Now that we have a better understanding of El Nino, we will take a look at what we expect during the months ahead. The image below looks at how current sea surface temperatures compare to long term averages. In the circled region of the Pacific Ocean near the Equator, sea surface temperatures are near to slightly above average.
An interesting side note is the large region of warmer than average ocean water that is west of British Columbia. This relatively warm water contributed to the development of the persistent pattern in the upper atmosphere that we saw last winter which brought colder than seasonal temperatures to central and eastern Canada. This sea surface temperature pattern was also present during several of Canada’s coldest winters during the past century.
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As we look to the future, numerous models have been consistent in showing a steady progression to warmer than average sea surface temperatures in the Equatorial Pacific.
The image below is a model depiction of what this region may look like during the upcoming summer.
The black oval highlights the region to the west of South America where sea surface temperatures are forecast to rise to as much as 1 to 2 °C above average during June, July and August.
The trend towards warmer average temperatures is forecast to continue into autumn.
The map below shows a similar region of warmer than average sea surface temperatures during the months of September, October and November.
As we head into winter there is still a clear El Nino signature in the model depiction of sea surface temperatures, but several models show that sea surface temperatures will begin to cool slightly, with the warmest water found over the central Pacific rather than immediately to the west of South America.
FORECASTING VIA THE MODELS
Another way to look at the forecast for El Nino is the image below which shows sea surface temperature forecasts (relative to average) for the equatorial regions of the central Pacific from over 20 models. Each line represents a forecast from a different model. On the far left of the screen we start with sea surface temperatures from this winter. As we move to the right on the diagram we progress further into the future with the forecast. Without getting caught up in all the details, the key point is that all of the models show that sea surface temperatures will warm to above average as we head into the summer and fall (which indicates an El Nino), but there is considerable disagreement between the different models regarding how much warming will occur.
NEXT PAGE: HOW STRONG WILL THE UPCOMING EL NINO BE?