Northern Australian rainfall outlook

Issued 28 May 2014

No strong shift in the odds for most of northern Australia

Summary

  • The chances of a wetter or drier season are roughly equal over most of northern Australia
  • Drier than normal conditions are more likely for southern Queensland, and small parts of the tropical north
  • Climate influences include a warming tropical Pacific, and an easing of the warm eastern Indian Ocean
  • Outlook accuracy is moderate to high over large parts of northern Australia, with low accuracy in the far north of Queensland and the southern NT.
Probability of exceeding median rainfall, large image

Details

The chances of receiving above median rainfall for June to August are less than 40% over parts of southern Queensland and along small areas of the north coast. In other words, this means the chances of below median rainfall is greater than 60% in these areas. However, it should be noted that the median rainfall along the north coast during these dry season months ranges from 0 mm to 4 mm. For every ten winter outlooks with similar odds to these, about three or four of them would result in above-normal rainfall over these areas, while about six or seven would experience normal to below normal rainfall.

Over the rest of northern Australia, there is no significant shift in the odds towards either a wetter or drier than normal season.

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 June to August period is:

  • Moderate to high over the northeast half of Australia
  • Low to very low over Cape York Peninsula in Queensland and the southern NT