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 is 70% during the Northern Hemisphere summer and reaches 80% during the fall and winter.

 

Discussion:  

 

            Above-average sea surface temperatures (SST) expanded over the equatorial Pacific Ocean during May 2014 (Fig. T18), though the collective atmospheric and oceanic state continued to reflect ENSO-neutral.  All of the Niño indices increased during the month, with the monthly values between 0.5°C and 1.3°C (Table T2).  In contrast, subsurface temperature anomalies decreased over the last two months, but still reflect a large pool of above-average temperatures at depth (Fig. T17).  The low-level winds over the tropical Pacific remain near average, except for westerly anomalies over the eastern Pacific (Fig. T20). At upper-levels, anomalous easterly winds have predominated over most of the equatorial Pacific (Fig. T21).  Unlike the previous month, convection was near average across most of the tropics (Fig. T25).  The lack of a clear atmospheric response to the positive SSTs indicates ENSO-neutral, though the tropical Pacific continues to evolve toward El Niño. 

Over the last month, the chance of El Niño and its ultimate strength weakened slightly in the models (Figs. F1-F13).  Regardless, the forecasters remain just as confident that El Niño is likely to emerge.  If El Niño forms, the forecasters and most dynamical models, such as NCEP CFSv2, slightly favor a moderate-strength event during the Northern Hemisphere fall or winter (3-month values of the Niño-3.4 index between 1.0°C and 1.4°C).  However, significant uncertainty accompanies this prediction, which remains inclusive of a weaker or stronger event due to the spread of the models and their skill at these lead times.  Overall, the chance of El Niño is 70% during the Northern Hemisphere summer and reaches 80% during the fall and 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).