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HOME > Expert Assessments > ENSO Diagnostic Discussion
 
 
EL NIŅO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP
April 7, 2005
 
Spanish Version (Español -- Courtesy of INFOCLIMA, Peru)
 

Synopsis: A transition fromweak warm-episode (El Niņo conditions to ENSO-neutral conditions is expected to continue during the next three months.

Sea surface temperature  (SST) anomalies increased in the Niņo 3.4 and Niņo 3 regions during March 2005 (Fig. 1), while positive SST anomalies [greater than +0.5°C (~0.9°F)] persisted in the Niņo 4 region. By the end of the month, positive equatorial SST anomalies greater than +0.5°C (~0.9°F) extended from Indonesia eastward to 115°W (Fig. 2). Cloudiness and precipitation returned to near average over Indonesia , while the enhanced precipitation, observed over the central tropical Pacific in February, weakened and drier-than-average conditions developed over that region (Fig. 3).

The increase in SST anomalies and upper-ocean heat content (Fig. 4) in the east-central equatorial Pacific during the last half of March was associated with an eastward-propagating oceanic Kelvin wave (downwelling phase). This wave is stronger than those that have occurred in recent months in association with MJO activity. Surface and subsurface ocean temperatures are expected to increase along the west coast of South America (Ecuador and northern Peru) during April. However, substantial cooling in the upper ocean has occurred in the wake (upwelling phase) of this Kelvin wave, accompanied by a strengthening of the easterly winds over the central and western equatorial Pacific during March. This cooling is expected to propagate eastward, eventually reaching the eastern equatorial Pacific during May. Thus, the effects of the expected warming along the west coast of South America during April should be brief.

A majority of the statistical and coupled model forecasts indicate that a transition from weak warm- episode (El Niņo) conditions to ENSO-neutral conditions will continue during the next three months, and that ENSO-neutral conditions will likely prevail during the northern summer

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 http://www.cpc.ncep.noaa.gov (Weekly Update). Forecasts for the evolution of El Niņo/La Niņa are updated monthly in the Forecast Forum section of CPC's Climate Diagnostics Bulletin. The next ENSO Diagnostics Discussion is scheduled for 5 May 2005.  To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send your e-mail address to: ncep.list.enso-update@noaa.gov.

 
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