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Published August 21, 2013
El Niño Status and ForecastData Source(s): NOAA-Climate Prediction Center (CPC), International Research Institute for Climate and Society (IRI)
The El Niño-Southern Oscillation (ENSO) remains neutral, as sea surface temperatures (SSTs) have been close to average across the tropical Pacific Ocean. The upper and lower atmospheric winds also have been close to average for this time of year, an additional indication that the neutral conditions are firmly entrenched in the Pacific region. The Southern Oscillation Index (SOI), a measure of the atmospheric circulation patterns, remains neutral (Figure 14a). These signs suggest that the development of either an El Niño or La Niña event is not imminent.
Official SST outlooks issued jointly by the NOAA-Climate Prediction Center (CPC) and International Research Institute for Climate and Society (IRI) support neutral conditions persisting into spring 2014. The outlook for the August–October period indicates more than a 73 percent chance that neutral conditions will continue, less than a 19 percent chance that a La Niña event will develop, and about an 8 percent chance that an El Niño event will emerge (Figure 14b). The outlook for neutral conditions is at or above 55 percent through May 2014. However, the CPC notes that the variability in ENSO models is unusually high for this time of the year, indicating uncertainty in these outlooks, especially in those periods farther in the future. Statistical models generally show a progression towards cooler SSTs, which would characterize a borderline La Niña event, while dynamical models are showing warmer SSTs, reflecting a borderline El Niño event. The consensus forecast, therefore, falls in the middle with neutral conditions. The uncertainty, however, bears monitoring over the next several months. The temperature and precipitation outlooks are in part based on the expectation of ENSO-neutral conditions. If ENSO changes direction in coming months, these forecasts also will likely change.Notes:
The first figure shows the standardized three-month running average values of the Southern Oscillation Index (SOI) from January 1980 through June 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.
Technical discussion of current El Niño conditions::
Information about El Niño and to access graphics similar to the figures on this page::
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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