Forecast Forum

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 Forecast System Model (CFS03) are presented in Figs. F3 and F4a, F4b.  Predictions from the Markov model (Xue, et al. 2000: J. Climate, 13, 849‑871) are shown in Figs. F5 and F6.   Predictions from the latest version of the LDEO model (Chen 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 and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F12.  Niño 3.4 predictions are summarized in Fig. F13, 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.

 

ENSO Alert System Status:  La Niña Advisory

 

Outlook:

 

La Niña is expected to transition to ENSO-neutral conditions during April 2012.

 

Discussion:  

 

La Niña continued to weaken during March 2012, as below-average SSTs persisted primarily in the central Pacific (Fig. T18). All of the Niño indices have warmed during the last two months, and the Niño 4 and Niño 3.4 indices were near -0.5 in March (Table T2). The oceanic heat content (average temperature in the upper 300m of ocean) anomalies also continued to warm, with alternating pockets of negative and positive temperature anomalies observed within the upper 100 m in the central and eastern Pacific (Fig. T17). Significant anomalous low-level westerly winds developed in the western tropical Pacific in late March, associated with the MJO. This wind event could further warm the central and eastern Pacific within the coming few months. Presently, however, the larger scale atmospheric circulation anomalies and the Southern Oscillation Index retain their La Niña characteristics (Fig. T1). Accordingly, convection remains suppressed in the western and central Pacific, and enhanced over Indonisia, Malaysia and the Philippines (Fig. T25). Collectively, these oceanic and atmospheric patterns indicate that a transition from La Niña to ENSO-neutral conditions is underway.

A majority of models predict ENSO-neutral conditions for March-May 2012, continuing through the Northern Hemisphere summer 2012 (Figs. F1-F13).  Based on the continued weakening of the negative SST anomalies during March 2012, and on the historical tendency for La Niña to dissipate during the Northern Hemisphere spring, we continue to expect La Niña to dissipate during April 2012. ENSO-neutral conditions are then expected to persist through the summer. Thereafter, there is considerable uncertainty in the forecast, which slightly favors ENSO-neutral or developing El Niño conditions over a return to La Niña conditions during the remainder of 2012

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