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 most likely that near neutral conditions will occur in the
tropical Pacific during the last half of 2003.
Oceanic and atmospheric conditions in the tropical Pacific were
consistent with ENSO-neutral conditions during July 2003. Equatorial
sea-surface temperature anomalies greater than +0.5°C
persisted in the region west of the date line, while negative anomalies
remained in the far eastern Pacific, near the South American coast (Figs.
T9, T18). During
July there was very little net change in the SST anomalies in the Niņo
regions (Fig. T5, Table
Since late May positive equatorial upper-ocean temperature departures
have spread eastward into the central and eastern Pacific (Figs. T15,
T17). This evolving subsurface pattern is
associated with an eastward propagating oceanic Kelvin wave, resulting
from a period of weaker-than-average easterlies in the central
equatorial Pacific that occurred during late May and early June (Fig.
T13). SST anomalies in the Niņo
3.4 and Niņo 3 regions
increased during early-June through early July, but then decreased
during the last half of July, as the equatorial easterlies strengthened.
Some atmospheric indices, such as the Tahiti-Darwin SOI, and central
Pacific low-level (850-hPa) zonal wind and OLR, have displayed
considerable month-to-month variability and no consistent trend towards
either La Niņa or El Niņo
since May 2003 (Table T1).
A majority of the statistical and coupled model forecasts indicate
near neutral conditions (Niņo
3.4 SST anomalies between -0.5°C and +0.5°C)
through early 2004 (Figs. F1,
F4a, F4b, F5, F6, F7,
F8, F9, F10,
F11, F12, F13).
This is consistent with current conditions and the lack of any
consistent trend in the oceanic and atmospheric indices.
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: