La Nina Draws to a Close

The 2008-2009 La Nina has drawn to a close and the Climate Prediction Center has officially called an end to the continued monitoring of this year’s event.

The 2008-2009 La Niña has drawn to a close, as indicated by the lack of a significant temperature anomoly in the equatorial Pacific.  Source:  NOAA
The 2008-2009 La Niña has drawn to a close. Image indicates sea surface water temperatures (top) and the departure from the average sea surface temperature (bottom). La Niña is indicative of cooler than normal (blue). The lack of a significant temperature anomaly in the equatorial Pacific indicates to scientists that this year's La Niña has come to an end. Image Source: NOAA

La Niña (Spanish for “the little girl”) is the term used to describe the period when the sea surface temperatures of the equatorial Pacific ocean are cooler than normal. This region of the ocean tends to waiver between periods that are warmer than average (referred to as “El Niño”) and warmer than average – La Niña . In between these extremes are relatively neutral periods where sea surface temperatures are within a degree or two of average. It is this neutral period that the Climate Prediction Center is indicating is now imminent.

The end of the current La Niña indicates that the Pacific Northwest may begin to dry out and the south may return to near-normal rainfall patterns.

La Niña tends to bring nearly opposite effects of El Niño to the United States — wetter than normal conditions across the Pacific Northwest and dryer and warmer than normal conditions across much of the southern tier. The impacts of El Niño and La Niña at these latitudes are most clearly seen in wintertime. In the continental U.S., during El Niño years, temperatures in the winter are warmer than normal in the North Central States, and cooler than normal in the Southeast and the Southwest. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest.

It is unknown precisely when El Nino will return.


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