La Niña persisted during November, as indicated by well below-average sea surface temperatures (SSTs) extending from the Date Line to the eastern Pacific Ocean [Fig. 1]. Most of the weekly indices fluctuated through the month, with the westernmost Niño regions Niño-4 and Niño-3.4 ending up around -1.0°C [Fig. 2]. The negative equatorial subsurface temperature anomalies (averaged from 180°-100°W) weakened slightly last month [Fig. 3], but continued to reflect below-average temperatures from the surface to 200m depth in the eastern Pacific Ocean [Fig. 4]. The atmospheric circulation over the tropical Pacific Ocean remained consistent with La Niña. Over the western and central tropical Pacific Ocean, low-level wind anomalies were easterly and upper-level wind anomalies were westerly. Tropical convection continued to be suppressed from the western Pacific to the Date Line [Fig. 5]. Also, both the Southern Oscillation and Equatorial Southern Oscillation indices were positive. Overall, the coupled ocean-atmosphere system indicates the continuation of La Niña.
A majority of the models in the IRI/CPC plume predict La Niña (Niño-3.4 index less than -0.5°C) to persist through the Northern Hemisphere winter 2020-21 and to weaken through the spring [Fig. 6]. Supported by the latest forecasts from several models, the forecaster consensus is for a moderate strength La Niña (Niño-3.4 index values between -1.0°C and -1.5°C) during the peak November-January season. In summary, La Niña is likely to continue through the Northern Hemisphere winter 2020-21 (~95% chance for January-March), with a potential transition during the spring 2021 (~50% chance of Neutral during Apr-Jun; click CPC/IRI consensus forecast for the chances in each 3-month period).
https://origin.cpc.ncep.noaa.gov/produc ... ONI_v5.php
https://www.cpc.ncep.noaa.gov/products/ ... disc.shtml
