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:

 

The chance of El Niño has decreased to about 65% during the Northern Hemisphere fall and early winter.

 

Discussion:  

 

            During July 2014, above-average sea surface temperatures (SST) continued in the far eastern equatorial Pacific, but near average SSTs prevailed in the central and east-central equatorial Pacific (Fig. T18).  Most of the Niño indices decreased with values of +0.3°C in Niño-4, +0.2°C in Niño-3.4, +0.7°C in Niño-3, and +1.4°C in Niño-1+2 (Table T2). Subsurface heat content anomalies (averaged between 180º-100ºW) continued to decrease and are slightly below average.  The above-average subsurface temperatures that were observed near the surface during June (down to 100m depth) are now limited to a thin layer in the top 50m, underlain by mainly below-average temperatures (Fig. T17).  The low-level winds over the tropical Pacific remained near average during July, but westerly wind anomalies appeared in the central and eastern part of the basin toward the end of the month (Fig. T20). Upper-level winds remained generally near average and convection was enhanced mainly just north of the equator in the western Pacific (Fig. T21).  The lack of a coherent atmospheric El Niño pattern, and a return to near-average SSTs in the central Pacific, indicate ENSO-neutral.

Over the last month, model forecasts have slightly delayed the El Niño onset, with most models now indicating the onset during July-September, with the event continuing into early 2015 (Figs. F1-F13).  A strong El Niño is not favored in any of the ensemble averages, and slightly more models call for a weak event rather than a moderate event.  At this time, the consensus of forecasters expects El Niño to emerge during August-October and to peak at weak strength during the late fall and early winter (3-month values of the Niño-3.4 index between 0.5°C and 0.9°C).  The chance of El Niño has decreased to about 65% during the Northern Hemisphere fall and early winter.

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