Seasonal Climate Outlook Message for March to June 2005

The bottom line

Chance of some relief rain Dave McRae 31st April 05

The MJO (or 40-day wave) is due in early April and will hopefully trigger some widespread and much needed relief rain. It can presently be found in the Indian Ocean and interestingly, has the strongest signal it has had for a number of months. It is worth noting though that this late in the northern wet season it would be unusual to see widespread monsoonal activity as a result of the MJO. According to the Bureau of Meteorology though there is some potential for this MJO to trigger the development of a low-pressure system in the Coral Sea.

If this MJO does trigger widespread rain especially in central and southern Queensland it would prove a challenge to those producers with sorghum and cotton harvesting to be completed.

The SOI has maintained an upward trend from minus 29.2 at the end of February. As of Wednesday the 30th March, the 30-day average was minus 1.3. Based on a 'Rapidly Rising' SOI phase over February and March, the chance of average to above average rain for April to the end of June across most of Queensland is generally around 50% with a few regions mainly across central Queensland lower at 30 to 40%.

The full story

Rainfall probabilities for April to June for Queensland (31st April 05)

Based on a 'Rapidly Rising' SOI phase over February and March, the chance of average to above average rain for April to the end of June across most of Queensland is generally around 50% with a few regions mainly across central Queensland lower at 30 to 40%.

For example, there is around a 50% chance of getting above their April to June average rainfall of 90 mm, 90 mm, 65 mm and 45 mm for Dalby, Dulacca, Charters Towers and Jundah respectively with Mt Isa having a slightly higher 55% chance of getting above its April to June average rainfall of 25 mm. This compares to a 35% and 33% chance of getting above their April to June average rainfall of 90 mm and 80 mm for Springsure and Emerald.

As we have stated regularly, for there to be an overall widespread improvement in conditions across the state, it would help if the SOI went into positive values for a couple of months at least. Daily updates on the SOI are available on (07) 46881439. The latest rainfall probability maps for Queensland, Australia and the world are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au

Other states

Based on a Rapidly Rising SOI phase at the end of March and historical rainfall records, the chance for average to above average rain for April to June across Victoria, Tasmania, South Australia, Western Australia and New South Wales is generally between 40 to 60% with some regions as low as 30%. For the Northern Territory the chance of getting average to above average rainfall is generally between 50 to 70%.

It is worth noting that this doesn't mean there will be no rainfall at all for the 3-month period for those areas with low rainfall probabilities. What it does means though, is that rainfall recorded for March to the end of May in the affected areas will, more likely than not, be below average for this time of year.

Because rainfall probabilities and median rainfall levels vary between regions, we recommend referring to Rainman StreamFlow for more specific information. Otherwise call the DPI Call Centre on 13 25 23 or (07) 3404 6999. This forecast doesn't indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full 3-month period and doesn't suggest that any expected rain will fall evenly across these 3 months.

The intra-seasonal oscillation (or MJO)

The MJO (or 40-day wave) is due in early April and will hopefully trigger some widespread and much needed relief rain. It can presently be found in the Indian Ocean and interestingly, has the strongest signal it has had for a number of months.

It is worth noting that this late in the summer rainfall season it would be unusual to see widespread monsoonal activity. According to the Bureau of Meteorology though there is some potential for this MJO to trigger the development of a low-pressure system in the Coral Sea.

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 for more technical blurb try www.bom.gov.au/climate/tropnote/tropnote.shtml

Understanding probabilities

As with any probability based forecast system it is important to consider the opposite aspect. For example, Springsure in central Queensland has a 33% chance of getting above its normal April to June rainfall of 90 mm. This also means that there is a 67% chance of NOT getting the 90 mm over April to June.

Another way of looking at this is that in around 3 years out of 10 historically (or around one third) with the current SOI pattern, Springsure has received at least 90 mm over April to June. Therefore in 7 years out of 10 historically (or around two thirds), Springsure has gotten less than its normal 90 mm over April to June.

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

Analogue Periods

Many people like to follow the relationship between the SOI and rainfall patterns in more detail. To do that, have a look at what happened in your area over April to June in the following years; 1990, 1988, 1986, 1973, 1970, 1969, 1964, 1960, 1959, 1952, 1947, 1937, 1935, 1931, 1927, 1914, 1913, 1908, 1903 and 1902 compare the rainfall recorded with your 'normal' rainfall for April to June.

Information on what rainfall patterns where like for April to June in those years can be found at www.longpaddock.qld.gov.au or in Australian Rainman.

