El Niño persists Dave McRae, Qld Climate Change Centre of Excellence, 12/01/10.
According to the latest ENSO Wrap-up from the Bureau of Meteorology www.bom.gov.au/climate/enso sea surface temperatures throughout the central Pacific remain well above El Niño thresholds with values more than 2Â°C above normal along the equator. Sub-surface sea temperatures (to a depth of 300 plus metres) throughout the central and eastern tropical Pacific also remain warmer than normal with temperatures as much as 4 degrees C above normal.
Climate models suggest that tropical Pacific Ocean temperatures may have peaked for this event, though are likely to remain above El Niño thresholds until autumn. This is not unusual as El Niño events tend to run autumn to autumn.
Negative SOI values (below minus 5) are normally associated with El Niño events. Typically during an El Niño event, there is a lower chance of getting above median rainfall during winter, spring and early summer throughout southern and inland eastern Australia as has been the case over the last 9 to 12 months. The poor start to the northern wet season and the occurrence of spring heatwaves are also both typical impacts for an El Niño event. However, the influence of El Niño events on Australian rainfall typically declines by mid to late summer.
At this stage the majority of the international models surveyed forecast sea surface temperatures to remain above El Niño threshold levels throughout summer. None of the surveyed climate models are forecasting any potential return of La Niña like conditions. Given that El Niño events (and La Niña's) tend to persist from autumn to autumn, this is not a surprise.
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