The Science Division of the Department of Science, Information Technology and Innovation (DSITI) considers that, for most of Queensland, there remains an increased probability of below median rainfall for summer (November to March 2015/16). Read more (PDF, 432K, last updated 02:05PM, 9 December 2015)*
DSITI’s seasonal outlooks for Queensland are based on the current and projected state of the El Niño–Southern Oscillation (ENSO) phenomenon and on factors which alter the impact of ENSO on Queensland rainfall (i.e. the more slowly changing extra-tropical sea surface temperature (SST) pattern in the Pacific Ocean).
At this time of year, the prevailing ENSO pattern, as measured by indices such as the Southern Oscillation Index (SOI) or central equatorial Pacific Ocean SST anomalies, offers a useful basis for providing seasonal outlooks for summer.
Currently, 86 per cent of Queensland is drought declared under state government processes - the shires of Burdekin, Kowanyama and Pormpuraaw and the remainder of Isaac and parts of Cook and Whitsunday being added as at 1 November. For some parts of Queensland, the high probability of the current El Niño event continuing further over summer poses a risk of current drought conditions becoming more protracted. This risk should be factored into decision making and allocation of resources. In this context, DSITI’s outlook for summer rainfall should be taken into consideration.
Seasonal rainfall outlook (Dec-Feb 2015/16)
Based on previous years when the SOI has been in a ‘Rapidly Rising’ phase at the end of November, the probability of rainfall being above median for the next three-month period (December to February) is less than 50 per cent for most northern and eastern parts of Queensland. For many western and some southern parts of the state the probability of above median December to February rainfall is higher (50 to 70 per cent).
Summer rainfall outlook (Nov-Mar 2015/16)
DSITI scientists have shown that extra-tropical SST anomalies, when measured in specific regions of the Pacific Ocean in March each year, provide a useful basis for long-lead forecasting of summer (November to March) rainfall in Queensland. The accuracy of this outlook increases as the evolving ENSO-related SST pattern is also taken into account from May through to October. This understanding has been incorporated in an experimental system known as SPOTA-1 (Seasonal Pacific Ocean Temperature Analysis version 1), which has been operationally evaluated by DSITI scientists for over a decade.
As at 1 November 2015, DSITI’s final outlook for summer (November to March 2015/16) indicated a lower than normal probability of exceeding median rainfall for most of Queensland, based on the evolving sea surface temperature pattern across the Pacific.
This final outlook for summer rainfall, which has been consistent since June this year, is closely related to the SST gradient measured across the South West Pacific Ocean in October, and is indicative of the current strong El Niño event.
In summary, it should be noted that:
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