Saturday, April 13, 2024

El Niño may put wind up spring growth

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Australian Bureau of Meteorology says it is likely El Niño will be starting to influence Australasian weather patterns by July.
El Niño is known for its increase in westerly weather conditions and drying effects along the east coast.
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Despite a current weather pattern dominated by warm tropical light conditions in the North Island, El Niño could become a reality in New Zealand by later this year based on the latest climate modelling.

The Australian Bureau of Meteorology’s climate driver update reports that it is likely El Niño will be starting to influence Australasian weather patterns by July and be in full force come August.

Meantime between now and then major climate influencers are parked firmly in neutral as the latest La Niña event finally fades from the weather dial.

WeatherWatch director Philip Duncan said even the most conservative weather modelling systems are predicting an El Niño to come. The weather system is known for its increase in westerly weather conditions and drying effects along the east coast.

“There is also the potential there that this could be a prolonged one. When you look at the monthly sea surface temperature predictions, you can see where we have come from to where we are heading is significantly different.”

In December last year sea temperatures were as much as -0.8degC below average, while come October predictions are for an average temperature to be 2degC above its long-term average. 

All seven key climate change models have predicted the sea surface temperature anomalies that accompany El Niño to be well in play by August.

With El Niño dominating winds from the westerly quarter, it is possible NZ will experience its first windy spring for some years if the models prove correct, said Duncan.

“But every El Niño event is different, and until it forms it can be hard to know how bad it will be.”

Typically, El Niño events have a five- to seven-year return period. The last one recorded in 2015 had strong southwesterly  winds through to December, but with conditions changing to more northerly than usual, bringing rain that alleviated concerns over an El Niño drought arising.

The UK Guardian recently reported the likelihood that this year’s El Niño event could have the makings of a “super El Niño” before year’s end.

However, forecasters including Duncan have cautioned about reaching that conclusion too soon, while the Australian Bureau of Meteorology cautions about the accuracy of models forecasting the event in autumn, compared to other times of the year.

At present the Southern Annular Mode (SAM) is in a neutral position, along with the Indian Ocean Dipole (IOD). Should they move to a positive position in coming months this could suppress winter and spring rainfall over Australia and exacerbate  El Niño’s drying effects. 

Predictions of a possible El Niño kicking off from springtime have cattle market analysts nervously eyeing the impact, should Australian farmers have to start offloading stock for processing in drier weather.

The past three years have witnessed massive restocking across Australia, sustained by significant and continuing rainfall across much of the continent.

AgriHQ analyst Mel Croad said she is keeping a sharp eye on what may unfold across the Tasman.

“The possibility of a swing to a strong El Niño does increase the risk of larger livestock offloads in Australia, leading to even higher production and red meat exports than were forecast earlier in the year. 

“Whether or not El Niño reaches our shores, we need to keep an eye on Australian production as it could saturate markets, potentially lowering export returns later in the year.”

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