Seasonal Climate Outlook Message for July to October 2006

The bottom line

SOI in Negative Phase Dave McRae 05 July 06 Based on a monthly value of minus 6.7 for June the SOI is now in a 'Consistently Negative' phase. At this time of year a consistently negative SOI phase gives generally low rainfall probabilities across Queensland. For example there is less than a 20% chance of getting above median rainfall during July to September for the south west and Burnett regions of Queensland. Throughout the rest of the north east and southern half of the state there is only a 20 to 40% chance of getting above median rainfall. Current 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 contact the DPI&F on 132523.

The full story

SOI In Negative Phase 5th July 06 At the end of June the SOI was in a 'Consistently Negative' phase. Based on this phase during July to September there is less than a 20% chance of getting above median rainfall for the south west and Burnett regions of Queensland. Throughout the rest of the north east and southern half of the state there is a 20 to 40% chance of getting above median rainfall (or depending on your view point a 60 to 80% chance of below median rainfall). A Negative SOI phase at the end of June also increases the chance of getting above median maximum temperatures and of getting below median minimum temperatures for July to September across much of Queensland. Interestingly the latitude of the sub-tropical ridge of high pressure is further south than normal for this time of year. This has the potential to increase shower activity along the coastal fringe. Low probabilities do not mean there will be no rainfall, all it means is that rainfall for July to September will more likely be below median than well above median. The latest probability maps are at http://www.dpi.qld.gov.au/climate or http://www.longpaddock.qld.gov.au and daily updates on the SOI are available on (07) 46881439. For more on rainfall probabilities, monthly medians or medians for your location refer to Rainman StreamFlow or contact 132523 or (07) 3404 6999. For all our selected locations there is a low chance of getting above median rainfall for July to September. For those interested in cloud seeding there is an interesting report from CSIRO available at http://www.cmar.csiro.au/e-print/open/cloud.htm It is a better source of information to quote or believe than some of the recent media articles on this topic. While there were MJO events over the Indian Ocean in April, May and June there was little or no rainfall impact across Australia and the MJO events were weak in amplitude and structure. If the recent timing of the MJO persists at around 30 days then the next passage north of Australia would be expected in late July. For those seeking rain for dry planted winter cereal crops, a synoptic feature such as a north-west cloud band or trough system is required in conjunction with the passage of the MJO in winter to result in rain. Over the past two weeks the passage of the MJO has triggered monsoonal activity in India and Indonesia. 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 http://www.apsru.gov.au/mjo/ or http://www.bom.gov.au/climate/tropnote/tropnote.shtml For those who like to follow the relationship between the SOI and rainfall patterns in more detail have a look at what happened in your area during July to September in the following years since 1900 that have had a 'Consistently Negative' SOI phase at the end of June; 1905, 1911, 1912, 1914, 1940, 1946, 1972, 1977, 1987, 1994, 1997 and 2002. For example at Toowoomba, below median rainfall for July to September in those years was recorded 7 times and close to median rainfall was recorded 5 times with no recordings of well above median. At Gayndah, below median rainfall for July to September in those years was recorded 7 times, close to median rainfall was recorded 5 times with no recordings of well above median rainfall. Therefore rainfall at Gayndah and Toowoomba during July to September is more likely to be below median than well above median. The output from ocean/atmosphere forecast models continues to indicate a neutral sea surface temperature (SST) pattern in the central Pacific (rather than an El Nino or La Nina). However both surface and sub-surface ocean temperatures in the key regions of the central Pacific have warmed over the last 2 months. If this warming trend in the central Pacific continues it may adversely impact on our expected winter, spring and early summer rainfall. For more on conditions in the Pacific try the Bureau of Meteorology at http://www.bom.gov.au/climate/ahead/ When I'm asked about how climate information can be used I refer to a couple of key points developed from client feedback. Key points include that management decisions should never be based entirely on one factor such as a climate or weather forecast. As always, everything that could impact of the outcome of a decision (soil moisture, pasture type/availability, crop and commodity prices, machinery, finance, costs etc) should be considered. For example, the level of soil moisture at planting is the major factor influencing crop yield or success. A simple cost benefit analysis when making a major decision may also be useful. For example what will I gain if I get the desired outcome? What will I lose (sleep, money, family relationships) if I do not get the desired outcome and what other options (risk neutral) are there? A PART OF THIS PROCESS IS TO HELP MANAGERS TO BE CAREFUL NOT TO CHANGE FROM NORMAL RISK MANAGEMENT TO HIGH LEVEL RISK TAKING BASED ON A PIECE OF INFORMATION (SUCH AS A CLIMATE FORECAST). Forecasts as well do not always give a strong signal as to likely conditions for your location. In assessing climate forecasts as a management tool consider the level of signal for the key decision times in your location. Rainman StreamFlow is a useful tool for this. An interesting site http://www.managingclimate.gov.au/ from the 'Climate Variability In Agriculture' (CVAP) research and development program is well worth looking at. It highlights some case studies on how producers and businesses have used (to varying levels of success) climate and weather information in their decision-making processes.