Northern Australian rainfall outlook

Issued 23 October 2013

Odds favour less rainfall for northeast Australia

Summary

  • A drier than normal season is more likely for most of northeastern Australia, with strongest odds over Arnhem Land and interior Queensland
  • The chances of a wetter or drier than normal season are roughly equal over the Top End's northwest coast and Cape York Peninsula
  • Climate influences include locally warm sea surface temperatures around most of Australia, and a neutral tropical Pacific
  • Outlook accuracy is moderate over most of Queensland, and weak-to-moderate over the Top End.
Probability of exceeding median rainfall, large image

Details

The chances of exceeding the median rainfall during November to January are 30 to 40% over most of Queensland, most of the NT. Meaning, the chances of below average rainfall are 60 to 70% over these areas. Or, for every ten November to January outlooks with similar odds to these, about three or four of them would result in above-median rainfall over these areas, while about six or seven would be below the long-term median.

Climate influences

The two main climate influences, the El Niño-Southern Oscillation and the Indian Ocean Dipole, are currently neutral and are likely to remain neutral (and hence have lesser impact upon Australia) for the remainder of the wet season. Secondary influences, such as warmer-than-normal sea surface temperatures around Australia are tending to drive the Australian climate patterns for this period.

How accurate is the outlook?

Outlook accuracy is related to how consistently the oceans and broadscale climate affect Australian rainfall. During the November to January period, historical accuracy shows the outlook to be moderately consistent over most of Queensland. Over the Top End of the NT and western Queensland the outlook is weakly consistent, with the rest of the country only very weakly consistent.