Useful Relief Rain 07/10/03
Useful rainfall triggered by the passage of the MJO (or '40day wave') was recorded across much of south eastern Queensland during the first 7 days of October. However the question remains as to whether the rest of the state will also receive some relief from widespread dry conditions.
These dry conditions were intensified by the well below average rainfall recorded across most of Queensland for September. The lack of rain in September compounded the problems caused by the prolonged drought that most of Queensland is currently affected by.
Therefore many producers (especially those irrigators looking for irrigation water supplies for the summer cropping season) are looking for a vast improvement in overall seasonal conditions.
Based on the recent pattern of the SOI there is a 40 to 50% chance of getting above the long term October to December median rainfall for most of Queensland.
For most of South Australia, New South Wales, Victoria and Tasmania and the southern section of Western Australia there is a 40 to 60% chance of getting above the long term October to December median rainfall. Probabilities are marginally lower at 30-40% for much of the Northern Territory and the northern section of Western Australia.
While these figures are an improvement over this time last year, they are not high enough to guarantee immediate state wide drought breaking rain at this stage. These probabilities will be reviewed at the end of the month.
Preliminary research has also shown that with this type of SOI pattern there is increased potential for severe storm activity (including hail) across southern Queensland and northern NSW.
The 30day average of the SOI has risen slightly since the start of the month and as of the 8th October is plus 2.7. Daily recorded SOI updates are available on 07 46881439.
For those interested in following historical SOI/rainfall patterns more closely, it may be useful to find out what rainfall and farming conditions where like in your area for October to December in the following years - 1999, 1995, 1992, 1986, 1985, 1984, 1980, 1878, 1968, 1966, 1963 and 1961.
Information on what rainfall patterns where like in those years is available at www.longpaddock.qld.gov.au or in AUSTRALIAN RAINMAN.
When using any probability based forecast system, it is important to consider the alternate view. For example, Kingaroy currently has an 80% chance of getting at least 150mm over October to December. However, this also means that there is a 20% chance of not getting at least 150mm over this period.
Another way of looking at this is that in 8 years out of 10 (or slightly more than three quarters) with the current SOI pattern, Kingaroy has received more than 150mm for October to December. Therefore in 2 years out of 10 (or slightly less than one quater), Kingaroy has gotten less than 150mm for this period.
The latest version of 'Rainman StreamFlow' has just been released. Many new features have been introduced and to highlight these advances free copies of this program that 'time out' in 12 months are available from Land and Water Australia on 1800 776 616.