Visualization of Pacific ocean temperatures shows El Ni単o brewing, heralding possible winter weather impacts

By Tom Yulsman | October 12, 2018 5:58 pm
El Ni単o visualizations shows El Ni単o brewing

This animation shows how sea surface temperatures have departed from the long-term average, from August through early October 2018. (Animation by climate.gov; data from NOAAs Environmental Visualization Lab.)

It’s still not here yet, but El Ni単o sure looks like it’s coming.

In its latest forecast, NOAA’s Climate Prediction Center saysthere is a70 to 75 percent chance thatEl Ni単owill form “in the next couple of months and continue through the Northern Hemisphere winter 2018-19.” If the forecast turns out to be correct, the El Ni単o could influence weather around the world.

El Ni単o is typically associated with an extended Pacific jet stream and amplified storm track, boosting the odds of wetter than average conditions across the southern tier of U.S. states. Should things play out this way(and they may not!), it could bring at least somerelief for parts of the drought-stricken Southwest.

One of the factors behind the Climate Prediction Center’sincreasing confidence that El Ni単o is coming can be seen in the visualizationabove. It shows how sea surface temperatures have evolved each week from August through early October specifically, how thosetemperatures have differed from the 1985-2012 average.

Pay particular attention to the equator off the coast of South America and extending west to the middle of the Pacific. See the blue tending to give way to red? This is indicative of warming surface waters. As Emily Becker, a NOAA research scientist, puts it in a post at the ENSO Blog:

Over the past several weeks, surface temperature anomalies (difference from the long-term average) have gradually increased across much of the tropical Pacific. All four of the Ni単o-monitoring-region temperatures are now above average.

So we’re getting there. But we’re not there yet.

Visualization of deep ocean temperatures shows conditions favorable to El Ni単o

This visualization of a cross section of the equatorial Pacific shows how the temperature of subsurface waters has differed from the long-term average between August and early October. Depth is indicated on the vertical axis, and longitude on the horizontal one. (Source: NOAA Climate Prediction Center)

Other signs point toward El Ni単o’s arrival as well, according to Becker. The trade winds that normally blow from east to west (from South America toward Indonesia)have weakened significantly in the central and easternparts of the equatorial Pacific. The slackening in the winds, in turn, has helped a blob of warm subsurface water see the animation above to migrate eastward and rise toward the surface. This ishelping to reinforce the warming of equatorial Pacific surface waters.

Visualization of sea surface temperatures

Sea surface temperature anomalies during 2015El Ni単o. (Source: NOAA)

Right now, the models are forecasting a relatively weak El Ni単o. (Click on the thumbnail at right to see what sea surface temperatures look like during a strong El Ni単o.)

But thatdoesn’t excludesignificant weather impacts, including extra moisture in drought-plagued areas.

As Becker puts it, “The strength of El Ni単o doesnt necessarily indicate the strength of its impacts on global weather. Buta stronger El Ni単o can increase the likelihood that impacts of some kind will happen.”

If current forecasts are right, we won’t have to wait too much longer to find out just what El Ni単o will bring this time around.

CATEGORIZED UNDER: Climate, Drought, ENSO, select, Top Posts, Weather
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  • http://strawn-04.blogspot.com/ Kenny Strawn

    A variable that should definitely be noted is a trend in the Brazil Current: A wind-driven boost by a rapidly intensifying South Atlantic subtropical high in late September has resulted in Agulhas salinity leakage being diverted due-west across the South Atlantic directly to the Brazil Current, bypassing the Gulf Stream altogether. The result? A salinity-starved Gulf Stream, which should weaken as a result of such.

    As shown in FRESH-C model output, this thermohaline circulation change tends to favor stronger W African upwelling (which has temporarily weakened as a result of Leslie spinning aimlessly but is now forecast to re-strengthen now that Leslie is making landfall in Portugal) and as a result favors the kind of ++NAO that were currently seeing along with stronger-than-normal Caribbean winter high pressure, which in turn places southward stress on the position of the Pacific ITCZ. Warm South Atlantic, meanwhile, also places stress on the SW Indian Ocean conducive to +IOD on top of that. This combination is definitely capable of boosting El Ni単o impacts, especially as winter approaches the last time we had a south-based Atlantic Inter-Hemispheric Dipole, which this salinity diversion favors, was in 1994.

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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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