Another El Niño Could Be On Its Way

There’s a 40 percent chance of the pattern later this year

El Nino 2017
Sea surface temperatures are abnormally warm in the Pacific Ocean. Will that drive an El Niño event later this year? NASA/JASON-3

El Niño used to only come along once every few years—the weather equivalent of a big bonus. But if current predictions are right, this year may defy the pattern. With the most recent El Niño winding down last summer, scientists are now predicting that the weather pattern could rear its rainy head again within the next several months, reports the BBC’s Matt McGrath.

In a new update, the weather experts of the World Meteorological Organization say that there is a 35 to 40 percent chance of an El Niño developing later this year. La Niña, the phenomenon’s inverse, seems unlikely to happen despite previous predictions that the cool weather pattern would strike this winter.

El Niño occurs when water in the Pacific Ocean warms, usually around the end of the year. It’s the warm half of a pattern known as ENSO (El Niño-Southern Oscillation) that describes how ocean surface temperatures in the Pacific interact with the atmosphere. When sea surface gets warmer, areas in the north and west United States get warmer, too. The weather changes as well, causing lots of rain in some places and driving drought in others.

So what happened to the predicted La Niña? As McGrath reports, it never showed up. Instead, scientists were faced with a neutral pattern they jokingly dubbed “La Nada” (the nothing)—essentially the middle ground between Niño and Niña.

It’s still likely that that neutral pattern will persist throughout the first half of the year, says the WMO. And it can be hard to see far enough to really know what’s going to happen in terms of ocean temperatures. Even if there is an El Niño, it’s impossible to predict how the large-scale pattern will be affected by small-scale, local climate conditions.

One thing is clear, however: the possibility of another El Niño so close to the one that ended in mid 2016 is a bit weird. As the United Kingdom’s national weather service notes, there are precedents for close El Niños, but “the level of warming in current predictions of the tropical Pacific is unusual for this time of year.” Then again, oceans are warming up in general, and those warm temperatures could change the ENSO pattern at some point. Scientists are still trying to figure out if that is in fact taking place.

Will this year’s pattern be a Niño or a Nada? It’s too early to tell for sure. But you might want to spend a bit of that next bonus on an umbrella, just in case.

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