Australia is on track to experience its first neutral summer since 2005-06, as earlier signs of a predicted El Nino continue to wane.
The latest ENSO report from the Bureau of Meteorology indicates that the chance of an El Niño developing in late 2012 has reduced over the past two months as the Pacific Ocean has cooled to neutral levels.
The report said sea surface temperatures in the Indian Ocean off the west Australian coast during October were the equal second warmest on record.
Warm Indian Ocean temperatures off Western Australia in spring are associated with increased summer rainfall across far eastern parts of the continent, as well as large parts of Western Australia.
“If El Niño-Southern Oscillation (ENSO) indicators remain neutral as expected, this would be the first neutral summer since 2005-06,” the Bureau said.
The latest three-monthly rainfall outlook issued by the Bureau overnight suggests that a wetter-than-average season is likely from December to February for parts of Western Australia, southeast Queensland and eastern New South Wales.
The outlook points to a drier than normal season is more likely for the northern half of Queensland.
“The outlook is mostly the result of warmer than normal temperatures in the Indian Ocean, warmer than normal waters in the Pacific Ocean had less of an impact,” the bureau said.
The map (click below to view in large format) suggests that the chances of receiving above median rainfall during the December to February period are between 60 and 75pc over western and southern WA, southeast Queensland and eastern NSW).
Such odds mean that for every ten years with similar ocean patterns to those currently observed, about six or seven years would be expected to be wetter than average over these areas, while about three or four years would be drier.
In contrast, the chances of receiving above normal rainfall are between 20 and 40pc over most of the northern half of Queensland. In other words, the chances of below normal rainfall range from 60 to 80pc.