Forecast Forum - March 2004

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.  Niño 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.

Outlook

Based on recent trends and current atmospheric and oceanic conditions, it is likely that ENSO-neutral conditions will continue for the next 3-6 months.

Discussion

Sea surface temperature (SST) anomalies (departures from average) decreased in most of the equatorial Pacific during March (Fig. T9, Table T2). For the month, slightly cooler-than-average SSTs were observed between 150EW and 120EW and near the South American coast, with warmer-than-average conditions being confined to the region west of 180EW (Fig. T18).

Subsurface temperature anomalies were generally positive in the western and central equatorial Pacific and negative in the eastern equatorial Pacific (Fig. T17). This represents a steeper-than-average thermocline slope, which is consistent with stronger-than-average easterly winds over the central equatorial Pacific (Fig. T20).

The monthly 850-hPa zonal wind indices, OLR index, 200-hPa zonal wind index, SOI and EQSOI have exhibited considerable intraseasonal variability since November in association with tropical Madden-Julian Oscillation (MJO) activity (Table T1, Fig. T2). However, certain average atmospheric patterns have prevailed during that period including stronger-than-average easterly winds (Fig. T7) and drier-than-average conditions (Fig. T11) over the central equatorial Pacific. These conditions are consistent with the observed decrease in SST anomalies in the central equatorial Pacific since December 2003 (Table T2, Fig. T9).

A majority of the statistical and coupled model forecasts indicate near-average conditions in the equatorial Pacific (Niño 3.4 SST anomalies between -0.5°C and +0.5°C) through the northern summer 2004 (Figs. F1, F2, F3, F4a, F4b, F5, F6, F7, F8, F9, F10, F11, F12, F13). Thereafter, the forecasts show increasing spread and greater uncertainty. Given the recent trends and observed oceanic and atmospheric patterns discussed above, it is likely that ENSO-neutral conditions will continue for the next 3-6 months.

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: http://www.cpc.ncep.noaa.gov.