Seasonal Climate Outlook January - March 2009
The rainfall outlook for the period January to March was released by the Bureau of Meteorology on 17 December 2008.
The outlook shows no strong bias towards either wetter or drier conditions. The outlook indicates that the chances of exceeding the median rainfall across Victoria are between 45% and 50% 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 (issued on 23 December 2008) reveals that the equatorial Pacific Ocean has continued to cool. This raises the possibility of indicators reaching La Niña levels if the cooling persists. In the atmosphere, Trade Winds have been stronger than normal for some months across the western half of the basin. Cloudiness is suppressed along much of the central and eastern equatorial Pacific. The SOI remains strongly positive, with an approximate 30-day value of +13 as of 21st of December.
Given current conditions and recent trends, the development of a La Niña during the southern summer cannot be ruled out. However, for the first quarter of 2009, the majority of climate models forecast neutral conditions, but with a cooler than normal equatorial Pacific. The Indian Ocean Dipole is now neutral and expected to remain neutral through the rest of summer.