Seasonal Climate Outlook Message for September to December 2005

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Climate Watch 05 September 2005

SOI in Falling Phase

The monthly value of the SOI for July was plus 1.6 and for August was minus 6.5 putting the SOI in a "Rapidly Falling" phase. Based on this SOI phase the chance of receiving well above average rainfall across most of the state for September to November is low with rainfall more likely to be average to below average.

Generally across Queensland there is less than a 50 to 60% chance of getting above median rainfall for September to November. Some locations in Queensland such as in the southern and central coastal strip and into parts of the southern and central west have a lower 20 to 40% chance of getting above median rainfall (refer to map).

For example, Atherton has a 60% chance of getting above its September to November median rainfall of 102mm; Townsville, Rockhampton and Gatton have a 40% chance of getting above their September to November median rainfalls of 68mm, 140mm and 170mm respectively; Tambo and Millmerran have a 33% chance of getting above their September to November median rainfalls of 77mm and 150mm; and Eromanga has an 18% chance of getting above its September to November median rainfall of 32mm.

It is worth noting that September has a low median monthly rainfall value for many locations in Queensland. As of the 5th September the 30-day average of the SOI is minus 3.5. Daily updates on the SOI are available on (07) 46881439. The latest rainfall probability maps are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au.

For more information contact the DPI&F Call Centre on 132523 or (07) 3404 6999.

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Climate Watch 06 September 2005

SOI in Falling Phase

The monthly value of the SOI for July was plus 1.6 and for August was minus 6.5 putting the SOI in a "Rapidly Falling" phase. Based on this SOI phase the chance of receiving well above average rainfall across most of the state for September to November is low with rainfall more likely to be average to below average. Generally across Queensland there is less than a 50 to 60% chance of getting above median rainfall for September to November.

Some locations in Queensland such as in the southern and central coastal strip and into parts of the southern and central west have a lower 20 to 40% chance of getting above median rainfall. For example Atherton has a 60% chance of getting above its September to November median rainfall of 102mm; Townsville, Rockhampton and Gatton have a 40% chance of getting above their September to November median rainfalls of 68mm, 140mm and 170mm respectively; Tambo and Millmerran have a 33% chance of getting above their September to November median rainfalls of 77mm and 150mm; and Eromanga has an 18% chance of getting above its September to November median rainfall of 32mm.

It is worth noting that September has a low median monthly rainfall value for many locations in Queensland. As of the 5th September the 30-day average of the SOI is minus 3.5. Daily updates on the SOI are available on (07) 46881439.

A low chance of above median rainfall (20 to 40%) for September to November can be found in central and coastal NSW, the northern half of South Australia, across much of Western Australia extending into much of the Northern Territory. For most of Victoria and Tasmania there is 50 to 70% chance of getting above median rainfall.

This forecast does not indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full three-month period and does not suggest that any expected rain will fall evenly across these three months. We recommend referring to Rainman StreamFlow for more information for your location.

Recently the MJO has been hard to pin-point due to strong monsoonal activity over India and SE Asia as well as convection over the South China Sea. It is next expected to influence our region late September/early October.

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) across much of Queensland. For more information on the MJO including its location try www.apsru.gov.au/mjo/ or try 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 over September to November in the following years; 1902, 1921, 1934, 1936, 1953, 1957, 1979, 1986, 1989, 1990, 1991, 1997 and 2002 and compare the rainfall recorded with your median rainfall for September to November. Information on what rainfall patterns where like for September to November in those years can be found in Rainman StreamFlow.

As with any probability based system it is important to consider the opposite aspect. Goondiwindi for example has a 75% chance of getting above 80 mm for September to November. This also means that there is a 25% chance of NOT getting 80 mm. Another way of looking at this is that in around seven to eight years out of ten historically (or around three quarters) with the current SOI pattern, Goondiwindi has received at least 80 mm over September to November. Therefore in two to three years out of ten historically (or around one quarter of the time), Goondiwindi has gotten less than 80 mm over September to November.

When looking at rainfall probabilities for your area it may make it easier to think of them in these terms:

1. Probabilities above 80% highlight a high chance 2. Probabilities above 60% highlight an above average chance 3. Probabilities below 40% highlight a below average chance 4. Probabilities below 20% have a low chance

According to information from the Bureau of Meteorology "El Niño wrap up" at www.bom.gov.au/ key indicators in the Pacific suggest that the likelihood of a classic El Niño event developing this year has been substantially reduced.

In terms of output from 12 surveyed reputable ocean or coupled ocean/atmosphere forecast models, 9 are showing a neutral SST pattern through to December with 2 showing an El Niño SST pattern and 1 showing a La Niña pattern. For more information on conditions in the Pacific try the IRI for Climate Prediction at http://iri.ldeo.columbia.edu/ or the US Climate Prediction Centre at www.cpc.ncep.noaa.gov/

The number of drought declared shires in Queensland has remained steady. As of the 5th September there were 61 shires and 7-part shires drought declared under State government drought processes. This is approximately 60.6% of the land area of the State. There are also 104 Individually Droughted Properties (IDPs) in a further 17 shires. As well there is a Commonwealth Government Exceptional Circumstances Declaration covering 55.6% of the state.

Information regarding drought declarations can be obtained from your local DPI Stock Inspector or the Rural Risk Strategies Unit. The unit can be contacted through the DPI&F Call Centre on 132523 or on (07) 3239 3181. For a full list of drought declared shires and the latest seasonal conditions report go to www.longpaddock.qld.gov.au/

In terms of using climate information I've developed a list of key points 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.

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).

Be sure of your source of information and what it is actually suggesting. Do not take a quick grab of information from any source including radio, TV or the internet and assume what you heard/saw/read applies to your location.

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.

A key point to remember with any probability based forecasts is that they are just that - probabilities and not definitive forecasts. Therefore the opposite always applies eg 70-30; 30-70. So if you are not 'comfortable' with probability based forecasts only use climate information such as the long term monthly averages for your location.

An interesting site http://www.cvap.gov.au/mastersoftheclimate/ 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.