|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 Cane and
Zebiak model (Cane et al. 1986, Nature, 321, 827-832; Zebiak and Cane 1987, Mon.
Wea. Rev., 115, 2262-2278) are shown in Figs. F5 and
F6. Predictions from the modified Cane and Zebiak model (Chen
et al. 1998, Geophys. Res. Let., 103, 2387-2840), referred to in the figures
as LDEO3, are shown in Figs. F7 and F8.
Predictions using linear inverse modeling (Penland and Magorian 1993, J. Climate, 6,
1067-1076) are shown in Figs. F9 and F10.
Predictions from the Scripps / Max Planck Institute (MPI) hybrid coupled model (Barnett et
al. 1993, J. Climate, 6, 1545-1566) are shown in Fig. F11.
The CPC and the contributors to the Forecast Forum caution
potential users of this predictive information that they can expect only modest skill.
Discussion and Outlook
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 NOAAs 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.
Based on current conditions in the tropical Pacific, on the NCEP SST predictions, and
on results from historical studies on the effects of cold episodes, we expect
wetter-than-normal conditions to continue through March over Indonesia, northern
Australia, and southern Africa. Wetter-than-normal conditions should continue over
northeastern South America through May. Over the United States, drier- and
warmer-than-normal conditions are expected along the southern tier of states from southern
California eastward to the Carolinas. Cooler-than-normal conditions are also likely over
southern Alaska, western and central Canada and in the upper Midwest.
Weekly updates of SST, 850-hPa wind and OLR are available on the Climate Prediction
Center homepage at: http://www.cpc.ncep.noaa.gov (Weekly