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IRI ENSO Forecast

2013 November Quick Look

Published: November 21, 2013

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)

Use the navigation menu on the right to navigate to the different forecast sections

During October through mid-November the observed ENSO conditions remained neutral. Most of the ENSO prediction models indicate a continuation of neutral ENSO into the first quarter of 2014. During northern spring and summer a warming tendency is seen in both dynamical and statistical models.

Historically Speaking

    El Niño and La Niña events tend to develop during the period Apr-Jun and they
  • Tend to reach their maximum strength during Dec-Feb
  • Typically persist for 9-12 months, though occasionally persisting for up to 2 years
  • Typically recur every 2 to 7 years

Figure 1 is based on a consensus of CPC and IRI forecasters, in association with the official CPC/IRI ENSO Diagnostic Discussion

Figure 3 is purely objective, based on regression, using equally weighted model predictions from the plume

IRI ENSO Forecast

CPC/IRI ENSO Update

Published: Nov 7, 2013

El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued jointly by the Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society

ENSO Alert System Status: Not Active

Synopsis: ENSO-neutral is expected into the Northern Hemisphere spring 2014.

During October, ENSO-neutral persisted, as reflected by near-average sea surface temperatures (SST) across much of the equatorial Pacific Ocean (Fig. 1).  During the month, slightly below-average SSTs were evident in most of the Niño regions, except for Niño-4, which remained near zero (Fig. 2).   However, the oceanic heat content (average temperature in the upper 300m of the ocean) rose from near average to slightly above average (Fig. 3),  due to the eastward shift of a downwelling oceanic Kelvin wave, which was reflected in the above-average subsurface temperatures across the western half of the Pacific (Fig. 4). The atmospheric circulation remained largely near average during the month, with generally small departures in equatorial convection (Fig. 5) and upper and lower-level winds. Collectively, these atmospheric and oceanic conditions reflect ENSO-neutral

The majority of model forecasts indicate that ENSO-neutral (Niño-3.4 index between -0.5°C and 0.5°C) will persist into the Northern Hemisphere summer 2014  (Fig. 6). Though confidence is highest for ENSO-neutral, there are also growing probabilities for warm conditions (relative to cool conditions) toward the spring/summer 2014.  The consensus forecast is for ENSO-neutral to continue through the Northern Hemisphere spring 2014 (see CPC/IRI consensus forecast).

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 for the evolution of El Niño/La Niña are updated monthly in the Forecast Forum section of CPC’s Climate Diagnostics Bulletin. The next ENSO Diagnostics Discussion is scheduled for 5 December 2013. 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.

CPC/IRI Early-Month Consensus ENSO Forecast Probabilities

Season La Niña Neutral El Niño
OND 2013 7% 91% 2%
NDJ 2014 9% 86% 5%
DJF 2014 9% 82% 9%
JFM 2014 10% 78% 12%
FMA 2014 10% 74% 16%
MAM 2014 11% 67% 22%
AMJ 2014 11% 60% 29%
MJJ 2014 12% 55% 33%
JJA 2014 12% 52% 36%


Figure 7. NCEP CFSv2 forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W-170°W). Figure updated 3 November 2014.

IRI ENSO Forecast

IRI Technical ENSO Update

Published: November 21, 2013

Recent and Current Conditions

The SST anomaly in the Nino3.4 region has been in the neutral range lately, through mid-November 2013.  For October 2013 the Nino3.4 SST anomaly was -0.28 C, indicative of neutral ENSO conditions, and for August-October it was -0.23 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, indicating exactly average ENSO-related SST conditions in the tropical Pacific; this is slightly less cool than the -0.28 C level observed in October.

Expected Conditions

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 high likelihood of neutral ENSO conditions enduring through the remainder of northern autumn into winter 2013-14, and through spring 2014, with probabilities of El Niño or La Niña each less than 30% until May-Jul 2014 when El Niño probabilities rise above that level but still less than 50%. The latest set of model ENSO predictions, from mid-September, now available in the IRI/CPC ENSO prediction plume, is discussed below. Currently, Nino3.4 SST anomalies are near the middle of the ENSO-neutral range. The SST continues to be slightly above average in the far western part of the basin, but continues to be below average in the eastern quarter of the basin, but much less strongly so than several months ago. Subsurface temperature anomalies across the central and eastern equatorial Pacific have been slightly above average since mid-May, and are now becoming somewhat more clearly/strongly positive. In the atmosphere, the basin-wide sea level pressure pattern (e.g. the SOI), and the low-level zonal winds have been approximately average across much of the basin. The upper level zonal winds are now also near-average across the tropical Pacific. Anomalous convection (as measured by OLR) has generally been negative in the west-central tropical Pacific, and positive in the far western part of the basin and Indonesia. Together, these features reflect ENSO-neutral conditions.

