Rainfall probabilities remain reasonable (Dated 20th August)
As of the 20th August the 30day average of the SOI is minus 0.4.
Based on the recent pattern of the SOI, the chance of getting or getting above the long term August to October median rainfall levels are quite reasonable at around 50-80% for most of the southern two thirds of Queensland. The outlook across the rest of the state though is somewhat patchy.
For there to be increased confidence in the longer term outlook (eg through to summer) SOI monthly values will need to become more positive over the coming months.
Many readers of this column like to follow the timing of the MJO (also know as the 40day wave). The MJO is simply a band of low atmospheric pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 50 days.
While it is a tropical phenomenon, it appears to indicate the timing of potential rainfall events (but unfortunately not rainfall amounts) over central and southern Queensland.
The last passage of the MJO influenced Queenslands weather around mid July producing some generally useful falls across the state. As it's timing appears to have shifted out to approximately 50days it is next expected to influence our weather in very late August or early September.