A monthly summary of the status of El Niño, La Niña, and the Southern Oscillation, or ENSO, based on the NINO3.4 index (120-170W, 5S-5N)
During July through early-August the observed ENSO conditions were neutral. Most of the ENSO prediction models indicate warming to El Niño levels coming around early northern fall, peaking at weak strength during winter 2014-15 and lasting into the first few months of 2015.
Figures 1 ((the official CPC ENSO probability forecast) and 3 (the objective model-based IRI ENSO
probability forecast) are often quite similar. However, occasionally they may differ noticeably.
There can be several possible reasons for differences. One is the human forecasters, using their
experience and judgment, may disagree to some degree with the models, which may have known biases.
Another reason is the models are not run at the same time that the forecasters make their assessment,
so that the starting ENSO conditions may be slightly different between the two times. The charts
on this Quick Look page are updated at two different times of the month, typically about a week apart,
with the IRI forecast run later. Also note that the CPC forecast starts on the previous season
while the IRI forecast starts on the current season.
Click on the for more information on each figure.
El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued by the Climate Prediction Center/NCEP/NWS
Synopsis: The chance of El Niño has decreased to about 65% during the Northern Hemisphere fall and early winter.
During July 2014, above-average sea surface temperatures (SST) continued in the far eastern equatorial Pacific, but near average SSTs prevailed in the central and east-central equatorial Pacific (Figure 1). Most of the Niño indices decreased toward the end of the month with values of +0.3°C in Niño-4, -0.1°C in Niño-3.4, +0.2°C in Niño-3, and +0.6°C in Niño-1+2 (Figure 2). Subsurface heat content anomalies (averaged between 180º-100ºW) continued to decrease and are slightly below average (Figure 3). The above-average subsurface temperatures that were observed near the surface during June (down to 100m depth) are now limited to a thin layer in the top 50m, underlain by mainly below-average temperatures (Figure 4). The low-level winds over the tropical Pacific remained near average during July, but westerly wind anomalies appeared in the central and eastern part of the basin toward the end of the month. Upper-level winds remained generally near average and convection was enhanced mainly just north of the equator in the western Pacific (Figure 5). The lack of a coherent atmospheric El Niño pattern, and a return to near-average SSTs in the central Pacific, indicate ENSO-neutral.
Over the last month, model forecasts have slightly delayed the El Niño onset, with most models now indicating the onset during July-September, with the event continuing into early 2015 (Figure 6). A strong El Niño is not favored in any of the ensemble averages, and slightly more models call for a weak event rather than a moderate event. At this time, the consensus of forecasters expects El Niño to emerge during August-October and to peak at weak strength during the late fall and early winter (3-month values of the Niño-3.4 index between 0.5°C and 0.9°C). The chance of El Niño has decreased to about 65% during the Northern Hemisphere fall and early winter (click CPC/IRI consensus forecast for the chance of each outcome).
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum section of CPC’s Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog.
The next ENSO Diagnostics Discussion is scheduled for 4 September 2014. To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: ncep.list.enso-update@noaa.gov.
| Season | La Niña | Neutral | El Niño |
|---|---|---|---|
| JAS 2014 | 1% | 53% | 46% |
| ASO 2014 | 1% | 44% | 55% |
| SON 2014 | 1% | 39% | 60% |
| OND 2014 | 1% | 34% | 65% |
| NDJ 2014 | 2% | 32% | 66% |
| DJF 2014 | 2% | 34% | 64% |
| JFM 2015 | 3% | 38% | 59% |
| FMA 2015 | 3% | 44% | 53% |
| MAM 2015 | 4% | 48% | 48% |
The SST anomaly in the Nino3.4 region in recent weeks retreated from near the borderline of neutral and El Niño where it had been in May and June. For July the Nino3.4 SST anomaly was 0.18 C, indicative of neutral conditions, and for May-July it was 0.37 C. The IRI’s definition of El Niño, like NOAA/Climate Prediction Center’s, requires that the SST anomaly in the Nino3.4 region (5S-5N; 170W-120W) exceed 0.5 C. Similarly, for La Niña, the anomaly must be -0.5 C or less. The climatological probabilities for La Niña, neutral, and El Niño conditions vary seasonally, and are shown in a table at the bottom of this page for each 3-month season. The most recent weekly SST anomaly in the Nino3.4 region was 0.0 C, not far from the 0.18 C observed in July. Although the SST had been near the borderline of weak El Niño conditions in May and June, the atmospheric participation in an El Niño-like pattern had been weak or absent. During August so far, neither ocean nor atmosphere has reflected El Niño conditions in a clear or obvious way, but the atmosphere is recently showing a renewed tendency toward El Niño development.
