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 ~65% chance of ENSO-neutral during Northern Hemisphere summer 2020, with chances decreasing through the autumn (to 45-50%). 

 

Discussion:  

 

During April 2020, positive sea surface temperature (SST) anomalies weakened and were near zero by the end of the month (Fig. T18).  Most of the Niño indices decreased, with monthly index values around +0.5°C in the Niño-3.4 and 3 regions (Table T2).  Equatorial subsurface temperatures (averaged across 180°-100°W) declined further and were below average, due to the eastward expansion of below-average subsurface temperatures into the eastern Pacific (Fig. T17).  Also during the month, low-level wind anomalies were easterly across the central and east-central Pacific (Fig. T20), while upper-level wind anomalies were westerly over the central and eastern portions of the basin (Fig. T21).  Tropical convection was near average around Indonesia and suppressed over the Date Line (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 autumn, though considerable spread is evident at longer lead times. Niño 3.4 index values are expected to decrease through the remainder of the Northern Hemisphere spring and into the summer; with the possibility of below-average temperatures becoming more established toward the latter half of the year.  The consensus of forecasters favors ENSO-neutral conditions through the summer and fall, and slightly tilts toward La Niña at the end of the year (~45% chance). There is a ~10% chance of El Niño from the summer through the end the year. In summary, there is a ~65% chance of ENSO-neutral during Northern Hemisphere summer 2020, with chances decreasing through the autumn (45-50%).

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