Say, WHAT? After one of the strongest El Ni単os on record, another one may be brewing

By Tom Yulsman | April 17, 2017 5:03 pm

The equatorial Pacific Ocean is suffering from a split personality disorder: El Ni単o-ish in the east; La Ni単a-ish to the west. El Ni単o is likely to win out.

Split personality: warm water to the east, cool to the west

Sea surface temperatures in March 2017 compared to the 1981-2010 average. Cooler-than-average SSTs are present in the west-central equatorial Pacific and El Ni単o-ish warmer-than-average temperatures prevail to the east, extending out from the South American coast. (Source: NOAA map, based on GEO-Polar data.)

Climate forecast models are predicting a full-fledged El Ni単o by summer or fall. If it should happen, it would bring all manner of disruption to global weather patterns.

And it would also be an extraordinary event.

If you’ll recall, in 2015-16, the planet experienced a monster El Ni単o event, one of the three strongest on record. It then transitioned into itsopposite, La Ni単a, which has since fizzled into neutral conditions. Now, if El Ni単o rises from the dead, it would markjust the secondtime since 1950 that this sequence El Ni単o/La Ni単a/El Ni単o will have occurredin three consecutive years. The first time wasbetween1963 and 1966.

SEE ALSO: Although its impacts on the weather still reverberate, El Ni単o now has officially gone bye bye

But whilethe computer forecast models are gung-ho on El Ni単o roaring back to lifeby fall (or maybe mewing back to life it’s not clear how strong it could be), human forecasters, observingwhat the Pacific has looked like in advance ofpreviousEl Ni単o’s,are being more cautious.

According to a forecast issued last week by the National Oceanic and Atmospheric Administration,there is a 50 percent chance of El Ni単o developing by September. This is slightly more probable than the current neutral conditions continuing. Forecasters peg those odds at 40 percent. (And La Ni単a? Forget about it. Just a 10 percent chance.)

The trouble is that the tropical Pacific, where El Ni単o and La Ni単a brew up, is lookinglikeit’s suffering from dissociative identity disorder, known colloquially as a split personality. On the eastern side of the Pacific, a spear of very El Ni単o-looking warm surface water is jutting out from the coast of South America along the equator.

Ithas been called a “coastal El Ni単o,” and that’s where the split personality comes in.

It’s a coastal El Ni単o because the warming is fairlyintense along the Peruvian coast, but it doesn’t extend far across the Pacific along the equator as occurs in anormal El Ni単o. In fact, have a look at the map of sea surface temperatures above and you’ll see that cooler than average water is present in the central and west-central Pacific. That’s actually ratherLa Ni単a-ish!

The surface wind patterns in the west-central Pacific also look more like La Ni単a. And there’s more: a blob of cooler than average water has developed beneath the surface. You can see that blob developing in this animation depicting a cross section of the Pacific along the equator:

Split personality: cold blob in the tropical pacific

This animation depicts a cross section of the Pacific Ocean along the equator. The colors show how water temperatures at depth have varied from average starting in early March and continuing into mid-April. (Source: NOAA Climate Prediction Center)

If an El Ni単o were brewing, you’d expect to see the opposite.

Which ‘personality’ is finally going to win? If you’ve read that there is a “strong chance” for El Ni単o developing (as this story claimed), don’t believe it. A 50 percent chance is anything but “strong.” On the other hand, the El Ni単o personality is more likely to emerge than any other. Once we get into summer, forecasters will be able to get a somewhat more reliable fix on what could be coming. So stay tuned.

Lastly, if you are interested in the nitty gritty details of ENSO the umbrella term for the El Ni単o/La Ni単a phenomena I highly recommendthe ENSO blog over at It’s informative and written in a very engaging style.

CATEGORIZED UNDER: Climate, ENSO, Ocean, select, Top Posts, Weather
  • Pedro154

    Im went from the future (Nov/2017) to tell you these 10% chance of La Ni単a came true.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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