Forecast

Issue Notes - Issued Jun 21

ENSO status: Neutral, However, some models suggest La Niña may re-form in spring. IOD status: Neutral, however the index has been below zero for the past six weeks. SAM status: Negative, but is expected to rise to positive values before returning to neutral levels late in June. The 2021-22 La Nina event has ended, however four out of seven models suggest a return of La Nina in spring. Even though this event has ended, a La Nina-like pattern could persist in winter with warm sea surface temperatures surrounding Australia. There is still some uncertainty between forecast models, especially beyond the Southern Hemisphere’s spring. However, new data released by the U.S. Climate Prediction Centre continues to point towards the prospect of a third consecutive La Niña later this year. While the IOD is currently officially neutral, however the index has been below zero for the past six weeks. All climate models are forecasting a negative IOD event this winter and spring, with several forecasting stronglynegative IOD values in August. A negative IOD increases the chance of above average winter and spring rainfall and cloud across parts of southern Australia. The rainfall outlooks are reflecting this, with above average rain forecast during winter for much of Australia, except southwest WA, TAS and parts of VIC. If a negative IOD does develop this winter, it will increase the risk of flooding over large areas of inland Australia, especially areas that had a wet summer and autumn.