SOI message 13th December 2000 The average SOI over the previous 30 days remains ' strongly' positive at +24.8 (up to 13th December). The impact of a high SOI value on rainfall varies across the state. The probabilities of getting or exceeding the long-term median rainfall during the total December-February period are now 60-80% in most of eastern Queensland. Parts of southern Qld and the central-west have comparatively low probabilities at about 50%.
Review of Climate Forecasts and Information
As mentioned in previous releases, the dry conditions experienced over much of Qld (especially southern areas) have been due to the sub-tropical high-pressure ridge tracking further north than usual this year. This pattern would not normally be expected to persist beyond spring, suggesting some easing of the dry conditions is now probable.
Climate pattern and SOI 'phase'. The latest SOI 'phase' analysis suggests reasonably high probabilities (60-70%) of receiving the long-term median rainfall during the November-January period for most of the eastern States of Australia. Exceptions are small areas along the east coast, parts of far north-west Qld and central-western Qld, far central-western Qld, southern inland NSW where probabilities are 50-60%; most of Victoria and Tasmania where probabilities are 40-60%. 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. Sea-surface temperatures in the Pacific Ocean are mostly close to 'average' at present, but there are large areas of warm anomalies west of the International Dateline (including Gulf of Carpentaria to Kimberley). However, temperatures of waters off the coasts of eastern Qld and northern NSW are around average.
Some general circulation models are suggesting the potential for warming in the eastern equatorial Pacific Ocean over the next 6-9 months. We will watch the situation closely to determine any potential for El Niño development, or otherwise, in 2001. Close monitoring of sea-surface temperature patterns over the next six months is suggested.
30- to 50-Day Oscillation. The next passage of the 30- to 50-Day Oscillation over Qld is expected about the third week in November.