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., A. Leetmaa,
and M. Ji, 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., M. A. Cane, S.
E. Zebiak, Rafael Canizares and A. Kaplan, 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.
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 the recent evolution of conditions in the tropical Pacific
and on coupled model and statistical model forecasts, basin-wide warm
(El Niņo) episode
conditions are expected to continue through the northern spring of
Warm episode (El Niņo)
conditions dominated the tropical Pacific during December 2002.
Equatorial SST anomalies were greater than +1°C
throughout most of the Pacific between the date line and the South
American coast, and exceeded +2°C
at several locations between 175°W
and 100°W (Fig. T18).
Positive subsurface temperature departures (Fig. T17) and a
deeper-than-average oceanic thermocline (Figs. T15 and
prevailed throughout the equatorial Pacific east of 180°W.
Negative subsurface temperature departures were
observed west of 180°W
at a depth of between 100 and 150 m. This dipole pattern is a
typical feature observed during the mature phase of El Niņo.
Atmospheric indicators of El Niņo
include consistently negative values of the Tahiti-Darwin Southern
Oscillation Index (SOI) since March 2002 (Table T1), and
weaker-than-average low-level easterly winds since May 2002 throughout
the equatorial Pacific (Table T1, Fig. T7). Values of
atmospheric and oceanic indices such as the SOI, 850-hPa zonal wind
index, and NiZo 3.4 SST
index are all considerably less in magnitude than those observed
during the 1997-98 El Niņo
(Figs T1, T2, T3,
T4, and T5). Recent impacts of the current El
include: drier-than-average conditions over Indonesia, eastern
Australia, Central America and northeastern South America and
wetter-than-average conditions over the central equatorial Pacific,
southeastern South America and the southeastern United States (Figs.
E3, E4, E5 and
T25). Most coupled model and statistical model
forecasts indicate that El Niņo conditions will continue through the
northern spring of 2003 (Figs. F1, F2,
F3, F4, F5,
F6, F7, F8,
F9, F10, F11,
F12). Thereafter the
forecasts are more uncertain, during a time of the year when all of
the techniques have difficulty in making skillful forecasts.
Historically, most of the techniques have demonstrated more skill in
forecasting the onset of El Niņo
episodes than in forecasting their demise. A critical factor governing
the duration of the current warm episode is the rate of evolution of
the dipole pattern in the subsurface thermal structure along the
equatorial Pacific, which is linked to the persistence and eastward
extension of the pattern of deep convection into the eastern Pacific
and persistence of low-level westerly zonal wind anomalies. The
Climate Prediction Center will continue to monitor these features over
the next few months.
Expected global impacts of the warm episode include: 1)
drier-than-average over Indonesia and eastern Australia continuing
during the next several months, 2) drier-than-average over
southeastern Africa during January-March 2003, 3) drier-than-average
over Northeast Brazil and northern South America during January-April
2003, and 4) wetter-than-average conditions over coastal sections of
Ecuador and northern Peru during February-April 2003. Over the United
States and Canada, during the remainder of the northern winter,
expected conditions include: 1) drier-than-average in the Ohio Valley
states and northern U.S. Rockies, 2) wetter-than-average along much of
the southern tier of the U.S., and 3) warmer-than-average in the
northern tier states, southern and southeastern Alaska, and western
and central Canada.
Weekly updates of SST, 850-hPa wind, OLR, and the equatorial subsurface temperature
structure are available on the Climate Prediction Center homepage at:
http://www.cpc.ncep.noaa.gov (Weekly Update).