Climate Watch Dave McRae Qld DPI&F 10/04/06
According to the Bureau of Meteorology at www.bom.gov.au late February/early March saw an active phase of the MJO and a reinvigorated monsoon trough moving southward over northern Australia. The MJO then rapidly weakened until a new active MJO phase developed in late March along with a reinvigorated monsoon trough moving southward over northern Australia.
We now appear to be approaching the end of this MJO event. The next active phase of the MJO would therefore be expected in early to mid-May. 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 try www.apsru.gov.au/mjo/
The monthly SOI value rose from minus 0.6 for February to plus 11.4 for March placing it in a 'Rapidly Rising' SOI phase. Based on a Rising SOI phase at the end of March there is a 40 to 60% chance of getting above median rainfall across most of Queensland during April to June.
To follow the relationship between the SOI and rainfall patterns in more detail have a look at what happened in your area during April to June in the following years since 1900 that have had a 'Rapidly Rising' SOI phase at the end of March; 2005, 1990, 1988, 1986, 1973, 1970, 1969, 1964, 1960, 1959, 1952, 1947, 1937, 1935, 1931, 1927, 1914, 1913, 1908, 1907, 1903, 1902 and 1901.
For example at Emerald below median rainfall for April to June in those years was recorded five times, close to median rainfall was recorded eleven times and above median rainfall was eight times. More information on rainfall patterns can be found in Rainman StreamFlow.
Rainfall probability maps are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au and SOI updates are available on (07) 46881439. For more information call 132523.