As of mid-November, only 8% of the set of dynamical and statistical models models predicts weak La Niña SST conditions for the Nov-Jan 2013-14 season, 4% predicts El Niño conditions, and 88% 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 Feb-Apr 2014 season, among models that do use subsurface temperature information, 76% predicts ENSO-neutral SSTs, 24% predicts El Niño conditions and none predicts La Niña conditions. For all model types, the probability for neutral ENSO conditions is near 90% from Nov-Jan 2013-14 to Jan-Mar 2014, between 74% and 83% from Feb-Apr through May-Jul 2014, and 55%-60% for Jun-Aug and Jul-Sep 2014 at the end of the forecast period.

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 at 1% for Nov-Jan 2013-14, remaining at 10% or less through the end of the forecast period in northern summer 2014. Model probabilities for ENSO-neutral conditions are more than 90% from Nov-Jan 2013-14 to Jan-Mar 2014, dropping steadily during northern spring 2014, to become less than 50% from May-Jul through the end of the forecast period in Jul-Sep 2014. Probabilities for El Niño are below 10% from Nov-Jan 2013-14 to Jan-Mar 2014, thereafter steadily increasing to exceed 30% by Apr-Jun 2014 and to between 40% and 50% from May-Jul to Jul-Sep 2014 (maximizing at 48% for both Jun-Aug and Jul-Sep, the last two forecast seasons). It is clear that the models collectively favor neutral ENSO conditions into northern spring 2014; then by May-Jul El Niño probabilities become more competitive with ENSO-neutral probabilities, until they are approximately equally likely from May-Jul 2014 onward.

figure3 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, maintenance of neutral ENSO conditions during the coming months, continuing into northern spring 2014. The possibility of El Niño development is seen starting May-Jul 2014, and the objective model-based probabilities for that still remain just barely shy of 50% for Jun-Aug and Jul-Sep 2014. 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.

Using the 0.5 C thresholds, the climatological probabilities of La Nina, neutral, and El Nino conditions for each 3-month season are as follows:

Climatological Probabilities
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%

IRI ENSO Forecast

IRI/CPC Plume-Based Probabilistic ENSO Forecast

Published: November 21, 2013



IRI/CPC Mid-Month Plume-Based ENSO Forecast Probabilities

Season La Niña Neutral El Niño
NDJ 2014 1% 99% ~0%
DJF 2014 3% 96% 1%
JFM 2014 4% 92% 4%
FMA 2014 5% 84% 11%
MAM 2014 5% 74% 21%
AMJ 2014 7% 59% 34%
MJJ 2014 10% 48% 42%
JJA 2014 8% 44% 48%
JAS 2014 9% 43% 48%

IRI ENSO Forecast

CPC/IRI Consensus Probabilistic ENSO Forecast

Published: Nov 7, 2013



CPC/IRI Early-Month Consensus ENSO Forecast Probabilities

Season La Niña Neutral El Niño
OND 2013 7% 91% 2%
NDJ 2014 9% 86% 5%
DJF 2014 9% 82% 9%
JFM 2014 10% 78% 12%
FMA 2014 10% 74% 16%
MAM 2014 11% 67% 22%
AMJ 2014 11% 60% 29%
MJJ 2014 12% 55% 33%
JJA 2014 12% 52% 36%

IRI ENSO Forecast

IRI/CPC ENSO Predictions Plume

Published: November 21, 2013

Note on interpreting model forecasts

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.


