Southeast Australian rainfall outlook

Issued 27 November 2013

Wetter summer more likely for Tasmania

Summary

  • A wetter than normal season is more likely for Tasmania
  • A drier than normal season is more likely for northeast NSW
  • The chances of a wetter or drier than normal season are roughly equal over the remaining areas of Southeast Australia
  • Climate influences include a neutral tropical Pacific, and local sea surface temperature patterns
  • Outlook accuracy is moderate over most of the northern and southern parts of NSW and northeast Victoria. Outlook accuracy is very weak over most SA, southwest Victoria and Tasmania.
Probability of exceeding median rainfall, large image

Details

The chances of exceeding the median rainfall during summer are greater than 60% over Tasmania. So, for every ten summer 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.

Conversely, the chance of exceeding the median rainfall is less than 40% over northeast NSW.

The chance of receiving a wetter or drier than normal summer period is roughly equal (i.e., close to 50%) over the remaining areas of Southeast Australia.

Climate influences

The tropical Pacific has remained ENSO-neutral since mid-2012. Dynamical models surveyed by the Bureau suggest ENSO-neutral conditions are likely to persist at least for the austral summer. This means the tropical Pacific Ocean is not producing a strong shift in the odds in this outlook.

With major climate influences likely to remain neutral over the coming months, secondary influences, such as the pattern of warmer-than-normal sea surface temperatures around the Australian continent are tending to drive climate condition across the country.

How accurate is the outlook?

Outlook accuracy is related to how consistently the oceans and broadscale climate affect Australian rainfall. During summer, historical accuracy shows the outlook to be moderately consistent over Northern and southern parts of NSW and northeast Victoria. Over most of SA, southwest Victoria and most of Tasmania the outlook is only very weakly consistent.