Future ENSO development

At present there are a number of 'early warning signs' that suggest the development of an El Niño in 2005 is a possibility. As well as the recent drop in value of the SOI, these include a marked increase in sub-surface sea temperatures, strong westerly wind bursts in the eastern Pacific and a resulting Kelvin Wave, all of which can trigger the changes in ocean and atmospheric patterns needed for an El Niño event.

However, the development of an El Niño event in 2005 is by no means a certainty. For a start there will most likely need to be more strong westerly wind bursts in the Pacific over the next few months if an El Niño is likely to develop. Key times to watch out for those will be after the next passage of the MJO (or 40-day wave).

As well El Niño events usually develop in mid to late autumn so there is still some time for conditions in the Pacific to change.

However given the physical evidence our policy remains to recommend a cautious approach when considering the longer-term outlook this year. As part of the DPI&Fs' response to these changes we have initiated an "El Niño watch" and will regularly monitor any developments in the Pacific and pass on this information on as it becomes relevant.

To find out more on conditions in the Pacific try the Bureau of Meteorology "El Niño wrap up" at www.bom.gov.au/climate/enso/ or the International Research Institute for Climate Prediction at http://iri.ldeo.columbia.edu/news/monthlyproduct.html or the US Climate Prediction Centre at www.cpc.ncep.noaa.gov/ For the latest sea surface temperature maps have a look at www.cpc.ncep.noaa.gov/products/ or at www.longpaddock.qld.gov.au/

Cyclone Activity for 2004/05 Season

In a media release at the start of the cyclone season the Bureau of Meteorology www.bom.gov.au stated that based on the best available and most recent information the lengthy run of relatively quiet cyclone seasons was likely to continue for Queensland with the number of tropical cyclones in the Coral Sea this season having only an outside chance of exceeding 2 or 3, and not all will cross the coast.

In a reflection of the lack of cyclone activity the Bureau also state that the last 15 years have been relatively quiet in terms of both cyclone activity in the Coral Sea and the incidence of significant cyclone impacts along the Queensland coast with the past 3 cyclone seasons being particularly unusual in that only 1 cyclone has crossed the east Queensland coast ("Fritz" a low Category 1 in the far north last February).

For more information on cyclones try the Queensland Tropical Cyclone Warning Centre at www.bom.gov.au/weather/qld/cyclone

Sorghum Crop Yield Outlook

The current sorghum outlook for Queensland and northern NSW as a whole has a forecast median yield at the end of February this year of 2.15 t/ha. This is just below the long-term median of 2.20 t/ha and falls into the 39th percentile relative to all years (1901-2003). However among local regions there is much variation in the outlook.

Central Queensland has slightly below average crop yield expectations falling in the 49th percentile of all years. Southern Queensland shows very much below average crop yield expectations falling in the 21st percentile of all years while most areas in northern NSW show predicted yield outcomes very much above normal falling in the 76th percentile rank relative to all years.

With maturity being reached for most crops, projected rainfall for the remainder of the growing season will have little to no affect on the final realised yield. However, a wet finish will increase the chance of diseases or pests and could reduce yield outcomes.

This sorghum yield outlook is based on a shire scale. It does not take into account crop area planted and is purely a yield forecast. Nor does not take into account individual property circumstances or the effects and damage from poor crop nutrition, pests, diseases, frosts, heat stress and distribution of planting rain within a shire. For more information on the sorghum crop yield outlook contact Andries Potgieter on (07) 46881417 or try www.dpi.qld.gov.au/climate where a full copy of the sorghum crop outlook can be found. For detail on farm level crop management strategies for CQ and SQ access www.dpi.qld.gov.au/fieldcrops

Key Points To Consider When Using Climate Information

When incorporating climate forecasts into management decisions, it could be worthwhile to consider some of the following general rules of thumb developed from feedback from climate users.

1. 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.

2. Decisions should never be based entirely on one factor (such as a weather or climate forecast). As always, all factors that could impact of the outcome of a decision (such as soil moisture/type, crop, pasture type/availability, commodity prices, machinery, work force, transport, finance, costs, seasonal outlook etc) should be considered.

3. Access local information or at least be aware of the long-term median for your location so you can correctly interpret the forecast.

4. Do a cost benefit analysis of any decision with a climate risk factor eg What will I gain if I get the desired outcome from this decision? What will I lose if I don't get the desired outcome from this decision? What other cost neutral options do I have if any?

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.