ENSO Tracker - Apr 2022

ENSO Tracker - Apr 2022

Sea surface temperature (SST) forecasts for May  – Jul 2022 still indicate cool conditions across most of the equatorial Pacific (Fig. 1). Current 3.4/4 anomalies are still below the La Niña threshold (Fig. 2), and while most ENSO outlooks generally call for La Niña conditions to last into summer, there are now some indications in outlooks of a continuation of La Niña into Fall 2022, although there is considerable uncertainty in models and forecasts during the so-called spring (predictability barrier).

Forecast Roundup: On Apr 12 the Australian Bureau of Meteorology ENSO outlook stated, “Atmospheric and oceanic indicators persist at La Niña levels”, but called for a likely return to neutral conditions. On Apr 11 the Japanese Meteorological Agency (JMA) observed La Niña conditions had a 60-percent chance to continue through the end of spring, and a 70-percent chance of ENSO-neutral by summer. On Apr 14 the NOAA Climate Prediction Center (CPC) maintained their “La Niña Advisory” noting “the coupled ocean-atmosphere system reflected the continuation of La Niña” and called for a 59-percent chance of La Niña lasting through the Jun-Aug period, and a 50-55-percent chance of La Niña lasting through Fall 2022. On Apr 14 the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), noting “Sea Surface Temperatures remain below-average (strengthening slightly) in the central-eastern equatorial Pacific” but noted “slight disagreement between the two forecast methods on the dissipation of the current event”, and highlighted nearly equal chances of La Niña or ENSO-Neutral conditions in the ‘subjective’ (forecaster consensus) outlook. The North American Multi-Model Ensemble (solid and dashed black line, Fig. 4) remains in La Niña territory, and in a shift from previous months, now shows persistence of La Nina conditions into Fall 2022.

Summary: Last month, most outlooks called for a gradual transition out of La Niña over summer, but this month, some outlooks shifted to the possibility of La Nina extending into Fall 2022. If La Niña does persist through summer, the impact on spring and summer is less consistent or predictable, given the inherent variability and volatility of the monsoon, and limited sample size of ENSO events that persist over the summer period.