Meanwhile, in the Pacific…

By Tom Yulsman | September 13, 2018 3:23 pm
Pacific

Colors on this map show where and by how much monthly sea surface temperature differed from the 1981 to 2010 average during August 2018. (Source: NOAA)

As Hurricane Florence began lashing the Carolinas this morning, another potentially disruptive atmospheric and oceanic phenomenon continues to brew thousands of miles away in the Pacific: El Ni単o.

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

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

It’s not here yet, according to the National Oceanic and Atmospheric Administration’s latest monthly analysis, published today. But forecasters continue to favor its arrival this fall, pegging the odds at 50 to 55 percent. By winter, the chances rise to 65 to 70 percent.

We should care because what happens in the Pacific doesn’t stay in the Pacific. Here in the United States, El Ni単o tends to amplifywinter storm tracks across the southern tier of the country, bringing wetter conditions. Meanwhile, farther north, it tends to bewarmer and drier than average. (Click on the thumbnail to see typical winter weather impacts during El Ni単o episodes.)

El Ni単o is characterized bywarming of the ocean surfacein the central and eastern tropical Pacific Ocean.Asthe map at the top of this post shows, most of the ocean surface along the equator has indeed beenslightly warmer than the long-term average.

That warmth hasn’t yet crossed the threshold needed for an official El Ni単o declaration.So we’re still in neutral. But models and physical signs in the Pacific suggest El Ni単o is starting to get rolling.

Along with the warming of surface waters, El Ni単o brings aweakening, and sometimes a reversal, of the surface trade windsthatnormally blow from east to west along the equator in the Pacific. While nothing major has happened yet,those winds have weakened a bit on several occasions in recent months.

Nothing “exceptionally powerful” has happened with the winds yet, writesNOAA research scientist Emily Beckerat the ENSO Blog. But several modest bouts of wind weakening have been “enough to provide some confidence to the forecast that El Ni単o conditions are on the way.”

One of those bouts helped a large blob of warm water extending down to about1,000 feet migrate toward the east. All that warmth should help increase temperatures at the sea surface in the region key to an official El Ni単o declaration.

For the next several weeks at least, tropical cyclones are likely to be in the headlines. But stay tuned for what seems to be coming after the leaves fall…

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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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