What is the outlook for the ENSO status going forward? The most recent official diagnosis and outlook was issued earlier this month in the NOAA/Climate Prediction Center ENSO Diagnostic Discussion, produced jointly by CPC and IRI; it called for a likelihood for a transition from neutral ENSO conditions to El Niño conditions during the early fall 2014 about to begin, with probabilities of El Niño rising to 66% for Nov-Jan 2014-15. The latest set of model ENSO predictions, from mid-August, now available in the IRI/CPC ENSO prediction plume, is discussed below. Currently, Nino3.4 SST anomalies are neutral after having been close to the borderline of El during May and June. Positive anomalies are still found in the far eastern part of the Pacific basin. Subsurface temperature anomalies across the eastern equatorial Pacific have been at average levels during the last month, after being much above average during spring but subsequently decreasing due to discharging into the atmosphere with strong positive SST anomalies in the far eastern part of the basin. In the atmosphere, the basin-wide sea level pressure pattern (e.g. the SOI) has recently shown a tendencies in the direction of El Niño, with a negative SOI, weak anomalous low-level westerlies and anomalous upper level easterlies. Anomalous convection (as measured by OLR) has been near average near and east of the dateline. These atmospheric conditions, while weak, are suggestive of El Niño despite the SST being neutral in recent weeks. Together, the oceanic and atmospheric features continue to reflect neutral ENSO conditions that lean toward weak El Niño.
As of mid-August, none of the dynamical or statistical models models predicts La Niña SST conditions for the initial Aug-Oct 2014 season, 44% predicts El Niño conditions, and 56% indicates neutral ENSO. At lead times of 3 or more months into the future, statistical and dynamical models that incorporate information about the ocean’s observed subsurface thermal structure generally exhibit higher predictive skill than those that do not. For the Nov-Jan 2014-15 season, among models that do use subsurface temperature information, 40% predicts ENSO-neutral SSTs, 60% predicts El Niño conditions and none predicts La Niña conditions. For all model types, the probability for neutral ENSO conditions is 40% or below between Oct-Dec 2014 and Apr-Jun 2015. Probabilities for El Niño rise to more than 60% or more between these same two seasons, peaking at 71% for Dec-Feb 2014-15. No model predicts La Niña conditions for any of the 3-month periods between Aug-Oct 2014 and Apr-Jun 2015.
Note – Only models that produce a new ENSO prediction every month are included in the above statement.
Caution is advised in interpreting the distribution of model predictions as the actual probabilities. At longer leads, the skill of the models degrades, and skill uncertainty must be convolved with the uncertainties from initial conditions and differing model physics, leading to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution from that taken verbatim from the raw model predictions.
An alternative way to assess the probabilities of the three possible ENSO conditions is more quantitatively precise and less vulnerable to sampling errors than the categorical tallying method used above. This alternative method uses the mean of the predictions of all models on the plume, equally weighted, and constructs a standard error function centered on that mean. The standard error is Gaussian in shape, and has its width determined by an estimate of overall expected model skill for the season of the year and the lead time. Higher skill results in a relatively narrower error distribution, while low skill results in an error distribution with width approaching that of the historical observed distribution. This method shows probabilities for La Niña near 0% from Aug-Oct 2014 through Jan-Mar 2015, rising to 4% by Apr-Jun. Model probabilities for neutral ENSO conditions are 58% for the initial period of Aug-Oct 2014, 44% for the next running period of Sep-Nov, reach a low of 27% for Dec-Feb 2014-15 and rise to 45% by Apr-Jun 2015. Probabilities for El Niño are 42% for Aug-Oct 2014, rise to 73% for Dec-Feb 2014-15, and decline dlowly to 51% for Apr-Jun 2015. The models collectively favor El Niño over other ENSO conditions by a clear margin between Oct-Dec 2014 and Feb-Apr 2015. A plot of the probabilities generated from this most recent IRI/CPC ENSO prediction plume using the multi-model mean and the Gaussian standard error method summarizes the model consensus out to about 10 months into the future. The same cautions mentioned above for the distributional count of model predictions apply to this Gaussian standard error method of inferring probabilities, due to differing model biases and skills. In particular, this approach considers only the mean of the predictions, and not the total range across the models, nor the ensemble range within individual models.
