Click here to read the discussion and for the figures:
CLIMATE PREDICTION CENTER/NCEP/NWS
and the International Research Institute for Climate and Society 12 August 2021
ENSO Alert System Status: La Niña Watch
Synopsis: ENSO-neutral is favored for the remainder of summer (~60% chance in the July- September season), with La Niña possibly emerging during the August-October season and lasting through the 2021-22 winter (~70% chance during November-January).
Recently, sea surface temperatures (SSTs) were near-to-below average in the central and east- central equatorial Pacific, with above-average SSTs in the far eastern Pacific. In the last week, most Niño indices were slightly negative (-0.2oC to -0.3oC) except for the Niño-1+2 index, which was +0.7oC. Subsurface temperatures cooled considerably in July, becoming quite negative (averaged from 180-100oW, reflecting the emergence of below-average subsurface temperatures east of the DateLine. Low- level wind anomalies were easterly over the east-central Pacific Ocean, while upper-level wind anomalies were westerly across the eastern Pacific. Tropical convection was suppressed over the western Pacific Ocean and enhanced over a small region near Indonesia. Given the surface conditions, the ocean-atmosphere system reflected ENSO-neutral.
Compared to last month, forecasts from the IRI/CPC plume are generally cooler in the Niño-3.4 SST region during the fall and winter 2021-22. Recent model runs from the NCEPCFSv2 and the North American Multi-Model Ensemble suggest the onset of a weak La Niña in the coming months, persisting through winter 2021-22. The forecaster consensus continues to favor these models, which is also supported by the noticeable decrease in the observed subsurface temperature anomalies this past month. In summary,ENSO-neutral is favored for the remainder of summer(~60% chance in the July-September season), with La Niña possibly emerging during the August-October season and lasting through the 2021-22 winter (~70% chance during November-January; click CPC/IRI consensus forecast for the chances in each 3-month period).
I keep hearing Klaus Wolter’s warning from 2011, “Beware a second year La Niña.”