Northern Australian rainfall outlook

Issued 26 March 2014

Drier conditions more likely for parts of the north and east

Summary

  • A drier than normal April to June period is more likely for parts of southern Queensland and the Top End
  • Over the rest of northern Australia there is no significant shift in the odds towards either a wetter or drier three month period
  • Climate influences include a warming tropical Pacific, and a warm to near-normal Indian Ocean
  • Outlook accuracy is moderate to high over a large part of northern Australia
Probability of exceeding median rainfall, large image

Details

As the tropics transition away from the wet season, the chances of exceeding the median rainfall during April to June are 35 to 40% over the north coast of the Top End of the NT and Cape York. Likewise, parts of southern Queensland can expect similar odds. In other words, the chances of below average rainfall are 60 to 65% over these areas, or about six of ten seasons with similar odds would result in below-average rainfall over these areas, while about four would be above average.

Over the rest of northern Australia (such as tropical savannahs and semi-arid regions), there is a near equal chance of above or below normal rainfall, as there is no significant shift in the odds towards either a wetter or drier April to June period.

Keep in mind that across the tropical regions April is the wettest of the three months in this outlook while May and June are usually dominated by dry season weather patterns.

Climate influences

The El Niño-Southern Oscillation (ENSO) currently remains neutral, but the tropical Pacific is currently warming. 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 the southern winter.

Sea surface temperatures surrounding Australia, and to the west, are expected to be near normal to warmer than normal. The warmer waters to the west of Australia may partially influence the weather patterns over the coming months.

The Indian Ocean Dipole (IOD) influence is minimal during the first part of the outlook period, with a neutral IOD likely for the second part.

How accurate is the outlook?

Outlook accuracy for the April to June period is:

  • Moderate to high over a large part of northern Australia, with the exception of
  • a small part of the central NT and a medium sized part of southern Queensland, where accuracy is low to very low