Strong cold episode conditions continued in the tropical Pacific during January, as sea surface temperatures (SSTs) remained well below normal across the central and east-central equatorial Pacific (Fig. T18 and Table T2). Negative subsurface temperature anomalies and a shallower-than-normal oceanic thermocline continued to dominate the equatorial Pacific east of the date line (Fig. T16). Tropical convection during January (as inferred from Outgoing Longwave Radiation (OLR) measured by NOAA’s polar-orbiting satellites) was suppressed over the western and central equatorial Pacific and enhanced over Indonesia (Fig. T25). Accompanying these conditions, the mean low-level equatorial easterly winds were stronger-than-normal over the western and central tropical Pacific and near normal over the eastern Pacific (Fig. T20). These patterns of anomalous convection and low-level winds have been highly persistent during the last year, consistent with ongoing cold episode conditions.

Over the past several months the pattern of subsurface temperature anomalies has been very persistent, with positive anomalies in the western equatorial Pacific and negative anomalies in the eastern equatorial Pacific (Fig. T17). A notable feature of the current cold episode is the lack of evolution of the subsurface thermal structure from a pattern that is typical of the mature phase of cold episodes towards a pre-warm episode state. Thus, it is likely that cold episode conditions will continue for at least the next several months. This assessment is supported by the most recent NCEP coupled model forecast (Figs. F3 and F4) and by other available coupled model and statistical model predictions that indicate cold episode conditions persisting through the spring of 2000, followed by a return toward normal SSTs during the last half of the year.