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:  El Niño Watch

 

Outlook:

 

Borderline ENSO-neutral/ weak El Niño conditions are expected to continue into Northern Hemisphere winter 2012-13, possibly strengthening during the next few months.

 

Discussion:  

 

During September 2012, the trend towards El Niño slowed in several key oceanic and atmospheric indicators.  However, the Pacific basin reflects borderline ENSO-neutral/ weak El Niño conditions.   Equatorial sea surface temperatures (SST) remained elevated across the Pacific Ocean (Fig. T18), although anomalies decreased during the month in the Niño-3 and Niño-3.4  regions (Table T2).  The oceanic heat content (average temperature in the upper 300m of the ocean) anomalies also weakened, but continued to show large regions of above-average temperatures at depth across the equatorial Pacific (Fig. T17).  Interestingly, low-level westerly wind anomalies were evident over the equatorial western Pacific Ocean (Fig. T20), which may portend possible strengthening of the subsurface anomalies in the coming months.  Despite these winds, the atmosphere was still largely ENSO-neutral, as reflected by the Southern Oscillation index (Table T1) and near-average upper-level and lower-level winds across much of the Pacific (Figs. T20 and T21).  Tropical convection increased near the Date Line, which is consistent with weak El Niño conditions, but also remained elevated over eastern Indonesia, which is further westward than expected (Fig. T25).  Thus, the atmosphere and ocean indicate borderline ENSO-neutral/ weak El Niño conditions.  

Compared to the past few months, the chance is reduced for El Niño to develop during Northern Hemisphere fall/winter 2012-13. Due to the recent slowdown in the development of El Nino, it is not clear whether a fully coupled El Niño will emerge. The majority of models indicate that borderline ENSO-neutral/ weak El Niño conditions will continue, and about half suggest that El Niño could develop, but remain weak (Figs. F1-F13).  The official forecast therefore favors the continuation of borderline ENSO-neutral/ weak El Niño conditions into Northern Hemisphere winter 2012-13, with the possibility of strengthening during the next few months.

Weekly updates of oceanic and atmospheric conditions are available on the Climate Prediction Center homepage (El Niño/La Niña Current Conditions and Expert Discussions).