Monthly Climate Statement for January 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 (SST) pattern in the Pacific Ocean). The Science Division of DSITI considers that there is an increased probability of below median rainfall for most of Queensland for the remainder of this summer (January to March). Read more (PDF, 261K, last updated 02:59PM, 15 January 2016)*
- As at 13 January, the 30-day average SOI value remains very low (-13.5). The monthly value of the SOI was -10.1 in December, compared to -3.2 in November and -21.3 in October. The three-month (October to December) average was -11.5.
- The monthly SST anomaly in the Niño 3.4 region of the equatorial Pacific Ocean was +2.9 ºC in December, compared to +3.0 ºC in November and +2.5 ºC in October. As at 6 January, the weekly Niño 3.4 region SST anomaly was +2.6 ºC.
- The Bureau of Meteorology (ENSO Wrap Up, January 5), notes that the current El Niño has most likely passed its peak strength, with a return to ENSO neutral conditions not likely until late autumn or early winter. Most international global climate models indicate that the current warmth in the equatorial Pacific Ocean SSTs should weaken over autumn.
Eighty six per cent of Queensland has been drought declared since 1 November under state government processes.
- With the exception of those shires in the far-north and far-west of the state which received heavy monsoonal rainfall in late December, most drought declared shires received near-average rainfall from October to December 2015, with rainfall totals being well-below average to extremely-low in some locations.
- Some parts of south-western Queensland have received well-above average rainfall for the first two weeks in January, but elsewhere January rainfall has thus far been below average.
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. Conversely, there was a low probability of drought-breaking rainfall, based on the evolving sea surface temperature pattern across the Pacific.
The final outlook for summer rainfall, which had been consistent since June this year, was closely related to the SST gradient measured across the South West Pacific Ocean in October, being indicative of the current strong El Niño event.
As at 10 January 2016, median summer (November to March) rainfall has yet to be exceeded for most of the state.
In summary, it should be noted that:
- Although the current El Niño pattern is likely to have peaked, it should persist over the remainder of summer (January to March).
- An increased risk of below median rainfall for most of Queensland means that there is also a low probability of widespread drought-breaking rainfall. However, this does not rule out the possibility of localised high rainfall events or mean that below median rainfall will occur across all of the state (see Australia’s Variable Rainfall poster (PDF, 9.3M, last updated 03:09PM, 29 July 2016)*, or the department’s archive of historical rainfall maps).
- Users should also be aware 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, it does not mean that less probable events will not occur in any given year.
- The Bureau of Meteorology, which provides advice on the tropical cyclone season (November to April), has noted, in regard to eastern Australia, that El Niño shifts the odds toward both fewer cyclones and a later first cyclone crossing of the season. Although the probability of tropical cyclones is lower than normal, the risk of a tropical cyclone making landfall remains over the remainder of summer.
- On average, two tropical cyclones make landfall in Queensland during the tropical cyclone season.
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