Seasonal Climate Outlook Message for March to June 2000

The bottom line

SOI message 29th March 2000 The average SOI over the previous 30 days is +8.1 . Based on the SOI, the probabilities of exceeding median rainfall during the total March to May period are little different from the 'normal' for this time of year in most of the eastern States of Australia, 60-80% in much of north Qld, and 30-40 in most of the Burnett in Qld and parts of the northern inland cropping districts of NSW.

The full story

Review of Climatic Forecasts and Information

Based on the latest values and trends of the SOI, the probabilities of receiving above-median rainfall over the total March-May period are little different from the 'normal' for this time of year in most of the eastern States of Australia. Exceptions are much of north Queensland (particularly Charters Towers-Bowen area) where the probabilities are 60-80%; parts of the south-eastern corner of NSW, south-western corner of Victoria and northern Tasmania where probabilities are 60-70%; most coastal and sub-coastal districts of Qld south of Bundaberg and parts of northern inland cropping districts of NSW where they are 30-40%.

The persistent 'cool' sea-surface temperature (SST) anomalies are slowly contracting, indicating that the La Ni¤a may be receding. This is also hinted at by other features such as the slight weakening of the strong easterly winds in the central Pacific Ocean associated with the La Ni¤a.

Forecasts from most experimental general circulation models are currently suggesting that by mid-year the La Ni¤a will have subsided and neutral conditions dominate. However, three climate models indicate the possible development of an El Nino, and sub-surface sea temperatures to the east of Australia are now significantly warmer than normal, in classic 'pre-El Nino' mode. In addition, some early research work suggests the sub-tropical ridge may again be further north than normal this winter which may tend to reduce winter rainfall from the Goondiwindi district through to the Central Highlands. As these indicators provide some cause for concern, regular monitoring of them and the SOI during the autumn 'predictability gap' is recommended.

Combining the rainfall outlook with current soil water and pasture condition, the probabilities of above-median pasture growth during the total February-April period are 60-90% in much of north Qld, central-western Qld, and far central-western Qld.

The next passage of the 30- to 50-Day Oscillation is expected about the end of the first week in April.