ALTHOUGH the patterns across the Pacific basin indicate we are still in a neutral situation, the gradual trend towards an El Nino set up continues.
There is now about a 70 per cent chance that at least a weak El Nino will become established by the middle of late spring.
During an El Nino event, rainfall in eastern Australian is typically below average during spring and daytime temperatures are also usually warmer than average for southern Australia whereas a neutral El Nino–Southern Oscillation (ENSO) phase has little effect on Australian rainfall patterns.
However, in around one third of such events, there is minimal impact on rainfall, so the outlook is not all doom and gloom.
Another feature of developing El Nino events can be the encouragement of occasional, one off rain events and these are more likely to occur when sea surface temperatures (SSTs) are above normal, as they are at the moment but not often with full El Nino events.
So the prognosis for these occasional events remains on track.
The most likely scenario for NSW weather in the coming months is for rainfall to be generally below average with extended periods of stability, but with one or two brief but significant events effecting parts of the state.
Where these rain events occur, they have the potential to boost monthly rainfalls to near normal.
That said, many parts of the state, especially in the north and central districts in late winter and early spring and in the central and southern districts in late spring and early summer will record rainfall and moisture deficiencies persist.
Temperatures have been variable recently, but into spring, warmer than normal weather is expected to dominate.
This trend will persist into summer.
The other feature of a developing El Nino is to increase slightly the chance of severe weather events and severe storms in late spring and early summer especially.