El Niño Pattern to Bring Intense Winds to New Zealand in Coming Weeks

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The upcoming weeks in New Zealand are expected to be filled with windswept days. Unlike previous years, it’s not just the onset of spring this year that’s to blame for the persistent westerlies sweeping the land.

The annual spring equinox concurrently aligns with an impending El Niño climate pattern, anticipated to be officially declared within weeks, which is already pushing its characteristic westerly flow onto New Zealand’s shores.

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According to Philip Duncan of WeatherWatch, the influence of these conditions could result in robust westerly quarter winds across the country, escalating towards the week’s end. Gale or severe gale conditions are predicted to affect the eastern South Island and the lower eastern North Island.

Duncan shared forecasts for the winds to intensify over the weekend as series of weather fronts move in, leading to particularly turbulent conditions at sea. “The pattern is expected to fluctuate for the next few weeks, culminating in a surge at the end of this week, followed by an even more powerful one around Sunday,” he explained.

Duncan also anticipates severe weather warnings from MetService, including the potential for power lines and trees down across parts of the country over the next week or two.

MetService has already issued severe weather warnings and watches for Thursday and Friday, anticipating a moderate risk of severe gale northwesterlies across Marlborough, Wellington, Wairarapa, Tararua, and Central Hawke’s Bay by Friday morning.

MetService meteorologist, Andrew James, issued a caution for those residing east of the main divide, south of Napier, stating they are included in the strong wind alert for tomorrow.

Furthermore, MetService expressed “moderate” confidence in another phase of severe northwest gales affecting northern Marlborough, Wellington, Wairarapa, Tararua, and Central Hawke’s Bay, carrying on from Sunday into Monday morning.

Despite the potential for these intense winds, Duncan considers such westerly surges not to be extreme events. They will quickly pass each day due to their swift-moving nature.

However, he asserts that the winds would symbolize a significant shift from the weather patterns New Zealanders are used to experiencing under the three-year spell of La Niña.

“I’ve observed a reduction in wind during spring, particularly in the upper regions of the country. The previous year we experienced greater low pressure, mitigating many windy westerly occurrences,” he reflects.

“This year we witness more of a conventional pattern, but I believe the El Niño influence could see it persisting longer than usual,” Duncan opines.

Every year the Spring Equinox, scheduled to happen this month on September 23, triggers the days to gradually extend, ushering in more warmth to the Southern Ocean. This warmth activates the usually westerly quarter winds, which often stretch onto New Zealand, bringing fronts and squally winds with them.

This season of “equinoctial gales” generally peaks in October and November. Additionally, the El Niño effect, characterized by high pressure north of New Zealand and low pressure to the south, acts like gears in a machine, promoting those westerly flows onto the country.

Regions particularly affected include the West Coast of the South Island, where frequent fronts and rain bands are shared. Areas like New Plymouth or Auckland can also anticipate cloudier and windier weather, with average temperatures over summer, as Duncan predicts.

However, as air within these winds get progressively drier in their west to east journey, prolonged periods of warmth and scant rain become more likely for regions like Canterbury, eastern Marlborough, Hawke’s Bay, and Gisborne.

The proclamation of El Niño may come later this month, with early indications suggesting this phenomenon may be one of the most impactful in decades.

Predictions suggest unsettled conditions across much of New Zealand in spring, leaning towards a drying trend on the East Coast. “But as we transition into summer, this dryness could become far more widespread across the North Island and upper south, in places like Nelson, Marlborough, and Canterbury,” Duncan warns.

He concludes, “The El Niño weather pattern has been a key focus throughout the year. We’ve effectively entered this weather cycling phase now, with it establishing more firmly over summer, and potentially persisting even until next winter.”