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Published March 27, 2013
El Niño Status and ForecastData Source(s): NOAA-Climate Prediction Center (CPC), International Research Institute for Climate and Society (IRI)
Sea surface temperatures (SSTs) in the equatorial Pacific Ocean held steady this past month and continue to hover close to average for this time of the year. The International Research Institute for Climate and Society (IRI) states that while the presence of slightly enhanced easterly winds continues along the equator this month—a signal more consistent with borderline La Niña conditions—most other indicators such as the SST pattern point to ENSO-neutral conditions. The Southern Oscillation Index (SOI) is also exhibiting ENSO-neutral conditions (Figure 13a).
SST outlooks issued jointly by the NOAA-Climate Prediction Center and IRI continue to point towards a strong likelihood that ENSO-neutral conditions will remain in place through at least the upcoming spring season if not longer (Figure 13b). Outlooks issued in mid-March also show that there is greater than a 50 percent chance that neutral conditions will persist through 2013; a majority of both statistical and dynamical models support this. Several dynamical models, however, also point to the possibility that an El Niño will develop in mid-summer. There is low confidence in this scenario at this point due to lack of model agreement and challenges with the spring predictability barrier, which occurs because models have difficulty identifying the initiation of La Niña or El Niño events at this time of year. ENSO forecasts will continue to become more certain later in the spring, but there already appears to be strong agreement among models that neutral conditions will persist.Notes:
The first figure shows the standardized three month running average values of the Southern Oscillation Index (SOI) from January 1980 through February 2013. The SOI measures the atmospheric response to SST changes across the Pacific Ocean basin. The SOI is strongly associated with climate effects in the Southwest. Values greater than 0.5 represent La Niña conditions, which are frequently associated with dry winters and sometimes with wet summers. Values less than -0.5 represent El Niño conditions, which are often associated with wet winters.
The second figure shows the International Research Institute for Climate and Society (IRI) probabilistic El Niño-Southern Oscillation (ENSO) forecast for overlapping three month seasons. The forecast expresses the probabilities (chances) of the occurrence of three ocean conditions in the ENSO-sensitive Niño 3.4 region, as follows: El Niño, defined as the warmest 25 percent of Niño 3.4 sea-surface temperatures (SSTs) during the three month period in question; La Niña conditions, coolest 25 percent of Niño 3.4 SSTs; and neutral conditions where SSTs fall within the remaining 50 percent of observations. The IRI probabilistic ENSO forecast is a subjective assessment of current model forecasts of Niño 3.4 SSTs that are made monthly. The forecast takes into account the indications of the individual forecast models (including expert knowledge of model skill), an average of the models, and other factors.
For a technical discussion of current El Niño conditions, visit:
For more information about El Niño and to access graphics similar to the figures on this page, visit:
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, Managing Editor, CLIMAS Associate Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Dollin, CLIMAS Publications Assistant
- Dave Dubious, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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