Officially, 2014 closed without an official El Nino. Probably. If you went back in a time machine to the spring, and told El Nino watchers that, they would be a little surprised, but they would also say something like, “Yeah, well, you know, we keep saying this is hard to predict.”
Despite the fact that for the most part there was not an official El Nino declared, a subset of El Nino conditions have been around, off and on, for many months. To officially declare an El Nino, a number of things have to add up, and while some of those things developed, the standard was not met. A few weeks ago, the Japan Meteorological Agency did retroactively say that there had been an El Nino, but others are not really going along with that. Some agencies are saying something similar but with less certainty.
Over the last few days, a number of new statements about El Nino have come out, and it looks like we are not too likely to see a large El Nino in 2015, but maybe a weak one. Or maybe none. (But some who watch this phenomenon have quietly suggested there could be a strong one.) Here are some of those statements.
Let’s start with the Australian Bureau of Meteorology ENSO Wrap-Up:
Tropical Pacific Ocean moves from El Niño to neutral
Issued on 20 January 2015
Since late 2014, most ENSO indicators have eased back from borderline El Niño levels. As the natural seasonal cycle of ENSO is now entering the decay phase, and models indicate a low chance of an immediate return to El Niño levels, neutral conditions are considered the most likely scenario through into autumn.
Central tropical Pacific Ocean surface temperatures have fallen by around half a degree from their peak of 1.1 °C above average in late November. Likewise, the Southern Oscillation Index has weakened to values more consistent with neutral conditions, while recent cloud patterns show little El Niño signature. As all models surveyed by the Bureau favour a continuation of these neutral conditions in the coming months, the immediate threat of El Niño onset appears passed for the 2014–15 cycle. Hence the ENSO Tracker has been reset to NEUTRAL. The Tracker will remain at NEUTRAL unless observations and model outlooks indicate a heightened risk of either La Niña or El Niño developing later this year.
From NOAA’s climate prediction center, from a statement issued on January 8th, 2015:
Although the surface and sub-surface temperature anomalies were consistent with El Niño, the overall atmospheric circulation continued to show only limited coupling with the anomalously warm water. The equatorial low-level winds were largely near average during the month, while upper-level easterly anomalies continued in the central and eastern tropical Pacific. The Southern Oscillation Index (SOI) remained slightly negative, but the Equatorial SOI remained near zero. Also, rainfall remained below-average near the Date Line and was above-average over Indonesia (Fig. 5). Overall, the combined atmospheric and oceanic state remains ENSO-neutral.
Similar to last month, most models predict the SST anomalies to remain at weak El Niño levels (3-month values of the Niño-3.4 index between 0.5oC and 0.9oC) during December-February 2014-15, and lasting into the Northern Hemisphere spring 2015 (Fig. 6). If El Niño were to emerge, the forecaster consensus favors a weak event that ends in early Northern Hemisphere spring. In summary, there is an approximately 50-60% chance of El Niño conditions during the next two months, with ENSO-neutral favored thereafter (click CPC/IRI consensus forecast for the chance of each outcome).
And now a shout out from NOAA, January 15th:
CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS CONTINUE TO SHOW MIXED SIGNALS
REGARDING THE ENSO STATE. SEA-SURFACE TEMPERATURES (SSTS) REMAINED NEAR TO
ABOVE AVERAGE FOR MOST OF THE EQUATORIAL PACIFIC, BUT THROUGH EARLY JANUARY,
THE ATMOSPHERIC RESPONSE IS NOT ROBUST. TAKEN AS A WHOLE, THE ENSO SYSTEM
REMAINS IN AN ENSO NEUTRAL STATE, WITH SOME ASPECTS OF A WARM EVENT. THE
CHANCES OF EL NINO DEVELOPING DURING THE NEXT 2 MONTHS ARE 50-60 PERCENT, WITH
A RETURN TO ENSO NEUTRAL CONDITIONS FAVORED THEREAFTER.
(I thought they were going to stop using all caps.)
From the International Research Institute for Climate and Society, Columbia University, IRI ENSO forecast:
During December 2014 through early January 2015 the SST exceeded thresholds for weak Niño conditions, although the anomaly level has weakened recently. Meanwhile, only some of the atmospheric variables indicate an El Niño pattern. Most of the ENSO prediction models indicate weak El Niño conditions during the January-March season in progress, continuing through most or all of northern spring 2015.
And now a few pullouts from the January 19th ENSO: Recent Evolution, Current Status and Predictions report from NOAA, a PDF file chock full of graphics and stuff put out every month.
This table (of ONI Index values) puts the current year in context of previous El Nino (red) and La Nina (blue) seasons. It is interesting to look at how long it has been since the last strong El Nino event. Most of 2012, and all of 2013 and 2014, qualify as being enough of anything by this measure to call it anything other than Neutral.
This graphic summarizes the chance of El Nino over coming months.
ENSO Alert System Status: El Niño Watch
ENSO-neutral conditions continue.
Positive equatorial sea surface temperature (SST) anomalies continue across
most of the Pacific Ocean.
There is an approximately 50-60% chance of El Niño conditions during the
next two months, with ENSO-neutral favored thereafter.
So, did we have an El Nino? Not officially, though some features that make up this phenomenon were present, off and on, over the last several months. Will we have an El Nino? Well, the indications we are having now are not too different than what we have been having, so who knows? My personal opinion is that the last year and the coming months together are going to have to be looked at carefully to determine if the way in which El Nino is measured need to be tweaked. But, that is nothing new, there is an ongoing conversation among climatologists about this.
The graphic at the head of the post is from “Fishing in pink waters: How scientists unraveled the El Niño mystery.”