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 F4a, F4b. Predictions from the Markov model (Xue,
Y. et al. 2000: ENSO prediction with Markov model: The impact of sea level. J. Climate,
13, 849-871) are shown in Figs. F5 and F6.
Predictions from the latest version of the LDEO model (Chen,
D. et al. 2000, Geophys. Res. Let., 27,
2585-2587) 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. Predictions from the ENSO-CLIPER statistical model
(Knaff, J. A. and C. W. Landsea 1997, Wea. Forecasting, 12, 633-652) are
shown in Fig. F12. Niño
3.4 predictions are summarized in F13,
which is provided by the Forecasting
and Prediction Research Group of the IRI.
The CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
Based on current conditions and recent observed
trends, it is likely that slightly warmer-than-average conditions will
persist in the equatorial Pacific into the Northern Hemisphere early
Surface and subsurface temperatures remained warmer than average
across most of the equatorial Pacific Ocean during December. Equatorial
ocean surface temperatures more than +0.5°C
(~1°F) above average were found
in many areas between Indonesia and the
South American coast (Fig. T9), while
departures greater than +1°C
were found between 160°E and
180°W (Fig. T18).
Positive SST anomalies were observed in all four Niño
index regions for the third consecutive month (Table
T2). Positive equatorial upper-ocean temperature departures
persisted throughout the equatorial Pacific during December (Figs. T15,
T17). Overall the basin-wide upper ocean heat content was
slightly greater than average during the month (Fig. T17).
At the moment there are no discernable impacts from the anomalously
warm waters on the atmospheric circulation. In fact, none of the
atmospheric indices typically used to monitor ENSO reflect warm episode
conditions (Table T1). Over the past few months, these
atmospheric indices have not shown any significant trends that would
support either additional large-scale increases or any substantial
decreases of SST anomalies in the equatorial Pacific. However, many of
these indices have exhibited considerable week-to-week variability
during late November and December in response to tropical intraseasonal
(Madden-Julian Oscillation) activity. Wetter-than-average conditions,
observed over the Indian Ocean in late November, shifted eastward to the
western Pacific by late December (Fig. T11). At the same time,
the equatorial easterlies weakened over the western Pacific and westerly
anomalies developed in that region (Fig. T13). NOAA’s Climate
Prediction Center will continue to monitor these features to determine
what, if any, impacts this activity will have on surface and subsurface
temperatures in the region between the date line and the South American
A majority of the statistical and coupled model forecasts indicate
near-average conditions in the equatorial Pacific (Niño
3.4 SST anomalies between -0.5°C and +0.5°C)
through the early Northern Hemisphere spring 2004 (Figs. F1,
F2, F3, F4,
F5, F6, F7,
F8, F9, F10,
F11, F12, F13).
However, some forecasts indicate weak El Niño
conditions developing during the winter and intensifying thereafter. The
three-month (October-December) average SST anomaly in the Niño
3.4 region (+0.5°C) is at the threshold
(+0.5°C) required for NOAA to declare a
weak Pacific warm episode (El Niño).
However, the SST indices all decreased slightly during December and the
atmospheric indices do not currently reflect warm episode conditions.
Based on current conditions and recent observed trends, it is likely
that slightly warmer-than-average conditions will persist in the
equatorial Pacific into the Northern Hemisphere early spring 2004. These
conditions are not expected to have any significant impacts on
winter/early spring temperature and precipitation patterns over the
Weekly updates of SST, 850-hPa wind, OLR and features of the
equatorial subsurface thermal structure are available on the Climate
Prediction Center homepage at: