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 (CFSv2) 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 from the ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F9.  Niño 3.4 predictions are summarized in Fig. F10, 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 Advisory

 

Outlook:

 

La Niña conditions have developed and are expected to continue with an 87% chance of La Niña in December 2021- February 2022.

 

Discussion:

 

In the past month, La Niña conditions emerged, as indicated by below-average sea surface temperatures (SSTs) across the central and east-central equatorial Pacific (Fig. T18).  Based on ERSSTv5 data, the Niño-3.4 and Niño-4 index values were -0.5ºC.  Below-average subsurface temperatures (averaged from 180-100ºW) strengthened significantly in the past month, as negative anomalies were observed at depth across most of the central and eastern Pacific Ocean (Fig. T17).  Low-level easterly wind anomalies and upper-level westerly wind anomalies were observed over most of the equatorial Pacific (Fig. T20 & T21).  Tropical convection was suppressed near and west of the Date Line and enhanced over Indonesia (Fig. T25), while the Southern Oscillation Index and Equatorial Southern Oscillation Index were both positive (Fig. T1 & T2). Overall, the coupled ocean-atmosphere system was consistent with La Niña conditions.

The IRI/CPC plume average of forecasts for the Niño-3.4 SST index favors La Niña to continue through the fall and winter 2021-22 (Figs. F1-F12).  The forecaster consensus also anticipates La Niña to continue through the winter, with ENSO-neutral predicted to return during March-May 2022.  Because of the recent oceanic cooling and coupling to the atmosphere, forecasters now anticipate a 57% chance of one season (November-January) reaching -1.0ºC or less in the Niño-3.4 index.  Thus, at its peak, a moderate-strength La Niña is favored.  In summary, La Niña conditions have developed and are expected to continue with an 87% chance of La Niña in December 2021- February 2022.

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