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.
(El Niño) conditions are expected to
continue for the next three months.
sea surface temperature (SST) anomalies greater
than +0.5°C (~1°F) persisted across
most of the central and western equatorial Pacific during December 2004
T2, Fig. T18).
Positive equatorial SST anomalies greater than +1°C (~2°F) were
found from 160°E eastward to 155°W (Fig.
T18). During December
SST anomalies exceeded 0.5°C in the Niño
4, Niño 3.4 and Niño
3 regions, while anomalies remained near zero along the West Coast of
South America (Niño 1+2 region) (Table
T2). The pattern of anomalous warmth in the equatorial Pacific in
recent months (Fig. T9) and the most recent 5-month running mean
values of the Southern Oscillation Index (Fig. T1) indicate that
a weak warm (mid-Pacific El Niño)
episode has developed. However, through December 2004 there has been a
lack of persistent enhanced
convection over the anomalously warm waters of the central equatorial
Pacific (Figs. T8 and T25), which has limited El Niño-related
impacts on the global pattern of precipitation.
late 2003 tropical intraseasonal (Madden-Julian Oscillation) activity
has resulted in week-to-week and month-to-month variability in many
atmospheric and oceanic indices (Tables
T1 and T2). In
the past few months the warmth in the central equatorial Pacific has
supported eastward shifts of enhanced convection associated with the
convectively active phase of the MJO across the western equatorial
Pacific (Figs. T11 and T12).
The MJO activity weakened considerably during early
November 2004 and remained weak through mid-December.
However, during the last half of December the MJO strengthened,
as enhanced convection and precipitation over the Indian Ocean shifted
. By early January 2005,
enhanced convection extended into the western tropical Pacific. The
will continue to closely monitor the evolution of this activity over the
next several weeks as it shifts eastward over the abnormally warm waters
in the central equatorial Pacific.
The value of the Oceanic Niño
Index (ONI; 3-month running mean average of SST anomalies in the Niño
3.4 region – computed using the Extended Reconstructed SST version-2
data set) for October-December 2004 is +0.9°C,
which satisfies the NOAA operational definition of El Niño for the fifth consecutive month. Based on the recent
evolution of oceanic and atmospheric conditions and on a majority of the
statistical and coupled model forecasts (Figs.
F1, F2, F3,
F4a, F4b, F5,
F6, F7, F8,
F9, F10, F11,
F12 and F13), it seems most likely that warm (mid-Pacific El Niño)
episode conditions will persist for at least the next three months.
However, there is considerable uncertainty concerning future
developments in the extreme eastern equatorial Pacific (the classical El
Expected global impacts
include drier-than-average conditions over portions of
(through early 2005), northern and northeastern
(through February 2005), and southeastern
(through March 2005). If the warming in the tropical Pacific strengthens
and spreads eastward to the South American coast, then
wetter-than-average conditions would be expected in coastal sections of
during March-April 2005, and drier-than-average conditions would be
expected to develop in
during February through April 2005. Expected
impacts during Northern Hemisphere winter include warmer-than-average
conditions in the West and in the northern Plains, and cooler- and
wetter-than-average conditions for portions of the South and Southeast.
(Note: The recent pattern of heavy precipitation in California
during December 2004 and early January 2005 was associated with 1)
persistent high-latitude blocking in the vicinity of the Gulf of Alaska
and an associated trough along the West Coast, and 2) a weaker than
average jetstream across the central and eastern Pacific. These
circulation features are not consistent with El Niño,
which would favor a stronger-than-average jetstream over the central and
eastern Pacific and a
reduced tendency for blocking in the
Gulf of Alaska
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: