MJO Delayed Dave McRae 19/02/07
An MJO event was expected around the middle of February (16th to 20th). However the expected MJO event has been delayed until later in the month.
It will be interesting to see what if any rainfall events it triggers. Widespread rain is still needed to improve the currently poor crop outlook for most of Queensland and northern NSW summer cropping region and improve soil moisture levels for the coming winter cropping season.
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). For more information try www.apsru.gov.au/mjo/
Based on a "Near Zero" SOI phase and historical rainfall records, there is a 40 to 60% chance of getting median rainfall throughout most of Australia for February through to the end of April.
While the chance of getting median rainfall is only around 50% there is a reasonable (above 70% chance) of getting some useful relief rain throughout Queensland. For example Miles has an 80% chance of getting at least 100 mm during February to April.
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 February to April in the following years since 1900; 1900, 1903, 1907, 1909, 1910, 1924, 1925, 1927, 1932, 1936, 1945, 1947, 1948, 1949, 1960, 1965, 1972, 1975, 1979, 1981, 1984, 1985, 1988, 1990, 1991 and 1994. Work out your long term average rainfall for February to April and see how many times rainfall was well below, well above or close to average.
For example at Stanthorpe, below average rainfall for February to April in those years was recorded 5 times, close to average rainfall was recorded 14 times with above average rainfall recorded 7 times. Therefore rainfall during February to April at Stanthorpe is more likely to be closer to average than well below or well above average.
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 more on rainfall probabilities for your location refer to Rainman StreamFlow. Daily updates on the SOI are available on (07) 46881439. For more information contact the DPI&F Call Centre on 132523.