Issue Notes

ENSO status: Neutral (El Nino Alert)

Sea surface temperatures (SSTs) have been at El Nino level for weeks but atmospheric indicators across the equatorial Pacific Ocean remain within neutral values.

The Nino3.4 index lingered between 0.8 and 0.9 during November, within El Nino threshold. On the other hand, the Southern Oscillation Index (SOI) recorded a value of -0.1 in November.

Current consensus suggest El Nino threshold related to SSTs will continue until February. The risk of an El Nino developing during summer remains at about 80%, according to the International Research Institute for Climate and Society. The Australian Bureau of Meteorology continues to maintain an El Nino Alert. In the long run, seven out of eight international seasonal models maintain El Nino thresholds through to February with five maintaining it until April.

Seas across northern Australia have experienced some significant warming over the past week, in particular the Gulf of Carpentaria and the northern Coral Sea. On the other hand, SSTs have cooled down over the North West Shelf, southern Coral and Tasman Seas. Cooler SSTs off the northwest have led to a positive Indian Ocean Dipole (IOD) phase through spring but this is now finally decaying.

Climate forecasts continue to favour below average rainfall for northern Australia through the summer period. Throughout most of the southeast and east of the Great Dividing Range, however, odds are neutral due to the elevated SSTs off the coasts.

Despite last monthâ??s heavy rainfall across eastern NSW, the 11-month average rainfall continues to show serious-to-severe rainfall deficiencies in NSW (west of the ranges) Victoria, parts of southern Qld and the eastern half of South Australia.

In the longer term, a drier than average outlook is favoured for the continent during autumn. Higher humidity levels towards the end of summer/early autumn, however, could bring some good rainfall east of the Great Dividing Range in short but intense period with enhanced thunderstorm activity, leading to flash floods.

Despite El Nino increasing the risk of a late onset of a North Australian Monsoon (NAM), the recent tropical cyclone activity across our tropics and a possible MJO traversing the Maritime Continent in the coming week could bring an early start to the NAM. Depending on its strength, duration and geographical location it could bring some relief to dry areas across northern Australia.