Ag Weather Forum

The Australia Bureau of Meteorology's most recent Pacific Ocean discussion has details of the agency's call for the tropical Pacific to reach and maintain La Nina conditions during the first few months of 2018. However, this event does not appear to have nearly the same intensity as the La Nina event that began in August of 2010 and did not end until spring 2012. The agency's text comments are posted in the following paragraphs.

"The tropical Pacific is approaching La Nina thresholds. If the current progression continues, and thresholds are exceeded for a sustained period, 2017-18 will be considered a La Nina event. As a result, the Bureau's ENSO (El Nino Southern Oscillation) Outlook has been raised to La Nina ALERT meaning there is approximately a 70 percent chance -- or triple the normal likelihood -- of La Nina occurring. Climate models suggest that any event is likely to be weak and short-lived. This means it is expected to be very different to the strong 2010-12 La Nina.

"Oceanic indicators of ENSO show a clear progression towards La Nina. Tropical Pacific sea surface temperatures (SSTs) have cooled since late (Southern Hemisphere) winter, and waters beneath the surface remain cooler than average in the eastern Pacific. However, they are currently just shy of La Nina thresholds. Atmospheric indicators such as the Southern Oscillation Index (SOI) and trade winds have shown signs of shifting into a La Nina-like state. In order for La Nina to become established, atmospheric and oceanic indicators need to be reinforcing each other ("coupled"), which will strengthen and sustain these changes (i.e. a positive feedback).

"All international climate models suggest further cooling of the tropical Pacific is likely. All models reach La Nina thresholds in December 2017, and most maintain these values until at least February 2018. La Nina typically brings above average rainfall to eastern Australia during late spring and summer. However, sea surface temperature patterns in the Indian Ocean and closer to Australia are not typical of La Nina, reducing the likelihood of widespread summer rainfall. La Nina can also increase the chance of prolonged warm spells for southeast Australia."

What does all this mean for crop conditions and for a possible impact on crop prices? Right now, the most notable potential impact of La Nina would be a drier trend in Argentina's crop belt, and possible yield reduction there. From a market standpoint, such potential crop stress is certainly enough to keep a firm tone to prices, but a big rally seems like a stretch given the large supplies around right now. It's also seemingly a tall order to think about price rallies based on possible U.S. production shortfall in 2018 at this time, considering that La Nina is likely to fade by springtime of '18.

Bryce Anderson can be reached at bryce.anderson@dtn.com

Follow him on Twitter @BAndersonDTN

(CZ)

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