Seasonal Climate Outlook - May 2011 to July 2011
The Bureau of Meteorology released its rainfall outlook for May to July 2011 on 19 April. The outlook reports moderate odds favouring a drier than normal season for the majority of Victoria.
The Bureau’s latest ENSO Wrap-Up, issued on 27 April, reports that the La Niña event continues to decline in the Pacific Ocean, although atmospheric indicators remain strong. All available climate models indicate further weakening of the La Niña in the coming months, with neutral conditions forecast for the southern hemisphere winter.
Ocean temperatures continue to approach their normal values for this time of year, consistent with observations during past La Niña breakdowns. However, the atmospheric indicators of ENSO remain at odds with the trends in ocean temperatures. The Southern Oscillation Index (SOI) value is only slightly below the highest April monthly value on record, and has remained consistently high throughout the event. Cloudiness near the date-line remains below normal while trade winds continue to be stronger than normal. These atmospheric indicators are expected to return to neutral over the coming months in response to changes in the ocean.
Typically, the influence of the Indian Ocean Dipole (IOD) on rainfall in Australia is limited during the months from December through to April.