Outlook improves, El Nino decays Dave McRae, QCCCE, 06/05/10
The monthly value of the SOI rose in value from minus 10.8 for March to plus 12.1 for April placing the SOI in a Rapidly Rising phase.
Based on historical rainfall records and a Rapidly Rising SOI phase at the end of April, there is a reasonable 60 to 80% chance of getting above median rainfall across parts of north-west, central and south-east Queensland during May to July. Across the rest of the state there is a 40 to 60% chance of getting above median rainfall for May through to the end of July.
For example Tara has an 75% chance of getting above its May to July median rainfall of 98mm, Roma and Talwood have a 70% chance of getting above their May to July median rainfall of 90mm and 100mm respectively, Kingaroy has a 65% chance of getting above its May to July median rainfall of 105mm, and Pittsworth has a 60% chance of getting above its May to July median rainfall of 109mm.
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%.
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 May to July in the following years since 1950 that have had a Rapidly Rising SOI phase at the end of April: 1954, 1961, 1984, 1985, 1989, 1990,1999 and 2009. Find out your average rainfall for May to July and see how many times rainfall was well below, well above or close to average during May to July in the listed years. For more information on historical rainfall data for your region try Rainman Streamflow.
The 30day average of the SOI as of the 7th May is plus 9.3. If the SOI remains in positive values over coming months it increases the chance of getting at least an average winter and spring. And unlike this time last year, sea surface temperature patterns are indicating the decline of an El Niño and not the development of one. For more climate related information, updates on SOI values and the latest outlook map go to www.longpaddock.qld.gov.au
According to the latest ENSO Wrap-up from the Bureau of Meteorology, the 2009/2010 El Niño event has decayed. This change has been reflected by a maintained increase in value of the SOI, trade winds and cloud cover in the tropics returning to near normal and both surface and sub-surface sea surface temperatures in the eastern Pacific cooling to below El Niño thresholds.
This decline in the 2009/10 El Niño event is consistent with the surveyed global climate model projections which all have indicated for some months the continual breakdown of the El Niño climate pattern and return to a neutral ENSO climate pattern. Interestingly some of the surveyed models now indicate the potential development of a La Niña or La Niña like climate pattern during winter. Also of interest is that SST's around eastern and northern Australia are warmer than normal which may assist the inflow of moisture across the Queensland coastline.
However as autumn is the key transition time for the development and breakdown of El Niño and La Niña events we recommend monitoring SST and SOI values. Updates on the development of these climate patterns can be found at www.bom.gov.au/climate/enso or www.longpaddock.qld.gov.au or www.cpc.ncep.noaa.gov
Based on soil moisture levels and the seasonal climate outlook at the end of April, there is greater than a 70% chance of getting above median wheat yields throughout most of southern Queensland's wheat growing regions for the 2010 season. Throughout the rest of the state's wheat growing regions, there is a 40 to 70% chance of getting above median wheat yields for the 2010 season.
The current state wheat outlook shows a forecast median yield this year as 1.70 t/ha, which is above the long-term median of 1.41 t/ha. However, it should be noted that it is very early in the growing season and the situation can change considerably as the season progresses. Good rainfall during the next couple of months will be needed to ensure widespread planting.
The regional wheat crop outlook is based on the assumption of cropping after a summer fallow and does not take into account effects of poor crop nutrition or damage due to pests, diseases, heat or frosts. For more information on the seasonal crop outlook contact Andries Potgieter, DEEDI on (07) 4688 1417.
For those looking for a planting rain opportunity the next passage of the MJO is expected to cross Australian longitudes during the middle of May. It last travelled eastward across Australian during late March/early April. This coincided with the development of Tropical Cyclone Paul in the Gulf of Carpentaria.
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. It is worth noting that 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 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.