperature swings and high winds across the motu.

Kaikohe in the Far North had its wettest October ever, with 321 percent of its normal monthly rainfall.

The highest gust was on the West Coast - 232km/h on 26 October.

NIWA's Chris Brandolino told Morning Report's Susie Ferguson former Tropical Cyclone Lola had "grazed" the upper part of the North Island, particularly Northland, Coromandel and the Bay of Plenty with "a good drop" of rain towards the very end of the month, which lifted the total monthly rainfall.

But temperatures were normal - which NIWA defined as plus or minus 0.5C of the average.

"When you look at the big picture it was pedestrian. [Nationally], the average temp was near average and we were at... plus 0.4C.

Beyond the average, there were wild variations across the country, he said.

"When you dive into the detail there were a lot of swings in terms of temperatures, and that was expected.

"Part of that is because it is spring, and spring is inherently a very changeable time of year. But it is also because of El Niño helping to drive those temperature swings and changes, and with that you often get the winds."

He said New Zealand - particularly the South Island and lower North - was likely to experience more of these intense and potentially damaging wind gusts over the next two months.

"With El Niño we tend to have higher-than-normal air pressure near and just northwest of the country and lower pressure in the south.

"Low pressure is a hole in the atmosphere and Mother Nature wants to fill that hole with air. If the 'hole' and 'mountain' are close together, that air is going to flow pretty darn quickly.

"With El Niño we have that mountain, or high pressure, near the upper North Island and the hole in the south, and often times they can be quite polar in terms of height and depth, and that enhances the wind."

Brandolino said "really hot temperatures" were on the way when the winds "swing around" from Australia.

"That will be a theme (in the) second half of November - some pretty warm, if not hot, days are coming up. Wind will become more west, norwest in time and that, combined with high wind, (means) there's a fire risk so these are things to be mindful of in the coming weeks and months."

Main image (Supplied/Waka Kotahi): High winds saw a truck overturn in North Canterbury on 26 October.

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