Western Australian rainfall outlook

Issued 24 February 2014

Wetter autumn favoured in western parts of Western Australia

Summary

  • A wetter than normal autumn is more likely for western parts of WA
  • Outlook accuracy is low to moderate to high over most of WA
Probability of exceeding median rainfall, large image

Details

The chances of exceeding median rainfall during autumn are 60 to 70% in western parts of Western Australia. For every ten autumn outlooks with similar odds to these, about six or seven would be expected to be above average over these areas, while about three or four of them would be expected to result in below-average rainfall.

Over the north and east of the State, there is no significant shift in the odds towards either a wetter or drier than normal autumn.

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.

Oceans surrounding Australia are generally expected to remain close to their 1981-2010 average.

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 across parts of the west and northern coasts of WA
  • Low in the East Kimberley and across parts of the southwest of the State