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:

 

There is a ~60% chance of ENSO-neutral during Northern Hemisphere summer 2020, with roughly equal chances (~40-50%) of La Niña or ENSO-neutral during the autumn and winter 2020-21.

 

Discussion:  

 

During May 2020, sea surface temperature (SST) anomalies were near-to-below average across the east-central and eastern equatorial Pacific (Fig. T18).  All of the Niño indices decreased during the month, and the latest monthly Niño-3.4 index value was -0.2°C (Table T2).  Equatorial subsurface temperature anomalies (averaged across 180°-100°W) decreased further during the first half of the month, but rebounded slightly toward the end of the month.  However, below-average subsurface temperatures prevailed east of the Date Line (Fig. T17).  Also during the month, low-level wind anomalies were easterly across the east-central Pacific (Fig. T20), while upper-level wind anomalies were westerly over the central Pacific (Fig. T21).  Tropical convection departures were weak, but were enhanced near Indonesia and suppressed over the Date Line and west-central Pacific (Fig. T25). Overall, the combined oceanic and atmospheric system remained consistent with ENSO-neutral.

The majority of models in the IRI/CPC plume (Figs. F1-F12) favor ENSO-neutral (Niño-3.4 index between -0.5°C and +0.5°C) through the Northern Hemisphere winter.  The forecaster consensus also favors ENSO-neutral during the summer, but then chances become roughly split between La Niña and ENSO-neutral beginning with the August-October season.  That consensus mostly reflects the dynamical model guidance, which leans toward La Niña, along with ocean conditions that are somewhat favorable for the development of La Niña.  However, enough uncertainty remains that the chance of La Niña remains lower than 50%, and it is unclear whether oceanic and atmospheric anomalies will lock in and persist.  In summary, there is a ~60% chance of ENSO-neutral during Northern Hemisphere summer 2020, with roughly equal chances of La Niña or ENSO-neutral (~40-50%) during the autumn and winter 2020-21.

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