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 (5oN-5oS,
120oW-170oW) 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 -0.5C or less is
observed in the Niño-3.4 region of the equatorial Pacific Ocean (5oN-5oS,
120oW-170oW) 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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