Latest forecast: El Ni単o likely will develop later this year, promising significant impacts around the world

By Tom Yulsman | July 13, 2018 12:12 pm
Sea surface temperatures in large parts of the tropical Pacific Ocean are edging above normal. (Image source: Climate Reanalyzer)

Sea surface temperatures in large parts of the tropical Pacific Ocean are edging above normal. (Image source: Climate Reanalyzer)

El Ni単o’s coming.

That’s the increasingly confident forecast from the U.S. Climate Prediction Center. In its latest monthly report, the CPC continued an El Ni単o watch and boosted the odds of itdeveloping during the Northern Hemisphere winter of 2018-2019 to 70 percent. Last month, the center pegged El Ni単o’s chances at 65 percent.

El Ni単o weather impacts. (Source: NOAA)

El Ni単o weather impacts. (Source: NOAA)

This is important because El Ni単o has profound impacts on weather around the world.

Here in the United States, El Ni単o tends to result in an amplified winter storm track across the southern tier of the country. This usually brings wetter conditions including to southern California and portions of Nevada and Arizona, areas now afflicted by severe drought. Click on this map to see typical winter weather impacts during El Ni単o episodes.

The atmosphere is an incredibly complex and chaotic system.So we shouldn’t expect to see all of the impacts shown in themap which is about probabilities, not certainties. But more than half of all El Ni単o events since 1950 have brought wetter than average conditions to California.

What has happened to cause forecasters to feel more confident that anEl Ni単o will develop?

The climatic phenomenon is characterized by a number of changes in the tropical Pacific region, most especially warmer than average sea surface temperatures in a swath along the equatorknown as the Ni単o 3.4 region. And, in fact, temperatures along the equator have been edging up, as the map at the top of this post shows.

In that Ni単o 3.4 region, sea surface temperatures must rise0.5属C above the long-term average to cross the El Ni単o threshold and right now, we’ve still got a ways to go. But a huge blob of warm waterbeneath the surface of the Pacific has been rising from the depths, helping to raise temperatures at the surface:

Departure from average of the surface and subsurface tropical Pacific sea temperature averaged over 5-day periods starting in early June 2018. The vertical axis is depth below the surface in meters, and the horizontal axis is longitude, from the western to eastern tropical Pacific. The cross-section is along the equator. (Source: Climate.gov figure from CPC data.)

Departure from average of the surface and subsurface tropical Pacific sea temperature averaged over 5-day periods starting in early June 2018. The vertical axis is depth below the surface in meters, and the horizontal axis is longitude, from the western to eastern tropical Pacific. The cross-section is along the equator. (Source: Climate.gov figure from CPC data.)

“Its likely the surface will continue to warm over the next few months, helping to support the forecast for El Ni単os development,” writes research scientist Emily Becker in a post at the ENSO Blog. She also notes that“most climate climate models predict that the Ni単o3.4 region temperatures will reach the El Ni単o threshold . . . by the fall.”

If the models and forecasters are right and El Ni単o does develop, we should expect one other impact thatI’m sure would be an unpleasant prospect for the millions ofAmericans who have been sweltering in recent weeks: a boost in global temperatures. This would come on top of the rise in temperatures from human-caused global warming.

Thanks in part to a boost from aparticularly strong El Ni単o in 2016, that year obliterated the record for warmest year. Thank goodnessthere are no indications now that we’re heading for an El Ni単o that strong. Forecasters are actually expecting it to be in the weak to moderate range. Let’s hope that will mean only a modest boost to global temperatures but a nice influx ofdesperately needed moistureto drought afflicted areas.

CATEGORIZED UNDER: Climate, Drought, ENSO, select, Top Posts, Weather
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ImaGeo

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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