La Niña Begins to Weaken

by |February 18, 2011

This map, updated weekly, shows the cooler-than-normal sea-surface temperatures (blue) in the equatorial Pacific that define La Niña. Click on the chart to go to an interactive version in the IRI Data Library.

The current moderate-strength La Niña is now weakening and is expected to dissipate by late spring, said Tony Barnston, the lead forecaster at the International Research Institute for Climate and Society, which holds a monthly climate briefing.

Early February showed the first easing in strength of the cool sea-surface temperatures in the central and eastern tropical Pacific. The warmer sub-surface waters of the western Pacific are also gradually nosing eastward.  Both these indicators led IRI forecasters to predict only a 49% chance that this La Niña will continue through the April-May-June season and a 34% chance it will continue through the May-June-July season.

This chart shows historical sea-surface temperature anomaly averages for part of the equatorial Pacific. Red signifies the warmer-than-normal temperatures of El Niño, while blue signifies the cooler-than-normal temperatures of La Niña. Click on the chart to go to an interactive version in the IRI Data Library.

Because of this current La Niña’s extended duration, its strong rainfall impacts will likely also continue farther into the spring than is typical for La Niña events.  This La Niña has already been linked to flooding in Pakistan, West Africa, South Africa and eastern Australia, according to climate scientists.

If you want to learn more about El Niño, La Niña and everything in between, visit the IRI’s ENSO resources page.

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