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ENSO Tracker - July 2021 | CLIMAS

 SW Climate Outlook

ENSO Tracker - July 2021

ENSO Tracker - July 2021

Sea surface temperature (SST) forecasts for Aug – Oct 2021 call for cooling conditions across the equatorial Pacific (Fig. 1). The current Nino 3.4/4 anomalies have returned to the range of neutral (Fig. 2). The ENSO outlooks note the persistence of neutral conditions in the short term, along with the potential return of La Niña conditions in winter 2021-2022.

Forecast Roundup: On July 6, the Australian Bureau of Meteorology ENSO tracker was neutral/inactive, stating ENSO “remains neutral with all oceanic and atmospheric indicators within the neutral range”, but noted likely cooling in the Pacific SSTs into Fall 2021. On July 8, the NOAA Climate Prediction Center (CPC) ENSO status moved to “La Niña Watch” with a 51-percent chance of ENSO-neutral during Aug-Oct, and a 66-percent chance of La Niña emerging in Nov-Jan. On July 8, the International Research Institute (IRI) issued an ENSO Quick Look (Fig. 3), noting “most key atmospheric variables are consistent with ENSO-neutral conditions”, and with ENSO-neutral likely through fall, but “with greater uncertainty later in the year”. On July 9, the Japanese Meteorological Agency (JMA) observed ENSO-neutral conditions were persistent, and called for a 70-percent chance of neutral conditions continuing to autumn. The North American Multi-Model Ensemble (solid and dashed black line, Fig. 4) are back to ENSO-neutral, and are expected to remain neutral through summer, but then indicate a more towards La Niña conditions in late 2021.

Summary: ENSO neutral conditions persist, and the seasonal forecasts are relatively certain that neutral conditions will remain through the summer. Longer-term forecasts are starting to lean towards a return of La Niña later in 2021, despite considerable uncertainty in these forecasts. La Niña winters are typically drier than average in the Southwest, so this forecast is something to watch, along with the ongoing North American Monsoon, given the accumulated drought conditions in the region.

Online Resources

  • Figure 1 - Australian Bureau of Meteorology -
  • Figure 2 - NOAA - Climate Prediction Center -
  • Figure 3 - International Research Institute for Climate and Society -
  • Figure 4 - NOAA - Climate Prediction Center -