Seasonal Climate Outlook - December 2011 to February 2012
On 22 November, the Bureau of Meteorology released the rainfall outlook for the period December 2011 to February 2012. It shows: 1) a wetter season is likely across eastern NSW; and 2) a drier season is somewhat more likely across most of Tasmania, southern Victoria and south-eastern SA. A persistently warm Indian Ocean is the main driver behind this outlook, although it is also consistent with the La Niña in the Pacific Ocean. Over southern Victoria, the chances of below normal rainfall range from 60 to 65%; and over northern Victoria, the chances of a drier or wetter summer are roughly equal. The next outlook report is due on 20 December 2011.
The Bureau’s latest ENSO Wrap-Up reports that La Niña conditions have strengthened slightly over the past fortnight, with some, but not all, atmospheric and oceanic indicators intensifying. Forecast models reviewed by the Bureau suggest the event is likely to peak towards the end of 2011, and continue into early 2012. It is considered unlikely that the current La Niña will be as strong as the La Niña event of 2010-11. ENSO indicators are consistent with La Niña conditions. Over the past fortnight, ocean temperatures have remained cooler than normal for this time of year despite a slight warming of waters below the surface in the central to western Pacific. Trade winds and cloudiness in the tropical Pacific also point to a La Niña event. The next update is expected by 7 December 2011.