SOI Rises (Dated 22/01/02)
The Southern Oscillation Index has been remarkably variable over recent months with the 30-day average (as of the 22nd January) rising from minus 13 at the start of the month to plus 2.7.
Despite the recent fluctuations in SOI value, the chance of above median rainfall remains relatively low for the south east quarter of Queensland. However there has been a slight improvement in the rainfall outlook for parts of south west, central west and north west Queensland. While the combination of being in the summer rainfall season and a slight lift in rainfall probabilities indicates the potential for relief rain for much of Queensland, unfortunately an El Nino pattern can still be found in the Pacific. Therefore there remains only a low chance of getting those well above average rainfall totals required to break the drought pattern.
Historical rainfall records for individual locations and the recent SOI pattern can be used to highlight this. For example at Gatton in the Lockyer Valley there is only a low chance (27%) of receiving median rainfall (300mm) during January through to March 2003. There is however, an 87% chance of receiving 200mm (i.e. 2/3 of the median rainfall) during January through to March. Historically though there is 0% chance of getting more than 500mm (or flooding rains) during January to March with the recent SOI pattern.
It will be very interesting to see what changes occur in ocean and atmospheric patterns over the next 3 to 5 months. Changes during this period are crucial as autumn is the usual transition period for El Nino events. We will continue to monitor the situation on a regular basis and provide information on when and if there has been some measurable breakdown of this pattern.
I also urge people to be somewhat cautious of predictions of when the drought is going to break. As many people would be aware it may take several months of continual above average falls in many regions and often the breakdown of major drought events does not occur evenly across all affected areas.