Seasonal Climate Outlook Message for October to January 2006

The full story

SOI Rapidly Rising 03/10/05

The monthly value of the SOI rose from minus 6.5 at the end of August to plus 3.3 at the end of September placing it in a "Rapidly Rising" phase. Based on this SOI phase and historical rainfall records there is a 50 to 70% chance of getting above median rainfall for October to December across most of Queensland. For example Roma has a 70% chance of getting above its October to December median rainfall of 165mm, Goondiwindi has a 60% chance of getting above its October to December median rainfall of 165mm and Dalby has a 50% chance of getting above its October to December median rainfall of 210mm.

As of the 3rd October the 30-day average of the SOI is plus 2.9. 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.

There is a 20 to 40% chance of getting above median rainfall during October to December across much of southern and western NSW, parts of northern and western South Australia and extending into the Northern Territory. For the rest of Australia the outlook is patchy with probabilities of getting above median rainfall varying from 50% to 80% in a few locations on the Western Australian coastline. Therefore we recommend referring to Rainman StreamFlow for more information for your location.

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.

According to information from the Bureau of Meteorology "El Niño wrap up" at www.bom.gov.au/ the key indicators (SOI, trade winds and sea surface temperatures) confirm the persistence of a neutral sea surface temperature and climate pattern in the Pacific. This pattern would therefore be unlikely to change before the end of the year.

In terms of output from 12 surveyed reputable ocean or coupled ocean/atmosphere forecast models, 10 are showing a neutral SST pattern through to February with 1 showing an El Niño SST pattern and 1 showing a La Niña pattern. For more information on conditions in the Pacific try 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 20th 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 15 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 (07) 3239 3181. For a full list of drought declared shires and the latest seasonal conditions report go to www.longpaddock.qld.gov.au/

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 October to December in the following years; 1903, 1908, 1921, 1922, 1926, 1931, 1936, 1949, 1970, 1979, 1983, 1989 and 2001 and then compare the rainfall recorded with your median rainfall for October to December.

For example at Emerald below median rainfall for October to December in those years was recorded twice, close to median rainfall was recorded 5 times and above median rainfall was recorded 6 times. Information on what rainfall patterns where like for October to December in those years can be found in Rainman StreamFlow.

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 It is next expected to influence our region mid-October.

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. Charters Towers for example has a 70% chance of getting above 100 mm for October to December. This also means that there is a 30% chance of NOT getting 100 mm. Another way of looking at this is that in around seven years out of ten historically (or around three quarters) with the current SOI pattern, Charters Towers has received at least 100 mm over October to December. Therefore in three years out of ten historically (or around one quarter of the time), Charters Towers has gotten less than 100 mm over October to December.

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

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.