Seasonal Climate Outlook February - April 2009
The rainfall outlook for the period February to April was released by the Bureau of Meteorology on 22 January 2009.
The outlook shows no strong bias towards either wetter or drier conditions for Victoria. The outlook indicates that the chances of exceeding the median rainfall across Victoria are between 55% and 60% across most of the state, with between 50% and 55% in the far east. This means that the chances of being wetter than normal are about the same as the chances of being drier.
The Bureau’s latest ENSO Wrap-Up was issued on 14 January 2009. The central and eastern equatorial Pacific Ocean cooled further during December. This brings the Pacific Ocean into line with atmospheric indicators, a number of which have been approaching La Niña levels since October 2008. These include enhanced trade winds, suppressed cloudiness near the dateline, and a strongly positive SOI, which currently (January 12) has an approximate 30-day value of +14.
However, most current model outlooks, and a build-up of warmer sub-surface water in the western equatorial Pacific, suggest that the cooler conditions in the Pacific may not persist beyond summer 2009. The most likely scenario is for the central and eastern Pacific to warm over the coming months and hence remain neutral. The Indian Ocean Dipole is now neutral and is expected to remain neutral throughout the rest of the southern summer.