Welcome to the Climate and Water Outlook for summer 2016 to 2017.
After a very wet September, rainfall returned to closer to average in October and mostly
below average in November, helping to get the harvest underway.
But spring also brought damaging storms, wind, frost and bushfires.
For summer, the outlook suggests drier and warmer conditions than usual.
But first, let's look at recent conditions.
September was very wet for much of eastern and northern Australia, due to warm waters
to our northwest.
October saw rainfall return to closer to average, as the link between warm waters in the tropics
and rain in eastern Australia weakened.
November rainfall has been below average in many areas, providing good conditions for harvesting.
However, severe storms in western Victoria early in the month damaged grain and fruit crops.
Likewise, crops were also damaged in the Western Australian Wheat Belt due to an unusually
high number of frosty nights in September.
Vegetation growth from a wet winter, coupled with the onset of drier conditions, has contributed
to bushfires in Western Australia, Queensland, New South Wales and Victoria.
The southern fire season is now underway.
Soil moisture remains well above average in eastern and northern Australia, but the strong
vegetation growth, spring’s warmth and recent lower rainfall have started to dry the soil.
Water storages in the southeast look much better going into summer than at this time
last year, thanks to above-average rainfall over winter and spring.
High streamflows and surface water have benefited many ecosystems: Fish and waterbirds are breeding,
and native vegetation on flood plains is regenerating.
However, such conditions can also increase mosquito populations.
So what's driving Australia’s climate right now?
The Indian Ocean Dipole is back to neutral after a record-strong event.
But tropical waters remain warmer than average to our northwest, potentially boosting rainfall
and cyclone development in that area.
In the eastern Pacific, ocean temperatures have not reached La Niña levels …
So our ENSO Outlook remains at La Niña WATCH.
A brief but weak La Niña remains possible in the coming months.
Models indicate more westerly winds than usual over southern Australia during December.
This is typical of a negative Southern Annular Mode (known as SAM).
In summer, this prevents northern wet season rains reaching the south, and can raise the
risk of heatwaves.
So what's the rainfall outlook for summer?
Below-average rainfall is likely over parts of the east, with above-average rainfall expected
in northwest Western Australia.
Outlook accuracy is moderate at this time of year.
December is likely to be drier than average for most places.
Combined with warmer temperatures, this may rapidly dry vegetation and increase the risk of bushfires.
Turning to the streamflow forecast for November 2016 to January 2017:
Median-to-high streamflows are expected at most forecast locations, as water from winter
and spring rains continues to flow through the landscape.
Accuracy for our streamflow forecasts is high at this time of year.
In terms of temperatures: Days and nights are likely to be warmer than
average in the north and east, and cooler than average in Tasmania and southwest WA.
Accuracy for this outlook is moderate at this time of year.
So in summary: Rainfall is likely to be below-average over
parts of eastern Australia, particularly in December.
Higher-than-average streamflows are likely to continue into early summer.
Temperatures are expected to be warmer than average in the east, with an increased risk of heatwaves.
And bushfire potential is also raised.
For more details, go to our website at bom.gov.au/climate/ahead.
You can also get updates via Facebook, Twitter and the new BOM Weather App.
Our next video will be released on Thursday 15 December.
For the Bureau of Meteorology, I’m Robyn Duell.