One More Time! The Troubles with Predicting El Niño

In North America, it brought cozy warm winters, rainy days in California, few hurricanes and excellent crop conditions. Summers were cooler, food cheaper and good times were had by most Americans.

It used to be easy to predict El Niños that would bring California lots of rain. Source NOAA

Sigh! Those were the days.

Now scientists say that we are experiencing El Niño conditions and will probably have an El Niño this summer. Just one problem—the last few times they predicted an El Niño, they were wrong!

Here’s the problem: The Pacific is complicated. The El Niño/La Niña is only one of many cycles in the ocean that covers 30% of the globe. An even bigger cycle is messing with the scientists’ models and predictions.

Over the past few years, the trend towards Negative PDOs has made El Niños less common.

Welcome to the PDO! It means Pacific Decadal Oscillation, a 50+ year cycle that shifts warm and cold water around the Pacific. You can remember it as Pretty Dry Oklahoma. In the positive phase, the Tropical and Eastern Pacific tend to be warm. In the cool negative phase, we see the reverse. Each phase, warm or cool, lasts for decades (which is why it was called decadal.)

It and the El Niño interact. When the trend was positive, it was easy to predict warm El Niños. They tend to be strong and their impact on American rainfall is good. When the trend is negative and cold, it is hard to develop and they tend to be weak and don’t last very long.

When the trend was warm and positive, we had an El Niño every four years. Since 2006 the trend has tended to be negative and we have only had one event. Bad news for El Niños, California rainfall and scientists trying to predict either.  Every other time, when an El Niño started to develop, like in 2012 and last year, it failed.

Scientist say there is a good chance of an El Niño most of the rest of this year. Source: NOAA

So if scientists are predicting an El Niño, just remember the Pacific is a really crazy ocean. It is getting a lot less predictable.