Southeast Australian rainfall outlook

Issued 28 May 2014

A drier winter more likely for the southeast Australian mainland

Summary

  • A drier than normal winter is more likely for most of the southeast Australian mainland
  • A wetter than normal winter is more likely for eastern Tasmania
  • Climate influences include a warming tropical Pacific, and an easing of the warm eastern Indian Ocean
  • Outlook accuracy is moderate northern parts of NSW, northeast SA and western Tasmania, with low accuracy elsewhere
Probability of exceeding median rainfall, large image

Details

The chances of receiving above median rainfall for winter are less than 40% over most of SA, NSW and northern Victoria (see map above). Chances fall below 30% over eastern agricultural parts of SA, and southern NSW. In other words, this means the chances of below average rainfall is greater than 60% in these areas. For every ten winter outlooks with similar odds to these, about three or four of them would result in above-average rainfall over these areas, while about six or seven would be below average.

Conversely, the chance of exceeding the median rainfall is greater than 60% over eastern Tasmania.

There is no significant shift in the odds towards either a wetter or drier than normal season for the southern parts of Victoria and western Tasmania.

Climate influences

The El Niño-Southern Oscillation (ENSO) is currently in a state of transition towards El Niño. Dynamical models surveyed by the Bureau indicate that further warming of the tropical Pacific is likely in the coming months, with most models approaching or exceeding El Niño thresholds during late winter.

Models indicate the currently warm tropical eastern Indian Ocean is likely to return to near normal. The Indian Ocean Dipole (IOD) is expected to remain neutral for the next three months, and is therefore unlikely to have a significant influence upon this outlook. Positive IOD events often coincide with El Niño and are typically associated with lower than average winter and spring rainfall over parts of southern and central Australia.

How accurate is the outlook?

Outlook accuracy for the winter period is:

  • Moderate over northern parts of NSW, northeast SA and western Tasmania
  • Low most of SA and Victoria