Southeast Australian rainfall outlook

Issued 24 April 2014

No strong rainfall tendency for most of southeast Australia

Summary

  • The chances of a wetter or drier than normal season are roughly equal over a majority of southeast Australia
  • A wetter than normal season is more likely for eastern Victoria and the far South Coast of NSW
  • Climate influences include a warming tropical Pacific, and a warm Indian Ocean
  • Outlook accuracy is moderate throughout NSW, central Victoria and most of Tasmania with low accuracy generally throughout the pastoral and southeast parts of SA and eastern Victoria.
Probability of exceeding median rainfall, large image

Details

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

However, the chances of exceeding the median rainfall during May to July are greater than 60% over the East Gippsland area of Victoria and the South Coast of NSW. For every ten May to July outlooks with similar odds to these, about six or seven of them would result in above-average rainfall over these areas, while about three or four would be below average.

Climate influences

The El Niño-Southern Oscillation (ENSO) currently remains neutral, but is 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 models approaching or exceeding El Niño thresholds during the southern winter.

Sea surface temperatures in the eastern Indian Ocean, to the south of Australia, and in parts of the Tasman Sea are currently warmer than normal, and are generally expected to remain warm through the forecast period. These warmer waters surrounding Australia are not typical of El Niño, and may be somewhat negating the effect of the developing El Niño on the eastern regions.

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.

How accurate is the outlook?

Outlook accuracy for the May to July period is:

  • Moderate over most of NSW, central Victoria and most of Tasmania
  • Low over Pastoral and southeast parts of SA and western and eastern Victoria