POSSIBLY the most significant climatic indicator at the moment in the Australian region is the Indian Ocean Dipole.
There has been increased awareness in recent years about the importance of the sea surface temperature patterns in the Indian ocean and their effect on the rainfall in the south east of Australia in the winter half of the year - from about May to November.
For the past four to five months, the pattern of sea surface temperatures in the Indian Ocean has resulted in the positive IOD, being above the long held threshold of +0.4, with warmer than average sea surface temperatures in the central and western tropical Indian Ocean, south of the Persian Gulf and average to cooler than average waters in the eastern tropical Indian Ocean, to the northwest of Australia and south of Indonesia.
In early September the IOD was starting to fall a little but was still close to +1.0 and most international models forecast it to stay above +0.4 until early 2020.
This pattern reduces the potential for upper and mid-level moisture to stream across continental Australia from the north west and has been responsible for the lack of rainfall from the so-called north west cloud bands that has been mostly absent in pre-frontal weather situations in recent months.
Another cause of a positive IOD is increased temperatures in the southern and central parts of the continent, leading to increased fire dangers in spring and early summer.
There is little to indicate any significant change to the current set-up, at least until the end of the year. The one slightly optimistic sign, however, is that there is now no real chance of an El Nino developing in the Pacific, which would have exacerbated the dry situation in eastern Australia.
The tropical Pacific Ocean remains in a neutral El Nino-Southern Oscillation phase. Atmospheric and oceanic indicators are also close to normal, reflecting neutral tropical Pacific cloud and rainfall patterns.
Most climate models indicate the tropical Pacific is likely to remain ENSO-neutral for the rest of 2019 and into early 2020, and in many past neutral years, the occasional one-off event has been a provider of localised useful rain at times.
This is an increasing chance into the second half of spring, but it appears that even if a few one-off events do occur, they will be insufficient to overcome the deficiencies established by close to two years of drought.
So, below average rainfall and warmer than average temperatures appear to remain as the favoured scenario for much of eastern Australia for the rest of 2019.