We are privileged to have had wetter than normal start to the season on the east coast. Sowing conditions are ideal, with most seeds being planted into better than average moisture. The outlook is also favourable with increasing chances of negative IOD.
Year to date Average 2019
Berrigan 165mm 130mm 41mm
Henty 161mm 167mm 147mm
Marrar 161mm 167mm 86mm
Widgelli 198mm 124mm 108mm
Wetter than average conditions are likely for most of Australia during the remainder of autumn and into winter. The exception is parts of the tropical north and along the eastern seaboard, where outlooks have roughly equal chances of being wetter or drier than average.
In the shorter-term, the fortnight of 20 April to 3 May is likely to be drier than average along the eastern seaboard and for much of northern Australia, meaning a drier end to the northern wet season (mostly 60–75% chance). However, parts of the northern Kimberley in WA, southeast WA, SA and western Tasmania are likely to be wetter than average (60–75% chance).
The three months May to July are also likely to be wetter than average for most of Australia (mostly 60–75% chance, 70–80% chance for central Australia and the WA interior). The likelihood of a wetter or drier May to July is roughly equal across the far north NT and Queensland, along the coastlines of southeast Queensland, along NSW and into eastern Victoria, and southern Tasmania.
Similarly, June to August is also likely to be wetter than average for most of Australia (mostly 60–75% chance, with chances slightly higher towards central Australia).
While the Indian Ocean Dipole (IOD) is currently neutral, the Indian Ocean is expected to approach, or even exceed, negative IOD thresholds later in the outlook period. However, caution should be exercised with using IOD forecasts made during autumn, as they are less accurate than forecasts made at other times of the year. While all other international models surveyed by the Bureau approach or exceed negative IOD thresholds during 2020, the individual models have only moderate confidence at this time. Negative IOD events typically increase the likelihood of above average winter-spring rainfall across southern Australia.
The El Niño–Southern Oscillation (ENSO) is most likely to remain neutral over winter, though a weak La Niña cannot be ruled out for later in 2020.