Monthly Climate Statement for December 2016
The Department of Science, Information Technology and Innovation’s (DSITI’s) seasonal outlooks for the Queensland summer are based on the state of the El Niño-Southern Oscillation (ENSO) phenomenon prior to summer, and on factors which alter the impact of ENSO on Queensland rainfall (i.e. the more slowly changing extra-tropical sea-surface temperature pattern in the Pacific Ocean).
The Science Division of DSITI considers that, for most of Queensland, the probability of exceeding median summer (November to March 2016/17) rainfall is higher than normal. This view is based on an analysis of tropical and extra-tropical Pacific Ocean sea-surface temperatures (SSTs) leading up to summer. Read more (PDF, 446K, last updated 11:41AM, 15 December 2016)*
‘El Niño’, ‘La Niña’ and ‘ENSO-neutral’ are phases of the ENSO climate pattern which has a strong influence on Queensland summer rainfall. DSITI closely monitors key ENSO indicators over winter and spring, a period when El Niño and La Niña events tend to form. Over the last three months SST anomalies in the central equatorial Pacific have been at, or close to, La Niña thresholds (depending on definition). The most recent values of the Southern Oscillation Index (SOI) have been near-average.
- Monthly SST anomalies in the Niño 3.4 region of the central equatorial Pacific for September, October and November were -0.6ºC, -0.7ºC and -0.6ºC respectively. As at 10 December, the weekly SST anomaly was -0.6ºC.
- Monthly values of the SOI for September, October and November were +13.8, -4.5 and +0.7 respectively. As at 13 December, the 30-day average SOI value was -0.8.
Although the International Research Institute for Climate and Society and NOAA, in their joint ‘ENSO Diagnostic Discussion’, maintain that “La Niña conditions are present”, the Australian Bureau of Meteorology, in its ‘ENSO-Wrap-Up’, argue that these conditions are weak and unlikely to persist. As discussed, DSITI’s seasonal outlook for summer rainfall (below) does not depend on emerging ENSO patterns, but rather SST conditions which have led up to summer.
Outlook for summer (Nov-Mar 2016/17)
DSITI monitors tropical and extra-tropical Pacific Ocean SSTs and, on this basis, provides a long-lead outlook for the coming summer (November to March). An initial summer rainfall outlook based solely on extra-tropical Pacific Ocean SSTs is produced in April and subsequently updated monthly until the beginning of summer (November). The accuracy of this long-lead outlook increases as the evolving ENSO-related SST pattern is taken into account from May through to October.
As at 1 November 2016, DSITI’s final outlook for summer (November to March 2016/17) indicated a higher than normal probability of exceeding median rainfall for most of Queensland.
It should be noted that seasonal outlooks are probabilistic, rather than deterministic, in nature. For example, if an outlook is described as having a 50 to 70 per cent probability of below median rainfall, there is also a 30 to 50 per cent probability of above median rainfall. Although outcomes with a high probability may be more likely, this does not mean that less probable events will not occur in any given year. Furthermore, an increased probability of above-median rainfall for Queensland will not necessarily result in above-median rainfall throughout all of the state.
Recent rainfall
Rainfall totals for November were well-below average across much of south-eastern Queensland. November rainfall was closer to average in many other parts of the state.
Drought status of Queensland shires
As a result of protracted dry conditions over previous summers eighty-four per cent of Queensland remains drought declared under state government processes.
Tropical cyclones
The Bureau of Meteorology has advised that eastern Queensland is most likely to experience a near-average tropical cyclone season (November to April). On average, two tropical cyclones have made landfall in Queensland during the tropical cyclone season.
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