SOI message 6th June 2001. We are currently watching developments in the Pacific Ocean very closely after the largest "westerly wind burst" this year was recorded in the western Pacific Ocean two weeks ago. At this crucial time of year, this wind event has set up the preconditions for an El Niño.
The Southern Oscillation Index (SOI) dropped through May resulting in a "Rapidly Falling SOI phase" for April-May. From historical records, we see that in only 30 to 50% of the years that also had a Rapidly Falling May phase, did most of the state get at least median June-July-August rainfall totals. That is, there is a 50 to 70% chance of below-median rainfall for much of Queensland. In southern Qld the areas with the lowest chance, 20%-30%, of exceeding the median June-August rainfall total are in the far western and south west Downs, the Warrego and Maranoa. It is important to remember that we can have very low rainfall probabilities without being in an El Niño.
Crop management strategies will vary significantly depending on levels of soil moisture and actual planting opportunities. * Ensure you update your forecast at the end of each month.
Review of Climate Forecasts and Information
Climate pattern and SOI 'phase'. Based on the latest values and trends of the SOI, the probabilities of receiving above-median rainfall over the June-July-August period is between 20 and 60% for much of Queensland, although there are exceptions.
In Queensland, exceptions include small areas of the Central Highlands and Cape York that have chances of between 50 and 70% of above-median June-August rainfall totals.
Regions of southern Queensland that were drought affected over much of the previous two growing seasons have probabilities between 30% and 50% of getting at least June-August median rainfall. The areas with the lowest chance, 20%-30%, of exceeding the median June-August rainfall total are in the far western and south west Downs, the Warrego and Maranoa.
Coastal districts east of the Divide have the greatest likelihood of above-median June-August total rainfall in NSW (60-70% chance). The majority of the areas of NSW, Victoria, and South Australia have probabilities ranging between 20 and 50%.
Note that a 70% probability of receiving the long-term median for a location also means there is a 30% probability of not receiving the median for that location. These probability values are simply statements of fact referring to the history of rainfall events for particular locations over the past 100 years.
Sea-surface temperatures (SSTs). Sea surface temperatures in the key regions of the eastern equatorial Pacific Ocean are mainly close to average or slightly warmer than average. Although the recent westerly wind burst has created the necessary preconditions for an El Niño, it has not been included in some of the General Circulation Model analyses and forecasts. Most of the GCMs, i.e. 8 out of a selected 12, are predicting that we will be in a "neutral" event in 6 months time.
Pasture Growth forecasts. The probabilities of obtaining median pasture growth or better during the May-June-July period are below 50% for most of the state, although in the south-east they are mostly above 80%.
30 to 50-Day Oscillation. The 30-50 day oscillation is next due to influence Queensland around the 2nd week of July.
More detailed information for your location can be obtained from the Australian Rainman software package. Also additional information is available on our internet site 'The Long Paddock', or by phoning Col Paull (07 3896 9587), Dr Allyson Williams or Dr Roger Stone (climatologists) on 07 4688 1407, 07 4688 1293 or Roger's Mobile 041 255 9408. Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Queensland Centre for Climate Applications, has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter. Contributions by Bureau of Meteorology are gratefully acknowledged. This message will next be updated at the beginning of July.