Drier Outlook For Australia, As Indian Ocean's Stored Heat May Combine With El Nino
Prospects are firming that the latest El Nino event may leave much of Australia drier, with conditions in the Indian Ocean possibly reinforcing those in the Pacific, the Bureau of Meteorology says. In its fortnightly update, the bureau said the El Nino continues to strengthen in the tropical Pacific and sea-surface temperatures are likely to remain "well above" the threshold for such events into the southern hemisphere spring.
"We've had some weak El Ninos in recent years but this one looks like being quite significant," David Jones, head of climate prediction services at the bureau, said, adding that the event looks likely to exceed the intensity of the previous three in 2002, 2006 and 2009.
El Ninos form when the equatorial central and eastern Pacific waters warm relative to western regions, resulting in a weakening or reversal in the easterly trade winds. Rainfall tends to shift eastwards away from Australia and south-east Asia, while countries on the Pacific's eastern fringe tend to have wet years.
Whether Australia has a particularly dry period during an El Nino year depends largely on how the Indian Ocean counters or reinforces the Pacific influence. The latest readings suggest the Indian Ocean off north-western Australia is starting to cool, a shift that would tend to reduce moisture flows over the continent.
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http://www.smh.com.au/environment/weather/australias-outlook-turns-drier-as-indian-ocean-set-to-reinforce-el-nino-20150526-gha1br.html