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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 0.5C or greater is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5N-5S, 120W-170W) and an expectation that the 3-month Oceanic Nio 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 -0.5C or less is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5N-5S, 120W-170W) and an expectation that the 3-month Oceanic Nio 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: August 3, 2011
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