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 ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F11.  Niño 3.4 predictions are summarized in Fig. F12, 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: Not Active

 

Outlook:

 

ENSO-neutral is favored during the Northern Hemisphere fall 2019 (~85% chance), continuing through spring 2020 (55-60% chance).

 

Discussion:  

 

Near-average sea surface temperatures (SST) were evident in the east-central Pacific Ocean during most of September, though SST anomalies increased during the past couple of weeks (Fig. T18).  The monthly SST indices in the westernmost Niño-4 and Niño-3.4 regions were +0.6C and 0.0C, respectively, and the indices in the easternmost Niño-3 and Niño-1+2 regions remained near-to-below average (-0.2C and -0.8C respectively; Table T2).  The subsurface temperature anomalies (averaged across 180-100W) increased during the month partially because a downwelling oceanic Kelvin wave expanded eastward (Fig. T17).  This wave was triggered by low-level westerly wind anomalies across the western and central equatorial Pacific Ocean (Fig. T20).  At upper-levels, easterly wind anomalies prevailed over much of the Pacific during September (Fig. T21).  Also, the region of suppressed convection over Indonesia intensified and expanded to the Date Line (Fig. T25).  Despite the recent warming, the overall oceanic and atmospheric system remained consistent with ENSO-neutral. 

The majority of models in the IRI/CPC plume (Figs. F1-F12) continue to favor ENSO-neutral (Niño-3.4 index between -0.5°C and +0.5°C) through the Northern Hemisphere spring.  Many dynamical forecast models, including the NCEP CFSv2, suggest Niño-3.4 SST index values will remain near +0.5°C during the next month or so before decreasing, but remaining above zero.  Consequently, forecasters believe the recent oceanic warmth reflects sub-seasonal variability and is not indicative of an evolution toward El Niño.  However, chances for El Niño remain between approximately 25-30% through the winter and spring.  In summary, ENSO-neutral is favored during the Northern Hemisphere fall 2019 (~85% chance), continuing through spring 2020 (55-60% chance).

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