The probabilities derived from the models on the IRI/CPC plume describe, on average, a likely development of El Niño development during Sep-Nov 2014, becoming even more likely by Oct-Dec. The consensus of model predictions calls for a weak El Niño event, a moderate event being second most likely, no El Nino being next most likely, and a strong event being least likely. A caution regarding this latest set of model-based ENSO plume predictions, is that factors such as known specific model biases and recent changes that the models may have missed will be taken into account in the next official outlook to be generated and issued in early October by CPC and IRI, which will include some human judgement in combination with the model guidance.
| Season | La Niña | Neutral | El Niño |
|---|---|---|---|
| DJF | 37% | 28% | 35% |
| JFM | 34% | 37% | 29% |
| FMA | 30% | 48% | 22% |
| MAM | 26% | 54% | 20% |
| AMJ | 24% | 54% | 22% |
| MJJ | 25% | 51% | 24% |
| JJA | 25% | 50% | 25% |
| JAS | 27% | 46% | 27% |
| ASO | 29% | 40% | 31% |
| SON | 32% | 34% | 34% |
| OND | 34% | 31% | 35% |
| NDJ | 37% | 27% | 36% |
| Season | La Niña | Neutral | El Niño |
|---|---|---|---|
| ASO 2014 | ~0% | 58% | 42% |
| SON 2014 | ~0% | 44% | 56% |
| OND 2014 | ~0% | 36% | 64% |
| NDJ 2014 | ~0% | 30% | 70% |
| DJF 2014 | ~0% | 27% | 73% |
| JFM 2015 | ~0% | 32% | 68% |
| FMA 2015 | 1% | 37% | 62% |
| MAM 2015 | 2% | 43% | 55% |
| AMJ 2015 | 4% | 45% | 51% |
The following graph and table show forecasts made by dynamical and statistical models for SST in the Nino 3.4 region for nine overlapping 3-month periods. Note that the expected skills of the models, based on historical performance, are not equal to one another. The skills also generally decrease as the lead time increases. Thirdly, forecasts made at some times of the year generally have higher skill than forecasts made at other times of the year--namely, they are better when made between June and December than when they are made between February and May. Differences among the forecasts of the models reflect both differences in model design, and actual uncertainty in the forecast of the possible future SST scenario.
You can highlight a specific model by hovering over it either on the chart or the legend. Selecting An item on the legend will toggle the visibility of the model on the page. You can also select DYN MODELS or STAT MODELS to toggle them all at once. Clicking on the "burger" menu above the legend will give you options to download the image or expand to full screen. If you have any feedback on this new feature, please let us know at webmaster@iri.columbia.edu.
