ENSO Tracker - Nov 2021

ENSO Tracker - Nov 2021

Sea surface temperature (SST) forecasts for Dec 2021 – Feb 2022 indicate cool conditions across the equatorial Pacific (Fig. 1). Current Nino 3.4/4 anomalies appear to have reached the La Niña threshold (Fig. 2), and most ENSO outlooks now call for La Niña conditions to last through winter 2021-2022.

Forecast Roundup: Forecast Roundup: On Nov 10 the Japanese Meteorological Agency (JMA) observed La Niña conditions are present and called for a 60-percent chance of La Niña conditions to last through winter. On Nov 9 the Australian Bureau of Meteorology ENSO maintained their La Niña ALERT status noting “International climate models have strengthened their forecast likelihood of La Niña forming before the end of the year”, but that ”atmospheric and oceanic observations have yet to consistently reach La Niña levels.” On Nov 11 the NOAA Climate Prediction Center (CPC) maintained their “La Niña Advisory” noting strengthening La Nina conditions and calling for a 90-percent chance of La Niña during winter 2021-2022. On Nov 11 the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), noting “the evolution of key oceanic and atmospheric variables is consistent with La Niña conditions”. The North American Multi-Model Ensemble (solid and dashed black line, Fig. 4) reached La Niña levels and indicates a further swing to moderate La Niña in late 2021 and into 2022.

Summary: The seasonal outlooks have shifted to near consensus on a La Niña event in winter 2021-2022. This is tied to cooling SSTs in the equatorial region, and oceanic/atmospheric coupling indicative of La Niña, with overall consensus on a La Niña event of weak to moderate intensity. There are still lingering questions about whether conditions will last long enough to be classified as a La Niña event, but each month the forecasts are more confident the conditions will meet that threshold. La Niña winters are frequently warmer and drier than average in the Southwest, so this forecast is something to watch, given the drought conditions and cumulative precipitation deficits affecting the region.

Online Resources

  • Figure 1 - Australian Bureau of Meteorology - bom.gov.au/climate/enso
  • Figure 2 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov
  • Figure 3 - International Research Institute for Climate and Society - iri.columbia.edu
  • Figure 4 - NOAA - Climate Prediction Center - cpc.ncep.noaa.gov