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
. The predictions from the National Centers for
Environmental Prediction (NCEP) Coupled Forecast System Model (CFS03) are
presented in Figs. F3 and F4a,
from the Markov model (Xue, et al. 2000: J. Climate, 13,
849‑871) are shown in Figs. F5 and F6.
Predictions from the latest version of the LDEO model (Chen 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 and
Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in
Niño 3.4 predictions are summarized in Fig. F13,
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.
A transition from weak warm-episode (El Niño) conditions to ENSO-neutral
conditions is expected during the next three months.
Sea surface temperature (SST)
anomalies increased in the Niño 3.4 and Niño 3 regions during March 2005 (Table
T2). Positive SST anomalies greater than
+1.0°C were observed in portions of the central and west central equatorial
Pacific between 165°E and 165°W (Fig. T18).
Cloudiness and precipitation returned to near average over Indonesia (Fig.
T25), while the enhanced precipitation,
observed over the central tropical Pacific in February, weakened and
drier-than-average conditions developed over that region (Fig. T11).
The increase in SST anomalies and upper-ocean
heat content (Fig. T15) in the east-central
equatorial Pacific during the last half of March was associated with an
eastward-propagating oceanic Kelvin wave (downwelling phase) (Fig. T17).
This wave is stronger than those that have occurred in recent months in
association with MJO activity. Surface and subsurface ocean temperatures are
expected to increase along the west coast of South America (Ecuador and
northern Peru) during April 2005. However, substantial cooling in the upper
ocean has occurred in the wake (upwelling phase) of this Kelvin wave (Fig.
T17), accompanied by a strengthening of the
easterly winds over the central and western equatorial Pacific during March (Fig.
T20). This cooling is expected to propagate
eastward, eventually reaching the eastern equatorial Pacific during May.
Thus, the effects of the expected warming along the west coast of South
America during April should be brief.
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
January-March 2005 is +0.5°C, which satisfies the NOAA operational
definition of El Niño. However, a majority of the statistical and coupled
model forecasts (Figs. F1,
F2, F3, F4a,
F4b, F5, F6,
F7, F8, F9,
F10, F11, F12
indicate that a transition from weak warm-episode (El Niño) conditions to
ENSO -neutral conditions will continue during the next three months, and that
ENSO-neutral conditions will likely prevail during the northern summer.
updates of SST, 850-hPa wind, OLR and features of the equatorial subsurface
thermal structure are available on the