Seasonal Climate Outlook - December 2010 to February 2011
The Bureau of Meteorology released its rainfall outlook for December 2010 to February 2011 on 23 November. The outlook for south-eastern Australia favours wetter than average conditions for north-eastern New South Wales, and drier than average conditions for South Australia and western Victoria. The odds for the rest of Victoria are considered neutral, with above average rainfall as likely as below average rainfall. The pattern of seasonal rainfall odds across Australia is a result of warm conditions in the Indian Ocean, as well as cool conditions in the equatorial Pacific Ocean associated with the current La Niña.
The Bureau’s latest ENSO Wrap-Up, issued on 24 November reports that, despite a slight weakening of La Niña conditions, the La Niña event remains firm in the tropical Pacific Ocean. Long range model outlooks continue to suggest the La Niña event will persist into the first quarter of 2011.
All ENSO indicators continue to exceed La Niña thresholds. Despite slight warming over the past two weeks, the tropical Pacific Ocean remains significantly cooler than the long-term average for this time of year. The Southern Oscillation Index (SOI) has fallen, but remains strongly positive. Trade winds have strengthened and are stronger than average, and cloudiness over the central tropical Pacific remains suppressed.
The negative Indian Ocean Dipole (IOD) event is following its normal cycle of decay for this time of year, and the IOD is currently neutral. La Niña periods are generally associated with above normal rainfall during the second half of the year across large parts of Australia, most notably eastern and northern regions.