Skip Navigation Links 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center

CPC Search
Expert Assessments
   ENSO Diagnostic
     Discussion Archive

About Us
   Our Mission
   Who We Are

Contact Us
   CPC Information
   CPC Web Team

HOME > Expert Assessments > ENSO Diagnostic Discussion
issued by
January 12, 2006
Spanish Version (Español -- Courtesy of INFOCLIMA, Peru)

Synopsis: Developing La Niña conditions are expected to continue during the next 3-6 months.

Equatorial SST anomalies greater than +0.5ºC were restricted to the region between Indonesia and 165ºE during December, while negative anomalies less than –0.5ºC were observed at most locations between the date line and the South American coast (Fig. 1). By the end of the month the SST departures were negative in all of the Niño regions (Fig. 2). During the last several months surface and subsurface temperature anomalies have decreased in the region between 180ºW and the South American coast (Fig. 3). During the same period persistent stronger-than-average low-level equatorial easterly winds were observed over the central Pacific.Since early November there has been a persistent pattern of enhanced tropical convection near 130ºE (Indonesia) and suppressed convection near the date line (180ºW). Collectively, the present oceanic and atmospheric anomalies are consistent with the development of La Niña conditions in the tropical Pacific.

Over the past several months most of the statistical and coupled model forecasts have trended towards cooler conditions in the tropical Pacific through mid-2006. The spread of the most recent statistical and coupled model forecasts (weak La Niña to ENSO-neutral) indicates some uncertainty in the outlooks (Fig. 4). However, current conditions (stronger-than-average easterly winds over the central equatorial Pacific) and recent cooling trends in observed oceanic conditions support the continuation of La Nina conditions in the tropical Pacific during the next 3-6 months.

Based on current conditions in the tropical Pacific, the most recent SST predictions,and on results from historical studies on the effects of cold episodes, we expect wetter-than-normal (drier-than-normal) conditions to prevail over Indonesia (central equatorial Pacific) during the remainder of the NH winter. That pattern of tropical precipitation favors a northward shift in the position of the jet stream over the eastern North Pacific during winter, which is usually accompanied by drier-than-normal conditions over southern California and Arizona. However, given the late onset of La Niña there is considerable uncertainty as to whether or not typical La Niña impacts will be experienced in the West during the remainder of NH winter.

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 9 February 2006. To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message:

Climate Prediction Center
National Centers for Environmental Prediction
NOAA/National Weather Service
Camp Springs, MD 20746-4304

NOAA/ National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
5200 Auth Road
Camp Springs, Maryland 20746
Page Author: Climate Prediction Center Internet Team
Page last modified: January 12, 2006
Information Quality
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities