28th October 2008
Dry October after initial spring break
Generally below average rainfall has been recorded during October throughout most of the Queensland's broadacre cropping regions. This follows on from the average to above average spring break rainfall recorded during September. This has impacted on the area of dryland crops planted due to limited planting opportunities and condition of early planted crops.
For those looking for some rainfall opportunities the MJO is currently crossing northern Australia (end of October). During early to mid October the MJO signal was incoherent and weak. Over the last week the MJO signal has strengthened and become more organised. It is likely to trigger storm activity throughout the north of Queensland.
If its current timing remains consistent the next passage of the MJO is likely to occur very late in November or more likely in early December. This could trigger an early start to the monsoon season. Interestingly a key time to watch for the potential development of cyclones is after summer passages of the MJO.
The Madden-Julian Oscillation, or MJO, is a band of low air pressure which originates off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 60 days. Because of the timing of the MJO the phenomenon is also known as the forty day wave. It can be used as an indicator for the timing of potential rainfall events.
The MJO influences rainfall across Australia. The impact of the MJO on rainfall varies between the different seasons and location. For example the MJO has a greater influence of rainfall throughout northern Australia during summer and southern Australia during winter.
Throughout spring the MJO has a drying influence across Queensland when it is in Phase 1 and 2 (Indian Ocean). Wetter conditions tend to prevail in south west Queensland when the MJO is in Phase 5 (Indonesian Region) and in northern Queensland when the MJO is in Phase 6 and 7 (Western Pacific).
The SOI has remained in positive values. The thirty day average of the SOI as of the 28th October was plus 15.3.
The outlook for November to December based on a Consistently Positive (Phase 2) SOI for October and historical rainfall records indicates a 50 to 70 % chance, or slightly better than even odds, of receiving median rainfall over summer.
For more information on the current seasonal outlook try www.longpaddock.qld.gov.au http://www.longpaddock.qld.gov.au/> or call (07) 46881459.