Seasonal Climate Outlook

Summary

The Department of Primary Industries and Regional Development’s (DPIRD) Statistical Seasonal Forecast (SSF) system is indicating less than 40% chance of exceeding median rainfall for summer, December 2017 to February 2018 for the majority of the wheatbelt.

  • The SSF is indicating 60-70% chance of exceeding median rainfall for the far northern agriculture region and south-west corner. This chance has increased to 70-80% for the Perth region. This region typically has low rainfall over summer.There is less than 40% chance for northern, central and eastern agricultural regions, with neutral (40-60%) chances elsewhere. The most probable decile range map indicates decile 2-3 rainfall is most likely for eastern and central wheatbelt, with decile 8-10 rainfall for the far northern wheatbelt and south-west corner and decile 4-7 elsewhere. Predictive skill based on November conditions is poor (50-60% consistent) across most of the region.
  • The Bureau of Meteorology’s current seasonal outlook indicates generally a neutral outlook, with 45-60% chance of exceeding median rainfall for summer for the South West Land Division (SWLD). Predictive skill is poor to good (50-75% consistent). For the individual month of December the chance is lower at 35-45%.
  • Temperature outlooks for summer, December 2017 to February 2018 from the Bureau indicate a 45-65% chance of above normal day-time maxima for the SWLD. Skill is moderate to good at 50-75% consistent. Minimum temperature outlooks indicate a 55-65% chance of above normal night-time minima for the SWLD, with moderate to good skill at 50-75% consistent.
  • November rainfall in the SWLD was below average to near average. November maximum and minimum temperatures were very much above average.

Three month outlook for the south-west of Western Australia

Statistical Seasonal Forecasting (SSF)

DPIRD’s Statistical Seasonal Forecast (SSF) system uses historical relationships between global sea surface temperature and sea level pressure with rainfall in south-west Australia to produce forecasts of rainfall for the coming months. Users can click on any station indicated on the map for location-specific forecast information from the Seasonal Climate Information page.

For summer, December 2017 to February 2018, the SSF is indicating 60-70% chance of exceeding median rainfall for the far northern agricultural region and south-west corner. This chance has increased to 70-80% for the Perth region. This region typically has low rainfall over summer, so the outlook is not necessarily indicating heavy rainfall. There is less than 40% chance for northern, central and eastern agricultural regions, with neutral (40-60%) chances elsewhere. The most probable decile range map indicates decile 2-3 rainfall is most likely for the eastern and central wheatbelt, with decile 8-10 rainfall for the far northern wheatbelt and south-west corner and decile 4-7 elsewhere. Predictive skill based on November conditions is poor to good (50-70% consistent). Note that most of the region has low skill at this time of year.

SSF forecast of probability of exceeding median rainfall for summer, December 2017 to February 2018. Indicating less than 40% chance of receiving median rainfall for the majority of the wheatbelt, and higher chances (above 60%) for the south-west corner a

SSF forecast of probability of exceeding median rainfall for summer, December 2017 to February 2018.

Percent Consistent skill of the SSF at forecasting December to February rainfall using data up to and including November.  Skill is 50 to 70 percent consistent.

Percent Consistent skill of the SSF at forecasting December to February rainfall using data up to and including November.