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HOME > Expert Assessments > ENSO Diagnostic Discussion
issued by
April 6, 2006

Spanish Version (Español -- Courtesy of INFOCLIMA, Peru)

Weekly ENSO Update (PDF, PPT) - updated Mondays

Synopsis: La Niña conditions are expected to continue during the next 1-3 months.

The patterns of anomalous ocean temperatures, atmospheric circulation and precipitation are consistent in indicating La Niña conditions in the tropical Pacific. During March negative equatorial SST anomalies less than –0.5ºC were observed at most locations between 180ºW and 90ºW (Fig. 1), and negative SST departures were observed in all of the Niño regions, except for Niño 1+2 (Fig. 2). During the month, positive SST departures decreased in the extreme eastern equatorial Pacific, as conditions returned to near average in that region.

During March above-average precipitation (negative OLR anomalies, Fig. 3, top panel) was observed over Indonesia, the Philippines, northern Australia and Hawaii, while below-average precipitation (positive OLR anomalies) was observed over the central equatorial Pacific and over the eastern tropical Pacific between the equator and 10ºN. Stronger-than-average low-level (850-hPa) easterly winds (Fig. 3, middle panel) persisted over the central equatorial Pacific, and anomalous upper-level (200-hPa) cyclonic circulation centers were observed in both hemispheres (Fig. 3, bottom panel). The equatorial subsurface temperature anomaly pattern (negative anomalies in the central and eastern Pacific and positive anomalies in the western Pacific, Fig. 4) persisted during February-March 2006, and the basin-wide upper ocean heat content, although increasing, remained below-average (Fig. 5). These atmospheric and oceanic features are consistent with ongoing La Niña conditions.

Most of the statistical and coupled model forecasts indicate ENSO-neutral conditions in the tropical Pacific through the end of 2006 (Fig. 6). The spread of the most recent statistical and coupled model forecasts (weak La Niña to weak El Niño) indicates uncertainty in the outlooks for the last half of the year. However, current conditions (stronger-than-average easterly winds over the central equatorial Pacific and below-average upper-ocean heat content) support those forecasts indicating that La Nina conditions will continue for the next 1-3 months.

This discussion is a consolidated effort of NOAA and its funded institutions. Weekly updates for SST, 850-hPa wind, OLR and features of the equatorial subsurface thermal structure are available on the Climate Prediction Center web page at (Weekly Update). Forecasts for the evolution of El Niño/La Niña are updated monthly in the Forecast Forum section of CPC's Climate Diagnostics Bulletin. The next ENSO Diagnostics Discussion is scheduled for 11 May 2006. To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message:

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National Centers for Environmental Prediction
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Page Author: Climate Prediction Center Internet Team
Page last modified: January 12, 2006
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