Monthly climate statement for October 2017
The Department of Science, Information Technology and Innovation (DSITI) monitors sea-surface temperature (SST) anomalies in key regions of the Pacific Ocean over autumn, winter and spring and provides objective outlooks for summer (November to March) rainfall on this basis. The Science Division of DSITI considers that the probability of exceeding median rainfall for the coming summer (November to March) is currently near-normal for much of Queensland. Read more (PDF, 184K, last updated 10:16AM, 12 October 2017)*
Rainfall in Queensland over spring and summer is strongly influenced by the El Niño-Southern Oscillation (ENSO) — a coupled atmospheric and oceanic phenomenon which is strongly persistent at seasonal timescales. The key oceanic indicator of ENSO is the SST anomaly in the Niño 3.4 region of the Pacific Ocean. The September SST anomaly was -0.5°C, a monthly value which is on the threshold between ENSO-neutral and La Niña classifications. The Southern Oscillation Index (SOI) is the key atmospheric indicator of ENSO. The average value of the SOI over July to September was +5.4, a three-month value which likewise is on the threshold between ENSO-neutral and La Niña classifications.
DSITI provides outlooks for summer rainfall based on an objective analysis of Pacific Ocean SSTs. This analysis currently indicates a near-normal probability of exceeding median rainfall for the coming summer across much of Queensland. DSITI will provide a final outlook for summer rainfall in November which will take into account any changes in the Pacific Ocean SST pattern.
When interpreting seasonal climate outlook information it should be appreciated that seasonal climate outlooks are probabilistic, rather than deterministic, in nature. For example, if an outlook is described as having a 70 per cent probability of exceeding median rainfall, then there will also be a 30 per cent probability of below median rainfall. Furthermore, in cases where there are high probabilities for a specified outcome, it does not mean that a less probable event will not occur.
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