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January ENSO update: The little engine that couldn't quite

A month ago, I wrote about the factors we look for when declaring the presence of “El Niño conditions.” Last month we were close: monthly average sea surface temperature anomalies in the Niño3.4 region were above +0.5° Celsius, and they looked to stay that way for at least another few seasons.

However, signs that the atmosphere was responding to the warmer-than-average ocean waters were inconclusive, and we decided to hold off on declaring the presence of El Niño conditions for the moment. Was that the right decision? Why is this particular forecast so difficult? This month, I’m going to take you behind the scenes, into the forecast process.

The CPC/IRI ENSO* team currently consists of eleven forecasters. The forecasters use a variety of statistical and dynamical computer model forecasts, information from different climate monitoring systems, and personal knowledge. As the team develops the forecast, we also seek input from several other climate experts at NOAA.

Each forecaster provides a prediction for the Oceanic Niño Index (ONI), the three-month average sea surface temperature anomaly in the Niño3.4 region. This is a 3-category probability forecast: one probability that the ONI will be below -0.5°C, one that it will be above +0.5°C, and one that it will be between the two.

These forecasts extend out to ten months into the future. For example, this month’s first forecast period is for the December-January-February average, and the last is for August-September-October 2015. These probabilities are what go into the consensus probabilistic forecast (fig. 1).

Forecasters must also answer the question of whether or not they think El Niño conditions are present (El Niño Advisory), likely to develop (El Niño Watch), or neither. (The same applies for La Niña, but for now I’m going to focus on the current situation.) This forecast has been tricky because, while the sea-surface temperature anomalies increased during October and November, the atmosphere was slow to respond.  

We make such a big deal about the atmospheric response for two main reasons. One, the changes in the tropical atmosphere connect to the higher latitudes through teleconnections, affecting the jet stream and leading to weather impacts over North America and elsewhere. The other reason is that the atmosphere feeds back onto the ocean, helping to develop and sustain the sea surface temperature anomalies.

As of the end of December, we were still seeing limited changes in the Walker Circulation. The Equatorial Southern Oscillation Index, or EQSOI, was still near zero (-0.1), and the SOI (Tahiti minus Darwin) increased slightly, but remained negative, at -0.6. Positive outgoing longwave radiation anomalies in the central Pacific decreased slightly too, but there was still suppressed rainfall near the Date Line.

What else is going on?

Through all these months during which the atmosphere has been saying “maybe” to El Niño, the ocean has been pretty consistently saying “yes.” However… during December, we saw a drop in the weekly Niño3.4 index, down from +1.0°C at the end of November to +0.5°C at the end of December. Plus, there is a reduction of sub-surface heat across the equatorial Pacific (fig. 2; see an animated progression here), meaning that there is a diminishing supply of heat that could recharge surface temperatures. The CFSv2 model, which has been hinting at this drop in SSTs for a couple of months now, also doesn’t think there will be a reversal in this current trend over the coming few months.

All of these considerations led the forecasters to conclude we are not in El Niño conditions this month. And, while there is a 50-60% chance of El Niño conditions emerging during the next two months, ENSO-neutral is favored beyond that.

So is this El Niño completely dead?

Not quite yet. With probabilities hovering around 50% that the ONI will stay above +0.5°C through January-February-March, we’re leaving the El Niño Watch up.

It’s not just U.S. forecasters that are watching this situation closely and trying to figure out what is going to happen. Australia’s Bureau of Meteorology has left their “El Niño Alert” raised, similar to our consensus. On the other hand, last month, the Japanese Meteorological Agency announced that El Niño was upon us, and has been since summer. They focus on the Niño-3 SST region (slightly eastward of Niño3.4).

The fact that different agencies are coming to different conclusions is further evidence of how borderline these conditions are.  If “El Limbo” were real, and not a fake category someone at the IRI thought of, we might have already declared it.     

*Climate Prediction Center/International Research Institute for Climate and Society (CPC/IRI) El Niño-Southern Oscillation (ENSO)

Comments

I enjoyed reading your commentary. Since I live in NW Montana, and we have seen an abundance of precipitation and cold so far this winter, I concur that the typical atmospheric response we often see here in the NW US during an El Nino has not occurred at all. In fact nearby Washington state has received record rainfall and my area just received over 2 feet of snow in a major snowstorm earlier this week and we are close to annual seasonal snowfall totals and it's only January. Normally we experience mild and drier than normal conditions for El Ninos. Clearly other factors are effecting our weather patterns this year. I note that other than a brief period of heavy rains in California in December, much of the SW quarter of the US has been both above average in temps and below average in precipitation--not boding well for their drought conditions, and certainly not conditions one could expect from an El Nino. Thus I like your term "El Limbo".

in the caption for the image it states "December 29, 2014 - January 3, 2014." but I'm pretty sure you meant January 3, 2015.

The Pliocene ocean was very mixed vs today, typhoons happen anywhere in the Pacific not a band in western and some in eastern, all over. This points to that, the north Pacific is very warm, the Philippines expecting their first typhoon of the year on the radar ... seems where it's going, it's mixing so the southern oscillations may not always hold anymore with an ocean warming so fast to depth, as shown by the Argos buoys. The oscillation relies on a difference in ocean temps & trade winds, we are losing that temperature contrast as the oceans warm the thesis, fits into El Limbo and the jetstream doing these radical loops due north, due south farther in total latitude instead of normal waves, that tied a warming atmosphere. Another way to check this would be longer term averages of sea-level in west vs east, if they equalize would be another indication.

Unfortunately as of now El Nino predictions are little more than soothsaying. There is neither the knowledge nor technology. NOAA should just get out of predicting climate and stick to five day forecasts.

Great article - thanks for putting this together and the plug for the ENSO Wrap!

Gracias por la información . Se que básicamente tratan de prever las condiciones para los USA , al menos en el comentario . Pero es importante para nosotros ( Ecuador ) , dado que la influencia o no del fenómeno del niño o niña en su caso es desbastador para una economía en crecimiento como la nuestra . En el caso particular estamos en le niño 1,2 y notamos que las condiciones de anomalías positivas se están reduciendo . En el caso de Ecuador , se mantienen están predicciones ? o podrían variar significativamente .

I usually enjoy reading this blog. I appreciate all of the time that is spent on analysis. Thanks to all involved! Over the years I'm reminded just how far we have come, whether that be on the meso-scale level or the global level of forecasting. I'm also reminded just how far we have to go. I believe there are so many atmospheric processes happening that have not been captured as of yet. I agree that we don't have that level of knowledge nor the technology at this time. I certainly do not agree with those that say we should just quit. I would encourage all that have the "passion" for this type of forecasting to keep going...continue your research and don't quit!!

It's very strange how some "El Nino-like" patterns have shown up, such as the deluge California got not too long ago. And where I live in western Washington State, it seems like winter started to pop it's ugly head up in December, January has been more like March around here. Recently I've noticed that the frogs out in the wetland behind our house have been croaking-they normally don't until March. Our early spring season flowering shrubs have been blooming; I've seen humming birds outside and also hornets have been flying around lately. And the geese never left when autumn showed up. But I'm not complaining. My only concern is that we might have an infestation of wasps and hornets this year (if) it turns out that many of them have not died off during the winter months. They might be a foot long by the time April comes around.

All these models are unable to predict weather accurately within a week's span, California being a great example. Just look at the GFS or any model for that matter. A lot of good big words like statistics and dynamics will do. Weather prediction is only slightly better today than during the times in which people beat drums and danced around trees to bring forth rain. Until we admit this, there will be no real progress.

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