Brett Anderson

El Nino Southern Oscillation Update

4/19/2012, 9:06:45 AM

La Nina was barely hanging on as of early April, and the transition to neutral ENSO conditions in the equatorial Pacific region should be complete by the end of this month.

La Nina is the abnormal cooling of the sea surface waters in the equatorial Pacific. El Nino is the opposite (warming). Sea surface temperature anomalies as of Jan. 16, 2012


Latest sea surface anomalies as of April 16, 2012. Note the trend toward warmer anomalies, especially in the eastern, equatorial Pacific.


Even though the ENSO will likely go neutral for the rest of this spring, there is always a lag effect with these transitions, so that the larger-scale atmospheric circulation anomalies will likely continue to have some La Nina characteristics over the next month or two.

A clear majority of forecast models project ENSO-neutral conditions into the summer of 2012. There is much more uncertainty beyond that, but some models are leaning toward a weak to moderate El Nino later in the year.

Image courtesy of the International Research Institute for Climate and Society.


For fun, let's assume that we will transition into a weak El Nino for the winter of 2012-2013 (still high uncertainty) How could this impact the weather pattern across Canada based on an average of weak El Nino winters? Keep in mind, these type of analog maps were of no use for this past winter during the La Nina. Courtesy Environment Canada.



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