Northern Australian rainfall outlook

Issued 24 February 2014

Drier autumn more likely for parts of Queensland

Summary

  • A drier than normal autumn is more likely for most of Queensland and south eastern NT
  • Outlook accuracy is moderate to high over much of Northern Australia, except for some areas near the WA/NT border where the accuracy is low.
Probability of exceeding median rainfall, large image

Details

The chances of exceeding the median rainfall during autumn are less than 40% over parts of central and western Queensland and the southeast corner of the NT. In other words, there is a 60% chance of below normal rainfall over these areas. For every ten autumn outlooks with similar odds to these, about four of them would result in above-median rainfall over these areas, while about six would be below average.

Conversely, the NTs Roper-McArthur region has a 60% chance of exceeding the median rainfall over the course of the season.

Climate influences

The El Niño-Southern Oscillation (ENSO) remains neutral, with the majority of atmospheric and oceanic indicators close to their long-term average. Dynamical models surveyed by the Bureau suggest that while ENSO-neutral conditions are likely to persist through autumn, some warming of the central tropical Pacific Ocean is likely. While short of El Niño levels, this warming may still have some impacts upon Australian climate.

Ocean temperatures surrounding Australia are generally expected to remain close to their 1981-2010 average, though some cooler than average temperatures around northern and north-eastern coasts early in the season may mean a reduction in evaporation in those areas. Atmospheric pressures may be below average over some southern areas in the first half of the season, which may favour drier westerly winds over some parts of eastern Australia.

The Indian Ocean Dipole is typically too weak to have a significant influence on the Australian climate during the months from December to April.

How accurate is the outlook?

Outlook accuracy for the autumn period is:

  • Moderate over mmuch of the Top End of the NT and across parts Queensland
  • Low in parts over southeast Queensland, eastern parts of the NT and northern parts of the WA/NT border