Key time for changes 27th March 06
For those looking out to the long term (>6 months) autumn is the key time to watch for developing trends in both the SOI and sea surface temperatures (SST). For example a return to long term sustained positive monthly SOI values would help provide the basis for a widespread improvement in seasonal conditions.
Currently there are some features of a weak La Niña (namely cool sea surface temperatures in the eastern and central Pacific) present in the Pacific Ocean. However this pattern has developed so late in the season that any impact on rainfall in Australia is highly uncertain. According to the output from most climate models this pattern is also unlikely to persist past autumn into winter and spring when the positive impacts for rainfall across Queensland would be greatest. For example of 12 surveyed reputable ocean or coupled ocean/atmosphere forecast models, 11 are showing a continuing neutral SST pattern through to July and one is showing the development of an El Nino SST pattern. For more on conditions in the Pacific try the Bureau of Meteorology at www.bom.gov.au/climate/ahead/