Summary
The Department of Primary Industries and Regional Development’s (DPIRD) Statistical Seasonal Forecast (SSF) outlook for autumn, March to May 2023, is indicating greater than 60% probability of above median rainfall for the majority of the South West Land Division, although skill is very low this time of the year.
- For autumn, March to May 2023, the SSF forecast is indicating greater than 60% probability of above median rainfall for the majority of the South West Land Division. Less than 40% probability for parts of the Central West, Lower West, and South West forecast districts, neutral probability for elsewhere. The most likely decile range map is indicating decile 8-10 for the majority of the South West Land Division, decile 2-3 for parts of the Central West, Lower West, and South West forecast districts and decile 4-7 elsewhere. Skill is mostly poor at 50 to 70 % consistent.
- The Bureau of Meteorology’s seasonal outlook for autumn, March to May 2023, is indicating 25-40% chance of exceeding median rainfall for the SWLD, with mostly poor skill (45-65%). The current longer-term outlook (at time of writing) for April to June 2023 is 25-45% chance of exceeding median rainfall with mostly poor skill (45-75%).
- Temperature outlooks for autumn, March to May 2023, from the Bureau indicate a 80% chance of above average day-time maxima. Skill is moderate to good 65-100%. For night-time minima for the SWLD, the Bureau is indicating 70-80% chance of exceeding above average temperatures, with the higher chances along the coast. Skill is mostly poor at 45-65%.
- February rainfall was below average. February maximum temperatures were average to above average. Minimum temperatures were average.
- There is a possibility of an El Niño and a positive Indian Ocean Dipole (IOD) developing later this year. If an El Niño coincides with a positive IOD, there is a clear signal for reduced winter-spring rainfall for large parts of the South West Land Division. However skill at this time of the year is low and ENSO outlooks that extend past autumn should be viewed with caution.
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 DPIRD’s Seasonal Climate Information pages.
For autumn, March to May 2023, the SSF forecast is indicating greater than 60% probability of above median rainfall for the majority of the South West Land Division. Less than 40% probability for parts of the Central West, Lower West, and South West forecast districts, neutral probability for elsewhere. The most likely decile range map is indicating decile 8-10 for the majority of the South West Land Division, decile 2-3 for parts of the Central West, Lower West, and South West forecast districts and decile 4-7 elsewhere. Skill is mostly poor at 50 to 70 % consistent.
