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 continue through the remainder of
the NH winter and into the spring of 2001 followed by a return to near-normal conditions
during the summer of 2001.
Cold episode conditions continued in the tropical Pacific during December, as sea
surface temperatures (SSTs) remained well below normal across the central and east-central
equatorial Pacific (Fig. T18 and Table T2).
Below-normal subsurface temperatures continue to dominate the eastern equatorial Pacific
while above normal subsurface temperatures dominate the western Pacific (Fig. T17). Tropical convection during December (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 the
Phillippines, portions of Indonesia and northern Australia (Fig.
T25). Consistent with these conditions, the mean low-level equatorial easterly
winds remained stronger-than-normal over the western and central tropical Pacific and near
normal over the eastern Pacific (Fig. T20). The patterns
of tropical convection and low-evel winds have been strongly influenced by tropical
intraseasonal (Madden-Julian Oscillation) activity (Fig. T11),
which has been present since June 2000 (Fig. T12).
As in previous months, a notable feature of the current oceanic conditions is the lack
of evolution of the subsurface thermal structure in the tropical Pacific 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 be present through the remainder of
the NH winter and into the spring of 2001. This assessment is generally supported by the
most recent NCEP statistical and coupled model forecasts (Figs. F1, F2, F3, F4), as well as by other available coupled model and
statistical model predictions (Figs. F5, F6,
F7, F8) that indicate a gradual
weakening of cold episode conditions in the tropical Pacific through the remainder of the
NH winter, followed by near-normal SSTs during the spring of 2001. However, over the past
several months the forecast tools have weakened cold episode conditions more rapidly than
has been observed.
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 average conditions to prevail over Indonesia, northern Australia, and
southern Africa during the remainder of the NH winter. Over North America
warmer-than-normal average conditions are expected along the southern tier of the United
States from southern California eastward to Florida. Cooler-than-normal average conditions
are likely over western and central Canada and in the upper Midwest and Great Lakes.
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