Bye bye La Ni単a, we hardly knew you. (And btw, is that your baby brother, El Ni単o, lurking there in the shadows?)

By Tom Yulsman | February 11, 2017 4:46 pm
With La Ni単a's demise, just a small patch of blue indicative of cooler than average sea surface temperatures remains in the central equatorial Pacific Ocean. Meanwhile, very warm water has formed off the coast of Peru. (Source: NOAA View)

With La Ni単a’s demise, just a small patch of blue indicative of cooler than average sea surface temperatures remains in the central equatorial Pacific Ocean. Meanwhile, very warm water has formed off the coast of Peru. (Source: NOAA View)

The La Ni単a of 2016is nowofficially gone. Following on from a monster El Ni単o, it turned outto beone of the shortest and weakest on record.

La Ni単a, which can influence weather across many parts of the world, is characterized by abnormally cool surface waters in the central equatorial Pacific Ocean. Those have now mostly dissipated, leaving behind temperatures that are close to average for February. Forecasters expectthese neutral conditions to continue for the next few months.

La Ni単a

This animation showing week-by-week sea surface temperature anomalies begins on Nov. 16, 2016. At the time, a spear of cooler than average surface water extended along the equator across much of thePacific. By the week of Feb. 1, that cool pool had mostly dissipated, heralding the end of La Ni単a. (Source: NOAA Climate Prediction) Center

Despite its relative puniness, 2016’s La Ni単a did produce some typical impacts in North America. For example: a warmer than normal winter so far in the South, and unusual cold in Alaska, western Canada, and the northern Plains.

But most Californians can’t really thank La Ni単a for the incredible bounty of drought-bustingrain and snow they’ve received this winter. While thePacific Northwest andnorthernmost California typically are wetter than normal during La Ni単a episodes,central California is not.

La Ni単a

ThisENSO forecast is based on human judgment and the output of computer models. The red bars show the chances of El Ni単o developing. By the September-October-November period, the probability rises to 48 percent. (Source: CPC/IRI)

Beyond April, what might be coming?During this time of the year, that is exceedingly difficult for forecasters to predict. That’s because of something known as thespring predictability barrier.

In a nutshell: Models have a hard time looking past the spring to predict which way the El Ni単o-Southern Oscillation, consisting of the El Ni単o and La Ni単aphenomena, might swing. Here’s howEmily Beckerexplains itat NOAA’s ENSO blog:

. . .spring is often a transitional time, when ENSO events wind down and neutral conditions prevail. It can be tougher to predict the change into a new phase than to predict the growth, continuation, or demise of an event.

With that big caveat in mind, let’s talk about El Ni単o.

“Some of the computer models are calling for a return of El Ni単o conditions by the second half of 2017,” Becker writes. “These models have a pretty good track record, so were not completely ignoring them.” But the spring predictability barrier also argues for caution.

“The bottom line is that were giving the odds of developing El Ni単o conditions a slight edge for fall 2017, with the probability around 50%,” Becker says. That compares with abaseline 33 percent chance that an El Ni単o, La Ni単a, or neutral phase, will developin the fall of any random year.

In other words, right now the forecast is leaning El Ni単o-ish. We certainly do not yet have tofasten our seat belts for a wild ride like what we had during thelast one. But it will sure be interesting to see how things play out this year.

CATEGORIZED UNDER: Climate, ENSO, select, Top Posts


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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