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 recent trends and current atmospheric and
oceanic conditions, it is likely that ENSO-neutral conditions will
continue for the next 3 months.
Sea surface temperature (SST) anomalies (departures from average)
increased in the central equatorial Pacific, and decreased in the
eastern equatorial Pacific during April 2004 (Fig.
T9, Table T2)
as the equatorial cold tongue strengthened.
For the month, cooler-than-average SSTs were observed between 150EW
and the South American coast, with warmer-than-average conditions
generally being confined to the region west of 180EW
(Fig. T18). Equatorial
subsurface temperatures were above
average in the western and central Pacific and below average in the
eastern equatorial Pacific during April (Fig. T17). This pattern
represents a steeper-than-average thermocline slope in the central
equatorial Pacific, which is consistent with the stronger-than-average
easterly winds (Figs. T13, T20) and above normal precipitation (Figs.
T25, E3) observed over that region.
Slightly more than half of
the statistical and coupled model forecasts indicate near neutral
conditions in the tropical Pacific (Niņo 3.4 SST anomalies between
-0.5°C and +0.5°C) through the northern summer and early
fall 2004 (Figs. F1, F2,
F3, F4a, F4b, F5,
F6, F7, F8,
F9, F10, F11,
F12, F13). The
remaining forecasts indicate that El Niņo will develop during the next
3-6 months and intensify through the end of the year.
Many oceanic and atmospheric
indices have displayed considerable intraseasonal variability related to
Madden-Julian Oscillation (MJO) activity during the last several months
(Table T1), which together with the time of year, may be
contributing to the diversity of statistical and coupled model forecasts
for the tropical Pacific. Given the recent trends and observed oceanic
and atmospheric patterns discussed above, it is more likely that ENSO-neutral
conditions will continue for the next 3 months (through July 2004).
There is considerable uncertainty about what will happen after July
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: