The Bureau of Meteorology (BoM) has confirmed the strong La Niña weather event which has contributed to record breaking spring rainfall over eastern and southern parts of the country is slowly weakening. While La Niña is still in place in the Pacific Ocean, BoM forecasts that Pacific Ocean temperatures will warm towards neutral over the coming weeks with changes in the atmosphere also tipped to head towards the neutral phase. BoM urged caution, saying La Niña is not the only driver of wet weather; with the Southern Annular Mode (SAM) currently set up at present to deliver wet summer conditions in parts of the country. A positive SAM increases the chance of above-average rainfall for eastern NSW, eastern Victoria and north-eastern Tasmania.
Meanwhile, the BoM’s latest long-range forecats to February to April is for large parts of the country to have a close to equal chance of above or below median rainfall. Above median rainfall is likely (greater than 60% chance) for southern coastal parts of NSW, far eastern Victoria and parts of eastern Tasmania. Below median rainfall is likely (greater than 60% chance) for parts of WA, central Australia and almost all of SA, with areas of SA and WA having an increased risk of unusually dry conditions (bottom 20% of historical totals).