Seasons (2013-2014)
Model
Dynamical models
NCEP CFS version 2 0.1 0 -0.1 0 0.2 0.3 0.4 0.5
NASA GMAO model -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 0
Japan Met. Agency model 0 0.1 0.1 0.2 0.3
Scripps Inst. HCM 0.3 0.4 0.5 0.6 0.7 0.7 0.7 0.8 0.9
Lamont-Doherty model -0.5 -0.6 -0.5 -0.4 -0.3 -0.1 0.1 0.3 0.3
POAMA (Austr) model -0.1 -0.1 -0.1 0 0 0 0
ECMWF model 0.1 0.1 0.1 0.2 0.2
UKMO model -0.2 -0.3 -0.4
KMA (Korea) SNU model 0.2 0.4 0.5 0.5 0.5 0.5 0.5 0.4 0.4
ESSIC Intermed. Coupled model -0.2 -0.2 -0.2 -0.1 0 0.1 0.1 0.2 0.2
COLA CCSM3 model 0.7 0.9 1.1 1.3 1.5 1.5 1.3 1.2 1.1
MÉT&#201O FRANCE model -0.1 0 0 0.1 0.2
Japan Frontier Coupled model 0.2 0.3 0.3 0.3 0.3 0.3 0.4 0.5 0.5
CSIR-IRI 3-model MME -0.3 -0.4 -0.4 -0.3 -0.2
GFDL CM2.1 Coupled Climate model 0.1 0.3 0.4 0.5 0.6 0.8 0.9 0.9 0.8
Canadian Coupled Fcst Sys 0.1 0.1 0.1 0.2 0.2 0.3 0.4 0.5 0.5
Average, dynamical models 0 0 0.1 0.2 0.3 0.4 0.4 0.6 0.6
Statistical models
NCEP/CPC Markov model -0.3 -0.2 -0.1 0 0.1 0.1 0.2 0.2 0.2
NOAA/CDC Linear Inverse -0.3 -0.3 -0.3 -0.3 -0.3 -0.2 -0.1 -0.1 0
NCEP/CPC Constructed Analog -0.3 -0.3 -0.3 -0.3 -0.1 0.2 0.3 0.4 0.3
NCEP/CPC Can Cor Anal -0.5 -0.5 -0.4 -0.2 0 0.2 0.3 0.5 0.5
Landsea/Knaff CLIPER 0 0 0 0 0.1 0.2 0.3 0.3 0.4
Univ. BC Neural Network -0.2 -0.1 -0.1 0 0.1 0.1 0.2 0.3 0.3
FSU Regression -0.2 -0.1 -0.1 0 0.2 0.5 0.7 0.9 0.8
TDC – UCLA -0.2 -0.3 -0.3 -0.2 -0.2 -0.1 0 0.1 0.1
Average, statistical models -0.2 -0.2 -0.2 -0.1 0 0.1 0.2 0.3 0.3
Average, all models -0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.5

Discussion of Current Forecasts

Most of the set of dynamical and statistical model predictions issued during late October and early November 2013 predict neutral ENSO conditions through the rest of 2013 and into early 2014, with a warming tendency during northern spring and summer 2014. Development of weak El Nino conditions appears possible by the middle of 2014. In the most recent week, the SST anomaly in the Nino3.4 region was 0.0C. 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 Nina, neutral and El Nino conditions (using -0.5C and 0.5C thresholds) over the coming 9 seasons are:

IRI/CPC Mid-Month Plume-Based ENSO Forecast Probabilities

Season La Niña Neutral El Niño
NDJ 2014 1% 99% ~0%
DJF 2014 3% 96% 1%
JFM 2014 4% 92% 4%
FMA 2014 5% 84% 11%
MAM 2014 5% 74% 21%
AMJ 2014 7% 59% 34%
MJJ 2014 10% 48% 42%
JJA 2014 8% 44% 48%
JAS 2014 9% 43% 48%

Summary of forecasts issued over last 22 months

The following plots show 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 also 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. The first plot shows forecasts for dynamical models, the second for statistical models, and the third for all models. For less difficult readability, forecasts are shown to a maximum of only the first five lead times. Below the third plot, we provide a mechanism for highlighting the forecasts of one model at a time against a background of more lightly colored lines for all other models.


Notes on the data 

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.

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:

  • Temporal averaging
  • Linear temporal interpolation
  • Visual averaging of values on a contoured map

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 1971-2000 period as the base period, or a period not very different from it.