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 Watch

 

Outlook:

 

La Niña conditions are favored (~55-65%) during the Northern Hemisphere fall and winter 2017-18.

 

Discussion:  

 

During September, ENSO-neutral conditions were reflected in near-to-below average sea surface temperatures (SSTs) across most of the central and eastern Pacific Ocean (Fig. T18).  The weekly Niño indices were volatile during the month (Table T2), with negative values weakening to near zero late in the month in the Niño-4, Niño-3.4, and Niño-3 regions.  In contrast, sub-surface temperature anomalies were increasingly negative during September, reflecting the shallow depth of the thermocline across the central and eastern Pacific (Fig. T17).  Also, convection was suppressed near the International Date Line and enhanced near Indonesia (Fig. T25).  Over the western equatorial Pacific Ocean, low-level trade winds were anomalously easterly and upper-level winds were anomalously westerly (Fig. T20, Fig. T21).  Overall, the ocean and atmosphere system remains consistent with ENSO-neutral, although edging closer to La Niña conditions. 

For the upcoming Northern Hemisphere fall and winter 2017-18, a weak La Niña is favored in the dynamical model averages of the IRI/CPC plume and North American Multi-Model Ensemble (NMME) (Figs. F1-F13).  Several models indicate a period of near-average Niño-3.4 values in the upcoming weeks, but then predict reinvigorated growth of negative SST anomalies across the equatorial Pacific Ocean.  These forecasts are supported by the ongoing easterly wind anomalies across portions of the Pacific Ocean and the reservoir of below-average subsurface temperatures.  In summary, La Niña conditions are favored (~55-65%) during the Northern Hemisphere fall and winter 2017-18.

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