Odds of El Niño Weather Pattern Drop. . .

[Bob Of Burleson]

. . . but Still Expected to Form

By Andrea Thompson
ScientificAmerican.com

The climate impacts typically associated with an El Niño during the months of December, January, and February.
Credit: NOAA

The El Niño that seems to be trying to form in the tropical Pacific Ocean is looking a little less likely now, though the chances of it developing are still double the normal odds, forecasters said in the latest monthly update on the cyclical climate phenomenon, released Thursday.

That update lowered the odds of an El Niño occurring in fall and early winter to 65 percent, down from 80 percent last month. But “we’re still fairly confident that El Niño will come,” said Michelle L’Heureux a meteorologist with the National Oceanic and Atmospheric Administration’s Climate Prediction Center, who puts out the El Niño forecasts along with the International Research Institute for Climate and Society at Columbia University.

If and when the El Niño forms, it would influence weather and climate patterns in particular regions around the globe, for example, tamping down on hurricane activity in the Atlantic Ocean. Depending on its strength, it could also drive up global temperatures enough on top of the rise from human-induced warming to send 2015 into the record books.

While above-normal sea surface temperatures in the far eastern tropical Pacific — a hallmark of an El Niño event — have persisted, the warmth in other key surface regions and below the surface has ebbed. The shifts in atmospheric patterns that accompany an El Niño also have yet to materialize. These factors combined caused forecasters to lower the odds.

The updated probabilities mean that instead of a 4-in-5 chance that an El Niño would materialize, there is now a 2-in-3 chance it would, L’Heureux said.

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