12-Month Rainfall Forecast

Issue Notes

ENSO status: Neutral IOD status: Neutral SAM status: Trending neutral Sea surface temperatures (SSTs) across the equatorial central Pacific remained stable throughout January with the Nino3.4 index registering a value of 0.4 as per December. On the other hand, the Southern Oscillation Index (SOI) recorded a value of 1.3 in January. The current outlook suggests warmer than average SSTs will persist across the equatorial Pacific Ocean through the austral autumn, cooling even further by mid 2020. Six out of eight international models continue to maintain a warmer than average equatorial Pacific Ocean through the first half of the year, none of these reaching El Nino thresholds. To the west of Australia, the Indian Ocean Dipole (IOD) remains neutral, which is what you will expect for this time of the year. All six international models maintain neutral IOD values until the austral winter, with indications we could see another positive event late winter/spring. However, the skill of the models is low at this time of the year. In terms of rainfall across Australia, the current outlook favours average-to-below average rainfall for parts of inland NSW and Qld for the end of summer and autumn. This however, excludes any extreme weather events such as tropical cyclones or East Coast Lows. Across the north, the North Australian Monsoon (NAM) had its latest onset on record in early February at Darwin (by its technical definition) with the current prognosis suggesting another below average wet season for northern Australia. The northern half of the country however, could see a wet end to the wet season compared to the season thus far. Looking further ahead, with no significant signature from ENSO, there are no significant climate drivers tilting the balance towards a drier or wetter end of autumn/winter.