NEUTRAL conditions persist in both the Pacific Basin and Indian Ocean and all international models continue to favour these conditions persisting for at least the rest of the year.
In the Pacific, the Southern Oscillation Index has stabilised a little in the past few weeks and has been consistently about +3 to +6 and at the end of August the 30-day running mean was about +4 after averaging +6 in July.
These values are towards the La Nina end of the neutral range and will help ensure the likelihood of an unexpected El Nino development remains very low.
The south-eastern trades and tropical ocean cloud cover are also well within the neutral range.
The same applies in the Indian Ocean with the Indian Ocean Dipole just fractionally positive in the past few weeks.
Although in the neutral range, a slightly positive result can reduce spring rainfall potential in the south east of Australia although its effects are likely to be minimal this year.
As indicated previous, long term neutral patterns reduce the confidence level of any long term predictions.
In past years when such patterns have dominated for long periods, rainfall in NSW has generally been a little down on normal but the occurrence of occasional rain events has been slightly more frequent.
However, these have often effected only limited areas but where they do occur, they have the potential to boost local rainfall to at least average.
Also the occasional severe storm has been more frequent, especially in late spring and early summer so the potential for hail in storms at these times is slightly higher than in a normal year, but not significantly so.
In addition, the chances of late season frost is a little higher than normal in the first half of spring, despite the fact that daytime maximum temperatures will be warmer than average.
Above average temperatures are likely over summer and well into 2018 but the long term 2018 outlook remains unclear with neutral conditions likely to last well into next year.
