Seasonal Climate Outlook Message for December 2009 to March 2010

The bottom line

MJO due end of year Dave McRae, Qld Climate Change Centre of Excellence, 08/12/09.

The last passage of the MJO crossed Australian longitudes during the second half of November. It triggered patchy and isolated storms and showers throughout Queensland although unfortunately not generating widespread relief rain. Although there is some uncertainty in MJO predictions at present, it is looking like the next active MJO should cross northern Australia during late December or early January.

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 the mean time based on a Consistently Negative SOI phase at the end of November and historical rainfall records there is a relatively low 20 to 40% chance of getting above median rainfall for December to February throughout most of Queensland. The exception is for the far western border regions of Queensland where there is a marginally higher 40 to 50% chance of getting above median rainfall for December to February.

As this is my last update for the year I'd like to wish all you all a merry and wet Christmas and New Year. If anyone is interested I'm happy to give climate presentations at meetings or field days etc. To contact me e-mail david.mcrae@climatechange.qld.gov.au

The full story

SOI in Consistently Negative Phase Dave McRae, Qld Climate Change Centre of Excellence, 08/12/09.

The monthly SOI value for October was minus 14.8 and for November was minus 6.4. Based on these values the SOI is in a Consistently Negative SOI phase at the end of November. An analysis of historical rainfall records and a Consistently Negative SOI phase indicate that there is a relatively low 20 to 40% chance of getting above median rainfall for December to February throughout most of Queensland. The exception is for the far western border regions of Queensland where there is a marginally higher 40 to 50% chance of getting above median rainfall for December to February.

It is worth noting that even for those areas with a relatively low chance of getting above median summer rainfall, that as we are entering our rainfall season there is still a reasonable chance of getting some useful relief rain.

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 December to February in the following years since 1900 that have had a 'Consistently Negative' SOI phase at the end of November; 1901, 1911, 1913, 1914, 1919, 1925, 1939, 1940, 1941, 1944, 1951, 1963, 1965, 1972, 1977, 1982, 1991, 1992, 1994 and 1997. It can be useful to find out what rainfall and farming conditions where like in your area for December to February in those years. For more information try www.longpaddock.qld.gov.au or Rainman StreamFlow.

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%.

The last passage of the MJO crossed Australian longitudes during the second half of November. It triggered patchy and isolated storms and showers throughout Queensland although unfortunately not generating widespread relief rain. Although there is some uncertainty in MJO predictions at present, it is looking like the next active MJO should cross northern Australia during late December or early January.

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

Lately there has been some press coverage of a recently released Queensland Government technical assessment of the Queensland pastoral beef industry. The report aims to determine the 'net carbon' position of an example beef enterprise at the farm gate level (i.e. total on-farm emissions minus total sequestration of agriculture) using the latest available data. This assessment is not definitive rather an attempt to help the Government and industry understand the issue of net carbon position in relation to agriculture. For a copy of the report go to www.dpi.qld.gov.au/27_15803.htm

For those interested the Queensland Government website www.climatesmart.qld.gov.au/ provides information on climate change, climate change mitigation and adaptation strategies and funding opportunities for business and communities to identify opportunities and increase knowledge on how to improve energy, water and waste efficiency.

According to the latest ENSO Wrap-up from the Bureau of Meteorology www.bom.gov.au/climate/enso a typical El Niño sea surface temperature pattern remains clearly present in the tropical Pacific Ocean. Sea surface temperatures have continued to warm in the central and eastern Pacific Ocean to a level that has not been observed since the 2002 El Niño event.

Sub-surface sea temperatures (to a depth of 300 plus metres) throughout the central and eastern tropical Pacific have also continued to warm, with temperatures as much as 5 degrees C above normal in some regions. Rainfall patterns over eastern Australia for the past three months have also broadly been in keeping with the impact of an El Niño event.

This pattern is expected to continue with five of the six international models surveyed, forecasting sea surface temperatures to remain above El Niño threshold levels throughout summer. None of the surveyed climate models are forecasting any potential return of La Niña like conditions. Given that El Niño events (and La Niña's) tend to persist from autumn to autumn, this is not a surprise.

The Bureau of Meteorology (www.bom.gov.au/climate) has also just issued its seasonal temperature outlook for summer with the warning of likely above average temperatures. For example there is a 60 to 70% chance of getting above long term median maximum temperatures for December to February throughout most of Queensland. As well there is a 60 to 80% chance of getting above long term median minimum temperatures for December to February throughout most of the state. This is mostly due to the El Niño pattern currently persisting in the Pacific Ocean.

It is worth remembering that 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.

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.

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 or e-mail david.mcrae@climatechange.qld.gov.au