| Seasons (2014-2015) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Model | ASO | SON | OND | NDJ | DJF | JFM | FMA | MAM | AMJ |
| Dynamical models | |||||||||
| NCEP CFS version 2 | 0.5 | 0.9 | 1.1 | 1.1 | 1 | 0.9 | 0.9 | 0.8 | |
| NASA GMAO model | 0.5 | 0.7 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | ||
| Japan Met. Agency model | 0.2 | 0.4 | 0.5 | 0.7 | 0.7 | ||||
| Scripps Inst. HCM | 1.1 | 1.2 | 1.2 | 1.3 | 1.2 | 1 | 0.8 | 0.6 | 0.4 |
| Lamont-Doherty model | 0.4 | 0.3 | 0.2 | 0.2 | 0.2 | 0.3 | 0.3 | 0.3 | 0.6 |
| POAMA (Austr) model | 0.1 | 0.2 | 0.3 | 0.3 | 0.4 | 0.4 | 0.4 | ||
| ECMWF model | 0.6 | 0.9 | 1.1 | 1.2 | 1.2 | ||||
| UKMO model | 0.4 | 0.4 | 0.4 | 0.3 | |||||
| KMA (Korea) SNU model | 0.7 | 0.9 | 0.9 | 1 | 1 | 1 | 0.9 | 0.9 | 0.8 |
| ESSIC Intermed. Coupled model | 0.2 | 0.2 | 0.3 | 0.3 | 0.3 | 0.2 | 0.1 | 0 | -0.1 |
| COLA CCSM3 model | 0.8 | 1 | 1.2 | 1.4 | 1.6 | 1.6 | 1.4 | 1.1 | 0.7 |
| Japan Frontier Coupled model | 0.7 | 0.8 | 0.8 | 0.8 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 |
| CSIR-IRI 3-model MME | 0.6 | 0.7 | 0.9 | 1.1 | 1.3 | 1.1 | |||
| GFDL CM2.1 Coupled Climate model | -0.1 | 0 | 0 | 0.1 | 0.2 | 0.3 | 0.5 | 0.6 | 0.7 |
| Canadian Coupled Fcst Sys | 0.6 | 0.8 | 1 | 1.1 | 1.1 | 1.1 | 1.1 | 1 | 0.8 |
| GFDL CM2.5 FLOR Coupled Climate model | 0.2 | 0.3 | 0.4 | 0.4 | 0.5 | 0.7 | 0.8 | 0.8 | 0.8 |
| Average, dynamical models | 0.5 | 0.6 | 0.7 | 0.7 | 0.8 | 0.8 | 0.7 | 0.7 | 0.6 |
| Statistical models | |||||||||
| NCEP/CPC Markov model | 0.2 | 0.3 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 0.5 | 0.5 |
| NOAA/CDC Linear Inverse | 0.2 | 0.2 | 0.1 | 0.1 | 0 | 0 | -0.1 | -0.1 | -0.1 |
| NCEP/CPC Constructed Analog | 0.6 | 0.8 | 1 | 1.2 | 1.2 | 1.1 | 0.8 | 0.7 | 0.5 |
| NCEP/CPC Can Cor Anal | 0.5 | 0.5 | 0.6 | 0.6 | 0.5 | 0.5 | 0.4 | 0.4 | 0.4 |
| Landsea/Knaff CLIPER | 0.6 | 0.9 | 1.2 | 1.5 | 1.3 | 1.1 | 0.9 | 0.8 | 0.7 |
| Univ. BC Neural Network | 0.6 | 0.8 | 0.8 | 0.8 | 0.9 | 0.8 | 0.8 | 0.7 | 0.6 |
| FSU Regression | 0.1 | 0.2 | 0.2 | 0.3 | 0.3 | 0.3 | 0.3 | 0.4 | 0.5 |
| TCD – UCLA | 0.4 | 0.6 | 0.7 | 0.8 | 0.8 | 0.8 | 0.8 | 0.7 | 0.7 |
| UNB/CWC Nonlinear PCA | 0.2 | 0.2 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0.1 |
| Average, statistical models | 0.4 | 0.5 | 0.6 | 0.7 | 0.6 | 0.6 | 0.5 | 0.5 | 0.4 |
| Average, all models | 0.4 | 0.6 | 0.6 | 0.7 | 0.7 | 0.7 | 0.6 | 0.6 | 0.5 |
Most of the set of dynamical and statistical model predictions issued during late July and early August 2014 predict a transition from neutral ENSO conditions to weak El Nino conditions during northern early fall 2014 with some further warming predicted into late fall and winter 2014-15. Development of El Nino conditions appears approximately 50% likely for the Aug-Oct or Sep-Nov seasons of 2014, and rises to 70-75% by Nov-Jan and Dec-Feb 2014-15. In the most recent week, the SST anomaly in the Nino3.4 region was 0.0 C, reflecting neutral conditions. The monthly anomalous SSTs in the Nino3.4 region were near 0.5 during May and June, but returned to neutral levels during July and August. Based on the multi-model mean predictions, and the expected skill of the models by start time and lead time, the probabilities (X100) for La Niña, neutral and El Niño conditions (using -0.5C and 0.5C thresholds) over the coming 9 seasons are:
| Season | La Niña | Neutral | El Niño |
|---|---|---|---|
| ASO 2014 | ~0% | 58% | 42% |
| SON 2014 | ~0% | 44% | 56% |
| OND 2014 | ~0% | 36% | 64% |
| NDJ 2014 | ~0% | 30% | 70% |
| DJF 2014 | ~0% | 27% | 73% |
| JFM 2015 | ~0% | 32% | 68% |
| FMA 2015 | 1% | 37% | 62% |
| MAM 2015 | 2% | 43% | 55% |
| AMJ 2015 | 4% | 45% | 51% |
The following interactive plot shows the model forecasts issued not only from the current month (as in the plot above),
but also from the 21 months previous to this month. The observations are shown up to the most recently completed
3-month period. The plots allow comparison of plumes from the previous start times, or examination of the forecast
behavior of a given model over time.
