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HOME > Expert Assessments > ENSO Diagnostic Discussion > ENSO Alert System
 
 

ENSO ALERT SYSTEM:

 

El Niño or La Niña Watch: Issued when conditions are favorable for the development of El Niño or La Niña conditions within the next six months.

El Niño or La Niña Advisory: Issued when El Niño or La Niña conditions are observed and expected to continue.

Final El Niño or La Niña Advisory: Issued after El Niño or La Niña conditions have ended.

NA: ENSO Alert System is not active.


The Climate Prediction Center defines. . .

    "El Niño conditions" as existing when:
    • A one-month positive sea surface temperature anomaly of 0.5° C or greater is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5° N - 5° S, 120° W - 170° W) and an expectation that the 3-month Oceanic Niño Index (ONI) threshold will be met, AND
    • An atmospheric response typically associated with El Niño is observed over the equatorial Pacific Ocean (see The ENSO Cycle).

    "La Niña conditions" as existing when:
    • A one-month negative sea surface temperature anomaly of -0.5° C or less is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5° N - 5° S, 120° W - 170° W) and an expectation that the 3-month Oceanic Niño Index (ONI) threshold will be met , AND
    • An atmospheric response typically associated with La Niña is observed over the equatorial Pacific Ocean (see The ENSO Cycle).


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Page last modified: June 13, 2018
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