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.
(El Niņo) conditions are expected to
continue into early 2005.
sea surface temperature (SST) anomalies greater
than +0.5°C (~1°F) persisted across
most of the equatorial Pacific during October 2004 (Table T2, Fig. T18).
Positive equatorial SST anomalies greater than +1°C (~2°F) were
found from 160°E eastward to 150°W.
The increase and eastward expansion of the area of anomalous
warmth in the central equatorial Pacific during July-October (Fig.
T9) indicate the early
stages of a warm (El Niņo)
the end of October conditions were not yet indicative of a
basin-wide El Niņo, particularly due to the presence of below-average
SSTs in the far eastern equatorial Pacific near the South American coast
Through most of 2004 tropical intraseasonal (Madden-Julian Oscillation)
activity has resulted in week-to-week and month-to-month variability in
many atmospheric and oceanic indices.
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).
This activity has been associated with periods of
weaker-than-average easterlies (Fig. T13) that initiated
eastward-propagating oceanic Kelvin waves.
This intraseasonal variability has been superposed on an upward
trend in SST anomalies east of the date line (Table T2, Fig. T5) and a
gradual increase in the upper-ocean heat content during the last year (Fig.
The value of the Oceanic Niņo Index (ONI; 3-month running mean average of SST anomalies in
the Niņo 3.4 region
computed using the Extended Reconstructed SST version-2 data set)
for August-October 2004 is +0.9°C,
which satisfies the NOAA operational definition for El Niņo
for the third 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,
it seems most likely that the ONI will remain positive, at or above +0.5°C,
through early 2005.
global impacts include drier-than-average conditions over
(through early 2005), northern and northeastern
(November 2004-February 2005), and southeastern
(November 2004-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
Ecuador and northern Peru during the first few months of 2005, and
drier-than-average conditions would be expected to develop in the
eastern Amazon late this year and spread to Northeast Brazil during
February through April 2005.
El Niņo wintertime impacts
vary considerably depending on the character (distribution and
intensity) of the warming in the tropical Pacific. Composite impacts for
selected ranges of the ONI for El Niņo episodes since 1950 show that
the areal extent of warmer-than-average (wetter-than-average) conditions
increases across the northern (southern)
, as the strength of El Niņo increases. The current warming in the
tropical Pacific is expected to continue through the upcoming winter,
with models indicating an ONI in the range of +0.5ēC to +1.4ēC (Figs.
F1, F2, F3,
F4a, , F4b, F5,
F6, F7, F8,
F9, F10, F11,
Thus, 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.
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: