Issue Notes

ENSO status: Neutral (El Nino Watch)

Sea surface temperatures (SST's) have dropped below El Nino threshold across the equatorial Pacific Ocean during the past few weeks, prompting the Bureau of Meteorology to decrease their level of advice to a Watch.

The Nino3.4 index lingered between 0.5 and 0.3 during January, neutral but remaining within the El Nino side of neutral. On the other hand, the Southern Oscillation Index (SOI) recorded a value of -0.6 in January. Moreover, sub-surface equatorial water temperatures have cooled down significantly in the east but remain warmer than average in the west. There are early indications an oceanic Kelvin Wave could transport some of the western pacific heat back to the east in coming months.

Current consensus suggest the marginal El Nino thresholds (related to SST's) will continue through the early autumn, with only two out of eight international seasonal models maintaining El Nino thresholds through to at least April.

Around Australia, SST's off Western Australia and the Northern Territory have experienced significant cooling in recent months with temperatures one to two degrees cooler than average. Further east, the Coral Sea and the Gulf of Carpentaria continue to see average-to-below average SST's. The most significant feature of the SST's is the oceanic heatwave which is bringing extreme temperatures to the Tasman Sea as well as surrounding Tasmania.

Climate forecasts favour below average rainfall for northern and western Australia through the end of the summer and early autumn. Below average rainfall is also favoured for the remainder of summer over southern South Australia. On the contrary, average to above average rainfall is likely for the remainder of summer and spring along the eastern states, particularly in New South Wales, Victoria and Tasmania. SST's are very much warmer than average over the Tasman Sea increasing the humidity in the region. This higher humidity levels can bring some good rainfall, especially east of the Great Dividing Range in short but intense periods with enhanced thunderstorm activity, leading to flash floods.

The 10-month average rainfall shows serious-to-severe rainfall deficiencies in northern and western parts of NSW, Victoriaâ??s Gippsland, most of southern Qld and the eastern half of South Australia.