Updated Today 11/9/2012 from the BOM
Pacific near El Niño thresholds; positive Indian Ocean Dipole
Issued on Tuesday 11 September | Product Code IDCKGEWWOO
Tropical Pacific Ocean sea surface temperatures remain at values close to El Niño thresholds. Other ENSO indicators such as the trade winds and tropical cloud patterns show patterns more typical of neutral conditions. The Southern Oscillation Index (SOI) is also presently within neutral values.
Regardless of whether El Niño thresholds are reached, the tropical Pacific remains warmer than average. This, combined with other influences on Australian climate such as cooler than normal waters to the north of the Australian continent and the patterns of cloud and ocean temperatures in the Indian Ocean, tends to favour below average spring rainfall over much of Australia.
Climate models surveyed by the Bureau of Meteorology suggest sea surface temperatures in the tropical Pacific Ocean will maintain values close to El Niño thresholds before returning to more neutral values towards the end of 2012 or early 2013.
The Indian Ocean Dipole (IOD) is currently positive, with values of the IOD index consistently above positive thresholds for the past 7 weeks. Outlooks from the Bureau’s climate model indicate the IOD will likely remain positive throughout the remainder of spring. A positive IOD is usually associated with decreased spring rainfall over parts of southern, central and northern Australia.
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