Seasonal Climate Outlook

Bureau of Meteorology seasonal climate outlook

The Bureau of Meteorology's climate forecast system for monthly and seasonal climate outlooks is the Australian Community Climate Earth-System Simulator – Seasonal (ACCESS–S). It is a dynamic (physics-based) forecast modelling system and is a collaboration between the Bureau of Meteorology and the Meteorological Office of the United Kingdom.

The Bureau of Meteorology’s seasonal outlook for May to July indicated 35-55% chance of exceeding median rainfall for the SWLD. Predictive skill is poor to good (55-75% consistent). The longer term outlook for winter, June to August, is mostly neutral (40-65%) chance of exceeding median rainfall for the majority of the SWLD, with poor to moderate predictive skill (45-65%).

Temperature outlooks for May to July 2021 from the Bureau indicate a 65-80% chance of above average daytime maxima (skill 75-100%), and 60-80% chance of exceeding above average night time minima for most of the SWLD (skill 45-65%).

Rainfall outlook for May to July 2021 for Western Australia from the Bureau of Meteorology, indicating 35-55% chance of above median rainfall for the SWLD.
Rainfall outlook for May to July 2021 for Western Australia from the Bureau of Meteorology
Percent Consistent skill of the Bureau of Meteorology’s outlook for May to July indicating 55 to 75 percent consistent skill over the SWLD.
Percent Consistent skill of the Bureau of Meteorology’s outlook for May to July

Looking at other rainfall forecasting models, the majority of models are suggesting neutral to better chances of receiving above median rainfall for the SWLD for May to July 2021.

Model distribution summary of 12 models (not including the SSF) which forecast May to July 2021 rainfall in the South West Land Division. Most models are indicating neutral chance of above median rainfall in the next three months.
Model distribution summary of 12 models (not including the SSF) which forecast May to July 2021 rainfall in the South West Land Division.

SSF forecast for May to October

The SSF forecast for SWLD May to October 2021 rainfall is indicating mostly neutral (40-60%) chance of exceeding median rainfall for the majority of the SWLD, with wetter chances in south eastern parts. The most likely decile range map is indicating decile 4-7 for the SWLD. Skill is moderate to good at 60-100% consistent.

SSF forecast of the probability of exceeding median rainfall for May to October 2021 using data up to and including April. Indicating mostly neutral chances of exceeding median rainfall for Esperance and the western part of the South West Land Division.
SSF forecast of the probability of exceeding median rainfall for May to October 2021 using data up to and including April.
Percent consistent skill of the SSF at forecasting May to October rainfall using data up to and including April. Skill is 60 to 100 percent consistent.
Percent consistent skill of the SSF at forecasting May to October rainfall using data up to and including April.