Seasonal Climate Outlook - February 2011 to April 2011
While the Bureau of Meteorology’s rainfall outlook for February to April 2011 favours drier than average conditions over southern and eastern Australia, other indicators show wetter conditions persisting through autumn.
The Bureau’s ENSO Wrap-Up, issued on 19 January, reports that strong La Niña conditions remain firmly in place in the tropical Pacific. The 2010/11 event has been one of the strongest La Niña events on record. Long range model outlooks suggest the La Niña event may persist into the southern hemisphere autumn.
All ENSO indicators continue to exceed La Niña thresholds. Sub-surface temperatures in the eastern and central Pacific remain cooler than the long-term average, and the Southern Oscillation Index (SOI) remains strongly positive. The trade winds remain stronger than average and cloudiness near the date-line remains suppressed.
La Niña periods are generally associated with above normal rainfall during winter, spring and summer particularly across eastern and northern Australia. Tropical cyclone occurrence in northern Australia is typically higher than normal during the cyclone season (Nov-April). The Indian Ocean Dipole (IOD) is currently neutral. The influence of the IOD on rainfall in Australia between December and April is typically limited.