Climate Watch 18/08/04
Fall in wheat yield outlook
In what shouldn't be a surprise to anyone, the below to very much below average rainfall across Queenslands cropping belt over May to July has caused a significant drop in the potential wheat yield outlook.
At the end of July, current soil water conditions and seasonal rainfall outlook for August to October indicate a very low 0-30% chance of getting above the long-term median wheat yield for the grain growing shires of Queensland (refer to map). Rain over the next few weeks across the entire cropping region would help improve the overall crop condition for those areas that where planted especially as the crop goes through the flowering and grain filling stages.
This wheat 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 and distribution of planting rain within a shire. For more information on the APSRU/DPI&F regional wheat crop outlook contact Andries Potgieter on (07) 46881417 or try www.dpi.qld.gov.au/climate where a full copy the wheat crop outlook can be found.
In the mean time the SOI has remained in negative values and as of the 18th August the 30day average is minus 9.6. Based on the recent pattern of the SOI there is only a low (10 to 40%) chance of getting above the long-term median rainfall across Queensland.
For example Emerald only has a 25% chance of getting at least its long term August to October median rainfall of 75mm. This also means that there is a 75% chance of NOT getting at least 75mm through to the end of October.
Another way of looking at this is that in 2 to 3 years out of 10 (or one quarter of years) with the current SOI pattern, Emerald has received at least 75mm for August to October. Therefore in 7 to 8 years out of 10 (or three quarters of years), Emerald has gotten less than 75mm for August to October.
Please note that this does not mean we do not get any rainfall at all. It simply means that most years like the current year result in below the long-term median rainfall overall.
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 August to October in the following years; 1997, 1994, 1993, 1992, 1987, 1982, 1977, 1972, 1946, 1941, 1940, 1919, 1914, 1911 and 1905 and compare the rainfall recorded with your 'normal' rainfall for August to October.
For example at Emerald, historical records show that with this SOI pattern for August to October below average rainfall was recorded ten times, near average rainfall was recorded once and above average rainfall was recorded three times.
Information on what rainfall patterns where like for August to October in those years can be found at www.longpaddock.qld.gov.au or in Australian Rainman.
For there to be an overall improvement in the seasonal outlook for Queensland, it would help if the SOI rose to a "Consistently Positive" pattern for a couple of months at least. It's also worth remembering that for northern Australia we are still in our "traditional dry season" of July, August and September.
For more information give us a call through the DPI&F Call Centre on 132523.