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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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www.nws.noaa.gov
