Summary
The Department of Primary Industries and Regional Development’s (DPIRD) Statistical Seasonal Forecast (SSF) outlook for spring, September to November is generally less than 40% chance of exceeding median rainfall for the majority of the South West Land Division, with neutral to higher odds chance (40-70%) elsewhere.
- For spring, September to November, the SSF is generally less than 40% chance of exceeding median rainfall for the majority of the South West Land Division. Neutral to higher chance (40-70% chance) for some central and southern parts. The most probable rainfall decile map indicates decile 2-3 for the northern and eastern parts of the SWLD, with decile 4-7 for southern parts and 8-9 for western parts of the Great Southern. Predictive skill based on August conditions is poor to moderate (50-70% consistent).
- The Bureau of Meteorology’s current seasonal outlook is indicating 25-55% of exceeding median rainfall for spring, September to November 2020 for the majority of the South West Land Division. Higher chances 60-65% for the South East Coastal District of the SWLD. Predictive skill is good (55-75% consistent). The longer-term outlook for October to December is mostly neutral with (50-70%) wetter chances for southern parts of the SWLD. Predictive skill is poor (55% of less) for the northern SWLD and good (55-75%) for the remainder 45-75% consistent.
- Temperature outlooks for spring, September to November 2020, from the Bureau indicate a 45-70% chance of above average day-time maxima (skill 55-100%) and 50-75% chance of above average night-time minima (skill 55-75%) for the SWLD.
- August rainfall was generally below average in the SWLD, and above average along the south coast. August maximum temperatures were above average. August minimum temperatures were average to above average. Maximum temperatures for winter was the highest on record for Western Australia.
- The main climate driver influencing the South West Land Division is a positive Southern Annual Mode, reducing the chance of rainfall for September.
Three month seasonal outlook
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 web page.
For spring, September to November, the SSF is generally less than 40% chance of exceeding median rainfall for the majority of the South West Land Division. Neutral to higher chance (40-70% chance) for some central and southern parts. The most probable rainfall decile map indicates decile 2-3 for the northern and eastern parts of the SWLD, with decile 4-7 for southern parts and 8-9 for western parts of the Great Southern. Predictive skill based on August conditions is poor to moderate (50-70% consistent).
