Seasonal Climate Outlook Message for April to July 2009
The bottom line
MJO Due Dave McRae, Qld Climate Change Centre of Excellence, 14/04/09.
The Madden-Julian Oscillation or MJO last crossed northern Australia during late February/early March. The enhanced tropical convection associated with this passage of the MJO also saw the development of tropical cyclones Gabrielle and Hamish with another tropical low off the northwest Australian coast.
The next active phase of the MJO is likely to cross northern Australia during the second half of April. Given the time of year it is unlikely that a strong monsoon trough would redevelop although there remains some risk of tropical cyclone development.
The MJO is a band of low air pressure which originates off the east coast of central Africa. It travels 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 impact of the MJO on rainfall varies between the different seasons and location. For example the MJO has a greater influence on rainfall throughout northern Australia during summer and southern Australia during winter. For more information on the MJO go to www.bom.gov.au
In what would not be a surprise there is a reasonable chance of getting an above median sorghum yield on a shire basis throughout the north east Australian cropping region for the 08/09 summer growing season.
There are though the usual variations. For example, the summer cropping regions of central Queensland and northern NSW have an average to above average sorghum crop yield expectation. This is comparison to southern QLD where sorghum crop yield expectations are closer to or slightly below long term average yields.
The regional sorghum crop outlook is based on the assumption of a winter fallow and does not take into account effects of poor crop nutrition or damage due to pests, diseases, heat or frosts. For more information go to www.dpi.qld.gov.au or give Andries Potgieter a call on (07) 4688 1417 or 132523.
The 30 day average of the SOI as of the 14th April is plus 4.8. You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, call me on (07) 4688 1459.
The full story
SOI fluctuates. Dave McRae, Qld Climate Change Centre of Excellence, 14/04/09
The monthly value of the SOI has fallen from plus 15.2 for February to minus 1.4 for March. This is the lowest monthly value of the SOI since May 2008. Based on historical rainfall records and a Rapidly Falling SOI phase at the end of March, there is a lower 30 to 50% chance of getting above median rainfall during April through to the end of June across most of Queensland.
For example Killarney has an 48% chance of getting above its April to June median rainfall of 122mm, Charters Towers has a 45% chance of getting above its April to June median rainfall of 65mm, Cooyar has a 40% chance of getting above its April to June median rainfall of 100mm, Augathella has a 40% chance of getting above its April to June median rainfall of 75mm, Longreach has a 35% chance of getting above its April to June median rainfall of 57mm, Rockhampton has a 35% chance of getting above its April to June median rainfall of 135mm, Goomeri has a 30% chance of getting above its April to June median rainfall of 116mm and Julia Creek has a 30% chance of getting above its April to June median rainfall of 25mm.
In terms of the seasonal outlook for winter and spring it would be worthwhile to watch SOI trends over coming months. For example, if the current fall in value of the SOI where to continue into strongly negative values and remain there through to the end of autumn, it would be a warning sign for a likely dry winter/spring.
When using a climate forecast you should remember that the probability or percent chance of something occurring is just that - a probability. For example if there is a 70% chance of recording more than 100 mm there is also a 30% chance of recording less than 100 mm i.e. 70-30; 30-70. It does not mean that you will get 70% more than 100 mm or 100 mm plus another 70%.
SOI influence on climate varies across Australia (greatest skill is for eastern Australia) and between seasons (usually greatest skill is for winter, spring and early summer). Therefore users of the SOI and any other seasonal forecasts are urged to investigate skill level for their location by using such tools as Rainman StreamFlow.
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 April to June in the following years since 1950 that have had a Rapidly Falling SOI phase at the end of March: 1951, 1955, 1961, 1966, 1968, 1977, 1979, 1980, 1981, 1984, 1985, 1991, 1994, 1997 and 2002. Find out your average rainfall for April to June and see how many times rainfall was well below, well above or close to average during April to June in the listed years. For more information on historical rainfall data for your region try Rainman Streamflow, www.longpaddock.qld.gov.au or www.bom.gov.au
As autumn is a key time for the establishment of climate phenomena such as El Nino and La Nina QCCCE climate staff will continue to closely monitor what happens over the next few months. You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, call me on (07) 4688 1459.
The Madden-Julian Oscillation or MJO last crossed northern Australia during late February/early March. The enhanced tropical convection associated with this passage of the MJO also saw the development of tropical cyclones Gabrielle and Hamish with another tropical low off the northwest Australian coast.
The next active phase of the MJO is likely to cross northern Australia during the second half of April. Given the time of year it is unlikely that a strong monsoon trough would redevelop although there remains some risk of tropical cyclone development.
The MJO is a band of low air pressure which originates off the east coast of central Africa. It travels 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 impact of the MJO on rainfall varies between the different seasons and location. For example the MJO has a greater influence on rainfall throughout northern Australia during summer and southern Australia during winter. For more information on the MJO go to www.bom.gov.au
In what would not be a surprise there is a reasonable chance of getting an above median sorghum yield on a shire basis throughout the north east Australian cropping region for the 08/09 summer growing season.
There are though the usual variations. For example, the summer cropping regions of central Queensland and northern NSW have an average to above average sorghum crop yield expectation. This is comparison to southern QLD where sorghum crop yield expectations are closer to or slightly below long term average yields.
The regional sorghum crop outlook is based on the assumption of a winter fallow and does not take into account effects of poor crop nutrition or damage due to pests, diseases, heat or frosts. For more information go to www.dpi.qld.gov.au or give Andries Potgieter a call on (07) 4688 1417 or 132523.
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.
