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. Niņo
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 warmer-than-average (borderline weak El Niņo
and ENSO-neutral) conditions will persist in the equatorial Pacific
through the Northern Hemisphere winter of 2003-2004.
Surface and subsurface temperatures remained warmer than average
across most of the equatorial Pacific Ocean during November. Equatorial
ocean surface temperatures greater than +0.5°C
(~1°F) above average were found
in most areas between Indonesia and the
South American coast (Fig. T9), while
departures greater than +1°C
were found between 150°E and
170°W (Fig. T18).
Positive SST anomalies were observed in all four Niņo
index regions for the second consecutive month (Table
T2). Positive equatorial upper-ocean temperature departures
persisted throughout the equatorial Pacific during November (Figs. T15,
T17). Overall the basin-wide upper ocean heat content was
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, all of the
atmospheric indices typically used to monitor ENSO remained near zero
during November (Table 1), indicating a continuation of ENSO-neutral
atmospheric conditions. 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.
A majority of the statistical and coupled model forecasts indicate
near-average conditions in the equatorial Pacific (Niņo
3.4 SST anomalies between -0.5°C and +0.5°C)
through the Northern Hemisphere 2003-2004 winter (Figs. F1,
F2, F3, F4,
F5, F6, F7,
F8, F9, F10,
F11, F12, F13).
However, some forecasts indicate
weak El Niņo conditions
developing during the winter, which is consistent with observed trends
in SST anomalies in the vicinity of the date line. The three-month
(September-November) average SST anomaly in the Niņo
3.4 region (+0.4°C) is just below the
threshold (+0.5°C) required for NOAA to
declare a weak Pacific warm episode (El Niņo).
It is likely that the October-December 2003 average will reach that
threshold and that borderline weak El Niņo
/ ENSO-neutral conditions will persist through the winter. However, it
seems unlikely that classical El Niņo
conditions will develop along the west coast of South America.
In the past, weak Pacific warm episodes have not shown consistent
temperature and precipitation impacts for areas outside the tropical
Pacific. Therefore, at this time these conditions are not expected to
have any significant impacts on wintertime temperature and precipitation
patterns over the United States.
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: