12-Month Rainfall Forecast

Issue Notes

ENSO status: Neutral. IOD status: Neutral, although during the past three weeks it has been negative. SAM status: Positive. The El Niño–Southern Oscillation (ENSO) is currently neutral, which is predicted to continue until at least October. The Indian Ocean Dipole (IOD) is currently neutral. although the last 3 weekly values have been negative.The negative value would need to continue for another 5 weeks for a negative IOD to be declared. While a negative IOD has not been officially declared, the negative weekly value may enhance rainfall across central and southern Australia. A negative IOD is forecast during winter or early spring by 3 out of 5 climate models. However, the confidence in the IOD forecast at this time of the year is low, specifically because the models are showing a range of outcomes from mid winter onwards. During winter, much of the Australia is likely to be wetter than normal, apart from far southern WA and SA, southern VIC and much of TAS. The weekly negative IOD valuesmay be influencing this outlook, potentially feeding moisture into cold fronts sweeping across central and southern Australia. Therefore a normal to above normal snow season is forecast. Springs rainfall at this stage is forecast to be above normal for much of the Australia, apart from western TAS. Again, the negative IOD values may be playing a role in this outlook.