Rain welcome; SOI slowly rising; MJO due.
Dave McRae, Qld Climate Change Centre of Excellence, 19th June 2007.
A broad upper trough over northern and central Queensland earlier this week has brought un-seasonal cloud and rain across much of the northern half of the state. While some areas have recorded in excess of 50 mm, the totals recorded have varied and unfortunately much of the very dry southern half of Queensland has missed out.
Interestingly over the last week the sub-tropical ridge of high pressure has been further south than normal. If this pattern continued over winter it would increase the flow of moisture laden south easterlies across Queensland and improve the opportunities for convection and potentially rainfall.
In the mean time the SOI has maintained a slow upward trend. As of Tuesday the 19th the 30day average of the SOI was plus 6.2. The development of consistently positive monthly SOI values would help provide the background climate conditions for an improvement in seasonal conditions throughout Queensland.
Rainfall to date, soil water conditions and the current seasonal outlook indicate a below average wheat yield for Queensland's 2007 wheat-growing season. There are though variations between the different growing regions.
The MJO is due to cross northern Australia over the next few days. This means it would not be next expected until the end of July. The MJO is a band of low air pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 60 days. Research has shown the MJO to be a useful indicator of the timing of potential rainfall events (but not amounts). For more information on the MJO try www.apsru.gov.au/mjo/