BOM: Shift towards La Niña continues

BOM 15 Sep 2020

The Bureau’s ENSO Outlook remains at La Niña ALERT. However, further cooling of the surface of the tropical Pacific Ocean is expected. All surveyed international climate models indicate La Niña thresholds will be met from October until at least the end of the year, with most models maintaining these values into early 2021.

Key indicators of ENSO are currently at or approaching La Niña thresholds, indicating that the atmosphere is responding to the changes in the ocean. If current atmospheric patterns and ocean cooling continue until the end of September, it is highly likely that La Niña conditions will be sustained until at least the end of the year.

In the Indian Ocean, values of the Indian Ocean Dipole (IOD) index have risen back into neutral territory. However, five of the six surveyed models indicate values may drop once again, and that negative IOD thresholds could be met in October. To be considered a negative IOD event, these values would need to be sustained for at least eight weeks.

NINO3.4 SST plume graphs from ACCESS-S forecasts, updated daily

IOD SST plume graphs from ACCESS-S forecasts, updated daily

Source: http://www.bom.gov.au/climate/enso/outlook/