SSF Forecast for July to October
For July to October the SSF forecast is indicating above 60% probability of above median rainfall for parts of the Central West, Central Wheatbelt, Lower West, South West, Great Southern and South East Coastal forecast districts. Less than 40% probability for South Coastal forecast district, and neutral (40-60%) probability for the remainder. The most likely decile range map is indicating decile 8-9 for parts of the Central West, Central Wheatbelt, Lower West, South West, Great Southern and South East Coastal forecast districts, decile 2-3 for South Coastal forecast district and decile 4-7 elsewhere. Skill is poor to good at 50 to 70% consistent.
June rainfall was below average to average for the SWLD, due to the positive Southern Annular Mode. June maximum and minimum temperatures were average to above average. Rainfall decile map for 1 April to 3 July 2022 shows decile 8-10 rainfall for South East Coastal, South Coastal and parts of the Great Southern and Central Wheatbelt forecast districts.
In June the atmospheric pressure was higher than normal over the SWLD.
In June, sea surface temperatures were warmer than average around tropical Australia. The August to October, sea surface temperature outlook by the Bureau of Meteorology indicates SSTs are likely to remain warmer than normal around Western Australia and the north and south-east of Australia.
The Indian Ocean Dipole (IOD) is neutral. There has been little change in the IOD in the last two months, and models have significantly over forecast a negative IOD developing since May. Models are still indicating the development of a negative IOD in July and persisting until at least October. Past negative IOD events generally increase rainfall in the eastern grainbelt.
The Southern Annular Mode (SAM), also known as the Antarctic Oscillation (AAO), describes the north–south movement of the westerly wind belt that circles Antarctica, dominating the middle to higher latitudes of the southern hemisphere. SAM is currently positive which suppresses the activity of cold fronts in the Southern Ocean. SAM forecast to remain positive until the end of July. For more information see the Bureau of Meteorology’s Climate Driver Update.
The 2021-22 La Nina is at an end, with key indicators having returned to neutral. However, some models suggest that La Nina may re-from during spring 2022.
The table below gives a summary of past month and three-month South West Land Division (SWLD) climate conditions and can indicate what is likely to occur in the near future if climate conditions follow the current pattern.
|Climate Indicator||Past month||Past 3 months|
|SWLD Rainfall||Below average to average||Mixed|
|SWLD Mean Temperature||Average to above average||Average to above average|
|SWLD atmospheric pressure||Higher||Lower|
|Indian Ocean Sea surface temperature||Warmer||Warmer|
|El Niño/Southern Oscillation (ENSO)||neutral||La Niña|
|Indian Ocean Dipole (IOD)||Neutral||Neutral|
|Southern Annular Mode (SAM)||Positive||Positive|