La Niña Rolls On

by |January 21, 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.

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.

The current moderate-to-strong La Niña is expected to continue through at least the middle of spring, said forecasters at the International Research Institute for Climate and Society’s monthly climate briefing.

La Niña events typically die out quickly this time of year, but the sustained presence of very cool sea-surface and sub-surface temperatures in the eastern tropical Pacific led IRI forecasters to predict a 67% chance this La Niña will continue through the March-April-May season. But its days are limited because warmer sub-surface waters in the western Pacific are beginning to nose eastward.

While this La Niña’s peak sea-surface temperature anomaly did not quite reach the strength of the one in 2008, its extended duration and strong rainfall impacts may make this one more memorable. Climate scientists have already linked it to widespread flooding that has occurred in Pakistan, West Africa, eastern Australia and other areas.  Rainfall patterns around the world have shifted more dramatically than is typical of a La Niña of this strength, although the reasons why aren’t yet fully understood, says IRI’s lead forecaster, Tony Barnston.

In the video embedded here, IRI’s Brad Lyon gives a rundown of the current situation, with maps showing how La Niña has affected precipitation and temperature.

[vimeo]http://vimeo.com/19010936[/vimeo]

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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