The canonical correlation analysis (CCA) forecast
of SST in the central Pacific (Barnett et al. 1988, Science, 241, 192-196;
Barnston and Ropelewski 1992, J. Climate, 5, 1316-1345), is shown in Figs.
F1 and F2. This forecast is produced
routinely by the Prediction Branch of the Climate Prediction Center. The predictions from
the National Centers for Environmental Prediction (NCEP) coupled ocean/atmosphere model
(Ji et al. 1998, Mon. Wea. Rev, 126, 1022-1034) are presented in Figs. F3 and F4. Predictions from the latest
version of the LDEO model (Chen, D., M. A. Cane, S. E. Zebiak, Rafael Canizares and A.
Kaplan, 2000, Geophys. Res. Let., accepted) are shown in Figs. F5 and F6. Predictions using linear
inverse modeling (Penland and Magorian 1993, J. Climate, 6, 1067-1076) are
shown in Figs. F7 and F8.
Predictions from the Scripps / Max Planck Institute (MPI) hybrid coupled model (Barnett et
al. 1993, J. Climate, 6, 1545-1566) are shown in Fig. F9.
The CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
Cold episode (La Niņa) conditions are expected to gradually weaken through the spring
of 2001 followed by near-normal conditions in the tropical Pacific during the summer of
Mature cold episode (La Niņa) conditions continued in the tropical
Pacific during February, as sea surface temperatures (SSTs) remained well below normal
across the central equatorial Pacific (Fig. T18 and Table T2). The slope of the oceanic thermocline remained greater
than normal, with positive (negative) subsurface temperature anomalies in the west-central
(eastern) equatorial Pacific (Figs. T16 and T17). This pattern of anomalous subsurface temperatures has been
highly persistent since mid-1998, though its strength has exhibited a distinct annual
cycle (Fig. T15). The cooler-than-normal surface waters
contributed to a vigorous Walker circulation over the equatorial central Pacific (Fig. T29) characterized by enhanced low-level easterlies (Fig. T20), enhanced upper-level westerlies (Fig. T21), suppressed deep convection over the western and
central equatorial Pacific, and enhanced deep convection over the Phillippines, Indonesia
and the eastern Indian Ocean (Figs. T25 and E3). During February, the pattern of tropical convection was
strongly influenced by tropical intraseasonal (Madden-Julian Oscillation) activity,
especially over the eastern Indian Ocean, Indonesia and the western Pacific (Fig. T11). Overall, the patterns of anomalous 850-hPa zonal
wind and convection have shown remarkable similarity in the tropical Pacific during the
last three years, with a distinct annual cycle featuring maxima in the OLR anomalies (Fig. T8) and maxima in the 850-hPa easterlies (Fig. T7) over the central equatorial Pacific during northern
Over the past two years there has been a gradual eastward expansion of the area of
positive subsurface temperature anomalies into the central Pacific (Fig.
T15). This evolution is consistent with a slow decay of the subsurface thermal
structure that characterizes the mature phase of cold episodes. Thus, it is likely that
cold episode conditions will gradually weaken over the next several months, with
near-normal conditions likely during the summer of 2001. This assessment is generally
supported by the most recent NCEP statistical (Figs. F1 and F2) and coupled model forecasts (Figs. F3
and F4), as well as by other available forecasts (Figs. F5, F6, F7, F8, and F9), which indicate a gradual
weakening of cold episode conditions during the next few months. Thereafter, the models
indicate near-normal or slightly warmer-than-normal conditions during the second half of
Weekly updates of SST, 850-hPa wind, OLR, and the equatorial subsurface temperature
structure are available on the Climate Prediction Center homepage at:
http://www.cpc.ncep.noaa.gov (Weekly Update).