ENSO Update

15 February 2006

Summary

General Discussion 

During January 2006, sea surface temperatures (SSTs) were approximately 1.0C below average in the central Pacific and approximately 0.5C above average in the western Pacific. Although the magnitude of the coldest SST anomalies was similar to that of December 2005, the pattern of anomalies shifted westward into the central Pacific during January.

There appears to be sufficient changes in the upper ocean thermal structure, created by the low-level wind response to the SST anomalies, to maintain the cool SST conditions at least through the next several months. Out of a large set of dynamical and statistical forecast models, most predict weak La Nina conditions continuing into levels early northern spring 2006, returning to ENSO-neutral conditions thereafter. Overall, based on model forecasts and current observations of the ocean surface and subsurface, the probability of a La Niña event for the next season is approximately 65%, decreasing to 20% by mid-2006. The chances for developing El Niño conditions are estimated at approximately 2% through April 2006, increasing to 25% by the mid-2006.

Note 1 - Only models that produce a new ENSO forecast every month are included in the above statement.