Hovering over any single model will highlight that particular model in the chart.
Clicking a particular model will hide/show that model in the chart.
At the bottom of the plot, you can select which models to show in the chart:
all the models, the dynamical models only, or the statistical models only.
Only models producing forecasts on a monthly basis are included. This means that some models whose forecasts appear in the Experimental Long-Lead Forecast Bulletin (produced by COLA) do not appear in the table.
Once an IRI ENSO probability forecast has been published, the results stand even if a model reports an error and changes their data. When this happens we will update the plume with the model's correct values even though our forecast hasn't changed. What this means is that our forecast is always the same, but the underlying data may be different from what we based our forecast on.
The SST anomaly forecasts are for the 3-month periods shown, and are for the Nino 3.4 region (120-170W, 5N-5S). Often, the anomalies are provided directly in a graph or a table by the respective forecasting centers for the Nino 3.4 region. In some cases, however, they are given for 1-month periods, for 3-month periods that skip some of the periods in the above table, and/or only for a region (or regions) other than Nino 3.4. In these cases, the following means are used to obtain the needed anomalies for the table:
The anomalies shown are those with respect to the base period used to define the normals, which vary among the groups producing model forecasts. They have not been adjusted to anomalies with respect to a common base period. Discrepancies among the climatological SST resulting from differing base periods may be as high as a quarter of a degree C in the worst cases. Forecasters are encouraged to use the standard 1991-2020 period as the base period, or a period not very different from it.
The IRI ENSO forecast is released on the 19th of each month. If the 19th falls on a weekend or holiday, it is released on the closest business day.
Forecast and model data used in our probabilistic forecast can be accessed by submitting a Request to Access IRI ENSO Data.
All data from this website is covered under the Creative Commons Attribution 4.0 License. When citing IRI ENSO images or data, please use "Images [or Data] provided by The International Research Institute for Climate and Society, Columbia University Climate School", with a link to https://iri.columbia.edu/ENSO.
The official CPC ENSO probability forecast, based on a consensus of CPC and IRI forecasters. It is updated during the first half of the month, in association with the Official CPC ENSO Diagnostic Discussion. It is based on observational and predictive information from early in the month and from the previous month. It uses human judgment in addition to model output, while the forecast shown in Fig. 3 relies solely on model output. Figure 1 is updated on this page on the second Thursday of every month.
NOAA/CPC ENSO Forecast Graphic, courtesy of NOAA/CPC
×A purely objective ENSO probability forecast, based on regression, using as input the model predictions from the plume of dynamical and statistical forecasts shown in Fig. 4. Each of the forecasts is weighted equally. It is updated near or just after the middle of the month, using forecasts from the plume models that are run in the first half of the month. It does not use any human interpretation or judgment. Figure 3 is updated on the third Thursday of every month.
×Plume of forecasts of the Nino3.4 SST anomaly from dynamical and statistical models that are run during the first half of the month. A probability forecast is generated using all the models in Fig. 4, and is shown in Fig. 3. The average of the forecasts of the dynamical models is shown by the thick yellow line, and of the statistical models by the thick green line. The average of the four models run at the NOAA Climate Prediction center (CPC) is shown by the thick pink line. This figure is updated on the third Thursday of every month. Because forecasts from some models of Fig. 4 are not yet available when the official CPC ENSO probability forecast (Fig. 1) is made, the official forecast uses the previous month's Fig. 4 as one of its inputs, which is shown in the CPC ENSO Diagnostic Discussion.
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