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 observed oceanic and atmospheric conditions and the
SST predictions, warm episode (El Niño)
conditions are expected to continue through the spring of 2003.
Further evolution toward basin-wide mature El Niño
conditions occurred during October. SST anomalies (departures from
average) were greater than +1°C throughout most of the equatorial
Pacific between 180°W and the South American coast during the month (Fig.
T18), and positive subsurface temperature departures (Fig.
T17) and a deeper-than-average oceanic thermocline (Figs. T15
and T16) prevailed throughout most of the
The current warm episode has also exhibited a number of typical
atmospheric features in recent months. The Southern Oscillation Index
(SOI) has been consistently negative since March 2002 (Table
T1), and weaker-than-average low-level easterly winds have
been observed throughout the tropical Pacific since May 2002 (Fig.
T7). Consistent with this, there has been a reversal of the
east-west Walker circulation in the Pacific-Indonesian sector, with
mean descending air motion over Indonesia and ascending air motion
over the central and east-central equatorial Pacific (Fig.
T29). During October the anomalous circulation in the tropical
Pacific was accompanied by wetter-than-average conditions over the
tropical Pacific, especially in the vicinity of the date line
(180°W), and drier-than-average conditions over Indonesia (Figs. E3
and E4). These oceanic and atmospheric
features indicate the presence of El Niņo.
Most coupled model and statistical model forecasts indicate that El
Niņo conditions will continue into the spring of 2003 (Figs. F1,
F2, F3, F4,
F5, F6, F7,
F8, F9, F10,
Thereafter the forecasts are more uncertain, during a time of the year
when all of the techniques have difficulty in making skillful
forecasts. Based on the recent evolution of conditions in the tropical
Pacific, we expect SST anomalies to increase further in the eastern
equatorial Pacific (Niņo 3 and Niņo 1+2 regions), with the
establishment of basin-wide mature El Niņo conditions during December
2002-February 2003. Furthermore, based on the latest predictions and
an assessment of current oceanic and atmospheric conditions, we expect
that this event will be weaker than the 1997-98 El Niņo. Thus, the
global impacts should generally be weaker than those observed during
1997-98. However, strong impacts are still possible in a few
Expected global impacts include: 1) drier-than-average over
Indonesia and eastern Australia continuing during the next several
months, 2) wetter-than-average over southeastern South America
(Uruguay, northeastern Argentina, and southern Brazil) during the next
three months, 3) drier-than-average over southeastern Africa during
December 2002-February 2003, 4) drier-than-average over Northeast
Brazil and northern South America during December 2002-April 2003, and
4) wetter-than-average conditions over coastal sections of Ecuador and
northern Peru during December2002-April 2003. Over the United States
and Canada we expect: 1) drier-than-average conditions in the Ohio
Valley states and northern Rockies during winter 2002-2003, 2)
wetter-than-average conditions along much of the southern tier of the
U.S. during winter 2002-2003, and 3) warmer-than-average conditions in
the northern tier states, southern and southeastern Alaska, and
western and central Canada during late fall 2002 and winter 2002-2003.
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).