Seasonal Climate Outlook

Summary

The Department of Primary Industries and Regional Development’s (DPIRD) Statistical Seasonal Forecast (SSF) system is indicating a 20-60% chance of exceeding median rainfall for August to October 2018.

  • The SSF is indicating less than a 40% chance of exceeding median rainfall for the northern grainbelt and southern coast for August to October 2018. Elsewhere is close to neutral chance (40-60%). Unfortunately the SSF cannot be updated to include July data as NOAA has not updated the mean monthly sea surface temperatures to include the month of July. The most probable decile range is decile 2-3 for most of the grainbelt. Predictive skill based on June conditions is mostly poor to moderate (50- 65% consistent).
  • The Bureau of Meteorology’s current seasonal outlook is indicating a 35-50% chance of exceeding median rainfall for July to September, for the South West Land Division (SWLD). Predictive skill is mostly poor to moderate (45-65% consistent).
  • Temperature outlooks for August to October 2018, from the Bureau indicate a 60-70% chance of above normal day-time maxima for the SWLD. Skill is poor to good at 50-75% consistent. Minimum temperature outlooks indicate a 65-75% chance of above normal night-time minima for the SWLD, with skill poor at 45-55% consistent.
  • July rainfall was near average or above average for much of the northern and central grainbelt, but below average in the Esperance region. July maximum and minimum temperatures were 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.

Unfortunately the SSF cannot be updated to include July data as NOAA has not updated the mean monthly sea surface temperatures to include the month of July. For the next three months, August to October, the SSF is indicating less than a 40% chance of exceeding median rainfall for the grainbelt, with large parts having less than a 30% chance. The most probable decile range is decile 2-3 rainfall for most of the grainbelt. Predictive skill based on June conditions is poor to moderate (50-65% consistent).

SSF forecast of the probability of exceeding median rainfall for August to October 2018 using data up to and including June. Indicating less than a 40% chanceof receiving median rainfall for the northern and southern grainbelt.
SSF forecast of the probability of exceeding median rainfall for August to October 2018 using data up to and including June

Percent Consistent skill of the SSF at forecasting August to October rainfall using data up to and including June. Skill is 50 to 65 percent consistent.
Percent Consistent skill of the SSF at forecasting August to October rainfall using data up to and including June