La Nina 2020-21 Is Now Past Peak Intensity

Highlight: La Nina 2020-21 is now past peak intensity.

Fig. 1: The 12-week Nino SSTA observations reveal La Nina has likely peaked.

Discussion: La Nina 2020-21 has likely peaked (Fig. 1). Subsurface water is not quite as cool as 1-2 months ago (Fig. 2). However, the subsurface cool water in the eastern half of the equatorial Pacific is broader and therefore plenty of fuel remains to sustain La Nina well into 2021. During November the Pacific decadal oscillation (PDO) strengthened to -1.2 which is well-coupled to mature La Nina. The NOAA/CPC consolidated ENSO phase outlook using Nino34 SSTA indicates weakening La Nina the first 3-5 month of 2021 and neutral phase by northern hemisphere summer (Fig. 3).

Fig. 2: The subsurface equatorial Pacific Ocean water is plenty cool to sustain La Nina although the strength of the anomalies has diminished.

Fig. 3: The NOAA/CPC consolidation Nino34 SSTA forecast indicates La Nina weakens the first half of 2021.