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 ENSO-neutral
to La Niña conditions is possible during the next 1-3 months.
The pattern of anomalous sea surface temperatures
(SSTs) during May 2007 was consistent with ENSO-neutral conditions in the
tropical Pacific, with average to below-average SSTs extending from the date
line to the west coast of
(Fig. T18). The
latest SST departures are negative in the Niño 1+2 (-1.6ºC) and Niño 3
(-0.7 ºC) regions, and remain near zero in the Niño 3.4 (-0.2 ºC) and Niño
4 (+0.2 ºC) regions (Table T2).
An area of anomalously warm SSTs persisted well west of the
date line (near 150ºE) (Fig. T18).
The equatorial upper-ocean
heat content (average temperature departures in the upper 300 m of the ocean)
remained below-average across the central and east-central equatorial
Pacific, with temperatures at thermocline depth ranging from 1°- 4°C below
Consistent with the surface and sub-surface temperature patterns,
stronger than-average low-level easterly winds persisted over the central
equatorial Pacific (Figs. T7 and T20),
and convection was enhanced over the western equatorial Pacific and
suppressed east of the date line (Fig. T25).
Collectively, these atmospheric and oceanic conditions continue to indicate that La Niña conditions could develop over the next 1-3 months.
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 March – May 2007 is -0.1°C, which reflects ENSO-neutral
conditions in the tropical Pacific. Nearly all of the model forecasts predict below-average
SSTs in the Niño 3.4 region
the remainder of the year (Figs. F1,
F2, F3, F4a,
F4b, F5, F6,
F7, F8, F9,
F10, F11, F12
and F13). Most statistical models show ENSO-neutral
conditions persisting through August 2007, while most dynamical models
indicate La Niña will develop within the next three months. Some
forecast models, especially the NCEP Climate Forecast System (CFS), continue
to predict a rapid transition to La Niña conditions. However, for the
past few months the CFS forecasts have been predicting a stronger and more
rapid cooling than has actually occurred. Historically, the next few
months are a favorable period for the development of La Niña.
updates of SST, 850-hPa wind, OLR and features of the equatorial subsurface
thermal structure are available on the
Center homepage at: